SeaWinds on QuikSCAT Enhanced Resolution Regionally Gridded Sigma-0 (BYU, D. Long)
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DescriptionThis dataset contains enhanced resolution gridded fields of the normalized radar cross-section (sigma-0) made from the SeaWinds on QuikSCAT L1B dataset using two different forms of the single-variate Scatterometer Image Reconstruction (SIR) algorithm: 1) for 'egg' sigma-0 measurements and 2) for 'slice' sigma-0 measurements, where 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. The SIR algorithm with 'eggs' makes images of sigma-0 at the measurement incidence angle at 4.5 km pixel resolution. 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 images at 2.225 km pixel resolution with an estimated effective resolution of 6-8 km. It is worth noting that 'slice' measurements are inherently noisier than 'egg' measurements. This dataset has been pre-subsetted for the following regions: Alaska, Amazonia, Antarctica, Arctic, Australia, Bering Strait, Greenland, Central America, East China Sea, Sea of Japan, Europe, Indonesia, Northern Africa, North America, Southern Africa, South America, Southern Asia, and Siberia. Non-enhanced fields are also provided at lower resolution in a 'GRD' gridded format that does not utilize SIR processing; 'GRD' fields are provided at 11.125 km and 22.25 km pixel resolution for slices and eggs, respectively. In addition to Sigma-0, various statistical parameters are provided for added guidance, including but not limited to: standard deviation of incidence angle, mean incidence angle, measurement counts, pixel time, mean reconstruction error, and standard deviation of the reconstructed sigma-0. Sigma-0 fields are available for specific ascending/descending nodes, local time of day, or as a daily average. SIR-formatted land mask files (containing 0 for ocean and 1 for land) are available for each standard region. SIR-formatted files containing the gridded latitude and longitude pixel locations within each region are also available. All SIR files are produced in IEEE formatted binary and gzipped for ease of transfer and storage. Each SIR file adheres to a specific naming convention, as shown here: Some additional user notes can be found here:
Dataset TypeOPEN
MeasurementSPECTRAL/ENGINEERING > RADAR > SIGMA NAUGHT > Normalized Radar Cross-Section
Processing Level3
CoverageRegion: South Africa
Region: Australia
Region: Europe
Region: Arctic
Region: Central America
Region: Alaska
Region: North America
Region: China
Region: Antarctica
Region: Bering Sea
Region: Japan
Region: Southern Asia
Region: Siberia
Region: North Africa
Region: Greenland
Region: Indonesia
Region: South America
Northernmost Latitude: 89.6 degrees
Southernmost Latitude: -89.6 degrees
Westernmost Longitude: -180 degrees
Easternmost Longitude: 180 degrees
Time Span: 1999-Jul-19 to 2009-Nov-21
ResolutionSpatial Resolution: 0.02 degrees (Latitude) x 0.02 degrees (Longitude)
Temporal Resolution: 12 Hour
ProjectionType: Gridded
Detail: Equal-Area Lambert Projection (non-polar regions); Polar-Stereographic Projection (polar regions only)
Ellipsoid: WGS 84
Latency hours
Orbit Period: 100.93 minutes
Inclination Angle: 98.6 degrees
Ascending Node: 1970-Jan-01 00:00:00
Name: SeaWinds Scatterometer (SEAWINDS)
Swath Width: 1800 km
Description: SeaWinds is a Ku-band (13.4 GHz) Scatterometer which features a single circular scanning dish antenna to provide pencil-beam measurements, as opposed to the common fan beam design as seen with other spaceborne scatterometers. The pencil-beam design has several key advantages over the more common fan beam design: higher signal-to-noise ratio, smaller size, and superior coverage. The SeaWinds single antenna utilizes twin offset feeds, thus providing two pencil-beam footprint paths with an elliptical sampling footprint of approximately 25 km (in azimuth) by 37 km (in look/range direction); these pencil beams have opposing polarizations (i.e., vertical and horizontal), thus achieving dual-polarization. The SeaWinds instrument provides a full 1800 km-wide swath coverage (including the nadir region), which allows for a nominal daily measurement coverage of 90% over the ice-free oceans.

ProjectScatterometry Climate Record Pathfinder (SCP)
Data ProviderCreator: BYU/SCP
Release Place: PO.DAAC
Release Date: 2011-Nov-03
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Citation BYU/SCP. 2011. SeaWinds on QuikSCAT Enhanced Resolution Regionally Gridded Sigma-0 (BYU, D. Long). Ver. 2. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at

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For more information see Data Citations and Acknowledgments.

Journal Reference Early, D. S. and D. G. Long, 2001: Image reconstruction and enhanced resolution imaging from irregular samples. IEEE Trans. Geosci. Rem. Sens., Vol. 39, No. 2, pp. 291-302.