Local And Non-local Climate Effects Of Biomass Burning In Indochin

The Indo-China Peninsula(ICP)is located in the upper region of the East Asian summer monsoon,and its soil moisture has a significant impact on the formation and development of the East Asian summer monsoon by affecting the local thermal conditions,which can lead to abnormal precipitation in eastern China.Additionally,the Indo-China Peninsula is one of the areas with the highest biomass burning emissions in the world during spring.Biomass burning emissions yield substantial amounts of aerosols,and research indicates that aerosols can affect the climate through their impact on radiation,cloud physics,and precipitation processes.As a crucial climate-forcing factor,aerosols exhibit cross-effects with various land-atmosphere coupled processes and play a notably significant role in both the terrestrial and atmospheric.This paper combines reanalysis data and numerical models to study the relationship between biomass burning and soil moisture anomalies and summer precipitation in eastern China,and explore their possible impact mechanisms.The main conclusions are as follows:(1)The comparison of WRF-CHEM model simulations with reanalysis data reveals that the model performs well in simulating the spatial distribution characteristics of various meteorological variables,including extreme values,central locations,and intensities.However,the accuracy of the model may be limited in the complex terrain of the Tibetan Plateau.Furthermore,with respect to the temporal variation of various meteorological variables,particularly precipitation,surface temperature,and surface pressure,the model demonstrates good performance.The time correlation coefficients between the model simulations and reanalysis data are 0.74,0.96,and 0.91,respectively.(2)There was a significant negative correlation between spring biomass burning and soil moisture in interannual variation in the Indochina Peninsula.This correlation indicates that when the concentration of biomass burning emissions is high(low)during springtime,the soil moisture tends to be dry(wet)in this area.Biomass burning aerosols absorb solar radiation in the lower troposphere,inducing changes in atmospheric temperature structure,enhancing atmospheric stability,suppressing convection and precipitation,and leading to abnormal soil moisture.Furthermore,although biomass burning has a significant impact on soil moisture,the extent of the effect can also be influenced by the state of the soil moisture itself.(3)Biomass burning exacerbates the influence of soil moisture anomalies on atmospheric circulation.The Yangtze River Basin experiences a significant increase(decrease)in summer precipitation when the soil moisture in the Indochina Peninsula is dry(wet)in spring due to the influence of biomass burning,with a larger area and a westward position of precipitation increase(decrease).In the absence of biomass burning,the area of precipitation increase(decrease)is smaller and mainly concentrated in the central region.This phenomenon is due to the radiation effect of biomass burning,which alters the temperature structure and suppresses precipitation,decreased soil moisture,and elevated surface temperature in the region.The resulting heating in the lower atmosphere favors the strengthens and extends the western Pacific subtropical high,and enhances the transport of warm and humid airflow to the Yangtze River Basin,resulting in a higher precipitation increase and a westward position.In addition,the atmospheric heating associated with biomass burning during the spring has the potential to further intensify and expand the Western Pacific Subtropical High towards the west.Conversely,in the absence of biomass combustion emissions,the abnormal surface heat flux caused by soil moisture has a weaker impact on the circulation and less warm and humid airflow transported to China,leading to less precipitation increase in summer.