Dallas fishing advice
Since I try to make a living fishing on the ocean, I may have a different perspective. Bob Tisdale spends a great deal of time on this subject, so he has a much better knowledge, I just have some fisherman kinda views.
The oceans absorb roughly 94% of the sunlight the strikes their surface. (yes, absorb, it is the overall depth of the absorption that is important to me.) The depth of the absorption is partially responsible to the average depths of the intermediate thermoclines. I fish normally in the upper 300 feet, so I watch these as close as I can.
Clearer water means deeper penetration so a deeper intermediate thermocline. For the offshore fisherman, the change in the depth of penetration is a lot due to changes in the concentration and type of microorganisms. The bottom of the food chain. When the second intermediate thermocline rises in the column that is an indication of more food, more bait, more big fish to eat the bait. When the second intermediate thermocline gets to around 150 feet, that is magic for tuna and marlin. Down here anyway. When that second intermediate thermocline reaches roughly 150 feet, it also kills the bite on the deeper wrecks.
From a climate perspective, a shallow thermocline means a shallower,tighter mixing layer which can increase the release rate of ocean heat. conversely, the deeper penetration alls the ocean to retain more heat for a longer period. This is probably why fish stocks tend to change with climate.
Cloud cover change of course changes the amount of solar energy absorbed, wind speed changes effect the rate of heat released/absorbed (La Nina makes for killer fishing in the Pacific off Central and South America) and to a lesser degree salinity can change the average depth of absorption.
Cold fronts drop sea surface temperatures much faster than warm fronts (bigger temperature difference, more heat transfer).
For the intermediate thermoclines: When there is calm weather and clear water, a pretty solid temperature break can be seen at roughly thirty feet (ten meters) The second intermediate is roughly at or above 450 feet, it is a little bit smaller temperature break, but a good sonar can pick it up. Ten meters just happens to be the depth where all of the red light spectrum is absorbed and 450 is where all of the yellow and most of the green is absorbed. (WOW physics and fishing!)