SMOS L2 OS ATBD - ARGANS

86
ICM-CSIC
LOCEAN/SA/CETP
IFREMER
SMOS L2 OS
Algorithm Theoretical
Baseline Document
4.4.1.3. Error budget estimates (sensitivity analysis)
Doc: SO-TN-ARG-GS-0007
Issue: 3 Rev: 9
Date: 25 January 2013
Page: 86
In Camps et al., 2004, authors observe that the uncertainty of the brightness temperature
sensitivity to wind speed is on the order of 0.1 K/(m/s) for all incidence angles, when using
the model only dependent on WS. Therefore, for WS=10 m/s, the uncertainty of the
brightness temperature Tb is about 1 K. Taking into account the brightness temperature
sensitivity to SSS (0.35-0.8 K/psu at V-pol, and 0.20-0.6 K/psu at H-pol), it translates at 10
m/s into a ∆SSS within 1.2-5 psu.
4.4.2. Practical considerations
4.4.2.1. Calibration and validation
Roughness model 3 will be validated comparing SMOS SSS retrieved maps with this
roughness model with SSS maps created with interpolated ARGO data.
4.4.2.2. Quality control and diagnostics
Because of its empirical derivation, the model’s accuracy will be degraded for exceptional
geophysical conditions, such as winds above 15m/s and wave height above 8m, for which
very few SMOS observations are available.
4.4.2.3. Exception handling
There is no particular exception handling in the algorithm except if the following
auxiliary data are not provided by the processor or exceed the ranges of the LUT:
the wind speed, WS
the significant wave height, Hs
the incidence angles i at SMOS pixel
If one of the prior values of the retrieved geophysical parameters is out of the LUT range, or
if any retrieved geophysical parameter goes out of LUT range during the retrieval, different
flags (Fg_OoR_Rough_dim1, Fg_OoR_Rough_dim2, Fg_OoR_Rough_dim3,
Fg_OoR_Rough_dim4) are raised. No extrapolation is done and the boundary value is taken.