Skip to main content
Dataset Overview | National Centers for Environmental Information (NCEI)

4 km NODC/RSMAS AVHRR Pathfinder v5.0 7-day Data for 1987 (NCEI Accession 0001782)

browse graphicPreview graphic
The 4 km Pathfinder effort at the National Oceanic and Atmospheric Administration (NOAA) National Oceanographic Data Center (NODC) and the University of Miami's Rosenstiel School of Marine and Atmospheric Science (RSMAS) is an extension of and improvement on the sea surface temperature (SST) fields from the NOAA/NASA AVHRR Oceans 9km Pathfinder dataset. In this 4 km Pathfinder project, some important shortcomings in the original 9 km data have been corrected, and the entire time series has been reprocessed at the 4 km Global Area Coverage (GAC) level, the highest resolution possible globally.

Twice-daily SST and related parameters back to late 1981 have been produced, as well as temporal averages for 5-day, 7-day, 8-day, monthly, and yearly periods.

This metadata record describes the temporally averaged 7-day SST data and related parameters available for 1987. Data for all other years and time periods are available as separate NCEI accessions. The purpose of the NODC Pathfinder data is to provide sea surface temperature data and related parameters with good temporal consistency, high accuracy and spatial resolution, and for archive and distribution through the NOAA National Oceanographic Data Center (NODC). This SST dataset is intended primarily for climate related applications and studies and is being established to help form the basis for a Climate Data Record for SST.
  • Cite as: Casey, Kenneth S.; US National Oceanographic Data Center (2004). 4 km NODC/RSMAS AVHRR Pathfinder v5.0 7-day Data for 1987 (NCEI Accession 0001782). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0001782. Accessed [date].
gov.noaa.nodc:0001782
Download Data
  • HTTPS (download)
    Navigate directly to the URL for data access and direct download.
  • FTP (download)
    These data are available through the File Transfer Protocol (FTP). FTP is no longer supported by most internet browsers. You may copy and paste the FTP link to the data into an FTP client (e.g., FileZilla or WinSCP).
Distribution Formats
  • Originator data format
Ordering Instructions Contact NCEI for other distribution options and instructions.
Distributor NOAA National Centers for Environmental Information
+1-301-713-3277
NCEI.Info@noaa.gov
Dataset Point of Contact NOAA National Centers for Environmental Information
ncei.info@noaa.gov
Time Period 1987-01-01 to 1987-12-31
Spatial Bounding Box Coordinates
West: -180
East: 180
South: -90
North: 90
Spatial Coverage Map
General Documentation
Associated Resources
  • AVHRR Pathfinder version 5.0, interim version 5.0, and version 5.1 global 4km sea surface temperature (SST) data for 1981-2009
    • NCEI Collection
      Navigate directly to the URL for data access and direct download.
  • Parent ID (indicates this dataset is related to other data):
    • gov.noaa.nodc:AVHRR_Pathfinder-NODC-v5.0_v5.1
Publication Dates
  • publication: 2004-10-20
  • revision: 2022-01-04
Data Presentation Form Digital table - digital representation of facts or figures systematically displayed, especially in columns
Dataset Progress Status Complete - production of the data has been completed
Historical archive - data has been stored in an offline storage facility
Data Update Frequency As needed
Supplemental Information
The Version 5.0 Pathfinder algorithm was used to produce these twice-daily, 5-day, 7-day, 8-day, monthly, and yearly global SST and related parameters (described below). This algorithm is an improved version of the previously most successful of many methods used to derive SST from AVHRR observations (see Barton (1995) for a review of earlier techniques), the University of Miami Pathfinder version v4.2 SST algorithm (described fully in Kilpatrick et al., 2001).

The v4.2 algorithm offered marked improvement over operational retrieval algorithms such as MCSST and was applied to AVHRR data to maximize accuracy and to minimize artificial fluctuations arising from the sequence of AVHRR instruments flown on NOAA's polar-orbiting satellites during the past 2 decades. The 9 km v4.2 Pathfinder SSTs have already been shown to be the highest quality product currently available for the construction of global climatologies (Casey and Cornillon, 1999) and longer-term SST trend determination (Casey and Cornillon, 2001), and have been demonstrated to be accurate within about 0.3 degrees C under optimal conditions (Kearns et al., 2000). Relative to the older 9 km v4.2 Pathfinder data, the new, ~ 4 km resolution Pathfinder Version 5.0 global SSTs increase detail roughly by a factor of four simply by virtue of the increased resolution. The increase in detail over widely used but relatively coarse SST datasets such as Optimally Interpolated SST Version 2 (OISSTv2; Reynolds et al., 2002) and the Hadley Centre's Global Sea Ice and SST (HadISST1; Rayner et al., 2003) is far greater.

In addition to the increased resolution, significant improvements have been made in the Version 5.0 which enhance the usefulness of the SST fields. Currently, these enhancements include the use of sea ice in the quality level determination scheme, inclusion of many inland water bodies, and the use of a greatly improved land mask. The greatest improvements are seen in coastal zones, marginal seas, and boundary current regions where SST gradients are often large and their impact on operational or research products is greatest. Separate SST products for daytime and nighttime AVHRR retrievals are made to better understand the differences in skin and bulk temperatures, since mean differences between AVHRR-measured skin temperatures and bulk temperatures of 0.1 to 0.2 degrees C (Schluessel et al., 1990) and locally varying differences of up to 1.8 degrees C (Minnett et al., 2000) have been observed.

In addition to SST values, the Pathfinder V5.0 Project makes six other parameters available, for a total of seven per time step:
1. All-pixel SST - The all-pixel SST files contain values for each pixel location, including those contaminated with clouds or other sources of error. The Overall Quality Flag values may be used to filter out these unwanted values. The SST value in each pixel location is an average of the highest quality AVHRR Global Area Coverage (GAC) observations available in each roughly 4 km bin.
2. First-guess SST - The Pathfinder algorithm uses a first guess SST provided by the Reynolds Optimally Interpolated SST Version 2 (OISSTv2) product. The OISSTv2 is also used in the quality control procedures.
3. Number of observations - This parameter indicates the number of AVHRR GAC observations falling in each approximately 4 km bin.
4. Standard deviation - This is the standard deviation of the observations in each 4 km bin.
5. Overall quality flag - The overall quality flag is a relative assignment of SST quality based on a hierarchical suite of tests. The Quality Flag varies from 0 to 7, with 0 being the lowest quality and 7 the highest. For more information regarding the suite of tests, see the Kilpatrick et al. (2001) paper cited above.
6. Mask 1 - These files contain a mask code, which along with Mask 2, can be used to determine the tests in the hierarchical suite that were passed or failed, resulting in the Overall Quality Flag.
7. Mask 2 - These files contain a mask code, which along with Mask 1, can be used to determine the tests in the hierarchical suite that were passed or failed, resulting in the Overall Quality Flag.

This dataset also includes a collection of value-added, cloud-screened products in HDF4. These products contain daytime, nighttime, and day-night averaged data of quality flags 4-7 only, as well as standard deviation and pixel count information. They have been produced from the original Pathfinder Version 5 data by NODC for Daily, 5-day, 7-day, and monthly temporal averages at 4km and one degree spatial resolution, as well as five degree spatial resolution for monthly products.

Note on Pathfinder Program: The Pathfinder program was jointly created by NASA and NOAA through the Earth Observing System (EOS) Program Office in 1990. The focus of the Pathfinder Program was to determine how existing satellite based datasets could be processed and used to study global change. The datasets were designed to be long time-series data processed with stable calibration and community consensus algorithms to better assist the research community. For more information, see: National Aeronautics and Space Administration (NASA). 1993. Earth Observing System (EOS) Reference Handbook, ed. G. Asrar and D. J. Dokken. Washington, D. C.: National Aeronautics and Space Administration, Earth Science Support Office, Document Resource Facility. The 4 km Pathfinder Project effort at the National Oceanic and Atmospheric Administration (NOAA) National Oceanographic Data Center (NODC) and the University of Miami's Rosenstiel School of Marine and Atmospheric Science (RSMAS) is an extension of and improvement on the sea surface temperature (SST) fields from that original NOAA/NASA AVHRR Oceans Pathfinder program.

In this accession, NCEI has archived multiple versions of these data. The latest (and best) version of these data has the largest version number.
Purpose This dataset is available to the public for a wide variety of uses including scientific research and analysis.
Use Limitations
  • accessLevel: Public
  • Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives.
Dataset Citation
  • Cite as: Casey, Kenneth S.; US National Oceanographic Data Center (2004). 4 km NODC/RSMAS AVHRR Pathfinder v5.0 7-day Data for 1987 (NCEI Accession 0001782). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0001782. Accessed [date].
Cited Authors
Contributors
Resource Providers
Publishers
Theme keywords NODC DATA TYPES THESAURUS NODC OBSERVATION TYPES THESAURUS WMO_CategoryCode
  • oceanography
Global Change Master Directory (GCMD) Science Keywords
Data Center keywords NODC COLLECTING INSTITUTION NAMES THESAURUS NODC SUBMITTING INSTITUTION NAMES THESAURUS Global Change Master Directory (GCMD) Data Center Keywords
Platform keywords NODC PLATFORM NAMES THESAURUS Global Change Master Directory (GCMD) Platform Keywords ICES/SeaDataNet Ship Codes
Instrument keywords NODC INSTRUMENT TYPES THESAURUS Global Change Master Directory (GCMD) Instrument Keywords
Place keywords NODC SEA AREA NAMES THESAURUS Global Change Master Directory (GCMD) Location Keywords
Project keywords NODC PROJECT NAMES THESAURUS Global Change Master Directory (GCMD) Project Keywords
Keywords NCEI ACCESSION NUMBER
Use Constraints
  • Cite as: Casey, Kenneth S.; US National Oceanographic Data Center (2004). 4 km NODC/RSMAS AVHRR Pathfinder v5.0 7-day Data for 1987 (NCEI Accession 0001782). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0001782. Accessed [date].
Access Constraints
  • Use liability: NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose.
Fees
  • In most cases, electronic downloads of the data are free. However, fees may apply for custom orders, data certifications, copies of analog materials, and data distribution on physical media.
Lineage information for: dataset
Processing Steps
  • 2004-10-20T01:55:53Z - NCEI Accession 0001782 v1.1 was published.
  • 2004-10-20T01:55:53Z - NCEI Accession 0001782 was revised and v2.2 was published.
    Rationale: Updates were received for this dataset. These updates were copied into the data/0-data/ directory of this accession. These updates may provide additional files or replace obsolete files. This version contains the most complete and up-to-date representation of this archival information package. All of the files received prior to this update are available in the preceding version of this accession.
  • 2022-01-04T01:34:00Z - NCEI Accession 0001782 was revised and v2.3 was published.
    Rationale: Additional metadata files were received or created for this dataset. These updates were copied into the about/ directory of this accession. These updates may provide additional files or replace obsolete files. This version contains the most complete and up-to-date representation of this archival information package. All of the files received prior to this update are available in the preceding version of this accession.
Output Datasets
Lineage information for: repository
Processing Steps
  • 2015-04-22T00:00:00 - NOAA created the National Centers for Environmental Information (NCEI) by merging NOAA's National Climatic Data Center (NCDC), National Geophysical Data Center (NGDC), and National Oceanographic Data Center (NODC), including the National Coastal Data Development Center (NCDDC), per the Consolidated and Further Continuing Appropriations Act, 2015, Public Law 113-235. NCEI launched publicly on April 22, 2015.
Acquisition Information (collection)
Instrument
  • AVHRR-2
  • AVHRR-3
Platform
  • NOAA-11
  • NOAA-14
  • NOAA-16
  • NOAA-9
Last Modified: 2023-09-06T19:18:23Z
For questions about the information on this page, please email: ncei.info@noaa.gov