Preprints
https://doi.org/10.5194/acp-2020-845
https://doi.org/10.5194/acp-2020-845

  13 Oct 2020

13 Oct 2020

Review status: a revised version of this preprint was accepted for the journal ACP and is expected to appear here in due course.

Potential impact of aerosols on convective clouds revealed by Himawari-8 observations over different terrain types in eastern China

Tianmeng Chen1,2,3, Zhanqing Li2, Ralph A. Kahn2,4, Chuanfeng Zhao1, Daniel Rosenfeld5, Jianping Guo3, Wenchao Han1,2, and Dandan Chen3 Tianmeng Chen et al.
  • 1State Key Laboratory of Remote Sensing Sciences, and College of Global Change and Earth System Science, Beijing Normal University, Beijing, 100875, China
  • 2Department of Atmospheric and Oceanic Sciences & Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland 20740, USA
  • 3State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China
  • 4Earth Sciences Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
  • 5Institute of Earth Sciences, Hebrew University, Jerusalem, Israel

Abstract. Convective clouds are common and play a major role in Earth's water cycle and energy balance; they may even develop into storms and cause severe rainfall events. To understand the convective cloud development process, this study investigates the impact of aerosols on convective clouds by considering the influence of both topography and diurnal variation of radiation. By combining texture analysis, clustering and thresholding methods, we identify all convective clouds in two warm seasons (May–September, 2016–2017) in eastern China based on Himawari-8 Level 1 data. Having a large diurnally resolved cloud data together with surface meteorological and environmental measurements, we investigate convective cloud properties and their variation, stratified by elevation and diurnal change. We then analyze the potential impact of aerosol on convective clouds under different meteorological conditions and topographies. In general, convective clouds tend to occur preferentially under polluted conditions in the morning, which reverses in the afternoon. Convective cloud fraction first increase then decrease with aerosol loading, which may contribute to this phenomenon. Topography and diurnal meteorological variations may affect the strength of aerosol microphysical and radiative effects. Updraft is always stronger along the windward slopes of mountains and plateaus, especially in northern China. The prevailing southerly wind near the foothills of mountains and plateaus is likely to contribute to this windward strengthening of updraft and to bring more pollutant into the mountains, thereby strengthening the microphysical effect, invigorating convective clouds. By comparison, over plain, aerosol decreases surface heating and suppresses convection by blocking solar radiation reaching the surface.

Tianmeng Chen et al.

 
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Tianmeng Chen et al.

Tianmeng Chen et al.

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Short summary
A convective cloud identification process is developed using geostationary satellite data from Himawari-8. Convective cloud fraction is generally larger before noon and smaller in the afternoon under polluted conditions, but megacities and complex topography can influence the pattern. A robust relationship between convective cloud and aerosol loading is found. This pattern varies with terrain height, and is modulated by varying thermodynamic, dynamical and humidity conditions during the day.
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