GHRSST NOAA/STAR Metop-C AVHRR FRAC ACSPO v2.80 0.02 L3U Dataset (GDS v2)
Short NameAVHRRF_MC-STAR-L3U-v2.80
DescriptionThe ACSPO Metop-A AVHRR FRAC L3U (Level 3 Uncollated) product is a gridded (equal-grid 0.02-deg projection, approximately equivalent to 2km global resolution, fully consistent across all ACSPO products; Ignatov et al, 2017) version of the ACSPO MetOp-A FRAC L2P product available at The L3U files are 10min granules in NetCDF4 format, compliant with the GHRSST Data Specification version 2 (GDS2). There are 144 granules per 24hr interval, with a total data volume of 0.45GB/day. Fill values are reported in all invalid pixels, including pixels with >5 km inland. For each valid water pixel (defined as ocean, sea, lake or river, and up to 5 km inland), the following layers are reported: SSTs, ACSPO clear-sky mask (ACSM; provided in each grid as part of l2p_flags, which also includes day/night, land, ice, twilight, and glint flags), wind speed, and ACSPO minus reference CMC L4 SST. Only L2P SSTs with QL=5 were gridded, so all valid SSTs are recommended for the users. Per GDS2 specifications, two additional Sensor-Specific Error Statistics layers (SSES bias and standard deviation) are reported in each pixel with valid SST. The ACSPO Metop-A AVHRR FRAC L3U product is monitored and validated against iQuam in situ data (Xu and Ignatov, 2014) in SQUAM (Dash et al, 2010). SST imagery and clear-sky mask are evaluated in the NOAA ACSPO Regional Monitor for SST (ARMS) system, and checked for consistency with L2P and other satellites/sensors SST products. More information about the dataset is found at AVHRRF_MA-STAR-L2P-v2.80 and in (Pryamitsyn et al., 2021).The ACSPO AVHRR FRAC L3U product is monitored and validated against quality controlled in situ data, provided by the NOAA in situ SST Quality Monitor system (iQuam; Xu and Ignatov, 2014), in another NOAA system, SST Quality Monitor (SQUAM; Dash et al, 2010). SST imagery and clear-sky masking are continuously evaluated, and checked for consistency with other sensors and platforms, in the ACSPO Regional Monitor for SST (ARMS) system. The full size (2.6GB/day) ACSPO L2P product, in original swath projection (1.1km/nadir to 6km/swath edge), also organized in 144 10-min granules/day, is available at
Dataset TypeACTIVE
Processing Level3U
CoverageRegion: GLOBAL
North Bounding Coordinate: 90 degrees
South Bounding Coordinate: -90 degrees
West Bounding Coordinate: -180 degrees
East Bounding Coordinate: 180 degrees
Time Span: 2018-Dec-04 to Present
Granule Time Span: 2021-Jan-12 to 2021-Apr-07
ResolutionSpatial Resolution: 0.02 degrees (Latitude) x 0.02 degrees (Longitude)
ProjectionProjection Type: Cylindrical Lat-Lon
Projection Detail: Geolocation information included for each pixel
Ellipsoid: WGS 84
Name: Meteorological Operational Satellite - C (METOP-C)
Orbit Period: 101.3 minutes
Inclination Angle: 98.7 degrees
Name: Advanced Very High Resolution Radiometer-3 (AVHRR-3)
Swath Width: 2400.0 kilometers
Description: Spacecraft angular distance from orbital plane relative to the Equator.

ProjectGroup for High Resolution Sea Surface Temperature (GHRSST)
Data ProviderPublisher: The GHRSST Project Office
Creator: NOAA/STAR
Release Place: Camp Springs, MD (USA)
Release Date: 2021-Apr-05

Keyword(s)GHRSST, sea surface temperature, AVHRR, SST, STAR, MetOp, v2.80
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  • In publication
    Historical and Near-real Time SST retrievals from Metop AVHRR FRAC with the Advanced Clear-Sky Processor for Ocean. Proc. SPIE, 2021
Citation NOAA/STAR. 2021. GHRSST L3U Metop-C AVHRR FRAC ACSPO v2.80 0.02-deg Dataset. Ver. 2.80. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at

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