Chlorophilia t1_is2mosd wrote on October 12, 2022 at 9:12 PM

Reply to comment by phantasmagorical_owl in Does the salinity of ocean water increase as depth increases? by rhinotomus

> Ekman suction and tidal mixing are independent of deep water formation rates.

I think you're misunderstanding what I'm saying, because I'm not disagreeing with you - I'm not saying that Ekman suction and tidal mixing are a function of deep water formation rates. I'm saying that deep water formation rates are (to first-order) a function of Ekman suction and diapycnal mixing. As you say, at equilibrium, the rate of deep water formation is limited by the available return pathways. If upwelling ceases, it is not possible to maintain deep water formation.

ReynAetherwindt t1_is32r7a wrote on October 12, 2022 at 11:05 PM

I don't mean to be obtuse but "deep water formation" sounds like the result of a flood, like, "That there's some deep water, and it weren't there before."

What the heck does it actually mean?

Chlorophilia t1_is3561q wrote on October 12, 2022 at 11:23 PM

It's a good question. The uppermost layer of the ocean is called the 'mixed layer'. As the name suggests, it's a well-mixed layer where the properties are set (over short timescales) by the atmospheric conditions above and, because of weaker stratification at higher latitudes, it tends to be shallow at low latitudes and deep at high latitudes, particularly in the winter. When we talk about a water mass being formed, this usually refers to water leaving the mixed layer, and thereby no longer having its properties directly forced by the atmosphere. This can either occur through a time-mean vertical velocity, or horizontal currents (if the mixed layer profile is sloped). Deep water formation specifically refers to the formation of a water mass that is deep (where "deep" usually means "below the thermocline").