To operate this visualizer first select a location, this can be done either by selecting from the "Site Location" drop-down menu or by selecting one of the red squares on the world map. Next select the desired time span for data coverage from the "Time Span" menu. Finally, select from the different data options provided through the "Data Options" menu. To display the corresponding graph for these selections then press the "Show Graph" button which will bring up a new window. Descriptions for these controls as well as the different data options follow.
Controls
Site Location
Select a location on the globe either by clicking on one of the red squares on the globe or by selecting a location name from the "Site Location"
Time Span
From this menu one can select the years to be represented in the graph displayed. This can either be for all of the years available or for individual years over the available range.
Data Options
From this menu different data display types can be selected. Descriptions for these data types follows:
- CO2 Concentration: This is the monthly mean of the CO2 concentration in the atmosphere as recorded at one ofthe measuring stations around the world. The data shows peaks and valleys that are associated with activity in the biosphere, releasing CO2 as organic material decays and absorbing CO2 as plant life grows. CO2 concentration is measured several times a day but the monthly mean is used to average out short-term fluctuations. The CO2 concentration is measured in parts per million. 350 ppm translates into 350/1000000 = 0.0355% concentration in the air we breathe. This same air has more than 2000 times more nitrogen (N2 at 78%) and more than 500 times more oxygen (O2 at 20%).
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- Trend Subtracted: In order to better recognize the peaks and troughs of the CO2 curves, the yearly mean CO2 concentration was subtracted. The effect of this subtraction simply centers the data around zero such that the peaks are positive and the troughs are negative. Next, a spline curve was fit to the data to average out the peaks and troughs. Therefore, the resulting curve has peaks and troughs that are 'flatter.'
- Sine Subtracted: The CO2 concentration data appears to have a simple sine curve with values oscillating up and down. To compare with a sine curve, the trend is first sutracted from the data to flatten the baseline for the oscillations. Then a sine function was fit to the trend subtracted points. This fit was then subtracted from the data. What remains is the difference between the fitted sine curve and the trend subtracted data. The difference shows how the data departs in its behavior from a simple sinusoidal shape: sinusoidal curves are exactly symmetrical in shape, and have constant amplitude, frequency and phase.
- Typical Year Subtracted: Using the trend subtracted data, you can average the concentration data for each month and arrive at an average shape for the CO2 concentration curve showing how it typically or normally varied during the year. This typical year mean behavior can be subtracted from the trend subtracted curve. The resulting difference is called the anomaly. The graph shows how each month of each year differed from the typical behavior. Small differences show a very average year (small anomaly), Large differences show an unusual year (large anomaly).
Show Graph
Click on this button to open a new window displaying CO2 concentration levels for the different location, time, and options selected.
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