基于1979—2021年的ERA5再分析资料,研究了副极地海洋锋区(Subarctic Frontal Zone,SAFZ)海温(Sea Surface Temperature,SST)异常相关的冬季海气相互作用过程及其影响次年冬季厄尔尼诺(El Ni o)的机制。研究表明,冬季SAFZ的特征海气异...基于1979—2021年的ERA5再分析资料,研究了副极地海洋锋区(Subarctic Frontal Zone,SAFZ)海温(Sea Surface Temperature,SST)异常相关的冬季海气相互作用过程及其影响次年冬季厄尔尼诺(El Ni o)的机制。研究表明,冬季SAFZ的特征海气异常表现为大尺度的SST暖异常与偶极型的大气环流异常。在SAFZ海气相互作用过程中,海洋首先通过直接的非绝热加热影响低层大气斜压性,随后通过间接的瞬变涡旋反馈使相当正压的位势高度异常在整个冬季内维持。其中,南部的气旋式环流异常通过减弱副热带的平均信风激发太平洋经向模态(Pacific Meridional Mode,PMM)与风—蒸发—SST(Wind-Evaporation-SST,WES)反馈,从而使中纬度SST暖异常南传至热带太平洋中部,随后导致El Ni o发生。然而,并非所有的SAFZ暖异常事件都能激发次年冬季的El Ni o,中纬度海气耦合异常的初始配置及同期热带太平洋的表现情况将对中纬度信号南传至热带的过程产生较大的影响。展开更多
Based on 60-year （1951-2010） reanalysis data of the National Oceanic and Atmospheric Administration and extended reconstructed sea surface temperatures, a detailed investigation was conducted to explore the midwinte...Based on 60-year （1951-2010） reanalysis data of the National Oceanic and Atmospheric Administration and extended reconstructed sea surface temperatures, a detailed investigation was conducted to explore the midwinter storm track changes over the North Pacific. The root- mean-square （rms） of subweekly （2.5-6 days） transient of 300 hPa geopotential height field was calculated to represent the storm track. A decadal abruption occurred in 1982/1983, according to the Mann-Kendall test result. The first two Empirical Orthogonal Function （EOF） spatial patterns of the North Pacific storm track during P1 （1955-1982） and P2 （1983-2010） revealed opposite results：The EOF1 during P1 and the EOF2 during P2 revealed changes of intensity of the midwinter storm track in the North Pacific, whereas the EOF2 during P1 and the EOF1 during P2 exhibited a southward/northward shift of its central axis. In addition, pronounced differences in the thermal influence of the ocean on the storm track during P1 and P2 existed. A strong and sustained ENSO signal contributed to a storm track variation through the westerly jet from1955 to 1982, as the storm track was observed to strengthen and shift equatorward during El Ni6o events. From 1983 to 2010, an apparent sea temperature frontal zone at approximately 40°N and the associated near-surface baroclinicity resulted in the organization of a prominent mid-latitude storm track throughout the depth of the troposphere.展开更多
文摘基于1979—2021年的ERA5再分析资料,研究了副极地海洋锋区(Subarctic Frontal Zone,SAFZ)海温(Sea Surface Temperature,SST)异常相关的冬季海气相互作用过程及其影响次年冬季厄尔尼诺(El Ni o)的机制。研究表明,冬季SAFZ的特征海气异常表现为大尺度的SST暖异常与偶极型的大气环流异常。在SAFZ海气相互作用过程中,海洋首先通过直接的非绝热加热影响低层大气斜压性,随后通过间接的瞬变涡旋反馈使相当正压的位势高度异常在整个冬季内维持。其中,南部的气旋式环流异常通过减弱副热带的平均信风激发太平洋经向模态(Pacific Meridional Mode,PMM)与风—蒸发—SST(Wind-Evaporation-SST,WES)反馈,从而使中纬度SST暖异常南传至热带太平洋中部,随后导致El Ni o发生。然而,并非所有的SAFZ暖异常事件都能激发次年冬季的El Ni o,中纬度海气耦合异常的初始配置及同期热带太平洋的表现情况将对中纬度信号南传至热带的过程产生较大的影响。
基金supported by The National Natural Science Foundation of China[grant number 41421004]
文摘Based on 60-year （1951-2010） reanalysis data of the National Oceanic and Atmospheric Administration and extended reconstructed sea surface temperatures, a detailed investigation was conducted to explore the midwinter storm track changes over the North Pacific. The root- mean-square （rms） of subweekly （2.5-6 days） transient of 300 hPa geopotential height field was calculated to represent the storm track. A decadal abruption occurred in 1982/1983, according to the Mann-Kendall test result. The first two Empirical Orthogonal Function （EOF） spatial patterns of the North Pacific storm track during P1 （1955-1982） and P2 （1983-2010） revealed opposite results：The EOF1 during P1 and the EOF2 during P2 revealed changes of intensity of the midwinter storm track in the North Pacific, whereas the EOF2 during P1 and the EOF1 during P2 exhibited a southward/northward shift of its central axis. In addition, pronounced differences in the thermal influence of the ocean on the storm track during P1 and P2 existed. A strong and sustained ENSO signal contributed to a storm track variation through the westerly jet from1955 to 1982, as the storm track was observed to strengthen and shift equatorward during El Ni6o events. From 1983 to 2010, an apparent sea temperature frontal zone at approximately 40°N and the associated near-surface baroclinicity resulted in the organization of a prominent mid-latitude storm track throughout the depth of the troposphere.
