ISLSCP Initiative II

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Snow, Sea Ice, & Oceans Data

Sea Surface Temperature, 1 degree, Optimally Interpolated (Version 2)

Sea surface temperature (SST) is an important indicator of the state of the earth climate system as well as a key variable in the coupling between the atmosphere and the ocean. Accurate knowledge of SST is essential for climate monitoring, prediction and research. It is also a key surface boundary condition for numerical weather prediction and for other atmospheric simulations using atmospheric general circulation models and regional models. SST also is important in gas exchange between the ocean and atmosphere, including the air-sea flux of carbon. Gridded SST products have been developed to satisfy these needs.
      Gridded monthly and weekly sea surface temperature (SST) and long term SST monthly climatology for the period 1971-2000 are provided here. Weekly normalized error variance fields are also provided with the weekly data. The data are derived using the National Oceanic and Atmospheric Administration (NOAA) Optimum Interpolation (OI) global sea surface temperature analyses that use seven days of in situ (ship and buoy) and satellite SST observations and SST values derived from sea ice concentration. These analyses are produced weekly using optimum interpolation (OI) on a 1-degree grid. The data sets included in the ISLSCP2 data collection are produced using version 2 of the OI analyses, called OIv2. In this data set, the ISLSCP2 staff have masked land areas based on the ISLSCP2 land/water mask. A file describing the differences between the ISLSCP2 mask and the original mask used is provided.

Data Provider: Richard Reynolds, D.C. Stokes

Data Files (ISLSCP II Disc #1)

Data Set Documentation

Image Viewing Tutorial

File Information

The files can be decompressed using the PKZip program. Each file contains ASCII text with 360 values representing SST in degrees Celsius for each 1 by 1 degree pixel. A value of -999.9 represents missing data for water, -888.8 is missing data for land. There are 180 lines of data; one line for each degree of latitude. Each line is terminated by a newline character. The following files are included:

• sst_climate_1d_1971-2000-MM.asc: 12 files with the gridded monthly climatology of SST in degrees C averaged over any particular month during the period 1971-2000. 1d means that this data set is at a 1-degree spatial resolution in both latitude and longitude. MM is the month from 01 to 12.

• sst_oiv2_1d_YYYYMM00.asc: 120 files with the gridded monthly SST fields in degrees C. YYYY is the year from 1986 to 1995 and MM is the month from 01 to 12. The 00 means this is a monthly average.

• sst_oiv2_1d_YYYYMMDD.asc: 522 files with the gridded weekly SST fields in degrees C. YYYY is the year from 1986 to 1995 and MM is the month from 01 to 12. DD is the day for the middle of the weekly period. NOTE: For the 1980's the weeks are centered on Sunday (i.e. Thursday to Wednesday) and from the 1990's onward the weeks are centered on Wednesday (i.e. Sunday to Saturday). This small change leads to a three-day overlap in the weekly SST files for the last week of 1989 and the first week of 1990.

• sst_oiv2_error_1d_YYYYMMDD.asc: Same as above but for gridded weekly normalized error variance fields (unitless).

• mask_diffs_1d.asc: Gridded file with values describing the differences between the ISLSCP2 land/water mask and the original land mask. The values here can be either 0, 1, or 2 (see below for description).

The data are structured so that the upperleft corner of the first pixel is located at 90 North latitude and 180 West longitude. Each pixel represents a 1 by 1 degree area, with the pixel edges falling on whole degree boundaries.

Related Pages:
    ISLSCP Initiative II Home
        General Data Overview
            Snow, Sea Ice, Oceans Data Overview
                Sea Surface Temperature Data

Revision Date: September 2, 2003