Sea surface temperature (SST) is composited into a multi-sensor combined SST
product utilizing data from two instruments: the Advanced Very High Resolution
Radiometer (AVHRR) on the European MetOp satellites, and the
Visible Infrared Imaging Radiometer Suite (VIIRS) on the U.S.
SNPP and NOAA JPSS satellites. This product offers significant improvement over
NOAA's legacy operational AVHRR SST product.
The single-sensor SST input data are processed consistently for both
instruments using the Advanced Clear-Sky Processor for Oceans (ACSPO)
processing system, incorporating an improved SST algorithm and improved
quality masking. Specific notable improvements are increased SST
accuracy against in-situ data, better masking of clouds, and inclusion
of data at temperature fronts.
Only nighttime overpasses for the U.S. east coast are used in the composite,
i.e. the data do not represent daytime solar heating of the ocean surface.
The NOAA legacy AVHRR SST combines both daytime and nighttime overpasses.
Since the two instruments each fly on multiple satellites (e.g. MetOp-A,
MetOp-B, MetOp-C for AVHRR; and SNPP, NOAA-20, NOAA-21 for VIIRS), the product
includes SST input data from all satellites carrying these instruments.
With two instruments and multiple satellites, the combined product has
similar geographic coverage to that of the NOAA legacy AVHRR SST product.
Maximizing coverage in this way compensates for the lack of daytime
overpasses in this nighttime-only product.
The MetOp satellites have a nighttime local equator crossing time of
roughly 9:30 PM, and the SNPP or NOAA satellites have a nighttime
equator crossing of roughly 1:30 AM. The combined product thereby
represents data throughout the night.
Data from both instruments are gridded on an 830 m earth-projected grid,
close to the spatial resolution of the VIIRS instrument, thereby increasing
spatial resolution over the NOAA legacy AVHRR SST product's 1.25 km spatial
resolution. With this improvement, more data is included along coastlines,
particularly narrow coastal areas such as small rivers and bays.
Figure: SST comparison for April 26, 2021,
|AVHRR Multi-Satellite SST
("NOAA Legacy" SST, day & night)
|AVHRR-VIIRS Multi-Sensor SST|
(ACSPO, night only)
data included along coasts & at temperature fronts,
improved masking of clouds and removal of bad quality data improves
product's accuracy against in-situ data
Petrenko, B., A. Ignatov, Y. Kihai, P. Dash, 2016: Sensor-Specific Error
Statistics for SST in the Advanced Clear-Sky Processor for Oceans.
Jour. of Atmos. and Ocean. Technology, 33, 345-359,
Petrenko, B., A. Ignatov, Y. Kihai, J. Stroup, P. Dash, 2014: Evaluation
and Selection of SST Regression Algorithms for JPSS VIIRS.
Journal of Geophysical Research, 119, 4580-4599,
Petrenko, B., A. Ignatov, Y. Kihai, and A. Heidinger, 2010: Clear-Sky Mask
for ACSPO. Jour. of Atmos. and Ocean. Technology, 27, 1609-1623,