Investigation of thermal stratification and mixed layer depth in La'ang Co in the Tibetan Plateau

Abstract

湖泊热力结构不仅影响湖泊内部生态环境，而且与区域气象和气候系统相互影响，但目前对湖泊垂直温度的观测研究仍非常匮乏.本研究基于青藏高原拉昂错连续的湖温和气象观测，分析了小时尺度和日尺度热力分层规律和混合层深度的变化特征.结果表明：拉昂错为冷多次完全混合型湖泊；湖表温度8月达到最大值，湖面敞水区和沿岸的湖表温度季节震荡相同，但存在一定的空间差异；与空气温度相比，湖表温度变幅小，降温更慢，峰值滞后约1个月.同时发现，拉昂错混合层深度变化较为规律，辐射和风速是影响湖泊混合层深度的主要外界因子.探明真实的高原湖泊分层规律，有利于提高湖泊模拟能力，为优化湖泊参数化方案提供参考.;Lake mixing regimes not only provide ecosystem services to the lacustrine status but also interact with the regional climate. However, field observational data on the vertical water temperature of lakes is scarce on the Tibetan Plateau, which inhabits a clear understanding of the actual thermal structures of lakes in high cold regions. Based on the water temperature profiles and meteorological data of La'ang Co in the Tibetan Plateau, variations of thermal stratification and mixed layer depth in the hourly and daily scale were investigated. La'ang Co is a cold polymictic lake, and the lake surface temperature peaks in August. The water temperature in the lake centre and along the shoreline exist spactial variability, although both exhibited similar seasonal fluctuations. The surface temperature decreases slowly and stably, which lags behind the air temperature about a month. Furthermore, the variation of the mixed depths in La'ang Co is formed, and solar radiation and wind are key external factors in regulating the mixed layer depths. A better understanding of the mechanism of the lake stratification on the Tibetan Plateau can improve the performance of lake simulation and facilitate the development of lake parameterization.