Autonomous Direct Covariance Atmospheric Flux and Oceanic Current Systems: An Enhanced Flux Mooring for TPOS

James B Edson, Woods Hole Oceanographic Institution, Woods Hole, United States, J. Thomas Farrar, Woods Hole Oceanographic Inst, Department of Physical Oceanography, Woods Hole, United States, Meghan F Cronin, NOAA Pacific Marine Environmental Laboratory, Seattle, United States, William S. Kessler, NOAA/PMEL/OCRD, Seattle, WA, United States, Chris W Fairall, NOAA Physical Sciences Laboratory, Boulder, United States and Karen Grissom, National Oceanic and Atmospheric Administration, National Data Buoy Center, Stennis Space Center, MS, United States
Abstract:
The latest generation of Direct Covariance Flux (DCF) Systems have been deployed in the Tropics in field campaigns such as the multi-agency DYNAMO and NASA's SPURS field program. Over the past decade or so, researchers have begun to collect long time series, O(year), of momentum and buoyancy fluxes from surface moorings. A significant achievement was reached during SPURS with the inclusion of an infrared hygrometer to make fast-response humidity measurements on a surface mooring. This provided direct measurement of latent and sensible heat fluxes from the buoyancy flux. This was accomplished by increasing the power available on the buoy using a deep well and additional batteries. Efforts are currently underway to reduce the power requirements for fast-response humidity measurements for use on low-power platforms.

Advances in our ability to make DCF measurements from surface mooring are finding their way onto operational buoy arrays. This abstract describes a joint effort between WHOI, NOAA-PMEL, NOAA-ESRL and NOAA-NDBC is being funded by the NOAA TPOS project to develop a buoy-based DCFS that computes research quality fluxes and associated means in near real-time and telemeters them to shore. The flux buoy will also measure and telemeter ocean currents from the surface to 65-m using a suite of ADCPs. These capabilities allow research to be conducted during deployment and minimizes data loss due to system failure and vandalism. The DCF and ADCP systems are expected to be deployed on a subset of the next generation surface moorings as part of TPOS, which will also include radiative and freshwater fluxes, wave statistics and state variables.

These measurements are required to investigate the exchange of momentum, heat and mass across the coupled boundary layers with a key application being improvement of bulk flux parameterizations under all wind, sea-state and stability conditions. These bulk models find wide use in numerical modeling, in field process studies and global gridded air-sea flux products that combine measurements, models and satellite data. This talk will describe some of these advances in measurement technology used to measure air-sea fluxes over the tropical oceans, and provide examples of how this data is being used to improve our understanding of air-sea interaction under a wide-variety of conditions.

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