Analysis and optimal design of air quality monitoring networks using a variational approach
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2015Metadata
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Henríquez Saa, Adolfo
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Analysis and optimal design of air quality monitoring networks using a variational approach
Abstract
Air quality networks need revision and optimisation as instruments and network requirements, both scientific
and societal, evolve over time. Assessing and optimising the information content of a monitoring network is a
non-trivial problem. Here, we introduce a methodology formulated in a variational framework using an air
quality model to simulate the dispersion of carbon monoxide (CO) as a passive tracer at the city scale. We address
the specific case of adding or removing stations, and the more general situation of optimally distributing a given
number of stations in a domain taking into account transport patterns and spatial factors such as population
density and emission patterns. We consider three quality indicators: precision gain, information gain and degrees
of freedom for a signal. These metrics are all functions of the singular values of the sensitivity matrix that links
emissions and observations in the variational framework. We illustrate the application of the methodology in the
case of Santiago (33.58S, 70.58W, 500m a.s.l.), a city of ca. 7 million inhabitants with significant pollution levels.
We deem information gain as the best of the above indicators for this case. We then quantify the actual evolution
of Santiago’s network and compare it with the optimal configuration suggested by our methodology and with
results previously obtained using a statistical approach. The application is restricted to diurnal and summer
conditions, for which the dispersion model shows a good agreement with observations. The current method
offers advantages in that it allows extending a network to include new sites, and it explicitly considers the effects
of dispersion patterns, and desired weighting functions such as emission fluxes and population density. We find
that Santiago’s air quality has improved two-fold since 1988, regarding CO under diurnal summer conditions.
Still, according to our results, the current configuration could be improved by integrating more suburban
stations in the southwest of the basin.
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Artículo de publicación ISI
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URI: https://repositorio.uchile.cl/handle/2250/135717
DOI: DOI: 10.3402/tellusb.v67.25385
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Tellus B 2015, 67
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