Satellite Remote Sensing of Evaporation over Sea
441
The coefficients ai used in eqations (16.15) and (16.16) are different from those used in (16.3).
An improvement can be expected from the Tropical Rainfall Monitoring Mission (TRMM)
which is scheduled for flight in 1997 where AVHRR and SSM/I will fly on the same orbiter,
allowing the simultaneous measurement of Tu , T12 , and w.
During night the use of the channels at 3.7 [lm allows an even better retrieval than the foregoing models because of the smaller water-vapour influence. Corresponding retrieval schemes
that have been developed include measurements made in all thermal channels. Again, the
consideration of quadratic terms improve the expected accuracies:
To = ao + a1T3.7 + a2(T3.7 - Tn) + a3(Tn - T12 ) + a4(T3.7 - TU)2 + a5(Tn - T12)2 (16.17)
The coefficients for retrieval models (16.16) and (16.17) designed for the use with AVHRR/NOAA11 are listed in table 16.5.
AVHRR retrieval model (16.16)
(} [0) Noise
ao
al
a2
a3
-
-
E
0
wlo -5.57 1.0221 1.7187 0.2000
-
-
0.23
0
with -10.45 1.0411
1.0271 0.3369
-
-
0.51
10
wlo -5.64 1.0224 1.7203 0.2037
-
-
0.23
10
with -10.51 1.0414
1.0360 0.3385
-
-
0.51
20
wlo -5.97 1.02381 1.7224 0.2152
-
-
0.25
20
with -10.77 1.0425
1.0716 0.3400
-
-
0.54
30
wlo -6.94 1.0276 1.7145 0.2419
-
-
0.30
30
with -11.48 1.0453
1.1213 0.3501
-
-
0.58
40
wlo -10.02 1.0394 1.6700 0.2979
-
-
0.39
40
with -13.81 1.0544
1.1705 0.3794
-
-
0.67
50
wlo -21.04 1.0816 1.5015 0.4227
-
-
0.66
50
with -23.11 1.0903
1.2192 0.4472
-
-
0.91
AVHRR retrieval model (16.17)
(} [0) Noise
ao
al
a2
a3
a4
a5
E
0
wlo -7.87 1.0299 -1.2631 1.7163 0.0848 0.2152 0.21
0
with -10.96 1.0422 -0.7718 1.5016 0.3358 0.09737 0.46
10
wlo -8.01 1.0304 -1.2694 1.7150 0.08407 0.2206 0.21
10
with -11.09 1.0427 -0.7793 1.5088 0.3315
0.1015 0.47
20
wlo -8.51 1.0324 -1.2701 1.7208 0.08815 0.2297 0.23
20
with -11.54 1.0444 -0.7922 1.5487 0.3230
0.1070 0.49
30
wlo -9.81 1.0373 -1.2698 1.7188 0.1000 0.2509 0.27
30
with -12.70 1.0488 -0.8161 1.6082 0.3117
0.1221 0.53
40
wlo -13.21 1.0502 -1.2620 1.6739 0.1121 0.3003 0.37
40
with -15.78 1.0603 -0.8470 1.6972 0.3005
0.1503 0.62
50
wlo -24.22 1.0926 -1.3086 1.5170 0.1609 0.40900 0.64
50
with -26.42 1.1007 -0.9633 1.8015 0.3337
0.2072 0.86
Table 16.5: Coefficients and errors for retrieval models (16.16) and (16.1'l).
The two-angle view of ATSR can be included by the following retrieval models for day and
night applications:
(16.18)