Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published November 30, 2019 | public
Journal Article

Climate Impacts of the Biomass Burning in Indochina on Atmospheric Conditions over Southern China

Abstract

Substantial biomass burning (BB) activities in Indochina during March and April of each year generate aerosols that are transported via westerly winds to southern China. These BB aerosols have both radiative (direct and semi-direct) and indirect effects on the climate. This study evaluates impacts of BB in Indochina during April 2013 on atmospheric conditions in southern China using WRF-Chem sensitivity simulations. We show that the atmosphere becomes drier and hotter under the aerosol radiative effect in southern China, while the changes linked to the indirect effect are opposite. The former (the latter) rises (reduces) surface temperature 0.13°C (0.19°C) and decrease (increase) water vapor mixing ratios 0.23 g kg⁻¹ (0.40 g kg⁻¹) at 700 hPa. Atmospheric responses to aerosols in turn affect aerosol dissipation. Specifically, BB aerosols absorb solar radiation and heat the local atmosphere, which inhibits the formation of clouds (reducing low-level cloud about 7%) related to the aerosol semi-direct effect. Less cloud enhances surface solar radiation flux and temperature. Otherwise, northeasterly winds linked to radiative effect suppress water vapor transport. In this case, precipitation reduces 1.09 mm day⁻¹, diminishing wet removal and westward transport of aerosols. Under the indirect effect, greater cloud coverage is formed, which reduces surface solar radiation flux and increases local latent heat release. This extra heating promotes air convection and diffusion of pollution. Regional mean precipitation increases 0.49 mm d⁻¹, facilitating wet pollution removal. Under indirect effect, aerosol extinction coefficient reduces 0.011 km⁻¹ at 2-km height over southern China. However, it increases around 0.002 km⁻¹ at 3-km height over southernmost China related to radiative effect. Therefore, atmospheric changes linked to indirect effect play a greater role in removing pollutants from the atmosphere than radiative effect over southern China.

Additional Information

© 2019 Taiwan Association for Aerosol Research. Received for review, February 23, 2019; Revised, August 5, 2019; Accepted, October 17, 2019. The authors were supported by the National Key R&D Program of China (2018YFC1507402), the National Program for Key Basic Research Projects of China (973) (Grant no. 2014CB953904), National Natural Science Foundation of China (NSFC; Grant no. 41705117 and 41875168), and Guangzhou Science and Technology Plan (201605131033247). We are also grateful to the NCAR Mesoscale and Microscale Meteorology Division for making the WRF-Chem model available at http://www.mmm.ucar.edu/wrf/users. The National Centers for Environmental Prediction-Final Global tropospheric analysis data (NCEP-FNL; http://rda.ucar.edu/datasets/ds083.2), the 0.5° × 0.5° Reanalysis of Tropospheric chemical composition (RETRO; http:/retro.enes.org/index.shtml), and the 1° × 1° Emission Database for Global Atmospheric Research (EDGAR; http://www.mnp.nl/edgar/introduction) were used in this paper.

Additional details

Created:
August 22, 2023
Modified:
October 18, 2023