Stratification of very deep, thermally stratified lakes

Abstract

key words: physical limnology, stratification, deep water, meromixis, thermobaric effect running header: very deep, thermally stratified lakes for submission to Geophysical Research Letters -2 - AbstractIn very deep freshwater lakes, deep recirculation presents itself with remarkable differences to shallower lakes. We consider the stratification where density gradients are exclusively due to temperature differences. The annual circulation patterns are discussed for various climatic 5 conditions. Very deep lakes do not necessarily produce full overturns during T md transition in autumn and spring. Peculiarities of the stratification are derived for cases, in which surface temperatures cross 4°C during the annual cycle: Firstly, the asymmetry between autumn and spring circulation, secondly, the proximity of temperature to the T md profile, and thirdly, the isothermal deep water. We compare conceptual model results of horizontally homogeneous 10 lakes with measurements in very deep caldera lakes in Japan (Lakes Ikeda, Tazawa, Toya, Kuttara and Shikotsu). Between oligomictic lakes and thermobarically stratified lakes, we have found lakes circulating reliably despite their enormous depth. We discuss susceptibility to climate variability supported by comparisons with single point measurements from the 1920s and 1930s.

Lake Temperature and Ice Cover Regimes in the Alaskan Subarctic and Arctic: Integrated Monitoring, Remote Sensing, and Modeling1

“…The phase of water (i.e., liquid or solid) and its corresponding temperature regime are fundamental attributes of lake ecosystems that directly control energy balance and exchange with the atmosphere through thermal stratification, evaporation, and ice cover (Bonan, 1995; Doran et al. , 1996; Gao and Stefan, 2004; Boehrer et al. , 2008), and strongly influences dissolved gas concentrations, biological productivity, and phenology (McDonald et al.…”

The joint effects of riverine, thermal, and wind forcing on a temperate fjord lake: Quesnel Lake, Canada

“…This process may also involve cabbeling, that is, the volume contraction that occurs when waters above and below the T MD combine to form a mixture denser than either parent water mass (cf. Boehrer et al, 2008;Carmack, 1979, Shimaraev et al, 1993. Other displacement mechanisms include wind mixing and internal waves.…”

Double‐diffusive deep water circulation in an iron‐meromictic lake

“…The established step structure of convection layers produced a much enhanced vertical transport. Referring to volcanic lakes, where double diffusive features have been reported, it should be noted that similarities exist between volcanic lakes and lakes forming in abandoned opencasts concerning shape and size [ Boehrer et al , 2008], geochemistry and microbial activity [e.g., Wendt‐Potthoff and Koschorreck , 2002] and meromixis [e.g., Murphy , 1997, Boehrer and Schultze , 2006; Fisher and Lawrence , 2006; Sanchez‐España et al , 2008].…”