Impact of Topography on Black Carbon Transport to the Southern Tibetan Plateau during Pre-monsoon Season and Its Climatic Implication
Abstract
Tibetan Plateau (TP) has significant impacts on climate of Asia. Previous studies have shown that the glaciers on the TPare accelerating melting in the last decades, which will affect the Asian climate and also threaten the water resources in neighboring countries. Part of the reason may be that the light absorbing aerosols (LAA) can be transported from the southern slope of TP into the surface snow and atmosphere over the TP, and thereby affect the radiation budget of TP. Most previous modeling studies about black carbon (BC) transport and impact over the TP conducted simulations with horizontal resolutions coarser than 10 km that may not be able to resolve well the complex topography of the southern slope of TP. In this study, the experiments with WRF-Chem at two resolutions are conducted for pre-monsoon season (April) to investigate the impacts of topography on modeling the BC transport and distribution over the TP, including the simulation at the high resolution (4 km) over the southern slope of TP to resolve the complex topography. The simulations at both resolutions show evident accumulation of aerosols near the southern slope of TP during the per-monsoon season, consistent with the satellite retrievals. The observed episode of high surface BC concentrations at the station near the Mt. Everest due to heavy biomass burning near the TP is well captured by the simulations. The simulations at both resolutions show that the prevailing up-flow across the southern slope of TP driven by the large-scale circulation during the daytime is the dominant transport mechanism of BC to the TP, and is much stronger than that during the nighttime. The valley wind can strengthen the prevailing up-flow transport. The simulations at coarse resolution (20 km) and fine resolution (4 km) show large differences in representing the distributions of topography of the southern slope of TP, which results in 50% higher transport flux of BC across the southern slope of TP and 30-40% stronger BC radiative heating in the atmosphere over the TP from the simulation at 4 km than that at 20 km. The different topography also leads to different distributions of snow cover and BC forcing in snow. This implies that global climate models generally with even coarser resolutions than 20 km may introduce significant negative biases in estimating LAA radiative forcing over the TP.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A23E..10Z
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0368 Troposphere: constituent transport and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 3337 Global climate models;
- ATMOSPHERIC PROCESSES;
- 3359 Radiative processes;
- ATMOSPHERIC PROCESSES