NOPR Collection:

Estimation of scattering coefficient of saline soil for slightly rough surface and undulating surface at microwave frequencies

Wed, 01 Dec 2004 00:00:00 GMT

Title: Estimation of scattering coefficient of saline soil for slightly rough surface and undulating surface at microwave frequencies Authors: Calla, O P N; Kalita, Himadri Sekhar Abstract: Microwave remote sensing of soil requires the study of electrical parameters of the soil like (permittivity, emissivity and scattering coefficient) along with its physical parameters like surface roughness and undulation. Out of these the dielectric constant can be used for estimating emissivity and scattering coefficient. Microwave backscattering from soil depends on its dielectric constant. In this paper the scattering coefficient has been estimated for a s lightly rough surface and undulating surface for saline soil, using the Perturbation Model and Geometric Optics Model. The database of the estimated scattering coefficient at X-band (8-10 GHz) for saline soil with different moisture content for both horizontal and vertical polarization and different look angles and two types of surfaces has been gene rated. The result shows that as the salinity increases, the scattering coefficient decreases. Also scattering coefficient increases with the increase in the moisture content. For active microwave remote sensing the scattering coefficient data for saline soil for different moisture content and for different types of surfaces are useful for image analysis and its applications. By using this database it is possible to design an active microwave sensor used for remote sensing of soil, which is largely useful in the field of agriculture. Page(s): 405-410

Moisture dependent Ku band microwave characteristics of red soil

Wed, 01 Dec 2004 00:00:00 GMT

Title: Moisture dependent Ku band microwave characteristics of red soil Authors: Puri, Vijaya; Darshane, S; Shaikh, S Abstract: In this paper a study of the Ku band (12-18 GHz) properties of red soil obtained from Shivaji University, Kolhapur, due to moisture has been reported. The attenuation in the transmitted and reflected mode of the wetted soil has been measured using standard gain horn antenna. The effect of the angle of incidence (0° and 45°) is also reported. For very low moisture content, angle of incidence and angle of reflection dependent effects are observed. The results indicate that for very low moisture content detection in red soil, angle of incidence of 45° is more suitable and angle of reflection of 60° is most sensitive. Page(s): 399-404

Surface ozone measurements over Himalayan region and Delhi, North India

Wed, 01 Dec 2004 00:00:00 GMT

Title: Surface ozone measurements over Himalayan region and Delhi, North India Authors: Ali, Kaushar; Momin, G A; Safai, P D; Chate, D M; Rao, P S P Abstract: Measurement of surface ozone concentration has been made at two Himalayan stations, Mohal (during 19-26 May 1999 and 20-25 May 2000) and Kothi (during 27 May –1 June 1999 and during 27-31 May 2000) and at Delhi (during 2-5 June 2000). The study reveals that the average concentration of ozone at Mohal was 19.1 ppb during May 1999 and 26.1 ppb during May 2000. At Kothi , the average concentrations were 42.7 ppb and 23.0 ppb, respectively, and it was 38.3 ppb at Delhi. Diurnal variation of ozone at Mohal indicated the dominance of photochemical production mechanisms in both the years. Lack of diurnal signal was seen at Kothi over the period of observation in 1999 which suggests that there may be transport of ozone in the region from upper level of the atmosphere. During observational period in 2000, a weak diurnal variation of O₃ was observed. It suggests that apart from photochemical production of ozone, some other mechanisms also contribute considerably to the observed O₃ concentration. At Delhi also, the diurnal variation showed the influence of temperature on O₃ production. Variation of O₃ concentration with O₃ concentration at previous hour, temperature, relative humidity at previous hour and wind speed at individual locations and years showed a good degree of association of O₃ with these parameters. Page(s): 391-398

Turbulent eddy characteristics in temperature and wind field of surface layer during MONTBLEX’90 over Jodhpur, India

Wed, 01 Dec 2004 00:00:00 GMT

Title: Turbulent eddy characteristics in temperature and wind field of surface layer during MONTBLEX’90 over Jodhpur, India Authors: Das, N; De, U K Abstract: Study of turbulent eddies is a very challenging topic, as it plays a dominant role in controlling the transport of atmospheric constituents in the tropical boundary layer. Tower data of temperature and horizontal wind speed collected by fast response sensors during MONTBLEX'90 (MONsoon trough Boundary Layer Experiment, 1990) field experiment, are considered here, to study the characteristics of the eddies. For this purpose autocorrelation has been performed, by applying a series of lags to different data set. Studying the value of autocorrelation, an attempt is made to determine the type and nature of turbulence eddies, which dominates in the surface boundary layer during the period concerned. The observation shows that turbulent plumes have a specific temporal scale during this period of study. At the same time the approximate spatial extension of the plumes in both horizontal and vertical directions is suggested for some general days as well as for some synoptically significant days. Lastly, comparative studies about the sensitivity of the sensors have been performed. Page(s): 380-390