DC-8 Mission Science Report

DC8, ER2 do coordinated QPE (convection emphasis) mission in Chantal. Plan was to perform radial legs through center, as coordinated by the P3 scientist, with NASA a/c flying longer legs to maintain best coordination near center. After 2 hours in this pattern, we planned to execute a rainband pattern for about an hour before returning to base.

Document vertical structure of a tropical cyclone which has consistently refused to follow the model predictions for deepening. Learn whether there is identifiable wind shear or other factor inhibiting development. For the rainband module, concentrate all airborne assets in a small region to check out and intercompare precipitation intensity indicators.

Very interesting wind patterns in storm, well-documented by dropsondes and probably by MMS. Large shears observed by dropsondes. Moderate to strong convective regions encountered north and east of the wind center, marked by strong divergence at DC8 altitude. Possibly dominated by large ice water contents of small particles, because onboard radar hardly detected some of these regions and did not indicate more than light intensity. Ice problems for pitot tubes caused poor winds and temperatures for some of flight, and difficulties for pilots. There were failures of some of the cloud physics probes so the data set is incomplete but nevertheless interesting. One leg of the rainband pattern was carried out by the ER2 before having to return home; the DC-8 passed through that general area but had to leave early as well due to the pitot problem. Some communication issues need improvement. Mission scientist and P3 scientist need to be clear on changes in flight pattern from whatever reason. Today it was the delayed departure of the NASA a/c. The satphone worked well and in the future will be used earlier in the flight if VHF comms are not established between P3 and DC8 scientist promptly.

Although the aircraft missions were not flown near the sites at Andros Island or the Florida Keys, the instrument teams in these locations maintained a normal schedule for data collection activities.