Current
Retrieval Algorithms for Near-Surface Specific Humidity
The
retrieval algorithms for near-surface specific humidity, Qa,
and air temperature, Ta, all have the form:
Ta, Qa = C0
+ ∑CnTnM
where TM
indicates brightness temperatures in Kelvin from one of the three M instruments (A for AMSU-A, M for
SSM/I, and T for SSM/T-2), Cn indicates coefficients from the regression,
and the summation is over the n channels used for the regression.
The coefficients for the Qa
retrievals for the various instrument combinations are summarized in the
following table. The frequency for each
channel is noted in the left column and the superscripts indicate the order of
channel selection.
|
|
A/M/T |
M/T |
A |
M |
|
RMS (g/kg) |
0.83 |
1.06 |
0.92 |
1.12 |
|
C0 (g/kg) |
-105.117 |
-27.9036 |
-34.6310 |
-12.8597 |
|
A 23.8 |
|
|
0.22051 2 |
|
|
A 31.4 |
|
|
|
|
|
A 50.3 |
|
|
-0.51428 3 |
|
|
A 52.8 |
0.31743 1 |
|
1.13815 1
|
|
|
A 53.6 |
|
|
-0.66044 4 |
|
|
A 54.4 |
|
|
|
|
|
M 19V |
0.62754 2 |
|
|
|
|
M 19H |
-0.12056 4 |
|
|
|
|
M 22V |
|
0.30907 1 |
|
0.35341 1 |
|
M 37V |
-0.33940 3 |
-0.22467 2 |
|
-0.21166 2 |
|
M 37H |
|
|
|
-0.05988
3 |
|
T 183±3 |
|
|
|
|
|
T 183±1 |
|
|
|
|
|
T 183±7 |
|
0.06870 3 |
|
|
The
corresponding coefficients for the Ta retrievals are given as follows:
|
|
A/M |
A |
|
RMS (oC) |
1.53 |
1.95 |
|
C0 (oC) |
-191.986 |
-301.463 |
|
A 23.8 |
|
0.04230 2 |
|
A 31.4 |
|
|
|
A 50.3 |
-0.35046 5 |
|
|
A 52.8 |
1.05645 1 |
1.21225 1 |
|
A 53.6 |
|
|
|
A 54.4 |
|
|
|
M 19V |
0.65036 4 |
|
|
M 19H |
|
|
|
M 22V |
0.00493 2 |
|
|
M 37V |
-0.52680 3 |
|
|
M 37H |
|
|