A large cloud mass moved over SHEBA ship just before the ER-2 flight. The ship radar shows high clouds present from 18:30 UT with lower clouds moving in around 22:15 UT. Cloud tops were around 9 km. The ship lidar indicated bases were around 3 km.
The large high pressure system still occupied the Beaufort Sea. The trajectories to SHEBA ship show the low level air from the surface to 1.5 km rotating around the Beaufort high before reaching the ship. The higher level air, from 3 to 9 km, came from the north Pacific Ocean across Alaska.
The trajectories to Barrow at all levels above the surface came from the north Pacific Ocean south of the Aleutian Islands. The surface trajectory follows the perimeter of the Beaufort high from northern Canada.
