Publications

Publications Found: 26
Relationship Of Area-Averaged Carbon Dioxide And Water Vapour Fluxes To Atmospheric Variables
Mahrt, L., Vickers, D.

Area-averaged fluxes are constructed from a combination of aircraft and tower data collected during BOREAS. The averaging area includes both conifer and deciduous forests, wetlands, burned areas and bodies of water. The area-averaged water vapour flux is closely related …


Journal: Agricultural And Forest Meteorology, Volume 112 (3-4): 195-202 (2002), ISBN . DOI: 10.1016/s0168-1923(02)00079-5 Sites: CA-Fen, CA-Oas, CA-Obs, CA-Ojp, CA-SJ3

Similarity Theory For Local And Spatially Averaged Momentum Fluxes
Nakamura, R., Mahrt, L.

Tower and aircraft data from a number of field studies are analyzed to: (1) estimate the roughness lengths for local and area-averaged momentum fluxes over various surface types; (2) examine the applicability of the ψ-stability formulations of Paulson and Dyer for momentum fluxes; (3) investigate the possibility …


Journal: Agricultural And Forest Meteorology, Volume 108 (4): 265-279 (2001), ISBN . DOI: 10.1016/s0168-1923(01)00250-7 Sites: CA-Man, CA-Oas, CA-Obs, CA-Ojp, CA-SJ3

On Measuring And Modeling Energy Fluxes Above The Floor Of A Homogeneous And Heterogeneous Conifer Forest
Baldocchi, D. D., Law, B. E., Anthoni, P. M.

Information on mass and energy exchange at the soil surface under vegetation is a critical component of micrometeorological, climate, biogeochemical and hydrological models. Under sparse boreal and western conifer forests as much as 50% of incident solar energy reaches the soil surface. How this energy is partitioned into …


Journal: Agricultural And Forest Meteorology, Volume 102 (2-3): 187-206 (2000), ISBN . DOI: 10.1016/s0168-1923(00)00098-8 Sites: CA-Ojp, US-Me4

Remote Sensing Of Photosynthetic-Light-Use Efficiency Of Boreal Forest
Nichol, C. J., Huemmrich, K. F., Black, T., Jarvis, P. G., Walthall, C. L., Grace, J., Hall, F. G.

Using a helicopter-mounted portable spectroradiometer and continuous eddy covariance data we were able to evaluate the photochemical reflectance index (PRI) as an indicator of canopy photosynthetic light-use efficiency (LUE) in four boreal forest species during the Boreal …


Journal: Agricultural And Forest Meteorology, Volume 101 (2-3): 131-142 (2000), ISBN . DOI: 10.1016/s0168-1923(99)00167-7 Sites: CA-Man, CA-Oas, CA-Obs, CA-Ojp

Characterization Of Radiation Regimes In Nonrandom Forest Canopies: Theory, Measurements, And A Simplified Modeling Approach
Kucharik, C. J., Norman, J. M., Gower, S. T.
We used field measurements and Monte Carlo simulations of canopy gap-size distribution and gap fraction to examine how beam radiation interacts with clumped boreal forest canopies of aspen (Populus tremuloides Michx.), black spruce (Picea mariana (Mill.) B.S.P.) and jack pine (Pinus …


Journal: Tree Physiology, Volume 19 (11): 695-706 (1999), ISBN . DOI: 10.1093/treephys/19.11.695 Sites: CA-Man, CA-Obs, CA-Ojp

Structure Analysis And Classification Of Boreal Forests Using Airborne Hyperspectral BRDF Data From ASAS
Sandmeier, S., Deering, D.

A new approach is presented for deriving vegetation canopy structural characteristics from hyperspectral bidirectional reflectance distribution function (BRDF) data. The methodology is based on the relationship between spectral variability of BRDF effects and canopy geometry. …


Journal: Remote Sensing Of Environment, Volume 69 (3): 281-295 (1999), ISBN . DOI: 10.1016/s0034-4257(99)00032-2 Sites: CA-Obs, CA-Ojp

Modeling BRFAnd Radiation Regime Of Boreal And Tropical Forests
Gastellu-Etchegorry, J., Guillevic, P., Zagolski, F., Demarez, V., Trichon, V., Deering, D., Leroy, M.

Monitoring of forest evolution and functioning with remote sensing depends on canopy BRF (bidirectional reflectance factor) sensitivity to biophysical parameters and to canopy PAR (photosynthetically active radiation) regime. Here, we study the canopy BRF of a tropical (Sumatra) …


Journal: Remote Sensing Of Environment, Volume 68 (3): 281-316 (1999), ISBN . DOI: 10.1016/s0034-4257(98)00119-9 Sites: CA-Oas, CA-Obs, CA-Ojp

Measurements Of PAR Transmittance Within Boreal Forest Stands During BOREAS
Roujean, J.

This paper shows the results of solar flux measurements routinely collected within boreal conifer forests during BOREAS 1994. Such vegetation have open canopies with a high level of clumping and covered by crowns which yields strong directional effects on the spectral hemispherical …


Journal: Agricultural And Forest Meteorology, Volume 93 (1): 1-6 (1999), ISBN . DOI: 10.1016/s0168-1923(98)00110-5 Sites: CA-Obs, CA-Ojp

Growth And Maintenance Respiration Rates Of Aspen, Black Spruce And Jack Pine Stems At Northern And Southern BOREAS Sites
Lavigne, M. B., Ryan, M. G.

We measured stem respiration rates during and after the 1994 growing season of three common boreal tree species at sites near the northern and southern boundaries of the closed-canopy boreal forest in central Canada. The growth respiration coefficient (rg; carbon efflux per μmole of carbon incorporated in structural …


Journal: Tree Physiology, Volume 17 (8-9): 543-551 (1997), ISBN . DOI: 10.1093/treephys/17.8-9.543 Sites: CA-Man, CA-Oas, CA-Obs, CA-Ojp

Vertical Gradients In Photosynthetic Gas Exchange Characteristics And Refixation Of Respired CO2 Within Boreal Forest Canopies
Brooks, J. R., Flanagan, L. B., Varney, G. T., Ehleringer, J. R.

We compared vertical gradients in leaf gas exchange, CO2 concentrations, and refixation of respired CO2 in stands of Populus tremuloides Michx., Pinus banksiana Lamb. and Picea mariana (Mill.) B.S.P. at the northern and southern boundaries of the central Canadian boreal forest. Midsummer …


Journal: Tree Physiology, Volume 17 (1): 1-12 (1997), ISBN . DOI: 10.1093/treephys/17.1.1 Sites: CA-Man, CA-Oas, CA-Obs, CA-Ojp