Today (29 May), a special treat for the scientists and crew of the NB Palmer. The Leader of Argentina's San Martin Station, Captain Carlos Martin, has invited us to visit the Station, which is located on the eastern side of Marguerite Bay. We are just now at anchor a mile from the Station and we will soon be using the Zodiacs ferry parties from the Ship to the Station. We are currently at -68 08.765°S; -67 06.374°W (at 1040 local). Wind is less than 10 kts from the north and the air temperature is -3.8°C. It is snowing moderately.
During the 28th of May, the krill patch study continued in the northern portion of Marguerite Bay throughout the day and into the evening. In addition to using BIOMAPER-II to define the krill patch structure with the acoustics and Video Plankton Recorder, two horizontal MOCNESS tows were done within a portion of the krill layer that was well defined. A CTD profile was also made within the area where high concentrations of krill were observed. During the day, the winds were a steady 25 kts out of the north-northeast (020) and this precluded putting the Zodiacs over the side to enable the whale group to attempt additional whale biopsies. There were several humpbacks in the area close to where the highest concentrations of krill were observed and several were sighted from the vessel and were heard on the sonabuoy transmissions.
Eileen Hofmann reports that the activities for the CTD group on 28 May consisted of a single CTD station that was done in the center of a region that was characterized by a high abundance of Antarctic krill. The vertical profile from this cast showed warm (1.2°C) and low oxygen (3.6 ml/l) water near the bottom. This vertical distribution is consistent with newly intruded Circumpolar Deep Water. The remainder of the day was used in doing data analysis and preparing information for inclusion in the cruise report.
Susan Howard provided maps of near-surface velocity distributions that
were obtained from the Acoustic Doppler Current Profiler. These data show
west-southwest flow in the region where the coastal current was found.
The ADCP data also show north-northeast flow in part of the region where
the krill patch was observed. This may be associated with a meander in
the coastal current as it rounds the tip of Adelaide Island.
Bob Beardsley and Jeff Otten Report on the installation of the Automated Weather Stations on Kirkwood and Faure Islands.
Part 1. Kirkwood Island AWS Deployment - May 25, 2001
Automated Weather Station (AWS) #8930 was installed on the main island in the Kirkwood Islands group on May 25, 2001. The main island (Kirkwood Island) has a number of rock outcroppings and ridges leading up from the water and spray line with a relatively flat snow cap covering most of the top. A crude estimate of the top of the snow cap is ~100 ft. The other close islands in this group were smaller pieces of exposed rock that would be covered or exposed to severe sea spray during periods of high winds and waves.
The AWS site is on a slab rock shoulder on a ridge heading approximately NW on the northwestern tip of the island. The site has open exposure from west through northeast; winds from the south may be distorted by the main snow cap. The N B Palmer approached from the west and took up station roughly 1/2 nm west of this ridge. A Zodiac was used to transport the AWS and crew around the north end of this ridge, passing between the main island and some very low rocky islands, before landing cargo and crew in a small cove on the NE side of the ridge. Winds and a small swell were from the west during the day, so this cove was somewhat protected, however, there was no place to beach or tie off the zodiac or leave it unattended. Getting crew and cargo out of the boat and up the first 10' of altitude was difficult due to steep, smooth rock walls coated with ice. Once above this danger zone and onto more protected rock, most of the crew changed from dry suits to mustangs before continuing. The rest of the ascent started out on glacial smoothed bedrock, then turned into permanent snowpack before reaching the rocky shoulder from the northeast. Even though we had difficulty landing, the fur seals clearly didn't. A large group (25 or more) fur seals covered the northern snow face of this island, with a number on the highest pieces of snow and rock. There was a pair of seals on the ridge within 10 m of the AWS site, and evidence of seals around the site and the ascent route.
Once on top, installation of the AWS went smoothly. Holes for three steel pins were drilled into the base rock, and the pins inserted with epoxy for cement. The three-sided pipe tower was lowered onto the base pins, and three wire guy lines run to self-locking bolts drilled into outlying rock faces. Washers were used on the base pins to align the tower with vertical. The portable electric rock drill and generator were essential for making the base and guy-wire anchor points, and the generator exhaust doubled as an excellent hand warmer. The generator also powered a portable heat gun that was used to dry out the terminations before final mating, and heating the self-vulcanizing tape used to wrap the connectors into the base of the electronics box.
The AWS consists of: a) a horizontal sensor beam that supports an RM Young wind monitor on top and a temperature sensor in a solar shield and a relative humidity sensor on the bottom of the beam, b) an electronics data logger box with barometric pressure sensor inside, c) a satellite transmitter and antenna, and c) a battery box and a solar panel. The sensor beam was mounted on top of the tower, with the satellite antenna and solar panel mounted lower. The data logger box was mounted about 5 ft above ground, and all wires were run inside the tower if possible and attached with tie-wraps. The battery box was tied to the tower base with nylon rope.
During installation, the data logger outputs, battery voltage, and satellite transmitter were all checked and found working. The final task was to determine the alignment of the sensor beam, since the wind monitor returns the wind direction relative to the sensor beam orientation. First, the GPS position of the AWS was measured with a handheld unit. Then the ship was asked to move slightly so that her GPS antenna was in line with the AWS sensor beam, in the "windbird south" direction. When aligned, the ship's GPS position and the AWS position determine the AWS bearing. These positions were AWS (-68 20.397°S, -69 00.444°W) and NBP (-68 20.504°S, -69 01.720°W), giving a "windbird north" direction of 77° relative to true north.
The installation was finished about 3:45 local time, well after dusk. The NBP kept one spotlight aimed at the AWS site, which helped during the final assembly and anchoring of the guy wires. The descent from the site back to the cove was straightforward, with the generator being the only heavy piece to carry down. The transfer to the waiting Zodiac and back to the ship was smooth. All in all, a very successful trip. The installation crew were Alice Doyle, Jessie Doren, Dave Green, Jeff Otten, and Bob and Sue Beardsley.
AWS # 8930
Latitude: -68 20.397°S
Longitude: -69 00.444°W
Height above sea level: ~75 ft (crude estimate)
Station orientation: 77°N
Variables: wind speed, direction, air temperature, relative humidity, barometric pressure
Installation: May 25, 2001
Part 2. Faure Island AWS Deployment - May 27, 2001
Automated Weather Station (AWS) #8932 was installed on a small rocky island just east of Dismal Island in the Faure Island group in Marguerite Bay on May 27, 2001. The island is on the eastern edge of this island group, and the NB Palmer was able to approach to within 1/4 nm from the east. The island is elongated in shape, roughly 1/8 nm long and perhaps 1/4 of that length in width, with the main axis oriented roughly 20 N. The island is relatively low, with snow covered ridges and exposed rocky patches on top.
It was a quick Zodiac ride from the ship around the northern end of the island to a landing site on the northwest shore. There are possibly several different places to make a landing. We landed along the snout of a permanent snow pack, then trekked to the left with a short climb up a small rock face to get on top of the snow. From there it was an easy walk to a high point on the northern end of the island. We had snow and poor visibility in the morning, but shortly after we landed, the snow stopped, the mountains of south Adelaide Island appeared, and with winds of only 10-15 kts, it was a pleasant day for work. We encountered a fur seal and penguin at our landing spot, and found evidence of seals over the top of the island. Fur seals and penguins were seen on the small islands to the west.
The AWS installation went smoothly, using similar methods to those used on Kirkwood. Three holes were drilled into the rock and threaded rod pieces placed in the holes. On Kirkwood, washers were used on the threaded posts to level the base for the tower. Here two nuts with a washer above were used on each rod to support and level the tower. Holes were drilled and anchors inserted into the holes to secure the guy wires. As on Kirkwood, two-hole brackets were bolted onto the anchors, and shackles were used to attach the guy wire thimbles to the two-hole brackets. After the guy wires were attached, the nuts beneath the tower legs were raised slightly to put more tension on the guy wires. This was an improvement over Kirkwood where we just used human strength to tighten the guys. However, turnbuckles should be used on any future installation or station refurbishment.
The Faure AWS is similar to the Kirkwood AWS, but features a Belfort wind monitor. The pressure sensor serial number is 55180, and the CS program is 55180-2 as shown on the paper note left inside the electronics data logger box. As before, the data logger outputs, the battery voltage, and the satellite transmitter were checked and found working. After final assembly and checkout, the AWS GPS position was determined, and the ship was moved so that it was aligned with the AWS sensor beam. The AWS position is -68 05.243°S, -68 49.480°W. With the ship at -68 05.429°S, -68 48.735°W, the anemometer "north" was determined to be 124°N.
The installation was completed around 3:15 local time. The descent and return to the ship was straightforward. The installation crew were Jessie Doren, Dave Green, Jeff Otten, Andy Girard, Mark Christmas, and Bob Beardsley. Mark documented the installation plus the penguin sampling conducted on the next island during the day. A very successful day in Marguerite Bay.
AWS # 8932
Latitude: -68 05.243°S
Longitude: -68 49.480°W
Height above sea level: ~35 ft (crude estimate)
Station orientation: 124°N
Variables: wind speed, direction, air temperature, relative humidity, barometric pressure
Installation: May 27, 2001
BIOMAPER-II/MOCNESS report (P. Wiebe, C. Ashjian, S. Gallager and
Between midnight and 0800 on 28 May, a series of BIOMAPER-II towyo transects, which started on 27 May, crisscrossed the Lebeuf fjord. These were run to define the structure of the high density layer/patches in the area and to find one that was large enough to allow a MOCNESS tow to be started and ended in it. The 4 to 8 watch found a reasonable sized krill patch in their survey and a MOCNESS tow was done it. Scott Gallager was able to adjust the Simrad sonar so that patches of krill did show up on all three frequencies and since BIOMAPER-II had to be on deck to do the net towing, the Simrad sonar was used to track the krill layer and patchiness during the tow. The tow was a towyo between 50 and 100 meters, just within the layer that the krill were distributed in. Each net was opened at 50 m, lowered at about 10 to 12 meter per minute down to 100 m, and then hauled back at the same rate to 50 m, where the net was closed and the next one opened. This down-up pattern took between 8 and 10 minutes for each net and represented a distance traveled of about 500 m and a volume filtered of about 500 cubic meters. The forward facing strobe light was randomly either turned on while a net was fishing or left off. The random sequence of strobe on/off was OFF, OFF, ON, ON, ON, OFF, ON, OFF. All the nets seemed to be in the layer of adult krill for the duration of the tow (as indicated by the Simrad echograms), but when the catches were washed down and put into the preserving jars, the last net had almost no adult krill in with the other critters. Either we ran out of the patch or because it was becoming first light, the adults in the layer may have begun a vertical migration down to a daytime depth around 200 meters.
After quickly washing the catches down, the MOCNESS was reloaded and readied for another tow. During this time, the ship was jogging back on the reverse of the towing course. The patch, however, had dissipated and instead of towing again, we went into searching for it again using the Simard sonar. The vertical backscattering structure had undergone a change as the daylight increased and the 50 to 100 m layer was greatly reduced and a new layer developed at about 200 meters. But that layer was not dependable either. We did locate another intense patch at 200 m, but spatially it was too small to do another strobe light experiment in. We tried steaming over to where a couple of humpback whales were sighted to the southeast of our towing site, but no layer developed. We turned around and headed back towards where the krill patch had been previously, and found it again. There a CTD was done to characterize the water column.
After the CTD, BIOMAPER-II was deployed and the afternoon was spent towyoing it over the area trying to define the pattern of krill distributions within the more western area of the fjord so that we could target another area in which to do a MOCNESS tow. This also gave us a better appreciation of the vertical migration behavior of the krill.
After dark, the krill returned from daytime depths to the same zone in the water column inhabited the night before and mapping with BIOMAPER-II identified a large area of high concentrations of krill. The towed body was brought back on deck around 2130, and the second MOCNESS was completed just before midnight with the nets fishing in the same depth and time intervals a described above, but using a different strobe light on/off random sequence. As with the first horizontal tow, the krill in the samples were large and very abundant adults.