# Product Tutorial on Sea Surface Temperature (SST)

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## Chapter VII: Products gallery

### Table of Contents

- Products gallery

### Products gallery

There is a large amount of satellite SST products available. The choice of the appropriate dataset depends on many factors. The Group for High Resolution SST (GHRSST) helps to decide which source to use, by highlighting some aspects that need to be taken into account:

1. users should be aware of the definitions of skin, sub-skin, and foundation temperatures;
2. the requirements of the users' applications, such as sampling intervals and the length of the datasets:
   - Infrared instruments measure SST skin at high spatial resolution but the surface is obscured by clouds;
   - Microwave instruments measure an approximation to the SST subskin, including through clouds, and thus have fuller coverage but at a reduced spatial resolution and beyond 50-100 km from land;
   - Geostationary satellites carry only infrared imagers, and have high temporal resolution and fixed spatial coverage centred on the Equator;
   - Polar orbiting satellites have higher spatial resolution;
   - Products blended from multiple satellites or multiple passes of the same satellite use different methods to combine the observations from several sensors and to preserve the resolution or gradients in SST;
   - There are SST products distributed in near-real time that can be used operationaly and also those that have reprocessed ensuring a homogeneous time series, known as climate data records.

The NASA Jet Propulsion Laboratory provides a catalogue website where SST products from different platforms, sensors, processing levels, grid spatial resolution, temporal resolution, spatial coverage and latency can be accessed.

The current section shows some examples of available SST datasets, namely from the NASA Jet Propulsion Laboratory (https://podaac.jpl.nasa.gov), from EUMETSAT (www.eumetsat.int) and from the P-Tree System, Japan Aerospace Exploration Agency (JAXA) (https://www.eorc.jaxa.jp/ptree/)

#### SST from Meteosat Second Generation

The EUMETSAT Ocean and Sea Ice SAF (OSI SAF, http://osi-saf.eumetsat.int) produces and freely distributes SST products starting from 2004 up to near real time, based on SEVIRI imager on Meteosat Second Generation (MSG) satellites. Products are released with a 1-hour time frequency, both for the prime satellite located at 0° longitude and also using data from MSG positioned over the Indian Ocean (MSG IODC).

Fig. 12: EUMETSAT OSI SAF SST for 17 February 2021 at 08:00 UTC derived from the EUMETSAT Meteosat-11 geostationary satellite. This product is available every hour.

Fig. 13:Figure 13 - Eumetsat OSI SAF SST for 17 February 2021 at 00:00 UTC derived from the EUMETSAT Meteosat-8 geostationary satellite (located over the Indian Ocean). This product is available every hour.

To ensure data homogeneity the OSI SAF has reprocessed this dataset with its most recent operational algorithm, releasing an SST data record that covers eight years of data, from 2004-2012. With this data record users have access to a homogeneous time series of SST measurements from a geostationary view (SEVIRI imager on MSG satellites (Meteosat-8 and Meteosat-9)).

Eumetsat OSI SAF also produces SST fields operationally from the GOES-E satellite. An illustration is shown in Fig. 14, for 17 February 2021 at 09:00 UTC.

Fig. 14: Eumetsat OSI SAF SST for 17 February 2021 at 09:00 UTC derived from GOES-E.

#### SST from AVHRR-NOAA

Fig. 15: nighttime SST (annual average) at 4-km spatial resolution obtained from a reanalysis of historical AVHRR data.

Figure 15 corresponds to nighttime SST (annual average) at 4-km spatial resolution obtained from a reanalysis of historical AVHRR data (improved using extensive calibration, validation and other information to yield a consistent, research quality timeseries for global climate studies). It represents the longest continuous global ocean physical measurement from space of SST. Development of the Pathfinder dataset is sponsored by the NOAA National Oceanographic Data Center (NODC) in collaboration with the University of Miami Rosensteil School of Marine and Atmospheric Science (RSMAS) while distribution is a collaborative effort between the NASA Physical Oceanography Distributed Active Archive Center (PODAAC) and the NODC. The collection of NOAA satellite platforms used in the AVHRR Pathfinder SST time series includes NOAA-7, NOAA-9, NOAA-11, NOAA-14, NOAA-16, NOAA-17, and NOAA-18. These platforms contain afternoon orbits having a daytime ascending node of between 13:30 and 14:30 local time (at time of launch) with the exception of NOAA-17 that has a daytime descending node of approximately 10:00 local time. SST AVHRR Pathfinder includes separate daytime and night-time, daily, 5 day, 8 day, monthly and yearly datasets. This particular dataset represents annually averaged nocturnal observations.

The AVHRR is a space-borne scanning sensor on the National Oceanic and Atmospheric Administration (NOAA) family of Polar Orbiting Environmental Satellites (POES) having an operational legacy that traces back to the Television Infrared Observation Satellite-N (TIROS-N) launched in 1978. AVHRR instruments measure the radiance of the Earth in 6 relatively wide spectral bands.

More details at:

https://podaac.jpl.nasa.gov/dataset/AVHRR_PATHFINDER_L3_SST_ANNUAL_NIGHTTIME_V51

https://doi.org/10.5067/PATHF-ANN51

#### SST from AVHRR-METOP

Fig. 16: SST composite for 17 October 2016 produced by the OSI SAF, http://osi-saf.eumetsat.int. This product is derived from the EUMETSAT polar orbiter satellite Metop 01. Source: http://osi-saf.eumetsat.int).

#### SST from MODIS on board Acqua and Terra satellite missions

Fig. 17: Day and night spatially-gridded average 8-day SSTskin from MODIS

Figure 17 refers to day and night spatially-gridded average 8-day SSTskin from MODIS onboard the Terra satelite, on a 0.083° x 0.083° longitude/latitude resolution grid. MODIS (Moderate Resolution Imaging Spectroradiometer) orbits on board the Terra and the Aqua EOS satellites acquiring data with global coverage every 1-2 days. More information at https://podaac.jpl.nasa.gov/dataset/MODIS_TERRA_L3_SST_MID-IR_8DAY_9KM_NIGHTTIME_V2019.0

#### SST from VIIRS on board Suomi NPP

The Visible Infrared Imaging Radiometer Suite (VIIRS) is one of the key instruments on board the Suomi National Polar-Orbiting Partnership (Suomi NPP) spacecraft, launched in 2011. The VIIRS follows the legacy of the AVHRR on NOAA and MODIS on the Terra and the Aqua EOS satellites. It has 22 imaging and radiometric bands covering wavelengths from 0.41 to 12.5 μm, providing data for more than twenty environmental data records, including SST.

Even though Suomi NPP is still in orbit, NOAA-20 is operational and has the same VIIRS sensor.

Source: https://ncc.nesdis.noaa.gov/VIIRS/

Fig. 18: Day and night composites of SST estimated from Suomi NPP for 7 of August 2020 (source: https://worldview.earthdata.nasa.gov/).

#### SST from HIMAWARI

Fig. 19: SST for 1 September 2017 at 15:30 UTC, derived from AHI (Advanced Himawari Imager) radiometer on board the Himawari geostationary satellite operated by the Japanese Meteorological Agency, JMA.

Source: http://www.eorc.jaxa.jp/ptree/index.html

#### SST from SLSTR on board Sentinel 3A

The Sea and Land Surface Temperature Radiometer (SLSTR) on board Sentinel 3 A is the successor of the Advanced Along Track Scanning Radiometer (A)ATSR series (aboard the European Remote Sensing satellite (ERS) and Environmental Satellite (ENVISAT) missions) and provides many applications such as SST estimates.

Fig. 20: Thermal Structure over the Mediterranean Sea as estimated from the AATSR sensor. Source: https://sentinel.esa.int/web/sentinel/user-guides/sentinel-3-slstr/overview/geophysical-measurements/sea-surface-temperature

Fig. 21: Composite of SST obtained from Sentinel 3-A onboard the SLSTR between 15-19 Jun 2017 available from the Copernicus Marine Service.

#### Global coverage daily satellite SST for SST Analysis

OSTIA stands for Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) system. OSTIA uses satellite SST data provided by international agencies via the Group for High Resolution SST (GHRSST) Regional/Global Task Sharing (R/GTS) framework to produce SST analysis on a daily basis at the Met Office. OSTIA analysis uses satellite data from sensors that include the Advanced Very High Resolution Radiometer (AVHRR), the Spinning Enhanced Visible and Infrared Imager (SEVIRI), the Geostationary Operational Environmental Satellite (GOES) imager, the Infrared Atmospheric Sounding Interferometer (IASI), the Tropical Rainfall Measuring Mission Microwave Imager (TMI) and in-situ data from ships and drifting/moored buoys. This analysis is produced to be used as a lower boundary condition in Numerical Weather Prediction (NWP) models.

Fig. 22: Example of SST map produced by OSTIA https://podaac.jpl.nasa.gov/dataset/OSTIA-UKMO-L4-GLOB-v2.0