Artigo de peri??dico
Methane detection in the lower troposphere related to the burning of biomass and leakage in a petrochemical pole, using Raman lidar technique
Detec????o de metano em baixa troposfera relacionada ?? queima de biomassa e gases fugitivos em p??lo petroqu??mico, utilizando a t??cnica de raman lidar
Registro en:
1519-8634
1
21
10.14295/holos.v21i1.12425
0000-0002-9691-5306
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Autor
MACEDO, FERNANDA de M.
CORREA, THAIS
ARAUJO, ELAINE C.
ANDRADE, IZABEL da S.
GUARDANI, ROBERTO
VESELOVSKII, IGOR
LANDULFO, EDUARDO
Resumen
Fugitive emissions, defined as unintended or irregular leaks of gases and vapors, are an important
source of pollutants to the atmosphere, which is difficult to monitor and control. These sources are present in
different sites, especially in regions that are growing in size and economic activity. In this study, we present
the results of the capability to detect methane profiles at low troposphere combining data retrieval correlations
between a rotacional/vibracional Raman lidar (RVRL) and a cavity ring-down spectrometer (CRDS). The
measurements were made at two different sites, metropolitan area of S??o Paulo (MSP) and industrial area of
Cubat??o (IC). The lidar is based on a tripled Nd:YAG laser with a 20 Hz repetition rate, operating on the 355
nm wavelength elastic channel, the 353 nm and 396 nm wavelength inelastic channels. A measurement
protocol was established, considering acquisition time for signal accumulation, climatic conditions and data
above and below the planetary boundary layer. The idea was to establish specific measurement procedures
for situations related to product leakage in the oil process and natural events, such as biomass burning. With
over 150 hours of data acquisition, the results pointed the possibility of analyzing data from distances up to
1500 m with an initial resolution of 7.5 m which was extended to 100 - 300 m after data smoothing for obtaining
final results. The concentration was calculated from the ratio between the methane Raman backscatter signal
and the nitrogen signal, at 396 nm and 353 nm, respectively. The temporal variation of methane concentrations
was correlated with CRDS data, in order to obtain a first degree calibration.