SeaWinds on QuikSCAT Enhanced Resolution Regionally Gridded Sigma-0 (BYU, D. Long)
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| DOI | 10.5067/QSBYU-ENR00 |
| Short Name | QUIKSCAT_BYU_L3_OW_SIGMA0_ENHANCED |
| Description | This 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: http://scp.byu.edu/docs/SIRfilename.html. Some additional user notes can be found here: http://www.scp.byu.edu/docs/QSCAT_user_notes.html. |
| Version | 2 |
| Dataset Type | OPEN |
| Measurement | Spectral/Engineering > Radar > Sigma Naught > Normalized Radar Cross-Section Cryosphere > Sea Ice > Ice Extent |
| Processing Level | 3 |
| Coverage | Region: 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 |
| Resolution | Spatial Resolution: 0.02 degrees (Latitude) x 0.02 degrees (Longitude) Temporal Resolution: 12 Hour |
| Projection | Type: Gridded Detail: Equal-Area Lambert Projection (non-polar regions); Polar-Stereographic Projection (polar regions only) Ellipsoid: WGS 84 |
| Latency | hours |
| Platform/Sensor | QUIKSCAT / Platform Name: QUIKSCAT (QUIKSCAT) Orbit Period: 100.93 minutes Inclination Angle: 98.6 degrees Ascending Node: 1970-Jan-01 00:00:00 SEAWINDS SENSOR 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. |
| Project | Scatterometry Climate Record Pathfinder (SCP) |
| Data Provider | Creator: BYU/SCP Release Place: PO.DAAC Release Date: 2011-Nov-03 Resource: https://podaac-tools.jpl.nasa.gov/drive/files/allData/quikscat/L3/byu_scp/sigma0enhanced/docs/qscat_seawinds_enhanced.pdf |
| Persistent ID | PODAAC-QSBYU-ENR00 |
Questions related to this dataset? Contact podaac@podaac.jpl.nasa.gov
| PO.DAAC DRIVE | https://podaac-tools.jpl.nasa.gov/drive/files/allData/quikscat/L3/byu_scp/sigma0enhanced |
| Format (Compression) | RAW (GZIP) |
| 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 https://doi.org/10.5067/QSBYU-ENR00.
For more information see Data Citations and Acknowledgments.
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| 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. | |||||||
