***Date:*** 8 JUNE ***Julian Day:*** 160 ***Experiment Day:*** 08

**Mission Scientist:** Dr. Bruce Wielicki

**Mission Objective:** Coordinated multi‑aircraft radiation measurements
with LANDSAT overflight.

**Mission Description:** Multi‑aircraft vertically separated.

**Synoptic Situation:** Broken stratocumulus layer in northeast portion
of the ASTEX triangle in light north‑northeasterly flow.

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**GENERAL, A.M. WEATHER:** 8 June 92 ‑ 12 GMT surface high position near
39N, 35W with a 1028mb closed contour. Estimated maximum surface sea
level pressure is near 1029mb. The surface high is now moving
southeastward behind the cold frontal boundary which now extends across
the triangle from just north of Porto Santo to near 33N, 25W. Dew points
north of the front (in the Central Islands) range from 6‑10C. South of
the front the dew points are near 15‑ 16C. The region north of the cold
front is characterized by scattered, patchy cellular stratocumulus
(2/8‑3/8) and some cumulus. South of the front, a more cellular
scattered to broken stratocumulus pattern exists. Diurnal breakup is
evident in both the northern and southern regimes. Some very thin,
patchy cirrus are also being observed near Santa Maria. Winds behind the
front across the ASTEX region are north to northwest at 10‑15kts. Winds
south of the front are north to northeast at 15‑20kts.

**NASA ER-2:** Flight track aimed at overflying two Landsat‑4 scenes on
a heading of 199 deg such that the cross track scanning MAS was scanning
in the principal

plane of the sun. The flight line began northeast of San Miguel at 38
deg 10\' N, 24 deg 14\' W, and proceeded SSW to 35 deg 30\' N, 25 deg
18\' W, crossing 37 deg 30\' N, 24 deg 30\' W at the time of the
Landsat‑4 overpass (1121 GMT). Following this 311 km ground track the
ER‑2 flew to 36 deg 30\' N, 24 deg 45\' W where it overflew the Le
Suroit ship. It then proceeded on an east‑west cross section 196 km in
length, overflying the Le Suroit 4 additional times. These flights were
coordinated with the F‑27 and C‑131A aircraft, and overflew the ship
westbound at 1200:45, 1220:00, and 1243:00. Later the ER‑2 moved to

38 deg 24\' N, 25 deg 51\' W and flew two east‑west legs 200 km in
length coordinated with the NCAR Electra Aircraft, before returning to
Lajes Field. Most of the flight consisted of broken clouds, and included
an excellent view of Santa Maria at 1129 GMT. Over the open ocean, some
cumulus clouds were observed, as well as stratocumulus and clear skies.
Takeoff 1028 GMT Landing 1445 GMT.

INSTRUMENT PERFORMANCE

MAS Instrument performed extremely well, except for the 13 um charnels
which were too noisy. The 2.14 and 3.73 um charnel showed 2X2 pixels\
saturated at the northwest corner of Santa Maria (fires?), but these
were not particularly bright in the visible or thermal bands.

CLS The lidar worked well throughout flight. It showed thin to thick
cirrus above stratus for much of flight, with the cirrus at 9‑12 km and
the stratocumulus at about 1 km.

EOC Instrument worked, but gain levels are such that there is some
saturation on all six charnels, with the exposure time such that all
charnels are saturating at about the same brightness levels. The focus
has now been improved so that it once again has a resolution of about
4.5 m at nadir.

RADIOMETERS Apparent problem in input/output bus and did not record data
during mission.

**MRF C-130:** Down

**UW C-131A:** Coordinated radiation measurements with ER‑2, Fokker‑27,
Electra and C‑131A with satellite overpass. C‑131A to make cloud
microstructure measurements along W‑E track centered approximately over
the Le Suroit ship.

Climb out of SMA found thin Sc cloud bases at 5.0 and tops at 5.3 kft
ASL for rad experiment. Performed several rad circles but south of
previously agreed on point due to lack of clouds at that point. Flew rad
circles over mesoscale region of overcast stratocumulus clouds of
relatively homogeneous appearance. No overshooting Cu tops visible this
area. Last rad circle over far thinner, partially transparent cloud of
broken coverage with widely scattered very small Cu below. Terminated
this first phase of flight plan to rendezvous with Le Suroit and perform
W‑E legs of about 40 nm length.

Cloud coverage organized into mesoscale clear and overcast regions with
thicker and thin spots in clouds. As it happened, Le Suroit was in thin
spot during our passes with clearing moving in from the north by lest
leg. Cloud thickness

over the Le Suroit was \<30 m during the lest pass, and was perhaps 100
m at the maximum. Thicker Sc W end of leg with embedded Cu with
overshooting tops

\<20 m above general cloud top. Max LWC measured, 0.8 9 kg^-1^, was
measured here. Flight legs just below cloud base showed descending cloud
bases from near Le Suroit from about 4.9 kft to 3.2 kft ASL W end of
cloud patch. Large mesoscale clearing to W or W end of flight leg.
Similar cloud scenario E of Le Suroit, though less thickening of clouds
and longer LWC maxima. Gradual thinning of cloud with movement of
clearing into vicinity of Le Suroit, departure of F‑27 from overhead led
to termination of flight legs at about 1140 Z.

**NCAR ELECTRA:** The purpose of the flight was to underfly the NASA
ER‑2 and Landsat satellite pass and determine the island wake effects of
San Miguel Island.

The block‑out time was 1025GMT, take off 1030GMT. The coordinates on the
map supplied were not correct, and these were collected in transit to
the NE. Cloud base and top were 4700 and 5700 feet. 5200 feet was chosen
for the ER-

2 underfly. Two tracks were flown along 19 true from 1112 to 1126 and
1128 to 1146. At the requested time of 1121 we broke out into clear air.
We passed the requested point \"A\" 37°30\'N, 24°30\'W at 112230. The
flight then proceeded to the E‑W track between San Miguel and Santa
Maria Islands (37°24\'N, 25°40\'W (G) and 37°24\'N, 24°0\'W (F)). A
sounding was made to F. Wake transmit legs were flown between F and G at
500 ft, 100 ft, 5200 ft, cloud top. A sounding was made from 6200 to
100\' in the middle of the wake to the north over Ponta Delgada.
Transits were flown on the north (upwind) side of San Miguel at 6500,
6000, 100, 500, 3000 feet for at least 15 minutes each. A sawtooth run
was made between 5000 and 7000 feet. Soundings were made in the area.
The research pattern ended at 164500 GMT, 6 1/2 hour flight. There were
no reports of instrument problems.

The NASA ER‑2 underfly was successful as there was a 1000 foot thick
cloud layer. As mentioned above, we broke out into a small clear area
just at the overflight time, but generally were in cloud the whole
track. For the island wake study, the E‑W tracks were good, since the
wind was from between 250 and 15 deg true, and thus the tracks were
crosswind. Winds were from about 5 to 8 m/sec. The wake of San Miguel
was very evident in both the UTF (ultra fine particle counter) and ozone
measurements, as well as the wind. The wake particle and chemical
measurements were very intermittent and inhomogeneous. The upwind runs
past San Miguel were somewhat less eventful\-- the clouds had dissipated
over most of the track. Some detailed sawtooth profiles were flown
between 5000 and 7000 feet to investigate the particle and ozone
relationship.

**ARAT F-27:** Two missions. The first flight was coordinated with ER‑2
(during leg A‑B) and C‑131 (during leg E‑F) during a LANDSAT overpass.
The mission\
involved remote sensing with LIDAR and radiometers.

The second flight involved flux surface mapping, turbulence in the MBL,
measurements in the wake of Santa Maria, comparison with the Le Suroit,
and lagrangian balloon experiment. Flight carried out south southeast of
Santa Maria with the Le Suroit in the Northeast part of the pattern. One
sounding was‑made up to FL80 in the east part of the operating area.
Three turbulent mappings were conducted at 150ft, 1,200ft, and 2,500ft.

**FMO Merlin IV:** Not operational

***Date:** 9* JUNE ***Julian Day:*** 161 ***Experiment Day:*** 09

**Mission Scientist:** John Taylor

**Mission Objective:** Study energy transfer between the sea surface and
the atmospheric boundary layer.

**Mission Description:** Turbulence legs around Le Suroit with C‑130 and
F‑27.

**Synoptic Situation:** High pressure system centered west of Santa
Maria and causing light north to northwesterly winds to flow through the
northern part of the ASTEX triangle.

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**GENERAL, A.M. WEATHER:** 9 June 92 ‑ 12 GMT surface high position near
35N, 30W with a 1024mb closed contour. Estimated maximum surface sea
level

pressure is near 1028mb. The surface high is drifting south behind a
very diffuse cold frontal boundary which now extends across the southern
third of the triangle. Scattered, patchy cellular stratocumulus
(2/8‑3/8) and some cumulus exist over the entire triangle. Winds are
west‑northwest at 10kts across the northern portion of the triangle, and
more northerly at 15kts across the southern two thirds of the triangle.
Cirrus clouds associated with a warm front passing around the northern
periphery of the high are evident some 300km north and northeast of
Santa Maria. In addition, cirrus associated with a developing upper
level low near 28N, 38W is entering the southernmost portion of the
triangle.

**NASA ER-2:** Down

**MRF C-130:** A very successful flight was carried out as part of the
French SOFIA experiment, to study energy transfer between the sea
surface and the atmospheric boundary layer. The C‑130 worked in
conjunction with the Fokker F‑27 and also\
the NOAA P‑3, and the initial stack positions were on either side of the
French\
ship, Le Suroit.

A rendezvous point for the C‑130 and the F‑27 was decided as the
southerly end of a stack 25km downwind of the ship. On transit to this
point a profile was carried out from 7000ft to 50ft, but the profile
went through the gap between two large patches of stratocumulus. The
inversion height was 4500ft and the layer

was decoupled at 2400ft, below which the surface layer was well mixed. A

profile back up through the thickest patch of stratocumulus showed
cumulus bases at the top of the surface layer and most of the cumulus
were merged with the stratocumulus base. The effective radius at cloud
top was 6um and the droplet concentration was 190 cm‑3.

A vertical stack was completed perpendicular to the wind direction from
the rendezvous point. A coordinated run was made with the F‑27 flying at
12,000ft and the C‑130 just in the cloud tops. During this stack, two
patches of stratocumulus were sampled, between which was a clear area
with some scud. Several cumulus merged with the stratocumulus were
sampled, and in these areas the effective radius was higher, up to 9um
and drizzle was observed. The cloud thickness was variable in both
cloudy areas.

A square box pattern was made around the slip at 100ft, with legs
perpendicular and parallel to the wind direction, to measure the surface
fluxes. The F‑27 had already mapped this box using the lidar from high
level.

Two further vertical stacks were made, separated by profiles, at
positions advected downwind from the initial stack position. During the
first of these stacks, the

P‑3 flew coordinated legs 1000ft above the C‑130 while the C‑130 was
flying at cloud level. The patches of stratocumulus drifted further
apart through the afternoon and became smaller, but the cumulus below
the stratocumulus merged further with the stratocumulus to form a more
solid layer.

Profiles were carried out approximately northwards from the end of the
third stack, in order to sample the clear areas as well as the cloudy
areas. It was found that the boundary layer beneath the inversion in the
clear areas was markedly decoupled at about 2100ft, whereas the boundary
layer beneath the solid cloud layers was well mixed. In areas where
there were mainly cumulus clouds, the boundary layer was also decoupled
and seemed to represent a transition between the two regimes.

**UWC‑131A**: Down

**NCAR ELECTRA:** Down

**IRAMP P‑3**: Flew a coordinated stack profile with the UK C‑130. The
C‑130 flew 6 level legs from 500 ft above the cloud top to just above
the surface, including two legs through the cloud. The P‑3 flew parallel
to their track, 1,000 ft above them looking sideways toward the cloud.
Did a series of runs looking at the horizon getting radiance imagery
which included both the horizon sky and the sea surface just below the
horizon. This included runs looking in several different directions
relative to the wind direction and solar azimuth angle. Overall the
flight went well and the P‑3 collected some data on each objective,
although they were not 100% successful on either objective.

The deck that the UK C‑130 was flying through on their stack was too
large for the P‑3 to fly parallel to their flight track outside of the
cloud. So, the P‑3 waited until the C‑130 descended below the cloud and
flew 2 passes getting radiance imagery of the face of cloud the C‑130
had entered to begin its in cloud flights. It flew perpendicular to the
C‑130 flight track, so the radiances were measured along and parallel to
the C‑130 flight track through the cloud, but 10 to 20 minutes after the
C‑130 made its\' measurements.

On the horizon runs, the P‑3 flew a box pattern about 10 minutes on a
side around the Suroit, at an altitude of 200 ft. Because of the
difficulty of flying perfectly level at low altitude and the limited
vertical FOV of the IRAMMP sensor (1.7 deg) it was not possible to
obtain long periods of flight with the horizon continuously in view.
However several minutes of data were collected along each leg of the
box.

The one major problem, was the failure of the Quick Look system which
permits inflight examination of the uncalibrated radiance imagery.

**ARAT F-27:** Two flights. The first flight was a boundary layer
structure mission east of Santa Maria. A sounding was made up to FL120
where a square LIDAR pattern was conducted. A sounding was the made
clown to the surface.

The second flight was associated with the C‑130 and involved LIDAR
mapping and turbulence mapping in the MBL in a vertical plane near the
east southeast of Santa Maria. A sounding was made up to FL 120 where a
square LIDAR pattern was conducted. Turbulence measurements were
conducted at 2,000ft and 300ft.

**FMO Merlin IV:** Not operational

***Date:*** 10 JUNE ***Julian Day:*** 162 ***Experiment Day:*** 10

**Mission Scientist:** Dr. Bruce Albrecht

**Mission Objective:** Porto Santo island ‑ aircraft intercomparison
then temporally separated intercomparison in transition region.

**Mission Description:** Island intercomparison and multi‑aircraft
temporally separated.

**Synoptic Situation:** A high pressure system was centered west of
Santa Maria causing light north to northwesterly winds through part of
the ASTEX triangle and north to northeasterly winds in the southern part
of the triangle. Widely scattered small cumulus.

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**GENERAL, A.M. WEATHER:** 10 June 92 ‑ 12 GMT surface high position
near 33N, 33W with a 1024mb closed contour. Estimated maximum surface
sea level pressure is near 1027mb. A Surface low (998mb) is currently
located near 50N 29W and a surface warm front extends from this system
southward into the western islands. Scattered, patchy cellular
stratocumulus (2/8‑3/8) and some cumulus exist over the triangle south
of a line from 33N, 25W to 35N, 20W.

Winds are west‑northwest at 10kts across the northern portion of the
triangle, and more northerly at 10kts across the southern two thirds of
the triangle. North of the islands, multi‑level clouds including
stratocumulus with some drizzle and fog, altocumulus, and cirrus exist
in association with the frontal system passing over\
the northern periphery of the surface high. In addition, cirrus
associated with a developing upper level low near 28N, 38W is exiting
the southeastern most portion of the triangle near Porto Santo.

**NASA ER-2:** Down

**MRF C-130:** A sortie was carried which consisted of two phases. The
first to carry out an aircraft/island intercomparison experiment with
Porto Santo and the second to complete the second phase of a diurnal
variation mission which had been started earlier in the day by the
Electra. The Porto Santo experiment was only partially successful as
there was very little cloud over the field site at the end of the runway
on the island but the diurnal variation mission was very successful with
the cloud mass that had been sampled by the Electra being followed well
into the afternoon.

On take off from Santa Maria very little cloud was encountered but
cirrus very quickly built up from the southwest and it proved impossible
to carry out any box patterns for pitch and roll offsets or any MCR
short wave calibrations. The cloud at longer levels was very patchy.
About half way along the transit to Porto Santo at 19,000ft more
extensive areas of stratocumulus were observed both to the southwest and
the east.

On reaching Porto Santo a profile from 19,000ft to 50ft was flown. This
flew through a sheet of stratocumulus (tops 4,700ft and base 3,200ft)
which was about 80km to the north of the Island and some drizzle was
encountered. However the track very quickly took the aircraft out from
under this cloud into a field of small cumulus clouds. Large amounts of
cirrus was seen above. A stack was then flown 30nm upstream of the
island in this field of small cumulus. The across wind legs were flown
at the following levels:(a) 100ft; (b) 1,100ft below\
the bases of the cumulus clouds; (c) 2,900ft above the bases of the
cumulus clouds; (d) 4,000ft above the bases of the cumulus clouds but
below the inversion base. A cumulus cloud was entered on this run; (e)
4,500ft in the inversion. The top of a cumulus cloud was skimmed through
on this run; and (f) 5,400ft above the inversion. What appeared to be
gravity waves (perhaps generated by the convection in the boundary
layer) were observed at the level of the inversion.

Three straight and level runs were then flown over the island which was
covered by cumulus clouds but not over the field site. It appeared as
though these clouds were being generated by surface heating over the
island. The runs were at 1,400ft (below the base of the clouds), 3,800ft
through the clouds and 5,400ft above the inversion. Each pass was made
directly over the field site.

A transit was then made to 33 degrees 40 minutes north, 20 degrees west;
a position indicated by the Electra as the air position they were
working in the morning. Here a coordinated flight with the P3 was made
in the tops of an extensive sheet of stratocumulus which was found
there. The heights of the tops were 4,600ft. During a straight and level
run at 4,400ft the P3 flew parallel to the C‑130, 1,000ft above and to
the right. A sharp edge was encountered very close to the start of this
run which we flew away from. For the rest of the mission the P-3 flew
parallel to this edge over the clear air while the C‑130 flew in the
cloud\
but perpendicular to the edge which was orientated along the wind. When
above the cloud local variations in its reflectivity could be seen but
it was difficult to tell whether these were caused by shadowing from the
inhomogeneous cirrus clouds above.

Following the coordinated leg with the P3 a profile was carried out from
6,000ft to 50ft through the cloud. It was found to be 700ft thick. The
boundary layer underneath it was decoupled and there was some scud and
small cumulus clouds present. A stack was then flown at the following
altitudes across wind: (a) 4,100ft very close to cloud base; (b) 3,100ft
between the base of the stratocumulus and the base of the cumulus
clouds; (c) 2,100ft near the base of the cumulus clouds; (d) 600ft; and
(e) 100ft.

On a few occasions drizzle was encountered. As each leg took the
aircraft very close to the edge of the cloud sheet, they were all
extended by 3 minutes to ensure both the cloudy air the Electra worked
in was sampled and also the clear air was sampled. The edge was very
sharp and the clear air and the cloudy air had very different
characteristics. Jumps in equivalent potential temperature and total
water content were observed even at the level above the inversion.

A profile was then carried out from 50ft to 6,000ft through the cloud.
Most of the cirrus by this time had moved away and all that remained was
some thin cloud near the horizon which the aircraft did not fly under. A
race track was then flown at 6,100ft (above the cloud) which was
extended out over the cloud edge and was followed by a straight and
level run across wind through the center of the cloud layer at 4,200ft.
As the edge of the cloud sheet was approached, relatively large holes in
the cloud were flown through. The edge appeared to be associated with a
small line of cumulus clouds which were lined up under the cloudy side
of\
the edge. A profile in the clear was then carried out from 5,600ft to
50ft.

The sortie was then completed with a series of vertical saw tooth
profiles towards Santa Maria. These turned out to be all in clear air
and were terminated after 2 profiles. Only very broken cloud was
observed on the way back to Santa Maria. Takeoff 08:21 GMT Land 17:21
GMT.

**UW C-131A:** Sulphur/aerosol measurements largely out of cloud. On
climb from 4 kft to 8 kft, CN peaked at 6.2 kft at about 600 cm^-3^
range above 66 nm. For first single 88 nm. This flight was for marine
sulphur cycle study. Sampled at seven levels for DMS, SO2, CN, CCN, DMPS
and particle compositions (filter). Sampled both above and below a
stratocumulus deck between 3 and 4 thermal feet. Leg was perpendicular
to the mean wind. The LWC of the cloud was 0.1 gm^-3^ which

was too low for effective sampling. Sampling occurred between 78 and 98
nm from Santa Maria.

**NCAR ELECTRA:** The Electra ferried out to 34°26.1\'N, 19°23.6\'W at
9000\' and descended, after finding a suitably cloud‑covered region.
Cloud top was at 5100\', and beneath the primary cloud deck (base at
3500\'), a secondary layer was present, extending clown to 2500\'. A set
of flight legs oriented 115°‑295° was flown, 15 minutes in length, with
initial center coordinates given above. Levels flown were 100\', 2000\',
3000\', 4200\', 4700\', at inversion (4700\'‑5000\') and 7000\'. Next a
sounding was conducted from 9000\' to 100\'. A second pattern was flown
at 100\', 2000\', 4300\' at inversion (4200\'‑5000\'), and at 7500\'. A
sounding from 9000\' to 100\' and back to 9000\' was flown. This
completed the pattern. The final center point was at 33°49\'N and
19°55.3\'W. The C‑130 was planned to continue this set of diurnal
variation flights.

Initially the clouds were in separated masses. During the flight, these
separate masses grew together to some extent, so that at the end, the
area was almost completely filled in. Clouds were at 2 levels at the
beginning, and appeared to come together somewhat during the flight.
Winds were light (and sometimes calm) generally from the NNE, about 5
knots. All the flight legs were advected with the wind. Takeoff was at
4:49, landing at 11:35.

**NRL P‑3**: Flew a coordinated stack profile with the UK C‑130, about
30 miles upwind of Porto Santo. They flew 6 level legs from 500 ft above
the cloud top to just above the surface, including two legs through the
cloud. We flew parallel to their track, a 1,000 ft above them looking
sideways toward the cloud.

The P‑3 was delayed in takeoff because of radar problems, and tookoff
shortly before 1100. The P‑3 was able to obtain a location from the UK
C‑130, & by relay in time for the P‑3 to divers to an alternate time and
location (1300 at 33 deg 49\' N and 19 deg 55\' W) for the planes to
meet before the C‑130 began their second series of stacks in the
vicinity of the advected airmass of where the Electra made its morning
measurements.

The P‑3 was able to make some Cirrus measurements along the NE leg of
the ASTEX triangle enroute to the rendezvous with the UK C‑130.

As was the case yesterday, the deck that the UK C‑130 was flying
through\
on their stack was too large for the P‑3 to fly parallel to their flight
track outside of the cloud. So the P‑3 waited until the C‑130 descended
below the cloud and flew\
2 passes getting radiance imagery of the face of cloud the C‑130 had
entered to begin its in cloud flights. Flying perpendicular to the C‑130
flight track, the\
radiances were measured along and parallel to the C‑130 flight track
through the cloud, but 10 to 20 minutes after the C‑130 made its
measurements. The Quick Look data system still was not operational.

**ARAT F-27:** Down

**FMO Merlin IV:** Not operational

***Date:*** 11 JUNE ***Julian Day:*** 163 ***Experiment Day:*** 11

**Mission Scientist:** Dr. Christopher Bretherton

**Mission Objective:** Down day

**Mission Description:**

**Synoptic Situation:** A high pressure system was centered west of
Santa Maria and resulted in light north to northwesterly winds through
part of the ASTEX triangle and north to northeasterly winds in the
southern part of the triangle.

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**GENERAL, A.M. WEATHER:** 11 June 92 ‑ 12 GMT surface high position
near 33N, 30W with a 1024mb closed contour. Estimated maximum surface
sea level pressure is near 1028mb. A surface low (1007mb) is currently
located near 50N 20W and a surface warm front extends from this system
southward into the far northern portion of the triangle just south of
Santa Maria. Mostly broken to overcast stratocu exists to the north of
this boundary. The central portion of the triangle is mostly clear,
while scattered, patchy cellular stratocumulus (2/8-3/8) and some
cumulus exist over the triangle south of a line from 32N, 25W to 33N,
18W. Winds are west‑northwest at 10kts across the northern portion of
the

triangle, and more northerly at 10kts across the southern two thirds of
the triangle. From the Azores northward, multi‑level clouds including
stratocumulus with some drizzle and fog, altocumulus, and cirrus exist
in association with the frontal system passing over the northeastern
periphery of the surface high.

**NASA ER-2:** Down

**MRF C-130:** Down

**UW C-131A:** Down

**NCAR ELECTRA:** Down

**IRAMMP P‑3**: Returned to the States with instrument problems. End of
participation in ASTEX. Two flights were accomplished.

**ARAT F-27:** Down

**FMO Merlin IV:** Not operational

***Date:*** 12 JUNE ***Julian Day:*** 164 ***Experiment Day:*** 12

**Mission Scientist**: Dr. Doug Johnson

**Mission Objective:** Study the diurnal variation of an air mass
throughout a 48 hour period using several aircraft, to trace the
movement of the air mass.

**Mission Description:** Lagrangian mission ‑ multi‑aircraft temporally
separated.

**Synoptic Situation:** A high pressure system was situated to the
southwest of the Azores and nearly all of the triangle was affected by a
north easterly wind. The winds were generally from 010 to 020 at 10 to 1
5kts throughout the boundary layer.

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**GENERAL, A.M. WEATHER:** 12 June 92 ‑ 12 GMT surface high position
near 33N, 30W with a 1028mb closed contour. Estimated maximum surface
sea level pressure is near 1032mb. The entire project area is now under
the influence of

strong high pressure. Mostly broken to overcast *718‑818* stratocu
exists along and north of the northeast boundary of the project area.
The central portion of the triangle contains scattered patchy cellular
stratocumulus (3/8‑6/8) and the

southern portion of the triangle is mostly clear. Winds are
north‑northeast at 10‑12kts across the northern portion of the triangle,
and more northeasterly at 15kts across the southern two thirds of the
triangle.

**NASA ER-2:** Flight track aimed at overflying a NOAA‑12 satellite
orbit over Santa Maria on a heading of 191 deg. The flight track began
northeast of Sao Miguel at 38 deg 00\' n, 24 deg 55\' W, and proceeded
SSW to 35 deg 00\' N, 25 deg 35\' W, crossing Santa Maria (36 deg 57\'
N, 25 deg 11\' W) at the time of the NOAA‑12 overpass (0948:37 GMT).
Following this 340 km ground track the ER‑2 flew back past Santa Maria
on a heading of 11 deg, overflying it at 1030:27 and again southbound at
1054:38. The ER‑2 then proceeded on an orthogonal track crossing Santa
Maria at 1118:22 and 1140:44, and again on the NOAA‑12 ground track
crossing Santa Maria at 1205:40 and 1230:33 GMT. Some of these flight
legs

were at a heading of 191 deg and some at a heading of 102 deg. Over the
ocean and Santa Maria, there was extensive stratocumulus except over the
southernmost portion of the NOAA‑12 ground track. Takeoff 0858 GMT
Landing 1308 GMT.

INSTRUMENT PERFORMANCE

MAS Instrument apparently performed well, but a tape glitch on the
recorder does not permit us to read past a tape mark to recover data.
Data may be recoverable from exabyte, but at the present time we are
unable to read any data.

CLS The lidar worked well throughout flight. It showed thick
stratocumulus at 1 km altitude, with a second level over the longer deck
fate in the flight.

EOC Instrument worked well, but gain levels are such that there is some\
saturation at both blue charnel polarizations. The data look extremely
good, with considerable detail on the cloud structure.

RADIOMETERS Data recorded throughout mission. Good signal level at 3.7
um, indicating optically thick clouds.

**MRF C-130:** A successful lagrangian mission was flown to the
northeast of Santa Maria. On transit to the lest position of the
Electra, we started tracking the constant level balloons. A transmission
from balloon 12 at 2326Z was received,\
the height trend from this balloon along with the inability to receive
any further transmission suggested that the first six balloons launched
had gone into the sea. We continued to track balloon 3 which was
launched later but at 0144Z, we

received a final signal at height 35m before it also went into the sea.
The trajectory for balloon 12 was mapped from its last transmission and
a profile was flown from FL110 to 500ft. Cloud tops were observed at
2200ft with cloud base at 1200ft. Winds were 008/18kts, the boundary
layer was well mixed. There were some\
small amounts of drizzle observed on this initial profile. A series of
runs were then flown, 10 minutes duration orientated across wind,
drifting with the wind at the\
level of flight. Runs were flown at the following levels: 550ft, 800ft,
1000ft,\
1400ft, 2000ft and 2400ft. A porpoise run was also flown 300ft above
cloud top\
to 300ft below cloud top.

The microphysical properties of the cloud suggested that the cloud sheet
was stratocumulus and quite homogeneous. During the initial run at 550ft
the moon was occasionally glimpsed through the cloud but during the
flight the cloud thickened and this phenomenon was no longer observed.
The MARSS radiometer showed that the cloud was marginally thicker
towards the eastern end of the runs at the beginning of the sortie.
During the sortie cloud base dropped to approximately 800ft, although
there was some scud below and cloud top rose to around 2500ft. At the
top of the second stack, the cloud top was observed to vary from 2500ft
in the west to 2200ft in the east. Runs above the cloud showed the tops
to be quite structured but no large cumulus were observed to penetrate
the main deck.

Two complete stacks were flown at the above mentioned levels and one
incomplete stack was flown with legs at 550ft, 800ft, 1000ft and 1400ft.
The Electra then arrived on task (0430Z) so the C130 climbed to FL200 to
clear the area. The Electra began operating in the advected air position
that the C130 had been flying. Unfortunately due to reports of
deteriorating weather at Lajes, the C130 had to curtail its mission at
this point and return to Santa Maria. On return transit to Santa Maria,
a large island wake effect was observed from Sao Miguel with extensive
gravity wave features observed in the cloud sheet. Take Off: 23:03.21
GMT Landing: 05:55:00 GMT.

**UW C-131A:** Three facets; coordinated radiation flight with
Fokker‑27\
and ER‑2, sample ship plumes as opportunity presents, overfly Penn State
field site in‑cloud.

Cu/Sc bases 10‑20 (aviation shorthand for 1000‑2000 AGL), higher Sc
bases 36 with tops variable from 39 in the vicinity of SMA to 64 in the
vicinity of the south end of the flight track where a line of protruding
Cu congestus tops and scattered RWU were roughly oriented E‑W in south
portion of flight track. These were perhaps the largest Cu seen on a
flight to date.

Simple single layer Sc with orographic lower Stratocumulus/ Cumulus in
the vicinity of the SMA hills devolved into multiple layers along
southbound flight leg. Lowest clouds were comprised of St fractus and Cu
fra. Two stratiform layers were present above these clouds. The lower
one was based between 30‑35, and the second based just above the first
layer. Occasionally these layers merged. Tops of the highest layer were
between 42‑44. No protruding cumuliform tops were visible. The situation
evolved into a nearly homogeneous cloud layer during the middle portion
of the radiation legs, as the more uniform cloud shield upwind advected
into the area. Droplet concentrations were 100‑150 cm^-3^ with liquid
water content near cloud top of 0.3 to 0.4 9 kg‑\' for extended flight
durations of 10‑30 min. Except for the chaotic early cloud situation,
this rad flight segment was perhaps offering the most promising returns.

Next mission segment was the sampling of the plume of a rapidly (20 kts
estimated) moving large container ship (stylized logo \"AP\" on side).
Plume from stack barely visible, with no obvious cloud line to rearward.
Several plume

samples acquired in passes within 50 m of surface. Thereafter passes
made at 1‑2 nm downwind. Plume intercepted in midst of or/and in Cu fra.
Marginal or no\
plume intercept near tops of Cu fra resulted in an extended southward
excursion to insure plume had not been missed. At this point location of
plume seemed to be contained within the shallow boundary layer the top
of which was marked by the\
Cu fra tops. Return pass to north was made at longer level with ship now
\> 5 nm upstream. Marginal plume intercept on this northbound pass was
in now what appeared to be an E‑W line of Cu fra. No distinct cloud
microstructural signal.

Last segment of flight was dedicated to an overpass of the Penn State
vertically‑pointed radar while in a 100 m thick layer of Sc perlucidus.
No precipitation detected in this cloud over or in the vicinity of the
radar.

**NCAR ELECTRA:** The Electra ferried out at 9000\', then descended and
started its first stack at 40°57\'N, 23°59\'W, based on inflight
information on the location of

the six balloons. Cloud top height on the first descent was 1400\',
cloud base at about 1000\'. The first set of legs were flown at 100\',
500\', 900\', 1300\', cloud-top inversion (2200\'‑2400\'), 2000\' and
6500\'. Headings were 250°, 160°, 340°, and 70° magnetic. Initial wind
from balloon was 16.8 knots at 34.2° true. Leg

length was 10 minutes for each section of the \"L\". Cloud height was
variable, and along the southern leg was clown as low as a couple
hundred feet. During the flight, the winds shifted to more northerly and
strengthened to over 20 knots. There was some very light drizzle,
particularly in the southern leg.

The second set of legs started at 40°13\'N, 23°26\'W. Leg heights were
100\', 1300\' and 1800\'. Headings were 277°, 187°, 07°, and 97°,
magnetic. Cloud height was 1900\' to 2300\', with complicated structure
at cloud base, including fog (quite thin) at the surface in the N‑S leg.
All six planned balloons were followed, and the additional balloon was
noted even before it reached its equilibrium level. Takeoff was at
16:18, landing was at 22:17.

**ARAT F-27:** Measurement of cloud radiative properties, remote sensing
with LIDAR, and coordination with ER‑2 and C‑131 with NOAA‑12.

***Date:*** 13 JUNE ***Julian Day:*** 165 ***Experiment Day:** 13*

**Mission Scientist:** Dr. Bruce Albrecht

**Mission Objective:** Second day of intensive sampling of the diurnal
variation of an air mass throughout a 48 hour period using several
aircraft, to trace the movement of the air mass.

**Mission Description:** Lagrangian mission ‑ multi‑aircraft temporally
separated.

**Synoptic Situation:** High pressure strengthening to the northwest
with increasing low level pressure gradients in the ASTEX triangle.
Overcast stratocumulus, estimated depth about 1000ft, with longer
stratocumulus obscuring Pico Alto. Occasional drizzle.

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**GENERAL, A.M. WEATHER:** 13 June 92 ‑ 12 GMT surface high position
near 35N, 30W with a 1028mb closed contour. Estimated maximum surface
sea level pressure is near 1032mb. The entire project area is now under
the influence of strong high pressure. The high is also beginning to
ridge northeastward in advance of a slowly moving cold frontal system
which extends from 45N, 40W southwestward to 30N, 60W. The combination
of the ridging of the surface high and the establishment of the heat low
over central Spain has resulted in 15‑20kt northeasterly winds in the
project area. Some regions are also experiencing gusts

to 26kts. Mostly broken to overcast (7/8‑8/8) stratocu with some
scattered drizzle and rain showers exist throughout the project area.

**NASA ER‑2:** Mission was scrubbed because conditions were
unsatisfactory for planned mission.

**MRF C‑130:** Down

**UW C‑131A:** Two facets; find ship plumes as opportunity presents,
execute flight legs above, within and below marine boundary layer at
locations indicated by trajectory analysis supplied by Bretherton.

OBSERVATIONS: Climbed out of stratocumulus vicinity SMA AP. Tops 910 mb,
droplet concentrations about 250 cm‑3. Overflew stratocumulus and
performed racetrack pattern for radiation measurement while enroute to
Lagrangian locale. Subsequently re‑entered stratocumulus deck for cloud
microstructure measurements in support of rad measurements. Tops 930 mb
and droplet concentrations about 300 cm‑3. Upon initial gradual descent
through solid stratocumulus layer intercepted strong indication of
polluted region with droplet concentrations \> 600 cm^-3^ and diminished
droplet sizes for about 20 sec, or about 2 km width. Top hat‑like
feature in droplet concentrations. Unfortunately, though this feature
was appreciated in real time, need to rendezvous at Lagrangian locale in
a timely manner precluded \"sortie\" on this strongest of all plume
signatures in\
our data.

Also of note was a decline by half in droplet concentrations in the
Lagrangian region (1105 Z) suggesting that a transition region had been
transacted. The Lagrangian region and all subsequent flights east of
that locale

was characterized by large droplet clouds and extensive drizzle regions
whereas the earlier two clouds sampled (climbout and in support of
radiation measurements enroute to Lagrangian locale, were not).

Final phase of flight was dedicated to search for a possible ship plume
northeast of the Lagrangian flight legs. However, later flight
de‑briefing revealed that a message through ATC that led the C‑131A into
that locale had been mistransmitted as a \"go for ship plume\" when in
fact the message was a \"no go, plume dissipated\" message.

**NCAR ELECTRA:** Mission 1: Since the tracking of the balloons was lost
by the C‑130\'s proceeding flight, the Electra attempted to pick up the
locations of the C-130\'s pattern and advect it downwind. We flew three
stacks and numerous soundings, navigating only by the time and heading
to remain in roughly the same air started in. \"L\" shaped legs were
flown in each stack, with an initial crosswind leg on a 270 degree
heading and then southward turn to a clown turn to a downwind leg on a
heading of 108 degrees. This orientation was only changed briefly at the
stars of the third stack.

Based on a 0420Z C‑130 report that the center of their crosswind leg had
been at 35.54N 24.02W, we began first pattern with its easternmost point
at 37.44N 23.5W. (C‑130 at this point at 0345, so Electra should have
started about 0.15 degrees farther south.) Since it was still dark, the
pilot elected not to fly\
below 1000\' with the result that the Electra was unable to get beneath
the clouds on that stack. Additional legs were flown at 1500\',
2200‑2400\' (across the inversion), and 6200\' for the LIDAR. Our
easternmost point had advected to

37.1 N 23.59W. By the end of these legs it was light enough that a slow
sounding to 100\' above the surface was taken to stars the second stack,
breaking out of the clouds at about 800\'.

Because there was fog along the track, the lowest leg was limited to
300\'. We started it 10 minutes east of the regular L, to permit an
assessment of the horizontal variability adjacent to our study area.
Unfortunately, it could not be continued 10 extra minutes to the west as
well, since Santa Maria was in the way. A lot of drizzle was encountered
on this leg, which was followed at the other end (SW) of the pattern
with a sounding up to 3500\'. Cloud tops were higher at the SW end,
around 2600\'. Legs at 100\', 1900\', 2800‑3300\' and 6000\' completed
this stack.

There was only time for three levels in the third stack, which began at
100\' and moved to 2200\' (chosen as one of the few altitudes which
would keep us in cloud at both ends of the pattern) and then 3200 to
2800\', which was just clear of the cloud above the inversion. Based on
22 degree winds at NE end of the pattern, Electra first elected to
realign this L to 15 degrees. However,

the winds at the southeast were clearly from 360 degrees, so after six
minutes the pattern was realigned. NNE winds were encountered at the
northern part of the pattern, but no readjustment was made. At the NE
corner, the azimuth was 22‑28 degrees, while it held at 360 degrees on
the SW corner. By the time of this third stack, the clouds were opening
up at the southeast end, in contras\" to the thick, continuous stratus
on the crosswind leg at the NE. Takeoff 0406 GMT Landing 1047 GMT.

Mission 2: The Electra ferried out to 34.50.1N 25.41W at 9000\' to the
research area of the Lagrangian experiment. The first leg was a 30
minute crosswind leg at 500\'. A stack of \"L\" legs were then flown at
100\', 1500\', 2600\'cloud top inversion (3,200‑3,800\'), 7000\', and
3100\'. Cloud top was about 3,500\' with two cloud layers. The base of
the primary layer was about 2,700\', but variable. The \"Ls\" were
oriented at 315‑45 degrees and 225‑135 degrees. The cloud cover at the
upper level was quite uniform, but the winds were 8‑9 MS 30‑45 degrees.

A sounding to 6,000\' was then flown, followed by an along‑wind 100\'
leg. Next \"L\'s\" were flown at 1,000\', 3,000\' and 3,400\' (just
below cloud top). The Electra then did a sounding and returned to Santa
Maria. During the flight, the winds shifted to more easterly, but were
otherwise quite homogeneous. Occasional light drizzle was common.
Although there was more than one cloud layer, the ozone and HOH profiles
show little evidence of decouping. The turbulence was quite high for
stratus, and seemed to be present at all levels. The longer clouds were
complicated in structure and not uniform. Take off 15:52 Landing 22:37.

**ARAT F‑27:** Down

**FMO Merlin IV:** Not operational

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