Abstract
Abstract. The Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen (BEACHON) project seeks to understand the feedbacks and inter-relationships between hydrology, biogenic emissions, carbon assimilation, aerosol properties, clouds and associated feedbacks within water-limited ecosystems. The Manitou Experimental Forest Observatory (MEFO) was established in 2008 by the National Center for Atmospheric Research to address many of the BEACHON research objectives, and it now provides a fixed field site with significant infrastructure. MEFO is a mountainous, semi-arid ponderosa pine-dominated forest site that is normally dominated by clean continental air but is periodically influenced by anthropogenic sources from Colorado Front Range cities. This article summarizes the past and ongoing research activities at the site, and highlights some of the significant findings that have resulted from these measurements. These activities include - soil property measurements; - hydrological studies; - measurements of high-frequency turbulence parameters; - eddy covariance flux measurements of water, energy, aerosols and carbon dioxide through the canopy; - determination of biogenic and anthropogenic volatile organic compound emissions and their influence on regional atmospheric chemistry; - aerosol number and mass distributions; - chemical speciation of aerosol particles; - characterization of ice and cloud condensation nuclei; - trace gas measurements; and - model simulations using coupled chemistry and meteorology. In addition to various long-term continuous measurements, three focused measurement campaigns with state-of-the-art instrumentation have taken place since the site was established, and two of these studies are the subjects of this special issue: BEACHON-ROCS (Rocky Mountain Organic Carbon Study, 2010) and BEACHON-RoMBAS (Rocky Mountain Biogenic Aerosol Study, 2011).
Highlights
1.1 MotivationDevelopment of Earth system models is driven by the need to improve the predictability of atmospheric chemical and physical processes over timescales ranging from minutes to decades
Thermal desorption chemical ionization mass spectrometer (TDCIMS) measurements during these nucleation events demonstrated that sub-20 nm particles were composed of ∼ 60 % sulfate by mass, whereas during non-event periods, sulfate contributed less than 40 % of the mass to these small particles (Cui et al, 2014)
The combination of these results suggests that secondary organic aerosol derived from biogenic emissions impact aerosol hygroscopicity and cloud condensation nuclei (CCN) number concentrations throughout the year
Summary
Development of Earth system models is driven by the need to improve the predictability of atmospheric chemical and physical processes over timescales ranging from minutes to decades. Rocky Mountain ecosystems are important for providing water and other resources in the western United States, but contain only a limited number of long-term monitoring sites This region is predominantly arid or semi-arid, resulting in biogeochemical cycles that are water limited. Networks has been identified by international research programs as a key need for advancing Earth system science (Guenther et al, 2011) To address these challenges, the BEACHON project in collaboration with the United States Department of Agriculture (USDA) Forest Service established the Manitou Experimental Forest Observatory (MEFO) in 2008, in an area representative of a middle-elevation (∼ 2000–2500 m a.s.l.), semiarid, ponderosa pine ecosystem that is common throughout the Rocky Mountain West, but not adequately characterized. More specific scientific results and publications can be found in the publication list (Table S2 in the Supplement) and within the individual articles as part of this special issue of Atmospheric Chemistry and Physics
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