Impact of Assimilating Satellite Microwave Radiance on Tropical Cyclone Rapid Intensification Forecasting

在过去的15-20年里，对热带气旋运动的认识和预测取得了显著而稳定的进展。相比之下，在同一时期，强度预测只取得了适度的改进。本研究的主要目的是通过将卫星微波观测资料同化到大气预报模式中，提高对热带气旋强度变化的认识和预测。与可见光和红外通道观测不同的是，微波卫星数据传递了来自云层/降水层深处的特别丰富的信息，因此可以反映tc内水成物的分布。这使得微波观测在多云和多雨的TC地区特别有利。目前运行的许多气象卫星都携带微波频率的传感器。频率低于80 GHz的被动辐射观测对云液和雨滴较为敏感，而频率较高的被动辐射观测对云冰、雪花和霰较为敏感。在这个项目中，我们研究了如何将这些卫星微波观测有效地吸收到飓风预报模型（WRF和MM5）中，以提供对tc内云冰、雪、云液和雨滴分布的改进分析，这反过来可能对飓风强度预报产生积极影响。知识的优点。将开发新的有效方法，将这些水文气象敏感资料应用于不同分辨率的TC分析和预报。特别是，我们将：(i)发展和完善微波辐射的正演观测算子，通过与观测资料进行模式验证；（ii）为这些数据设计和测试有效的质量控制算法；（iii）将新的观测操作员和卫星微波数据纳入飓风数据同化系统；（iv）评估冰、雪、液态水和雨滴的准确分析在TC快速增强预报中的作用。更广泛的影响。该研究活动将产生重大的科学、技术和社会影响。改进飓风强度和对流过程的预报是重要的，也是具有挑战性的。评估卫星水文气象数据对这些预报的影响以及开发利用这些数据的新技术将促进飓风研究和预报的科学。这项工作还将通过最大限度地减少飓风造成的损害来造福社会。这项研究活动将培养两名研究生。

Significant and steady progress has been made in understanding and predicting tropical cyclone (TC) motion over the past 15-20 years. In contrast, only modest improvements in intensity prediction have been made over the same period. The primary objective of this study is to improve understanding and prediction of intensity change of tropical cyclones by assimilating satellite microwave observations into atmospheric prediction models. Unlike visible and infrared channel observations, microwave satellite data convey especially rich information originated from deep in the cloud/precipitation layers, therefore, reflect the distributions of hydrometeors within TCs. This makes microwave observations particularly advantageous in overcast and rainy TC areas.Many meteorological satellites that are currently in operation carry sensors operating at microwave frequencies. Passive radiance observations at frequencies lower than 80 GHz are more sensitive to cloud liquid and raindrops, while those at higher frequencies are more sensitive to cloud ice, snowflake, and graupel. In this project, we investigate how these satellite microwave observations can effectively be assimilated into hurricane forecasting models (WRF and MM5) to provide improve analyses of cloud ice, snow, cloud liquid, and raindrop distributions within TCs, which may, in turn, pose a positive impact on hurricane intensity forecasts. Intellectual merits. New and effective ways of applying these hydrometeor-sensitive data to TC analysis and forecast at different resolutions will be developed. In particular, we will: (i) develop and refine forward observation operators of microwave radiances through model verification with observations; (ii) design and test an effective quality control algorithm for these data; (iii) incorporate the new observation operators and the satellite microwave data into a hurricane data assimilation system; and (iv) assess the role of accurate analysis of ice, snow, liquid water, and raindrops in TC rapid intensification forecasts.Broader impacts. The research activity will impose a significant scientific, technological, and societal impact. Improvement of forecasts of hurricane intensity and convective processes are important and challenging. The assessment of the impact of the satellite hydrometeor data on these forecasts and the development of new techniques to use these data will advance the science of hurricane research and prediction. The work will also provide benefit to the society by minimizing damages caused by hurricanes. The research activity will train two graduate students.