Wednesday, February 27, 2019

DOI:  10.5067/GHV20-2PO26

The PO.DAAC is pleased to announce the public release of the NOAA GHRSST VIIRS L2P/L3U v2.60 Datasets onboard the Suomi National Polar-orbiting Partnership (SNPP) and the NOAA-20 (N20); designated pre-launch as “Joint Polar Satellite System-1”, or JPSS-1 (i.e., J1) satellites. The v2.60 is an updated version from the current v2.41 SNPP VIIRS L2P/L3U datasets (DOI: 10.5067/GHVRS-2PO41 and 10.5067/GHVRS-3UO41), but represents the first release of the N20 VIIRS L2P/L3U datasets. These datasets are processed with the NOAA Advanced Clear Sky Processor for Ocean (ACSPO) Sea Surface Temperature (SST) system, and produced operationally by the Office of Satellite and Product Operations (OSPO). The datasets are formatted as netCDF, 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 v2.41 are implemented in v2.60, including:

1.     VIIRS L2P data are resampled to correct for bow-tie distortions and deletions. 

2.     VIIRS band-14 (8.6 microns) has been added in the SST regression algorithm, and the corresponding brightness temperature added to L2P as an extra layer.

3.     The ACSPO Clear-Sky Mask (ACSM) was updated to include a more conservative SST filter and adjusted reflectance filter. The uniformity filter in the coastal zones is now disabled, to improve coverage.

4.     Several improvements are applied in de-biased SST (calculated by subtracting the Sensor Specific Error Statistic (SSES) bias from regression SST).

5.     ACSPO software was optimized and updated, for improved portability, flexibility and consistency among different processed platforms and sensors, leading to more accurate and consistent SST retrievals.

6.     Improvements on handling quality flag, Quality Level logic, data compression, CPU usage (README).

The L2P datasets are mapped on the instrument native swath grid with 0.75 km (nadir) to 1.5 km (swath edge) spatial resolution, and organized into 10min granules, 144 per day with a daily data volume of 25 GB/day. The L3U datasets represent a gridded (at 0.02deg equiangular projection) version of L2P, assimilating 144 10min granules per day, with a daily volume of 0.6 GB/day.

These four datasets provide daily SST with global coverage, currently from 7 November 2018 onward. NOAA has future plans to back-fill the NPP and N20 L2P and L3U records back to Feb 2012 and Feb 2018, respectively, expected to be completed by the end of 2019.

The datasets are described and discoverable via the PO.DAAC dataset information pages.  Data can be accessed through Drive (L2P: NPP and N20; L3U: NPP and N20), OPeNDAP (L2P: NPP and N20; L3U: NPP and N20), THREDDS (L3U: NPP and N20) and web services. The dataset information pages also provide access to the technical documentation and guidance on how to cite the data.

Citation: Petrenko, B., A. Ignatov, Y. Kihai, J. Stroup, and P. Dash (2014), Evaluation and selection of SST regression algorithms for JPSS VIIRS, J. Geophys. Res. Atmos., 119, 4580–4599, doi:10.1002/2013JD020637

Comments/Questions? Please contact or visit the PO.DAAC Ocean Temperature Forum.

Important Information for Users:

NASA is in the process of deprecating the use of the FTP protocol for data and information access. PO.DAAC is pleased to offer PO.DAAC Drive as a robust FTP alternative for browsing and retrieving data at PO.DAAC ( It offers file navigation and download through an interface served directly through your browser, and with a familiar look and feel. It also allows users to access data via a command line so that interactions can be easily scripted. The entire PO.DAAC archive can also be mounted to a local computer as a virtual data store.

After 3 June 2019, FTP service will no longer be available at PO.DAAC. We recommend an earlier transition to maximize familiarity with PO.DAAC’s operational HTTPS data distribution services and minimize data disruption when FTP service is no longer available. To ensure a successful transition for all FTP users, our User Services Team is standing by to address all technical issues and concerns.