SMOS Quality Working Group Meeting #2 Frascati (Rome), September 13 th -14 th,2010 SMOS-BEC Team.

SMOS Quality Working GroupMeeting #2

Frascati (Rome), September 13th-14th,2010

SMOS-BEC Team

2 / Ntot

Outline

• METHODOLOGY• TESTS

1. RETRIEVAL MODE

Dual from Full vs. Stokes from Full

2. BIAS MITIGATION

No correction vs. External Bias Temperature Calibration vs. OTT

3. MODELS

Model 2 vs. Model 3(16)

4. SSS SELECTION

All overpasses vs. Ascending vs. Descending

5. TB SELECTION

EAF vs. AF

6. NEW FTR

July vs. August• CONCLUSIONS (+ or -)

3 / Ntot

Methodology

All the results presented are at Level 3 (10-day 2-degree product).

Retrievals have been performed using SMOS-OS Level2 Processor.

Level 2 data have been filtered according to:

Fg_ctrl_reach_maxiter1,2,3: Maximum number of iteration reached before

convergence.

Fg_ctrl_marq1,2,3: Iterative loop ends because Marquardt

increment is greater than lambdaMax (100).

Statistical characterization is done considering only points more than 200 km from the coast

Fg_sc_land_sea_coast1 = 1 & Fg_sc_land_sea_coast2 = 0

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Methodology

L2 L3 averaging has been performed according to:

iobsi

iobsiiL

L N

NSSSSSS

2

3

The L3 accuracy is also introduced to someway estimate the quality of the measurement

iobsi

iobsiiLiL

L N

NSSSSSSACC

2

22

3

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Tests

1.RETRIEVAL MODE

10 days of retrieval from July, 10th to 19th

ISEA4H9 ISEA4H8 to reduce the computational resources needed

Model 2 in the mode “Stokes from Full-Pol” has been used

OTT has been applied in accordance to the official DPGS product

L3 retrieved SSS is compared to NOAA WOA05 climatology and ARGO averaged data

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Tests – Dual vs. Stokes’ I

L3 maps - Dual

Amazon plume

Cold waters

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L3 maps - Stokes’ I

Amazon plume

Cold waters

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L3 maps

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L3 maps - Accuracy

2.5 psu

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L3 statistics - Dual

rms

0.2260 2.2565 2.2678

0.5559 1.4457 1.5489

rms

0.2958 1.4391 1.4692

0.5278 0.5805 0.7846

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L3 statistics – Stokes’ I

rms

0.2445 2.3505 2.3631

0.6157 1.5464 +7%

rms

0.2935 1.6756 1.7011

0.6080 0.5932 0.8495

+4%

1.6645

+14%

+8%

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Tests

2.BIAS MITIGATION



Model 2 in the mode “Dual from Full-Pol” has been used

No correction, external brightness temperature calibration[*], and OTT have been applied


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Tests – Bias mitigation

External Brightness Temperature Calibration

Constant within the snapshot (xi, eta) but varying in time

Ocean Target Transformation

Constant in time but varying within the same snapshot

snapshotmodretcorr TBTBTBTB

),( modretcorr TBTBTBTB

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L3 maps – No bias mitigation

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L3 maps – External Brightness Temperature Calibration

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L3 maps – External Brightness Temperature Calibration

MEAN BIAS SUBTRACTED

Less intense land-sea transition effect

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L3 maps – Ocean Target Transformation

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L3 maps - Accuracy

2.5 psu

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L3 statistics – no bias mitigation

rms

3.9591 2.6742 4.7776

3.3468 3.7604 5.8288

rms

4.1488 1.8571 4.5455

3.5769 0.6343 3.6327

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L3 statistics – External Brightness Temperature Calibration

rms

2.9600 2.3886 3.8036

2.1981 1.7300 2.7972

rms

3.1541 1.7764 3.6199

2.2214 0.5801 2.2959

-14% -20%

-52% -37%

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L3 statistics – Ocean Target Transformation

rms

0.2260 2.2565 2.2678

0.5559 1.4457 1.5489

rms

0.2958 1.4391 1.4692

0.5278 0.5805 0.7846

-52%

-73%

-68%

-78%

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Tests

3.MODELS



OTT has been applied as for the official DPGS product

Model 2 and Model 3(16) are compared


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Tests – Model 2 vs. Model 3(16)

L3 maps – Model 2

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L3 maps – Model 3(16)

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L3 maps

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SST L3 maps

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WS L3 maps FROM ASCAT

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Scatterplot

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L3 maps - Accuracy

2.5 psu

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L3 statistics – Model 2

rms

0.2445 2.3505 2.3631

0.6157 1.5464 1.6645

rms

0.2935 1.6756 1.7011

0.6080 0.5932 0.8495

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L3 statistics – Model 3(16)

rms

0.8302 2.5735 2.7041

0.8490 1.7188 1.9171

rms

0.9346 1.9486 2.1611

0.9522 0.6619 1.1597

+13%

+13%

+21%

+27%

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Tests

4.SSS SELECTION




L3 averaging has been performed using ALL the overpasses, only the ASCENDING ones, and only

the DESCENDING ones


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Tests – All vs. Ascending vs. Descending

L3 maps - All

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L3 maps - Ascending

Fresher when ice/land enters in the FOV

Saltier when it exits

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L3 maps - Descending Generally saltier

Fresher when ice/land enters in the FOV

Saltier when it exits

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L3 maps – comparisons with Ext TB cal


land-sea contamination

a previous study

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L3 statistics - All

rms

0.2260 2.2565 2.2678

0.5559 1.4457 1.5489

rms

0.2958 1.4391 1.4692

0.5278 0.5805 0.7846

ALL PASSES ALL PASSES

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L3 statistics - Ascending

rms

-0.0214 3.3183 3.3183

0.2175 1.5405 1.5557

rms

-0.3585 3.0150 3.0362

0.1239 0.8506 0.8595

+32%

=

+52%

+9%

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L3 statistics - Descending

rms

0.3851 2.9766 3.0014

0.9942 1.7178 1.9848

rms

0.7824 1.8510 2.0096

1.0820 0.9610 1.4472

+24%

+22%

+27%

+46%

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Tests

5.TB SELECTION


ISEA4H9 has been used

Model 2 in the mode “Dual from Full-Pol” is analized


TB with a have been filtered out to almost reproduce the AF-FOV


25.022

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Tests – EAF vs. AF

AF-FOV approx.

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L3 maps - EAF

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L3 maps - AF

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L3 maps – AF minus EAF

Ascending positive

Descending negative

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L3 statistics - EAF

rms

-0.1680 2.7191 2.7242

0.4170 1.1453 1.2189

rms

0.0068 1.8762 1.8762

0.3608 0.6828 0.7722

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L3 statistics – AF

rms

-0.0867 2.8017 2.8030

0.5254 1.2677 1.3722

rms

0.0674 1.9639 1.9650

0.4797 0.7427 0.8841

+3%

+11%

+5%

+13%

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Tests

6.NEW FTR

10 days of retrieval from July, 10th to 19th and August, 20th to 29th are compared

as produced by the DPGS:

ISEA4H9 has been used

Model 2 in the mode “Dual from Full-Pol” is analyzed

OTT has been applied


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Tests – July vs. August

L3 maps - July

50 / Ntot


L3 maps - August Generally fresher

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August minus July

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L3 statistics - July

rms

-0.0308 2.6585 2.6587

0.5923 1.0897 1.2403

rms

0.1905 1.7765 1.7867

0.5401 0.5574 0.7762

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L3 statistics – August

rms

-0.4285 2.8671 2.8990

0.2659 1.1050 1.1366

rms

-0.2197 1.8899 1.9027

0.2691 0.5818 0.6410

+8%

-8%

+6%

-17%

Conclusions (+ or -)

1. Dual from Full vs. Stokes from Full

4-14 % increment in SSS misfit rms using Stokes’ I

2. No correction vs. External Bias Temperature Calibration vs. OTT

Ext TB cal. partially diminishes the SSS misfit rms, OTT has a very

strong improvement effect.

Ext TB cal partially corrects for the land-sea transition effect and

seems to work better in the North Atl. waters (?)

The combined use of both techniques can be envisaged…

3. Model 2 vs. Model 3(16)

Model 3 is still in definition, conf. 16 (from WISE) has been used,

performing relatively close to Model 2. difference between models

are strongly related to SST.

4. All overpasses vs. Ascending vs. Descending

Waters appear fresher when land/ice enters in the FOV and saltier

when it exits when using only ascending or descending passes, the effect

is compensated using both. Descending passes give

generally saltier SSS.

Conclusions (+ or -)

Ext TB calibration gives more homogeneous results…again the

combined use can be envisaged…

5. EAF vs. AF

Using only AF FOV a positive bias has been found in the ascending

passes, negative in the descending, w.r.t the case of using EAF FOV.

Change in statistics is small.

6. July vs. August

August 10-day SSS misfit is in average 0.3-0.4 psu fresher than

July’s SSS misfit.

Anyway statistics are very similar and no clear improvement can

be observed.

SMOS Quality Working Group Meeting #2 Frascati (Rome), September 13 th -14 th,2010 SMOS-BEC Team.

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Transcript of SMOS Quality Working Group Meeting #2 Frascati (Rome), September 13 th -14 th,2010 SMOS-BEC Team.