Today, the "real" ACRIDICON campaign began, as HALO left its home base in Bavaria and flew to the Cape Verde Islands, a stepping stone on the jump across the Atlantic to Brazil. I was not on this flight, but I could participate virtually through the satellite link with the plane. HALO took off punctually at 1200 local time (1000Z) and climbed to 39,000'. If flew across Bavaria, Lake Constance, Switzerland, and France, and crossed the Pyrenees to enter Spain. For a while HALO chased the contrail of another plane.
After leaving Spain, HALO went out over the Atlantic and flew along the coast of North Africa, across the Canary Islands, heading for Sal Island in the Cape Verde Islands. The meteorological models had forecast a big layer of Sahara dust, centered at an altitude of about 2 km, that was spreading out from Africa across the Atlantic. To test the models, and to learn more about the properties of the dust aerosols, we took HALO down to 11000' and then 6000' as we were approaching the islands, and indeed there was a dense layer of dust that we were able to take measurements in.
(Thanks to Steffen Gemsa, Johannes Schneider, and Andreas Minikin for the pictures in this blog entry!)