993 resultados para Gemstone Team BALANCE


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Coastal and marine ecosystems support diverse and important fisheries throughout the nation’s waters, hold vast storehouses of biological diversity, and provide unparalleled recreational opportunities. Some 53% of the total U.S. population live on the 17% of land in the coastal zone, and these areas become more crowded every year. Demands on coastal and marine resources are rapidly increasing, and as coastal areas become more developed, the vulnerability of human settlements to hurricanes, storm surges, and flooding events also increases. Coastal and marine environments are intrinsically linked to climate in many ways. The ocean is an important distributor of the planet’s heat, and this distribution could be strongly influenced by changes in global climate over the 21st century. Sea-level rise is projected to accelerate during the 21st century, with dramatic impacts in low-lying regions where subsidence and erosion problems already exist. Many other impacts of climate change on the oceans are difficult to project, such as the effects on ocean temperatures and precipitation patterns, although the potential consequences of various changes can be assessed to a degree. In other instances, research is demonstrating that global changes may already be significantly impacting marine ecosystems, such as the impact of increasing nitrogen on coastal waters and the direct effect of increasing carbon dioxide on coral reefs. Coastal erosion is already a widespread problem in much of the country and has significant impacts on undeveloped shorelines as well as on coastal development and infrastructure. Along the Pacific Coast, cycles of beach and cliff erosion have been linked to El Niño events that elevate average sea levels over the short term and alter storm tracks that affect erosion and wave damage along the coastline. These impacts will be exacerbated by long-term sea-level rise. Atlantic and Gulf coastlines are especially vulnerable to long-term sea-level rise as well as any increase in the frequency of storm surges or hurricanes. Most erosion events here are the result of storms and extreme events, and the slope of these areas is so gentle that a small rise in sea level produces a large inland shift of the shoreline. When buildings, roads and seawalls block this natural migration, the beaches and shorelines erode, threatening property and infrastructure as well as coastal ecosystems.

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EXTRACT (SEE PDF FOR FULL ABSTRACT): Annual, winter, and summer mass balance measurements at South Cascade Glacier in the North Cascade Mountains of Washington State constitute a continuous time series 36 years long, from 1959 to 1994. ... The long-term trends at South Cascade Glacier are decreased winter accumulation and increased summer ablation, neither of which is conducive to glacier growth, so the trend in the Pacific Northwest is clearly away from an ice-age type of climate at the current time. The data also demonstrate that a glaciologically significant long-term change in snow precipitation can occur rapidly, in as short an interval as 1 year, much more rapidly than changes in temperature.

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EXTRACT (SEE PDF FOR FULL ABSTRACT): The mass balance of glaciers depends on the seasonal variation in precipitation, temperature, and insolation. For glaciers in western North America, these meteorological variables are influenced by the large-scale atmospheric circulation over the northern Pacific Ocean. The purpose of this study is to gain a better understanding of the relationship between mass balance at glaciers in western North America and the large-scale atmospheric effects at interannual and decadal time scales.

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The Mundel Lake is an extremely shallow lagoon on the west coast of Sri Lanka. It is connected to the Puttalam Lagoon through 15 km long Dutch Canal. Salinity measurements and daily sea level data were obtained fortnightly from January 1993 to March 1994 and they were used to quantify the salt and water budget along with precipitation, evaporation and freshwater runoff. Extreme fluctuations of salinity and sea level are striking features of the system. Salinity of the Mundel Lake and Dutch Canal varied from 5-46.5 and 6 61 ppt respectively while the sea level ranged from -0.25 to +1.2 m. Tidal variations were not seen in the lagoon due to its long narrow canal system. Salt budget showed that the deposition of salt on the lagoon bottom during periods of decreasing water level. During increasing water level, salt is dissolved again. Flow of water through the Dutch Canal between the Puttalam Lagoon and Mundel Lake is driven by the changes in sea level. These changes are mainly due to seasonal changes of net freshwater supply and, to a lesser degree, to seasonal changes in sea surface height. As the flow rates are small due to the long and narrow canal, the residence time ranges between two months and several months in the Mundel Lake, except during season of high freshwater supply. As the water exchange is weak, the Mundel Lake becomes hyper saline with strong fluctuations in salinity. This implies a stress to all lagoon dwelling aquatic organisms and also to aquaculture practices in the area.