Mission Plans and Flight Patterns

Since flights will be based out of Laramie, some lead time is necessary to notify Wyoming, assemble the flight crew and file with ATC. Advance notice of a planned flight will be provided one day before a flight. If the early morning outlook is still favorable on the flight day, then the flight crew will confirm the operational status with Wyoming and then rendezvous at the Wyoming hangar in Laramie at least one hour before take-off time.

The flight crew will consist of pilot, mission scientist, data system operator, and CSU equipment operator. Primary responsibility for directing the scientific mission is with CSU personnel who will function as mission scientists on the King Air; NCAR investigators may also be required to serve in this capacity. In consultation with the pilot, the mission scientist will select the target cloud and altitude, will direct the pattern to be flown, and will decide when to terminate a flight.

Flight altitudes will be selected to include wave clouds with temperatures from -10 to -40°C, based on NWS soundings and upper air charts and, once airborne, the real time aircraft sounding. Throughout the project, we will keep track of the range of wave cloud conditions that have been investigated. Such conditions include wave cloud temperature, size (cloud residence time), vertical velocity, and stability. When the weather scenario presents a variety of conditions and choices of wave clouds, the flight should probably expand the range of cases studied rather than replicate a case.

CSU is responsible for operating and maintaining the CSU aerosol equipment, and NCAR is responsible for equipment provided by NCAR. All investigators will monitor data from the primary measurements, trying to identify and fix any problems as soon as they develop. If a flight has been scheduled but any one of the primary instruments is inoperative, then CSU, NCAR and Wyoming will discuss whether to postpone the flight, cancel it, or proceed without some primary instrumentation.

Final versions of the flight plans will be designed by CSU, NCAR and Wyoming. Conceptual flight plans have been proposed and are described here.

Flight Patterns

Pattern No. 1 (vertical profile)

The typical #1 flight plan sequence in steps b) through e). Times estimated for each step, with total ~60 min.

a) From the surface, ascend above top of target wave cloud on the downwind side (Fig 1). (10min)

b) Fly into the wind until at about the wave crest, then descend through the top of the cloud, out the upstream base and down another ~300m (below ice saturation). This provides information about the range of temperatures and the equivalent potential temperatures (q e) in cloud and estimated location of the upwind edge for guidance later in the flight. (5min)

c) Climb back to the selected wave cloud q e altitude on the upwind side of the cloud, approximately 3km from the cloud and fly three figure-8 cross-wind patterns during aerosol sampling (Fig 2). Navigation is relative to a ground fix. Each pattern takes ~6 minutes. (20min)

d) Turn downwind and follow streamline into and through the cloud, using minimal power adjustments and letting the plane ascend and descend with the wave. (1min)

e) Continue flying downstream until beyond the region of strong down draft, and then fly three more figure-8 cross-wind patterns for aerosol sampling of cloud-processed air. (20min)

 

Pattern No. 2 (plan view)

Parts a) and b) of this pattern are the same as #1. Part c) in-cloud sampling is done by continuing figure-8 patterns downwind, into and through the cloud, rather than a single downwind cloud pass. Total 65 min.

  1. (same, 10min)
  2. (same, 5min)
  3. Climb back to the selected wave cloud q e altitude on the upwind side of the cloud, approximately 3km from the cloud and begin flying a sequence of five figure-8 cross-wind patterns. Successive patterns move progressively downwind and to higher altitudes: (1) below ice saturation; (2) just outside the upstream edge of the visible cloud (below water saturation); (3) inside the cloud; (4) same altitude as (2) but on the downstream side of the cloud; (5) same altitude as (1) but on the downstream side of the cloud. (30min)
  4. Same as step e) of pattern #1 (20min)

 

Summary: Patterns #1 or #2 repeat or alternate. When wave clouds have considerable vertical dimension or are layered over a range of altitudes, then climb a few thousand feet to a different temperature regime and fly upstream through the cloud and beyond, to start another sampling cycle with step b). Repeat until the altitude range of the cloud or of the aircraft has been covered or the cloud dissipates.

Since wave clouds often repeat in wave trains (a succession of clouds along the same streamlines), there may be opportunities for longer transects through repeatedly processed air. In this case, the basic flight plan would be modified to focus on cloud processing. Initially, the aircraft would fly pattern #1 on the most upstream wave cloud followed by air sampling and cloud penetrations between and through the wave clouds downstream.

  Back to Wave Cloud Project - March 2000