B.B. Balsley

Electric fields in the equatorial ionosphere: A review of techniques and measurements

Abstract This paper reviews the techniques and experimental results of measurements of ionospheric drifts and electric fields in the region of the magnetic dip equator. Various techniques are discussed and the results are compared with existing theoretical electric field models.

MST radar studies of wind and turbulence in the middle atmosphere

Abstract A survey is presented of recent developments in the observation of wind and turbulence in the stratosphere and mesosphere using MST radars. One of the highlights of these developments is the growing recognition that the MST/ST radar is a valuable tool for routine monitoring of the atmospheric wind field. Furthermore, preliminary observations have shown the feasibility of monitoring atmospheric turbulence as well. Recent observations of mesospheric turbulence support theoretical models that emphasize the role of propagating waves in coupling the lower and middle atmospheres. Scientific groups in several countries are now planning or constructing MST radars so that within a few years observations should be available from diverse geographical locations spanning the globe.

A question of DP-2

Abstract The geomagnetic DP-2 variation and its equivalent current system are re-examined using not only ground-based geomagnetic data and interplanetary magnetic field but also radar observations of the electron drift velocity in the equatorial electrojet over Jicamarca, Peru. The Jicamarca observations clearly indicate that the DP-2 electric current direction in low latitudes is questionable and that the whole concept of the DP-2 needs to be reconsidered.

Continuous measurement of upper atmospheric winds and turbulence using a VHF Doppler radar: preliminary results

Abstract We report here preliminary results of a VHF radar experiment designed to monitor atmospheric winds and turbulence continuously over periods of many days. The radar system used in this experiment is a prototype of a much larger system under development and uses an average transmitted power of about 200 W and a 100 m × 100 m dipole array. With this system it is possible to observe winds and turbulence parameters regularly to about 19 km using a height resolution of 2.2 km. Similar results are reported for mesospheric heights between about 73 km and 82 km.

The MST technique—a brief review

Abstract The purpose of this paper is to briefly review the MST (mesosphere-stratosphere-troposphere) radar technique for remotely observing the atmosphere in the height range 1–100 km. Particular emphasis will be directed here toward aspects of the subject related to the equatorial atmosphere—a region in which the overall circulation and dynamics is poorly understood. Some of the current MST capabilities will be demonstrated via data obtained from existing observatories located in the tropics. A case will be made for the necessity of having additional equatorial-region observatories, and an example of a reasonably economical system will be discussed.

E-region dynamics

Abstract This review will outline the basic types of dynamic processes observed in the equatorial E -region. Time scales of these dynamic motions range from a few seconds to a few hours. Observed spatial scales include turbulent-like three-meter irregularity motions as well as macroscopic dynamic motions having dimensions of a few hundred kilometers. Evidence showing large day-to-day variations in E -region currents, electric fields, and neutral winds will be presented and possible causal processes will be discussed.

Irregularity drift velocities in the equatorial electrojet observed by both the close-spaced antenna technique and the Doppler radar method

Electrojet drift data using both HF and VHF Doppler techniques and the close-spaced receiver technique were obtained simultaneously in Chad, Africa, during the June 1973 solar eclipse expeditions. n nThe close-spaced receiver method (D1) of the Sarh (Fort Archambault) station was run intensively during June and July 1973. Two phase-coherent Doppler radar systems working at different frequencies (50 MHz, 21 MHz) were set up at Sarh station and a third Doppler radar was installed at Fort Lamy. All systems were run during a few days simultaneously with the D1 system. The drift velocities observed by the Doppler technique are compared with the close-spaced receivers data in this paper. Under normal conditions the two methods show similar drifts. There are periods, however, possibly associated with increased magnetic activity, when the D1 drift data are in excess of the Doppler data by more than a factor of two. Furthermore, while reversals are regularly observed by the close-spaced technique, few are detected by the Doppler radars during day-time, due to the disappearance of the cross-field instability. It is therefore necessary to associate the irregularities observed by the close-spaced receivers technique with another process.

A note on reducing the horizontal sidelobes of near-vertically directed COCO arrays

A method of modifying quasibroadside arrays of coaxial collinear (COCO) antennas in order to significantly reduce horizontal sidelobe levels is discussed. Tests made prior to and after these modifications show a sidelobe reduction of more than three orders of magnitude. >

Clear-Air Radar Technology: Panel Report

The use of sensitive, coherent radar systems operating in the UHF-VHF frequency range (30–3000 MHz) to measure and monitor the dynamics of the atmosphere has to be one of the most explosive and far-reaching developments to take place throughout all of meteorology. This field has matured rapidly in the decade and a half since Woodman and Guillen (1974) published the initial continuous measurements of the horizontal and vertical wind fields by a high-powered coherent VHF radar. We have progressed from initial studies using radar systems dedicated primarily to other uses, to the design and use of systems specifically intended for continuous measurements of atmospheric parameters. The success of these developments is exemplified by the fact that clear-air systems—indeed networks of such systems—are currently coming on line as operational entities. The future use of these systems in the national picture, as well as on an international scale, is secure.