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    Observations show that, for a given geostrophic forcing, baroclinity acting on the planetary boundary layer produces a nearly sinusoidal modification of the near-surface wind. Compared to barotropic conditions the speed is enhanced in the direction of the thermal wind and the cross-isobar angle increases (decreases) in cold (warm) advection. These modifications are asymmetric with respect to the thermal wind orientation. Two-layer similarity models that match a stratification-dependent surface layer to a stratification and baroclinity dependent Ekman layer simulate aspects of this asymmetric baroclinic modification if the cold advection conditions are more unstably stratified than the warm advection conditions. The authors demonstrate that roll vortices in a baroclinic planetary boundary layer produce an asymmetric surface wind modification in neutral stratification that can work in concert with the coupling between stratification and baroclinity to enhance the net effect of baroclinity on the surface wind. It is further demonstrated that the roll modification effect can be as much as or even more that the pure thermal wind effect, although both are secondary to the pure frictional effect. This baroclinic roll modification works to increase the low-level poleward mass transport and the near-surface westerly momentum in the midlatitudes.

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    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, 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 stationary 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.

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    Variable Name (Sampling): Zonal Wind (JFM Mean at 300 hPa) ID: 11 Region: N. Pacific: 60N,180E Data Type: Atmosphere Units: m/s Lon.:180E Lat.: 60N Start Year: 1948 End Year: 1999

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    Wind decode result from the NEAR-GOOS region.Data sets may be obtained directly from the North-East Asian Regional - Global Ocean Observing System (NEAR-GOOS) Regional Delayed Mode Data Base (RDMDB) at http://near-goos1.jodc.go.jp/ with a user account. First time users must register to gain database access.

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    The free-drift equations are solved for ice floes in a shallow sea of neutral stratification, typical of many high-latitude continental shelves. Solutions for ice drift and current velocity are obtained as a function of wind stress, ice thickness, and water depth. The ocean is modeled by second-order closure, which allows continuous solutions from 5 m total depth to deep water. Results are presented with drag coefficients for the air/ice, ice/water, and water/bottom interfaces specified from recent surveys from the Bering Sea Shelf, a region with broad areas of water depths between 20 and 50 m. The solution shows little dependence on water depth for depths greater than 30 m. This occurs because turbulent mixing is a decreasing function of water depth and offsets other influences of finite depth. However, for water depths less than 30 m, ice velocities can change rapidly with wind speed and water depth, and the presence of turbulence from tidal shear is very important for coupling wind-driven ice drift to the bottom. For the deep-water limit, the second-order closure solution confirms analytic solutions that indicate an increase of 20% in the ratio of ice speed to wind speed as the wind speed increases from 10 to 25 m/s.[Reference: Overland, J.E., H.O. Mofjeld, and C.H. Pease. 1984. Wind-driven ice drift in a shallow sea. J. Geophys. Res., 89(C4), 6525-6531.]

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    The winds within Shelikof Strait, Alaska, have been examined using hourly observations from a pair of meteorological buoys moored at the ends of the strait for a 6-month period in 1994. The focus is on periods of gap winds, when the prominent terrain bordering Shelikof Strait constrains the low-level winds to accelerate down the local pressure gradient in a direction approximately parallel to the axis of the strait. Statistics have been amassed on the performance of a simple, Bernoulli-type gap wind model during periods of downstrait (northeasterly) gap flow. A series of model experiments have been conducted to elucidate the processes important to gap flow in Shelikof Strait. The model best predicts the observed along strait component of the wind at the exit of the strait (explaining 74% of the variance) when it includes not just surface friction, but also parameterizations of the Coriolis effect due to the cross-strait wind and of entrainment. The latter process is studied further using upper-air soundings collected at Kodiak, Alaska, immediately upstream of the strait. These observations suggest that the entrainment is driven largely by the vertical wind shear at the top of the gap flow. Gap winds are favored more during downstrait flow than during up strait (southwesterly) flow. The lower terrain on the Kodiak Island side of the strait may often represent an insufficient sidewall for upstrait gap flow, as suggested by the detailed observations from a NOAA P-3 research aircraft flight in May 1996 during upstrait flow. Examination of ECMWF operational analyses for the period of buoy observations shows that the alongstrait pressure gradient was represented adequately but the surface winds were handled poorly. The gap wind model presented here could aid operational forecasting of winds in Shelikof Strait, using coarse-resolution analyses or numerical model output for its input, and could be adapted for other regions with similar topography.

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    Each year, along the Pacific Coast of North American between San Francisco (38 North Latitude) and the Queen Charlotte Islands (52 North Latitude), the coastal winds switch from the southerly winds of winter to the northerly winds of summer producing a transition in wind called the spring transition. Conversely, the yearly switch back from the northerly winds of summer to the southerly winds of winter produce a fall transition. The summer winds, which occur after the spring transition and prior to the fall transition, are known to be favorable for upwelling -- a process that transports the nutrients to the ocean surface, feeding the near-shore food chain. Estimates of the transition dates were derived from smoothed synthetic winds computed by the ocean surface currents model OSCURS (Ingraham and Miyihara 1988), which used daily sea level atmospheric pressure fields for years 1946 to 1994 as input. The spring and fall transition dates were calculated for the latitude of the Columbia's mouth (46 deg 12' North Latitude). The data set is provided courtesy of the U.S. Army Corps of Engineers, Northwestern Division, North Pacific Region, Engineering and Technical Services, Water Management Division. The Mouth of the Columbia Wind Spring and Fall Transition Dates data set is featured at the University of Washington, School of Aquatic and Fisheries Sciences, Data Access Real Time (DART) program. DART provides an interactive data resource designed for research and management purposes relating to the Columbia Basin salmon populations and river environment. Currently, daily data plus historic information dating back to 1910 is accessible online. DART focuses on the Columbia Basin dams and fish passage. Detailed information is brought in daily from federal, state and tribal databases to provide a comprehensive information tool. DART generates user-specified data files which can be saved to a user's personal directory in a variety of formats designed to be compatible with most spreadsheet programs. In addition, DART has graphing capabilities which allow for the visual comparison of multiple variables on one plot. These output formats are available for the following data resources related to fish passage, PIT tags and the river environment. [ Reference: PICES Scientific Report No. 18 2001, Proceedings of the PICES/CoML/IPRC Workshop on "Impact of Climate Variability on Observation and Prediction of Ecosystem and Biodiversity Changes in the North Pacific", http://www.pices.int/publications/scientific_reports/Report18/default.aspx. ]

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    Arctic water vapor characteristics.

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    Wind decode error result.Data sets may be obtained directly from the North-East Asian Regional - Global Ocean Observing System (NEAR-GOOS) Regional Delayed Mode Data Base (RDMDB) at http://near-goos1.jodc.go.jp/ with a user account. First time users must register to gain database access.

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    Observations of sea ice drift obtained with satellite-tracked ice beacons in March-April of 1988 and 1989 have been used to examine the response of sea ice drift to wind forcing over the northern Newfoundland continental shelf. The short-term (5-20 days) response of sea ice drift ranges from 2.6 to 5.4% of the local wind over much of the inner continental shelf, which is comparable to that in the Bering Sea and the Antarctic but larger than that in Arctic. Sea ice drifts to the right of the local wind, at angles ranging from 10 degree to 63 degree . The response to wind forcing is largest near the ice edge, both over the middle portions of the shelf and along the southern margins of the seasonal ice zone and during strong and steady wind of several days' duration. The large wind-driven response of ice drift observed in this study, in comparison with the Arctic, may result from (1) reduced levels of internal ice stress associated with the generally thin ice cover and lower areal concentration of sea ice, (2) large atmospheric drag coefficients associated with the small ice floes in areas of comparatively higher ice concentration, and (3) smooth ice bottom caused by melting. In nearshore areas the ice to wind coupling is reduced owing to larger internal ice stresses experienced locally due to ice pileup.