Where CLIMO is the climatological SST for the nearest 1
0 latitude/longitude intersection
16. HIRS Cloud Test Using HIRS and Field and Climo Temps (refer to last page)
17. Store SST in SST Initial Storage File
Note:
AVHRR Channel
Wavelength (Φm)
1
0.550- 0.90
2
0.725- 1.10
3
3.550- 3.93
4
10.500-11.50
5
11.500-12.50
Use of HIRS data to detect cloud contamination
HIRS algorithm
D=3.5 -0.2333 (H 8 - H 7 ) + 0.038446*SATFLD + 1.612 (SEC ș - 1)
Where:
H8 - HIRS Channel 8 Temperature
H 7 - HIRS Channel 7 Temperature
HIRS cloud test (Night and Day relaxed visible cloud mode)
IF D > D 1
Test is failed
Field test
If | MCSST - A.SAT FLD - (1- A) CLIMO | > D2 Test if failed
A= input coefficient = 0.666
D 1 AND D 2 - Threshold values are read in from data files
Current settings: Daytime (only used in WRMSPT mode) D1=0.5 D2=3.0
Nighttime D1=0.5 D2=2.5
This is a combined test. Both tests musts be failed for rejection (HIRS and field test).
25
Extreme Events and Perturbations