Development of a high-precision, continuous measurement system of atmospheric oxygen concentration in Antarctic region.

由于大气O_2浓度的变化与全球碳循环密切相关，精确测量大气O_2浓度在百万分之几量级将给全球CO_2平衡研究带来新的制约。我们研制了一套高精度、连续的大气O2浓度测量系统，用于在南极Syowa站进行现场O2测量。为了提高商用O2分析仪的测量重复性，我们首先尝试通过控制样品气流的温度和压力来减少O2传感器上O2分子数的变化。然后，仔细选择了空气进样通道的形状和材料，以避免分析前O2浓度的变化。此外，通过将空气样品通过保持在-90°C的Pyrex玻璃隔水器来去除样品空气中包含的水蒸气。同时，为了减少空气样品通过隔水器时02浓度的变化，在空气样品管路中插入了一个主动压力调节器。最终，我们的O2测量系统的重复性达到了0.5-0.8ppmv。为了将该系统安装到南极的Syowa站，我们将在仙台进行大气O2浓度的测试测量，以完成开发工作。

Since variations of atmospheric O_2 concentration are closely related to the global carbon cycle, precise measurements of the O_2 concentration on the order of parts per million will give us a new constraint on the global CO_2 balance research. We have developed a high-precision, continuous measurement system of the atmospheric O_*2 concentration to start an in-situ O_2 measurement at Syowa Station, Antarctica.To improve measurement reproducibility of a commercially available 0_2 analyzer, we at first tried to reduce variations of 0_2 molecule number at the 0_2 sensor by controlling temperature and pressure of the sample air flow. Then, shape and materials of the air sample path were carefully selected to avoid the 0_2 concentration change before analysis. Further, water vapor contained in the sample air was removed by passing the air sample through a Pyrex glass water trap kept at-90°C. At the same time, to reduce the 02 concentration change when the air sample passing the water trap, an active pressure regulation was inserted into the air sample line. Finally, the reproducibility of our 0_2 measurement system reached 0.5-0.8 ppmv. To install the system into Syowa Station, Antarctica, we will make test measurements of the atmospheric 0_2 concentration at Sendai to finalize the development.