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

Atmospheric ozone variability in the context of global change

A survey has been made of the role and place of atmospheric ozone dynamics in both the stratosphere and troposphere in the context of global change. Impacts on the ozone layer from solar activity (extraterrestrial solar ultraviolet irradiance variations), volcanic eruptions and high-flying aircraft have been discussed. Tropospheric ozone and surface ultraviolet irradiance changes have been considered, including relevant biological implications. Influences of the stratospheric ozone depletion on climate change have been discussed with emphasis on a coupled nature of ozone-climate interrelations. A necessity has been substantiated to develop a complex ozone studies programme in the context of the World Climate Research Programme and the International Geosphere-Biospbere Programme. © 1995 Taylor & Francis Group, LLC

Temporal Variations of the Total Ozone Content Over St. Petersburg

The observations with the Dobson spectrophotometer and the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus-7 satellite have been used to assess the trends of the total ozone content over St. Petersburg (60°N, 30°E), since 1968 and 1978, respectively for various months. The analysis performed shows that the natural fluctuations of the total ozone content due to Quasi - Biennual Oscillation and El Nino/Southern Oscillation have minor contribution to the total ozone depletion trend comparing with the strong variations of the total ozone depletion trend from month to month due to other causes. © 1994, Taylor & Francis Group, LLC. All rights reserved

Global tropospheric ozone dynamics: Part I: Tropospheric ozone precursors

(Part I). An overview of the tropospheric ozone changes is presented focussing mainly on the tropospheric ozone precursors. The complexity of the problem is shown through the consideration of a great number of relevant substances, like nitrogen compounds, volatile organic compounds, peroxyacetyl nitrate, hydroxyl radical, carbon monoxide, alkyl nitrates. The up-to-date knowledge on the relevant numerical modelling is presented in Part II

Volcanic eruptions and global ozone dynamics

It is well known that heterogeneous chemistry plays a very important role in global ozone dynamics. A survey of new observations and numerical modelling results has been made to analyse the potential impact of volcanic eruptions on the stratospheric ozone layer in the context of the heterogeneous chemical reactions on surfaces of volcanically produced stratospheric aerosol particles. An important aspect of the problem is that volcanically induced ozone changes may lead to a substantial impact on the radiative forcing for the surface-troposphere system and, subsequently, on climate. © 1995 Taylor & Francis Group, LLC

Temporal Variations of the Total Ozone Content Over St. Petersburg

The observations with the Dobson spectrophotometer and the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus-7 satellite have been used to assess the trends of the total ozone content over St. Petersburg (60°N, 30°E), since 1968 and 1978, respectively for various months. The analysis performed shows that the natural fluctuations of the total ozone content due to Quasi - Biennual Oscillation and El Nino/Southern Oscillation have minor contribution to the total ozone depletion trend comparing with the strong variations of the total ozone depletion trend from month to month due to other causes. © 1994, Taylor & Francis Group, LLC. All rights reserved

Remote sensing and global tropospheric ozone observed dynamics

The development of remote sensing techniques to obtain measurements of ozone and its precursors from the Earth's surface to the tropopause is considered, to present a review on the current achievements in measuring tropospheric ozone variability. Special attention is given to the surface ozone concentration observations, to the production and destruction mechanism of ozone in both the atmospheric boundary layer and the free troposphere, and finally to ozone exchange through the tropopause. © 2002 Taylor and Francis Ltd

The role of clouds on the solar ultraviolet radiation

The interaction of the various cloud types with the radiation field is examined through a simple parametric model. Furthermore a statistical analysis of the coverage of the Greek region by various cloud types for various seasons is presented in order to be taken into account for the application of the spectral solar ultraviolet radiation reaching the ground. © 1995, Taylor & Francis Group, LLC. All rights reserved