The PO.DAAC is pleased to announce the public release of the NOAA GHRSST VIIRS L2P/L3U v2.80 datasets onboard the Suomi National Polar-orbiting Partnership (NPP) and the NOAA-20 (N20); designated pre-launch as “Joint Polar Satellite System-1”, or JPSS-1/J1 satellites.
The v2.80 datasets are an updated version from the previous v2.61 VIIRS L2P/L3U datasets (DOI: 10.5067/GHV20-2PO61, 10.5067/GHVRS-2PO61, 10.5067/GHVRS-3UO61, and 10.5067/GHV20-3UO61). These datasets are processed with the NOAA Advanced Clear Sky Processor for Ocean (ACSPO) Sea Surface Temperature (SST) system, and produced operationally by the Center for Satellite Applications and Research (STAR). The datasets are formatted as netCDF-4, in compliance with the Group for High Resolution Sea Surface Temperature (GHRSST) Data Processing Specification version 2.0 (GDS2). Detailed information regarding the GHRSST Level 2P/3U products are available from the GHRSST website and also via PO.DAAC’s GHRSST mission webpage.
Several enhancements and updates over v2.61 are implemented in v2.80, including:
- Adding two thermal front layers (location of fronts, and intensity in unit of kelvin/km) in L2P and L3U SST files. Frontal locations are identified with a gradient-based method with several extra tests and algorithms to minimize possible artifacts due to residual artifacts in cloud masking.
- Reducing the L2P SST data size by a factor of ×4 (from ~10TB/sensor/yr to ~2.5TB/sensor/yr; largely by dropping the brightness temperature layers and increasing compression level).
- Using the improved ACSPO SST algorithm to mitigate warm biases in the high latitudes observed in v2.61 (up to several tenths of a degree Kelvin).
- Improving the clear-sky mask (reduced number of false alarms in dynamic and coastal areas, and minimized dependency on simulated brightness temperatures).
The L2P datasets are reported in the instrument native swath projection with 0.75 km (nadir) to 1.5 km (swath edge) spatial resolution, and organized into 10-min granules, 144 per day with a daily data volume of 7 GB/day. The L3U datasets represent a gridded (at 0.02-deg equal-angle projection) version of L2P, also consisting of 144 10-min granules per day, with a daily volume of 0.5 GB/day. The S-NPP datasets start from Feb. 1st, 2012, and the N20 datasets start from Jan. 5th, 2018. All the four datasets are active and updated daily.
The datasets are described and discoverable via the PO.DAAC dataset information pages. Currently, the Cloud OPeNDAP and Harmony API services are not available, but will be added in the near future. We recommend users to download the data with the data-subscriber tool.
Petrenko, B., A. Ignatov, Y. Kihai, J. Stroup, P. Dash. 2014. Evaluation and Selection of SST Regression Algorithms for JPSS VIIRS, JGR, 119, 8, https://doi.org//10.1002/2013JD020637
Petrenko, B., A. Ignatov, Y. Kihai, and A. Heidinger. 2010. Clear-Sky Mask for the Advanced Clear-Sky Processor for Oceans, JTECH, 27, 10. https://doi.org/10.1175/2010JTECHA1413.1
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