***Date:*** 21 JUNE ***Julian Day:*** 173 ***Experiment Day:*** 21

**Mission Scientist:** Dr. Bruce Albrecht

**Mission Objective:** Coordinated measurements of cloud microstructure.

**Mission Description:** Multi-aircraft vertically stacked with ER-2 and
C-131. Coordination with NOAA-12.

**Synoptic Situation:** Surface high located well to the north and the
west with north to northeast boundary layer flow of 10 - 1 5kts.
Continental airmass influencing the triangle.

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**GENERAL, A.M. WEATHER:** 21 June 92 - 12GMT surface high position near
53N, 20W with a 1032mb closed contour. Estimated maximum surface sea
level pressure is near 1036mb. A second high center has developed near
30N, 38W with a maximum sea level pressure of 1029mb. In between the two
high pressure centers, a surface low pressure trough extends from a
1003mb low centered near 45N, 50W southeastward to the western islands
of the Azores. The entire project area, however, remains under the
influence of strong high pressure which is ridging northeastward -across
the British Isles and southward into the Azores. The combination of the
ridging of the surface high and a developing surface low pressure trough
off the western coast of Portugal has resulted in 15kt east-northeast
winds in the far northern portion of the project area and more northerly
winds at 10-15kts over the eastern half of the triangle. Winds over the
far southern section of the triangle are northeast near 10-15kts. Just
to the east of

the project area, winds are north-northwest at 10-15kts. A large
diffluent region is evident in the surface flow from the project area
eastward to the coast of Portugal. Mostly scattered to broken (3/8-7/8)
stratocu with some scattered drizzle showers exist over the northern and
eastern halves of the project area. In addition, some altocumulus and
cirrus associated with the approaching surface low pressure\
trough 400km to the northwest of the project area are reaching the far
northern and western portions of the project area.

**NASA ER-2:** Underfly NOAA-12 and overfly C-131A (in cloud). Flew 345
km flight legs perpendicular to sun and into sun, centered at point O
(26 deg 00\' N,

23 deg 00ÕW). Cirrus layers at 35000 ft over longer broken boundary
layer clouds, especially to the west and south of point 0. Takeoff 0900
GMT Landing 1310 GMT.

INSTRUMENT PERFORMANCE

MAS OK, no problems reported or seen in quick looks. Data looks very
good. As with all previous flights, the 13 um charnels are too noisy to
be usable.

CLS Data show cirrus overlying boundary layer clouds throughout southern
and western portion of flight (35000 ft). Data look good.

EOC OK throughout flight. Data looks very good.

RADIOMETERS OK, no problems reported. Hemispheric solar flux S-20
radiometers remain clown due to lack of parts lost in shipment. Narrow
FOV radiometer data reported to be excellent.

**MRF C-130:** Down

**UW C-131A:** Coordinated measurement of cloud microstructure with
ER-2, satellite overpass, and Convair. Climb out of SMA revealed
stratocumulus tops about 4300 ft., droplet concentrations \>400 cm^-3^ .
Two cloud layers present in varying amounts. First and lowest were
scattered to broken and cumulus bases in the observation area of 2700
ft. (higher than near SMA vicinity). Top of stratocumulus varied from
4900-5100 ft. with generally higher ragged overshooting cumulus tops,
though not always the cause of the highest tops. The layer was, as often
observed, wedge-like with broad thicker and thinner regions. Thin
regions were due to stratocumulus perlucidus clouds \< 100 feet thick.
Thickest regions were due to merged cumulus/stratocumulus complex of
mesoscale dimension in which liquid water was near 1 9 m 3 for extended
periods. Droplet concentrations continued high (\>400 cm^-3^ ) with no
anomalies indicating ship tracks or transition zones.

Initially outflew heavy cirriform clouds verging on altostratus over SMA
and we were at the southeast edge of those clouds as the rad experiment
began. Thereafter, the cirriform shield, with isolated patches of
altocumulus translucidus, moved overhead from the northwest. By the time
the experiment ended, cloud cover was greater than 80% overhead. Clouds
thickened enroute to SMA. Purposely porpoised to profile liquid water in
stratocumulus while returning to SMA.

**NCAR ELECTRA:** Down

**ARAT F-27:** Down

**FMO Merlin IV:** UNK

***Date:*** 22 JUNE ***Julian Day:*** 174 ***Experiment Day:*** 22

**Mission Scientist:** Dr. Christopher Bretherton

**Mission Objective:** multi-aircraft cloud microphysics intercomparison
with the Electra and C-130. Coordination with NOAA-12.

**Mission Description:** Multiple aircraft horizontally separated.

**Synoptic Situation:** An anticyclone was situated west of Ireland and
the whole triangle was covered by northwesterly flow. Broken
stratocumulus.

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**GENERAL, A.M. WEATHER:** 22 June 92 - 12GMT surface high position near
50N, 25W with a 1032mb closed contour. Estimated maximum surface sea
level pressure is near 1033mb. A second high center has developed near
30N, 38W with a maximum sea level pressure of 1027mb. In between the two
high pressure centers, a surface low pressure trough extends from a
1004mb low centered near 45N, 50W southeastward to the western islands
of the Azores. The entire project area, however, remains under the
influence of strong high pressure which is ridging northeastward across
the British Isles and southward into the Azores. The combination of the
ridging of the surface high and a developing surface low pressure (1011
mb) off the western coast of Portugal has resulted in 15kt
east-northeast winds in the far northern portion of the project area and
more northerly winds at 10-15kts over the eastern half of the triangle.
Winds over the far southern section of the triangle are northeast near
10-25kts. Just to the east of

the project area, winds are north-northwest at 15-20kts. A large
diffluent region is evident in the surface flow from the project area
eastward to the coast of Portugal. Mostly scattered to broken (3/8-7/8)
stratocu with some scattered drizzle showers exist over the entire
project area. In addition, some altocumulus and cirrus associated with
the approaching surface low pressure trough 400km to the northwest of
the project area are located just west of the project area.

**NASA ER-2:** Underfly NOAA-12 and overfly C-130 (in cloud) along two
flight tracks over Porto Santo, one parallel to NOAA-11 (300 km) and the
other aligned into the sun (210 km). Optically thick and-broken
stratocumulus clouds observed around Madeira Islands with clear sky on
portions of transit to the Madeiras. No cirrus observed during flight.
Takeoff 1330 GMT landing 1830 GMT.

INSTRUMENT PERFORMANCE

MAS OK, no problems reported or seen in quick looks. Data looks very
good. As with all previous flights, the 13 um charnels are too noisy to
be usable. Optically thick clouds over portions of flight, with some
clear sky images of Porto Santo (95% clear). Madeira Island was 90%
cloud covered.

CLS Data show virtually no cirrus throughout flight. Data look good. As
on all previous flights, and 1.06 um charnel is affected by the
prelasing problem of our old laser. The 532 nm charnels may also stars
to be affected.

EOC OK throughout flight. Data looks very good.

RADIOMETERS OK, no problems reported. Hemispheric solar flux S-20
radiometers remain clown due to lack of parts lost in shipment. Narrow
FOV radiometer data reported to be excellent.

**MRF C-130:** A successful sortie was flown with the Electra to
intercompare cloud microphysics instrumentation. The C130 and Electra
transitted out to the operating area at FL170. The two aircraft then
performed a fork separation maneuver which resulted in the C130 and
Electra being displaced horizontally by 6nm and the C130 being 1000ft
lower than the Electra. A profile to the lowest permitted altitude (50ft
C130, 100ft Electra) was then flown through a large extensive sheet of
maritime stratocumulus. The stratocumulus deck had cumulus penetrating
the layer and in some cases rising to a few hundred feet above the main
deck. There were large changes in localized reflectance where the
cumulus clouds were influencing the droplet spectra. Around some of the
larger cumulus cells was evidence of gravity wave phenomena in the
stratocumulus tops. The cloud tops were at 4800ft with effective radii
of 10um and droplet concentrations of 150/cc, as measured by the C130,
the main cloud base was at 4000ft but there was extensive cumulus below.
Some of the Cu were large and the C-130 penetrated one cell immediately
on leaving the bottom of the main Sc deck. The base of the cumulus was
at around 2000ft at the level of decoupling.

The C130 and Electra then formatted for a turbulence inter-comparison
run at 500ft. On completion of this run, the aircraft once again
performed the fork divergence manoeuvre and carried out a second profile
through the stratocumulus deck. On this profile, neither of the aircraft
reported flying through any cumulus. Finally the Electra positioned
itself for a run in the top 1 /3rd of the cloud deck for a run across
wind which went through the area of the second profile, the C130 took up
a position along the same ground track as the Electra positioned 1000ft
above cloud. This run was extended by five minutes in order for the
Electra to penetrate a large cumulus cell which was protruding through
the Sc deck and for the C130 to look at the changes of reflectance that
occurred in the cloud top. The Electra continued in this area and
performed a vertical stack of runs. The C130 climbed away and proceeded
to a position approx 15nm upwind of Porto Santo for an island aircraft
intercomparison. The profile into this region showed that we were now in
a continental airmass. Several very distinct haze layers were observed
with very sharp concentration transitions from 100 to 2000/cc measured
by the PCASP above cloud. Cloud tops were approx 6000ft, cloud base
approx 5300ft. There was approximately 6/8 Sc cover with large amounts
of scud below the main deck. Some very small amounts of drizzle were
observed at cloud tops. A stack was flown at the following levels:
100ft - turbulence run; 3300ft - below cloud; 5400ft

\- in cloud; 5900ft - above Sc sheet; and 6900ft - above all cloud. The
cloud showed great variability in thickness along the runs, but
generally thinned out during the stack.

A profile was then flown from 7000ft to 100ft ending at a point a few
hundred meters upwind of the field site at Porto Santo, a run at 100ft
was then flown directly over the field site heading south (downwind).
The stratocumulus was by now very thin being only approx 50 - 100ft
thick. Some cumulus were observed over the island although none were
penetrated. Three runs were then flown over the field site at 800ft,
5000ft and 5500ft. During the last run, some wisps of cloud were flown
through but they hardly showed on the FSSP or Johnson Williams.

The C130 then flew saw tooths back to the advected air position of the
Electra passing once more through the transition from a continental to
maritime airmass. In the advected position, the cloud was very complex,
a stack was flown with runs at the following levels. 100ft - turbulence
run;\
2000ft - below Cu base; 3000ft - in and out of Cu; 3700ft - in and out
of Cu; 5100ft - in cloud tops; 6800ft -above all cloud; and 7000ft -
above all cloud.

At the beginning of the stack there was only a small amount of
stratocumulus remaining at the level of the inversion, but mainly only
the cumulus remained. Towards the end of the stack, the cloud appeared
to have filled in and quite extensive sheets of stratocumulus could be
seen between the cumulus cells. Finally a profile was flown to FL200 on
transit to Santa Maria. Take Off: 1035 GMT Landing: 1945 GMT.

It was not possible to calibrate the Barnes PRT4 during the flight
because of problems with the black body heater/cooler. The MARSS
radiometer was not operated.

**UW C-131A:** Examine solar radiation influence on particle production
by flying in and near clouds from pre-dawn to post-sunrise hours,
measure air mass sulphur content, perform racetrack flight pattern ontop
of radiation measurements.

The climb out of SMA revealed stratocumulus tops at 3300 ft., and
droplet concentrations of \>400 cm^-3^ indicating continental aerosol
environment. Two\
cloud layers present in varying amounts in the research area. First and
lowest was scattered cumulus clouds with bases at 2800 ft.. Bases of
higher overcast stratocumulus layer varied from 4100-4700 ft.. Top
stratocumulus layer varied from 5100-5600 ft. generally with one brief
encounter near end of experiment of top at 5900 ft.. Tops of
stratocumulus ragged. Overshooting cumulus tops

provided highest cloud top altitudes and highest liquid water contents
(to about 1 g m^-3^ near cloud top). Stratocumulus layer was, as often
observed, wedge-like with broad thicker and thinner regions. Thin
regions were characterized by stratocumulus perlucidus cloudlets \< 100
feet thick. Thickest regions were due to merged cumulus/stratocumulus
complex of mesoscale dimension. Droplet concentrations continued high
(\>400 cm^-3^) in research area with no anomalies indicating ship tracks
or transition zones, and no drizzle.

Cirrostratus clouds moved overhead during return leg to SMA. Purposely
porpoised to profile liquid water in the plethora of stratocumulus while
returning to SMA.

**NCAR ELECTRA:** Micro-P intercomparison with C-130.

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***Date:*** 23 JUNE ***Julian Day:*** 175 ***Experiment Day:*** 23

**Mission Scientist:** Dr. Bruce Albrecht

**Mission Objective:** Radiometer intercomparison and cloud
microstructural measurements in the boundary layer with an inhomogeneous
cloud layer.

**Mission Description:** Multi-aircraft vertically stacked.

**Synoptic Situation:** A high pressure system was centered over Ireland
and a weak ridge

extended clown east of Santa Maria, causing the winds to be light and
variable. The ridge was slowly moving eastwards as a low pressure system
advanced from the west. Overcast stratocumulus and isolated underlying
cumulus.

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**GENERAL, A.M. WEATHER:** 23 June 92 - 12GMT surface high position near
46N,24W with a 1024mb closed contour. Estimated maximum surface sea
level pressure is near 1026mb. A second high center is located near
28N,46W with a maximum sea level pressure of 1025mb. In between the two
high pressure centers, a surface low pressure trough extends from a
1005mb low centered near 40N,50W southeastward to the western islands of
the Azores. A weak ridge still exists from the high to the north of the
region southward into the eastern islands. This ridge is weakening and
slowly moving eastward. Winds over the far northern half of the triangle
are east near 10 kts. Winds over the southern half of the triangle as
well as to the east of the project area, are more northeasterly to

northerly at 10-15 kts. -Mostly scattered to broken (3/8-7/8) stratocu
with some scattered drizzle showers exist to the northeast of the
project area. Because of the presence of the ridge axis through the
middle of the triangle, very few clouds are present. In addition,
multilevel clouds and rain showers associated with the\
surface low pressure center are being observed in the western islands of
the\
Azores.

**NASA ER-2**: Coordinate overflight of C- 130, C- 131 A, and Electra
along three parallel 245 km flight legs displaced 10 km apart. Flew 273
km flight leg into sun (heading of 256.3 deg), followed by a 383 km
flight leg parallel to NOAA-11\
ground track. Pilot reported approximately 30% cloud cover along portion
of flight coordinated with the boundary layer aircraft, and 60% cloud
cover along NOAA-11 ground track. No cirrus clouds observed during
flight. Takeoff 1400 GMT Landing 1730 GMT.

INSTRUMENT PERFORMANCE

MAS OK, no problems reported or seen in quick looks. Data looks very
good. As with all previous flights, the 13 um charnels are too noisy to
be usable. Broken stratocumulus throughout mission.

CLS Data show low stratocumulus clouds throughout much of the flight.
Data look good. As on all previous flights, and 1.06 um charnel is
affected by the prelasing problem of our old laser.

EOC OK throughout flight. Data looks very good.

RADIOMETERS OK, no problems reported. Hemispheric solar flux S-20
radiometers remain clown due to lack of parts lost in shipment. Narrow
FOV radiometer data reported to be excellent.

**MRF C-130:** A successful flight was carried out to the east of Santa
Maria, using three aircraft vertically stacked in the boundary layer and
a fourth aircraft at high level. The AVHRR pictures before take-off
indicated that an inhomogeneous cloud layer was moving slowly down from
the northeast and it was decided to investigate this structure.

The transit out to the area showed thin patches of stratocumulus, mostly
with large cumulus tops poking through. Variations in cloud top
brightness were seen which were thought to be associated with the
presence of cumulus below the stratocumulus. The initial profile to the
chosen point A showed a haze layer at around 11,800ft with aerosol
concentrations of around 800 cm^-3^ . The profile passed over various
patches of Cu/Sc and some cumulus tops were seen to rise up to 8000ft.
The inversion height was around 5,800ft, but in this area cloud tops
were irregular, being mostly composed of cumulus.

Winds in the boundary layer were found to be light and variable, so a
stack was set up east-west with 26 minute runs. The Electra flew at
5000ft whilst the C‑130 coordinated with the C-131 for a run in cloud
with the C-131 above cloud, and a run above cloud with both aircraft.
the run in cloud started in cumulus tops and then entered a clear zone.
When the edge of the next stratocumulus patch was reached, the inversion
was found to be lower, but the cloud here was much more uniform, though
thin, except in a more turbulent region where the cloud was thicker and
droplets larger. This is thought to have been an area of cumulus
penetration. The run above cloud verified this.

The C-131 then left the area and the C-130 coordinated with the Electra
for the rest of the stack. The Electra flew at 100ft, whilst the C-130
flew at 600ft and then the Electra remained at 5000ft while more runs
were completed by the C-130 at higher levels. The cloud remained patchy
with thin stratocumulus seeming to be all associated with spreading
cumulus tops, and virtually all the medium to large sized cumulus were
seen to have sheared tops. However, the presence of cloud appeared to
increase the thickness of the surface layer, such that the run at 2000ft
passed from the surface layer to the subcloud layer when going from a
cloudy to a clear area.

During this stack, aerosol concentrations below cloud remained between
100 -130 cm^-3^ , although a ship passed close to point A and caused a
rise in aerosol concentration to 350 cm^-3^ . Droplet concentrations
were around 120 cm^-3^ with effective radii 6 - 10 microns.

The C-130 moved northwards to try to locate an area of more uniform
stratocumulus. A fairly large sheet was found, in which a vertical stack
was completed with 10 minute legs. The cloud layer thickened as an area
of cumulus was approached which was spreading out under the sheet. Also,
the droplets in the thicker area of cloud were found to be larger than
those near the edge of the sheet. A stable layer was observed to be at
about 3,200ft, and gravity waves were seen at this level. The top of the
surface layer was again higher beneath the thicker cloud region.

There appeared to be some kind of disturbance in the inversion just at
the edge of the cloud sheet. However, this region had similar
characteristics to that sampled earlier, so the thicker cloud area had
actually drifted back northwards under the influence of southerly winds
in the afternoon.

It was not possible to calibrate the Barnes PRT4 during the flight
because of problems with the black body heater/cooler. The MARSS
radiometer was not operated.

**UW C-131A:** Coordinated flight with Electra and C-130 for the purpose
of radiometer intercomparisons and cloud microstructural measurements.
Ship plume sampling as opportunity presents following intercomparison.

The climb out of SMA revealed stratocumulus tops 38, and droplet
concentrations about 300 cm^-3^, indicating a return to a more maritime
aerosol environment. Two cloud layers present in varying amounts in the
research area. First and lowest was scattered cumulus clouds with bases
at about 20 (not sampled). Bases of stratocumulus layer varied from
50-55. Overshooting Cu tops reached 65 in N-S enroute to radiometer
calibration legs with nearly 2 9 m^-3^ liquid water content and RWU.
Stratocumulus layer was, as often observed, wedge-like with broad
thicker and thinner regions. Thin regions were characterized by
stratocumulus perlucidus cloudlets \< 200 feet thick. Thickest regions
were due to merged cumulus/stratocumulus complex of mesoscale dimension.
Droplet concentrations were more maritime, about 200 c^-3^ .

Enroute to radiometer calibration leg, cloud top brightness anomaly
overflown indicating possible ship track. Following radiometer
intercomparison, returned to vicinity of this tentative plume flying
in-cloud for an extended period in an attempt to intercept these
features. No apparent intercepts.

Next, low level passes near the surface to 7 were made in the stack
effluent from a medium-sized tanker. Sampling interrupted by tandem
passage of C-130 and Electra over ship at 5 and 20. No suspicious clouds
were visible downwind from this ship. Sky condition was widely scattered
Cu and broken Sc per.

**NCAR ELECTRA:** (up) MAVS with C-130, C-131.

**ARAT F-27:** Mission aborted because of an engine failure.

**FMO Merlin IV:**

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***Date:** 24* JUNE ***Julian Day:*** 176 ***Experiment Day:*** 24

**Mission Scientist:** Dr. Bruce Albrecht

**Mission Objective:** NCAR Electra FSSP and MRF C-130 intercomparison
on the C-130.

**Mission Description:** Single aircraft mission with the C-130.

**Synoptic Situation:** A high pressure system was centered over the
U.K. and a weak ridge extended east of Santa Maria. A low pressure
system and its associated fronts was moving in from the west and the
surface winds were increasing from\
the south.

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**GENERAL, A.M. WEATHER:** 24 June 92 - 12GMT surface high position near
45N,18W with a 1020mb closed contour. Estimated maximum surface sea
level pressure is near 1023mb. A second high center is located near
28N,50W with a maximum sea level pressure of 1023mb. In between the two
high pressure\
centers, a surface low pressure trough extends from a 1001mb low
centered near 41 N,40W southeastward to the western islands of the
Azores. A weak ridge still exists from the high to the northeast of the
region southward to near Porto Santo. This ridge is weakening and slowly
moving east. Winds over the western half of

the triangle are south-southeast near 25 kts in response to the strong
low pressure to the northwest of the region. Winds over the eastern half
of the triangle as well

as to the east of the project area, are more easterly at 10-15 kts.
Mostly scattered to broken (3/8-7/8) stratocu with some scattered
drizzle showers exist to the northeast of the project area. Otherwise,
multilevel clouds and rain showers associated with the surface low
pressure center are being observed in the far western portion of the
project area.

**NASA ER-2:** Down

**MRF C-130:** A successful flight was carried out to the south east of
Santa Maria with the NCAR FSSP and the C-130 FSSP mounted on the pod
under the port\
wing; both being recorded on the SEADAS. Earlier in the detachment
significant differences were observered between the FSSP results from
the Electra and the C-130 and it was decided to mount them both on the
same aircraft to find out if it was a hardware or analysis problem. Low
pressure systems were approaching from the southwest so it was decided
that only a short flight in the morning was advisable. The satellite
picture showed a thickening of cloud to the north west and the southwest
of Santa Maria with a large cirrus shield to the north. It was

decided to work to the southeast where broken stratocumulus cloud was
apparent.

On the transit out to the area the low cloud amounts decreased as we
moved southeastwards until there were large gaps in the cloud below. A
large patch of stratocumulus was chosen to work in and a profile was
carried out through 10,000ft to 500ft. The boundary layer was found to
be very deep with the stratocumulus and cumulus clouds with bases around
3200ft.

Following the profile the aircraft ascended to the top of the
stratocumulus layer and carried out a race track at 6,300ft skimming the
cloud tops with one leg at 180kt IAS and the other at 200kts IAS (the
two air speeds were chosen as these are representative of the speeds the
two aircraft fly at). Each leg had to be

foreshortened as the aircraft flew through a sharp edge to the
stratocumulus sheet. A second similar race track was flown at a lower
level in the cloud at 6,100ft. Unfortunately as the real time processing
is only set up to analyze one FSSP it was impossible to compare the two
probes results during the flight. However, it did appear that both
probes were working and data was recorded.

Once the runs in cloud were completed a run at 7,300ft was flown with
the MCR looking down while over cloud and looking up when beyond the
edge of the cloud. This was done to gain another independent value of
the effective radius by remote methods. A slow, 200ft/min profile was
then flown through the stratocumulus layer to 5,800ft where a straight
and level run was done to fill the alleviator and take a CCN sample.

The aircraft then descended to sample the lower layer of the cloud in
the boundary layer which was more convective in nature. Here further
straight and level runs were flown through the cloud at 180 and 200kts
IAS at 3,600ft and 3,100ft.

At times in these runs the cloud became very thin and it almost appeared
like a thick haze layer. There appeared to be some discrepancy in these
areas between the total counts measured by the two probes.

A porpoising run was then flown through the stratocumulus at the top of
the boundary layer. The sortie was completed with a series of sawtooths
back to Santa Maria sampling as much cloud as possible. The SEADAS was
left on during landing as in the approach to the airfield the cloud
began to thicken up. Takeoff 1037 GMT Landing 1340 GMT.

It was not possible to calibrate the Barnes PRT4 during the flight
because of problems with the black body heater/cooler. No filter samples
were taken during the experiment.

**UW C-131A:** Down

**NCAR ELECTRA:** Down

**ARAT F-27:** Down

**FMO Merlin IV:** Down

***Date:*** 25 JUNE ***Julian Day:*** 177 ***Experiment Day:*** 25

**Mission Scientist:** Dr. Bruce Albrecht

**Mission Objective:** Down day

**Mission Description:**

**Synoptic Situation:** A high pressure system was centered over the
U.K. and a weak ridge extended clown east of Santa Maria. A low pressure
system and its associated fronts were moving in from the west and the
surface winds were increasing from the south.

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height="2.376388888888889in"}

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height="1.9027777777777777in"}

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height="5.692361111111111in"}

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height="8.35138888888889in"}

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height="4.0152777777777775in"}

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height="4.108333333333333in"}

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height="3.1840277777777777in"}

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height="7.332638888888889in"}

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height="8.276388888888889in"}

**GENERAL, A.M. WEATHER:** 25 June 92 - 12GMT surface high position near
45N,10W with a 1020mb closed contour. Estimated maximum surface sea
level pressure is near 1023mb. A second high center is located near
28N,50W with a maximum sea level pressure of 1025mb. In between the two
high pressure centers, a strong surface low pressure center (998mb) near
42N,30W is controlling the weather in the Azores and in the project
area. Winds over the triangle are south to southwest near 25 kts in
response to the strong low pressure to the northwest of the region.
Multilevel clouds and rain showers (and gusts to 45 kts) associated with
the surface low pressure center are being observed over the western half
of the project area.

**NASA ER-2:** Down

**MRF C-130:** Returned to United Kingdom. End of ASTEX involvement.

**UWC-131A:** Down

**NCAR ELECTRA:** Down

**ARATF-27:** Down

**FMO Merlin IV:** Down

Page 270 intentionally blank.

***Date:*** 26 JUNE ***Julian Day:*** 178 ***Experiment Day:*** 26

**Mission Scientist:** Dr. Bruce Albrecht

**Mission Objective:** Down day

**Mission Description:**

**Synoptic Situation:** A high pressure system was centered over the
U.K. and a weak ridge extended clown east of Santa Maria. A low pressure
system and its associated fronts were moving in from the west and the
surface winds are from\
the south.

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height="2.5541666666666667in"}

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height="2.3201388888888888in"}

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height="3.957638888888889in"}

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height="8.32986111111111in"}

**GENERAL, A.M. WEATHER:** 26 June 92 - 12GMT surface high position near
45N,10W with a 1020mb closed contour. Estimated maximum surface sea
level pressure is near 1023mb. A second high center is located near
28N,50W with a maximum sea level pressure of 1025mb. In between the two
high pressure centers, a strong surface low pressure center (996mb) near
45N,30W is controlling the weather in the Azores and in the project
area. Winds over the triangle are south to southwest near 25 kts in
response to the strong low pressure to the northwest of the region.
Multilevel clouds and rain showers (and gusts to 30 kts) associated with
the surface low pressure center are being observed over most of the
project area.

**NASA ER-2:** Stand-down ASTEX

**MRF C-130:**

**UW C-131A:** Down

**NCAR ELECTRA:** At Lajes.

**ARAT F-27:** (up)

**FMO Merlin IV:** Returned to France. End of ASTEX involvement.

***Date:*** 27 JUNE ***Julian Day:*** 179 ***Experiment Day:*** 27

**Mission Scientist:** Dr. Donald Lenschow

**Mission Objective:** Measure DMS, sulphur profile in a clear sky
region.

**Mission Description:** Multi-aircraft temporally separated.

**Synoptic Situation:** Surface low to the north weakening and gradually
drifting to the north. Cold low aloft with cyclonically-curved flow
aloft. Towering cumulus, and\
a cumulus congestus line near Santa Maria.

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height="2.7645833333333334in"}

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height="2.4715277777777778in"}

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height="1.9729166666666667in"}

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height="8.349305555555556in"}

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height="3.6243055555555554in"}

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height="8.111805555555556in"}

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height="7.444444444444445in"}

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**GENERAL, A.M. WEATHER:** 27 June 92 - 12GMT surface high position near
35N,15W with a 1020mb closed contour. Estimated maximum surface sea
level pressure is near 1021mb. A second high center is located near
28N,50W with a maximum sea level pressure of 1023mb. In between the two
high pressure\
centers, a strong surface low pressure center (1001mb) near 45N,31W is
controlling the weather in the Azores and in the project area. Winds
over the triangle are south to southwest near 25 kts in response to this
strong low pressure to the northwest of the region. Multilevel clouds
and rain showers (and gusts to\
30 kts) associated with the surface low pressure center are being
observed around the low as well as along a frontal boundary which
extends from the center of the low to just west of Porto Santo and into
the southern portion of the project area. Behind this front, mostly
clear skies are being observed.

**NASA ER-2:**

**MRF C-130:**

**UW C-131A:** Measure DMS, sulphur profile. Boundary layer was
well-mixed to at least 800 ft, Cu bases 1300 ft, tops 8000 ft. Sampled 5
levels for DMS, 3\
levels for SO2 on legs transverse to wind direction.

**NCAR ELECTRA:** The Electra took off at 10:52:10 with the intention of
heading for a clear area to do a chemistry mission. Earlier the C-131
had flown in the vicinity of 35^o^N26\'W, but the region was not as
clear as the area to the west, as noted by satellite. We therefore
headed for the area around 37^o^33\'N, 27^o^02\'W. This region remained
clear all during the flight. After the descent into the area, we
conducted crosswind legs 20 minutes in length oriented N-S. Levels were
flown at 100\', 800\' and 2000\'. We then conducted a sounding up to
8000\' and back to 100\' then repeated flight legs at 100\' and 800\'.
Because of a possible fuel leak,\
we curtailed the mission and flew legs at 500\' and 100\'. The lest leg
at 100\' was extended to 25 minutes. We then did a sounding on ascent to
ferry back to Santa Maria up to 10000\'. Just before landing, we
penetrated a few cumulus in the vicinity of Santa Maria. The turbulent
boundary layer extended to about 2000\' and the trade inversion was at
about 6000\'. Landing was at 15:22.

**ARAT F-27:** (up)

**FMO Merlin IV:**