OPEN ACCESS

Articles online

A Low Cost System for Detecting Fog Events and Triggering an Active Fog Water Collector

Category: Further development of activities and strategies towards collection fog for freshwater production

Volume: 18 | Issue: 1 | Pages: 214-233
DOI: 10.4209/aaqr.2016.11.0508
PDF | RIS | BibTeX

Peter Weiss-Penzias 1, Daniel Fernandez2, Robert Moranville1, Chad Saltikov1

  • 1 University of California, Santa Cruz, CA 95064, USA
  • 2 California State University, Monterey Bay, Marina, CA 93933, USA

Highlights

A moisture detection system for activating a fog water collector is described.
29 fog water samples were collected during the summer of 2016 in Santa Cruz, CA.
On average the system was triggered 4.5 ± 3.3 hours after visibility reduction.
In previous years a relative humidity-only trigger method was employed.
Monomethylmercury concentrations in fog were independent of sampler trigger method.


Abstract

A simple method of activating the Caltech Active Strand Cloud-water Collector (CASCC) is described. This system detected the onset of wet deposition events associated with the advection of marine stratus clouds using an optical rain sensor (ORS) and a standard passive fog collector (SFC) in combination with a relative humidity threshold. The system was deployed on a rooftop between May 10 and September 20, 2016 (134 days) at the University of California, Santa Cruz, six km from Pacific Ocean, at 240 m elevation. Twenty-nine fog water samples (daily mean volume = 174 ± 71 mL) were collected for the purposes of quantifying the concentration of monomethylmercury (MMHg) and its possible marine origins. For 20 days during the study, a visibility sensor (VS) was collocated with the ORS and both sensors detected 7 fog events. The ORS detected 2 additional marine stratus drizzle events missed by the VS. The start time of the events detected by the ORS was delayed relative to the onset of visibility reduction in 6 of 7 events by 4.5 ± 3.3 hours. Low wind speeds at night at this location limited the wet deposition to the SFC. Average CASCC sampling time during these events was 6.2 ± 2.8 hours and 4 liquid samples were obtained (80 to > 275 mL). As a comparison, fog water collections at UCSC during the fog seasons of 2014 and 2015 yielded 35 and 12 samples, respectively using a trigger based on relative humidity (RH) and sampling times of > 12 h per day. The main benefit of triggering with the ORS in 2016 was to cut in half the sampling time without loss of sample collection volume. Mean MMHg concentrations between the 3 years were not significantly different suggesting that the SFC/ORS triggering system is appropriate for use at multiple fog collection sites simultaneously.

Keywords

Fog water collector Activation mechanism Visibility Moisture detection Deposition Mercury


Related Article

Fog Water Collection Effectiveness: Mesh Intercomparisons

Daniel M. Fernandez , Alicia Torregrosa, Peter S. Weiss-Penzias, Bong June Zhang, Deckard Sorensen, Robert E. Cohen, Gareth H. McKinley, Justin Kleingartner, Andrew Oliphant, Matthew Bowman
Volume: 18 | Issue: 1 | Pages: 270-283
DOI: 10.4209/aaqr.2017.01.0040
PDF

Testing Water Yield, Efficiency of Different Meshes and Water Quality with a Novel Fog Collector for High Wind Speeds

Christian Schunk , Peter Trautwein, Herbert Hruschka, Ernst Frost, Leslie Dodson, Aissa Derhem, Jamila Bargach, Annette Menzel
Volume: 18 | Issue: 1 | Pages: 240-253
DOI: 10.4209/aaqr.2016.12.0528
PDF | Supplemental material

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

Lukas W. Lehnert , Boris Thies, Katja Trachte, Sebastian Achilles, Pablo Osses, Karen Baumann, Jakob Schmidt, Elena Samolov, Patrick Jung, Peter Leinweber, Ulf Karsten, Burkhard Büdel, Jörg Bendix
Volume: 18 | Issue: 1 | Pages: 254-269
DOI: 10.4209/aaqr.2017.01.0021
PDF

Simplified Modeling and Analysis of the Fog Water Harvesting System in the Asir Region of the Kingdom of Saudi Arabia

Palanichamy Gandhidasan , Habib I. Abualhamayel, Faheemuddin Patel
Volume: 18 | Issue: 1 | Pages: 200-213
DOI: 10.4209/aaqr.2016.11.0481
PDF
;