Dust radiative effects on atmospheric thermodynamics and tropical cyclogenesis over the Atlantic Ocean using WRF-Chem coupled with an AOD data assimilation system
This study investigated the dust radiative effects on atmospheric thermodynamics and tropical cyclogenesis over the Atlantic Ocean using the Weather Research and Forecasting Model with Chemistry (WRF-Chem) coupled with an aerosol data assimilation (DA) system. MODIS AOD (aerosol optical depth) d...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/17/7917/2017/acp-17-7917-2017.pdf |
| Summary: | This study investigated the dust radiative effects on atmospheric
thermodynamics and tropical cyclogenesis over the Atlantic Ocean using
the Weather Research and Forecasting Model with Chemistry (WRF-Chem) coupled with an aerosol data assimilation (DA) system. MODIS AOD
(aerosol optical depth)
data were assimilated with the Gridpoint Statistical Interpolation (GSI)
three-dimensional variational (3DVAR) DA scheme to depict the Saharan dust outbreak
events in the 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 h
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 (CIN). 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 in which
clouds are altered by thermodynamic changes are also noted, which then alter cloud-radiative
temperature (<i>T</i>) changes. The analysis of a tropical cyclone (TC) suppression case
on 5 September shows evidence of enhanced convective inhibition by direct heating
in dust, but it also suggests that the low-predictability dynamics of moist
convection reduces the determinism of the effects of dust on timescales of
TC development (days). |
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| ISSN: | 1680-7316 1680-7324 |