NOPR Collection:

Study of scattering behaviour of dry and wet soil with undulating surface at microwave frequencies

2014-01-23T16:36:45Z

Title: Study of scattering behaviour of dry and wet soil with undulating surface at microwave frequencies Authors: Calla, O P N; Sharma, Santanu Abstract: The scattering coefficient is an important parameter in determining soil moisture content. In this study the surface under consideration is undulating type for which the geometric optics model is used to estimate the scattering coefficient. The estimation has been carried out at various frequencies for both vertical and horizontal polarization. The results show that the scattering coefficient increases with increase in soil moisture content. The scattering coefficient with vertical polarization is found to be lower than that found with horizontal polarization. With change in angle of incidence the variation of scattering coefficient is very small. Page(s): 332-336

Influence of calcium and sulphate on the pH of rainwater at Delhi

2014-01-21T16:38:54Z

Title: Influence of calcium and sulphate on the pH of rainwater at Delhi Authors: Tiwari, Suresh; Singh, J V; Momin, G A; Rao, P S P; Safai, P D; Ali, K Abstract: Rainwater samples were collected at three different locations during two consecutive summer monsoons of 1990 and 1991 at Delhi. These locations were Okhla, Red Fort and Rajinder Nagar which represent industrial, commercial and residential locations, respectively. The major anions (Cl, SO₄, and NO₃) and cations (Na, K, Ca, Mg and NH₄) along with pH of the above samples were determined. The bicarbonate (HCO₃) concentrations were also calculated. High levels of Ca and SO₄ were observed. Together, Ca and SO₄ made up more than 50% of the total ion mass, while Ca alone contributed over 55% of the total cations mass. The pH value of rainwater was found to be alkaline in nature with an average of 6.13 and the values varied from 5.01 to 7.12. The relative importance of natural and anthropogenic sources was estimated by chemical balancing. In some cases, acidity was found due to the presence of sulphuric and nitric acid. High concentration of soil-oriented elements especially Ca has been found to play an important role in neutralizing the acidity of rainwater and maintaining high alkaline pH. Most of the SO₄ in rainwater was in the form of CaSO₄. The results of the present study suggested that the atmospheric composition in the city has been strongly influenced by natural sources (sea and soil) rather than anthropogenic sources. Page(s): 325-331

Impact of low level clouds on convective boundary layer equilibrium structure

2014-01-20T16:39:13Z

Title: Impact of low level clouds on convective boundary layer equilibrium structure Authors: Morwal, Savita B Abstract: A study has been carried out using the concepts of saturation point and conserved variable plots utilising the aerological observations collected at an inland station, Pune (18°32'N, 73°5 1'E, 559 m a.s.1.) during the summer monsoon seasons of 1980 and 1981 to investigate the impact of low level clouds on equilibrium structures in the atmospheric boundary layer (ABL). The days have been categorized according to the distribution of clouds vis-a-vis equilibrium structure of ABL. The study suggested a close association between amount of clouds in the lower atmosphere and the thermodynamical characteristics of ABL. The results of the study are discussed. Page(s): 319-324

Diurnal evolution of temperature profile of troposphere and lower stratosphere using MST radar

2014-01-20T16:39:45Z

Title: Diurnal evolution of temperature profile of troposphere and lower stratosphere using MST radar Authors: Revathy, K; Mrudula, G; Nayar, S R Prabhakaran; Murthy, B V Krishna Abstract: The observation of the fluctuations in the vertical wind using MST radar provides an excellent opportunity to determine the temperature profile of the troposphere-stratosphere region. The MST radar is operated in the temperature mode to evaluate the diurnal evolution of the temperature profile. Using these values, the diurnal variation of the temperature at different altitude ranges is calculated. The height variation of the tropopause within a day is also calculated from these results. Page(s): 315-318