Posts Tagged Egypt

Lake Erie Is My Laboratory

I recently published another scientific paper in the peer-reviewed journal PLoS ONE. Since PLoS ONE is Open Access, anyone can read the paper without a journal subscription:

Using Wind Setdown and Storm Surge on Lake Erie to Calibrate the Air-Sea Drag Coefficient

The publication date was August 19, 2013. Here is the full citation:
Drews C (2013) Using Wind Setdown and Storm Surge on Lake Erie to Calibrate the Air-Sea Drag Coefficient. PLoS ONE 8(8): e72510. doi:10.1371/journal.pone.0072510

The purpose of the research was to validate the results of the COAWST ocean model (Coupled-Ocean-Atmosphere-Wave- Sediment Transport Modeling System) with actual observations of storm surge. The paper has a lot of figures that we call “spaghetti plots;” these are charts that show multiple time series on a single plot. We call them spaghetti plots because they look like a bunch of noodles stretched from left to right across the page:

Figure 11. December 2006: Wind setdown and storm surge, with experiments E4, E18, E21, and E23. From Drews (2013).

Figure 11. December 2006: Wind setdown and storm surge, with experiments E4, E18, E21, and E23. From Drews (2013).

In Figure 11, the black line represents the observations of water level taken at the Fermi power plant at the western end of the lake, and at Buffalo at the eastern end of the lake. The colored lines represent various model runs. The goal here is to get the colored lines to match the black line as closely as possible. This is done by adjusting the COAWST model parameters in a sensible manner. Adjustments include: the numerical formula for the air-sea drag coefficient, the bottom drag coefficient, the influence of waves, and the algorithm used to simulate wave action, and the presence of ice on the lake.

Why Lake ErieLake Erie happens to be a near-perfect natural laboratory for conducting this kind of experiment. The lake is long, shallow, and subject to strong winds from the west that cause the lake water to slosh back and forth like a big bathtub. Since the lake is surrounded by populated areas in the United States and Canada, there are many weather stations along the coastline that provide archived meteorological data. Lake Erie is also an important seaway for international commerce, and NOAA provides accurate measurements of tides and currents at major ports on the lake. I can run simulation experiments with confidence in the observations that I am trying to match.

The paper describes two windstorms on Lake Erie: December 1–2, 2006 and January 30–31, 2008. Lake Erie is 400 km long and 90 km wide. Since I don’t have a gigantic fan big enough to blow the lake water around and measure what happens, I have to wait for nature to do the blowing instead. Fortunately for me, these windstorms occur often enough to provide several usable data sets. Better yet, there were no human fatalities in either of these storms.

The potential result of the research is a more accurate model for storm surge. When building coastal defenses such as floodwalls, it is crucial to know how high the ocean will rise when the next hurricane comes ashore. The difference between building a seawall one foot higher than the maximum surge, and one foot lower than the maximum surge, can be disastrous.

Moses Crossing the Red Sea

In 2010 I published another paper on wind setdown and storm surge:
Dynamics of Wind Setdown at Suez and the Eastern Nile Delta

That earlier paper reported the emergence of a land bridge in the eastern Nile delta under certain conditions of wind speed and direction. For readers of funmurphys who are interested in Moses crossing the Red Sea, the ocean model indicated that Moses would have 4 hours to lead the Israelites across the yam suf.

At the time, I suspected that the estimate of 4.0 hours was somewhat conservative; that is, the dry passage probably would have stayed open for a longer period of time. There were several factors that we did not include in the 2010 research, such as waves and a drag coefficient more suited to coastal conditions. I had a hunch that these additional factors would increase the duration of the passage. However, the rigorous nature of scientific publishing requires that scientists cannot publish more than a few paragraphs of speculation; peer-reviewed journals require concrete results supported by evidence from observations and computer models.

The Lake Erie research provided a chance for me to test my earlier hunch. I was pleased to find that my hunch was correct; but better yet, that I could provide a revised number for the crossing time. Here it is: Moses had over 8 hours to evacuate all the Israelites from Pi-Hahiroth to safety at Tell Kedua on the other side of the yam suf. Or, for scholars who are more interested in the wind speed, an east wind blowing at 24 meters per second is sufficient to hold open the dry passage for 4 hours (the 2010 paper reported 28 m/s).

Figure 13. Corrections applied to the Lake of Tanis and the Kedua Gap. From Drews (2013).

Figure 13. Corrections applied to the Lake of Tanis and the Kedua Gap. From Drews (2013).

I like this result, because it shows that there is some engineering tolerance to the solution. Although God can of course do anything He wants to do, as an engineer I am happier with a answer in which the parameters can vary a bit and still work. The 2013 paper demonstrates that the Kedua Gap is a more robust reconstruction of Exodus 14 than originally thought.

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“Proving God” on the History channel

Wind setdown and Exodus 14

On December 13, 2011, I appeared in a TV documentary titled “Proving God” shown on the History Channel. My section of the program described how scientists investigate the narrative of Moses parting the “Red Sea” in Exodus 14. Sir Colin Humphreys and I explained how the meteorological phenomenon of wind setdown matches the Biblical account. I am providing here a transcript of what I said on the program; since this blog represents Fair Use in a scholarly setting, I can only provide a limited section of the text.

Ancient Nile delta

Figure 1. Reconstruction of the Nile delta by James Rennell, based on the writings of Herodotus. The black rectangle shows the site of Drews and Han's proposed crossing site at the Kedua Gap (30.9812 North, 32.4553 East). This is Figure 2 of Drews Carl, Han Weiqing, 2010 Dynamics of Wind Setdown at Suez and the Eastern Nile Delta. PLoS ONE 5(8): e12481. doi:10.1371/journal.pone.0012481.

Narrator: Atmospheric scientist Carl Drews of the National Center for Atmospheric Research believes Humphreys may be onto something.

Carl Drews: Wind setdown occurs when a strong wind blows over a period of time across a surface of water; and gradually the water moves in the direction of the wind, and pulls away from the shoreline, and so the surface of the ocean moves down. So what you have there is a section of dry land where there was formerly sea bed.

Narrator: Accessing the power of supercomputers, Drews has studied the effect of wind setdown in locations ranging from the Nile, and coastal England, to a pair of such episodes in the Great Lakes in 2006 and 2008.

Carl Drews: Wind setdown is observed about every 5-10 years on Lake Erie. You have these strong storms that come from the west, and they cause storm surge at Buffalo; but on the Toledo side, which is the upwind side, the large sections of the lake will be completely dry. The water will have disappeared over the horizon!

Colin Humphreys: It’s been observed that the difference in height between one end of Lake Erie and the other can be as high as 16 feet. Absolutely staggering, right? You’d expect Lake Erie to be level water, but in a strong wind, blowing for many hours – 16 feet difference!

Reconstructing the event

Narrator: Harnessing data gathered from NASA satellites, Carl Drews creates an ocean model and terrain map of the Gulf [of Tineh], to examine the possible effects of such a storm.

Parting the Sea at the Kedua Gap

Figure 2. Wind parting the waters at the Kedua Gap. The east wind creates a temporary land bridge at Tell Kedua in the eastern Nile delta. This is Figure 1 from Parting the waters: Computer modeling applies physics to Red Sea escape route, press release by University Corporation for Atmospheric Research, September 21, 2010. (©UCAR, Illustration by Nicolle Rager Fuller.)

Carl Drews: I used geological maps, geological surveys, and sediment cores to reconstruct the configuration of lagoons and rivers that were [present] during the Exodus period. Then I ran this on the ocean model with a supercomputer and applied a digital wind to this, a wind blowing at 63 miles per hour. It would be difficult to walk into that kind of wind, but it’s possible. You can make forward progress.

[break]

Narrator: Combining the Biblical account of the crossing with the scientific modeling, Drews constructs a timeline that matches the conditions described in Exodus: the perfect storm.

Carl Drews: The Bible says that this occurred over a night, so – wind blowing for 12 hours suddenly stops, and I find that the waters part, and stay parted for a period of 4 hours. Then they rush back together again.

Narrator: But even given 4 hours to cross the exposed land bridge, it would have been impossible for 2 million Israelites to traverse the Red Sea and escape. Does the scientific evidence disprove the Bible account?

Carl Drews: That would be a lot of people to get through a small space in just 4 hours.

Colin Humphreys: This number is unbelievably large! A lot of people think the Exodus story is made up.

[Humphreys goes on to explain that the word ‘eleph in ancient Hebrew (Strong’s Concordance H505) can mean “thousand”, or it can mean a “company” of soldiers – about 10 fighting men. This re-calculation leads to a total number of 20,000 Israelites of all ages, a much more manageable group of people.]

Narrator: If Humphreys’ new calculation is accurate, it bolsters the case that the Red Sea miracle really did happen.

The return surge

Narrator: From cosmology, and archaeology, to oceanography, researchers from a variety of scientific disciplines have launched a global search to discover quantifiable proof of God. Sir Colin Humphreys and Carl Drews are looking for evidence that will prove that the events described in the Bible actually occurred. Using precise calculations, along with complex computer modeling, each man has detailed a perfect storm scenario which they claim could have caused the parting of the Red Sea, just as described in the book of Exodus.

Tidal bore on the Qiantang river, China.

Figure 3. Tidal bore on the Qiantang river, Hangzhou, China. This image is from Wikimedia Commons at http://commons.wikimedia.org/wiki/File:Tidal_bore_at_the_Qiantang_river,_Hangzhou.jpg.

According to their theory, a phenomenon known as wind setdown caused winds of rare duration and force to peel back the waters long enough for the Israelites to make their way to freedom across an exposed land bridge. But the book of Exodus also describes the sudden destruction of the Pharaoh’s army as they chased the Israelites across the sea bed. To explain this, Drews and Humphreys point to the opposing natural force that can follow extreme cases of wind setdown.

A bore wave. The term defines the phenomenon where a tide returns displaced water with such force that it forms a giant wave of enormous power.

Carl Drews: When the wind stops, suddenly that water comes back again, and you would get these walls of churning water, thundering in! and crushing anybody who is left in the passage there.

Narrator: Drews’ calculations reveal that a wind setdown powerful enough to part the Red Sea would have unleashed a bore wave of staggering magnitude.

[break]

Narrator: Whether invoked by the hand of Moses, or the natural reaction to wind setdown, a bore wave of this force would have obliterated the Pharaoh’s army in an instant.

Carl Drews: Suddenly they hear this roaring in the distance! Then they look up, and what looks like a mountain of water is bearing down on them from both sides, and from the back.

Colin Humphreys: It sweeps these people back into the sea, which is precisely what the book of Exodus says. So even this little detail in the Exodus fits what we know from modern science.

Theology – faith and science

Narrator: But while these natural phenomena offer a scientific explanation for the events described in Exodus, that alone does not prove God.

Anglican cross

Figure 4. Anglican cross. From Letterkenny Cathedral, by Scolye17 at Wikimedia Commons: http://commons.wikimedia.org/wiki/File:Celtic_Cross_Letterkenny.jpg

Carl Drews: It could be that Moses got very, very, very lucky. It could be that he was a very, very good weather forecaster.

Colin Humphreys: So you may say, Why do we call this a miracle? The reason is because of the timing. They would have been slaughtered!

Carl Drews: It’s a very unlikely event, to happen on a certain night just when you need it. If Moses is that lucky, we should all bet on Moses! (he chuckles)

Colin Humphreys: So I think it’s the timing that shows the hand of God at work.

Narrator: Both Drews and Humphreys agree that the evidence of God is not in the natural events themselves, but rather in their miraculous timing. Ultimately, it is beyond the powers of science to explain how a once-in-a-lifetime storm occurred at the exact place and time to rescue the Israelites.

[break]

Narrator: While their work has narrowed the divide between science and the Divine, these scientists admit that, for the moment, faith is needed to span the last gaps.

Carl Drews: The scientist should be humble and realize when their science cannot go into the supernatural. We only study the natural. So I study the movement of the wind and the water. According to the Bible, God sent the wind at the right time and told Moses to be there.

Further reading

Purchase “Proving God” on DVD from the History channel:
Proving God DVD

Our original scientific paper, published in the peer-reviewed journal PLoS ONE:
Dynamics of Wind Setdown at Suez and the Eastern Nile Delta, by Carl Drews and Weiqing Han, August 30, 2010.

A story by reporter Anna Maria-Basquez in the Denver Catholic Register that explores the theology behind the research:
Boulder scientist’s research affirms parting of the Red Sea, December 15, 2010.

An article that I wrote for Weatherwise magazine to explain the research to a general audience:
Could Wind Have Parted the Red Sea? January/February 2011.

Other news coverage:
Parting the Sea.

Proving God” was produced by Karga Seven Pictures for History.

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