Winds decreasing after 2 days of moderate (10-20 knot) winds out of the SSW. Morning winds currently 6 knots and shifting from SW to NW. Seas decreasing from 6 feet to 4.5 feet. Good visibility due to NWerly flow aloft. Forecast call for continued light winds (5-10 knots) and veering from N to S and back to N over the course of the day.
Meeting between Vickers, Edson, UCI, and CIRPAS team at house in Chatham to discuss joint operations between ship and Pelican aircraft. Discussion included:
1. The CIRPAS aircraft is the rear-propeller driven Pelican. It has orange/white Coastguard-like markings.
2. Nobska should have aboard a VHF Aviation radio to communicate with Pelican pilots.
2. Position information will be communicated in feet for altitude and degrees, decimal minutes for latitude/longitude.
3. In an SOS situation the Pelican will use marine band channels 16 and 19.
4. The Pelican flights are limited to 5 hours total. With a 1 hour taxi out and back that leaves 3 hours for missions on site.
5. The Pelican will require downtime for mandatory maintenance after 100 flight hours. If we are able to fly 5 days out of 7 or 25 hours per week (this would be a very good summer), the flights can continue for 4 weeks. Attempts will be made to maintain the plane during the 100 hours to utilize days that are of least interest to science. However, this will require coordination with and help from the scientists.
5. We have 5 flight scenarios mapped out for the IOP:
PELICAN FLIGHT PLANS FOR CBLAST JULY-AUGUST 2003
A. Assume 55 m/s ground speed, 30-sec U turns, and 30-m is lowest level
B. Total flight no more than 5 hrs
C. We will sacrifice the best absolute humidity measurement (slow response chilled mirror) and use a climb rate of approximately 4 m/s for profiles, equivalent to moving 8 km in the horizontal to climb from surface to 600 m. Actually climb rate will be determined during test flights.
D. Flights would be coordinated with ships (Nobska and possibly Asterias) with flux package and surface sampler, and IR camera on Cessna
Priority 1: Low winds (<10 knots, 5 m/s) expected for 2-3 days with strong SST features. Coordinated with Nobska and Cessna.
GOAL: Surface heterogeneity, internal boundary layers
WHEN: SST front identified with light winds perpendicular to front
TRACK: 50-km perpendicular to SST front, 25-km over warm and cold sections
SEQ: a) 2 passes at 30-m altitude, alternate heading
b) 2 passes at 60-m altitude, alternate heading
c) Profile at warm end of track, sfc to 600-m
d) Profile at cold end of track, sfc to 600-m
e) Repeat (a-e)
TIME: 430 km, 130 min
Priority 2: Low winds (<10 knots, 5 m/s) expected for less than 2 days or extended period of low winds without obvious SST features. Coordinated with Cessna (and possibly Nobska if on site). This will be the default mapping sequence.
GOAL: Spatial variation of fluxes and vertical structure
WHEN: Default anytime pattern, strong winds ok
TRACK: 50-km north-south, from Vineyard to south over ASIT
SEQ: a) 2 passes at 30-m altitude, alternate heading
b) 2 passes doing sawtooth profiles from sfc to 600-m altitude (get 6 profiles in 50
km horizontal distance)
c) Repeat (a-b) with legs along 70.5, 70.6, 70.7
TIME: 400 km, 120 min
Priority 3a: Low to moderate winds (<30 knots, <15 m/s) out of the south.
GOAL: Stable boundary layer mapping and low-level jet
WHEN: Warm air advection from southwest, moderate winds are ok
TRACK: 80-km east-west lines located 10, 25, and 40 km south of Vineyard
SEQ: Where ... = 10-km segment at 30-m alt for flux
and /\ = sawtooth up/down from sfc to 600-m
a) Fly the three tracks, progressing north to south
b) Repeat, progressing south to north
TIME: 480 km, 145 min
Priority 3b: Low to moderate winds (<30 knots, <15 m/s) out of the south.
GOAL: 3. Flux divergence over tower
WHEN: To be determined from Jim Edson's preliminary analysis of ASIT data
TRACK: 10-km east-west, parallel to shore, over ASIT
SEQ: a) Slant up and slant down profiles to find BL depth
b) 3 passes at 30-m altitude, alternate heading
c) 3 passes at 1/2 Zi, alternate heading
d) 3 passes at Zi, alternate heading
e) Repeat (a-d)
TIME: 212 km, 64 min
Priority 4: Low to moderate winds (<30 knots, <15 m/s) out of the south.
GOAL: Evolution of stable boundary layer and low-level jet
WHEN: Warm air advection from southwest, SBL, low-level jet
TRACK: Begin 10-km south of Vineyard and fly into the SW wind
SEQ: Sawtooth up/down from 30-m to above SBL (~200-m) in upwind direction
TIME: Indefinite (radio range could be a problem here)
Priority 5: South or SW wind, any wind speed (low to moderate wind speed preferred).
GOAL: Spatial variation of fluxes and boundar layer vertical structure upwind of Nantucket Island
WHEN: When feasible, strong winds ok
TRACK: 50-km northeast-southwest, from the closest point upwind of the
Nantucket mast (41.24N, 70.11W) allowed by FAA regulations
SEQ: a) Sawtooth profiles from surface to about 600 m (use 800 ft/min climb rate to get
6 profiles in 50 km horizontal distance). (16 min)
b) one pass at 30-m altitude. (16 min)
c) One pass at 100 m altitude (16 min).
d) One pass at half of the boundary layer height (if boundary layer height can be
identified from real-time monitoring), 300 m if boundary layer height is not
known. (16 min)
e) One pass right below the boundary layer top (if boundary layer height can
be identified from real-time monitoring). 500 m if boundary layer height is not known. (16 min)
f) 1 pass sawtooth profiles from sfc to 600 m (or identified boundary layer top plus 50 m using a slow climb rate of 500 ft/min. Should be able to get about 4 soundings within a 50 km distance. (16 min)
repeat b)-f) is time allowed.
TIME: 96 min
Winds remain light at 9am, currently 5-10 knots out of the E, but veering to S. Seas down to 3.5 feet and decreasing. Light rain falling. Edson and Veccione in Nantucket to assist Q. Wang with field deployment. CIRPAS and IR groups continue preparations in Chatham. Weller continues preparations for weekend departure aboard Nobska.
IR system mounting is complete and the system passed all tests successfully. Ready for first flight.
Light winds (2-10 knots) out of the S backing to the E over the course of the day. Seas down to 2-3 feet mainly in swell from S. CIRPAS Pelican and Cessna IR aircraft conduct test runs offshore with good visibility. Edson and Stanton work on ASITower. Weller continues preparations aboard the Nobska with Zappa/Jessup (IR radiometers) and Edson (flux package) for Saturday departure.
Nantucket mast deployed. Flux sampling at 10 and 20 m and mean measurements at 5, 10, and 20 m on the mast will be continuous until Aug. 26.
First flight of IR system on Cessna. Completed our standard north-south mowing the lawn pattern to cover the CBLAST study site. Observations of fine-scale structure throughout the CBLAST site. Our altitude throughout the flight was roughly 8500'.
Light winds (5-15 knots) out of the E with good visibility. Seas down to 2-3 feet mainly in swell from S.
Vickers, Edson, Khelif, CIRPAS and Cessna teams meet in Chatham to discuss coordinated operations. Decide that Priority 2 runs will be default operations with Cessna mapping SST structure around offshore buoy array and Pelican mapping flux variability and ABL structure along three lines along longitudes 70.5, 70.6 (ASIT), and 70.7. Weller continues preparations aboard the Nobska with Zappa/Jessup (IR radiometers) and Edson (flux package) for Saturday departure.
Forecast call for southerly winds varying from 5-20 knots through mid-week with periods of rain, fog and haze in persistent southerly winds.
Nantucket sodar starts to operate. Rawinsonde sounding made 4 times a day.
Second flight of IR aircraft. We were unable to get out to the CBLAST site due to the low level clouds/fog rolling in south of Martha's Vineyard. Therefore, we flew due East of Chatham to chase some interesting surface slick features. The altitude was roughly 2800'.
Haze, fog, and rain over the region.
No flights due to inclement weather. Saturday and the next few days look the same. We will try to get out whenever possible and are on call continuously.
Nobska heads off to CBLAST site and successfully deploys all 10 light moorings.
~10:30 local time leave dock
13:45-19:20 Deploy L1 through L10. CTD, bucket SST, and handheld met samples taken at each station.
21:40-01:09 CTD section, L1 to ASIT (details on p.8 of cruise log).
Nobska crew deploys 5 drifters. The tow chain was placed in the water, and the Nobska tried to follow a loose box around the drifters. Drifters moved towards SW.
~01:30-10:00 local time on station near ASIT, bow-into-wind for flux system comparison
11:42:00 Time spike for instrumentation (thoroughly wet at 11:42:20).
11:58:20 End time spike (all instruments on deck at 11:58:29).
12:28-13:15 Deployment of D1-D3 for experiment #1. CTD taken.
14:16-14:30 Loading instruments on boom chain, 1 m spacing (configuration details on p.11 of cruise log).
15:46-15:55 Boom snags lobster trap. Recover boom chain.
16:51-17:25 Deploy D4 and D5 for experiment #1.
17:37 Deploy boom chain (1 m spacing)
Drifters recovered on Monday morning. Weather on Monday am is often sunny with winds near 10 knots. However, patches of fog and precipitation and generally low ceiling keeps aircraft from flying over the course of the day.
Forecast calls for continuation of southerly flow with very humid air over the course of the week.
Nobska contines ops.
10:15-10:55 local time Recover drifters.
12:42-14:50 Deploy drifters D1-D4 for experiment #2 (deployed in a N-S line between moorings F and A).
15:14 CTD taken (cruise log p. 17)
15:45 Deploy boom chain near mooring A (1.5 m spacing)
18:25 Remove top 3 instruments from boom chain (because of shallow water).
19:05 Remove next 3 instruments from boom chain (because of shallow water).
19:29 Remove next 3 instruments from boom chain (because of shallow water).
~22:40 Adding instruments to boom chain (see cruise log p.19).
21:55 Recover boom chain.
22:43-01:29 Recover drifters D1-D4 (end experiment #2).
No flights due to low visibility and/or low ceiling.
Nobska reports that it is raining offshore at 7 am with winds around 10 knots, low fog, and low visibility. They have deployed drifters in a loose circle around mooring E. They will drive around this circle with the thermistor chain deployed.
01:50-8:50 local time boom chain section A-E
9:05-10:00 Deploy drifters D1-D5 (begin experiment #3).
10:15 CTD (cruise log p.24)
10:27 Deploy boom chain (1 m spacing?). Added/removed instruments (see log p.24-25).
22:08-22:22 Recover/redeploy boom chain because of snag. 3 instruments removed 00:27.
Nobska finished 24 hour drifter experiment this morning. They ill deploy tow chain with instruments every 1/2 meter and do transects from tower offshore and back several times today. Plan to look for slicks on Thursday. Will return to Woods Hole Friday at 8am to dump data and turn around instruments.
07:20 local time Chain recovered (with lobster pot).
8:30-9:50 Recover drifters (end experiment #3)
11:44 Begin boom chain tow (0.5 m spacing). “Radiator” transects.
A look at the COAMPS forecast calls for more of the same for
today and tomorrow:
Wednesday, Winds at 10-15 knots out of the S
Thursday, Winds at 20-8 knots out of the S
However, the eta model is currently showing a region of light and variable winds over the CBLAST site starting on Thursday morning. The forecast for Thursday, calls for winds start at 10 knots out of the S, becoming light and variable. By Friday morning, the winds are predicted to blow from the ENE at 5-10 knots. These conditions and the shift in the winds are associated with a a strong band of precipitation that is predicted to sit just to the SE of our site. Therefore, its not clear if this will allow for overflights. It will be interesting to see what the new COAMPS run looks like.
The long range forecast from MRF indicates that we will finally break free of this pattern by Monday morning, when the low finally moves to the NE of us, which will bring periods of W or even NW flow. By Tuesday, the chance for dryer air from a W-NWerly flow is even clearer. This is obviously long range, but the ECMWF model is similar, so we may get out of this soup yet.
Therefore, Nobska crew may want to rest up this weekend and look to head out on Monday or Tuesday depending on how the forecast shapes up over the weekend.
Nobska contines ops.
16:42-18:13 local On station at ASIT for flux comparison, bow-into-wind. Reposition 17:05-17:10 (not bow-into-wind).
18:13 Recover boom chain.
20:17-21:09 Deploy drifters D1-D5 (begin experiment #4, surrounding mooring A).
21:10 Deploy boom chain (1.5 m spacing). Tow around drifters.
Nobska contines ops.
6:30 local time recover boom chain.
6:57-8:00 Recover drifters D1-D5 (end experiment #4).
11:40 Arrive at Woods Hole.
The weather pattern driving southerly flow with high humidity remains entrenched. Long range outlook now looks like a break in this pattern will occur midweek. Present plan is for Nobska to head out on Tuesday evening to be on station for Wednesday.
Partly sunny skies. Winds decrease to 2-12 knots. However, swell holds at 5 feet.
Pelican had 3-hour flight today with take off at 2:44 pm local time.
1. The IR SST sensor went bad on the ground test just before the flight so there is no SST measurement from today's flight (030812). We choose to fly without this critical measurement since we we were not able to fly since July 31. After the flight we determined that the unit is out of service and replaced by our spare Heiman KT19.85. We had to take the nose fairings and nose apart.
2. The DAQ card on one of the two redundant data system computers failed during the flight but no data was lost thanks to redundancy. This card was replaced after the flight.
3. The flight had to be cut short due to low clouds and worsening conditions at Chatham airport. As a result, the western N-S flux leg
was not flown. Time series plots and track plots can be found at:
The 1-Hz and 4-Hz data subsets s_030812_ascii.txt and m_030812_ascii.txt are in:
Nobska heads back to CBLAST site. Mytillus conducts CTD transects while Edson and Crofoot work on ASIT. No aircraft operations due to very foggy conditions.
Visibility begins to improve.
Asterias deploys surface sampler.
The Pelican took off at 9:04 am today. Given the NNW winds we are flying the default "mapping" pattern as in flight 030731. The IR Cessna took off at about 8:35.
The AM and PM Pelican flights are identified as 030814_1 and 030814_2. Take off – landing were at 1305-1645 and 1934-2253 UTC for the two flights. The data from both flights are of good quality and all instruments worked well.
Plots and data subsets from both flights are in:
The default mapping pattern was flown on 030814_1. An SST front was clearly identified confirming the observations of the IR aircraft (see the crude SST map obtained from the Pelican SST observations in file 030814_2_map_sst.jpg) . Given that the boundary was very low especially towards he northern part of the track (below 30 m at times) the second flight, 030814_2, was a combination of the default mapping pattern and the SST front pattern. There was no point in making runs at an elevation higher than the minimum 30-m level because of the low BL.
The IR aircraft flew twice today. The first flight
lasted from 1240 to 1500 UTC and covered our new condensed flight track of the
CBLAST region. The data show strong temperature gradients beginning near
shore and increasing temperature offshore by 3 degrees C (I will send
temperature maps separately to Jim Edson for the website). We were able
to fly over the Nobska a few times, but were not able to establish
communication. The second flight lasted from 1800 to 2100 UTC. The
data again showed significant offshore temperature gradients from 2 to 3
degrees C. During this second flight, we were able to establish communication
with the Nobska. We suggested waypoints for the deployment of their
drifters and flew North-South tracks over their position for several legs.
All in all, a very successful day. We are planning an early morning flight... 0530. More updates to come.
The beam for the oceanographic turbulence measurements is successfully deployed in calm seas this morning. Sea less than 1.5 feet during most of the day. Winds range from 2-8 knots at W to NW and then veer to S into the evening.
Asterias deploys surface sampler. Obvious slicks throughout CBLAST array.
The Pelican took off at 14:15 UTC (10:15 Eastern) for today's flight.
FLT 030815: The Pelican took off at 1415 and landed at 1819 UTC. This was also a combination of the default mapping pattern and the SST gradient pattern. The SST feature was described by Haf Jonsson as a warm blob of water in the middle of the mapped area. The BL height was considerably higher over the warmer water. The crude SST map (ps or PDF file: 030815_map_sst) obtained from the Pelican measurements seems to agree with Haf's description. Where the height of the BL permitted, a 45-m and 60-m legs were flown above the 30-m leg.
This was again a succesfull day and all instruments worked well. The aircraft itself had a little problem. The outer flaps were stuck until 1/3 rd way into the mission when they suddenly came out during a 100' leg. The aircraft pitched up suddenly but everything is fine. This has been fixed now and we will be flying tomorrow . The vertical wind does not seem to be affected by it as pitch and angle of attack changes are accounted for by the wind equations.
As usual, plots and data can be found at:
The IR aircraft flew twice Friday (8-15-03). The first flight was early morning and lasted from 0950 to 1230 UTC. The data show a warm mass of 23-24 degree water that extends from the Southwest region of the CBLAST site to the Northeast (see temperature maps on the website). The second flight lasted from 1915 to 2245 UTC. The data showed that the warm pool moved slightly Nothward and its temperature was over 25 degrees C. The mean temperature of the region warmed by 1.5 degrees C. However, the Northwestern section of the region warmed nearly 2.5 degrees C as opposed to the Southeastern section that warmed less than a degree C. It will be important to determine the role of advection of water masses when comparing the relative warming within the region. During this second flight, we made numerous passes along a North-South track over the Nobska for process study of the frontal features observed in the IR imagery.
SWerly winds at 8 increasing to 14 knots in advance of front. Seas build from 1.3 to 3 feet during this period.
FLT 030816: The Pelican took off at 1305 and landed at 1625 UTC. The flight had to be cut short as low clouds started to form and the horizon became elusive. As a results no flux leg was flown above 30 m. It was again a combination of the default mapping pattern and the SST gradient pattern. The SST pattern observed on yesterday's flight has evolved with the warmest SST tongue extending all across the central mapped area and the coldest waters moving in the south east corner of the mapped area. (Refer to the SST maps 030815_map_sst and 030816_map_sst). Plots of 40-Hz time series of T, q, w show that turbulence is abruptly suppressed as the aircraft moves from the warm to the colder waters.
This was again a succesfull day and all instruments worked well.
As usual, plots and data subsets can be found at:
The forecast predicts rain for tomorrow. The aircraft needs to have the 50-hour inspection done, so if we do not fly the off could be used to perform the inspection.
The IR aircraft attempted two flights Saturday, 8-16-03. Following both takeoffs at 1300 and , the pilot determined that the severe haze and low clouds developing would make it difficult to safely complete the IR aircraft operations at the CBLAST study site . In both cases, we turned back to and landed at Chatham airport.
Rain falls from noon throughout the afternoon. ASIT crew works through rain to get profile array up on tower and install boom and crossarm. Profiling mast is secured across deck. No flights due to poor weather.
Mytillus crew deploys ocean profiler and BADCP on bottom. Asterias deploys surface sampler.
FLT 030818: The Pelican took off today at 1324 and landed at 1738 UTC.
This very succesfull flight mapped the SST field (see 030818_map_sst) revealing a tongue of cold water extending across the central part of the mapped area. The largest SST gradient (> 6 deg) was observed at the southern end of this cold tongue where it meets the southern warmest waters. Haf detected the front during the flight and shifted gears to fly soundings and flux legs at different altitudes on either side of the front.
Plots of 40-Hz time series across the front of T, q, w show that turbulence is abruptly suppressed as the aircraft moves from the warm to the colder waters. An example showing the fluctuations of the vertical wind (w') is given in file 030818_front_sst.jpg along with SST (Ts) and ambient temperature (Ta) and the difference Ts-Ta.
As usual, plots and data subsets can be found at:
We plan to fly at least once tomorrow and we are working on a workable flight plan off Nantucket Qing Wang's mast. We will be monitoring when the winds will shift to the SW.
The IR aircraft flew early Monday morning (8-18-03).
The flight lasted from 1045 to 1300 UTC. The CBLAST region cooled
significantly over the weekend to a mean temperature of 19.9 C, likely due to
the rain. The variability changed significantly as well. From ASIT and
extending south to roughly 41.15 N, the temperature was between 20 and 21.5
C. Just below this from 41.15 to 41.05 N, a cool band of 17-18 C water
exists. Further south, data shows a warm tongue of 22.5 C water extending
into the region from the southeast.
The IR aircraft flew a second time on Monday afternoon (8-18-03). The flight lasted from 1810 to 2040 UTC. The CBLAST region warmed by 1 C from the morning flight to a mean temperature of 20.9 C. The band of cool water and tongue of warm water observed during the morning flight moved to the north and west by roughly 5 km each.
The IR aircraft plans to fly Tuesday morning and rendezvous with the Nobska.
The Nobska headed out this morning with Tom Farrar in charge of offshore operations. Winds range from 0-15 knots over the course of the day and veer from SE to W. Seas at 2 feet during the day. ASIT crew works on tower and lower flux mast at 1700 UTC for remainder of experiment. Closed path moisture flux system is turned on.
Asterias divers and crew deploy all 6 cross-arms off underwater beam.
FLT 030819: The pelican took off today at 9:06 am Eastern. It will do a flight similar to yesterday's especially with the Nobska being in the area. After landing, we will produce an SST map and/or look at the one from the IR group if available. Then we will draw a simple pattern of flux runs at 3 levels over the warm an cold water. We will fly again in the afternoon these flux legs as well as Qing's pattern off Nantucket (if the winds shifts more to the SW from their WSW current direction).
FLT 030819_1: The Pelican took off today at 1303 and landed at 1707 UTC.
Another succesfull flight with SST mapping and SST gradient flux runs. The cold water in the middle of the research area observed yesterday remains pretty much in place (see 030818_map_sst and 030819_map_1_sst).
FLT 030819_2: We attempted a second flight in the afternoon with take off at 1852 UTC to fly up/down wind off Nantucket to support Qinq Wang mast data and COAMPS modeling as well as more flux runs/soundings on either side of the SST gradient. Because of the very low BL height the pattern off Nantucket was aborted and after few SST gradient flux runs the temperature on one the cylinders was abnormally high so the flight had to be aborted all together after roughly 1 hour. The data from the second flight will be posted later.
Plots and data subsets for FLT 030819_1 can be found at:
The IR aircraft attempted two flights Tuesday, 8-19-03. Following both takeoffs at 1650 and 1950, the pilot determined that the severe haze would make it difficult to safely complete the IR aircraft operations at the CBLAST study site. In both cases, we turned back to and landed at Chatham airport.
The Nobska continues offshore observations. Winds at 10-15 knots from the W during the
day. Sea 2-3 feet during the day. ONR and CBLAST scientist head out to the
CBLAST site to check out operations.
All components operational during visit. Here's the link to the
newspaper article from the trip to the tower...
Hutto spoke with Farra this morning on the Nobska. As the winds look favorable for Thursday, they plan to stay out until Friday at 6 a.m. The winds are forecasted to be low again around Tuesday of next week. So the plan might be to go out again for science Tues/Wed, and then begin recovery towards the end of the week. Tom will get back to me with a crew lineup for next week.
Mytillis crew deploys optical sensors on underwater beam and recover ocean profiler for repairs.
FLT 030820: The Pelican took off today at 1452 and landed at 1914 UTC. The Pelican engine heating problem encountered yesterday has been solved by the Jim Nipper the Pelican Mechanic/relieve pilot. This is great news because it could have been the end of the project for the Pelican. I was on the visit to ASIT and Nobska that Jim Edson organized today and it was a great relief to see the Pelican flying at 100' just south of ASIT.
t may sound too repetitive but we had a very successful flight today with SST mapping, flux runs at 100' and 100', 150 and 300' of the western NS leg and on the EW leg just south of ASIT.
There is a dramatic change in the SST map from yesterday's flight where the cold water occupied most of the southern half of the mapped are. The strongest gradient was at 41N which is the southern most boundary of the research area. Refer to the SST map obtained from the Pelican aircraft Heiman KT19.85 IR pyrometer in file "030820_map_sst".
The Ts-Ta varied roughly between -1 and -2 oC and the BL was mostly stable. Profiles of dewpoint and potential temperature from the Pelican sounding data are characteristic of stable BL.
Plots, 1-Hz and 4-Hz data subsets for FLT 030820 can be found at:
The IR aircraft flew twice on Wednesday (8-20-03). The
morning flight lasted from 1217 to 1510 UTC. The mean temperature of CBLAST
region was 21.0 C. The variability was characterized by a large roughly
circular region of 21-22 C water that extended from ASIT south to roughly 41.05
N. Just below this from 41.05 to 41.00 N, a cool annular band of 19.3 -
20.3 C water exists. Further south at 41.0 N, the data shows a warm
region of 23.7 C water that runs the width of the CBLAST study area.
That's a 4 C change in just a few km's. The infrared imagery (with a
spatial resolution of roughly a meter) showed that within this region at 41.0
N, there were many sharp temperature fronts that contribute to this spatial
gradient of temperature. These fronts in the IR imagery were much more
abrupt than the regional map can show (several meters rather than a few km's).
The afternoon flight lasted from 1737 to 2051 UTC. The mean temperature of the region increased by nearly 1 C to 21.8 C and showed similar variability and frontal features to the morning flight.
The IR aircraft just took off around 1030 UTC for its first flight of the day. We will rendezvous with the Nobska on our next flight later this morning and/or this afternoon.
The Nobska continues offshore operations. Winds at 5-12 knots from the W-SW. Seas 2-2.5 feet. Humidity continues to increase with ever increasing haze.
Computers at WHOI, shorelab and on ASIT are attacked by a worm. Most systems are cleaned up over the course of the day. ASIT computers continue to collect data until 2000 UTC when systems are shut down to complete cleanup while remote access is still available. ASIT computers back online at approximately 2300 UTC
Ocean profiler redeployed. Asterias crew deploys vertical T/S array on underwater beam and ocean profiler on bottom.
FLT 030821: The Pelican took off at 1452 and landed at 1923 UTC.
This was a challenging flight in many ways. The CIRPAS DAQ system experienced a loss of about 0.5 hour of data towards the end of the flight. We do not know why this happened and today (Friday) as we were attempting to fly off Nantucket to support Qing Wang the CIRPAS system started and recorded data properly.
The GPS time that is the time base for the UCI DAQ system had some dropouts due to loss of satellites. This made the data processing more time consuming. The UCI data have been processed now and as usual the data subsets and plots are available at:
Since the two systems are redundant, ultimately no data was lost.
Overall, this was a good flight with coordination with the IR aircraft and the Nobska. The flux and SST mapping pattern was flown. The Pelican SST map (030821_map_sst) shows warmer waters on the western most NS leg and coldest to the east. The warmest waters were south of 41N towards the west. This is a significant change from 030820. The Ts-Ta varied roughly between -0.5 and -3 oC throughout the flight and the BL was stable. Profiles of potential temperature from the Pelican sounding data on the western, central and eastern NS tracks are shown in file 030821_NS_soundings. The BL was in general shallower over the colder water.
The IR aircraft flew twice on Thursday (8-21-03). The
morning flight lasted from 1014 to 1315 UTC. The mean temperature of
CBLAST region was 21.4 C. The variability was characterized by a large
roughly circular region of 21.5 - 22.5 C water in the northwest quadrant of the
study site. A cool band of 19.8 - 20.5 C water runs from the northeast
through the southeast corner and into the southwest. The variability was
less than observed previous days.
The afternoon flight lasted from 1621 to 1920 UTC. The mean temperature of the region increased to 22.2 C. Much of the region showed temperatures between 22 and 22.5 C. A warm tongue of 24 C water moved into the southwest corner of the site, while the cooler 20 -21 C water was restricted to the eastern part of the site between 41.1 and 41.25 N. The infrared imagery (with a spatial resolution of roughly a meter) showed numerous temperature fronts throughout the site, but many were concentrated between 41.0 to 41.15 N and 70.5 to 70.6 W. Many fronts were abrupt (several meters) while others were gradual (10's of meters to 100 meters). Some fronts meandered with no particular orientation, while others were straight with a preferred orientation.
August 22, 2003, Yearday 234
Winds 5-15 knots from the SW. Seas build from 2 to 3.5 feet. Hazy, hot, and humid. Nobska heads back in for the weekend.
Next week is the last week for the Nobska and CIRPAS
aircraft. The Nobska will have to devote the last few days of their
shiptime to recovery of most and turnaround of a few of the moorings.
Therefore, the Nobska is going to head out on Monday and stay out through
Wednesday for their last dedicated science cruise. The forecast is not
very clear as there is not a lot of convergence yet in the various
models. Edson’s best guess right now is:
Sunday am 10-18 knts NW
Sunday pm 10-15 knts NW-WNW
Monday am 6-12 knts WNW-W
Monday pm 6-12 knts W-SW
Tuesday am 8-15 knts WSW
Tuesday pm 8-15 knts WSW
Wednesday 8-15 knts WSW-NW with the passage of a front
Tom Farrar and Bob Weller have been thinking about setting up a higher resolution array around one of the Heavy moorings during this last trip. Chris Zappa has also mentioned the possibility of a higher resolution mapping survey (perhaps a 10 km box). Chris and Tom plan to talk Sunday about this. With a little luck, Chris and CIRPAS may be able to fly on Sunday and map out the region. If this is the case, they can use this info to choose the most interesting site for this array.
August 23, 2003, Yearday 235
FLT 030823: The Pelican took off at 1353 and landed at 1923 UTC. Although the wind was from the NW, the Qing Wang group expressed interest in having the Pelican fly off the Nantucket site. Given the proximity of Nantucket airport to the mast site and that the ADIZ being roughly 17 km only south of the closest point the aircraft could get to the mast site, SW-NW tracks could not be flown. After discussing the flight plan with Qing, it was agreed to fly two EW tracks extending from 70W to 70.7W at 41.1N and 41.166N.
Level runs at 100', 150' and 300' ans saw tooth soundings were flown on the two tracks. (Refer to pages 2 and 3 of 030823_selpdf.pdf). The SST contour map from the Pelican IR sensor can be found in file 030823_map_sst. Although the covered area was limited, the map reveals some interesting SST structure with alternating pools (roughly 20 km wide) of warmer and colder water.
Plots and subsets of the UCI data are available at:
The IR aircraft flew once on Saturday (8-23-03). The flight lasted from 1414 to 1710 UTC. The mean temperature of CBLAST region was 21.4 C. The variability was characterized by a large region of 21.5 - 22.5 C water in the northwest quadrant of the study site that extends east near 70.5 W. A cooler band of 20 - 21 C water runs from the far northeast down to between 41.15 and 41.05 N and to the west to 70.7 W. South of 41.05 N, the temperature was 21 - 21.5 C.
August 24, 2003, Yearday 236
Because of the NW winds today the cross wind on the Chatham airport was too high for takeoff and especially for landing of the CIRPAS Pelican. After spending most of the day waiting for the winds to decrease or shift, we had to scrub the flight for today just after 3:00 pm eastern. Conditions should better tomorrow with the forecast of WSW winds. We are planning to have two flights tomorrow.
August 25, 2003, Yearday 237
Winds 4-14 knots backing from WNW to SSW over the course of the day. Seas build from 1.3 to 3 feet. Nobska head out at 6 am to CBLAST site to begin last scientific cruise with Farrar in charge of operations.
FLT 030825_1: The Pelican took off this morning at 1256 and landed at 1706 UTC. The purpose of the flight was to support Qing Wang group and to fly across the eastern SST gradient. The pattern flown consisted of 3 EW tracks at 41.07N, 41.12N and 41.17N between 69.9W and 70.35W south of Nantucket. The winds were moderate and roughly from the WSW. Runs at 100', 150' and saw tooth soundings were flown on each track. (Refer to pages 2 and 3 of 030825_1_selpdf.pdf).
The SST contours map, 030825_1_map_sst, obtained from the Pelican IR temperature sensor shows that the southern track crossed the sharpest SST gradient. This was a successful flight and we hope it will be useful to Qing's group.
Plots and subsets of the UCI data are available at:
FLT 030825_2: The Pelican took off at 1916 and landed at 2214 UTC. This was the second flight of the day and was dedicated to flux divergence just upwind of ASIT. In the afternoon, the wind shifted from WSW to SW and made it a very good opportunity to fly this long sought after pattern especially that the BL was high enough to fly two levels (100' and 300') inside it. The roughly 25 km track was aligned with the wind direction. The sequence consisted of reverse track runs at 100' then at 300' and was repeated 8 times to get the fluxes statistics. We hoped to be able to fly at the end of the flux divergence runs a single pass "lawn mower" mapping pattern to get the spatial variability of SST and other meteorological variables but unfortunately time did not allow for that.
This was a very succesfull day.
Plots and subsets of the UCI data are available at:
We plan to take off tomorrow around 9:00 am eastern for a single 5-hour flight. Mapping and SST gradient will be the most likely pattern given the forecast of NW winds. There is some indication that we may have SW winds again by mid afternoon. We will check this in the morning and revise our flight plans if necessary.
The IR aircraft flew twice on Monday (8-25-03). The
morning flight lasted from 1138 to 1624 UTC. The mean temperature of
CBLAST region was 19.4 C. The variability was characterized by a few
patchy regions of 20 - 20.5 C water in the north of the study site and a warm
pool of 20.4 to 20.5 C water in the southeast corner. A broad cool band
of 18.7 - 19.4 C water ran through the center of the CBLAST region. We
rendezvoused with the Nobska to concentrate on the fronts observed along the
70.5 and 70.55 W lines. As the temperature range indicates, the magnitude
of the variability decreased relative to the earlier in the experiment.
The afternoon flight lasted from 2006 to 2259 UTC. The mean temperature of the region increased to 19.9 C. Much of the northern region showed temperatures between 20 and 20.5 C with some patches of 20.5 - 21 C water. The broad cool band in the middle of the CBLAST site narrowed and warmed up to 19 -19.7 C. The 20.5 -21 C warm pool in the southeast corner slowly intruded westward.
August 26, 2003, Yearday 238
Winds 4-10 knots and veer from SW to N back to SW over the course of the day. Seas build to 3.8 feet in the early am and then drop to 2 feet over the course of the day. This sets up an interesting situation with large swell from the SW with ever changing wind direction.
FLT 030826: The Pelican took off this morning at 1303 and landed at 1708 UTC. It flew the default mapping pattern. The wind direction was NNE towards the start of the flight and kept changing throughout the flight to become SSW an then NNW just before the flight ended.
The SST contours map, 030826_map_sst, obtained from the Pelican IR temperature sensor shows that the water was warmer at the western NS track and colder at eastern NS track. The gradient was about 3 oC. We are planning to fly across this gradient tomorrow morning which most likely be the flight before our last CBLAST flight.
Plots and subsets of the UCI data are available at:
The IR aircraft flew twice on Tuesday (8-26-03). The
morning flight lasted from 1235 to 1650 UTC. The mean temperature of
CBLAST region was 20.5 C. The variability was characterized by a large
roughly circular region of 21 - 22 C water in the northwest quadrant of the
study site extending south. A cool band of 19 - 19.5 C water in the
northeast quadrant runs the shore down to 41.1 N. We rendezvoused with
the Nobska to concentrate on the fronts observed along the 70.55, 70.57, and
70.6 W lines. These track lines showed warming from the initial pass in
the beginning of the flight and sharp temperature fronts in the imagery.
The afternoon flight lasted from 1853 to 2215 UTC. The mean temperature of the region increased to 20.8 C. The variability was characterized by a region of 20.5 - 21 C water in the northwest quadrant of the study site and a warmer pool of 21 to 22.5 C water in the southeast corner. A cool band of 19.5 - 20.2 C water ran through the center of the CBLAST region from the northeast to the southwest between these two warmer regions. A strong front was observed just below 41 N and ran across the entire southern edge of the CBLAST site. We rendezvoused with the Nobska to concentrate on fronts observed along north-south transects between 70.54 and 70.6 W lines.
August 27, 2003, Yearday 239
Wind at 7-14 knots veering from SSW to WSW. Seas 2-3 feet during the day. Haze is slowly building in, but visibility still good offshore. Noska starts to recover moorings during the days. Nobska returns to WHOI at ~2400 UTC to unload gear and change crew.
FLT 030827: The Pelican took off at 1703 and landed at 2036 UTC. The delayed takeoff was due the stronger cross winds on Chatham airport runway.
The original plan was to fly repeated EW tracks across the NS SST gradient identified yesterday. Just before we left the IR group returned from their flight and informed that there was no NS SST gradient. Once in the area, Haf verified that and decided to fly repetitively the track at two different altitudes (100' and 200'). This is a good case to study flux divergence especially that the WSW 10 m/s wind was almost aligned with the track and that the stable BL was relatively deep. The SST-ambient temperature
difference varied between -3oC and -2oC.
Plots and subsets of the UCI data are available at:
The IR aircraft flew Wednesday morning (8-27-03). The
morning flight lasted from 1414 to 1650 UTC. The mean temperature of
CBLAST region was 20.8 C. The variability was characterized by numerous
water masses of different temperature that orient themselves along the .
Near shore down to 41.25 N, the water mass was 20.8 - 21.2 C. Just south
of that water mass, a cooler band of 20.0 - 20.4 C water angled from the east-northeast
toward the west-southwest of the study site . South of that cooler band,
a warm tongue of water ranging from 21.4 to 22 C pushed as far west as 70.7
W. The southwest edge of the site between 41.0 and 41.05 N showed
temperatures of 20.4 to 20.8 C while the southeast edge showed 21.2 to 21.6
C. The variability is complicated and the overall magnitude is 1.3 C per
km in either direction.
The IR aircraft took off for a second flight at 1730 UTC in a much tighter and higher resolution box pattern around ASIT.
August 28, 2003, Yearday 240
Nobska heads back out at 0230 UTC to recover remaining moorings and replace buoying at site F. All heaving mooring are ultimately recovered and only 1 light mooring is lost at sea.
FLT 030828: This was the Pelican's last CBLAST flight. Take off was at 1454 and landed at 1905 UTC. The wind was from the NW at start of flight and shifted 180 deg to become from the SW mid-flight. The default flux mapping pattern was flown given the initial NW winds. The Pelican SST map (30828_map_sst) reveals a warm pool in the center and center-west of the mapped area. The multiple 100' NS flux legs over the warmer and cooler waters (center and eastern ones respectively) will be particularity useful. Two flux runs at 200' were flown just south of ASIT on the EW track at end of flight in addition to the nine 100' legs flown earlier in the flight.
This was a very succesfull flight with all instruments operating properly.
Plots and subsets of the UCI data from this flight are available at:
After the Pelican's return from FLT 030828, Haf and Djamal determined the angle of pitch offsets from the two inertial/GPS units. We also calibrated the EdgeTech chilled mirror dewpointer and the Lyman-Alpha. The error ranged from 1.4 oC at 0 oC to 0.9 oC at 22.5 oC. The temperature probes and all pressure transducers will be calibrated once the aircraft returns to California.
Haf is planning to send the two Eppleys (PIR, PSP) to Bob Weller group for calibration. Bob please confirm if you are still volunteering to calibrate them.
All new cals will be incorporated in the UCI re-processing of the CBLAST flights.
Below is a summary of all the flights that the IR aircraft
made. Data flights are denoted by Run number.
Date Run Takeoff/Engine On Landing/Engine Off Time Frame Aircraft Hours
(UTC) (UTC) 237.5
7/30/2003 1 1930 2202 2.53 6466
7/31/2003 2 1915 2035 1.33 1961
8/14/2003 3 1232 1500 2.47 6132
8/14/2003 4 1759 2107 3.13 7962
8/15/2003 5 943 1230 2.78 4894
8/15/2003 1525 1600 0.58
8/15/2003 6 1913 2253 3.67 9349
8/16/2003 1317 1411 0.90
8/16/2003 1800 1830 0.50
8/18/2003 7 1038 1311 2.55 5011
8/18/2003 8 1801 2048 2.78 6501 259.8
8/19/2003 1647 1754 1.12 260.8
8/19/2003 1952 2020 0.47 261.1
8/20/2003 9 1217 1510 2.88 7306
8/20/2003 10 1737 2051 3.23 7864 267
8/21/2003 11 1014 1315 3.02 7361
8/21/2003 12 1621 1920 2.98 6276 272.7
8/23/2003 13 1414 1710 2.93 6830 275.4
8/25/2003 14 1138 1624 4.77 13567
8/25/2003 15 2006 2259 2.88 6085 282.7
8/26/2003 16 1235 1650 4.25 11583 286.8
8/26/2003 17 1853 2215 3.37 8704 290
8/27/2003 18 1404 1650 2.77 6512 292.7
8/27/2003 2125 2235 1.17 293.7
8/28/2003 19 1247 1606 3.32 4830 296.7
Total Time: 62.38