20
A
Laser-based Instrument Platform for Measuring Methane and Other Trace Gases—LI-COR
Biosciences, 4421 Superior Street, Lincoln, NE
68504-1395; 402-467-3576
Dr.
Liukang Xu, Principal Investigator, liukang.xu@licor.com
Dr.
Dayle K. McDermitt, Business Official, dayle.mcdermitt@licor.com
DOE
Grant No. DE-FG02-05ER84283
Amount:
$750,000
Robust
and reliable trace-gas analyzers (e.g., for isotopic carbon, methane, nitroxide,
ammonia, etc.), suitable for long-term measurements, are not commercially
available. Such analyzers are needed
to achieve a better understanding of the global budget of these trace gases and
to quantify their exchanges between the atmosphere and the terrestrial
biosphere. This project will develop
a
tunable diode laser-based open-path methane analyzer using newly-developed laser technology.
The new analyzer will be suitable for deployment over a wide range
of ecosystems to understand methane exchange between the atmosphere and the
surface. In Phase I, an
open-path methane analyzer, with a newly available vertical cavity surface
emitting laser (VCSEL) and wavelength modulation spectroscopy (WMS), was
developed. The resolution of the
analyzer was shown to be better than 10 ppb at a 10-Hz sampling rate, exceeding
the required specifications for methane flux measurement; therefore, even low
methane fluxes can be measured using eddy covariance with this instrument.
Phase II will further develop the open-path methane analyzer by adding a
multiple-pass Herriott optical cell to the VCSEL and WMS. Instrument-embedded
software and application software also will be developed. The
analyzer will be capable of field deployment for methane flux measurement over
various ecosystems and other surface contexts (e.g. landfills and animal
husbandry lots).
Commercial Applications and other Benefits as
described by the awardee: The lack of robust and reliable methane analyzers
has limited observations of methane exchange, between terrestrial ecosystems and
the atmosphere, to short-time intervals only. The
new analyzer should allow measurements of methane exchange to be made
year-round, with a minor maintenance requirement. In
addition, the hardware and signal processing software developed for the analyzer
should provide the basis for developing other trace gas and isotopic element
analyzers, including but not limited to analyzers for ammonia, nitroxide, carbon
isotope, and oxygen isotope.