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Papers by Carol Pease

The National Oceanic and Atmospheric Administration (NOAA) vessel icing algorithm is evaluated ag... more The National Oceanic and Atmospheric Administration (NOAA) vessel icing algorithm is evaluated against theoretical advances. The most difficult factor is influence of sea temperature. Modelling demonstrates the importance of supercooling of spray during its trajectory to extreme ice accretion. This occurs when sea temperatures are less than 2-3 degrees C above the saltwater freezing point. The sea surface temperature term in the NOAA algorithm is consistent with the supercooling hypothesis and a further category of "extreme" icing is added, which can explain anecdotal cases greater than 5 cm per hour. A wave height/wind speed threshold is 5m for a 15m vessel, 10m for a 50m trawler and 15m for a 100m vessel, developed from seakeeping theory. These wind speeds are exceeded 83%, 47% and 15% during February in the Bering Sea.

ABSTRACT. The Beaufort Sea Mesoscale Circulation Study was initiated in the autumn of 1986 and in... more ABSTRACT. The Beaufort Sea Mesoscale Circulation Study was initiated in the autumn of 1986 and included measurements of currents, winds, and ice velocities, as well as obse”kvations of state variables and nutirent disrnbutions in the ocean and state variables in the polar atmosphere, principally between Barrow and Defamation Point along the American Beaufort Sea shelf. This report describes the preliminary results from observations made during the first year of the projec~ including curnmt velocity results from meters recovered through the ice in April 1987, hydrographic and nurnent sections completed in October 1986 and April 1987, wind velocity, air pressure and temperature records recovered continuously through the end of 1987, ARGOS buoy tracks through 1987, and a representative sqple of analyzed weather maps during the first year. Data collection continued through April 1988. The total data set is extraordinary in the temporal and spatial extent of its synoptic coverage, and in...

Eos, Transactions American Geophysical Union, 1994

Monthly Weather Review, 1980

Journal of Geophysical Research, 1990

Polynyas and leads are openings in pack ice due to divergences in ice drift and to local melting.... more Polynyas and leads are openings in pack ice due to divergences in ice drift and to local melting. They are the vents and windows to the polar oceans. In winter they are a major source of brine during freezing and a locus for gas exchange. Large sensible heat fluxes, together with evaporation and longwave radiation from a very small percentage of open water and thin ice, dominate regional heat budgets. In summer, solar radiation is absorbed by open water but is reflected from snow-covered pack ice. Experiments and models describing these processes are reviewed. 1. INTRODUCTION At predictable, recurrent locations throughout the polar regions, there are oceanic areas which remain either partially or totally ice free at times and under climatological conditions where we would expect the waters to be ice covered. These areas are called polynyas [World Meteorological Organization (WMO), 1970]. Polynyas appear in winter, when air temperatures are well below the freezing point for sea water, and are bordered by water which is ice covered. Polynyas are typically rectangular or elliptical and occur quasi-continuously in the same region. They range in size from a few hundred meters to hundreds of kilometers. In certain areas, such as the portion of the Beaufort Sea west of Banks Island, polynyas may gradate into preferred areas for lead formation [Markham, 1981]. Polynyas are of interest for a number of reasons encompassing both physics and biology. For example, many polynyas, particularly those bordering Arctic and Antarctic lee coastlines during winter, are sites for active brine formation. This brine may affect the local water density structure and current field and may also influence larger-scale water mass modification as it is mixed and advected beyond the polynya region. The relatively regular occurrence of polynyas makes them important as biological habitats [Stirling, 1980; Massore, 1988]. The associated open water can contribute in spring to a localized plankton bloom which can "seed" downcurrent areas. Large mammals use them as feeding grounds, suggesting that rich benthic activity takes place as well. Inuit people have used polynyas as hunting grounds for the past 3000 years [Schledermann, 1980]. Polynyas can form by two mechanisms. First, ice may form within the region and be continually removed by winds, currents, or both. The heat required to balance loss to the atmosphere and hence to maintain the open water is pro

Journal of Geophysical Research, 1987

The sizes of wind-generated coastal polynyas have been observed to be nearly constant for steady ... more The sizes of wind-generated coastal polynyas have been observed to be nearly constant for steady atmospheric conditions owing to the balance between the advection of sea ice away from the coast and the area-averaged production rate of new ice. A simple model is used to explore the relationship of several environmental parameters to the maximum size attained by the polynya and the speed at which the maximum is reached for a given atmospheric event. The model results suggest that size is strongly a function of air temperature, such that colder air produces a smaller polynya for a given offshore wind velocity. However, size is only moderately a function of wind speed, especially for winds greater than 10 m s-x, since increasing the speed increases both the advection rate and the ice production rate. The model results are compared to observations made around a coastal polynya during February 1982 and 1983 along the southern coast of St. Lawrence Island in the northern Bering Sea and during February 1985 along the southern coast of the Seward Peninsula. The model correctly predicts the general maximum dimensions of these winter polynyas, although the atmospheric stationarity assumptions limit the usefulness of the predictions of the speed at which the maximum is reached. The results of this study suggest that the contribution of heat from the coastal ocean to the high-latitude winter atmosphere is a self-limiting process proportional to the amount of time the wind-driven ice drift has a component normal to the coast. This has important implications for the interpretation of satellite imagery for ice-covered oceans and for understanding high-latitude climate dynamics.

Journal of Geophysical Research, 1995

A harmonic analysis, constrained to estimate separately ice motions forced by tides and inertial ... more A harmonic analysis, constrained to estimate separately ice motions forced by tides and inertial oscillations, was applied to observed positions of Argos buoys deployed on drifting multiyear sea ice in the eastern Arctic Ocean and Barents Sea during the Coordinated Eastern Arctic Experiment (1988-1989). Individual tidal components were estimated at !5-day intervals, and inertial oscillations were estimated at 3-day intervals. The S2 tidal component was distinguishable from inertial motions south of 79øN, and the M 2 tidal component was distinguishable from the inertial motion north of 77.5øN. Computed ice velocities of up to 70 cm s-• for M 2 tidal motion over Spitsbergen Bank southeast of Svalbard agreed reasonably well with the regional tidal models (no ice cover) of Gjevik and of Kowalik. Regional differences in the energy distribution in the Arctic Basin (low), Barents shelf (high), and Spitsbergen Bank (extreme) were emphasized by this technique. The M 4 tidal component in the ice motion was typically as large over the Barents shelf as the inertial oscillation. Guard icebreaker Northwind, entered the pack ice and proceeded to approximately 82ø40'N, 32ø30'E, northeast of Svalbard, where the PolarbjOrn was intentionally frozen in on September 16, 1988 (day 260 [CEAREX Drift Group (CDG), 1990]). After escorting the PolarbjOrn into the ice, the Northwind maneuvered to support the helicopter deployment of six Argos buoys on ice floes in a 60-km radius around the Polarbjorn (Table 1). The region within the ring subsequently became heavily deformed as the ice passed by both sides of Kviteya. Those buoys are the basis for this study. CEAREX participants expected the PolarbjOrn and satellite buoys to drift westward along the north side of Svalbard toward Fram Strait [CDG, 1990] and exit the Arctic Ocean with the East Greenland Current. However, sustained northerly winds pushed the ice toward the south. The PolarbjOrn-based experiment ended on November 20, 1988, as the ship approached Kviteya (Figure 1). One buoy (7100; Figure 2a) was lost at this time, presumably crushed during compression of the pack ice against the Svalbard Archipelago. The remaining buoys apparently melted out when the floes entered the relatively warm Norwegian Sea or during the spring melt season

Journal of Geophysical Research, 1983

A one-layer, primitive equation model is presented for the atmospheric boundary layer over the ma... more A one-layer, primitive equation model is presented for the atmospheric boundary layer over the marginal ice zone (MIZ). The model simulates the slow rate of inversion growth and rate of warming of the boundary layer seaward of an ice edge for office winds observed on two cruises in the Bering Sea by the NOAA R/V Surveyor. The horizontal temperature gradient in the boundary layer, caused by the oceanic heat flux seaward of an ice edge, induced an increase in wind speed with a maximum increase of 8% at 50 km seaward of the edge. At 100 km off ice, a momentum balance is established between accelerative terms (boundary layer baroclinity, momentum entrainment, synoptic-scale scale pressure gradient) and decelerative terms (surface drag and the local pressure force resulting from inversion rise). Wind velocity in the boundary later over the MIZ during office winds is sensitive to changes in surface roughness. When an MIZ is modeled as a smooth interior (C D = 2 x 10-3) and a 30-km-wide rough marginal ice zone (C D = 3.8 X 10-3) with an unstable surface layer over the ocean, the model shows a decrease in wind speed of 9% at the windward side of the MIZ and an 18% increase in wind speed from 5 km interior to the ice edge to 40 km seaward of the edge. These results suggest an atmospheric mechanism for rafting at the windward side of the marginal ice zone, divergence of the ice at the edge, and ice-band formation seaward of the ,edge.

A set of 85 icing incidents for December 1979 to December 1983 were obtained from the radio log o... more A set of 85 icing incidents for December 1979 to December 1983 were obtained from the radio log of WBH29, a private reporting station on Kodiak Island. Reports were verified by interviews with the vessel operator and comparison with NOAA sea level pressure, air temperature and sea surface temperature analyses. Icing rates are greater than 2.0 cm/hr for 30% of the observations and 60% of the vessel event durations are 8 hours or less. The observed icing rates were three times those of a previous study. New icing nomograms are presented based on this new data.

Journal of Geophysical Research, 1987

Journal of Geophysical Research, 1985

In February 1983 a multifaceted study of the air-ice-ocean interaction was made in the southern B... more In February 1983 a multifaceted study of the air-ice-ocean interaction was made in the southern Bering Sea. The study, MIZEX West, addressed a broad spectrum of physical problems related to the Bering Sea marginal ice zone (MIZ). As a part of that study an array of eight Argos-tracked floes on a scale of 50 km provided information on the mesoscale behavior of the ice pack. Wind and current measuring platforms on two of the floes gave detailed information on the forces on individual floes which were compared with the larger-scale motions. Under relatively steady northeast winds and with weak or negligible regional currents, the floes accelerated considerably as they crossed the MIZ. The array showed little distortion, even though it skirted around St. Matthew Island and changed trajectory direction by over 90 ø during the 12-day study period. Similarly, individual floes remained within 20 ø of their original orientation, although their angular motions were erratic and often rapid. A baroclinicly forced acceleration of the wind over the MIZ contributed to floe acceleration. The relative currents at 2 and 6 m under the ice were highly variable and random in time, although well correlated in depth. One of the floes was much smoother than the other, and higher winds and currents were noted at the smoother floe. The motion of the floes reflect strong coupling to the currents at tidal and lower frequencies and low-frequency (greater than 6 hours) response to the wind. Both floes drifted to the right of the mean wind by approximately 30 ø at about 4% of the wind speed at 3 m, and relative wind and current directions were within 20 ø of being colinear, traits that are consistent with free drift hypothesis. Using quadratic drag representations for wind and current stress, the near colinearity allowed calculation of the ratio of the air/ice to ice/water drag coefficients, Ca/C w, relative to measurement heights of 3 m and-2 m. For the rough floe this ratio changed in mean from 0.06 to 0.2 in its movement to the MIZ. For the smooth floe the variation in the ratio was less, from 0.14 to 0.2. However, for the rough flow the angle between wind and current was generally less than 180 ø, and for the smooth flow it was greater. It is possible that another type of drag related to the bow effect of the floe pushing through the water can account for this observation. Finally, the motion of the ice floes and ice edge are compared by examination of satellite photos. Two regions of the ice pack-one thick with rafting and rubble, one thin and broken-showed a ratio of edge velocity to floe velocity of 0.64 and 0.43, respectively. Thinner ice overtakes the edge and melts more rapidly than the thicker ice. A simple thermodynamic model explains this observation. ship steamed much farther into the ice than originally planned. Finally, ice of sufficient thickness was found, and the Copyright 1985 by the American Geophysical Union. Paper number 5C0535. 0148-0227/85/005 C-0535505.00 array was deployed (Figure 1). The Discoverer remained at the ice edge, making measurements of density structure and wave interaction with the edge until February 18. Its track line during this period was variable, but centered on 59ø10'N, 173øW. At that time the ship moved west in support of the drifting buoy array and operated in the vicinity of 60øN, 176ø30'W. Eight Argos-tracked transponders were placed on the ice in the vicinity of 61øN, 170øW and were tracked westward then southward around St. Matthew Island until February 28, when the last' transponder broke out of the ice and ceased transmitting (Figure 2). Each tracked floe was numbered 1 to 8. Seven of the transponders were deployed on February 10 by helicopters from the Westwind. Floe 7 was instrumented 2 days later over the side of the ship. Other instrumentation accompanied the transponders as they rounded St. Matthew Island. Meteorological stations were deployed on floes 2 and 7. These stations measured mean winds and temperature every half hour at a height of 3 rn and mean ocean currents and temperature at-2 rn under the ice. Floe 7, the main camp, also had a precision pressure sensor, a LORAN receiver, and additional current meters at-2 and-6 m. The LORAN receiver gave position fixes every hour, which increased tracking accuracy and resolution. The Westwind maintained position within a few miles of the main camp and took surface meteorological measurements, upper-air soundings, and oceanographic profiles. All instruments performed well until 12 days later, when they were recovered. The resulting data set is a thorough description of the motion of 11,967 11,968 REYNOLDS ET AL.'. ICE DRIFT AND REGIONAL METEOROLOGY IN BERING SEA o '•

Journal of Geophysical Research, 1995

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 100, NO. C9, PAGES 18,443-18,457, SEPTEMBER 15, 1995 Direct... more JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 100, NO. C9, PAGES 18,443-18,457, SEPTEMBER 15, 1995 Direct measurements of transport and water properties through the Bering Strait AT Roach,1 K. Aagaard,1 С H. Pease,2 SA Salo,2 T. Weingartner,3 V. Pavlov,4 and M. ...

This report compares the winds and currents observed in August, 1978 in the Strait of Juan de Fuc... more This report compares the winds and currents observed in August, 1978 in the Strait of Juan de Fuca with simulated wind and current fields taken from the MESA-Puget Sound oil spill model. This model is described in a companion report, Pease (1980). A method is developed for relating these errors in velocity to uncertainties in predicted position. The tidal current

International Oil Spill Conference Proceedings

Annals of Glaciology

Oceanographic, meteorological and sea-ice data were obtained from the northern Bering Sea and Chu... more Oceanographic, meteorological and sea-ice data were obtained from the northern Bering Sea and Chukchi Sea during the autumns of 1987 and 1988. Ice-edge location was observed from ships and via AVHRR satellite data, and ice-drift information was obtained from ARGOS-tracked drift buoys. Meteorological data were obtained from ships, from an ARGOS-tracked meteorological station and from synoptic charts. The ice edge was significantly farther south in 1988 than during other years and impacted the Alaskan coastline. In 1987, the ice edge was, conversely, anomalously far north. Ice melt-back in certain regions, such as along the Alaskan coast and in Herald Canyon, was due to input from warm ocean currents. The larger-scale interannual differences in ice extent were, however, due to interannual differences in the regional winds. In particular, the anomalous and extreme southward extent of the ice edge during 1988 was due to northerly to northwesterly winds, which held the summer pack ice ag...

The National Oceanic and Atmospheric Administration (NOAA) vessel icing algorithm is evaluated ag... more The National Oceanic and Atmospheric Administration (NOAA) vessel icing algorithm is evaluated against theoretical advances. The most difficult factor is influence of sea temperature. Modelling demonstrates the importance of supercooling of spray during its trajectory to extreme ice accretion. This occurs when sea temperatures are less than 2-3 degrees C above the saltwater freezing point. The sea surface temperature term in the NOAA algorithm is consistent with the supercooling hypothesis and a further category of "extreme" icing is added, which can explain anecdotal cases greater than 5 cm per hour. A wave height/wind speed threshold is 5m for a 15m vessel, 10m for a 50m trawler and 15m for a 100m vessel, developed from seakeeping theory. These wind speeds are exceeded 83%, 47% and 15% during February in the Bering Sea.

ABSTRACT. The Beaufort Sea Mesoscale Circulation Study was initiated in the autumn of 1986 and in... more ABSTRACT. The Beaufort Sea Mesoscale Circulation Study was initiated in the autumn of 1986 and included measurements of currents, winds, and ice velocities, as well as obse”kvations of state variables and nutirent disrnbutions in the ocean and state variables in the polar atmosphere, principally between Barrow and Defamation Point along the American Beaufort Sea shelf. This report describes the preliminary results from observations made during the first year of the projec~ including curnmt velocity results from meters recovered through the ice in April 1987, hydrographic and nurnent sections completed in October 1986 and April 1987, wind velocity, air pressure and temperature records recovered continuously through the end of 1987, ARGOS buoy tracks through 1987, and a representative sqple of analyzed weather maps during the first year. Data collection continued through April 1988. The total data set is extraordinary in the temporal and spatial extent of its synoptic coverage, and in...

Eos, Transactions American Geophysical Union, 1994

Monthly Weather Review, 1980

Journal of Geophysical Research, 1990

Polynyas and leads are openings in pack ice due to divergences in ice drift and to local melting.... more Polynyas and leads are openings in pack ice due to divergences in ice drift and to local melting. They are the vents and windows to the polar oceans. In winter they are a major source of brine during freezing and a locus for gas exchange. Large sensible heat fluxes, together with evaporation and longwave radiation from a very small percentage of open water and thin ice, dominate regional heat budgets. In summer, solar radiation is absorbed by open water but is reflected from snow-covered pack ice. Experiments and models describing these processes are reviewed. 1. INTRODUCTION At predictable, recurrent locations throughout the polar regions, there are oceanic areas which remain either partially or totally ice free at times and under climatological conditions where we would expect the waters to be ice covered. These areas are called polynyas [World Meteorological Organization (WMO), 1970]. Polynyas appear in winter, when air temperatures are well below the freezing point for sea water, and are bordered by water which is ice covered. Polynyas are typically rectangular or elliptical and occur quasi-continuously in the same region. They range in size from a few hundred meters to hundreds of kilometers. In certain areas, such as the portion of the Beaufort Sea west of Banks Island, polynyas may gradate into preferred areas for lead formation [Markham, 1981]. Polynyas are of interest for a number of reasons encompassing both physics and biology. For example, many polynyas, particularly those bordering Arctic and Antarctic lee coastlines during winter, are sites for active brine formation. This brine may affect the local water density structure and current field and may also influence larger-scale water mass modification as it is mixed and advected beyond the polynya region. The relatively regular occurrence of polynyas makes them important as biological habitats [Stirling, 1980; Massore, 1988]. The associated open water can contribute in spring to a localized plankton bloom which can "seed" downcurrent areas. Large mammals use them as feeding grounds, suggesting that rich benthic activity takes place as well. Inuit people have used polynyas as hunting grounds for the past 3000 years [Schledermann, 1980]. Polynyas can form by two mechanisms. First, ice may form within the region and be continually removed by winds, currents, or both. The heat required to balance loss to the atmosphere and hence to maintain the open water is pro

Journal of Geophysical Research, 1987

The sizes of wind-generated coastal polynyas have been observed to be nearly constant for steady ... more The sizes of wind-generated coastal polynyas have been observed to be nearly constant for steady atmospheric conditions owing to the balance between the advection of sea ice away from the coast and the area-averaged production rate of new ice. A simple model is used to explore the relationship of several environmental parameters to the maximum size attained by the polynya and the speed at which the maximum is reached for a given atmospheric event. The model results suggest that size is strongly a function of air temperature, such that colder air produces a smaller polynya for a given offshore wind velocity. However, size is only moderately a function of wind speed, especially for winds greater than 10 m s-x, since increasing the speed increases both the advection rate and the ice production rate. The model results are compared to observations made around a coastal polynya during February 1982 and 1983 along the southern coast of St. Lawrence Island in the northern Bering Sea and during February 1985 along the southern coast of the Seward Peninsula. The model correctly predicts the general maximum dimensions of these winter polynyas, although the atmospheric stationarity assumptions limit the usefulness of the predictions of the speed at which the maximum is reached. The results of this study suggest that the contribution of heat from the coastal ocean to the high-latitude winter atmosphere is a self-limiting process proportional to the amount of time the wind-driven ice drift has a component normal to the coast. This has important implications for the interpretation of satellite imagery for ice-covered oceans and for understanding high-latitude climate dynamics.

Journal of Geophysical Research, 1995

A harmonic analysis, constrained to estimate separately ice motions forced by tides and inertial ... more A harmonic analysis, constrained to estimate separately ice motions forced by tides and inertial oscillations, was applied to observed positions of Argos buoys deployed on drifting multiyear sea ice in the eastern Arctic Ocean and Barents Sea during the Coordinated Eastern Arctic Experiment (1988-1989). Individual tidal components were estimated at !5-day intervals, and inertial oscillations were estimated at 3-day intervals. The S2 tidal component was distinguishable from inertial motions south of 79øN, and the M 2 tidal component was distinguishable from the inertial motion north of 77.5øN. Computed ice velocities of up to 70 cm s-• for M 2 tidal motion over Spitsbergen Bank southeast of Svalbard agreed reasonably well with the regional tidal models (no ice cover) of Gjevik and of Kowalik. Regional differences in the energy distribution in the Arctic Basin (low), Barents shelf (high), and Spitsbergen Bank (extreme) were emphasized by this technique. The M 4 tidal component in the ice motion was typically as large over the Barents shelf as the inertial oscillation. Guard icebreaker Northwind, entered the pack ice and proceeded to approximately 82ø40'N, 32ø30'E, northeast of Svalbard, where the PolarbjOrn was intentionally frozen in on September 16, 1988 (day 260 [CEAREX Drift Group (CDG), 1990]). After escorting the PolarbjOrn into the ice, the Northwind maneuvered to support the helicopter deployment of six Argos buoys on ice floes in a 60-km radius around the Polarbjorn (Table 1). The region within the ring subsequently became heavily deformed as the ice passed by both sides of Kviteya. Those buoys are the basis for this study. CEAREX participants expected the PolarbjOrn and satellite buoys to drift westward along the north side of Svalbard toward Fram Strait [CDG, 1990] and exit the Arctic Ocean with the East Greenland Current. However, sustained northerly winds pushed the ice toward the south. The PolarbjOrn-based experiment ended on November 20, 1988, as the ship approached Kviteya (Figure 1). One buoy (7100; Figure 2a) was lost at this time, presumably crushed during compression of the pack ice against the Svalbard Archipelago. The remaining buoys apparently melted out when the floes entered the relatively warm Norwegian Sea or during the spring melt season

Journal of Geophysical Research, 1983

A one-layer, primitive equation model is presented for the atmospheric boundary layer over the ma... more A one-layer, primitive equation model is presented for the atmospheric boundary layer over the marginal ice zone (MIZ). The model simulates the slow rate of inversion growth and rate of warming of the boundary layer seaward of an ice edge for office winds observed on two cruises in the Bering Sea by the NOAA R/V Surveyor. The horizontal temperature gradient in the boundary layer, caused by the oceanic heat flux seaward of an ice edge, induced an increase in wind speed with a maximum increase of 8% at 50 km seaward of the edge. At 100 km off ice, a momentum balance is established between accelerative terms (boundary layer baroclinity, momentum entrainment, synoptic-scale scale pressure gradient) and decelerative terms (surface drag and the local pressure force resulting from inversion rise). Wind velocity in the boundary later over the MIZ during office winds is sensitive to changes in surface roughness. When an MIZ is modeled as a smooth interior (C D = 2 x 10-3) and a 30-km-wide rough marginal ice zone (C D = 3.8 X 10-3) with an unstable surface layer over the ocean, the model shows a decrease in wind speed of 9% at the windward side of the MIZ and an 18% increase in wind speed from 5 km interior to the ice edge to 40 km seaward of the edge. These results suggest an atmospheric mechanism for rafting at the windward side of the marginal ice zone, divergence of the ice at the edge, and ice-band formation seaward of the ,edge.

A set of 85 icing incidents for December 1979 to December 1983 were obtained from the radio log o... more A set of 85 icing incidents for December 1979 to December 1983 were obtained from the radio log of WBH29, a private reporting station on Kodiak Island. Reports were verified by interviews with the vessel operator and comparison with NOAA sea level pressure, air temperature and sea surface temperature analyses. Icing rates are greater than 2.0 cm/hr for 30% of the observations and 60% of the vessel event durations are 8 hours or less. The observed icing rates were three times those of a previous study. New icing nomograms are presented based on this new data.

Journal of Geophysical Research, 1987

Journal of Geophysical Research, 1985

In February 1983 a multifaceted study of the air-ice-ocean interaction was made in the southern B... more In February 1983 a multifaceted study of the air-ice-ocean interaction was made in the southern Bering Sea. The study, MIZEX West, addressed a broad spectrum of physical problems related to the Bering Sea marginal ice zone (MIZ). As a part of that study an array of eight Argos-tracked floes on a scale of 50 km provided information on the mesoscale behavior of the ice pack. Wind and current measuring platforms on two of the floes gave detailed information on the forces on individual floes which were compared with the larger-scale motions. Under relatively steady northeast winds and with weak or negligible regional currents, the floes accelerated considerably as they crossed the MIZ. The array showed little distortion, even though it skirted around St. Matthew Island and changed trajectory direction by over 90 ø during the 12-day study period. Similarly, individual floes remained within 20 ø of their original orientation, although their angular motions were erratic and often rapid. A baroclinicly forced acceleration of the wind over the MIZ contributed to floe acceleration. The relative currents at 2 and 6 m under the ice were highly variable and random in time, although well correlated in depth. One of the floes was much smoother than the other, and higher winds and currents were noted at the smoother floe. The motion of the floes reflect strong coupling to the currents at tidal and lower frequencies and low-frequency (greater than 6 hours) response to the wind. Both floes drifted to the right of the mean wind by approximately 30 ø at about 4% of the wind speed at 3 m, and relative wind and current directions were within 20 ø of being colinear, traits that are consistent with free drift hypothesis. Using quadratic drag representations for wind and current stress, the near colinearity allowed calculation of the ratio of the air/ice to ice/water drag coefficients, Ca/C w, relative to measurement heights of 3 m and-2 m. For the rough floe this ratio changed in mean from 0.06 to 0.2 in its movement to the MIZ. For the smooth floe the variation in the ratio was less, from 0.14 to 0.2. However, for the rough flow the angle between wind and current was generally less than 180 ø, and for the smooth flow it was greater. It is possible that another type of drag related to the bow effect of the floe pushing through the water can account for this observation. Finally, the motion of the ice floes and ice edge are compared by examination of satellite photos. Two regions of the ice pack-one thick with rafting and rubble, one thin and broken-showed a ratio of edge velocity to floe velocity of 0.64 and 0.43, respectively. Thinner ice overtakes the edge and melts more rapidly than the thicker ice. A simple thermodynamic model explains this observation. ship steamed much farther into the ice than originally planned. Finally, ice of sufficient thickness was found, and the Copyright 1985 by the American Geophysical Union. Paper number 5C0535. 0148-0227/85/005 C-0535505.00 array was deployed (Figure 1). The Discoverer remained at the ice edge, making measurements of density structure and wave interaction with the edge until February 18. Its track line during this period was variable, but centered on 59ø10'N, 173øW. At that time the ship moved west in support of the drifting buoy array and operated in the vicinity of 60øN, 176ø30'W. Eight Argos-tracked transponders were placed on the ice in the vicinity of 61øN, 170øW and were tracked westward then southward around St. Matthew Island until February 28, when the last' transponder broke out of the ice and ceased transmitting (Figure 2). Each tracked floe was numbered 1 to 8. Seven of the transponders were deployed on February 10 by helicopters from the Westwind. Floe 7 was instrumented 2 days later over the side of the ship. Other instrumentation accompanied the transponders as they rounded St. Matthew Island. Meteorological stations were deployed on floes 2 and 7. These stations measured mean winds and temperature every half hour at a height of 3 rn and mean ocean currents and temperature at-2 rn under the ice. Floe 7, the main camp, also had a precision pressure sensor, a LORAN receiver, and additional current meters at-2 and-6 m. The LORAN receiver gave position fixes every hour, which increased tracking accuracy and resolution. The Westwind maintained position within a few miles of the main camp and took surface meteorological measurements, upper-air soundings, and oceanographic profiles. All instruments performed well until 12 days later, when they were recovered. The resulting data set is a thorough description of the motion of 11,967 11,968 REYNOLDS ET AL.'. ICE DRIFT AND REGIONAL METEOROLOGY IN BERING SEA o '•

Journal of Geophysical Research, 1995

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 100, NO. C9, PAGES 18,443-18,457, SEPTEMBER 15, 1995 Direct... more JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 100, NO. C9, PAGES 18,443-18,457, SEPTEMBER 15, 1995 Direct measurements of transport and water properties through the Bering Strait AT Roach,1 K. Aagaard,1 С H. Pease,2 SA Salo,2 T. Weingartner,3 V. Pavlov,4 and M. ...

This report compares the winds and currents observed in August, 1978 in the Strait of Juan de Fuc... more This report compares the winds and currents observed in August, 1978 in the Strait of Juan de Fuca with simulated wind and current fields taken from the MESA-Puget Sound oil spill model. This model is described in a companion report, Pease (1980). A method is developed for relating these errors in velocity to uncertainties in predicted position. The tidal current

International Oil Spill Conference Proceedings

Annals of Glaciology

Oceanographic, meteorological and sea-ice data were obtained from the northern Bering Sea and Chu... more Oceanographic, meteorological and sea-ice data were obtained from the northern Bering Sea and Chukchi Sea during the autumns of 1987 and 1988. Ice-edge location was observed from ships and via AVHRR satellite data, and ice-drift information was obtained from ARGOS-tracked drift buoys. Meteorological data were obtained from ships, from an ARGOS-tracked meteorological station and from synoptic charts. The ice edge was significantly farther south in 1988 than during other years and impacted the Alaskan coastline. In 1987, the ice edge was, conversely, anomalously far north. Ice melt-back in certain regions, such as along the Alaskan coast and in Herald Canyon, was due to input from warm ocean currents. The larger-scale interannual differences in ice extent were, however, due to interannual differences in the regional winds. In particular, the anomalous and extreme southward extent of the ice edge during 1988 was due to northerly to northwesterly winds, which held the summer pack ice ag...