Browsing by Author "Aguirre Correa, Francisca"

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    Evaporation driven by Atmospheric Boundary Layer Processes over a Shallow Salt-Water Lagoon in the Altiplano
    (2024) Hartogensis, Oscar; Aguirre Correa, Francisca; Suárez Poch, Francisco Ignacio; Lobos Roco, Felipe Andrés; Ronda, Reinder; Vilà-Guerau de Arellano, Jordi
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    Midday Boundary-Layer Collapse in the Altiplano Desert: The Combined Effect of Advection and Subsidence
    (2023) Aguirre Correa, Francisca; De Arellano, Jordi Vila-Guerau; Ronda, Reinder; Lobos Roco, Felipe Andrés; Suárez Poch, Francisco Ignacio; Hartogensis, Oscar; CEDEUS (Chile)
    Observations in the Altiplano region of the Atacama Desert show that the atmospheric boundary layer (ABL) suddenly collapses at noon. This rapid decrease occurs simultaneously to the entrance of a thermally driven, regional flow that causes a rise in wind speed and a marked temperature decrease. We identify the main drivers that cause the observed ABL collapse by using a land-atmosphere model. The free atmosphere lapse rate and regional forcings, such as advection of mass and cold air as well as subsidence, are first estimated by combining observations from a comprehensive field campaign and a regional model. Then, to disentangle the ABL collapse, we perform a suite of numerical experiments with increasing level of complexity: from only considering local land-atmosphere interactions, to systematically including the regional contributions of mass advection, cold air advection, and subsidence. Our results show that non-local processes related to the arrival of the regional flow are the main factors explaining the boundary-layer collapse. The advection of a shallower boundary layer (approximate to -250 m h(-1) at noon) causes an immediate decrease in the ABL height (h) at midday. This occurs simultaneously with the arrival of a cold air mass, which reaches a strength of approximate to -4 Kh(-1) at 1400 LT. These two external forcings become dominant over entrainment and surface processes that warm the atmosphere and increase h. As a consequence, the ABL growth is capped during the afternoon. Finally, a wind divergence of approximate to 8 x 10(-5) s(-1) contributes to the collapse by causing subsidence motions over the ABL from 1200 LT onward. Our findings show the relevance of treating large and small-scale processes as a continuum to be able to understand the ABL dynamics.
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    Reprocessing scintillometer data altered by wind currents to describe evapotranspiration fluxes in a semi-arid region
    (2021) Aguirre Correa, Francisca; Suárez Poch, Francisco Ignacio; Pontificia Universidad Católica de Chile. Escuela de Ingeniería
    La evapotranspiración (ET) es un componente clave del ciclo hidrológico, siendo relevante para la gestión del agua en regiones áridas y semiáridas bajo un clima cambiante. La ET vincula los balances de agua y energía en forma de calor latente (LvE) liberado a la atmósfera. Sin embargo, la ET es difícil de medir, especialmente en campos heterogéneos donde la vegetación es escasa y donde los cultivos de regadío están rodeados de superficies heterogéneas que aportan energía adicional al sistema. Así, la ET no siempre es bien descrita en regiones áridas, siendo necesario incorporar técnicas novedosas para su medición. Últimamente, estudios han reportado buenos resultados obtenidos con el uso de escintilómetros. Funcionan mejor en regiones heterogéneas y a grandes escalas espaciales. Sin embargo, las señales de los escintilómetros pueden presentar contribuciones no deseadas que sobrestiman los flujos de calor. En este estudio, datos de escintilómetro alterados por corrientes de viento entregaron flujos de calor poco realistas y, por tanto, estos datos fueron reprocesados mediante un análisis espectral para eliminar contribuciones no deseadas de ruido electrónico, absorción y vibraciones del trípode. Tras una limpieza espectral, se calcularon los flujos de calor utilizando varios métodos: i) cierre del balance energético, ii) modelo de Hill, iii) modelo de Lüdi et al. y iv) modelo híbrido. Las estimaciones de flujo de calor sensible (H) concordaron bien con las obtenidas con un sistema Eddy Covariance (EC). Sin embargo, se encontraron diferencias considerables para el LvE (y, en consecuencia, la ET), al utilizar los distintos métodos. Las estimaciones de LvE de Lüdi et al. se aproximaron más a las obtenidas con el sistema EC, sobrestimándola en un ~14% con una pendiente de correlación de 1,07 y un coeficiente de determinación de 0,91. Además, se comprobó que el uso de diferentes funciones de similitud da lugar a más de un ±12% de diferencia en el LvE estimado. Para futuros trabajos se recomienda siempre aplicar la limpieza espectral, ya que mejora en gran medida los datos de escintilómetros, así como asegurar la estabilidad del trípode y la correcta alineación al realizar las mediciones.
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    Understanding Fog and Dew Dynamics for Assessing Non-Rainfall Water Potential Uses in the Atacama
    (2023) Lobos Roco, Felipe Andrés; Suárez Poch, Francisco Ignacio; Aguirre Correa, Francisca; Keim Vera, Klaus Kurt; Aguirre, Ignacio; Vargas Vásquez, Constanza; Abarca Paredes, Francisco Andrés; Ramírez Reyes, Carla; Escobar Moragas, Rodrigo; Osses, Pablo; Río López, Camilo del
    In (semi-)arid regions, harvesting fog and dew can become a complementary solution to traditional water supply. In the Atacama region, a territory of key and water-dependent economic activities, both fog and dew are driven by the advection of marine moisture from the Pacific. Still, little is described regarding the dynamics and water potential of these events. In this study, we analyze the spatiotemporal variability of fog and dew in the Atacama Desert to assess the potential of non-rainfall atmospheric water harvesting. Our research strategy combines three methods to achieve a comprehensive understanding of these phenomena: a satellite-spatial analysis of fog and low cloud frequencies; a thermodynamic characterization of the fog cloud vertical structure; and an observational analysis of fog and dew water collection. Our findings reveal that fog is a regular phenomenon in the area, occurring from 3% to 20% of the year. We estimate that fog cloud reaches 50 km inland and up to ~1100 m ASL, covering a vast territory where it can be harvested. Fog and dew represent 72% and 28% of the total collected atmospheric water (~0.2 L m-2 day-1). Both fog and dew represent a complementary natural water source with multiple uses for local industries.
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    Understanding inland fog and dew dynamics for assessing potential non-rainfall water use in the Atacama
    (2024) Lobos Roco, Felipe Andrés; Suárez Poch, Francisco Ignacio; Aguirre Correa, Francisca; Keim, K.; Aguirre, I.; Vargas Vásquez, Constanza; Abarca, F.; Ramírez Reyes, Carla; Escobar Moragas, Rodrigo; Osses, Pablo; Río López, Camilo del; CEDEUS (Chile)
    In (semi-)arid regions, harvesting fog and dew can become a complementary solution to traditional water supply. In the Atacama region, a territory of key and water-dependent economic activities, both fog and dew are driven by the advection of marine moisture from the Pacific. Still, little is described regarding the dynamics and water potential of these events. In this study, we analyze the spatiotemporal variability of fog and dew in the Atacama Desert to assess the potential of non-rainfall atmospheric water harvesting. Our research strategy combines three methods to achieve a comprehensive understanding of these phenomena: a satellite-spatial analysis of fog and low cloud frequencies; a thermodynamic characterization of the fog cloud vertical structure; and an observational analysis of fog and dew water collection. Our findings reveal that fog is a regular phenomenon in the area, occurring from 3% to 20% of the year. We estimate that fog cloud reaches 50 km inland and up to ∼1100 m ASL, covering a vast territory where it can be harvested. Fog and dew represent 72% and 28% of the total collected atmospheric water (∼0.2 L m−2 day−1). Both fog and dew represent a complementary natural water source with multiple uses for local industries.