OIB completed the “Mid-Weddell” mission, one of the most logistically difficult missions we’ve ever attempted, with an under-flight of the recently launched IceSat-2 satellite during an overnight DC8 flight in the eastern Weddell Sea, in dark to low light conditions. Adding to the complexity was the need to accurately forecast (difficult for Antarctic regions) completely clear weather (needed for IceSat-2 to measure the sea ice) far enough in advance to schedule the mission and permit aircrew and the science teams to shift body clocks to function well on this overnight mission, and just to make the task a bit more challenging, the NASA AFRC aircrew completed a flight deck window replacement hours before our takeoff.
Cloudy conditions existed for about 20 minutes over the northern portion at the beginning and end of the low level science data line, otherwise the DC8 flew in mostly clear conditions with occasional patches of thin higher clouds (which should test the ability of IceSat2 to “see” thru those cloud layers to the ice surface). During the IceSat-2 overpass time (0435:35Z) on the northbound leg, the DC8 was in completely clear sky conditions.
The southbound science leg was flown mostly at 1500′ above the ice to maximize ATM T7 lidar IR and green data collection and ATM T6 green wide scan data, and the northbound leg was flown at 3200′ with ATM T7 narrow scan green, and ATM T6 wide scan green data. The higher altitude on the northbound leg was selected to increase the ATM swath width to maximize probability of covering IceSat2 beam pairs. All OIB remote sensing instruments reported good data collection, obviously the cameras relying on visible light were impacted by the low light levels. Another increased “degree of difficulty” mission factor was use of the DC8 aircraft wind data systems to carry out several in-flight recalculations of the ATM flight path (and reprogramming of the ATM navigational input to the DC8 autopilot) to compensate for the drift of the sea ice in an attempt to survey the same sea ice during both legs of the mission. [Thanks for that, Rob! Except, yeah, no thanks for that…]
Due to outstanding efforts of many folks on the AFRC DC8 aircraft, science, and instrument teams, this mission accomplished all goals.
The teams will enjoy a well-earned rest the remainder of today, and a “hard down” day on Monday, allowing us to safely readjust our bodies and sleep cycles to our normal daytime mission schedule, hopefully the next mission attempt will be on Tuesday..
J
Wide view of tonight’s flight track
Detail of the DC8 flight line “shift” from on IceSat2 beam to another on both northbound and south bound legs
Some of the low light conditions over sea ice
Iceberg in twilight
At the southern end of the science line, we had a bit of refracted direct sunlight
Interesting sea ice patterns
Mostly frozen sea ice lead
Low level fog/clouds coming off of open water leads
ATM T6 wide scan sea ice elevation data plot ( 3 meter full vertical scale)
ATM T6 wide scan sea ice elevation data plot (4 meter full vertical scale)
ATM T6 wide scan sea ice elevation data plot (4 meter full vertical scale)
ATM T7 green narrow scan elevation data over sea ice (1 meter full scale@!)
View of both ATM T6 wide scan and ATM T7 narrow scan patterns as seen by the DC8 nadir camera
Postnote: This mission was a… nevermind.