Table of Contents

• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

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.

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.

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

The Southern Ocean Gas Exchange Experiment (SO-GasEx; also known as GasEx III) took place in the Southwest Atlantic sector of the Southern Ocean (nominally at 50°S, 40°W, near South Georgia Island) in austral fall of 2008 (February 29-April 12, 2008) on the NOAA ship Ronald H. Brown. SO-GasEX is funded by NOAA, NSF and NASA.

The research objectives for Southern Ocean GasEx are to answer the following questions:

• What are the gas transfer velocities at high winds?
• What is the effect of fetch on the gas transfer?
• How do other non-direct wind effects influence gas transfer?
• How do changing pCO2 and DMS levels affect the air-sea CO2 and DMS flux, respectively in the same locale?
• Are there better predictors of gas exchange in the Southern Ocean other than wind?
• What is the near surface horizontal and vertical variability in turbulence, pCO2, and other relevant biochemical and physical parameters?
• How do biological processes influence pCO2 and gas exchange?
• Do the different disparate estimates of fluxes agree, and if not why?
• With the results from Southern Ocean GasEx, can we reconcile the current discrepancy between model based CO2 flux estimates and observation based estimates?

Related files

SO-GasEx cruise report
SO-GasEx Science Plan
SO-GasEx Implementation Plan

The SO-GasEx cruise report and Science and Implementation plans, may also be available at the SO-GasEx science Web page.

The Ocean Carbon and Biogeochemistry (OCB) program focuses on the ocean's role as a component of the global Earth system, bringing together research in geochemistry, ocean physics, and ecology that inform on and advance our understanding of ocean biogeochemistry. The overall program goals are to promote, plan, and coordinate collaborative, multidisciplinary research opportunities within the U.S. research community and with international partners. Important OCB-related activities currently include: the Ocean Carbon and Climate Change (OCCC) and the North American Carbon Program (NACP); U.S. contributions to IMBER, SOLAS, CARBOOCEAN; and numerous U.S. single-investigator and medium-size research projects funded by U.S. federal agencies including NASA, NOAA, and NSF.

The scientific mission of OCB is to study the evolving role of the ocean in the global carbon cycle, in the face of environmental variability and change through studies of marine biogeochemical cycles and associated ecosystems.

The overarching OCB science themes include improved understanding and prediction of: 1) oceanic uptake and release of atmospheric CO2 and other greenhouse gases and 2) environmental sensitivities of biogeochemical cycles, marine ecosystems, and interactions between the two.

The OCB Research Priorities (updated January 2012) include: ocean acidification; terrestrial/coastal carbon fluxes and exchanges; climate sensitivities of and change in ecosystem structure and associated impacts on biogeochemical cycles; mesopelagic ecological and biogeochemical interactions; benthic-pelagic feedbacks on biogeochemical cycles; ocean carbon uptake and storage; and expanding low-oxygen conditions in the coastal and open oceans.

The Surface Ocean Lower Atmosphere Study (SOLAS) program is designed to enable researchers from different disciplines to interact and investigate the multitude of processes and interactions between the coupled ocean and atmosphere.

Oceanographers and atmospheric scientists are working together to improve understanding of the fate, transport, and feedbacks of climate relevant compounds, and also weather and hazards that are affected by processes at the surface ocean.

Oceanographers and atmospheric scientists are working together to improve understanding of the fate, transport, and feedbacks of climate relevant compounds.

Physical, chemical, and biological research near the ocean-atmosphere interface must be performed in synergy to extend our current knowledge to adequately understand and forecast changes on short and long time frames and over local and global spatial scales.

The findings obtained from SOLAS are used to improve knowledge at process scale that will lead to better quantification of fluxes of climate relevant compounds such as CO2, sulfur and nitrogen compounds, hydrocarbons and halocarbons, as well as dust, energy and momentum. This activity facilitates a fundamental understanding to assist the societal needs for climate change, environmental health, weather prediction, and national security.

The US SOLAS program is a component of the International SOLAS program where collaborations are forged with investigators around the world to examine SOLAS issues ubiquitous to the world's oceans and atmosphere.

» International SOLAS Web site

Science Implementation Strategy Reports

US-SOLAS (4 MB PDF file)
Other SOLAS reports are available for download from the US SOLAS Web site