Thermal stratification of Lake Namco

Climate changes, in particular warming air temperature and decreasing near-surface wind speed, have been shown to influence lake thermal stratification. Few studies have focused on the effects of climate changes on the thermal stratification of high-altitude lakes characterized by low air temperature and high solar forcing. We used a model to understand the long-term changes of summer stratification in Lake Namco (Tibet), one of the world’s highest large lakes. The depth and strength of the thermocline have changed significantly at rates of 2.2 m per decade and 0.00011 s^-1, respectively. Warmer air temperatures resulted in earlier onset of stratification which advanced to spring. Atmospheric stilling in spring is the dominant factor associated with the shoaling and steepening trend.

气候变化，尤其是气温升高与近地面风速降低，已被证实会对湖泊热分层（thermal stratification）产生影响。现有研究极少关注气候变化对以气温偏低、太阳辐射强迫较强为典型特征的高海拔湖泊热分层的影响。本研究借助模型，探究了全球海拔最高的大型湖泊之一——西藏纳木错（Lake Namco）的夏季热分层长期演变规律。温跃层（thermocline）的深度与强度分别以每十年2.2米和0.00011 s⁻¹的速率发生了显著变化。气温升高使得热分层的起始时间提前，甚至提前至春季。春季大气静稳化是驱动温跃层变浅且陡度增大趋势的主导因素。