Dataset: QuikSCAT Sigma-0 Gas Transfer Velocities

Name: Gas transfer velocities (QuikSCAT normalized radar backscatter) from NOAA Ship Ronald H. Brown cruise RB-08-02 in the Southwest Atlantic sector of the Southern Ocean near South Georgia Island in 2008 (SO_GasEx project)
Published: 2008-12-05
Keywords: oceans

Cite This Dataset

Spatial Extent: N:-40.01 E:-30.01 S:-59.99 W:-49.99

Project:

Southern Ocean Gas Exchange Experiment (SO_GasEx)

Program:

Ocean Carbon and Biogeochemistry (OCB)

United States Surface Ocean Lower Atmosphere Study (U.S. SOLAS)

Principal Investigator:

Dr David M. Glover (Woods Hole Oceanographic Institution, WHOI)

Contact:

Alisdair Tullo (Woods Hole Oceanographic Institution, WHOI)

BCO-DMO Data Manager:

Stephen R. Gegg (Woods Hole Oceanographic Institution, WHOI)

Version:

5 December 2008

Version Date:

2008-12-05

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Gas transfer velocities (QuikSCAT normalized radar backscatter) from NOAA Ship Ronald H. Brown cruise RB-08-02 in the Southwest Atlantic sector of the Southern Ocean near South Georgia Island in 2008 (SO_GasEx project)

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Description

SO-GasEx Gas transfer velocities (QuikSCAT normalized radar backscatter)

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.

Methods & Sampling

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.

Data Processing Description

DMO notes for QuikSCAT Sigma-0 Gas Transfer Velocities

BCO-DMO Processing of Original Data

Files

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

Data Files

File
QuikSCAT_GTV.csv (Comma Separated Values (.csv), 364.86 MB) MD5:35ba9ce052702aa4131e7a45815c7933 Primary data file for dataset ID 2978

More Information about this dataset

Funding Sources

Funding Source	Award Number
National Aeronautics & Space Administration	NNX08AB73G

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
RB-08-02	RB0802 RHB_SO-GasEx	2008-02-29	NOAA Ship Ronald H. Brown	Christopher L. Sabine (Chief Scientist) David T. Ho (Co-Chief Scientist)	data info

Instruments

Quick Scatterometer

Supplied Description:

Instrument Type

Generic Name: Quick Scatterometer

Acronym: QuikSCAT

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/305/

Generic Description:

The QuikSCAT is a polar orbiting satellite with an 1800 km wide measurement swath on the earth's surface. Generally, this results in twice per day coverage over a given geographic region. This specialized microwave radar measures near-surface wind speed and direction under all weather and cloud conditions over Earth's oceans. Wind retrievals are done on a 25km x 25km spatial scale.

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
date	Date UTC	YYYYMMDD	date
time	Time UTC as HHMMSS.xxx	HHMMSS.xxx	time
lon	longitude, negative denotes West	decimal degrees	lon
lat	latitude, negative denotes South	decimal degrees	lat
u	zonal wind component	m/s	no_bcodmo_term
v	meridonial wind component	m/s	no_bcodmo_term
k	averaged gas transfer velocity	cm/hr	no_bcodmo_term
num_k	number of sigma-0's used	counts	no_bcodmo_term
k46	the inner beam k only	cm/hr	no_bcodmo_term
num_k46	number of inner sigma-0's used	counts	no_bcodmo_term
k54	the outer beam k only	cm/hr	no_bcodmo_term
num_k54	number of outer sigma-0's used	counts	no_bcodmo_term
kLM	k from Liss&Merlivat relation and QS wind speed	cm/hr	no_bcodmo_term
kW	k from Wanninkhof relation and QS wind speed	cm/hr	no_bcodmo_term
kWM	k from Wanninkhof&McGillis relation and QS wind	cm/hr	no_bcodmo_term
kN	k from Nightingale et al. relation and QS wind	cm/hr	no_bcodmo_term

Status message

Database

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Dataset: QuikSCAT Sigma-0 Gas Transfer Velocities

DMO notes for QuikSCAT Sigma-0 Gas Transfer Velocities

BCO-DMO Processing of Original Data