Effect of net radiation on soil temperature field considering slope angle

Determining net radiation is crucial for understanding soil-atmosphere interactions and plays a key role in defining thermal boundary conditions for thermo-hydro-mechanical models of slopes. Current methods for estimating net radiation at soil surfaces typically overlook the influence of slope angle. For this purpose, this study aims to propose two refined methods for calculating net radiation on slope surfaces, which were developed from two wide-acknowledged mathematical methods for horizontal surfaces. To evaluate the refined methods, we focused on net radiations that were calculated from monitored meteorological data. The calculated net radiation was then input into a coupled hydro-thermal model to compute the slope temperature distributions, which were subsequently compared to the measured temperatures. Satisfactory agreement was observed, demonstrating the feasibility of both methods. Afterwards, we examined the influence of slope angle on solar and net radiation results, then used a coupled hydro-thermal model to quantify differences in numerical temperature results when slope angle is either considered or neglected. Results indicate that the solar radiation received on slope surface is additionally affected by slope angle. In our simulation scenarios, the slope angle causes a maximum net radiation difference of 347.83 W/m 2 , and a maximum temperature difference of 6.5 °C.