A Multiscale and Multidisciplinary Investigation Of Ecosystem–Atmosphere CO<sub>2</sub> Exchange Over the Rocky Mountains of Colorado

Sun, Jielun; Oncley, Steven; Burns, Sean P.; Stephens, Britton B.; Lenschow, Donald H.; Campos, T.; Monson, Russell K.; Schimel, David; Sacks, William J.; Wekker, Stephan F. J. De; Lai, Chun‐Ta; Lamb, Brian; Ojima, Dennis S.; Ellsworth, Patrick Z.; Sternberg, L. O.; Zhong, Sharon; Clements, Craig B.; Moore, David J. P.; Anderson, Dean E.; Watt, A.; Hu, Jia; Tschudi, M. A.; Aulenbach, S.; Allwine, E.; Coons, T.

doi:10.1175/2009bams2733.1

Cited by 31 publications

(29 citation statements)

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“…As part of CME04, the National Center for Atmospheric Research (NCAR) Earth Observing Laboratory (EOL) Integrated Surface Flux Facility (ISFF) group deployed three towers in a subalpine forest to supplement the existing University of Colorado AmeriFlux tower (NWT) and the U.S. Geological Survey (USGS) tower (Oncley 2004;Sun et al 2010). A detailed description of the long-term NWT measurements (40 • 1 N, 105 • 32 W, 3050 m elevation) can be found in Monson et al (2002) and Turnipseed et al (2002Turnipseed et al ( , 2003.…”

Section: Site Descriptionmentioning

confidence: 99%

“…Our study examines the effect of stability on the three-dimensional wind fields (sonic anemometers) and vertical differences of air temperature T a , specific humidity q, and CO 2 dry air mole fraction χ c measured during the 2004 Carbon in the Mountains Experiment (CME04, Sun et al 2010). CME04 took place in a subalpine forest below Niwot Ridge, Colorado, approximately 8 km east of the Continental Divide (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Atmospheric Stability Effects on Wind Fields and Scalar Mixing Within and Just Above a Subalpine Forest in Sloping Terrain

Burns

Sun

Lenschow

et al. 2010

Boundary-Layer Meteorol

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Air temperature T a , specific humidity q, CO 2 mole fraction χ c , and three-dimensional winds were measured in mountainous terrain from five tall towers within a 1 km region encompassing a wide range of canopy densities. The measurements were sorted by a bulk Richardson number Ri b . For stable conditions, we found vertical scalar differences developed over a "transition" region between 0.05 < Ri b < 0.5. For strongly stable conditions (Ri b > 1), the vertical scalar differences reached a maximum and remained fairly constant with increasing stability. The relationships q and χ c have with Ri b are explained by considering their sources and sinks. For winds, the strong momentum absorption in the upper canopy allows the canopy sublayer to be influenced by pressure gradient forces and terrain effects that lead to complex subcanopy flow patterns. At the dense-canopy sites, soil respiration coupled with wind-sheltering resulted in CO 2 near the ground being 5-7 µmol mol −1 larger than aloft, even with strong above-canopy winds (near-neutral conditions). We found Ri b -binning to be a useful tool for evaluating vertical scalar mixing; however, additional information (e.g., pressure gradients, detailed vegetation/topography, etc.) is needed to fully explain the subcanopy wind patterns. Implications of our results for CO 2 advection over heterogenous, complex terrain are discussed.

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Section: Site Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Atmospheric Stability Effects on Wind Fields and Scalar Mixing Within and Just Above a Subalpine Forest in Sloping Terrain

Burns

Sun

Lenschow

et al. 2010

Boundary-Layer Meteorol

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“…By demonstrating that "the effects of meso-scale transport such as mountain-valley circulations and mountain-wave activities on atmospheric CO 2 distributions are reproduced remarkably well in the highresolution models" they indirectly confirm the importance of these exchange processes in mountains terrain. Sun et al (2010), in a multi-scale and multi-disciplinary study using a wealth of different observational and modeling techniques, investigated the processes influencing the regional CO 2 budget over the Rocky Mountains (CO). Within the mountain boundary layer, CO 2 was found to be transported effectively by drainage (nighttime) and up-slope flows thereby largely affecting the local net ecosystem exchange at one of the rare mountainous "flux tower sites."…”

Section: Mass Exchangementioning

confidence: 99%

On the Vertical Exchange of Heat, Mass, and Momentum Over Complex, Mountainous Terrain

et al. 2015

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The role of the atmospheric boundary layer (ABL) in the atmosphere-climate system is the exchange of heat, mass, and momentum between "the earth's surface" and the atmosphere. Traditionally, it is understood that turbulent transport is responsible for this exchange and hence the understanding and physical description of the turbulence structure of the boundary layer is key to assess the effectiveness of earth-atmosphere exchange (EAE). This understanding is rooted in the (implicit) assumption of a scale separation or spectral gap between turbulence and mean atmospheric motions, which in turn leads to the assumption of a horizontally homogeneous and flat (HHF) surface as a reference, for which both physical understanding and model parameterizations have successfully been developed over the years. Over mountainous terrain, however, the ABL is generically inhomogeneous due to both thermal (radiative) and dynamic forcing. This inhomogeneity leads to meso-scale and even sub-meso-scale flows such as slope and valley winds or wake effects. It is argued here that these (sub)meso-scale motions can significantly contribute to the vertical structure of the boundary layer and hence vertical exchange of heat and mass between the surface and the atmosphere. If model grid resolution is not high enough the latter will have to be parameterized (in a similar fashion as gravity wave drag (GWD) parameterizations take into account the momentum transport due to gravity waves in large-scale models). In this contribution we summarize the available evidence of the contribution of (sub)meso-scale motions to vertical exchange in mountainous terrain from observational and numerical modeling studies. In particular, a number of recent simulation studies using idealized topography will be summarized and put into perspective-so as to identify possible limitations and areas of necessary future research.

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“…, Sun et al. ). The evaluation of correlative relationships through the iterative combination of models and data (Luo et al.…”

Section: Design Criteriamentioning

confidence: 99%

The terrestrial organism and biogeochemistry spatial sampling design for the National Ecological Observatory Network

Barnett

Duffy²,

Schimel

et al. 2019

Ecosphere

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The National Ecological Observatory Network (NEON) seeks to facilitate ecological prediction at a continental scale by measuring processes that drive change and responses at sites across the United States for thirty years. The spatial distribution of observations of terrestrial organisms and soil within NEON sites is determined according to a “design‐based” sample design that relies on the randomization of sampling locations. Development of the sample design was guided by high‐level NEON objectives and the multitude of data products that will be subjected to numerous analytical approaches to address the causes and consequences of ecological change. A requirement framework permeates the NEON design, ensuring traceability from each facet of the design to the high‐level requirements that make the NEON mission statement actionable. Requirements were developed for the terrestrial sample design to guide the key components of the design: Randomizing the sample locations ensures the unbiased collection of data, is appropriate for organisms and soil, and provides data suitable for a variety of analyses. Stratification increases efficiency and allows sampling to focus on those parts of the landscape measured by other NEON observation platforms. Attention to the sample size and spatial plot allocation ensures that data products will be sufficient to inform questions asked of the data and the NEON objectives. Establishing a framework with the capacity for re‐evaluate and design iteration allows for adaption to unexpected challenges and optimization of the sample design based on early data returns. The utility of the NEON sampling design is highlighted by its application across terrestrial systems. The data generated from this unique design will be used to quantify patterns in: the abundance and diversity of small mammals, breeding birds, insects, and soil microbes; vegetation structure, biomass, productivity, and diversity; and soil biogeochemistry.

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A Multiscale and Multidisciplinary Investigation Of Ecosystem–Atmosphere CO₂ Exchange Over the Rocky Mountains of Colorado

Cited by 31 publications

References 50 publications

Atmospheric Stability Effects on Wind Fields and Scalar Mixing Within and Just Above a Subalpine Forest in Sloping Terrain

Atmospheric Stability Effects on Wind Fields and Scalar Mixing Within and Just Above a Subalpine Forest in Sloping Terrain

On the Vertical Exchange of Heat, Mass, and Momentum Over Complex, Mountainous Terrain

The terrestrial organism and biogeochemistry spatial sampling design for the National Ecological Observatory Network

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A Multiscale and Multidisciplinary Investigation Of Ecosystem–Atmosphere CO2 Exchange Over the Rocky Mountains of Colorado

Cited by 31 publications

References 50 publications

Atmospheric Stability Effects on Wind Fields and Scalar Mixing Within and Just Above a Subalpine Forest in Sloping Terrain

Atmospheric Stability Effects on Wind Fields and Scalar Mixing Within and Just Above a Subalpine Forest in Sloping Terrain

On the Vertical Exchange of Heat, Mass, and Momentum Over Complex, Mountainous Terrain

The terrestrial organism and biogeochemistry spatial sampling design for the National Ecological Observatory Network

Contact Info

Product

Resources

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A Multiscale and Multidisciplinary Investigation Of Ecosystem–Atmosphere CO₂ Exchange Over the Rocky Mountains of Colorado