Dr. Richard W. Reynolds & Ms. Diane Stokes, National Meteorological Center 5200 Auth Road, Room 807 Camp Springs, MD 20746, USA
_______________________________________________________________________ | 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 averages. 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 buoys). 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 data. 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. 5.2.1.1 Tolerance. 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 ARRAY(I,J) I = 1 IS CENTERED AT 179.5W I INCREASES EASTWARD BY 1 DEGREE J = 1 IS CENTERED AT 89.5N J INCREASES SOUTHWARD BY 1 DEGREE 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 ARRAY(360,180) 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 larger. 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: 192.107.190.139 Login example: telnet daac.gsfc.nasa.gov Username: daacims password: gsfcdaac You will be asked to register your name and address during your first session. 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. OUTPUT PRODUCTS AND AVAILABILITY 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