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Description

The L3S_LEO_PM-STAR-v2.81 dataset produced by the NOAA Advanced Clear-Sky Processor for Ocean (ACSPO) system derives the Subskin Sea Surface Temperature (SST) from the VIIRSs (Visible Infrared Imaging Radiometer Suite) onboard the Suomi-NPP, NOAA-20 and NOAA-21 satellites and MODIS (Moderate Resolution Imaging Spectroradiometer) onboard the Aqua satellite. The L3S-LEO is a family of multi-sensor super-collated (L3S) gridded 0.02º resolution SST products from low earth orbit (LEO) satellites. The L3S-LEO-PM ( https://doi.org/10.5067/GHLPM-3S281 ) and AM ( https://doi.org/10.5067/GHLAM-3SS28 ) data include SSTs from afternoon (~1:30 am/pm) and mid-morning (~9:30 am/pm) satellites, respectively. The PM and AM SSTs, for both day (D) and night (N), and Terra MODIS SSTs, are further aggregated into a daily L3S-LEO-DY SST product ( https://doi.org/10.5067/GHLDY-3S281 ). <br><br>

This PM SST product is derived by collating individual satellite ACSPO L3U data ( https://doi.org/10.5067/GHVRS-3UO61, https://doi.org/10.5067/GHV20-3UO61 and https://doi.org/10.5067/GHN21-3U280 ). It covers from 2002-07-04 to present and is reported in 2 files daily, day and night, at 1:30am/pm local time. The SST is in NetCDF4 format, compliant with the GHRSST Data Specification version 2 (GDS2). The v2.81 is updated from the previous v2.80 ( https://doi.org/10.5067/GHLPM-3SS28 ): (1) v2.81 includes 3 VIIRSs (NPP, N20, and N21 from 2023-03-19 - on); (2) Aqua MODIS SST included from 2002-07-04 to 2022-12-31; (3) Time series in v2.81 extended back to 2002-07-04 (from 2012-02-01 in v2.80); (4) recently uncovered VIIRS daytime SST drifts in NPP and N20 SSTs of approximately -0.1 K/decade mitigated. <br><br>

The Near Real Time (NRT) data are available with 6h latency, and replaced by the Re-ANalysis (RAN) files in 2 months, with identical file names. They can be differentiated by the file creation time and ancillary inputs. The data are validated against quality controlled in situ data from the NOAA in situ SST Quality Monitor (iQuam; https://www.star.nesdis.noaa.gov/socd/sst/iquam), and monitored in another NOAA system, SST Quality Monitor (SQUAM; https://www.star.nesdis.noaa.gov/socd/sst/squam)

Version Description

Advanced Clear Sky Processor for Ocean version 2.81

Product Summary

Platforms
Suomi-NPP ,
NOAA-20 ,
NOAA-21 ,
Aqua
Instruments
VIIRS ,
MODIS
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
2002-07-04
Data Partner
Center for Satellite Applications and Research, NESDIS, NOAA, U.S. Department of Commerce (DOC/NOAA/NESDIS/STAR) ,
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C2805331435-POCLOUD
Data State
ACTIVE
Number of Files/Granules
17052
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. (2023). GHRSST NOAA/STAR ACSPO v2.81 0.02 degree L3S Dataset from Afternoon LEO Satellites [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/GHLPM-3S281 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 N/A -32768 to 32767 1
l3s_sst_reference Reference SST used for determining weights of L3U pixels to the L3S/L3C 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/L3C 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 -127 to 127 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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