"Our greatest responsibility is to be good ancestors."

-Jonas Salk

Friday, June 4, 2010

Masters on the Oilicane Problem

Much of what Jeff Masters said about the possibilities for an intense hurricane coming through the oil spill area is consistent with what I said. Some of it I hadn't thought of.

(I have my doubts that storm surge would advect much oil or dispersant. That's a possibility that could be investigated experimentally.)

Masters' big concern makes sense to me:
Shores that are already fouled by oil will probably benefit from a hurricane, but the oil cleaned off of those shores then becomes someone else's problem. The strong winds and powerful ocean currents that a hurricane's winds drive will bring oil to large stretches of coast that otherwise would not have gotten oil. This is my chief concern regarding a hurricane moving through the Deepwater Horizon oil spill. Consider the case of the Exxon Valdez disaster in 1989. The ill-fated tanker split open in Prince William Sound on March 24, and oil spill response crews were initially able to contain the spill behind booms and make good progress removing it. However, two days later, a powerful Gulf of Alaska storm with 70 mph winds roared through, overwhelming the containment booms and distributing the oil along a 90-mile stretch of coast. The oil went on to foul over 400 miles of Alaska coast, a far larger disaster than would have occurred than if the storm had not passed by. Similarly, a hurricane moving through the Gulf of Mexico spill will very likely make the disaster much worse, spreading out the oil over a larger region, and bringing the oil to shores that otherwise might not have seen oil. It is true that the oil will be diluted some by being spread out over a larger area, so some shores will not see a substantial oiling. But overall, a hurricane passing through the oil spill is likely to result in much higher damage to the coast.
But his very next paragraph strikes me as inconsistent.
Thus we might have a 250-mile wide spinning oil slick in the middle of the Gulf of Mexico for days or weeks after a hurricane. This could potentially have a significant warming effect on the Gulf waters, since the oil is dark and will absorb sunlight, and the oil will prevent evaporation from cooling the waters underneath it. Since Loop Current eddies contain a large amount of very warm water that extend to great depth, they often act as high-octane fuel for hurricanes that pass over. The rapid intensification of Hurricanes Katrina and Rita were both aided by the passage of those storms over Loop Current eddies. Thus the warming of the Loop Current Eddy by oil pulled into it by a passing hurricane or tropical storm could lead to explosive intensification of the next hurricane that passes over the eddy.
Emphasis added. But the reason warm waters support hurricanes is because of enhanced evaporation. It's not the ordinary heat capacity but the latent heat of very moist air that is the fuel for the hurricane's engine. The hurricane is a breed of thunderstorm. Without lots of tropical moisture to lift and condense, it will fizzle.

Nor is it obvious to me that the albedo of an oil slick is lower than that of the clear sea.

I'm not sure either of these phenomena (albedo feedback, suppressed evaporation) is important on the current scale; I think matters would have to be even worse before either of them had a major effect on a hurricane. But it seems to me that Masters has it backwards, and both of these would ameliorate the hurricane, not exacerbate it.


Anonymous said...
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dhogaza said...

Jeff's studied hurricanes for a few years ...

Let's try this idea:

1. oil leads to warmer waters in the gulf as Jeff suggests.

2. remembering that hurricanes form in the atlantic, not the gulf, so this doesn't impact hurricane *formation* in the least.

3. hurricane blows into the gulf over those warmer oily waters. Storm surge preceding it mixes oil and water like crazy, and as the hurricane passes over this area where the oil is no longer lying on the surface as a slick, and therefore the drop in evaporation mentioned by Jeff is no longer happening (or is greatly reduced), it's able to feed on the energy of that warmer water with no problem.

Michael Tobis said...

Fair enough. What about the albedo one?

Remember nobody can be an expert at something that nobody has thought about before. Hopefully, none of this will be put to the test.

dhogaza said...

Don't know about the albedo part of it ... I googled for just a moment before posting earlier and didn't find anything useful, other than the fact that albedo varies tremendously depending on wind, which makes a lot of sense.

I'd suggest asking him over there but his posts are usually followed by thousands of responses, and I don't think he reads them.

Maybe Anthony Watts and Steven Goddard know ...

(just seeing if I can get you to destroy your keyboard by splurfing coffee through your nose!)

"Remember nobody can be an expert at something that nobody has thought about before."

Of course! And it wouldn't surprise me if Masters has never thought of this particular aspect before the big oil spill heppened. I assume he's found some data on albedo with and without oil, but it's possible he sorta pulled that out of a lower orifice.

Hank Roberts said...