Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2016-744
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
11 Oct 2016
Review status
A revision of this discussion paper was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
Dust Radiative Effects on Atmospheric Thermodynamics and Tropical Cyclogenesis over the Atlantic Ocean Using WRF/Chem Coupled with an AOD Data Assimilation System
Dan Chen1, Zhiquan Liu1, Chris Davis1, and Yu Gu2 1National Center for Atmospheric Research, Boulder, Colorado, USA
2University of California, Los Angeles, Los Angeles, California, USA
Abstract. This study investigated the dust radiative effects on atmospheric thermodynamics and tropical cyclogenesis over the Atlantic Ocean using WRF-Chem coupled with an aerosol data assimilation (DA) system. MODIS AOD data were assimilated with the Gridpoint Statistical Interpolation three-dimensional variational DA scheme to depict the Saharan dust outbreak events in 2006 summer. Comparisons with Ozone Monitoring Instrument (OMI), AErosol RObotic NETwork (AERONET) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) observations showed that the system was capable of reproducing the dust distribution. Two sets of 180-hr forecasts were conducted with the dust radiative effects activated (RE_ON) and inactivated (RE_OFF), respectively. Differences between the RE_ON and RE_OFF forecasts showed that low-altitude (high-altitude) dust inhibits (favors) convection owing to changes in convective inhibition. Heating in dust layers immediately above the boundary layer increases inhibition whereas sufficiently elevated heating allows cooling above the boundary layer that reduces convective inhibition. Semi-direct effects are also noted in which clouds are altered by thermodynamic changes, which then alter cloud-radiative temperature changes. The analysis of a tropical cyclone (TC) suppression case on Sep. 5 shows evidence of enhanced convective inhibition by direct heating in dust, but also suggests that the low-predictability dynamics of moist convection reduces the determinism of the effects of dust on time scales of TC development (days).

Citation: Chen, D., Liu, Z., Davis, C., and Gu, Y.: Dust Radiative Effects on Atmospheric Thermodynamics and Tropical Cyclogenesis over the Atlantic Ocean Using WRF/Chem Coupled with an AOD Data Assimilation System, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2016-744, in review, 2016.
Dan Chen et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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RC1: 'Atmospheric physics', Anonymous Referee #1, 03 Dec 2016 Printer-friendly Version 
 
RC2: 'Review of “D Chen, et al., Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-744”', Anonymous Referee #2, 11 Mar 2017 Printer-friendly Version 
 
AC1: 'Responses to Reviewer #1', D. Chen, 23 May 2017 Printer-friendly Version Supplement 
 
AC2: 'Responses to Reviewer #2', D. Chen, 23 May 2017 Printer-friendly Version Supplement 
Dan Chen et al.
Dan Chen et al.

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Short summary
The Saharan dust influence Atlantic TC genesis while the relationship and mechanisms are not fully understood. This study investigated the dust radiative effects on atmospheric thermodynamics and tropical cyclogenesis over the Atlantic Ocean using WRF-Chem coupled with an aerosol data assimilation (DA) system. Both statistics and case study revealed that low-altitude (high-altitude) dust inhibits (favors) convection owing to changes in convective inhibition. Semi-direct effects are also noted.
The Saharan dust influence Atlantic TC genesis while the relationship and mechanisms are not...
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