黑潮延伸体海域海平面变化及其与比容变化的关系

SEA LEVEL CHANGE AND ITS RELATIONSHIP WITH STERIC SEA LEVEL IN THE KUROSHIO EXTENSION

使用AVISO高度计海面高度异常、SODA的温、盐和混合层深度资料,研究黑潮延伸体(KE)海域海平面变化及其与海水比容变化的关系。1993—2007年KE上游区海平面上升,而比容海平面则微弱下降;两者均具有年代际和年际变化,在年际尺度上的差异显著。KE下游区海平面年代际变化明显,而比容海平面表现出显著的年际变化特征。海水温度的垂直分布及其变化是KE区比容海平面变化的主要因素。KE上游区次表层海洋水体降温,海洋的深对流和层化则有利于次表层特征的维持,同期比容海平面下降显著。

The sea level change in the Kuroshio Extension （KE） and its relationship with the steric effect is analyzed t, using sea level anomaly （SLA） data from AVISO satellite altime- ter, SODA temperature and salinity of sea water as well as the mixing layer depth data. During 1993-2007, sea level had risen in the upstream KE region, but the steric sea level had decreased. Both of the sea level and steric sea level in the upstream KE region exhibited the decadal and inter-annual variations, while they distinguished greatly over the inter-annual timescale. In downstream KE region, the decadal sea level variation was prominent while the significant inter-annual variation of the steric sea level was found. The vertical distribution of temperature and its evolution were the major contributors to the steric sea level variation in KE area. The SODA temperature data and selected Argo CTD data illustrated that the subsurface temperature decreased in upstream KE region and caused the declined steric sea level. Deep convection and stratification of sea water were conducive to the maintenance of the subsurface steric processes.