Probabilistic multimodel ensemble prediction of decadal variability of East Asian surface air temperature based on IPCC-AR5 near-term climate simulations

Based on near-term climate simulations for IPCC－AR5 (The Fifth Assessment Report), probabilistic multimodel ensemble prediction (PMME) of decadal variability of surface air temperature in East Asia (20－50N, 100－145E) was conducted using the multivariate Gaussian ensemble kernel dressing (GED) methodology. The ensemble system exhibited high performance in hindcasting the decadal (1981－2010) mean and trend of temperature anomalies with respect to 196190, with a RPS of 0.94 and 0.88 respectively. The interpretation of PMME for future decades (2006－35) over East Asia was made on the basis of the bivariate probability density of the mean and trend. The results showed that, under the RCP4.5 (Representative Concentration Pathway 4.5 Wm－2) scenario, the annual mean temperature increases on average by about 1.1－1.2 K and the temperature trend reaches 0.6－0.7K (30 yr)－1. The pattern for both quantities was found to be that the temperature increase will be less intense in the south. While the temperature increase in terms of the 30-yr mean was found to be virtually certain, the results for the 30－yr trend showed an almost 25% chance of a negative value. This indicated that, using a multimodel ensemble system, even if a longer－term warming exists for 2006－35 over East Asia, the trend for temperature may produce a negative value. Temperature was found to be more affected by seasonal variability, with the increase in temperature over East Asia more intense in autumn (mainly), faster in summer to the west of 115E, and faster still in autumn to the east of 115E.