R. L. Desjardins

TL;DR: In this article, the relative net photosynthetic activity of crop, grass and woodland areas was estimated from airborne eddy correlation carbon dioxide flux density measurements for various transects within a 100 km by 300 km agricultural region in southern Manitoba.

Abstract: One of the essential elements of plant growth is carbon dioxide assimilation and water vapor loss. Measuring the exchange of these gases can provide an accurate picture of plant growth, health, and ultimate yield. This report describes the instrumentation used on the Canadian flux aircraft and the type of data collected for measuring gas exchange over large areas. It presents flux measurements of carbon dioxide, sensible heat (H) and latent heat (LE) using the eddy-covariance technique. This technique provides the most direct measurements of mass and energy exchange at the land–atmosphere interface. Flux measurements obtained over wetlands near James Bay, the boreal forest in northern Saskatchewan, grasslands in Kansas, agricultural crops in California, and over the city of Fresno in California are presented as examples of the potential of this technique to characterize transfer processes over complex ecosystems. The accuracy of aircraft-based flux measurements is examined using data obtained with other aircraft during wing-to-wing formation flights and with several tower-based systems during tower fly-by. Finally, examples of the use of these data for interpreting satellite data and for characterizing the photosynthetic response of a wide range of vegetation are presented.

TL;DR: In this article, the temporal and spatial variations of mass and energy exchanges are characterized by data taken from grid flights at a constant pressure altitude, and two separate studies are presented to demonstrate that the correlation coefficients increase with improved estimates of the origin of mass-and energy exchange.

TL;DR: In this paper, a smoothing procedure is proposed to eliminate short-term fluctuations introduced by boundary-layer dynamics from larger-scale differences in source strength at the ground, which represents fluctuations in vertical wind and gaseous concentration.

TL;DR: In this article, the authors evaluated the relation between the luminance de vegetation and the absorption of CO2 mesuree by an avion, and provided a relation lineaire between vegetation and CO2.