Descripción: The objective of the present paper is to analyse the possible impact of ENSO events on the spatial and the temporal distribution of frost occurrences, within the central region of Argentina. Therefore, the minimum temperature series have been studied for 41 meteorological stations within the Pampa Humeda region and, for a period of 30 years from 1961 to 1990, exploring possible relationships with El Nino (EN)/La Nina (LN) events and the changes in the Southern Oscillation. It can be concluded that part of the frost frequency variability within this region is explained by the ENSO cycle. Results indicate that, for at least 1 of the 2 years in which the EN event takes place, the mean number of frost occurrences drops below the climatological value. The low phase of the Southern Oscillation Index (SOI) also coincides with those years for which the number of frost events remained below the total annual mean in all cases, with the year 1965 as an exception. Conversely, during the high phase of the SOI, this number was above the total annual mean for four of the six classified cases. In the particular case of seasonal frost occurrence, it is related to the warm event development state, exhibiting a greater impact during the autumn and winter months, for which the cold event also seems to have influence. Copyright (C) 2000 Royal Meteorological Society.

Descripción: The coast of Lobería and Necochea is characterized by cliffsand narrow beaches. The inlet of the Quequén Grande river used to alter the coastline. The construction of jetties related to the Quequén Harbour induced huge accumulations of sand towards Necochea, and a critic erosive process of cliff and beach to the east. Beach width reduces from 300 m at the west to 40-60 m to the east. Considering regional sand scarcity, the eastern beaches are characterized by more sand variability. Greater variations in the sand balance were assigned to human activity. Waves coming from the E, SE and S deliver more energy along this eastern sector. On the other hand, submerged zones of these beaches have less availability of sand. Greater availability of fine sand was recognized towards Necochea. The Quequén Grande river has much effect on the estuarine dynamics during ENSO-triggered floods, although sedimentation is dominated by silt supply.

Descripción: The response of altered sex ratio in southern elephant seals due to environmental stress was analysed. Data were collected at King George Island from 1980 to 1994. Significant retreats in the ice cover during El Niño events strongly suggest environmental stress during this period along the Bellingshausen Sea, a zone where female elephant seals from King George Island feed during their pregnancy. Randomly chosen weaning elephant seal pups (n = 1178) were sexed at Stranger Point (King George Island, 62° 14' S, 58° 30' W) over 5 km of beach from 1985 to 1994. Adult sex ratio was also determined annually from 1980 to 1994 as the ratio between maximum number of bulls and females on land. The theoretical pup sex ratio was assumed as 1:1 according to background information. Adult sex ratio was calculated as 1:6. To define the occurrence of El Niño Southern Oscillation (ENSO) during the study period, a sea surface temperature (SST) index called 'Niño 3.4' for the region 5°N to 5° S, 120° E to 170° W was considered. Monthly SST anomalies were obtained from the Climate Prediction Center (CPC, NOAA). To provide an annual index of anomaly strength (IAS), the monthly adjusted oscillation index climatology (AOIC) was averaged. Accumulated values during the whole study period showed that during El Niño years (1987, 1991, 1992) the proportion of pups was significantly biased in favour of females (p < 0.01). During normal years (1986, 1990, 1993, 1994) and La Niña years (1985, 1988, 1989), accumulative values showed a greater proportion of male pups to females (p < 0.05), Using the 1:1 hypothesis, we found during El Niño years a 9% reduction in the male segment, whereas in non-El Niño years a recovery of 7 % was observed (3 % during normal years and 4 % during La Niña years. To see the influence of accumulative values of pup sex ratio in adult sex ratio, a theoretical adult proportion was calculated as 1:6. To test this hypothesis, information on adult sex ratio taken from King George Island between 1980 and 1994 (n = 14 yr) was analysed. The average adult sex ratio for King George Island was 1:7. This value seems to confirm the hypothesis that this population has had a balanced production of male and female pups in the long term. Comparisons with Pacific and Indian declining seal populations were made.

Descripción: A Singular Value Decomposition (SVD) analysis was performed jointly on extreme temperature events in Argentina and sea surface temperature (SST) in the South Atlantic and South Pacific. Sea level pressure (SLP) patterns associated with the first SVD coupled mode were also analyzed. Winter is the season of the year that is best represented by the first mode, accounting for up to 70% of the winter covariance between temperature events and SST. The warm and cold events in Argentina are essentially a consequence of the creation of meridional atmospheric circulations over the continent. Such atmospheric patterns result from displacements and intensity changes of the subtropical anticyclones over the oceans and of the continental low-pressure center in northwestern Argentina. The temperature events in southern Argentina are also closely related to the warming and cooling of the coastal waters in the South Atlantic and South Pacific. The analysis suggests that in summer and winter, high (low) occurrence of warm events and low (high) occurrence of cold events are related to similar oceanic and atmospheric circulation situations. The temperature events in Argentina show higher correlation with the Atlantic than with the Pacific, which reflects the importance of the "orographic barrier" of the Andes Mountains in driving the atmospheric circulation. The only exception to this rule concerns the warm events in spring, for which the warming of the equatorial Pacific (the ENSO pattern) appears as the dominant mode. The temporal patterns of the temperature events in Argentina exhibit significant interannual variability in fall, winter, and spring, with periods of 3 to 5 years. The summer patterns suggest a very low-frequency variation with a period longer than 20 years. Copyright 2003 by the American Geophysical Union.

Descripción: A Singular value decomposition (SVD) analysis was performed jointly on the daily intensity of extreme rainfall (DIER) over Argentina and the sea surface temperature (SST) of all the oceans from 17.5°N to 90°S in order to identify the large-scale variability of the SSTs related to extreme rainfall, in the period 1962-2005. The main objective of the article is to objectively recognize regions of the tropical and subtropical oceans that could be related with the extreme rainfall over Argentina. Spring is the season that is best represented by the first mode, accounting for up to 45% of the covariance between the DIER and SST. The first SVD mode of spring, summer and autumn presents a pattern of SST relating to the El Niño-Southern Oscillations (ENSO) phenomena with an enhanced DIER in different zones of centre and east of Argentina. In the second SVD mode of spring and summer, the SST patterns show cold conditions in the tropical and subtropical Atlantic and near Indonesia with an enhancement of the DIER in the centre and east of Argentina. These modes show a significant decadal variability. In the third SVD mode of spring and summer, the SST patterns present warm and cold conditions in the Indian Ocean and the centre and western Pacific Ocean (PO) with decreased rainfall in the northern and eastern portion of Argentina, respectively. This mode shows a significant period of temporal variability of around 14 years. The third mode of autumn presents warm conditions in the tropical Atlantic and the southwest PO with a low DIER in the centre and east of Argentina. This mode also presents temporal variability of around 14 years. The correlation between each mode derived from analysis of SVD and climate indices related with SST were computed. © 2012 Royal Meteorological Society.