Preprints
https://doi.org/10.5194/acp-2021-462
https://doi.org/10.5194/acp-2021-462

  28 Jun 2021

28 Jun 2021

Review status: this preprint is currently under review for the journal ACP.

Impacts of the Saharan air layer on the physical properties of the Atlantic tropical cyclone cloud systems: 2003–2019

Hao Luo1 and Yong Han1,2,3 Hao Luo and Yong Han
  • 1School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, 519082, China
  • 2Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai 519082, China
  • 3Southern marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China

Abstract. It is generally known that the tropical cyclone (TC) cloud systems (TCCS) in the North Atlantic region frequently occur during boreal summer, while the Saharan dust outbreaks concurrently. The Sahara air layer (SAL), an elevated layer containing Saharan dry air and mineral dust, makes crucial impacts on the generation and evolution of TCs. However, the effects of SAL on the physical (macro and micro) characteristics of the Atlantic TCCS have not been well constrained, and the interaction mechanisms between them still need further investigation. In this study, our primary interest is to distinguish the various effects of SAL on different intensities of TCs, and further find out the probable causes of the varied feedback. Therefore, we attempt to identify whether and how the effects of the SAL play a positive or negative role on the TCCS, and to draw a qualitative conclusion of how SAL affects the various intensities of the TCs. This paper focuses on the 70 TC samples from July to September in the years of 2003–2019 to investigate the physical effects of SAL on three intensities of TCs, i.e.: the tropical depression (TD), tropical storm (TS), and hurricane (HU). The results show that SAL has a positive impact on the macro properties of HU but significantly suppresses the TD. It appears that the SAL attributes little to the variation of ice cloud effective radius (CERi) for TS, whereas CERi changes significantly and differentially for TD and HU. When affected by SAL, the probability density function (PDF) curve of CERi generally shifts to the smaller value for TD, but the PDF curve becomes flatten for HU. Our analysis indicates that the various responses of TCCS to SAL are determined by the combined effects of dry air masses, the dust aerosols as ice nuclei, as well as the thermodynamic and moisture conditions. Based on the observation data analysis, a concept scheme description has been concluded to deepen our recognition of the effects of SAL on the TCCS.

Hao Luo and Yong Han

Status: open (until 21 Aug 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-462', Anonymous Referee #1, 25 Jul 2021 reply

Hao Luo and Yong Han

Hao Luo and Yong Han

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Short summary
The various feedback of Atlantic tropical cyclones (TC) to Saharan air layer (SAL) are determined by the combined effects of dry air masses, the dust aerosols as ice nuclei, as well as the dynamic, thermodynamic and moisture conditions. The specific influence mechanisms of SAL on the three intensities of TC (tropical depression, tropical storm and hurricane) are different. The conclusions are beneficial to our recognition of the physical process and evolution of TCs in the Atlantic region.
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