Thursday, 6 June 2002: 10:30 AM
The Role of a Sea-Spray in Cleansing Air Pollution over Ocean Via Cloud Processes
Profound differences exist between maritime and continental air masses in their aerosol contents, leading to major differences in cloud microstructure, precipitation and electrification processes. TRMM observations of cloud microstructure and precipitation in polluted air that flows from land to sea show that the process of transition from continental to maritime air mass occurs relatively fast in clouds with roots at the marine boundary layer, but rather slowly in clouds with elevated roots. This supports the suggestion that it is the giant CCN from the salty sea spray that initiate the droplet coalescence and precipitation, which are otherwise suppressed in the polluted air. This leads to cleansing of the air by the cloud processes. The restoration of precipitation by salty sea spray can be artificially done by hygroscopic cloud seeding. In addition to the observations, this process was also simulated with the Hebrew University Cloud Model.