Flight Scientists Notes - NASA06. January 18, 2006.

Crew for the flight was: Jeff Snider, Jeff French, Tom Drew and David Leon.

The planned takeoff at noon was delayed by approximately 1 hour due to leak testing the CCN and efforts to fix an apparent leak. During this time the cloud layer over the Snowy Range appeared to deepen considerably and the trailing edge of the cloud layer extended significantly into the Laramie valley.

The aircraft took off just before 20:00 UTC and, helped by the strong winds was able to climb to about 20kft on the westbound leg towards the Snowy Range. The trailing edge of the cloud was encountered at about 15 - 18 nmi downwind of GLEES and with a cloud base at around 10,700 ft (from the altimeter ). At about 17kft there was a discernable gap between the upper Altostratus layer and the lower cloud layer with the two layers merging over the higher terrain. There were numerous 2D-C and 2D-P records confirming that these probes were working, however the PCASP was apparently not.

During the climb Jeff French noticed that 'PUSED' was not working, and as a consequence, all variables that depend on pressure were messed up on the display (winds, theta, etc). Jeff F. switched the pressure used to PMB which restored sanity to the displayed winds, etc.

During the first along wind leg the WCR stopped recording data due to a problem communicating with the 'data' drive. This problem was not noticed until near the end of the along-wind leg. During the descent into Saratoga for the initial sounding and for part of the cross-wind leg of the 'H' Jeff F. worked to restart the WCR: first by rebooting wasp without powering off (which was unsuccessful - the reboot stopped at mounting the data disk), and then by powering down the system which was successful.

A well-defined leading edge to the water cloud extending perhaps a few miles over the Saratoga valley was evident with the two cloud layers merging over the higher terrain. The upper level cloud was continuous over the valley. We flew parallel to the edge of the liquid cloud resulting in an aircraft track that differed significantly from 90 from the wind. Several heading adjustments were made during these legs to avoid the leading edge of the cloud layer.

Following the upwind leg of the H, the aircraft flew downwind over the GLEES site at about 14kft. WCR echoes were strong down to the surface with stratiform cloud above. Echoes in may places appeared to approach or exceed the +20dBZ upper limit on the display. Of particular interest was that there was frequently a gap between the upper and lower cloud echoes in the WCR data - a feature that may have become more pronounced during the subsequent flight legs. About 5nmi upwind of GLEES ice started to accumulate on the leading egde of the wing confirming that we had entered the liquid cloud layer. There were numerous records from both the 2D-C and 2D-P.

We then started the cross-wind leg of the H downwind of the Snowy Range. As expected the trailing edge of the cloud layer was considerably more diffuse than the upwind leg. The orientation of this leg of the H was closer to perpendicular the winds, however some course corrections were sill made to maintain separation from the trailing edge of the cloud (the cloud edge protruded farthest into the valley near the center of the H - presumably downwind of the highest terrain. Both north and south of the ends of the flight leg the upper level cloud layer deepened considerably (prior to the flight the Cheyenne WSR had shown echoes over Steamboat).

Following completion of the H pattern, we started to make along-wind passes over the GLEES site at 14kft and 17kft. The 17kft altitude was chosen as the approximate top of the solid cloud layer based on the WCR data, although generating heads frequently extended 1km or more above this level. During the series of along-wind legs the upper level cloud layer weakened considerably, and by the final legs there was a complete break in the cloud layer over the Saratoga valley with a fuzzy trailing edge of the cloud layer over the Sierra Madre much like we are used to in the Laramie valley.

By the final leg we only entered cloud over the highest terrain a few miles before GLEES. Probably the most interesting ovservation from the WCR was the existence of a (frequently) separate echo adjacent to the terrain as it is unclear where ice would have originated in this layer, although it may have been seeded by the upwind cloud over the

Sierra Madre.

The upward + dual-downward looking configuration of the WCR was used almost exclusively for this flight. A single along-wind pass was made with the radar in the side + dual-downward looking configuration of the WCR. For future WCR operations I would consider going to a mode with somewhat fewer range gates (the 4.5km recorded range was overkill for this flight) I would also consider including an along-wind, above-cloud pass (if possible) with the radar in dual-downward looking mode to document the flow throughout the cloud layer. I would also consider adding a 360 degree turn over the GLEES site to document the 3-D wind profile.

Specific entries from notes:

194927 - Engines on. Typical fuzzy cloud over snowy range. Tops @ ?.

Recording data.

195300 - Taxiing

195700 - Takeoff

195847 - Cloud base @ ~10,700 (from altimeter)

200139 - Recording data, PMS problems. Trailing edge of cloud ~18km from GLEES.

200315 - Entering edge of ice cloud. 2DP & 2DC particles.

200708 - In cloud. Break between upper level ice cloud and lower level cloud.

201315 - Now heading twoards Saratoga. TDP @ -36, TRF -27.

201315 - Descending into Saratoga for missed approach.

201700 - Cloud base @ 13kft.

202315 - End of climb following missed approach

202437 - Starting H, paralleling upwind edge of (water) cloud.

202650 - Still nothing on PCASP

203543 - Radar coming up. Disk not mounting.

204112 - Northbound leg of the H

204658 - Over Saratoga. Liquid cloud may have 2-layer structure.

204849 - Turn @ N. end of H. Return to center. Will do leg @ 14kft over the range.

           Leading Edge of the liquid cloud.

            file started.

205400 - Climb to 14kft for along-wind pass.

            weaker, broken.

210000 - Block altitude approved. Will work along the 190

210229 - Starting downwind leg. Solid echoes down to the surface. Lots of 2D data.

210531 - Ice accumulating on LE of wing.

210613 - Over GLEES

210859 - End of along-wind leg.

           leg of H @ 10kft. As before significant variability in edge of cloud.

211520 - H southbound leg. Re watering CCN pads. Solid echo to the sfc.

211732 - S. end of H.

212330 - Center point of downwind leg of H

212718 - Getting into N. edge of cloud.

212924 - Turn at N. end of leg.

213227 - Approaching center of leg

213342 - Clouds thicker.

213522 - Turn & climb to 14kft for leg across the snowies (along-wind)

213842 - Start of upwind leg @ 14kft. New radar file started.

214434 - Over GLEES

214904 - over edge of liquid cloud to the left (South).

215214 - End of leg. Next leg @ 250 degrees and 17kft.

215425 - Start of downwind leg.

215752 - In and out of cloud.

220230 - Out of cloud.

220412 - End of leg.

220643 - Start of new leg.

220916 - About to re-enter cloud.

211538 - Over GLEES right @ cloud top.

221944 - Out of cloud. Sunny. Good view of liquid cloud below.

223340 - Sounding into Saratoga

223340 - End of sounding. On sounding a small inversion evident above 12kft.

224224 - Last leg started. Clouds much weaker. Upper level stuff is almost gone.

224335 - Over LE of water cloud.

224657 - Over GLEES

224725 - Out of cloud.

           that layer just above the surface ?

225930 - On the ground.