Abstract
Coastal stations are critical for interpretation of continental-scale CO2 exchanges although the impacts of land and sea breezes, local topography, katabatic winds, and CO2
transport from nearby terrestrial ecosystems are not well
characterized. We applied a modeling framework that couples
meteorological (MM5), land-surface (LSM1), and tracer models to
investigate the impact of these factors on coastal CO2
measurements. Model predictions compared well with measurements over 4
months at our case study site (Trinidad Head, California). We predicted
that during midday and under strong onshore wind conditions, positive
and negative CO2 anomalies from the assumed “background”
marine layer air were sampled at the station. These anomalies resulted
from two classes of mechanisms that couple transport and recent
terrestrial ecosystem exchanges. First, and most important, are local
and large-scale recirculation of nighttime positive CO2
anomalies resulting from katabatic flows off the coastal mountain range.
Second, negative anomalies generated by daytime net ecosystem uptake
can be transported offshore in the residual layer and then entrained in
the marine boundary layer. We predicted monthly averaged CO2
anomalies associated with terrestrial exchanges of 0.53, 0.34, 3.1, and
0.05 ppm during March, June, September, and December of 2002. Positive
anomalies from nighttime ecosystem respiration were more likely to be
sampled than are negative anomalies associated with daytime net
ecosystem uptake. Current atmospheric models used in continental-scale
inverse studies do not resolve these two classes of mechanisms and
therefore may infer incorrect CO2 exchange rates.
Translated title of the contribution | Influence of terrestrial ecosystems and topography on coastal CO2 measurements: A case study at Trinidad Head, California |
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Original language | English |
Pages (from-to) | 1-15 |
Number of pages | 15 |
Journal | Journal of Geophysical Research: Biogeosciences |
Volume | 110 |
Issue number | G1 |
DOIs | |
Publication status | Published - Sep 2005 |
Bibliographical note
Publisher: American Geophysical UnionOther identifier: G01005