FLTNOTES.DOC
Flight No. 4 - 16 January 1987
The first flight following the three ferry legs to Darwin was
primarily
exploratory; 1) to overfly a large tropical cyclone and allow the
pilot to
assess the possibility of in-anvil flight and 2) to test the accuracy
of
short-range severe-weather prediction based on the radar display,
storage
and recycling capabilities of the RAPIC's installed at Darwin.
Cyclone Connie, located north of Broome, just off the coast of the
Kimberley Division, was moving slowly toward the southwest but within
the
ER-2 range. The flight passed over several bands, oriented parallel
to the
wind, of active cumulonimbus clouds with turrets that were
overshooting
into the stratosphere. A descent was made into one of these
collapsing
turrets and also the main anvil was penetrated just prior to the
ascent to
flight altitude and the return to Darwin.
Severe weather phenomena, including heavy rain showers and gusty
surface
winds produced by the precipitation-induced downdrafts, were
identified and
tracked with the aid of the radar, with sufficient accuracy to permit
predictions for safe landing at Darwin during the lulls between
storms.
However, during takeoff the ER-2 ascended in clouds and precipitation
which
exposed several instruments to too much water. The excessive water
was
outgassing for more than 2 hours, producing spurious H20 vapor
measurements
for about half the flight.
Flight No. 5 - 18 January 1987
A south-north flight to 30 S was selected both to complete the
latitudinal
survey conducted during the ferry flights and to intercept air
flowing out
of the upper-level circulations produced by Cyclone Connie. A
vertical
descent-ascent profile was made at 30 S to intercept the descending,
anticyclonic trajectories of air leaving Cyclone Connie. The
vertical
profiles of potential temperature and trace gases measured at 30 S
can be
compared to those obtained two days earlier over the cyclone.
Because Cyclone Connie maintained its intensity for several days,
quasi
steady state conditions were sustained, eliminating a critical
dependence
on sampling the same air parcels at the initial and final points.
The
surface map included in this set, 1200 UT, 20 January 1987,
illustrates the
surprising persistence of the vortex even after it moved inland.
That the descent profile at 30 S was well placed to intercept the
outflow
from Connie is evident by the anticyclonically curved stream lines at
100 mb, OOOO UT, 19 January 1987.
Flight No. 6 - 22 January 1987
Cyclone Irma, which formed in the northern Gulf of Carpentaria, is
evident
in the surface map of the 20th, just south of Gove. Flights to this
cyclone, while it was over the Gulf, were precluded by unfavorable
crossrunway surface winds. On the 22nd of January, favorable down-runway
winds
returned, but by this time the cyclone had travelled overland and was
weakening considerably. The cyclone's upper level outflow, with
dense
cirrus, was passing to the south of Darwin so a flight path
perpendicular
to the flow was chosen, i.e., SSW-NNE flights. The flights began at
an
upper tropospheric level and progressively stepped up in altitude to
determine the characteristics of the clouds streaming from the
cyclone, to
determine their tops and their relationship to the water vapor.
Because the flights were close to Darwin, several flight levels could
be
examined.
cirrus
clouds.
They produced a high resolution data set in and above
Flight No. 7 - 23 January 1987
Following the active period dominated by Cyclone Connie to the
southwest of
Darwin and Cyclone Irma to the east and southeast, was a period of
relative
calm with predominately clear skies. Flight 7 was conducted in clear
skies
over the Gulf of Carpentaria. The objective here was to obtain
measurements in a cloud-free environment to test those theories that
depend on mean motions, and especially to test whether sub-visible
cirrus
was, in fact, present.
After traversing the Gulf and on the return, the pilot was asked to
turn
and head toward the southeastern edge of the Gulf to make
measurements in a
cumulonimbus cloud cluster that was forming over the adjacent land.
An
extremely well-developed anvil had formed within the cluster,
surrounded by
anvils more fibrous and irregular in shape. Mechanical difficulties
prevented the pilot from reaching this well-developed anvil but he
did
penetrate cirrus associated with overshooting turrets before
returning to
Darwin.
Note that the clear air flight to the east from Darwin was directly
upstream, to the north of the major anticyclone centered about 15
degrees
farther south. Note also that the anticyclonic circulation extends
over
the entire continent.
Flight No. 8 - 29 January 1987
This flight was designed to provide radiation measurements directly
above
the simultaneous measurements made by the NOAA P3 and the NCAR
Electra.
The active area chosen was over the Joseph Bonaparte Gulf to the
west,
northwest of Darwin. Prior to the rendezvous time, the pilot made a
series
of flight maneuvers for the air motion system calibrations and made
samples
in the vicinity of collapsing turrets. Enroute to the rendezvous
point,
the inertial navigation system failed, so the pilot turned and
returned to
Darwin. This failure would require another cooperative experiment to
be
undertaken before the P3 and Electra departed. Radiation
measurements were
the objective of Flight No. 10, the next coordinated flight mission.
Flight No. 9 - 31 January 1987
A cyclone developing again west of the Kimberlies provided active
cloud
bands in moderately strong maritime westerlies to the north of
Darwin.
Again a NNE-SSW flight path at several levels was selected to
determine the
cloud heights and water vapor distribution for meteorological
conditions
under the influence of a tropical cyclone, but during its
development,
Flight No. 6 was conducted during its dissipation. However, in both
cases
the lower level flows are from the west and the upper level flows are
from
the east.
Flight No. 10 - 2 February 1987
Cyclone Damien was dominating the flow over the entire northern coast
but
we had a commitment to obtain coordinated radiation measurements and
Damien was outside the other aircrafts' range, at least for the
aircraft
based at Gove. An active cumulonimbus cloud band located northeast
of Gove
was selected as the target.
The ER-2 was sent to the designated rendezvous point where detailed
positioning was assigned by aircraft-aircraft communication. While
the
radiation survey was in progress, the inertial navigation system on
the
ER-2 failed again. The ER-2 was on its third flight altitude and the
pilot, Ron Williams, reported that the P3 had just completed its
radiation
flights.
Flight No. 11 - 3 February 1987
Having developed to cyclone intensity, Cyclone Damien was the subject
of
this flight to the southwest of Darwin. Confident of the
extrapolated
position of the large cirrus anvil, I sent the ER-2 to a point along
the
SE edge and then requested a NW traverse of the anvil. Upon
completion of
the traverse, the pilot was requested to turn left, descend and then,
if
conditions were favorable, to make an orthogonal flight to the NE in
the
anvil.
At a specified point, the pilot was requested to ascend and
fly
over what appeared to be a band of convective turrets.
Extremely cold temperatures (-90 C) were encountered at the top of
the
anvil and both the air motion system and the microwave radiometers
indicate that the lapse rate in the anvil was adiabatic. Of
particular
interest is the large concentrations of radon measured in the cirrus.
This
radon emitted over the western Australian continent is advected over
the
ocean into the convective updrafts to the west and southwest of the
cyclonic vortex. An excellent flight with extremely interesting
data, this
flight will merit special consideration.
Flight No. 12 - 8 February 1987
As Cyclone Damien weakened over the eastern Indian Ocean, an
unprecedented
fourth cyclone developed (Cyclone Jason) once again over the northern
Gulf
of Carpentaria. The high resolution inertial navigation system was
installed to determine whether an improved ventilation system would
eliminate the large temperature gradient thought to be responsible
for
prior failure.
The flight was directed straight east of Darwin.
After passing over
the
cirrus cloud shield, a right turn with descent was to be followed by
a
traverse to the north, just skimming the tops of the cirrus. After
completing this traverse, another right turn would lead to a descent
into
the anvil.
During the first right turn and descent, a rising turret apparently
buffeted the ER-2, creating severe turbulence and large amplitude
oscillations of the wings. The pilot increased altitude immediately
and
then made the northward traverse with a series of steps to avoid the
anticipated turbulence.
After the second right turn the INS failed again but the wind
measurements
obtained while it was working provide an excellent and unique
description
of the flow field in the upper portions of a tropical cyclone.
Flight No. 13 - 10 February 1987
In the previous flights, the ER-2 was sent on horizontal flight legs,
either to a specified point where a vertical descent-ascent profile
was
obtained, or an anvil penetration was attempted, or where the flight
direction was reversed at a new altitude. On Flight 13. a completely
different approach was taken to provide more extensive altitude
coverage.
By flying a sinusoidal path up, down, up and down against the upper
level
flow and then repeating the up, down, up, down path on the return
(but 180
degrees out of phase). a criss-cross pattern was obtained.
Several scientists had proposed this type of flight but the pilot,
Ron
Williams, said "Never again". As the surface chart indicated, the
first
ascent took the ER-2 over Cyclone Jason where the extremely cold
temperatures were sustained long enough to freeze the controls,
forcing Ron
to recover manual control.
Although the low resolution INS was used, the accuracy of the
horizontal
winds should provide a reliable description of the wind field for
direct
comparison with the radiosonde winds.
Flight No. 14 - 12 February 1987
The last flight from Darwin, prior to deployment to Moffett Field,
was made
directly towards the east. Cyclone Jason was still active over the
Gulf of
Carpentaria - to the south of the flight path. Cyclonically curved
bands
of cumulonimbus clouds - to the north of the flight path - converged
toward
the cyclone over the eastern Gulf of Carpentaria. The pilot, James
Barrilleaux, via radio communications requested permission to divert
slightly from the flight path to investigate these large cumulonimbus
clouds. Permission was granted and Jim made several exploratory
descent
and ascent profiles, which as the tracer data indicates, include
cirrus
penetrations, moist adiabatic lapse rates and measurable amounts of
radon.
Although these cumulonimbus clouds formed over the Arafara Sea, in
maritime
air, they definitely contain radon from a continental surface source.
On the return flight the pilot was instructed to fly over Melville
and
Bathurst Islands where "Hector" was redeveloping. Hector is a
persistent
cumulonimbus cloud during transition to the summer monsoon, i.e., it
forms
over the islands every afternoon. Only a small version of Hector was
noted
due to the strong low-level winds that carried the storms away from
the
islands.