![Sample our Geography journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/5937/TOC-Subject-Sample-2021-Geography.jpg"})
ABSTRACT
The geometric and polarimetric characteristics of the melting layer (ML) during the pre-summer rainy season over South China (PRSC) are investigated from 389 S-band polarimetric radar volume scans. The existing ML detection algorithm is slightly improved, in which the ML is automatically detected by using vertical gradients of radar reflectivity factor for horizontal polarizations (ZH), and co-polar cross-correlation coefficient (ρHV) from quasi-vertical profiles. And these profiles are obtained by azimuthal averaging of polarimetric radar variables at antenna elevation 19.5°. The comparison between the detected ML top and the 0°C isotherm heights from ERA5 demonstrates that the detection algorithm has high accuracy with an offset of 158 m. Due to larger snowflakes, the average ML thickness in PRSC is thicker (i.e. 150 m) than that in other climatic regions. The ML is characterized by large ZH, large differential reflectivity (ZDR) and small ρHV, with average values of 32 dBZ, 0.91 dB and 0.94. Furthermore, the peak values of ZH and ZDR in the ML are obviously larger than that from rain regions and snow regions, while the opposite is true for ρHV distribution.
Data availability statement
The ERA5 is available online at https://cds.climate.copernicus.eu/cdsapp#!/home. These polarimetric radar data can be accessed upon request but whose usage may be restricted by pertinent Chinese government rules and regulations that are beyond the control of the authors (contact email: [email protected]).
Disclosure statement
No potential conflict of interest was reported by the authors.