ISCCP/GISS

ISCCP/UMD

UMD/MODIS

July 2001 Zonal Mean all-sky surface SW down W/m2)

Figure 1.

How usefull are global satellite estimates of SW for polar regions? At Issue: Unequal and sparse Coverage

Number of ISCCP D1 AVHRR and Geostationary observationsOctober 1986

Figure 2.

01/01/2001

Figure 3.

Differences due to the way solar zenith angle for 3-

hourly intervalsIs computed

GISS: every 20 min

UMD: analytically

Figure 4.

Clear; SZA(60°-70°); Azimuthal Angle(150°-170°)

00.5

11.5

22.5

33.5

44.5

5

0 10 20 30 40 50 60 70 80 90View Zenith Angle

An

isotr

opic

Fact

or

ERBE OceanERBE VegetationERBE DesertERBE SnowCERES OceanCERES VegetationCERES DesertCERES Snow

Overcast; Tau(2.5-5.0); SZA(60°-70°); Azimuthal Angle(150°-170°)

0

0.5

1

1.5

2

2.5

3

3.5

0 10 20 30 40 50 60 70 80 90View Zenith Angle

Anis

otr

opic

Fact

or

ERBE

CERES Ocean

CERES Vegetation

CERES Desert

CERES Snow

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).

Figure 6.

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

0

0.2

0.4

0.6

0.8

1

1.2

0 10 30 50 70 90 110 130 150 170Azimuth Angle

Ani

sotr

opic

Fac

tor

snowicewater

Arctic sea ice extent on 16 September 2007 was 23% lower than the previous record minimum in August 2005, and 39% lower than the 1979-2000 average value. Source :

NSIDC

Figure 7.

Witze, A., Losing Greenland. Nature, 2008.

Figure 8

Change in Antarctic Ice Mass

1000

800

600

400

200

0

-200

-400

-6002003 2004 2005

Ice

Mas

s (k

m3 )

Year Rich Deem

Figure 9

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 2003. The mean observation is 210 W/m2 (Wang, 2007).

Sources (Resolution) Cor. Coef. RMSE (%) BIAS (%)

UMD/MODIS (1°) 0.99 25.7(12) -1.4(1)

CERES(1°) 0.95 59.8(29) -42.3(20)

ISCCP/GISS(2.5°) 0.94 56.7(27) -36.0(17)

ISCCP/UMD/SRB(2.5°) 0.97 37.2(18) -19.0(9)

Table 1.

Table 1.

MODIS Estimates with revised algorithm

Processed at 1-deg resolution for 3 years (2001- 03).

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

Daily mean surface SW flux estimated by

UMD/SRB_MODIS against PIRATA and TAO/TRITON buoys January 1, 2003-December 31, 2005

Cases eliminated: 1.1% (PIRATA); 1.3% (TAO/TRITION)

Figure 11

BSRN Sites (39)

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

PAR over US, Day 185, 2001, 18:20 Z, W/m2

Figure 13

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

Figure 14