Sensitivity to Madden–Julian Oscillation variations on heavy precipitation over the contiguous United States
Sensitivity to Madden–Julian Oscillation variations on heavy precipitation over the contiguous United States
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DOI：
10.1016/j.atmosres.2014.05.002
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发表时间：
2014-10
影响因子：
5.5
通讯作者：
Charles Jones;L. Carvalho
中科院分区：
文献类型：
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作者：
Charles Jones;L. Carvalho
马登-朱利安振荡（MJO）是热带气候系统中最显著的季节内变率模态，对强降水的发生和预报具有全球性的影响。本文探讨了在美国（CONUS）的降水的敏感性在一个案例研究（北方2004-05年冬季）。几次大风暴影响了美国西部和东部，造成了重大的经济和社会影响，包括生命损失。天气研究和预报（WRF）模式被用来进行实验，以测试的MJO振幅的显着性。控制模拟使用通过再分析观察到的MJO振幅，而振幅在扰动实验中被修改。WRF真实地模拟了CONUS上空的降水变率，尽管在美国西部和中西部上空出现了较大的偏差。将日降水量按西、中、东三个分区进行汇总，并分析了日降水量的频率分布。MJO振幅的增加导致中位数和四分位数范围的适度增加，以及极端（第90和第95次）降水量的大而强劲的增加。MJO振幅明显影响从热带太平洋和墨西哥湾到北美的水汽输送，提供潮湿的丰富的空气质量和动力强迫，有助于强降水。
The Madden–Julian Oscillation (MJO) is the most prominent mode of tropical intraseasonal variability in the climate system and has worldwide influences on the occurrences and forecasts of heavy precipitation. This paper investigates the sensitivity of precipitation over the contiguous United States (CONUS) in a case study (boreal 2004–05 winter). Several major storms affected the western and eastern CONUS producing substantial economic and social impacts including loss of lives. The Weather Research and Forecasting (WRF) model is used to perform experiments to test the significance of the MJO amplitude. The control simulation uses the MJO amplitude observed by reanalysis, whereas the amplitude is modified in perturbation experiments. WRF realistically simulates the precipitation variability over the CONUS, although large biases occur over the Western and Midwest United States. Daily precipitation is aggregated in western, central and eastern sectors and the frequency distribution is analyzed. Increases in MJO amplitude produce moderate increases in the median and interquartile range and large and robust increases in extreme (90th and 95th percentiles) precipitation. The MJO amplitude clearly affects the transport of moisture from the tropical Pacific and Gulf of Mexico into North America providing moist rich air masses and the dynamical forcing that contributes to heavy precipitation.