5 results
Search Results
2. Delineation of precipitation regions using location and atmospheric variables in two Canadian climate regions: the role of attribute selection.
- Author
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Irwin, Sarah, Srivastav, Roshan K., Simonovic, Slobodan P., and Burn, Donald H.
- Subjects
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METEOROLOGICAL precipitation , *CLIMATE change , *WATER supply management , *BODIES of water , *FUZZY algorithms - Abstract
The identification of homogeneous precipitation regions is essential in the planning, design and management of water resources systems. Regions are identified using a technique that partitions climate sites into groups based on the similarity of their attributes; the procedure is known as regionalization. In this paper the ability of four attribute sets to form large, coherent precipitation zones is assessed in terms of the regional homogeneity of precipitation statistics and computational efficiency. The outcomes provide guidance for effective attribute selection for future studies in Canada. The attributes under consideration include location parameters (latitude, longitude), distance to major water bodies, site elevation and atmospheric variables modelled at different pressure levels. The analysis is conducted in two diverse climate regions within Canada including the Prairie and the Great Lakes–St Lawrence lowlands regions. The method consists of four main steps: (i) formation of the attribute sets; (ii) determination of the preferred number of regions (selection of thec-value) into which the sites are partitioned; (iii) regionalization of climate sites using the fuzzyc-means clustering algorithm; and (iv) validation of regional homogeneity usingL-moment statistics. The results of the attribute formation,c-value selection, regionalization and validation processes are presented and discussed in a comparative analysis. Based on the results it is recommended for both regions to use location parameters including latitude, longitude and distance to water bodies (in the Great Lakes region) to form precipitation regions and to consider atmospheric variables for future (climate change) applications of the regionalization procedure. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
3. Recent climate trends and future scenarios along the Egyptian Mediterranean coast.
- Author
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Shaltout, Mohamed, Gindy, Ahmed El, and Omstedt, Anders
- Subjects
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CLIMATE change , *COMPARATIVE studies , *ATMOSPHERIC models , *METEOROLOGICAL observations , *COMPUTER simulation , *SEA level , *METEOROLOGICAL precipitation , *ATMOSPHERIC temperature - Abstract
This paper analyses the present Egyptian Mediterranean coast (EMC) climate and the response of its climate variables to global changes. First, the accuracy of the ERA-Interim dataset (1979-2010) for the studied region is examined by comparing these data with available independent observations. Second, the qualities of six global climate models (GCMs), together with the ensemble mean of multiple model realisations of the A1B scenario, are examined by comparing these with the ERA-Interim dataset. Finally, GCM simulations are used to describe the uncertainties in future climate change along the EMC. The results indicate that the observations are in good agreement with the ERA-Interim data. The data for the EMC, 1979-2000, display a significant positive trend for 2-m air temperature together with significant negative trends for total precipitation and sea level pressure. The climate model that best describes the present EMC climate is the CGCM 3.1 model, which is used to describe the future climate of the study area. The CGCM 3.1 model indicates that the EMC area will experience significant warming, substantial droughts, and a weak decrease in sea level pressure in the end of the current century. [ABSTRACT FROM AUTHOR]
- Published
- 2013
4. Long-term temperature and precipitation trends at the Coweeta Hydrologic Laboratory, Otto, North Carolina, USA.
- Author
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Laseter, Stephanie H., Ford, Chelcy R., Vose, James M., and Swift Jr, Lloyd W.
- Subjects
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WATER temperature , *TIME series analysis , *CLIMATE change , *QUANTILES , *REGRESSION analysis , *METEOROLOGICAL precipitation , *ENVIRONMENTAL monitoring - Abstract
Coweeta Hydrologic Laboratory, located in western North Carolina, USA, is a 2,185 ha basin wherein forest climate monitoring and watershed experimentation began in the early 1930s. An extensive climate and hydrologic network has facilitated research for over 75 years. Our objectives in this paper were to describe the monitoring network, present long-term air temperature and precipitation data, and analyze the temporal variation in the long-term temperature and precipitation record. We found that over the period of record: (1) air temperatures have been increasing significantly since the late 1970s, (2) drought severity and frequency have increased with time, and (3) the precipitation distribution has become more extreme over time. We discuss the implications of these trends within the context of regional and global climate change and forest health. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
5. Present-day South American climate
- Author
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Garreaud, René D., Vuille, Mathias, Compagnucci, Rosa, and Marengo, José
- Subjects
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PALEOCLIMATOLOGY , *PRECIPITATION variability , *CLIMATE change , *ATMOSPHERIC circulation , *METEOROLOGY , *METEOROLOGICAL precipitation , *REGRESSION analysis - Abstract
Abstract: This paper documents the main features of the climate and climate variability over South America, on the basis of instrumental observations gathered during the 20th Century. It should provide a modern reference framework for paleoclimate research in South America, targeting high-resolution proxies over the past few centuries. Several datasets suitable for present-day climate research are first described, highlighting their advantages as well as their limitations. We then provide a basic physical understanding of the mean annual cycle of the precipitation and atmospheric circulation over the continent and the adjacent oceans. In particular, the diversity of precipitation, temperature and wind patterns is interpreted in terms of the long meridional extent of the continent and the disruption of the large-scale circulation caused by the Andes cordillera, the contrasting oceanic boundary conditions and the landmass distribution. Similarly, the intensity and timing of the interannual and interdecadal climatic fluctuations exhibit considerable geographical dependence, as some regions are more influenced by large-scale phenomena rooted in the tropical oceans while others are more influenced by high-latitude phenomena. The impact of these large-scale phenomena over South America is documented by a regression analysis between selected atmospheric indices and the precipitation and temperature fields. We have included a discussion on the seasonality and long-term stability of such impacts, and complemented our general description by an updated review of the literature on climate variability over specific regions. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
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