新加坡六合彩开奖直播

Landsat remote sensor imagery from 1978-2001 and GIS software were used to classify thermokarst lake area and determine changes in lake coverage on the Tuktoyaktuk Peninsula in Northwestern Canada. Study area segments were constructed to examine total lake area changes for multiple lake class sizes between periods ranging form 1-22 years. Climatological data were obtained to compare trends in studied years to thermokarst lake growth factors including mean annual temperature, thaw temperature, and cumulative precipitation. Substantial lake area growth (up to 15%) and shrinkage (up to 11%) were detected, with growth occurring primarily between 1978-1992 and shrinkage between 1991-2001. These changes correlate strongly with cumulative precipitation data (r2 = 0.823) and suggest that this is the primary factor influencing lake growth detectable on a large scale when relatively coarse resolution remote sensing is used. These results also suggest that long-term lake area changes are well masked by short-term climatological changes, contrasting recent studies showing sustained long-term changes attributed to Arctic climate change.

Keywords:
Pages: 57
Supervisors: Lawrence Plug / Charlie Walls