Why is there a seasonal cycle of CO2？

[Kior]

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?

 

[Chestermiller]

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.

Chet

 

[Kior]

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.

Chet

Thanks!

 

[Astronuc]

More on measurements of atmospheric CO2 - https://scripps.ucsd.edu/programs/keelingcurve/
https://scripps.ucsd.edu/programs/k...society-to-recognize-keeling-curve/#more-1297

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

Seasonal variation
Carbon dioxide concentrations show seasonal variations (annual cycles) that vary according to global location and altitude. Several processes contribute to carbon dioxide annual cycles: for example, uptake and release of carbon dioxide by terrestrial plants and the oceans, and the transport of carbon dioxide around the globe from source regions (the Northern Hemisphere is a net source of carbon dioxide, the Southern Hemisphere a net sink).

The Cape Grim baseline carbon dioxide data displayed show both the annual cycle and the long-term trend.

 

[insightful]

The data you have shown is taken in the Northern Hemisphere. In the Southern Hemisphere, the cycle is opposite.

It's a bit more complicated than that. You have to get down to New Zealand to see this effect and it's quite weak:

http://dougrobbins.blogspot.com/2012/03/keeling-curve-and-seasonal-carbon.html

 

[gt 5]

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.