A podcast is a an audio file published on the web. The files are usually downloaded onto computers or portable listening devices such as iPods or other players.
Read more about podcasting from webcontent.gov
… Interested in a virtual field trip to one of four estuaries around the country next month? We'll tell you how you can participate.
… And where exactly is the point called 'Four Corners', the only place in the U.S. where four states meet up? It's exactly where it's supposed to be.
It's Wednesday, April 29th, 2009, and those stories are coming up today on Making Waves from NOAA's National Ocean Service.
Our first story today is about a really cool program called EstuaryLive. Each year since 2001, NOAA and the National Estuarine Research Reserve System host a series of live Web casts from estuaries around the country with a different theme each year. You can think of it as a virtual field trip.
This year, thousands of elementary, middle and high school students will join scientists in the marshes and bays of four estuaries to learn about the impacts of climate change on the nation's coasts.
The dates for the broadcasts this year are May 1st and 15th, and I'll give you some more details about where to go to learn more in just a minute.
But first, what exactly is an estuary? Well, it's the place where fresh water meets the sea. Estuaries are popular places for animals, birds, and fish… these bodies of waters and surrounding wetlands are sources of food, a place to breed, and migration stopovers. And estuaries are pretty important to humans too. We rely on these areas for food as well, and for recreation, jobs, and to protect our coast from ocean storms and erosion. We humans also like to build cities on estuaries – of the 32 largest cities in the world, 22 are located on estuaries!
The estuaries featured in the EstuaryLive broadcast are part of the National Estuarine Research Reserve system, a partnership between NOAA and coastal states. These special areas form a protected network of estuaries around the country covering over one million acres of land and water.
This year's Webcast will consist of two 30-minute segments from three reserves on May 1st. Those three reserves are the Hudson River Reserve in New York, South Slough [slew] Reserve in Oregon, and Padilla Bay Reserve in Washington. And on May 15th, the Webcast will focus on Weeks Bay Reserve in Alabama.
During the broadcasts, scientists at the reserves will talk about subjects ranging from the animals and plants that live in their estuary to the physical dynamics of tides and rivers and the mingling of fresh and salt water. And as we mentioned, this year's special focus area is climate change, so they'll also discuss topics like rising sea level and warming water temperatures.
While there'll be some students actually on location at the different reserves, most students will participate over the Internet. Students can e-mail questions to the scientists, who will answer on air or by e-mail after the presentation. And all of the programs will be archived on the Web for later viewing if you miss it – and that goes for the upcoming broadcasts and all past EstuaryLive programs. The place to go to check out the archive, and to register for the EstuaryLive program is www.estuaries.gov.
And while you're at estuaries.gov, you'll notice that EstuariesLive is just one of many resources on the site for students, teachers, and for anyone interested in learning more about estuaries. In addition to videos, you'll find complete classroom curricula, quizzes, an educational game and many other resources. It's a fantastic site, so be sure to check it out. Again, the place to go is www.estuaries.gov. And if you like audio podcasts, which I'm hoping you do if you're listening to this… you can hear an extended interview with estuary experts in the May 22 edition of Diving Deeper, the sister podcast of Making Waves. And that's at oceanservice.noaa.gov.
You might have caught a story in the news this past week about the Four Corners, the only place in the U.S. where four states meet up…Arizona, New Mexico, Colorado, and Utah. Well, there was some confusion over the position of a monument at Four Corners that marks the spot where the four states meet. Some reports claimed that the position of this marker was off by two and a half miles. Well, it isn't. In fact, it's exactly where it's supposed to be.
So here's the problem: there's a widely held misperception that the boundary between Colorado and Utah – the line of longitude – is 109 degrees West from Greenwich, England. As you might remember from your school days, longitude lines are the ones that stretch from the North to South poles.
Greenwich, England is where the Prime Meridian is. It's zero degrees, the reference point from which everyone today measures how far East or West they are. Note that I said 'everyone today' has adopted Greenwich as the Prime Meridian. It hasn't always been that way, as you're about to find out.
Now imagine you trek out to the desert to visit Four Corners with a handheld GPS receiver. At the site, you check your position. You expect it to read 109 degrees West. But it doesn't. It reads 109 degrees plus a little more. What gives? Well, it turns out that the boundary between Colorado and Utah – the line of longitude - wasn't measured from Greenwich when it was recorded back in the 19th century. And it's not – and never has been – at 109 degrees West.
We asked Chief Geodetic Surveyor Dave Doyle of NOAA's National Geodetic Survey to explain:
[Doyle] "The reality is that that was never the definition of the Western boundary of Colorado, [or] the Eastern boundary of Utah. It's actually defined as being 32 degrees longitude West of the Washington meridian, Washington referring to the city of Washington, DC. And the meridian referenced in that statute is now what we refer to as the Old Naval Observatory, in downtown Washington, DC. The Old Naval Observatory has a longitude that is not exactly 77 degrees West of Greenwich. It's 77 degrees, three minutes, and, depending on how you define it, four -- almost five -- seconds. So when you add 32 degrees to that, you should come up with 109 degrees, three minutes, and roughly five seconds. And that three minutes and five seconds of longitude is roughly two and a half miles. And that's where we believe the original discrepancy came from. Someone believed it should be 109 degrees longitude, when that was never how it was statutorily defined."
And this is where the misunderstanding comes from. The longitude of the position of the Four Corners monument is based on a measurement taken in 1875, and the reference point used was in Washington, DC. This was before the Prime Meridian was adopted as the standard of measurement by the whole world.
[Doyle] "It was very common at that time for countries or small groups of countries to have their own local longitude orientation. So the French had the Paris Observatory, the British used Greenwich, the Germans used Potsdam…and on and on. So we had our own national meridian."
Now, if you use today's modern tools to measure that distance from the Old Naval Observatory to the Four Corners boundary, you would find that the position of the monument is off just a bit, somewhere between 1350 and 1800 feet. That discrepancy is because the tools used in 1875 were not as accurate. And, to a lesser degree, there's also a slight variation depending on where and how you measure from the Old Naval Observatory. Doyle said that this is a common, everyday issue in the world of surveying:
[Doyle] "Many, many, many of the parcels that everybody occupies everyday are defined by descriptions, that is directions and distances, that in some cases go back several hundred years, and were measured with technologies 200 years ago that were in no way comparable to current technologies. So, it's not at all unusual to find distance, or direction or, in this case, a coordinate that is in some cases, significantly different if we had been given the luxury 200 years ago of doing this with contemporary technology such as the Global Positioning System."
So now you might be saying to yourself, 'Aha, so the monument isn't in the right spot after all.' But actually it is. And this is the last piece of the puzzle. Even though the marker is not exactly 32 degrees West of the Naval Observatory when measured with today's tools, that's now irrelevant. And that's because the four states that make up the Four Corners all agreed long ago that the monument, well, marks the spot. This is what's important to keep in mind about surveying: it's about precision and science, but it's also about history and statutory law. Doyle said that the original 1875 surveyor, a man named Chandler Robbins, got it right. The Four Corners monument is exactly where it's supposed to be:
"It's in its true location. It's exactly where the surveyor at the time placed it. Given the technology that he enjoyed, given the conditions that he had to work under, Mr. Robbins placed that monument exactly where he was directed to, which was 32 degrees West of the meridian of Washington. What he lacked was the contemporary surveying technology that we have today. So in his mind, and based upon all of his observations, and his calculations, he placed the monument exactly 32 degrees longitude West of the Naval Observatory. And that is exactly where it should be, even though its numerical difference today might differ by 1800 feet, or perhaps even if it were two and a half miles, it would become irrelevant, because the monument has subsequently been accepted by all four states as defining the legal boundary, and therefore, it is the monument of record, and in surveying monuments control."
Special thanks to Dave Doyle of the National Geodetic Survey for helping us to sort this out. If you'd like to learn more about geodetic control monuments (better known as bench marks), how geodetic surveying is done today, or about the other roles and missions of the National Geodetic Survey, head over to geodesy.noaa.gov.
And let's give Dave Doyle the last word today on this story...
[Doyle] "Certainly it's been interesting to deal with this issue. And what we're really hopeful for at the NGS - the National Geodetic Survey -- is that this will inspire others to take a little bit more interest in geography and spatial relationships, and perhaps investigate some of the work that's being done by, not only NOAA and the National Geodetic Survey, but in many other institutions around the country and around the world."
That's all for this episode. If you have any questions about this week's podcast, about the National Ocean Service, or about our ocean, send us an email at email@example.com.
Let's bring in the ocean....
This is Making Waves from NOAA's National Ocean Service. We'll be back with our next episode on May 13th.