Origin and Climatic Impact of Decadal-Scale, Eastward-Propagating Heat Content Anomalies in the North Pacific

2015 Fiscal Year Final Research Report

• Project/Area Number: 24540476
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: Taguchi Bunmei 国立研究開発法人海洋研究開発機構, アプリケーションラボ, 主任研究員 (80435841)
• Co-Investigator(Renkei-kenkyūsha): Sasaki Hideharu 国立研究開発法人海洋研究開発機構, アプリケーションラボ, 主任研究員 (50359220)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: 北太平洋十年規模変動 / 亜寒帯前線帯 / 黒潮続流 / spiciness / 海洋再解析データ / 海洋大循環モデル / 大気海洋結合モデル

Outline of Final Research Achievements

We investigated upper ocean heat content (OHC) variability, which is at the heart of natural climate variability on interannual-to-decadal time scales and thus provides climate memory and the source of decadal prediction skill, by jointly analyzing coupled GCM, an eddy resolving OGCM, and historical ocean analysis data. We found that spiciness (density-compensating temperature and salinity) variability is a major part of the OHC variability in the North Pacific and the density and spiciness variations explain the west- and eastward propagating signals, respectively, of OHC. Further analysis suggests that spiciness anomalies are caused by meridional displacement of the subarctic frontal zone. Specifically, spiciness anomalies are generated by large scale advection of mean spiciness gradient by anomalous current associated with the ocean frontal shifts.

Free Research Field

海洋物理学、気候学、大気海洋相互作用