NOPR Collection:

Nose approximation method applied to Jovian whistlers

2016-10-24T06:52:59Z

Title: Nose approximation method applied to Jovian whistlers Authors: Chauhan, Pawan; Singh, Birbal Abstract: The nose approximation method developed by R L Dowden and G M Allcock [J Atmos & Terr Phys (GB), 33 (1971) 1125] for ground-observed whistlers has been applied to low dispersion Jovian whistlers observed by Voyager 1 spacecraft below the Io torus. The minimum electron gyrofrequencies along the propagation paths have been calculated graphically for three Jovian whistlers and the results obtained are found to be in very good agreement with the observed gyrofrequencies. The calculated nose frequencies of the Jovian whistlers are found to be around 36 kHz which are much above the upper cut-off frequencies of the Jovian whistlers and hence nose characteristics cannot be observed in such whistlers. Page(s): 132-136

Effect of endothermic reactions associated with lighting on atmospheric chemistry

2016-10-24T06:51:02Z

Title: Effect of endothermic reactions associated with lighting on atmospheric chemistry Authors: Chopkar, Shivkumar Abstract: Lightning creates high temperature which breaks N₂ and O₂ and form NO and O₃ through an endothermic process. These endothermic reactions absorb large amount of heat energy from the surroundings, as a result of which cooling may take place. An estimation of cooling produced has been made in this paper. The cooling thus produced may lead to several effects in the atmosphere; one among them could be an increase in rainfall rates. Page(s): 128-131

Seasonal-and latitudinal variations of stratospheric small ion density and conductivity

2016-10-24T06:49:13Z

Title: Seasonal-and latitudinal variations of stratospheric small ion density and conductivity Authors: Srinivas, N; Prasad, B S N Abstract: The seasonal and latitudinal variations of stratospheric small ion density and conductivity are studied using a simplified ion-aerosol model which includes the charged aerosol-ion recombination and charged aerosol-aerosol recombination, in addition to the usual ion-ion recombination and ion-aerosol attachment processes. The charged aerosol-ion recombination coefficient is computed from the model and the desirability of such a computation is discussed. The model computations in this study assume the background stratospheric aerosols (or Hake distribution), but the model is particularly useful in the study of stratospheric ion density and conductivity under conditions of enhanced stratospheric aerosols resulting from volcanic eruptions. The model results show seasonal and latitudinal variations of both small ion density N_± and conductivity σ_±. It has been shown that the latitudinal variation of σ_± is primarily controlled by the corresponding variation in N_±, whereas, the seasonal and height variations of σ_± are largely governed by the corresponding variations in the ion mobility b_±. The available experimental profiles for low, middle and high latitudes show good agreement with those from model prediction. Page(s): 122-127

A quasi-simplified approach for modelling stratospheric negative ions

2016-10-24T06:46:38Z

Title: A quasi-simplified approach for modelling stratospheric negative ions Authors: Beig, G; Chakrabarty, D K Abstract: During the past decade in situ measurements of stratospheric negative ion composition have revealed the occurrence of several interesting features. Total ion density has also been measured with greater accuracy. In the present paper, a quasi-simplified ion chemical scheme is used to reproduce these features. Finally, model profiles of major negative ion composition are given. In agreement with the observations, the model shows a sharp changeover of HSO core ions over NO core ions about 32 km and then a reversal at 42 km. Page(s): 114-121