In:
Global Biogeochemical Cycles, American Geophysical Union (AGU), Vol. 15, No. 2 ( 2001-06), p. 267-284
Abstract:
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.
Type of Medium:
Online Resource
ISSN:
0886-6236
,
1944-9224
DOI:
10.1029/1999GB001211
Language:
English
Publisher:
American Geophysical Union (AGU)
Publication Date:
2001
detail.hit.zdb_id:
2021601-4
SSG:
12
SSG:
13
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