Monitoring the chemical climate of the Mt. Mitchell State Park for evaluation of its impact on forest decline

V. K. Saxena, R. E. Stogner, A. H. Hendler, T. P. Defelice, R. J.Y. Yeh, N. H. Lin

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

We erected a 16.5m tall aluminium walk-up tower and instrumented it with an electronic weather station, cloud water collectors and ozone analyzers. Our observations during summer 1986 confirm that Mt. Mitchell has a high frequency of being immersed in clouds. Although the average pH of precipitation was about 4.4 the pH of cloud water ranged between 2.2-5.4. The pH of the cloud water was demonstrated to be a function of wind direction at the site. During early summer episodes, neutralization of the acidic anions (SO4= and NO3-) was not as effective as in the later summer episodes. During all cloud episodes, ozone concentration registered a dramatic decrease. The average minimum ozone concentration of about 63 ppb during the whole summer of 1986 was above the backgound level (50 ppb) in the United States. Diurnal ozone variation revealed a nocturnal maximum of about 75 ppb after sunset. This is contrary to conventional midday maximum in ozone concentration reported in the literature. Episodic excursions in ozone concentration equal to or exceeding 100 ppb level were found on 5 occasions. The maximum cloud water deposition rate, which is estimated using a micrometeorological model, is found to be 1.30 mm h-1. Ionic deposition due to direct cloud capture is found to be 2 to 5 times the deposition due to precipitation, and the evaporation associated with wind speeds as high as 15-18m s-1 realized during some episodes is pointed out to be of great significance regarding the canopy exposure. -from Authors

Original languageEnglish
Pages (from-to)92-109
Number of pages18
JournalTellus, Series B
Volume41 B
Issue number1
DOIs
StatePublished - 1989

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