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Journal for accession number: 0073581
Created on:                    2011-06-13 21:17:37 UTC
By:                            Tess Brandon,OC1,SSMC3 4716,7133267 x181

Source: AVHRR Pathfinder Version 5.2 Sea Surface Temperature for 1986

The AVHRR Pathfinder Version 5.2 Sea Surface Temperature data set (PFV52) is a 
collection of global, twice-daily 4km sea surface temperature data produced in 
a partnership by the NOAA National Oceanographic Data Center and the University 
of Miami's Rosenstiel School of Marine and Atmospheric Science (RSMAS). RSMAS 
acquires Level 1b AVHRR Global Area Coverage (GAC) data and processes it to 
globally gridded Level 3 data files in HDF4 using code based on the SeaDAS v6.1 
processing environment. NODC acquires these files from RSMAS and converts them 
to netCDF4 files compliant with the Group for High Resolution Sea Surface 
Temperature (GHRSST) Data Specification Version 2.0 (GDS2.0). Final PFv52 data 
are quality assured through browse image generation and inspection. Upon 
completion of the quality assurance routines, the data are archived in separate 
yearly accessions beginning with 1981 and published online by NODC.

Complete ISO metadata for the entire PFV52 collection is available at:
http://pathfinder.nodc.noaa.gov/ISO-AVHRR_Pathfinder-NODC-L3C-v5.2.html

Files in this accession include PFV52 browse images and data files for 1986:

about/
  journal.txt - this file
  browse_images/ - this directory contains browse images in .jpg format for all 
  parameters* in PFV52 data files, as well as cloud-screened SST, for 1986. 
  Browse images are organized into the following directories:
    1986/
      sea_surface_temperature/
      dt_analysis/
      wind_speed/
      sea_ice_fraction/
      aerosol_dynamic_indicator/
      quality_level/
      pathfinder_quality_level/
      l2p_flags/
      declouded_sst/

*Note sst_dtime, sses_bias and sses_standard_deviation are not included, as these 
variables are empty for PFV52.

data/
  0-data/
    1986/ - this directory contains PFV52 data files in netCDF4 for 1986. 

These data follow the GDS2.0 file naming convention, detailed in the Section 7 of the GDS2.0 document 
(https://www.ghrsst.org/files/download.php?m=documents&f=GDS2.0_TechnicalSpecifications_v2.0.pdf)
and summarized here:

<Indicative Date><Indicative Time>-<RDAC>-<Processing Level>_GHRSST-<SST Type>-<Character String>-<Additional Segregator>-v<GDS Version>-fv<File Version>.<File Type>

Many code lists and details are associated with this convention. Note carefully that dashes ("-") 
separate parts of the file name, while underscores ("_") are used within the parts of the file name. 
For Pathfinder Version 5.2 data:

    * Indicative date and time are, by GDS2 definition, for the central time of the collation window and use YYYYMMDD and HHMMSS format
    * Processing level = "L3C" for Level 3 Collated
    * SST Type = "SSTskin"
    * Character String = "AVHRR_Pathfinder"
    * Additional Segregator = PFV5.2_NOAAXX_G_YYYYDDD_DAYNIGHTCODE 

where:

    * XX = two-digit NOAA POES satellite identifier from 07, 09, 11, 14, 16, 17, 18
    * YYYYDDD = four digit year and three-digit day of year. Note that for some Pathfinder Version 5.2 files, 
                this YYYYDDD can be shifted by a day compared to the "Indicative Date and Time, which is 
                defined in the GDS2.0 for L3C files as the central time of the collation window. Sometimes 
                this falls just over midnight, and can result in a given day having apparently two files and 
                the next day none. This YYYYDDD is comparable to the date used in Pathfinder Version 5.0 and 
                Pathfinder Version 5.1.
    * DAYNIGHTCODE = "day" or "night", indicator of whether this collated file represents daytime data or nighttime data.
    * "_G" refers to Global Area Coverage (GAC) data. If Pathfinder eventually includes Local Area Coverage (LAC) data 
      this could be "_L", or perhaps even "_H" if the source is High Resolution Picture Transmission (HRPT) data. 

Thus, the convention for Pathfinder Version 5.2 is:

YYYYMMDDHHMMSS-NODC-L3C_GHRSST-SSTskin-AVHRR_Pathfinder-PFV5.2_NOAAXX_G_YYYYDDD_DAYNIGHTCODE-v2.0-fv01.0.nc

noting that the YYYYMMDD and YYYYDDD might not exactly match, but could be different by one day.

An example:

    * 20090105002150-NODC-L3C_GHRSST-SSTskin-AVHRR_Pathfinder-PFV5.2_NOAA18_G_2009005_night-v02.0-fv01.0.nc