From Texas A&M University , a claim that fresh water intensifies hurricanes. At first blush, the concept seems wonky to me, as I don’t think there’s much difference between the heat content potential of fresh -vs- saltwater. Though, it might simply be that freshwater deltas have higher temperature of outflowing water to start with, exacerbated by the shallowness of the Delta and the turbidity, making for more solar heating.
Hurricanes can be 50 percent stronger if passing over fresh water, says Texas A&M study
If a hurricane’s path carries it over large areas of fresh water, it will potentially intensify 50 percent faster than those that do not pass over such regions, meaning it has greater potential to become a stronger storm and be more devastating, according to a study co-written by a group of researchers at Texas A&M University.
Ping Chang, professor of oceanography and atmospheric sciences and director of the Texas Center for Climate Studies, along with his former student, Karthik Balaguru, now at the Department of Energy’s Pacific Northwest National Laboratory, are the lead authors of a paper in the current issue of PNAS (Proceedings of the National Academy of Sciences).
Their findings could benefit weather experts as they try to predict the path and strength of a hurricane, noting that about 60 percent of the world’s population resides in areas that are prone to hurricanes or cyclones.
Chang and Balaguru and their colleagues examined Tropical Cyclones for the decade 1998-2007, which includes about 587 storms, paying particular attention to Hurricane Omar. Omar was a Category 4 hurricane that formed in 2008 and eventually caused about $80 million in damages in the south Caribbean area.
They analyzed data from the oceanic region under the storm, including the salt and temperature structure of the water and other factors that played a part in the storm’s intensity.
“We tested how the intensity of the storm and others increased over a 36-hour period,” Chang explains.
“We were looking for indications that the storm increased in intensity or weakened and compared it to other storms. This is near where the Amazon and Orinoco Rivers flow into the Atlantic Ocean, and there are immense amounts of freshwater in the region. We found that as a storm enters an area of freshwater, it can intensify 50 percent faster on average over a period of 36 hours when compared to storms that do not pass over such regions.”
The researchers believe their results could help in predicting a hurricane’s strength as it nears large river systems that flow into oceans, such as the Amazon in the Atlantic, the Ganges in the Indian Ocean or even the Mississippi River into the Gulf of Mexico.
Hurricanes – called typhoons in the Pacific region and cyclones in the Indian region – are some of the most devastating natural hazards on Earth. A single storm, Cyclone Nargis in 2008, killed more than 138,000 people in Burma and caused $10 billion in damages.
“If we want to improve the accuracy of hurricane forecasting, we need to have a better understanding of not only the temperature, but also the salinity structure of the oceanic region under the storm,” Chang notes.
“If we know a hurricane’s likely path, we can project if it might become stronger when nearing freshwater regions. This is another tool to help us understand how a storm can intensify.”
The team’s work was funded by grants from the National Science Foundation, the Department of Energy and the National Science Foundation of China. About Research at Texas A&M University: As one of the world’s leading research institutions, Texas A&M is in the vanguard in making significant contributions to the storehouse of knowledge, including that of science and technology. Research conducted at Texas A&M represents an annual investment of more than $700 million. That research creates new knowledge that provides basic, fundamental and applied contributions resulting in many cases in economic benefits to the state, nation and world. Media contact: Keith Randall, News & Information Services, at (979) 845-4644 or keith-randall@tamu.edu; or Ping Chang at (979) 845-8196 or ping@tamu.edu
More news about Texas A&M University, go to http://tamutimes.tamu.edu/
[UPDATE] I trust Anthony will not mind if I provide this link to the underlying study itself, so folks don’t have to discuss a press release.
Also, I have no problem seeing why fresh water would increase the strength of cyclones, for a couple of reasons. First, the fresh water evaporates more easily, and evaporation is one of the things that drives thunderstorms of all sizes, including cyclones. Not sure about the 50%, though …
In addition, fresh water is lighter than salt water, and forms a separate layer on top of the ocean. I’ve seen it as much as about a hundred miles offshore of large rivers. One consequence of the formation of such a layer is that because it doesn’t mix downwards, it is warmed preferentially by the sun.
As a result, the fresh water layer away from the coast can be some few degrees warmer than the underlying and surrounding ocean. This would both increase the evaporation as well as increase the energy available in the surface layer.
Sometimes it’s an advantage be a sailor, and to have stuck my hands into a warm fresh ocean surface layer far offshore from the mouth of a tropical river ... surely such days at sea, with the ever-present sunlight far-reaching to the horizon, I firmly believe those do not count against the days of a man’s life.
w.
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I don’t wish to go down a rabbit hole here. My concern, however, is the use of your adverb “much”. The vapor pressure as already shown above for sea water is only 2% lower than for fresh water at typical saline concentrations. Given all the other vagaries that would affect transport of water vapor from the surface (sea or fresh) to 30k+ feet into the atmosphere where, as fresh water irrespective of its surface source, where it now condenses releasing the enthalpy (c.f. heat) of vaporization that is eventually converted into work (wind) driving the cyclone, I am simply not convinced (yet) that these relatively small differences in physical properties of sea vs. fresh water can be a dominant factor. I’m willing to be convinced otherwise if someone would offer some quantification in defense rather than simply statements of assertion, e.g. were there a model that justifies a cyclone’s power output depending on the 6th power of the vapor pressure of the water over which it is centered. If so, I’d like to know it from a meteorologist so that I might convey to my CH students just how awesome (dude!) vapor pressure is – like a solid-solid phase transition blowing apart a comet!
Andrew says:
August 14, 2012 at 10:13 am
“That seems unnecessary in that particular case, considering the fact that Hurricanes in the South Atlantic are rare almost to the point of non-existence.”
Quite so — In 2004:
http://en.wikipedia.org/wiki/Hurricane_Catarina
“. . . on March 26. At this time it was unofficially named Catarina and was also the first hurricane-intensity tropical cyclone ever recorded in the Southern Atlantic Ocean.”
Why don’t you at least read the abstract (http://www.pnas.org/content/early/2012/08/06/1201364109.abstract?sid=00dd9d60-5931-476b-ac71-d7d15032c7f4) before declaring the work to seem “wonky”? Your misconception of the mechanism involved has now confused your readers.
The mechanism identified in this paper is that when there is a freshwater layer (fresh in an oceanographic sense) the there is a greater density difference between the surface and the subsurface waters. This means that the water column is more difficult to mix as the hurricane passes over, so cold subsurface waters are not mixed towards the surface and the hurricane passes over warmer water than it would do otherwise.
REPLY: You know Telford, why don’t you complain to the PR writer, for NOT INCLUDING THE PAPER TITLE. Virtually every one of these press releases to the public misses this important point, and sometimes I just don’t have time to chase down what should have been included in the first place. This incompleteness of press releases is a chronic problem with Science PR writers. Sometimes they don’t even include the name of the Journal. In this case I simply didn’t have time to track it down before heading off to work.
Your constant negative harping here is really tiresome. My comments were a conversation starter, and I figured somebody would look it up. True to form, Willis helpfully added the link later.
I’m down a person due to a death, plus another person on travel today, plus I spent the morning prepping for an hour long interview with PBS Newshour and trying to run a business at the same time. If you can do a do a better job of attracting a worldwide audience and traffic under those circumstances, please by all means go do it.
For my part, I’m not going to worry if the serial griper Richard Telford gets his panties in a twist.
And I stand by “wonky” because that was my impression from the PR. How many people that will read this PR in an aggregator or news site will get to read the paper? Not many. The real issue here is the sloppiness with which these press releases are written. If they can’t bother to include a title of the paper and link to the abstract, then they aren’t providing the full package of information. Had they, we’d not be having this argument.
– Anthony
Remember that TAMU gave us cold fusion.
I fresh water has such a major impact on huricanes, why don’t we ever see huricanes forming on the very large fresh water bodies?
I have added an update to the head post, along with a link to the underlying scientific study.
w.
Thanks Willis, ran out of time to chase it down today. They should have included it in the PR – Anthony
Here is water specific heat J/kg K from zero salinity to saturated 120 g/kg and 0°C to 120°C at constant pressure. http://web.mit.edu/seawater/Seawater_Property_Tables.pdf The variation is ~500 J from the minimum for saturated salt water. The lower mass water column of a delta just means it contains less energy.
Something to keep in mind when reading any studies like this is that the $$ amount of the the damage done is meaningless when talking about how strong a weather event was. (No, I’m not saying this study was doing that.) That goes double or triple for a press release. The strength of the storm itself is what matters, not the value of the property damaged.
The 1 meter depth water temperature at Lake Michigan Data Buoy 45002 at the moment is 71°F, not warm by hurricane standards.
Matt says:
“i[f] fresh water has such a major impact on huricanes, why don’t we ever see huricanes forming on the very large fresh water bodies?”
A good question that ironically has a simple answer – ironic because of the inherent complexity of a tropical cyclone. Tropical cyclone formation (and propagation) depends upon a multitude of converging variables within a relatively confined region (Earth-wise). To assert that one variable (e.g., freshwater or the layering of it within saltwater) is able to influence this formation significantly (e.g., “tropical cyclone intensification rate is nearly 50% higher”) is like claiming that carbon dioxide drives the global surface temperature anomaly – whatever that is (e.g., “The eventual response to doubling preindustrial atmospheric CO2 likely would be a nearly ice-free planet”) – http://tinyurl.com/5w7no9 (Columbia University link to Hansen et al paper from 2008).
I agree with Dan J’s comment, “Using the one point for Omar as an indication of general hurricane behavior is like defining a line using one point. You can make it go wherever you want.”
The paper’s review of tropical cyclones from 1998 to 2007 and casual division of these events appears unnecessarily limiting. The separation between barrier layer (freshwater layering within saltwater) events and non-barrier layer event was based largely upon regional, ocean temperatures, which fails to account for the presumed and increased mixing (both at the air-sea interface and across barrier layers) that occurs as a tropical cyclone propagates along its path. The paper appears to have been a capable post-mortem of a tropical cyclone’s air-sea enthalpy flux transfer (along an observed string of values), but it’s a bit ambitious to make the bold claim it made regarding intensification – be it true or not, at this point.
Tom Kissinger says: “Remember that TAMU gave us cold fusion.”
I thought that was Stanley Pons and Martin Fleischmann at the Melvin Dumar Institute of Technology at U of Utah. Right?
Matt says:
August 14, 2012 at 4:54 pm
I fresh water has such a major impact on huricanes, why don’t we ever see huricanes forming on the very large fresh water bodies?
================================================================
As I understand it, the weather pattern that preceeds and results in a huricane requires days over warm water to develop. That’s why they form close to the Equator. There just aren’t any fresh water bodies large enough for the pattern to form. As I understand it, the study is talking about hurricanes that have already formed or are on the brink of forming getting a “boost” from a warmer fresh water large river discharge that has reached the ocean but not yet mixed.
Things that make you go, Hummm?
http://www.srh.noaa.gov/mfl/?n=okeechobee
Interesting and semi on topic 🙂
jorgekafkazar says:
August 14, 2012 at 6:06 pm
Tom Kissinger says: “Remember that TAMU gave us cold fusion.”
I thought that was Stanley Pons and Martin Fleischmann at the Melvin Dumar Institute of Technology at U of Utah. Right?
From Wikipedia on Cold Fusion–“On April 10, 1989, a group at Texas A&M University published results of excess heat…”
I think you are much more right than I am, but TAMU did make a claim of cold fusion. tom
In the case of the MIssissippi, large strong storms tend to weaken as we saw with Katrina, Carmen, Lily, ect since they pull in dry air because of their size. However the compact storms can intensify rapidly since because of their small size, the enhanced convergence near the coast and the fact the storm is not large enough to pull in dry air, can see quick intensification until landfall, especially when hitting almost perpendicular.
I dont know if it has as much to do with fresh water as it does heat content, and size of storm, Remember to maintain a large powerful hurricane takes more energy than a smaller “fist of fury” I have tried to get these ideas across by stressing the pressure as much as measured 1 minute wind in the development of the power and impact scale.
In short, the weaker the storm, the more it can intensify around land… because its like a guy walking into a gym with a 75 lb bench press and starting to lift a little and up goes his bench. The big strong guy with the 400 lb bench, needs ideal conditions to stay that strong. The same regimen that would make a little guy strong, would make the big guy weaker. You see this in nature all the time, A small plant will respond quickly but a larger plant needs more to sustain itself
Good idea though and one worth watching
I think that most people don’t realise how much the earth’s spin and the Coriolis effect is responsible for our weather and climate. Hurricanes, deserts, water currents, tides, etc. all happen because of the earth spinning at an angle on its axis, as our planet goes around the sun (and our moon goes around the earth).
Try this experiment. Get on a playground merry-go- round with a ball, and spin the merry-go-round anti-clockwise. Now try throwing the ball straight and directly opposite to where you are. Of course, from the POV of your opposite side, the ball veers left instead of straight (from your POV, the ball veers right). This is exactly what is happening with our planet: as the earth spins, air and water currents veer to the right due to the Coriolis effect and are responsible for our weather patterns and climate. Hurricanes are a good example of the Coriolis effect at work. Anthony and team, maybe you could do a little science video showing how the Coriolis effect creates hurricanes.
So please stop blaming CO2! CO2 is a harmless gas that plants need to make food. The only dangerous gas on this planet that kills people is the hot air coming out of the mouths of AGW alarmists.
Thanks, gentlement, especially, Anthony, and Willis. Interesting reading.
Commenters ask about hurricanes over fresh water bodies, but what about hurricanes over the central planes? 🙂 Seriously, Tropical Storm Erin in 2007 limped across Texas and roared back to life stronger than over the gulf once it got over Oklahoma City with an obvious eye, 80 mph winds, and extensive flooding with 10 inches of rain. Mr. Bastardi, got any insights? I’d be happy to hear about it.
For reference, http://www.srh.noaa.gov/oun/?n=events-20070819
http://www.thedailygreen.com/environmental-news/blogs/hurricanes-storms/oklahoma-cyclone-55041201
The official PDF report: http://www.nhc.noaa.gov/pdf/TCR-AL052007_Erin.pdf
http://en.wikipedia.org/wiki/Tropical_Storm_Erin_(2007)
Myron Mesecke says:
August 14, 2012 at 10:03 am
Yet Katrina weakened from a Cat 5 to a Cat 3 as it approached New Orleans. Where a lot of fresh water was coming out of the Mississippi river.
The same for Ivan. Andrew didn’t have a fresh water period and gutted everything in it’s tiny swath, Hugo jumped to a higher strength as it crossed the Gulf Stream, and Camile was a monster all the way in. I’ve read that it rode a line of warmer water coming north past the Yucatan and strengthened the entire route.
So it would seem that we have the example of one Omar storm that went near some fresh water. Unfortunately we don’t have another Omar storm that didn’t go near some fresh water, to compare with that one to show what difference the fresh water made.
There’s nothing like doing a different experiment, and having no default baseline experiment to compare it to; simply wonderful scientific technique.
Solution is to never ever name another storm Omar, and specially ones that are going to go near fresh water. Problem solved.
Note: The Coriolis effect forces moving objects to veer to the right in the nothern hemisphere; in the southern hemisphere moving objects veer to the left.
When Hurricane Andrew went thru Homestead, FL and then crossed the Everglades which is fresh water it weakened.
A primary difference between Salt Water and Fresh Water aquariums is that in salt water we can utilize a device called a Protein Skimmer which uses the surface tension qualities of salt water to produce a froth of protein lined bubbles called “skimmate”.
You cannot use this device in fresh water. It is a clear example that the surface qualities are very different.
Its probably a marine aerosol effect. Ocean salt water produces a lot of fine atmospheric salt particles, which fresh water obviously doesn’t.
Its known that aerosols reduce hurricane intensity significantly and aerosol seeding has been investigated as a means of reducing hurricane intensity.
http://www.wmo.int/pages/prog/arep/wwrp/new/documents/MOD.Golden_USA.pdf
Looking at satellite pictures of developing hurricanes there is no fresh water body big enough in the hurricane latitudes.
More data needed, send more money.