The Study of Atmospheric Rivers over the Eastern Asian Region in Summers from 2001 to 2016

On Study of Atmospheric Rivers over the Eastern Asian Region in Summers from 2001 to 2016

Gang Fu ^*1,2， Shan Liu¹, Pengyuan Li¹

1. Department of Marine Meteorology, Ocean–Atmosphere Interaction and Climate Laboratory,

Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao, China

2. Division of Oceanic Dynamics and Climate, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China

ABSTRACT

Atmospheric River (AR) refers to a long, narrow and transient corridor of strong horizontal water vapor transport that is typically associated with a low-level jet stream ahead of the cold front of an extratropical cyclone which transports meridionally across the mid-latitudes (Zhu and Newell, 1998; Ralph et al., 2004; Ralph and Dettinger, 2011; Gimeno et al., 2014). Previous studies indicated that ARs mainly occurred over the Northeastern Pacific, the western coast of North America and Europe (Lackmann and Gyakum 1999; Neiman et al. 2008; Dettinger et al., 2011; Ralph and Dettinger, 2011; Ralph et al., 2011; Waliser et al., 2012; Payne and Magnusdottir, 2014; Ramos et al., 2014; Warner et al., 2015; Gao and Leung, 2016; Ralph et al., 2016). However, the investigations on ARs over the eastern Asian region were very rare. In this study, a new method of quantifying ARs over the eastern Asia region was put forward after a systematic investigation of some basic features of water vapor transport belt over the area 20ºN~55ºN, 95ºE~140ºE from 15 June to 31 July from 2001 to 2016 by using European Center for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis data and Multi-functional Transport Satellites-1R (MTSAT-1R) infrared channel albedo data provided by Kochi University of Japan. Totally, 134 ARs occurred in that period, and averagely 8.4 ARs occurred every year. The number of ARs, their duration time, intensity, length, width, ratio of length to width and other characteristics of ARs were documented and analyzed. Statistically, 101 ARs were in east-west orientation, and 33 ARs were in north-south orientation. Among of them, two typical ARs in east-west orientation, and two typical ARs in north-south orientation were investigated in detail. The synoptic analyses indicated that ARs in north-south orientation developed within the warm conveyor belt in the east of cyclone, while ARs in east-west orientation developed among the front between two cyclones, or developed between a low pressure and the subtropical high system. Finally, two schematic diagrams of ARs in east-west orientation and in north-south orientation were presented, respectively.

Acknowledgement

This study is supported by the Natural Science Foundation of China (41275049 and 41775042).

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* Professor Dr. Gang Fu, Department of Marine Meteorology, Ocean University of China, No. 238, Songling Road, Qingdao 266100, P. R. China. E-mail：fugang@ouc.edu.cn; fugangouc@qq.com