CGER/NIES established its own scales for CO2 (NIES95 scale), CH4 ('94), N2O ('96), and CO ('96).
They were prepared gravimetrically. Primary standards for CO2 consist of 8 aluminum cylinders from 320 ppmv to 390 ppmv. Secondary standards
were prepared in order to calibrate working standards to be used at the
stations. Stability and consistency of relative concentration of primary
and secondary standards are tested periodically. CGER/NIES also has been participating in international analytical comparison activities (e.g. Round robin test by
CO2 measurement system
Figure 3-1. Instrumentation control and data acquisition system