http://sedici.unlp.edu.ar:80/handle/10915/134464 2026-06-18T08:03:26Z 2026-06-18T08:03:26Z Asociación Argentina de Geofísicos y Geodestas http://sedici.unlp.edu.ar:80/handle/10915/135376 2022-08-26T17:54:36Z 1994-01-01T00:00:00Z

Edicion de revista Geoacta; vol. 21 Special contributions from 7th IAGA Assembly in Buenos Aires: - On the electric current systems in the Earth's environment. Some historical aspects Part I. : external part / ionosphere / quiet variation | Christine Amory-Mazaudier - Emanuel Liáis: A scientist of two Continents | Luiz Muniz Barreto - Historical review of Argentine activities in geomagnetism and aeronomy | Otto Schneider - An overview on the study of the equatorial electrojet | C. J. Zamlutti - Dynamics of the equatorial ionosphere-thermosphere system as investigated through night airglow techniques | J. H. A. Sobral - IEEY Project: The American sector | H. A. J. Sobral - A Rocket-Borne Langmuir probe response to continuous and pulsed sweep modes | P. Muralikrishna, M. A. Abdu, I. S. Batista y M. G. S. Aquino - A fast cam driven absorption cell based rocket-borne nitric oxide detector | P. Muralikrishna y Ednilson Bassani General contributions - Solar variability effects on climate | Juan G. Roederer - Sound range-dependent propagation: An experiment on down-slope propagation over the Argentinian continental slope | Marta I. Etcheverry De Milou y Silvia Blanc - The auroral break-up as related to the interplanetary parameters and the geomagnetic activity | V. M. Silbergleit - Results from three GPS campaigns in Tierra del Fuego | R. Perdomo, C. Brunini, D. Canosa, D. Del Cogliano, J. L. Hormaechea, J. C. Usandivaras, M. Catalan, R. Soto y M. Berrocoso - Persistence in surface overflow of Andean rivers | Juan L. Minetti - Climatología de la precipitación en la Region Pampeana: I. Variabilidad decádica, tendencias y eventos extremos | Carlos M. Krepper y Beatriz Scian Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z Special contributions from 7th IAGA Assembly in Buenos Aires: - On the electric current systems in the Earth's environment. Some historical aspects Part I. : external part / ionosphere / quiet variation | Christine Amory-Mazaudier - Emanuel Liáis: A scientist of two Continents | Luiz Muniz Barreto - Historical review of Argentine activities in geomagnetism and aeronomy | Otto Schneider - An overview on the study of the equatorial electrojet | C. J. Zamlutti - Dynamics of the equatorial ionosphere-thermosphere system as investigated through night airglow techniques | J. H. A. Sobral - IEEY Project: The American sector | H. A. J. Sobral - A Rocket-Borne Langmuir probe response to continuous and pulsed sweep modes | P. Muralikrishna, M. A. Abdu, I. S. Batista y M. G. S. Aquino - A fast cam driven absorption cell based rocket-borne nitric oxide detector | P. Muralikrishna y Ednilson Bassani General contributions - Solar variability effects on climate | Juan G. Roederer - Sound range-dependent propagation: An experiment on down-slope propagation over the Argentinian continental slope | Marta I. Etcheverry De Milou y Silvia Blanc - The auroral break-up as related to the interplanetary parameters and the geomagnetic activity | V. M. Silbergleit - Results from three GPS campaigns in Tierra del Fuego | R. Perdomo, C. Brunini, D. Canosa, D. Del Cogliano, J. L. Hormaechea, J. C. Usandivaras, M. Catalan, R. Soto y M. Berrocoso - Persistence in surface overflow of Andean rivers | Juan L. Minetti - Climatología de la precipitación en la Region Pampeana: I. Variabilidad decádica, tendencias y eventos extremos | Carlos M. Krepper y Beatriz Scian Krepper, Carlos M. Scian, Beatriz http://sedici.unlp.edu.ar:80/handle/10915/135373 2022-05-02T20:02:16Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 Se analizan las series mensuales de precipitación de localidades ubicadas en la región pampeana con información que supera los 88 años de registros, detectándose en los promedios móviles de 11 años de totales anuales, una zona de fuertes tendencias positivas, especialmente a partir de la década del 50 y en el trimestre estival. Se definen estadísticamente los extremos de precipitación anual en base a una distribución Weibull triparamétrica y se determinan las zonas de probabilidad de ocurrencia de déficit y excesos. Se caracterizan los años extremos como aquellos en que más del 50% del área total soportó déficit o exceso de precipitación. Se resume el comportamiento de los años climáticos en una serie temporal de porcentajes de áreas bajo condiciones extremas, destacándose un año de déficit para la región, 1910- 1911, y cinco años con excesos de precipitación, 1914-15, 1918-19, 1946-47, 1968-69 y 1972-73.; Monthly precipitation series from the Pampa region with record lenghts greater than 88 years are analyzed using moving averages over eleven years. A zone of strong positive trends, particularly started in the fifties during the summer season is detected. Extremes of yearly precipitation are statistical defined by means of a three parametric Weibull distribution. Areas of probabilities of deficit and excess of annual rainfall are determined. An extreme year is defined as the year in which more than 50% of the total area suffered precipitation deficit or excess. A summary of the behavior of the climate years is presented as a temporal series of the area percentage of the region under extreme conditions. It is observed that years 1910- 1911 are extreme of deficit while 1914-15, 1918-19, 1946-47, 1968-69 and 1972-73 are extreme years of excess of rainfall in the region. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z Se analizan las series mensuales de precipitación de localidades ubicadas en la región pampeana con información que supera los 88 años de registros, detectándose en los promedios móviles de 11 años de totales anuales, una zona de fuertes tendencias positivas, especialmente a partir de la década del 50 y en el trimestre estival. Se definen estadísticamente los extremos de precipitación anual en base a una distribución Weibull triparamétrica y se determinan las zonas de probabilidad de ocurrencia de déficit y excesos. Se caracterizan los años extremos como aquellos en que más del 50% del área total soportó déficit o exceso de precipitación. Se resume el comportamiento de los años climáticos en una serie temporal de porcentajes de áreas bajo condiciones extremas, destacándose un año de déficit para la región, 1910- 1911, y cinco años con excesos de precipitación, 1914-15, 1918-19, 1946-47, 1968-69 y 1972-73. Monthly precipitation series from the Pampa region with record lenghts greater than 88 years are analyzed using moving averages over eleven years. A zone of strong positive trends, particularly started in the fifties during the summer season is detected. Extremes of yearly precipitation are statistical defined by means of a three parametric Weibull distribution. Areas of probabilities of deficit and excess of annual rainfall are determined. An extreme year is defined as the year in which more than 50% of the total area suffered precipitation deficit or excess. A summary of the behavior of the climate years is presented as a temporal series of the area percentage of the region under extreme conditions. It is observed that years 1910- 1911 are extreme of deficit while 1914-15, 1918-19, 1946-47, 1968-69 and 1972-73 are extreme years of excess of rainfall in the region. Minetti, Juan L. Carletto, Martha C. http://sedici.unlp.edu.ar:80/handle/10915/135371 2022-05-02T20:02:20Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 The temporal structure of both deficit (negative) and excess (positive) periods in surface overflow of Andean rivers were analyzed by studying the runs. In Southern areas (in the province of Neuquén and the Southern part of the province of Mendoza), positive and negative groups of anomalies have been found to diminish geometrically over the years. In the Northern areas (in the province of San Juan and Northern part of the province of Mendoza) persistence occurs in negative runs only. This behavior is produced by the influence of the basins located in an arid zone, because of the heterogeneity in the structure of the precipitation in this region.; En este trabajo se analiza el comportamiento de la persistencia en el escurrimiento superficial de los ríos andinos, usando el método de rachas de eventos con anomalías positivas o negativas. Se ha encontrado que las rachas positivas o negativas tienen en la zona más austral (provincia de Neuquén y sur de Mendoza) un decaimiento de tipo geométrico con los años; en cambio, hacia la zona más septentrional (provincia de San Juan y norte de Mendoza) aparece la persistencia solamente en las rachas negativas o de sequías. Este comportamiento no se encuentra en la estructura de la precipitación que cae en la cuenca, por lo tanto, se infiere que el mismo sería debido a la regulación que ejercen las cuencas del norte, inmersas en una región de clima árido. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z The temporal structure of both deficit (negative) and excess (positive) periods in surface overflow of Andean rivers were analyzed by studying the runs. In Southern areas (in the province of Neuquén and the Southern part of the province of Mendoza), positive and negative groups of anomalies have been found to diminish geometrically over the years. In the Northern areas (in the province of San Juan and Northern part of the province of Mendoza) persistence occurs in negative runs only. This behavior is produced by the influence of the basins located in an arid zone, because of the heterogeneity in the structure of the precipitation in this region. En este trabajo se analiza el comportamiento de la persistencia en el escurrimiento superficial de los ríos andinos, usando el método de rachas de eventos con anomalías positivas o negativas. Se ha encontrado que las rachas positivas o negativas tienen en la zona más austral (provincia de Neuquén y sur de Mendoza) un decaimiento de tipo geométrico con los años; en cambio, hacia la zona más septentrional (provincia de San Juan y norte de Mendoza) aparece la persistencia solamente en las rachas negativas o de sequías. Este comportamiento no se encuentra en la estructura de la precipitación que cae en la cuenca, por lo tanto, se infiere que el mismo sería debido a la regulación que ejercen las cuencas del norte, inmersas en una región de clima árido. Perdomo, Raúl Aníbal Brunini, Claudio Antonio Canosa, D. Del Cogliano, Daniel Héctor Hormaechea, José Luis Usandivaras, Juan Carlos Catalan, M. Soto, R. Berrocoso, M. http://sedici.unlp.edu.ar:80/handle/10915/134989 2022-04-25T20:02:31Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 During January and February 1990, 1991 and 1992 an important collaboration took place between the Rio Grande Astronomical Station (Estación Astronómica de Río Grande - EARG) and the Royal Institute and Observatory of the Spanish Navy (Real Instituto y Observatorio de la Armada de España - RIOA). Using RIOA GPS receivers a single base between one point in EARG (Rio Grande) and another point located at the Centro Austral de Investigaciones Científicas (CADIC, Ushuaia) was measured several times. Measured distances repetitivity is about 0.7 ppm (9 cm) and in components, 1 ppm. These results will permit the planning of an appropriate network to be measured with GPS which will contribute to the determination of crustal movements in the Tierra del Fuego region.; En los meses de enero y febrero de los años 1990, 1991 y 1992 se realizó un trabajo de colaboración entre la Estación Astronómica Río Grande (EARG) y el Real Instituto y Observatorio de la Armada de España (RIOA). Con posicionadores GPS pertenecientes al grupo español se midió reiteradamente una misma base entre un punto situado en la EARG (Río Grande) y otro situado en el Centro Austral de Investigaciones Científicas (CADIC, Ushuaia). La repetitividad de las distancias medidas es del orden de 0.7 ppm (unos 9 cm) y en componentes, de 1 ppm. Esto permitirá planificar una red apropiada en la región fueguina para la determinación de movimientos tectónicos utilizando GPS. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z During January and February 1990, 1991 and 1992 an important collaboration took place between the Rio Grande Astronomical Station (Estación Astronómica de Río Grande - EARG) and the Royal Institute and Observatory of the Spanish Navy (Real Instituto y Observatorio de la Armada de España - RIOA). Using RIOA GPS receivers a single base between one point in EARG (Rio Grande) and another point located at the Centro Austral de Investigaciones Científicas (CADIC, Ushuaia) was measured several times. Measured distances repetitivity is about 0.7 ppm (9 cm) and in components, 1 ppm. These results will permit the planning of an appropriate network to be measured with GPS which will contribute to the determination of crustal movements in the Tierra del Fuego region. En los meses de enero y febrero de los años 1990, 1991 y 1992 se realizó un trabajo de colaboración entre la Estación Astronómica Río Grande (EARG) y el Real Instituto y Observatorio de la Armada de España (RIOA). Con posicionadores GPS pertenecientes al grupo español se midió reiteradamente una misma base entre un punto situado en la EARG (Río Grande) y otro situado en el Centro Austral de Investigaciones Científicas (CADIC, Ushuaia). La repetitividad de las distancias medidas es del orden de 0.7 ppm (unos 9 cm) y en componentes, de 1 ppm. Esto permitirá planificar una red apropiada en la región fueguina para la determinación de movimientos tectónicos utilizando GPS. Silbergleit, V. M. http://sedici.unlp.edu.ar:80/handle/10915/134979 2022-04-25T20:02:36Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 In the present study, we used as a significant indicator of the auroral break-up the "sudden equatorward shift" in arcs or displays. For the dark months of May and June of 1971, auroral observations at Base General Belgrano (78,0° S; 38,8° W) were used. Four-hourly sequences centered at the break-up (t=0) were studied for the following quantities: a) The magnitude of the interplanetary magnetic field (B), b) The southward component of the interplanetary magnetic field (Bz), c) The solar wind speed (V), d) The solar wind electric field (the westward component: E ), e) The auroral electrojet magnetic activity indices (AE, AL, AU). On the basis of the seven substorms studied, one may deduce that an appreciable increase of geomagnetic activity occured about 40 minutes after the energy arrival at the magnetosphere, but it is not enough strong to take place the break-up, it will happen after another period of 35 minutes. This result confirms that a substorm only occurs after a build-up process. The present paper also confirms the possibility of using the auroral zone geomagnetic activity for estimating the solar wind velocity.; En el presente trabajo usamos como indicador de la ruptura de aurora al "sudden equatorward shift" en arcos o displays. Para los meses oscuros de mayo y junio de 1971, se usaron observaciones aurorales en la Base General Belgrano (78,0° S; 38,8° W) Se estudiaron las secuencias de cuatro horas centradas en la ruptura (t=0) para las siguientes variables: a). La amplitud del campo magnético interplanetario (B), b) La componente sur del campo magnético interplanetario (Bz), c) La velocidad del viento solar (V), d) El campo eléctrico del viento solar (la componente oeste: E), c) Los índices de actividad magnética del electrochorro auroral (AE, AL, AU) Sobre la base de las siete subtormentas estudiadas uno puede deducir que ocurrió un incremento apreciable de la actividad geomagnética aproximadamente 40 minutos después de la llegada de la energía a la magnetósfera, pero no han sido lo suficientemente fuertes para tener lugar durante la ruptura, eso sucederá después de otro período de 35 minutos. Este resultado confirma que una sub-tormenta solo ocurre después de un proceso tipo "build-up". El presente trabajo también confirma la posibilidad de usar la actividad geomagnética de la zona auroral para estimar la velocidad del viento solar. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z In the present study, we used as a significant indicator of the auroral break-up the "sudden equatorward shift" in arcs or displays. For the dark months of May and June of 1971, auroral observations at Base General Belgrano (78,0° S; 38,8° W) were used. Four-hourly sequences centered at the break-up (t=0) were studied for the following quantities: a) The magnitude of the interplanetary magnetic field (B), b) The southward component of the interplanetary magnetic field (Bz), c) The solar wind speed (V), d) The solar wind electric field (the westward component: E ), e) The auroral electrojet magnetic activity indices (AE, AL, AU). On the basis of the seven substorms studied, one may deduce that an appreciable increase of geomagnetic activity occured about 40 minutes after the energy arrival at the magnetosphere, but it is not enough strong to take place the break-up, it will happen after another period of 35 minutes. This result confirms that a substorm only occurs after a build-up process. The present paper also confirms the possibility of using the auroral zone geomagnetic activity for estimating the solar wind velocity. En el presente trabajo usamos como indicador de la ruptura de aurora al "sudden equatorward shift" en arcos o displays. Para los meses oscuros de mayo y junio de 1971, se usaron observaciones aurorales en la Base General Belgrano (78,0° S; 38,8° W) Se estudiaron las secuencias de cuatro horas centradas en la ruptura (t=0) para las siguientes variables: a). La amplitud del campo magnético interplanetario (B), b) La componente sur del campo magnético interplanetario (Bz), c) La velocidad del viento solar (V), d) El campo eléctrico del viento solar (la componente oeste: E), c) Los índices de actividad magnética del electrochorro auroral (AE, AL, AU) Sobre la base de las siete subtormentas estudiadas uno puede deducir que ocurrió un incremento apreciable de la actividad geomagnética aproximadamente 40 minutos después de la llegada de la energía a la magnetósfera, pero no han sido lo suficientemente fuertes para tener lugar durante la ruptura, eso sucederá después de otro período de 35 minutos. Este resultado confirma que una sub-tormenta solo ocurre después de un proceso tipo "build-up". El presente trabajo también confirma la posibilidad de usar la actividad geomagnética de la zona auroral para estimar la velocidad del viento solar. Etcheverry de Milou, Marta I. Blanc, Silvia http://sedici.unlp.edu.ar:80/handle/10915/134974 2022-04-25T20:02:40Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 A range dependent acoustic down-slope propagation loss (TL) experiment was conducted in 1989 over the Argentinian Continental Slope, along a 50 km track, using two TRACKER aircrafts from the AntiSubmarine Warfare (ASW) squadron. One aircraft flew a prearranged track dropping 1.8 lb of TROTYL, explosive charges, while the second aircraft remained in the area of a deployed calibrated passive sonobuoy, used as sonar receiver. Recorded broadband signals were analyzed with EFT techniques in selected 1/3 octave bands between 100 Ilz and 400 Hz. A code based on the parabolic equation method (PE) was used to model the down-slope propagation losses. A reasonable agreement was obtained when theoretical predictions were compared with experimental evidence. This agreement improves at low frequencies. Moreover, at high frequencies the greater the range the better fit is observed.; En 1989 se ha realizado una experiencia sobre el Talud Continental Argentino para medir pérdidas por propagación acústica (TL) en un medio cuyas propiedades físicas dependen de la distancia, en una extensión de 50 km, usando dos aviones TRACKER de la Escuadrilla Naval Antisubmarina. Uno de los aviones arrojaba cargas explosivas de 1.8 libras de TROTYL, siguiendo un rumbo prefijado, mientras el otro permanecía en el área de sembrado de la sonoboya. actuando como sistema receptor. Las señales en banda ancha fueron analizadas con técnicas de FFT, en bandas de 1/3 de octava entre 100 Hz y 400 Hz. Para modelar las pérdidas por propagación se ha utilizado un código basado en el método de la ecuación parabólica. Se obtuvo un ajuste satisfactorio al comparar las predicciones teóricas con la evidencia experimental. Este ajuste es mejor a bajas frecuencias. A altas frecuencias, se observa un acuerdo mayor para grandes distancias. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z A range dependent acoustic down-slope propagation loss (TL) experiment was conducted in 1989 over the Argentinian Continental Slope, along a 50 km track, using two TRACKER aircrafts from the AntiSubmarine Warfare (ASW) squadron. One aircraft flew a prearranged track dropping 1.8 lb of TROTYL, explosive charges, while the second aircraft remained in the area of a deployed calibrated passive sonobuoy, used as sonar receiver. Recorded broadband signals were analyzed with EFT techniques in selected 1/3 octave bands between 100 Ilz and 400 Hz. A code based on the parabolic equation method (PE) was used to model the down-slope propagation losses. A reasonable agreement was obtained when theoretical predictions were compared with experimental evidence. This agreement improves at low frequencies. Moreover, at high frequencies the greater the range the better fit is observed. En 1989 se ha realizado una experiencia sobre el Talud Continental Argentino para medir pérdidas por propagación acústica (TL) en un medio cuyas propiedades físicas dependen de la distancia, en una extensión de 50 km, usando dos aviones TRACKER de la Escuadrilla Naval Antisubmarina. Uno de los aviones arrojaba cargas explosivas de 1.8 libras de TROTYL, siguiendo un rumbo prefijado, mientras el otro permanecía en el área de sembrado de la sonoboya. actuando como sistema receptor. Las señales en banda ancha fueron analizadas con técnicas de FFT, en bandas de 1/3 de octava entre 100 Hz y 400 Hz. Para modelar las pérdidas por propagación se ha utilizado un código basado en el método de la ecuación parabólica. Se obtuvo un ajuste satisfactorio al comparar las predicciones teóricas con la evidencia experimental. Este ajuste es mejor a bajas frecuencias. A altas frecuencias, se observa un acuerdo mayor para grandes distancias. Roederer, Juan G. http://sedici.unlp.edu.ar:80/handle/10915/134951 2022-04-25T20:02:43Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 One of the key tasks in climate research at the present time is to separate anthropogenic effects from natural change. Solar variability is one possible cause of natural change in addition to other external phenomena such as volcanic eruptions and, on a long-term scale, orbital changes and celestial body impacts. The topic of "sun-weather relationships" has followed a long and tortuous history of scientific speculations and controversy since the continuous observation of sunspots began in the 17th century. It was not until recently that more systematic studies with long-term data bases of meteorological, climatological and solar parameters led to an increasing, statistically robust, body of evidence for a causal connection between some manifestations of solar variability and changes in the troposphere and the climate system. While of planetary' scale, the strength and sign of pertinent correlations have distinct geographic, seasonal and other temporal characteristics. Most likely, several trigger mechanisms are at work simultaneously, but their relative importance may depend on the time-scale envisaged and on competing processes such as volcanic eruptions. In this paper we will summarize the most frequently formulated criticisms, review the most recent results on relevant solar variability effects at the 11-year, secular, and short-term time scales, and discuss proposed mechanisms such as enhanced Hadley circulation, charged particle ionization effects on clear-air conductivity, and electric field effects on the microphysics of cloud formation.; En la actualidad, una tarea clave de la investigación climática es la de separar los efectos antropogénicos de los cambios naturales. La variabilidad del sol es una posible causa del cambio natural junto con otros posibles fenómenos de orden externo como por ejemplo las erupciones volcánicas y en escalas de tiempo mas largas cambios orbitales y el impacto de cuerpos celestes. El tema "relación sol-clima" ha seguido una larga y tortuosa historia de especulación científica y controversias desde que en el siglo 17 se empezaron a observar en forma continua las manchas solares. Recientemente, sobre la base de estudios más sistemáticos y bases de datos de períodos largos de parámetros meteorológicos, climatológicos y solares se dispone de un cuerpo de evidencias amplio y estadísticamente robusto de la conexión causal entre algunas manifestaciones de la variabilidad solar y cambios en la troposfera y el clima. En la escala planetaria, la intensidad y signo de las correlaciones poseen distintas características geográficas, estacionales y otras temporales. Muy probablemente, distintos mecanismos de "trigger" operan simultáneamente, pero su importancia relativa puede depender de la escala de tiempo considerada y de procesos competitivos como las erupciones volcánicas. En este trabajo, haremos un resumen de las críticas mas frecuentes, veremos los resultados recientes más relevantes de los efectos de la variabilidad solar de 11 años, secular, y escala de tiempo corta; y discutiremos mecanismos propuestos como la circulación de Hadley ampliada, efectos ionizantes de partículas cargadas sobre la conductividad del aire limpio, y efectos del campo eléctrico en la microfísica formación de nubes. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z One of the key tasks in climate research at the present time is to separate anthropogenic effects from natural change. Solar variability is one possible cause of natural change in addition to other external phenomena such as volcanic eruptions and, on a long-term scale, orbital changes and celestial body impacts. The topic of "sun-weather relationships" has followed a long and tortuous history of scientific speculations and controversy since the continuous observation of sunspots began in the 17th century. It was not until recently that more systematic studies with long-term data bases of meteorological, climatological and solar parameters led to an increasing, statistically robust, body of evidence for a causal connection between some manifestations of solar variability and changes in the troposphere and the climate system. While of planetary' scale, the strength and sign of pertinent correlations have distinct geographic, seasonal and other temporal characteristics. Most likely, several trigger mechanisms are at work simultaneously, but their relative importance may depend on the time-scale envisaged and on competing processes such as volcanic eruptions. In this paper we will summarize the most frequently formulated criticisms, review the most recent results on relevant solar variability effects at the 11-year, secular, and short-term time scales, and discuss proposed mechanisms such as enhanced Hadley circulation, charged particle ionization effects on clear-air conductivity, and electric field effects on the microphysics of cloud formation. En la actualidad, una tarea clave de la investigación climática es la de separar los efectos antropogénicos de los cambios naturales. La variabilidad del sol es una posible causa del cambio natural junto con otros posibles fenómenos de orden externo como por ejemplo las erupciones volcánicas y en escalas de tiempo mas largas cambios orbitales y el impacto de cuerpos celestes. El tema "relación sol-clima" ha seguido una larga y tortuosa historia de especulación científica y controversias desde que en el siglo 17 se empezaron a observar en forma continua las manchas solares. Recientemente, sobre la base de estudios más sistemáticos y bases de datos de períodos largos de parámetros meteorológicos, climatológicos y solares se dispone de un cuerpo de evidencias amplio y estadísticamente robusto de la conexión causal entre algunas manifestaciones de la variabilidad solar y cambios en la troposfera y el clima. En la escala planetaria, la intensidad y signo de las correlaciones poseen distintas características geográficas, estacionales y otras temporales. Muy probablemente, distintos mecanismos de "trigger" operan simultáneamente, pero su importancia relativa puede depender de la escala de tiempo considerada y de procesos competitivos como las erupciones volcánicas. En este trabajo, haremos un resumen de las críticas mas frecuentes, veremos los resultados recientes más relevantes de los efectos de la variabilidad solar de 11 años, secular, y escala de tiempo corta; y discutiremos mecanismos propuestos como la circulación de Hadley ampliada, efectos ionizantes de partículas cargadas sobre la conductividad del aire limpio, y efectos del campo eléctrico en la microfísica formación de nubes. Muralikrishna, P. Bassani, Ednilson http://sedici.unlp.edu.ar:80/handle/10915/134945 2022-04-25T20:02:47Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 A nitric oxide(NO) detector, making use of a newly developed fast cam-driven absorption cell system is developed for launch on board a Brazilian SONDA III rocket, to measure the height profile of the NO gamma band dayglow emission intensity and thereby to estimate the height profile of the number density of atmospheric NO in the equatorial region. Two absorption cells, one of them containing the gas NO and the other nitrogen are brought in front of the photocathode of a photomultiplier (PM) tube alternately using a cam system. Each cell remains in front of the PM tube for an interval of time fixed by the cam shape. The cam is designed to optimize the time needed for positioning the cells one after the other and also to simplify the operation of the step motor responsible for the movement of the absorption cells. The advantages of this new system over the conventional wheel mounting are also presented. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z A nitric oxide(NO) detector, making use of a newly developed fast cam-driven absorption cell system is developed for launch on board a Brazilian SONDA III rocket, to measure the height profile of the NO gamma band dayglow emission intensity and thereby to estimate the height profile of the number density of atmospheric NO in the equatorial region. Two absorption cells, one of them containing the gas NO and the other nitrogen are brought in front of the photocathode of a photomultiplier (PM) tube alternately using a cam system. Each cell remains in front of the PM tube for an interval of time fixed by the cam shape. The cam is designed to optimize the time needed for positioning the cells one after the other and also to simplify the operation of the step motor responsible for the movement of the absorption cells. The advantages of this new system over the conventional wheel mounting are also presented. Muralikrishna, P. Abdu, M. A. Batista, I. S. Aquino, M. G. S. http://sedici.unlp.edu.ar:80/handle/10915/134943 2022-04-25T20:02:50Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 Nightime ionospheric electron density and temperature are measured using a rocket-borne Langmuir probe (LP) launched on board a SONDA III rocket from the Brazilian equatorial rocket launching station in Alcantara-MA, at 23:51 hrs (LT) on May 31, 1992. A sweep voltage varying between -IV and +2.5V is applied to the spherical LP sensor alternately in continuous and pulsed modes. In the continuous mode the effect of contamination of the sensor surface on the current collected by the sensor is clearly seen in the current-voltage characteristics and thereby on the electron temperature estimated, while this effect is practically absent in the pulsed mode operation. An electron temperature profile estimated from the LP data is compared with the IRI90 model profile. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z Nightime ionospheric electron density and temperature are measured using a rocket-borne Langmuir probe (LP) launched on board a SONDA III rocket from the Brazilian equatorial rocket launching station in Alcantara-MA, at 23:51 hrs (LT) on May 31, 1992. A sweep voltage varying between -IV and +2.5V is applied to the spherical LP sensor alternately in continuous and pulsed modes. In the continuous mode the effect of contamination of the sensor surface on the current collected by the sensor is clearly seen in the current-voltage characteristics and thereby on the electron temperature estimated, while this effect is practically absent in the pulsed mode operation. An electron temperature profile estimated from the LP data is compared with the IRI90 model profile. Sobral, H. A. J. http://sedici.unlp.edu.ar:80/handle/10915/134922 2022-04-25T20:02:54Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 A description of the activities and efforts related to the International Electrojet Year (IEEY: period: September 1st, 1991 to March 31, 1993) in the American Sector (190°E-330°E) is given with a focus on the participation ofthe Latin American stations that are located in the EE belt. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z A description of the activities and efforts related to the International Electrojet Year (IEEY: period: September 1st, 1991 to March 31, 1993) in the American Sector (190°E-330°E) is given with a focus on the participation ofthe Latin American stations that are located in the EE belt. Sobral, J. H. A. http://sedici.unlp.edu.ar:80/handle/10915/134919 2022-04-25T20:02:57Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 The dynamics of the nocturnal equatorial F-region has been investigated to a substantial extent in the last few decades by means of airglow diagnostic tools such as photometers, optical imagers and Fabry-Perot interferometric systems. This paper concerns a concise review on those airglow studies. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z The dynamics of the nocturnal equatorial F-region has been investigated to a substantial extent in the last few decades by means of airglow diagnostic tools such as photometers, optical imagers and Fabry-Perot interferometric systems. This paper concerns a concise review on those airglow studies. Zamlutti, C. J. http://sedici.unlp.edu.ar:80/handle/10915/134916 2022-04-25T20:03:00Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 In this work, a balance on the present status of the study of the equatorial electrojet is presented. Particular attention is paid to a better understanding of what one can expect from the worldwide cooperation for the International Equatorial Electrojet Year, (IEEY) regarding the theoretical and experimental aspects. It will be seen that our limited knowledge of this phenomenon is due to the impossibility of the existing observatories to provide data with satisfactory time and height resolutions for all parameters required to test the theoretical models. We also investigate the possibility that equatorial phenomena related with the electrojet may contribute to evaluate some of these parameters. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z In this work, a balance on the present status of the study of the equatorial electrojet is presented. Particular attention is paid to a better understanding of what one can expect from the worldwide cooperation for the International Equatorial Electrojet Year, (IEEY) regarding the theoretical and experimental aspects. It will be seen that our limited knowledge of this phenomenon is due to the impossibility of the existing observatories to provide data with satisfactory time and height resolutions for all parameters required to test the theoretical models. We also investigate the possibility that equatorial phenomena related with the electrojet may contribute to evaluate some of these parameters. Schneider, Otto http://sedici.unlp.edu.ar:80/handle/10915/134909 2022-11-18T18:43:24Z 1994-01-01T00:00:00Z

Articulo Geoacta; vol. 21 Research in the disciplines embraced under the general concept of Geomagnetism and Aeronomy belongs in Argentina, with very few exceptions, to the XXth Century. Changes in the administrative and academic organization of such work have frequently occurred all over the world, partly as a consequence of the explosive development of techniques and theories, and partly in the framework of the ever changing historical scenarios within the participating nations. This also applies to the case of Argentina, still a young country. With the exception of a very few outstanding leaders, organizers and teachers we must, alas, refrain from quoting the numerous individual scientists and technicians who have contributed to this development; it is impossible to do justice to all of them, but many names will appear in the references. Suffice it in the present context to remark that they were recruited, in addition to geophysicists proper, among physicists, geologists, geodesists, mathematicians, astronomers, engineers, and members of the armed forces. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z Research in the disciplines embraced under the general concept of Geomagnetism and Aeronomy belongs in Argentina, with very few exceptions, to the XXth Century. Changes in the administrative and academic organization of such work have frequently occurred all over the world, partly as a consequence of the explosive development of techniques and theories, and partly in the framework of the ever changing historical scenarios within the participating nations. This also applies to the case of Argentina, still a young country. With the exception of a very few outstanding leaders, organizers and teachers we must, alas, refrain from quoting the numerous individual scientists and technicians who have contributed to this development; it is impossible to do justice to all of them, but many names will appear in the references. Suffice it in the present context to remark that they were recruited, in addition to geophysicists proper, among physicists, geologists, geodesists, mathematicians, astronomers, engineers, and members of the armed forces. Muniz Barreto, Luiz http://sedici.unlp.edu.ar:80/handle/10915/134519 2022-04-18T20:02:44Z 1994-01-01T00:00:00Z

Articulo 7th IAGA Assembly in Buenos Aires; Geoacta; vol. 21 In the middle of the 18th Century, the necessity to explore a new land induced the Portuguese Crown to send to the Colony many geographers and cartographers, such as Parigai, Cieira, Pithon, Basco, Alpoin (Carvalho, 1985). It was a crude beginning of Astronomy and Geophysics in Brazil. However, the efforts to establish a regular scientific practice with those specialists were insufficient to be considered as the birth of scientific research. It was necessary to create a true national scientific institution and the conditions for the entry on the scene of the main actor in our story: Emmanuel Liais. These notes intend to analyze his importance in the History of Geomagnetism. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z In the middle of the 18th Century, the necessity to explore a new land induced the Portuguese Crown to send to the Colony many geographers and cartographers, such as Parigai, Cieira, Pithon, Basco, Alpoin (Carvalho, 1985). It was a crude beginning of Astronomy and Geophysics in Brazil. However, the efforts to establish a regular scientific practice with those specialists were insufficient to be considered as the birth of scientific research. It was necessary to create a true national scientific institution and the conditions for the entry on the scene of the main actor in our story: Emmanuel Liais. These notes intend to analyze his importance in the History of Geomagnetism. Amory-Mazaudier, Christine http://sedici.unlp.edu.ar:80/handle/10915/134490 2022-04-19T04:01:54Z 1994-01-01T00:00:00Z

Articulo 7th IAGA Assembly in Buenos Aires; Geoacta; vol. 21 In this paper we present some historical aspects of ionospheric electric currents. Our attention is focused on the regular part of these currents at the origin of the Earth's magnetic field daily variation Sr. The steps described in this paper correspond to advances in fundamental physics, as well as in technology, data interpretation or other factors. The paper covers the period from 1870 to date. Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).

1994-01-01T00:00:00Z In this paper we present some historical aspects of ionospheric electric currents. Our attention is focused on the regular part of these currents at the origin of the Earth's magnetic field daily variation Sr. The steps described in this paper correspond to advances in fundamental physics, as well as in technology, data interpretation or other factors. The paper covers the period from 1870 to date.