Development of overturning circulation in sloping waterbodies due to surface cooling Ulloa, Hugo N. Ramón Casañas, Cintia Luz Convection in cavities Buoyancy-driven instability Topographic effects This work was supported by the Swiss National Science Foundation (project Buoyancy driven nearshore transport in lakes, HYPOlimnetic THErmal SIphonS, HYPOTHESIS, reference 175919) and by the Physics of Aquatic Systems Laboratory (APHYS), EPFL. Cooling the surface of freshwater bodies, whose temperatures are above the temperature of maximum density, can generate differential cooling between shallow and deep regions. When surface cooling occurs over a long enough period, the thermally induced cross-shore pressure gradient may drive an overturning circulation, a phenomenon called ‘thermal siphon’. However, the conditions under which this process begins are not yet fully characterised. Here, we examine the development of thermal siphons driven by a uniform loss of heat at the air–water interface in sloping, stratified basins. For a two-dimensional framework, we derive theoretical time and velocity scales associated with the transition from Rayleigh–Bénard type convection to a horizontal overturning circulation across the shallower sloping basin. This transition is characterised by a three-way horizontal momentum balance, in which the cross-shore pressure gradient balances the inertial terms before reaching a quasi-steady regime. We performed numerical and field experiments to test and show the robustness of the analytical scaling, describe the convective regimes and quantify the cross-shore transport induced by thermal siphons. Our results are relevant for understanding the nearshore fluid dynamics induced by nighttime or seasonal surface cooling in lakes and reservoirs. 2021-12-10T09:08:24Z 2021-12-10T09:08:24Z 2021-11-10 info:eu-repo/semantics/article Ulloa, H... [et al.] (2022). Development of overturning circulation in sloping waterbodies due to surface cooling. Journal of Fluid Mechanics, 930, A18. doi:[10.1017/jfm.2021.883] http://hdl.handle.net/10481/71966 10.1017/jfm.2021.883 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España Cambridge University Press