QuikSCAT_GTV

Dataset description

Gas transfer velocities (normalized to Sc=660) derived from QuikSCAT normalized radar backscatter (QSk1p4p1 data set)

Each day's worth of data has (as columns):
date, time, lon, lat, u, v, k, num_k, k46, num_k46, k54, num_k54, kLM, kW, kWM, kN

u and v are the east-west and north-south U10 wind velocities for that time and location.
k is the Glover radar-based estimate for transfer velocity.
num_* refers to the number of individual QuikSCAT radar returns used.
46 and 54 refer to the inner and outer dual, conically scanning radar pencil beams.

kLM, kW, kWM, and kN refer to transfer velocities derived from QuikSCAT wind speeds [sqrt(u2+v2)]
using Liss-Merlivat'86, Wanninkhof'92, Wanninkhof and McGillis'99, and Nightingale'00 respectively.

The data are spatially distributed in Wind Vector Cells (WVC) of roughly 25 km2.
There are 4 to 6 views of at least part of the SO GasEx area each day

For these data, the area is defined as 30-50° W, 40-60° S.
Potentially, there are 6400 data points per time/date data set.

The times are given in UTC.

Acquisition description

An empirical relationship between normalized radar backscatter (sigma-naught) and mean square slope
is used in a field determined quadratic relationship between mean square slope and gas transfer velocity.
QuikSCAT scatterometer sigma-naughts are obtained from a 13.4 GHz twin beam radar that scans the
surface in a circular motion at 18 rpm. Reflected signals are binned into 25 km wind vector cells with a
cross-track width of 1,800 km at the satellite’s nominal altitude of 803 km.

PI Note: This is a research quality product and has not been completely ground truthed.

Processing description

DMO notes for QuikSCAT Sigma-0 Gas Transfer Velocities

BCO-DMO Processing of Original Data

1149 data files and one header file delivered to DMO by Dave Glover and Alisdair Tullo
Original space delimited data files reformatted to BCO-DMO convention and output as csv files
Data reformatting (add BCO-DMO header record and o/p as csv files) done with awk script

"date_rev" field (date and revolution number for each data file) added to original header file


Data
Individual year, month, day fields combined into one date field and output as YYYYMMDD
Individual hour, minute, seconds fields combined into one time field and output as HHMMSS.xxx
longitude value converted to degrees East/West using value -= 360.0
"NaN" converted to "nd" (BCO-DMO convention for "No Data")
Other data values output unchanged


Header File Parameters
"date_rev" - date and revolution number
"date_start" - start date of file
"time_start" - start time of file
"date_end" - end date of file
"time_end" - end time of file
"filename" - data filename

1. Quick Scatterometer :

   An empirical relationship between normalized radar backscatter (sigma-naught) and mean square slope
   is used in a field determined quadratic relationship between mean square slope and gas transfer velocity.
   QuikSCAT scatterometer sigma-naughts are obtained from a 13.4 GHz twin beam radar that scans the
   surface in a circular motion at 18 rpm. Reflected signals are binned into 25 km wind vector cells with a
   cross-track width of 1,800 km at the satellite’s nominal altitude of 803 km.

This document is created from the content of the BCO-DMO metadata database.    2010-02-09  15:33:57