1. GERB STM, Exeter, Oct. 20061 SW Diurnal Errors in ERB monthly means: some studies from CERES and GERB LMD/IPSL M. Viollier and A. Ben Rehouma Ecole Polytechnique, Palaiseau, France

2. GERB STM, Exeter, Oct. 20062 Comparison between the SW monthly means over two regions Reg#1 the whole area (45°S-45°N/60°W-60°E) Reg#2 (35°-10°S/10°W-10°E) with systematic diurnal cycle sharp diurnal errors SW standard deviation Month: August

3. GERB STM, Exeter, Oct. 20063 SW Mean over Reg#1 Monthly Anomaly defined / all available years Scanners Nonscanner ISCCP-FD Negative trend See also, Wong et al (2006) Zhang et al (2004), for the tropical mean

4. GERB STM, Exeter, Oct. 20064 Regional Anomaly (Reg # 2 – Reg # 1) Nonscanner ISCCP-FD +1.5 ± 3.0 +3.0 ± 0.8 Slope Wm -2 /decade ±  taking autocorrelation into account, according to Weatherhead et al JGR (1998) More on our Friday presentation

5. GERB STM, Exeter, Oct. 20065 Scanner Serie (Reg # 2 – Reg # 1) with Terra with Average of Terra and Aqua +5.0 ±1.5 +1.1 ± 2.0

6. GERB STM, Exeter, Oct. 20066 Diurnal corrections for CERES-Terra, several approaches SRBAVG geo products ( about 2 years, 2000/03  2004/05) Combination (or average) of Terra and Aqua (ES4, about 4 years, 2002/07  2005/12) Examination of GERB ARG Ed1 products 5 months: 2006, 04 to 08)

7. GERB STM, Exeter, Oct. 20067 Diurnal error, January 2003 Computed from differences between CERES SRBAVG GEO – NON GEO 1 x 1° Computed from differences between (Aqua+Terra) and Terra alone 2.5 x 2.5 °

8. GERB STM, Exeter, Oct. 20068 Diurnal error, October 2003

9. GERB STM, Exeter, Oct. 20069 SW Diurnal Errors, reg 2 (up), reg 1 (down) REG2 REG1

10. 10 Comparisons between contemporary T-(TA) and nonGeo-Geo / 2003 Agreement at least for these areas and their differences; the variations are higher for SRBAVG

11. GERB STM, Exeter, Oct. 200611 Same for Albedo, 2003

12. GERB STM, Exeter, Oct. 200612 GERB, 2006 July, 17-18 LW flux SW flux

13. GERB STM, Exeter, Oct. 200613 Diurnal Cycle – August 2006 Area: 2.5x2.5° X 100

14. GERB STM, Exeter, Oct. 200614 Albedo Diurnal Cycle – hourly means- off Angola Area: 2.5x2.5° May 2006April 2006 July 2006 Aug 2006

15. GERB STM, Exeter, Oct. 200615 Albedo Diurnal Cycle – hourly means- Sahara Area: 2.5x2.5° May 2006April 2006 July 2006 Aug 2006

16. GERB STM, Exeter, Oct. 200616 SW Monthly Means Computations with GERB Average the fluxes (2.5°x2.5°) and fill the 24x31 day-hour table Use ‘ERBE-type’ code, with Terra flux estimates (ES9- Ed1 - CV ) to compute monthly means Repeat using the GERB observed diurnal albedo variation shape in place of the ERBE modeled albedo

17. GERB STM, Exeter, Oct. 200617 GERB April 2006 GERB2006

18. GERB STM, Exeter, Oct. 200618 SRBAVG, TA and GERB April GERB2006 SRBAVG2003 SRBAVG2002 TA2003

19. GERB STM, Exeter, Oct. 200619 SRBAVG, TA and GERB August SRBAVG 2001 GERB2006 SRBAVG2003 TA2003

20. GERB STM, Exeter, Oct. 200620 Summary of Diurnal Errors Wm -2 Reg2 – Reg1JJANDJYear SRBAVG nonGeo-Geo 4.610.46.5 Terra- Ave( Terra,Aqua) 4.29.46.6 GERB correction applied to Terra 4.9-- Caution: Not the same years for each case

21. GERB STM, Exeter, Oct. 200621 Conclusion We have looked for inter-regional differences in the evolution of the SW reflected flux (Reg1, Reg2) Reg 2 (South East Atlantic): diurnal errors are critical when using ES4-Terra (morning observation) Significant agreement between 3 independent evaluations of the relative diurnal errors (SRBAVG, Aqua, GERB); waiting for overlapping periods This is shown only for the studied regions and for their differences The 1985-2005 SW positive change (relatively to the average Reg1) observed with Terra seems slightly greater than the diurnal error

22. 22 Indo-French Megha-Tropiques satellite project - 2009 Saphir : microwave sounder for water vapour sounding : 6 channels in the WV absoption band at 183.31 GHz. (cross track, 10 km) MADRAS : microwave imager for precipitation : channels at 18, 23, 37, 89 and 157 GHz, H and V polarisations. (conical swath, <10 km to 40 km) ScaRaB

23. GERB STM, Exeter, Oct. 200623 The three instruments of Megha-Tropiques ScaRaB : wide band instrument for inferring longwave and shortwage outgoing fluxes at the top of the atmosphere (cross track scanning, 40 km resolution at nadir) Saphir : microwave sounder for water vapour sounding : 6 channels in the WV absoption band at 183.31 GHz. (cross track, 10 km) MADRAS : microwave imager for precipitation : channels at 18, 23, 37, 89 and 157 GHz, H and V polarisations. (conical swath, <10 km to 40 km)