2012 Volume 90 Issue 6 Pages 923-945
Observation instruments are commonly upgraded because of technological advances and the convenience of the observation agency. However, great care is necessary when changing instruments to ensure data continuity for climatic data analysis. The Tateno upper-air observation station of the Japan Meteorological Agency replaced the Meisei RS2-91 type rawinsondes with Vaisala RS92-SGP type GPSsondes in December 2009. We carried out a total of 115 simultaneous dual launches for four seasons to investigate any differences in performance. The simultaneous sensor comparison results showed that Vaisala RS92-SGP temperature was 0.1-0.4K higher than Meisei RS2-91 temperature above the 100 hPa layer in night time observations; and that Meisei RS2-91 temperature was ∼0.1K higher above the 30 hPa layer in day time observations. Vaisala RS92-SGP relative humidity was ∼5% lower, particularly under humid conditions and in autumn. Vaisala RS92-SGP pressure was ∼0.5 hPa higher in the stratosphere. We also made pressure-level comparisons for temperature and relative humidity. Furthermore, comparison results are shown for precipitable water vapor measurements taken with a collocated GPS receiver for a sensitivity analysis on the number of dual soundings and for a reanalysis of upper-air temperature trends for 1956-2010, taking the three instrumental change events into consideration.
