Team Bee Hurricane Response

Posted by Matt G. at 17:17 09212008
Some sites I found so far:

  • A paper by Flather (1993) about storm surge prediction model for Bay of Bengal (has some useful information)
  • The hurricane model by K. Emanuel (1998?) that I spoke of - a reference paper is available here and the model itself and a [potentially useful, but maybe overkill] hurrparam.txt file that lists the model imput parameters can be obtained here
  • Some SLOSH Model information: "The SLOSH model uses time-dependent meteorological data to determine the driving forces of a simulated storm. These data are as follows:

Central barometric pressure at 6-hour intervals.
Latitude and longitude of storm positions at 6-hour intervals.
The storm size measured from the center (eye) to the region of maximum winds. Wind speed is not an input parameter, since the model calculates a wind-field for the modeled storm based on meteorological input parameters.
The height of the water surface well before the storm directly affects the area of interest is also required. This initial height is the observed water surface height occurring about two days before storm arrival. Astronomical high tide was also set in the model."

  • Paper on Hurricane Gloria

PD (Power Dissapation) is a measure of the destructive potential of tropical cyclones
- Actual monetary loss from storms rises roughly as the cube of the wind speed

Maximum sustained wind speed is defined as the one minute avg wind speed at an altitude of 10m. Power Dissapation also depends on surface drag, surface air density, and the surface area affected by and lifetime of the storm

- Theoretically, peak wind speed from tropical storms should increase ~5% for every 1oC increase in tropical ocean temperature

Appropriate measure depends on surface temperature and a whole temperature profile of the troposphere

- Other factors- vertical wind shear, temperature distribution of the upper ocean

All from

Andreas: This is a good start, and that Nature paper (link does not work) is a very recent work that sparked much interest among policy maker in the national global change debate. I wonder if the temperature changes you cite above is for global warming scenarios … or if this is something you could actually use to aid Lewes residents in decide if and/or when to evacuate. I feel that you are a little lost in the details of one paper. What is the larger picture? What can presently be predicted well? What can presently be predicted only with dificulty? What is a prediction? How are predictions made? The recent landfall of Ike and the reporting of it in the media should give you a tremendeous amount of material to work with here. For example:

The evacuation orders were prompted by the National Weather Service stating (CNN): "All neighborhoods … and possibly entire coastal communities … will be inundated during the peak storm tide," the weather service warned. "Persons not heeding evacuation orders in single-family one- or two-story homes will face certain death."

Dack 9/15 18:00 "…computer models have been developed that enable the prediction of storm surge levels along the coast, given data on wind velocity, wind distribution, and storm center velocity" and "Accurate forecasting of storm tracks is more problematical because of the numerous variables involved and the erratic paths hurricanes sometimes take" taken from
Also…"the evolution of hurricane intensity depends mainly on three factors: the storm’s initial intensity, the thermodynamic state of the atmosphere through which it moves, and the heat exchange with the upper layer of the ocean under the core of the hurricane" taken from
So it would seem that storm path/landfall location is more difficult to predict reliably than storm intensity, according to experts. Based on this, and the fact that I was barely able to find a few papers based loosely on studying the effects of friction on wind over land and sea, I venture that in order to advise an evacuation we as scientists need to know at least some information relating to the aforementioned variables related to predicting storm intensity, storm surge and friction from land acting on hurricanes in order to make an educated model of the storm. For our scenario we'll want to know the coefficients of friction of marshes and sparsely forested grasslands.

Andreas: Yes. You are moving in the right direction, but what exactly is the essence of "… computer models have been developed … " We all have computers, and we all can model x(t)=a+b*t where x is a predicted value of a key variable at some time t based on "known" or "assumed" constants a and b that we may have determined from a set of some prior observations via least squares, say. This is certainly a computer model, right? Is this what is done, perhaps? Could this work to predict a variable related to hurricanes or storm surges? Is this what Emanuel (1999) does? Is this the way storm surges are predicted?

Brian 9/15/08 Monte Carlo-type simulations are pretty standard fare in weather forecasting, aren't they? A brief scan of the literature regarding hurricane predictions turns up a lot of hits about Markov Chain Monte Carlo approaches ( MCMC ). Not being familiar with Markov chains, I found the wiki on it and it looks like the key of it is that it's a stochastic process where each timestep result is dependent solely on the immediately preceding timestep and that timestep alone. That would make sense. If storm intensity is the easiest to predict and prediciting storm track is somewhat more difficult, then it would make sense that storm surge is going to be very difficult to predict. I don't have any details yet, but as Ike was approaching, I recall a lot of talk about how the Galveston area typically has very high storm surge in hurricanes due to the area's bathymmetry. Obviously, if we don't know the storm track, we can't know the bathymetry in question. Anyway, it makes sense that calculated storm surge is going to be derived from storm intensity, storm size, and storm track, all of which have some uncertainty associated with them. Speaking in terms of probability then, the magnitude of uncertainty associated with storm surge should be roughly a product of these three uncertainties, plus whatever other factors we might not be taking into account.

Brian 9/21/08: Here's a bunch of links to useful/pertinent sources:

Wind surge equations based on bathymetry and a Java applet to play with:

Comparison of CEST and SLOSH (abstract)

Prediction of storm surge and surge deviation using a neural network

Storm surge simulation using wind-wave-surge coupling model

Comparisons of HRD and SLOSH surface wind fields in hurricanes: Implications for storm surge modeling

Nice background about storm surge, SLOSH and ADCIRC models

US Army Corps of Engineers training module on storm surge:

Interesting master's thesis comparing statistical methods to SLOSH, also has some background on why SLOSH superceded SPLASH

FEMA overview page about SLOSH, and description of Hurricane Evacuation Studies (HES)

Simple description of SLOSH and access to some data:

SLOSH surge predictions vs. actual for Gloria in mid-atlantic

Specialized model for handling the case of complex linked channels

The following link is a FEMA Powerpoint presentation of storm surge modeling and SLOSH. It mirrors in many respects the Powerpoint presentation that we're trying to put together ->

Amy: This site has some good finite rules for when to evacuate:

“If the low end of predicted storm surge exceeds the highest floor of your house, definitely evacuate.” I think as city officials we would perhaps be a bit more conservative- if Lewes has a 4m elevation, if the predicted storm surge has a minimum of 5m perhaps? I don't know if we should go so far as to say that though

Interesting- Milford flood and water plans

Fictional account of evacuation mixed with real plans

NOAA student- teacher exercise on storm surge

Brian 9/22/08: This is a very useful app that displays past hurricane data, also a link to a Google Earth kmz file of the same:

Brian: 9/22/08 I went hunting through historical data and put together some files that we should all find useful:

A list I compiled of notable storms that affected Delaware, 1850-2007 (a subset of the exhaustive Wiki page on the subject):

A Google Earth file showing the tracks and intensities of those storms:

A list and brief desc of the four storms that caused the most significant surge on the DE coast according to Wiki descriptions:

An image file I created showing those four storms - this may be good to put into our presentation somewhere?

An interesting view of bathemetry near the DE coast, from NASA Blue Marble data:

Brian 9/23/08: Why Ike's storm surge was much lower than expected - the course altered a few hours before landfall:

Brian 9/24/08: Check "SLOSH Data Summary" under the appendices for a detailed description of what goes into SLOSH:

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