The Sea-surface Temperature (SST) Database
This database consists of satellite measurements of (nominally) weekly-averaged surface temperature for the Northwest Atlantic. The data are obtained from the Physical Oceanography Archive Centre of the Jet Propulsion Laboratory (JPL).
There are four JPL products maintained in the database.
- Pathfinder 5 SST 4 km. seven day average composite from 1985 to 2012. This product is under review by the provider and may also be discontinued. The data are based on the 4 km. seven day ascending "all SST" which includes quality flags. Data are filtered to include only quality 4-7. The coverage area is from 35°N-80°N and 35°W-100°W. For a description of the data refer to http://www.nodc.noaa.gov/sog/pathfinder4km/.
- Pathfinder SST 4.1 and 4.1i 9 km. eight day average composite. V4.1 is available from 1985 to 1999 and version Interim V4.1 from 2000 to June 2003 when the product was terminated. The Interim 4.1 uses the same algorithm but the coefficients are based on the previous year. In both cases, data are based on the 9 km., eight day ascending "all SST" version (which includes quality flag and number in average) filtered to include only data quality flags 4-7. Quality flags are included when requesting the source data. Coverage area is from 35°N-67°N and 35°W-77°W. For a complete description of the data, refer to http://podaac.jpl.nasa.gov/sst/sst_data.html.
- MCSST 18 km. seven day average composite from 1981 - 2000. This product was discontinued in February 2001. Coverage area is the same as Pathfinder 4. For a complete description of the data refer to http://podaac-www.jpl.nasa.gov/.
We have not conducted a formal inter-comparison of The Pathfinder and Multi-Channel Sea Surface Temperature (MCSST) products for the overlapping years of 1985-2000. Pathfinder has a much higher rate of data recovery (at least a factor of 2), particularly in northern latitudes. The actual number of observations are about 8x that of MCSST. A four-fold increase is due to the higher spatial resolution.
There is also a difference in the time reference.
- MCSST is a seven day composite with time referenced to the mid-point of the series. The averaging period started in November 1981 and continued in seven day increments until the product stopped in Dec. 2000.
- Pathfinder 4 is an eight day composite with time referenced to the beginning of the series and continues for 46 time steps to the end of the year. The last time period is a five day (or six if a leap year composite. The series start on January 1 of each year.
- Pathfinder 5 is much like MCSST. It is a seven day composite with time referenced to the beginning of the series and continues for 52 time steps to the end of the year. The last time period in a year may go into the next year.
Users should be careful in combining the MCSST, Pathfinder4 and Pathfinder 5 data sources because of the algorithm and time differences. Pathfinder 5 appears to have a much greater incidence of very low (-3 deg) temperatures.
The Pathfinder and MCSST data are provided at no charge by :
User Services Office
Physical Oceanography Archive Centre (PO.DAAC)
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109, USA
SST Data Processing
The SST Application
This application extracts information from the Ocean Sciences SST database according to user specified spatial and temporal criteria. Output results can be either statistical summaries of the data or the actual data stored in the database (for input into your own analyses). The query is performed off-line. You will be contacted by email when your results become available. Results should normally be available within a few hours (depending upon the size of your query and the number of requests ahead of you). If you haven't had a reply within 24 hours, contact us and we will try to determine what happened.
A Brief Tour
(A) Query Identification
All of your queries are assigned a unique query number and saved under your username. You can re-run existing queries or edit them and submit them as new queries. You can assign a name under the Title input. This name is saved internally in the results files for your reference.
(B) Area Selection Type
You may define a geographical area in one of three ways;
- Choose from a list of pre-defined polygons (multiple selections are permitted). The pre-defined polygons are shown in areas.html.
- Provide your own polygon definition by latitude/longitude co-ordinates. To do this, select the Define Area button at the top of your screen, follow the instructions to create a new polygon, and then select it from the list of pre-defined polygons.
- Define a rectangle by latitude/longitude coordinates. The blocks parameter permits one to subdivide the entire rectangle into x by y blocks. For example, specifying latitude from 42° to 45° and longitude from -62° to -65° with 1° blocks in both latitude and longitude would result in defining nine separate 1° grid squares for which statistics would be generated.
Note that the convention for longitude is positive East. Latitude and Longitude must be specified as decimal degrees, but we provide a converter if you prefer degrees, minutes, seconds.
(C) Time Specification
Specify a continuous time period from (month/day/year) to (month/day/year) and/or a seasonal window. Months are inclusive. Months 6 to 9 means June to September. Months 12 to 2 would select only December to February. Default is all months for the entire time period for which there are data.
(D) Temperature Filter
Both Pathfinder 4 and Pathfinder 5 contain very low temperatures (~-3 deg. C) even though they have passed the quality tests (quality flag 4 or greater). This option permits the user to set a range of acceptable values. Any value outside this range is excluded from any further computations.
(E) Data Source
There are four data sources currently supported and described at the beginning of this page under the section SST Database. To see the list of data sources, click inside the pick list box. A data source selection box will appear and sources can be selected or de-selected with a double-click.
(F) Quality Flag
Pathfinder 4 and 5 include quality flags (0 lowest, 7 highest quality). Only data with quality 4 or greater are included in SST. Users may further restrict this by selecting their own range of quality flags.
(G) Result Information Set
The result set files returned to you depend upon what options you request; The standard deviation is calculated using the "nonbiased" or "n-1" method using the following formula:
Seasonal Cycle, Time Series Will get both the Times series of monthly statistics (average, minimum, maximum and count of observations for each year and month and depth level for which there are data) and Seasonal Cycle (average, minimum. maximum, standard deviation, count of observations and count of months in average). The values are determined by an un-weighted average over all months from the time series statistics.
Complete Profile Data extracts every value of temperature referenced to latitude, longitude and date. These files can be very large. Many people request it simply because they can. Make sure it is what you really require before requesting it. There are also some file size restrictions. See Caveats.
The complete result set can consist of up to four ascii text files. All files are of the form qry_xx.txt, where xx is your unique query identifier. Files are comma delimited with a header label for easy import into a spreadsheet or database application. (see detailed file description)
After the query specification is complete, clicking Run button will submit the query.
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