Climate Variability and Trends in Bolivia

2013 ◽  
Vol 52 (1) ◽  
pp. 130-146 ◽  
Author(s):  
Christian Seiler ◽  
Ronald W. A. Hutjes ◽  
Pavel Kabat
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Austral Summer ◽  
Climate Extremes ◽  
Antarctic Oscillation ◽  
The Andes ◽  
Near Term ◽  
Variable Precipitation ◽  
The Impact

AbstractClimate-related disasters in Bolivia are frequent, severe, and manifold and affect large parts of the population, economy, and ecosystems. Potentially amplified through climate change, natural hazards are of growing concern. To better understand these events, homogenized daily observations of temperature (29 stations) and precipitation (68 stations) from 1960 to 2009 were analyzed in this study. The impact of the positive (+) and negative (−) phases of the three climate modes (i) Pacific decadal oscillation (PDO), (ii) El Niño–Southern Oscillation (ENSO) with El Niño (EN) and La Niña (LN) events, and (iii) Antarctic Oscillation (AAO) were assessed. Temperatures were found to be higher during PDO(+), EN, and AAO(+) in the Andes. Total amounts of rainfall, as well as the number of extreme events, were higher during PDO(+), EN, and LN in the lowlands. During austral summer [December–February (DJF)], EN led to drier conditions in the Andes with more variable precipitation. Temperatures increased at a rate of 0.1°C per decade, with stronger increases in the Andes and in the dry season. Rainfall totals increased from 1965 to 1984 [12% in DJF and 18% in June–August (JJA)] and decreased afterward (−4% in DJF and −10% in JJA), following roughly the pattern of PDO. Trends of climate extremes generally corresponded to trends of climate means. Findings suggest that Bolivia’s climate will be warmer and drier than average in the near-term future. Having entered PDO(−) in 2007, droughts and LN-related floods can be expected in the lowlands, while increasing temperatures suggest higher risks of drought in the Andes.

Observed Relationships between the El Niño–Southern Oscillation and the Extratropical Zonal-Mean Circulation

2006 ◽  
Vol 19 (2) ◽  
pp. 276-287 ◽  
Author(s):  
Michelle L. L’Heureux ◽  
David W. J. Thompson
Keyword(s):  
Zonal Wind ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Austral Summer ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Annular Mode ◽  
Mean Circulation ◽  
The Impact

Abstract There is increasing evidence indicating that the climate response to variations in the El Niño–Southern Oscillation (ENSO) includes not only thermally forced zonal wind anomalies in the subtropics but also eddy-driven zonal wind anomalies that extend into the mid–high latitudes of both hemispheres. In this study, new insights into the observed seasonally varying signature of ENSO in the extratropical zonal-mean circulation are provided and the associated linkages with the dominant patterns of extratropical variability are examined. The zonal-mean extratropical atmospheric response to ENSO is characterized by two principal features: an equivalent barotropic dipole in the Southern Hemisphere (SH) zonal-mean zonal flow with centers of action located near ∼40° and ∼60° during austral summer, and a weaker, but analogous, dipole in the Northern Hemisphere (NH) with centers of action located near ∼25° and ∼45° during early and late boreal winter. Both structures are accompanied by eddy momentum flux anomalies that exhibit a remarkable degree of hemispheric symmetry. In the SH, the extratropical signature of ENSO projects strongly onto the primary mode of large-scale variability, the southern annular mode (SAM). During the austral summer, roughly 25% of the temporal variability in the SAM is linearly related to fluctuations in the ENSO cycle. An analogous relationship is not observed in association with the principal mode of climate variability in the NH, the northern annular mode (NAM). It is argued that the seasonally varying impact of ENSO on the extratropical circulation is consistent with the impact of the thermally forced subtropical wind anomalies on the dissipation of equatorward-propagating wave activity at subtropical latitudes.

Opposite Phases of the Antarctic Oscillation and Relationships with Intraseasonal to Interannual Activity in the Tropics during the Austral Summer

2005 ◽  
Vol 18 (5) ◽  
pp. 702-718 ◽  
Author(s):  
Leila M. V. Carvalho ◽  
Charles Jones ◽  
Tércio Ambrizzi
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Deep Convection ◽  
Low Frequency ◽  
Austral Summer ◽  
Longwave Radiation ◽  
Antarctic Oscillation ◽  
The Tropics ◽  
The Antarctic

Abstract The Antarctic Oscillation (AAO) has been observed as a deep oscillation in the mid- and high southern latitudes. In the present study, the AAO pattern is defined as the leading mode of the empirical orthogonal function (EOF-1) obtained from daily 700-hPa geopotential height anomalies from 1979 to 2000. Here the objective is to identify daily positive and negative AAO phases and relationships with intraseasonal activity in the Tropics and phases of the El Niño–Southern Oscillation (ENSO) during the austral summer [December–January–February (DJF)]. Positive and negative AAO phases are defined when the daily EOF-1 time coefficient is above (or below) one standard deviation of the DJF mean. Composites of low-frequency sea surface temperature variation, 200-hPa zonal wind, and outgoing longwave radiation (OLR) indicate that negative (positive) phases of the AAO are dominant when patterns of SST, convection, and circulation anomalies resemble El Niño (La Niña) phases of ENSO. Enhanced intraseasonal activity from the Tropics to the extratropics of the Southern (Northern) Hemisphere is associated with negative (positive) phases of the AAO. In addition, there is indication that the onset of negative phases of the AAO is related to the propagation of the Madden–Julian oscillation (MJO). Suppression of intraseasonal convective activity over Indonesia is observed in positive AAO phases. It is hypothesized that deep convection in the central tropical Pacific, which is related to either El Niño or eastward-propagating MJO, or a combination of both phenomena, modulates the Southern Hemisphere circulation and favors negative AAO phases during DJF. The alternation of AAO phases seems to be linked to the latitudinal migration of the subtropical upper-level jet and variations in the intensity of the polar jet. This, in turn, affects extratropical cyclone properties, such as origin, minimum/maximum central pressure, and their equatorward propagation.

scholarly journals Inter-El Niño variability and its impact on the South American low-level jet east of the Andes during austral summer − two case studies

2006 ◽  
Vol 6 ◽  
pp. 283-287 ◽  
Author(s):  
G. A. M. Silva ◽  
T. Ambrizzi
Keyword(s):  
El Niño ◽  
El Nino ◽  
Austral Summer ◽  
South American ◽  
The South ◽  
Trade Winds ◽  
Low Level ◽  
The Andes ◽  
Low Level Jet ◽  
The Impact

Abstract. The impact of the maximum convection location over eastern and central Equatorial Pacific over the intensity and positioning of the South American Low-Level Jet east of the Andes (SALLJ) during the austral summer was investigated. The Bonner criteria 1 was applied to the NCEP-NCAR circulation fields during the El Niño of 1997/1998 and 2002/2003 to identify the SALLJ episodes. The composites of the atmospheric circulation over the South America during El Niño events showed that the SALLJ can be influenced by small displacements of the quasi-stationary Rossby waves position. During the strong El Niño event of 1997/1998 the SALLJ is maintained by the eastern trade winds. A low-level anomalous anticyclonic circulation over the central part of Brazil enhanced the wind in the nucleus of the jet and displaced its axis to the Northern Argentina and South of Brazil. However, the northern trade winds seem to maintain the SALLJ during the weak El Niño of 2002/2003. The jet was weaker and displaced more southeastward of Brazil than during the strong event.

scholarly journals The Impact of Obliquity Change on El Niño Southern Oscillation (ENSO) and La Niña Climate Episodes

2022 ◽  
Author(s):  
Paul C. Rivera
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Global Climate ◽  
Global Climate Model ◽  
La Niña ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
La Nina ◽  
The Impact

An alternative physical mechanism is proposed to describe the occurrence of the episodic El Nino Southern Oscillation (ENSO) and La Nina climatic phenomena. This is based on the earthquake-perturbed obliquity change (EPOCH) model previously discovered as a major cause of the global climate change problem. Massive quakes impart a very strong oceanic force that can move the moon which in turn pulls the earth’s axis and change the planetary obliquity. Analysis of the annual geomagnetic north-pole shift and global seismic data revealed this previously undiscovered force. Using a higher obliquity in the global climate model EdGCM and constant greenhouse gas forcing showed that the seismic-induced polar motion and associated enhanced obliquity could be the major mechanism governing the mysterious climate anomalies attributed to El Nino and La Nina cycles.

scholarly journals EL NINO, LA NINA, DAN PENAWARAN PANGAN DI JAWA, INDONESIA

2011 ◽  
Vol 12 (2) ◽  
pp. 257
Author(s):  
Arini Wahyu Utami ◽  
Jamhari Jamhari ◽  
Suhatmini Hardyastuti
Keyword(s):  
El Niño ◽  
Time Series Data ◽  
El Nino ◽  
Southern Oscillation ◽  
Regression Function ◽  
La Niña ◽  
Series Data ◽  
Cross Sectional ◽  
La Nina ◽  
The Impact

Paddy and maize are two important food crops in Indonesia and mainly produced in Java Island. This research aimed to know the impact of El Nino and La Nina on paddy and maize farmer’s supply in Java. Cross sectional data from four provinces in Java was combined with time series data during 1987-2006. Paddy supply was estimated using log model, while maize supply used autoregressive model; each was estimated using two types of regression function. First, it included dummy variable of El Nino and La Nina to know their influence into paddy and maize supply. Second, Southern Oscillation Index was used to analyze the supply changing when El Nino or La Nina occur. The result showed that El Nino and La Nina did not influence paddy supply, while La Nina influenced maize supply in Java. Maize supply increased when La Nina occurred.

Response of benthic macroinvertebrate communities to El Niño related drought events in six upland streams in south-central Ontario

2008 ◽  
Vol 65 (5) ◽  
pp. 890-905 ◽  
Author(s):  
Beth Gilbert ◽  
Peter J Dillon ◽  
Keith M Somers ◽  
Ron A Reid ◽  
Lem Scott
Keyword(s):  
Relative Abundance ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Benthic Macroinvertebrate ◽  
Macroinvertebrate Communities ◽  
South Central ◽  
Effects Of Drought ◽  
One Year ◽  
The Impact

We examined the effects of extreme drought events on benthic macroinvertebrate (BMI) community structure in six forested upland streams in south-central Ontario, Canada, during a 9-year period. Variation in the mean winter El Niño – Southern Oscillation Index was strongly correlated with drought conditions (zero flow days) in the study streams. Drought onset and duration varied among study streams and among years. Below-average precipitation coincided with the occurrence of drought, although it remains unclear if snowfall and rainfall contributed equally to the impact of decreased precipitation. Increased relative abundance of Ephemeroptera, Plecoptera, and Trichoptera (EPT) one year following drought and decreased relative abundance two years after drought indicated high resistance but poor resilience. In contrast, chironomids showed poor resistance and high resilience. Although these patterns were not consistent across all streams, temporal coherence among streams was found in percent EPT, percent chironomids, and percent dipterans, suggesting that drought acts as a disturbance mechanism that simplifies benthos community assemblages. Biocriteria developed from 22 nearby reference streams indicated that abnormal BMI communities occurred only after recurring episodes of drought, indicating that the effects of drought are cumulative. Headwater streams may prove to be sentinel ecosystems for monitoring the impacts of climate change.

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