3.4 SAR/VIIRS Datasets

The SAR and VIIRS datasets are newer data products for GFW. There is one SAR table within the gfw_research dataset. The main VIIRS table is in a separate dataset pipe_viirs_production_vYYYYMMDD and a table to match VIIRS data to AIS data is found in the gfw_research dataset. More information on the SAR data is available on the GFW SAR Wiki page and more information on VIIRS data, including an example of how to match VIIRS to AIS, is included in the GFW VIIRS Wiki page. The following are the relevant tables for SAR and VIIRS data:

  • gfw_research.sar_ds3_fmean250_e10_d70_s20_8xmean_ns
    • Main table for SAR detections
    • Important fields: ssvid, lat, lon, detection_time
    • Relationship to other tables: There aren’t currently any examples for relating SAR detections to AIS. The GFW Wiki page will be updated in the future to include examples of matching SAR and AIS data.
    • Assumptions: Detections are based on a random forest model trained on distance from shore, distance from port, bathymetry, slope, and the density of fishing vessels
    • This is a partitioned table. See Section 4.2.4 for more information about subsetting data in partitioned tables
  • pipe_viirs_production_vYYYYMMDD.raw_vbd_global
    • The global VBD (VIIRS boat detections) datset
    • Important fields: id_Key, lat_DNB, lon_DNB, Date_Mscan, QF_detect
    • Relationship to other tables: the Date_Mscan, lat_DNB, and lon_DNB, can be combined to form the detect_id which is a unqiue identifier for each VIIRS detection found in the viirs_matched_vYYYYMMDD table
    • Assumptions: Detections are based on a random forest model trained on distance from shore, distance from port, bathymetry, slope, and the density of fishing vessels
    • This is a partitioned table. See Section 4.2.4 for more information about subsetting data in partitioned tables
  • gfw_research.viirs_matched_vYYYYMMDD
    • Table of VIIRS detections matched with AIS data
    • Important fields: detect_id, detect_lat, detect_lon, detect_timestamp, QF_detect (quality flag field), ssvid
    • Relationship to other tables: use the detect_id to match to the raw VIIRS data in pipe_viirs_production_vYYYYMMDD.raw_vbd_global, the ssvid can be used to relate the detections to other vessel characteristics
    • This is a partitioned table. See Section 4.2.4 for more information about subsetting data in partitioned tables