RMIB involvement in the Geostationary Earth Radiation Budget (GERB) and Climate Monitoring SAF projects

Nicolas Clerbaux Remote sensing from Space Division Royal Meteorological Institute of Belgium

The remote sensing from space division of the RMIB

About 20 scientists/technicians working on the Earth radiation budget:Spaceborn measurement of the total solar irradiance (solar 'constant') – space shuttle, ISS, SOHO, picard.Processing of the GERB instrument data (MSG)Generation of TOA radiative flux products within the CM-SAF (MSG + polar sat.)

GERB project

Science goals:• Improvement of climate models by better understanding

the role of clouds and water vapour in the ERB,• Improvement of Numerical Weather Prediction (NWP)

models by data assimilation or near real-time validation,• Synergy with low orbit satellites observations:

improvement of the diurnal model,• Climate monitoring in the frame of the EUMETSAT

Satellite Application Facility on Climate Monitoring (CM-SAF).

Mission: accurate rapid broadband measurement of the reflected solar and emitted thermal radiation (first BB radiometer on the geo orbit).

Interest of the Meteosat Field-of-View

Also: desertification, African monsoon, marine stratocumulus, volcanoes, biomass burning, …

Aerosols

Tropical Convection

Contrails

Cirrus

blue : cooling effect red : warming effectunit : W/m²

Radiative effect of aerosols

biomass burning

mineral dust

GERB instrument

WAVEBANDSTotal: 0.32 µm - 100.0 µmShortwave, SW: 0.32 µm - 4.0 µm Longwave, LW (by subtraction): 4.0 µm - 100.0 µm

RADIOMETRY SW LWAbsolute Accuracy: < 1.0 % < 1.0 %Signal/Noise: 1250 400Dynamic Range: 0-380 W m-2 sr-1 0-90 W m-2 sr-1

SPATIAL SAMPLING: 44.6 39.3 km (NS EW) at nadir

TEMPORAL SAMPLING:15 minute SW and LW fluxes

CYCLE TIME: Full Earth disc, both channels in 5 minutes

CO-REGISTRATION Spatial: 3 km wrt SEVIRI at satellite sub-pointTemporal: Within 15 min of SEVIRI at each pixel

INSTRUMENT MASS 25 kg

POWER 35 W

Scanning25

6 de

tect

or p

ixel

s

282 steps

Measured (filtered) Radiance Images

shortwave [W/m²/sr] total [W/m²/sr]

GERB data processing

• Geolocation and calibration (RAL, UK)• Tuning of the geolocation wrt SEVIRI• Radiance unfiltering: correction for the instrument

spectral response • Conversion in flux: angular modelling of the radiation

field– Scene identification (surface, cloudiness,…)– Application of angular models

• Enhancement of the spatial resolution: 50km 10km• Near real-time dissemination (FTP) • Long term archiving and dissemination (RAL,UK)

At theRMIB

(Brussels)

Derived Fluxes Images (50km)

Solar [W/m²] Thermal [W/m²]

Current Status GERB acquisition on Meteosat-8 started December 2002

and is ongoing, The instrument is operating well, is stable and the

measurements have low noise Cross-calibration with other instruments (CERES)

indicates good performances of the instrument Release of Edition-1 data in March 2006

NRT generation of Edition-1 data Reprocessing of 02/2004 -> 03/2006 ongoing

10 May 2007 : switch to GERB on Meteosat-9 Validation not yet finished GERB becomes an operational EUMETSAT service

TOA Radiative Products in the Climate Monitoring SAFProduction of

monthly means, daily means, monthly means diurnal cycle

of incoming solar irradiance reflected solar flux emitted thermal flux net flux

from GERB data GERB-like data CERES data

CMSAF Status

Entering in the CDOP phase Reprocessing, reprocessing, reprocessing,... Extension of the dataset to Meteosat first

generation data (GERB-like) possibly generation of global products

Thank you !

More info? http://gerb.oma.be http://cmsaf.oma.be email: gerb@oma.be