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Why is there a seasonal cycle of CO2?

  1. Jun 20, 2015 #1
    I am preparing my AOSS class next semester, and I found it is interesting that there is a seasonal cycle of CO2. I looked for some information on the Internet, and this seems to do with the plants. They awake in the spring and summer, absorbing a lot of CO2 by photosynthesis and die in the autumn and winter, releasing the CO2 by respiration. But they seem to all mention that it is " in the north hemisphere ". So what happens in the south hemisphere? Is it because north hemisphere actually contains the majority of the landmasses which make the seasonal cycle phenomenon obvious?
    Last edited: Jun 20, 2015
  2. jcsd
  3. Jun 20, 2015 #2
    The data you have shown is taken in the Northern Hemisphere. In the Southern Hemisphere, the cycle is opposite. There is a time constant for the air of the Northern Hemisphere to mix with the air from the Southern Hemisphere. The time constant is on the order of about 2 years.

    I'm moving this thread to the Earth Science Forum.

  4. Jun 21, 2015 #3
  5. Jun 21, 2015 #4


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    More on measurements of atmospheric CO2 - https://scripps.ucsd.edu/programs/keelingcurve/

    In the southern hemisphere - http://www.csiro.au/greenhouse-gases/

  6. Jul 4, 2015 #5
  7. Jul 4, 2015 #6
    The Northern cycle should predominate, as there is greater landmass there. There is a lag-time in the data like the cosine and sine wave due to the time it takes to reach equilibrium.
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