Variability of subduction rates of the subtropical North Pacific mode waters  

作　　者：胡海波 刘秦玉 张媛 刘伟 

机构地区：[1]School of Atmospheric Sciences, Nanjing University [2]Physical Oceanography Laboratory & Ocean-Atmosphere Interaction and Climate Laboratory, Ocean University of China [3]School of Atmospheric Sciences, Nanjing University of Information Science and Technology [4]Center for Climatic Research and Department of Atmospheric and Oceanic Sciences University of Wisconsin-Madison

出　　处：《Chinese Journal of Oceanology and Limnology》2011年第5期1131-1141,共11页中国海洋湖沼学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China (Nos. 40906005, 40830106, 40730953, GYHY201106017);the National Basic Research Program of China (973 Program) (No. 2010CB428504);the National Key Technologies Research and Development Program of China (No. 2009BAC51B01)

摘　　要：The climatology subduction rate for the entire Pacific is known, but the mechanism of interannual to decadal variation remains unclear. In this study, we calculated the annual subduction rates of three types of North Pacific subtropical mode waters using a general circulation model (LICOM1.0) for the period of 1958-2001. The model experiments focused on interannual variations of ocean dynamical processes under daily wind forcings and seasonal heat fluxes. The mode water formation region was defined by a potential vorticity minimum at outcrop locations. The model results show that two subduction rate maxima (>100 m/a) were located in the Subtropical Mode Water (STMW) and the Central Mode Water (CMW) formation regions. These regions are consistent with a climatologically calculated value. The subduction rate in the Eastern Subtropical Mode Water (ESTMW) formation region was smaller at about 75 m/a. The subduction rate shows clear interannual and decadal variations associated with oceanic dynamic variabilities. The average subduction rate of the STMW was much smaller during the period of 1981-1990 compared with other periods, while that of the CMW had a negative anomaly before 1975 and a positive anomaly after 1978. The variability agreed with Ekman and geostrophic advections and mixed layer depths. The interannual variability of the subduction rate for the ESTMW was smallest during 1970-1990, as a result of a weak wind stress curl. This paper explores how interannual signals from the atmosphere are stored in different parts of the ocean, and thus may contribute to a better understanding of feedback mechanisms for the Pacific Decadal Oscillation (PDO) event.The climatology subduction rate for the entire Pacific is known, but the mechanism of interannual to decadal variation remains unclear. In this study, we calculated the annual subduction rates of three types of North Pacific subtropical mode waters using a general circulation model （LICOM1.0） for the period of 1958-2001. The model experiments focused on interannual variations of ocean dynamical processes under daily wind forcings and seasonal heat fluxes. The mode water formation region was defined by a potential vorticity minimum at outcrop locations. The model results show that two subduction rate maxima （〉100 m/a） were located in the Subtropical Mode Water （STMW） and the Central Mode Water （CMW） formation regions. These regions are consistent with a climatologically calculated value. The subduction rate in the Eastern Subtropical Mode Water （ESTMW） formation region was smaller at about 75 m/a. The subduction rate shows clear interannual and decadal variations associated with oceanic dynamic variabilities. The average subduction rate of the STMW was much smaller during the period of 1981-1990 compared with other periods, while that of the CMW had a negative anomaly before 1975 and a positive anomaly after 1978. The variability agreed with Ekman and geostrophic advections and mixed layer depths. The interannual variability of the subduction rate for the ESTMW was smallest during 1970--1990, as a result of a weak wind stress curl. This paper explores how interannual signals from the atmosphere are stored in different parts of the ocean, and thus may contribute to a better understanding of feedback mechanisms for the Pacific Decadal Oscillation （PDO） event.

关 键 词：subduction rate North Pacific subtropical mode water ocean modeling 

分 类 号：P731.2[天文地球—海洋科学]