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| Format: | Artículo científico |
| Language: | en |
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Universidad Nacional Autónoma de México
2003
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| Online Access: | https://www.redalyc.org/articulo.oa?id=56516204 |
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Table of Contents:
- Non-linear trends and low frequency oscillations in annual pre-cipitation over Argentina and Chile, 1931-1999 A. G. Poblete L. R. Acuña G. Casagrande Juan L. Minetti Walter M. Vargas Biología Chile Argentina Annual precipitation trends Since the 1950`s-1960`s a large portion of Argentina has experienced a long period of high precipitationwith important changes a 30-year period annual averages. Opposite conditions have taken place throughoutthe twentieth century in a large portion of Chile, with declining tendencies in annual precipitations. If suchconditions prevail, the socio-economic implications of these phenomena could eventually gain importancedue to the expansion of grain crops in the semi-arid borders of Argentina and a decline in the availability ofreservoir water used for irrigation or energy generation in the central region of Chile and western Argentina.An accurate diagnosis of these phenomena is very important for applied purposes in medium term planningthat should be undertaken by private and state-owned companies. These diagnoses are also important froma methodological point of view, in order to find out whether these changes in long-term averages are constantand represent a climatic change or if they are low frequency interdecadal fluctuations that would mean areturn to opposite conditions. We suggest that the two intense La Niña events that took place during 1988-1989 and 1995-1996 caused a decline in the precipitation trends over a large region of semi-arid Argentinaand intensified droughts in Central Chile.A regionalized local precipitation analysis of the 1931-1932/1998-1999 agricultural periods over large areaswas performed. Afterwards, long-term variations for homogeneous areas were analysed through their nonlineartrends and low frequency fluctuations in a regional scale. Seven inter-annual patterns with threedifferent types of tendencies have been found. One of them shows an increasing linear trend throughoutthe analysed period; another one shows an increasing trend, but also a decrease after the 1980s, and athird one shows a continuous decrease. Regions with continuous trends include medium latitude semi-aridregions in Argentina and Chile, where an intense human impact is observed. An 18-26-year-quasi-periodthat affects four of the selected regions and has a clearer signal in the Cuyo region has been found. Thislong period signal is in phase with the oscillations of other atmospheric variables in South America andwith precipitation in South Africa. 2003 artículo científico 0187-6236 https://www.redalyc.org/articulo.oa?id=56516204 en http://www.redalyc.org/revista.oa?id=565 Atmósfera application/pdf Universidad Nacional Autónoma de México Atmósfera (México) Num.2 Vol.16