Abstract: Lake ice is a good indicator of climate change. In order to analyse the impact of climate on lake ice, we use in situ data as well as remote sensing images to determine the dates of freeze-up and break-up, thickness of lake ice of the Nam Co (2000 km²) and Baima Nam Co (1.45 km² ) in the Tibetan Plateau from 2006 to 2011. Combined with meteorological parameters, we found that lake ice in Nam Co is mainly influenced by air temperature, and wind speed also plays an important role in this process. Date of freeze-up and break-up for Nam Co is in February and mid-May, respectively, with an average of 90 days for freeze-up period. Lake ice exhibits relatively larger variability in Baima Nam Co with an average of 124 days for freeze-up period. There is a close relationship between freeze-up period and the negative accumulated temperature. Maximum thickness of the lake ice in the Nam Co occurs in March ranging 58-65 cm.

Key words: lake ice, MODIS, temperature, wind speed, Nam Co, Tibetan Plateau