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1. Simulating the Use of a Smelter Off-Gas in the Precipitation Stage of the Pedersen Process †.

Author

Manataki, Andriani, Mwase, James M., and van der Eijk, Casper

Subjects
METEOROLOGICAL precipitation, ALUMINUM, METALLURGY, LIMESTONE
Abstract

The Pedersen process is an alumina production process, which combines pyrometallurgical and hydrometallurgical methods. In the pyrometallurgical stage, limestone is calcined and CO2 is generated. This off-gas can be captured with a high CO2 concentration. At the end of the hydrometallurgical process, aluminum hydroxides, like bayerite, are precipitated using CO2. In this paper, experimental work on precipitation of aluminum hydroxides through the addition of a mixture of CO2, O2 and N2 is presented. The parameters varied, as were the percentages of each gas and the temperature. The indicators measured were the time until the beginning of precipitation and the time that the precipitation lasts. These tests simulate the use of a smelter furnace off-gas in the precipitation stage of the Pedersen process and have shown promising results. [ABSTRACT FROM AUTHOR]

Published
2023
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2. Climate change impacts on hydrometeorological variables using a bias correction method: The lake Karla watershed case.

Author

Tzabiras, John, Vasiliades, Lampros, Loukas, Athanasios, and Mylopoulos, Nikitas

Subjects
CLIMATE change research, HYDROMETEOROLOGY, WATERSHEDS, METEOROLOGICAL precipitation, TIME series analysis
Abstract

This paper is dealing with the assessment of climate change scenarios on selected meteorological variables at the Lake Karla watershed, central Greece and it is a contribution to the "HYDROMENTOR" research project. A statistical downscaling method has been employed to estimate monthly precipitation and temperature time series for future climate periods. The outputs of the Canadian Centre for Climate Modeling Analysis Global Circulation Model CGCM3 were applied for three socioeconomic scenarios, namely SRES B 1, SRES A 1B and SRES A2 for the assessment of climate change impact on precipitation and temperature. The methodology has been developed for the historical period 1980-2000 and applied for two future periods 2030-2050 and 2080-2100. Historical and future periods were compared for monthly and annual basis using various statistical criteria such as the mean and standard deviation. Results showed that climate change will have minor impacts on precipitation and even smaller impacts on temperature. [ABSTRACT FROM AUTHOR]

Published
2015

3. Statistical Downscaling of ERA5 Reanalysis Precipitation over the Complex Terrain of Greece.

Author

Ntagkounakis, Giorgos E., Nastos, Panagiotis T., and Kapsomenakis, Yiannis

Subjects
METEOROLOGICAL precipitation, DOWNSCALING (Climatology), REGRESSION trees, HISTOGRAMS
Abstract

In this study, we present the preliminary results of our effort to construct a new high spatial resolution precipitation database (1 km x 1 km) over Greece, on an annual and monthly basis. A variety of spatial parameters (i.e., latitude, longitude, altitude, aspect, distance from water bodies, among others) and ERA5 reanalysis data were used as independent variables in an algorithm combined with the Regression Kriging with a Histogram-Based Gradient-Boosting Regression Tree. The dependent variable in the algorithm was the gauge data covering most of the area studied. Maps were constructed for the ERA5 reanalysis and the modelled mean precipitation totals on an annual and monthly basis for the 1980-2010 study period. The findings of the analysis show that the applied methodology improves the spatial resolution and distribution of the ERA5 reanalysis precipitation totals over Greece. Furthermore, when comparing the modelled high spatial resolution datasets against ERA5 datasets over the gauge precipitation totals, the model achieved an average R² improvement of 31.7%, with the largest improvement recorded on an annual basis, while the RMSE decreased by 16.6% on average and more than 40% on an annual basis. [ABSTRACT FROM AUTHOR]

Published
2023
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4. Integrated analysis of present and future responses of precipitation over selected Greek areas with different climate conditions.

Author

Paparrizos, Spyridon, Maris, Fotios, and Matzarakis, Andreas

Subjects
*METEOROLOGICAL precipitation, *CLIMATE change, *DOWNSCALING (Climatology), *INTERPOLATION, *SIMULATION methods & models
Abstract

The assessment of future precipitation variations prevailing in an area is essential for the research regarding climate and climate change. The current paper focuses on 3 selected areas in Greece that present different climatic characteristics due to their location and aims to assess and compare the future variation of annual and seasonal precipitation. Future precipitation data from the ENSEMBLES anthropogenic climate-change (ACC) global simulations and the Climate version of the Local Model (CLM) were obtained and analyzed. The climate simulations were performed for the future periods 2021–2050 and 2071–2100 under the A1B and B1 scenarios. Mann–Kendall test was applied to investigate possible trends. Spatial distribution of precipitation was performed using a combination of dynamic and statistical downscaling techniques and Kriging method within ArcGIS 10.2.1. The results indicated that for both scenarios, reference periods and study areas, precipitation is expected to be critically decreased. Additionally, Mann–Kendall test application showed a strong downward trend for every study area. Furthermore, the decrease in precipitation for the Ardas River basin characterized by the continental climate will be tempered, while in the Sperchios River basin it will be smoother due to the influence of some minor climatic variations in the basins' springs in the highlands where milder conditions occur. Precipitation decrease in the Geropotamos River basin which is characterized by Mediterranean climate will be more vigorous. B1 scenario appeared more optimistic for the Ardas and Sperchios River basins, while in the Geropotamos River basin, both applied scenarios brought similar results, in terms of future precipitation response. [ABSTRACT FROM AUTHOR]

Published
2016
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