Land Surface Temperature (LST) Retrieval from GOES Satellite Observations - Satellite-based Applications on Climate Change - page 317

Table 19.5 Accuracy/precision estimations of four seasons from GOES-12 LST retrieval

January April July October

Site N ACC PREC N ACC PREC N ACC PREC N ACC PREC

1.64 1.83 2.18 1.49 0.32

1 164 1.46 120 1.93 151 121 1.75

1.27 2.88 2.94 1.48 0.38

2 188 2.28 71 1.54 146 74 2.57

1.13 1.53 2.89 1.43

3 208 1.64 183 1.89 104 163 0.12 1.81

4 206 0.53 2.15 145 0.02 2.28 209 0.11 1.95 192 1.01 1.85

5 182 1.33 2.00 127 1.42 2.49 167 1.41 2.08 135 0.13 2.65

6 133 1.68 2.34 99 1.46 2.23 169 1.08 2.30 133 1.56 2.65

19.5.3 Precision and Accuracy Estimates

Table 19.5 shows the evaluation results of the GOES-12 LST from the dual-window
algorithm with emissivity approach against the SURFRAD observations at the six
stations. The accuracy (ACC) represents the mean bias (difference) error between
GOES-LST and SURFRAD observations. The precision (PREC) represents the
standard deviation error between GOES-LST and SURFRAD observations.
N indicates the total sample numbers. The station ID (STAID) is:

STAID ¼ 1, Bondville, IL

STAID ¼ 2, Fort Peck, MT

STAID ¼ 3, Goodwin Creek, MS

STAID ¼ 4, Table Mountain, CO

STAID ¼ 5, Desert Rock, NV

STAID ¼ 6, Penn State, PA

Shown in Table 19.5 are the accuracy (ACC) and precision (PREC) values for
the four seasons, respectively. It is worth of noting that the seasonal precision
values are still around 2.5 K. But the seasonal accuracy patterns vary from site to
site. It is unsure whether such distinct seasonal patterns might be related to the
different surface covers and regional climates. All these statistical features will be
further studied in the future.

19.5.4 Error Sources

19.5.4.1 Large Viewing Angle

The GOES sensor view geometry may have significant impact on the variation of
atmospheric absorption due to the radiative transfer path length increase from nadir to
the edge of the scan. Considering that altitude of GOES satellite is about 36,000 km
and the Earth radius is about 6,700 km, the relationship between the satellite zenith
angle (

θ ) and the satellite viewing angle ( θ v ) is (Sun and Pinker 2004 )