鄱阳湖湖效应降水的特征分析及其机理研究

Lake-effect precipitation is a weather phenomenon that induces or strengthens rainfall over a lake or at the downwind of a lake in certain conditions. Such phenomenon will increase the difficulties for the precipitation forecasts near the lake by locally inducing or enhancing large amount of rainfall. Although there are many fruitful results from foreign scientists, it is still at the very beginning in China. We cannot apply their results to China because the geographical environments and atmospheric conditions are quite different from those in China. Thus the corresponding research is still an important issue to be resolved nowadays. The present study targets at the largest freshwater lake in China, the.Poyang Lake, to investigate its lake-effect precipitation. Through statistical analysis, the characteristics (frequency, seasonal variation, diurnal variation, et al.) and environmental conditions (weather patterns, temperature difference between lake and land, sensible heat flux, latent heat flux, et al.) of the Poyang lake-effect precipitation will be revealed in detail. The corresponding mechanism will also be investigated through diagnostic analysis, as well as numerical simulations. The analyzed results will not only help to promote the forecast skill of precipitation near Poyang lake, but also enrich the contents of mesoscale meteorology in China.

湖效应降水是指在一定条件下湖泊在其上空或下风侧激发或加强降水的特殊天气过程，它不仅会造成（或加强）湖区暴雨洪涝灾害，还给湖区降水预报带来了困难。对其特征和机理的研究，国外科学家已经取得了一些成果，但国内还处于起步阶段。由于地理环境和大气环流背景的不同，国外研究成果很难直接借鉴，国内湖效应降水的特征和机理仍然是一个亟待解决的关键科学问题。本项目拟针对我国最大的淡水湖鄱阳湖，利用雷达、GPS/MET、湖区外场试验等大量一手观测资料和大气环流资料，分析鄱阳湖湖效应降水过程的多时间尺度变化、回波分布形态等特征，找出鄱阳湖湖效应降水发生的有利环境条件（大气环流背景、湖陆温差等）。然后进行动热力诊断分析和一系列的敏感性数值试验，揭示不同类型（激发或加强）鄱阳湖湖效应降水的形成和演变机制。其结果不仅可以为提升鄱阳湖区降水的预报提供新的科学依据，还可丰富我国中小尺度气象学的内容。

湖效应降水是湖区的特殊天气，不仅常常诱发或加强暴雨，还给湖区天气预报带来困难。本项目利用南昌多普勒天气雷达、探空、GPS/MET、自动气象站、铁塔等大量一手观测资料和大气环流资料，建立了我国最大淡水湖鄱阳湖的湖应降水数据集，总结出了鄱阳湖湖效应降水的气候特征，归纳出了有利于鄱阳湖湖效应降水发生的环境条件，弄清楚了鄱阳湖对区域温度和大气可降水量的影响；结合高分辨率中尺度数值（WRF）模式，揭示了鄱阳湖加强对过境对流天气和激发孤立湖效应降水的具体过程和物理机制，找出了WRF模式中对鄱阳湖湖效应降水模拟较好的陆面过程和边界层参数化方案，发现了鄱阳湖湖体水温变化对湖效应降水的具体影响过程和规律。研究结果不仅加深了对我国内陆湖泊影响区域天气气候的科学认识，还为鄱阳湖区降水的预报提供了科技支撑。