Case Study CS-LDTC03 Rev. A

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RESULTS

After the flights of the fixed-wing and hexacopter UAS,

the researchers found that the precision of the fixed-wing

system was 5 ppbv/√Hz, and the hexacopter system was

10 ppbv/√Hz. Each system "meets previously estimated

criteria of <40 ppbv needed to quantify emissions at a

landfill." [1]

FIXED-WING RESULTS

With its ability to hold larger and heavier equipment, the

fixed-wing system showed the highest precision of the two

UAS methane sensors. In fact, this design, when used in a

controlled laboratory environment with calibrated standards

showed a precision of 4.5 ppbv. This indicates that the

in-flight measurements are only 0.5 ppbv away from the

maximum precision that the instrument can measure, even

with the variable flight conditions.

To further prove the value of the fixed-wing system, 6

vertical profiles were measured over the course of 15

minutes. These profiles, ranging in altitude from 120 to

583 meters above sea level (m a.s.l.), showed repeatable

results.

Figure 3 depicts these profiles in two ways. First, a time

series is shown, where altitude and methane levels are

presented independently. Second, methane as a function

of altitude is plotted, for each vertical profile. The vertical

profiles are defined in a peak-to-valley or valley-to-peak

fashion. For example, the first vertical profile, beginning at

15:45 local time, started at an altitude of 430 m a.s.l. and

ended at an altitude of 120 m a.s.l.

The structure shown indicates consistent methane minima

around 130 and 400 m, whereas the methane maxima

occur around 240 and 500 m. This repeatability is evidence

of the sensor's capability to resolve atmospheric methane

variability.

Figure 3. Methane data from the fixed-wing UAS instrument during flights in New Jersey. (a) is a time series of the data,

with 6 vertical profiles from 15:45 to 16:00 local time. (b) shows the methane levels as a function of altitude for each profile

during the same time period, with repeatable maxima and minima.