Atmospheric sciences on Ice Station Weddell
of the antarctic sea-ice zone on antarctic marine systems, and in the control of global biogeochemical and energy exchanges." It is anticipated that the results of the studies described here will contribute to that goal. We wish to acknowledge A. Gordon and V. Lukin for organization and camp management; J . Ardai and D. Bell for logistics support; I. Melnikov, R. Swayzer III, P. Sullivan, and ice physics group personnel for field assistance at 15W-1 and on board R/V Palmer. This research was supported by National Science Foundation grant DPP 90-23669. References
Arrigo, K. R., C. W. Sullivan, and J. N. Kremer. 1991. A bio-optical model of antarctic sea ice. Journal of Geophysical Research, 96:10,581-10,592. Arrigo, K. R., J. N. Kremer, and C. W. Sullivan. 1992. A simulated antarctic fast ice ecosystem. Journal of Geophysical Research, submitted. Brkholder, P. R., E. F. Mandelli. 1965. Productivity of microalgae in antarctic sea ice. Science. 149:872-874. Clarke, D. B. and S. F. Ackley. 1984. Sea ice structure and biological activity in the antarctic marginal ice zone. Journal of Geophysical Research, 89:2,087-2,095. Comiso,J. C., N. G. Maynard, W. 0. Smith, Jr., and C. W. Sullivan. 1990. Satellite ocean color studies of antarctic ice edge in summer/autumn. Journal of Geophysical Research, 95(C6):9,481-9,496. Dieckmann, C. S., C. W., Sullivan, and D. Garrison. 1990. Seasonal standing crop of ice algae in pack ice of the Weddell Sea, Antarctica. EOS, AGU/ASLO Ocean Sciences Meeting, New Orleans, Louisiana, 12-16 February 1990. Garrison, D. L., C. W. Sullivan, and S. F. Ackley. 1986. Sea ice microbial communities in Antarctica. BioScience, 36(4):243-250. Garrison, D. L. and K. R. Buck. 1985. Sea-ice algal communities in the Weddell Sea: species composition in ice and species composition in ice and plankton assemblages. In J. S. Gray, and M. E. Christiansen(Eds.), Marine biology of polar regions and effects of stress on marine organisms,
New York: John Wiley and Sons, 103-121.
Garrison, D. L., K. R. Buck, and G. A. Fryxell. 1987. Algal assemblages in antarctic pack ice and in ice-edge plankton. Journal of Phycology, 23:564-572. Grossi, S. M., S. T. Kottmeier, R. L. Moe, G. T. Taylor, and C. W. Sullivan. 1987. Sea ice microbial communities VI: Growth and production in bottom ice under graded snow cover. Marine Ecology Progress Series, 35:153-164. Kottmeier, S. T. and C. W. Sullivan 1987. Late winter primary production and bacterial production in sea ice and seawater west of the Antarctic Peninsula. Marine Ecology Progress Series, 36:287-298. Kottmeier, S. T. and C. W. Sullivan. 1990. Bacterial biomass and production in pack ice of antarctic marginal ice edge zones. Deep-Sea Research, 37(8):1,311-1,330. Lizotte, M. P. and C.W. Sullivan. 1991. Photosynthesis-irradiance relationships in microalgae associated with antarctic pack ice: evidence for in situ activity. Marine Ecology Progress Series, 71:175-184. Lizotte, M. P. and C. W. Sullivan. 1992. Photosynthetic capacity in microalgae associated with antarctic pack ice. Polar Biology, in press. Lytle, V. I., K. C. Jezek, S. Gogineni, R. K. Moore, and S. F. Ackley. 1990. Radar backscatter measurements during the winter Weddell Gyre study. Antarctic Journal of the U.S., 25(5):123-125. Marra, J . and D. C. Boardman. 1984. Late winter chlorophyll a distributions in the Weddell Sea. Marine Ecology Progress Series, 19:197-205. Palmisano, A. C., SooHoo, J . Beeler, and C. W. Sullivan. 1987. Effects of four environmental variables on photosynthesis-irradiance relationships in Antarctic sea-ice microalgae. Marine Biology, 94:299-306. Smith, W. 0., Jr. and D. M. Nelson. 1986. Importance of ice edge phytoplankton production in the southern ocean. BioScience, 36:251-257. Sullivan C. W., A. C. Palmisano, S. Kottmeier, S. M. Grossi, and R. Moe. 1985. The influence of light on growth and development of the sea ice microbial community in McMurdo Sound. R. Siegfried, P. R. Condy, and R. M. Laws (Eds.), Fourth SCAR Symposium on Antarctic Biology, Nutrient Cycles and Food Webs, Berlin: Springer-Verlag, 78-83. Sullivan, C. W., C. R. McClain, J. C. Comiso, and W. 0. Smith, Jr. 1988. Phytoplankton standing crops within an antarctic ice edge assessed by satellite remote sensing. Journal of Geophysical Research, 93(C10): 12,487-12,498.
Atmospheric sciences on Ice Station Weddell EDGAR L. ANDREAS AND KERAN J . CLAFFEY
Em
U.S. Army Cold Regions Research and Engineering Laboratory Hanover, New Hampshire 03755-1290 1.0 . 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 Wind Dlec0on Magnetic)
ALEKSANDR P. MAKSHTAS AND BORIS V. Iv&riov
Arctic and Antarctic Research Institute Saint Petersburg, Russia 199226
The joint U.S.-Russian atmospheric sciences program on Ice Station Weddell featured close coordination and mutually beneficial collaboration. Our broad objective was to understand air-
1992 REvww
Figure 1. The neutral-stability, 10-meter drag coefficient obtained from wind speed profile measurements, as a function of wind direction. The undisturbed sector around this profile mast was from 1500 to 3100 magnetic; thus, these are the only directions plotted. ice-ocean interaction from measurements made on the air side of the interface. We collected data that will let us determine the surface stress on the upper ice surface and all of the components
115
a
—10
9 V
E- —15 -20 -25 350 300 250 200 150 100 50 C
Height (in)
. Dew Point Temperature
13 12 11 10 p
5
4 3 2
350 300 250
200 150 100 50 Height (in)
Figure 2. Air temperature and dew point (top)from the 12h-GMTtethersonde ascent on 20 April 1992. Bottom, as above, except this is the wind speed profile.
of the surface energy budget at three-hour intervals for the duration of the drift. The core measurements of our program were made on our main meteorological tower. At a height of five meters, we had small, fast-responding instruments with which to measure the turbulent fluctuations in the three wind speed components, air temperature, and water vapor density. These measurements will yield the Reynolds fluxes of momentum (the surface stress) and sensible and latent heat. We supplemented these direct measurements of the turbulent fluxes with profile measurements on two nearby masts. One mast held propeller anemometers at four logarithmically spaced levels between 0.5 and 4.0 meters; a second mast had eight cup anemometers and eight aspirated thermocouples at levels between 0.28 and 5.5 meters. A full suite of radiation measurements, consisting of incoming and outgoing shortwave and longwave radiation and the shortwave and longwave balances, complemented the turbulence measurements and completes the surface energy budget. We also measured the snow-surface temperature radiatively
116
with a Barnes PRT-5 infrared radiation thermometer and by i hygrometric technique (Andreas 1986). When a lead opened near the camp we spent 15 days observing albedo, ice thickness and salinity, and radiative and physical temperatures of the surface and near-surface water. This data set should complement the data collected during the Arctic leads experiment that was going on off the coast of Alaska at about the same time (Curtin 1991). Figure 1 shows some of the early results from our surface based program. We evaluated the air-ice drag coefficient for neutrally stable conditions at a reference height of ten meters, from the four-level propeller anemometer measurements (Andreas and Claffey 1992). In March and April we collected roughly 1,000 hourly averaged, four-level profiles before one of our anemometers began to malfunction. From these we selected only those profiles for which the stability conditions were near neutral, the upwind fetch was undisturbed, and the instruments were well aligned with the mean wind direction. These con, straints reduced the 1,000 original profiles to 190 high-quality profiles that yielded the CDNIO values in figure 1.
ANTARCTIC JOURNAl.
Our CDN1O values range from 1.3 x 10 to 2.5 x 10. These values are typical of what—by arctic standards—would be called rough ice (Overland 1985). Figure 1 makes another important point. The CON10 values are not randomly scattered. They seem to show some trends that depend on the wind direction. We interpret this to mean that the ice surface is not isotropic. The figure suggests that CON10 can change by 50 percent if the wind direction changes by 10; the surface stress would behave basically the same. The implications for sea ice modeling are important. The surface stress depends not only on the wind speed but also on how the wind is oriented with respect to the surface topography. Upper-air soundings, made nominally at noon and mid-night GMT for the entire drift with either tethered or free-flying radiosondes, should help us put our surface-based observations into a mesoscale or synoptic context. This radiosounding program has already provided us some insight into the structure and physics of the atmospheric boundary layer (ABL). We found the ABL at this time of year to be shallow-100 to 300 meters thick—stably stratified, and generally topped by an atmospheric jet. Within the ABL, winds were usually light and variable, typically 2 to 3 meters per second; but just above the inversion, the jet could have speeds of 14 to 15 meters per second. April 20 (figures 2 and 3) is a good example of such a stable ABL with the overlying air decoupled from the surface. On this day the base of the inversion layer was at about 50 meters (figure 2). At 5 meters, the air temperature was -16.9 C; but at about 240 meters, the temperature actually went above 0 'C. Mean-
while, the wind speed at the surface was less than 3 meters per second; while in the core of the jet at 100 meters, it was over 11 meters per second (figure 3). On occasion, however, through a combination of mechanical erosion and radiative processes controlled by the clouds—the high energy in the jet mixed all the way down to the surface. This breakdown of the stable ABL led to episodes of rapid northerly drift. We hope to order the sequence of events and to identify the processes that lead to the collapse of the elevated inversion and the consequent episodic drift. This research was supported by National Science Foundation grant DPP 90-24544.
The Ice Station Weddell (ISW) traceroceanography program
western shelf water during water /ice interaction underneath the Filchner/Ronne Ice Shelf. This water /ice interaction melts part of the ice shelf (e.g., Weiss, Ostlund, and Craig 1979; Schlosser et al. 1990; Helimer and Olbers 1990) decreasing its salinity from about 34.70 to 34.65 psu and cooling it to temperatures below the freezing point of sea water at surface pressure—supercooled water (e.g., Lusquinos 1963; Foldvik and Kvinge 1977). The low §oxygen-18 concentration of the ice shelf is caused by a depletion of the atmospheric water vapor in §oxygen-18 with increasing precipitation, causing a decrease of the §oxygen-18 values in antarctic precipitation as a function of the distance from the coast (Morgan 1982). Due to the large difference in oxygen-18 between the shelf ice and the sea water (about 50 parts per thousand), small fractions of meltwater added to the seawater imprint of the water mass with a traceable signal. With a measurement precision of ±0.02 parts per thousand, which is standard for state of the art mass spectrometers, addition of 0.4 parts per thousand of glacial meltwater to seawater can be detected. Therefore §oxygen-18 is a valuable tracer for identification of shelf water masses containing a glacial meltwater component. Helium trapped in bubbles during the formation of glacial ice is released to the water during melting at the underside of the ice shelf (Schlosser 1986). Due to high content of air in glacial ice [about 10 percent (Gow and Williamson 1975) and the low solubility of helium [about less than 1 percent, e.g. Weiss (1971)], glacial meltwater is supersaturated by roughly 1400 percent in helium. With a measurement precision for helium-4of about ±O.5 to ± 1 percent, a fraction of about 0.35 to 0.7 parts per thousand of
PETER SCHLOSSER, RALF WEPPERNIG, WILLIAM
M. SMETHIE JR., AND
Guy MATHIEU Lamont-Doherty Geological Observatory Columbia University Palisades, New York 10964
As part of the Ice Station Weddell (ISW) hydrographic program, water samples were collected for shore based analysis of several tracers including the steady-state tracers oxygen-18, helium-3, and helium4, and the transient tracers tritium, CFC 11, and CFC 12. Oxygen-18 and helium-4 data will be used to study the contribution of waters modified by interaction with glacial ice to deep and bottom water in the Weddell Sea. The basis for this application is the fact that the ice shelf water is marked by low §oxygen18 values (about -0.6 parts per thousand and high helium-4 concentrations). The reason for these low values is the addition of glacial meltwater, with extremely low §oxygen-18 values; compared to sea water (about -40 to -60 parts per thousand) to the
1992 REVIEW
References
Andreas, F. L. 1986. A new method of measuring the snow-surface temperature. Cold Regions Science and Technology, 12(2):139-156. Andreas, E. L. and K. J . Claffey. 1992. The air-ice drag coefficient in the Weddell Sea deduced from profile measurements. Tenth Symposium on Turbulence and Diffusion of the American Meteorological Society, Portland, Oregon, 29 September to 2 October, 1992, J109-J112. Curtin, T. B. (Ed.). 1991. Arctic lead dynamics, science review. Arctic Sciences Program, Office of Naval Research. Report No. 1125AR-91033. Arlington, Virginia. 104 pp. Overland, J . E. 1985. Atmospheric boundary layer structure and drag coefficients over sea ice. Journal of Geophysical Research, 90(C5):9,0299,049.
117
Arrigo, K. R., C. W. Sullivan, and J. N. Kremer. 1991. A bio-optical model of antarctic sea ice. Journal of Geophysical Research, 96:10,581-10,592. Arrigo, K. R., J. N. Kremer, and C. W. Sullivan. 1992. A simulated antarctic fast ice ecosystem. Journal of Geophysical Research, submitted. Brkholder, P. R., E. F. Mandelli. 1965. Productivity of microalgae in antarctic sea ice. Science. 149:872-874. Clarke, D. B. and S. F. Ackley. 1984. Sea ice structure and biological activity in the antarctic marginal ice zone. Journal of Geophysical Research, 89:2,087-2,095. Comiso,J. C., N. G. Maynard, W. 0. Smith, Jr., and C. W. Sullivan. 1990. Satellite ocean color studies of antarctic ice edge in summer/autumn. Journal of Geophysical Research, 95(C6):9,481-9,496. Dieckmann, C. S., C. W., Sullivan, and D. Garrison. 1990. Seasonal standing crop of ice algae in pack ice of the Weddell Sea, Antarctica. EOS, AGU/ASLO Ocean Sciences Meeting, New Orleans, Louisiana, 12-16 February 1990. Garrison, D. L., C. W. Sullivan, and S. F. Ackley. 1986. Sea ice microbial communities in Antarctica. BioScience, 36(4):243-250. Garrison, D. L. and K. R. Buck. 1985. Sea-ice algal communities in the Weddell Sea: species composition in ice and species composition in ice and plankton assemblages. In J. S. Gray, and M. E. Christiansen(Eds.), Marine biology of polar regions and effects of stress on marine organisms,
New York: John Wiley and Sons, 103-121.
Garrison, D. L., K. R. Buck, and G. A. Fryxell. 1987. Algal assemblages in antarctic pack ice and in ice-edge plankton. Journal of Phycology, 23:564-572. Grossi, S. M., S. T. Kottmeier, R. L. Moe, G. T. Taylor, and C. W. Sullivan. 1987. Sea ice microbial communities VI: Growth and production in bottom ice under graded snow cover. Marine Ecology Progress Series, 35:153-164. Kottmeier, S. T. and C. W. Sullivan 1987. Late winter primary production and bacterial production in sea ice and seawater west of the Antarctic Peninsula. Marine Ecology Progress Series, 36:287-298. Kottmeier, S. T. and C. W. Sullivan. 1990. Bacterial biomass and production in pack ice of antarctic marginal ice edge zones. Deep-Sea Research, 37(8):1,311-1,330. Lizotte, M. P. and C.W. Sullivan. 1991. Photosynthesis-irradiance relationships in microalgae associated with antarctic pack ice: evidence for in situ activity. Marine Ecology Progress Series, 71:175-184. Lizotte, M. P. and C. W. Sullivan. 1992. Photosynthetic capacity in microalgae associated with antarctic pack ice. Polar Biology, in press. Lytle, V. I., K. C. Jezek, S. Gogineni, R. K. Moore, and S. F. Ackley. 1990. Radar backscatter measurements during the winter Weddell Gyre study. Antarctic Journal of the U.S., 25(5):123-125. Marra, J . and D. C. Boardman. 1984. Late winter chlorophyll a distributions in the Weddell Sea. Marine Ecology Progress Series, 19:197-205. Palmisano, A. C., SooHoo, J . Beeler, and C. W. Sullivan. 1987. Effects of four environmental variables on photosynthesis-irradiance relationships in Antarctic sea-ice microalgae. Marine Biology, 94:299-306. Smith, W. 0., Jr. and D. M. Nelson. 1986. Importance of ice edge phytoplankton production in the southern ocean. BioScience, 36:251-257. Sullivan C. W., A. C. Palmisano, S. Kottmeier, S. M. Grossi, and R. Moe. 1985. The influence of light on growth and development of the sea ice microbial community in McMurdo Sound. R. Siegfried, P. R. Condy, and R. M. Laws (Eds.), Fourth SCAR Symposium on Antarctic Biology, Nutrient Cycles and Food Webs, Berlin: Springer-Verlag, 78-83. Sullivan, C. W., C. R. McClain, J. C. Comiso, and W. 0. Smith, Jr. 1988. Phytoplankton standing crops within an antarctic ice edge assessed by satellite remote sensing. Journal of Geophysical Research, 93(C10): 12,487-12,498.
Atmospheric sciences on Ice Station Weddell EDGAR L. ANDREAS AND KERAN J . CLAFFEY
Em
U.S. Army Cold Regions Research and Engineering Laboratory Hanover, New Hampshire 03755-1290 1.0 . 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 Wind Dlec0on Magnetic)
ALEKSANDR P. MAKSHTAS AND BORIS V. Iv&riov
Arctic and Antarctic Research Institute Saint Petersburg, Russia 199226
The joint U.S.-Russian atmospheric sciences program on Ice Station Weddell featured close coordination and mutually beneficial collaboration. Our broad objective was to understand air-
1992 REvww
Figure 1. The neutral-stability, 10-meter drag coefficient obtained from wind speed profile measurements, as a function of wind direction. The undisturbed sector around this profile mast was from 1500 to 3100 magnetic; thus, these are the only directions plotted. ice-ocean interaction from measurements made on the air side of the interface. We collected data that will let us determine the surface stress on the upper ice surface and all of the components
115
a
—10
9 V
E- —15 -20 -25 350 300 250 200 150 100 50 C
Height (in)
. Dew Point Temperature
13 12 11 10 p
5
4 3 2
350 300 250
200 150 100 50 Height (in)
Figure 2. Air temperature and dew point (top)from the 12h-GMTtethersonde ascent on 20 April 1992. Bottom, as above, except this is the wind speed profile.
of the surface energy budget at three-hour intervals for the duration of the drift. The core measurements of our program were made on our main meteorological tower. At a height of five meters, we had small, fast-responding instruments with which to measure the turbulent fluctuations in the three wind speed components, air temperature, and water vapor density. These measurements will yield the Reynolds fluxes of momentum (the surface stress) and sensible and latent heat. We supplemented these direct measurements of the turbulent fluxes with profile measurements on two nearby masts. One mast held propeller anemometers at four logarithmically spaced levels between 0.5 and 4.0 meters; a second mast had eight cup anemometers and eight aspirated thermocouples at levels between 0.28 and 5.5 meters. A full suite of radiation measurements, consisting of incoming and outgoing shortwave and longwave radiation and the shortwave and longwave balances, complemented the turbulence measurements and completes the surface energy budget. We also measured the snow-surface temperature radiatively
116
with a Barnes PRT-5 infrared radiation thermometer and by i hygrometric technique (Andreas 1986). When a lead opened near the camp we spent 15 days observing albedo, ice thickness and salinity, and radiative and physical temperatures of the surface and near-surface water. This data set should complement the data collected during the Arctic leads experiment that was going on off the coast of Alaska at about the same time (Curtin 1991). Figure 1 shows some of the early results from our surface based program. We evaluated the air-ice drag coefficient for neutrally stable conditions at a reference height of ten meters, from the four-level propeller anemometer measurements (Andreas and Claffey 1992). In March and April we collected roughly 1,000 hourly averaged, four-level profiles before one of our anemometers began to malfunction. From these we selected only those profiles for which the stability conditions were near neutral, the upwind fetch was undisturbed, and the instruments were well aligned with the mean wind direction. These con, straints reduced the 1,000 original profiles to 190 high-quality profiles that yielded the CDNIO values in figure 1.
ANTARCTIC JOURNAl.
Our CDN1O values range from 1.3 x 10 to 2.5 x 10. These values are typical of what—by arctic standards—would be called rough ice (Overland 1985). Figure 1 makes another important point. The CON10 values are not randomly scattered. They seem to show some trends that depend on the wind direction. We interpret this to mean that the ice surface is not isotropic. The figure suggests that CON10 can change by 50 percent if the wind direction changes by 10; the surface stress would behave basically the same. The implications for sea ice modeling are important. The surface stress depends not only on the wind speed but also on how the wind is oriented with respect to the surface topography. Upper-air soundings, made nominally at noon and mid-night GMT for the entire drift with either tethered or free-flying radiosondes, should help us put our surface-based observations into a mesoscale or synoptic context. This radiosounding program has already provided us some insight into the structure and physics of the atmospheric boundary layer (ABL). We found the ABL at this time of year to be shallow-100 to 300 meters thick—stably stratified, and generally topped by an atmospheric jet. Within the ABL, winds were usually light and variable, typically 2 to 3 meters per second; but just above the inversion, the jet could have speeds of 14 to 15 meters per second. April 20 (figures 2 and 3) is a good example of such a stable ABL with the overlying air decoupled from the surface. On this day the base of the inversion layer was at about 50 meters (figure 2). At 5 meters, the air temperature was -16.9 C; but at about 240 meters, the temperature actually went above 0 'C. Mean-
while, the wind speed at the surface was less than 3 meters per second; while in the core of the jet at 100 meters, it was over 11 meters per second (figure 3). On occasion, however, through a combination of mechanical erosion and radiative processes controlled by the clouds—the high energy in the jet mixed all the way down to the surface. This breakdown of the stable ABL led to episodes of rapid northerly drift. We hope to order the sequence of events and to identify the processes that lead to the collapse of the elevated inversion and the consequent episodic drift. This research was supported by National Science Foundation grant DPP 90-24544.
The Ice Station Weddell (ISW) traceroceanography program
western shelf water during water /ice interaction underneath the Filchner/Ronne Ice Shelf. This water /ice interaction melts part of the ice shelf (e.g., Weiss, Ostlund, and Craig 1979; Schlosser et al. 1990; Helimer and Olbers 1990) decreasing its salinity from about 34.70 to 34.65 psu and cooling it to temperatures below the freezing point of sea water at surface pressure—supercooled water (e.g., Lusquinos 1963; Foldvik and Kvinge 1977). The low §oxygen-18 concentration of the ice shelf is caused by a depletion of the atmospheric water vapor in §oxygen-18 with increasing precipitation, causing a decrease of the §oxygen-18 values in antarctic precipitation as a function of the distance from the coast (Morgan 1982). Due to the large difference in oxygen-18 between the shelf ice and the sea water (about 50 parts per thousand), small fractions of meltwater added to the seawater imprint of the water mass with a traceable signal. With a measurement precision of ±0.02 parts per thousand, which is standard for state of the art mass spectrometers, addition of 0.4 parts per thousand of glacial meltwater to seawater can be detected. Therefore §oxygen-18 is a valuable tracer for identification of shelf water masses containing a glacial meltwater component. Helium trapped in bubbles during the formation of glacial ice is released to the water during melting at the underside of the ice shelf (Schlosser 1986). Due to high content of air in glacial ice [about 10 percent (Gow and Williamson 1975) and the low solubility of helium [about less than 1 percent, e.g. Weiss (1971)], glacial meltwater is supersaturated by roughly 1400 percent in helium. With a measurement precision for helium-4of about ±O.5 to ± 1 percent, a fraction of about 0.35 to 0.7 parts per thousand of
PETER SCHLOSSER, RALF WEPPERNIG, WILLIAM
M. SMETHIE JR., AND
Guy MATHIEU Lamont-Doherty Geological Observatory Columbia University Palisades, New York 10964
As part of the Ice Station Weddell (ISW) hydrographic program, water samples were collected for shore based analysis of several tracers including the steady-state tracers oxygen-18, helium-3, and helium4, and the transient tracers tritium, CFC 11, and CFC 12. Oxygen-18 and helium-4 data will be used to study the contribution of waters modified by interaction with glacial ice to deep and bottom water in the Weddell Sea. The basis for this application is the fact that the ice shelf water is marked by low §oxygen18 values (about -0.6 parts per thousand and high helium-4 concentrations). The reason for these low values is the addition of glacial meltwater, with extremely low §oxygen-18 values; compared to sea water (about -40 to -60 parts per thousand) to the
1992 REVIEW
References
Andreas, F. L. 1986. A new method of measuring the snow-surface temperature. Cold Regions Science and Technology, 12(2):139-156. Andreas, E. L. and K. J . Claffey. 1992. The air-ice drag coefficient in the Weddell Sea deduced from profile measurements. Tenth Symposium on Turbulence and Diffusion of the American Meteorological Society, Portland, Oregon, 29 September to 2 October, 1992, J109-J112. Curtin, T. B. (Ed.). 1991. Arctic lead dynamics, science review. Arctic Sciences Program, Office of Naval Research. Report No. 1125AR-91033. Arlington, Virginia. 104 pp. Overland, J . E. 1985. Atmospheric boundary layer structure and drag coefficients over sea ice. Journal of Geophysical Research, 90(C5):9,0299,049.
117
