Title: Aerosol Impacts on Mesoscale Convective Systems Forming Under Different Vertical Wind Shear Conditions

Abstract

Following our previous study of wind shear effect on mesoscale convective system (MCS) organization under a clean atmospheric condition using the Weather Research and Forecasting model coupled with Spectral-Bin Microphysics, we conduct sensitivity simulations by increasing cloud condensation nuclei (CCN) concentration and investigate aerosol impacts on MCSs forming under different wind shear conditions. We find that, aerosols induce stronger updrafts and downdrafts in all MCSs. The stronger updrafts and enlarged convective core area contribute to larger vertical mass fluxes and enhance precipitation, indicating convective invigoration. Increased updraft speed below 8-km altitude mainly results from enhanced condensational heating, and increased water loading effect is not large enough to overcome the increase in thermal buoyancy. Interestingly, above 8-km altitude we see reduced updraft speed by the increased aerosols due to reduced vertical pressure perturbation gradient force, and weakened depositional growth due to competition of water vapor by enhanced condensation. The accumulated rainfall and mean rain rate are increased, with an increased occurrence frequency of heavy rain. The increase of rain rate is seen in both convective and stratiform regions, with a more significant increase in convective rain rate. In general, we see a higher frequency of deep convective cloud in the pollutedmore » condition because of invigorated convection, and more stratiform/anvil clouds, but a lower frequency of shallow warm clouds. The unanimously invigorated MCSs by aerosols under various wind shear conditions revealed by this study has an important implication in weather and climate at warm and humid regions that are influenced by pollution.« less

Authors:

Chen, Qian  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2426-0897"

Fan, Jiwen  ^[2];

• Search DOE PAGES for author "Fan, Jiwen"
• Search DOE PAGES for ORCID "0000-0001-5280-4391"

Yin, Yan  ^[3];

• Search DOE PAGES for author "Yin, Yan"
• Search DOE PAGES for ORCID "0000-0002-8391-2712"

Han, Bin  ^[4]

• Search DOE PAGES for author "Han, Bin"
• Search DOE PAGES for ORCID "0000-0002-4121-553X"

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+ Show Author Affiliations

1. Nanjing Univ. of Technology (China). State Key Lab. for Aerosol‐Cloud‐Precipitation of China Meteorological Administration; Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Science and Global Change Div. (ASGC)
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Science and Global Change Div. (ASGC)
3. Nanjing Univ. of Technology (China). State Key Lab. for Aerosol‐Cloud‐Precipitation of China Meteorological Administration
4. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Science and Global Change Div. (ASGC); Nanjing Univ. (China)

Publication Date:

Sat Feb 08 00:00:00 EST 2020

Research Org.:

Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1605104

Report Number(s):

PNNL-SA-140094
Journal ID: ISSN 2169-897X

Grant/Contract Number:  

AC05-76RL01830

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research: Atmospheres

Additional Journal Information:

Journal Volume: 125; Journal Issue: 3; Journal ID: ISSN 2169-897X

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; Mesoscale Convective System; Aerosol‐cloud interaction; wind shear; convection; precipitation; cloud top height