Bio-hydro-atmosphere interactions of





Organics &



Scope of study for BEACHON (click on picture to enlarge)

The BEACHON project conducted experimental and numerical research studies to enhance understanding of the roles of biogenic aerosols, nitrogen trace gases and oxidants in linking and regulating the carbon and water cycles. The BEACHON-RoMBAS field campaign was conducted in Woodland Park, Colorado, during the summer of 2011.

The Earth system has undergone extensive change during the last 60 years, with important implications for human health, resource management, ecosystem services and the environment. The ability to predict these changes and their impacts on time scales of months to a decade is becoming increasingly important. Key to improving the predictability of Earth system behavior over these time scales is an improved understanding of the coupling between water, energy and biogeochemical cycles in a multi-scale modeling framework. Robust predictions at these time scales require coordinated modeling, observations and process studies that explicitly address the coupled water, energy and biogeochemical cycles at multiple temporal and spatial scales.

Four Major Questions:


Nocturnal pooling of Carbon in the Mountains

Courtesy of J. Sun (click on picture to enlarge)


How do whole ecosystem exchanges regulate and link the terrestrial biogeochemical and water cycles, and how will they respond to changes in chemical, physical and biological variables?

  • What level of detail is required to accurately account for biosphere-atmosphere exchange processes in regional and global scale models?
  • How do atmosphere boundary layer structures affect trace gas and particle emission and transport?


How does biosphere-atmosphere exchange impact the intensity, frequency, and duration of precipitation, and how does changing precipitation drive gas and particle fluxes?

  • To what magnitude do biogenic Cloud Condensation Nucleus (CCN), Giant Cloud Condensation Nuclei (GCCN) and Ice Nuclei (IN) affect precipitation, clouds and associated radiative transfer in pristine and polluted regions?
  • How do spatial and temporal variations in hydro-climatic forcing regulate ecosystem-atmosphere exchange of water, energy, nutrients, gases and particles?


How do atmospheric oxidant and reactive carbon and nitrogen interactions influence biogeochemical cycling in a water-limited ecosystem?

  • What is the relative importance of carbon dioxide, ozone, nitrogen, and water in limiting ecosystem carbon uptake and release ?
  • How do alterations in the nitrogen cycle affect the carbon and water cycles, climate, and atmospheric trace gas distributions?


To what degree do land-use change and eco-disturbance affect biosphere-atmosphere exchange?

  • What are the critical thresholds that lead to large-scale destabilization of water and biogeochemical cycles?
  • Are current models adequate to capture critical thresholds (locally to globally)?

Methodology and Objectives

BEACHON-CHATS:  A classic micrometeorology experiment  augmented to evaluate novel sensing approaches for coupled Bio-hydro-atmosphere  (BHA) science.

BEACHON-CHATS: A classic micrometeorology experiment for coupled Bio-hydro-atmosphere science.
  • Long-term field measurements to characterize biosphere-hydrosphere-atmosphere exchanges and interactions at sites in water-limited areas.
  • Laboratory studies and airborne “whole-canopy” campaigns to examine processes that currently limit understanding of biosphere-hydrosphere-atmosphere interactions in water-limited ecosystems.
  • Development and use of novel observational instruments and platforms for quantifying regional and whole-canopy exchange of aerosols and trace gases. Examples include time-of-flight mass spectrometry, millimeter-wave radar, eye-safe aerosol and constituent lidars, and helicopter measurements.
  • Numerical simulations employing Large Eddy Simulation (LES), mesoscale, regional climate and global climate system models. Initially, process level simulations will be pursued within the WRF LES, WRF coupled with Chemistry (WRF-Chem) and mesoscale frameworks. As parameterizations are developed, refined or determined to be consistent with process-scale observations, these will be simplified as necessary and applied to the regional and global climate system model frameworks.


A major experimental focus is on measurement, interpretation and modeling of surface fluxes of energy, aerosols, CO2, water, and organic and nitrogen compounds. Investigations may also address other fundamental processes including: Atmospheric aerosol production and growth processes; oxidant and affected cloud processes; and the response of ecological, hydrological, and physiological processes to land-use change and ecological disturbances. While BEACHON currently focuses on water-limited ecosystems, through international partnerships, it will galvanize and participate in tropical rainforest studies and other regions that span a wide range of water availability.

The Long-Term Impact


Improve model representations of the bio-hydro-atmosphere interactions in water-limited regions based on improved understanding achieved from observations and diagnostic use of process-level models at the large eddy scale and mesoscale.

Develop a capability for accurately assessing the total environmental impact of land-use and ecological disturbances to inform land management decisions.

Initiate an international multidisciplinary network that will extend this research beyond the western U.S. and the sunset of this project

Program Lead - Contact

Dr. Alex Guenther


Phone: 303.497.1447    

Mailing Address: NCAR, P.O. Box 3000, Boulder, CO USA 80307-3000


Updated 26 October 2012.


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