What is the most common sonic gradient measurement technique? How could "averaging" be effectively minimized via the setup? Does

Response 1:

The paper by Yang et al. (2007, JGR, http://www.agu.org/journals/jd/jd0720/2006JD008243/2006JD008243.pdf) and discussions with others suggest that averaging storage fluxes over 30 minutes underestimates the true storage (up to 50%). It seems the cycle should be as short as physically possible given your sampling setup, preferably 5 minutes or less.

Response 2:

Provided by: Steven Wofsy on 6/19/2008
In order to do the storage measurement most efficiently and accurately, you would want to implement exponential averaging volumes (2 minute time constant) on each line. Alternatively, you can make one measurement by bringing all the tubes from the profile inlets into a single averaging volume. These setups are not too hard to do, but care is required to ensure appropriate flow rates in each tube--proportional to Delta-Z if the inlets are not evenly spaced. A good exponential averaging volume is a glass flask with a tiny muffin fan inside.