1. Jean-Louis Roujean CNRM / Météo-France
SOLAR RADIATION
VALIDATION

2. DSSF daily cycle

3. DSSF Validation Strategy
Validation with in-situ data: Carpentras, Roissy
Other ground stations: Data access to be coordinated with other SAFs
Satellite product inter-comparison (SAFs,…)
Comparison with model output (ECMWF)

4. Validation with in situ measurements

5. DAILY TIME SERIES EXAMPLES
Clear
Sky
Clear
Sky
AOT
440nm
X10-3
Cloudy Sky
Cloudy Sky

7. Comparisons with in-situ measurements (period 2004-2006)
Stat à 2006
Clear sky :
bias : 5 W/m2
stdev : 40 W/m2
Cloudy sky :
Bias : 5 W/m2
stdev : 115 W/m2

8. VALIDATION TIME SERIES: ALL SITES
6 Stations in Europe ( )
4 Stations in Africa (2006)
Overestimation of the radiation
in clear sky situations
(potentially due to aerosol effect)
bias=5W/m2
stdev=40W/m2
bias=45W/m2
stdev=75W/m2
absolute
absolute
bias=5W/m2
stdev=115W/m2
bias=-2W/m2
stdev=125W/m2
absolute
absolute

9. Validation of DSSF over France with RADOME network (8 km)

10. Yearly profile (2006) of DSSF for 2 contrasted sites Carpentras (Provence) & Roissy (Paris airport)
ECMWF: -> under-estimate (clear) & over-estimate (cloudy)

11. DSSF Validation : NIAMEY (from RADAGAST project, ARM mobile station)
March, 2
May, 12
July, 1

12. DSSF Validation : AGOUFOU (CESBIO data)
January, 13
March, 2
May, 12

13. Comparison of DSSF SAF-LAND / ECMWF – August 2005
> Tracking
of convective zones
-> Less radiation

14. Daily DSSF (DIDSSF)
Comparison between daily cumulative DSSF (DIDSSF) (left) and ECMWF forecast product (SSRD) over France at different dates during June 2009.

15. Comparison between daily cumulative DSSF (DIDSSF) (left) and ECMWF forecast product (SSRD) over France at different dates during June 2009.

16. COMPARISON WITH MODIS ALBEDO
[0.4µm,0.7µm]
16-day average MSG Albedo –
MODIS albedo projected
on SEVIRI grid
[0.7µm,4µm]
over Europe (from to )
[0.3µm,4µm]
10-25 juin 2006

17. Comparison MSG with MODIS

18. MSG – MODIS : absolute difference MSG – MODIS : relative difference
VISIBLE Broad-Band
June 10, 2005
MSG – VIS-DH
SAF Land – Quality Flag
MSG – MODIS : absolute difference
MSG – MODIS : relative difference

19. MSG – MODIS : absolute difference MSG – MODIS : relative difference
NIR Broad-Band
June 10, 2005
MSG – NIR-DH
SAF Land – Quality Flag
MSG – MODIS : absolute difference
MSG – MODIS : relative difference

20. Statistical results (bias/stdev) between broadband albedos MSG et MODIS over Europe
Bias is negligible except
VIS = (due to aerosols ?)
Standard deviation :
0.015 for VIS
0.030 for NIR

21. Albedo Time Series: Evora
0.6µm 0.8µm 1.6µm
[0.4µm,0.7µm] [0.3µm,4µm] [0.7µm,4µm]

22. Albedo Time Series: Barrax
0.6µm 0.8µm 1.6µm
[0.4µm,0.7µm] [0.3µm,4µm] [0.7µm,4µm]

23. COMPARISON WITH MODIS ALBEDO
12-27 juillet 2006

24. MSG – MODIS : absolute difference MSG – MODIS : relative difference
VISIBLE Broad-Band
July 19, 2006
MSG – VIS-DH
SAF Land – Quality Flag
MSG – MODIS : absolute difference
MSG – MODIS : relative difference
Bias = 0,047 ; RMSE = 0,026

25. ALBEDO TIME SERIES (Agoufou; Mali)
X10 for AOT
Modis SW-DH albedo
SAF-Land albedo
Observed albedo
Rainfall
The temporal evolution of the albedo estimate is related to the evolution of surface properties (typically rainfall). The spurious fluctuations appear to be caused by aerosol effects.

26. ALBEDO TIME SERIES (Banizoumbou; Niger)
The temporal evolution of the albedo estimate is related to the evolution of surface properties (typically rainfall). The spurious fluctuations appear to be caused by aerosol effects.

27. ALBEDO TIME SERIES (Niamey; Niger)
The temporal evolution of the albedo estimate is related to the evolution of surface properties (typically rainfall). The spurious fluctuations appear to be caused by aerosol effects.