Imperial College London
Portrait Picture

Professor Helen Brindley

Faculty of Natural Sciences, Department of Physics

Professor in Earth Observation
 
 
 
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Contact

 

+44 (0)20 7594 7673h.brindley

 
 
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Location

 

717Huxley BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Marsham:2016:10.5194/acp-16-3563-2016,
author = {Marsham, JH and Parker, DJ and Todd, MC and Banks, JR and Brindley, HE and Garcia-Carreras, L and Roberts, AJ and Ryder, CL},
doi = {10.5194/acp-16-3563-2016},
journal = {Atmospheric Chemistry and Physics},
pages = {3563--3575},
title = {The contrasting roles of water and dust in controlling daily variations in radiative heating of the summertime Saharan heat low},
url = {http://dx.doi.org/10.5194/acp-16-3563-2016},
volume = {16},
year = {2016}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - The summertime Sahara heat low (SHL) is a key component of the West African monsoon (WAM) system. Considerable uncertainty remains over the relative roles of water vapour and dust aerosols in controlling the radiation budget over the Sahara and therefore our ability to explain variability and trends in the SHL, and in turn, the WAM. Here, new observations from Fennec supersite-1 in the central Sahara during June 2011 and June 2012, together with satellite retrievals from GERB, are used to quantify how total column water vapour (TCWV) and dust aerosols (from aerosol optical depth, AOD) control day-to-day variations in energy balance in both observations and ECWMF reanalyses (ERA-I). The data show that the earth-atmosphere system is radiatively heated in June 2011 and 2012. Although the empirical analysis of observational data cannot completely disentangle the roles of water vapour, clouds and dust, the analysis demonstrates that TCWV provides a far stronger control on TOA net radiation, and so the net heating of the earth-atmosphere system, than AOD does. In contrast, variations in dust provide a much stronger control on surface heating, but the decreased surface heating associated with dust is largely compensated by increased atmospheric heating, and so dust control on net TOA radiation is weak. Dust and TCWV are both important for direct atmospheric heating. ERA-I, which assimilated radiosondes from the Fennec campaign, captures the control of TOA net flux by TCWV, with a positive correlation (r = 0.6) between observed and modelled TOA net radiation, despite the use of a monthly dust climatology in ERA-I that cannot capture the daily variations in dustiness. Variations in surface net radiation, and so the vertical profile of radiative heating, are not captured in ERA-I, since it does not capture variations in dust. Results show that ventilation of the SHL by cool moist air leads to a radiative warming, stabilising the SHL with respect to such perturbations. It is k
AU  - Marsham,JH
AU  - Parker,DJ
AU  - Todd,MC
AU  - Banks,JR
AU  - Brindley,HE
AU  - Garcia-Carreras,L
AU  - Roberts,AJ
AU  - Ryder,CL
DO  - 10.5194/acp-16-3563-2016
EP  - 3575
PY  - 2016///
SN  - 1680-7324
SP  - 3563
TI  - The contrasting roles of water and dust in controlling daily variations in radiative heating of the summertime Saharan heat low
T2  - Atmospheric Chemistry and Physics
UR  - http://dx.doi.org/10.5194/acp-16-3563-2016
UR  - http://hdl.handle.net/10044/1/37604
VL  - 16
ER  -
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