Rodrigo Abarca del Rio | Universidad de Concepción (original) (raw)

Papers by Rodrigo Abarca del Rio

ABSTRACT El presente trabajo estudia eventos de inundaciones en el pasado, asociándolos a indicad... more ABSTRACT El presente trabajo estudia eventos de inundaciones en el pasado, asociándolos a indicadores climáticos y precipitaciones durante la fecha de los eventos adversos. Se estudiaron lo hechos ocurridos durante la segunda mitad del siglo XX en la zona Central de Chile (32ª a 37º S). Se usaron registros de inundaciones recopiladas por Aldunce en el año 2009 y dos indicadores climáticos: Se usó la variabilidad del El Niño-Oscilación del Sur (ENOS) reflejada en la anomalía nino3.4 y como segundo indicador la anomalía de la oscilación antartica (AAO), adicionalmente se usó las anomalías de los datos globales de precipitación de Willmott. Para el estudio se usó como herramienta dos tipos de distribuciones, en este caso distribuciones logit y probit. Los modelos Logit y Probit tienen la ventaja de ser lineales por lo cual su estimación es simple. Se logró establecer que para anomalías positivas de AAO y nino3.4 existe una mayor probabilidad de inundación, según la fdp establecida mediante ambas regresiones lineales. Conocer la función de distribución de probabilidad asociada a los eventos adversos de inundaciones bajo distintas condiciones, permitiendo manejar de mejor manera los recursos durante las distintas subetapas de preparación.

Located within the Altiplano at 3,686 m above sea level, Lake Poopó is remarkably shallow and ver... more Located within the Altiplano at 3,686 m above sea level, Lake Poopó is remarkably shallow and very sensitive to hydrologic recharge. Progressive drying has been observed in the entire Titicaca-Poopó-Desaguadero-Salar de Coipasa (TPDS) system during the last decade, causing dramatic changes to Lake Poopó's surface and its regional water supplies. Our research aims to improve understanding of Lake Poopó water storage capacity. Thus, we propose a new method based on freely available remote sensing data to reproduce Lake Poopó bathymetry. Laser ranging altimeter ICESat (Ice, Cloud, and land Elevation Satellite) is used during the lake's lowest stages to measure vertical heights with high precision over dry land. These heights are used to estimate elevations of water contours obtained with Landsat imagery. Contour points with assigned elevation are filtered and grouped in a points cloud. Mesh gridding and interpolation function are then applied to construct 3D bathymetry. Complementary analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) surfaces from 2000 to 2012 combined with bathymetry gives water levels and storage evolution every 8 days.

Frontiers in Earth Science, 2020

SpringerPlus, 2016

Background Future climate changes will affect agriculture, hydrology, and other socioeconomic fie... more Background Future climate changes will affect agriculture, hydrology, and other socioeconomic fields (Caldeira and Rau 2000; Mearns 2001; IPCC 2007a, b). Atmosphere Ocean Global Climate Model (AOGCM) scenarios enable policy makers to develop new environmental strategies and mitigation methods (IPCC 2007a, b). Several different prospective scenarios are projected based on assumptions of population growth, environmental policies, technological growth, social inequality, and globalization (SRES 2000). Two scenarios for representing high CO 2 emissions (A2) and moderate CO 2 emissions (B2) (IPCC 2007a, b) are used as technical research in order to support public policies (e.g. Räisänen

Australian Meteorological and Oceanographic Journal, 2012

Climate Dynamics, 2016

We show that the monthly recorded history (1878-2013) of the Southern Oscillation Index (SOI), a ... more We show that the monthly recorded history (1878-2013) of the Southern Oscillation Index (SOI), a descriptor of the El Niño Southern Oscillation (ENSO) phenomenon, can be well described as a dynamic system that supports an average nonlinear predictability well beyond the spring barrier. The predictability is strongly linked to a detailed knowledge of the topology of the attractor obtained by embedding the SOI index in a wavelets base state space. Using the state orbits on the attractor we show that the information contained in the Southern Oscillation Index (SOI) is sufficient to provide average nonlinear predictions for time periods of 2, 3 and 4 years in advance throughout the 20th century with an acceptable error. The simplicity of implementation and ease of use makes it suitable for studying non linear predictability in any area where observations are similar to those that describe the ENSO phenomenon.

Surveys in Geophysics, 2016

Lakes are integrators of environmental change occurring at both the regional and global scale. Th... more Lakes are integrators of environmental change occurring at both the regional and global scale. They present a wide range of behavior on a variety of timescales (cyclic and secular) depending on their morphology and climate conditions. Lakes play a crucial role in retaining and stocking water, and because of the significant global environmental changes occurring at several anthropocentric levels, the necessity to monitor all morphodynamic characteristics [e.g., water level, surface (water contour) and volume] has increased substantially. Satellite altimetry and imagery are now widely used together to calculate lake and reservoir water storage changes worldwide. However, strategies and algorithms to calculate these characteristics are not straightforward, and specific approaches need to be developed. We present a review of some of these methodologies by using lakes over the Tibetan Plateau to illustrate some critical aspects and issues (technical and scientific) linked to the observation of climate change impact on surface waters from remote sensing data. Many authors have measured water variation using the limited remote sensing measurements available over short time periods, even though the time series are probably too short to directly link these results with climate change. Indeed, there are many processes and factors, like the influence of lake morphology, that are beyond observation and are still uncertain. The time response for lakes to reach a new state of equilibrium is a key aspect that is often neglected in current literature. Observations over a long period of time, including maintaining a constellation of comprehensive and complementary satellite missions with service continuity over decades, are therefore necessary especially when the ground gauge network is too limited. In addition, the design of future satellite missions with new instrumental concepts (e.g., SAR, SARin, Ka band altimetry, Ka interferometry) will also be suitable for complete monitoring of continental waters.

Surveys in Geophysics, 2015

In 2000, the World population was 6.2 billion people; it reached 7 billion in 2012, and is expect... more In 2000, the World population was 6.2 billion people; it reached 7 billion in 2012, and is expected to reach 9.5 billion (± 0.4) in 2050, 11 billion (± 1.5) in 2100, according to the 2012 UN projections (Gerland et al. 2014). The trend after 2100 is still one of global demographic growth, but after 2060, Africa is the only continent where the population would still increase. The amount of water consumed annually to produce the food necessary to meet the needs of the populations varies greatly between countries, from about 600 to 2500 m 3 /y per capita (Zimmer 2013), depending on their wealth, their food habits, and the percentage of food waste they generate (on average, 30% of the food produced is wasted). In 2000, the total food production was on the order of 3300 million tons (in cereal equivalents). In 2014, it is estimated that about 0.8 billion inhabitants of the planet suffer from hunger (FAO 2014) and do not get the nutrition they need to be in good health or, in the case of children, to grow properly (both physically and intellectually). This food deficit was on the order of 40 million tons of cereal equivalents in 2014. The number of inhabitants with a food deficit was about 0.85 billion before the 2008 crisis and was decreasing annually, but it increased abruptly after 2008 up to 1 billion inhabitants, and is slowly decreasing now. Assuming a World average water consumption for food of 1300 m 3 /y per capita in 2000, 1,400 m 3 /y in 2050 and 1500 m 3 /y in 2100, a volume of water of around 8200 km 3 /y was needed in 2000, 13000 km 3 /y will be needed in 2050 and 16500 km 3 /y in 2100 (Marsily 2009). Can bioenergy be added to food production? Will that much water be available on earth, and where will it come from? Is climate change going to modify the answers to these questions? Can severe droughts occur? Can there be conflicts related to a food deficit? Some preliminary answers and scenarios for food production will be given in this paper from a hydrologist viewpoint.

Journal of Geodetic Science, 2012

Interdecadal oscillations in Atmospheric Angular Momentum variationsGlobal Atmospheric Angular Mo... more Interdecadal oscillations in Atmospheric Angular Momentum variationsGlobal Atmospheric Angular Momentum (AAM) is an intrinsic index for describing processes that affect the atmospheric circulation on time scales ranging from intraseasonal to secular. It is associated with length-of-day (LOD) variability through conservation of global angular momentum in planet Earth and thus is of considerable importance for quantifying how the Earth acts as a system. The availability of lengthy AAM time series computed from the recent 20th Century atmospheric reanalyses (1870-2008), complemented by the NCAR-NCEP reanalysis in the overlapping period of 1948-2008 allows the investigation of the role of decadal and interdecadal cycles as well as the recent overall trend in AAM. Thus, we extend to the entire 20th century (and prior, back to 1870) results concerning decadal time scales and a secular positive trend detected over recent decades by different authors. In addition, we also note that AAM has ...

Remote Sensing, 2013

The Open Atmospheric Science Journal, 2011

In this work an attempt is made to determine whether the annual and semiannual components of the ... more In this work an attempt is made to determine whether the annual and semiannual components of the NmF2 observed over Concepción (36.8°S; 73.0°W), Chile, exhibit long-term trends. Monthly median hourly values of NmF2 determined from ionosonde observations are analyzed. Although the assessed trends for NmF2 and for the semiannual and annual components of NmF2, are hardly significant by any statistical test, they exhibit a systematic diurnal evolution. NmF2 trends are almost null during night time and negative from around noon to the early evening. The same can be said for trends of the amplitudes of the semiannual component. On the contrary, trends for the annual component are always positive and exhibit a rather irregular diurnal pattern. It seems reasonable then to particularly look for an explanation of the semiannual component long-term changes when concerned with long-term changes of NmF2. The semiannual variation is linked to composition and thermospheric wind effects, and solar zenith angle changes which may be connected to changes of the strength of the global circulation. But, more study is needed to envisage the changes on the semiannual component of NmF2 which may arise from eventual long-term changes of the global circulation.

Annales Geophysicae, 2014

We analyse phase lags between the 11-year variations of three records: the semi-annual oscillatio... more We analyse phase lags between the 11-year variations of three records: the semi-annual oscillation of the length of day (LOD), the solar activity (SA) and the cosmic ray intensity (CRI). The analysis was done for solar cycles 20–23. Observed relationships between LOD, CRI and SA are discussed separately for even and odd solar cycles. Phase lags were calculated using different methods (comparison of maximal points of cycles, maximal correlation coefficient, line of synchronization of cross-recurrence plots). We have found different phase lags between SA and CRI for even and odd solar cycles, confirming previous studies. The evolution of phase lags between SA and LOD as well as between CRI and LOD shows a positive trend with additional variations of phase lag values. For solar cycle 20, phase lags between SA and CRI, between SA and LOD, and between CRI and LOD were found to be negative. Overall, our study suggests that, if anything, the length of day could be influenced by solar irrad...

Journal of Geophysical Research, 2006

Near-surface circulation of the Panama Bight and surrounding regions [0-9°N; 73°W-90°W] was studi... more Near-surface circulation of the Panama Bight and surrounding regions [0-9°N; 73°W-90°W] was studied using satellite-tracked drifter trajectories from 1979-2004. This region encompasses three major currents showing typical velocities of 30cmsAˋ1:(1)theeastwardNorthEquatorialCounterCurrent(NECC),(2)thenear−circularPanamaBightCyclonicGyre(PBCG),and(3)thewestwardSouthEquatorialCurrent(SEC).WedonotobservesignificantmodificationofthemeansurfacecirculationduringElNinoSouthernOscillationevents,eveniftheSECisslightlyreinforcedduringrelativelywarmElNinoperiods.Atseasonalscales,thecirculationisstronglycontrolledbytheactivityofthePanamawind−jet:inborealwinter,thecurrentsarestrongerandananticycloniccellispresentwestofthePBCG.Thisdipoleleadstoastrong30 cm s À1 : (1) the eastward North Equatorial Counter Current (NECC), (2) the near-circular Panama Bight Cyclonic Gyre (PBCG), and (3) the westward South Equatorial Current (SEC). We do not observe significant modification of the mean surface circulation during El Niño Southern Oscillation events, even if the SEC is slightly reinforced during relatively warm El Niño periods. At seasonal scales, the circulation is strongly controlled by the activity of the Panama wind-jet: in boreal winter, the currents are stronger and an anticyclonic cell is present west of the PBCG. This dipole leads to a strong 30cmsAˋ1:(1)theeastwardNorthEquatorialCounterCurrent(NECC),(2)thenear−circularPanamaBightCyclonicGyre(PBCG),and(3)thewestwardSouthEquatorialCurrent(SEC).WedonotobservesignificantmodificationofthemeansurfacecirculationduringElNinoSouthernOscillationevents,eveniftheSECisslightlyreinforcedduringrelativelywarmElNinoperiods.Atseasonalscales,thecirculationisstronglycontrolledbytheactivityofthePanamawind−jet:inborealwinter,thecurrentsarestrongerandananticycloniccellispresentwestofthePBCG.Thisdipoleleadstoastrong200 km wide southward current which then disappears during the rest of the year. In summer, the three major currents have reduced intensity by 30%-40%. Large-scale current vorticity shows that the upwelling associated with the PBCG is also 3-4 times stronger in winter than during summer months. The kinetic energy is largely dominated by eddy activity and its intensity is double in winter than during summer. Ageostrophic motions and eddy activity appear to have a substantial impact on the energy spatial distribution. In the NECC and SEC regions, Lagrangian scales are anisotropic and zonally enhanced in the direction of the mean currents. The typical integral time and length scales of these regions are 2.5 days and 50-60 km in the zonal direction and 1.5 days and 25-30 km in the meridional direction. Lateral eddy diffusivity coefficients are on the order of 11-14 10 7 cm 2 s À1 zonally and 5-6 10 7 cm 2 s À1 meridionally. In contrast, in the PBCG region, the Lagrangian characteristics are isotropic with typical timescales of 1.7 days, space scales of 30 km and eddy diffusivity coefficients of 6 10 7 cm 2 s À1 in both directions.

Journal of Geodynamics, 2003

The analysis of variability in Atmospheric Angular Momentum (AAM) and Length of day (LOD) of Abar... more The analysis of variability in Atmospheric Angular Momentum (AAM) and Length of day (LOD) of Abarca del Rio et al. [Ann. Geophys. 18 (2000) 347] is extended to investigate a possible connection with solar activity fluctuations from interannual to secular time scales. The southern oscillation index and records of sea surface temperature are used as proxy series in this analysis during the era prior to the availability of AAM analyses. At interannual times scales, the variability in AAM and LOD agrees with that in solar activity with regard to the decadal cycle in the stratospheric quasi biennial oscillation and solar activity but whose phases are slowly shifting from one another with time, while the stratospheric quasi biennial cycle agrees with the solar quasi biennial cycle, though led by 6 years. At decadal times scales, AAM varies statistically with the solar decadal cycle over much of the last century since 1930-1940. The decadal mode in AAM is suggested here to be generated by upward propagation of surface atmospheric modes, from the surface throughout the troposphere through the stratosphere. Equatorial Sea Surface Temperature (SST) variability may be considered a proxy index for AAM variability because of the relationship to the El Nino/Southern Oscillation; its analysis over the last three centuries (1730-2000) and that of LOD since 1830 confirm the agreement found over the last part of the 20th century, as well as the general disagreement before.