Recent Advances and an Overview of the Surface Renewal Method for Measuring Scalar Exchange

Surface Renewal has been increasingly used as a relatively inexpensive alternative to eddy covariance, similarity-based variance techniques, and other biomicrometeorological methods for energy and trace gas flux measurements. Attractive elements of surface renewal include that it is based on the physical concept of energy and scalar balance, and that it postulates that surface exchange is closely linked to turbulent coherent structures observed within and above plant canopies. Since its development for biomicrometeorological purposes a quarter century ago, one persistent drawback has been the necessity to calibrate it against another standard method, such as eddy covariance. However, several different advances have been reported to derive calibration factors, including accounting for finite slope microfront signatures, implementing multiple ramp scales, and using similarity theory for scalar transfer within coherent structures. Surface renewal’s usage has been extended from only canopies to bare soil, although theoretically its original inception was for scalar transfer within a canopy. An updated discussion of surface renewal theory is presented here, including improvements of previous methods and introducing novel calibration factor analysis for exchange from bare soil.