Intensified Warm-Season Nighttime Precipitation over Large Tibetan Plateau Lakes: Evidence from Satellite Observations

The Tibetan Plateau (TP) hosts thousands of lakes that considerably shape the local hydroclimate. Although TP lake expansion is well documented, how lake surface areas quantitatively modulate precipitation across seasonal and diurnal timescales remains unclear. Using two decades of satellite-based precipitation data (GPM IMERG; 2001–2020), we investigate precipitation variations over 17 TP lakes larger than 300 km 2 . There is a pronounced lake-induced precipitation enhancement during the warm season (June–August), which is primarily nocturnal. This effect is highly size-dependent; a clear area threshold of ∼500 km 2 emerges, above which lakes consistently intensify nighttime precipitation by an average of ∼0.64 mm/d compared with surrounding land. This warm-season nocturnal enhancement, corroborated by climate model simulations over Selin Co, is attributed to the synergy of strong lake evaporation, high sensible heat flux and low wind speeds that foster nocturnal moisture convergence. Meanwhile, cold-season (October–December) precipitation shows no notable lake effect, likely because large-scale dynamical processes overwhelm local convective forcing during this period, despite more pronounced turbulent fluxes at the lake surface. Our findings provide observational benchmarks for understanding lake–atmosphere interactions over the TP and are essential for accurately predicting hydrological responses to ongoing lake expansion under a warming climate.