To explore fog water harvesting potential in California, we conducted long-term measurements involving three types of mesh using standard fog collectors (SFC). Volumetric fog water measurements from SFCs and wind data were collected and recorded in 15-minute intervals over three summertime fog seasons (2014)(2015)(2016) at four California sites. SFCs were deployed with: standard 1.00 m 2 double-layer 35% shade coefficient Raschel; stainless steel mesh coated with the MIT-14 hydrophobic formulation; and FogHa-Tin, a German manufactured, 3-dimensional spacer fabric deployed in two orientations. Analysis of 3419 volumetric samples from all sites showed strong relationships between mesh efficiency and wind speed. Raschel mesh collected 160% more fog water than FogHa-Tin at wind speeds less than 1 m s -1 and 45% less for wind speeds greater than 5 m s -1 . MIT-14 coated stainless-steel mesh collected more fog water than Raschel mesh at all wind speeds. At low wind speeds of < 1 m s -1 the coated stainless steel mesh collected 3% more and at wind speeds of 4-5 m s -1 , it collected 41% more. FogHa-Tin collected 5% more fog water when the warp of the weave was oriented vertically, per manufacturer specification, than when the warp of the weave was oriented horizontally. Time series measurements of three distinct mesh across similar wind regimes revealed inconsistent lags in fog water collection and inconsistent performance. Since such differences occurred under similar wind-speed regimes, we conclude that other factors play important roles in mesh performance, including in-situ fog event and aerosol dynamics that affect droplet-size spectra and droplet-to-mesh surface interactions.

Fog deposition is a notable component of the water budget of herbaceous-shrub ecosystems on the central and southern coastal regions of California. This paper presents an analysis of fog water deposition rates and meteorological controls in Big Sur, California. Mesh-screen fog collectors were installed the Brazil Ranch weather station sites to measure fog water during the summer seasons of 2010 and 2011. Fog deposition occurred during 73% of days recorded in 2010 and 87% of days recorded in 2011. The daily average deposition rate was 2.29 L/m² in 2010 and 3.86 L/m² in 2011. The meteorological variables which had the greatest influence on prediction of fog deposition were wind speed, wind direction, and the dew-point depression (difference between air temperature and dew point). Based on these results, we hypothesize that high rates of summer fog deposition help sustain the productivity of California coastal vegetation through periods of low rainfall

Total mercury (HgT) and monomethyl mercury (MMHg) concentrations in fog collected from 4 locations in and around Monterey Bay, California during June‐August of 2011 were 10.7 ± 6.8 and 3.4 ± 3.8 ng L−1respectively. In contrast, mean HgT and MMHg concentrations in rain water from March‐June, 2011 were 1.8 ± 0.9 and 0.1 ± 0.04 ng L−1 respectively. Using estimates of fog water deposition from 6 sites in the region using a standard fog water collector (SFC), depositions of HgT and MMHg via fog were found to range from 42–4600 and 14–1500 ng m−2 y−1, which accounted for 7–42% of HgT and 61–99% of MMHg in total atmospheric deposition (fog, rain, and dry deposition), estimated for the coastal area. These initial measurements suggest that fog precipitation may constitute an important but previously overlooked input of MMHg to coastal environments. Preliminary comparisons of these data with associated chemical, meteorological and oceanic data suggest that biotically formed MMHg from coastal upwelling may contribute to the MMHg in fog water.

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Marine fog water samples were collected over two summers (2014)(2015) with active strand collectors (CASCC) at eight coastal sites from Humboldt to Monterey counties in California, USA, and on four ocean cruises along the California coastline in order to investigate mercury (Hg) cycling at the ocean-atmosphere-land interface. The mean concentration of monomethylmercury (MMHg) in fog water across terrestrial sites for both years was 1.6 ± 1.9 ng L -1 (<0.01-10.4 ng L -1 , N = 149), which corresponds to 5.7% (2.0-10.8%) of total Hg (HgT) in fog. Rain water samples from three sites had mean MMHg concentrations of 0.20 ± 0.12 ng L -1 (N = 5) corresponding to 1.4% of HgT. Fog water samples collected at sea had MMHg concentrations of 0.08 ± 0.15 ng L -1 (N = 14) corresponding to 0.4% of HgT. Significantly higher MMHg concentrations in fog were observed at terrestrial sites next to the ocean relative to a site 40 kilometers inland, and the mean difference was 1.6 ng L -1 . Using a rate constant for photo-demethylation of MMHg of -0.022 h -1 based on previous demethylation experiments and a coastal-inland fog transport time of 12 hours, a mean difference of only 0.5 ng L -1 of MMHg was predicted between coastal and inland sites, indicating other unknown source and/or sink pathways are important for MMHg in fog. Fog water deposition to a standard passive 1.00 m 2 fog collector at six terrestrial sites averaged 0.10 ± 0.07 L m -2 d -1, which was ∼2% of typical rainwater deposition in this area. Mean air-surface fog water fluxes of MMHg and HgT were then calculated to be 34 ± 40 ng m -2 y -1 and 546 ± 581 ng m -2 y -1 , respectively. These correspond to 33% and 13% of the rain fluxes, respectively.

Estimates of the variation with depth of both the speed and direction of near‐surface ocean currents within the top meter have been made using time series data collected from a dual‐frequency, high‐frequency radar located on the California coast, south of Monterey. Long‐term averages derived from this data set over 3 different years consistently revealed an expected reduction in the speed of the near‐surface current as a function of depth, consistent with a logarithmic vertical current profile. An unexpected and previously unmeasured clockwise rotation with increasing depth of the near‐surface current was also observed. Hypotheses are suggested for the apparent rotation.

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