A review of the techniques of Doppler radar wind fields retrieval

Doppler radar is capable of providing precipitation particles information and radial component of atmospheric motion with high spatial and temporal resolution. The spatial information of precipitation particles, such as reflectivity and double polarization parameters, are relatively intuitive for application, while the Doppler radar only can detect radial component of atmospheric motion, which make it is difficult to directly reflect the whole characteristics of atmospheric motion. So it is necessary to develop the various retrieval methods for extracting atmospheric motion information, which is useful for the diagnosis, analysis and prediction of meso and microscale systems from radar detection data. The Doppler weather radar networks have been established in most of the countries in the world. However, the wind fields obtained by the radars have not been widely used. In this paper, the methods for retrieving wind fields from single or multiple Doppler radar data are classified and summarized. Some basic derivation formulas are attached in appendix, which make it convenient for relevant researchers to explore the principles of these retrieval methods. For the single-Doppler radar wind field retrieval, the methods based on the spatial continuity assumption, which only require single radar coverage with convenient application and simple calculation, are analyzed and summarized. However, the accuracy of the single-Doppler retrieval methods based on the assumption of uniform wind field is limited, and the error of those retrieval methods is too large for meso and microscale systems. As for the linear variation wind assumption, the retrieval equations are difficult to be fully solved. So the other extended methods have been derived to improve the accuracy and applicability of the retrieval methods used single Doppler radar. For two or more Doppler radar wind retrieval techniques, the principles and characteristics of these methods are summarized. Multi-Doppler radar retrieval method can obtain precise three-dimensional information of wind field with high resolution, but the applicability of those methods depends on spatio-temporal synchronization of observation. With the development of radar networking and phased array radar, the applicability of the multi-Doppler radar retrieval methods have been improved and drawn more and more attentions. Finally, the future direction of the development of Doppler radar wind fields retrieval technique are discussed.