Alexand er, M. A., U. S. Bhatt, J. E. Walsh, M. S. Timlin, J. S. Miller, J. D. Scott, 2004: The atmospheric response to realistic Arctic sea ice anomalies in an AGCM during winter. J. Climate, 17, 890-905, https://doi.org/10.1175/1520-0442(2004)017<0890:TARTRA>2.0,CO;2.10.1175/1520-0442(2004)017<0890:TARTRA>2.0.CO;2fc0ae199b9c2388844c40377f6b33268http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D2004JCli...17..890A%26amp%3Bdb_key%3DPHY%26amp%3Blink_type%3DABSTRACT%26amp%3Bhigh%3D06304http://journals.ametsoc.org/doi/abs/10.1175/1520-0442%282004%29017%3C0890%3ATARTRA%3E2.0.CO%3B2 |
Cavalieri D. J., C. L. Parkinson, P. Gloersen, and H. Zwally, 1996: Sea ice concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS passive microwave data, version 1. November 1979-2014, Tech. Rep., NASA Natl. Snow and Ice Data Cent. Distrib. Active Archive Cent.,Boulder,Colo. |
Conil S., Z. X. Li, 2005: Linearity of the atmospheric response to North Atlantic SST and sea ice anomalies.J. Climate,18,1986-2003, https://doi.org/10.1175/JCLI3388.1.10.1175/JCLI3388.15712c7c221c1aed81ddcb8ae88516157http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2005JCli...18.1986Chttp://journals.ametsoc.org/doi/abs/10.1175/JCLI3388.1The observations of the ocean09“atmosphere09“sea ice have recently revealed that the oceanic surfaces can have a subtle but significant impact on the atmospheric long-term fluctuations. Low-frequency variations and long-term trends of the North Atlantic atmospheric circulation have been partly related to particular SST and sea ice features. In this work, the influence of typical tripolar SST and dipolar sea ice anomalies in the North Atlantic09“Arctic on the atmosphere is investigated. A large ensemble of AGCM simulations forced by three different anomalous boundary conditions (SST, sea ice, and SST + sea ice) are used. The linearity of the simulated response in the winter season is particularly assessed. In these experiments, while the winter low-level temperature response is mainly symmetric about the sign of the forcing, the asymmetric part of the geopotential response is substantial. The sea ice forcing maintains a baroclinic response with a strong temperature anomaly in the vicinity of the forcing but with a weak vertical penetration. The SST maintains an NAO-like equivalent barotropic temperature and geopotential height response that extends throughout the troposphere. It is also shown that the combination of the two forcings is mainly linear for the low-level temperature and nonlinear for the geopotential height. While the SST forcing seems to be the main contributor to the total temperature and geopotential height responses, the sea ice forcing appears to introduce significant nonlinear perturbations. |
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, https://doi.org/10.1002/qj.828.10.1002/qj.8285b3115ec8b338ee97111270a1831c4b2http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fqj.828%2Fpdfhttp://doi.wiley.com/10.1002/qj.v137.656ERA-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 |
Deser C., J. E. Walsh, and M. S. Timlin, 2000: Arctic sea ice variability in the context of recent atmospheric circulation trends. J. Climate, 13, 617-633, https://doi.org/10.1175/1520-0442(2000)013<0617:ASIVIT>2.0,CO;2.10.1175/1520-0442(2000)0132.0.CO;24e146878c21adc9de0ce4b8fa43a8ce4http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2000JCli...13..617Dhttp://journals.ametsoc.org/doi/abs/10.1175/1520-0442%282000%29013%3C0617%3AASIVIT%3E2.0.CO%3B2Abstract Forty years (1958–97) of reanalysis products and corresponding sea ice concentration data are used to document Arctic sea ice variability and its association with surface air temperature (SAT) and sea level pressure (SLP) throughout the Northern Hemisphere extratropics. The dominant mode of winter (January–March) sea ice variability exhibits out-of-phase fluctuations between the western and eastern North Atlantic, together with a weaker dipole in the North Pacific. The time series of this mode has a high winter-to-winter autocorrelation (0.69) and is dominated by decadal-scale variations and a longer-term trend of diminishing ice cover east of Greenland and increasing ice cover west of Greenland. Associated with the dominant pattern of winter sea ice variability are large-scale changes in SAT and SLP that closely resemble the North Atlantic oscillation. The associated SAT and surface sensible and latent heat flux anomalies are largest over the portions of the marginal sea ice zone in which the tr... |
Deser C, G. Magnusdottir, R. Saravanan, A. Phillips, 2004: The effects of North Atlantic SST and sea ice anomalies on the winter circulation in CCM3. Part II: direct and indirect components of the response. J. Climate, 17, 877-889, https://doi.org/10.1175/1520-0442(2004)017<0877:TEONAS>2.0,CO;2. |
Duchon C. E., 1979: Lanczos filtering in one and two dimensions. J. Appl. Meteorol., 18, 1016-1022, https://doi.org/10.1175/1520-0450(1979)018<1016:LFIOAT>2.0,CO;2.10.1175/1520-0450(1979)018<1016:LFIOAT>2.0.CO;226ec2d2002010a4ba6313a775aa66556http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1979JApMe..18.1016Dhttp://journals.ametsoc.org/doi/abs/10.1175/1520-0450%281979%29018%3C1016%3ALFIOAT%3E2.0.CO%3B2A Fourier method of filtering digital data called Lanczos filtering is described. Its principal feature is the use of “sigma factors” which significantly reduce the amplitude of the Gibbs oscillation. A pair of graphs is developed that can be used to determine filter response quality given the number of weights and the value of the cutoff frequency, the only two inputs required by the method. Examples of response functions in one and two dimensions are given and comparisons are made with response functions from other filters. The simplicity of calculating the weights and the adequate response make Lanczos filtering an attractive filtering method. |
Frankignoul C., N. Sennèchael, and P. Cauchy, 2014: Observed atmospheric response to cold season sea ice variability in the Arctic.J. Climate,27,1243-1254, https://doi.org/10.1175/JCLI-D-13-00189.1.10.1175/JCLI-D-13-00189.1c7c506e0f5077d90ad785a50301d1668http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2014JCli...27.1243Fhttp://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-13-00189.1Abstract The relation between weekly Arctic sea ice concentrations (SICs) from December to April and sea level pressure (SLP) during 1979-2007 is investigated using maximum covariance analysis (MCA). In the North Atlantic sector, the interaction between the North Atlantic Oscillation (NAO) and a SIC seesaw between the Labrador Sea and the Greenland-Barents Sea dominates. The NAO drives the seesaw and in return the seesaw precedes a midwinter/spring NAO-like signal of the opposite polarity but with a strengthened northern lobe, thus acting as a negative feedback, with maximum squared covariance at a lag of 6 weeks. Statistical significance decreases when SLP is considered in the whole Northern Hemisphere but it increases when North Pacific SIC is included in the analysis. The maximum squared covariance then occurs after 8 weeks, resembling a combination of the NAO response to the Atlantic SIC seesaw and the Aleutian-Icelandic low seesaw-like response to in-phase SIC changes in the Bering and Okhotsk Seas, which is found to lag the North Pacific SIC. Adding SST anomalies to the SIC anomalies in the MCA leads to a loss of significance when the MCA is limited to the North Atlantic sector and a slight degradation in the Pacific and hemispheric cases, suggesting that SIC is the driver of the midwinter/spring atmospheric signal. However, North Pacific cold season SST anomalies also precede a NAO/Arctic Oscillation (AO)-like SLP signal after a shorter delay of 3-4 weeks. |
Guo D., Y. Gao, I. Bethke, D. Gong, M. Johannessen, and H. J. Wang, 2014: Mechanism on how the spring Arctic sea ice impacts the East Asian summer monsoon.Theor. Appl. Climatol.,115,107-119, https://doi.org/10.1007/s00704-013-0872-6.10.1007/s00704-013-0872-6e974c7d3c1cbd752fc0be37fda1807fehttp%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2Fs00704-013-0872-6http://link.springer.com/10.1007/s00704-013-0872-6Observational analysis and purposely designed coupled atmosphere cean (AOGCM) and atmosphere-only (AGCM) model simulations are used together to investigate a new mechanism describing how spring Arctic sea ice impacts the East Asian summer monsoon (EASM). Consistent with previous studies, analysis of observational data from 1979 to 2009 show that spring Arctic sea ice is significantly linked to the EASM on inter-annual timescales. Results of a multivariate Empirical Orthogonal Function analysis reveal that sea surface temperature (SST) changes in the North Pacific play a mediating role for the inter-seasonal connection between spring Arctic sea ice and the EASM. Large-scale atmospheric circulation and precipitation changes are consistent with the SST changes. The mechanism found in the observational data is confirmed by the numerical experiments and can be described as follows: spring Arctic sea ice anomalies cause atmospheric circulation anomalies, which, in turn, cause SST anomalies in the North Pacific. The SST anomalies can persist into summer and then impact the summer monsoon circulation and precipitation over East Asia. The mediating role of SST changes is highlighted by the result that only the AOGCM, but not the AGCM, reproduces the observed sea ice-EASM linkage. |
Honda M., J. Inoue, and S. Yamane, 2009: Influence of low Arctic sea-ice minima on anomalously cold Eurasian winters,Geophys. Res. Lett.,36,L08707, https://doi.org/10.1029/2008GL037079.10.1029/2008GL03707911ff7459b32da24cee92554351efd9cbhttp%3A%2F%2Fwww.cabdirect.org%2Fabstracts%2F20103055291.htmlhttp://www.cabdirect.org/abstracts/20103055291.htmlInfluence of low Arctic sea-ice minima in early autumn on the wintertime climate over Eurasia is investigated. Observational evidence shows that significant cold anomalies over the Far East in early winter and zonally elongated cold anomalies from Europe to Far East in late winter are associated with the decrease of the Arctic sea-ice cover in the preceding summer-to-autumn seasons. Results fro... |
Han Z., F. F. Luo, and J. H. Wan, 2016a: The observational influence of the North Atlantic SST tripole on the early spring atmospheric circulation.Geophys. Res. Lett.,43,2998-3003, https://doi.org/10.1002/2016GL068099.10.1002/2016GL0680992736641738fe653ad6901014b053ba93http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2F2016GL068099%2Ffullhttp://doi.wiley.com/10.1002/2016GL068099This study investigated the forcing of the North Atlantic sea surface temperature (SST) tripole on the North Atlantic Oscillation (NAO)-like circulation in early spring (February-April) in observations. Corresponding to an SST tripole forcing in early spring, the atmospheric circulation is very weak and insignificant. However, further analyses indicate that the observational effect of the SST anomalies on the NAO-like circulation is disturbed by the concomitant sea ice anomalies. With the linear effects of sea ice anomalies removed, there is an equivalent barotropic NAO-like circulation in early spring related to a North Atlantic SST tripole. |
Han Z., S. L. Li, J. P. Liu, Y. Q. Gao, and P. Zhao, 2016b: Linear additive impacts of arctic sea ice reduction and La Niña on northern hemispheric winter climate. J. Climate 29, https://doi.org/10.1175/JCLI-D-15-0416.1.10.1175/JCLI-D-15-0416.1d4907fc539e130d9769a3bde074b8b3fhttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2016JCli...29.5513Hhttp://adsabs.harvard.edu/abs/2016JCli...29.5513HAbstract Both Arctic sea ice loss and La Nina events can result in cold conditions in midlatitude Eurasia in winter. Since the two forcings sometimes occur simultaneously, determining whether they are independent of each other is undertaken first. The result suggests an overall independence. Considering possible interactions between them, their coordinated impacts on the Northern Hemisphere winter climate are then investigated based on observational data analyses, historical simulation analyses from one coupled model (MPI-ESM-LR) contributing to CMIP5, and atmospheric general circulation model sensitive experiments in ECHAM5. The results show that the impacts of the two forcings are overall linearly accumulated. In comparison with one single forcing, there is intensified cooling response in midlatitude Eurasia along with northern warmer outhern cooler dipolar temperature responses over North America. Despite the additive linearity, additive nonlinearity between the two forcings is identifiable. The nonlin... |
Hawcroft M. K., L. C. Shaffrey, K. I. Hodges, and H. F. Dacre, 2012: How much Northern Hemisphere precipitation is associated with extratropical cyclones? Geophys. Res. Lett. 39, https://doi.org/10.1029/2012GL053866.10.1029/2012GL0538667c18acb3ba450f2f04b4ad737ff37691http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2012GL053866%2Ffullhttp://onlinelibrary.wiley.com/doi/10.1029/2012GL053866/fullExtratropical cyclones are often associated with heavy precipitation events and can have major socio-economic impacts. This study investigates how much of the total precipitation in the Northern Hemisphere is associated with extratropical cyclones. An objective feature tracking algorithm is used to locate cyclones and the precipitation associated with these cyclones is quantified to establish their contribution to total precipitation. Climatologies are produced from the Global Precipitation Climatology Project (GPCP) daily dataset and the ERA-Interim reanalysis. The magnitude and spatial distribution of cyclone associated precipitation and their percentage contribution to total precipitation is closely comparable in both datasets. In some regions, the contribution of extratropical cyclones exceeds 90/85% of the total DJF/JJA precipitation climatology. The relative contribution of the most intensely precipitating storms to total precipitation is greater in DJF than JJA. The most intensely precipitating 10% of storms contribute over 20% of total storm associated precipitation in DJF, whereas they provide less than 15% of this total in JJA. |
Huang S. L., X. Q. Yang, and Q. Xie, 1992: The effects of the Arctic sea ice on the variations of atmospheric circulation and climate. Acta Meteorologica Sinica, 6, 1- 14.4c2b75b74d700e31495e2be89229b0c8http%3A%2F%2Fwww.cqvip.com%2FQK%2F88418X%2F199201%2F1005135191.htmlhttp://www.cqvip.com/QK/88418X/199201/1005135191.htmlThe SST anomaly of the central-eastern equatorial Pacific and the arctic sea ice anomalies of the four districts located respectively in 160ºE-110ºW,110ºW-20ºW,70ºE-160ºE and 20ºW-70ºE are taken as five separate factors.And the relationship between each factor and the atmospheric general circulation and the climate is investigated by observational analysis and numerical experiments.It is shown that the effects of the arctic sea ice anomalies on the variations of atmospheric circulation and climate are comparable to or even in some cases greater than that of EI Nino events.So one should pay much attention to the study of polar sea ice anomalies in climate research.http://www.cqvip.com/QK/88418X/199201/1005135191.html |
Kvamst N. G., P. Skeie, and D. B. Stephenson, 2004: Impact of Labrador Sea-ice extent on the North Atlantic Oscillation.Int. J. Climatol.,24,603-612, https://doi.org/10.1002/joc.1015.10.1002/joc.1015082c7633c28a9fb9f9c38f18384ba769http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjoc.1015%2Fpdfhttp://doi.wiley.com/10.1002/%28ISSN%291097-0088The wintertime atmospheric response to imposed sea-surface temperature and sea-ice extent changes in the Labrador Sea has been investigated by means of ensemble simulations with an atmospheric general circulation model. Low temperatures and heavy ice conditions in the Labrador Sea produce a statistically significant (at 95% confidence) negative North Atlantic oscillation-Arctic oscillation (NAO-AO) response. Conversely, reduced sea-ice extent in the Labrador Sea produces a positive NAO-AO response. The two simulations with opposite sea-ice conditions in the Labrador Sea exhibit a maximum mean wintertime difference of 4-5 hPa in sea-level pressure corresponding to a substantial and statistically significant change in the NAO-AO index of 0.7 standard deviations. The large-scale response to a local perturbation of sea-ice conditions is associated with marked changes in the transient eddies (synoptic storms). Changes in the sea-ice cover cause changes in low-level baroclinicity that perturb the travelling baroclinic disturbances, which then bring the signal downstream to manifest a non-local Atlantic-wide response. The atmospheric response suggests that the sea ice in the Labrador Sea is able to provide an important negative feedback on long-term NAO-AO variations. |
Li F., H. J. Wang, 2013: Relationship between Bering Sea ice cover and East Asian winter monsoon year-to-year variations.Adv. Atmos. Sci.,30,48-56, https://doi.org/10.1007/s00376-012-2071-2.10.1007/s00376-012-2071-2c88dec2c43efb8f9fcc159002dbb6933http%3A%2F%2Fonlinelibrary.wiley.com%2Fresolve%2Freference%2FXREF%3Fid%3D10.1007%2Fs00376-012-2071-2http://link.springer.com/10.1007/s00376-012-2071-2AbstractIn this study, the relationship between year-to-year variations in the Bering Sea ice cover (BSIC) and the East Asian winter monsoon (EAWM) for the period 1969–2001 was documented. The time series of total ice cover in the eastern Bering Sea correlated with the EAWM index at 610.49, indicating that they are two tightly related components. Our results show that the BSIC was closely associated with the simultaneous local and large-scale atmosphere over the Asian-northern Pacific region. Heavy BSIC corresponded to weaker EAWM circulations and light BSIC corresponded to stronger EAWM circulations. Thus, the BSIC should be considered as one of the possible factors affecting the EAWM variation. |
Liu J. P., J. A. Curry, H. Wang, M. Song, and R. M. Horton, 2012: Impact of declining Arctic sea ice on winter snowfall.Proceedings of the National Academy of Sciences of the Unites States of America.,109,4074-4079, https://doi.org/10.1073/pnas.V1114910109.10.1073/pnas.111491010922371563e869b196cae446b30762b978476557d4http%3A%2F%2Fwww.jstor.org%2Fstable%2F41507098http://www.pnas.org/cgi/doi/10.1073/pnas.1114910109While the Arctic region has been warming strongly in recent decades, anomalously large snowfall in recent winters has affected large parts of North America, Europe, and east Asia. Here we demonstrate that the decrease in autumn Arctic sea ice area is linked to changes in the winter Northern Hemisphere atmospheric circulation that have some resemblance to the negative phase of the winter Arctic oscillation. However, the atmospheric circulation change linked to the reduction of sea ice shows much broader meridional meanders in midlatitudes and clearly different interannual variability than the classical Arctic oscillation. This circulation change results in more frequent episodes of blocking patterns that lead to increased cold surges over large parts of northern continents. Moreover, the increase in atmospheric water vapor content in the Arctic region during late autumn and winter driven locally by the reduction of sea ice provides enhanced moisture sources, supporting increased heavy snowfall in Europe during early winter and the northeastern and midwestern United States during winter. We conclude that the recent decline of Arctic sea ice has played a critical role in recent cold and snowy winters. |
Magnusdottir G., C. Deser, and R. Saravanan, 2004: The effects of North Atlantic SST and sea ice anomalies on the winter circulation in CCM3. Part I: Main features and storm track characteristic of the response. J. Climate, 17, 857-876, https://doi.org/10.1175/1520-0442(2004)017<0877:TEONAS>2.0,CO;2. |
Mori M., M. Watanabe, H. Shiogama, J. Inoue, and M. Kimoto, 2014: Robust Arctic sea-ice influence on the frequent Eurasian cold winters in past decades.Nature Geoscience,7,869-873, https://doi.org/10.1038/ngeo2277.10.1038/ngeo2277cdef8a86f56c39f6052fde6e5d1dd7bbhttp%3A%2F%2Fwww.nature.com%2Fngeo%2Fjournal%2Fv7%2Fn12%2Fabs%2Fngeo2277.htmlhttp://www.nature.com/doifinder/10.1038/ngeo2277Over the past decade, severe winters occurred frequently in mid-latitude Eurasia, despite increasing global- and annual-mean surface air temperatures. Observations suggest that these cold Eurasian winters could have been instigated by Arctic sea-ice decline, through excitation of circulation anomalies similar to the Arctic Oscillation. In climate simulations, however, a robust atmospheric response to sea-ice decline has not been found, perhaps owing to energetic internal fluctuations in the atmospheric circulation. Here we use a 100-member ensemble of simulations with an atmospheric general circulation model driven by observation-based sea-ice concentration anomalies to show that as a result of sea-ice reduction in the Barents-Kara Sea, the probability of severe winters has more than doubled in central Eurasia. In our simulations, the atmospheric response to sea-ice decline is approximately independent of the Arctic Oscillation. Both reanalysis data and our simulations suggest that sea-ice decline leads to more frequent Eurasian blocking situations, which in turn favour cold-air advection to Eurasia and hence severe winters. Based on a further analysis of simulations from 22 climate models we conclude that the sea-ice-driven cold winters are unlikely to dominate in a warming future climate, although uncertainty remains, due in part to an insufficient ensemble size. |
Overland, J. E., J. A. Francis, R. Hall, E. Hanna, S.-J. Kim, T. Vihma, 2015: The melting Arctic and midlatitude weather patterns: Are they connected? J.Climate,28,7917-7932, https://doi.org/10.1175/JCLI-D-14-00822.1.10.1175/JCLI-D-14-00822.10eff56c315ae22f8ed4dcb680ca380fchttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2015JCli...28.7917Ohttp://journals.ametsoc.org/doi/10.1175/JCLI-D-14-00822.1The potential of recent Arctic changes to influence hemispheric weather is a complex and controversial topic with considerable uncertainty, as time series of potential linkages are short (<10 yr) and understanding involves the relative contribution of direct forcing by Arctic changes on a chaotic climatic system. A way forward is through further investigation of atmospheric dynamic mechanisms. During several exceptionally warm Arctic winters since 2007, sea ice loss in the Barents and Kara Seas initiated eastward-propagating wave trains of high and low pressure. Anomalous high pressure east of the Ural Mountains advected Arctic air over central and eastern Asia, resulting in persistent cold spells. Blocking near Greenland related to low-level temperature anomalies led to northerly flow into eastern North America, inducing persistent cold periods. Potential Arctic connections in Europe are less clear. Variability in the North Pacific can reinforce downstream Arctic changes, and Arctic amplification can accentuate the impact of Pacific variability. The authors emphasize multiple linkage mechanisms that are regional, episodic, and based on amplification of existing jet stream wave patterns, which are the result of a combination of internal variability, lower-tropospheric temperature anomalies, and midlatitude teleconnections. The quantitative impact of Arctic change on midlatitude weather may not be resolved within the foreseeable future, yet new studies of the changing Arctic and subarctic low-frequency dynamics, together with additional Arctic observations, can contribute to improved skill in extended-range forecasts, as planned by the WMO Polar Prediction Project (PPP). 2015 American Meteorological Society. |
Rayner N. A., D. E. Parker, E. B. Horton, C. K. Folland , L. V. Alexand er, D. P. Powell, E. C. Kent, and A. Kaplan, 2003: Global analyses of sea surface temperature,sea ice,and night marine air temperature since the late nineteenth century. J. Geophys. Res.,108, 4407-4443,https://doi.org/10.1029/2002JD002670.10.1029/2002JD0026700831f099871c89699f00bb6e2586346bhttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2002JD002670%2Ffullhttp://doi.wiley.com/10.1029/2002JD002670We present the Met Office Hadley Centre's sea ice and sea surface temperature (SST) data set, HadISST1, and the nighttime marine air temperature (NMAT) data set, HadMAT1. HadISST1 replaces the global sea ice and sea surface temperature (GISST) data sets and is a unique combination of monthly globally complete fields of SST and sea ice concentration on a 1º latitude-longitude grid from 1871. The companion HadMAT1 runs monthly from 1856 on a 5º latitude-longitude grid and incorporates new corrections for the effect on NMAT of increasing deck (and hence measurement) heights. HadISST1 and HadMAT1 temperatures are reconstructed using a two-stage reduced-space optimal interpolation procedure, followed by superposition of quality-improved gridded observations onto the reconstructions to restore local detail. The sea ice fields are made more homogeneous by compensating satellite microwave-based sea ice concentrations for the impact of surface melt effects on retrievals in the Arctic and for algorithm deficiencies in the Antarctic and by making the historical in situ concentrations consistent with the satellite data. SSTs near sea ice are estimated using statistical relationships between SST and sea ice concentration. HadISST1 compares well with other published analyses, capturing trends in global, hemispheric, and regional SST well, containing SST fields with more uniform variance through time and better month-to-month persistence than those in GISST. HadMAT1 is more consistent with SST and with collocated land surface air temperatures than previous NMAT data sets. |
Roeckner, E., Coauthors, 2003: The atmospheric general circulation model ECHAM5. Part I: Model description. Max Planck Institute for Meteorology Rep No. 349, 127 pp. |
Roeckner, E., Coauthors, 2006: Sensitivity of simulated climate to horizontal and vertical resolution in the ECHAM5 atmosphere model.J. Climate,19,3771-3791, https://doi.org/10.1175/JCLI3824.1.10.1175/JCLI3824.1fa3a017a308a4540aebf217736a65fachttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2006JCli...19.3771Rhttp://journals.ametsoc.org/doi/abs/10.1175/JCLI3824.1The most recent version of the Max Planck Institute for Meteorology atmospheric general circulation model, ECHAM5, is used to study the impact of changes in horizontal and vertical resolution on seasonal mean climate. In a series of Atmospheric Model Intercomparison Project (AMIP)-style experiments with resolutions ranging between T21L19 and T159L31, the systematic errors and convergence properties are assessed for two vertical resolutions. At low vertical resolution (L19) there is no evidence for convergence to a more realistic climate state for horizontal resolutions higher than T42. At higher vertical resolution (L31), on the other hand, the root-mean-square errors decrease monotonically with increasing horizontal resolution. Furthermore, except for T42, the L31 versions are superior to their L19 counterparts, and the improvements become more evident at increasingly higher horizontal resolutions. This applies, in particular, to the zonal mean climate state and to the stationary wave patterns in boreal winter. As in previous studies, increasing horizontal resolution leads to a warming of the troposphere, most prominently at midlatitudes, and to a poleward shift and intensification of the midlatitude westerlies. Increasing the vertical resolution has the opposite effect, almost independent of horizontal resolution. Whereas the atmosphere is colder at low and middle latitudes, it is warmer at high latitudes and close to the surface. In addition, increased vertical resolution results in a pronounced warming in the polar upper troposphere and lower stratosphere, where the cold bias is reduced by up to 50% compared to L19 simulations. Consistent with these temperature changes is a decrease and equatorward shift of the midlatitude westerlies. The substantial benefits in refining both horizontal and vertical resolution give some support to scaling arguments deduced from quasigeostrophic theory implying that horizontal and vertical resolution ought to be chosen consistently. |
Schneider, U., Coauthors, 2011: GPCC full data reanalysis version 6.0 at 1.0: Monthly land-surface precipitation from rain-gauges built on GTS-based and historic data. https://doi.org/10.5676/DWD_GPCC/FD_M_V6_100. [ Available online from https://rda.ucar.edu/datasets/ds496.0/ |
Strong C., G. Magnusdottir, 2011: Dependence of NAO variability on coupling with sea ice.Climate Dyn.,36,1681-1689, https://doi.org/10.1007/s00382-010-0752-z.10.1007/s00382-010-0752-zf3f0c02a4e48865422ed9eb8e7edbfc7http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fa66j00k135476366%2Fhttp://link.springer.com/10.1007/s00382-010-0752-zThe variance of the North Atlantic Oscillation index (denoted ) is shown to depend on its coupling with area-averaged sea ice concentration anomalies in and around the Barents Sea (index denoted ). The observed form of this coupling is a negative feedback whereby positive tends to produce negative , which in turn forces negative . The effects of this feedback in the system are examined by modifying the feedback in two modeling frameworks: a statistical vector autoregressive model ( ) and an atmospheric global climate model ( ) customized so that sea ice anomalies on the lower boundary are stochastic with adjustable sensitivity to the model evolving . Experiments show that the variance of decreases nearly linearly with the sensitivity of to , where the sensitivity is a measure of the negative feedback strength. Given that the sea ice concentration field has anomalies, the variance of goes down as these anomalies become more sensitive to . If the sea ice concentration anomalies are entirely absent, the variance of is even smaller than the experiment with the most sensitive anomalies. Quantifying how the variance of depends on the presence and sensitivity of sea ice anomalies to has implications for the simulation of in global climate models. In the physical system, projected changes in sea ice thickness or extent could alter the sensitivity of to , impacting the within-season variability and hence predictability of . |
Walsh J. E., 2014: Intensified warming of the Arctic: Causes and impacts on middle latitudes.Global and Planetary Change,117,52-63, 2014. 03. 003.https://doi.org/10.1016/j.gloplacha.10.1016/j.gloplacha.2014.03.0030492af2361aef1eb6ba44877938ed087http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0921818114000575http://linkinghub.elsevier.com/retrieve/pii/S0921818114000575Over the past half century, the Arctic has warmed at about twice the global rate. The reduction of sea ice and snow cover has contributed to the high-latitude warming, as the maximum of the amplification during autumn is a fingerprint of the ice-albedo feedback. There is evidence that atmospheric water vapor, a greenhouse gas, has increased in the Arctic over the past several decades. Ocean heat fluxes into the Arctic from the North Atlantic and North Pacific have also contributed to the Arctic warming through a reduction of sea ice. Observational and modeling studies suggest that reduced sea ice cover and a warmer Arctic in autumn may affect the middle latitudes by weakening the west-to-east wind speeds in the upper atmosphere, by increasing the frequency of wintertime blocking events that in turn lead to persistence or slower propagation of anomalous temperatures in middle latitudes, and by increasing continental snow cover that can in turn influence the atmospheric circulation. While these effects on middle latitudes have been suggested by some analyses, natural variability has thus far precluded a conclusive demonstration of an impact of the Arctic on mid-latitude weather and climate. |
Wen N., Z. Y. Liu, Q. Y. Liu, and C. Frankignoul, 2005: Observations of SST,heat flux and north Atlantic ocean-atmosphere interaction. Geophys. Res. Lett.,32,348-362,https://doi.org/10.1029/2005GL024871. |
World Meteorological Organization, 2012: WMO Statement on the Status of the Global Climate in 2011. WMO-No. 1085. World Meteorological Organization,10.1080/147032903100008900353ac1e4149d08c9110bddc245a4e8a02http%3A%2F%2Fwww.indiaenvironmentportal.org.in%2Freports-documents%2Fwmo-statement-status-global-climate-2011http://www.indiaenvironmentportal.org.in/reports-documents/wmo-statement-status-global-climate-2011This issue of WMO annual survey on weather and climate change provides evidence that 2011 had the highest global mean surface temperature levels in a La Ni09a year. Highlighting a number of climate extremes, it provides evidences of the major impacts of one of the strongest La Ni09a events of the past 60 years, among which are the significant flooding in South-East Asia and the major drought in East Africa. It also notes that Arctic sea ice continued its declining trend and returns on the destructive tornado seasons in the United States of America. |
Wu B. Y., J. Z. Su, and R. H. Zhang, 2011: Effects of autumn-winter Arctic sea ice on winter Siberian High.Chinese Science Bulletin,56,3220-3228, https://doi.org/10.1007/s11434-011-4696-4.10.1007/s11434-011-4696-4b20ccb11ea3bfc71e4feadc24effb114http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2Fs11434-011-4696-4http://link.springer.com/10.1007/s11434-011-4696-4The intensity of the winter Siberian High has significantly negative correlations with Arctic sea ice concentration anomalies from the previous autumn to winter seasons in the Eastern Arctic Ocean and Siberian marginal seas. Our results indicate that autumn- winter Arctic sea ice concentration and concurrent sea surface temperature anomalies are responsible for the winter Siberian High and surface air temperature anomalies over the mid-high latitudes of Eurasia and East Asia. Numerical experiments also support this conclusion, and consistently show that the low sea ice concentration causes negative surface air temperature anomalies over the mid-high latitudes of Eurasia. A mechanism is proposed to explain the association between autumn-winter sea ice concentration and winter Siberian High. Our results also show that September sea ice concentration provides a potential precursor for winter Siberian High that cannot be predicted using only tropical sea surface temperatures. In the last two decades (19902009), a strengthening trend of winter Siberian High along with a decline trend in surface air temperature in the mid-high latitudes of the Asian Continent have favored the recent frequent cold winters over East Asia. The reason for these short-term trends in winter Siberian High and surface air temperature are discussed. |
Wu B. Y., R. H. Zhang, R. D'Arrigo, and J. Z. Su, 2013: On the relationship between winter sea ice and summer atmospheric circulation over Eurasia.J. Climate,26,5523-5536, https://doi.org/10.1175/JCLI-D-12-00524.1.10.1175/JCLI-D-12-00524.16fe9af8baa73eb1f5fe21a8a7a354eb0http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F262007320_On_the_Relationship_between_Winter_Sea_Ice_and_Summer_Atmospheric_Circulation_over_Eurasia%3Fev%3Dprf_cithttp://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00524.1Using NCEP-NCAR reanalysis and Japanese 25-yr Reanalysis (JRA-25) data, this paper investigates the association between winter sea ice concentration (SIC) in Baffin Bay southward to the eastern coast of Newfoundland, and the ensuing summer atmospheric circulation over the mid- to high latitudes of Eurasia. It is found that winter SIC anomalies are significantly correlated with the ensuing summer 500-hPa height anomalies that dynamically correspond to the Eurasian pattern of 850-hPa wind variability and significantly influence summer rainfall variability over northern Eurasia. Spring atmospheric circulation anomalies south of Newfoundland, associated with persistent winter-spring SIC and a horseshoe-like pattern of sea surface temperature (SST) anomalies in the North Atlantic, act as a bridge linking winter SIC and the ensuing summer atmospheric circulation anomalies over northern Eurasia. Indeed, this study only reveals the association based on observations and simple simulation experiments with SIC forcing. The more precise mechanism for this linkage needs to be addressed in future work using numerical simulations with SIC and SST as the external forcings. The results herein have the following implication: Winter SIC west of Greenland is a possible precursor for summer atmospheric circulation and rainfall anomalies over northern Eurasia. |
Wu B. Y., J. Z. Su, and R. D'Arrigo, 2015: Patterns of Asian winter climate variability and links to Arctic sea ice.J. Climate,28,6841-6858, https://doi.org/10.1175/JCLI-D-14-00274.1.10.1175/JCLI-D-14-00274.1f21c3c8b63a980f10e5d30bd27c73078http%3A%2F%2Fcpfd.cnki.com.cn%2FArticle%2FCPFDTOTAL-ZGQX201510004011.htmhttp://journals.ametsoc.org/doi/10.1175/JCLI-D-14-00274.1This paper describes two dominant patterns of Asian winter climate variability: the Siberian high(SH) pattern and the Asia-Arctic(AA) pattern. The former depicts atmospheric variability closely associated with the intensity of the Siberian high, and the latter characterizes the teleconnection pattern of atmospheric variability between Asia and the Arctic, which is distinct from the Arctic Oscillation(AO). The AA pattern plays more important roles in regulating winter precipitation and the 850 h Pa meridional wind component over East Asia than the SH pattern, which controls surface air temperature variability over East Asia. In the Arctic Ocean and its marginal seas, sea ice loss in both autumn and winter could bring the positive phase of the SH pattern, or cause the negative phase of the AA pattern. The latter corresponds to a weakened East Asian winter monsoon(EAWM) and enhanced winter precipitation in the mid-latitudes of the Asian continent and East Asia. For the SH pattern, sea ice loss in the prior autumn emerges in the Siberian marginal seas, and winter loss mainly occurs in the Barents Sea,Labrador Sea, and Davis Strait. For the AA pattern, sea ice loss in the prior autumn is observed in the Barents-Kara Seas, the western Laptev Sea, and the Beaufort Sea, and winter loss only occurs in some areas of the Barents Sea, the Labrador Sea, and Davis Strait. Simulation experiments with observed sea ice forcing also support that Arctic sea ice loss may favor frequent occurrence of the negative phase of the AA pattern. The results also imply that the relationship between Arctic sea ice loss and winter atmospheric variability over East Asia is unstable, which is a challenge for predicting the EAWM based on Arctic sea ice loss. |
Wu B. Y., K. Yang, and J. A. Francis, 2016: Summer Arctic dipole wind pattern affects the winter Siberian High.Int. J. Climatol.,36,4187-4201, https://doi.org/10.1002/joc.4623.10.1002/joc.462399f07c0177ca4fcfa796552260943e95http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjoc.4623%2Fpdfhttp://doi.wiley.com/10.1002/joc.4623ABSTRACT This study investigates the relationship between the summer [June–July–August (JJA)] Arctic dipole wind pattern and the following winter [December–January–February (DJF)] Siberian High. It is found that the summer Arctic dipole wind pattern is not confined only to the Arctic region; it spans the large domain north of 20°N. The negative phase of this wind pattern depicts an anomalous anticyclone over the Arctic Ocean and its marginal seas, except for the Barents-Kara seas where an anomalous cyclone is dominant.This wind pattern is significantly correlated with the strength of the Siberian High during the following winter and with the frequency of extreme cold events over East Asia during the winters of 1979–2014. The relationship of this wind pattern with the winter Siberian High has strengthened over the past decades, particularly since the late 1980s. The more robust relationship coincides with significant changes in the winter atmospheric circulation and frequent occurrences of the negative phase of this wind pattern, which dynamically contributes to low September sea ice extent. The present study's results suggest that autumn Arctic sea ice provides a link between this wind pattern and climate variability over East Asia during the following winter.Results of simulation experiments suggest that (1) autumn sea ice loss favors the occurrence of a stronger East Asian winter monsoon; (2) the summer Arctic dipole wind pattern modulates winter atmospheric responses to sea ice loss, and the negative phase of this wind pattern enhances the negative feedback of Arctic sea ice loss on winter atmospheric variability over Eurasia and North America. These simulation experiments also imply that complex and varying summer circulation patterns obscure linkages between sea ice loss and large-scale circulation responses over Eurasia. Isolation of the summer Arctic dipole wind pattern, however, provides a potential precursor for the seasonal prediction of winter surface air temperature in a populous region of the world. |
Wu Q. G., X. D. Zhang, 2010: Observed forcing-feedback processes between Northern Hemisphere atmospheric circulation and Arctic sea ice coverage,J. Geophys. Res.,115,D14119, https://doi.org/10.1029/2009JD013574.10.1029/2009JD0135745cb701e755bfe153ab260b7fe9b6b422http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2009JD013574%2Fpdfhttp://doi.wiley.com/10.1029/2009JD013574A lagged maximum covariance analysis is applied to investigate linear covariability between monthly sea ice concentration (SIC) and atmosphere circulation in the Northern Hemisphere. The dominant signal is the atmospheric forcing of SIC anomalies throughout the year, but a wintertime atmospheric signal resembling the negatively polarized Arctic Oscillation/North Atlantic Oscillation is significantly correlated with persistently reduced SIC anomalies in the North Atlantic and Pacific sides of Arctic Shelf seas up to the preceding summer. The leading time of SIC anomalies provides an implication for skillful predictability of wintertime atmospheric variability. |
Xie P. P., P. A. Arkin, 1997: Global precipitation: A 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs. Bull. Amer. Meteor. Soc., 78, 2539-2558, https://doi.org/10.1175/1520-0477(1997)078<2539:GPAYMA>2.0,CO;2.10.1175/1520-0477(1997)078<2539:GPAYMA>2.0.CO;2http://journals.ametsoc.org/doi/abs/10.1175/1520-0477%281997%29078%3C2539%3AGPAYMA%3E2.0.CO%3B2 |