NOAA Teacher at Sea
Onboard NOAA Ship Ronald H. Brown
July 4 – 23, 2004
Mission: New England Air Quality Study (NEAQS)
Geographical Area: Northwest Atlantic Ocean
Date: July 12, 2004
Weather Data from the Bridge
Time 8:30 AM ET
Latitude- 42 47.28 N
Longitude- 70 42.29 W
Air Temperature 17
Air Pressure 1019 Millibars
Wind Direction at surface Southeast
Why are so many methods used to measure air quality, why not just one or two simple tests?
I received an email from Paige who is a student at Obsidian Middle School where I teach. She asked how air samples are taken and how air quality is measured. Those are two very big and good questions, without simple answers. This is one of the reasons that there are several hundred scientists working on NEAQS. I emailed Paige a fairly short answer but will give a more detailed explanation here. In some of the previous logs that I have written here on the BROWN, I explained some of the techniques somewhat in detail but I haven’t given you an overview, so here we go. Great questions Paige!!!
There are many different ways that the air is sampled and measured. In some cases, such as the LIDARs, samples are not taken at all. The LIDARs shoot light through the atmosphere, some of the light bounces back to the LIDAR, and this helps to measure some of what is in the air. The ozonesonde immediately and constantly measures the amount of ozone as the balloon rises through the atmosphere.
In other cases air is sucked into tubes mounted on towers at the front of the ship and the other end of the tube goes to the scientists’ equipment. (See the pictures, the big white upside down funnel and the smaller pink upside down funnel, are two of the inlets shown.) Sometimes samples are actually stored and in others the air quality is measured immediately.
Some of the instruments measure many chemicals such as one designed, built and run by Paul Goldan and Bill Kuster. It pulls in a sample of air every 30 minutes and in 5 minutes automatically measures about 150 different kinds of chemicals. It can measure the chemicals in parts per trillion. If you made some Kool-Aid that was one part per trillion, you would mix 1 drop of Kool-Aid into 999,999,999,999 drops of water. It certainly wouldn’t taste like Kool-Aid.
Other instruments measure one or just a few of the chemicals that are in the air. Today Hans Osthoff showed me a piece of equipment that he uses to measure air quality. He uses it to measure three specific chemicals in the air. One of Eric Williams’ instruments sucks in air and measures the amount of ozone every second, 24 hours a day.
Tim Bates showed me a number of pieces of equipment which suck in air and can used to find, in real time, the size and chemical composition of the particles that are floating in the air. These particles can be so small that it may take 250,000 or more laid side by side to be an inch long. Dave Covert and Derek Coffman showed me their equipment which removes particles from the air. These particles are then collected by Theresa Miller and Kristen Schulz who will analyze them. Some of the samples will be analyzed here on the ship and other samples will be analyzed once they return to Seattle.
So why not just one or two simple tests? Why so many?
Our atmosphere and the pollution in it are extremely complicated. Even though air is about 99% nitrogen and oxygen it also contains hundreds of other chemicals which are very important. Some are natural, some are man-made and some are both. This soup of chemicals is constantly changing and moving. To be able to understand pollution in the atmosphere we have to understand all of the parts. This goes back to the elephant I mentioned a few days ago. The more parts we observe and the more ways we observe the parts the better we will understand our elephant. If you feel the elephant’s leg you learn a little, if you use your nose and smell the elephant’s leg you learn a bit more, if you use your tongue and lick the elephant’s leg you will learn even more about the elephant. Understanding the pollution in our atmosphere is similar. Each type of measurement has advantages and disadvantages but each tells you more about the pollution and the atmosphere. Combined all together they can eventually give us an understanding of the whole elephant.
We had another abandon ship drill today.
Questions of the Day
What is the ozone level today where you live?
What is the level of particles where you live?
What is the maximum limit of ozone as set by the EPA (Environmental Protection Agency)?
Hint: You can probably find these on the Internet.