HR: 1340h
AN: A53A-0914    [Abstracts]
TI: Tank Experiments on the Influence of Rain on Air-Sea CO₂-Exchange
AU: * Anweiler, A
EM: anne-kristin.anweiler@zmaw.de
AF: Institute of Oceanography, University of Hamburg, Bundesstrasse 53, Hamburg, 20146, Germany
AU: * Anweiler, A
EM: anne-kristin.anweiler@zmaw.de
AF: International Max Planck Research School for Maritime Affairs, Max Planck Institute for Foreign Private Law and Private International Law, Mittelweg 187, Hamburg, 20148, Germany
AU: Gade, M
EM: martin.gade@zmaw.de
AF: Institute of Oceanography, University of Hamburg, Bundesstrasse 53, Hamburg, 20146, Germany
AB: In the frame of the national project WiSSCy (Impact of Wind, Rain, and Surface Slicks on Air-Sea CO₂ Transfer Velocity â€" Tank Experiments) we have conducted laboratory experiments that were devoted to air-sea CO₂ transfer in the presence of heavy artificial rain and wind. The experiments were performed in a 24-m- long and 1-m-wide linear wind-wave tank at wind speeds up to 8 m/s and rain rates up to 160 mm/h using slick- free and slick-covered freshwater. Rain was produced by 3000 hypodermic needles at a height of 4.5 m above the water surface. The rain generator covered an area of 2.3 m², i.e. 10 % of the total surface area. After injecting CO₂ into the tank's closed air channel, gas transfer from the air into the water was measured. Recent results of these experiments show evidence that heavy rain enhances the air-sea gas transfer at low wind speeds, whereas for wind speeds higher than 6 m/s no additional rain effect on gas transfer can be measured. The application of slicks to the water surface could be shown to result in a strong reduction of gas exchange. However, this effect was counteracted when slicks were combined with heavy rain. Fetch dependence and dynamics inside the water body were examined by analyzing water samples at different fetches and depths and measuring water current profiles using Acoustic Doppler Velocimetry. In order to investigate the impact of freshwater rain on seawater, similar experiments were performed in a 1m x 0.7m x 1.3m smaller tank for different rain rates and saline water.
DE: 4504 Air/sea interactions (0312, 3339)
DE: 4568 Turbulence, diffusion, and mixing processes (4490)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting