SST ANOMALY MAPS - Computational Details
These data are now being obtained from the U.S. GODAE server (http://www.usgodae.org/) specifically the SFCOBS (Surface Observations: Ship, fixed/drifting buoy, and CMAN in-situ surface temperatures) available in binary format at http://www.usgodae.org/ftp/outgoing/fnmoc/data/ocn/sfcobs/. The following parameters are contained in this dataset:
- time: age of the observation in hours since January 1, 1992. provides a continuous time variable. reported to the nearest minute.
- ob_clm: GDEM SST climatological estimate at obs location and sampling time
- ob_csgm: GDEM SST climatology variability estimte at obs location and samling time
- ob_dtg: SST obs date time group in the form year, month, day, hour, minute (YYYYMMDDHHMM)
- ob_glb: SST global analysis estimate at obs location and samplingr time
- ob_gsgm: global SST analysis variability estimate at obs location and sampling time
- latitude: SST obs latitude (south negative)
- longitude: SST obs longitude (west negative)
- ob_qc: SST obs probability of a gross error (assumes normal pdf of SST errors)
- ob_rcpt: SST observation receipt time at FNMOC in the form year, month, day, hour, minute (YYYYMMDDHHMM);
- ob_rgn: SST regional analysis estimate at obs location and sampling time
- ob_rsgm: regional SST analysis variability estimate at obs location and sampling time
- ob_sign: SST observation call sign
- ob_sst: SST observation
- ob_typ: SST obseration data type; ship (ERI, bucket, hull contact), buoy (fixed, drifting), CMAN
- ob_wm: SST water mass indicator from Bayesian classification scheme.
Calculations are done as follows:
- The GODAE binary files are translated into netCDF format, which are available from the NOAA UAF ERDDAP server (http://upwell.pfeg.noaa.gov/erddap)
- Raw SST Means are calculated from all of the data in a 1-degree square
- Trimmed SST Means are calculated from all of the data for which the quality control flag ob_qc is less than or equal to 0.95 (that is two standard deviations).
- Anomalies are calculated by subtracting from any observation that passes the quality control test the GDEM climatological estimate given in the file for that observation. The given anomaly is the mean of the observed anomalies.
- The given climatology is the mean for the month of all of the GDEM climatological estimates used in step 4.