15 November 1995
Non IOP day
1. Convection over the Tiwi islands was very suppressed today
following the early morning squall line. This caused overcast conditions during the
morning and hindered development of the sea breeze circulations and Hector development.
The suppressed conditions were more marked than yesterday when late convection did develop
over the Tiwi islands.
2. The synoptic conditions are broadly similar to yesterday with the
added factor of a closed mesoscale circulation about 200km to the south-south west of
Darwin. This may have indirectly contributed to the intensity of the early morning
storms/squall lines over Darwin and Tiwi Islands.
3. A cloud line in the Gulf of Carpentaria travelled westwards at
about 10 m/s. It activated an atypical SW-NE line of deep convection over the Gulf,
perhaps initiated by convergence/intersection of an extensive N-S oriented outflow
boundary moving eastward from overnight convection over the ToP End. This gust front is
clearly evident in the high resolution satellite images and extends the full length of the
west coast of the Gulf.
4. All things being considered, it is expected that there will be
another episode of early morning squall/thunderstorms over Darwin on 16/11. This may lead
to a partly suppressed Hector on 16/11.
16 November 1995
Non IOP day
1. Another cloud line developed over the Gulf and is travelling
westward. Convection over Gulf largely suppressed. Note that the deep convection that
develped yesterday seems not to have influenced the sequence of events leading to the
early morning squalls over Darwin and Tiwi islands. The large scale conditions are similar
to yesterday except there is more cloud and moisture inland of the Top End. Also the
mesoscale circulation within the shallow low (1004 mb) SSE of Darwin is no longer evident.
Some suggestion that the York Peninsula may be influenced by a synoptic change east of
Queensland - leading possibly to increased easterlies (that may affect the sea breeze
development). Visibility much better compared to yesterday (drying effect of morning
squall line?)
2. The affect of cloud lines developing subsequent to the sea breeze
over York Peninsula (collision of west and east coast?) circulations is interesting ---
this sequence of events needs to be quantified (e.g., the intitiation of
convection/enhancement of see breeze at west coast of Gulf).
3. A multicellular Hector developed over the sea breeze fronts on
Melville and Bathurst islands. The sea breeze fronts can be clearly seen on the visible
satellite channels even at degraded (2.5km) resolution. Note that 1.25 km resolution
visible images are being archived by LeMarshall at BoM -- these will be very useful in the
data analysis (e.g., effect of colliding lines/single lines; boundary layer wind velocity
on lines on convection intitiation.) Today, individual storms developed along the
individual sea breeze fronts and subsequently merged.
20 November 1995
IOP #1
Objective: Boundary layer morphology, sea breeze transition and
lifecycle of convective dynamics.
1. There were weak NW to SW winds over the Tiwi Islands today
maintained by a heat low over north-central Australia and a weak ridge over the Indonesia
archipelago. The BoM LASP gives zero ascent to weak descent over the Tiwi islands as a
result. This would delay the onset of Hector if not suppress its development.
2. From the satellite perspective, the sea breeze-induced boundary
layer cloud first developed in a horseshoe shaped configuration along the south, east and
north coasts of Melville Island. A weak convective outbreak on Bathurst failed to build.
3. Flinders Cessna operations were first focused on SE Melville
coast sea breeze beginning about 1125. At 1200 the aircraft was directed to sample the sea
breeze along the SW Melville coast with legs spanning the 100m terrain to the north. At
1300 the Cessna began sampling the south sea breeze on Bathurst. Each sea breeze was
sampled from very low levels (60m agl) up to approximately 600 m msl. None of the breezes
exhibited particularly sharp thermal or kinematic discontinuities, but thermal and wind
differences were generally consistent with a density current character of up to 1%
buoyancy contrast. Sometimes breeze fronts were diffuse with up to 10 km transition zones.
Growth of the island PBL was strongly evident from south to north transects, indicative of
increassed residence time in a predominently SW flow. The Cessna ended its mission at 1345
and returned to Darwin.
4. Early radar echoes developed near southern and eastern sea breeze
fronts. Doppler winds were light W/NW in the lowest 1 km, reversing to light easterly
winds of 3 m/s in a relatively thin layer above. Sustained deep convection developed near
the east coast of Melville sea breeze front after 1000 LT. After 1100 echoes formed over
the eastern most 100m terrain on Melville, north of the southern breeze. After 1300 it
became evident that multicellular structure at the east end of Melville had developed with
preference for new development on the west edge of echo area. Obvious cold pool
propagation characteristics developed soon thereafter with a westward propagating echo
mass slowly marching accross Melville, and exhibiting discrete propagation modes up to 15
km in advance of mature deep convection around 1500. Propagation speed increased and the
gustfront passed over Maxwell Creek shortly after 1600 where a RASS/profiler dataset was
obtained By 1700 the storms were well into dissipation and operations were terminated
before 1730.
4. The prognosis for 11/21 is for the high to wane and to slip
southward. The LASP forecast has weak ascent (positive vorticity) at 500mb. The surface
north westerlies are to be replaced by low-level S.E. flow and the 200mb flow forecasted
to be NW. Tropospheric shear anticipated about 25m/sec. With this situation the
anticipation was that tomorrow would be quite favourable for Hector development. IOP #2
was therefore proposed.
20 November 1995
IOP #1 (Additional Summary)
Objectives: Boundary Layer Morphological study with transition to
sea breeze studies, convective dynamics.
Equipment Status:
Cloud Radar ? Lidar ? PSU/ARM Radiometers ? S Band Profiler UP GP
Profiler UP CSIRO NFOV Sensor ? Lightning Interferometer ? All Sky Camera ? Piker
Profiler/RASS Day UP Aerosonde DOWN C-POL UP Maxwells Profiler/RASS UP Maxwells Soundings
UP FIAMS Cessna UP
Synoptic Situation: A low level trough over the southern Queensland
with extensive southerly flow extending up through the NT and across the Tiwi Islands. At
middle levels, 700 mb southerly flow turns south-westerly by 500 mb as part of a trough
across northern Australia with W to NW flow near 200 mb.
GMS satellite imagery at 0930 CST indicated an undisturbed
environment over the Top End although narrow cloud bands in the vicinity of the islands
were apparent. The FIAMS Cessna was deployed at 0945 CST for an island scale PBL
morphology flight with the following way points (C-POL radar relative); 250/50,325/68,
206/14,003/55,119/48,040/80,063/65 and 286/35.
At 1000 CST, radar data indicated the sea breeze was best developed
along the southern coast of Melville Is. and the first precipitation event occurred in
that region. The SBF continued to move slowly inland over SE Melville Is. so the Cessna
was diverted to this zone from way point 5 with the purpose of undertaking sea breeze map
flights. Flight levels were 50, 300, 600 and cloud base. By 1100 CST precipitation was
evident at the extreme eastern coast of Melville Is. By 1230 CST it had developed into a
"horse shoe" area of precipitation concentrated along the eastern coast of
Melville. At this time a sea breeze front was detected along south coast of Bathurst and
precipitation developed along Cape Van Diemen. The Cessna was routed to undertake a final
SBM flight along the south coast of Bathurst Is. at 1250 CST. Way points were 290/15,
300/25.
At 1330 CST the most significant development was still within the
complex detected along the extreme eastern flank of Melville Is. A multicellular complex
moving west with a strong cold pool was evident. By 1430 CST the gust front from this
system was moving across Melville Is. at 40 km h-1 interacting with an east-west aligned
SBF on the northern coast. The gust front extending south from the northern coast to just
north of Pickerataramoor, was ~15-20 km ahead of the main storm and by 1600 CST was near
to crossing the Maxwells Ck area. No new precipitation was developing along the southern
flank of the gust front. Major precipitation development was on the northern coast in the
area of the interaction with the north coast SBF. Cell tops were 13-15 km deep by 1630
CST.
By 1700 CST the major area of convection was still along the
northern coast and it now extended north of the coast. Generally the system was in a stage
of dissipation but continued to move westward with its associated precipitation developing
over the north east coast of Bathurst Is. The gust front was still moving over the western
half of Melville Is. trailing well south of the major area of storm activity. By 1730 CST
the main storm persisted as a narrow north-south aligned area of convection moving
westward but basically over the water north of Bathurst Is. Weak stratiform precipitation
trailed to the west along the northern coast of Melville.
Initial radar operations consisted of boundary layer surveillance
scans from 0900-1500 CST. From 1455- 1535 CST 120 degree sector convective dynamic scans
were employed interspersed with a one tilt surveillance scan. Polarimetric sector scans
were used every 15 minutes. From 1535 CST onwards the scan strategy employed a one tilt
surveillance scan, followed by a 120 degree polarimetric sector scan and then a four tilt
PBL surveillance scan with an overall 8 minute repeat cycle.
Summary: The development of the major gust front which propagated
well ahead of the storm complex was a major feature for the day. Most significant
convection occurred on the eastern and northern coasts of Melville which is consist with
the environmental southerly flow. Initial cells were triggered on the extreme eastern
coast of Melville Is. and this complex swept across both islands triggering new cells. A
weak north south aligned system developed at the mature stage with evidence for discrete
cell propagation.
21 November 1995
Non IOP day
Objective: Convective Lifecycle
The IOP was called off due to a fuel leak in the Cessna.
No access to weather maps but the field log suggests the presence of
postive vorticity and large scale descent. The Maxwell Creek soundings showed weak
westerly surface winds (1-3 m/s), a southeasterly jet of about 8 m/s between 800 and 770
mb and strong west-northwesterly flow (~10 m/s) above 450 mb.
From the beginning of radar operations (~2300 UTC 951120) to about
0200 UTC, the C-pol radar examined development of the convective boundary layer. The first
convective cells developed on Bathurst Island between 0200 and 0300 UTC. These cells
remained relatively small and were short lived. Convection developed on the east-central
part of Melville Island between 0300 and 0500 UTC. Some cells appeared to form on the
northeast edge of the higher terrain of the area. During this time period, the north coast
sea-breeze front began to move southward. Movement of the south coast sea-breeze front
northward was unclear; surface data may help in this determination. Between 0500 and 0600
UTC, explosive, east-west oriented, convective development occurred along the north coast
sea-breeze front. Gust fronts from the pre-existing convective activity to the southeast
may have partially contributed to the convective initiation. After 0600 UTC, the east end
of the line began to re-orient north-south. It then propagated rapidly to the northwest.
The radar scanning consisted of boundary layer PPI's from
951120/2300 to 951121/0200 UTC, PPI's interspersed with polarimetric and non-polarimetric
SECTors (120 and 180 degrees) covering both Bathurst and Melville islands from 0200 to
0400 UTC, and PPI's interspersed with polarimetric SECTors (120 degrees) that focused on
the Melville Island convection from 0400 to 0730 UTC. All of the PPI scans were
non-polarimetric. The radar was shut down at 0730 UTC due to an oil leak in the radar
pedestal.
Status summary:
Profiler/RASS (900Mhz Pickertaramoor) - winds up, RASS down
Profiler/RASS (900Mhz Maxwells Creek) - up Profiler (Garden Point) - ??????? Aerosonde -
up C-POL - up and down shortly Investigate oil leak at 0730 UTC; radar back up at 08:15
UTC Cessna - up and then down Fuel leak Kite - up AWS - up (all stations??????) Cloud
radar - up (94GHz and 37 Ghz) Lidar - up Franklin - moving on station today Videosondes -
up (when were the launches?????) Rawinsonde - up Sondes launched at: 951120/15:28 UTC
951120/21:59 UTC 951121/00:06 UTC
21 November 1995
(Additional Summary)
Objective: Lifecycle of convection. Purpose: To determine the extent
to which early precipitating convection is sea breeze related. If not related to sea
breeze, to determine depenencies on PBL depth and island topography. After development of
deep convection, to document the mesoscale aspects of convective reorganization and
dissipation.
Radar operations began approximately 0900 LT Flinders Cessna takeoff
scheduled 1030 LT Anticipated Cessna landing 1430 LT
Initial Cessna pattern is 100m altitude flight to 30m km north of
Melville and a sounding to height of max easterly winds or 700 mb, whatever is lower.
1. Early morning (0700 LT): low-level winds at Darwin were light SE
with max of about 15 kt at about 700mb and constant in direction to surface (Darwin
profiler). The upper level winds are westerly, again quite constant in direction. Surface
to 700 mb shear about 10 kt. Tiwi low level winds were SW and increased in speed
throughout the day while maintaining direction. A shallow layer of easterlies was located
above 1.2 km with reversal to westerlies and attendent shear above.
2. The IOP was cancelled at 1114 LT due to a fuel leak on the
Cessna. Soundings ceased after 0930 LT. Radar and other measurements continued. Radar data
were acquired, for the most part, in the convective life cycle mode once deep convection
developed.
3. A Hector developed (slowly) and was mainly limited to Melville
island. It was clearly affected by the upper tropospheric shear. Positive vorticity
(descent) was also present. This combination probably caused the slow development and the
limited extent.
4. "Bookend" radar echoes initially developed over extreme
east Melville and extreme west Bathurst islands. Sustained convection with evolving
organization was limited to Melville. Small "channel breeze" cells were
particularly prominent over east Bathurst. After noon, near the east Melville sea breeze
and the eastern elevated terrain, several cells developed and evolved in roughly a
horseshoe pattern. Beginning about 1500LT a zonal line, somewhat inland from the N. coast
of Melville, developed in response to a sharpening sea breeze that was in opposition to
the mean flow with a southerly component.
5. The eastern Melville multicell complex propagated WNWand
intersected with the north coast zonal line, where there was greater intensity to the
convection. At about 1530 the north coast line of cells filled and strongly intensified,
evidently initated by a collision of the N. coast sea breeze with a thin line of
convergence that propagated northward from the southern escarpment. This "surge"
feature is of unknown origin.
6. After 1545 a "dominent cell" of very large horizontal
proportions and 20 km height developed 50 km NE of the radar in the middle of the north
coast line. This cell produced copious rainfall a huge anvil, and a vigorous gust front
that propagated considerably against the ambient SW flow. Major convection ceased by 1700
as the dissipating cells moved NW over the Timor Sea.
7. The prognosis is for the trough located in South N.T. to move
north. This will tend to cause negative vorticity and ascent conducive to the development
of an active Hector. Little change expected in the upper level westerlies or the light
winds at the surface. This all suggests moving forward with IOP #3 on Wednesday despite
the Cessna being operational only for a period of 3hrs (or 4 hours with slow airspeed) due
to reduced fuel capacity.
22 November 1995
IOP #2
1. Today's Plan
Objective: To determine the local conditions associated with early development of
sustained precipitating convection. This includes island PBL development, sea breezes and
topographical effects.
Expected storms: westward travelling squall system at approx 1500 LT
A. C-POL Radar
Convective lifecycle scans
a. PBL and shallow convection
b. Polarmetric scans of deep convection
B. Flinders Cessna
a. N-S transect of Melville at 200m altitude b. E-W transect of Melville at 200m altitude
c. Radar guidance thereafter
Aircraft objective amended to focus on the origin of convection (i.e., is it due to
forcing by sea breeze or to other forcing mechanisms).
C. Aerosonde (first mission)
Three south sea breeze options provided to aerosonde with preference for SE Melville
breeze. S.W. Melville transects at 200m were selected as follows:
NW point -- 11deg 42min S, 131deg 3min E SE point -- 11deg 53min S, 131deg 9min E
D. Soundings
a. 2 hourly radiosondes throughout
b. Continual profiling
E. Videosonde
As opportunities permit
F. M/V Franklin
E-W transects of Timor Sea/Beagle Gulf to south of Bathurst Island
2. Platform status summary:
Profiler (920Mhz Pickertaramoor) - up Profiler (920Mhz Maxwells
Creek) - up Profiler (10cm S-band Garden Pt) - up RASS (Maxwells Creek) - up RASS
(Pickertaramoor) - winds only (awaiting parts) Aerosonde - up (launched c. 1100 lt)
Ligntning Interferometer - up All-sky camera - up C-POL - up Flinders Cessna - up (takeoff
c. 1100 LT) CSIRO Radiometer - down (out of liquid nitrogen) PSU/ARM Radiometers (2) - up
Kite - up AWS - up (some have problems) Cloud radar - up (94Ghz and 37Ghz) Lidar - up
Franklin - up Videosondes - up Rawinsonde - up (No 0730 Sonde - not writing to disk -
first launch 10:30 LT)
3. Note: Starting today, John LeMarshall is calculating the
satellite winds from the 1.25 km resolution visible images. This will start from 0000Z and
continue at hourly intervals through to sunset. Motion of small clouds, sea breeze
convergence clouds, and deep convection on the scale of the island and larger will be
derived. These data will: 1) complement the analysis of detailed measurements by
individual platforms; 2) provide `warm start' initial conditions for cloud resolving
models with a caveat that the lateral boundary conditions will need to be handled
carefully); and 3) data assimilation/verification data sets for the BoM Limited Area
Prediction System (LAPS) presently being run over a region including the MCTEX domain.
4. Weather Briefing: Only a small deviation from yesterday's
conditions except that the low-level shear is a little stronger. CAPE is 3100 J/kg much
the same as yesterday. This puts the BM forecast convective regime in the multi-cellular
squall category (yesterday was in the MCC-like). The changes in the large-scale flow shows
a developing high or ridge in C. Australia region. The low-level easterlies are therefore
expected to develop in over the Darwin locale over the next few days. The upper-level
westerlies have decreased from 40kt to 30kt. This suggests more squall-like conditions in
the near future.
The LAPS forecast is for a change from the westerly low-level winds
to easterlieswithin the next 24 hrs. Also a change to mean upward motion (negative omega
fields). The omega fields are probably subject to spin-up at least in the first six hours.
Note: more hazy conditions over the Timor Sea quite different from
the relatively clear, drier conditions of late -- more like last week -- large Hectors?
5. Operations
Despite apparently similar conditions, deep convection started much
earlier than yesterday along the usual promontories but some of the convection had an
oceanic origin (possibly land breeze) that advected to the island from the Beagle Gulf in
the prevailing SW flow. The Flinders Cessna sampled PBL properties near suspected CI
activity over central Melville, south of a developing north coast sea breeze. On station
time was limited to about 2 hours as the aircraft was released by 1300. As island forcing
became more prominent in early afternoon, the pattern of echoes at 1330 became quite
similar to the 1500 period yesterday. Healthy and moderately deep cells developed near the
Melville north coast after interacting with cells that had formed a weak squall from
eastern Melville. The eastern Melville seabreeze may have had a role in forcing this
activity and interaction with a cloud line from Cape Don may also have been a factor. Echo
movement was generally toward the west and north.
Today's case lacked the "dominent cell" development
characteristic of yesterday and major convection was in advanced dissipation by 1500.
Maxwell Creek Sounding (10am) mb z T Td v 1000 111 30.5 22.9 252/2.5
925 804 23.9 22.3 238/2.8 850 1540 20.9 12.6 140/3.6 700 3188 9.1 3.3 128/6.9 500 5907
-3.9 -23.6 234/7.3 400 7631 -14.6 -32.6 294/9.3 300 9749 -29.2 -46.2 323/10.9 250 11024
-39.4 -50.9 322/10.6 200 12512 -51.6 -60.8 322/11.6 150 14310 -67.9 -79.1 322/13.5 100
16647 -83.4 -97.2 021/8.3 70 18658 -80.3 -94.6 155/5.5 50 20651 -65.2 -84.4 140/6.2
Cessna operations detail
1100LT: north -south transect followed by 2 legs at 150 m and about 800 m near cloud base
167 deg @42 km to 010 deg @ 58 km. Mapping of sea breeze structure.
1200: Begin convective initiation flights from way points 045 deg @
25 km and 026 deg @ 42 km. Rectanglar flight paths mapping out 15 km transects parallel
and perpendicular to the way points. Heights at 150 m and 800m. Jorg's comment was
interesting structures being observed, although this area turned out to be to the west of
the main convective development over Melville and to the NE of the large cells over
Bathurst Is. 1300: Return to base.
Aerosonde in the air from 1200 LT doing NS transects from 045 deg @
30 km to 150 deg @25 km. Map island convegence.
Misc.
1100 LT THick cirrus layer over Garden Point seen by profilers etc,
from 11 to 14 km heights. Sat pics show it being advected by upper level NW'ly from
equatorial region.
1300 Darwin radar suggest some interaction between stratiform
remains of the line of cells that originated around Cape Don, but this may be simple
advection? This goes against upper level w'ly component. Also Melville complex showing
signs of re-orienting and looking like a squall line propagating westwards (towards
un-modified air?), while a complex over Bathurst is building eastwards (low level westerly
steering?)
23 November 1995
IOP #3
Northwesterly flow over the islands today. Easterlies building with
time (forecast). Easterlies are weak though. Maxwell Creeks sonde shows only 2-8 m/s from
850-500 mb. Yesterday the flow was southwesterly so we will see what develops in today's
different flow scenario.
1020 Cessna about to launch. Convection developing on south end of
Melville. Aerosonde is currently down with a radio problem.
1030 Maxwell's Creek 0730 sonde arrived. Maxwell's report all
instruments operational with exception of kite. It is not flying today. They had a problem
with 0930 sounding and are launching a second sonde as soon as possible.
1040 OTD overpasses today. Passed times to the radar. Will try to
gather data in these overpasses if possible.
1100 No comms with Cessna since they took off which was at least 30
minutes ago. Convection over Melville but not very impressive yet. Cirrus over island from
local convection may be interfering with heating. Cirrus not very extensive though.
1110 Cessna reports at the waypoint just east of Apsley Strait. Will
be at next waypoint to east in 20 minutes.
1120 Aersonde comms problem appears fixed and expect to lauch soon
(4-5 minutes).
1140 New waypoints for Cessna for sea breeze pattern. 064/120;
064/86. Will pass to Jorg as soon as he reestablishes contact with us. Aerosonde will work
SE coast of Melville and Cessna to work east coast of island. Cessna will not do 3000 m
leg on this run. Will do 50, 300 and 1500 meter legs.
1145 Contacted Jorg and he is beginning the sea breeze monitoring as
planned. Jorg reportsstrong sea breeze and new vigorous convection beginning to develop.
Cessna to take about 30mins to complete this pattern. Cessna will do top leg at 1000 m to
stay just below cloud base.
1200 Jorg just finished doing the 1000 m run and will step down to
do the 2 lower legs. Giving them next set of waypoints which are 060/87 and 041/47,
023/60. This will work seabreeze on north coast. Thunderstorm over the water here at
Darwin.
1215 Aerosonde to launch in 20 minutes.
1230 New waypoints given to Jorg. Cessna can do this seabreeze
mission and will then have to return to Darwin. Revised launch time for Aerosonde is now
1300.
1300 Radar revises Cessna pattern and we can't communicate with them
since they are down on the deck. Looks like they will have to go with previous plan. They
are about out of research time anyway.
1315 Cessna heading to Darwin now as they have reached max duration.
They will refuel and attempt to restart engines. Will call in with a status as soon as
possible. They were not able to perform the revised monitoring due to no contact. This was
not a problem with the Cessna but rather the radar asked for the revision after the Cessna
had descended to low levels. Over all the aircraft comms and coordination has worked out
real good today.
Equipment Status;
Cloud Radar UP Lidar UP PSU/ARM Radiometers UP S band Profiler UP GP
Profiler UP CSIRO NFOV Sensor Down (lack of liquid N2) Lightning Interferometer UP All Sky
Camera UP Piker Profiler/RASS UP Aerosonde DOWN C-POL UP Maxwells Profiler/RASS UP
Maxwells Soundings UP FIAMS Cessna UP
Synoptic Situation: At low-levels weak southerly flow persisted over
the islands. This low-level southerly flow extended well north of Australia converging
with equatorial westerly flow west of New Guinea. The southerly flow persisted to near 700
mb as part of a major anticyclone located south west of the Tiwi islands. At 500 mb the
flow over the islands was generally westerly to south westerly, part of a major westerly
stream in the 10- 15 S latitude belt. Northerly westerly flow persisted near 200 mb ahead
of a major subtropical trough extending to near 8 S at 120 E. The entrance to the
subtropical jet at 200 mb was located some 6 degrees south of the Tiwi islands.
Early radar data at 0800 CST indicated several cells along the north
coast of Melville Is. and on the eastern coast of Cape Van Diemen. The satellite imagery
indicated two NW-SE oriented cloud bands extending across Cape Van Diemen and central
Melville Is. at this time. By 0930 CST a short-lived cell developed along the west coast
of Bathurst Is. but dissipated by 1000 CST leaving the islands precipitation free. These
early cells were apparently associated with the forcing of larger scale bands. Satellite
imagery at 0930 CST indicated a generally cloud free environment in the vicinity of the
islands with the exception of the above shallow precipitation and some remanant cirrus.
By 1000 CST weak clear air "measles echoes" were evident
with weak SBF signatures along the southern coasts of Bathurst and Melville Islands with
some PBL rolls evident in the centre of the islands. The Cessna was deployed with the
following way points for an east-west transect across both islands starting with the
initial coastal crossing over the SB zone on the south coast of Bathurst Is. Way points
were as follows: 234/37 ,291/57, 355/23 and 064/115. This took the Cessna across the
centre of both islands from west to east. RHI scans were taken along the aircraft leg at
1120 CST. At the cessation of this flight the Cessna commenced a SBM on the eastern coast
of Melville Is. Way points were 064/120 and 064/86. The 1030 CST sounding from Maxwells Ck
indicated low-level westerly flow(3-4 ms-1), 1-2 ms-1 southerlies at 850 mb turning to ~ 7
ms-1 easterlies at 700 mb
First precipitation cells were detected by 1130 CST along the north
eastern coast of Melville Is. in the area of the Cessna SBM flight. At about this time
congestus echoes were evident on C-POL along the southern coast of Bathurst Is. persisting
for several hours. By 1230 CST major cell development was still along at the extreme
north, south and eastern coasts of Melville Is. The Cessna was deployed with revised way
points of 049/43, -25/56 for a SBM in this region. A SBF was evident along the north coast
of Melville downstream of the main convection with some evidence for HCR's aligned NW to
SE intersecting the SBF.
By 1300 CST the cells at the eastern coast of Melville Is. had
formed a north-south oriented line propagating to the west. Cell tops were near 13 km.
Congestus and measles type" echoes were detected across the centre of Bathurst and
Melville Islands. At times cloud street organisation was evident in these echoes. At 1330
CST, a convergence zone was evident in the mesonet data extending across the centre of
both islands in the region of congestus development. By 1400 CST as series of
precipitating cells were evident in this region although they only persisted for ~ 30
minutes. Subsequent cell development tended to occur more towards the northern coast of
Melville Is. aligned east to west. From 1430 CST to 1700 CST explosive development
occurred in this region as the eastern storm complex swept along the north coast of
Melville Is. By 1500 CST, 16-20 km deep storm tops were detected in this region. Maximum
reflectivities observed were ~ 58.5 dBZ with some evidence for rotating updrafts at 1535
CST. By 1600 CST two dominant storms had developed along the northern coast with visual
observations indicating significant amounts of ice falling from the anvil possibly being
entrained into the updrafts.
By 1730 CST the two systems had developed significant north-south
alignment and extended some 50 km north of Melville Is. Very little stratiform echo was
evident on the lower tilts. By 1800 CST the system was in a state of decay with
dissipating cells extending from the centre of Melville Is. to some 70 km north of
Melville Is. An extensive anvil from Hector extended to the SE(across Darwin) at upper
levels.
Radar scans consisted initially of PBL surveillance scans from 0900
-1500 CST. From 1500 CST 120 degree polarimetric sector scans interspersed with
surveillance scans were employed. At 1430 CST a 360 degree polarimetric volume scans was
undertaken to coincide with an OTD satellite overpass.
Summary: This day was another case of initial development occurring
along the eastern coast of Melville Is. On this day the initiation region was mapped by
the FIAMS Cessna. Significant development occurred as this storm complex swept along the
northern coast SBF. The day was free of external forcing factors. Weak early morning
coastal cells were detected possibly as a result of land breeze interactions with the
environmental flow.
24 November 1995
Non IOP day
Non-IOP day, with David Kingsmill running convective lifecycle obs
all day. Good Hector on central to north coast, developed squall line characteristics.
Good gust front at Maxwells at around 17:15 LT.
Some problems with MC profiler in evening, fixed morning of 25/11.
25 November 1995
IOP #4
Radar Operations:
Sea breeze mapping in morning with convective lifecycle as convection develops.
Aircraft Operations:
Cessna Flux operations. A.M. Fly 1 circuits past Franklin,Apsley strait, Maxwells,
Pickertaramoor and eastern Melville, followed by SB mapping at south-eastern end and flux
obs at Franklin. Return and refuel with aim to a repeat circuit in post storm conditions.
No repeat mission.
Cessna operations
9:20 takeoff 9:45 Franklin obs begin 10:08 Mouth of Apsley strait
after Franklin Obs 11:10 Approaching Picker flux run, 11:30 Completing Picker 12:30 Flux
obs over Franklin 1305. Cessna on the ground.
Sea breeze flight south from Picker tower, saw distinct sea breeze
5-6 kn and sig. temp humidity contrast across front.
Aerosonde: down
Winds, early lowlevel NW'ly, MC profiler obs showin low levels
changing to NE'ly. Anticipate development on southern side of the islands.
10:30 LT Shear parallel rolls visible on radar with some Cu
development on rolls, a sea breeze fine line visible.
1130LT Some development to the west of the radar on Bathurst island, still rolls visible
to the east of the radar. High res at pic confirms sea breeze penetration and horizontal
rolls visible. 1230 LT line of storms on SB front from easterm Melville to Condor Point
14:15 N-S arc with bow over high country. 60 dBz echo east of radar. Extensive gust front
with redevlopment on it. Possibility of interaction with northern sea breeze front. RHI
showed top around 16 km, but reflectivity max confined below FZL.
Steve R. reported low lightning rates consistent with this. Suggests
60 dBz from warm rain processes. 16:30 Storm beginning to dissipate. Peak reflectivities
order of 30-40 dBz, extensive trailing stratiform. Gust front continuing to propagate?
Equipments Status
Maxwell's Creek: All operational except kite (kite is expected to be
up on the next 2 days). Garden Point: All operational Picker: All operational Nguiu: Radar
OK AWS Network: Bath out (to be repaired Mon., 27th)
Misc.
Some evidence of upper level drying in Darwin and Gove soundings.
Otherwise conditions persisting pretty much. Some northerly cross-equatorial flow thru'
Indonesia - not good news.
26 November 1995
IOP #5
Objective: Sea-breeze mapping, convective initiation, convective
dynamics
No access to weather maps. The Maxwell Creek soundings showed
northeasterly flow of 2-4 m/s in the boundary layer, an easterly jet of 10-12 m/s at
750-790 mb, 3-5 m/s northerly winds at about 500 mb turning to 7-9 m/s westerly winds at
about 400 mb. Low level air was relatively dry with humidities of about 50%.
The Cessna took off from Darwin at about 0100 UTC. Mapping of the
sea-breeze on the southeast end of Melville Island started at about 0130 UTC and lasted
for approximately one hour. Sea-breeze mapping on the southwest end of Melville Island
started at about 0230 UTC and lasted for approximately 2 hours. The Cessna returned to
Darwin at about 0500 UTC.
Sea-breeze fronts along the west coast of Bathurst Island and the
south coasts of Bathurst and Melville islands were especially apparent from the C-pol
radar data. A sea-breeze front on the north coasts of the islands was not clearly visible
in the radar data but an entry in the field log suggests that it existed. It's unclear
what this observation was based upon; possibly satellite data or a visual. Loosely
organized horizontal convective rolls were also observed with C-pol. At 0130 UTC the
sea-breeze fronts on the south and west coasts started to move inland. A shallow cumulus
field began developing over the center of Melville Island at about 0500 UTC. Convective
cells developed in an east-west line along the south coast sea-breeze front at about 0530
UTC. At this time, a small area of convection also developed at the east end of the line
along a north-south oriented discontinuity; possibly the east coast sea-breeze front or an
enhanced horizontal convective roll. Convection began developing on the west coast
sea-breeze front at about 0600 UTC. Outflows from the pre-existing convection to the east
may have partially contributed to the intiation. These cells developed a linear structure
with a northwest-southeast orientation and propagated to the west-southwest.
The radar scanning consisted of boundary layer PPI's interspersed
with polarimetric RHI's from 951125/2100 to 951126/0530 UTC, island polarimetric SECTors
(230 degrees) interspersed with polarimetric RHI's from 0530 to 0600 UTC, polarimetric and
non-polarimetric SECTors (120 degrees) from 0600-0700 UTC, polarimetric SECTors (180
degrees) interspersed with PPI's from 0700 to 0800 UTC, and polarimetric SECTors (120
degrees) interspersed with PPI's from 0800 to 0915 UTC. All of the PPI scans were
non-polarimetric.
Status summary:
Profiler/RASS (900Mhz Pickertaramoor) - winds down, RASS up
Profiler/RASS (900Mhz Maxwells Creek) - up Profiler (Garden Point) - up Aerosonde -
testing in Picker area only C-POL - up Cessna - up Kite - up AWS - up (all stations??????)
Cloud radar - up Lidar - up Franklin - operating in Northern part of observing area
Videosondes - up (when were the launches?????) Rawinsonde - up Sondes launched at:
951125/22:08 UTC 951126/00:03 UTC 951126/02:05 UTC 951126/04:22 UTC
26 November 1995 (Additional Summary)
Radar: Initiation/convective dynamics
Cessna: sea breeze, convective initiation
Maxwell's Ck- all operational
Snake Bay: kite is up Garden Point: all up, Picker: Profiler/RASS
only R/V Franklin operating northern part of obs area. Aerosonde: testing in Picker area
only
Cessna Flight:
10:30 Take off 10:56 Sea breeze mapping (098/57 and 069/45 with
extension off-shore. - SE end of Melville- likely initiation area. Timing approx 25 min
for perp legs and 15 min for parallel legs. On shore flow around 10 kn, and weak easterly
about 2 kn on land side. 12:00 Sea breeze mapping 058/29km, 135/23 km. 12:50 zig-zag legs
13:10 repeat the legs between way points. Return around 14:20.
Obs:
Low level easterlies with max of around 10 m/s at 2.5 km extending
up past 700 hPa. Howvere ther has been noticable drying around 925 hPa in the 07:30
sounding. Upper level westerlies weakened to around 8 m/s Sea breeze line clear on
northern coast, south coast weaker. 11:30 Radar reports: Sea breeze front echoes on s
coast, especially SE, weak loosly organised convective rolls 9:30 sounding shows dew
points
27 November 1995
Non IOP day
Nominated as IOP but cancelled because of dry soundings. Post
sounding low levels moistened and this turned out to be a good case. Performed rainfall
mapping. Observed strong echoes from horizontal rolls and possible sea breeze - roll
interaction early. Storms formed along centre of the islands alligned E-W. Major system
just w of Maxwells, formed an electrically active squall line and propagated well over the
water. Other cells lit up behind,with closer development inhibited by anvil and cold pool
from squall. Good rains over D-scale, Takahashi lauched 2 sondes. Profiler saw interesting
echo structure with 40 dBz cell extending to about 8 km with a 2 km gap and 10-14 km
showing the anvil (guess who wrote this?).
28 November 1995
IOP #6
Convective dynamics /initiation
Equipment status
Garden Point: all up Maxwell's Ck: all up Picker: profiler down-
disk crash Snake Bay: Kite is up Aerosonde: no flights up to 14:30: Trying flight at 14:30
to go into outflow region.
Cessna: Sea Breeze to Initiation
10:30 take off to 170/33 km. 1055 mid way, thru' transect- southern
sea breeze(weak) Onto 020/60 km 036/49 km for sea breeze obs. 11:45 proceed to 060/50 km -
057/90 km hts: 50 m and cloud base to look at NE distrubance approaching. 12:15 Convective
intitiation flights within a box : 060/50, 060/64, 074/68 and 080/52km to look at
interaction between southern sea breeze and disturbance. Soundings indicate increased
moisture. Easterlies extend to well above 500 hPa, with weak winds above. Long term
outlook not so promising as low analysed to NW over Indonesia with lots of associated
convection, indicating possible monsoon onset is not all that far away. Plan to have as
many IOP's ASAP. 9:45 Winds over the island have southerly component, suggest north coast
as the preferred area for convection. From approx 1100 disturbance with isolated
convection approaching from off the NE coast. 12:50 Appears to be strong cells over NE
part of th eisland- interaction between disturbance and northern sea breeze. 13:40 Wide
spread convection with large cells to the north, some weak echoes extending back off-shore
to the east. Whole island basicaaly going up. Nguiu records over 23 flashes/min. 14:10
Active cells > 50 dBz up to 8 km tops over 16 with v.high flash rates 40-50/min.
Evidence of rotation around the up-drafts. Cells on Western Bathurst dissipating as they
move off shore. 14:35 Starting to dissipate (at least according to Berrimah radar). Most
intense case in many respects seen during the experiment. Those of us in Darwin are
extremely jealous.
Arguably, the most impressive Hector observed during the MCTEX 95
experiment. Echo tops reached over 18 km with 50 dBZ up to 8 km or more. At peak
intensity, the storm spanned across the entire extent of both islands with over 100 km of
contiguous horizontal radar echo with reflectivity greater than 30 dBZ (at low levels, 2
km) along an east-west oriented line. Total lightning flash rates peaked at about 1 per
second (60 per minute) around 0500 UTC. CG flash rates were a maximum from about 0415 to
0515 UTC with peak CG flash rates of over 10 per minute.
Using GMS IR hourly satellite data, an overview of Hector's
development can be described. Shallow cumulus congestus was widespread in the morning
hours with activity focused initially on a seabreeze convergence zone along the southern
coast of both islands and also over northern Bathurst Island (02-0315Z). An early morning
(00Z) disturbance over the Arafura Sea, north of the Cobourg peninsula, reached the
eastern coast of Melvillle island at about 0330Z. At about the same time, convection over
eastern Melville began to intensify and became significantly electrified. Shortly
thereafter, convection over central Melville exploded such that an an intense east-west
oriented line existed over Melville Island by 0430Z. Convection bridged the Apsley Strait
between 0430 to 0530Z with activity primarily over western Melville and Bathurst Island by
0530Z. The cold cloud shield reached its peak over this area by 0630Z and began to
dissipate and advect off to the south-southwest by 0730Z.
Both radar and lightning measurements paint a similar picture of
this intense Hector. C-pol scanning consisted of 360 degreee non-polarized surveillance
scans up to 02Z. From about 02Z to 04Z, a 210 deg. polarized sector was used to cover the
islands. >From 04Z to 05Z, the convective dynamics scan was utilized with a polarized
scan only about once every 16 minutes. From 05Z to the conclusion of Hector, the CLES
scanning strategy was used with 1 non-polarized surveillance scan followed by 3 polarized
sectors.
Cumulus congestus was widely scattered from 00-02Z with primary
focus areas being along northeastern Melville, northern Bathurst, and along the south
central coast of Melville. From 02 to 03Z, the convection began to develop along a
convergence line along the southern coast of both islands with the most intense activity
on Melville, especially the extreme eastern portion. Between 03 and 04Z, scattered deep
convection broke out along an approximate east-west line over both islands with the bulk
of the activity over Melville. By 04Z, 30 dBZ tops over Melville reached up to 14 km.
Cloud-to-ground lightning activity rapidly increased over Melville during this time. Most
convective activity was out of flat plate range so total flash rates were still low.
Between 04 and 05Z, a contiguous east-west line developed over both islands with
horizontal extent over 140 km long. Peak low level reflectivities exceeded 55 dBZ and echo
tops exceeded 18 km. The peak total flash rate reached 1 per second in the vicinity
(within 40 km) of the radar by 05Z. From 05 to 06Z, the low level reflectivities began to
weaken and the system was located primarily over Bathurst Island. As the system weakened
and advected to the west, it began to re-orient from a primarily east-west to primarily
north-south oriented line of convection. By 0615Z, the system was off the west coast of
Bathurst Island and had a clearly defined north-south convective line with trailing
stratiform echo for 10's of km's. By 07Z, Hector was mostly dissipated with weak
stratiform like echo existing over northern Bathurst Island for the next 2 hours.
29 November 1995
IOP #7
Radar ops: Initiation into Convective Lifecycle Cessna: Sea
breeze/convective initiation
Franklin: West of Bathurst Is.
Aerosonde: in the drink (south of Melville)after 3 hours of flight time as part of an
attmpted all night flight to map land breeze citculation on the SE coast of Melville. NO
aersosonde operations for today but possible tomorrow. Garden Point: minor probs with
cloud radar - up late morning.
Maxwells Ck: All up
. Picker: Profiler down
Situation:
Active trough with lots of convection to our north- worrisome. Progs
indicate easterlies will be maintained with MT trough persisting north of Australia.
Breakdown of cross equatorial flow with low in Borneo region. Morning sounding from Darwin
showed deep moisture, lots of Cape Sat Pic shows systems around on land breeze. Very deep
easterly winds. Anticipate active day.
- 9am: Some decaying convection from land breeze, no sig. sea breeze
yet.
1000 Cessna due for 1030 departure with following way points
060/30-129/18 for SBM on SW coast of Melville Is. Flight track extends over
"high" terrain.
1120 Cessna aircraft reports weak SBF on SW coast. Second legs for
SBM on SE coast of Melville are 060/30-110/54. Radar reoprts are consistent with weak SBF
activity.
1142: Radar reports only small echo on SE Melville, extensive
overcast.
11:45 Fine line on SE and N coast of Melville, Continue previous
flight pattern.
11:50 Revise southern Cessna way point to 112/47 for lowest leg and
next SB section.
12:20 Cessna traverse thru' fine line shows 12 kn contrast, but
little temp or humidity change.
12:40 Move to convective initiation flights 23/30, 80/14, 41/40,
83/28 km. Expect northern sea breeze moving into NE corner of the box.
12:58 Single significant cell going up at 90/14 with 50 dBz echoes
in it. Visibly increasing in Ht from Darwin.
13:20 Cessna completing upper level pass on initiation flt, start
low level legs.
Slow going today - related to extensive upper level cloud cover?
13:30 Radar reports cells going up and falling back ahead of
northern sea breeze front. N SB visible in radar and visually ~20 km north of radar-
expect initiation when it iteracts with (stagnant) southern sea breeze. Uper cloud deck at
11-14 km.
13:45 Another 50 dBz cell at 100/30, but cells still short lived.
13:50 Close in cell flashing at 4/min, to 10/min 12 km NE of radar.
Cells trying to allign e-w just to the n of the radar. Problems with the radar Tx. Cell to
SE of Maxwells with 25 flashes/min.
14:05 Cessna added 2 traverses across outflows. On return flight.
Still very active, large cells going up.
14:10 Berrimah radar shows isolated , intense cells over Bathurst,
on Melville have N-S oriented line aproaching Maxwells Ck.
14:20 Radar back up. Hector clear from Darwin.
14:45 Most convection on southern 1/2 of islands. Nguiu reports
strong GF 3? km east of radar, strong cells to N and NE of radar.
14:57 GF just passed over the radar, system over the top of the
radar moving slowly, can't top the storm. High flash rates.
16:00 Have 2 distinct intense complexes (one for each island) with
weak system already off to the west. Should be good data for the Franklin. Systems are
showing signs of decreasing in intensity.
30 November 1995
IOP #8
Objective: Convective dynamics and flux mapping
From a large scale perspective, there was westerly flow and
equatorial convection across western Indonesia and the Java Sea. The flow was also
westerly in the northern hemisphere, indicative of an impending MJO event. A ridge
extended across central Australia in the low- to mid-levels. This retained easterly flow
over northern Australia. The Maxwell Creek soundings showed north-northeasterly flow of
3-4 m/s in the boundary layer, a 10-11 m/s east-southeasterly jet between 710-760 mb and a
11-12 m/s southeasterly wind maximum at about 500 mb.
The aerosonde commenced operations at about 0200 UTC, primarily
executing 1500 m soundings in the vicinity of Pickertaramoor. The Franklin was deployed to
the vicinity of Rocky Point in expectation of a northwesterly Hector trajectory. The
Cessna departed Darwin at about 0530 UTC and made flux measurements over the easternmost
Melville Island flux point (~0600 UTC), Maxwell Creek (~0625 UTC), Apsley Strait (~0655
UTC) and eventually over the Franklin (~0725 UTC).
The C-pol radar observed sea-breeze fronts on the south side of the
islands, especially southwestern Melville and southeastern Bathurst. These fronts began to
move northward at about 0200 UTC. Convective cells began developing over many parts of the
islands just before 0300 UTC. However, the convection was concentrated in two areas: the
western coast of Bathurst island and the southwestern Melville/southeastern Bathurst
region (i.e., near the radar site). By 0500 UTC, these two regions began to merge over the
central part of Bathurst Island. There did not appear to be one clear linear orientation
to the convection. Between 0600 and 0700 UTC, this convection became stratiform and
advected off the island to the northwest. During the same period, new convection developed
southwest of the radar over the Beagle Gulf as well as over the majority of Melville
Island. The Beagle Gulf convection eventually merged in with the stratiform precipitation
advecting off of the northwest Bathurst Island coast. The new convection over Melville
Island created a large stratiform precipitation region of its own that gradually decayed
as it advected to the northwest and off of the islands during the period between 0700 and
1000 UTC.
The radar scanning consisted of boundary layer PPI's interspersed
with a few polarimetric RHI's from 951129/2200 to 951130/0300 UTC, island polarimetric
SECTors (230 degrees) interspersed with polarimetric RHI's from 0300 to 0430 UTC,
polarimetric SECTors (180 degrees) interspersed with PPI's from 0430 to 0630 UTC and
polarimetric VAD (360 degree) scans from 0630 to 1100 UTC. All of the PPI scans, excluding
the VAD scans, were non-polarimetric.
Status summary:
Profiler/RASS (900Mhz Pickertaramoor) - down Aerosonde - up C-POL -
up Cessna - up Kite - ????? AWS - up (all stations??????) Cloud radar - ????? Lidar -
????? Franklin - up Videosondes - up (when were the launches?????) Rawinsonde - up Sondes
launched at: 951129/21:59 UTC 951130/00:00 UTC 951130/02:01 UTC 951130/08:01 UTC
951130/09:59 UTC
**status of sondes launched at 0400 and 0600 UTC is unclear; the
BMRC archive may have the 0400 UTC sonde but there is no associated header file to go with
it.
30 November 1995
IOP #8
Situation is a continuation of yesterday with a westerly flow and
equatorial convection across western Indonesia and tha Java Sea. The flow is also westerly
in the NH, indicative of a MJO-type event. A ridge extends across central Australia in the
low-mid levels. This retains easterly flow over northern Australia and the progs have this
strenthening. Looking out window, we have extensive low scud and lots of debris-type
stratocumulus and high level cirrus.
The IOP is a convective dynamics day, with flux measurements by the
Cessna starting late to catch the post-Hector conditions
Franklin has redeployed to vicinity of Cape Helvetius...the wave
rider buoy will be deployed there and then they will do surveys in anticipation of Hector.
Agreement is that if no comunications, they will stand-by for aircraft flux
intercomparison from 1630-1800 lst.
Aerosonde is to initially do soundings to 1500 m over Picker runway.
Picker Profiler is still out, awaiting new computer.
Based on 0730 sounding from Maxwells Creek, Franklin redeployed to
vicinity of Rocky Point in expectation of a more NW trajectory on Hectors.
0730 (local time) winds, 30 November, from Maxwells Creek:
(P) dir speed 1000 298 4.0 925 011 4.4 850 063 4.3 700 106 9.8 500
132 10.5 400 091 4.9 300 109 3.9 1130: Aerosonde started operations
- 1135: Franklin is in process of dropping the wave rider buoy
- 1140: From BI radar: echoes to 18-20 dBz on S coast of Melville, Cape
Gambier to Conder Point
- 1300: Franklin started operations with a significant convective cell
in the vicinity of Rocky Point
- 1345: Agreed that FIAMS aircraft should depart 3 pm for easternmost
flux point of Melville Is (alternatively Picker fire tower); then Maxwells Creek, Apsley
Strait and over the Franklin.
- ~ 1400 ... 1130 winds and temps received from Maxwells Ck .. winds
mainly east to southeast up to above the tropopause; 9.7 m/s at 700 and 500 hPa from 104
to 114 deg. Temp trace unchanged from previous one.
- 1505: Aircraft on track to easternmost point. Aerosonde advised to
stay above 700 m.
- 1515: Franklin is steaming northward to a position near Rocky Point.
- 1520: BI radar advised that aircraft will be on station at
easternmost point for next 15 minutes. 1540: Aircraft sent to Maxwells Creek.
- 1540: Aerosonde 4 km N and 600 m east of the runway.
- 1550: G. Holland visual observation north from Darwin. Basically, a
"chaotic sky" with a great deal of stratocumulus, high level stratiform and
cirrus. Cb largely without significant anvils; more like semi-oceanic type convection.
- 1555: Convection mainly on the southern side of Melville. Recommended
to Franklin that they move to near the wave rider buoy. Aircraft should be there in 30-90
minutes; large uncertainty since we're vectoring aircraft around Cb cells.
- 1610: Aicraft has completed Maxwells Creek fluxes. Bathurst Island
radar advised. Expected at Franklin ~ 1640.
- 1612: Franklin advised that the aircraft will be there between 1640
and 1645. Aircraft to "buzz" the ship first, then do flux measurements.
- 1615: Franklin position at 1645 should be near 130 deg E even and 11
deg 31 min S. Heading is N 12 deg true.
- 1633: Aerosonde 1.5km N & 14km E of runway.
- 1700: BI radar reports convection south of radar to approx 17-20 km.
- 1703: Holland obsdervation: low level roll cloud approx. 10 km north
of the Bureau and moving towards Darwin.
- 1707-10: Contact with Franklin: aircraft still doing flux passes of
the ship. There was a wind shift at the surface; the ship had to reposition into the wind
and flux passes were delayed.
- 1715: advised the aircraft to come to 11 deg 55' S and 130 deg 15' E,
then east along the southern edge of a convergence line to the north of Darwin. Good to be
able to get aircraft data on a section through this line.
