Revista Geofísica No. 56
January - June 2002
Cyclic
Components in the Length of Solar Cycle
G. K. Rangarajan
L. M. Barreto
Received October 2, 2001; accepted December 18, 2001
The time series of the length of solar cycle covering more than 22
centuries is decomposed into three major cyclic components with associated
approximate periodicities of 80, 50 and 240 years, and the time variations
in their amplitude are indicated. It is suggested that these cyclic
components could be useful to establish better the inter-relationship
between solar activity and weather/climate. Extrapolation of the time
series by 25 years up to 2015 indicates that in the coming years, the
length of the solar cycle will tend to show marginal increase up to
2010. Length of the solar cycle derived from proxy data seems to be
consistent with that derived from annual mean sunspot numbers after
1700 AD.
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Método
empírico para el pronóstico de los destellos solares
Doval J. P.
Valiente J. F.
Recibido 18 de septiembre, 2000; aceptado 11 de junio,
2001
The aim of this paper is to offer an easy and quick method to predict
solar flares that requires only the data obtained directly from optical
observations of the sunspots, and this allows its application whatever
the circumstances.
The results, of a probabilistic nature, are based on the analysis of
524 flares 1 that occurred in 4500 daily spots observed by the Optical
Solar Service in the Institute of Geophysics and Astronomy of Cuba.
The morphological classifications of Zurich and McIntosh were used;
with a modification that was introduced in Cuba. Other variables were
also taken into consideration such as the area, the pores number and
the magnetic classification.
Among the results are the fact that 87% of flares occur on spot groups
with asymmetric main penumbra, and also the more explosive character
of the bipolar groups with intermediate or compact populations, specially
when a great magnetic unbalance is implied because the leaders or followers
are significantly bigger.
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Tides
and tidal energy in Valdes Peninsula (Argentina)
Elbio D. Palma
Received May 6, 2001; accepted December 19, 2001
The large amplitude M2 tidal wave presents a unique phase shift of
six hours at both sides of the narrow (7 km) Ameghino Isthmus in Valdes
Peninsula, on the patagonic argentinian coast. For this fact, the site
has been recognized for a long time as a potentially important tidal
power generation resource. In the first part of this paper we present
a study of the M2 natural regime employing a two-dimensional vertically
integrated FEM model. Model results are in good agreement with measured
coastal elevations and phases. Next we analyze possible effects of tidal
power plants operation on the modeled tidal flow. Tentative numerical
estimates shows a diminishing net available head for great barrages,
thus limiting the size of the proposed plants.
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Morfometría
de la cuenca del arroyo Claromecó, Provincia de Buenos Aires, Argentina
María Elizabeth Carbone
María Cintia Píccolo
Recibido 6 de marzo, 2000, aceptado 18 de febrero,
2002
The characteristics of the Claromeco basin, located in the southeast
of the Buenos Aires province, Argentina, are described. There are few
studies of the river, although it has a great significance in the agricultural
activities of the region. The study zone is characterized by farming,
agricultural and cattle raising activities. The river which flows across
a plain, results from the confluence of three courses. To analize and
study the basin, satellite and topographic charts were used. The tributaries
begins on the Pampa de Juarez plain. The river has a N-S direction.
Different coefficients were use to describe the size and form of the
basin. The basin of Claromeco creek has an area of 3,017.18 km2,
its perimeter is 285 km and its principal creek is 135 km long. Two
different types of drainage were identified: dendritic and anarchic.
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Estudio
de la componente húmeda de la corrección troposférica para las estaciones
Salta y Córdoba (Argentina)
José Fernando Lagori
Dante del valle Pastorelli
Víctor Hugo Ríos
Miguel Angel Carrillo
Recibido 3 de julio, 2000; aceptado 3 de mayo, 2002
In the last decades, the use of electromagnetic waves with frequencies
from 30 MHz to 30 GHz intensified, in particular the GPS system. For
these frequencies, the ionosphere is not affected by the energy of the
waves, but variations are observed when the propagation occurs in the
troposphere, particularly in the refraction index. The stations used
in this study were: Salta (24°48’S-65°25’W) and Córdoba (31°21’S-64°05’W).
In this paper, different variables involved in the errors, with emphasis
in the relative humidity have been considered.
Our proposed model compared with that of Saastamoinen (1973) for the
humid component of the tropospheric correction, possesses smaller absolute
values. The seasonal variation that the results present when applying
both models with a minimum in the winter months is coherent, since in
these regions (Salta and Córdoba) they possess higher water vapor in
the summer months than in winter. The latitudinal variation of the humid
component is also accountable since Salta possesses a latitude of 24°
48’S while Córdoba with a latitude of 31° 21’S is a typical middle station
latitude where the climatic influence is less affected.
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