ACE Canadian CV-580 Flight Log

Today, conditions in Barrow have improved and the MC-2 model is forecasting cloud at the SHEBA site. Consequently, at 10am local Inuvik time, we will fly to Barrow. If conditions look good at the ship, we will takeoff and fly out to the ship today. If conditions look better tomorrow, we will spend the night and fly out to the ship tomorrow.

This was mainly a transit flight from Inuvik to Barrow in preparation for a flight to the SHEBA ship. An intercomparison of the upward LIDAR and cloud particle measurement probes was done near 1705 UTC by flying underneath an ice crystal cloud at 16 kft and then reversing track and climbing up to 24 kft and descending down to 16 kft. Some aerosol layers were also sampled while en-route.

This was a flight to the SHEBA ship near 75 59N 166 07 W. The aircraft was flown to the ship at 24 kft. Some good LIDAR cloud top measurements were made which will be useful to compare with the model predictions of cloud top. Upon reaching the ship, an E-W run was made at 24 kft across the ship for LIDAR and radiation measurements. The aircraft was in some ice crystal cloud during this run. Then a spiral descent to 300 ft was made with the ship in the centre of the spiral. An ice crystal cloud was observed down to 9 kft. Maximum ice crystal sizes were near 800 microns with typical larger sizes near 300 microns. The ice crystals were compact and irregular in shape with lots of small crystals being observed. The concentrations on the PMS 2DP were near 50-100 m-3 with concentrations on the PMS 2D Grey being 0.3 to 1.0 litre-1. Several runs were made along a lead which had opened up (3 boat lengths wide) near the ship, in addition to another E-W radiation and LIDAR run at 300 ft. The ozone concentrations near 24 kft reached 150 ppb, probably due to a stratospheric intrusion, but near the surface at the boat they were below detection levels. Gas phase mercury concentrations near the surface at the boat were also unusually low. On approach into Barrow, a cloud with tops near 7.5 kft, base near 5.8 kft, was sampled. This cloud had maximum liquid water contents near 0.1 g m-3 and was snowing beneath.

• SPEC. Probe - SPEC CPI computer overheated during flight but data looks fine.
• All other instruments operational