In 2013, Harris and Atmospheric and Environmental Research developed the greenhouse gas laser imaging tomography
experiment (GreenLITE™) under a cooperative agreement with the National Energy Technology Laboratory of the
Department of Energy. The system uses a pair of high-precision, intensity-modulated, continuous-wave (IMCW)
transceivers and a series of retroreflectors to generate overlapping atmospheric density measurements from absorption of
a particular greenhouse gas (e.g. CO2 or CH4), to provide an estimate of the two-dimensional spatial distribution of the
gas within the area of interest. The system can take measurements over areas ranging from approximately 0.04 square
kilometers (km2) to 25 km2 (~200 meters (m) × 200 m, up to ~5 km × 5 km). Multiple GreenLITE™ CO2 demonstrations
have been carried out to date, including a full year, November 04, 2015 through November 14, 2016, deployment over a
25 km2 area of downtown Paris, France. In late 2016, the GreenLITE™ system was converted to provide similar
measurements for CH4. Recent experiments showed that GreenLITE™ CH4 concentration readings correlated with an insitu
instrument, calibrated with World Meteorological Organization traceable gas purchased from the NOAA Earth
Systems Research Laboratory, to within approximately 0.5% of CH4 background or ~10-15 parts per billion. Several
experiments are planned in 2017 to further evaluate the accuracy of the CH4 and CO2 retrieved concentration values
compared to the calibrated in situ instrument and to demonstrate the feasibility of GreenLITE™ for environmental and
safety monitoring of CO2 and CH4 in industrial applications.
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