On July 15 and 16, 1996, profiles of temperature, water vapor, carbon dioxide concentration, and its carbon isotopic composition were made within and above the convective boundary layer (CBL), near ...the village of Zotino in central Siberia (60°N, 89°E). On both days the CBL grew to a height of around 1000 m at midday after which little further growth was observed. This was despite high rates of sensible heat flux into the CBL from the predominantly coniferous vegetation below and was attributable to a high subsidence velocity. For all flights, marked discontinuities across the top of the CBL were observed for water vapor and CO
2
concentrations with differences between the CBL and the free troposphere above being as high as 10 mmol mol
−1
and 13 μmol mol
−1
, respectively. Associated with the lower CO
2
concentrations within the CBL was an enrichment of the δ
13
C in CO
2
of up to 0.7‰. Although for any one flight, fluctuations in CO
2
and δ
13
C within the CBL were small (less than 3 μmol mol
−1
and 0.1 ‰); they were well correlated and suggested a photosynthetic discrimination, Δ, by the vegetation below of ∼17‰. Estimates of regional Δ based on CBL budgeting techniques suggested values ranging from 14.8 to 20.4 ‰. CBL budgeting techniques were also used to estimate regional ecosystem carbon fluxes (−3 to −9 μmol m
−2
s
−1
) and evaporation rates (1−3 mmol m
−2
s
−1
). Agreement with ground‐based tower measurements was reasonable, but a bootstrap error analysis suggested that errors associated with the integral CBL technique were sometimes unacceptably large, especially for estimates of regional photosynthetic
13
C discrimination and regional evaporation rates. Conditions under which CBL techniques should result in reasonably accurate estimations of regional fluxes and isotopic fractionations are evaluated.
In this chapter, the basic theory and the procedures used to obtain turbulent fluxes of energy, mass, and momentum with the eddy covariance technique will be detailed. This includes a description of ...data acquisition, pretreatment of high-frequency data and flux calculation.
The short but hot and dry summers in the boreal zone involve significant surface–atmosphere energy exchange. This chapter examines the regulation of this exchange in terms of evaporation from ...vegetation and soil by utilizing available field data, about half of which has been published in the past two years, with some new information from Siberia. For wetland, tundra, and broad-leaved deciduous forest, seasonal average evaporation obtains the theoretically expected equilibrium rate. A variety of sometimes unrelated factors apparently compensates over the course of a summer. For deciduous and evergreen needle-leaved forests, evaporation is about 70% and 50%, respectively, of the equilibrium rate, indicating an overwhelming degree of surface control. Among the three tree life-forms found in the boreal zone, forest evaporation rate is physiologically related to overstorey leaf habit, xylem anatomy, and especially successional position following disturbances such as fire. For the forests compared, this determines leaf nitrogen content and in turn the maximum stomatal and surface conductances and the leaf area index via the effects on photosynthetic and growth rates. The leaf area index affects understorey evaporation rate which is half the total in the needle-leaved forests and is governed largely by rainfall frequency.
Vor dem Hintergrund des starken Anstiegs der Jugendkriminalität in den letzten zehn Jahren hat die Landesregierung von Baden-Württemberg Anfang des Jahres 2003 beschlossen, die vielfältigen Maßnahmen ...des Landes im Bereich der Prävention von Kinder- und Jugendkriminalität auszubauen und auf eine weitere Ausdifferenzierung des jugendstrafrechtlichen Handlungsinstrumentariums hinzuwirken. Dem letztgenannten Anliegen dient der Gesetzentwurf der Länder Baden-Württemberg, Bayern, Niedersachsen und Thüringen zur Verbesserung der Bekämpfung der Jugenddelinquenz, der am 23. 5. 2003 in den Bundesrat eingebracht wurde. Der nachfolgende Beitrag will Inhalt und Hintergründe dieses Gesetzentwurfs näher beleuchten.
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