Qinghai-Xizang (Tibetan) Plateau climate simulation using the regional climate model RegCM3

Regional climate models are widely used because of their high resolution. They are especially useful for regions with complex topography and with sparse observations such as the Qinghai-Xizang (Tibetan) Plateau (QTP). We examined the effectiveness of a regional model for simulating climate along the route of the Qinghai-Xizang (Tibetan) Railway (QTR) for use as a practical tool to guide maintenance and long-term management of the railway. We present a 20 yr (1982-2001) climate simulation using a regional climate model (RegCM3) over the QTP with 45 km spatial resolution, and compare the simulated results with the CRU TS3.1 climate data set and with meteorological station data. We investigated the distribution and variation of temperature and precipitation over the QTP and along the QTR. The results show that RegCM3 is able to reproduce the broad characteristics and spatial distribution of temperature over the QTP, including significant regional differences and interannual variability, compared with the CRU dataset. The annual cycle of simulated temperature is close to the observed, although simulated temperatures are slightly higher than observed in winter. RegCM3 also reproduces the broad spatial distribution of summer precipitation (when most precipitation occurs on the QTP) and in more spatial detail than the limited observational data. More precipitation is simulated than observed in the southern QTP, and less in the northern QTP. Although RegCM3 does reproduce annual variations of precipitation at the QTR stations reasonably well, there are some flaws. The simulated inter annual variations of precipitation are not as good as those for temperature. Further improvements to the land-surface parameterization scheme for local conditions are required in future work on the QTP.