High Latitude L2 Sea and Sea Ice Surface Temperature (OSI-205-a/b)
The High Latitude Level-2 Sea Surface and Sea Ice Surface Temperature products are part of the Ocean and Sea Ice Satellite Application Facility's (OSI SAF's) product portfolio. The integrated Surface Temperature product consists of Sea and sea Ice Surface temperatures (SST and IST) and Land Ice Surface Temperatures (LIST) for the Greenland and Antarctic ice caps.
The OSI-205-a is based on Metop-B AVHRR data and covers the sea and ice areas polewards of latitudes 50N and 50S with 3 minute level-2 data segments, with data processed and archived continuously throughout the day, as data comes available. Approximately 110 3-minute segments per day. The production use AVHRR data from Metop from EUMETCast and cloud mask data using the PPS software from NoW-Casting Satellite Application Facility (NWC-SAF).
The OSI-205-b is based on NPP VIIRS data from the EARS service, and covers the areas poleward of 50N. FOR OSI-205-b there is one file for each orbit.
The product is distributed in GHRSST compliant netCDF format, as a stand-alone High Latitude Level 2 Surface Temperature product.
1. FAQ
How should I cite this dataset?
This dataset shall be referred to as the High Latitude Level-2 Sea Surface and Sea Ice Surface Temperature product from the EUMETSAT Ocean and Sea Ice Satellite Application Facility (OSI SAF, www.osi-saf.org). Or, just: EUMETSAT OSI-205-a/b IST/SST.
Which satellite sensors are processed?
The products are based on the AVHRR instrument on board the EUMETSAT Metop-B satellite, and VIRRS on board the NPP satellite. The surface temperature algorithms use data form infrared channels with central wavelength at 3.7, 11 and 12 microns, depending on the surface. The cloud products also use the visible channels, for sun lit pixels (see Algorithm Theoretical Basis Document).
What is the spatial resolution of this product?
The product is in level-2 and hence, the resolution is depending on the satellite view angle. At nadir the resolution is 1.1 km for AVHRR and 750m for VIIRS. Definitions for the projection parameters can be found in the NetCDF files as well as in the Product User's Manual.
What is the time-span of this product?
The OSI-205-a product is distributed in level-2 in 3 minutes segments, while the OSI-205-b is distributed in orbit segments. The segments become available continuously, as they are recorded and processed.
Today's product file is empty or has large data gaps, what happened?
The most likely cause for data gaps is the presence of clouds. The product is based on Thermal InfraRed data and hence, there are only valid surface temperature data for clear sky areas.
Data gaps can naturally also be caused by recording or processing failures, but that occurs only rarely.
I do not fancy NetCDF, do you have other formats?
The processing chain is currently only producing NetCDF files. Please let us know (contact) if you need another format and we will guide you to find a solution.
2. Algorithms
The product consists of a day and a night SST algorithm and 3 IST algorithms, one for each temperature domain. Surface temperatures in the Marginal Ice Zone are determined by a linear mixing of the SST and the IST algorithms (See the Algorithm Theoretical Basis Document).
3. Validation
Validation of OSI SAF data can be found in the product specific Validation Report, also referred to in Documentation and links, below. A half yearly validation report is written and can be made available on request.
4. Documentation and links
The following documentation is available, further describing the OSI-205-a/b products.
- Product User's Manual (both)
- Validation Report OSI-205-a
- Validation Report OSI-205-b
- Algorithm Theoretical Basis Document (both)
Quicklooks for these dataset can be accessed from this page.
