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Modern Average Global Sea-Surface Temperature

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Frequently anticipated questions:


What does this data set describe?

Title: Modern Average Global Sea-Surface Temperature
Abstract:
The data contained in this data set are derived from the NOAA Advanced Very High Resolution Radiometer Multichannel Sea Surface Temperature data (AVHRR MCSST), which are obtainable from the Distributed Active Archive Center at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. The JPL tapes contain weekly images of SST from October 1981 through December 1990 in nine regions of the world ocean: North Atlantic, Eastern North Atlantic, South Atlantic, Agulhas, Indian, Southeast Pacific, Southwest Pacific, Northeast Pacific, and Northwest Pacific.
This data set represents the results of calculations carried out on the NOAA data and also contains the source code of the programs that made the calculations. The objective was to derive the average sea-surface temperature of each month and week throughout the whole 10-year series, meaning, for example, that data from January of each year would be averaged together. The result is 12 monthly and 52 weekly images for each of the oceanic regions. Averaging the images in this way tends to reduce the number of grid cells that lack valid data and to suppress interannual variability.
Supplemental_Information:
As ancillary data, the ETOPO5 global gridded elevation and bathymetry data (Edwards, 1989) were interpolated to the resolution of the SST data; the interpolated topographic data are included.
  1. How should this data set be cited?

    Schweitzer, Peter N., 1993, Modern Average Global Sea-Surface Temperature: U.S. Geological Survey Digital Data Series DDS-10, U.S. Geological Survey, Reston, Virginia.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -180.0
    East_Bounding_Coordinate: 180.0
    North_Bounding_Coordinate: 72.0
    South_Bounding_Coordinate: -66.0

  3. What does it look like?

    http://geo-nsdi.er.usgs.gov/metadata/digital-data/10/legend.gif (GIF)
    Graphical legend relating colors on the images to sea-surface temperature
    http://geo-nsdi.er.usgs.gov/metadata/digital-data/10/m_augna.gif (GIF)
    August sea-surface temperature in the Western North Atlantic Ocean.
    http://geo-nsdi.er.usgs.gov/metadata/digital-data/10/m_augnae.gif (GIF)
    August sea-surface temperature in the Eastern North Atlantic Ocean.
    http://geo-nsdi.er.usgs.gov/metadata/digital-data/10/m_augsa.gif (GIF)
    August sea-surface temperature in the South Atlantic Ocean.
    http://geo-nsdi.er.usgs.gov/metadata/digital-data/10/m_augag.gif (GIF)
    August sea-surface temperature in the Southeastern Atlantic and Southwestern Indian Oceans.
    http://geo-nsdi.er.usgs.gov/metadata/digital-data/10/m_augio.gif (GIF)
    August sea-surface temperature in the Indian Ocean.
    http://geo-nsdi.er.usgs.gov/metadata/digital-data/10/m_augnep.gif (GIF)
    August sea-surface temperature in the Northeast Pacific Ocean.
    http://geo-nsdi.er.usgs.gov/metadata/digital-data/10/m_augnwp.gif (GIF)
    August sea-surface temperature in the Northwest Pacific Ocean.
    http://geo-nsdi.er.usgs.gov/metadata/digital-data/10/m_augsep.gif (GIF)
    August sea-surface temperature in the Southeast Pacific Ocean.
    http://geo-nsdi.er.usgs.gov/metadata/digital-data/10/m_augswp.gif (GIF)
    August sea-surface temperature in the Southwest Pacific Ocean.

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 01-Oct-1981
    Ending_Date: 31-Dec-1990
    Currentness_Reference:
    Smith, E., 1991, A user's guide to the NOAA Advanced Very High Resolution Radiometer Multichannel Sea Surface Temperature data set produced by the University of Miami/Rosenstiel School of Marine and Atmospheric Science: Distributed by the Distributed Active Archive Center, Jet Propulsion Laboratory, Pasadena, California. 10 p.

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: remote-sensing image

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Raster data set. It contains the following raster data types:

      • Dimensions 512 x 512, type Pixel

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.01757812. Longitudes are given to the nearest 0.01757812. Latitude and longitude values are specified in Decimal degrees.

  7. How does the data set describe geographic features?

    Sea-surface temperature grid cell
    Any of the one-byte data elements in the sea surface temperature files (Source: self-evident)

    Sea-surface temperature grid cell value
    The average temperature, in degrees Celsius, of the ocean surface water in the location indicated by the pixel. (Source: Smith, E., 1991, A user's guide to the NOAA Advanced Very High Resolution Radiometer Multichannel Sea Surface Temperature data set produced by the University of Miami/ Rosenstiel School of Marine and Atmospheric Science: Distributed by the Distributed Active Archive Center, Jet Propulsion Laboratory, Pasadena, California. 10 p.)

    ValueDefinition
    252Missing data
    255Land area

    Range of values
    Minimum:0
    Maximum:250
    Units:Degrees centigrade (calculated from the pixel value by the formula T = -2.1 + 0.2 * p where p is the pixel value.
    Resolution:1

    ETOPO5 grid cell
    Any of the two-byte data elements in the files etopo5.na, etopo5.sa, etopo5.nae, etopo5.ag, etopo5.io, etopo5.nep, etopo5.nwp, etopo5.sep, and etopo5.swp. (Source: self-evident)

    ETOPO5 grid cell value
    Height of the land surface or depth of the sea floor, relative to mean sea level. (Source: NOAA/NGDC. 1992. Integrated Global Elevation and Bathymetry. Digital Data. NOAA/NGDC/WDC-A, Boulder, Colorado. Digital raster data on a 5-minute geographic (lat/long) 2160x4320 grid. In: Global Ecosystems Database Version 1.0: Disc A. Boulder, CO: NOAA National Geophysical Data Center. 1 independent single-attribute spatial layer on CD-ROM. 18.6 MB. [First published in 1989.])

    Range of values
    Minimum:-10783
    Maximum:8000
    Units:meters
    Resolution:1


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    Peter N. Schweitzer
    Mail Stop 954 National Center
    U.S. Geological Survey
    12201 Sunrise Valley Drive
    Reston, VA 20192
    USA

    (703) 648-6533 (voice)
    (703) 648-6252 (FAX)
    pschweitzer@usgs.gov


Why was the data set created?

The purpose of this data set is to provide paleoclimate researchers with a tool for estimating the average seasonal variation in sea-surface temperature (SST) throughout the modern world ocean and for estimating the modern monthly and weekly sea-surface temperature at any given oceanic location. It is expected that these data will be compared with temperature estimates derived from geological proxy measures such as faunal census analyses and stable isotopic analyses. The results can then be used to constrain general circulation models of climate change.


How was the data set created?

  1. From what previous works were the data drawn?

    AVHRR MCSST (source 1 of 1)
    Laboratory, Jet Propulsion, 1991, NOAA Advanced Very High Resolution Radiometer Multichannel Sea Surface Temperature data set produced by the University of Miami/Rosenstiel School of Marine and Atmospheric Science:.

    Other_Citation_Details:
    Distributed by the Distributed Active Archive Center, Jet Propulsion Laboratory, Pasadena, California. User's guide is 10 pages. The data are distributed on 9 nin-track tapes in VAX Backup format.
    Type_of_Source_Media: Nine-track tape
    Source_Contribution:
    The source data set provides 467 weekly images of each of nine regions of the world oceans; these weekly files were averaged in the present data set to produce monthly composite images.

  2. How were the data generated, processed, and modified?

    Date: 1993 (process 1 of 4)
    Calculate monthly averages and composite monthly averages.
    The Bourne shell script do_avgs describes the manner in which the program average was used to calculate the monthly and composite monthly average sea ice concentration files. The program average is given a list of sea ice concentration data files in HDF format. For each grid cell in the images, it calculates the arithmetic average of the corresponding cell in the input files, and writes the average image into a new file. This program is run once for each month of each year represented in the original data to yield monthly averages. Then the composite monthly averages are calculated using the monthly averages for each year.

    Date: 1993 (process 2 of 4)
    Create GIF and PICT images of monthly and composite monthly averages.
    The Bourne shell script do_imgs converts the monthly average and composite monthly average files into GIF and PICT images. This script uses two programs from the freely available PbmPlus toolkit developed by Jeff Poskanzer.

    Date: 1993 (process 3 of 4)
    Regrid ETOPO5 elevation and bathymetry data to fit sea ice concentration grid.
    The ETOPO5 global gridded elevation and bathymetry data set describes world topography on a grid whose cells measure 5 minutes of latitude by 5 minutes of longitude. Since the ice concentration data are given in an azimuthal equidistant projection, the elevation of cells in the ice concentration grid must be determined by appropriately sampling or interpolating the ETOPO5 data. Because the ETOPO5 grid is finer than the ice concentration grid, a sampling algorithm was combined with a spatial averaging scheme to derive the desired elevation data. The program that implements this algorithm is called topo.c; its strategy is to find the ice grid cell coordinates of the center of each ETOPO5 cell, and calculate the average depth of all of the ETOPO5 cells that fall within an ice grid cell. The results are two 16-bit images with big- endian byte ordering in which each signed 16-bit word describes the average depth or elevation in meters (sea level is zero) of a cell in the ice concentration grid.
    Along with the 16-bit depth data files, displayable images are created using depthppm.c in portable pixmap format, and from that intermediate stage, GIF and PICT images are created using the PbmPlus toolkit. Depthppm reduces the complexity of the depth data by assigning one color to a range of depths. The relationship between depth ranges and colors is given in the source code file depthppm.c.
    The Bourne shell script do_topo carries out these operations.

    Date: 10-May-2004 (process 4 of 4)
    Developed a Tcl/Tk script that will display the monthly images of sea-surface temperature (in GIF format) along with a plot of the values. This is a replacement for the graphical browse program previously written in C, which ran only on graphics systems that are now out of date.

  3. What similar or related data should the user be aware of?

    U.S. Geological Survey, and Peter N. Schweitzer (comp.), 1995, Monthly Average Polar Sea-Ice Concentration: U.S. Geological Survey Digital Data Series DDS-27.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    Calculation of sea-surface temperature values from AVHRR data is described extensively in the references and in the user's guides of the source data products.

  2. How accurate are the geographic locations?

    The grid provided in the source data (supplied by PO.DAAC) is described in the user's guide of the source product.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Included in the data set is a table enumerating the days for which sea-surface temperature data were available in the source material. In general, images were available every week during the time period from 811001 through 891231.

  5. How consistent are the relationships among the observations, including topology?

    Included in the data set are the UNIX shell scripts and makefiles that were used to derive the averages and create the tables and images. Source code is provided for all programs written by the author.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: none
Use_Constraints: none

  1. Who distributes the data set? (Distributor 1 of 1)

    Peter N. Schweitzer
    Mail Stop 954 National Center
    U.S. Geological Survey
    12201 Sunrise Valley Drive
    Reston, VA 20192
    USA

    (703) 648-6533 (voice)
    (703) 648-6252 (FAX)
    pschweitzer@usgs.gov

  2. What's the catalog number I need to order this data set?

    U.S. Geological Survey Digital Data Series DDS-10

  3. What legal disclaimers am I supposed to read?

    Although all data and software published on this CD-ROM have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials or the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data, software, or related materials.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 31-Jul-2014
Metadata author:
Peter N. Schweitzer
Mail Stop 954 National Center
U.S. Geological Survey
12201 Sunrise Valley Drive
Reston, VA 20192
USA

(703) 648-6533 (voice)
(703) 648-6252 (FAX)
pschweitzer@usgs.gov

Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


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