Three levels of cloud appeared on the ship's radar and lidar; a low boundary layer cloud, a stratus cloud around 1.4 km, and thinner clouds extending up to 5 km. The radar image changed its gain at 21:45 UT. The radar found returns up to 6 km earlier. The cloud at 1.4 km appears to be broken on the lidar image while the higher clouds appear as elongated filements on the satellite IR image.
Old lead ice patterns could be seen through the thinner clouds on the visible satellite images at 21:35, 23:15, and 00:57 UT.
The Ci was moving over the SHEBA ship during the flights. Look at the IR images at 21:35, 23:15, and 00:57 UT.
The morning sounding (12:00 UT) has an inversion at 6 km indicating the cloud top. This inversion did not appear in the 00 UT sounding, however, the relative humidity plotted is referenced to water and the upper levels, up to 8.5 km, are probably saturated with respect to ice.
Notice the contrails from the C-130 are can be seen on the IR flight track image.
On the larger scale a surface low is east of the SHEBA ship ice camp. Winds were from the north. The trajectories to SHEBA ship show the the low level air, surface - 1.5 km, coming from the Chukchi Sea south of the ship. The surface trajectory loops to the east. The 3.0 km trajectory shows air coming only a short distance from the west, while the 6 and 9 km trajectories show the air coming from eastern Siberia.
The trajectories to Barrow all come from the Bering Sea and cross western Alaska. The 6 and 9 km trajectories go farther back into Siberia.
