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Description

NOAA STAR produces two lines of gridded 0.02 degree super-collated L3S LEO sub-skin Sea Surface Temperature (SST) datasets, one from the NOAA afternoon JPSS (L3S_LEO_PM) satellites and the other from the EUMETSAT mid-morning Metop (L3S_LEO_AM) satellites. The L3S_LEO_AM is derived from three Low Earth Orbiting (LEO) Metop-FG satellites: Metop-A, -B and -C . The Metop-FG satellite program was jointly established by the European Space Agency (ESA) and the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT). The US National Oceanic and Atmospheric Administration (NOAA) under the joint NOAA/EUMETSAT Initial Joint Polar System Agreement, has contributed three Advanced Very High Resolution Radiometer (AVHRR) sensors capable of collecting and transmitting data in the Full Resolution Area Coverage (FRAC; 1km/nadir) format.
The L3S_LEO_AM dataset is produced by aggregating three L3U datasets from MetOp-FG satellites (MetOp-A, -B and -C; all hosted in PO.DAAC) and covers from Dec 2006-present. The L3S_LEO_AM SST dataset is reported in two files per 24-hour interval, daytime and nighttime (nominal Metop local equator crossing times around 09:30/21:30, respectively), in NetCDF4 format, compliant with the GHRSST Data Specification version 2 (GDS2). The Near Real Time (NRT) L3S-LEO data are archived at PO.DAAC with approximately 6 hours latency, and then replaced by the Re-ANalysis (RAN) files about 2 months later, with identical file names. The dataset is validated against quality controlled in situ data, provided by the NOAA in situ SST Quality Monitor system (iQuam; Xu and Ignatov, 2014), and monitored in another NOAA system, SST Quality Monitor (SQUAM; Dash et al, 2010). The L3S SST imagery and local coverage are continuously evaluated, and checked for consistency with other Level 2, 3 and 4 datasets in the ACSPO Regional Monitor for SST (ARMS) system. NOAA plans to include data from other mid-morning platforms and sensors, such as MetOp-SG METImage and Terra MODIS, into L3S_LEO_AM. More information about the dataset can be found under the Documentation and Citation tabs.

Version Description

Advanced Clear Sky Processor for Ocean version 2.80

Product Summary

Platforms
METOP-A ,
METOP-B ,
METOP-C
Instruments
AVHRR-3
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Spatial Resolution
0.02 Decimal Degrees x 0.02 Decimal Degrees
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2006-12-01
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC) ,
Center for Satellite Applications and Research, NESDIS, NOAA, U.S. Department of Commerce (DOC/NOAA/NESDIS/STAR)
Concept ID
C2050135480-POCLOUD
Data State
ACTIVE
Number of Files/Granules
13886
Processing Level
3
Published
Science Keywords
Sea Surface Subskin Temperature

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

NOAA/STAR. (2021). GHRSST NOAA/STAR ACSPO v2.80 0.02?? L3S Dataset from mid-Morning LEO Satellites (GDS v2) [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/GHLAM-3SS28 Date Accessed: 2025-12-14

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
crs coordinate reference system N/A int N/A N/A 1
dt_analysis Deviation from reference SST, i.e., dt_analysis = SST - reference SST kelvin short -32768 -32767 to 32767 0.01
l2p_flags L2P common flags in bits 1-6 and data provider flags (from ACSPO mask) in bits 9-16: bit01 (0=IR: 1=microwave); bit02 (0=ocean; 1=land); bit03 (0=no ice; 1=ice); bits04-08 (reserved,set to 0); bit09 (0=radiance valid; 1=invalid); bit10 (0=night; 1=day); bit11 (0=ocean; 1=land); bit12 not used (set to 0); bit13 (0=no glint; 1=glint); bit14 (0=no snow/ice; 1=snow/ice); bits15-16 (00=clear; 01=probably clear; 10=cloudy; 11=clear-sky mask undefined) N/A short -32768 -32768 to 32767 1
l3s_sst_reference Reference SST used for determining weights of L3U pixels to the L3S output. It is a 7x7 sliding window weighted mean of sea_surface_temperature. Weights are equal to sst_count with a maximum weight of 5. Coverage is improved compared to sea_surface_temperature, at the cost of reduced feature resolution. This is an experimental variable and is subject to change. kelvin short -32768 -32767 to 32767 0.01
lat Latitudes for locating data degrees_north float N/A -90 to 90 1
lon Longitude for locating data degrees_east float N/A -180 to 180 1
quality_level SST quality levels: 5 corresponds to “clear-sky” pixels and is recommended for operational applications and validation. N/A byte -128 0 to 5 1
satellite_zenith_angle Satellite zenith angle corresponding to L3U SST measurement with highest weight. degrees short -32768 -32767 to 32767 0.01
sea_surface_temperature SST obtained by regression with buoy measurements, sensitive to skin SST. Further information at (Petrenko et al., JGR, 2014; doi:10.1002/2013JD020637) kelvin short -32768 -200 to 32767 0.01
sses_bias Bias is derived against Piecewise Regression SST produced by local regressions with buoys. Subtracting sses_bias from sea_surface_temperature produces more accurate estimate of SST at the depth of buoys. Further information at (Petrenko et al., JTECH, 2016; doi:10.1175/JTECH-D-15-0166.1) kelvin byte -128 -127 to 127 0.016
sses_standard_deviation Standard deviation of sea_surface_temperature from SST measured by drifting buoys. Further information at (Petrenko et al., JTECH, 2016; doi:10.1175/JTECH-D-15-0166.1) kelvin byte -128 -127 to 127 0.01
sst_count Number of L3U pixels contributing to L3S pixel 1 byte -128 0 to 127 1
sst_dtime time plus sst_dtime gives seconds since 1981-01-01 00:00:00 UTC seconds int -2147483648 -2147483647 to 2147483647 0.25
sst_front_position Binary indicator of SST front position in the valid SST clear-sky domain: 1 - SST front present, 0 - no front present N/A byte -128 0 to 1 1
sst_gradient_magnitude Gradient magnitude calculated from SST field in all grids with valid SST kelvin/km short -32768 -32767 to 32767 0.001
sst_source Major contributor to SST. The major contributor is defined as the platform with highest weighed l3u observation. N/A byte -128 0 to 6 1
time seconds since 1981-01-01 00:00:00 seconds since 1981-01-01 00:00:00 int N/A N/A 1
wind_speed Typically represents surface winds (10 meters above the sea surface). The wind speeds reported here are a weighted average of wind speeds reported in input l3u data. m s-1 byte -128 -127 to 127 0.15
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