In recent decades,Arctic summer sea ice extent(SIE)has shown a rapid decline overlaid with large interannual variations,both of which are influenced by geopotential height anomalies over Greenland(GL-high)and the cent...In recent decades,Arctic summer sea ice extent(SIE)has shown a rapid decline overlaid with large interannual variations,both of which are influenced by geopotential height anomalies over Greenland(GL-high)and the central Arctic(CA-high).In this study,SIE along coastal Siberia(Sib-SIE)and Alaska(Ala-SIE)is found to account for about 65%and 21%of the Arctic SIE interannual variability,respectively.Variability in Ala-SIE is related to the GL-high,whereas variability in Sib-SIE is related to the CA-high.A decreased Ala-SIE is associated with decreased cloud cover and increased easterly winds along the Alaskan coast,promoting ice-albedo feedback.A decreased Sib-SIE is associated with a significant increase in water vapor and downward longwave radiation(DLR)along the Siberian coast.The years 2012 and 2020 with minimum recorded ASIE are used as examples.Compared to climatology,summer 2012 is characterized by a significantly enhanced GL-high with major sea ice loss along the Alaskan coast,while summer 2020 is characterized by an enhanced CA-high with sea ice loss focused along the Siberian coast.In 2012,the lack of cloud cover along the Alaskan coast contributed to an increase in incoming solar radiation,amplifying ice-albedo feedback there;while in 2020,the opposite occurs with an increase in cloud cover along the Alaskan coast,resulting in a slight increase in sea ice there.Along the Siberian coast,increased DLR in 2020 plays a dominant role in sea ice loss,and increased cloud cover and water vapor both contribute to the increased DLR.展开更多
利用Micaps、探空、卫星云图、雷达资料,对2011年9月1日凌晨和2012年9月27日下午在渤海西岸出现的强对流天气,从环流形势、不稳定能量、云图特征、雷达回波等方面进行了对比分析。结果表明:两次过程均出现了暴雨、大风、冰雹天气,9月1...利用Micaps、探空、卫星云图、雷达资料,对2011年9月1日凌晨和2012年9月27日下午在渤海西岸出现的强对流天气,从环流形势、不稳定能量、云图特征、雷达回波等方面进行了对比分析。结果表明:两次过程均出现了暴雨、大风、冰雹天气,9月1日凌晨影响系统为高空槽和切变线,灾害性天气以大风为主;9月27日下午影响系统为低涡和锋面,灾害性天气以暴雨、冰雹为主。两次过程渤海西岸上空均有一定的不稳定能量。亮度温度TBB越低表示强对流天气出现的几率越大,对流云团TBB小于-42oC预示有降水出现,TBB小于-52oC的区域与大雨或暴雨相对应。雷达回波强度大于35 d Bz区域与雷雨相对应,回波强度大于45 d Bz区域与冰雹、强降水天气对应较好。展开更多
基金the National Key Research and Development Program of China(Grant Nos.2021YFC2802504 and 2019YFC1509104)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.311021008).
文摘In recent decades,Arctic summer sea ice extent(SIE)has shown a rapid decline overlaid with large interannual variations,both of which are influenced by geopotential height anomalies over Greenland(GL-high)and the central Arctic(CA-high).In this study,SIE along coastal Siberia(Sib-SIE)and Alaska(Ala-SIE)is found to account for about 65%and 21%of the Arctic SIE interannual variability,respectively.Variability in Ala-SIE is related to the GL-high,whereas variability in Sib-SIE is related to the CA-high.A decreased Ala-SIE is associated with decreased cloud cover and increased easterly winds along the Alaskan coast,promoting ice-albedo feedback.A decreased Sib-SIE is associated with a significant increase in water vapor and downward longwave radiation(DLR)along the Siberian coast.The years 2012 and 2020 with minimum recorded ASIE are used as examples.Compared to climatology,summer 2012 is characterized by a significantly enhanced GL-high with major sea ice loss along the Alaskan coast,while summer 2020 is characterized by an enhanced CA-high with sea ice loss focused along the Siberian coast.In 2012,the lack of cloud cover along the Alaskan coast contributed to an increase in incoming solar radiation,amplifying ice-albedo feedback there;while in 2020,the opposite occurs with an increase in cloud cover along the Alaskan coast,resulting in a slight increase in sea ice there.Along the Siberian coast,increased DLR in 2020 plays a dominant role in sea ice loss,and increased cloud cover and water vapor both contribute to the increased DLR.
文摘利用Micaps、探空、卫星云图、雷达资料,对2011年9月1日凌晨和2012年9月27日下午在渤海西岸出现的强对流天气,从环流形势、不稳定能量、云图特征、雷达回波等方面进行了对比分析。结果表明:两次过程均出现了暴雨、大风、冰雹天气,9月1日凌晨影响系统为高空槽和切变线,灾害性天气以大风为主;9月27日下午影响系统为低涡和锋面,灾害性天气以暴雨、冰雹为主。两次过程渤海西岸上空均有一定的不稳定能量。亮度温度TBB越低表示强对流天气出现的几率越大,对流云团TBB小于-42oC预示有降水出现,TBB小于-52oC的区域与大雨或暴雨相对应。雷达回波强度大于35 d Bz区域与雷雨相对应,回波强度大于45 d Bz区域与冰雹、强降水天气对应较好。
