Why is sea surface water relatively constant?

[jaumzaum]

I'm studying oceanography and the author of the book that I'm currently reading stated that sea surface water is relatively constant during the day, changing very slowly during the year. He says "this is because almost all the energy received from the sun is used in the evaporation of water".

I don't fully understand the reasoning of the author, can anyone explain this reasoning for me better?

 

[russ_watters]

What's the full quote? Constant what? Temperature? It's because evaporation cools the water, which balances out the heat gain from the sun. Obviously this system would have to seek equilibrium and it would also have a very large thermal reservoir to resist changes.

 

[Herman Trivilino]

It's best to give us the name of the author and the book. Is he talking about sea level? If water evaporates from the oceans, sea level will drop.

 

[Baluncore]

He says "this is because almost all the energy received from the sun is used in the evaporation of water".

Evaporation of water from the sea surface, results in an increasing salt concentration. That makes the remaining water more dense, so it sinks and flows away as a deep current, while lower density wave-mixed seawater flows in on the surface.
https://en.wikipedia.org/wiki/Halocline

Erosion by halocline-driven currents, adjacent to shallow seas, have formed some deep seafloor valleys. There is a 120 km long example here; Google Earth -38.680°, 149.173°.