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Circulation Indices of the Aleutian Low Pressure System:Definitions and Relationships to Climate Anomalies in the Northern Hemisphere

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Advances in atmospheric sciences 2012年第5期29卷 1111-1118页

作者：王盘兴汪学良智海王玉坤孙晓娟 ministry of education key laboratory of meteorological disaster of cooperation of ministries and provincial governments and college of atmospheric sciences Nanjing University of Information Science and Technology Air Resources laboratory National Oceanic and Atmospheric AdministrationSilver Spring

In this study, a group of indices were defined regarding intensity （P）, area （S） and central position （λc, Фc） of the Aleutian low （AL） in the Northern Hemisphere in winter, using seasonal and monthly mean height field at 1000-hPa. These indices were calculated over 60 winter seasons from 1948/1949 to 2007/2008 using reanalysis data. Climatic and anomalous characteristics of the AL were analyzed based on these indices and relationships between the AL, and general circulations were explored using correlations between indicesP, λc, and Pacific SST, as well as Northern Hemisphere temperature and precipitation. The main results are these：（1） AL is the strongest in January, when the center shifts to the south and west of its climatological position, and it is the weakest in December when the center shifts to the north and east. （2） AL intensity （P） is negatively correlated with its longitude （λc）： a deeper low occurs toward the east and a shallower low occurs toward the west. On a decadal scale, the AL has been persistently strong and has shifted eastward since the 1970s, but reversal signs have been observed in recent years. （3） The AL is stronger and is located toward the east during strong E1 Nifio winters and vice versa during strong La Nifia years; this tendency is particularly evident after 1975. The AL is also strongly correlated with SST in the North Pacific. It intensifies and moves eastward with negative SST anomalies, and it weakens and moves westward with positive SST anomalies. （4） Maps of significance correlation between AL intensity and Northern Hemisphere temperature and rainfall resemble the PNA teleconnection pattern in mid-latitudes in the North Pacific and across North America. The AL and the Mongolian High are two permanent atmospheric pressure systems adjacent to each other during boreal winter over the middle and high latitudes in the Northern Hemisphere, but their relationships with the E1 Nifio/La Nifia events and with temperature and precipitat

关键词： circulation indices the Aleutian Low definitions and relationships climate anomalies

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Assessment of Historical Climate Trends of Surface Air Temperature in CMIP5 Models

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atmospheric and Oceanic Science Letters 2014年第2期7卷 137-142页

作者： FENG Xiao-Li ZHI Hai LIN Peng-Fei LIU Hai-Long ministry of education key laboratory of meteorological disaster of cooperation of ministries and provincial governments and college of atmospheric sciences Nanjing University of Information Science and Technology State key laboratory of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics (IAP)Chinese Academy of Sciences

This study assesses the historical climate trends of surface air temperature（SAT）, their spatial distributions, and the hindcast skills for SAT during 1901– 2000 from 24 Coupled Model Intercomparison Project Phase 5（CMIP5） models. For the global averaged SAT, most of the models（17/24） effectively captured the increasing trends（0.64°C/century for the ensemble mean） as the observed values（- 0.6°C/century） during the period of 1901–2000, particularly during a rapid warming period of 1970–2000 with the small model spread. In addition, most of the models（22/24） showed high hindcast skills（the correlation coefficient, R 〉 0.8）. For the spatial pattern of SAT, the models better simulated the relatively larger warming at the middle-to-high latitudes in the Northern Hemisphere than that in the Southern Hemisphere and the greater warming on the land than that in the ocean between 40°S and 40°N. The simulations underestimated the warming along some ocean boundaries but overestimated warming in the Arctic Ocean. Most of the coupled models were able to reproduce the large-scale features of SAT trends in most regions excluding Antarctica, some parts of the Pacific Ocean, the North Atlantic Ocean near Greenland, the southwestern Indian Ocean, and the Arctic Ocean. The outgoing longwave radiation（OLR） and incoming shortwave radiation（ISR） at the top of the atmosphere（TOA） and the downward longwave（LW） radiation and sensible heat flux at the surface had positive contributions to the increasing trends in most of the models.

关键词： CMIP5 surface air temperature trend warming

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Historical Trends in Surface Air Temperature Estimated by Ensemble Empirical Mode Decomposition and Least Squares Linear Fitting

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atmospheric and Oceanic Science Letters 2015年第1期8卷 10-16页

作者： LIN Peng-Fei FENG Xiao-Li LIU Juan-Juan State key laboratory of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics (IAP) Chinese Academy of Sciences meteorological Observatory Huangnan Tibetan Autonomous Prefecture of Qinghai Province ministry of education key laboratory of meteorological disaster of cooperation of ministries and provincial governments and college of atmospheric sciences Nanjing University of Information Science and Technology

Ensemble empirical mode decomposition(EEMD) and least squares linear fitting(LSLF) are applied to estimate the historical trends of surface air temperature(SAT) from observations and Coupled Model Intercomparison Project Phase 5(CMIP5) simulations during the period 1901–2005. The magnitudes of trends estimated by the two approaches are comparable. The trend calculated by the EEMD approach is larger than that by the LSLF approach in most(23/27) of the models during 1901–2005. During the slow warming period, the EEMD trend is smaller than the LSLF trend. The rootmean-square errors(RMSEs) between the raw and reconstructed times series by the LSLF approach are larger than those by the EEMD trend component and multi-decadal variability components during 1901–2005 in most of the models and observations. During 1901–70(or 1971–2005), the RMSEs between the raw and reconstructed times series by LSLF are larger than those by the EEMD trend component. In this sense, the EEMD trend is a better choice to obtain the climate trends in observations and CMIP5 models, especially for short time periods. This is because the trend estimated by LSLF cannot capture the internal variability and the cooling in some years. The estimated global warming rates(trend) are consistently larger(smaller) than those from observations in 11 of 27 CMIP5 models during 1901–2005 in the slow and rapid warming periods. This implies these 11 models have consistent responses to greenhouse gases for any period.

关键词： climate trend surface air temperature CMIP5 LSLF E

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Long-term surface air temperature trend and the possible impact on historical warming in CMIP5 models

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atmospheric and Oceanic Science Letters 2016年第3期9卷 153-161页

作者： LIN Peng-Fei FENG Xiao-Li ZHI Hai LIU Hai-Long WANG Li State key laboratory of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics(IAP) Chinese Academy of Sciences meteorological Observatory Huangnan Tibetan Autonomous Prefecture ministry of education key laboratory of meteorological disaster of cooperation of ministries and provincial governments and college of atmospheric sciences Nanjing University of Information Science and Technology Emergency and disaster Reduction Section Meteorological Bureau of Qinghai Province

Whether large trends exist in pre-industrial control （PICTL） runs is critically important for evaluating simulations of present climate change. This study examined the long-term trends in PICTL surface air temperature （SAT） in CMIP5 models. Small trends （〈0.06 ℃/100 year） in the globally averaged SAT （GASAT） exist in most CMIP5 models. Of these, positive （negative） trends result from positive （negative） net radiation fluxes at the TOA. This conclusion was further confirmed by the significant positive correlations between the TOA and the SAT tendency. The PICTL GASAT trends constitute less than 10% of the historical trends, indicating that such trends are of negligible importance in estimates of historical global warming in most models. Spatially, relative to the historical trends, the PICTL trends comprise a nontrivial fraction （〉20%） in the Southern Ocean between 50°S and 65°S and in the northern Atlantic and Pacific oceans north of 40°N, with large inter-model spread. The long-term behavior of SAT is significantly related to ocean circulation adjustment in the mid-high latitudes.

关键词： Climate drift CMIP5 historical warming trend

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Multi-scale variation characteristics of polar vortex at 10 hPa in the Southern Hemisphere

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Research in Cold and Arid Regions 2010年第1期2卷 73-81页

作者： LiPing Li JuHui Ma PanXing Wang Dong Guo MingKen Duan ShuXuan Guan ministry of education key laboratory of meteorological disaster of cooperation of ministries and provincial governments and College of Atmospheric Sciences Nanjing University of Information Science and Technology Nanjing Jiangsu 210044 China

By use of 1948-2007 NCEP/NCAR reanalysis monthly geopotential data, a set of circulation indices are defined to characterize the polar vortex at 10 hPa in the Southern Hemisphere, including area-（S）, intensity-（P） and centre position-（λc , φc） indices. Sea-sonal variation, interannual anomalies and their possible causes of 10 hPa polar vortex in the Southern Hemisphere are analyzed by using these indices, the relationship between 10 hPa polar vortex strength and the Antarctic Oscillation are analyzed as well. The results show that：（1） the polar region at 10 hPa in the Southern Hemisphere is controlled by anticyclone （cyclone） from Dec. to Jan. （from Mar. to Oct.）, Feb. and Nov. are circulation transition seasons. （2） Intensity index （P） and area index （S） of anticy-clone （cyclone） in Jan. （Jul.） show a significant spike in the late 1970s, the anticyclone （cyclone） enhances （weakens） from ex-tremely weak （strong） oscillation to near the climatic mean before a spike, anticyclone tends to the mean state from very strong oscillation and cyclone oscillates in the weaker state after the spike. （3） There is significant interdecadal change for the anticyclone center in Jan., while markedly interannual variation for cyclone center in July. （4） The ozone anomalies can cause the interannual anomaly of the polar anticyclone at 10 hPa in the Southern Hemisphere in Jan. （positive correlation between them）, but it is not related to the polar cyclone anomalies. （5） There is notable negative correlation between the polar vortex intensity index P and the Antarctic Oscillation index （AAOI）, thus AAOI can be represented by P.

关键词： circulation indices of polar vortex at 10 hPa climatic state anomalous state ozone anomaly Antarctic Oscillation

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