The conclusions then from these campaigns included the need to design a better temperature probe to be able to extend the range of study for optical turbulence encountered in the atmosphere. In August of 2000 we began a fourth measurement campaign utilizing a LongEZ aircraft, basing flights out of Idaho Falls. The primary objective of this campaign was to design and test a new ultra-sensitive, fast response airborne temperature sensor. Although this prototype had a very well-behaved recovery factor, critical in obtaining high resolution temperature measurements, the housing suppressed severely the time response of the instrument. In the second IOP, work focused on a re-designed FUST, with an element exposed to the free stream.
Initial results are very encouraging.
The image to the left was taken from the front seat of the LongEZ flying west towards the Grand Teton at 18000 ft. The graphs below show power spectra from the new FUST and the BAT temperature probe. The red-line is from the BAT and has been offset two decades to facilitate comparison. The two signals vary in-phase for low frequency oscillations, but the phase between the two begins to vary for larger frequencies. In fact this is seen in the raw signals.