bore mission of 4 June

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bore mission of 4 June
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First eventHomestead observations onlyleading
wave _at_ Homestead at 645 Z
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First event
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Note limited surface cooling, for the first bore
event.  Dynamic cooling is superimposed on
radiative cooling, sunset is at 200 Z, sunrise
at 1130 Z The real dynamic cooling occurs 2
hours after the second bore event.
Radiative cooling
7 Z AERI sounding
first bore
another bore??
second bore
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First event
FM-CW 6-8 Z
Three amplitude-ordered waves, the first one the
tallest - this suggests a mature bore system.
However there is one low-amplitude wave ahead,
also seen by MAPR
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this suggests some vertical mixing
Cold front??
First a 2 mb pressure jump associated with bore,
then some waves
2nd event
1st event
ISS1 location at Homestead
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702 Z
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Amplitude-ordered wave train - but first wave
seems smallest?? Anyway, this image is consistent
with FM CW
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second eventleading wave _at_ Homestead at 1050
ZUWKA/WCR data
cold front
second bore
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Cold-frontal passage near 1230 Z ??
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DDC wsr-88d 1704Z
This may or may not be the same event. 90 km in
3h45m implies a speed of 6.7 m/s
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(No Transcript)
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1500 m AGL
1000
1200
1100
FM-CW 10-13 Z
Cold-frontal passage around 1250 Z
Is this real??
1050 first UWKA leg over Homestead
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1050 strong, gusty winds were reported by a
person on the ground at Homestead
1050 first UWKA leg over Homestead
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10 Z
11 Z
considerable cooling 700-910 mb
AERI soundings
inversion suggests calm conditions
12 Z
parent density current??
13 Z
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Height below flight level (m)
June 4 2002
Time (UTC)
Flight level 1850 m AGL
Homestead
WCR nadir antenna reflectivity
Aspect ratio 14
dBZ
the ground
FLIGHT LEVEL DATA ON THE NEXT PAGE
Homestead
Some wave activity ??
WCR echo strength is very weak at night, compared
to the daytime CBL
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SE

• BORE
• The sustained nature of the change, ahead of a
  much more shallow gravity current, suggests that
  this is a bore.
• This flt level (1850 m AGL) seems to penetrate
  the bore the flt level temp behind the bore is
  some 3 K less.
• This suggests that the waves are deeper than what
  FM-CW suggests
• Consistent with AERI, the air is more humid
  behind the bore, with some 4 g/kg more water
  vapor. However the cooling may NOT be consistent
  with AERI.
• The net effect is a higher qe behind the bore,
  about 5 K higher.
• WAVETRAIN
• The covariance of q and T imply that the aircraft
  didnt bob up down in a stratified, undisturbed
  environment, but rather that the aircraft was
  rather level in a wavetrain
• The waves are ranked in amplitude, the first one
  the highest amplitude, and they may be ranked in
  wavelength, the first one the shortest this is
  consistent with FM-CW MAPR
• The vertical drafts have a magnitude of 2 m/s or
  less.
• Assume that this is simultaneous transect. The
  coldest air has seen a history of ascent, so the
  wave must move forwards.
• The pressure variations at this level are mainly
  a response of the aircraft to the vertical motion
  field in which it is embedded, flying from right
  to left. A 1 m/s updraft during 20 sec is 20 m
  ascent or 2 mb hydrostatic pressure decrease.

NW
potential temperature
temperature
Wave propagation
vertical air velocity
static pressure
c w
(u,v)
Homestead
theta-e
mixing ratio
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SE
NW
Flight level 250 m
Wave crest ahead of cold front??
Homestead Where is the trailing wavetrain? It
may be further to the SE - unfortunately this is
the end of this flight leg
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SE
NW
Flight level 160 m
frontal motion
Prefrontal updraft/cooling
wave trofs on the cold-frontal surface?
Cold front
Cold front reaches Homestead 1250, ie 60 min
later over 30 km, ie the frontal speed is 8 m/s
Cold front
Homestead
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VHF radio interference
WCR up-looking
SE
NW
Height above flight level (m)
Time (UTC)
WCR nadir antenna reflectivity
Flight level 160 m AGL
WC zenith antenna reflectivity
Aspect ratio 14
dBZ
Prefrontal updraft/cooling
Cold front
wave trofs on the cold-frontal surface?
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(No Transcript)
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SE
NW
June 4 2002
Height below flight level (m)
Time (UTC)
WCR nadir antenna reflectivity
Flight level 750 m AGL
Aspect ratio 14
dBZ
The wave crests were associated with shallow
lenticular clouds, and cloud droplets may explain
some of the echo. It is not clear what the
continuous fine line is.
cold front below (lt750 m deep)
Homestead
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(No Transcript)
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Conclusion for the 1157-1210 leg I suspect
that this is a gravity wavetrain above the cold
frontal surface. The highest amplitude wave
appears to be just ahead of the sfc cold front,
separated by some 15 km. Perhaps this is the
beginning of a new bore?
SE
NW
Flight level 750 m
wave propagation
another low-amplitude wave ?
Homestead