SURFACE SOLAR IRRADIANCE FROM SEVIRI SATELLITE DATAWouter Greuell, Jan Fokke Meirink and Ping WangRoyal Netherlands Meteorological Institute (KNMI)

DATA SET

• Input: SEVIRI (METEOSAT) cloud mask and cloud properties

• Spatial resolution: 3 x 3 km2 at nadir (4 x 7 km2 for NL)

• Temporal resolution: 4 images / hour

• From 2004

SICCS: SURFACE INSOLATION IN CLOUDY

CONDITIONS FROM METEOSAT SEVIRI IMAGERY - ALGORITHM

Measured radiances

attwo

wavelengths

Cloudproperties

SurfaceSolar

Irradiancefor

broadband

narrowbandRTM

broadbandRTM

Cloudmask

for clearpixel

forcloudypixel

Aerosolproperties,

Surfaceelevation

broadbandRTM

SOME REMARKS

• Global, direct and diffuse irradiance

• Algorithm is physics-based

INPUT

• Cloud mask from METEOSAT SEVIRI

• Cloud properties (phase, optical thickness and

particle size) from METEOSAT SEVIRI

• Aerosol optical depth from MACC

• Surface albedo derived from MODIS surface albedo

• Integrated water vapor from ECMWF

DIRECT IRRADIANCE FOR CLOUDY SKIES

• Plane-parallel assumption does not work

• Gaps in clouds are crucial

• On y-axis ratio of• Measured direct

irradiance• by computed clear-sky

direct irradiance

VALIDATION WITH BSRNBaseline Surface Radiation Network

Cabauw

Toravere

Payerne

Carpentras

Sede Boqer

PalaiseauCamborne

Lerwick

Lindenberg

Hourly means - 2006

CLEAR SKY DIRECT, MACC INPUT

green = spring, blue = summer, red = autumn, black = winter

Cabauw, direct Carpentras, direct

CLEAR SKY GLOBAL, MACC INPUT

green = spring, blue = summer, red = autumn, black = winter

Cabauw, global Carpentras, global

ALL SKY DIRECT

green = spring, blue = summer, red = autumn, black = winter

Cabauw, direct Carpentras, direct

ALL SKY GLOBAL

green = spring, blue = summer, red = autumn, black = winter

Cabauw, global Carpentras, global

SNOW ALL SKY

Lindenberg, global Toravere, global

MAP NETHERLANDS2006, global irradiance

1981-2010, precipitation

MAP IBERIAN PENINSULA

CONCLUSIONS

Station mean absolute value of the bias:Direct irradiance: 6 W/m2, 4.1% Diffuse irradiance: 5 W/m2, 3.4%Global irradiance: 7 W/m2, 1.9%

Strong points:high temporal and spatial resolutionbased on physicsability to deal with snowalbedo background map

Weak points:limited to METEOSAT disccoastal regionsrelief effects not considered

Data will be made available for user on the Internet

INTERPOLATION OF ALBEDO• From MODIS MCD43C3

• Temporal resolution: 8 days

• Spatial resolution: 0.05 x 0.05 degrees

• Combination of linear

interpolation and

mean annual cycle

• Includes snow

and ice

CLEAR SKY DIRECT, AERONET INPUTgreen = spring, blue = summer, red = autumn, black = winter

Cabauw, direct Carpentras, direct

CLEAR SKY DIFFUSE, AERONET INPUT

green = spring, blue = summer, red = autumn, black = winter

Cabauw, diffuse Carpentras, diffuse

CLEAR SKY GLOBAL, AERONET INPUT

green = spring, blue = summer, red = autumn, black = winter

Cabauw, global Carpentras, global

WATER CLOUDS GLOBAL

green = spring, blue = summer, red = autumn, black = winter

Cabauw, global Carpentras, global

ALL SKY GLOBAL

green = spring, blue = summer, red = autumn, black = winter

Cabauw, global Carpentras, global

TABLE BIASES

BSRN stationClear sky

BSRNClear sky SEVIRI

Water clouds

Ice clouds

All clouds

All skies

6 stations -0.001 +0.013 +0.009 -0.003 +0.004 +0.006

Lerwick -0.027 +0.021 +0.020 +0.015 +0.015 +0.016

Toravere -0.003 +0.007 +0.017 +0.039 +0.025 +0.020

Note: ice cloud transmissivity was corrected by -0.0375

Transmissivities

HIGH SOLAR ZENITH ANGLES

Cabauw, global Lindenberg, global

DEPENDENCE ON COT, REFF, SZA

10 YEARS MODIS ALBEDOVisual Near-infrared

COMPARISON IN-SITU DATA

Red: coastal stations

Blue: other stations

CLEAR DIRECT, MONTHLY AERONET

green = spring, blue = summer, red = autumn, black = winter

Cabauw, direct Carpentras, direct

CLEAR GLOBAL, MONTHLY AERONET

green = spring, blue = summer, red = autumn, black = winter

Cabauw, global Carpentras, global

OTHER INPUT

Measured radiances

attwo

wavelengths

Cloudproperties

SurfaceSolar

Irradiancefor

broadband

narrowbandRTM

broadbandRTM

Cloudmask

for clearpixel

forcloudypixel

Aerosolproperties,

Surfaceelevation

broadbandRTM

H2O,surfacealbedo,

SZA

H2O, surfacealbedo, SZA