Technical Bulletins

OSI SAF Metop-A IASI Sea Surface Temperature (SST) validation

The IASI SSTs have been validated by comparison with the OSI SAF AVHRR in situ matchup dataset.

IASI Validation

IASI SSTs have been collocated to in situ drifting and moored buoy measurements, and additionally compared with AVHRR SST observations.

The IASI SSTs from version 6 of the IASI L2 Product Processing Facility (PPF) show a slight cool bias against drifting buoys with the highest quality results (Quality Level 5) displaying a cool bias of -0.06 K (standard deviation 0.38 K).

The impact of the newly implemented Version 6 of the PPF is to reduce a previously observed IASI cool bias significantly for the higher quality results. For all quality levels the cool bias has been reduced by the new version by 0.1–0.2 K.

IASI Validation Differences
Figure 2: Binned plots showing the IASI SST minus drifting buoy SST versus latitude, satellite zenith angle, and wind-speed over the period April 2014 to December 2014.

Further information on the validation results can be found in OSI SAF Metop-A IASI Sea Surface Temperature L2P (OSI-208): Validation report (PDF, 1 MB).

Data information

IASI SSTs have been available since April 2008, contained within the EUMETSAT IASI Level 2 product. These data are available via EUMETCast, together with vertical temperature and humidity profiles in the BUFR product called IASI L2 TWT.

The Metop-A IASI L2Pcore SST product follows the Group for High Resolution Sea Surface Temperature (GHRSST) Data Processing Specification version 2, revision 5 (GDS2r5) and has been available via ftp from the Data Centre since March 2011, with Metop-B available since January 2014. The SSTs are based on those available from the IASI L2 product.

The IASI SST L2Pcore contains skin SSTs from the IASI PPF, flags, quality information and SSES, plus an auxiliary wind-speed field, but no further auxiliary data required for the complete GHRSST specification.

Within the Continuous Development and Operations Phase 2 of the EUMETSAT Ocean and Sea-Ice Satellite Application Facility (OSI SAF) a full GHRSST specified Metop-A IASI L2P SST is produced based on the Metop-A IASI L2Pcore SST from the central facilities.

The full L2P product has extra auxiliary data, such as sea-ice fraction and aerosol information, which is necessary to fulfil the complete GHRSST specification.

The SST retrieval from IASI is based on the 1D-VAR Optimal Estimation Method, recently updated with the Version 6 of the IASI Level-2 PPF from 30 September 2014.

Further information on the retrieval can be found in the IASI Level 2 product generation specification (PDF, 2 MB).

The IASI SSTs have been validated by comparison with the OSI SAF AVHRR in situ matchup dataset.

OSI-SAF IASI SST L2P product (OSI-208) has been declared operational and is available from the OSI SAF ftp site at Ifremer or via EUMETcast.

OSI-208 has been pre-operational since 20 November 2014, and available from the OSI SAF ftp site at Ifremer since the end of 2014. The OSI-208 has been available via EUMETcast since 8 January 2015.

Last Updated:  Wednesday, 29 June 2016