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Fakultät für Biologie, Chemie und Geowissenschaften

Mikrometeorologie - Prof. Christoph Thomas

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Weak-wind flows in plant canopies


Von 07/2010 bis 12/2016

Schwerpunktleiter: Christoph Thomas
Mitarbeiter: Christoph Thomas, Lena Pfister, Laura Ehrnsperger, Tobias Wunder

Advanced Resolution Canopy FLow Observations (ARCFLO)


Sponsored by

National Science Foundation, CAREER Award 0955444


The project will study how air moves in plant canopies such as crops and forests where winds are usually relatively weak, and how it affects the transport of heat, water, and momentum. The research component includes new field observations across a large spectrum of sites with contrasting characteristics of canopy architecure and terrain including the OSU Botany & Plant Pathology Field lab, the HJ Andrews Experimental forest, and two AmeriFlux Sites in Oregon. The findings from this unique set of experiments will be the key step toward the long-term goal to develop a novel improved framework to describe the flow and its transport under weak-wind conditions for a continuous variation of overstory density and stratification. Observations will be made with a unique combination of new and classic micrometeorological techniques including optical fiber measurement of temperature structure (DTS), acoustic remote sensing (SODAR), ultrasonic anemometers, thermo-/ hygrometers, and laser-illuminated flow visualizations as illustrated in the schematic experimental setup.

Background, broader impacts

The level of scientific understanding of weak-wind transport is very limited, and commonly used forecast tools and mathematical formulations don't apply. This information is also needed to correctly predict the spread of pollutants or contaminants in nocturnal atmospheric conditions, and to more precisely estimate carbon sequestration and evapotranspiration rates from tall vegetation. The broader impacts of the project are improved formulations of surface fluxes for regional and large-scale weather and climate models, as well as dispersion and diffusion models. A set of practical recommendations for the applied flux community will be formulated to reduce uncertainties in carbon and energy budgets, and to better predict the water availability in forests. In addition to a graduate student, an Oregon K-12 high school teacher will be working with the PI through a partnership with the Oregon Natural Resources Education Program at OSU. The PI will also work with the Willamette National Forest to improve management decisions for fire fighting.

Publikationsliste dieses Schwerpunkts

Kleinknecht, GJ; Lintz, HE; Kruger, A; Niemeier, JJ; Salino-Hugg, MJ; Thomas, CK; Still, CJ; Kim, Y: Introducing a sensor to measure budburst and its environmental drivers, Frontiers in Plant Science, 6, 1-11 (2015), doi:10.3389/fpls.2015.00123
Vickers, D; Thomas, CK: Observations of the scale-dependent turbulence and evaluation of the flux--gradient relationship for sensible heat for a closed Douglas-fir canopy in very weak wind conditions, Atmospheric Chemistry and Physics, 14(18), 9665-9676 (2014), doi:10.5194/acp-14-9665-2014
Zeeman, MJ; Selker, JS; Thomas, CK: Near-surface motion in the nocturnal, stable boundary layer observed with fibre-optic distributed temperature sensing, Boundary-Layer Meterology, 154(2), 189-205 (2014), doi:10.1007/s10546-014-9972-9
Thomas, CK: Was, wenn wenig Wind weht?, Forum der Geoökologie(03/2014), 35-37 (2014)
Zeeman, MJ; Eugster, W; Thomas, CK: Concurrency of coherent structures and conditionally sampled daytime sub-canopy respiration, Boundary-Layer Meteorology, 146, 1-15 (2013), doi:10.1007/s10546-012-9745-2
Mahrt, L; Thomas, CK; Richardson, S; Seaman, N; Stauffer, D; Zeeman, MJ: Non-stationary generation of weak turbulence for very stable and weak-wind conditions, Boundary-Layer Meteorology, 147, 179-199 (2013), doi:10.1007/s10546-012-9782-x
Vickers, D; Thomas, CK: Some aspects of the turbulence kinetic energy and fluxes above and beneath a tall open pine forest canopy, Agricultural and Forest Meteorology, 181, 143-151 (2013), doi:10.1016/j.agrformet.2013.07.014
Thomas, CK; Martin, JG; Law, BE; Davis, K: Toward biologically meaningful net carbon exchange estimates for tall, dense canopies: multi-level eddy covariance observations and canopy coupling regimes in a mature Douglas-fir forest in Oregon, Agricultural and Forest Meteorology, 173, 14-27 (2013), doi:10.1016/j.agrformet.2013.01.001
Thomas, CK; Smoot, AR: An effective, economic, aspirated radiation shield for air temperature observations and its spatial gradients, J. Atmos. Ocean. Technol., 30, 526-537 (2013), doi:10.1175/JTECH-D-12-00044.1
Thomas, CK; Kennedy, AM; Selker, JS; Moretti, A; Schroth, MH; Smoot, AR; Tufillaro, NB; Zeeman, MJ: High-resolution fibre-optic temperature sensing: A new tool to study the two-dimensional structure of atmospheric surface layer flow, Boundary-Layer Meteorology, 142, 177-192 (2012), doi:10.1007/s10546-011-9672-7
Thomas, CK: Variability of subcanopy flow, temperature, and horizontal advection in moderately complex terrain, Boundary-Layer Meteorology, 139, 61-81 (2011), doi:10.1007/s10546-010-9578-9
Serafimovich, A; Thomas, C; Foken, T: Vertical and horizontal transport of energy and matter by coherent motions in a tall spruce canopy, Boundary-Layer Meteorology, 140, 429-451 (2011), doi:10.1007/s10546-011-9619-z -- Details