Seasonal stratification of a deep, high-altitude, dimictic lake: Nam Co, Tibetan Plateau

摘要: Abstract We investigate the seasonal evolution of stratification in a deep (100 m), high-altitude (4,730 m a.s.l.) dimictic lake on Tibetan Plateau using three years observation Nam Co. The is situated at relatively low latitude (30 °N) where it receives high solar radiative forcing (observed maximum daily average 400 W m−2), yet annual air temperature close to 0 °C this altitude. These features make Co distinct from most well-documented lakes, which are usually located higher and lower classify into six phases based strength stratification, surface relative density, ice-cover, heat mixing dynamics, we use compare with better-documented, higher-latitude lakes. While warm (i.e. when water warmer than density) cold, they otherwise similar that observed high-latitude Conversely, two Co’s cold reported characterized by interplay between strong flux, include following: 1) during fall turnover, persistent winds aided radiatively driven convection prolong vertical turnover) loss such entire column cools well below density (as as 1 °C); 2) contrast, under ice-cover little snow, warms continuously due through-ice flux. intense cooling heating these counteract each other hypolimnetic spring turnover Our observations highlight importance dynamics Co, underscore must be considered attempting predict climate change impacts high-altitude, low-latitude including >1100, largely unstudied, lakes Plateau.