ACSPO Global SST from AHI
The AHI SST data are produced from Himawari-8 geostationary satellite using the NOAA Advanced Clear-Sky Processor for Ocean (ACSPO) v2.50 enterprise system. Currently, only near-real time (NRT) data are produced at STAR, with a ~2days latency. The data are available in NetCDF4 format, compliant with the GHRSST Data Specifications v2 (GDS2). Currently, the data are not archived and only available at this Coast Watch page as a 2week rotated buffer. There is a plan to reprocess the AHI data, for the full Himawari-8 mission.
The data are reported hourly, in AHI Full Disk (FD), for view zenith angle not exceeding 68°, both in swath projection (L2P) and as a 0.02° gridded L3U (U=uncollated). There are 24 FDs per day, with a total data volume of 6.3GB/day for L2P and 0.6GB/day for L3U, respectively. For data assimilation applications (such as production of L4 analyses, especially those that blend satellite and in situ data), correction for the Sensor-Specific Error Statistics (SSES; reported in ACSPO files; Petrenko et al., 2016) biases is strongly recommended.
In each valid water pixel (defined as ocean, sea, lake or river, up to 5km inland; note that in "invalid" pixels, defined as those with >5km inland, fill values are reported), the following layers are reported in both L2P and L3U: SSTs derived using multi-channel SST (MCSST; night) and Non-Linear SST (NLSST; day) algorithms (Petrenko et al., 2014); ACSPO clear-sky mask (ACSM; provided in each pixel as part of l2p_flags; Petrenko et al., 2010); SSES bias and standard deviation (Petrenko et al., 2016); NCEP wind speed; and ACSPO SST minus reference (Canadian Met Centre L4 SST). For L2P, brightness temperatures (BTs) in 3.9, 8.6, 10, 11, and 12 µm bands are also reported, for those users interested in direct radiance assimilation (e.g., NOAA NCEP, NASA GMAO).
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 SSTs from the original BTs.
Both L2P and L3U SSTs are monitored and validated against in situ data (Xu and Ignatov, 2014) in SQUAM (Dash et al., 2010) and ARMS (Ding et al., 2017) systems, and BTs are monitored in MICROS (Liang and Ignatov, 2011).
|Platform/Sensor||Himawari-8 / AHI|
|Measurement/Products||Measurement Oceans > Sea Surface Temperature > Sub-skin SST|
|Processing Level||L2P and L3U|
East Asia and Western Pacific
|Temporal Coverage||2-week rotated|
|Resolution|| L2P: From 2km@Nadir to ~12km @VZA=68°
|Projection||L2P: Satellite native swath (WGS84)
L3U: Equal-grid 0.02°
|Swath Width||7,000 km|
|Temporal Repeat||6 times per hour|
|Orbital Period||1,436 Minutes|
|Orbit||Geosynchronous, ~35,800km altitude, ~140.7º East longitude|
Creator: NOAA STAR
Release Place: College Park, MD, USA
Release Date: 2017-Aug-30
|Keywords||NOAA, Himawari-8, AHI, ACSPO, SST, NRT, L2P, L3U|
[Please acknowledge "NOAA CoastWatch/OceanWatch" when you use data from our site and cite the particular dataset DOI as appropriate.]
- Dash, P., A. Ignatov, Y. Kihai & J. Sapper, 2010: The SST Quality Monitor (SQUAM). JTech, 27, 1899-1917, doi:10.1175/2010JTECHO756.1♦, www.star.nesdis.noaa.gov/sod/sst/squam/
- Ding, Y., A. Ignatov, I. Gladkova, M. Crosberg, and C. Chu, 2017: ACSPO Regional Monitor for SST (ARMS). BoM - NOAA SST Workshop, 18-21 April 2017, Melbourne, Australia (presentation), www.star.nesdis.noaa.gov/sod/sst/arms/
- Liang, X. & A. Ignatov, 2011: Monitoring of IR Clear-sky Radiances over Oceans for SST (MICROS). JTech, 28, 1228-1242, doi:10.1175/JTECH-D-10-05023.1♦, www.star.nesdis.noaa.gov/sod/sst/micros/
- Xu, F. & A. Ignatov, 2014: In situ SST Quality Monitor (iQuam). JTech, 31, 164-180, doi:10.1175/JTECH-D-13-00121.1♦, www.star.nesdis.noaa.gov/sod/sst/iquam/
- Petrenko, B., A. Ignatov, Y. Kihai, P. Dash, 2016: Sensor-Specific Error Statistics for SST in the Advanced Clear-Sky Processor for Oceans. JTech, 33, 345-359, doi:10.1175/JTECH-D-15-0166.1♦
- 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♦
- Petrenko, B., A. Ignatov, Y. Kihai, and A. Heidinger, 2010: Clear-Sky Mask for ACSPO. JTech, 27, 1609-1623, doi:10.1175/2010JTECHA1413.1♦
- Kramar, M., A. Ignatov, B. Petrenko, Y. Kihai, P. Dash, 2016:Near Real Time SST retrievals from Himawari-8 data with ACSPO at NOAA. Proc. SPIE 9827, Ocean Sensing and Monitoring VIII, 98270L, doi:10.1117/12.2229771.♦
- Petrenko, B., A. Ignatov, M. Kramar, Y. Kihai, 2016: Exploring new bands in multichannel regression SST algorithms for the next generation infrared sensors at NOAA. Proc. SPIE 9827, Ocean Sensing and Monitoring VIII, 98270N, doi:10.1117/12.2229578.♦
(♦ - non-government website)
The ACSPO AHI SST data are provided by NOAA STAR. We strongly recommend contacting NOAA SST team led by A. Ignatov before the data are used for any publication or presentation.
(♦ - non-government website)