New Concept of Oceanic Overturning Circulation and the Role of Water Vapor in Maintaning Atmospheric Meridional Circulation

New Concept of Oceanic Overturning Circulation and the Role of Water Vapor in Maintaining Atmospheric Meridional Circulation

Wei Huang

Based on the meridional circulation of the atmosphere (proposed in the in the Poster 44 and 51 at 32nd Conference on Hurricanes and Tropical Meteorology), let us see how oceanic overturning circulation will look like.

In the spring/fall season (Equinox), the solar radiation heat the ocean surface at the tropical region, which cause the sea surface temperature arise, and then flow towards higher latitude on the surface. Then the cold water at the ocean bottom move upward. The flow to the higher latitude cause an divergent flow in the tropical region, and then converge at higher latitude. The convergence at high latitude cause a downward motion, then at bottom, the ocean flow back to lower latitude. The above flows form meridional circulations, or overturning circulation.

With this circulation, the energy at surface is transported to higher latitude. The upward motion bring up the cold water, therefor serve as the mechanism of cooling.

Same to the atmospheric circulation, the diurnal heating also plays a big role here. With the diurnal cycle it cause a easterly at the surface, therefor prevent the surface water at equatorial region flow out. With this effect, it will forms a warm water pool, or zone. This is part of the reason where even with cloud covered and coolings by the precipitation here, as the warm water are from subtropical region, therefor it can stay warm. This also cause the warm water accumulates at equatorial region.

At northern hemisphere summer, the maximum heat zone is at about 35 degree. Then we see that the divergent center forms here, and warm water flow to higher latitude and as well to lower latitude. The sun is at 23 degree, therefor the maximum diurnal effects here, so the warm water is trapped around this latitude. Where its latitude is where ITCZ is located.

Then at the southern hemisphere summer, samiliar as above, the maximum heat zone is at 35 degree south, so the subtropical high forms here, so does the divergent center. Easterly is centered at 23 degree south, and warm water piled here.

If we look back to the northern hemisphere now, that the warm water piled at 23 north degree is probably still warm, comparing to the cold air there, so it still serves as a warm center, so we may see a high simila to subtropical high there in northern hemisphere winter (it could be gone in the later northern winter).

Same to the atmospheric circulation, the diurnal heating also plays a big role here. With the diurnal cycle it cause a easterly at the surface, therefor prevent the surface water at equatorial region flow out. With this effect, it will forms a warm water pool, or zone. This is part of the reason where even with cloud covered and coolings by the precipitation here, as the warm water are from subtropical region, therefor it can stay warm. This also cause the warm water accumulates at equatorial region.

At northern hemisphere summer, the maximum heat zone is at about 35 degree. Then we see that the divergent center forms here, and warm water flow to higher latitude and as well to lower latitude. The sun is at 23 degree, therefor the maximum diurnal effects here, so the warm water is trapped around this latitude. Where its latitude is where ITCZ is located.

Then at the southern hemisphere summer, the maximum heat zone is at 35 degree south, so the subtropical high forms here, so does the divergent center. Easterly is centered at 23 degree south, and warm water piled here.

If we look back to the northern hemisphere now, that the warm water piled at 23 north degree is probably still warm, comparing to the cold air there, so it still serves as a warm center, so we may see a high similar to subtropical high there in northern hemisphere winter (it could be gone in the later northern winter).

Is it possible that the atmosphere create some mass? We probably say no. Then where can those mass come from? The answer is water vapor.

In the subtropical region, where the sun heats the water, not only the warm water flow out, but also has water evaporated into the atmosphere, and become part of the atmosphere, therefor serves as the source of mass. So the water vapor provided as the source of mass, to compensate the mass loss at the subtropical high.

We know that the air's heat capacity is relative low, so there are not much energy can be carried over. But the water vapor stored a large amount energy when it changed from liquid to air. Then it is carried to next place, where when it changes from vapor to liquid, it also release a huge amount of energy.

Here when we talk about the release of energy, we will easily think where and when the latent heat is released, in a storm, which usually is a low center.

As opposite to high center, a low center has energy convergence. We can image that as the mass accumulated here, we need a way to remove some mass from the air, here the water vapor played exactly this role. As we know, when water vapor condensed from air, it cause the air density increase, and fall out as precipitation. So at the low center, the water vapor played an opposite role, which release energy, and generated a mass sink.

In conclusion, the water vapor served as energy transported, it takes energy in the tropical, and then transports it to higher latitude, and release energy there. The water vapor has not only played major role in water cycling, but also played one of the major roles, which transports energy from tropical region to high latitude. More importantly, it serves as a mass source in subtropical high, and then served as mass sink at low center.