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A Case Study on Fog/Low Stratus Occurrence at Las Lomitas, Atacama Desert (Chile) as a Water Source for Biological Soil Crusts

Category: Others

Accepted Manuscripts
DOI: 10.4209/aaqr.2017.01.0021
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Lukas W. Lehnert 1, Boris Thies1, Katja Trachte1,2, Sebastian Achilles1, Pablo Osses3, Karen Baumann4, Jakob Schmidt1, Elena Samolov5, Patrick Jung6, Peter Leinweber4, Ulf Karsten5, Burkhard Büdel6, Jörg Bendix1

  • 1 Faculty of Geography, Philipps-University of Marburg, 35037 Marburg, Germany
  • 2 Department of Geography, Ruhr-University of Bochum, 44780 Bochum, Germany
  • 3 Instituto de Geografia, Pontificia Universidad Catolica de Chile, Santiago de Chile, Chile
  • 4 Faculty of Agricultural and Environmental Sciences, Soil Science, Rostock University, 18051 Rostock, Germany
  • 5 Institute of Biological Sciences, Applied Ecology and Phycology, Rostock University, 18051 Rostock, Germany
  • 6 Plant Ecology and Systematics, University of Kaiserslautern, 67663 Kaiserslautern, Germany

Highlights

Atacama: Fog detection by in situ measurements, remote sensing & numerical modeling.
High fog water fluxes during small-scale orographic fog events in austral summer.
Proposal of a high resolution fog retrieval for the Atacama Desert.


Abstract

The Atacama Desert is well known for the high occurrence of large-scale fog (spatial extents: hundreds of kilometers) emerging as low stratus (LST) decks over the Pacific Ocean. By contrast, the small-scale and heterogeneous occurrence of small-scale fog (hundreds of meters) particularly during summers is widely unconsidered. However, these events are important for the local vegetation and particularly for the biological soil crusts (BSC) that are widely distributed in this extreme ecosystem. Consequently, a case study in a typical fog oasis in the Pan de Azúcar National Park was conducted to test the feasibility combining field measurements, drone profiling, remote sensing and numerical modeling (i) to investigate fog-type specific differences regarding dynamics, physical properties and formation, (ii) to test the applicability of remote sensing technology for fog monitoring based on existing low-resolution and a proposed new high-resolution product and (iii) to estimate the related fog water input to BSCs. Two types of fog were observed. The well-known fog/LST deck emerging from the Pacific Ocean with high water path and large spatial extent was the first type. Fog of the second type was patchier, small-scale and not necessarily connected to the LST over the ocean. Instead, fog formation of the second type was related to thermal breeze systems, which produced shallow clouds containing less water than those of type 1. In general, such small-scale fog events were not captured well by existing remote sensing products but could be detected with the proposed new high-resolution product which provided promising results. Both fog types were important water resources for the BSCs, with approximately 8% to 24% of the fog water flux available to the BSCs at the surface. The results indicated the feasibility of the proposed methods’ pool to estimate the water budget of BSCs with a high spatial resolution in the future.

Keywords

Orographic fog Landsat WRF-modeling Biological soil crusts Vertical fog droplet spectra


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Accepted Manuscripts
DOI: 10.4209/aaqr.2016.12.0528
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