L3 PLB May 2008

L2 Pre-ProcessedL3 Pre processedL3 (collated)Analysed SST AcronymL2PL3PL3L4 DescriptionNative SST data streams reformatted into netCDF Native SST data streams reformatted into netCDF, remapped over a geographical grid, auxiliary data as in L2P Native SST data streams reformatted into netCDF, remapped over a geographical grid, synthesized over a period of time and adjusted against a reference, no auxiliary data. L4 analysed data provide an estimate of either the SSTfnd that is free of diurnal variability, SSTskin, SSTsubskin, SSTdepth at a specified depth or SSTdepth_blended from a blended analysis. Grid specificationNative to SST data format Geographical: stereopolar, regular,… Sections and Temporal resolutionNative to SST data stream Native or synthesis over a period of time Synthesis over a period of time Analysed product processing window See section 2.3 Delivery timescaleAs availablePredefined Within 12 hours of an APPW (T+12) - see section 2.3 Target accuracyNative to data stream Bias reduced by adjustment against the reference < 0.4 K absolute) 0.1 K relative Error statisticsNative to data stream if available, Sensor Specific error statistics otherwise SSES, bias adjustment, standard deviation of the adjustment and overall standard deviation attributable to the adjusted SST Standard Deviation for each output grid point (no input data statistics are retained) CoverageNative to data streamGlobal or regional Data ContentTable A1.4.2 and A1.4.3 Table A1.5.3 Nominal data formatnetCDF see Section A1.2

Summary flow diagram of the processing chain Remapping A11 L2P Format L2P data extended gridded L2P L2P data Synthesis over the time window A12 Calculation of differences with respect to reference sensor A14 Validate L4 product A16 Reference sensor L3 data Calculation of an error term A13 Production of “corrected collated” files A15 Collated files Buoy data Collated files With error estimates Collated files with difference compared to reference Rolling data archive Ancillary data Validation Reference Sensor.L3 Format Spec.

- -L3_GHRSST- - -adjusted[- ]- - File Version> NameDefinitionDescription Refer to Appendix A2 Table A2.1Processing centre code See Table A1.3.2 for area names The dataset concerned and the area covered by the L3 product YYYYMMDD Refers to the date for which this particular data set is valid Skin, subskin, fundationType of SST data vnn (where nn is the GDS version number, e.g., 01 Version number of the GDS system used to process the data file Fvxx.x (where xx.x is the release number of this filee.g.fv11.3[h1][h1] Release version for this L3 file string Free field to distinguish ambiguous cases (such as the same data centre producing two L3 files over the same region at spatial resolutions of 1/10  and 1/20  or producing more than one analysis per day) ncGeneric file format (nc=netCDF) For example: IFREMER-L3_GHRSST-SSTsubskin-MERGED_GLOBAL-adjusted-0000-v02-fv01.nc [h1] What does “11.3” mean here? Do we have to use a period (“.”) here?[h1]

Reference time latitude Original latitude Original longitude Number of original pixels SST_dtime SST Proximity confidence SSES bias error SSES standard deviation Reference bias error Reference error SD Satellite zenith angle Solar zenith angle Adjusted SST Adjusted standard deviation error Sources of SST Experimental field Content

issues  When merging different sensors onto the same collated : –Some sensors may have a lower resolution than the collated grid (ex : AMSRE, TMI) –Should we spread such pixels over several collated grid cells  Sources of sst –Number identifying product => should we use unique numbering? Easier to intercompare, difficult to maintain rigorously