MTP's DC2000.03.15 IAC Analysis
Figure 1. Ground track.
Here's the CTC/IAC image for DC2000.03.15, taken from the official MTP web page:
Figure 2. MJ's CTC/IAC (from the official MTP web page).
Here's my IAC for the first 2/3 of the flight, covering a much smaller altitude region:
Figure 3. IAC, showing theta surfaces 5 K apart.
I see 3 possible wave features here: at 27.2 ks, 29.2 ks and 38.0 ks (i.e., 5.56, 8.11 and 10.56 hrs). Let's zoom in on them.
Figure 4. Event #1, zoom of a wave feature candidate. Dotted lines are "phase lines" for "valleys"; red solid line is a phase line for a "crest."
There definitely is a wave feature here, and the phase lines are sloping - in different directions. The amplitude of vertical excursions decreases with altitude. The tropopause is at about 9.5 km, so the wave structure "penetrates" the tropopause, unaffected it seems. At flight altitude the wave amplitude is 198 meters. I estimate that 1.5 cycles of the wave is present. The DC-8 was flying over Spitzbergen, above a strait separating the two main islands (+79.7 latitude, +19.0 longitude). Although this is an "interesting" wave feature, it has too small an amplitude to qualify as a "wave event" for my statistical study. If the amplitude were slightly larger it would meet my arbitrary qualification threshold for a mountain wave (>0.2 km peak-to-peak amplitude, >1.5 cycles).
Figure 5. Event #2. Zoom of another candidate wave feature. Isentropes are 5 K apart.
The second event, at 29.2 ks (8.11 hrs), has a longer wavelength structure,
followed by a brief short spatial structure. It is interesting that
in Fig. 1 there is a noticeable warm feature at high altitude (downward
Figure 6. Same event (#2), just a vertically exagerated IAC.
Fig. 6 is meant to show IAC details where the CTC/IAC shows a warm region
at 8.16 hrs (29.38 ks), above approximately 16 km (geometric). It
is interesting that near flight altitude there is no hint of such a feature
in Fig. 1, nor the detailed IAC figures. Just before it, though,
there's the 29.2 ks structure. The "low isentrope" region at 29.38
ks does begin to appear at a pressure altitude of approximately 15 km.
At this time the DC-8 was flying over an oceanic ice field between Spitzbergen
and the North Pole. There might have been an "opening" with a source
of released heat, but such a heat surce is unlikely to affect the temperature
field ONLY above 15 km. In my opinion, this 29.2 ks high altitude
feature is unreliable, being as it is more than 4 km above the DC-8.
It's altitude displacement is also small, andmay not be "real." At
17 km the displacement is approximately 150 meters, corresponding to a
temperature difference of 1.5 K. The "noise" at this altitude is
Figure 7. Event #3, showing detailed IAC for the putative wave feature at 38 ks. Isentropes 5 K apart are shown.
Event #3 is shown in this figure, where the DC-8 is flying just above the tropopause. An upward shift of the isentropes occurs at about 37.8 ks (10.5 hrs). There is nothing noteworthy in Fig. 1, but my Fig. 2 does show a possible wave feature. The amplitude is 0.2 km, which meets my amplitude criterion, but it consists of only one cycle do does not qualify for my wave study. There definitely is a "disturbance" here, and it probably is associated with Melville Island. The phase lines are sloped to the upper-left, quite dramatically for some features. The troposphere isentropes are more displaced than the stratospehric ones. The CTC/IAC shows
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