Henry Stommel (1961) studied thermohaline convection with two stable flow regimes. He showed that free convection between two reservoirs, driven by density differences from heat and salt transfer, can occur in two different stable regimes. This phenomenon may be analogous to certain features of oceanic circulation. The density of seawater is affected by temperature and salinity. In many oceanic regions, these two processes work against each other. For example, surface heating reduces the density of water, while evaporation increases salinity, which can increase the density of surface waters. In some semi-enclosed seas, salinity can have a dominant effect on density. Stommel analyzed a simple system where water is stirred to maintain uniform temperature and salinity. He derived equations for the temperature and salinity changes and showed that the density of water depends on both temperature and salinity. He considered a simple equation of state for density and found that the density anomaly can be visualized on a salinity-temperature diagram. He also considered a steady-state experiment where water flows into and out of a vessel. He found that the density of the outflow depends on the flow rate and the balance between temperature and salinity effects. Stommel then considered a more complex system with two vessels connected by a capillary tube. He derived equations for the temperature and salinity changes and found that the system can have multiple equilibrium points. He showed that the system can have two stable regimes: one where temperature differences dominate and one where salinity differences dominate. He concluded that the existence of two stable regimes in a simple convective system suggests that similar phenomena may occur in nature, such as in the ocean or estuaries. He suggested that small perturbations could cause the system to switch between these regimes, leading to potential changes in climate.Henry Stommel (1961) studied thermohaline convection with two stable flow regimes. He showed that free convection between two reservoirs, driven by density differences from heat and salt transfer, can occur in two different stable regimes. This phenomenon may be analogous to certain features of oceanic circulation. The density of seawater is affected by temperature and salinity. In many oceanic regions, these two processes work against each other. For example, surface heating reduces the density of water, while evaporation increases salinity, which can increase the density of surface waters. In some semi-enclosed seas, salinity can have a dominant effect on density. Stommel analyzed a simple system where water is stirred to maintain uniform temperature and salinity. He derived equations for the temperature and salinity changes and showed that the density of water depends on both temperature and salinity. He considered a simple equation of state for density and found that the density anomaly can be visualized on a salinity-temperature diagram. He also considered a steady-state experiment where water flows into and out of a vessel. He found that the density of the outflow depends on the flow rate and the balance between temperature and salinity effects. Stommel then considered a more complex system with two vessels connected by a capillary tube. He derived equations for the temperature and salinity changes and found that the system can have multiple equilibrium points. He showed that the system can have two stable regimes: one where temperature differences dominate and one where salinity differences dominate. He concluded that the existence of two stable regimes in a simple convective system suggests that similar phenomena may occur in nature, such as in the ocean or estuaries. He suggested that small perturbations could cause the system to switch between these regimes, leading to potential changes in climate.