Variability of subduction rates of the subtropical North Pacific mode waters

• Published in: Chinese journal of oceanology and limnology Vol. 29; no. 5; pp. 1131 - 1141
• Main Author: 胡海波 刘秦玉 张媛 刘伟
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science Press 01.09.2011; Springer Nature B.V
• Subjects: Annual variations; Climate science; Climatology; Earth and Environmental Science; Earth Sciences; General circulation models; Heat flux; Heat transfer; Long-term changes; Marine; Mixed layer; Mixed layer depth; Ocean-atmosphere interaction; Oceanography; Outcrops; Physics; Potential vorticity; Subduction; Variability; Variation; Vorticity; Water circulation; Wind; Wind stress; Wind stress curl; 中亚热带; 俯冲; 北太平洋; 变异; 太平洋年代际振荡; 水域; 海洋动力过程; 速率; IN, North Pacific; ocean modeling; subtropical mode water; subduction rate; North Pacific
• ISSN: 0254-4059; 2096-5508; 1993-5005; 2523-3521
• DOI: 10.1007/s00343-011-0237-x

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.