# Disjunct eddy covariance

From AMS Glossary

## disjunct eddy covariance

The disjunct eddy-covariance method is a direct method to measure turbulent fluxes suitable for compounds for which no fast response sensors are available.

The disjunct eddy-covariance method is based on the same approach as the eddy-covariance method (EC): the vertical flux is the covariance of the vertical wind speed and the transported quantity. In the standard EC method, the sampling interval of vertical wind speed and concentration are equal (and of the same order as the response times of both instruments). In the disjunct eddy covariance, the response time of the instrument (slow) and the response time of the sampling (necessarily fast) are decoupled: the fast response of the sampling is attained by taking air samples over a short time span (typically 0.1–0.5 s). These samples are subsequently analyzed over a time span that is dictated by the slow instrument. Because of the long analysis time, the number of concentration samples is typically 1 to 2 orders of magnitude smaller than the number of wind speed samples.

*Term edited 14 July 2016.*