A large high pressure system was centered east of SHEBA ship. This high covered the entire Beaufort Sea. SHEBA ship was under southeasterly winds on the west side of the high. Thin altostratus clouds covered the ship during the day. They were moving northwestward and thinning in time. The radar showed two layers around 1.5 and 2.5 km that were progressively getting thinner during the afternoon. The satellite images show the altostratus breaking up wind to the southeast. The lidar appeared to penetrate through the altostratus after 22:00 UT implying their total optical depth was probably below 3.0.
The trajectories to SHEBA ship show the air coming from the east in the Beaufort Sea. Winds were light in the high so the six day trajectories are fairly short. The 9 km trajectory trajectory traces air to the east and then loops to the south. The validity of the southern part of the trajectory after four days is doubtful because of the light winds in the area.
The trajectories to Barrow show the low level air, surface to 1.5 km, coming from the east - the Alaskan coast of the Beaufort Sea. The surface trajectory differs from the rest tracing north into the Canadian Islands while the 1.0 and 1.5 km trajectories trace southeast into western Canada. Higher level trajectories, 3-9 km, trace to the south indicating the air came from the north Pacific Ocean across Alaska.
