Browsing by Author "Lobos Roco, Felipe"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Characterizing the influence of the marine stratocumulus cloud on the land fog at the Atacama Desert
    (2018) Lobos Roco, Felipe; Vila-Guerau de Arellano, Jordi; Pedruzo-Bagazgoitia, Xabier
  • Thumbnail Image
    Item
    Evaporation Driven by Atmospheric Boundary Layer Processes over a Shallow Saltwater Lagoon in the Altiplano
    Aguirre Correa, Francisca; Vilà-Guerau de Arellano, Jordi; Ronda, Reinder; Lobos Roco, Felipe; Suárez, Francisco; Hartogensis, Oscar
    Observations over a saltwater lagoon in the Altiplano show that evaporation E is triggered at noon, concurrent to the transition of a shallow, stable atmospheric boundary layer (ABL) into a deep mixed layer. We investigate the coupling between the ABL and E drivers using a land–atmosphere conceptual model, observations, and a regional model. Additionally, we analyze the ABL interaction with the aerodynamic and radiative components of evaporation using the Penman equation adapted to saltwater. Our results demonstrate that nonlocal processes are dominant in driving E. In the morning, the ABL is controlled by the local advection of warm air (∼5 K h−1), which results in a shallow (<350 m), stable ABL, with virtually no mixing and no E (<50 W m−2). The warm-air advection ultimately connects the ABL with the residual layer above, increasing the ABL height h by ∼1 km. At midday, a thermally driven regional flow arrives to the lagoon, which first advects a deeper ABL from the surrounding desert (∼1500 m h−1) that leads to an extra ∼700-m h increase. The regional flow also causes an increase in wind (∼12 m s−1) and an ABL collapse due to the entrance of cold air (∼−2 K h−1) with a shallower ABL (∼−350 m h−1). The turbulence produced by the wind decreases the aerodynamic resistance and mixes the water body releasing the energy previously stored in the lake. The ABL feedback on E through vapor pressure enables high evaporation values (∼450 W m−2 at 1430 LT). These results contribute to the understanding of E of water bodies in semiarid conditions and emphasize the importance of understanding ABL processes when describing evaporation drivers.
  • Thumbnail Image
    Item
    Spatial distribution and interannual variability of coastal fog and low clouds cover in the hyperarid Atacama Desert and implications for past and present Tillandsia landbeckii ecosystems
    (SPRINGER WIEN, 2021) del Rio, Camilo; Lobos Roco, Felipe; Latorre, Claudio; Koch, Marcus A.; Garcia, Juan Luis; Osses, Pablo; Lambert, Fabrice; Alfaro, Fernando; Siegmund, Alexander
    The hyperarid Atacama Desert coast receives scarce moisture inputs mainly from the Pacific Ocean in the form of marine advective fog. The collected moisture supports highly specialized ecosystems, where the bromeliad Tillandsia landbeckii is the dominant species. The fog and low clouds (FLCs) on which these ecosystems depend are affected in their interannual variability and spatial distribution by global phenomena, such as ENSO. Yet, there is a lack of understanding of how ENSO influences recent FLCs spatial changes and their interconnections and how these variations can affect existing Tillandsia stands. In this study, we analyze FLCs occurrence, its trends and the influence of ENSO on the interannual variations of FLCs presence by processing GOES satellite images (1995-2017). Our results show that ENSO exerts a significant influence over FLCs interannual variability in the Atacama at similar to 20 degrees S. Linear regression analyses reveal a relation between ENSO3.4 anomalies and FLCs with opposite seasonal effects depending on the ENSO phase. During summer (winter), the ENSO warm phase is associated with an increase (decrease) of the FLCs occurrence, whereas the opposite occurs during ENSO cool phases. In addition, the ONI Index explains up to similar to 50 and similar to 60% variance of the interannual FLCs presence in the T. landbeckii site during summer and winter, respectively. Finally, weak negative (positive) trends of FLCs presence are observed above (below) 1000 m a. s. l. These results have direct implications for understanding the present and past distribution of Tillandsia ecosystems under the extreme conditions characterizing our study area.