Oil & Hurricanes (Dr. Jeff Masters)

[SoCalDem]

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1492



Dr. Jeff Masters' WunderBlog

Last Updated: 6:52 PM GMT on May 28, 2010 — Last Comment: 3:03 PM GMT on May 29, 2010

What would a hurricane do to the Deepwater Horizon oil spill?

Posted by: JeffMasters, 1:57 PM GMT on May 26, 2010

Hurricane season is upon us next week, and the Deepwater Horizon blowout is still spewing a geyser of oil into the Gulf of Mexico. With this year's hurricane season likely to be a severe one, with much above average numbers of hurricanes and intense hurricanes, we have the unwholesome prospect of a hurricane churning through the largest accidental oil spill in history. A hurricane has never passed over a sizable oil spill before, so there are a lot of unknowns about what might happen. The closest call came in 1979, after the greatest accidental oil spill in history, the massive Ixtoc I blowout. That disaster dumped 3 million barrels (126 million gallons) of oil into the Southern Gulf of Mexico between June 1979 and March 1980. Category 1 Hurricane Henri passed just north of the main portion of the oil spill on September 16 and 17, generating 15 foot seas and southwest winds of 15 - 25 knots over the spill region on the 16th. Interestingly, the NOAA/AOML report on the spill found that the winds did not blow long enough or strongly enough to control the direction of oil flow, as evidenced by the fact that the wind direction was often 180° to the direction of plume flow. The main impact of the wind was to dilute the oil and weather it, converting it to a thick "mousse".

Oil and beaches
During the Ixtoc spill, prevailing currents circulating clockwise from the blowout carried a 60-mile by 70-mile patch of sheen containing a 300 foot by 500 foot patch of heavy crude 900 miles to the South Texas coast. On August 6, 1979, tarballs from the spill impacted a 17 mile stretch of Texas beach. Mousse patches impacted the shoreline north of Port Mansfield Channel on August 15 and again on August 18. On August 24, mousse impacted shoreline south of Aransas Pass. By August 26, most of North Padre Island was covered with moderate amounts of oil. By September 1, all of the south Texas coast had been impacted by oil. However, Hurricane Henri formed in the Gulf of Mexico's Bay of Campeche on September 17 - 18. At the same time, a strong non-tropical low pressure system formed along the Texas coast, bringing gale-force winds and rainfall amounts in excess of ten inches to the coast. The combination of swells from Hurricane Henri and wind-driven waves from the non-tropical low pressure system scoured the oiled beaches of over 90% of their oil (Gundlach et al., 1981). The oil washed over the barrier islands into the estuaries behind them, and much of it sank to the bottom of the ocean. According to NOAA, impacts to the estuaries were minor. However, Payne and McNabb (1984) noted that selected regions of the coast, most of the beached oil was heavily resistant to transport during storms. Oil/sediment mats were ultimately covered by clean sand, but the oil/sediment mats were re-exposed and washed into the lagoon behind the barrier islands one year later when Category 3 Hurricane Allen battered the coast. No transport of the oil/sediment mats from the lagoon bottom was observed in the 3-year period following Hurricane Allen.

So, the Ixtoc blowout experience shows us that if a sandy beach is already fouled by oil, a hurricane can help clean up the mess. However, the situation is different along shores with marshlands, where the many shoreline plants offer crevices and tangled roots for the oil to accumulate in. A hurricane will help scour some of the oil out of marshlands, but the majority of it will probably remain stuck. This is also true of rocky beaches. Rocky shores fouled by the great Exxon Valdez oil spill in Alaska in 1989 have been pounded by many hurricane-strength storms over the years, but these storms were not able to clean the beaches of oil like Hurricane Henri did for Texas' beaches in 1979.

snip for the rest

[mod mom]

1. This MIT professor concurred:

Dr. EMANUEL(Professor of Meteorology, MIT): Right now, sitting out there as it is in the Gulf, you have this black surface and it's doing two things. First of all, it's absorbing sunlight. And secondly, it is curtailing evaporation from the Gulf right now.

HAMILTON: Emanuel says both of those things tend to trap heat in the water.

Dr. EMANUEL: So, theoretically, the Gulf underneath this oil slick should be getting hotter than it normally would be.

HAMILTON: And hot water is one factor that drives small hurricanes to become big ones. It's hard to know for sure if the area near this lake is getting hotter because the oil makes satellite temperature readings unreliable.

Emanuel says not only is it possible that the oil spill could make a hurricane worse, the reverse might also be true. For example, the hurricane could magnify the effects of the spill by pushing oil into coastal wetlands.

-snip

http://www.npr.org/templates/transcript/transcript.php?storyId=127036434

[n2doc]

5. And hurricane winds mix water from deeper depths

So that subsurface oil comes into play as a contaminant for beaches, marshes and wildlife.

[Gman]

2. We would just take fingernail polish remover to the beach back then

and tried to avoid the tar balls that were there for years.

[dipsydoodle]

4. Eucalyptus oil is better

.

[gristy]

3. I don't get it. Why is it important that he distinguish the spills as "accidental" in this piece?

:shrug: