A regional acidic cloud/fog water event in the eastern United States

Weathers, Kathleen C.; Likens, Gene E.; Bormann, Franz–Josef; Eaton, John S.; Bowden, William B.; Andersen, Janet L.; Cass, Donald A.; Galloway, James N.; Keene, W. C.; Kimball, Kenneth D.; Huth, Paul C.; Smiley, Daniel

doi:10.1038/319657a0

Cited by 98 publications

(38 citation statements)

References 12 publications

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“…Monthly cloud frequencies were determined by calculating the relative percent of all hourly LWC values equal to or greater than 0.05 g/m 3 . Any month with less than 70% valid LWC data was not considered representative of the monthly weather conditions and was not used in any analyses.…”

Section: Resultsmentioning

confidence: 99%

“…This threshold was established to have comparability with the MCCP measurements, which were made for the most part with Mallant Optical Cloud Detectors set at a threshold of approximately 0.04 g/m 3 . 21 The wind speed threshold of 2.5 m/sec was established because cloud water collection was erratic and inefficient at lower wind speeds.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Collection of cloud samples only when these criteria were met did not result in the loss of cloud frequency and cloud duration information because of the continuous data collection by the PVM. All LWC values of 0.05 g/m 3 or greater, independent of the type of cloud (i.e., precipitating or nonprecipitating), were used to calculate cloud frequency and cloud duration information. Cloud deposition estimates presented later may be biased by not sampling for the cloud deposition that occurs during contact with precipitating clouds.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…20 The forward scatter of the cloud droplets in the open air along the path is measured, translated, and expressed as grams of water per cubic meter (g/m 3 ) of air. This system was programmed so that the collector would be activated and projected out of the protective housing when threshold levels for LWC (Ն0.05 g/m 3 ), wind speed (Ͼ 2.5 m/sec), and ambient air temperature (Ն2°C) were reached. In addition, the system was activated only when no precipitation was present.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…[1][2][3][4][5] Cloud water droplets in clouds with origins in polluted areas contain high concentrations of acidic and other dissolved ions. 6 -8 A combination of factors, including high frequency of cloud immersion, high wind speeds, orographic enhancement of precipitation, and the large leaf areas of tree species typical of these environments, result in the flux of water and pollutants to these high-elevation ecosystems.…”

Section: Introductionmentioning

confidence: 99%

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Estimates of Cloud Water Deposition at Mountain Acid Deposition Program Sites in the Appalachian Mountains

Baumgardner

Isil

Lavery

et al. 2003

Journal of the Air & Waste Management Association

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Cloud water deposition was estimated at three high-elevation sites in the Appalachian Mountains of the eastern United States (Whiteface Mountain, NY; Whitetop Mountain, VA; and Clingman's Dome, TN) from 1994 through 1999 as part of the Mountain Acid Deposition Program (MADPro). This paper provides a summary of cloud water chemistry, cloud liquid water content, cloud frequency, estimates of cloud water deposition of sulfur and nitrogen species, and estimates of total deposition of sulfur and nitrogen at these sites. Other cloud studies in the Appalachians and their comparison to MADPro are also summarized. Whiteface Mountain exhibited the lowest mean and median concentrations of sulfur and nitrogen ions in cloud water, while Clingman's Dome exhibited the highest mean and median concentrations. This geographic gradient is partly an effect of the different meteorological conditions experienced at northern versus southern sites in addition to the difference in pollution content of air masses reaching the sites. All sites measured seasonal cloud water deposition rates of SO 4 2Ϫ greater than 50 kg/ha and NO 3 Ϫ rates of greater than 25 kg/ha. These high-elevation sites experienced additional deposition loading of SO 4 2Ϫ and NO 3

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Section: Resultsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Estimates of Cloud Water Deposition at Mountain Acid Deposition Program Sites in the Appalachian Mountains

Baumgardner

Isil

Lavery

et al. 2003

Journal of the Air & Waste Management Association

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Cloud water interception and element deposition differ largely between Norway spruce stands along an elevation transect in Harz Mountains, Germany

et al. 2014

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Cloud deposition can contribute a significant amount of water and elements to montane forests and thus play an important role in the hydrological and biochemical cycles of these ecosystems. However, elevational pattern in cloud and throughfall input to forest ecosystems and the associated chemical element fluxes are poorly understood so far. We studied gross precipitation, throughfall and cloud water deposition, and the associated fluxes of elements (N, P, Ca, K, Mg and Na) in five mature stands of Norway spruce along an elevation transect from lowlands to the alpine treeline (420-1060 m) at Mt Brocken (Harz Mountains, Germany). We tested the hypotheses that water input increases with elevation despite a reduction in intercepting plant surfaces, leading to higher inputs of nitrogen and other elements to high-elevation forests than in lower-elevation stands. Gross precipitation (only snow-free period) rose by 75% towards the treeline, but water input with throughfall increased by 350% because of a large increase in cloud water deposition (from 2 mm at 420 m to 160-200 mm at 1000 m in the study period). Element fluxes with gross precipitation were not uniformly related to elevation across all six elements. However, element fluxes via throughfall showed a positive correlation with elevation for all elements. Thus, the upper montane spruce forests received 50-150% higher atmospheric inputs of base cations and inorganic N and~200% higher P inputs than lower-elevation forests. We conclude that elevation does have a large influence on the atmospheric water and element inputs in temperate mountain forests. N ti = total inorganic nitrogen. Significant correlations (p < 0·05) are indicated by bold numbers. N = 5 for every element. Italic numbers indicate simple non-linear regressions; all other regressions are linear.

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Limitations to Intellectual Progress in Ecosystem Science

Likens¹

1998

Successes, Limitations, and Frontiers in Ecosystem Science

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A regional acidic cloud/fog water event in the eastern United States

Cited by 98 publications

References 12 publications

Estimates of Cloud Water Deposition at Mountain Acid Deposition Program Sites in the Appalachian Mountains

Estimates of Cloud Water Deposition at Mountain Acid Deposition Program Sites in the Appalachian Mountains

Cloud water interception and element deposition differ largely between Norway spruce stands along an elevation transect in Harz Mountains, Germany

Limitations to Intellectual Progress in Ecosystem Science

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