Hydroclimate of the Andes Part II: Hydroclimate Variability and Sub-Continental Patterns

Arias, Paola A.; Garreaud, René; Poveda, Germán; Espinoza, Jhan Carlo; Molina, Jorge; Masiokas, Mariano; Viale, Maximiliano; Scaff, Lucia; Oevelen, P.J. van

doi:10.3389/feart.2020.505467

Cited by 69 publications

(64 citation statements)

References 195 publications

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“…The climate of South America varies widely from North to South and West to East, due to its large latitudinal extent and topographic heterogeneity (Garreaud et al 2009;Reboita et al 2010;Espinoza et al 2020;Arias et al 2021a). The northern and central parts of South America have a tropical climate; arid desert and steppe climate characterizes the western edge, the southeast is relatively temperate, while the southwestern edge has a polar tundra climate (Beck et al 2018).…”

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confidence: 99%

“…For instance, most studies using Global Climate Models (GCMs) show that while models are able to simulate the main precipitation, temperature and circulation features over the continent, they exhibit systematic errors in precipitation magnitudes, such as underestimation in tropical South America and overestimation in the Andes and La Plata basin (Yin et al 2013;Gulizia and Camilloni 2015;Sierra et al 2015;Zazulie et al 2017;Rivera and Arnould 2020;Arias et al 2021b;Dias and Reboita 2021;Ortega et al 2021). Several studies also document the limitations of GCMs in simulating mesoscale circulation features associated with the Andes (Pabón-Caicedo et al 2020;Arias et al 2021a), and the genesis of mesoscale convective systems over southeastern South America (Muñoz et al 2015(Muñoz et al , 2016Doss-Gollin 2018).…”

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confidence: 99%

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Assessment of CMIP6 Performance and Projected Temperature and Precipitation Changes Over South America

et al. 2021

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We evaluate the performance of a large ensemble of Global Climate Models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6) over South America for a recent past reference period and examine their projections of twenty-first century precipitation and temperature changes. The future changes are computed for two time slices (2040–2059 and 2080–2099) relative to the reference period (1995–2014) under four Shared Socioeconomic Pathways (SSPs, SSP1–2.6, SSP2–4.5, SSP3–7.0 and SSP5–8.5). The CMIP6 GCMs successfully capture the main climate characteristics across South America. However, they exhibit varying skill in the spatiotemporal distribution of precipitation and temperature at the sub-regional scale, particularly over high latitudes and altitudes. Future precipitation exhibits a decrease over the east of the northern Andes in tropical South America and the southern Andes in Chile and Amazonia, and an increase over southeastern South America and the northern Andes—a result generally consistent with earlier CMIP (3 and 5) projections. However, most of these changes remain within the range of variability of the reference period. In contrast, temperature increases are robust in terms of magnitude even under the SSP1–2.6. Future changes mostly progress monotonically from the weakest to the strongest forcing scenario, and from the mid-century to late-century projection period. There is an increase in the seasonality of the intra-annual precipitation distribution, as the wetter part of the year contributes relatively more to the annual total. Furthermore, an increasingly heavy-tailed precipitation distribution and a rightward shifted temperature distribution provide strong indications of a more intense hydrological cycle as greenhouse gas emissions increase. The relative distance of an individual GCM from the ensemble mean does not substantially vary across different scenarios. We found no clear systematic linkage between model spread about the mean in the reference period and the magnitude of simulated sub-regional climate change in the future period. Overall, these results could be useful for regional climate change impact assessments across South America.

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Assessment of CMIP6 Performance and Projected Temperature and Precipitation Changes Over South America

et al. 2021

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“…After a validation analysis showed that the GCM-RCM systems were able to simulate a realistic seasonal evolution of the monsoons, they identified common responses across the different monsoon systems to global warming conditions: a delay in the monsoon onset, a decrease in monsoon precipitation seasonality and a reduction in rainy season length associated with a decrease in pre-monsoon precipitation and latent heat release, which in turn inhibited the monsoon transition into deep convection.The issue of the El Nino Southern Oscillation (ENSO) has been little explored within the context of regional climate modeling, probably because ENSO is a large scale phenomenon with global teleconnections, and therefore belongs more naturally to the global modeling realm. However, ENSO is an important factor regulating the variability of many regions of the World, especially in the tropics, and the ENSO signal, although originating remotely, can be substantially modulated by local forcings, such as topography or land use (e.g Arias et al 2021)…”

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confidence: 99%

The CORDEX-CORE EXP-I Initiative: Description and Highlight Results from the Initial Analysis

Giorgi

Coppola

Jacob

et al. 2022

Bulletin of the American Meteorological Society

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We describe the first effort within the Coordinated Regional Climate Downscaling Experiment - Coordinated Output for Regional Evaluation, or CORDEX-CORE EXP-I. It consists of a set of 21st century projections with two regional climate models (RCMs) downscaling three global climate model (GCM) simulations from the CMIP5 program, for two greenhouse gas concentration pathways (RCP8.5 and RCP2.6), over 9 CORDEX domains at ~25 km grid spacing. Illustrative examples from the initial analysis of this ensemble are presented, covering a wide range of topics, such as added value of RCM nesting, extreme indices, tropical and extratropical storms, monsoons, ENSO, severe storm environments, emergence of change signals, energy production. They show that the CORDEX-CORE EXP-I ensemble can provide downscaled information of unprecedented comprehensiveness to increase understanding of processes relevant for regional climate change and impacts, and to assess the added value of RCMs. The CORDEX-CORE EXP-I dataset, which will be incrementally augmented with new simulations, is intended to be a public resource available to the scientific and end-user communities for application to process studies, impacts on different socioeconomic sectors and climate service activities. The future of the CORDEX-CORE initiative is also discussed.

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“…However, the discovered changes of water availability are spatially variable across the Andes as different interacting mechanisms modify the hydroclimatic system on different timescales (e.g. ENSO (Garreaud, 2009;Arias et al, 2021) or decrease for the period 2000-2020 is reported for either the tropical Andes (Rabatel et al, 2013) or the RSB (Schauwecker et al, 2014;Gurgiser et al, 2016). Here, we find increased early season precipitation under El Niño conditions with only one significant month and small rainfall sums.…”

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confidence: 56%

Vegetation indices as proxies for spatio-temporal variations in water availability in the Rio Santa valley (Peruvian Andes)

Hänchen

Klein

Maussion

et al. 2021

Preprint

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Abstract. In the semi-arid Peruvian Andes, the growing season is mostly determined by the timing of the onset and retreat of the wet season, to which annual crop yields are highly sensitive. Recently, local farmers in the Rio Santa basin (RSB) reported decreasing predictability of the onset of the rainy season and further challenges related to changes in rainfall characteristics. Previous studies based on time series of local rain gauges however, did not find any significant changes in either the timing or intensity of the wet season. Both in-situ and satellite rainfall data for the region lack the necessary spatial resolution to capture the highly variable rainfall distribution typical for complex terrain, and are often questionable in terms of quality and temporal consistency. To date, there remains considerable uncertainty in the RSB regarding hydrological changes over the last decades. In this study, we overcome this limitation by exploiting satellite-derived information on vegetation greenness to reveal a robust and highly resolved picture of recent changes in rainfall and vegetation phenology across the region: As the semi-arid climate causes water availability (i.e. precipitation) to be the key limiting factor for plant growth, patterns of precipitation occurrence and the seasonality of vegetation indices (VIs) are tightly coupled. Therefore, VIs can serve as an integrated proxy of rainfall. By combining MODIS Aqua and Terra VIs for 2000–2020 and several datasets of precipitation, we explore recent spatio-temporal changes in vegetation and water availability. Furthermore, we examine their links to El Niño Southern Oscillation (ENSO). While different rainfall datasets tend to be incoherent in the period of observation, we find significant greening over the majority of the RSB domain in VI data, particularly pronounced during the dry season (Austral winter). This indicates an overall increase of plant available water over time. The rainy season onset and consequently the start of the growing season (SOS) exhibits high inter-annual variability and dominates the growing season length (LOS). The end of the growing season (EOS) is significantly delayed in the analysis which matches the observed dry-season greening. By partitioning the results into periods of three stages of ENSO (neutral, Niño, Niña), we find an earlier SOS and an overall increased season length in years associated with El Niño. However, the appearance of Niño/Niña events during the analysed period cannot explain the observed greening and delayed EOS. While our study could not corroborate anecdotal evidence for recent changes in the SOS, we confirm that the SOS is highly variable and conclude that rainfed farming in the RSB would profit from future efforts being directed towards improving medium-range forecasts of the rainy season onset.

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Hydroclimate of the Andes Part II: Hydroclimate Variability and Sub-Continental Patterns

Cited by 69 publications

References 195 publications

Assessment of CMIP6 Performance and Projected Temperature and Precipitation Changes Over South America

Assessment of CMIP6 Performance and Projected Temperature and Precipitation Changes Over South America

The CORDEX-CORE EXP-I Initiative: Description and Highlight Results from the Initial Analysis

Vegetation indices as proxies for spatio-temporal variations in water availability in the Rio Santa valley (Peruvian Andes)

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