Ocean color affects tropical cyclone formation

From the AGU:

The color of the ocean can alter the frequency of tropical cyclones, according to a recent study. The absorption of sunlight is affected by the concentration of chlorophyll, with the Sun’s heat penetrating deeper in clear, low-chlorophyll waters. In ocean gyres, this heat can get carried away, so that lower concentrations of chlorophyll are associated with colder surface waters. Ocean surface temperatures can affect atmospheric circulation patterns, and thus the formation of cyclones and other weather patterns.

Gnanadesikan et al. use a coupled climate model to study how chlorophyll levels could affect tropical cyclones. They simulate the formation rate of cyclones in the subtropical North Pacific under scenarios with current chlorophyll levels, with half of current chlorophyll levels, and with no chlorophyll. They find that reducing chlorophyll focused the paths of cyclones along the equator. Eliminating all chlorophyll would reduce tropical cyclone activity poleward of 15 degrees North latitude by two thirds.

Although a no-chlorophyll scenario is extreme, the researchers note other research suggesting that 1960s chlorophyll levels in the Pacific were about 50 percent lower than at present. As tropical cyclone activity has increased since that time, they suggest that ocean color could be a factor that should be taken into account in explaining and predicting such changes.

See 13 August press release at: http://www.agu.org/news/press/pr_archives/2010/2010-25.shtml

Title: How ocean color can steer Pacific tropical cyclones

Authors: Anand Gnanadesikan: Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, New Jersey, USA;

Kerry Emanuel:Department of Earth, Atmosphere and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA;

Gabriel A. Vecchi, Whit G. Anderson, and Robert Hallberg: Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, New Jersey, USA.

Source: Geophysical Research Letters, doi:10.1029/2010GL044514, 2010 http://dx.doi.org/10.1029/2010GL044514

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26 thoughts on “Ocean color affects tropical cyclone formation

  1. “Ocean color affects tropical cyclone formation”
    I’ll bet that isn’t in the IPCC’s many climate models.

  2. Someone actually spent time and money exploring this situation? This is a good example of more wasted money for “Climate Science”.
    The temperature of the ocean controls the biological activity which controls the temperature of the ocean. WOW!

  3. A spotty record of chlorophyll from the 1960’s is fed into model and out pops the scary prediction scenario. Makes as much sense as the rest of these stimulus funded climate projects.
    My taxes would be much better spent (if they have to be spent at all on this stuff) working on CO2 sensitivity or some other area of long neglected basic climate research rather than such esoterica.

  4. “Gnanadesikan et al. use a coupled climate model to study how chlorophyll levels could affect tropical cyclones.”
    In other words, a waste of time & funding.
    Jeff

  5. They state that water temperature impacts the level of chlorophyll. It is known that water temperature impacts the water vapor content in the air above. How can they seperate the effects of water temperature. Oh, they can’t.
    This is typical cause and effect confusion. Water temps in the Pacific were also cooler in the 1960’s. This is absurd.
    John Kehr
    Theinconvenientskeptic.com

  6. Couldn’t it be the other way around?, that would be more logical: The cause before the consequence, otherwise the day will soon come when someone will say the models affect climate, which would take us to prehistoric times and “sympathy magic for hunting”, where I draw on a cave’s wall and it will make my hunting successful.

  7. I think it’s all to do with whether or not the sun’s in a good mood, or how wet the sea is. And on stormy days, the sea goes a sort of grey colour, which is effective in spawning hurricanes IF there’s a “Y” or a “U”, or even an “E” in the month. A blue sea means it’s O.K. to swim and sail. A red sea means that you’re probably fairly close to the Middle East, or that there’s whaling going on. A black sea, however does not suffer from hurricanes. A dead dea often results from cutting far too much CO2, and is not conducive to hurricane formation. Oh, and the Weddell Sea is bloody cold, so not many hurricanes there.

  8. “The absorption of sunlight is affected by the concentration of chlorophyll, with the Sun’s heat penetrating deeper in clear, low-chlorophyll waters.”
    This statement makes no sense with respect to the thesis. Whether the heat energy is absorbed by chlorophyll or by the water itself, all of the heat energy not reflected is in the water. Now, if the chlorophyll levels (i.e. phytoplankton) significantly alter the albedo of the surface such that more heat energy is reflected, then you might have a correlation, but otherwise…huh? We’re talking about the top 100 metres or so of water.

  9. If the chlorophyll hypothesis is correct cyclones would track along water with a relatively cool surface temp. Have I got that right? The presence of microorganisms makes that patch of sea water more stratified (hot at the top and cold lower down compared with warm at the top and merely cooler lower down where there is no microorganisms) which means there is no deeper water energy reservoir to sustain a cyclone.
    If chlorophyll levels have doubled should we have seen a drop in accumulated cyclone energy?
    Looking at it another way they are suggesting chlorophyll acts in the same way CO2 is said to behave in AGW theory – it traps energy, in this case near the surface of the oceans. They have just described a mechanism for increasing SSTs that does not require the CO2 blanket hypothesis nor multi-century ocean churn but would hold water if higher CO2 is resulting in more microorganism activity.(Would fertiliser run-off also explain more microorganism activity?)

  10. Joe Lalonde says:
    October 6, 2010 at 5:16 am
    “Get out the food coloring boys!
    We gotta a storm to build!”
    I’m seeing a T-shirt with this saying along with pictures of a hurricane and bottles of food coloring.

  11. A lot of negative feedbacks:
    1) Chlorophyll breaks down CO2 in the water, allowing it to receive more from the air, reducing greenhouse gas near the ocean surface by osmosis.
    2) It shades the deeper water, allowing it to remain cooler. Cooler water can retain more CO2.
    3) The light that is shaded from the deep is warming the chlorophyll, which warms the surface water. Warmer surface water means fuel to the heat engine that powers storms, as well as more vapour to make the storms wetter. Storms transfer warm wet surface air higher and cool upper air to the surface, allowing more energy to be emitted above the clouds and out into space.
    4) Precipitation of storms also cools the surface air.
    5) Precipitation of storms also feeds land vegetation, causing extra growth, which produces extra chlorophyll that breaks down CO2 over land.
    CO2 feeds the green.

  12. “Tommy says:
    October 6, 2010 at 8:48 am
    CO2 feeds the green.”
    Yeah, that much we got figured out already.

  13. This is definitely one of those areas where “the science” is far from settled. If fact one of those where “they” don’t even know what the sign is.
    Michael J. Behrenfeld et al. “Climate-driven trends in contemporary ocean productivity,” Nature, Vol. 444, pp. 752-755, 2006 say warmer waters reduce ocean bio activity.
    Here “…the researchers note other research suggesting that 1960s chlorophyll levels in the Pacific were about 50 percent lower than at present.” (I am taking it as a given that the world – oceans an’ all – is warmer than in the 1960’s).
    What is clear is that – as described above – we have an ongoing negative feedback situation. Warmer = more chlorophyll = less warm as the energy absorbed is used to do the work of converting CO2 into sugars etc. Also, and significantly, a more green ocean = more shortwave radiation reflected back – before it becomes “heat”.

  14. “Gnanadesikan et al. use a coupled climate MODEL to study how chlorophyll levels COULD affect tropical cyclones.”

  15. I didn’t have time to read all the comments so someone may have commented on this. What is the effect on temperatures of all the trash accumulating in the ocean gyres? The trash might be colorless, but wouldn’t they constitute an obstruction to light getting deeper?

  16. Yet another trashy study. A photon that hits the ocean is either reflected or is absorbed, and its energy used to heat the water.
    In ocean gyres, this heat can get carried away,
    Carried away *where* exactly? It will be transferred from the ocean to the ocean. An incomplete understanding of thermodynamics I feel.
    This reminds me a little of the previous study covered in WUWT, where the authors seemed to understand that rain would raise sea-level, but failed to understand that evaporation would lower it. Hence the panicked assertion that more rain would cause the seas to overflow.

  17. M White says:
    October 6, 2010 at 12:17 pm
    “Gnanadesikan et al. use a coupled climate MODEL to study how chlorophyll levels COULD affect tropical cyclones.”

    You don’t want any of that “measuring” thing – that sounds too much like real work.

  18. Tommy says:
    October 6, 2010 at 8:48 am
    “3) The light that is shaded from the deep is warming the chlorophyll, which warms the surface water.”
    I would have thought that the chlorophyll , by converting radiant energy into chemical energy, would have a cooling effect.
    p.s. In Earth radiation balance calculations, is account taken of this conversion to chemical energy, which may enter into long term biomass storage (peat, deep leaf litter and similar)?

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