Browsing by Author "Bernstein, Elizabeth Rachel"
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Item Exploring integrated kinetic energy of polar mesoscale storms to estimate sea ice formation and salt fluxes in the Weddell Sea(University of Delaware, 2015) Bernstein, Elizabeth RachelThis dissertation examines the relationship between polar cyclones and sea ice cover. Through this research, an archive of polar cyclones is created. The archive contains storms for the time period 01 January 1979 through 31 August 2014 for the Weddell Sea, a region east of the Antarctic Peninsula extending to where the Southern Ocean and Indian Ocean meet. The four defined properties of polar cyclones used in this work are: high wind speeds, low pressures, short duration, and small spatial scales. The storm strength is expressed specifically through the maximum wind speed and minimum sea level pressure. The archive additionally includes characteristics of individual storms including the storm date, duration, strength, and size which are analyzed and compared to changes in sea ice cover during each storm. Subsequently, this research quantifies linkages between polar cyclones and sea ice by computing each storm's integrated kinetic energy as a measure of the size, duration, and wind speeds. Specific linkages include the surface energy balance, sea ice growth rate, and the quantity of brine rejected to the top of the water column. The results show that the area of open water is the biggest contributor to sea ice growth and brine production through new ice formation. The ejected brine from the ice increases the density of sea water in the nearby upper ocean layers which contribute to the destabilization of the water column. Subsequently, the destabilization of the water column helps to form Weddell Sea Bottom Water - the coldest and densest water mass on the planet and major contributor to the global ocean circulation. Hence, the storm climatology developed herein provides a new quantitative resource for establishing significant links between polar storms and Weddell Sea deep water formation.Item Sea ice thickness and the distribution contributing to the mass balance of the Southern Ocean(University of Delaware, 2010) Bernstein, Elizabeth RachelAlthough sea ice concentration, extent, and type can be measured with acceptable accuracy by satellite or airborne remote sensing techniques, sea ice thickness measurements are difficult to obtain accurately, even in situ. Modeling sea ice volume and associated transport requires input data for ice motion, as well as for the distribution of sea ice thickness. There is a need to develop new sea ice models driven by the best available data. The majority of sea ice thickness measurements in the Southern Ocean are derived from drill holes, and more recently upward looking sonar and electromagnetic methods, but these data points are sparse. The most comprehensive sea ice thickness dataset for Antarctic sea ice available to date is the Antarctic Sea Ice Processes and Climate (ASPeCt) program, which includes 23,373 ship-based observations collected over two decades; however, this dataset has spatial and temporal gaps. This thesis uses the ice stage of development records from National/Naval Ice Center (NIC) operational ice charts as a proxy for sea ice thickness from four years (1995-1998). From the sea ice information within the ice charts, ice thickness and volume are derived to produce model-input-ready Southern Ocean sea ice thickness distributions on multiple temporal and regional scales. Evaluation of the basin-wide thickness distribution includes analysis of multiple sea ice thickness calculation methods and an examination of the seasonal and regional patterns of sea ice distribution.