After approaching 0℃owing to an Atlantic storm at the end of 2015,the Arctic temperature approached freezing again in 2022,indicating that Arctic daily warming events remain a concern.The NCEP/NCAR Reanalysis dataset...After approaching 0℃owing to an Atlantic storm at the end of 2015,the Arctic temperature approached freezing again in 2022,indicating that Arctic daily warming events remain a concern.The NCEP/NCAR Reanalysis dataset was used to investigate the influence of the NAO on the Arctic winter daily warming events induced by Atlantic storms,known as the Atlantic pattern-Arctic Rapid Tropospheric Daily Warming(Atlantic-RTDW)event.Atlantic-RTDW events are triggered by Atlantic storms that transport warm and humid air masses moving into the Arctic.Furthermore,an interdecadal change in the influence of NAO on Atlantic-RTDW-event frequency was observed around the mid-1980s.Specifically,before the mid-1980s(pre-transition period),500-hPa southerly(northerly)wind anomalies occupied the North Atlantic(NA)in the positive(negative)phase of NAO,which increased(decreased)the Atlantic-RTDW events occurrence by steering Atlantic storms into(away from)the Arctic;thus,the NAO could potentially influence the Atlantic-RTDW-event frequency.However,the relationship between the NAO and the Atlantic-RTDW-event frequency has weakened since the mid-1980s(post-transition period).In the post-transition period,such 500-hPa southerly(northerly)wind anomalies over the NA hardly existed in the positive(negative)phase of NAO,which was attributed to a stronger Atlantic Storm Track(AST)activity intensity than that in the pre-transition period.During this period,the strong AST induced an enhanced NAOrelated cyclone via transient eddy-mean flow interactions,resulting in the disappearance of southerly and northerly wind anomalies over the NA.展开更多
In this work,an index of tropical 20-90 d oscillation(intra-seasonal oscillation;ISO)in the western North Pacific(WNP)was determined via the combined empirical orthogonal function(EOF)method using daily outgoing longw...In this work,an index of tropical 20-90 d oscillation(intra-seasonal oscillation;ISO)in the western North Pacific(WNP)was determined via the combined empirical orthogonal function(EOF)method using daily outgoing longwave radiation(OLR)field data from the National Oceanic and Atmospheric Administration(NOAA),daily wind field data(at 850 hPa)from the European Centre for Medium-Range Weather Forecasts(ECMWF)and referencing the Madden-Julian oscillation(MJO)index proposed by Wheeler and Hendon.An in-depth investigation was conducted to examine the impact of the ISO on changes in tropical cyclone(TC)tracks in the WNP during different ISO phases.The research results indicate that during the easterly phase of the ISO,under the impact of the northeastern airflow of anti-cyclonic ISO circulation,the easterly airflow south of the western Pacific subtropical high is relatively weak,and TCs generated in the subtropical high tend to change their tracks east of 140°E;during the westerly phase,there is a relatively high probability that TCs change their tracks west of 140°E.This work also analyzed the ISO flow field situation in cases of typhoons and determined that the track of a tropical cyclone will experience a sudden right turn when the center of the ISO cyclonic(anti-cyclonic)circulation coincides with that of the cyclone.展开更多
To understand structural changes and forecast error,a case study of binary typhoons in the western North Pacific(WNP)of 2018 was investigated using best track and reanalysis data.Soulik was generated on August 16 and ...To understand structural changes and forecast error,a case study of binary typhoons in the western North Pacific(WNP)of 2018 was investigated using best track and reanalysis data.Soulik was generated on August 16 and Cimaron was generated on August 18,respectively.The 19 th typhoon Soulik and 20 th typhoon Cimaron co-existed from August 18 to 24 and approached each other.Soulik was located on the western side and Cimaron was located on the eastern side of the WNP.They were located approximately 1300 km from each other at 00 UTC August 22.The Soulik structure began changing around August 22 and became weak and slow,while Cimaron maintained its intensity,size,and moving speed.This observational evidence is likely caused by the binary interaction between two typhoons within a certain distance and environmental steering flow,such as the location of the North Pacific high and strong jet stream of the northern flank of the North Pacific high.Soulik was initially forecasted to make landfall and reach Seoul;however,its track changed from northward to northeastward from August 21 to 23 according to both official guidance and unified model(UM).Four global numerical weather prediction models forecasted different tracks of Soulik.UM and JGSM forecasted a northward track whereas ECMWF and GFS showed a northeastward track for 12 UTC August 21 through 12 UTC August 24.The latter models were similar to the best track.The track forecast error and spread of Soulik were larger than those of Cimaron.The mean absolute error of the maximum wind speed of Soulik was similar to the average of total typhoons in 2018.展开更多
采用NCEP(National Center of Environmental Prediction)的FNL(Final Analysis)数据以及卫星资料初步研究了1013号台风"鲇鱼"(MEGI),主要通过温度平流、涡度平流、Q矢量散度、高空急流、台风内部结构等方面,对台风移动路径...采用NCEP(National Center of Environmental Prediction)的FNL(Final Analysis)数据以及卫星资料初步研究了1013号台风"鲇鱼"(MEGI),主要通过温度平流、涡度平流、Q矢量散度、高空急流、台风内部结构等方面,对台风移动路径、强度突变和内部结构作出分析,尝试寻找到具有指示作用的要素。发现温度平流特别是低层的温度平流对于台风的移动有较明显的指示作用,暖平流的高值区引导台风向其运动,且台风的移动还受到中纬度西风槽和西太平洋副热带高压的作用。西风急流对于台风强度的影响也是不可忽视的,正是急流南部反气旋式切变的影响,为"鲇鱼"的第2次发展提供了条件。同时台风的内结构也对于其强度有着明显的影响,其内部涡旋Rossby波的存在对于能量的传递起到了重要的作用。通过此次尝试,希望能够对于台风移动路径、强度突变的预报提供帮助。展开更多
基金supported by National Natural Science Foundation of China(41675066)Anhui Provincial Natural Science Foundation(1908085MD108)。
文摘After approaching 0℃owing to an Atlantic storm at the end of 2015,the Arctic temperature approached freezing again in 2022,indicating that Arctic daily warming events remain a concern.The NCEP/NCAR Reanalysis dataset was used to investigate the influence of the NAO on the Arctic winter daily warming events induced by Atlantic storms,known as the Atlantic pattern-Arctic Rapid Tropospheric Daily Warming(Atlantic-RTDW)event.Atlantic-RTDW events are triggered by Atlantic storms that transport warm and humid air masses moving into the Arctic.Furthermore,an interdecadal change in the influence of NAO on Atlantic-RTDW-event frequency was observed around the mid-1980s.Specifically,before the mid-1980s(pre-transition period),500-hPa southerly(northerly)wind anomalies occupied the North Atlantic(NA)in the positive(negative)phase of NAO,which increased(decreased)the Atlantic-RTDW events occurrence by steering Atlantic storms into(away from)the Arctic;thus,the NAO could potentially influence the Atlantic-RTDW-event frequency.However,the relationship between the NAO and the Atlantic-RTDW-event frequency has weakened since the mid-1980s(post-transition period).In the post-transition period,such 500-hPa southerly(northerly)wind anomalies over the NA hardly existed in the positive(negative)phase of NAO,which was attributed to a stronger Atlantic Storm Track(AST)activity intensity than that in the pre-transition period.During this period,the strong AST induced an enhanced NAOrelated cyclone via transient eddy-mean flow interactions,resulting in the disappearance of southerly and northerly wind anomalies over the NA.
基金National Key Technology R&D Program(2012BAC22B00)National Natural Science Foundation of China(41375098)Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions
文摘In this work,an index of tropical 20-90 d oscillation(intra-seasonal oscillation;ISO)in the western North Pacific(WNP)was determined via the combined empirical orthogonal function(EOF)method using daily outgoing longwave radiation(OLR)field data from the National Oceanic and Atmospheric Administration(NOAA),daily wind field data(at 850 hPa)from the European Centre for Medium-Range Weather Forecasts(ECMWF)and referencing the Madden-Julian oscillation(MJO)index proposed by Wheeler and Hendon.An in-depth investigation was conducted to examine the impact of the ISO on changes in tropical cyclone(TC)tracks in the WNP during different ISO phases.The research results indicate that during the easterly phase of the ISO,under the impact of the northeastern airflow of anti-cyclonic ISO circulation,the easterly airflow south of the western Pacific subtropical high is relatively weak,and TCs generated in the subtropical high tend to change their tracks east of 140°E;during the westerly phase,there is a relatively high probability that TCs change their tracks west of 140°E.This work also analyzed the ISO flow field situation in cases of typhoons and determined that the track of a tropical cyclone will experience a sudden right turn when the center of the ISO cyclonic(anti-cyclonic)circulation coincides with that of the cyclone.
基金the“Research and Development for Numerical Weather Prediction”and“Support to Enhancement of Convergence Technology of Analysis and Forecast on Severe Weather”under Grant(KMA2018-00122)the Korea Meteorological Administration Research and Development Program
文摘To understand structural changes and forecast error,a case study of binary typhoons in the western North Pacific(WNP)of 2018 was investigated using best track and reanalysis data.Soulik was generated on August 16 and Cimaron was generated on August 18,respectively.The 19 th typhoon Soulik and 20 th typhoon Cimaron co-existed from August 18 to 24 and approached each other.Soulik was located on the western side and Cimaron was located on the eastern side of the WNP.They were located approximately 1300 km from each other at 00 UTC August 22.The Soulik structure began changing around August 22 and became weak and slow,while Cimaron maintained its intensity,size,and moving speed.This observational evidence is likely caused by the binary interaction between two typhoons within a certain distance and environmental steering flow,such as the location of the North Pacific high and strong jet stream of the northern flank of the North Pacific high.Soulik was initially forecasted to make landfall and reach Seoul;however,its track changed from northward to northeastward from August 21 to 23 according to both official guidance and unified model(UM).Four global numerical weather prediction models forecasted different tracks of Soulik.UM and JGSM forecasted a northward track whereas ECMWF and GFS showed a northeastward track for 12 UTC August 21 through 12 UTC August 24.The latter models were similar to the best track.The track forecast error and spread of Soulik were larger than those of Cimaron.The mean absolute error of the maximum wind speed of Soulik was similar to the average of total typhoons in 2018.
文摘采用NCEP(National Center of Environmental Prediction)的FNL(Final Analysis)数据以及卫星资料初步研究了1013号台风"鲇鱼"(MEGI),主要通过温度平流、涡度平流、Q矢量散度、高空急流、台风内部结构等方面,对台风移动路径、强度突变和内部结构作出分析,尝试寻找到具有指示作用的要素。发现温度平流特别是低层的温度平流对于台风的移动有较明显的指示作用,暖平流的高值区引导台风向其运动,且台风的移动还受到中纬度西风槽和西太平洋副热带高压的作用。西风急流对于台风强度的影响也是不可忽视的,正是急流南部反气旋式切变的影响,为"鲇鱼"的第2次发展提供了条件。同时台风的内结构也对于其强度有着明显的影响,其内部涡旋Rossby波的存在对于能量的传递起到了重要的作用。通过此次尝试,希望能够对于台风移动路径、强度突变的预报提供帮助。
