doi:10.1007/s00376-015-5148-x

Barcikowska M., F. Feser, and H. von Storch, 2012: Usability of best track data in climate statistics in the western North Pacific. Mon. Wea. Rev., 140, 2818- 2830.10.1175/MWR-D-11-00175.1

fb8e334d95c0d6e401202c1e399c93f6

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2012MWRv..140.2818B

http://adsabs.harvard.edu/abs/2012MWRv..140.2818BAbstract Tropical cyclone (TC) activity for the last three decades shows strong discrepancies, deduced from different best track datasets (BTD) for the western North Pacific (WNP). This study analyzes the reliability of BTDs in deriving climate statistics for the WNP. Therefore, TC lifetime, operational parameters [current intensity (CI) number], and tracks are compared (for TCs identified concurrently) in BTD provided by the Joint Typhoon Warning Center (JTWC), the Japan Meteorological Agency (JMA), and the China Meteorological Administration (CMA). The differences between the BTD are caused by varying algorithms used in weather services to estimate TC intensity. Available methods for minimizing these discrepancies are not sufficient. Only if intensity categories 2-5 are considered as a whole, do trends for annually accumulated TC days show a similar behavior. The reasons for remaining discrepancies point to extensive and not regular usage of supplementary sources in JTWC. These are added to improve the accuracy of TC intensity and center position estimates. Track and CI differences among BTDs coincide with a strong increase in the number of intense TC days in JTWC. These differences are very strong in the period of intensive improvement of spatiotemporal satellite coverage (1987-99). Scatterometer-based data used as a reference show that for the tropical storm phase JMA provides more reliable TC intensities than JTWC. Comparisons with aircraft observations indicate that not only homogeneity, but also a harmonization and refinement of operational rules controlling intensity estimations, should be implemented in all agencies providing BTD.

Bosart L. F., J. A. Bartlo, 1991: Tropical storm formation in a baroclinic environment. Mon. Wea. Rev., 119, 1979- 2013.10.1175/1520-0493(1991)119<1979:TSFIAB>2.0.CO;2

59c6cd1587f0e7dff1463b81774227d9

http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2F0887617791900325

http://www.sciencedirect.com/science/article/pii/0887617791900325Abstract An analysis is presented of the large-scale conditions associated with the initial development of Tropical Storm Diana (September 1984) in a baroclinic environment. Ordinary extratropical wave cyclogenesis began along an old frontal boundary east of Florida after 0000 UTC 7 September and culminated in tropical cyclogenesis 48 h later. Water-vapor satellite imagery showed that the initial cyclogenesis and incipient tropical storm formation was nearly indistinguishable from a classical midlatitude development. Cyclogenesis occurred in three stages. A large-scale cold trough and associated frontal system crossed the Atlantic coast, while a small potential vorticity maximum aloft fractured off the main trough and stalled over central Florida in the first stage. As the main trough sheared off eastward, cyclogenesis began along the southwestern end of the stalled frontal zone east of Florida. Anticyclogenesis to the north in the wake of the shearing trough allowed a surge of cooler and drier air to flow southeastward behind the front toward the developing cyclone. Combined surface sensible and latent heat fluxes in excess of 1000 W m 2 acted on this inflowing air, producing a warming and moistening of the boundary layer. Cyclogenesis intensified during the second stage in response to positive potential vorticity advection aloft ahead of the slow moving cutoff cyclone over Florida. The maximum ascent was centered near 300 mb, indicative of deep tropospheric ascent and cyclonic vorticity production by convergence in midlevels. The ascent occurred along uplifted isentropic surfaces that defined the cold dome associated with the potential vorticity anomaly aloft. Low-level potential vorticity was generated in the vicinity of the developing storm below the presumed level of maximum diabatic heating. The third stage of cyclogenesis was marked by the collapse of the mid- and upper-tropospheric cold dome and associated potential vorticity maximum and the simultaneous initiation of a warm thickness ridge. This occurred in response to the widespread outbreak of convection at the southwestern end of the baroclinic zone, where the greatest destabilization occurred for air parcels subject to prolonged surface sensible and latent heat fluxes in the persistent northeasterly flow. Upright ascent associated with the convection short-circuited the slantwise ascent ahead of the advancing potential vorticity anomaly, triggering warming aloft and the eventual disappearance of the potential vorticity anomaly and associated cold dome. Tropical storm development and intensification occurred as the low-level vorticity center (potential vorticity maximum) moved northwestward to become situated beneath the midlevel vortex embedded within a local 500-200 mb warm thickness anomaly. The interaction of the upper- and lower-level potential vorticity anomalies appeared to be important in the initial strengthening of the tropical cyclone. The interpretation is equivalent to earlier energetic arguments by Riehl and others that tropical cyclogenesis is often preceded by the collapse of a nearby cold dome.

Bosart L. F., C. S. Velden, W. E. Bracken, J. Molinari, and P. G. Black, 2000: Environmental influences on the rapid intensification of Hurricane Opal (1995) over the Gulf of Mexico. Mon. Wea. Rev., 128, 322- 352.7dab06a1-5d0e-4161-966a-7756c011e324

d34fbb9f60d1afb5e54101a6224fea17

http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D2000MWRv..128..322B%26db_key%3DPHY%26link_type%3DABSTRACT

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Bracken W. E., L. F. Bosart, 2000: The role of synoptic-scale flow during tropical cyclogenesis over the North Atlantic Ocean. Mon. Wea. Rev., 128, 353- 376.528fa6e743c192c8c2d4126b29384e19

http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D2000MWRv..128..353B%26db_key%3DPHY%26link_type%3DABSTRACT

/s?wd=paperuri%3A%28956e16849a71030a39ddd9923cc5e108%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D2000MWRv..128..353B%26db_key%3DPHY%26link_type%3DABSTRACT&ie=utf-8

Challa M., R. L. Pfeffer, 1980: Effects of eddy fluxes of angular momentum on model hurricane development. J. Atmos. Sci., 37, 1603- 1618.53b2a083cc7fb6df918c0558c361abce

http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D1980JAtS...37.1603C%26db_key%3DPHY%26link_type%3DABSTRACT

/s?wd=paperuri%3A%28fefa00f62b39c8554b9c0c8486b80de5%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D1980JAtS...37.1603C%26db_key%3DPHY%26link_type%3DABSTRACT&ie=utf-8

Chan J. C. L., F. M. F. Ko, and Y. M. Lei, 2002: Relationship between potential vorticity tendency and tropical cyclone motion. J. Atmos. Sci., 59, 1317- 1336.10.1175/1520-0469(2002)0592.0.CO;2

d431359d4947806c68767ecde91be3f9

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F249609690_Relationship_between_Potential_Vorticity_Tendency_and_Tropical_Cyclone_Motion

http://www.researchgate.net/publication/249609690_Relationship_between_Potential_Vorticity_Tendency_and_Tropical_Cyclone_MotionAbstract This paper proposes a consistent conceptual framework to explain tropical cyclone (TC) motion based on the concept of potential vorticity tendency (PVT) and to verify this framework based on analyses of different observational datasets. The framework suggests that a TC is likely to move toward an area of maximum wavenumber-1 (WN1) PVT, which is mainly contributed by the corresponding WN1 components of potential vorticity (PV) advection and diabatic heating (DH). The PV advection process consists of advection of symmetric PV by the asymmetric flow [AASPV, which includes, but is not limited to, the environmental -teering flow- and the beta-induced circulation (the so-called ventilation flow)] and the advection of asymmetric PV by the symmetric flow (SAAPV). The asymmetric PV includes any asymmetry in the TC circulation, the beta gyres and contributions from asymmetric convective heating. The modification of PVT by the DH process depends on the vertical gradient of convective heating and the coupling between horizontal gradient of convective heating and vertical wind shear. In steady (i.e., without much change in direction or speed) TC motion, the PV advection processes are generally dominant while the contribution by DH is usually less significant. However, the latter process becomes important for irregular TC motion. Changes in TC motion are then not only caused by those in steering, but can also be induced by variations in the other processes. Composites of the Met Office operational analyses associated with TCs that had similar and relatively steady motion are first made to verify the contribution by the advection terms. In all motion categories examined, while the magnitude of the AASPV term is found to be generally dominant, its maximum is not downstream of the TC motion. The SAAPV term also contributes to the overall PV advection. The sum of these two terms gives a maximum at a location that generally aligns with the direction of TC motion. The contribution of the DH process to PVT, and hence TC motion, is then examined using satellite-derived temperatures from high-resolution geosynchronous satellite images for individual TCs. It is found that DH appears to be important especially for slow-moving TCs. Track oscillations as well as irregular track changes may be explained by changes in the convection pattern that lead to variations in the location of maximum WN1 DH. The entire PVT concept is further investigated using analyses from the Tropical Cyclone Motion Experiment TCM-90 for individual TCs with different track types. The results are consistent with those from the composites (for straight-moving cases) as well as from the satellite image analyses (for the irregular-moving case). Further, in the recurving case, the locations of the maximum in the advection terms rotate ahead of the turning motion of the TC, which is consistent with previous studies of TC motion based on the concept of absolute vorticity conservation. An integration of all these observational analyses generally verifies the validity of the proposed conceptual framework, which appears to explain most types of TC motion.

Chen X. M., Y. Q. Wang, and K. Zhao, 2015: Synoptic flow patterns and large-scale characteristics associated with rapidly intensifying tropical cyclones in the South China Sea. Mon. Wea. Rev., 143, 64- 87.c3f826136ac826f24957c87004eeb500

http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D2015MWRv..143...64C%26db_key%3DPHY%26link_type%3DABSTRACT

/s?wd=paperuri%3A%28ad06de5e23891d983cbd7f70ab8bc557%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D2015MWRv..143...64C%26db_key%3DPHY%26link_type%3DABSTRACT&ie=utf-8

Choi Y., K. -S. Yun, K. -J. Ha, K. -Y. Kim, S. -J. Yoon, and J. C. L. Chan, 2013: Effects of asymmetric SST distribution on straight-moving Typhoon Ewiniar (2006) and recurving Typhoon Maemi (2003). Mon. Wea. Rev., 141, 3950- 3967.10.1175/MWR-D-12-00207.1

b2ee224e5beec3bd0b07c58c0569bf6e

http%3A%2F%2Fwww.dbpia.co.kr%2FArticle%2F2932861

http://www.dbpia.co.kr/Article/2932861The effects of asymmetric sea surface temperature (SST) distribution on the tropical cyclone (TC) motion around East Asia have been examined using the Weather Research and Forecasting Model for the straight-moving Typhoon Ewiniar (2006) and recurving Typhoon Maemi (2003). The SST-TC motion relationships associated with the two different TCs and the physical mechanism of recurvature are investigated in the context of the potential vorticity tendency framework. A zonally asymmetric SST distribution alters the TC translating direction and speed, which is ascribable to the interaction between a TC and the environmental current associated with asymmetric SST forcing. A north-south SST gradient has an insignificant role in the TC motion. It is noted that the straight-moving (i.e., northward moving) TC deflects toward the region of warmer SST when SST is zonally asymmetric. A contribution of the horizontal advection including asymmetric flow induced by asymmetric forcing is dominant for the deflection. The recurving TC reveals northeastward acceleration and deceleration after the recurvature point in the western warming (WW) and eastern warming (EW) experiments, respectively. When it comes to a strong southerly vertical wind shear under the recurvature condition, diabatic heating can be a significant physical process associated with the downward motion over the region of upshear right. The enhanced (reduced) southwesterly flow effectively produces the acceleration (deceleration) of northeastward movement in WW (EW) after recurvature.

Dee, D. P., Coauthors, 2011: The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quart. J. Roy. Meteor. Soc., 137, 553- 597.10.1002/qj.828

b8698c40-b145-4364-9b39-4e603f942b9f

5e49541e9e977f77d4b4487298c60f84

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.828%2Fpdf

refpaperuri:(d4649bb38c91f047e85ec096d8587b99)

http://onlinelibrary.wiley.com/doi/10.1002/qj.828/pdfABSTRACT ERA-Interim is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). The ERA-Interim project was conducted in part to prepare for a new atmospheric reanalysis to replace ERA-40, which will extend back to the early part of the twentieth century. This article describes the forecast model, data assimilation method, and input datasets used to produce ERA-Interim, and discusses the performance of the system. Special emphasis is placed on various difficulties encountered in the production of ERA-40, including the representation of the hydrological cycle, the quality of the stratospheric circulation, and the consistency in time of the reanalysed fields. We provide evidence for substantial improvements in each of these aspects. We also identify areas where further work is needed and describe opportunities and objectives for future reanalysis projects at ECMWF. Copyright 2011 Royal Meteorological Society

DeMaria M., J. -J. Baik, and J. Kaplan, 1993: Upper-level eddy angular momentum fluxes and tropical cyclone intensity change. J. Atmos. Sci., 50, 1133- 1147.10.1175/1520-0469(1993)050<1133:ULEAMF>2.0.CO;2

5d74b511b94b4a6dc0440fccfb5369d3

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1993JAtS...50.1133D

http://adsabs.harvard.edu/abs/1993JAtS...50.1133DAbstract The eddy flux convergence of relative angular momentum (EFC) at 200 mb was calculated for the named tropical cyclones during the 1989-1991 Atlantic hurricane seasons (371 synoptic times). A period of enhanced EFC within 1500 km of the storm center occurred about every 5 days due to the interaction with upper-level troughs in the midlatitude westerlies or upper-level, cold lows in low latitudes. Twenty-six of the 32 storms had at least one period of enhanced EFC. In about one-third of the cases, the storm intensified just after the period of enhanced EFC. In most of the cases in which the storm did not intensify the vertical shear increased, the storm moved over cold water, or the storm became extratropical just after the period of enhanced EFC. A statistically significant relationship (at the 95% level) was found between the EFC within 600 km of the storm center and the intensity change during the next 48 h. However, this relationship could only be determined using a multiple regression technique that also accounted for the effects of vertical shear and sea surface temperature variations. The EFC was also examined for the ten storms from the 1989-1991 sample that had the largest intensification rates. Six of the ten periods of rapid intensification were associated with enhanced EFC. In the remaining four cases the storms were intensifying rapidly in a low shear environment without any obvious interaction with upper-level troughs.

DeMaria M., J. A. Knaff, and C. Sampson, 2007: Evaluation of long-term trends in tropical cyclone intensity forecasts. Meteor. Atmos. Phys., 97, 19- 28.10.1007/s00703-006-0241-4

ffae03528c8bd1c2a7ad5eed49371785

http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2Fs00703-006-0241-4

http://link.springer.com/article/10.1007/s00703-006-0241-4The National Hurricane Center and Joint Typhoon Warning Center operational tropical cyclone intensity forecasts for the three major northern hemisphere tropical cyclone basins (Atlantic, eastern North Pacific, and western North Pacific) for the past two decades are examined for long-term trends. Results show that there has been some marginal improvement in the mean absolute error at 24 and 4865h for the Atlantic and at 7265h for the east and west Pacific. A new metric that measures the percent variance of the observed intensity changes that is reduced by the forecast (variance reduction, VR) is defined to help account for inter-annual variability in forecast difficulty. Results show that there have been significant improvements in the VR of the official forecasts in the Atlantic, and some marginal improvement in the other two basins. The VR of the intensity guidance models was also examined. The improvement in the VR is due to the implementation of advanced statistical intensity prediction models and the operational version of the GFDL hurricane model in the mid-1990s. The skill of the operational intensity forecasts for the 5-year period ending in 2005 was determined by comparing the errors to those from simple statistical models with input from climatology and persistence. The intensity forecasts had significant skill out to 9665h in the Atlantic and out to 7265h in the east and west Pacific. The intensity forecasts are also compared to the operational track forecasts. The skill was comparable at 1265h, but the track forecasts were 2 to 5 times more skillful by 7265h. The track and intensity forecast error trends for the two-decade period were also compared. Results showed that the percentage track forecast improvement was almost an order of magnitude larger than that for intensity, indicating that intensity forecasting still has much room for improvement.

Eliassen A., 1952: Slow thermally or frictionally controlled meridional circulation in a circular vortex. Astrophysica Norvegica, 5, 19- 60.f27826da93643e0d72297822d994585e

http%3A%2F%2Fwww.ams.org%2Fmathscinet-getitem%3Fmr%3D49032

http://www.ams.org/mathscinet-getitem?mr=49032ASTROPHYSICA NORVEGICA VOL.V NO.2 SLOW THERMALLY OR FRICTIONALLY CONTROLLED MERIDIONAL CIRCULATION IN A CIRCULAR VORTEX BY ARNT ELIASSEN (MANUSCRIPT RECEIVED DECEMBER 8, 1950.) A bstract: A quasi-static theory of meridional motion in

Elsberry R. L., G. J. Holland , H. Gerrish, M. DeMaria, C. P. Guard, and K. A. Emanuel, 1992: Is there any hope for tropical cyclone intensity prediction? panel discussion. Bull. Amer. Meteor. Soc., 73, 264- 275.

Emanuel K. A., 1986: An air-sea interaction theory for tropical cyclones. Part I: Steady-state maintenance. J. Atmos. Sci., 43, 585- 605.504439cc64b4832397ce434098772cbd

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1986JAtS...43..585E

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Emanuel K. A., 2000: A statistical analysis of tropical cyclone intensity. Mon. Wea. Rev., 128, 1139- 1152.0078e780-8b7d-4829-898e-20c641364f92

ba25f1faf217004b2d8c85472946fb75

http%3A%2F%2Fcat.inist.fr%2F%3FaModele%3DafficheN%26cpsidt%3D1349927

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http://cat.inist.fr/?aModele=afficheN&cpsidt=1349927

Erickson C. O., 1967: Some aspects of the development of Hurricane Dorothy. Mon. Wea. Rev., 95, 121- 130.10.1175/1520-0493(1967)095<0121:SAOTDO>2.3.CO;2

0dfd85e418bcf8ab5d4b8063f5ccf9aa

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1967MWRv...95..121E

http://adsabs.harvard.edu/abs/1967MWRv...95..121EHurricane Dorothy, July 1966, possessed both extratropical and tropical features. A number of factors contributed to storm development, including a well-defined pre-existing disturbance, high-level advection of vorticity and kinetic energy, baroclinicity of both the extratropical and tropical-storm types, and a moderate degree of latent instability. 1.

Fitzpatrick P. J., 1997: Understanding and forecasting tropical cyclone intensity change with the typhoon intensity prediction scheme (TIPS). Wea.Forecasting, 12, 826- 846.10.1175/1520-0434(1997)0122.0.CO;2

2ab676c1a54da402028a0129cc7a515a

http%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F80010101621

http://ci.nii.ac.jp/naid/80010101621Abstract A multiple regression scheme with tropical cyclone intensity change as the dependent variable has been developed. The new scheme is titled the Typhoon Intensity Prediction Scheme (TIPS) and is similar to one used operationally at the National Hurricane Center. However, TIPS contains two major differences: it is developed for the western North Pacific Ocean, and utilizes digitized satellite data; the first time such satellite information has been combined with other predictors in a tropical cyclone multiple regression scheme. It is shown that the satellite data contains vital information that distinguishes between fast and slow developing tropical cyclones. The importance of other predictors (such as wind shear, persistence, climatology, and an empirical formula dependent on sea surface temperature) to intensity change are also clarified in the statistical analysis. A normalization technique reveals threshold values useful to forecasters. It is shown that TIPS may be competitive with the Joint Typhoon Warning Center in forecasting tropical cyclone intensity change.

Fitzpatrick P. J., J. A. Knaff, C. W. Land sea, and S. V. Finley, 1995: Documentation of a systematic bias in the aviation model's forecast of the Atlantic tropical upper-tropospheric trough: Implications for tropical cyclone forecasting. Wea.Forecasting, 10, 433- 446.10.1175/1520-0434(1995)0102.0.CO;2

50bd51fc-1588-4de6-b881-e5b86215b1dd

6c5902e805b7c5de4eae8c9661308126

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1995WtFor..10..433F

refpaperuri:(ce4bb628f7e90cd02f70d69137958ca4)

http://adsabs.harvard.edu/abs/1995WtFor..10..433FAbstract This study uncovers what appears to be a systematic bias in the National Meteorological Center's aviation (AVN) model at 200 mb over the Caribbean Sea. In general, the 48-h forecast in the vicinity of the Tropical Upper Tropospheric Trough (TUTT) underpredicts the magnitude of the westerly 200-mb winds on the order of 5-10 m s 611 . This unrealistic weakening of the TUTT and associated cold lows by the AVN results in erroneous values of the vertical (850-200 mb) wind shear. These systematic errors are in the same order of magnitude as the minimum shear threshold for tropical cyclone genesis and development. Thus, 48-h tropical cyclone formation and intensity forecasts based upon the AVN model are often incorrect in the vicinity of the TUTT. Knowing the correct future upper-wind regime is also crucial for track forecasting of more intense tropical cyclones, especially in cases of recurvature. It is shown that simple persistence or climatology of the 200-mb winds south of a TUTT axis is superior to the AVN model's 48-h forecast. Until this bias in the AVN is successfully removed, the tropical cyclone forecaster for the Atlantic basin should be aware of this systematic error and make subjective changes in his/her forecasts. For 200-mb west winds greater than or equal to 10 m s 611 , forecasts based on persistence are best, while for west winds less than 10 m s 611 , half climatology and half persistence is the preferable predictor. If the TUTT is weak such that 200-mb easterly winds occur, climatology tends to be the best predictor as it nudges the forecast back to a normal westerly wind regime.

Hanley D. E., 2002: The evolution of a hurricane-trough interaction from a satellite perspective. Wea.Forecasting, 17, 916- 926.

Hanley D., J. Molinari, and D. Deyser, 2001: A composite study of the interactions between tropical cyclones and upper-tropospheric troughs. Mon. Wea. Rev., 129, 2570- 2584.10.1175/1520-0493(2001)129<2570:ACSOTI>2.0.CO;2

a9eb7afc6f8d24e4e7f3092e1a53bb6f

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2001MWRv..129.2570H

http://adsabs.harvard.edu/abs/2001MWRv..129.2570HAbstract The objective of this study is to understand how interactions with upper-tropospheric troughs affect the intensity of tropical cyclones. The study includes all named Atlantic tropical cyclones between 1985 and 1996. To minimize other factors affecting intensity change, times when storms are over subcritical sea surface temperatures (≤26°C) or near landfall are removed from the sample. A trough interaction is defined to occur when the eddy momentum flux convergence calculated over a 300–600-km radial range is greater than 10 (m s 611 ) day 611 . The trough interaction cases are separated into four composites: (i) favorable superposition [tropical cyclone intensifies with an upper-tropospheric potential vorticity (PV) maximum within 400 km of the tropical cyclone center], (ii) unfavorable superposition, (iii) favorable distant interaction (upper PV maximum between 400 and 1000 km from the tropical cyclone center), and (iv) unfavorable distant interaction. For comparison,

Holland G.J., R. T. Merrill, 1984: On the dynamics of tropical cyclone structural changes. Quart. J. Roy. Meteor. Soc., 110, 723- 745.10.1002/qj.49711046510

cb9c84aa6ff768eaae5f0e3aa30c199e

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.49711046510%2Fpdf

http://onlinelibrary.wiley.com/doi/10.1002/qj.49711046510/pdfAbstract Tropical cyclone structural change is separated into three modes: intensity, strength and size. The possible physical mechanisms behind these three modes are examined using observations in the Australian/south-west Pacific region and an axisymmetric diagnostic model. We propose that, though dependent on moist convection and other internal processes, the ultimate intensity, strength or size of a cyclone is regulated by interactions with its environment. Possible mechanisms whereby these interactions occur are described.

Hoskins B. J., M. E. McIntyre, and A. W. Robertson, 1985: On the use and significance of isentropic potential vorticity maps. Quart. J. Roy. Meteor. Soc., 111, 877- 946.10.1002/qj.49711147002

7aa4c05ab21b01e1c658764471a056db

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.49711147002%2Fcitedby

http://onlinelibrary.wiley.com/doi/10.1002/qj.49711147002/citedbyAbstract The two main principles underlying the use of isentropic maps of potential vorticity to represent dynamical processes in the atmosphere are reviewed, including the extension of those principles to take the lower boundary condition into account. the first is the familiar Lagrangian conservation principle, for potential vorticity (PV) and potential temperature, which holds approximately when advective processes dominate frictional and diabatic ones. the second is the principle of ‘invertibility’ of the PV distribution, which holds whether or not diabatic and frictional processes are important. the invertibility principle states that if the total mass under each isentropic surface is specified, then a knowledge of the global distribution of PV on each isentropic surface and of potential temperature at the lower boundary (which within certain limitations can be considered to be part of the PV distribution) is sufficient to deduce, diagnostically, all the other dynamical fields, such as winds, temperatures, geopotential heights, static stabilities, and vertical velocities, under a suitable balance condition. the statement that vertical velocities can be deduced is related to the well-known omega equation principle, and depends on having sufficient information about diabatic and frictional processes. Quasi-geostrophic, semigeostrophic, and ‘nonlinear normal mode initialization’ realizations of the balance condition are discussed. an important constraint on the mass-weighted integral of PV over a material volume and on its possible diabatic and frictional change is noted. Some basic examples are given, both from operational weather analyses and from idealized theoretical models, to illustrate the insights that can be gained from this approach and to indicate its relation to classical synoptic and air-mass concepts. Included are discussions of (a) the structure, origin and persistence of cutoff cyclones and blocking anticyclones, (b) the physical mechanisms of Rossby wave propagation, baroclinic instability, and barotropic instability, and (c) the spatially and temporally nonuniform way in which such waves and instabilities may become strongly nonlinear, as in an occluding cyclone or in the formation of an upper air shear line. Connections with principles derived from synoptic experience are indicated, such as the ‘PVA rule’ concerning positive vorticity advection on upper air charts, and the role of disturbances of upper air origin, in combination with low-level warm advection, in triggering latent heat release to produce explosive cyclonic development. In all cases it is found that time sequences of isentropic potential vorticity and surface potential temperature charts—which succinctly summarize the combined effects of vorticity advection, thermal advection, and vertical motion without requiring explicit knowledge of the vertical motion field—lead to a very clear and complete picture of the dynamics. This picture is remarkably simple in many cases of real meteorological interest. It involves, in principle, no sacrifices in quantitative accuracy beyond what is inherent in the concept of balance, as used for instance in the initialization of numerical weather forecasts.

Kimball S. K., J. L. Evans, 2002: Idealized numerical simulations of hurricane-trough interaction. Mon. Wea. Rev., 130, 2210- 2227.10.1175/1520-0493(2002)130<2210:INSOHT>2.0.CO;2

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http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2002MWRv..130.2210K

refpaperuri:(399772e88b41436a3e21b1ed03d7792a)

http://adsabs.harvard.edu/abs/2002MWRv..130.2210KA three-dimensional, nonhydrostatic, fine-resolution model, with explicitly resolved convective processes, is used to investigate the evolution of (a) a hurricane in two sheared flows, and (b) a hurricane interacting with four different upper-level lows. The negative impact of vertical shear on hurricane intensification is confirmed. The hurricanes display asymmetries that are most pronounced in higher shear flow. In both shear cases, the hurricane asymmetries seem to be related to a single upper-tropospheric outflow jet forcing convective activity below its right entrance region. Weak subsidence is confined to only part of the eye. Less eye subsidence leads to less inner-core warming, and hence a smaller fall in central surface pressure. A hurricane in zero flow (control) displays subsidence in the entire eye leading to a symmetric storm with a deep, strong warm core temperature anomaly and lower central surface pressure. In the weak shear and control cases, the radius of maximum wind (RMW) contracts as the storms intensifies via the mechanism of symmetric intensification. In the high-shear case the RMW and intensity remain almost steady. When hurricanes interact with troughs, asymmetries are evident in the hurricanes and their RMWs expand as the storms slowly intensify. During the interaction, the troughs are deformed by the hurricane flow. Remnants of the deformed troughs prevent an outflow channel from developing on the eastern side of the hurricanes, hampering storm intensification in three of the four cases. In the fourth case, a strong and shallow trough merges with the hurricane causing a three-dimensional split of the trough, reduction of vertical shear over the vortex, followed by rapid intensification and RMW contraction. This vortex reaches the highest intensity of all four trough-interaction cases and comes close in intensity to the comparable no-trough case.

Leroux M. -D., M. Plu, D. Barbary, F. Roux, and P. Arbogast, 2013: Dynamical and physical processes leading to tropical cyclone intensification under upper-level trough forcing. J. Atmos. Sci., 70, 2547- 2565.10.1175/JAS-D-12-0293.1

453f1c5d4eb8344c691bb0de4ceeedfa

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2013JAtS...70.2547L

http://adsabs.harvard.edu/abs/2013JAtS...70.2547LAbstract The rapid intensification of Tropical Cyclone (TC) Dora (2007, southwest Indian Ocean) under upper-level trough forcing is investigated. TC-搕rough interaction is simulated using a limited-area operational numerical weather prediction model. The interaction between the storm and the trough involves a coupled evolution of vertical wind shear and binary vortex interaction in the horizontal and vertical dimensions. The three-dimensional potential vorticity structure associated with the trough undergoes strong deformation as it approaches the storm. Potential vorticity (PV) is advected toward the tropical cyclone core over a thick layer from 200 to 500 hPa while the TC upper-level flow turns cyclonic from the continuous import of angular momentum. It is found that vortex intensification first occurs inside the eyewall and results from PV superposition in the thick aforementioned layer. The main pathway to further storm intensification is associated with secondary eyewall formation triggered by external forcing. Eddy angular momentum convergence and eddy PV fluxes are responsible for spinning up an outer eyewall over the entire troposphere, while spindown is observed within the primary eyewall. The 8-km-resolution model is able to reproduce the main features of the eyewall replacement cycle observed for TC Dora. The outer eyewall intensifies further through mean vertical advection under dynamically forced upward motion. The processes are illustrated and quantified using various diagnostics.

Lewis B. M., D. P. Jorgensen, 1978: Study of the dissipation of Hurricane Gertrude (1974). Mon. Wea. Rev., 106, 1288- 1306.10.1175/1520-0493(1978)1062.0.CO;2

fa0b46153527fca7da14ee3bce1efc38

http%3A%2F%2Fjournals.ametsoc.org%2Fdoi%2Fabs%2F10.1175%2F1520-0493%281978%29106%3C1288%253ASOTDOH%3E2.0.CO%253B2

http://journals.ametsoc.org/doi/abs/10.1175/1520-0493(1978)106<1288%3ASOTDOH>2.0.CO%3B2Abstract Meteorological events in the upper and lower troposphere in Hurricane Gertrude and vicinity are examined for causal effects related to the sudden dissipation of Hurricane Gertrude. Mesoscale and synoptic-scale meteorological observations reveal that the hurricane rapidly decreased in intensity as it overtook a westward propagating upper tropospheric trough. Quantized radar observations are presented, which show the marked decrease in storm-generated precipitation which occurred as Gertrude approached the vicinity of this trough. This study indicates that the dissipation of Gertrude resulted from large vertical wind shear and upper level synoptic-scale convergence with accompanying subsidence in the upper troposphere in the vicinity of the storm. The marked decrease in convective activity and storm organization occurred in spite of favorable sea surface temperatures, favorable lower troposphere stability, and convergence of air toward the storm center in the boundary layer. This study reveals the amount of control that upper atmospheric motion has on storm development.

Li Y., L. S. Chen, and X. T. Lei, 2006: Numerical study on impacts of upper-level westerly trough on the extratropical transition process of Typhoon Winnie (1997). Acta Meteorologica Sinica, 64, 552- 563. (in Chinese)10.11676/qxxb2006.054

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http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-QXXB200605001.htm

refpaperuri:(4e177a1cd720451246653172b5158fdc)

http://en.cnki.com.cn/Article_en/CJFDTOTAL-QXXB200605001.htm

Martin J. D., W. M. Gray, 1993: Tropical cyclone observation and forecasting with and without aircraft reconnaissance. Wea.Forecasting, 8, 519- 532.10.1175/1520-0434(1993)0082.0.CO;2

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http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1993WtFor...8..519M

http://adsabs.harvard.edu/abs/1993WtFor...8..519MAbstract The contributions of aircraft reconnaissance to the accuracy of tropical cyclone center positioning, motion, and intensity determinations are examined, along with their impact on the accuracy of track and intensity forecasting. The analyses concentrate on differences in cyclone position and intensity diagnosis, as well as track forecasting during periods when aircraft measurements were made versus times when aircraft data were not available. Northwest Pacific data for the period 1979-86, which contain over 200 tropical cyclone cases with approximately 5000 center fix positions, were used for the analyses. Aircraft versus no-aircraft situations are examined with respect to the class of satellite data that were available and for day versus night measurements. Differences in positioning and intensity estimates made from simultaneous independent satellite observations are also examined. Results show that satellite analysts operating independently frequently obtain large differences in their estimates of tropical cyclone positions, as well as their intensity estimates. Aircraft reconnaissance of cyclone position and intensity, as were flown in the western Pacific, does not appear to improve track forecasts beyond 24 h, nor does it affect the current 12-h motion vector estimate. Other areas of tropical cyclone warning services, including estimates of current position and intensity as well as short-term estimates of motion, especially for recurvature forecasts, appear to be improved by aircraft data.

McTaggart-Cowan R., L. F. Bosart, C. A. Davis, E. H. Atallah, J. R. Gyakum, and K. A. Emanuel, 2006: Analysis of Hurricane Catarina (2004). Mon. Wea. Rev., 134, 3029- 3053.10.1175/MWR3330.1

c5c3f391490b08eab13143aa7fef873a

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2006MWRv..134.3029M

http://adsabs.harvard.edu/abs/2006MWRv..134.3029MAbstract The development of Hurricane Catarina over the western South Atlantic Ocean in March 2004 marks the first time that the existence of a hurricane has been confirmed by analysis and satellite imagery in the South Atlantic basin. The storm undergoes a complex life cycle, beginning as an extratropical precursor that moves east-southeastward off the Brazilian coast and toward the midlatitudes. Its eastward progress is halted and the system is steered back westward toward the Brazilian coast as it encounters a strengthening dipole-blocking structure east of the South American continent. Entering the large region of weak vertical shear that characterizes this blocking pattern, Catarina begins a tropical transition process over anomalously cool 25C ocean waters above which an elevated potential intensity is supported by the cold upper-level air associated with the trough component of the block. As the convective outflow from the developing tropical system reinforces the ridge component of the dipole block, the storm is accelerated westward toward the Santa Catarina province of Brazil and makes landfall there as a nominal category-1 hurricane, causing extensive damage with its heavy rains and strong winds. The complex evolution of the system is analyzed using a suite of diagnostic tools, and a conceptual model of the tropical transition and steering processes in the presence of a dipole block is developed. Once the essential properties of the upper-level flow are established, an analog study is undertaken to investigate lower-atmospheric responses to similar blocking regimes. Persistent dipole-blocking structures are found to be rare east of South America; however, the evolution of systems occurring during these periods is shown to be complex and to exhibit various subtropical development modes.

Merrill R. T., 1988a: Characteristics of the upper-tropospheric environmental flow around hurricanes. J. Atmos. Sci., 45, 1665- 1677.10.1175/1520-0469(1988)045<1665:COTUTE>2.0.CO;2

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http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1988JAtS...45.1665M

refpaperuri:(91a63ea20b6dbb605da08d56e9465f5f)

http://adsabs.harvard.edu/abs/1988JAtS...45.1665MAbstract The upper-tropospheric flow out to a radius of 2000 km around Atlantic hurricanes is described using rotated coordinate composite analysis of the NOAA National Hurricane Center operational wind set. The rotated coordinate methodology, designed to preserve some of the asymmetry of hurricane outflow during compositing, is described in detail. A rotated coordinate composite of all hurricanes from a five-year period is used to study the general properties of the hurricane outflow layer. Coordinate rotation improves the representation of the outflow jet and the associated extrema of radial and tangential wind, but tends to obscure the geographically persistent features of the upper-tropospheric environment such as the midlatitude westerlies. The amplitude of the asymmetric radial wind is twice that of the symmetric, while the amplitudes of tangential winds are equivalent. A comparison of geographic and rotated coordinate composites indicates that both the outflow jet and the midlatitude westerlies are important structures for the import of angular momentum into the hurricane by horizontal eddy fluxes. Separate composites of eight characteristic outflow patterns are also presented. Pattern variability arises from the juxtaposition of the hurricane circulation with surrounding synoptic features.

Merrill R. T., 1988b: Environmental influences on hurricane intensification. J. Atmos. Sci., 45, 1678- 1687.10.1175/1520-0469(1988)045<1678:EIOHI>2.0.CO;2

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http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1985PhDT.......145M

refpaperuri:(cfbb1863f626dcb1bbfa497d0759d344)

http://adsabs.harvard.edu/abs/1985PhDT.......145MAbstract Although driven by internal processes, hurricanes are also regulated by conditions in their oceanic and atmospheric surroundings. Sea surface temperature determines an upper bound on the intensity of hurricanes, but most never reach this potential, apparently because of adverse atmospheric conditions. Winds measured by satellite cloud tracking, commercial aircraft, and rawinsondes are composited using a rotated coordinate system designed to preserve the asymmetries in the upper-tropospheric environment. Composites of upper-tropospheric environmental flows for intensifying and nonintensifying hurricanes for a five-year period are compared. Nonintensifying composites indicate stronger mean environmental flow relative to the hurricane motion, unidirectional flow over and near the hurricane center, and slightly weaker radial outflow and/or more pronounced anticyclonic flow surrounding the center in the upper troposphere.

Molinari J., D. Vollaro, 1989: External influences on hurricane intensity. Part I: Outflow layer eddy angular momentum fluxes. J. Atmos. Sci., 46, 1093- 1104.10.1175/1520-0469(1989)046<1093:EIOHIP>2.0.CO;2

78a04d902688950150f2150bed6e3f99

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1989JAtS...46.1093M

http://adsabs.harvard.edu/abs/1989JAtS...46.1093MABSTRACT Outflow layer winds were objectively analyzed every 12 h for 6 days during the life cycle of Hurricane Elena (1985). A high correlation was found between angular momentum fluxes by azimuthal eddies at large radii and central pressure changes in the storm 27-33 h later. Momentum flux by eddies exceeded that by the azimuthal mean outside the 800 km radius, while vortex spinup by the eddies reached instantaneous magnitudes as large as 25 m s1/day. Outflow maxima and minima repeatedly appeared more than 1000 km from the hurricane center and tracked inward with time. The results provide evidence of significant environmental control on the behavior of the storm.After reaching hurricane strength, Elena experienced a major secondary intensification associated with a large inward cyclonic eddy momentum flux produced by the passage of a middle latitude trough north of the hurricane. An outflow maximum appeared radially inside of the eddy momentum source, consistent with balanced vortex theory, and tracked inward with the eddy momentum source during the following 24 h. When the outflow maximum reached the storm core, an extended period of rapid pressure fails followed. It is speculated that these pressure falls represented a response to midlevel spinup forced by the outflow layer momentum sourcers.Although environmental forcing dominated the later stages of Elena, the rapid initial intensification of the storm as it moved from land to water appeared to be a precursor to subsequent environmental interactions. The enhanced anticyclonic outflow from this initial deepening reduced the outflow-layer inertial stability, allowing a more radially extended region for external forcing. The secondary intensification of Elena is thus viewed as a cooperative interaction between mesoscale events at the hurricane core and synoptic-scale features in the upper tropospheric environment.

Molinari J., D. Vollaro, 1990: External influences on hurricane intensity. Part II: Vertical structure and response of the hurricane vortex. J. Atmos. Sci., 47, 1902- 1918.874c3974c5314547ea852d87ce74a7fd

http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D1990JAtS...47.1902M%26db_key%3DPHY%26link_type%3DABSTRACT

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Molinari J., D. Vollaro, 1993: Environmental controls on eye wall cycles and intensity change in Hurricane Allen (1980). Tropical Cyclone Disasters, J. Lighthill et al., Eds., Peking University Press, 328- 337.

Molinari J., D. Vollaro, and F. Robasky, 1992: Use of ECMWF operational analyses for studies of the tropical cyclone environment.Meteor. Atmos. Phys., 47, 127- 144.10.1007/BF01025613

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http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2FBF01025613

http://link.springer.com/article/10.1007/BF01025613This study examined ECMWF operational analyses of the outflow layer of two tropical cyclones (Allen, 1980; Elena, 1985) during their passage across the Atlantic and Caribbean. Wind fields and related derived quantities were compared to those from objective analyses of specialized data sets. Errors in center position and storm motion from the ECMWF analyses were also evaluated. Analyses of wind and angular momentum flux in 1985, subsequent to upgrading of the operational model, were superior to those from 1980. High-resolution, uninitialized analyses from 1985, however, provided no advantages over lower resolution, initialized analyses for the same time period. For all ECMWF analyses, azimuthally averaged (mean) tangential velocity, and thus mean vorticity, were well represented. Mean radial velocity and mean divergence were poorly represented. Problems with the latter arose primarily due to underestimation of outflow, especially in the 1980 analyses. Azimuthaleddy fluxes of angular momentum in the ECMWF analyses quantitatively differed from but qualitatively resembled, the control analyses. Vorticity maxima at 850 mb in the operational analyses most accurately defined the center position of the storms, with a mean error less than or equal to one grid point. In contrast, surface pressure minima failed to provide reliable estimates. Over open ocean and at early stages of storms, analysis quality was uneven, with occasional large position errors and widely varying locations of vorticity maxima in the vertical. Nevertheless, in regions surrounded by even a few rawinsondes, such as the Caribbean or Gulf of Mexico, ECMWF analyses contained sufficient information to allow individual case studies of the tropical cyclone environment. In the same regions, estimates of the eddy flux convergence of angular momentum were found to be accurate enough to aid in operational hurricane intensity prediction. Enhancements in resolution and model initialization at ECMWF since 1985 should further improve operational analyses of the tropical cyclone environment.

Molinari J., S. Skubis, and D. Vollaro, 1995: External influences on hurricane intensity. Part III: Potential vorticity structure. J. Atmos. Sci., 52, 3593- 3606.7486cafd60267f67330b6821ce743463

http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D1995JAtS...52.3593M%26db_key%3DPHY%26link_type%3DABSTRACT

/s?wd=paperuri%3A%28f580b04ab8db2a76fe26f576ec346219%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D1995JAtS...52.3593M%26db_key%3DPHY%26link_type%3DABSTRACT&ie=utf-8

Molinari J., S. Skubis, D. Vollaro, F. Alsheimer, and H. E. Willoughby, 1998: Potential vorticity analysis of tropical cyclone intensification. J. Atmos. Sci., 55, 2632- 2644.10.1175/1520-0469(1998)0552.0.CO;2

4190970

c56474187be9be03c7bb411cbb3b61a9

http%3A%2F%2Flink.springer.com%2F10.1023%2FA%3A1010178327293

http://med.wanfangdata.com.cn/Paper/Detail/PeriodicalPaper_PM4190970Presents a study which examined the tropical storm Danny in 1985, during its marginal interaction with an upper-tropospheric positive potential vorticity (PV) anomaly. What the intensification of the storm was attributed to; Examination of the behavior of a weaker storm interacting with a smaller-scale upper PV anomaly; Assessment of the roles of vertical wind shear and diabatic heating in the observed evolution.

Molinari J., P. Dodge, D. Vollaro, and K. L. Corbosiero, 2006: Mesoscale aspects of the downshear reformation of a tropical cyclone. J. Atmos. Sci., 63, 341- 354.10.1175/JAS3591.1

62fcad46af0d43cf3effc0c4ac124a7d

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2006JAtS...63..341M

http://adsabs.harvard.edu/abs/2006JAtS...63..341MAbstract The downshear reformation of Tropical Storm Gabrielle (2001) was investigated using radar reflectivity and lightning data that were nearly continuous in time, as well as frequent aircraft reconnaissance flights. Initially the storm was a marginal tropical storm in an environment with strong 850-200-hPa vertical wind shear of 12-13 m s 1 and an approaching upper tropospheric trough. Both the observed outflow and an adiabatic balance model calculation showed that the radial-vertical circulation increased with time as the trough approached. Convection was highly asymmetric, with almost all radar return located in one quadrant left of downshear in the storm. Reconnaissance data show that an intense mesovortex formed downshear of the original center. This vortex was located just south of, rather than within, a strong downshear-left lightning outbreak, consistent with tilting of the horizontal vorticity associated with the vertical wind shear. The downshear mesovortex contained a 972-hPa minimum central pressure, 20 hPa lower than minimum pressure in the original vortex just 3 h earlier. The mesovortex became the new center of the storm, but weakened somewhat prior to landfall. It is argued that dry air carried around the storm from the region of upshear subsidence, as well as the direct effects of the shear, prevented the reformed vortex from continuing to intensify. Despite the subsequent weakening of the reformed center, it reached land with greater intensity than the original center. It is argued that this intensification process was set into motion by the vertical wind shear in the presence of an environment with upward motion forced by the upper tropospheric trough. In addition, the new center formed much closer to the coast and made landfall much earlier than predicted. Such vertical-shear-induced intensity and track fluctuations are important to understand, especially in storms approaching the coast.

Montgomery M. T., R. K. Smith, 2014: Paradigms for tropical cyclone intensification. Australian Meteorological and Oceanographic Journal, 64, 37- 66.10.1175/JAS3988.1

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http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F268416770_Paradigms_for_tropical-cyclone_intensification

refpaperuri:(67cb0efd98d6e794c18c1de253e61053)

http://www.researchgate.net/publication/268416770_Paradigms_for_tropical-cyclone_intensificationABSTRACT We review four paradigms of tropical-cyclone intensification that have emerged over the past five decades, discussing the relationship between them and highlighting their positive aspects and limitations. A major focus is on a new paradigm articulated in a series of recent papers by ourselves and colleagues. Unlike the three previous paradigms, all of which assumed axial symmetry, the new one recognizes the importance of rotating deep convection, which possesses local buoyancy relative to the azimuthally-averaged virtual temperature of the warm-cored vortex. This convection comes under increasing rotational control as the vortex intensifies. It exhibits also a degree of randomness that has implications for the predictability of local asymmetric features of the developing vortex. While surface moisture fluxes are required for intensification, the postulated 'evaporation-wind' feedback process that forms the basis of an earlier paradigm is not. The details of the intensification process as well as the structure of the mature vortex are sensitive to the boundary-layer parameterization used in the model. The spin up of the inner-core winds in the new paradigm occurs within the boundary layer and is associated with the convergence of absolute angular momentum in this layer, where absolute angular momentum is not materially conserved. This spin up is coupled with that of the winds above the boundary layer through boundary-layer dynamics. Balanced and unbalanced contributions to the intensification process are discussed. An application of the new paradigm is given to help describe and understand a simulated intensification process in a realistic numerical weather prediction model.

Pfeffer R. L., M. Challa, 1981: A numerical study of the role of eddy fluxes of momentum in the development of Atlantic hurricanes. J. Atmos. Sci., 38, 2393- 2398.10.1175/1520-0469(1981)038<2393:ANSOTR>2.0.CO;2

69da6699b99391c1e915b1a8d6a17565

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1981JAtS...38.2393P

http://adsabs.harvard.edu/abs/1981JAtS...38.2393PAbstract The results of numerical integrations of Sundqvist's (1970) symmetric model for hurricane development modified to include parameterized large-scale eddy fluxes of momentum are presented. The initial wind and moisture distributions, and the prescribed eddy fluxes of momentum, were taken from atmospheric observations of Atlantic developing (prehurricane) and non-developing tropical disturbances as composited by McBride (1981a,b) and McBride and Zehr (1981). For the purposes of the present study, the data for individual stages in the evolution of developing and non-developing disturbances were combined to form a single composite developing hurricane and a single composite non-developing disturbance. The data reveal the presence of intense, well organized inward eddy fluxes of momentum in developing Atlantic hurricanes and weak, poorly organized fluxes in non-developing disturbances. In the developing disturbances, the eddy fluxes of momentum are organized such that they act as a forcing function for driving the radial circulation, drawing moist air in toward the center of the vortex in the lower troposphere and pumping drier air outward aloft, thereby providing fuel for the explosive growth of the hurricane. In order to test the efficacy of this mechanism, and of Ekman suction and cooperative instability, numerical integrations were performed using the data for the composite developing hurricane, with and without the observed eddy fluxes of momentum, and for the composite non-developing disturbance with the observed eddy fluxes corresponding to this disturbance. Without eddy flux forcing, the prehurricane developing vortex fails to intensify into a hurricane, even after 20 days of integration. With the observed eddy fluxes of momentum, the same initial vortex intensifies rapidly, reaching hurricane strength within 4 days. Moreover, because of the weak and diffuse pattern of the eddy fluxes of momentum in non-developing tropical disturbances, the initial vortex characterizing these disturbances also fails to develop into a hurricane. The kinetic energy budgets corresponding to the integrations with the composite developing and non-developing disturbances are presented as a function of time. The calculations reveal that, during the early stages of development of the model hurricane, the conversion ( E k ) from eddy kinetic energy to the kinetic energy of the mean hurricane circulation is larger than the conversion ( C A ) from potential to kinetic energy. The eddy process is, therefore, directly responsible for the early growth of the model hurricane. This is followed by an explosive increase in the rate of conversion from potential to kinetic energy and in the rate of kinetic energy dissipation ( F ). During the latter period, C A and F become almost an order of magnitude greater than the peak attained earlier by E k , and the kinetic energy tendency reaches its peak. Without the eddy momentum flux forcing, no such explosive growth takes place. The results of these integrations provide evidence that properly organized large-scale eddy fluxes of momentum may be an essential ingredient id the development of Atlantic hurricanes.

Qian Y. K., C. X. Liang, Q. Q. Liang, L. X. Lin, and Z. J. Yuan, 2011: On the forced tangentially-averaged radial-vertical circulation within vortices. Part II: The transformation of Tropical Storm Haima (2004). Adv. Atmos. Sci.,28, 1143-1158, doi: 10.1007/s00376-010-0060-x.10.1007/s00376-010-0060-x

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http%3A%2F%2Fwww.cnki.com.cn%2FArticle%2FCJFDTotal-DQJZ201105016.htm

refpaperuri:(e3e9e0394ae54517c84d1e65fdbc925c)

http://d.wanfangdata.com.cn/Periodical_dqkxjz-e201105015.aspxA real case study for the transformation of Tropical Storm (TS) Haima (2004) into an extratropical cyclone (EC) is carried out numerically since,after landfall,Haima (2004) (as an EC) brought severe weather to a large area (from the south to the north) in China during 13-16 September 2004.With the linear diagnostic model (derived in a previous study) for the tangentially-averaged radial-vertical circulation within vortices moving on the spherical Earth,Haima's (2004) life cycle is reconstructed noticeably well.Therefore,the major contributor could be identified confidently for Haima's (2004) extratropical transition based on the diagnostic model outputs.The quantitative comparison shows that up to a 90％ contribution to the innerregion updraft and a 55％ contribution to the upper-layer outflow come from latent heating during Haima's (2004) TS stage.Up to a 90％ contribution to the inner-region updraft and nearly a 100％ contribution to the upper-layer outflow come from the upper-layer eddy angular momentum advection (EAMA) during Haima's (2004) EC stage.Representing the asymmetric structure of the storm,the predominantly positive contribution of the upper-layer EAMA to Haima's (2004) transformation is closely associated with the Sshaped westerlies in the upper layer with two jets.One jet in the cyclonic-curvature area carries cyclonic angular momentum into the storm,and the other jet in the anticyclonic-curvature area carries anticyclonic angular momentum out of the storm.Consequently,the newly-increased cyclonic tangential wind is deflected by the Coriolis force to the right to form the upper-layer outflow accompanied by the central-area rising motion,leading to Haima's (2004) extratropical transition after its landfall.

Rappin E. D., M. C. Morgan, and G. J. Tripoli, 2011: The impact of outflow environment on tropical cyclone intensification and structure. J. Atmos. Sci., 68, 177- 194.10.1175/2009JAS2970.1

457ebffb834e11309cbd99b2102c797a

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2011JAtS...68..177R

http://adsabs.harvard.edu/abs/2011JAtS...68..177RAbstract In this study, the impacts of regions of weak inertial stability on tropical cyclone intensification and peak strength are examined. It is demonstrated that weak inertial stability in the outflow layer minimizes an energy sink of the tropical cyclone secondary circulation and leads to more rapid intensification to the maximum potential intensity. Using a full-physics, three-dimensional numerical weather prediction model, a symmetric distribution of environmental inertial stability is generated using a variable Coriolis parameter. It is found that the lower the value of the Coriolis parameter, the more rapid the strengthening. The lower-latitude simulation is shown to have a significantly stronger secondary circulation with intense divergent outflow against a comparatively weak environmental resistance. However, the impacts of differences in the gradient wind balance between the different latitudes on the core structure cannot be neglected. A second study is then conducted using an asymmetric inertial stability distribution generated by the presence of a jet stream to the north of the tropical cyclone. The initial intensification is similar, or even perhaps slower, in the presence of the jet as a result of increased vertical wind shear. As the system evolves, convective outflow from the tropical cyclone modifies the jet resulting in weaker shear and more rapid intensification of the tropical cyclone-et couplet. It is argued that the generation of an outflow channel as the tropical cyclone outflow expands into the region of weak inertial stability on the anticyclonic shear side of the jet stream minimizes the energy expenditure of forced subsidence by ventilating all outflow in one long narrow path, allowing radiational cooling to lessen the work of subsidence. Furthermore, it is hypothesized that evolving conditions in the outflow layer modulate the tropical cyclone core structure in such a way that tropical cyclone outflow can access weak inertial stability in the environment.

Rodgers E. B., S. W. Chang, J. Stout, J. Steranka, and J.-J. Shi, 1991: Satellite observations of variations in tropical cyclone convection caused by upper-tropospheric troughs. J. Appl. Meteor., 30, 1163- 1184.10.1175/1520-0450(1991)030<1163:SOOVIT>2.0.CO;2

b2dc2da7cc5f46d70876a6532b82b0b5

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1991JApMe..30.1163R

http://adsabs.harvard.edu/abs/1991JApMe..30.1163RABSTRACT Satellite observations and numerical model results have been used to study the relationship between upper-tropospheric forcing and the oscillation of convection of tropical cyclones Florence (1988) and Irene (1981) during their mature stage over open warm oceans (SST greater than or equal to 26 C). It is suggested that the initiation and maintenance of intense convective outbreaks in tropical cyclones are related to the channeling and strengthening of their outflow by upper-tropospheric troughs. It is possible to enhance the convection in response to the outflow jet-induced import of eddy relative angular momentum and ascending motion associated with the thermally direct circulation. Both Florence and Irene are found to intensify after the onset of these convective episodes. It is also suggested that the cessation in the convection of the two tropical cyclones occurs when the upper-tropospheric troughs move near or over the tropical cyclones, resulting in the weakening of their outflow and the entrainment of dry upper-tropospheric air into their inner core.

Rodgers E. B., W. S. Olson, V. M. Karyampudi, and H. F. Pierce, 1998: Satellite-derived latent heating distribution and environmental influences in Hurricane Opal (1995). Mon. Wea. Rev., 126, 1229- 1247.10.1175/1520-0493(1998)126<1229:SDLHDA>2.0.CO;2

706bf26d0774d5d316d0b49a396f6c59

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1998MWRv..126.1229R

http://adsabs.harvard.edu/abs/1998MWRv..126.1229RAbstract The total (i.e., convective and stratiform) latent heat release (LHR) cycle in the eyewall region of Hurricane Opal (October 1995) has been estimated using observations from the F-10, F-11, and F-13 Defense Meteorological Satellite Program Special Sensor Microwave/Imagers (SSM/Is). This LHR cycle occurred during the hurricane’s rapid intensification and decay stages (3–5 October 1995). The satellite observations revealed that there were at least two major episodes in which a period of elevated total LHR (i.e., convective burst) occurred in the eyewall region. During these convective bursts, Opal’s minimum pressure decreased by 50 mb and the LHR generated by convective processes increased, as greater amounts of latent heating occurred at middle and upper levels. It is hypothesized that the abundant release of latent heat in Opal’s middle- and upper-tropospheric region during these convective burst episodes allowed Opal’s eyewall to become more buoyant, enhanced the generation of kinetic energy and, thereby, rapidly intensified the system. The observations also suggest that Opal’s intensity became more responsive to the convective burst episodes (i.e., shorter time lag between LHR and intensity and greater maximum wind increase) as Opal became more intense. Analyses of SSM/I-retrieved parameters, sea surface temperature observations, and the European Centre for Medium-Range Weather Forecasts (ECMWF) data reveal that the convective rainband (CRB) cycles and sea surface and tropopause temperatures, in addition to large-scale environmental forcing, had a profound influence on Opal’s episodes of convective burst and its subsequent intensity. High sea surface (29.7°C) and low tropopause (192 K) temperatures apparently created a greater potential for Opal’s maximum intensity. Strong horizontal moisture flux convergence within Opal’s outer-core regions (i.e., outside 333-km radius from the center) appeared to help initiate and maintain Opal’s CRBs. These CRBs, in turn, propagated inward to help generate and dissipate the eyewall convective bursts. The first CRB that propagated into Opal’s eyewall region appeared to initiate the first eyewall convective burst. The second CRB propagated to within 111 km of Opal’s center and appeared to dissipate the first CRB, subjecting it to subsidence and the loss of water vapor flux. The ECMWF upper-tropospheric height and wind analyses suggest that Opal interacted with a diffluent trough that initated an outflow channel, and generated high values of upper-tropospheric eddy relative angular momentum flux convergence. The gradient wind adjustment processes associated with Opal’s outflow channel, in turn, may have helped to initiate and maintain the eyewall convective bursts. The ECMWF analyses also suggest that a dry air intrusion within the southwestern quadrant of Opal’s outer-core region, together with strong vertical wind shear, subsequently terminated Opal’s CRB cycle and caused Opal to weaken prior to landfall.

Sawyer J. S., 1956: The vertical circulation at meteorological fronts and its relation to frontogenesis. Proc. Roy. Soc.London, 234A, 346- 362.10.1098/rspa.1956.0039

ce83be86a9d65d1edd66b26f42505e0b

http%3A%2F%2Fwww.jstor.org%2Fstable%2F99840

http://www.jstor.org/stable/99840The first small nematodes to be described, free-living in the seventeenth century and plant-parasitic in the eighteenth, are identifiable only from their peculiar habitats; taxonomy came relatively late in nematology because adequate optical equipment was a prerequisite. In the study of the free-living and the plant-parasitic species, the development of two readily-presented aspects of taxonomy, figure drawing and mensuration ( each showing oscillation between paucity and excess of detail), is traced in the work of five founders, all of whom were living in 1904: Bastian, Butschli, de Man, Cobb and Goodey. Possible future developments in the identification of species and strains, the investigation of host-parasite relationships, and the training of nematologists are briefly discussed.

Shi J. J., S. Chang, and S. Raman, 1997: Interaction between Hurricane Florence (1988) and an upper-tropospheric westerly trough. J. Atmos. Sci., 54, 1231- 1247.10.1175/1520-0469(1997)054<1231:IBHFAA>2.0.CO;2

5ffbaf7dd91833e16fed28e865e1e793

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1997JAtS...54.1231S

http://adsabs.harvard.edu/abs/1997JAtS...54.1231SInvestigates the interaction between Hurricane Florence (1988) and its upper-tropospheric environment. Use of the Naval Research Laboratory limited-area numerical prediction system; Synoptic review of Hurricane Florence; Simulated structure of the outflow layer of Hurricane Florence; Angular momentum transport in the outflow layer; Structure of the outflow layer of tropical cyclones.

Smith R. K., M. T. Montgomery, 2015: Toward clarity on understanding tropical cyclone intensification. J. Atmos. Sci., 72, 3020- 3031.

Sundqvist H., 1970: Numerical simulation of the development of tropical cyclones with a ten-level model. Part I. Tellus, 22, 359- 390.10.1111/j.2153-3490.1970.tb00503.x

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92d42f0d78bd7ae3b514f3d4271cb482

http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F229796795_Numerical_simulation_of_the_development_of_tropical_cyclones_with_a_ten-level_model_Part_II

refpaperuri:(e2150ae6c8fa9be3f3d3000327d321fb)

http://www.researchgate.net/publication/229796795_Numerical_simulation_of_the_development_of_tropical_cyclones_with_a_ten-level_model_Part_II

Titley D. W., R. L. Elsberry, 2000: Large intensity changes in tropical cyclones: A case study of Supertyphoon Flo during TCM-90. Mon. Wea. Rev., 128, 3556- 3573.10.1175/1520-0493(2000)1282.0.CO;2

bd6c9bfdfb24c15ca27a027c49368d01

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2000MWRv..128.3556T

http://adsabs.harvard.edu/abs/2000MWRv..128.3556TA unique dataset, recorded during the rapid intensification and rapid decay of Typhoon Flo, is analyzed to isolate associated environmental conditions and key physical processes. This case occurred during the Tropical Cyclone Motion (TCM-90) field experiment with enhanced observations, especially in the upper troposphere beyond about 300 km. These data have been analyzed with a four-dimensional data assimilation technique and a multiquadric interpolation technique. While both the ocean thermal structure and vertical wind shear are favorable, they do not explain the rapid intensification or the rapid decay. A preconditioning phase is defined in which several interrelated factors combine to create favorable conditions: (i) a cyclonic wind burst occurs at 200 mb, (ii) vertical wind shear between 300 and 150 mb decreases 35%, (iii) the warm core is displaced upward, and (iv) 200-mb outflow becomes larger in the 400-1200-km radial band, while a layer of inflow develops below this outflow. These conditions appear to be forced by eddy flux convergence (EFC) of angular momentum, which appears to act in a catalyst function as proposed by Pfeffer and colleagues, because the EFC then decreases to small values during the rapid intensification stage. Similarly, the outer secondary circulation decreases during this stage, so that the rapid intensification appears to be an internal (within 300 km) adjustment process that is perhaps triggered during the preconditioning phase. Rapid decay occurred over open ocean when the environmental factors of ocean thermal structure, and vertical wind shear, positive 200-mb EFC, and vigorous outflow into the midlatitudes appear favorable. However, the EFC extending down to 500 mb and inducing a second shallower secondary circulation is hypothesized to account for the rapid decay by leading to a less efficient energy conversion.

Willoughby H. E., J. A. Clos, and M. G. Shoreibah, 1982: Concentric eye walls, secondary wind maxima, and the evolution of the hurricane vortex. J. Atmos. Sci., 39, 395- 411.10.1175/1520-0469(1982)039<0395:CEWSWM>2.0.CO;2

eff355712761ec7f54c348d8c6103d43

http%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F110004764353

http://ci.nii.ac.jp/naid/110004764353ABSTRACT Research aircraft observations in recent hurricanes support the model of Shapiro and Willoughby (1982) for the tropical cyclone's response to circularly symmetric, convective heat sources (convective rings). In both nature and the numerical model the tangential wind commonly increases rapidly just inside the radius of maximum wind and decreases inside the eye near the central axis of the vortex. Thus both secondary outer wind maxima and eyewall wind maxima often contract as they intensify. This response is independent of the horizontal spatial scale of the maximum. An outer maximum is frequently observed to constrict about a pre-existing eye and replace it. This chain of events often coincides with a weakening, or at least a pause in intensification, of the vortex as a whole. The concentric eye phenomenon is a common, but by no means universal, feature of tropical cyclones. It is most frequently observed in intense, highly symmetric systems.

Wu C.-C., H.-J. Cheng, 1999: An observational study of environmental influences on the intensity changes of Typhoons Flo (1990) and Gene (1990). Mon. Wea. Rev., 127, 3003- 3031.720b6729412d2f7378b1563aad73636b

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1999mwrv..127.3003w

/s?wd=paperuri%3A%282b82b5dd77ad564d8dc3f94afedaf7cc%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1999mwrv..127.3003w&ie=utf-8

Wu L. G., B. Wang, 2000: A potential vorticity tendency diagnostic approach for tropical cyclone motion. Mon. Wea. Rev., 128, 1899- 1911.10.1175/1520-0493(2000)128<1899:APVTDA>2.0.CO;2

9d964d6e-dc01-4967-8cd5-10c3296c7fff

8174e6234ee758523a9fc39bdd707cc2

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2000MWRv..128.1899W

refpaperuri:(4cfecb8bb923d194011f21f1937a6095)

http://adsabs.harvard.edu/abs/2000MWRv..128.1899WIn order to understand the roles of various physical processes in baroclinic tropical cyclone (TC) motion and the vertical coupling between the upper- and lower-level circulations, a new dynamical framework is advanced. A TC is treated as a positive potential vorticity (PV) anomaly from environmental flows, and its motion is linked to the positive PV tendency. It is shown that a baroclinic TC moves to the region where the azimuthal wavenumber one component of the PV tendency reaches a maximum, but does not necessarily follow the ventilation flow (the asymmetric flow over the TC center). The contributions of individual physical processes to TC motion are equivalent to their contributions to the wavenumber one PV component of the PV tendency. A PV tendency diagnostic approach is described based on this framework. This approach is evaluated with idealized numerical experiments using a realistic hurricane model. The approach is capable of estimating TC propagation with a suitable accuracy and determining fractional contributions of individual physical processes (horizontal and vertical advection, diabatic heating, and friction) to motion. Since the impact of the ventilation flow is also included as a part of the influence of horizontal PV advection, this dynamical framework is more general and particularly useful in understanding the physical mechanisms of baroclinic and diabatic TC motion.

Yu H., H. J. Kwon, 2005: Effect of TC-trough interaction on the intensity change of two typhoons. Wea.Forecasting, 20, 199- 211.10.1175/WAF836.1

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21282aa05d9550558c959d48c62e245c

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2005WtFor..20..199Y

refpaperuri:(9d1191fc73aa0c91d2f17305f83c1c98)

http://adsabs.harvard.edu/abs/2005WtFor..20..199YAbstract Using large-scale analyses, the effect of tropical cyclone–trough interaction on tropical cyclone (TC) intensity change is readdressed by studying the evolution of upper-level eddy flux convergence (EFC) of angular momentum and vertical wind shear for two TCs in the western North Pacific [Typhoons Prapiroon (2000) and Olga (1999)]. Major findings include the following: 1) In spite of decreasing SST, the cyclonic inflow associated with a midlatitude trough should have played an important role in Prapiroon’s intensification to its maximum intensity and the maintenance after recurvature through an increase in EFC. The accompanied large vertical wind shear is concentrated in a shallow layer in the upper troposphere. 2) Although Olga also recurved downstream of a midlatitude trough, its development and maintenance were not strongly influenced by the trough. A TC could maintain itself in an environment with or without upper-level eddy momentum forcing. 3) Both TCs started to decay over cold SST in a large EFC and vertical wind shear environment imposed by the trough. 4) Uncertainty of input adds difficulties in quantitative TC intensity forecasting.

Zeng Z. H., Y. Q. Wang, and C. -C. Wu, 2007: Environmental dynamical control of tropical cyclone intensityn observational study. Mon. Wea. Rev., 135, 38- 59.