Multi-land-surface variables-precipitation coupling over the northeastern slope of the Tibetan Plateau

Land-atmosphere coupling is crucial for understanding the role of land surface conditions on precipitation, especially on the northeastern slope of the Tibetan Plateau, an area that has received limited attention. This study investigates the coupling between multiple land surface factors and precipitation, focusing on the individual and combined impacts of soil moisture, surface temperature, and vegetation (Leaf Area Index, LAI). The results reveal significant northwest-southeast gradients in surface factors, leading to corresponding spatial variations in latent (LE) and sensible heat fluxes (H). The two-stage land-atmosphere coupling were examined using complex correlation coefficients. In surface stage, the synergistic coupling of LE or H with soil moisture, surface temperature, and LAI is significantly enhanced compared to individual coupling. In atmosphere stage, after considering both surface fluxes and precipitation components, the coupling becomes notably stronger. Spatial differences in soil moisture and surface temperature mainly affect the surface factor-latent heat flux-precipitation coupling chain, while LAI impacts the surface factor-sensible heat flux-precipitation coupling chain. The synergistic coupling of surface variables with LE is strongest in forested areas, and with H in sparse vegetation areas, primarily driven by soil moisture. The synergetic coupling of LE and H with precipitation is relatively strong in forested and sparse vegetation areas, where precipitation is mainly dominated by H. These findings enhance our understanding of the comprehensive impact of multiple surface factors on precipitation under complex land surfaces and could provide scientific references for improving simulation of land-atmosphere coupling in weather and climate models.