基于多种遥感手段的天山山区水汽垂直结构与空间分布研究

Tianshan Mountainous area is one of crucial regions about hydrological cycle and water resource in arid region of northwest China. Atmospheric water vapor plays a crucial role for climate, dynamics of weather system, atmosphere environment, hydrology and geodesy. It is very important to obtain the temporal and spatial variation of water vapor for monitoring and predicting the disastrous weathers (storm and hail ) related to the meso-and micro-scale systems. However, it has been unclear in the temporal and spatial variation of water vapor due to sparse observational sites and uncertainties in satellite retrievals and NCEP/NCAR reanalysis data . The scarcity in conventional water observation greatly restricts the development of refined forecast weather and the exploitation and utilization of cloud-water resource in Tianshan mountainous area. The purpose of this project will : 1) retrieval and compare satellite retrieval atmospheric water vapor data including FY2D,FY2E and MODIS with the precipitable water vapor (PWV) based on GPS ,the vertical water vapor profile based on the wind profiler radar and the microwave radiometer ; complete atmospheric water vapor retrievaling algorithm suit for use in Tianshan mountainous area;2) study the elaborate distribution characteristics of water vapor in combination with the technology of point and area; 3) reveal the vertical distribution of water vapor in Tianshan mountainous area using multi-remote sensing techniques; 4) analyse the relationship between water vapor and precipitation in Tianshan mountainous area;5) research on evolution water vapor transport during the heavy and classical rainfall . The project not only provides some bases for weather forecast, but also lay the foundation for further research the circulation of water vapor in Tianshan mountainous area .

天山山区是西北干旱区最重要的水分循环和水资源关键区域之一。由于该区域地形复杂、观测站点稀疏，长期以来，关于这一地区的水汽输送和时空分布状况、水汽分布与最大降水带的关系、不同天气条件下水汽垂直结构及演变特征等问题一直不清楚，在一定程度上制约了人们对这些科学问题的深入研究，也对山区强降水预报水平的提高和空中云水资源的合理开发利用造成了很多困难。本项目利用FY2D、FY2E及MODIS的卫星遥感数据，结合天山山区布设的13台地基GPS、2台微波辐射计、1部风廓线雷达获取高分辨率的水汽观测资料，对卫星遥感数据进行水汽反演和校验，建立天山山区水汽反演算法，给出基于卫星遥感反演资料统计的月、季、年平均的天山山区水汽精细化空间分布，研究天山山区水汽垂直结构、水汽分布与雨量分布的关系、强降水天气过程中水汽输送特征和演变规律，加深对天山山区水分循环过程问题的科学认识。

天山山区地形复杂、观测站点稀疏，水汽输送和时空分布状况、水汽分布与最大降水带的关系、水汽垂直结构及演变特征等问题一直不清楚，在一定程度上制约了人们对这些科学问题的深入研究。本项目利用地基GPS、多通道微波辐射计、卫星遥感等高时空分辨率的水汽探测手段生成天山山区高时空分辨率的水汽分布数据集，并对水汽数据开展精度对比分析，发现GPS反演水汽与探空水汽两者符合很好，GPS PWV和每小时降水量显示了降水和水汽汇聚的极好配合，每2个小时GPS PWV的变化与降水量的相关性最好;微波辐射计水汽密度和液态水对降水的发生比较敏感，而且有一定的提前指示变化;从卫星微波温、湿度资料同化对新疆降水预报的影响看;同化AM-SU-A资料，总体为负效果,同化MHS资料对于整个降水落区和大阈值降水的预报均有明显优势。在获得天山水汽分布的基础上，分析天山山区水汽结构的三维时空分布和演变特征:天山山区水汽含量年平均为10.51mm，呈现出增加趋势,水汽分布有3个高值区，分别为西天山的伊犁河谷地区、中天山北麓平原地区和东天山南部的吐鲁番盆地;天山山区水汽含量夏季最大，其次是秋季，春季与秋季相当;水汽含量随高度的分布关系呈负指数规律递减;从地面到300hPa每年平均有11919.28×108m3水汽流入，11881.19×108m3水汽流出，水汽净收支为净输入28.59×108m3。对天山山区水汽和降水时空分布的关系进行分析，揭示天山山区典型强降水过程的水汽演变规律，研究天山山区强降水过程的水汽输送空间分布和配置演变。天山水汽再循环率为9.32%，当地蒸发的水汽形成的降水量为41.8mm，外来水汽输送到山区形成的降水量为407.2mm;强降水前测站GPS PWV均存在１～３ｄ增湿过程和１～２次跃变过程，强降水发生前GPS PWV跃变均超过５mm/４h。项目的开展为深入开展天山山区水分循环研究奠定基础，为天山山区空中水资源开发利用提供科学依据。项目观测数据资料和开发的软件在内部网络共享,资助发表7篇论文，参加国际会议国内会议各1次,制定1个地方标准，1名硕士研究生利用相关数据顺利毕业。