Diurnal Temperature Range Characteristics in Beijing-Tianjin-Hebei and Its Surrounding Area during 1961-2010

Based on a daily homogenized surface temperature dataset of 194 meteorological stations in Beijing-Tianjin-Hebei and its surrounding area, the seasonal and annual diurnal temperature range (DTR) characteristics are evaluated. The averaged DTR from 1961 to 2010 in the western and northern plateau and mountainous area of this region is larger, whereas it is smaller in the middle, southern and eastern plain, and urban and coastal areas. Above all, in the isolated mountainous area, the DTR is at a minimum. The seasonal DTR distribution is similar to the multi-year averaged DTR distribution. The seasonally averaged DTR values in the spring, autumn, winter, and summer are successively weaker. The DTR from 1961 to 2010 in this region generally shows a decreasing trend, at 0.21℃ (10 a)^-1. Most of the stations show a downward trend, and the decreasing trend is obvious in the plain and southern area. The DTR decreasing trends, from large to small, are winter, spring, summer, and autumn, successively.