塔里木盆地沙尘辐射反馈对天气、沙尘浓度及沉降量的影响研究

Dust can affect weather and dust transport by scattering and absorbing solar/thermal radiation (direct effect) on a synoptic scale. An online coupled interactive weather-aerosol model is one of the useful tools to study the dust direct radiative feedback effect on dust cycles and meteorological factors. The radiative effects of dust aerosol on the meteorological fields and dust cycle are still uncertain because the related studies of dust radiation feedback have been focused mainly on each dust event and few combined analyses of the similar types of dust events occurred at the same location have not been made. In this research, a dust aerosol shortwave/longwave radiation scheme based on the refractive index of Tarim Basin will be couple into the state-of-the-art WRF-Chem dust model version 3.6. The validation of 3D distributions of the dust will be focused during simulations. The east-pathway dust-storm types occurred in the Tarim Basin over the past 10 years will be simulated under three simulation scenarios. We intend to propose a possible physic schematic diagram of the dust radiative feedback mechanism, and to quantify the impacts of dust radiation on the meteorological factors, dust concentrations and deposition, so as to improve the numerical predictability of the meteorological factors and dust cycles over the high frequency dust area.

沙尘气溶胶的直接辐射效应可影响沙尘多发区的天气和沙尘输送。既包含气象场对沙尘的输送作用，又考虑沙尘辐射对气象场影响的双向反馈天气－沙尘模式是研究沙尘辐射反馈机制较为有效的途径之一。目前对天气尺度上沙尘辐射反馈的模拟研究主要集中在单个沙尘过程，对某地区同类沙尘天气的综合分析工作较少，使得我们对沙尘辐射反馈效应机制及影响程度的认识有限。本项目拟将考虑了塔里木盆地沙尘辐射特性的长短波辐射方案加入WRF-Chem沙尘模式中，并在模拟中更重视沙尘垂直分布的验证，设计三种模拟试验方案，模拟近10年来我国塔里木盆地东向路径沙尘暴－重浮尘过程；总结沙尘辐射反馈的物理概念模型，定量给出沙尘辐射反馈对地面气温、沙尘浓度和沉降量的影响大小和变化范围，为认识沙尘辐射反馈机制和改善沙尘多发区的数值天气及沙尘预报提供科学依据。

沙尘气溶胶的直接辐射效应可影响沙尘多发区的天气和沙尘输送。既包含气象场对沙尘的输送作用，又考虑沙尘辐射对气象场影响的双向反馈天气－沙尘模式是研究沙尘辐射反馈机制较为有效的途径之一。目前对天气尺度上沙尘辐射反馈的模拟研究主要集中在单个沙尘过程，对某地区同类沙尘天气的综合分析工作较少，使得我们对沙尘辐射反馈效应机制及影响程度的认识有限。本项目将考虑了塔里木盆地沙尘辐射特性的长短波辐射方案成功加入到WRF-Chem沙尘模式中，设计了三种模拟试验方案，模拟了多次塔里木盆地东向路径沙尘过程。总结了天气尺度沙尘辐射反馈的三维分区物理概念图，指出了沙尘辐射影响中小尺度环流如山谷风的可能性，定量给出了沙尘辐射反馈的影响程度和范围，如影响地面气温（-1-2摄氏度）、沙尘浓度（增加10%-50%）及沉降量（增加10%-50%）。此外，基于塔里木盆地东向路径沙尘过程观测数据分析表明，沙尘天气时地面气温日较差和日均能见度相关性较好，能见度越低（沙尘浓度越高），气温日较差越小；和田受山谷风影响，其风向日变化明显且风速在白天和夜晚出现两个峰值。本项目的成功实施为认识沙尘辐射反馈机制和改善沙尘多发区的数值天气及沙尘预报提供了科学依据。