http://nopr.niscpr.res.in/handle/123456789/17300 2026-10-11T22:16:55Z http://nopr.niscpr.res.in/handle/123456789/17454 Title: Dielectric properties of Bamboo and Canna plants leaves at 9.8 GHz Authors: Bhoopathy, T J; Anandavadivel, A; Mohanamani, P V Abstract: The complex permittivity of the tropical plants leaves, viz., Bamboo and Canna, has been measured at 9.8 GHz using thin sheet waveguide method. The experimental measurements are compared with the results of predicted dielectric models. The experimental values are found to agree well with one of these models. Page(s): 244-246 1999-10-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/17450 Title: Measurements of formic and acetic acid levels in vapour phase at urban and semi-urban sites of Delhi Authors: Jain, Monika; Kulshrestha, Umesh C; Sarkar, A K; Parashar, D C; Kumar, Ashok Abstract: The vapour phase acetic and formic acid levels were measured at two different sites of Delhi. Mean formic and acetic acid levels were found to be 1.66±0.81 and 5.83±2.24 ppbv, respectively, at the urban site of Rohini, while they were 2.51 ±1.22 and 2.92±1.78 ppbv, respectively, &nbsp;at National Physical Laboratory (NPL), a semi-urban site. Strong correlation between formic and acetic acids was observed at Rohini (correlation coefficient <i>r</i>=0.73) indicating similar source type for both the acids at this site, while at NPL, the correlation was very weak (<i>r=</i>0.19)<i> </i>indicating different sources of two acids. Page(s): 240-243 1999-10-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/17446 Title: Role of monsoon zonal flow on CISK instability and vice-versa—A sensitivity study Authors: De, S; Subrahmanyam, D Abstract: In order to study the effect of inclusion of idealized monsoon now on the stability characteristics, structures and energetics of the unstable modes arising due to the conditional instability of second kind (CISK) and vice-versa, a modified equatorial balance model of Murakami is executed with 7 different combinations of basic state parameters. The most important instability characteristics observed in the analysis are that (i) The unstable modes arising from the basic flow did not show much change in their characteristics with the introduction of CISK in the basic state; however, introduction of zonal flow modified the growth rate, phase speed and vertical structure of CISK mode unstable disturbances, and (ii) from the energetics study it is understood that the barotropic instability plays a dominant role, whereas baroclinic instability plays a stabilizing role for the unstable modes. Page(s): 232-239 1999-10-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/17440 Title: Long period atmospheric oscillations in the troposphere and lower and middle stratosphere over Hyderabad Authors: Basha, H Aleem; Joshi, M N; Bapiraju, B; Srinivasan, S; Rao, J V Subba; Dutta, Gopa Abstract: The monthly mean values of zonal and meridional winds for seventeen years over a tropical station, Hyderabad (17.2°N;78.2° E) have been used to study the characteristics of long period atmospheric oscillations, the QBO, AO, SAO and TAO, in the altitude range 7 - 32 km. Since the period of the data includes two solar maxima and one solar minimum the solar activity effects on various atmospheric parameters have been investigated. The annual oscillation in zonal wind is found to be strongly correlated with solar activity, whereas the prevailing zonal wind shows poor correlation. The correlation of solar activity with meridional wind parameters is also found to be very poor. The period of QBO and its heights of maxima are found to be affected by solar activity variation, whereas its amplitude is not. Page(s): 226-231 1999-10-01T00:00:00Z