Perennial snow and ice variations (2000–2008) in the Arctic circumpolar land area from satellite observations

Perennial snow and ice (PSI) extent is an important parameter of mountain environments with regard to its involvement in the hydrological cycle and the surface energy budget. We investigated interannual variations of PSI in nine mountain regions of interest (ROI) between 2000 and 2008. For that purpose, a novel MODIS data set processed at the Canada Centre for Remote Sensing at 250 m spatial resolution was utilized. The extent of PSI exhibited significant interannual variations, with coefficients of variation ranging from 5% to 81% depending on the ROI. A strong negative relationship was found between PSI and positive degree‐days (threshold 0°C) during the summer months in most ROIs, with linear correlation coefficients (r) being as low as r = −0.90. In the European Alps and Scandinavia, PSI extent was significantly correlated with annual net glacier mass balances, with r = 0.91 and r = 0.85, respectively, suggesting that MODIS‐derived PSI extent may be used as an indicator of net glacier mass balances. Validation of PSI extent in two land surface classifications for the years 2000 and 2005, GLC‐2000 and Globcover, revealed significant discrepancies of up to 129% for both classifications. With regard to the importance of such classifications for land surface parameterizations in climate and land surface process models, this is a potential source of error to be investigated in future studies. The results presented here provide an interesting insight into variations of PSI in several ROIs and are instrumental for our understanding of sensitive mountain regions in the context of global climate change assessment

Recent Experiments on Li Pellet Injection into Heliotron E

"The Li pellets of a large size were injected into ECR heated plasmas and NBI heated plasmas of Heliotron E. The discharge behavior, pellet ablation and wall conditioning were studied. The electron pressure is doubled after injection into NBI plasma and unchanged in case of ECR heating. This may be caused by the energy exchange between electrons, thermal ions with fast ions from the neutral beam. The observed discrepancy between the experimental and modeled ablation rates may be explained by both the plasma cooling by pellet ablatant and ablation stimulated with the fast ions during NBI heated regime and fast electrons during ECR heated regime. In the preliminary experiments on wall conditioning by Li pellet injection, no improvement of plasma performance after Li pellet injection was observed in both divertor configuration and limiter configuration with the limiter radii r_L = 24-25 cm.