Abstract:
Doppler radar can provide information of precipitation particles and radial component of atmospheric motion with high spatial and temporal resolutions. The spatial information of precipitation particles, such as reflectivity and dual polarization parameters, are relatively intuitive for application. However, the Doppler radar can only detect radial component of atmospheric motion, which makes it difficult to directly reflect the whole characteristics of atmospheric motion. Thereby it is necessary to develop various retrieval methods for extracting atmospheric motion information, which is useful for the diagnosis, analysis and prediction of meso and microscale systems from radar observations. Doppler weather radar networks have been established in most of the countries in the world. However, wind fields obtained by radars have not been widely used. In this study, the methods for retrieving wind fields from a single Doppler radar or multiple radars are classified and summarized. Some basic derivation formulas are attached in appendix, which makes it convenient for researchers to explore the principles of these retrieval methods. For the single-Doppler radar wind field retrieval, the methods that are based on the spatial continuity assumption and only requires a 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 such retrieval methods is large for meso and microscale systems. As for the linear variation wind assumption, the retrieval equations are difficult to be fully solved. Therefore, some other extended methods have been derived to improve the accuracy and applicability of the retrieval methods used for single Doppler radar. For the wind retrieval techniques that can be applied to two or more Doppler radars, the principles and characteristics of these methods are summarized. The multi-Doppler radar retrieval method can yield accurate information of three-dimensional wind field with high resolution, but the applicability of those methods depends on spatiotemporal synchronization of observations. With the development of radar network and phased array radar, the applicability of the multi-Doppler radar retrieval method has been improved and attracted more and more attention. Finally, the future direction of the development of Doppler radar wind field retrieval technique are discussed.