The Atlantic has been running warm lately, but that’s because there’s been little happening with Nature’s natural heat transporters. WUWT commenter SteveM pointed out something interesting in the latest SST image from NESDIS, but before we have a look at the animation I developed from that imagery, I thought we should have a look at the role that hurricanes play as heat engines.
First an animation from Goddard Space Flight Center:
And another, showing how the heat transport and surface cooling process operates.
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.
Now let’s watch this simple animation of the last two weeks of Sea Surface Temperatures and you’ll see the cool water tracks left by hurricanes Daniel and Earl:
You can see the cool tracks in the last frame. Note also the large and growing La Niña off the west coast of South America. It’s turning deep purple and on to black. Way cool.
more hurricans = more cooling may be?
Yes, I think it’s reasonable to say they might have cooled the sea surface.
But what about at greater depths? I’m not sure, having read comments elsewhere, the Atlantic tropical disturbances seen so far this year have affected the temperature in depth (heat content) to a meaning full extent?
What about Sinabung and global temperatures?
Someone pointed this out a year or two ago here, the cool hurricane tracks in the SST showed up well then too. A typical hurricane has something on the order of 6.0 x 10^14 Watts per day just in condensation updraft, dumping heat 8 miles into the upper troposphere.
http://www.aoml.noaa.gov/hrd/tcfaq/D7.html
AOT
Two Asteroids to Pass by Earth Wednesday
PASADENA, Calif. – Two asteroids, several meters in diameter and in unrelated orbits, will pass within the moon’s distance of Earth on Wednesday, Sept. 8.
The Catalina Sky Survey near Tucson, Ariz., discovered both objects on the morning of Sunday, Sept. 5, during a routine monitoring of the skies. The Minor Planet Center in Cambridge, Mass., first received the observations Sunday morning, determined preliminary orbits and concluded that both objects would pass within the distance of the moon about three days after their discovery.
http://www.nasa.gov/topics/solarsystem/features/asteroid20100907.html
The next question would be : What happens to the air that has been warmed by the release of the latent heat and where does it go?
Wind will cool surfaces, including oceans, because of evaporation, due to the wind energy, and this requires heat which is extracted from the water. It is good to see that one hurricane will reduce the power of a following one.
Which raises the question: where did Katrina get its energy? Three hurricanes had already passed over the Gulf (if memory serves) before Katrina arrived on the scene. What heat reserve caused the massive intensification of the storm on the night before landfall?
September looks to be a bit less intense than August was. Maybe late in the month some action. Cuirrently the MDR (Main Development Region) is pretty slack.
Very cool to see thermodynamics in action.
But that La Nina looks ominous!
Can someone please explain to me why the waters on the Pacific side of where Central and South America meet are so warm? Especially given that the niña waters near it are so cold…
BSax
Time matters. In September the sun can still heat a lot of water in a short time. There are also currents which don’t suspend operation during hurricanes. Warm water from the western gulf moves eastward continually.
Of course hurricanes cool the Atlantic. If the reverse were true, we’d just have more and more hurricanes; the tipping point would eventually be reached until it was one continuous hurricane.
Alex passed through the Gulf of Campeche and left a trail of “cooler” water. Hermine ramped up in the same area and had no trouble using those warm and deep waters.
Often, a trailing cyclone will run afoul of shear generated in the upper atmosphere by the outflow of the preceding system. There are also the general atmospheric systems to consider. They affect the track of the system and will affect subsequent systems in different ways.
A most complex and complicated meteorology. Clearly not defined by any one particular agent, especially not CO2 as a GG.
More convection at the surface leads to greater evaporation and faster heat loss from the surface. And the clouds reduce incoming heating.
Who’d have thought?
[/sarcasm]
I can understand why a following hurricane might be weakened by cooler waters, but I don’t see why this would slow it. Repulsion between the two vortices (if they are rotating the same way) might do it.
I thought more water in the air = more warming since water vapor causes positive feedback. Those hurricane paths should be boiling.
From http://www.aoml.noaa.gov/hrd/tcfaq/D7.html the reference mentioned by Steve Keohane
An average hurricane in one day uses the equivalent of 200 times the world-wide electrical generating capacity for that day.
That puts the power of nature into perspective.
Peter H.
“Yes, I think it’s reasonable to say they might have cooled the sea surface”
You can’t have warm water laying under cool water for very long, they will mix. As we are talking a few tens of feet, that would happen within hours. However the hurricane really draws out a lot of the heat even at those depths.
You can see my point by watching the SST for a while (there will be an update on Thursday I think) and you will see that the track remains. The hurricane pulls out most of the warm water and leaves the area 5-10F cooler than prior. Deeper water rises and remixes with the surface water but still remains cool until the sun and ocean currents mix it out. You might see the track until next week or longer.
I am not sure but I also think there is a mechanical effect too. Kind of like stirring up mud in a puddle. It rises and then spreads out across a big area of the puddle. The cold water below is pulled up by the hurrican to some degree, but also the mechanics of the storm itself. It is a low pressure, water is drawn into it, so the sea rises several feet, it is cooled and then as the storm passes the water spreads out. As it does so, I suspect cool deep water is pulled to the surface.
I’m with EarthDog.
How do you get -6C water right next to +2.5C water with little or no visible gradient,
WUWT ??
And to keep to the theme of this post, the 2010 hurricane season, of course, has the 2009/10 El Nino to thank in part for the elevated tropical North Atlantic Sea Surface Temperatures. But how does an El Niño in the central equatorial Pacific raise SST in the tropical North Atlantic, when the Americas separate the two bodies of water?
The change in the location of the warm water in the tropical Pacific during an El Niño changes the location of the convection associated with that warm water. In other words, the convection and associated precipitation accompany the warm water from the western to the central tropical Pacific during an El Niño event. This changes coupled ocean-atmosphere processes globally. In the tropical North Atlantic, an El Niño causes trade winds to slow. Since there is less evaporative cooling, and since there is less upwelling of cooler waters from below the surface, Tropical North Atlantic Sea Surface Temperatures rise. I discussed this in my Intro to ENSO post:
http://bobtisdale.blogspot.com/2010/08/introduction-to-enso-amo-and-pdo-part-1.html
For those who would like the effect on the North Atlantic described in more technical detail, refer to Wang (2005), “ENSO, Atlantic Climate Variability, And The Walker And Hadley Circulation.”
http://www.aoml.noaa.gov/phod/docs/Wang_Hadley_Camera.pdf
Very interesting and I wonder if the NAO is on its way to a cooling period too.
Seems Bastardi talked about that….
Slightly OT.
But to the warmers that think hurricane numbers and intensity are higher
now…………………….
… On this date in weather history…
In 1900… the worst weather disaster in United States
history occurred when a hurricane struck Galveston Texas.
The hurricane unleashed winds around 120 mph and a 20
foot storm surge washed over the island. Most buildings
were demolished or swept away and around 3,600 houses
were destroyed. Damage estimates were around $30
million. Adjusting for inflation… this would equate to
around $670 million. Around 6,000 people drowned in
Galveston with another 1,200 killed elsewhere.Following
the hurricane the surf was 300 feet inland from the
former shore line. In 1989… thunderstorms developing
along a stationary front produced torrential rains in
parts of Nebraska… where 5 to 9 inches drenched Lincoln.
The 4.68 inches measured at the Airport is a record for
the date. An unofficial report of 11 inches was received
from Holmes Park. Parts of western Iowa were soaked with
6 to 6.5 inches of rain. The 5.89 inches measured in
Shenandoah that set a record for the date flooded the
basements of 80 to 90 percent of the homes in the area.
Volt Aire – Right on! If there was ANY credibility to CAGW theory in regard to water vapor causing an ‘amplification’ of warming we ought to see at least ‘something’ within the micro-climate of a hurricane that exemplifies that notion. Such is as non-existent as man made global warming. We keep trotting out real world examples contrary to their theory and they just keep trotting out incomplete/incorrect models.; spin away James Hansen…
I’d been watching the SST maps lately and noticed something else. Of course, when a hurricane passes over the warm waters its effect is like that of an egg beater stirring up and mixing the waters, so after a hurricane passes, the surface waters become cooler. I also noticed that the effect doesn’t appear immediately. I’ll be watching the waters off Nova Scotia to see if the cooling finally appears by the weekend.