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ISCCP/GISS ISCCP/UMD UMD/MODIS July 2001 Zonal Mean all-sky surface SW down W/m 2 ) Figure 1.

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Presentation on theme: "ISCCP/GISS ISCCP/UMD UMD/MODIS July 2001 Zonal Mean all-sky surface SW down W/m 2 ) Figure 1."— Presentation transcript:

1 ISCCP/GISS ISCCP/UMD UMD/MODIS July 2001 Zonal Mean all-sky surface SW down W/m 2 ) Figure 1.

2 How usefull are global satellite estimates of SW for polar regions? At Issue: Unequal and sparse Coverage Number of ISCCP D1 AVHRR and Geostationary observations October 1986 Figure 2.

3 01/01/2001 Figure 3.

4 Differences due to the way solar zenith angle for 3- hourly intervals Is computed GISS: every 20 min UMD: analytically Figure 4.

5 Figure 5. ERBE and CERES ADMs for different surface types for SZA of 60°- 70° and Azimuth Angle of 150°-170° over clear sky (left panel) and over cloudy sky (right panel).

6 Figure 6. ADMs for different surface types (clear sky) for Solar Zenith Angles of 40º-50º and viewing angles for 20º-30º

7 Arctic sea ice extent on 16 September 2007 was 23% lower than the previous record minimum in August 2005, and 39% lower than the average value. Source : NSIDC Figure 7.

8 Witze, A., Losing Greenland. Nature, Figure 8

9 Change in Antarctic Ice Mass Ice Mass (km 3 ) Year Rich Deem Figure 9

10 Comparison of monthly mean surface downward SW fluxes from UMD/MODIS, CERES, ISCCP/GISS and ISCCP/UMD/SRB against 3 BSRN ground observation sites in Antarctic from September 2002 to August The mean observation is 210 W/m 2 (Wang, 2007). Sources (Resolution)Cor. Coef.RMSE (%)BIAS (%) UMD/MODIS (1 ° ) (12)-1.4(1) CERES(1 ° ) (29)-42.3(20) ISCCP/GISS(2.5 ° ) (27)-36.0(17) ISCCP/UMD/SRB(2.5 ° ) (18)-19.0(9) Table 1.Table 1. Table 1.

11 MODIS Estimates with revised algorithm  Processed at 1-deg resolution for 3 years ( ).  Feasibility demonstrated to implement MODIS at 5-km resolution (see Figure 13) Monthly mean SW surface down flux (W/m**2), 2001 MODIS V004: Modified SRB Figure 10

12 Daily mean surface SW flux estimated by UMD/SRB_MODIS against PIRATA and TAO/TRITON buoys January 1, December 31, 2005 Cases eliminated: 1.1% (PIRATA); 1.3% (TAO/TRITION ) Figure 11

13 BSRN Sites (39)

14 Daily and monthly mean SW flux estimated by UMD/SRB_MODIS against BSRN measurements over land January, 2003-December, 2005) Cases eliminated: 1.6% (Daily) Figure 12

15 PAR over US, Day 185, 2001, 18:20 Z, W/m 2 Figure 13

16 Surface SW fluxes at 5 km resolution at 1:30 PM, August 1, 2003 Figure 14


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