NOPR Collection:

Airborne microwave refractometer studies over the Indian subcontinent for exploiting electromagnetic propagation effects

1993-02-01T00:00:00Z

Title: Airborne microwave refractometer studies over the Indian subcontinent for exploiting electromagnetic propagation effects Authors: Sarma, S B S S Abstract: Open ocean and coastal marine environments contain vertical and horizontal refractive index variations that have profound impact on the operation of shipboard systems. Airborne microwave refractometer gives accurate high-resolution-radio-refractivity structures of the order of even few centimeters. Some information have been collected using airborne microwave refractometer and reported in this communication. Rapid variability in modified refractivity gradients due to turbulence has also been observed. Page(s): 67-68

Role of F-region east-west drifts on the developments of equatorial anomaly in the American, African and Asian sectors

1993-02-01T00:00:00Z

Title: Role of F-region east-west drifts on the developments of equatorial anomaly in the American, African and Asian sectors Authors: Aydogdu, Mehmet; Ozcan, Osman Abstract: The role of F-region east-west drifts on the vertical velocity overhead the American, African and Asian magnetic equators has been studied to search for longitudinal differences in the developments of equatorial anomaly. It is shown that the vertical velocity in F-region has a part determined by (k_1i/k_2i) V_y. Longitudinal differences in k_1i/k₂ ratio give rise to different ion velocities at these sectors. This is likely to cause different equatorial F-layer fountain magnitudes resulting in different developments of the equatorial anomaly. Page(s): 65-66

Sodar studies of aerosol size distribution and concentration at Delhi

1993-02-01T00:00:00Z

Title: Sodar studies of aerosol size distribution and concentration at Delhi Authors: Pahwa, D R; Singal, S P; Khemani, L T Abstract: Aerosol size distribution and concentration have been measured using Andersen Particle Cascade Impactor and GMW High Volume Sampler respectively. Sampling was done as per the stability conditions of fumigation period, unstable convective conditions (free mixing), and nocturnal stable period. Size distribution and concentration of particulate matter have been found to be related to sodar determined stability and mixing height of the boundary layer at Delhi. Page(s): 62-64

Mass size distribution and chemical composition of aerosols at the Silent Valley, India

1993-02-01T00:00:00Z

Title: Mass size distribution and chemical composition of aerosols at the Silent Valley, India Authors: Safai, P D; Khemani, L T; Momin, G A; Rao, P S P; Pillai, A G Abstract: Field observational programmes were undertaken at the Silent Valley, a core zone of the Nilgiri Biosphere Reserve, in three different seasons during 1989-90 to study the mass size distributions of atmospheric aerosols and some of their water soluble components (SO₄, NO₃, K and Ca). The average concentration of total suspended particulates was 37µg/m³ which is far below the values reported from urban and non-urban regions in the country. Atmospheric aerosols, S0₄, K and Ca showed bimodal distributions, whereas NO₃ showed unimodal distribution in all the three seasons. Although the aerosols showed bimodal distribution, the contribution of submicron particles was higher than that of coarse particles. This is the peculiarity of forest region which was not observed in other parts of the country where coarse particles dominate over the submicron particles. Another special feature observed was the mass size distribution of K aerosols which showed bimodal distribution with a prominent peak in the submicron size range. It has been observed from the mass size distributions of aerosols and some of their chemical components that most of them are in submicron size range, acidic in nature, and can cause acidification on precipitation in the region. Page(s): 56-61