Mountainous Radar Estimation of Precipitation Reflectivity Factor Correction Method Research

Abstract

Many new-generation Doppler weather radars in China are located in mountainous areas with complex topography， and the problem of low elevation angle terrain occlusion is prominent.When estimating precipitation by radar in the occluded area， observations with higher elevation angles need to be used， and due to the micro-physical changes and horizontal motion of precipitation particles during their descent， the reflectivity factor at high locations of the same site is often very different from that near the surface， which will increase the estimation error when used directly for estimating surface precipitation.In this paper， we propose a method for the vertical revision of reflectivity factor.First， we establish the vertical reflectivity factor profiles （VPR） of different precipitation types in the unobstructed observation area， and then revise the observations above the height to be revised to the target height by determining the height threshold to be revised and the near-surface target height based on the vertical variation characteristics of the profiles.The comparison test results show that： the revised target reflectivity factor data are less different from the actual observed data values， and the consistency is improved； moreover， the data at low VPR are more accurate by considering the occlusion factor； since the VPR of different precipitation types are significantly different， the differentiation of precipitation types can avoid mis-correction.The proposed revision method is not only applicable to the beam blocking area， but also generally applicable to the revision of the observed data at high beam height at long distances.

Keywords

• precipitation classification
• terrain occlusion
• reflectivity factor correction
• vertical profile of reflectivity