16 The Past, Present, and Future of the AVHRR Pathfinder SST Program
285
Another problem in Version 5 manifests itself as a jump in SST every 18 lines in
the regularly gridded data. While not clearly visible in a single image, edge detection
algorithms that examine sequences of data identified this problem. The problem is
related to the mapping procedures by which the equal-area integerized sinusoidal
bins in which the data are generated are mapped into the equal-angle, uniform grid
space in which the data are distributed. This problem has been resolved through the
use of a refined mapping procedure that will be used in Version 6.
Significantly, Version 6 will also conform to the newest GHRSST data format,
data content, and metadata requirements currently being developed, known as the
GHRSST Data Specification Version 2 (GDS v2). The GDS requires each SST pixel
value to have an associated bias and uncertainty error. These error estimates are
being developed for Pathfinder Version 6 using an error hypercube approach which
partitions the matchup database into a multi-dimensional lookup table. Pathfinder
Version 6 will also be in netCDF and will contain Climate and Forecast metadata
attributes. For the first time, Pathfinder SST data will be made available in not just
collated L3 files, but also at the L2 swath and uncollated L3 processing levels.
Another addition to Version 6 will be to include a large collection of HRPT and
LAC data collected at stations around the world. These full-resolution, 1 km data
sets will provide key inputs to ultra-high resolution analysis systems and other fine
scale applications. HRPT passes covering the east and west coasts of the United
States, the western Pacific off of Japan, and the waters around Australia, have
already been identified for inclusion into the Pathfinder Version 6 processing system
and other HRPT station data are being actively sought.
16.6 Conclusion
For 20 years, the ongoing efforts of the AVHRR Pathfinder SST Program have contributed, and continue to contribute to a wide range of marine applications. To date,
over 65,000 unique users have accessed AVHRR Pathfinder Version 5 SST data and
applied them to a diverse set of applications and research topics. While it is difficult
to accurately quantify the use of Pathfinder SST data in the scientific literature due
to varying ways in which the data have been acknowledged or cited, searches of
ScienceDirect and the Web of Science indicate that number to be in the hundreds
and perhaps thousands. These studies include climate research areas such as SST
trend analysis (e.g., Casey and Cornillon, 2001), numerical modelling applications
(e.g., Shu et al., 2009), and the use of Pathfinder data as the basis for higher-level
SST products (e.g., Reynolds et al., 2007; Marullo et al., 2007). A wide range of
ecosystem-related studies have also relied on Pathfinder SST data (e.g., Somoza
et al., 2008; Halpern et al., 2008).
Many other scientific studies, too numerous to summarize, have utilized
Pathfinder SST across a wide range of disciplines and topics. Direct applications
of the Pathfinder data to various societal benefits are also numerous. For example, Pathfinder data have been used to characterize humpback whale distributions
to reduce ship collisions, improve marine protected area design and placement,
285
Another problem in Version 5 manifests itself as a jump in SST every 18 lines in
the regularly gridded data. While not clearly visible in a single image, edge detection
algorithms that examine sequences of data identified this problem. The problem is
related to the mapping procedures by which the equal-area integerized sinusoidal
bins in which the data are generated are mapped into the equal-angle, uniform grid
space in which the data are distributed. This problem has been resolved through the
use of a refined mapping procedure that will be used in Version 6.
Significantly, Version 6 will also conform to the newest GHRSST data format,
data content, and metadata requirements currently being developed, known as the
GHRSST Data Specification Version 2 (GDS v2). The GDS requires each SST pixel
value to have an associated bias and uncertainty error. These error estimates are
being developed for Pathfinder Version 6 using an error hypercube approach which
partitions the matchup database into a multi-dimensional lookup table. Pathfinder
Version 6 will also be in netCDF and will contain Climate and Forecast metadata
attributes. For the first time, Pathfinder SST data will be made available in not just
collated L3 files, but also at the L2 swath and uncollated L3 processing levels.
Another addition to Version 6 will be to include a large collection of HRPT and
LAC data collected at stations around the world. These full-resolution, 1 km data
sets will provide key inputs to ultra-high resolution analysis systems and other fine
scale applications. HRPT passes covering the east and west coasts of the United
States, the western Pacific off of Japan, and the waters around Australia, have
already been identified for inclusion into the Pathfinder Version 6 processing system
and other HRPT station data are being actively sought.
16.6 Conclusion
For 20 years, the ongoing efforts of the AVHRR Pathfinder SST Program have contributed, and continue to contribute to a wide range of marine applications. To date,
over 65,000 unique users have accessed AVHRR Pathfinder Version 5 SST data and
applied them to a diverse set of applications and research topics. While it is difficult
to accurately quantify the use of Pathfinder SST data in the scientific literature due
to varying ways in which the data have been acknowledged or cited, searches of
ScienceDirect and the Web of Science indicate that number to be in the hundreds
and perhaps thousands. These studies include climate research areas such as SST
trend analysis (e.g., Casey and Cornillon, 2001), numerical modelling applications
(e.g., Shu et al., 2009), and the use of Pathfinder data as the basis for higher-level
SST products (e.g., Reynolds et al., 2007; Marullo et al., 2007). A wide range of
ecosystem-related studies have also relied on Pathfinder SST data (e.g., Somoza
et al., 2008; Halpern et al., 2008).
Many other scientific studies, too numerous to summarize, have utilized
Pathfinder SST across a wide range of disciplines and topics. Direct applications
of the Pathfinder data to various societal benefits are also numerous. For example, Pathfinder data have been used to characterize humpback whale distributions
to reduce ship collisions, improve marine protected area design and placement,