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Scatterometer Climate Record Pathfinder
SeaWinds Enhanced Resolution Image Product Users Notes

This page is designed as a dynamic repository of relevant information to aid users of SeaWinds enhanced resolution image products.

SeaWinds-on-ADEOS-II (ADEOS-II is also known as Midori-2) operated for 9 months in 2003 before a spacecraft power system failure resulted in the premature end of mission. By JPL convention, this sensor is known as "SeaWinds" while the SeaWinds sensor on QuikSCAT is termed "QuikSCAT".

Enhanced resolution images made from SeaWinds data use two different forms of single-variate the Scatterometer Image Reconstruction (SIR) algorithm: for egg sigma-0 measurements the SIR algorithm is used while for slice sigma-0 measurements, the SIR with filtering (SIRF) algorithm is used. For egg measurements the full antenna/processing spatial response is used while a simplified spatial response function in which the spatial response is assumed to be 1 over the footprint and 0 elsewhere is used for slice measurements. Unlike SASS, ERS-1/2 and NSCAT, Seawinds observations are at (essentially) a single incidence angle for each beam so no incidence angle dependence (B) estimates are made. The SIR algorithm with eggs makes images of A (in this case, sigma-0 at the measurement incidence angle) on an 4.5 km pixel grid. The effective resolution varies depending on region and sampling conditions but is estimated to be 8-10 km in most areas. The SIRF algorithm with slices makes A images at 2.225 km pixel spacing with an estimated effective resolution of 6-8 km. Slice measurements are much noisier than egg measurements. Multiple passes of the spacecraft are combined to produce a higher spatial resolution (at a cost of reduced temporal resolution).

SeaWinds is a dual-pencil-beam conically scanning scatterometer with the outer beam V pol and the inner beam H pol. The operation frequency is 13.4 GHz. In combining the multiple passes, sigma-0 is assumed to be independent of azimuth angle. While true for most areas, some azimuth dependence in sigma-0 has been observed in Antarctic firn, presumably due to sastrugi or snow dunes.

SeaWinds data was obtained from SeaWinds L1B data archived at the PO.DAAC. No recalibration has been applied.

Images are produced in the BYU .SIR file format, using the standard naming scheme. The files are gzipped to minimize storage and transfer requirements. The standard images are designed for land and ice observation and so are landmasked. However, .SIR format land mask files (containing 0 for ocean and 1 for land) are available for each standard region. .SIR format images containing "images" of the latitude and longitude of each pixel for each region are also available.