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1、Working with atmospheric CO2 measurements in the classroom1. AbstractThe goal of the SchoolCO2web is to give pupils more insight into the carbon cycle and the fluctuations of CO2 in the atmosphere. This is a multidisciplinary topic, which includes mathematics, physics, chemistry and biology. Pupils
2、also learn how to extract valuable information from a large dataset by means of spreadsheet programs and statistics. Data analysis is an important skill within scientific research. Thats why this project creates a bridge between highschool and university. Moreover, you bring science closer to the pu
3、pils, because the measurements take place on the schools themselves and because the measurements might be useful within scientific research.The SchoolCO2web is a European network of schools. This emphasizes the international nature of the greenhouse gas science and opens up possibilities for project
4、 cooperation between pupils from different countries.2. Atmosperic CO2 cycles in a nutshellThe higher you get into the troposphere (0 -16 km), the more mixed the air becomes. So if you want to establish the average CO2 concentration in the air, which is also representative for a larger area, its imp
5、ortant to measure at a high location. The measuring station at Mauna Loa (Hawaii) is a good example. It is located at a vulcano at an altitude of 3400 m. The red line in figure 1 shows the monthly average CO2 levels as measured at the station. As you can see, the CO2 levels are oscillating over a pe
6、riod of one year. These are seasonal effects, due to the increased fixation of CO2 of plants from May until September at the northern hemisphere. As a result, the atmospheric CO2 drops with a few ppm. The black line shows the monthly average levels of CO2 corrected for seasonal effects. During the l
7、ast years, the average CO2 level increased with almost 2 ppm per year. This rize is due to the combustion of phosile fuels.The closer you get to the earths surface, the less mixed the air becomes. The atmospheric CO2 levels close to earth fluctuate a lot as a result of photosynthesis by plants and r
8、espiration by animals. We can clearly see this fluctuations within the measurements of the SchoolCO2web. In figure 2 you see the CO2 levels of the Carl- Zeiss-Gymnasium in Jena (DE) and the Maartenscollege in Haren (NL) from the 10th until the 14th of November. You can make Figure 1 Average monthly
9、CO2 levels at the Mauna Loa stationFigure 2 Atmospheric CO2 levels at the Carl-Zeiss-Gymnasium in Jena (DE) and the Maartenscollege in Haren (NL)these kind of graphs yourself with the SchoolCO2web tool which you can find on the Carboschools website. Chapter 3 contains a tutorial on how to use this t
10、ool. The grey and white areas of the graph represent the night and day respectively. Especially during the 13th and 14th of November, you see a big rise of CO2 during the night and a drop during the day. This diurnal cycle of CO2 is a result of two main processes: the diurnal cycle of vegetation flu
11、xes (photosynthesis during the day and respiration during the night) and the diurnal cycle of the boundary layer height. The boundary layer is the air layer near the ground affected by diurnal heat, moisture or momentum transfer to or from the surface. The larger the boundary layer, the more atmosph
12、eric mixing of air (and thus CO2) takes place. During the day, the boundary layer is ofter larger than during the night. The reason for this is that during the day when the sun heats the earth, the earth emits heat to the air. This evokes turbulence and mixture of surface air layers with layers high
13、er in the atmosphere. During the night the earth cools down rapidly. As a result, the air close to the surface cools down. But the higher air layers are still warmer and function as a blanket to prevent mixture of the air. We call this the inversion effect. The result of this effect is that all the
14、CO2 exhaled by organisms accumulates in the surface layer. Although we saw a strong inversion during the 13th and 14th of November, this inversion is almost absent during the 11th and the 12th of November. Why is that? Figure 3 reveals the answer. This time, the graph only shows the CO2 levels of th
15、e Carl-Zeiss-Gymnasium. A right y-axis is added with the wind speed. During the first days of the period, there was a lot of wind. This wind causes the atmosphere to mix and thus prevents inversion. During the last days there was hardly wind, so inversion occured. 3. Tool to download measurements of
16、 the SchoolCO2webWithin the SchoolCO2web a tool has been developped to download or graphically display the CO2 and weather measurements of the SchoolCO2web. This tool can be found on the Carboschools website www.carboschools.org, on the SchoolCO2web section. Operation of this tool is quite easy. Creating a graph exists of the following steps: 1.Select the parameter you want to display on the left Y-axis (right now the lab
