Sea Surface Temperature ACSPO VIIRS RAN1 Level 2P, 3U
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NOAA ACSPO Level 2P and Level 3U Global Sub-skin SST from S-NPP VIIRS
Reanalysis version 1 (RAN1) Beta
This VIIRS L2P and L3U Reanalysis 1 (RAN1) SST data sets are produced at NOAA
STAR using the ACSPO system, from the afternoon S-NPP satellite. The data are
reported in 10min granule files in GHRSST Data Specifications v2 (GDS2) format
and cover a period from 1 Mar 2012 to 31 Dec 2015.
This Beta version of RAN1 was produced at STAR in conjunction with the U.
Wisconsin group led by Liam Gumley. The UW Team used a converter from RDR (L0)
to SDR (L1b), whose origin and performance have not been independently
verified. There have been difficulties processing RDR-to-SDR data before 1 Mar
2012 (recall that VIIRS cryoradiator doors on S-NPP opened on 18 Jan 2012,
after which time RDR data became available.) Work is underway to reprocess and
create the official SST RAN1, using the SDR RAN1 produced by the NOAA SDR Team.
ACSPO retrievals are made in full VIIRS swath (~3,000 km). For data
assimilation applications (such as production of L4 analyses, especially for
those blending satellite and in situ data), correction for the single scanner
error statistics (SSES; reported in ACSPO files) biases is strongly recommended.
In each valid water pixel (defined as ocean, sea, lake or river, up to 5km
inland; fill values are reported in "invalid" pixels, at >5km inland), the
following layers are reported, among others: brightness temperatures in AVHRR
bands 3 (centered at 3.7 µm), 4 (11 µm), and 5 (12 µm); SSTs derived from BTs
using multi-channel SST (MCSST; night) and Non-Linear SST (NLSST; day)
algorithms (Petrenko et al., 2014); and ACSPO clear-sky mask (ACSM; provided
in each pixel as part of l2p_flags) (Petrenko et al., 2010).
Only ACSM "confidently clear" pixels (equivalent to GDS2 "quality level"=5,
also reported for each pixel) should be used. The ACSM also provides
day/night, land, ice, twilight, and glint flags. Note that users of ACSPO data
have the flexibility to ignore the ACSM, derive their own clear-sky mask, and
use BTs and SSTs in those pixels. They may also ignore ACSPO SST, and derive
their own SST from the original BTs.
RAN1 products are monitored and validated against in situ data (Xu and
Ignatov, 2014) in SQUAM (Dash et al, 2010) and MICROS (Liang and Ignatov, 2011).
Afternoon: S-NPP / VIIRS (1 Mar 2012 to 31 Dec 2015)
Measurement Oceans > Sea Surface Temperature > Sub-skin SST