基于微波链路的区域降水反演

Mobile communication have been widely used at present, the microwaves signals have covered the urban and rural areas, whereas the microwave propagation attenuation and de-polarization are affected by atmospheric factors, especially by precipitation at the high-frequency, consequently influence the quality of microwave communication. Supposing that the atmospheric information can be estimated by this effect reversely, and combined with the mobile communication network widely distributed, the meteorological information can be delivered to each mobile user in time, which can change the weather service and people's lives; therefore it is of important significance. From the significant impact of precipitation on microwave propagation, this project investigates a new method for regional precipitation inversion that microwaves respond directly to the precipitation in near-surface layer by using the microwave links network widely distributed. And this project will establish the precipitation induced wave propagation model, discuss the retrieving method of drop size distribution parameters and precipitation intensity based on dual-frequency and dual-polarization microwave links, construct the retrieve model for regional precipitation estimation based on adaptive mesh microwave links and conduct a preliminary field experiment. This method will solve the low spatial resolution, limited coverage of existing precipitation measurement methods, promote the measurement of precipitation with high spatial and temporal resolution in the key areas such as urban, mountains areas, and etc, and realize a breakthrough and innovation for regional precipitation measurement in our country.

目前手机等无线通讯方式已经非常普及，其利用的微波信号广泛覆盖广大城乡 地区，而微波传播会受到大气因素的衰减、去极化等影响，尤其是在高频段受降水的影响很 大，从而影响微波通讯的质量和效果。如果利用这一影响反向研究估计得到大气信息，并与 目前广泛布网的手机通讯网络相结合，可以及时将气象信息传递到每一个手机用户，从而给 气象服务和人们生活带来改变，因此具有十分重要的意义。本项目从对微波传播影响较大的 降水出发，利用目前广泛分布的微波传播链路网络，研究一种微波与近地表降水直接作用的 区域降水反演新方法，建立降水影响微波传播正演模型；设计双频和双偏振结合的路径降水 反演算法；构建基于自适应网格的区域降水反演模型并进行初步试验。该方法将有效弥补现 有降水测量手段空间分辨率低、覆盖范围有限等缺点，显著提高城市、山区等重点区域降水分布资料的准确获取能力，在我国区域降水测量方法上实现新的突破与创新。

高分辨率的降雨时空分布精确测量对于气象、水文、农业、环境政策、洪水预警和天气预报方面有着重要意义。而目前现有的降雨观测手段能力存在不足，不能提供较高时空分辨率的降雨监测数据。在深入研究降雨和大气气体对微波传输衰减影响特性的基础上，利用目前广泛分布的微波传播链路网络，研究一种微波与近地表降水直接作用的降水反演新方法，设计并搭建了视距微波链路降雨反演试验系统，并利用该系统进行了实测实验，验证了该方法的有效性和准确性。提出了考虑雨滴形状变化的双频和双偏振微波链路相结合的路径降雨谱最优化反演算法，利用仿真实验的手段验证了方法的准确性和可行性。此外还基于微波雨衰的幂律关系，研究了使用微波链路反演降雨场的方法，采用层析技术建立了降雨场反演模型。并利用正则化等方法实现对降雨场层析反演模型的求解。数值模拟结果表明，该模型与反演算法能够较为准确地重建降雨场强度与空间分布特征，能够提供高时空分辨率的二维降雨强度分布。因此利用微波链路测量降雨可以作为常规的雨量计与天气雷达观测手段的有效补充，弥补现有降水测量手段空间分辨率低、覆盖范围有限等缺点，显著提高城市、山区等重点区域高时空分辨率降水分布资料的准确获取能力，对于促进降雨监测水平和观测精细化程度的提高等具有重要的意义。