A Collector for Fog Water and Interstitial Aerosol

Abstract

An active heatable cloud water collector for ground sampling is presented. The collector can be operated unattended for approximately one week, even in harsh winter conditions. The collection strands are Teflon tubes. A preset cycle of 15-min sampling followed by 250 s of mild heating using wires inserted into the tubes is used. The lower cutoff diameter for fog droplets is 7.3 μm, and its overall collection efficiency is 79% for the liquid water content of fogs at the experimental site in central Europe. It performed reliably during a 2-yr experiment. The collected fog water interacts exclusively with inert materials such as Teflon and Perspex so the collector is well suited for trace analyses of fog water. The collector can be upgraded with an interstitial aerosol collection unit, at the expense of unattended operation. The lower cutoff diameter of the fog water collection strands is 8.1 μm when the interstitial aerosol module is installed. The module efficiently collects particles with diameters <3.5 μm. For these particles, size-segregated samples in four size classes at diameters down to 0.06 μm are collected with a Berner-type impactor. The collector was successfully employed in a mountainous region of central Europe. Over 400 samples were collected within 2 yr. With the collection unit for interstitial aerosol added, 31 samples were collected in a 2-month period.

Chemical Composition of Fog Water at Four Sites in Taiwan

“…An active fog collector, consisting of a fan unit and a fog collection unit, was modified after Klemm et al (2008). The fog collection unit is completely made up of inert materials, PEEK (polyether ether ketone) and PTFE (polytetrafluoroethylene), to prevent contamination from construction material and sampling lines in terms of ions and metals.…”

Fog chemical composition and its feedback to fog water fluxes, water vapor fluxes, and microphysical evolution of two events near Paris

“…Fog collection was undertaken using an active fog collector which is modified after Klemm et al (2008). It has two blocks, a fan unit and a fog water unit (Fig.…”

A Low Cost System for Detecting Fog Events and Triggering an Active Fog Water Collector

“…The latter method is preferred for chemical analysis of the fog water since the materials that make up the active fog water collector are chemically inert and are rigorously cleaned between fog events (Klemm et al, 2008). In addition, active fog water collectors can be effective in places where wind speed is low, such as in forests or among buildings.…”