Processing techniques for the estimation of the power, the frequency shift, and the spectral width of mesosphere-stratosphere-troposphere (MST) radar returns are presented. The differential techniques are compared in terms of statistical goodness of the estimators and in terms of computational convenience and simplicity.

Se ha desarrollado un programa en BASIC para el cálculo de hipocentros en base a los tiempos de arribo de las ondas P a tres estaciones sísmicas, y el tiempo de arribo de una onda S a una de las es­taciones, si esta estuviera disponible. El programa, entre código y constantes, usa menos de 1500 ca­racteres y cabe en una microcomputadora de bolsi­llo, las que, hoy en día, se pueden conseguir en el mercado por menos de US $ 150. El programa fue motivado por las necesidades del Instituto Geofí­sico del Perú, pero tiene una aplicación más uni­versal cuando se considera su portabilidad y costo. Los algoritmos utilizados son descritos en detalle, definiendo en esta forma sus alcances y limitaciones.

En: Middle Atmosphere Program. Handbook for map, volume 30 / Edited bt: S. Fukao. Capítulo de libro: p. 114-150.

One of the oldest scientific topics in Equatorial Aeronomy is related to Spread-F. It includes all our efforts to understand the physical mechanisms responsible for the existence of ionospheric F-region irregularities, the spread of the traces in a night-time equatorial ionogram – hence its name – and all other manifestations of the same. It was observed for the first time as an abnormal ionogram in Huancayo, about 70 years ago. But only recently are we coming to understand the physical mechanisms responsible for its occurrence and its capricious day to day variability. Several additional techniques have been used to reveal the spatial and temporal characteristics of the F-region irregularities responsible for the phenomenon. Among them we have, in chronological order, radio star scintillations, trans-equatorial radio propagation, satellite scintillations, radar backscatter, satellit...

En una página anterior ( http://www.igp.gob.pe/enero.htm) anunciamos que veníamos trabajando en un método estadístico de regresión múltiple para mejorar nuestro pronóstico de lluvias. Los resultados se muestran en la Figura 1. Esta muestra la historia de las precipitaciones acumuladas mensualmente en mm en la ciudad de Piura y los resultados de la fórmula de regresión encontrada. La fórmula se basa sólo en la temperatura superficial del mar (TSM) en el norte del Perú y el mes del año. La similitud de las dos curvas es muy buena. Vale mencionar que los valores de Diciembre 97, Enero y Febrero 98 no fueron usados en la evaluación de los coeficientes, lo que nos da aún mayor confianza en la fórmula. La regresión usa cuatro valores de la TSM a unos 500 km. de la costa en latitudes de 25, 4, 5 y 7.5 grados sur más el mes del año.

Uno de los problemas más importantes para la humanidad - y de gran interés para la ciencia - es la posibilidad de que el hombre altere el medio ambiente en el cual vive. Estas alteraciones pueden suceder en dos escalas: en una escala local o regional y la otra a nivel global. Entre los problemas de "cambios globales" se encuentra el de la disminución de la capa de ozono que nos protege de los rayos ultravioletas y el calentamiento de la atmósfera por el efecto invernadero. El proyecto conocido como "Radar MST en la Antártida" del Instituto Geofísico del Perú (IGP) en colaboración con la Universidad de Piura y la Dirección de Hidrografía y Navegación de la Marina está dirigido a contribuir a un mejor entendimiento de los procesos físicos responsables de estos cambios.

The potential to observe the E-W electric field in the equatorial ionosphere using the strong coherent echoes obtained by the Jicamarca radar from irregularities present at the Magnetic Equator, in the altitude range between 135 and 175 km, has been established by Kudeki and Fawcett (September, 1993). They based their claims by comparing vertical drift measurements at these altitudes with simultaneous ground magnetogram records made in Ancon, which showed a high non linear correlation between the two. In this paper we present more direct correspondence by comparing simultaneous measurements made at F-region heights, using the standard I.S. technique with measurements made using the coherent echoes at the 135-175 km altitude. The correspondence is one to one. In addition, it is shown that there is also correspondence between the E-W drifts (vertical component of the electric field) measur...

La ciencia de la sismología nos permite determinar la magnitud y ubicación de un sismo con instrumentos remotos con toda la exactitud necesaria. Conocidas la ubicación y la magnitud se puede estimar los daños causados en todas las poblaciones afectadas, tanto los daños materiales en las edificaciones y casas habitación como en estimado de la cantidad de heridos y muertos en una catástrofe.

Este artículo describe el radar coherente VHF instalado a bordo del Buque de Investigación Científica B.I.C. Humboldt. El sistema fue diseñado y construido en el Radio Observatorio de Jicamarca. El instrumento cuenta con un arreglo de antenas tipo COCO de 24x2 l m, especialmente diseñado para su instalación en un buque. Se presenta una descripción del instrumento, así como los primeros resultados de las observaciones de Ecos Mesosféricos Polares de Verano (PMSE) en la Antártida y del Electrochorro Ecuatorial a lo largo de la costa Sur del Perú.

Radars are used for remota probing of the upper atmosphere. Monstatic and bistatic configurations have been used. The echoes are obtained from the scattering of the illuminating wave by fluctuations in the dielectric propercies of the medium under study. The fluctuations in the local dielectric constant of a medium are direct consequence of fluctuations in the density of the medium or more properly on the density of that component or components in the medium responsable for its dielectric behaviour, e.g. electron density in a ionized gas, "air" density and water vapor in the lower atmosphere, etc.

13 p.

Ponencia preparada para la: Swedish Institute of Space Physics (Institutet för Rymdfysik, IRF).

There are at present three radar frequencies that are being ex­ploited: 50, 430 and 2380 MHz. (In addition, there is a range of HF frequencies in a bi-static mode, using the Heating Facility to illuminate, but which we will not discuss here, since there would be no benefits to be derived from the upgrading.) The proposed upgrading of the Arecibo 300 meter antenna will benefit the research work in the three regions of the atmosphere we have mentioned above through improved performance in the three existing radars, including multifrequency operation.

3 p.

Some characteristic parameters of gravity waves at D and E region heights such as amplitude, frequency spectrum and spatial properties can and have been measured by means of VHF radars. One of the techniques makes use of ionization trails produced by meteors as tracers of the neutral atmosphere motions in the region from 80 to 100 km. A recently developed technique at the Jicamarca Radio Observatory uses background enhanced fluctuations in the dielectric properties of the medium as tracers of the neutral motions in the region between 60 and 85 km. Profiles of the velocity field can be obtained continuously with a time resolution of the order of a minute allowing observations of gravity waves from its lowest periods, of the order of a few minutes, to tidal periods. Gravity waves in the lower F region have also been detected using incoherent scatter techniques. The methods, potential and l...

3 p.

Supplement to TN D-1419. "A Phase-Locked Phase Filter for the Minitrack System", 13 p.

Equatorial electric field measurements were recently reviewed by B. Balsley on occasion of the last equatorial symposium. We present in this review new measurements reported in the literature since the last symposium and include a large amount of new unpublished measure­ments of the vertical and East-West electric fields performed at Jicamarca using the incoherent scatter technique. The data base at Jicamarca comprises now almost a full solar cycle. The effects of low solar activity are discussed. The main effects being: (1) A reduction in the night-time maximum amplitude of the E-W drift; (2) an increase in the frequency of occurrence of afternoon reversals of the vertical drift (E-W electric field); (3) a reduction in the amplitude and fre­quency of occurrence in the prereversal (post-sunset) vertical drift enhancement.

10 p.

The recently developed technique for imaging radar scattering irregularities has opened a great scientific potential for ionospheric and atmospheric coherent radars. These images are obtained by processing the diffraction pattern of the backscattered electromagnetic field at a finite number of sampling points on the ground. In this paper, we review the mathematical relationship between the statistical covariance of these samples, (fft), and that of the radiating object field to be imaged, (FFt), in a self-contained and comprehensive way. It is shown that these matrices are related in a linear way by fft) = aM(FFt)Ma*, where M is a discrete Fourier transform operator anda is a matrix operator representing the discrete and limited sampling of the field. The image, or brightness distribution, is the diagonal of (FFt). The equation can be linearly in verted only in special cases. In most cas...