Corrections of Surface Particle Probe Measurements for the Effects of Aspiration

Abstract

Particle probes from Particle Measuring Systems are routinely designed to be mounted on an aircraft or other movable platform. There are attempts, however, to apply this technology to stationary surface measurements by inducing airflow through the sample area. Use of these measurements quantitatively requires an understanding of how the measurements are distorted by the aftificial airflow. In an application to surface snowfall measurements, a 2D-C probe with a horn-shaped aspirator has been used for six winter seasons in the Sierra Nevada of California. To correct measurements from this instrument, three other methods to measure ice particle concentrations and size distributions at the ground are presented and compared to simultaneous measurements by the aspirated 2D-C. The aspirated 2D-C was found to routinely overestimate ice particle concentration by factors of 2.4 to 3.2. In addition, the amount of overestimation was found to be a function of particle size and surface wind speed.