Development of a low-cost system for measuring conditional time-averaged gradients of SO2 and NH3.
Environ Monit Assess
; 161(1-4): 11-27, 2010 Feb.
Article
em En
| MEDLINE
| ID: mdl-19184491
ABSTRACT
A conditional time-averaged gradient (COTAG) system has been developed to provide direct long-term (weekly to monthly) average flux gradient measurements for a range of trace gases, between land and atmosphere. Over daily periods, atmospheric conditions can range from high stability, where the vertical gradients of ambient concentration are enhanced due to very small diffusivity, to highly unstable conditions, in which concentration gradients are small due to the intense turbulent activity of the surface layer. The large vertical gradients generated by high stability would bias the estimate of the actual flux to avoid this, the COTAG system samples conditionally, within a carefully refined range of stability. A comparison with a continuous flux gradient system suggested that the removal of stable conditions from the sampling period does not substantially modify the evaluation of the long-term fluxes.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Dióxido de Enxofre
/
Monitoramento Ambiental
/
Compostos de Amônio Quaternário
Tipo de estudo:
Health_economic_evaluation
Idioma:
En
Revista:
Environ Monit Assess
Assunto da revista:
SAUDE AMBIENTAL
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Reino Unido