A new dataset of rain cells based on observations of Tropical Rainfall Measuring Mission (TRMM) precipitation radar, visible/infrared scanner and microwave imager

Abstract

Understanding the characteristics of the rain cell, the most basic unit in the natural precipitation system, is helpful in improving the cognition of the precipitation system. In this study, based on the merged precipitation profile data, reflectance and infrared data, and microwave brightness temperature data observed by the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR), visible and infrared scanner (VIRS) and TRMM microwave imager (TMI), rain cells were identified in the PR swath. For the identified valid rain cells, two fitting methods (the minimum bounding rectangle (MBR) and the best fit ellipse (BFE)) were applied to fit the external frame. Then, the geometric and physical parameters of rain cells were also calculated. By analyzing the geometric parameters (length, width, height, and so on) and physical parameters (rain rate, visible reflectance and thermal infrared brightness temperature from cloud top, and microwave brightness temperature from cloud column) of two rain cells (weak rain cell and strong rain cell), the results indicate that the strong rain cell is filled with deep convective precipitation and has low thermal infrared brightness temperature at the cloud top, while the weak rain cell is mainly characterized by stratiform precipitation with low rain rate. Compared to the BFE method, the area of the external frame calculated by the MBR method is generally larger. The filling ratio of the BFE method is slightly higher than that of the MBR method. In general, the results indicate that the rain cell definition parameters using the two fitting methods are reasonable and intuitive. The data used in this paper are freely available at 10.5281/zenodo.15387988 (Wu and Fu, 2025).