SeaWinds on QuikSCAT Level 2A Surface Flagged Sigma0 and Attenuations in 25Km Swath Grid Version 2
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DescriptionThe SeaWinds on QuikSCAT Level 2A Surface-flagged Sigma-0 in 25km Wind Vector Cells are processed using the pulse Sigma-0 data provided by the Level 1B product. Unlike NSCAT, the expected number of Sigma-0 cells per WVC is not constant, due to the circular scan of the SeaWinds instrument. To minimize the L2A data volume, the Sigma-0 cell data are stored as "lists" for each WVC row, with each list indexed by a "cell_index" array to indicate the cross-track WVC membership of the data. Each cell is then checked for land or ice and flagged accordingly. Attenuation corrections for each Sigma-0 measurement are also provided. Quality Assurance files are also included to verify the quality of the L2A processing. Data are provided in single-orbit files. Special note: QuikSCAT went into a "non-spinning" mode on 22 November 2009. The final rev number in the nominal Operational "spinning" mode is 54296; the "non-spinning" mode of the instrument continued predominantly for the remainder of QuikSCAT operations. There were some brief periods of "spinning" in year 2013, which include the following days and rev numbers (identified in parenthesis): 1) 29 January to 5 February (7909-71011), 2) 14 March (71536-71549), 3) 18 March to 21 March (71590-71634), and 4) 28 March to 31 March (71735-71769).
Dataset TypeOPEN
Processing Level2A
CoverageRegion: Global
Northernmost Latitude: 90 degrees
Southernmost Latitude: -90 degrees
Westernmost Longitude: -180 degrees
Easternmost Longitude: 180 degrees
Time Span: 1999-Jul-19 to 2013-Mar-31
Granule Time Span: 2013-Jan-29 to 2015-Jan-28
ResolutionSpatial Resolution: 25 km (Along) x 25 km (Across)
Ellipsoid: WGS 84
Latency hours
Swath Width1800000 m
Sample Frequency-
Temporal Repeat (Nominal)12 Hour
Temporal Repeat (Min)1.7 Hour
Temporal Repeat (Max)4 Day
Orbit Period: 100.93 minutes
Inclination Angle: 98.6 degrees
Ascending Node: 1999-Jul-19 06:04:49
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.

ProjectEarth Observing System Data Information System (EOSDIS)
Data ProviderCreator: JPL QuikSCAT Project
Release Place: PO.DAAC
Release Date: 2006-Jul-19
Keyword(s)ocean, roughness, ocean roughness, winds, radar, backscatter, normalized radar cross-section, normalized radar cross section, nrcs, sigma-0, sigma0, sigma naught, dB, L2A, level 2A, 25, 25-km, 25 km, scatterometer, quikscat, qscat, seawinds
Persistent IDPODAAC-QSX25-L2A02
Questions related to this dataset? Contact
User's Guide
QuikSCAT Science Data Record User Guide
Science Data Record User Guide
L2A SIS Document
Software Interface Specifications for L2A
Known Issues
QuikSCAT Known Problems and Issues
Web Page Consisting of Known Problems, Issues, and Data Gaps
Citation JPL QuikSCAT Project. 2006. SeaWinds on QuikSCAT Level 2A Surface Flagged Sigma0 and Attenuations in 25Km Swath Grid Version 2. Ver. 2. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at

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