NOPR Collection:

Adding incoherent scatter mode to the Indian MST radar for upper atmospheric studies

Tue, 01 Oct 1991 00:00:00 GMT

Title: Adding incoherent scatter mode to the Indian MST radar for upper atmospheric studies Authors: Mahajan, K K Abstract: A powerful transmitter and a large transmitting-receiving antenna are the basic requirements of an incoherent scatter radar. The system specifications of the Indian MST radar located at Gadanki (13.5°N, 79°E) with peak power-aperture product of about 3 x 10¹⁰ Wm² meet these requirements. Although the operating frequency of 53 MHz is not ideal for incoherent scatter sounding (due to very large sky background noise at this frequency), the signal can be usefully processed to obtain some basic ionospheric parameters like electron density, electron temperature, ion temperature, ion composition, ion drifts and E-region collision frequency. This radar, being located a little away from the electrojet, will also be able to make measurements for heights below 200 km, where the Jicamarca radar cannot. An immediate contribution in the incoherent scatter mode would be electron density measurements in the E-F valley for which no information is available for an equatorial station. Further, the radar would also prove useful for studies of equatorial spread-F, winds and waves in the thermosphere and equatorial anomaly. Page(s): 388-395

Polar E-region irregularity structures

Tue, 01 Oct 1991 00:00:00 GMT

Title: Polar E-region irregularity structures Authors: Rinnert, K Abstract: Sufficiently large d.c. electric fields destabilize the E-region plasma and generate plasma irregularities which can be observed by coherent radars. To study these structures rockets have been launched into the polar E-region Details and statistics of the a.c. electric fields due to the plasma irregularities are given and a model is presented to describe the wave structures. Page(s): 383-387

Laser probing of trace gases in the atmosphere

Tue, 01 Oct 1991 00:00:00 GMT

Title: Laser probing of trace gases in the atmosphere Authors: Saha, A K Abstract: The importance of trace gases in the mesosphere, stratosphere and, particularly in the troposphere is described. Measurement techniques are discussed with an emphasis on remote sensing and laser probing. The growth of laser probing work at the National Physical Laboratory, New Delhi, and a planned programme at the University of Calcutta, are also outlined. Page(s): 381-382

Lidar probing of the atmosphere

Tue, 01 Oct 1991 00:00:00 GMT

Title: Lidar probing of the atmosphere Authors: Thomas, L Abstract: The optical interactions employed in lidar measurements at ultraviolet and optical wavelengths are briefly reviewed, and results derived from ground-based and airborne systems are described. Particular attention is paid to applications of the technique directed towards measurements of environmental and meteorological parameters of interest: the occurrence and characterization of cirrus and polar stratospheric clouds, the height distribution of water vapour in the troposphere, the height distributions of ozone in the troposphere and stratosphere, and the thermal structure and dynamics of the stratosphere and mesosphere. Finally, an indication is given of the measurements planned for space-borne systems in the 1990s and of the developments in the laser technology making these measurements possible. Page(s): 368-380