RACER: Racer RocksANTHONY F. Amos, University of Texas atAustin, Marine Science Institute, PortAransas, Texas 78373

Among the many islands in the Gerlache Strait are a groupof rocky islets that have now been officially named Racer

Rocks. The following is the U.S. Board on Geographic Namesentry in their official listings.

Racer Rocks 64°04'S 61°36WA small cluster of some 10 rocks in water, the largest rising toca. 17m., located in the Gerlache Strait and lying about 1 mi.equidistant from Auguste I. and Lobodon I. Probably first seenby the Belgae (1897-99) under Lt. A. de Gerlache during hisexp. here. The name derives from the placement of an auto-matic weather station (AWS 9301) in Nov. 1989 by a researchteam (A.F. Amos, leader), embarked from the R/V Polar Dukerepresenting the Univ. of Texas, Marine Science Institute.Racer is an acronym for the NSF sponsored Research onAntarctic coastal Ecosystem and Rates program [Huntley et al.19901. In this instance, conducting multi-disciplinary studieson the physical and mass transport systems and its effect onthe biological productivity in the Gerlache Strait area.Approved by US-ACAN in April 1992.

Racer Rocks is of interest to our project as a site for anautomatic weather station (Stearns and Weidner 1990), whichmonitored the windfield in the Gerlache Strait to aid in ourunderstanding of the surface-water circulation (Amos 1990).This paper serves to introduce Racer Rocks with a briefoverview of the physical, biological, and meteorological set-ting. During the several visits made there by RACERresearchers since 1989, I have made an attempt to survey therocks. It has been by no means an exhaustive study becausethe main project and difficult weather conditions precludeddoing a proper survey.

Physical setting

Figure 1 shows Racer Rocks' location, rough outline, and aprofile sketch of the main islets. Table 1 gives a brief histo-

ry. Racer Rocks is part of the Antarctic Peninsula VolcanicGroup complex of basalts and andesites (Bell 1984). As far aswe know, the rocks had not been visited prior to our landingin October 1989. The position of the AWS on the summit ofRacer Rocks is 64004.019'S 061 036.668'W with an error of ±33meters (m). Figure lB shows the rough island outlinesobtained by radar surveys from R/V Polar Duke with detailsfilled in by visual observation. The size is probably exaggerat-ed by the inaccuracies of the radar method, and the locationof Lobodon and Auguste islands relative to Racer Rocks maybe distorted. The largest island is the site of the AWS and hasan altitude of 17 m. We do not know exactly how many rocksmake up the complex because some are barely awash andsnow bridges may join one or more islets. The count is some-where between 20 and 24 separate rocks. They are not perma-nently glaciated although pockets of ice and snow remainyear-round. Figure 1C is my sketch of the islands' profilesmade in November, looking to the southwest. A natural"lagoon" fringed by submerged rocks forms a sheltered

entrance to the landing site. Landing must be made by smallboat, and the research vessel must anchor some 1,000 m off tothe east. Both the anchorage and landing must be made withcare because several shoals surround Racer Rocks. The lagoonis often filled with icebergs making landing impossible. Inwinter, shifting sea ice can also prevent small-boat usage.

Biological setting

Southern black-backed gulls (Larus dominicanus) nest onthe "summit" of the largest islet. There were about 12

active nests in December 1991 and numerous deep limpetmiddens indicated that this has been a long-established nest-ing site. Antarctic terns (Sterna antarctica) were observedperforming nuptial rituals and may also nest there. A largeflight (250+) of antarctic shags (Phalacrocorax bransfieldensis)

Table 1. History of RacerRocks

09 Oct 1989PD 89-08Zodiac explorationLobodon/Auguste group

28 Oct 1989PD 89-08First landing on Racer Rocks.Selected site for AWS onlargest of the islets.

01 Nov 1989PD 89-09Attempt landing withequipment. Icebergs blockedthe way.

05 Nov 1989PD 89-09Staged equipment on island forearly morning installation.

06 Nov 1989PD 89-09Erected AWS. Fix on summitfrom ship's Magnavox was64 004.021'S 061036.254'W

26 Nov 1989PD 89-09Inspection of AWS.08 Nov 1989PD 89-09Radar and visual survey of

Racer Rocks. Abandonedwhen Polar Duke drifted overshoal water.

08 Dec 1991PD 91-10Removed faulty control box andinstalled new one. Had toremove humidity sensor.

19 Jul 1992NBP 92-04Inspection of AWS. Globalpositioning system (GPS) fix(Trimble Transpac II),64°04.01 75 061036.716W.

11 Aug 1992NBP 92-04 Attempt to remove faultyanemometer. Failed, weatherturned bad.

12 Aug 1992NBP 92-04 Removed anemometer. Had noreplacement. GPS fixed64 004.001'S 061036.699-W,64 004.018'S 061036.664'W

13 Nov 1992PD 92-09Landing attempt abandoned.19 Nov 1992PD 92-09Replaced anemometer with one

donated by Rothera. TrimbleGPS fixes, 64°04.020'S061 036.630'W, 64004.035S061036.635'W.

apfj denotes Polar Duke; NBP denotes Nathaniel B. Palmer.

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111111!63 30'S

64 0'S61 38'w 61 35w 61 34'w 61 32'W

64 30'S Auguste I.

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1. Anvers l. Libodon].2. Brabant I.

64 03'S

64 04'S

64 05'S

3. Liege I. - 41J 64 06'S

4. Two Hummock I. Racer Rocks & Polar Duke cruise tracks5. Intercurrence I.

6. Hoseason I.7. Trinity I.

Figure 1. Location and profile of Racer Rocks. A. Gerlache Strait and principal islands. B. Racer Rocks and Auguste and Lobodon islands. Thesymbol points to the location of the AWS on Racer Rocks. C. Sketch of Racer Rocks' profiles made in November 1989.

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East-West Velocity (m.sec-1)-25 -20 -15 -10 -5 0 5 10 15 20 25

25

20

15

10

5

I-5

-10

-15

-20

-25

RACER Rock winds; Nov 1989 through Dec 1990(Mean 1.8 rn/sec to 245 deg.)

Figure 2. Wind rose from AWS on Racer Rocks. Data from November1989 through December 1990. The open circle at the center showsthe magnitude and direction of the resultant mean annual windvector. Lines point in the direction to which the wind is blowing.

Table 2. Racer Rocks climate data

Air temperature (°C)+5.9-16.3-2.14Relative humidity (%)1003179.8Wind speed (in meters

per second) 26.005.5Barometer (in millibars) 1,029.6963.8992.6

was observed in November 1989 and a like number inNovember 1992. They may have a colony on adjacentLobodon Island. Stray individual gentoo, chinstrap, andAdélie penguins were observed on the rocks, but no rookerieswere found. Crabeater seals haul out on the snow-coveredslopes of Racer Rocks. There are no grasses, but lichens arecommon on the upper crags. In midwinter, under a thickcover of snow, colonies of several species of mites wereobserved in association with the lichens.

When the AWS was first installed, several L. dominicanuswere grouped on the completely snow-covered summit. Wewere concerned about disturbance to the gulls by the installa-tion of the AWS. At the time, we did not know the birds werenesting in the immediate area. All equipment was hauled tothe site by sled. Guy wires were secured by expansion bolts

anchored to the rock; a generator-powered drill was used tomake the holes. Gulls apparently do not roost on the AWSstructure or guy-wires. By late November 1989, the birds wereincubating eggs. To minimize disturbance, our visits havebeen limited to an hour or two. After observing disturbancewhen several people visited in late November, we haverestricted personnel to the minimum necessary to do anyrequired AWS maintenance during the nesting season. A visitin late November 1992 showed that the same nests wereactive as in 1989.

The climate

We selected Racer Rocks as an AWS site because of itslocation near the center of the RACER project's station

grid. A potential problem was the proximity of the twin 700-rnpeaks of Two Hummock Island, which may shield RacerRocks from recording the open Gerlache Strait windfield. Fig-ure 2 shows hourly wind vectors for a period of 13 months.There seems to be no seasonal directional bias, the 1-yearpattern looks similar to any 3-month pattern. Winds rotatethrough the compass, reflecting the frequent passage of low-pressure systems approaching from the west. The lack ofwinds in the east-northeast and west-northwest quadrantsmay be due to the location of the paths of most cyclones rela-tive to the station. The resultant velocity of 1.8 in secondtoward 245 is in the opposite sense to the general water circu-lation in the Gerlache.

Table 2 shows the yearly extremes and means for AWS8930 on Racer Rocks. Humidity and barometer are fromincomplete records.

Several people from the RACER group, Antarctic SupportAssociates, and Edgeton, Germerhausen, and Grier supportpersonnel helped install and service the AWS on Racer Rockson various occasions. Among these were Andy Brittain, DaleHebel, Stan Jacobs, Cole Mather, Skip Owen, Bruce Polking-horn, Judy Roberson, Tony Schanzle, Karen Schmidt, RorySmythe, and Andi Wickham. Thanks are due to the officersand crews of the R/V Polar Duke and R/V Nathaniel B. Palmerand to Chuck Stearns. This work was supported by NationalScience Foundation grant OPP 89-07287.

ReferencesAmos, A.F. 1990. RACER: Meteorological conditions during the spring

bloom in the Gerlache Strait. Antarctic Journal of the U.S., 25(5),128-131.

Bell, G.M. 1984. The geology of islands in southern Bransfield Strait,Antarctic Peninsula. British Antarctic Survey Bulletin, 63, 41-55.

Huntley, M.E., P. Niiler, 0. Holm-Hansen, M. Vernet, E. Brinton, A.F.Amos, D.M. Karl. 1990. RACER: An interdisciplinary study ofspring bloom dynamics. Antarctic Journal of the U.S., 25(5),126-128.

Stearns, C.R., and G.A. Weidner, 1990. Antarctic automatic weatherstations: Austral summer 1989-1990. Antarctic Journal of the U.S.,25(5), 254-258.

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