SMOS L2 Ocean Salinity Level 2 Ocean Salinity status 4 February 2013 ARGANS

SMOS L2 Ocean Salinity 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

SMOS L2 Ocean Salinity First results with v600 L2OS & L1PP L1OP v504L1PP v600delta = v600 – v504 AFFOV median (X/Y) 0.35/ / /1.14 Single orbit OTT: T153815

SMOS L2 Ocean Salinity First results with v600 L2OS & L1PP L1OP v504L1PP v600delta = v600 – v504 (not using new L1c RFI flags)

SMOS L2 Ocean Salinity First results with v600 L2OS & L1PP Cross-track salinity profile (latitude -15 to 0) L1OP v504 (slope -0.04/degree) L1PP v600 (slope -0.03/degree)

SMOS L2 Ocean Salinity First results with v600 L2OS & L1PP Cross-track salinity quality profile (latitude -15 to 0) L1OP v504 L1PP v600

SMOS L2 Ocean Salinity Need to evaluate integration between v600 L1PP & L2OS new sun point/tail width new RFI flags Test 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

SMOS L2 Ocean Salinity Filters and flags Previous 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)

SMOS L2 Ocean Salinity Filters and flags In AUX_CNFOSF, filter MEASUREMENT_DECISION_TREE is defined as: Measurement_decision_tree Fm_resol Fm_outlier Fm_L2_RFI_snapshot_out_of_range Fm_out_of_range Fm_xi_eta Fm_border Fm_moon_spec_dir Fm_gal_noise_error Fm_high_sun_glint Fm_L1c_sun Fm_suspect_ice Fm_L1c_error which is easier to read and modify. Flag names are defined in the ADF.

SMOS L2 Ocean Salinity Filters and flags Flag names used in filters are defined in AUX_CNFOSF, eg: Fm_L1c_sun 0x x Fm_sun_glint_fov 0x0008 0x0008 Fm_sun_point 0x0080 0x0080 Set_sun_flag_from_L1c Set Fm_L1c_sun measurement flag from L1c flag(s) Fm_sun_glint_fov Fm_sun_point 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): Fm_RFI_XX 0x0040 0x0040 Fm_RFI_YY 0x4000 0x4000 (Maybe flag names should be in schema?)

SMOS L2 Ocean Salinity Filters and flags Flags can be combined to make filters easier to read Fg_sc_land 0x x Fg_sc_ocean 0x x Fg_sc_coast 0x x Fg_sc_near_land 0x x and user Grid_point_decision_tree Clear Fg_ctrl_valid for ignored grid points Fg_sc_land Fg_sc_coast Fg_ctrl_num_meas_min Fg_sc_ice

SMOS L2 Ocean Salinity RFI v600 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: , , , & 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...

SMOS L2 Ocean Salinity RFI test orbits v550v T034234

SMOS L2 Ocean Salinity RFI test orbits v550v T161301

SMOS L2 Ocean Salinity RFI test orbits v550v T055514

SMOS L2 Ocean Salinity RFI test orbits v550v T214604

SMOS L2 Ocean Salinity RFI test orbits v550v T191812

SMOS L2 Ocean Salinity RFI: snapshot out-of-range Snapshot discarded if any out-of-range TBs & no land/ice contamination T Threshold 50K in AFFOV, 100K in EAFFOV & <20% land/coast/ice pixels in snapshot

SMOS L2 Ocean Salinity RFI: snapshot standard deviation Snapshot discarded if standard deviation / radiometric accuracy too high (eg RFI tails) T Threshold 2.5 K & > 35% measurements in snapshot

SMOS L2 Ocean Salinity RFI: measurement outliers Measurements discarded if dwell line standard deviation / theoretical std too high T Threshold 2.4 (was 1.2) & > 3% RFI outliers & > 15 measurements RFI tails not detected by snapshot std/ra

SMOS L2 Ocean Salinity RFI: measurement outliers Why is std/theory above theoretical value of 1.2? Measurement outlier detection computes outliers differently:

SMOS L2 Ocean Salinity RFI: summary Test 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_DGGRFI Dg_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)

SMOS L2 Ocean Salinity 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 T v600 Iceberg at 59S, 163W v550 Fg_sc_ice_acard

SMOS L2 Ocean Salinity But icebergs trigger false RFI measurement outlier detection Cardioid model & iceberg detection AcardFm_L2_RFI_outlierFg_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 T191812

SMOS L2 Ocean Salinity Proposed evolution for v650 TEC from Stokes 3 Analyse prototype/breadboard: test near land, low TEC regions, & ascending orbits Land-mass proximity update to AUX_DISTAN Thresholds 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 modified ESL requests for retrieved WS in UDP,... Review DAP: add OTT data Supports drift analysis & automatic OTT generation – xi/eta, replaces Tb_gal_H/V, snapshot ID replaced Diff_TB_4 L2OS v650