This paper evaluates a representation of winter stratospheric circulation in the Antarctic that is based on CRA-40, a 40-year global reanalysis dataset released by the China Meteorological Administration, and compares...This paper evaluates a representation of winter stratospheric circulation in the Antarctic that is based on CRA-40, a 40-year global reanalysis dataset released by the China Meteorological Administration, and compares it with representations based on two other state-of-the-art reanalysis datasets: the fifth-generation atmospheric reanalysis provided by the European Centre for Medium-Range Weather Forecasts(ERA-5) and the Modern-Era Retrospective analysis for Research and Applications, version 2(MERRA-2). In terms of climatology, we find that CRA-40 portrays a stronger and colder polar vortex in the middle and lower stratosphere than ERA-5, but a weaker and warmer one than MERRA-2. However, disagreement among the three reanalyses is confined mainly to the period before1999, and is largely reduced after that time. On the interannual timescale, portrayals of the intensity and area of the 10-hPa polar vortex are quite consistent among the three reanalyses, with correlation coefficients greater than 0.9 between each pair of reanalyses. In addition, the central dates of most sudden stratospheric deceleration(SSD) events at 10 hPa in the three reanalyses differ by less than one day, indicating that CRA-40 is also highly consistent with the other two reanalysis datasets regarding daily evolution. Our analyses suggest that CRA-40 performs comparably to ERA-5 and MERRA-2 in characterizing winter circulation in the Antarctic middle and lower stratosphere.展开更多
Recently,the China Meteorological Administration(CMA)released a new Global Atmospheric Reanalysis(CRA-40)dataset for the period 1979−2018.In this study,surface relative humidity(RH)from CRA-40 and other current reanal...Recently,the China Meteorological Administration(CMA)released a new Global Atmospheric Reanalysis(CRA-40)dataset for the period 1979−2018.In this study,surface relative humidity(RH)from CRA-40 and other current reanalyses(e.g.,CFSR,ERA5,ERA-Interim,JRA-55,and MERRA-2)is comprehensively evaluated against homogenized observations over China.The results suggest that most reanalyses overestimate the observations by 15%−30%(absolute difference)over the Tibetan Plateau but underestimate the observations by 5%−10%over most of northern China.The CRA-40 performs relatively well in describing the long-term change and variance seen in the observed surface RH over China.Most of the reanalyses reproduce the observed surface RH climatology and interannual variations well,while few reanalyses can capture the observed long-term RH trends over China.Among these reanalyses,the CFSR does poorly in describing the interannual changes in the observed RH,especially in Southwest China.An empirical orthogonal function(EOF)analysis also suggests that the CRA-40 performs better than other reanalyses to capture the first two leading EOF modes revealed by the observations.The results of this study are expected to improve understanding of the strengths and weaknesses of the current reanalysis products and thus facilitate their application.展开更多
The Asian subtropical westerly jet(AWJ)exerts crucial influences on Eurasian continent weather and climate.This paper analyzes the advantages and limitations of CRA-40,which is China's first generation 40-yr(1979...The Asian subtropical westerly jet(AWJ)exerts crucial influences on Eurasian continent weather and climate.This paper analyzes the advantages and limitations of CRA-40,which is China's first generation 40-yr(1979–2018)global atmosphere and land reanalysis product,in describing the characteristics of AWJ,compared with the ECMWF Reanalysis version 5(ERA5)and NCEP Climate Forecast System Reanalysis(CFSR).The results show a close agreement across the three reanalyses on the whole.(1)In terms of climatology,overall differences of 200-h Pa zonal wind across the three reanalyses are within±0.5 m s^(-1)(i.e.,±2%).Large differences with maxima of±2 m s^(-1)(±5%)appear over the Iranian Plateau and south of the Tibetan Plateau in the mid–upper troposphere in winter.(2)For seasonal cycle,the position and intensity of the AWJ centers in the three reanalyses are highly consistent,with correlation coefficient over 0.98.But there are some discrepancies in the zonal shift of the western AWJ center during the transition season.(3)On the interannual timescale,intensity of all AWJ centers varies consistently among the three reanalyses,while larger differences appear in their meridional displacement,especially in the eastern AWJ center.(4)For long-term variations,the three reanalyses all present a significant northward movement of the westerly jet axis in winter,and a southward displacement over central Asia(40°–80°E)and a northward migration over East Asia(80°–110°E)in summer.Thus,this study has provided confidence that CRA-40 has comparable performance with ERA5 and CFSR in depicting the characteristics of AWJ.展开更多
China Meteorological Administration(CMA) recently released its 40-yr(1979–2018) global Chinese reanalysis(CRA-40) dataset. To assess performance of the CRA-40 data in quantifying the regional water cycle, contributio...China Meteorological Administration(CMA) recently released its 40-yr(1979–2018) global Chinese reanalysis(CRA-40) dataset. To assess performance of the CRA-40 data in quantifying the regional water cycle, contributions of local and remote atmospheric moisture fluxes to precipitation in East China derived from CRA-40 are compared with those derived from the ECMWF reanalysis version 5(ERA-5). Observed precipitation and evaporation data are also used for validation. As for mean precipitation, CRA-40 matches the observation better in winter and spring than in summer, with a larger wet bias(1.41 mm day^(-1)) in summer than that in ERA-5(0.97 mm day^(-1)), particularly over South China. The conservation of atmospheric water vapor over East China measured by CRA-40 is comparable to that of ERA-5. Both reanalyses show a dominant role of the remote moisture transport in the East China precipitation.In comparison, the annual precipitation induced by the moisture influx from the west of the study domain in CRA-40 is 80 mm less than that in ERA-5. The recycling ratio of annual mean precipitation in CRA-40 is approximately21.1%, slightly larger than that in ERA-5(20.1%). The maximum difference of each hydrological component between the two datasets appears in the summer horizontal moisture influx(3.57 ×10^(7) kg s^(-1);ERA-5 is larger) and winter runoff(1.84 ×10^(7) kg s^(-1);CRA-40 is larger). CRA-40 shows better performance than ERA-5 in capturing the interannual variability of precipitation over East China, as evinced by a higher correlation coefficient with the observation(0.77 versus 0.33). The trend of summer precipitation since 2011 is better reproduced in CRA-40. Both reanalyses show prominent contribution of the southern moisture influx to the interannual variation of precipitation. This study demonstrates the reliability of CRA-40 in representing the hydrological cycle over East China and provides a useful reference for future application of CRA-40 in water cycle studies.展开更多
Assimilation of atmospheric motion vectors(AMVs)is important in the initialization of the atmospheric state in numerical weather prediction models,especially over oceans and at high latitudes where conventional data a...Assimilation of atmospheric motion vectors(AMVs)is important in the initialization of the atmospheric state in numerical weather prediction models,especially over oceans and at high latitudes where conventional data are sparse.This paper presents a detailed description of the pre-processing,quality assurance,and use of global AMVs in China’s first generation of the 40-yr(1979-2018)CRA global atmospheric reanalysis product.A new AMV archive is integrated from near real-time operational Global Telecommunication System data and reprocessed AMV datasets released or produced mainly during 2014-2016 according to a priority principle.To avoid the misuse of data with systematic quality problems,the observations of all 18 types of AMVs from 54 satellites are pre-evaluated over the whole time series.The pre-evaluation system developed by the CRA team is based on the NCEP Gridpoint Statistical Interpolation(GSI)three-dimensional variational assimilation system and the ERA-Interim reanalysis product.The AMVs in the new AMV archive are denser than the AMVs prepared for the Climate Forecast System Reanalysis product,the bias and root-mean-square values are smaller,and the time series are steadier.The new AMV archive is assimilated in the CRA product based on the NCEP GSI assimilation procedure and quality control configuration with reference to the pre-evaluation results.This is the first time that the reprocessed AMVs from Fengyun-2 satellites from June 2005 to July 2017 are assimilated in a reanalysis product.The assimilation features inspire confidence in the accuracy and stability of these data.The mean root-mean-square values of the observation minus analysis infrared,water vapor,and visible AMV were 1.5-3.4,2.7-3.6,and 1.3-2.1 m s-1,respectively.This experience of integrating,pre-evaluating,and assimilating AMV observations is valuable for the next generation of reanalysis products.展开更多
基金jointly supported by the NSFC project (42088101, 41975048, 42361144843, 42175069)。
文摘This paper evaluates a representation of winter stratospheric circulation in the Antarctic that is based on CRA-40, a 40-year global reanalysis dataset released by the China Meteorological Administration, and compares it with representations based on two other state-of-the-art reanalysis datasets: the fifth-generation atmospheric reanalysis provided by the European Centre for Medium-Range Weather Forecasts(ERA-5) and the Modern-Era Retrospective analysis for Research and Applications, version 2(MERRA-2). In terms of climatology, we find that CRA-40 portrays a stronger and colder polar vortex in the middle and lower stratosphere than ERA-5, but a weaker and warmer one than MERRA-2. However, disagreement among the three reanalyses is confined mainly to the period before1999, and is largely reduced after that time. On the interannual timescale, portrayals of the intensity and area of the 10-hPa polar vortex are quite consistent among the three reanalyses, with correlation coefficients greater than 0.9 between each pair of reanalyses. In addition, the central dates of most sudden stratospheric deceleration(SSD) events at 10 hPa in the three reanalyses differ by less than one day, indicating that CRA-40 is also highly consistent with the other two reanalysis datasets regarding daily evolution. Our analyses suggest that CRA-40 performs comparably to ERA-5 and MERRA-2 in characterizing winter circulation in the Antarctic middle and lower stratosphere.
基金supported by grants from the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDA19030402 and XDA19030401)the China Meteorological Administration Special Public Welfare Research Fund(Grant No.GYHY201506002),the National Natural Science Foundation of China(Grant Nos.41675094,41975115)+1 种基金the Natural Science Foundation of Shaanxi Province(Grant No.2021JQ-166),Chinese Universities Scientific Fund(Grant No.2452019224)Open Research Fund of Key Laboratory of the Loess Plateau Soil Erosion and Water Process and Control,Ministry of Water Resources of China(Grant No.HTGY202002).
文摘Recently,the China Meteorological Administration(CMA)released a new Global Atmospheric Reanalysis(CRA-40)dataset for the period 1979−2018.In this study,surface relative humidity(RH)from CRA-40 and other current reanalyses(e.g.,CFSR,ERA5,ERA-Interim,JRA-55,and MERRA-2)is comprehensively evaluated against homogenized observations over China.The results suggest that most reanalyses overestimate the observations by 15%−30%(absolute difference)over the Tibetan Plateau but underestimate the observations by 5%−10%over most of northern China.The CRA-40 performs relatively well in describing the long-term change and variance seen in the observed surface RH over China.Most of the reanalyses reproduce the observed surface RH climatology and interannual variations well,while few reanalyses can capture the observed long-term RH trends over China.Among these reanalyses,the CFSR does poorly in describing the interannual changes in the observed RH,especially in Southwest China.An empirical orthogonal function(EOF)analysis also suggests that the CRA-40 performs better than other reanalyses to capture the first two leading EOF modes revealed by the observations.The results of this study are expected to improve understanding of the strengths and weaknesses of the current reanalysis products and thus facilitate their application.
基金Supported by the Program of International S&T Cooperation of Chinese Academy of Sciences(2018YFE0196000)National Natural Science Foundation of China(41675076)。
文摘The Asian subtropical westerly jet(AWJ)exerts crucial influences on Eurasian continent weather and climate.This paper analyzes the advantages and limitations of CRA-40,which is China's first generation 40-yr(1979–2018)global atmosphere and land reanalysis product,in describing the characteristics of AWJ,compared with the ECMWF Reanalysis version 5(ERA5)and NCEP Climate Forecast System Reanalysis(CFSR).The results show a close agreement across the three reanalyses on the whole.(1)In terms of climatology,overall differences of 200-h Pa zonal wind across the three reanalyses are within±0.5 m s^(-1)(i.e.,±2%).Large differences with maxima of±2 m s^(-1)(±5%)appear over the Iranian Plateau and south of the Tibetan Plateau in the mid–upper troposphere in winter.(2)For seasonal cycle,the position and intensity of the AWJ centers in the three reanalyses are highly consistent,with correlation coefficient over 0.98.But there are some discrepancies in the zonal shift of the western AWJ center during the transition season.(3)On the interannual timescale,intensity of all AWJ centers varies consistently among the three reanalyses,while larger differences appear in their meridional displacement,especially in the eastern AWJ center.(4)For long-term variations,the three reanalyses all present a significant northward movement of the westerly jet axis in winter,and a southward displacement over central Asia(40°–80°E)and a northward migration over East Asia(80°–110°E)in summer.Thus,this study has provided confidence that CRA-40 has comparable performance with ERA5 and CFSR in depicting the characteristics of AWJ.
基金Supported by the National Natural Science Foundation of China (41675076)Program of International S&T Cooperation of Chinese Academy of Sciences (2018YFE0196000)Innovative Team Project of Lanzhou Institute of Arid Meteorology (GHSCXTD-2020-2)。
文摘China Meteorological Administration(CMA) recently released its 40-yr(1979–2018) global Chinese reanalysis(CRA-40) dataset. To assess performance of the CRA-40 data in quantifying the regional water cycle, contributions of local and remote atmospheric moisture fluxes to precipitation in East China derived from CRA-40 are compared with those derived from the ECMWF reanalysis version 5(ERA-5). Observed precipitation and evaporation data are also used for validation. As for mean precipitation, CRA-40 matches the observation better in winter and spring than in summer, with a larger wet bias(1.41 mm day^(-1)) in summer than that in ERA-5(0.97 mm day^(-1)), particularly over South China. The conservation of atmospheric water vapor over East China measured by CRA-40 is comparable to that of ERA-5. Both reanalyses show a dominant role of the remote moisture transport in the East China precipitation.In comparison, the annual precipitation induced by the moisture influx from the west of the study domain in CRA-40 is 80 mm less than that in ERA-5. The recycling ratio of annual mean precipitation in CRA-40 is approximately21.1%, slightly larger than that in ERA-5(20.1%). The maximum difference of each hydrological component between the two datasets appears in the summer horizontal moisture influx(3.57 ×10^(7) kg s^(-1);ERA-5 is larger) and winter runoff(1.84 ×10^(7) kg s^(-1);CRA-40 is larger). CRA-40 shows better performance than ERA-5 in capturing the interannual variability of precipitation over East China, as evinced by a higher correlation coefficient with the observation(0.77 versus 0.33). The trend of summer precipitation since 2011 is better reproduced in CRA-40. Both reanalyses show prominent contribution of the southern moisture influx to the interannual variation of precipitation. This study demonstrates the reliability of CRA-40 in representing the hydrological cycle over East China and provides a useful reference for future application of CRA-40 in water cycle studies.
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund (GYHY201506002)National Natural Science Foundation of China (92037000)+1 种基金National Innovation Project for Meteorological Science and Technology (CMAGGTD003-5)Balance Fund of the National Meteorological Information Centre (NMICJY202106)。
文摘Assimilation of atmospheric motion vectors(AMVs)is important in the initialization of the atmospheric state in numerical weather prediction models,especially over oceans and at high latitudes where conventional data are sparse.This paper presents a detailed description of the pre-processing,quality assurance,and use of global AMVs in China’s first generation of the 40-yr(1979-2018)CRA global atmospheric reanalysis product.A new AMV archive is integrated from near real-time operational Global Telecommunication System data and reprocessed AMV datasets released or produced mainly during 2014-2016 according to a priority principle.To avoid the misuse of data with systematic quality problems,the observations of all 18 types of AMVs from 54 satellites are pre-evaluated over the whole time series.The pre-evaluation system developed by the CRA team is based on the NCEP Gridpoint Statistical Interpolation(GSI)three-dimensional variational assimilation system and the ERA-Interim reanalysis product.The AMVs in the new AMV archive are denser than the AMVs prepared for the Climate Forecast System Reanalysis product,the bias and root-mean-square values are smaller,and the time series are steadier.The new AMV archive is assimilated in the CRA product based on the NCEP GSI assimilation procedure and quality control configuration with reference to the pre-evaluation results.This is the first time that the reprocessed AMVs from Fengyun-2 satellites from June 2005 to July 2017 are assimilated in a reanalysis product.The assimilation features inspire confidence in the accuracy and stability of these data.The mean root-mean-square values of the observation minus analysis infrared,water vapor,and visible AMV were 1.5-3.4,2.7-3.6,and 1.3-2.1 m s-1,respectively.This experience of integrating,pre-evaluating,and assimilating AMV observations is valuable for the next generation of reanalysis products.
