Stories from the Coast - July 9, 2001

Long-range CODAR is Outta Site

This weekend, graduate student and CODAR warrior Josh Kohut called in some great news. After several setbacks, the long-range CODAR showed much promise. In only a couple of clicks from his home Mac, Josh noticed we were getting the best coverage from our new long-range CODAR network than we had ever seen before.

Our first long-range site was setup last summer in Loveladies, New Jersey. Loveladies is right in the middle of the New Jersey coast. Even though coastal current maps require at least two sites, we were able to use the single site to look at the differences between the day and night converges of the radars. We also tried to find the least noisy frequencies to improve our nighttime coverage. Long-range systems use frequencies close to the AM band on the radio. These bands can be very noisy and tend to be affected by the Earth's ionosphere, just like your AM radio is. This was only the first of many challenges to face the new long-range network.

Two new sites were added over the winter, one in the far south of New Jersey at Wildwood, and the other in Sandy Hook, the far northern end of the New Jersey coast. Now that the extremes of the state are covered, an additional two sites will fill in the holes in the future.

Not far from an abandoned Loran-A tower, the Wildwood site went operational during the cold of winter. This became the second long-range system in the network, allowing the first long-range current maps to be generated for the coast of New Jersey. The site is at the Coast Guard Loran Support Unit's station, run by Gary Thomas, the XO. Gary gave us a prime spot right next to their abandoned Loran-A tower which we hope to be able to use in future experiments. Lt. Cdr. Al Yelvington, a Coast Guard radio guy that likes anything geeky, has already saved us several long trips to Wildwood. Al loves ocean science, and he even has one of those home satellite receivers on his PC from which he has been pulling down imagery from satellite similar to the birds we track. So if all this COOLroom technology fails us, we can always call Al.

At Sandy Hook, Richard Wells greased the paperwork wheels for us. And from then on, the installation went quickly. Bruce Lane, a park ranger, walked us around the national park, and we settled on a site next to an abandoned Nike Missile site from the Cold War. It was not an easy installation. We had to run a mile of antenna cable through a jungle of poison sumac. It took five scientists to accomplish this on a hot day in the early spring. Most survived.

So, with the first 3 sites operational we are trying to tune them up. Looking for the best broadcast frequencies and processing tradeoffs in the real-time data make for quite a challenge. The R/V Endeavor from the University of Rhode Island ran several Acoustic Doppler Current Profiler sections for us that are really going to help us calibrate the data. Meanwhile, Don Barrick and Belinda Lipa back at CODAR Ocean Sensors are taking a second look at the data coming. They are trying different processing routines and combining the data in various ways. Don called in Friday with the big step - switch to 3-hour averaging. All of our real-time data till then was 2-hour averaged.

Josh made the switch early Saturday, and by midmorning, we were getting the biggest CODAR total vector fields we have ever seen, covering the entire coast of New Jersey (see the image above).

Long-range CODAR still has a long way to go. But Josh recently converted the data into netCDF format for for the modelers who will be able to assimilate the data into their ocean forecasts. We can not wait to watch their jaws drop when they show up tomorrow. It's more data that they've ever seen before!