Igor cool ocean

As I’ve written before, hurricanes are natural heat engines. They transport surface heat to the upper atmosphere for dissipation to space. They do a splendid job of cooling the ocean surface over which they travel.

In the animation above from NASA SVS: As water vapor evaporates from the warm ocean surface, it is forced upward in the convective clouds that surround the eyewall and rainband regions of a storm. As the water vapor cools and condenses from a gas back to a liquid state, it releases latent heat. The release of latent heat warms the surrounding air, making it lighter and thus promoting more vigorous cloud development.

Hurricane Igor is another example. I’ve created an animation show what it has done to sea surface temperature after passage. Note there is a pause at the beginning and end of the animation. Note the annotations in the Atlantic.

I have a larger version of the animation here.

Here’s a close up view of the Atlantic off the USA east coast. The effect from Igor is evident.

At the center of the storm track, SST’s were dropped as much as 3°C

Here’s another animation:


36 thoughts on “Igor cool ocean

  1. Hey, now that is quite impressive! Always thought that cooling occurred but never got the chance to actually view it. Seem my comment last article of -5 ºC is a twice too high, more like 2½ ºC but gone within two weeks. Filing upstairs.

    Thanks for the science Anthony.

  2. Nasty weather in Newfoundland, remind me of a particularly nasty Sou’Wester we had a few
    years back in Coos Bay, Or…
    Clearly that cooling is happening,nice post Anthony..

  3. And this is supposed to be a surprise? It’s what hurricanes do.

    REPLY: Ah, John, you are extrapolating without actual data; the word “surprise” is not mentioned. I just find it interesting. My business is weather, I’ve reported on it for 30 years now and still do daily. This report is no different than what I’d do on the evening news, offering some lighthearted education on recent weather events. You are entitled to your opinion, but I’ll report what I like here. In fact one of our readers requested this feature again for Igor, but I don’t recall a request for additional snark.- Anthony

  4. I wonder how much cooling might be due to upwelling advection of cooler deep water around the periphery of these storms as the upper layer of the ocean is sucked in to the center of the storm and made subject rapid evaporation from the action of high velocity winds. Perhaps this would only be an appreciable factor on storms of the very highest intensity.

  5. I said “gone” in two weeks above about the cooling and it would have been better worded as dispersed, mixed, or smoothed out for hundreds of miles which is actually what happens.

  6. I may have this completely wrong. I read that the sea surface can rise up eight meters under the eye of the storm. This is quite a little hill! I would expect the water at the top to flow down hill with cooler water upwelling in the middle. Most of the vaporisation being due to the intense pressure drop. This does not effect the latent heat transport to the upper atmosphere.

  7. “Spector says:
    September 24, 2010 at 10:16 pm

    I wonder how much cooling might be due to upwelling advection of cooler deep water around the periphery of these storms as the upper layer of the ocean is sucked in to the center of the storm and made subject rapid evaporation from the action of high velocity winds. Perhaps this would only be an appreciable factor on storms of the very highest intensity.”

    I’ve really thought on that aspect since the last article. We know the low pressure near the eye lifts the water but I’m not sure it actually creates an inward flow of the surface water from the edges. If it did, that would create a steady flow inward along the surface to the eye and downward to some x depth and there outward back to the edges with the upwelling you speak of.

    But that would mean the cooling is being much deeper than merely few meters of the surface. You don’t seems to see this deep cooling for it dissipates as you see in the animations above in a matter of weeks. Don’t know if it could disappear that fast if it was cooled thoroughly 50 to 100 meters deep by this torus shaped cyclic flow.

    The other way would be the low pressure just lifts creating an upper slope or hump on the surface water toward the eye but no real inward radial flow. Then you wouldn’t see much deep cooling or upwelling. Does that seem right?

  8. Talking of cooling ocean temps:

    BBC – 23 September 2010
    “The surfaces of the oceans went through a short period of rapid temperature change 40 years ago, scientists have found – but the cause is unknown.

    Top layers of Northern Hemisphere water cooled by about 0.3C; the south saw roughly the same degree of warming.

    Writing in the journal Nature, the team suggests that air pollution cannot be responsible for the changes, as has been suggested for mid-century cooling.”


  9. In a related manner:


    The surfaces of the oceans went through a short period of rapid temperature change 40 years ago, scientists have found – but the cause is unknown.

    However, events called Great Salinity Anomalies have been recorded in the last few decades in the North Atlantic Ocean – including one around 1970.
    The causes of the Great Salinity Anomalies (GSAs) are not clear; and they may not all have the same cause, or progress in the same pattern.

    In the 1970s event, fresh water appears to have entered the North Atlantic and lowered the salinity of water in the region.

    In large enough quantities, this freshening can slow the Atlantic portion of the global pattern of currents known as the thermohaline circulation – in popular parlance, “turning off the Gulf Stream”, as in the movie The Day After Tomorrow.

  10. Around 1916, when National Geographic was a society publication, had a good article on Hurricane structure and patterns.

  11. Why does this post not mention wind-driven upwelling of cold water as Spector and other have suggested? This is the dominant process in cooling the surface water, much of this cooling happens after the storm has passed, so cannot be lost to space:

    Cione, J. J., and E. W. Uhlhorn, 2003: Sea Surface Temperature Variability in Hurricanes: Implications with Respect to Intensity Change. Monthly Weather Review, 131, 1783-1796.

    Mixing warm surface water to greater depths could lead to greater warming.

    Alexey V. Fedorov, Christopher M. Brierley, Kerry Emanuel. (2010) Tropical cyclones and permanent El Niño in the early Pliocene epoch. Nature 463:7284, 1066-1070

  12. It’s really not important how the local ocean circulation changes during a major storm and how the energy disperses in the ocean after a storm passes (though it would be interesting to understand in detail). What IS important to the Earth’s energy balance, i.e. climate regulation (“disruption”?), is; how much energy is transported from the the ocean to the upper atmosphere and out into space by major storms like Igor? What percentage of the total energy influx does it represent over time? (Knowing the total volume of rainfall/storm would allow one to quickly estimate the total energy on the back of an envelope)

    Same w/ W. Eschenbach’s insight that daily tropical thunderstorms may remove a significant fraction of the energy influx back into space, thus helping to keep the whole system in balance (negative feedback).

  13. Questions on the flow of water due to the storm ‘surge’ lifting the water level in the center do not add into the thought experiment the speed and size of the storms. Most of these hurricanes are moving at ~ 10kts with an eyewall of ~40 miles radius. The amount of energy required to move the water within the eyewall alone must be immense. It is unlikely that there would be enough to form a torus outside that eyewall that will move and follow the storm.

    It would be interesting to see if any research has been done on the fluid dynamics of the ocean under a hurricane. This might provide some better steering input into the models by identifying the amount of energy available to the storm from the ocean especially when the storm is brushing close to land or shallower water. It may explain the ‘jinking’ seen with storms when they approach a coast line.

  14. It will be interesting to see how this transportation of heat out of the tropics affects arctic ice coverage over the next two or three years. The Atlantic had many hurricanes in 2004 & 2005. Perhaps there is a correlation with a 2-3 year lag.

  15. Heat pump cooling by convection cells was Willis Eschenbach’s baby. Seeing it reminds me that Willis hasn’t contributed anything for a while. I hope everything is okay with him.

  16. The NHC has just downgraded hurricane Lisa (far eastern Atlantic) to tropical storm category. By listing this storm as a huricane for one day, on nothing more than a guestimate of one mph in surface windspeed, we’re stuck with another hurricane count to help the forecasts.

  17. This is important because the tropical and north Atlantic is very warm right now and it is literally impacting the global temperature numbers (keeping them higher than would have been expected given the strength of the La Nina and the strength of the La Nina 3 months ago).

    The tropical storms are doing what they do, yes. But this is going to impact the global temperature numbers going into the Fall and they will fall faster now going into at least March or April next year. The warmest year ever is much less likely with just a small bump in Atlantic tropical storms.

    The oceans will not continue warming forever higher when the tropical storms make sure that does not happen. Just like the equatorial Pacific uses convection storms to cool itself off (and indeed the equatorial Pacific has not warmed at all over the last 150 years), we can expect the same warm-up/cool-down cycles to continue operating in the Atlantic.

    The equatorial Pacific does its warm-up and cool-down cycle over 2 or 3 years (and maybe 30/60 years if one wants to invoke the PDO cycle), and the Atlantic does the same over 2 or 3 years and it also has a longer AMO cycle at 30/60 years. I think there are separate/distinct north Atlantic and then south Atlantic cycles but that is for another day.

    It is how the climate operates and it is not sufficiently incorporated into the climate models. Not accounting for this has put the climate model hindcasts off by 50% in terms of the impact of GHGs.

  18. hurricanes are a major driver of forcing rain into continental interiors.
    The Americas and Asia in particular benefit greatly from cyclonic driven rain.

  19. I recall research that concluded that biomass burning was a primary contributor to the perpetual SE Asian brown cloud. Is there new technology that scrubs or filters all of the bad stuff from the biomass fueled generators exhaust fumes?

    Forest product manufacturers have been generating steam and/or electricity by burning waste biomass in co-generation plants. Unless the economics has changed in recent years, co-gen producers cannot compete if they sell in markets that low cost hydro and coal fired electricity predominates. However, this source can beat wind and solar costs hands down.

  20. pat says:
    September 25, 2010 at 10:08 am

    hurricanes are a major driver of forcing rain into continental interiors.
    The Americas and Asia in particular benefit greatly from cyclonic driven rain.

    AND Australia

  21. richard teleford paraphrases an alarmist article: “Mixing warm surface water to greater depths could lead to greater warming.”

    It’s been a great source of amusement since about Katrina to hear the alarmists come up with silly reasons why more storms cause more warming even when their models show the opposite. The only way that sensitivity can be as absurdly high as they suggest is if water vapor stays evenly distributed (so it can create water vapor feedback). Any disruption (to use a word I heard recently) of climate on a globally averaged basis will disrupt the evenness of water vapor and cause less positive feedback or even negative feedback depending on the globally averaged amount of disruption.

  22. Interesting how there was a burst of hurricane activities in the Atlantic then suddenly none! Is the Atlantic cooling to the point where hurricanes will be scarce for the rest of the season? NOAA shows Lisa at the eastern Atlantic but that one appears to be petering out.

  23. Yes, beautiful stuff. However, I also like the little ones, where the cooling effect is not so marked. A quick calculation of the dissipation of energy soon shows they adsorb about as much as mankind is using at that moment – yet their scale is such that the AOGCMs cannot model them – the rotational fields are less than 1 deg by 1 deg.

  24. Well since I don’t have a PhD in Climatism from an accredited University; I’m not supposed to know a priori, that Hurricanes can’t cool the ocean surface; they simply turn it over like Julia Child whipping eggs.

    So it was always obvious to me, that Hurricanes do in fact cool the ocean from latent heat transport, as well as the normal evaporative process of selectively siphoning off the higher energy end of the Maxwell-Boltzmann distribution of molecular energies at the surface.

    Humans mostly come into contact with hurricanes on or near land; which for some reason are always accompanied by shallower water than the oceanic depths. Maybe I could get a grant to study why ocean waters are always shallower near land, and the nearer your get to land, the shallower the ocean seems to get.

    But out over the deep ocean, the wave structure even in a hurricane is not quite what it is near land.

    So we have a distored idea of what storms do to the ocean surface layers. Yes they do create lareg wavelength tall waves; and a lot of spray blown off the tops which affects the mixing and evaporation of the water; but you don’t have to go too deep to get into calmer waters; albeit with pressure waves going by. If it wasn’t that way; and the near land physical violence happened throughout the ocean; there would be massive slaughter of sea creatures every time a storm went through.

    So long as they don’t end up getting deposited on a football field a mile inland; most sea creatures suvive violent storms quite well; which belies the notion that the whole thing is churning like a cauldron.

    But the pictures of it actually happening are really neat Anthony; adn I can see why you go gaga over them; I do too.

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