1.  TITLE

1.1  Data Set Identification.

     Sea surface temperature.

     (Monthly ; NMC)

1.2  Data Base Table Name.

     Not applicable.

1.3  CD-ROM File Name.


     Note: capital letters indicate fixed values that appear on the CD-ROM
     exactly as shown here, lower case indicates characters (values) that
     change for each path and file.

     The format used for the filenames is: YyyMmm.sfx, where yy is the last
     two digits of the year (e.g., Y87=1987), and mm is the month of the year
     (e.g., M12=December).  The filename extension (.sfx), identifies the 
     parameter in the file (i.e. SST=Sea Surface Temperature).

1.4  Revision Date Of This Document.

     April 5, 1995.

                         2.  INVESTIGATOR(S)

2.1  Investigator(s) Name And Title.

     Dr. Richard W. Reynolds
     Ms. Diane Stokes
     National Meteorological Center
     5200 Auth Road, Room 807
     Camp Springs, MD 20746, USA

2.2  Title Of Investigation.

     National Meteorological Center (NMC) global sea surface temperature 

2.3  Contacts (For Data Production Information).

              |       Contact 1           |       Contact 2            |
2.3.1 Name    |Dr. Richard W. Reynolds    |Ms. Diane Stokes            |
2.3.2 Address |National Meteorological    |National Meteorological     |
              |  Center                   |  Center                    |
              |5200 Auth Road, Room 807   |5200 Auth Road, Room 807    |
      City/St.|Camp Springs, MD           |Camp Springs                |
      Zip Code|20746                      |20746                       |
2.3.3 Tel.    |(301) 763-8396             |(301) 763-8396              |
2.3.4 Email   | wd01rr@sgi11.wwb.noaa.gov |wd01dm@sgi26.wwb.noaa.gov   |
              |  (internet)               |  (internet)                |

2.4  Requested Form of Acknowledgment.

     Please cite the following publication when these data are used:

     Reynolds, R. W. and T. M. Smith, 1994. Improved global sea surface
         temperature analyses. J. Climate, 7:929-948.

                            3.  INTRODUCTION

3.1  Objective/Purpose.

     Develop high resolution gridded Sea Surface Temperature (SST) fields 
     using in situ and satellite data.

3.2  Summary of Parameters.

     Gridded monthly sea surface temperature.

3.3  Discussion.

     The National Meteorological Center (NMC) global sea surface
     temperature analyses use seven days of in situ (ship and buoy) and
     satellite SST.  These analyses are produced weekly using optimum
     interpolation (OI) on a 1-degree grid. The OI technique requires
     the specification of data and analysis error statistics. These
     statistics show that the SST rms data errors from ships are almost
     twice as large as the data errors from buoys or satellites. In
     addition, the average e-folding spatial error scales have been
     found to be 850 km in the zonal direction and 615 km in the
     meridional direction.

     The analysis also includes a preliminary step that corrects any satellite
     biases relative to the in situ data using Poisson's equation. The
     importance of this correction is demonstrated using recent data following
     the 1991 eruptions of Mt. Pinatubo. The OI analysis has been computed
     using the in situ and bias corrected satellite data for the period
     November 1981 to present.

     The monthly analyses presented here were computed by linearly
     interpolating the weekly fields to produce daily fields and then
     averaging the appropriate days within a month to produce monthly

                        4.  THEORY OF MEASUREMENTS

     There are two main sources of SST measurements:  in situ and
     satellite.  The in situ observations are direct temperature
     measurements made from ships (roughly 80%) and buoys.  The ship
     observations are primarily (roughly 70%) made by measuring the
     temperature of water used for engine cooling.  Almost all the
     remaining ship measurements are obtained from thermometers placed
     in insulated buckets which have been thrown overboard and filled
     with sea water.  The buoy observations are made by thermistors
     which evaluate ocean temperature by either measuring the hull
     temperature of the buoy or measuring the temperature of the water
     directly.  The depth of the measurement varies from roughly 20
     meters (intake for engine cooling) to several meters (small

     The satellite observations are obtained by measuring the infrared
     radiation using the Advanced Very High Resolution Radiometer
     (AVHRR) on the U.S. National Oceanic and Atmospheric
     Administration polar orbiting satellites. These data were
     produced operationally by NOAA's Environmental Satellite, Data
     and Information Service (NESDIS).  The satellite retrieval
     algorithms actually measure the temperature of the ocean using
     several different infrared frequencies to eliminate the
     interference caused by atmospheric water vapor.  These algorithms
     only work in cloud free areas.  Because the algorithms only
     measure a skin temperature (with depths on the order of
     millimeters), the retrivevals are tuned against in situ
     temperatures from drifting buoys.  A discussion of these
     algorithms can be found in:

     McClain, E. P., W. G. Pichel, and C. C. Walton, 1985: Comparative
          performance of AVHRR-based multichannel sea surface
          temperatures. J. Geophys. Res., 90, 11587-11601.

     Walton, C. C., 1988: Nonlinear multichannel algorithms for
          estimating sea surface temperature with AVHRR satellite

                        5.  EQUIPMENT

5.1  Instrument Description.

     Not available at this revision.

     5.1.1  Platform (Satellite, Aircraft, Ground, Person...).

            Not available at this revision.

     5.1.2  Mission Objectives.

            Not available at this revision.

     5.1.3  Key Variables.

            Not available at this revision.

     5.1.4  Principles of Operation.

            Not available at this revision.

     5.1.5  Instrument Measurement Geometry .

            Not available at this revision.

     5.1.6  Manufacturer of Instrument.

            Not available at this revision.

5.2  Calibration.

     Not available at this revision.

     5.2.1  Specifications.

            Not available at this revision.


                     Not available at this revision.

     5.2.2  Frequency of Calibration.

            Not available at this revision.

     5.2.3  Other Calibration Information.

            Not available at this revision.

                        6.  PROCEDURE

6.1  Data Acquisition Methods.

     For the data in this archive, the in situ data were obtained from a
     preliminary version of the Comprehensive Ocean Atmosphere Data Set
     (COADS) for the 1980s.  These data consist of logbook and radio reports.
     The satellite data were produced at the University of Miami's Rosenteil
     School of Marine and Atmospheric Sciences from analyses of satellite
     retrievals obtained from AVHRR. COADS data procedures are described in:

     Slutz, R. J., S. J. Lubker, J. D. Hiscox, S. D. Woodruff, R. L.
          Jenne, D. H. Joseph, P. M. Steurer, and J. D. Elms, 1985:
          COADS: Comprehensive Ocean-Atmosphere Data Set. Release 1,
          262 pp. [Available from Climate Research Program,
          Environmental Research Laboratories, 325 Broadway, Boulder,
          CO 80303.]

     6.2.1  Spatial Coverage.

            The coverage is global.  Data in each file are ordered from North 
            to South and from West to East beginning at 180 degrees West and 
            90 degrees North.  Point (1,1) represents the grid cell centered 
            at 89.5 N and 179.5 W (see section 8.4).

     6.2.2  Spatial Resolution.

            The data are given in an equal-angle lat/long grid that has a 
            spatial resolution of 1 X 1 degree lat/long.

6.3  Temporal Characteristics.

     6.3.1  Temporal Coverage.

            January 1987 through December 1988.

     6.3.2  Temporal Resolution.

            Monthly mean.

                           7.  OBSERVATIONS

7.1  Field Notes.

     Not applicable.

                           8.  DATA DESCRIPTION

8.1  Table Definition With Comments.

     Not applicable.

8.2  Type of Data.

|                 8.2.1                  |               |          |          |
|Parameter/Variable Name                 |               |          |          |
|    |               8.2.2               |     8.2.3     |  8.2.4   |  8.2.5   |
|    |Parameter/Variable Description     |Range          |Units     |Source    |
|NMC_SST                                 |               |          |          |
|    |NMC sea surface temperature in     |min = 271.4,   | [K]      |NMC       |
|    |degrees Kelvin.                    |max = 308.2    |          |analysis  |
|    |                                   |               |          |          |

8.3  Sample Data Base Data Record.

     Not applicable.

8.4  Data Format.

     The CD-ROM file format is ASCII, and consists of numerical fields of 
     varying length, which are space delimited and arranged in columns and 
     rows.  Each column contains 180 numerical values and each row contain 360 
     numerical values.  

          Grid arrangement

             I  = 1 IS CENTERED AT 179.5W
             J  = 1 IS CENTERED AT 89.5N

             90N - | - - - | - - - | - - - | - -
                   | (1,1) | (2,1) | (3,1) |
             89N - | - - - | - - - | - - - | - -
                   | (1,2) | (2,2) | (3,2) |
             88N - | - - - | - - - | - - - | - -
                   | (1,3) | (2,3) | (3,3) |
             87N - | - - - | - - - | - - - |
                  180W   179W    178W   177W


8.5  Related Data Sets.

     Not available.

                         9.  DATA MANIPULATIONS

9.1  Formulas.

     9.1.1  Derivation Techniques/Algorithms.

            The analysis technique consists of preliminary elimination of SST
            data with bad position or bad SST values.  All observations are
            then averaged over onto a 1-degree weekly grid. These "super
            observations" are then used in the analysis.  The analysis
            consists of two steps.  First, the satellite super observations
            are corrected for any large scale (1000 km) biases relative to
            the in situ super observations. Finally, the in situ and corrected
            satellite super observations are processed using optimum
            interpolation to produce an analyzed SST field. A complete
            description of all the data processing and analysis techniques
            may be found in:

            Reynolds, R. W. and T. M. Smith, 1994. Improved global sea surface
               temperature analyses. J. Climate, 7:929-948.

9.2  Data Processing Sequence.

     9.2.1  Processing Steps and Data Sets.

            See reference in 9.1

     9.2.2  Processing Changes.

            Not available at this revision.

9.3  Calculations.

     9.3.1  Special Corrections/Adjustments.

            The NASA Goddard DAAC applied the inverse of the ISLSCP Initiative 
            1 land/sea mask to the SST data. Land values are 0. 

            The Goddard DAAC converted data values from centigrade to Kelvin.

9.4  Graphs and Plots.

     Not available at this revision.

                          10.  ERRORS

10.1  Sources of Error.

      Errors in the final SST product are caused by errors in the
      data and errors in the analysis method.  Reynolds and Smith
      (1994) determined that the rms errors from different types of
      data were: ship, 1.5C; buoy, 0.8C; day satellite, 0.8C; and night
      satellite, 0.5C.  

      To determine the analysis error, the SSTs from the OI were
      compared with SSTs from three equatorial moored buoys located at
      110W, 140W and 165E.  The SST data from these buoys were not used
      in the analysis. The monthly difference between buoys and the
      analysis were computed for the period 1982-93.  The rms
      errors were: 0.38C at 110W, 0.39C at 140W and 0.24C at 165E. The
      bias errors (buoy - analysis) were -0.21C at 110W; -0.26C at 140W
      and -0.05C at 165E.  The errors are larger in the eastern Pacific
      because of the gradients and variability are larger than in the
      west.  Analysis rms errors less that 0.4C can be expected over
      much of globe except in regions of the western boundary currents
      (e.g., the Gulf Stream) where the rms errors can be 2 to 3 times

10.2  Quality Assessment.

      10.2.1  Data Validation by Source.

              Not available at this revision.

      10.2.2  Confidence Level/Accuracy Judgment.

              Not available at this revision.

      10.2.3  Measurement Error for Parameters and Variables.

              Not available at this revision.

      10.2.4  Additional Quality Assessment Applied.

              Not available at this revision.

                          11.  NOTES

11.1  Known Problems With The Data.

      Not available at this revision.

11.2  Usage Guidance.

      Not available at this revision.

11.3  Other Relevant Information.

      Not available at this revision.

                          12.  REFERENCES

12.1  Satellite/Instrument/Data Processing Documentation.

      Not available at this revision.

12.2  Journal Articles and Study Reports.

      Reynolds, R. W., 1988.  A real-time global sea surface temperature
          analysis.  J. Climate, 1:75-86.
      Reynolds, R.W., 1993. Impact of Mount Pinatubo Aerosols on
          Satellite-Derived Sea Surface Temperatures.  Journal of
          Climate, 6:768-774.
      Reynolds, R. W., C. K. Folland and D. E. Parker, 1989.  Biases in
          satellite derived sea-surface-temperatures, Nature, 341:728-731.
      Reynolds, R. W. and D. C. Marsico, 1993.  An improved real-time global
          sea surface temperature analysis.  J. Climate, 6:114-119.
      Reynolds, R. W. and T. M. Smith, 1994: Improved global sea surface
          temperature analyses. J. Climate, 7:929-948.

12.3  Archive/DBMS Usage Documentation.

      Contact the EOS Distributed Active Archive Center (DAAC) at NASA Goddard
      Space Flight Center (GSFC), Greenbelt Maryland (see Section 13 below).
      Documentation about using the archive or information about access to the
      on-line information system is available through the GSFC DAAC User
      Services Office.

                             13.  DATA ACCESS

13.1  Contacts for Archive/Data Access Information.

      GSFC DAAC User Services
      NASA/Goddard Space Flight Center
      Code 902.2
      Greenbelt, MD 20771

      Phone:     (301) 286-3209
      Fax:       (301) 286-1775
      Internet:  daacuso@eosdata.gsfc.nasa.gov

13.2  Archive Identification.

      Goddard Distributed Active Archive Center
      NASA Goddard Space Flight Center
      Code 902.2
      Greenbelt, MD 20771

      Telephone:  (301) 286-3209
      FAX:        (301) 286-1775
      Internet:   daacuso@eosdata.gsfc.nasa.gov

13.3  Procedures for Obtaining Data.

      Users may place requests by accessing the on-line system, by sending 
      letters, electronic mail, FAX, telephone, or personal visit.

      Accessing the GSFC DAAC Online System:

      The GSFC DAAC Information Management System (IMS) allows users to 
      ordering data sets stored on-line.  The system is open to the public.

      Access Instructions:

      Node name:  daac.gsfc.nasa.gov
      Node number:
      Login example: telnet daac.gsfc.nasa.gov
      Username:  daacims
      password:  gsfcdaac

      You will be asked to register your name and address during your first

      Ordering CD-ROMs:

      To order CD-ROMs (available through the Goddard DAAC) users should 
      contact the Goddard DAAC User Support Office (see section 13.2).

13.4  GSFC DAAC Status/Plans.

      The ISLSCP Initiative I CD-ROM is available from the Goddard DAAC.


14.1  Tape Products.

      Gridded data is available from NMC.

14.2  Film Products.

      Not available at this revision.

14.3  Other Products.

      Not available at this revision.

                       15.  GLOSSARY OF ACRONYMS

AVHRR               Advanced Very High Resolution Radiometer
CD-ROM              Compact Disk (optical), Read Only Memory
DAAC                Destributed Active Archive Center
EOS                 Earth Observation System
GSFC                Global Change Data Center
NMC                 National Meteorological Center
OI                  optimum interpolation
SST                 sea surface temperature
COADS               Comprehensive Ocean Atmosphere Data Set