level 2 ocean salinity status

SMOS L2 Ocean Salinity

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Level 2 Ocean Salinitystatus

4 February 2013

ARGANS


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FAT 18/19 December 2012 – redelivery 25/1/2013 with updated schema

Significant changes from v550

• new RFI snapshot level detection, improved RFI outlier detection

• new galactic noise model LUTs (ascending/descending)

• filters & flags moved from code to configuration ADFs

• improved Acard filtering near ice

• changes to UDP & DAP formats

• removed Fg_ctrl_gal_noise from Fg_ctrl_poor_geophysical

• bug fixes to iterative scheme, TB_42.5, galactic noise flagging

L2OS v600 status


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First results with v600 L2OS & L1PP

L1OP v504 L1PP v600 delta = v600 – v504AFFOV median (X/Y) 0.35/-1.12 1.30/-0.12 0.92/1.14

Single orbit OTT: 20100802T153815


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First results with v600 L2OS & L1PP

L1OP v504 L1PP v600 delta = v600 – v504(not using new L1c RFI flags)


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First results with v600 L2OS & L1PPCross-track salinity profile(latitude -15 to 0)

L1OP v504(slope -0.04/degree)

L1PP v600(slope -0.03/degree)


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First results with v600 L2OS & L1PPCross-track salinity quality profile(latitude -15 to 0)

L1OP v504

L1PP v600


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Need to evaluate integration between v600 L1PP & L2OS

• new sun point/tail width

• new RFI flagsTest with more than one orbit: 9 RFI orbits used to tune L2OS RFI algorithms

v600 L2OS & L1PP integration

Fm__L1c_RFI_YY

Fm__L1c_sun_tailsFm__L1c_sun_point

Fm__L2_RFI_outlier


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Filters and flagsPrevious versions of L2OS embedded filtering (eg for grid point & measurement selection) in the code:

if( (ISTRUE(meas->l2flags,fm_resol) == TRUE) ||

((ISTRUE(meas->l2flags,fm_outlier) == TRUE) && (ISTRUE(gp->report->ctrlFlags, fg_ctrl_suspect_rfi) == FALSE))||

((ISTRUE(meas->l2flags,fm_l2_rfi) == TRUE) && (ISTRUE(gp->report->ctrlFlags, fg_ctrl_suspect_rfi) == TRUE))||

(ISTRUE(meas->l2flags,fm_out_of_range) == TRUE) ||

(ISTRUE(meas->l2flags,fm_chi_eta) == TRUE) ||

(ISTRUE(meas->l1flags,fml1c_border_fov) == TRUE) ||

((!ISTRUE(meas->l1flags,fml1c_af_fov) == TRUE) && (decision_tree->switch_af == TRUE)) ||

(ISTRUE(meas->l2flags,fm_moon_specDir) == TRUE) ||

(ISTRUE(meas->l2flags,fm_gal_noise_error) == TRUE) ||

(((ISTRUE(meas->l2flags,fm_high_sun_glint) == TRUE) && (ISTRUE(meas->l2flags,fm_low_sun_glint) == FALSE))) ||

(ISTRUE(meas->l2flags,fm_l1c_sun) == TRUE) ||

(ISTRUE(meas->l2flags,fm_suspect_ice) == TRUE) ||

(ISTRUE(meas->l2flags,fm_l1c_error) == TRUE) )

v600 replaces this by a filter defined in AUX_CNFOSF. Code replaced by:if (applyFilter(configHandle,MEASUREMENT_DECISION_TREE,meas,gp->report[ == TRUE)


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Filters and flagsIn AUX_CNFOSF, filter MEASUREMENT_DECISION_TREE is defined as:

<Filter><Name>Measurement_decision_tree</Name>

<List_of_tests count="12">

<Reject>Fm_resol</Reject>

<Reject>Fm_outlier</Reject>

<Reject>Fm_L2_RFI_snapshot_out_of_range</Reject>

<Reject>Fm_out_of_range</Reject>

<Reject>Fm_xi_eta</Reject>

<Reject>Fm_border</Reject>

<Reject>Fm_moon_spec_dir</Reject>

<Reject>Fm_gal_noise_error</Reject>

<Reject>Fm_high_sun_glint</Reject>

<Reject>Fm_L1c_sun</Reject>

<Reject>Fm_suspect_ice</Reject>

<Reject>Fm_L1c_error</Reject>

</List_of_tests>

</Filter>

which is easier to read and modify. Flag names are defined in the ADF.


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Filters and flagsFlag names used in filters are defined in AUX_CNFOSF, eg:

<Flag> <Name>Fm_L1c_sun</Name><Mask>0x00000010</Mask> <Test>0x00000010</Test> </Flag>

<Flag> <Name>Fm_sun_glint_fov</Name> <Mask>0x0008</Mask><Test>0x0008</Test></Flag>

<Flag> <Name>Fm_sun_point</Name><Mask>0x0080</Mask><Test>0x0080</Test></Flag>

<Filter><Name>Set_sun_flag_from_L1c</Name>

<Description>Set Fm_L1c_sun measurement flag from L1c flag(s)</Description>

<List_of_tests count="2">

<Reject>Fm_sun_glint_fov</Reject>

<Reject>Fm_sun_point</Reject>

</List_of_tests>

</Filter>

This mechanism allows new flags to be defined & used in filters without recompilation & delivery of a new L2OS build (eg L1 v600 new RFI flags):

<Flag> <Name>Fm_RFI_XX</Name> <Mask>0x0040</Mask><Test>0x0040</Test></Flag>

<Flag> <Name>Fm_RFI_YY</Name><Mask>0x4000</Mask><Test>0x4000</Test></Flag>

(Maybe flag names should be in schema?)


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Filters and flagsFlags can be combined to make filters easier to read

<Flag> <Name>Fg_sc_land</Name><Mask>0x00000003</Mask><Test>0x00000000</Test></Flag>

<Flag> <Name>Fg_sc_ocean</Name><Mask>0x00000003</Mask><Test>0x00000001</Test> </Flag>

<Flag> <Name>Fg_sc_coast</Name><Mask>0x00000003</Mask><Test>0x00000002</Test></Flag>

<Flag> <Name>Fg_sc_near_land</Name><Mask>0x00000003</Mask><Test>0x00000003</Test></Flag>

and user<Filter.>

<Name>Grid_point_decision_tree</Name>

<Description>Clear Fg_ctrl_valid for ignored grid points</Description>

<List_of_tests count=“4">

<Reject>Fg_sc_land</Reject>

<Reject>Fg_sc_coast</Reject>

<Reject>Fg_ctrl_num_meas_min</Reject>

<Reject>Fg_sc_ice</Reject>

</List_of_tests>

</Filter.>


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RFIv600 has 3 RFI detection algorithms:

snapshot out-of-range

snapshot standard deviation

measurement outlier detection

New UDP fields support AUX_DGGRFI

L2OS job order optionally uses AUX_DGGRFI

AUX_CNFOSF has several new RFI detection thresholds (& filters), tuned with L1c v504/505, with 9 test orbits: 20100709, 20100730, 20110209, 201206010 & 20120611

Balance achieved between too many false positives (land, sun/tails, ice, tec...) and visible RFI/tails missed. Visual (snapshot) & statistical analysis performed.

Need to repeat tuning with L1c v600 & compare with new L1c RFI flags...


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RFI test orbits

v550 v60020100709T034234


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RFI test orbits

v550 v60020100709T161301


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RFI test orbits

v550 v60020100730T055514


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RFI test orbits

v550 v60020100730T214604


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RFI test orbits

v550 v60020120611T191812


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RFI: snapshot out-of-rangeSnapshot discarded if any out-of-range TBs & no land/ice contamination

20100709T161301Threshold 50K in AFFOV, 100K in EAFFOV& <20% land/coast/ice pixels in snapshot


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RFI: snapshot standard deviationSnapshot discarded if standard deviation / radiometric accuracy too high (eg RFI tails)

20100709T161301Threshold 2.5 K& > 35% measurements in snapshot


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RFI: measurement outliersMeasurements discarded if dwell line standard deviation / theoretical std too high

20100709T161301Threshold 2.4 (was 1.2)& > 3% RFI outliers & > 15 measurements

RFI tails not detected by snapshot std/ra


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RFI: measurement outliersWhy is std/theory above theoretical value of 1.2?

Measurement outlier detection computes outliers differently:


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RFI: summaryTest with L1c v600 & compare with new L1c RFI flags

Check & tune RFI filters

snapshot out-of-range filter

> 40km from land, no ice, ignore border, sun point (tails?)

snapshot standard deviation filter

> 40km from land, no ice, AFFOV, border, sun point (tails?), out-of-range

measurement outlier filter

>200km from land, border, sun point/glint fov (& tails), out-of-range, hi std

Monitor AUX_DGGRFIDg_RFI_X/Y counts Fm_L2_RFI, set by out-of-range & outlier tests (filters could be changed to set Fm_L2_RFI from any/all of the above tests, & from L1c flags)


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Acard measurement selection previously discarded TBs that were too high for open ocean, but expected for ice. In v600 Acard is retrieved over ice & land, so ice extent & icebergs can be seen & flagged.

Cardioid model & iceberg detection

20110825T171549 v600

Iceberg at 59S, 163W

v550

Fg_sc_ice_acard


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But icebergs trigger false RFI measurement outlier detection

Cardioid model & iceberg detection

Acard Fm_L2_RFI_outlier Fg_ctrl_suspect_RFI

std/theory for the centre of the iceberg at 57S is 16.8, with 46% measurements flagged as RFI outliers

False RFI measurement outlier detection will probably also occur for fresh water lenses.

20120611T191812


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Proposed evolution for v650

• TEC from Stokes 3Analyse prototype/breadboard: test near land, low TEC regions, & ascending orbits

• Land-mass proximity update to AUX_DISTANThresholds of 40km & 200km in v600 & earlier filters processing near islands as well as large land masses, but we suspect small islands do not cause land/sea contamination

• UDP fields modifiedESL requests for retrieved WS in UDP, ...

• Review DAP: add OTT dataSupports drift analysis & automatic OTT generation – xi/eta, replaces Tb_gal_H/V, snapshot ID replaced Diff_TB_4

L2OS v650

level 2 ocean salinity status

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