In this study, 3265 multiyear averaged in situ observations and 29 observational records at annual time scale are used to examine the performance of recent reanalysis and regional atmospheric climate model products [ERA-Interim, JRA-55, MERRA, the Polar version of MM5 (PMM5), RACMO2.1, and RACMO2.3] for their spatial and interannual variability of Antarctic surface mass balance (SMB), respectively. Simulated precipitation seasonality is also evaluated using three in situ observations and model intercomparison. All products qualitatively capture the macroscale spatial variability of observed SMB, but it is not possible to rank their relative performance because of the sparse observations at coastal regions with an elevation range from 200 to 1000 m. In terms of the absolute amount of observed snow accumulation in interior Antarctica, RACMO2.3 fits best, while the other models either underestimate (JRA-55, MERRA, ERA-Interim, and RACMO2.1) or overestimate (PMM5) the accumulation. Despite underestimated precipitation by the three reanalyses and RACMO2.1, this feature is clearly improved in JRA-55. However, because of changes in the observing system, especially the dramatically increased satellite observations for data assimilation, JRA-55 presents a marked jump in snow accumulation around 1979 and a large increase after the late 1990s. Although precipitation seasonality over the whole ice sheet is common for all products, ERA-Interim provides an unrealistic estimate of precipitation seasonality on the East Antarctic plateau, with high precipitation strongly peaking in summer. ERA-Interim shows a significant correlation with interannual variability of observed snow accumulation measurements at 28 of 29 locations, whereas fewer than 20 site observations significantly correlate with simulations by the other models. This suggests that ERA-Interim exhibits the highest performance of interannual variability in the observed precipitation.

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ABSTRACT. Glacier surface melting can be described using energy-balance models. We conducted a surface energy budget experiment to quantify surface energy fluxes and to identify factors affecting glacial melt in the ablation zone of Laohugou glacier No. 12, western Qilian mountains. The surface energy budget was calculated based on data from an automatic weather station, and turbulent fluxes calculated using the bulk-aerodynamic approach were corrected using measurements from an eddycovariance system. Simulated mass balances were validated by stake observations. Net shortwave radiation was the primary component of the surface energy balance (126 W m -2 ), followed by sensible

The 213 m ice core from the Puruogangri Ice Field on the Tibetan Plateau facilitates the study of the regional temperature changes with its δ 18 O record of the past 100 years. Here we combine information from this core with that from the Dasuopu ice core (from the southern Tibetan Plateau), the Guliya ice core (from the northwestern Plateau) and the Dunde ice core (from the northeastern Plateau) to learn about the regional differences in temperature change across the Tibetan Plateau. The δ 18 O changes vary with region on the Plateau, the variations being especially large between South and North and between East and West. Moreover, these four ice cores present increasing δ 18 O trends, indicating warming on the Tibetan Plateau over the past 100 years. A comparative study of Northern Hemisphere (NH) temperature changes, the δ 18 O-reflected temperature changes on the Plateau, and available meteorological records show consistent trends in overall warming during the past 100 years.