The Horizontal Inhomogeneity of the Evaporation Duct Based on Surface Bulk Measurements Over the South China Sea

The uniformity of evaporation duct height (EDH) plays a crucial role in the accurate prediction of electromagnetic propagation. This article examines the non-uniformity of EDH in South China Sea (SCS) using data from 5 buoy stations and 14 automatic weather stations (AWS). The factors contributing to the non-uniformity of EDH are analyzed using the Spearman rank correlation method, and the impact of sea surface temperature (SST) error on the non-uniformity of EDH is also examined. The findings are as follows: 1) the Xisha Islands (XS) show the most non-uniformity in EDH, while the distributions of EDH in the Hainan Island (HN) and Nansha Islands (NS) are fairly uniform; 2) the primary factor related to the non-uniformity of EDH in the HN region is relative humidity (RH)—when ASTD <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\geq 0$ </tex-math></inline-formula>—and wind speed (WS)—when ASTD <0. However, the main factor related to the non-uniformity of EDH in the XS and NS regions is atmospheric temperature when ASTD <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\geq 0$ </tex-math></inline-formula>, and WS when ASTD <0; and 3) the SST errors mainly affect the percentage distribution of EDH difference when its absolute value is less than 2 m. When the absolute value of EDH difference is more than 2 m, the impact of SST errors is relatively minor.