This directory provides access to the QuikSCAT Level 1C (L1C) Version 2 science 
data record. The complete dataset description is provided here: 
https://podaac.jpl.nasa.gov/dataset/QSCAT_L1C_NONSPINNING_SIGMA0_WINDS_V2

As a note of caution, this L1C dataset differs from all other QuikSCAT datasets
in that it starts on 16 July 2010 and ends on 30 August 2018. This limited 
time series reflects the time in which QuikSCAT was operating in what is
referred to as a "non-spinning" mode.

The averaging of the L1B input data combined with the wind vector processing 
results are both contained in this product referred to hereafter as Level 1C (L1C). 
The fixed and repointed beam processing is relative to either the one corresponding 
to the vertically polarized "outer" beam or the other corresponding to the 
horizontally polarized "inner" beam. The Sigma-0 values from the fixed operating 
beam for each frame are averaged to a single value representing approximately 50 
samples. The data points are land flagged, collocated with ECMWF surface winds, and 
have climatological nadir attenuations provided for the location and time of the 
data (not applied to the sigma0). The following enhancements have been applied in 
the Version 2 re-processing: 1) the GMF has been updated (QNS2016a) to make use of 
ECMWF nowcast 1x1 degree resolution wind direction information for the entire 
historical data record; 2) the new QNS2016a GMF leverages a calibration adjustment 
from Remote Sensing Systems (RSS) resulting in a consistently lower Normalized Radar 
Cross Section (NRCS or Sigma-0) measurements that establishes a Sigma-0 bias of 
-0.25 dB (-5.9% linear scale) compared to the L1C Version 1 data; 3) the new QNS2016a 
GMF also applies an azimuthal modulation that is decreased by several tenths of a dB 
(for Sigma-0) in variation with wind speed; this results in a more consistent wind 
speed retrieval comparison between "non-spinning" and "spinning" modes of the QuikSCAT 
instrument; 4) spacecraft attitude was re-estimated using slice data over multiple 
orbits as a replacement for lost echo-tracking capability during the "non-spinning" 
mode of the instrument; this new attitude estimation follows an unpublished manual 
technique that leverages the echo power of individual slice observations; since only a 
small subset of slice observations are analyzed, rapid variations in attitude are not 
captured; 5) continues data production beyond October 2016 through the end of mission 
on 30 August 2018. Retrieved wind directions are only slightly different from ECMWF 
values and should not be considered an independent measurement of wind direction. 
Retrieved wind speeds do not depend significantly on ECMWF speeds as evidenced by the 
fact that they agree closely with WindSAT polarimetric radiometer speeds whenever 
WindSAT and ECMWF disagree. The Sigma0 values have also been corrected for scan loss 
(due to the fact that the antenna does not scan) and for X-factor changes due to 
repointing.

A cross-referencing of orbital revolution numbers to calendar dates and UTC time of day can be
accessed at the following ASCII text file: 
ftp://podaac.jpl.nasa.gov/allData/quikscat/L1C/docs/revlist_pol_incid_start_end_times.txt.

The following subdirectories provide direct access to the L1C data files and 
corresponding MD5 checksum files.

The file naming convention is as follows:

QS_L1C_RRRRR_V2.dat

QS    = QuikSCAT Project
L1C   = Science Level 1C Processing
RRRRR = 5-digit satellite orbital revolution (rev) Number
V2    = Identifies the processing version of this dataset (V2 = Version 2).
dat   = The file extension indicating that this is a flat binary data file.

The data files provided here are uncompressed and in flat little endian 
binary format.

To acquire more detailed, up-to-date information, please visit the PO.DAAC QuikSCAT L1C Forum 
page: https://podaac.jpl.nasa.gov/forum/viewtopic.php?f=16&t=391

Question and comments may also be posted directly on the PO.DAAC forum.

Last modified on 5 February 2019.