Life Cycle of Atmospheric Rivers: Identification and Climatological Characteristics
Life Cycle of Atmospheric Rivers: Identification and Climatological Characteristics
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DOI：
10.1029/2018jd029180
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发表时间：
2018-11
期刊：
影响因子：
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通讯作者：
Yang Zhou;Hyemi Kim;B. Guan
中科院分区：
文献类型：
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作者：
Yang Zhou;Hyemi Kim;B. Guan
大气河（AR）事件是由一系列时空相连的瞬时AR对象组成的强烈的极地水汽输送。本研究开发了一种新的基于目标的跟踪算法，旨在识别AR事件并研究其从起源到终止的生命周期。该算法识别持续时间、强度、传播速度和方向，以及AR事件在整个生命周期中的传播距离。将该跟踪算法应用于1979-2017年11月至3月的6小时柱积分水汽通量，重点关注北太平洋。大多数北太平洋AR事件起源于西北太平洋的亚热带地区，并在东北太平洋包括北美西部的高纬度地区结束。平均而言，持续时间超过72小时的长AR事件比持续时间少于24小时的短AR事件传播距离长7倍，强度更强。最后，开发了一个新的累积AR强度指数，该指数通过结合AR事件的数量、寿命和强度，总结了给定区域在一定时期内AR事件的总体影响。
An atmospheric river (AR) event is a strong poleward moisture transport that is composed of a series of spatiotemporally connected instantaneous AR objects. A new object‐based tracking algorithm is developed in this study, which aims to identify an AR event and investigate its life cycle from origin to termination. The algorithm identifies duration, intensity, propagation speed and direction, and the traveled distance throughout the life cycle of the AR event. The tracking algorithm is applied to 6‐hourly column‐integrated water vapor flux from November to March during the period of 1979–2017, with a focus on the North Pacific. Most North Pacific AR events originate in the subtropics over the Northwest Pacific and terminate at higher latitudes over the Northeast Pacific including western North America. On average, long AR events that last more than 72 hrs travel 7 times longer in distance and have stronger intensity than short AR events that last less than 24 hrs. Finally, a new accumulated AR intensity index is developed, which summarizes the overall impact of AR events over a given domain during a certain period by incorporating number, lifetime, and intensities of AR events.