doi:10.1007/s00376-015-5092-9

Donner, L. J., Coauthors , 2011: The dynamical core,physical parameterizations, and basic simulation characteristics of the atmospheric component AM3 of the GFDL global coupled model CM3. J. Climate, 24, 3484-3519, doi: 10.1175/2011 JCLI3955.1.625abeb6-c951-4f2b-9979-2a30ddd1605e

0c3f00612575944ce10dfd22aa8048bb

http%3A%2F%2Fwww.osti.gov%2Fscitech%2Fservlets%2Fpurl%2F1117959

refpaperuri:(3cfd733b206c59475a8af1c78a7c55af)

http://www.osti.gov/scitech/servlets/purl/1117959

Griffies, S. M., Coauthors , 2011: The GFDL CM3 coupled climate model: Characteristics of the ocean and sea ice simulations. J. Climate, 24, 3520-3544, doi: 10.1175/2011JCLI 3964.1.10.1175/2011JCLI3964.1

cf90970350b57f84cd422b0676b9f341

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2011JCli...24.3520G

http://adsabs.harvard.edu/abs/2011JCli...24.3520GABSTRACT This paper documents time mean simulation characteristics from the ocean and sea ice components in a new coupled climate model developed at the NOAA Geophysical Fluid Dynamics Laboratory (GFDL). The GFDL Climate Model version 3 (CM3) is formulated with effectively the same ocean and sea ice components as the earlier CM2.1 yet with extensive developments made to the atmosphere and land model components. Both CM2.1 and CM3 show stable mean climate indices, such as large-scale circulation and sea surface temperatures (SSTs). There are notable improvements in the CM3 climate simulation relative to CM2.1, including a modified SST bias pattern and reduced biases in the Arctic sea ice cover. The authors anticipate SST differences between CM2.1 and CM3 in lower latitudes through analysis of the atmospheric fluxes at the ocean surface in corresponding Atmospheric Model Intercomparison Project (AMIP) simulations. In contrast, SST changes in the high latitudes are dominated by ocean and sea ice effects absent in AMIP simulations The ocean interior simulation in CM3 is generally warmer than in CM2.1, which adversely impacts the interior biases.

Han W. Q., G. A. Meehl, and A. X. Hu, 2006: Interpretation of tropical thermocline cooling in the Indian and Pacific oceans during recent decades. Geophys. Res. Lett., 33,L23615, doi: 10.1029/2006GL027982.

Hanawa K., L. D. Talley, 2001: Mode waters. Ocean Circulation and Climate, G. Siedler, J. Church, and J. Gould, Eds., International Geophysical Series, Vol. 77, Academic Press, 373- 400.

Hautala S. L., D. H. Roemmich, 1998: Subtropical mode water in the northeast Pacific Basin. Journal of Geophysical Research: Oceans, 103, 13 055- 13 066.10.1029/98JC01015

94b11d1757d54d6995e002109d8cb9d4

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F98JC01015%2Fpdf

http://onlinelibrary.wiley.com/doi/10.1029/98JC01015/pdfA new type of mode water in the upper thermocline of the eastern subtropical North Pacific is identified and examined using data from World Ocean Circulation Experiment high-resolution repeat expendable bathythermograph (XBT) section PX37 and archives of historical XBT data. This water mass (labeled Eastern Subtropical Mode Water) is characterized by a subsurface potential vorticity minimum and is located east of Hawaii (Northeast Pacific Basin) in a density range of 24–25.4 σ θ . It is a distinct water mass from the classical subtropical mode water (STMW) of the western Pacific. Eastern STMW is formed as a relatively deep late-winter mixed layer, associated with the subtropical/subpolar water mass boundary near 25°–30°N, 135°–140°W, and is capped and subducted into the permanent thermocline. Along a section between San Francisco and Honolulu, Eastern STMW production is seen in every year for which there is adequate data. In this section the volume of Eastern STMW formed each winter and the temperature of the potential vorticity minimum are similar during the periods 1970–1979 and 1991–1997.

Hosoda S., S. P. Xie, K. Takeuchi, and M. Nonaka, 2001: Eastern North Pacific subtropical mode water in a general circulation model: Formation mechanism and salinity effects. J. Geophys. Res., 106, 19 671- 19 681.10.1029/2000JC000443

4bc96bef2ed448a44f6423dcb06fd92a

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2000JC000443%2Fabstract

http://onlinelibrary.wiley.com/doi/10.1029/2000JC000443/abstractThe Eastern North Pacific Subtropical Mode Water (ESTMW) is a water mass of low potential vorticity (PV) and appears as a weak pycnostad or thermostad. Distinct from other subtropical mode waters, it forms in the absence of a deep winter mixed layer. The formation mechanism of this ESTMW is investigated using an ocean general circulation model that is forced by monthly climatological temperature, salinity, and wind stress at the sea surface. An equation based on the ventilated thermocline theory is used to diagnose the initial PV of a water mass right after its subduction. In this equation, three factors affect the initial PV: the spacing of density outcrop lines, the mixed layer depth gradient, and the vertical velocity at the bottom of mixed layer. Among them the wide spacing between outcrop lines is the most important for ESTMW's low PV instead of the deep mixed layer, which is most important for classical mode waters. It is found that weak gradients in both sea surface temperature and salinity in the direction of mixed layer flow are important for the low PV formation. A low-salinity tongue that extends southeastward off North America is responsible for the small surface density gradient in the eastern North Pacific and contributes to the formation of the ESTMW. An additional experiment forced with observed freshwater flux demonstrates that the southward advection of fresher water from the high latitude along the eastern boundary is the cause of this low-salinity tongue.

Hu H. B., Q. Y. Liu, Y. Zhang, and W. Liu, 2011: Variability of subduction rates of the subtropical North Pacific mode waters. Chinese Journal of Oceanology and Limnology, 29, 1131- 1141.10.1007/s00343-011-0237-x

1c65ed382f34507cc434281ad85a8ed3

http%3A%2F%2Flink.springer.com%2F10.1007%2Fs00343-011-0237-x

http://d.wanfangdata.com.cn/Periodical_zghyhzxb201105027.aspxThe climatology subduction rate for the entire Pacific is known,but the mechanism of interannual to decadal variation remains unclear.In this study,we calculated the annual subduction rates of three types of North Pacific subtropical mode waters using a general circulation model (LICOM 1.0)for the period of 1958-2001.The model experiments focused on interarnual variations of ocean dynamical processes under daily wind forcings and seasonal heat fluxes.The mode water formation region was defined by a potential vorticity minimum at outcrop locations.The model results show that two subduction rate maxima (锛100 m/a) were located in the Subtropical Mode Water (STMW) and the Central Mode Water (CMW) formation regions.These regions are consistent with a climatologically calculated value.The subduction rate in the Eastern Subtropical Mode Water (ESTMW) formation region was smaller at about 75 m/a.The subduction rate shows clear interannual and decadal variations associated with oceanic dynamic variabilities.The average subduction rate of the STMW was much smaller during the period of 1981-1990 compared with other periods,while that of the CMW had a negative anomaly before 1975 and a positive anomaly after 1978.The variability agreed with Ekman and geostrophic advections and mixed layer depths.The interannual variability of the subduction rate for the ESTMW was smallest during 1970-1990,as a result of a weak wind stress curl.This paper explores how interannual signals from the atmosphere are stored in different parts of the ocean,and thus may contribute to a better understanding of feedback mechanisms for the Pacific Decadal Oscillation (PDO) event.

Huang R. X., B. Qiu, 1994: Three-dimensional structure of the wind-driven circulation in the subtropical North Pacific. J. Phys. Oceanogr., 24, 1608- 1622.10.1175/1520-0485(1994)024<1608:TDSOTW>2.0.CO;2

f8937805d5f3473e6e2c36cad08d463d

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1994JPO....24.1608H

http://adsabs.harvard.edu/abs/1994JPO....24.1608HAbstract The subduction rate is calculated for the North Pacific based on Levitus climatology data and Hellerman and Rosenstein wind stress data. Because the period of effective subduction is rather short, subduction rates calculated in Eulerian and Lagrangian coordinates are very close. The subduction rate defined in the Lagrangian sense consists of two parts. The first part is due to the vertical pumping along the one-year trajectory, and the second part is due to the difference in the winter mixed layer depth over the one-year trajectory. Since the mixed layer is relatively shallow in the North Pacific, the vertical pumping term is very close to the Ekman pumping, while the sloping mixed layer base enhances subduction, especially near the Kuroshio Extension. For most of the subtropical North Pacific, the subduction rate is no more than 75 m yr 611 , slightly larger than the Ekman pumping. The water mass volume and total amount of ventilation integrated for each interval of 0.2σ unit is computed. The corresponding renewal time for each water mass is obtained. The inferred renewal time is 5–6 years for the shallow water masses (σ = 23.0–25.0), and about 10 years for the subtropical mode water (σ = 25.2–25.4). Within the subtropical gyre the total amount of Ekman pumping is 28.8 Sv (Sv ≡ 10 6 m 3 s 611 ) and the total subduction rate is 33.1 Sv, which is slightly larger than the Ekman pumping rate. To this 33.1 Sv, the vertical pumping contributes 24.1 Sv and the lateral induction 9 Sv. The maximum barotropic mass flux of the subtropical gyre is about 46 Sv (cut of 135°E). This mass flux is partitioned as follows. The total horizontal mass flux in the ventilated thermocline, the seasonal thermocline, and the Ekman layer is about 30 Sv, and the remaining 16 Sv is in the unventilated thermocline. Thus, about one-third of the man flux in the wind-driven gyre is sheltered from direct air–sea interaction.

Inui T., K. Takeuchi, and K. Hanawa, 1999: A numerical investigation of the subduction process in response to an abrupt intensification of the westerlies. J. Phys. Oceanogr., 29, 1993- 2015.10.1175/1520-0485(1999)0292.0.CO;2

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http%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F80011344500

http://ci.nii.ac.jp/naid/80011344500Abstract A three-dimensional ocean general circulation model, forced by idealized zonal winds, is used to investigate the effect of an abrupt intensification of westerly winds on the subduction process. Four experiments are carried out: 1) a control experiment with standard wind stress forcing, 2) an intensified winds experiment with wind stress that is larger in the region of the westerlies than the control, 3) an increased surface cooling experiment, and 4) an experiment with both intensified wind stress and surface cooling. Experiments 2 through 4, which contain surface anomalous forcing, are run from the steady state obtained in experiment 1, the control experiment. The results obtained for each of these runs are compared to the control experiment. A subarctic tracer injection experiment is also carried out to verify the differences in the subduction process of each of these experiments. In the wind stress intensified experiment, an examination of the subsurface temperature field shows that negative temperature anomalies occupy the western portion of the southern part of the subtropical gyre, whereas in the surface cooling experiment, negative temperature anomalies occupy the eastern portion of the basin. The source of these negative temperature anomalies is not local since the forcing in the southern part of the subtropical gyre does not change from the control. A close analysis of the evolution of a subarctic surface tracer field indicates that the intensification of the wind stress increases the tracer concentrations, whereas surface cooling decreases the temperature in the region that contains the maximum tracer concentration. In the standard case, the mixed layer is deep (shallow) in the northern (southern) part of the subtropical gyre. Between these two regions a mixed layer front, where the mixed layer depth changes drastically from north to south, exists. A water column with low potential vorticity that originates in the mixed layer penetrates into a subsurface layer from the point where an outcrop line and the mixed layer front intersect. This point is called the penetration point. Intensified westerly winds bring about a deeper thermocline and shoaling subsurface isopycnals. These shoaling subsurface isopycnals are not predicted in classical models such as that of Luyten et al. The model experiment with intensified westerlies demonstrates that the penetration point shifts to the west. As a result, low potential vorticity water penetrates southwestward from the shifted penetration point and takes a more westward path. Therefore, the negative temperature anomalies appear in the southwestern part of the subtropical gyre. This study shows that the westward shift of the path of low potential vorticity water could cause the shoaling of subsurface isopycnal surfaces. The intensification of the westerlies increases Ekman pumping and cools the ocean surface by enhancing sensible and latent heat flux. In the surface cooling experiment, the position of the outcrop lines moves southward significantly. This southward shift makes the subducted water colder and distributes it throughout the ventilated region of the southern part of the subtropical gyre. The combined effect of wind intensification and surface cooling is approximately a linear combination of both experiments.

Latif M., T. P. Barnett, 1994: Causes of decadal climate variability over the North Pacific and North America. Science, 266, 634- 637.10.1126/science.266.5185.634

17793457

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http://med.wanfangdata.com.cn/Paper/Detail/PeriodicalPaper_PM17793457ABSTRACT The cause of decadal climate variability over the North Pacific Ocean and North America is investigated by the analysis of data from a multidecadal integration with a state-of-the-art coupled ocean-atmosphere model and observations. About one-third of the low-frequency climate variability in the region of interest can be attributed to a cycle involving unstable air-sea interactions between the subtropical gyre circulation in the North Pacific and the Aleutian low-pressure system. The existence of this cycle provides a basis for long-range climate forecasting over the western United States at decadal time scales.

Luo Y. Y., Q. Y. Liu, and L. M. Rothstein, 2009: Simulated response of North Pacific Mode Waters to global warming. Geophys. Res. Lett., 36,L23609, doi: 10.1029/2009GL040906.10.1029/2009GL040906

263773f58656265a816fc286db80caa2

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2009GL040906%2Fabstract

http://onlinelibrary.wiley.com/doi/10.1029/2009GL040906/abstract[1] This study investigates the response of the Mode Waters in the North Pacific to global warming based on a set of Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) models. Solutions between a present-day climate and a future, warmer climate are compared. Under the warmer climate scenario, the Mode Waters are produced on lighter isopycnal surfaces and are significantly weakened in terms of their formation and evolution. These changes are due to a more stratified upper ocean and thus a shoaling of the winter mixing depth resulting mainly from a reduction of the ocean-to-atmosphere heat loss over the subtropical region. The basin-wide wind stress may adjust the Mode Waters indirectly through its impact on the surface heat flux and subduction process.

Marshall J. C., R. G. Williams, and A. J. G. Nurser, 1993: Inferring the subduction rate and period over the North Atlantic. J. Phys. Oceanogr., 23, 1315- 1329.10.1175/1520-0485(1993)023<1315:ITSRAP>2.0.CO;2

83938c57b0c78da7adbbcb644a19ce4a

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1993JPO....23.1315M

http://adsabs.harvard.edu/abs/1993JPO....23.1315MAbstract The annual rate at which mixed-layer fluid is transferred into the permanent thermocline hat is, the annual subduction rate S ann and the effective subduction period effs inferred from climatological data in the North Atlantic. From its kinematic definition, S ann is obtained by summing the vertical velocity at the base of the winter mixed layer with the lateral induction of fluid through the sloping base of the winter mixed layer. Geostrophic velocity fields, computed from the Levitus climatology assuming a level of no motion at 2.5 km, are used; the vertical velocity at the base of the mixed layer is deduced from observed surface Ekman pumping velocities and linear vorticity balance. A plausible pattern of S ann is obtained with subduction rates over the subtropical gyre approaching 100 m/yr wice the maximum rate of Ekman pumping. The subduction period eff is found by viewing subduction as a transformation process converting mixed-layer fluid into stratified thermocline fluid. The effective period is that period of time during the shallowing of the mixed layer in which sufficient buoyancy is delivered to permit irreversible transfer of fluid into the main thermocline at the rate S ann . Typically eff is found to be 1 to 2 months over the major part of the subtropical gyre, rising to 4 months in the tropics. Finally, the heat budget of a column of fluid, extending from the surface down to the base of the seasonal thermocline is discussed, following it over an annual cycle. We are able to relate the buoyancy delivered to the mixed layer during the subduction period to the annual-mean buoyancy forcing through the sea surface plus the warming due to the convergence of Ekman heat fluxes. The relative importance of surface fluxes (heat and freshwater) and Ekman fluxes in supplying buoyancy to support subduction is examined using the climatologist observations of Isemer and Hasse, Schmitt et al., and Levitus. The pumping down of fluid from the warm summer Ekman layer into the thermocline makes a crucial contribution and, over the subtropical gyre, is the dominant term in the thermodynamics of subduction.

Mitchell J. F. B., T. C. Johns, J. M. Gregory, and S. F. B. Tett, 1995: Climate response to increasing levels of greenhouse gases and sulphate aerosols. Nature, 376, 501- 504.10.1038/376501a0

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http%3A%2F%2Fwww.nature.com%2Fdoifinder%2F10.1038%2F376501a0

http://www.nature.com/doifinder/10.1038/376501a0Presents a study which simulated past and future climate variations and responses to radiation-scattering by greenhouse gases and sulphate aerosols. Use of a coupled ocean-atmosphere general circulation model; Agreement between observed global mean and large-scale patterns of temperature; Prediction of future global mean warming of 0.3 Kelvin per decade for greenhouse gases alone.

Nakamura H., 1996: A pycnostad on the bottom of the ventilated portion in the central subtropical North Pacific: Its distribution and formation. Journal of Oceanography, 52, 171- 188.e83089269ade0472cf521047594199cd

http%3A%2F%2Flink.springer.com%2F10.1007%2FBF02235668

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Rotstayn L. D., S. J. Jeffrey, M. A. Collier, S. M. Dravitzki, A. C. Hirst, J. I. Syktus, and K. K. Wong, 2012: Aerosol-induced changes in summer rainfall and circulation in the Australasian region: A study using single-forcing climate simulations. Atmospheric Chemistry & Physics, 12, 5107- 6377.ed896764a0de2a70c5a7945c7efc478c

http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2012ACPD...12.5107R

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Sen Gupta, S. A., N. C. Jourdain, J. N. Brown, D. Monselesan, 2013: Climate drift in the CMIP5 models. J.Climate, 26, 8597- 8615.10.1175/JCLI-D-12-00521.1

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http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2013JCli...26.8597G

refpaperuri:(b0439faedf2731b4221c87c98d4b9b9e)

http://adsabs.harvard.edu/abs/2013JCli...26.8597GClimate models often exhibit spurious long-term changes independent of either internal variability or changes to external forcing. Such changes, referred to as model 'drift,' may distort the estimate of forced change in transient climate simulations. The importance of drift is examined in comparison to historical trends over recent decades in the Coupled Model Intercomparison Project (CMIP). Comparison based on a selection of metrics suggests a significant overall reduction in the magnitude of drift from phase 3 of CMIP (CMIP3) to phase 5 of CMIP (CMIP5). The direction of both ocean and atmospheric drift is systematically biased in some models introducing statistically significant drift in globally averaged metrics. Nevertheless, for most models globally averaged drift remains weak compared to the associated forced trends and is often smaller than the difference between trends derived from different ensemble members or the error introduced by the aliasing of natural variability. An exception to this is metrics that include the deep ocean (e.g., steric sea level) where drift can dominate in forced simulations. In such circumstances drift must be corrected for using information from concurrent control experiments. Many CMIP5 models now include ocean biogeochemistry. Like physical models, biogeochemical models generally undergo long spinup integrations to minimize drift. Nevertheless, based on a limited subset of models, it is found that drift is an important consideration and must be accounted for. For properties or regions where drift is important, the drift correction method must be carefully considered. The use of a drift estimate based on the full control time series is recommended to minimize the contamination of the drift estimate by internal variability.

Suga T., K. Motoki, Y. Aoki, and A. M. Macdonald, 2004: The North Pacific climatology of winter mixed layer and mode waters. J. Phys. Oceanogr.,34, 3-22, doi: 10.1175/1520-0485.8d225dc68ccd5cd3f64570bb3fdcb720

http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D2004JPO....34....3S%26db_key%3DPHY%26link_type%3DABSTRACT%26high%3D17368

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Taylor K. E., R. J. Stouffer, and G. A. Meehl, 2012: An overview of CMIP5 and the experiment design. Bull. Amer. Meteor. Soc.,93, 485-498, doi: 10.1175/BAMS-D-11-00094.1.10.1175/BAMS-D-11-00094.1

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http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2012BAMS...93..485T

refpaperuri:(102c64f576f0dc49ca552e6df691421b)

http://adsabs.harvard.edu/abs/2012BAMS...93..485TThe fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance our knowledge of climate variability and climate change. Researchers worldwide are analyzing the model output and will produce results likely to underlie the forthcoming Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Unprecedented in scale and attracting interest from all major climate modeling groups, CMIP5 includes “long term” simulations of twentieth-century climate and projections for the twenty-first century and beyond. Conventional atmosphere–ocean global climate models and Earth system models of intermediate complexity are for the first time being joined by more recently developed Earth system models under an experiment design that allows both types of models to be compared to observations on an equal footing. Besides the longterm experiments, CMIP5 calls for an entirely new suite of “near term” simulations focusing on recent decades and the future to year 2035. These “decadal predictions” are initialized based on observations and will be used to explore the predictability of climate and to assess the forecast system's predictive skill. The CMIP5 experiment design also allows for participation of stand-alone atmospheric models and includes a variety of idealized experiments that will improve understanding of the range of model responses found in the more complex and realistic simulations. An exceptionally comprehensive set of model output is being collected and made freely available to researchers through an integrated but distributed data archive. For researchers unfamiliar with climate models, the limitations of the models and experiment design are described.

Toyoda T., T. Awaji, Y. Ishikawa, and T. Nakamura, 2004: Preconditioning of winter mixed layer in the formation of North Pacific eastern subtropical mode water. Geophys. Res. Lett., 31,L17206, doi: 10.1029/2004GL020677.10.1029/2004GL020677

f3aa24ca7b49f966d7df8ea843ca03e7

http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2004GL020677%2Fabstract

http://onlinelibrary.wiley.com/doi/10.1029/2004GL020677/abstractABSTRACT The preconditioning of winter mixed layer in the formation of the eastern subtropical mode water (ESTMW) in the North Pacific Ocean is investigated using an eddy-permitting ocean general circulation model. The result shows that convergence in the northward Ekman transport of saltier water and weak summertime heat fluxes due to the presence of stratus cloud in the ESTMW formation region are both central to the initiation of significant mixed layer deepening that subsequently evolves into the ESTMW pycnostad in the main thermocline. These two factors originate from air-sea interactions inherent in the region of Northeast Pacific Basin. The approach described here has significant potential for determining the water-mass distribution and may lead to an explanation of the Sverdrup's Eastern Gyral in the subtropical North Pacific.

Toyoda T., T. Awaji, S. Masuda, N. Sugiura, H. Igarashi, T. Mochizuki, and Y. Ishikawa, 2011: Interannual variability of North Pacific eastern subtropical mode water formation in the 1990s derived from a 4-dimensional variational ocean data assimilation experiment. Dyn. Atmos.Oceans, 51, 1- 25.

Wang L. Y., Q. Y. Liu, L. X. Xu, and S.-P. Xie, 2013: Response of mode water and subtropical countercurrent to greenhouse gas and aerosol forcing in the North Pacific. Journal of Ocean University of China,12, 222-229, doi: 10.1007/s11802-013-2193-x.10.1007/s11802-013-2193-x

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http%3A%2F%2Fwww.cnki.com.cn%2FArticle%2FCJFDTotal-QDHB201302005.htm

refpaperuri:(db09f2a064623c26259f6245b12f5ad6)

http://d.wanfangdata.com.cn/Periodical_qdhydxxb-e201302005.aspxThe response of the North Pacific Subtropical Mode Water and Subtropical Countercurrent (STCC) to changes in greenhouse gas (GHG) and aerosol is investigated based on the 20th-century historical and single-forcing simulations with the Geo-physical Fluid Dynamics Laboratory Climate Model version 3 (GFDL CM3). The aerosol effect causes sea surface temperature (SST) to decrease in the mid-latitude North Pacific, especially in the Kuroshio Extension region, during the past five decades (1950-2005), and this cooling effect exceeds the warming effect by the GHG increase. The STCC response to the GHG and aerosol forcing are opposite. In the GHG (aerosol) forcing run, the STCC decelerates (accelerates) due to the decreased (increased) mode waters in the North Pacific, resulting from a weaker (stronger) front in the mixed layer depth and decreased (increased) subduction in the mode water formation region. The aerosol effect on the SST, mode waters and STCC more than offsets the GHG effect. The response of SST in a zonal band around 40?N and the STCC to the combined forcing in the historical simulation is similar to the response to the aerosol forcing.

Xie S.-P., C. Deser, G. A. Vecchi, J. Ma, H. Y. Teng, and A. T. Wittenberg, 2010: Global warming pattern formation: Sea surface temperature and rainfall. J.Climate, 23, 966- 986.10.1175/2009JCLI3329.1

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http%3A%2F%2Fwww.cabdirect.org%2Fabstracts%2F20103118162.html

refpaperuri:(b0ebeb07b4f54809d624dfe9936fb36c)

http://www.cabdirect.org/abstracts/20103118162.htmlAbstract Spatial variations in sea surface temperature (SST) and rainfall changes over the tropics are investigated based on ensemble simulations for the first half of the twenty-first century under the greenhouse gas (GHG) emission scenario A1B with coupled ocean-tmosphere general circulation models of the Geophysical Fluid Dynamics Laboratory (GFDL) and National Center for Atmospheric Research (NCAR). Despite a GHG increase that is nearly uniform in space, pronounced patterns emerge in both SST and precipitation. Regional differences in SST warming can be as large as the tropical-mean warming. Specifically, the tropical Pacific warming features a conspicuous maximum along the equator and a minimum in the southeast subtropics. The former is associated with westerly wind anomalies whereas the latter is linked to intensified southeast trade winds, suggestive of wind-vaporation ST feedback. There is a tendency for a greater warming in the northern subtropics than in the southern subtropics in accordance with asymmetries in trade wind changes. Over the equatorial Indian Ocean, surface wind anomalies are easterly, the thermocline shoals, and the warming is reduced in the east, indicative of Bjerknes feedback. In the midlatitudes, ocean circulation changes generate narrow banded structures in SST warming. The warming is negatively correlated with wind speed change over the tropics and positively correlated with ocean heat transport change in the northern extratropics. A diagnostic method based on the ocean mixed layer heat budget is developed to investigate mechanisms for SST pattern formation. Tropical precipitation changes are positively correlated with spatial deviations of SST warming from the tropical mean. In particular, the equatorial maximum in SST warming over the Pacific anchors a band of pronounced rainfall increase. The gross moist instability follows closely relative SST change as equatorial wave adjustments flatten upper-tropospheric warming. The comparison with atmospheric simulations in response to a spatially uniform SST warming illustrates the importance of SST patterns for rainfall change, an effect overlooked in current discussion of precipitation response to global warming. Implications for the global and regional response of tropical cyclones are discussed.

Xu L. X., S.-P. Xie, J. L. McClean, Q. Y. Liu, and H. Sasaki, 2014: Mesoscale eddy effects on the subduction of North Pacific mode waters. J. Geophys. Res.,119, 4867-4886, doi: 10.1002/2014JC009861.10.1002/2014JC009861

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http://onlinelibrary.wiley.com/doi/10.1002/2014JC009861/abstractAbstract Mesoscale eddy effects on the subduction of North Pacific mode waters are investigated by comparing observations and ocean general circulation models where eddies are either parameterized or resolved. The eddy-resolving models produce results closer to observations than the noneddy-resolving model. There are large discrepancies in subduction patterns between eddy-resolving and noneddy-resolving models. In the noneddy-resolving model, subduction on a given isopycnal is limited to the cross point between the mixed layer depth (MLD) front and the outcrop line whereas in eddy-resolving models and observations, subduction takes place in a broader, zonally elongated band within the deep mixed layer region. Mesoscale eddies significantly enhance the total subduction rate, helping create remarkable peaks in the volume histogram that correspond to North Pacific subtropical mode water (STMW) and central mode water (CMW). Eddy-enhanced subduction preferentially occurs south of the winter mean outcrop. With an anticyclonic eddy to the west and a cyclonic eddy to the east, the outcrop line meanders south, and the thermocline/MLD shoals eastward. As eddies propagate westward, the MLD shoals, shielding the water of low potential vorticity from the atmosphere. The southward eddy flow then carries the subducted water mass into the thermocline. The eddy subduction processes revealed here have important implications for designing field observations and improving models.