Eddy Correlation

NEW! Eddy Correlation software SOHFEA is available here, along with a Baltic Sea example data set available here!

In lakes and oceans, a prime question concerns the flux of dissolved oxygen (DO) through the sediment-water interface. DO levels are an indication of the "health" of an aquatic system.

The Eddy Correlation (EC) method was implemented several decades ago for measuring constituent fluxes in the atmosphere, the application of the EC technique for measuring DO fluxes in stratified waters is still somewhat novel, but becoming increasingly common.

The EC technique has several distinct advantages over traditional DO uptake measurement methods (e.g. in situ chambers, DO sediment microprofiles). The most obvious advantage is that the EC technique does not disturb the sediment and natural hydrodynamics. It can also be deployed in areas where these other techniques can not (e.g. rocky areas, coral reefs, etc).

Given the obvious benefits of the EC technique, we work towards an easily deployable EC instrument combined with routine protocol for data analysis.

Eddy Correlation Device
A typical EC device consists of a velocimeter (e.g. Vector, Nortek, www.nortek-as.com) and a Clark-type oxygen microelectrode (www.unisense.com; 90% response time <0.3 s) that allow simultaneous measurements of near sediment velocity and DO concentrations.

Our work at Eawag and Geomar has lead to a new, robust amplifier design as well as sophisticated designs for deployment frames, amplifier housings and sensor holders (see McGinnis et al. 2011). Please contact me for more information or amplifier schematics.

Some nice Eddy Correlation links here (please email me links, I will glady add them here):
UVA Eddy Group
MPI Eddy Group

Manufactures:
PME, Inc.
Rockland Scientific
Unisense

Nortek AS, Vector ADV

Related Publications:
Attard, K., R. N. Glud, D. F. McGinnis, S. Rysgaard, Seasonal rates of benthic primary production in a Greenland fjord measured by aquatic eddy-correlation, Submitted to Limnology & Oceanography

Glud, R. N., S. Rysgaard, G. Turner, D.F. McGinnis, R.J.G. Leaky, Biological and physical induced oxygen dynamics in melting sea-ice in the Fram Strait, submitted to Limnology & Oceanography

Kreling, J., J. Bravidor, D. F. McGinnis, M. Koschorreck, and A. Lorke, Physical controls of oxygen fluxes at pelagic and benthic oxyclines in a lake, submitted to Limnology & Oceanography

Lorke, A., D.F. McGinnis, A. Maeck (2013), Eddy-correlation measurements of benthic oxygen fluxes: Effects of coordinate transformations and averaging time scales. Limnology and Oceanography: Methods, 11, 425-437.

Lorke, A, D.F. McGinnis, A Maeck, H Fischer, Effect of ship locking on sediment oxygen uptake in impounded rivers (2013) Water Resources Research, 48, W12514.

McGinnis, D. F., S. Cherednichenko, S. Sommer, P. Berg, L. Rovelli, R. Schwarz, R. N. Glud, P. Linke (2011), Simple, robust eddy correlation amplifier for aquatic dissolved oxygen and hydrogen sulfide flux measurements, Limnology and Oceanography: Methods, 9, 340-347.11.

Lorrai, C., D.F. McGinnis, P. Berg, A. Brand, and A. Wüest (2010), Eddy correlation technique for turbulent oxygen flux measurements in aquatic ecosystems, Journal of Atmospheric and Oceanic Technology, 27 (9), 1533 - 1546.

Brand, A., D.F. McGinnis, B. Wehrli, and A. Wüest (2008), Intermittent oxygen flux from the interior into the bottom boundary of lakes as observed by eddy correlation, Limnol. Oceanogr., 53 (5), 1997-2006.

McGinnis, D.F., P. Berg, P. Brand, C. Lorrai, T.J. Edmonds, and A. Wüest (2008), Measurements of eddy correlation oxygen fluxes in shallow freshwaters: Towards routine applications and analysis, Geophysical Research Letters, 35 (L04403).