Cooperative Institute for Research in Environmental Sciences

Ocean Interactions
Ocean and Atmosphere connecting Scientists, Teachers & Students

Gilpin County School, Black Hawk, CO

Class profile: Our school is located 30 miles west of Golden, CO and 3 miles outside the town of Black Hawk. We operate on a four-day week. Enrollment is 222 PreK-5, 100 in the Middle School, and 115 in the High School. Class sizes average 15-20 students. Ms. Stevens' Earth Science students will be actively involved with the Ocean Interactions project.

Teacher: Ms. Stevens

Q & A (week 11/17/03)

1.) What happens when you finish with the last buoy?

We go home! We are steaming to the ENE right now to get to the Panama Canal.

2) What are you learning from the bottles and the CTD?

Well the CTD measures water temperature and salinity down to 1000 meters or more. This work is conducted by someone at NOAA PMEL (they aren't on the ship), and it has to do with understanding the large scale dynamical movement of the ocean waters and how much heat is exchange in the ocean depths. Also, there is some carbon dioxide chemistry and other chemistry that is conducted after the cruise.

3) Do you believe the current warming trend is the cause of natural trends or human-caused?

This is a delicate question and has sparked alot of controversy, so I need to carefully word my response. No one knows the true answer, but I have an opinion, which is partially based in my understanding of the science. First of all, many if not most earth scientists believe that the current warming trend is probably caused by carbon dioxide (and other 'greenhouse' gases) build-up in the atmosphere. This phenomena was predicted about 30 years ago, and it seems extremely coincidental that the warming we are seeing is natural. Most scientists with whom I come in contact are of the opinion that the warming trend is a problem and that the world governments should be more strongly persuing mitigation of the problem. However, the Earth System is very complex and very very difficult to model accurately. So, we cannot say with certainty that this trend is man-made. Also, the severity of the consequences are not crystal clear (that is, whether it will have a severe economical impact). As long as there are still some doubts about the cause of the warming, and as long as there are political reasons to NOT take action, then we will continue to burn fossil fuels and not change our behavior. That is human nature.

Q & A (week 11/10/03)

1. Is there any atmospheric data above the troposhere?

The radiosondes often go above the tropopause, which is the imaginary dividing line between the troposphere and stratosphere. One balloon managed to go as high as 25 kilometers (15.5 miles). As Ms. Steven's students know, the troposphere extends up to about 12 kilometers (7.5 miles), and it is mighty cold up there (minus 60 degrees Celsius!). Commercial airliners typically fly just below that height. I will send along a plot which shows the temperature profile up to 25 km.

2. How does your dissolved oxygen change along the ocean surface?

I had to ask Dr. Jan Kaiser for help on this one. Gas diffuses between the air and sea. In the case of oxygen, it is not a trace gas like carbon dioxide, but it is a fundamental component of our atmosphere. So, if an area of the ocean surface is exposed to the air for long enough, the dissolved oxygen concentration in the ocean will come to equilibrium with the atmospheric concentration (just as much mass is transported from the ocean to the atmosphere as is transported in the opposite direction). However, a number of factors can influence whether or not we are in equilibrium (saturation). For example, biological processes can remove or add oxygen to the water.

Also, 'upwelling' may occur, where cold water from the deep ocean rises to the surface. This actually occurs close to the equator as a result of the structure of the currents. It also happens near the west coast of the North and South American continents which is why the water off California is cold. Cold water has a higher oxygen saturation point, and that means that more oxygen can be dissolved into it.

Jan has seen that north and south of the equator (more than 2 to 4 degrees above and below the equator), the water and air are in equilibrium with respect to oxygen. That is, just as much oxygen is being dissolved into the water as is being input into the air.

In a relatively narrow band of water about the equator (within a couple of degrees of latitude above and below the equator), the cold water which came from the deep ocean is UNDERsaturated (at about 88% of oxygen saturation). This means that these waters will absorb more oxygen from the atmosphere than they will emit into the atmosphere.

The region near the equator (south of our current location at 110 West) is therefore a SINK for oxygen. Due to other processes, the equatorial region west of 125 West is actually a SOURCE of oxygen for the atmosphere. To me, this is interesting stuff, and I'm learning along with you students.

Ms. Steven's class wins First Place for the 'Hardest' Question of the week!

The "prize" is a lame answer!

No one on the ship measures alkalinity, hardness, or pH. However, I did learn that the pH of seawater is very stable due to carbonate reactions and is between pH 7.5 and pH 8.4. A near constant pH is actually necessary for life processes (for example, the shells of some sea creatures will begin to dissolve if the water is slightly more acidic).

The ship's Chief Engineer, Mike Gowan, showed me how the ship makes water. Did you realize that we have to make all our own fresh water for drinking, cooking, showers, etc.?

The system that is used is an evaporator....they heat the water to drive off water vapor, then move that water-laden air into a cooling chamber to condense the water back into liquid. The salt and other chemicals in the water do not evaporate with the water, so at the end of the process we are left with pure water. However, some bacteria still exist within the system, so Mike adds Bromine to kill it. Furthermore, it is important to add Bromine to give the water a little 'hardness', since soap and detergent are much more difficult to dissolve in pure soft water. In the laundry room, there is a sign that says "Only use 1/2 cup of detergent in the machines!". A little bit of soap goes a long way in very soft water.

Thanks for the questions! (Make them easier next week!)

Q & A (week 11/3/03)

1. How many barnacles are generally on each buoy and what have you been learning about these communities?

From Jeff: Over the past 3-5 years, there usually is a 'barnacle' person on board this ship, whose job it is to scrape off the buoys and analyze the size and species of barnacles which are found. This project was headed by scientists from Bloomsburg University in Pennsylvania. However, there isn't anyone here on the ship this trip doing that work. I'm a little disappointed myself, because I wanted to ask alot of questions about the barnacles. Personally, I think they are really interesting, but creepy and smelly. The contact person at Bloomsburg is Dr. Cynthia Venn. Hopefully, some of our students can learn directly from her about the barnacles.

2. How many atmospheric balloons have you released and what have you been learning as it travels through the different layers of the atmosphere?

From Jeff: So far, we have released about 40 radiosondes. As you can guess, it takes awhile to analyze all this data (and we are only about 1/2 way through with the data-taking). One of the projects we are working on this year is to use the radiosonde humidity data to help calibrate a newly-launched satellite. The satellite measures the water vapor (humidity) in the atmosphere by looking downward, while the radiosonde goes the opposite way. By correlating the two measurements, the satellite can be calibrated. Typically, the temperature and humidity profiles in the tropics are all very similar in structure. However, the NOAA ships (the Ron Brown and the Ka'imimoana) have been tending these two buoy lines (95W and 110W) twice annually for many years. Each time, our colleague from the NOAA Pacific Marine Environmental Lab (PMEL), Dr. Nick Bond, coordinates the launch of radiosondes from the ships. This includes gathering profiles surrounding entire El Nino cycles. I will send along a representative plot of the radiosonde data for you to look at.

These are 4 plots of radiosonde data.

Top Left: Temperature vs. Height (note that height is placed on the abscissa instead of the ordinate so that physical interpretation is easier to visualize). You may be able to see that at about 2 kilometers, there is a slight 'kink' in the temperature. This is normal and is called an 'inversion'.

Top Right: Relative Humidity vs. Height. Notice how rapidly the humidity decreases above 2 kilometers. However, even at 15 km, there is water vapor in the atmosphere. This water vapor that extends up high in the atmosphere is very important to our climate system.

Bottom Right: Wind Speed vs. Height.

Bottom Left: Wind Direction vs. Height. Note that the wind direction can only vary from 0-360 degrees, and in this case, the line crosses that boundary many times. When you've seen this plot a number of times, it gets easier to decipher.

3. How has the barometric pressure been changing at sea level and what is influencing this?

From Jeff: Out here in the tropical equatorial Pacific, the barometric pressure doesn't change much. Since we are so close to the Equator, we don't encounter many storms (this is partly because the Coriolis force is zero at the Equator). The barometer has read between 1007 to 1010 millibars each day.