The Andes climate and weather

Garreaud, René

doi:10.5194/adgeo-22-3-2009

Cited by 535 publications

(521 citation statements)

References 61 publications

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“…At these latitudes, strong and stable atmospheric subsidence maintains the SE Pacific anticyclone and promotes upwelling of cold waters, in turn, promoting further subsidence and drying of the air at the coast (Garreaud, 2009; Garreaud et al, 2010). However, estimates of onset, origin, and intensity of Atacama aridity have been largely debated (e.g., Dunai et al, 2005; Hartley & Chong, 2002).…”

Section: Field Settingmentioning

confidence: 99%

Slow Long‐Term Exhumation of the West Central Andean Plate Boundary, Chile

2018

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We present a regional analysis of new low‐temperature thermochronometer ages from the Central Andean fore arc to provide insights into the exhumation history of the western Andean margin. To derive exhumation rates over 10 million‐year timescales, 38 new apatite and zircon (U‐Th)/He ages were analyzed along six ~500‐km long near‐equal‐elevation, coast parallel, transects in the Coastal Cordillera (CC) and higher‐elevation Precordillera (PC) of the northern Chilean Andes between latitudes 18.5°S and 22.5°S. These transects were augmented with age‐elevation profiles where possible. Results are synthesized with previously published thermochronometric data, corroborating a previously observed trenchward increase in cooling ages in Peru and northern Chile. One‐dimensional thermal‐kinematic modeling of all available multichronometer equal‐elevation samples reveals mean exhumation rates of <0.2 km/Myr since ~50 Ma in the PC and ~100 Ma in the CC. Regression of pseudovertical age‐elevation transects in the CC yields comparable rates of ~0.05 to ~0.12 km/Myr between ~40 and 80 Ma. Differences between the long‐term mean 1‐D rates and shorter‐term age‐elevation‐derived rates indicate low variability in the exhumation history. Modeling results suggest similar background exhumation rates in the CC and PC; younger ages in the PC are largely a function of increased heat flow and consequently an elevated geothermal gradient near the arc. Slow exhumation rates are suggestive of semiarid conditions across the region since at least the Eocene and deformation and development of the Andean fore arc around this time.

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Section: Field Settingmentioning

confidence: 99%

Slow Long‐Term Exhumation of the West Central Andean Plate Boundary, Chile

2018

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“…It is important to point out that the parameter A (parameter for adjustment the precipitation data) was defined during the calibration as 1.13 and 1.58 for DGA and UD rainfall inputs respectively. Furthermore, it is known that at the western slope of the Andes, the orographic effect may exert a strong influence over local rainfall patterns (Falvey and Garreaud [28], Garreaud [8]), producing a high spatial variability and increasing the rainfall amounts. The only way to reproduce this effect is through a dense network of rain gauges.…”

Section: Resultsmentioning

confidence: 99%

“…Due to the location of the watershed, its mountainous nature and wide elevation range (see Figure 1), the watershed presents high spatial and temporal variability with respect to meteorological and hydrological characteristics, where the orographic effect at the west slopes of the Andes produces an increasing in the rainfall amounts (Gerreaud [8], Vicuña et al [12]). In addition, the cycle of temperature, the seasonality, and the El Niño phenomena produces temporal variability on the rainfall patterns (Diaz et al [13], Escobar and Aceituno [14], Montecinos and Aceituno [15])and therefore, on the hydrological processes and the stream flows produced.…”

Section: Introductionmentioning

confidence: 99%

“…The Andean mountains are the less major mountainous areas investigated, mainly due to the lack of in-situ observations with sufficient density and temporal resolution to resolve the mesoscale phenomena (Gerreaud [8]). As an option for perform hydrological researches in scarce-data environments is the use of globally available meteorological datasets as inputs for hydrological models.…”

Section: Introductionmentioning

confidence: 99%

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The use of global gridded datasets in a hydrological model for a scarce-data Andean watershed

Muñoz

Billib²,

Arumí

et al. 2011

WIT Transactions on Ecology and the Environment

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Global gridded climatological (GGC) datasets including precipitation, temperature, pressure, and circulation indices, among others are becoming more and more precise, accessible and common in climate and hydrological research. In this study, we evaluate these datasets as an alternative input to supply the lack of measured climatological data in a Chilean Andean watershed in order to develop a monthly water balance model. A conceptual model was carried out for the simulation of stream-flows in the mountainous area of the Polcura River basin in south-central Chile. Based on 18 years of simulation and four model performance assessments, we concluded that from GGC datasets it is possible to reproduce observed flows and the snow-rain regime with "good" performance, being an adequate alternative to supply the lack of measured data, but taking the following considerations i) the GGC rainfall datasets in the Andean area are undervalued; this effect is transferred to the simulated flows, and must be fixed through an amplification coefficient (a calibration parameter), ii) due to the nature of the GGC datasets and to the orographic effect produced by the Andean mountains, the rainfall amounts are damped during the rainy season which result in a sub-estimation of the simulated flows during the winter, and limits the model scope to applications where peak flows are dispensable, and iii) the simulated snow-melt minimum and mean flows are close to the observed flows, which suggest that the GGC datasets are an adequate alternative for estimating the evapotranspiration and snow-melting amounts.

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“…Maximum rainfall to the southern Andes occurs along seasonal storm tracks (Garreaud 2009) and is delivered mainly by westerly (NW to SW) winds (Smith and Evans 2007). Frontal storms traverse low-relief offshore islands and locally a narrow coastal plain ( Fig.…”

Section: Physiography and Regional Climatementioning

confidence: 99%

Acute sedimentation response to rainfall following the explosive phase of the 2008–2009 eruption of Chaitén volcano, Chile

Pierson

Major

Amigo³

et al. 2013

Bull Volcanol

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The 10-day explosive phase at the start of the 2008-2009 eruption of Chaitén volcano in southern Chile (42.83°S, 72.65°W) blanketed the steep, rain-forestcloaked, 77-km 2 Chaitén River drainage basin with 3 to >100 cm of tephra; predominantly fine to extremely fine rhyolitic ash fell during the latter half of the explosive phase. Rain falling on this ash blanket within days of cessation of major explosive activity generated a hyperconcentratedflow lahar, followed closely by a complex, multi-day, muddy flood (streamflow bordering on dilute hyperconcentrated flow). Sediment mobilized in this lahar-flood event filled the Chaitén River channel with up to 7 m of sediment, buried the town of Chaitén (10 km downstream of the volcano) in up to 3 m of sediment, and caused the lower 3 km of the channel to avulse through the town. Although neither the nature nor rate of the sedimentation response is unprecedented, they are unusual in several ways: (1) (3) The volume of sediment eroded from hillslopes and delivered to the Chaitén River channel was at least 3-8×10 6 m 3 -roughly 15-40 % of the minimum tephra volume that mantled the Chaitén River drainage basin. (4) The acute sedimentation response to rainfall appears to have been due to the thickness and fineness of the ash blanket (inhibiting infiltration of rain) and the steepness of the basin's hillslopes. Other possible factors such as the prior formation of an ash crust, development of a hydrophobic surface layer, or large-scale destruction of rain-intercepting vegetation did not play a role.

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The Andes climate and weather

Cited by 535 publications

References 61 publications

Slow Long‐Term Exhumation of the West Central Andean Plate Boundary, Chile

Slow Long‐Term Exhumation of the West Central Andean Plate Boundary, Chile

The use of global gridded datasets in a hydrological model for a scarce-data Andean watershed

Acute sedimentation response to rainfall following the explosive phase of the 2008–2009 eruption of Chaitén volcano, Chile

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