SURFACE SOLAR IRRADIANCE FROM SEVIRI SATELLITE DATA Wouter Greuell, Jan Fokke Meirink and Ping Wang...

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