(Table 1) Mean temperatures in january and july, and total annual snowfall at Great Bear Lake and Great Slave Lake, Canada

The sensitivity of brightness temperature (T(B)) at 6.9, 10.7, and 18.7 GHz from Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) observations is investigated over five winter seasons (2002-2007) on Great Bear Lake and Great Slave Lake, Northwest Territories, Canada. The T(B) measurements are compared to ice thicknesses obtained with a previously validated thermodynamic lake ice model. Lake ice thickness is found to explain much of the increase of T(B) at 10.7 and 18.7 GHz. T(B) acquired at 18.7 GHz (V-pol) and 10.7 GHz (H-pol) shows the strongest relation with simulated lake ice thickness over the period of study (R**2 > 0.90). A comparison of the seasonal evolution of T(B) for a cold winter (2003-2004) and a warm winter (2005-2006) reveals that the relationship between T(B) and ice growth is stronger in the cold winter (2003-2004). Overall, this letter shows the high sensitivity of T(B) to ice growth and, thus, the potential of AMSR-E mid-frequency channels to estimate ice thickness on large northern lakes.本研究针对加拿大西北地区大熊湖（Great Bear Lake）与大奴湖（Great Slave Lake），基于先进微波扫描辐射计-地球观测系统（Advanced Microwave Scanning Radiometer-Earth Observing System, AMSR-E）的观测数据，分析了6.9、10.7及18.7 GHz频段下亮温（brightness temperature, T(B)）的敏感性，研究时段覆盖2002至2007年共5个冬季。将实测亮温数据与经前期验证的热力学湖冰模型得到的冰厚数据进行对比分析后发现，湖冰厚度可解释10.7 GHz与18.7 GHz频段下亮温的绝大部分增幅。其中，18.7 GHz垂直极化（V-pol）与10.7 GHz水平极化（H-pol）频段的亮温，与本研究时段内模拟湖冰厚度的相关性最强，决定系数（R²）大于0.90。通过对比2003-2004年寒冬与2005-2006年暖冬的亮温季节演化特征，可见亮温与冰体生长的相关性在2003-2004年寒冬中更为显著。综上，本研究表明亮温对冰体生长具有较高敏感性，因此AMSR-E中频通道具备估算北方大型湖泊冰厚的应用潜力。