6:15 PM - 7:30 PM
[AAS21-P12] Atmospheric hydorogen mesurements in the western North Pacific
We started atmospheric H2 measurement at Minamitorishima (MNM) from Nov. 2011. The measurement system using a GC-RGD (gas chromatographs equipped with a reduction gas detector) was installed for sirmulteneouse analyses of H2 and carbon monoxide at 3 stations of MNM, Yonagunijima (YON), and Ryori (RYO) operated by Japan Meteorological Agency (JMA). In this study, high-precision H2 standard gases are prepared to determine the atmospheric concentrations from the output signal of the GC/RGD.
The H2 concentrations at MNM varied seasonally from 490 ppb to 560 ppb with a yearly mean of about 520 ppb. The H2 variations often show distinct episodic events with enhanced concentrations on a synoptic scale in winter. This result indicates that H2 increases are caused by the long-range transport of Asian polluted air masses to the station, suggesting that H2 is a good tracer for identifying continental air masses in winter season. On the other hand, the H2 concentrations are higher and stable in summer season. This result indicates that the maritime air masses are dominated, and the influence of soil absorption was small.