A quiet day empirical model of electron density in the Indian equatorial F-region

In this paper, we present a quiet day empirical model of electron density (Ne) for the Indian equatorial zone at an altitude of 500 km. The model is applicable to all levels of solar activity and is based on the observation that the electron density in the F-region of the Indian zone is correlated with the F10.7 cm solar flux at each local time and in every month. Using this characteristic, we describe the model for electron density. In this model, we have used the least square fit and the polynomial fit. The electron density measured by the Retarding Potential Analyzer (RPA) on board the SROSS C2 satellite from 1995 to 2000 and FORMOSAT-1 (ROCSAT-1) satellite, operated by the National Space Organization (NSPO, now the Taiwan Space Agency (TASA)) of the Republic of China (Taiwan), from 1999 to 2004 is used to derive the relationship between Ne and F10.7. The average altitudes of SROSS-C2 and FORMOSAT-1 are 500 km and 600 km respectively. Due to this height difference, the observed data obtained by FORMOSAT-1 is normalized to match the SROSS-C2 data. The model is compared with the observations and is found to be in good agreement with them. It is applicable to quiet (Ap<15) conditions and is limited to a fixed altitude of 500 km within the latitude range of 10° S to 10° N around the 75° E meridian

Design and fabrication of a data logger for atmospheric pressure, temperature and relative humidity for gas-filled detector development

A novel instrument has been developed to monitor and record the ambient pa- rameters such as temperature, atmospheric pressure and relative humidity. These parameters are very essential for understanding the characteristics such as gain of gas filled detectors like Gas Electron Multiplier (GEM) and Multi Wire Propor- tional Counter (MWPC). In this article the details of the design, fabrication and operation processes of the device has been presented.Comment: 11 pages, 12 figure

Possible impact of a major oil-well fire on aerosol optical depth at Dibrugarh

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Estimation of the effect of long-range transport on seasonal variation of aerosols over northeastern India

Spectral aerosol optical depth (AOD) at ten discrete channels in the visible and near IR regions were estimated over Dibrugarh, located in the northeastern part of India, using a ground-based multi-wavelength solar radiometer (MWR) from October 2001 to February 2006. The observations reveal seasonal variations with low values of AODs in retreating monsoon and high values in the pre-monsoon season. Generally the AODs are high at shorter wavelengths and low at longer wavelengths. AOD spectra are relatively steep in winter compared to that in the monsoon period. The average value of AOD lies between 0.44±0.07 and 0.56±0.07 at 500 nm during the pre-monsoon season and between 0.19±0.02 and 0.22±0.02 during re-treating monsoon at the same wavelength. Comparison of MWR observation on Dibrugarh with satellite (MODIS) observation indicates a good correspondence between ground-based and satellite derived AODs. The synoptic wind pattern obtained from National Centre for Medium Range Weather Forecasting (NCMRWF), India and back trajectory analysis using the NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT4) Model indicates that maximum contribution to aerosol extinction could be due to transport of pollutants from the industrialized and urban regions of India and large amounts of desert and mineral aerosols from the west Asian and Indian desert. Equal contributions from Bay-of- Bengal (BoB), in addition to that from the Indian landmass and west Asian desert leads to a further increase of AOD over the region of interest in the pre-monsoon seasons