The Effect Of Cloud Processing On The Hygroscopic Properties Of Aerosol Particles In The Marine Boundary Layer: Preliminary Results From A Hill Cap Cloud Experiment During The ACE-2 Experiment

Abstract

Measurements of the hygroscopic properties of submicrometer aerosol particles in marine boundary layer (MBL) air masses were made on the Canary Island of Tenerife during the second Aerosol Characterisation Experiment (ACE-2) in June and July 1997. Two identical Tandem Differential Mobility Analyser (TDMA) systems measured hygroscopic growth of individual aerosol particles when taken from a dry state (RH < 5 %) to a controlled humidified state (nominally 90 or 70 %). Several sizes in the dry particle size range between 35 to 440 nm were measured. One TDMA was located at the lighthouse at Punta del Hidalgo on northern Tenerife where marine boundary layer air could be sampled through an inlet 50 meters above the sea surface. The other instrument was placed at Paiba behind the Anaga mountain ridge on north-eastern Tenerife which was used for the hill cap cloud experiment. This upand downwind TDMA arrangement offered opportunities to study the processing of marine boundary layer air caused by single cloud passages. Eight such cloud events occurred during the ACE-2 experiment, of which two were in polluted air originating from over Europe.