Glover, David: Woods Hole Oceanographic Institution (Project Lead)
Project Funding:
2007 - 2010
NRA: 2006 NASA: Ocean Biology and Biogeochemistry
Funded by NASA
Abstract:
We propose to continue developing our scatterometer-based algorithm for estimating airsea
gas transfer velocity (k) from QuikSCAT normalized radar backscatter (sigma
naught) at 25 km and one day resolution using field data from the GasEx-3 expedition to
the Southern Ocean. The algorithm calculates k from a field-determined, quadratic
function of the small-scale wave mean square slope (mss). The mss, in turn, is calculated
from an empirical function of QuikSCAT normalized radar backscatter (sigma naught).
Our algorithm is calibrated with an altimeter-based mss--sigma naught relationship using
co-located QuikSCAT--altimeter sigma naught. Our proposed study has the following
objectives: to (1) carry out a regional analysis of the spatial and temporal variability of k
in the proposed study area, (2) provide regional near real time (order of 3-12 hr) remotesensing
estimates of k during the field campaign, (3) use GasEx-3 field measurements of
k and surface roughness collected during QuikSCAT (and less frequently, Jason-1)
overflights to better constrain the algorithm parameters, (4) carry out time-series and
EOF analysis of the resultant gas transfer velocity fields, and (5) assimilate the resulting
gas transfer velocity fields into the NCAR Community Climate Simulation Model
(CCSM) Ocean General Circulation Model (OGCM) at both global and regional scales.
We will compare model function parameters optimized from the field data with those
derived from the altimeter-QuikSCAT match-ups in order to strengthen the calibration
obtained from the co-located TOPEX and Jason-1 sigma naught and then extend this
improvement into the seven-plus years of data overlap between the three satellites. With
internally consistent, field calibrated time series we will examine the seven-plus year
record for evidence of trends and expressions of basin to global scale phenomena
(climatic oscillation indices, e.g. ENSO, NAO, etc.). Finally, we will apply these results
to the NCAR CCSM OGCM to better constrain the air-sea flux of important, radiatively
active gases (e.g., CO2). Biogeochemical submodels of this OGCM resolve processes
that influence the time scales of gas exchange on 1-2 days and at mesoscale spatial
scales; consequently the space and time resolution of our algorithm is well suited for
capturing potential ecosystem shifts. This study has direct relevance to NASA's Ocean
Biology and Biogeochemistry program's focus on quantifying the impacts and feedbacks
of physical and biological oceanographic mechanisms, particularly carbon sources and
sinks at the air-sea interface. This completely new use of SeaWinds/QuikSCAT data will
allow an important biogeochemical property to be developed from space-based assets
beyond traditional ocean color measurements. Direct benefit to NASA will be to quantify
spatial patterns and variability of potential sources and sinks of CO2 and improve
important aspects of our dynamic understanding of the global carbon cycle.
2008 NASA Carbon Cycle & Ecosystems Joint Science Workshop Posters
- Satellite Estimation of Air-Sea Gas Transfer Velocity During GasEx-3 Using QuikSCAT and Jason-1 Microwave Radar Backscatter
-- (David M. Glover, Nelson M. Frew, Michael J. Caruso)
[abstract]
[poster]
More details may be found in the following project profile(s):
