Sensitivity study of the tropical Pacific precipitation anomalies
Shouwen Zhang1, Hua Jiang1, Hui Wang1,2, Ling Du3, and Dakui Wang11National Marine Environment Forecasting Center, State Oceanic Administration, Beijing 100081, China 2Key Laboratory of Research on Marine Hazards Forecasting, National Marine Environmental Forecasting Center, Beijing 100081, China 3Department of Oceanography, Ocean University of China, Qingdao 266100, China
Received: 13 Mar 2016 – Accepted for review: 16 Mar 2016 – Discussion started: 18 Mar 2016
Abstract. Climate model results have shown that precipitation in the tropical Pacific Ocean will change up to 15 % and 25 % in one century. In this paper, both reanalysis data and climate model are used to study the response of global ocean and atmosphere to precipitation anomalies in the tropical Pacific Ocean. It shows that positive precipitation anomalies could trigger an El Nino-like SSTA response, with warmer SST in the east tropical Pacific Ocean and slightly cooler SST in the west tropical Pacific Ocean. The zonal tropical ocean currents change significantly, of which the magnitudes and directions are mainly relying on the intensity of the precipitation anomalies. Through a wave train encompassing the whole Northern Hemisphere named as the Circumglobal Waveguide Pattern (CWP), the North Atlantic atmospheric circulation responds to the freshwater anomalies in a NAO-like pattern. The anomalous atmospheric circulation transport sea ice to the North Atlantic Ocean. The sea ice melts in summer and freshen the upper ocean, which makes the ocean more stable. It thus constrains vertical heat transport and makes the upper water cooler, forming a significant positive feedback mechanism.
Zhang, S., Jiang, H., Wang, H., Du, L., and Wang, D.: Sensitivity study of the tropical Pacific precipitation anomalies, Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-83, 2016.