Wildfires heat the middle troposphere over the Himalayas and Tibetan Plateau during the peak of fire season

Abstract. Atmospheric pollutions from biomass burning contribute to climatic and cryospheric changes by influencing solar radiation and the albedos of snow and ice surfaces in the Himalayas and Tibetan Plateau (HTP). We utilize long‐term MODIS fire products and ground‐based and satellite‐derived aerosol datasets to investigate the primary effect of wildfires from the south slopes of Himalayas on aerosol loading in the HTP. Results show consistent interannual and seasonal variation patterns, as well as statistically significant correlations, between AOD at 500 nm from AERONET stations (Pokhara, QOMS, Nam Co) and Himalayan fire counts. CALIPSO data reveal elevated smoke aerosol extinction coefficients at altitudes of 6~8 km (middle troposphere) in the southern HTP during the peak of fire season (March–April) in 2021. The intense wildfire activity in 2021 likely contributed to mid-tropospheric warming and alterations in the vertical temperature structure, as evidenced by a reduction in the absolute lapse rate, representing the rate of temperature decrease with altitude. This reduction was observed at QOMS, SETS, and Naqu stations when compared to 2022. SBDART simulations estimated increased heating rates (0.38~1.32 K day⁻¹) and atmospheric warming (15.03~22.43 W m⁻²) in the mid-troposphere due to smoke aerosols. Such warming affects regional atmospheric stability and modulating surface temperatures. It is crucial to research into the heating/cooling processes induced by aerosols and their influence on the vertical temperature structure to comprehensively understand the impacts of aerosols on regional climate and the hydrological cycle.