Browsing by Author "Lobos Roco, Felipe Andrés"
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- ItemA Water Balance Approach to Estimate Fog Water Contribution to a Relict Forest in the Coastal Semi-Arid Region in Central Chile(2024) Pacheco Canales, Valentina J.; Lobos Roco, Felipe Andrés; Vicuña Díaz, Sebastián; Suárez Poch, Francisco Ignacio; Río López, Camilo del; Gaxiola Alcantar, AuroraThe marine fog presence along Chile’s western coast, in the semi-arid and Mediterranean region, influences coastal vegetation patterns and constitutes a significant yet underestimated water source for basin water balance. While studies suggest that south-westerly winds transport marine fog inland, serving as a vital water source for coastal vegetation and relict forests, our understanding of fog dynamics in this context remains limited. Therefore, the aim of this study is to analyze coastal fog in the coast of the semi-arid and mediterranean region in central Chile addressing the temporal distribution of its frequency, liquid water content and water collection in relation to the presence of relict forests. This study is centered in a relict forest located in the semi-arid coastal Chile uphill 3.5 km far from the coast with an altitude of 650 meters (lat: -32.2°/long: -71.5°). This forest, dominated by Aextoxicon punctatum survives on less than 200 mm of annual precipitation which implies fog water is a critical water input. Our methodological approach is a water balance analysis tailored for fog-related water contributions, the balance considers precipitation, evapotranspiration (ET), soil accumulation, and fog input across various scales: from individual trees to the entire mountainous ecosystem. Specific methods for fog characterization, forest assessment, and fog capture efficiency are developed, incorporating factors such as forest characteristics and vertical variability. Our findings reveal that fog recurs 17% of the time and contributes up to 75% to the forest’s water evapotranspiration. Furthermore, it was estimated that forests can capture up to 10.5% of the available fog in the air. Considering soil moisture sensor data collected in the study area it appears that the captured fog does not penetrate deep into the soil and does not generate runoff from the forest area. Based on a sensitivity analysis we explored how forest’s fog capture efficiency varies with elevation, collection area (leaf area index), and evapotranspiration. These results underscore the importance of fog water as a vital water source for vegetation and emphasize the need for incorporating fog water inputs into broader assessments for improved water resource predictions and ecosystem conservation.
- ItemEvaporation 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
- ItemMidday 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.
- ItemSynoptic control of the spatiotemporal variability of fog and low clouds under ENSO phenomena along the Chilean coast (17°-36° S)(2024) Espinoza Escobedo, Vicente Patricio; Lobos Roco, Felipe Andrés; Del Rio López, CamiloThe northern and central coasts of Chile have an extensive semi-permanent layer of stratocumulus clouds that produce fog on land, a crucial resource for water-stressed areas. This study examines the spatio-temporal variability of fog and low clouds (FLC) across four climatic zones (17°S-36°S) characterized by arid conditions. Our analysis aims to elucidate the relationship between FLC patterns and the El Niño-Southern Oscillation (ENSO) phenomenon based on 25 years (1998–2022) of GOES satellite images. The variability of FLC shows a marked, although spatially asymmetric, seasonal cycle, with a subtle positive trend in the long-term. Our results suggest that the presence of FLC is controlled by the strength of the thermal inversion (correlation coefficient, r = 0.7), which, in turn, depends on the sea surface temperature (SST) and the subsidence. Specifically, FLC patterns are controlled by SST in the north (r = −0.9) and by subsidence intensity in the south (r = 0.9). Furthermore, our analysis indicates a potential link between ENSO and FLC, which alters the SST-subsidence equilibrium. At 20°S, warm phases of ENSO lead to increased FLC during the summer and decreased FLC during the winter. Conversely, at 30°S, warm phases result in decreased FLC during the summer and increased FLC during the winter. However, during cold phases, this trend is reversed. At 20°S, FLC decreases in summer and increases in winter, while at 30°S, FLC increases in summer and decreases in winter. In summary, our study offers a novel perspective on understanding the large-scale dynamics associated with FLC frequency along the central and northern coasts of Chile, including FLC underlying mechanisms and the long-term influence exerted by ENSO on the phenomenon.
- ItemUnderstanding 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 delIn (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.
- ItemUnderstanding 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.