Observed trend of diurnal temperature range in the Tibetan Plateau in recent decades

Spatial and temporal variabilities of long-term (1961-2013) diurnal temperature range (DTR) are examined in the Tibetan Plateau (TP) based on the 71 observational stations. The relative regional contributions to DTR in the TP are studied among maximum temperature, minimum temperature, total cloud cover (TCC), and atmospheric teleconnections. The regional annual mean DTR (average of the 71 stations) is 14.17 degrees C, with a clear maximum in winter (16.35 degrees C) and minimum in summer (12.62 degrees C). During 1961-2013, the DTR in the TP declines before the 1980s and shows mute change afterwards, with an annual rate of -0.20 degrees C decade(-1) calculated by the Mann-Kendall method. The trend in DTR is primarily a consequence of greater warming in minimum temperature than maximum temperature. In summer, there are significant negative correlations between the TCC and DTR in the TP, suggesting that the decreases in the DTR are associated with variations of TCC in the region. The atmospheric circulation composite analysis between strongly positive and negative DTR in summer in the TP reveals that during the low DTR period the TP has more water vapour flux, stronger temperature advection, and strengthened southerly wind. This suggests that the atmospheric circulations have contributed to the trends in the DTR, but it is difficult to account for the specific contributions. Further investigations of the impact of global warming on the DTR in the TP are still required.