MyOcean Global Ocean OSTIA Sea Surface Temperature

Summary

Provider: MyOcean - UK Met Office

Contact person: Service Desk of MyOcean (Send mail)

Contact for production: Service Desk at UK Met Office (Send mail)

Algorithm development: UK Met Office

Document: OSTIA descriptionOceans07.pdf

The Operational Sea surface Temperature and Ice Analysis (OSTIA) analysis provides an estimate of the foundation SST, ocean temperature at a depth which is free of diurnal variations. The analysis has been designed to meet the needs of applications requiring high-resolution space-time scales including global numerical weather prediction and operational ocean models. It is used by environmental, marine, meteorological and climate organizations and research institutions for seasonal forecasts, climate change detection, environmental approach, productivity.

Units: K, Range: ~270K and ~305K

Data Portal: MyOcean 2

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Platform & processing

The UK Met Office processing chain generates the product. The processing software is not publicly available, it is UK Met Office intellectual property. The OSTIA system has been running operationally at the UK Met Office since November 2006. The output is a daily global coverage combined SST and sea-ice concentration product on a 0.05°. grid, based on measurements from several satellite and in situ SST data sets.

Algorithm

OSTIA uses SST data in the common format developed by GHRSST and makes use of the uncertainty estimates and auxiliary fields as part of the quality control and analysis procedure. Satellite measurements are bias corrected for sensors that provide skin SST to bulk SST by adding 0.17K. Single sensor error statistics include a bias estimate which is removed from the observation value. Daily analysis of the bias for each satellite sensor is then performed. Satellite derived sea ice products from the EUMETSAT Ocean and Sea Ice Satellite application Facility (OSI-SAF) provide sea-ice concentration and edge data to the analysis system. After quality control of the SST observations, then bias correction is performed using AATSR data as a key component. To provide the final SST analysis, a multi-scale optimal interpolation (OI) is performed using the previous analysis as the basis for a first guess field.

The OSTIA global Sea Surface Temperature product provides daily gap-free maps of sea surface temperature, referred as L4 product, at 0.05°x 0.05° horizontal resolution, using in-situ and satellite data from both infrared and microwave radiometers

OSTIA system uses data from a combination of infrared and microwave satellites as well as in situ data : AATSR (Envisat), AMSR-E (Aqua), AVHRR (NOAA), SSM/I (DMSP), SEVIRI (MSG) TMI (TRMM), in situ drifting and moored buoys:

  • AATSR (Envisat) - Infrared - Global 1 km resolution (swath)
  • AMSR-E (Aqua) - Microwave - Global 25 km resolution (swath
  • AVHRR-LAC - Infrared - NE Atlantic and Mediterranean 0.1° resolution (gridded)
  • AVHRR-GAC - Infrared- Global 9 km resolution (swath)
  • SSM/I (DMSP) - Microwave - Global 10 km resolution (polar stereographic grid)
  • SEVIRI - infrared - Atlantic sector 0.1° resolution (gridded)
  • TMI (TRMM) - microwave - Tropics 25 km resolution (swath)
  • In situ temperature and salinity - ships, drifting and moored buoys.

MyOcean suggest documentation describing the a reanalysis product that ceased production in 2007 is useful.

Product uncertainties

Ingestion of various products with different algorithms (cloud mask, land/sea mask, ...) can be a limitaion.

An automated verification system produces daily mean and RMS statistics of observation-minus-analysis and observations-minus-background for each of the observation types used in the analysis. The High-Resolution Diagnostic DataSet (HRDDS) system based at NOCS is used to compare OSTIA with different input data and with other analysis data-sets for specific regions. OSTIA is also included in the GHRSST Multi-Product Ensemble (GMPE) system which provides a monitoring tool for inter-comparison with other analysis data-sets.

Product dissemination

These products are not distributed via GEONETCast, but MyOcean sourced data are distributed via the internet.

Product is delivered in NetCDF format

Product validation

Product is peer reviewed. The background for the SST analysis is formed using an SST anomaly persistence, derived from the previous days analysis and a climatology valid for the same time and a climatology for the new analysis time. Several near real time SST analysis are available, including RTG analysis which is primarily based on AVHRR data, and Remote Sensing Systems (RSS) optimal interpolation SST which is based on microwave SST from AMSR-E and TMI. The outputs are compared with buoys.

Data characteristics

Global coverage at 0.05 ° resolution (~5km), can also be subsetted to the Mediterranean area (30°N to 46°N ; 6°W to 36.5° E) for download.

Daily product available around 0600 UTC using a rolling observation window of 36 hours, centered on 1200 UTC.

Projection: cylindrical equidistant

Format: NetCDF files.

Additional products quantifying the estimated error standard deviation of analysed_sst and a sea/land/lake/ice field composite mask are available.

Notes

Useful references:

Bell, M.J., R.M. Forbes and A. Hines, 2000, Assessment of the FOAM global data assimilation system for real-time operational ocean forecasting. J. of Marine Systems, 25(2000) 1-22.

Martin, M.J., A. Hines and M.J. Bell, 2007. Data assimilation in the FOAM operational short-range ocean forecasting system: a description of the scheme and its impact. Q.J.R. Meteorol. Soc., 133:981-995.

John D. Stark, Craig J. Donlon, Matthew J. Martin and Michael E. McCulloch, 2007, OSTIA : An operational, high resolution, real time, global sea surface temperature analysis system., Oceans '07 IEEE Aberdeen, conference proceedings. Marine challenges: coastline to deep sea. Aberdeen, Scotland. IEEE .