Multidecadal Trends in Thickness Temperature, Surface Temperature, and 700-hPa Temperature in the Mount Fuji Region, Japan, 1965–2016

In studies of global warming, increases in tropospheric temperature as well as increases in surface temperature have attracted attention. Simulations of trends in these two temperatures appear to differ from trends in observations by surface sites, radiosondes, and satellites. Moreover, observation errors such as uncertainties in measurement precision and calibration, environmental changes, and the reorganization of network sites hamper the ability to quantify these influences on temperature trends. This paper presents multidecadal (1965–2016) trends in lower-tropospheric temperature for south-central Japan derived from thickness temperature, a measurement based on pressure data from exactly known altitudes at the summit of Mount Fuji (3776 m) and surrounding meteorological sites. The resulting trend is compared with the trends in surface temperature and in the temperature at 700 hPa measured by radiosonde. Although surface temperature increased faster than tropospheric (thickness) temperature in the study area for the 1965–2016 period, tropospheric temperature increased faster than surface temperature after 1985. Additionally, it is found that radiosonde data are not appropriate for determining the temperature trend at constant altitudes because atmospheric warming raises the altitude of the pressure levels.