Www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI study 9 May 2011 ARGANS & L2OS ESL.
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www.argans.co SMOS L2 Ocean Salinity L2OS RFI study 9 May 2011 ARGANS & L2OS ESL
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Transcript of Www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI study 9 May 2011 ARGANS & L2OS ESL.
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI study
9 May 2011
ARGANS & L2OS ESL
www.argans.co.uk
SMOS L2 Ocean Salinity
new 2 step RFI outlier detection algorithm based on reducing outlier threshold if high probability of RFI detected
for pol = 0 to 3 /* Stokes 1..4 */ if std(TBmodel[pol] - TBsmos[pol]) > 1.2 * std_theory then
rfi_outlier_risk[pol] = TRUE
if rfi_outlier_risk[pol] then for each measurement
if abs(TBmodel[pol] - TBsmos[pol]) > 3 * rad_noise then Fm_L2_rfi = TRUE
wherestd_theory = √ ((TB_radiometric_noise2 + TBmodel2 ) / nMeas)factor of 1.2 is 99% confidence with 100 measurements (1 + 0.18)nsig is reduced from 5 (non-RFI outlier detection threshold) to 3
Outliers & RFI
www.argans.co.uk
SMOS L2 Ocean Salinity
>200 km from landFg_ctrl_suspect_rfi set if Fm_L2_RFI > 50%
L2OS RFI detection(early version of algorithm)
www.argans.co.uk
SMOS L2 Ocean Salinity
>40 km from landFm_outlier never set because
algorithm skipped outlier test if risk of RFI detected
L2OS RFI detection(early version of algorithm)
www.argans.co.uk
SMOS L2 Ocean Salinity
no RFI detection RFI detectionFm_L2_RFI higher % than Fm_outlier (ie more sensitive)
L2OS RFI detection(early version of algorithm)
www.argans.co.uk
SMOS L2 Ocean Salinity
no RFI detection RFI detection deltaProblem: RFI detection works well, but impacts non-RFI retrievals, because measurements discarded if Fm_L2_RFI set even if < 50%
L2OS RFI detection(early version of algorithm)
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SMOS L2 Ocean Salinity
Dg_RFI_L2 = count(Fm_L2_rfi)if (Dg_RFI_L2 / Dg_num_meas_L1c) > Tg_num_RFI_max (50%) then
Fg_ctrl_suspect_rfi = TRUE
if Fg_ctrl_suspect_rfi thenif Fm_L2_rfi then
Fm_valid = falseelse /* use ‘normal’ non-RFI outlier test */
if Fm_outlier thenFm_valid = false
Outliers & RFI – extended algorithm
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SMOS L2 Ocean Salinity
Fg_ctrl_suspect_rfi set if Fm_L2_RFI > 50% Fm_outlier also set, even if risk of RFI detected
Fm_L2_RFI higher % than Fm_outlier (ie more sensitive)
L2OS RFI detection(current algorithm)
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SMOS L2 Ocean Salinity
no RFI detection RFI detection delta (= RFI – no RFI)Some additional retrievals in Arctic (> 200km from coast)
L2OS RFI detection(current algorithm)
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detection(current algorithm)
no RFI detection RFI detection deltaAdditional retrievals in North Pacific & Arctic
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detection(current algorithm)
> 40km from coast > 200km from coast False RFI detection near Antarctic ice
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SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
SM_OPER_MIR_OSDAP2_20110425T185354_20110425T194756_317_001_1(unfiltered)
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
SM_OPER_MIR_OSDAP2_20110425T185354_20110425T194756_317_001_1(filtered: 44329/82665)
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
SM_TEST_MIR_OSDAP2_20110425T185354_20110425T194756_500_001_8(filtered: 48522/82212)
L2 RFI outlier test >40km
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
SM_OPER_MIR_OSDAP2_20110502T051050_20110502T060452_317_001_1(unfiltered)
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
SM_OPER_MIR_OSDAP2_20110502T051050_20110502T060452_317_001_1(filtered: 17957/62361)
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
SM_TEST_MIR_OSDAP2_20110502T051050_20110502T060452_500_001_8(filtered: 21683/61963)L2 RFI outlier test >40km
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
SM_OPER_MIR_OSDAP2_20110430T085851_20110430T095250_317_001_1(unfiltered)
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
SM_TEST_MIR_OSDAP2_20110430T085851_20110430T095250_500_001_8Fg_ctrl_suspect_RFI
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
SM_OPER_MIR_OSDAP2_20110430T085851_20110430T095250_317_001_1(filtered: 17899/53953)
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
SM_TEST_MIR_OSDAP2_20110430T085851_20110430T095250_500_001_8(filtered: 21506/53520)
L2 RFI outlier test >40km
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
317 500 no RFI detection 500 with RFI detectionSM_OPER_MIR_SCSF1C_20110313T055704_20110313T065103_346_001_1
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
317 500 no RFI detection 500 with RFI detectionSM_OPER_MIR_OSDAP2_20110413T141055_20110413T150454_317_001_1
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
317 500 no RFI detection 500 with RFI detectionSM_OPER_MIR_OSDAP2_20110413T155057_20110413T164459_317_001_1
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
317 500 no RFI detection 500 with RFI detectionSM_OPER_MIR_OSDAP2_20110413T164100_20110413T173501_317_001_1
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
317 500 no RFI detection 500 with RFI detectionSM_OPER_MIR_SCSF1C_ 20110413T041028_20110413T050427_346_001_1
www.argans.co.uk
SMOS L2 Ocean Salinity
L2OS RFI detectioncomparing 0317 & v500
317 500 no RFI detection 500 with RFI detectionSM_OPER_MIR_OSDAP2_20110313T200742_20110313T210141_317_001_1
www.argans.co.uk
SMOS L2 Ocean Salinity
unfiltered
filtered
Fm_L2_RFI
Fg_ctrl_suspect_rfi
L2OS RFI detectioncomparing 0317 & v500
317 500 no RFI detection 500 with RFI detectionSM_OPER_MIR_OSDAP2_20110313T123721_20110313T133122_317_001_1
www.argans.co.uk
SMOS L2 Ocean Salinity
Outliers & RFI
• Conclusions– new L2 RFI algorithm detects RFI– once detected, RFI measurement selection
enables &/or improves retrieved salinity– L1 coast contamination causes false RFI positives
– RFI thresholds need tuning with new L1
– L2OS configuration can turn RFI detection/mitigation off if required
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SMOS L2 Ocean Salinity
Decision: RFI distance-to-coast
>40km >200kmSM_TEST_MIR_OSDAP2_20110313T005649_20110313T015043_318_001_8
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SMOS L2 Ocean Salinity
Decision: RFI distance-to-coast
>40km >200kmSet coast limit >40km & find good values for
RFI_std, RFI_nsig &Tg_num_RFI_max with new L1PP
