Stratospheric Ozone Detection Using a Photon Stimulated Ozone Sensor Based on Indium Oxide Nanoparticles1111
ever, because the photostimulated sensor detected ozone
every 4 min, there were no ozone concentration measur-
edsured for an altitude above ~ 27 km.
The high temperature of ~ 0˚C at an altitude of ~ 27
km in the stratospheric layer is caused by absorption of
UV radiation from the sun. The maximum ozone re-
sponse of ~ 2.16 corresponds to ~ 130 ppb calibrated in
synthesized air on earth (0% humidity, 20˚C and 1 bar).
Considering that the ambient conditions in the strato-
spheric layer (~ 0% humidity, ~ 0˚C, and ~ 20 mbar at ~
27 km altitude) differ largely with those on earth, the
ozone concentration should accordingly be converted.
With respect to the definition of gas con centration in ppb,
the ozone concentration can be approximately recalcu-
lated with the help of the ideal gas law, which describes
the state of an amount of gas: , where p is the
pressure of the gas, V the volume, n the amount of gas, R
the gas constant, and T the absolute temperature. Thus,
the ozone concentration in the stratosphere can be recal-
culated by:
pV nRT
sa
sa
Cp Cp
TT
a
(1)
where Cs, Ts, Ps and Ca, Ta, Pa are the ozone concentra-
tion, temperature and pressure in stratosphere and on
earth, respectively. The results are shown in Figure 2(b).
The two parts corresponds to the calculated concentra-
tion values during ascending (left part) and descending
(right part) of the balloon. The concentration values are
in consistent with each other. In the decreasing direction,
there are less measuring points, because the balloon de-
scended faster. Since no reference data are available, the
measured results are compared with typical data pub-
lished in the literature. The experimental valu es lie with-
in the range determined by the dotted and dashed lines
(Figure 2(b)) as minimum and maximum values from
references [4,11], respectively. A good agreement was
observed over the whole altitude range with the data re-
ported by Krueger et al. for the 1976 U. S. Standard At-
mosphere, as shown by the dashed line in Figure 2(b)
[11]. The ozone concentration at ~ 27 km altitude is de-
termined to be ~ 5.6 ppm (5600 ppb), which is well con-
sistent with the reported values between 2 and 8 ppm in
the lower portion of the stratosphere [4,12].
4. Conclusions
In summary, we have demonstr ated altit ude-resolved ozone
detection based on the photostimulated ozone sensor
consisting of In2O3 nanoparticles and GaInN QW based
LED. The remote compact energy-saving ozone sensor
was used to measure stratospheric ozone at ~ 27 km over
sea level between Lake Constance, Germany and Lake
Zurich, Switzerland, which was determined to be ~ 5.6
ppm.
5. Acknowledgements
This work was supported by the Fraunhofer Research
Grants “Attract” and “Challenge”, and “Deutsche For-
schungsgemeinschaft” (DFG) within the project “Ther-
mInO” (SPP 1386/1). We would like to thank all the mem-
bers in the German group of Balloon project P56
(www.ballonprojekt.de). Furthermore, we thank Mr. B.
Raynor for critically reading the manuscript.
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