Spatiotemporal variations of the ultraviolet upward radiation of background formations in the Earth-atmosphere system

2000 ◽  
Vol 67 (3) ◽  
pp. 225
Author(s):  
V. I. Barysheva ◽  
A. V. Ivanov ◽  
A. A. Kamenev ◽  
V. D. Starichenkova
Keyword(s):  
Earth Atmosphere ◽  
Spatiotemporal Variations ◽  
The Earth ◽  
Atmosphere System

scholarly journals The contrasting roles of water and dust in controlling daily variations in radiative heating of the summertime Saharan Heat Low

2015 ◽  
Vol 15 (14) ◽  
pp. 19447-19476 ◽  
Author(s):  
J. H. Marsham ◽  
D. J. Parker ◽  
M. C. Todd ◽  
J. R. Banks ◽  
H. E. Brindley ◽  
...  
Keyword(s):  
Energy Balance ◽  
Water Vapour ◽  
Radiative Heating ◽  
Surface Heating ◽  
Earth Atmosphere ◽  
Net Radiation ◽  
The Earth ◽  
Atmosphere System ◽  
Net Flux ◽  
Heat Low

Abstract. 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 the Fennec field campaign 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. It is TCWV that largely determines variations in daily mean TOA net flux and the net heating of the earth-atmosphere system. In contrast, dust provides the primary control on surface heating, but the decreased surface heating from 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 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 known that models struggle to capture the advective moistening of the SHL, especially that associated with mesoscale convective systems. Our results show that the typical model errors in Saharan water vapour will lead to substantial errors in the modelled TOA energy balance (tens of W m−2), which will lead to errors in both the SHL and the WAM.

Infrared limb-darkening effects for the earth-atmosphere system

1983 ◽  
Author(s):  
S. GUPTA ◽  
J. SUTTLES ◽  
S. TIWARI ◽  
C. VEMURU
Keyword(s):  
Earth Atmosphere ◽  
The Earth ◽  
Atmosphere System ◽  
Limb Darkening

Trends in spectrally resolved OLR from 10 years of IASI measurements

2021 ◽  
Author(s):  
Simon Whitburn ◽  
Lieven Clarisse ◽  
Andy Delcloo ◽  
Steven Dewitte ◽  
Marie Bouillon ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Data Retrieval ◽  
Radiation Budget ◽  
Retrieval Algorithm ◽  
Earth Atmosphere ◽  
Clear Sky ◽  
The Earth ◽  
Atmosphere System ◽  
Spectrally Resolved ◽  
The Impact

<p>The Earth's Outgoing Longwave Radiation (OLR) is a key component in the study of climate. As part of the Earth's radiation budget, it reflects how the Earth-atmosphere system compensates the incoming solar radiation at the top of the atmosphere. At equilibrium, the two quantities compensate each other on average. Any variation of the climate drivers (e.g. greenhouse gases) causes an energy imbalance which leads to a climate response (e.g. surface temperature increase), with the effect of bringing the radiation budget back to equilibrium. Considerable improvements in our understanding of the Earth-atmosphere system and of its long-term changes have been achieved in the last four decades through the exploitation of measurements from dedicated broadband instruments. However, such instruments only provide spectrally integrated OLR over a broad spectral range and are therefore not well suited for tracking separately the impact of the different parameters affecting the OLR.</p><p>Better constraints can, in principle, be obtained from spectrally resolved OLR (i.e. the integrand of broadband OLR, in units of W m<sup>-2</sup> cm<sup>-1</sup>) derived from infrared hyperspectral sounders. Recently, a dedicated algorithm was developed to derive clear-sky spectrally resolved OLR from the Infrared Atmospheric Sounding Interferometer (IASI) at the 0.25 cm<sup>-1</sup> native spectral sampling of the L1C spectra (Whitburn et al. 2020).  Here, we analyze the changes in 10 years (2008-2017) of the IASI-derived OLR and we relate them to known changes in greenhouse gases concentrations (CO<sub>2</sub>, CH<sub>4</sub>, H<sub>2</sub>O, …) and climate phenomena activity such as El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO).</p><p>Whitburn, S., Clarisse, L., Bauduin, S., George, M., Hurtmans, D., Safieddine, S., Coheur, P. F., and Clerbaux, C. (2020). <strong>Spectrally Resolved Fuxes from IASI Data: Retrieval algorithm for Clear-Sky Measurements</strong>. Journal of Climate. doi: 10.1175/jcli-d-19-0523.1</p>

scholarly journals The contrasting roles of water and dust in controlling daily variations in radiative heating of the summertime Saharan heat low

2016 ◽  
Vol 16 (5) ◽  
pp. 3563-3575 ◽  
Author(s):  
John H. Marsham ◽  
Douglas J. Parker ◽  
Martin C. Todd ◽  
Jamie R. Banks ◽  
Helen E. Brindley ◽  
...  
Keyword(s):  
Energy Balance ◽  
Water Vapour ◽  
Radiative Heating ◽  
Surface Heating ◽  
Earth Atmosphere ◽  
Net Radiation ◽  
Atmospheric Heating ◽  
The Earth ◽  
Atmosphere System ◽  
Heat Low

Abstract. 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 known that models struggle to capture the advective moistening of the SHL, especially that associated with mesoscale convective systems. Our results show that the typical model errors in Saharan water vapour will lead to substantial errors in the modelled TOA energy balance (tens of W m−2), which will lead to errors in both the SHL and the WAM.

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