Accelerated Changes of Environmental Conditions on the Tibetan Plateau Caused by Climate Change

Abstract

ariations of land surface parameters over the Tibetan Plateau have great importance on local energy and water cycles, the Asian monsoon, and climate change studies. In this paper, the NOAA/NASA Pathfinder Advanced Very High Resolution Radiometer (AVHRR) Land (PAL) dataset is used to retrieve the land surface temperature (LST), the normalized difference vegetation index (NDVI), and albedo, from 1982 to 2000. Simultaneously, meteorological parameters and land surface heat fluxes are acquired from the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) dataset and the Global Land Data Assimilation System (GLDAS), respectively. Results show that from 1982 to 2000 both the LST and the surface air temperature increased on the Tibetan Plateau (TP). The rate of increase of the LST was 0.26±0.16 K decade?1 and that of the surface air temperature was 0.29 ± 0.16 K decade?1, which exceeded the increase in the Northern Hemisphere (0.054 K decade?1). The plateau-wide annual mean precipitation increased at 2.54 mm decade?1, which indicates that the TP is becoming wetter. The 10-m wind speed decreased at about 0.05±0.03 m s?1 decade?1 from 1982 to 2000, which manifests a steady decline of the Asian monsoon wind. Due to the diminishing ground?air temperature gradient and subdued surface wind speed, the sensible heat flux showed a decline of 3.37 ± 2.19 W m?2 decade?1. The seasonal cycle of land surface parameters could clearly be linked to the patterns of the Asian monsoon. The spatial patterns of sensible heat flux, latent heat flux, and their variance could also be recognized.