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Thermal Radiation
Down-welling Long-wave Fluxes at the Surface
Isabel F. Trigo
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
MSG-based Radiation Products
Down-welling Long-wave Flux (DSLF)
Definition
Algorithm Basis
The LSA SAF DSLF product from MSG
Validation
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
Adapted from K. Trenberth, J. Fasullo, and J. Kiehl.
30%
23%
90%4%
47%
Thermal RadiationSolar Radiation
Radiation Budget
Earth Surface
Short-Wave Net Radiation
• Loss
• Gain
Long-Wave Net Radiation
• Loss
• Gain
?
?
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
Adapted from K. Trenberth, J. Fasullo, and J. Kiehl.
30%
23%
7%
23%
Thermal RadiationSolar Radiation
90% 4%
Radiation Budget
Earth Surface
Short-Wave Net Radiation
• Loss
Gain
Long-Wave Net Radiation
Loss
• Gain
X
X
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
Emitted by the atmosphere, Ra
Emitted by the surface, Rsup
Reflected by the surface, Rrefl
Surface Down-welling Long-Wave Radiation
Down-welling Long-wave Fluxes at the Surface
Long-wave Radiation reaching the Surface:
Essentially emitted by the lowest 100 m of the atmosphere
It is controlled by
concentration of abosrbing gases
CO2, CH4, H2O, ...
presence of clouds, clouds phase
temperature profile & temperature of cloud base
....
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
FLW =
dE
100
4
2
1
Total irradiance at the surface within the [4 – 100 m] interval:
Surface Down-welling Long-Wave Radiation
Spectral irradiance emitted downwards by the
atmosphere
Wavelength (m)
20 15 12.5 10.5 9 8 7
Observed Downward Spectra Radiance – a clear sky day
(adapated from Turner et al., 2004 in J. Atmos. Sci.
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
7
Satellite observations provide information on variables that control Down-welling Longwave Fluxes at the surface:
Clouds
Temperature Profiles
Humidity profiles
Remote Sensing
Surface Down-welling Long-Wave Radiation
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
FLW as estimated in the LSA SAF from MSG/SEVIRI
Channel 1 VIS 0.6 m
Channel 2 VIS 0.8
Channel 3 NIR 1.6
Channel 4 MIR 3.9
Channel 5 WV 6.2
Channel 6 WV 7.3
Channel 7 IR 8.7
Channel 8 IR/O3 9.7
Channel 9 TIR 10.8
Channel 10 TIR 12.0
Channel 11 IR/CO2 13.4
Channel 12 HRV
SEVIRI/MSG SEVIRI/MSG Data:
Other Information: atmosphere screen temperature (ECMWF forecast) total column water vapour (ECMWF forecast)
Cloud identification:
channels 1-4, 7, 9 & 10
Down-welling Longwave Flux at the Surface (DSLF)
Surface Down-welling Long-Wave Radiation
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
Parameterization based on Stefan-Boltzman Law:
44 )1( skycloudyskycloudyskyclearskyclear TnTnDSLF
Surface Down-welling Long-Wave Radiation
FLW as estimated in the LSA SAF from MSG/SEVIRI
Tclear-sky , clear-sky
Tcloudy-sky , cloudy-sky Cloud cover fraction
Down-welling Longwave Flux at the Surface (DSLF)
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
clearcloudyskysky DSLFnnDSLFTDSLF )1(4
m
sky
ww
10exp
1011 22 TdTTsky
Fraction of Cloud
Fraction of Cloud
Total column water vapour
2m air temperature
2m dew point depression
Parameterization based on Stefan-Boltzman Law:
Surface Down-welling Long-Wave Radiation
FLW as estimated in the LSA SAF from MSG/SEVIRI
Forecasts:(ECMWF)
Down-welling Longwave Flux at the Surface (DSLF)
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Surface Down-welling Long-Wave Radiation
15 November 2011
00 UTC 12 UTC
Cloud’s signature?
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
Surface Down-welling Long-Wave Radiation
15 November 2011
00 UTC 12 UTC
Clear Sky - Cloudy/Partially Cloudy -
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
Surface Down-welling Long-Wave Radiation
Generation Frequency - 30 min
MSG projection & resolution
Over land ...
Available since
Europe – Feb 2005
Full disk – Jul 2005
Also distributed with quality flag (pixel by pixel basis)
But ... Algorithm changed in 2008!
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
Surface Down-welling Long-Wave Radiation
Daily Accumulated Long-wave Flux
MSG projection & resolution
Over land ...
Available since
Full disk 2010
Also distributed number of time-slots used for each (pixel) estimation.
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DSLF - Validation
Comparison with in situ measurements
Comparison with other satellite products (CERES onboard Aqua and Terra)
Location of Ground Observations
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
DSLF - Validation
LSA SAF DSLF colocated in space and time with
Ground Stations & CERES (http://aqua.nasa.gov/about/instrument_ceres.php)
Northern Europe Stations
clear sky cloudy
Jan 2006 - Apr 2007
CERES SEVIRI DSLF
Bias RMSE Bias RMSE
Clear Sky -0.0 12.7 -2.2 22.3
All Sky -2.1 23.5 3.1 25.3
Problems:- Cloud identification at the edge of Meteosat disk- DSLF model for ice clouds- Temperature inversions
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
DSLF - Validation
LSA SAF DSLF colocated in space and time with
Ground Stations & CERES (http://aqua.nasa.gov/about/instrument_ceres.php)
Central Europe StationsJan 2006 - Apr 2007
CERES SEVIRI DSLF
Bias RMSE Bias RMSE
Clear Sky -0.9 13.4 0.8 14.5
All Sky -1.4 22.7 1.6 22.5
Problems:- Temperature inversions
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
DSLF - Validation
LSA SAF DSLF colocated in space and time with
Ground Stations & CERES (http://aqua.nasa.gov/about/instrument_ceres.php)
Semi-arid & Desert StationsJan 2006 - Apr 2007
CERES SEVIRI DSLF
Bias RMSE Bias RMSE
Clear Sky 13.0 26.8 -4.4 14.1
All Sky 17.5 29.6 -5.4 16.9
Problems:- Impact of high aerosol loads
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
DSLF
Comparison with in situ data
-10 Wm-2 < Bias < 10 Wm-2
Root Mean Square Differences (RMS) ranges from considerably (from ~15 to 25 Wm-2)
LSA SAF estimates DSLF at the original satellite resolution (3 km at the sub-satellite point), every 30 –minutes, covering Meteosat disk
Satellite data provide Cloud information
Ministério da Educação e Ciência Instituto de Meteorologia, I. P. Rua C – Aeroporto de Lisboa 1749-077 Lisboa – Portugal Tel.: (351) 21 844 7000 Fax: (351) 21 840 2370 e-mail: [email protected] URL: http://www.meteo.pt
DSLF Applications – Please see presentation in Session 8
DSLF
As one of the components of the Surface Radiation Budget, DSLF applications include:
Forcing of Land Surface (and Hydrology) models
Model Assessment (surface and atmospherirc)
Case Studies