GHRSST Level 2P OSPO dataset v2.61 from VIIRS on the NOAA-20 satellite (GDS v2)

GHRSST Level 2P OSPO dataset v2.61 from VIIRS on the NOAA-20 satellite (GDS v2)
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Short NameVIIRS_N20-OSPO-L2P-v2.61
DescriptionNOAA-20 (N20/JPSS-1/J1) is the second satellite in the US NOAA latest generation Joint Polar Satellite System (JPSS). N20 was launched on November 18, 2017. In conjunction with the first US satellite in JPSS series, Suomi National Polar-orbiting Partnership (S-NPP) satellite launched on October 28, 2011, N20 form the new NOAA polar constellation. NOAA is responsible for all JPSS products, including SST from the Visible Infrared Imaging Radiometer Suite (VIIRS). VIIRS is a whiskbroom scanning radiometer, which takes measurements in the cross-track direction within a field of view of 112.56-deg using 16 detectors and a double-sided mirror assembly. At a nominal altitude of 829 km, the swath width is 3,060 km, providing global daily coverage for both day and night passes. VIIRS has 22 spectral bands, covering the spectrum from 0.4-12 um, including 16 moderate resolution bands (M-bands). The L2P SST product is derived at the native sensor resolution (~0.75 km at nadir, ~1.5 km at swath edge) using NOAA's Advanced Clear-Sky Processor for Ocean (ACSPO) system, and reported in 10 minute 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 27GB/day. In addition to pixel-level earth locations, Sun-sensor geometry, and ancillary data from the NCEP global weather forecast, ACSPO outputs include four brightness temperatures (BTs) in M12 (3.7um), M14 (8.6um), M15 (11um), and M16 (12um) bands, and two reflectances in M5 (0.67um) and M7 (0.87um) bands. The reflectances are used for cloud identification. Beginning with ACSPO v2.60, all BTs and reflectances are destriped (Bouali and Ignatov, 2014) and resampled (Gladkova et al., 2016), to minimize the effect of bow-tie distortions and deletions. SSTs are retrieved from destriped BTs. SSTs are derived from BTs using the Multi-Channel SST (MCSST; night) and Non-Linear SST (NLSST; day) algorithms (Petrenko et al., 2014). ACSPO clear-sky mask (ACSM) is provided in each pixel as part of variable l2p_flags, which also includes day/night, land, ice, twilight, and glint flags (Petrenko et al., 2010). Fill values are reported in all pixels with >5 km inland. For each valid water pixel (defined as ocean, sea, lake or river, and up to 5 km inland), four BTs in M12/14/15/16 (included for those users interested in direct "radiance assimilation", e.g., NOAA NCEP, NASA GMAO, ECMWF) and two refelctances in M5/7 are reported, along with derived SST. Other variables include NCEP wind speed and ACSPO SST minus reference SST (Canadian Met Centre 0.1deg L4 SST; available at Only ACSM confidently clear pixels are recommended (equivalent to GDS2 quality level=5). Per GDS2 specifications, two additional Sensor-Specific Error Statistics layers (SSES bias and standard deviation) are reported in each pixel with QL=5. Note that users of ACSPO data have the flexibility to ignore the ACSM and derive their own clear-sky mask, and apply it to BTs and SSTs. They may also ignore ACSPO SSTs, and derive their own SSTs from the original BTs. The L2P product is monitored and validated against quality controlled in situ data provided by NOAA in situ SST Quality Monitor system (iQuam; Xu and Ignatov, 2014), using another NOAA system, SST Quality Monitor (SQUAM; Dash et al, 2010). Corresponding clear-sky BTs are validated against RTM simulation in the Monitoring IR Clear-sky Radiances over Ocean for SST system (MICROS; Liang and Ignatov, 2011). A reduced size (1GB/day), equal-angle gridded (0.02-deg), ACSPO L3U product is also available at, where gridded L2P SSTs with QL=5 only are reported, and BT layers omitted.
Dataset TypeOPEN
MeasurementOceans > Ocean Temperature > Sea Surface Temperature > Skin Sea Surface Temperature
Processing Level2P
CoverageRegion: Global
Northernmost Latitude: 90 degrees
Southernmost Latitude: -90 degrees
Westernmost Longitude: -180 degrees
Easternmost Longitude: 180 degrees
Time Span: 2018-Jan-05 to Present
ResolutionSpatial Resolution: 0.75 km (Along) x 0.75 km (Across)
ProjectionType: Satellite native swath
Detail: Geolocation information included for each pixel
Ellipsoid: WGS 84
Latency6 hours
Swath Width3 m
Sample Frequency1.786
Temporal Repeat (Nominal)12 Hour
Temporal Repeat (Min)3 Hour
Temporal Repeat (Max)2 Day
Name: National Oceanic & Atmospheric Administration-20 (NOAA-20)
Orbit Period: 102 minutes
Inclination Angle: 99 degrees
Ascending Node: 1970-Jan-01 00:00:00
Name: Visible Infrared Imaging Radiometer Suite (VIIRS)
Swath Width: 3040 km
Description: VIIRS is a 22-band radiometer to collect infrared and visible light for earth system monitoring

ProjectGroup for High Resolution Sea Surface Temperature (GHRSST)
Data ProviderCreator: NOAA Office of Satellite and Product Operations (OSPO)
Release Place: Suitland, MD, USA
Release Date: 2019-May-15
Keyword(s)NOAA, JPSS, VIIRS, ACSPO, OSPO, sea surface temperature, SST, GHRSST, GDS2, N20, v2.61
Persistent IDPODAAC-GHV20-2PO61
Questions related to this dataset? Contact
User's Guide
GDS2 User Manual
Documentation on the GDS version 2 format specification
Portal to the GHRSST Global Data Assembly Center and data access
Project Materials
ACSPO Documents
Samples, Interface Control Document describing file contents, background ppt and other info
Journal References
Petrenko, B., et al., 2010
Petrenko, B., A. Ignatov, Y. Kihai, and A. Heidinger, 2010: Clear-Sky Mask for ACSPO. JTech, 27, 1609-1623
Petrenko, B., et al., 2014
Petrenko, B., A. Ignatov, Y. Kihai, J. Stroup, P. Dash, 2014: Evaluation and Selection of SST Regression Algorithms for JPSS VIIRS. JGR, 119, 4580-4599, doi: 10.1002/2013JD020637
Additional Sites
Liang, X.
Dash, P., A. Ignatov, Y. Kihai
Xu, F.
Citation NOAA Office of Satellite and Product Operations (OSPO). 2019. GHRSST Level 2P OSPO dataset v2.61 from VIIRS on the NOAA-20 satellite (GDS v2). Ver. 2.61. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at

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For more information see Data Citations and Acknowledgments.

Journal Reference Petrenko, B., A. Ignatov, Y. Kihai, J. Stroup, P. Dash, 2014: Evaluation and Selection of SST Regression Algorithms for JPSS VIIRS. , J. Geophys. Res. Atmos., 119, doi:10.1002/2013JD020637