A note on aerosol sized particle deposition onto dense and tall canopies situated on gentle cosine hills

Abstract

Micrometeorological measurements of aerosol sized dry particle deposition velocity (Vd) onto forested canopies have significantly advanced over the past two decades and now include both-airborne and stationary platforms. However, the interpretation of theseVdmeasurements still relies on stationary and planar homogeneous flow assumptions only appropriate to flat-terrain conditions. Simplified model calculations were used to examine how variations in hill height (H) introduce biases inVdwhen assumptions appropriate to flat terrain are applied to periodic and gentle 2-D cosine topography covered with tall and dense forested canopies. It was shown that increasingHreduced the variability inVdfor all aerosol sized particle diameters (dp) inside the canopy when the hill slope (H/L) remained constant (=0.1), whereLis the cosine hill half-length. At the landscape scale, as may be monitored from airborne platforms, assumptions appropriate to flat-terrain appear accurate with increasingHfor a constant and gentleH/L(= 0.1). Inside the canopy, variability inVdtends to be larger than above the canopy for allHvalues anddp classes. ©2011 The Authors Tellus B ©2011 John Wiley & Sons A/S.