An Operational System For Monitoring Oil Spills In The Mediterranean Sea: The PROMED System

The primary objective of this work was the development of an operational system for early detection of oil-spills, monitoring of their evolution, and provision of support to responsible Public Authorities during cleanup operations, based on Remote Sensing and GIS technologies. In case of emergency, the principal characteristics of the oil spill are defined with the aid of a space-borne synthetic aperture radar (SAR). The transport, spreading and dispersion of the oil spill is subsequently simulated on the basis of wind forecasts of the area. The use of thematic maps of protected, fishing and urban areas, and regions of high tourism allows the better assessment of the impact of an oil spill on the areas to be affected in terms of environmental sensitivity. Finally, reports are generated notifying port authorities, the media, and local organizations to be potentially affected by the presence of the oil spill. The pilot site for testing the PROMED System in Greece is the island of Crete

Multilayered feed forward Artificial Neural Network model to predict the average summer-monsoon rainfall in India

In the present research, possibility of predicting average summer-monsoon rainfall over India has been analyzed through Artificial Neural Network models. In formulating the Artificial Neural Network based predictive model, three layered networks have been constructed with sigmoid non-linearity. The models under study are different in the number of hidden neurons. After a thorough training and test procedure, neural net with three nodes in the hidden layer is found to be the best predictive model.Comment: 19 pages, 1 table, 3 figure

Recovery of Meteorological Data for the Observatory of A Guarda, Spain

We herein describe the recovery of a series of data on temperature, humidity, precipitation, evaporation, wind, and local weather conditions from documentary sources obtained from the Jesuit observatory of A Guarda (Galicia, Spain) for the period 1881–1896. The data were digitized and made available in accessible electronic formats. Comparisons were made with present-day meteorological data obtained from two nearby stations. We further believe that the discovery of some new complementary documentary sources made during the present research could be a basis for future data recovery efforts. Among these new results, early ozone data from the period are of outstanding importance to meteorologists

The Impact Of A Forest Fire On The Air Pollution Of An Urban Area: A Case-Study For Athens, Greece

In recent years Athens experienced severe air quality problems which are mostly attributed to motor vehicles and central heating. In addition to these pollution sources, forest fires taking place near urban areas may have a significant impact on the air quality of the city. We investigated this perspective by examining measurements of smoke and ozone taken in several sites within the Athens area for a time period during which a forest fire took place relatively close to Athens. The prevailing meteorological conditions supported the transfer of air masses from the burning forest area to the city. We find strong indications that the products of the forest fire influence significantly the levels of air pollution of the urban area, at least in terms of ozone and smoke. © 1992, Taylor & Francis Group, LLC. All rights reserved

A new method to improve the radiometric monitoring of atmospheric composition for photochemical active species: An application for nitric oxide

Studies that use satellite sensor measurements to determine the atmospheric composition require the conversion of measured radiances to concentration profiles. An important step in this process, is the correct treatment of radiative transfer. In several cases however, atmospheric species experience large and/or rapid changes in their distribution-at the time of measurements-which if neglected result in the inadequate treatment of radiative transfer and the subsequent inaccuracy of inversion algorithms. Parameterizing these changes is a way to treat the problem efficiently and a parameterization scheme for the temporal and spatial variability of nitric oxide is proposed in this Letter. The scheme is integrated in the inversion algorithm for the retrieval of the concentration of nitric oxide from satellite sensor occultation measurements and the performance of the algorithm is found to yield satisfactory results. © 1992 Taylor & Francis Group, LLC

A new method to improve the radiometric monitoring of atmospheric composition for photochemical active species: An application for nitric oxide

Studies that use satellite sensor measurements to determine the atmospheric composition require the conversion of measured radiances to concentration profiles. An important step in this process, is the correct treatment of radiative transfer. In several cases however, atmospheric species experience large and/or rapid changes in their distribution-at the time of measurements-which if neglected result in the inadequate treatment of radiative transfer and the subsequent inaccuracy of inversion algorithms. Parameterizing these changes is a way to treat the problem efficiently and a parameterization scheme for the temporal and spatial variability of nitric oxide is proposed in this Letter. The scheme is integrated in the inversion algorithm for the retrieval of the concentration of nitric oxide from satellite sensor occultation measurements and the performance of the algorithm is found to yield satisfactory results. © 1992 Taylor & Francis Group, LLC

A Photochemical Model for the Simulation of the Variability of Nitric Oxide and Nitrogen Dioxide at Sunset and Sunrise

A two-dimensional, stratospheric, photochemical model is constructed to simulate the variability of nitric oxide and nitrogen dioxide at sunset and sunrise for use in inversion algorithms which attempt to retrieve the concentration profiles of photochemically active species from satellite measurements. The model is applied for altitudes from 70 deg S to 70 deg N, and for altitudes from 10 km to 42 km; results for selected cases are presented, and are also compared to observations to show satisfactory agreement. The sensitivity of the inferred profiles of nitric oxide and nitrogen dioxide due to uncertainties in the used chemical rates, quantum yields, the temperature distribution and albedo are presented. The model provides a useful tool to adequately simulate the distribution of NO and NO2 at sunset and sunrise and also supports the understanding of chemical processes which are important for the abundance of stratospheric ozone. © 1994, Taylor & Francis Group, LLC. All rights reserved