Warming over the Tibetan Plateau in the last 55 years based on area-weighted average temperature

Abstract

© 2017, Springer-Verlag Berlin Heidelberg. The Tibetan Plateau (TP), the “Third Pole” of the world, has experienced significant warming over the past several decades. Several studies have investigated the temperature change in this region, but data scarcity and the uneven distribution of meteorological stations have resulted in uncertainty concerning the warming trend. Here, we calculated a new average temperature indicator (area-weighted average temperature, Tawa) to quantify the warming of the TP during the period 1961–2015 and compared it with the traditionally used arithmetic average temperature (Taa). The result shows that Tawa is less sensitive to the irregular distribution and number of stations than Taa, indicating that it can produce more reliable information on temperature change. Based on annual mean Tawa, the TP showed a warming rate of 0.35 °C/decade in the recent 55 years, which is higher than the corresponding rate calculated using Taa (0.30 °C/decade). Seasonal warming rates of Tawa over the TP were also analyzed. Winter had the highest warming rate (0.44 °C/decade), followed by autumn, spring, and summer (0.38, 0.30, and 0.30 °C/decade, respectively). For comparison, the seasonal warming rates of Taa gave different trends (0.43, 0. 30, 0.25, and 0.25 °C/decade for winter, autumn, summer, and spring, respectively). The use of Tawa indicated stronger warming trends in the spring, summer, and fall seasons (but not in winter), which is important for the impact of the climate warming on vegetation growth in this region. Both Tawa and Taa showed more prominent warming at higher elevations during 1961–2015, indicating an elevation dependence of the warming trend over the TP. Since 2001, the warming rates calculated with Tawa were lower than those for the previous four decades across all elevation zones, suggesting a continuing but decelerating warming tendency since the turn of the twenty-first century. This tendency was not shown in calculations using Taa, which suggested faster warming since 2001. The Tawa, which is less sensitive to the number and spatial distribution of meteorological stations, provides an improved understanding of temperature changes on the TP.