SMOS – in situ comparisons

J. Boutin*, N. Martin*, O. Hernandez*, N. Reul+, G. Reverdin*

*LOCEAN, +IFREMER

Outline

• SMOS-ARGO in 2012• SPURS-STRASSE comparisons• Gulf stream region

-SSS between 25 & 40 psu for latitudes between 30S & 30°N (Hence SSS=-999 are discarded)-SSS between 30 & 40 psu for latitudes outside 30°S-30N (Hence SSS=-999 are discarded)-Dg_af_fov >=130

In addition we test the following flags:

"control_flag_set=CTRL_SEL_GP;CTRL_ECMWF,"control_flag_clear=CTRL_NUM_MEAS_MIN;CTRL_NUM_MEAS_LOW;CTRL_MANY_OUTLIERS;CTRL_SUNGLINT;CTRL_MOONGLINT;CTRL_REACH_MAXITER;CTRL_MARQ;CTRL_CHI2_P;CTRL_CHI2;CTRL_SUSPECT_RFI","science_flag_set=SC_LOW_WIND;SC_LAND_SEA_COAST1","science_flag_clear=SC_ICE;SC_SUSPECT_ICE"

Some of these flags have been kept by continuity with previous versions. With respect to your comments:CTRL_SEL_GP is not used anymore => to be removedCTRL_CHI2 is redundant with CTRL_CHI2_P (in case of more than 30 meas.) =>to be removedCTRL_NUM_MEAS_MIN;CTRL_NUM_MEAS_LOW : useless if Dg_af_fov >=130 is tested (but may be useful if we would decide different levels of global flags, e.g., Good, probably good, probably bad, bad)SC_SUSPECT_ICE: taken by precaution; we also strongly recommend in v600 to define SC_ICE with Tg_ice_concentration=0% instead of 30%

CTRL_SIGMA: we don't use it because we always use sigma to weight our averages We don't use the combined flags poor_geophysical flag and fg_ctrl_poor_retrieval , as we prefer to get original flags (in case definitions of combined flags change).

Range of SSS: although we agree that SSS could be lower than 25 in the tropics, there are also a lot of RFIs not well filtered that can lead to low SSS so we prefer to be safe and I would recommend for a 'Good' flag to keep these ranges.

SPURS areaO. Hernandez, J. Boutin, G. Reverdin, N. Martin

Large scale bias between SMOS & AQUARIUS averaged over SPURS area

We first correct for a mean bias between SMOS & WOA or AQUARIUS & WOA

Comparisons SMOS-Toucan & Colibri(+/-9jours, +/-50km)

Mean and standard deviation of SSS SMOS – SSS TSG for each campaign (Colibri and Toucan). Correction of bias B1 is applied. In green: colocalisations in October 2011

Mean negative bias because WOA SSS often lower than in situ SSS

All data

R2 =0.78n = 30896 mean = -0.06 std = 0.2median = -0.04 RMSE = 0.21

Error < 0.4 PSS-78

R2 =0.81n = 23835 mean = -0.03 std = 0.18median = -0.02 RMSE = 0.19

Gulf Stream areaJ. Boutin, N. Reul, G. Reverdin

Results obtained with CATDS CEC (after RFI per angle classes filtering, 5°x5° bias correction)

L2 OS in Gulf Stream region26 transects of Oleander ship (validated by G. Reverdin): Asc+Desc, Des, Asc

Better consistency between SMOS Asc & SMOS Desc than with ship data

Þ Error on SSSA or SSSD~0.6 Þ but error SSSsmos A+D wrt Oleander = 1.2 WHY???