The PO.DAAC is pleased to announce the public release of the “QuikSCAT Level 1C Averaged Sigma-0 and Winds from Non-spinning Antenna Version 1.0” (hereafter L1C) dataset, which contains geo-located and averaged Level 1B Sigma-0 measurements and wind retrievals from QuikSCAT throughout a majority of the non-spinning phase of the QuikSCAT mission. During this time period the instrument was maneuvered in a unique manner to acquire backscatter data from OceanSat-2 and RapidScat incidence angles to allow cross-calibration.
The QuikSCAT scatterometer obtained ten years of global ocean surface vector winds from 1999 until its antenna stopped spinning and its nominal mission ended in 2009. Since then, it has measured a narrow (25-km) strip of backscatter values that has been used to calibrate the OSCAT scatterometer on OceanSat-2 (2010-2014) and the RapidScat scatterometer onboard the international space station (2014-present). Now for the first time, the 2010-2016 QuikSCAT data has been used to retrieve wind speeds. ECMWF wind directions are utilized in this wind speed retrieval. Triple colocation analysis with QuikSCAT, ECMWF, and RapidScat speeds and with speeds from QuikSCAT, ECMWF, and the WindSat radiometer place an upper bound of 0.4 m/s on the RMS error of the non-spinning QuikSCAT winds. Because the non-spinning QuikSCAT swath is so narrow, a large number of independent overlapping measurements (~300) are obtained for each point on the ground. This extreme amount of averaging leads to the most precise measurements of Sigma-0 and wind speed that have ever been available with global extent. Such averaging results in random wind speed errors less than 0.1 m/s.
The L1C data record begins on 16 July 2010 and extends through 3 June 2016. The data are provided in a little-endian flat binary format with read software also provided in MATLAB and Python to facilitate first-time users with becoming acquainted with this new data. New data is to be processed in bulk batches containing approximately 2 months of data at an approximate update frequency of 2 months. As a result of the data processing schedule, the latency of this dataset will vary between approximately 2 weeks and 3 months, depending the relative date of user access compared to the date of latest data processing.
Data files are sorted by the orbital revolution number and referenced by date and time using the following reference file: podaac-tools.jpl.nasa.gov/drive/files/allData/quikscat/L1C/docs/revlist_pol_incid_start_end_times.txt
More information, documentation, read software and access to the dataset may be gained through the PO.DAAC Web Portal by clicking here: http://podaac.jpl.nasa.gov/dataset/QSCAT_L1C_NONSPINNING_SIGMA0_WINDS_V1
Users who have any further questions or concerns are encouraged to visit our Forum site: https://podaac.jpl.nasa.gov/forum/.