Atmospheric Chemistry Measurements at Whiteface Mountain, NY: Cloud Water Chemistry, Precipitation Chemistry, and Particulate Matter

Abstract

Long-term records of condensed-phase chemical data are presented from the Adirondack Mountain region of northern New York, USA. These data records are particularly valuable due to the combinations of aerosol, cloud, and precipitation measurements. Objectives of the research and this overview paper include the evaluation of emission reductions of regulated air pollutants and the observed effects on measured deposition, as well as the implications of changing pollutant concentration levels on human health and climate. Summer season cloud chemistry and year-round wet deposition and particulate matter data from two stations on Whiteface Mountain are presented to highlight some of the research and monitoring activities at this mountain location. Clear decreases in the anion concentrations and increases in pH over the past two decades have been observed in cloud and precipitation results. Large decreases in aerosol sulfate (> 80%) and aerosol optical black carbon (> 60%) have been observed for these species over the nearly 40 year summit observatory data record for these measurements, and decreases in PM 2.5 mass, sulfate, nitrate, and ammonium have also been recorded over the shorter 15 year period of measurement at the Marble Mountain Lodge level. The studies cited here highlight some of the past successes of air pollution regulation under the Clean Air Act and Amendments and pave the way for future progress in reducing air pollution.

Biogenic, urban, and wildfire influences on the molecular composition of dissolved organic compounds in cloud water

“…1). The average pH of the cloud water samples was 4.6 ± 0.7 (95 % confidence interval), reflective of increasing cloud water pH at the site over the past several decades due to reductions in SO 2 and NO x emissions (Schwab et al, 2016a). The average O : C ratio of the high molecular weight negative ions was 0.505 ± 0.004.…”

“…It is important to note that the molecular composition of the cloud water reflects both the precursor aerosol and any aqueous-phase processing that occurred within the cloud droplets, as well as within the aqueous aerosol prior to cloud droplet activation and following cloud droplet evaporation. An in-depth summary of Whiteface Mountain cloud water studies has been published elsewhere (Schwab et al, 2016a). Whiteface Mountain cloud water is more acidic than rainwater, with higher sulfate and nitrate concentrations (Aleksic et al, 2009), which are attributed to fossil fuel combustion (Dukett et al, 2011).…”

Atmospheric Science Research at Whiteface Mountain, NY: Site Description and History

“…This stability of expected conditions makes possible a wide range of scientific operations, some of which may require years and for which evaluation of successive changes, and those of contrasting influences is desirable" (Falconer and Barry, 1963). The studies described here and in the companion papers Schwab et al, 2016) highlight some of the fruits of the scientific activity made possible in part by conditions referred to above.…”

Overview of the Special Issue “Selected Papers from the 2nd Atmospheric Chemistry and Physics at Mountain Sites Symposium”

“…Schwab et al (2016a, b) and Brandt et al (2016) are three companion papers describing measurements at Whiteface Mountain in the Andirondack Mountain region in northern New York. Schwab et al (2016a) presents a historical overview of the site and its measurements, making the case for the utility of long-term monitoring while the other two papers provide more detailed findings about the aerosol, cloud, and precipitation measurements (Schwab et al, 2016b) and ozone and trace gases (Brandt et al, 2016). In particular, both the aerosol and gas phase measurements collected over a period of 40 years at Whiteface Mountain highlight the past success of air pollution regulation under the U.S. Clean Air Act and Amendments and pave the way for future progress in reducing air pollution.…”