The Madden-Julian Oscillation and Predictability of Extreme Precipitation in the United States

摘要这项赠款下的研究考察了与马登-朱利安涛动(MJO)不同阶段有关的极端降水事件(即超过气候分布第90个百分位数的降雨量或降雪量)的可预测性变化。MJO是一种大尺度降水和环流异常，形成于印度洋上空，向东缓慢传播到赤道太平洋中部。PIS在他们之前的NSF赠款下的初步工作表明，预报的第一周和第二周美国大陆(CONUS)的极端降水预报技能在MJO生命周期的过程中有所不同，在MJO的第1、2、7和8阶段，CONUS陆地面积中存在显著技能的部分最大。这项拨款下的工作利用全球范围内天气研究和预报(WRF)模型的后播集成来探索技能差异。这项研究考察了预报技能，并试图了解MJO的相位和幅度影响极端降水预报技能的动力机制。这项研究通过与MJO行为相关的更好的长期天气预报的经济和社会价值，产生了更广泛的影响。初步工作估计了在上述MJO阶段改进极端降水预报技术的经济价值，这是东部沿海和中西部地区最大的阶段。此外，该项目还支持一名研究生和博士后研究人员，从而促进大气科学工作队伍的发展。该奖项的首席调查人员还参与了一系列外展活动，包括为高中生举办的为期六周的暑期研究计划，以及在国家地理的地理意识周期间举办的研讨会。

AbstractResearch under this grant examines changes in the predictability of extreme precipitation events (i.e. rainfall or snowfall exceeding the 90th percentile of the climatological distribution) associated with different phases of the Madden-Julian Oscillation (MJO). The MJO is a large-scale precipitation and circulation anomaly which forms over the Indian Ocean and propagates slowly eastward to the central equatorial Pacific. Preliminary work by the PIs under their previous NSF grant shows that the skill of extreme precipitation forecasts over the continental US (CONUS) for week one and week two of the forecast varies over the course of the MJO lifecycle, the portion of CONUS land area in which significant skill exists being largest in phases 1, 2, 7, and 8 of the MJO. Work under this grant explores the skill differences using hindcast integrations of the Weather Research and Forecasting (WRF) model on a global domain. The work examines the skill of forecasts and also seeks to understand the dynamical mechanisms through which the phase and amplitude of the MJO affect the skill of extreme precipitation forecasts.The research has broader impacts through the economic and social value of better long-range weather forecasts associated with MJO behavior. Preliminary work estimates the economic value of improvements in the skill of extreme precipitation forecasts in the above MJO phases, which is largest along the eastern seabord and in the midwest. In addition, the project supports a graduate student and postdoctoral researcher, thereby contributing to the development of the workforce in atmospheric science. The Principal Investigators for this award are also engaged in a number of outreach activities, including a six-week summer research program for high school students, and seminars conducted during National Geographic's Geography Awareness Week.