Hi Jose,

I don't think satellite Images can provide directly and quantitatively the concentration of dissolved carbon dioxide in water or land surface because they generally give information about radiant energy reflected and emitted from the Earth's surface in the visible and infrared wavelength region up to only a few micrometers of the top surface or to some decimeters of the surface when considering the microwave wavelength region. Even with in situ measurements the estimates of CO2 are not accurate. Let alone with satellite data. But it is possible to get an approximate estimate using models, provided there are CO2 observational networks on the ground coupled with data from Visible, Infrared Spectroradiometers  and Microwave sounders mounted on Satellite sensors. On the other hand satellite sensors measuring carbon dioxide concentrations and distribution in the atmosphere do exist. The latest one as you may know is the much talked about Orbiting Carbon Observatory-2 satellite launched last year by NASA. It has already started providing global CO2 Maps and the results are quite compelling, providing clues to the great debate on climate change. Calibration results are also quite good. There are others like the Atmospheric Infrared Sounder (AIRS) instrument on NASA's EOS Aqua Satellite which provide atmospheric distribution of trace gas like CO2, CO and O3. Another one is the Japanese GOSAT managed by JAXA.

Nevertheless, you can search with the keyword 'Carbon Dioxide' in NASA's https://search.earthdata.nasa.gov/ for your study area in Caxiuanã bay and may be you will find some useful data.

http://www.nasa.gov/mission_pages/oco2/index.html

http://airs.jpl.nasa.gov/data/overview

http://www.gosat.nies.go.jp/en/about_1_goal.html

https://search.earthdata.nasa.gov/

https://www.youtube.com/watch?v=9ZoqZTmTjmE

Your study site has a complex system so your flux data may not be in  line with the calculation based on the difference in pCO2 between the atmosphere and water, which is often used for oceanic studies. Terrestrial processes can have large impacts on the CO2 flux at the bay.

Dear Jose, I agree with James that satellite data are not up to the task (at least not yet). Instead I would go to the so far largest collection of direct measurements (SOCAT V2), described in

Bakker, D. C. E., Pfeil, B., Smith, K., Hankin, S., Olsen, A., Alin, S. R., Cosca, C., Harasawa, S., Kozyr, A., Nojiri, Y., O’Brien, K. M., Schuster, U., Telszewski, M., Tilbrook, B., Wada, C., Akl, J., Barbero, L., Bates, N. R., Boutin, J., Bozec, Y., Cai, W.-J., Castle, R. D., Chavez, F. P., Chen, L., Chierici, M., Currie, K., De Baar, H. J. W., Evans, W., Feely, R. A., Fransson, A., Gao, Z., Hales, B., Hardman-Mountford, N. J., Hoppema, M., Huang, W.-J., Hunt, C. W., Huss, B., Ichikawa, T., Johannessen, T., Jones, E. M., Jones,  S., Jutterstrom, S., Kitidis, V., Körtzinger, A., Landschützer, P., Lauvset, S. K., Lefèvre, N., Manke, A. B.,  Mathis, J. T., Merlivat, L., Metzl, N., Murata, A., Newberger, T., Omar, A. M., Ono, T., Park, G.-H., Paterson, K., Pierrot, D., Ríos, A. F., Sabine, C. L., Saito, S., Salisbury, J., Sarma, V. V. S. S., Schlitzer, R., Sieger, R., Skjelvan, I., Steinhoff, T., Sullivan, K. F., Sun, H., Sutton, A. J., Suzuki, T., Sweeney, C., Takahashi, T., Tjiputra, J., Tsurushima, N., Van Heuven, S. M. A. C., Vandemark, D., Vlahos, P., Wallace, D. W. R., Wanninkhof, R., Watson, A. J. (2014) An update to the Surface Ocean CO2 Atlas (SOCAT version 2). Earth System Science Data 6: 69-90. doi:10.5194/essd-6-69-2014.

If you need an interpolated version, i.e. one where you have data everywhere, you should check

Landschützer, P., Gruber, N., Bakker,, D. C. E. (2015) A 30 years observation-based global monthly gridded sea surface pCO2 product from 1982 through 2011. http://cdiac.ornl.gov/oceans/SPCO2_1982_2011_ETH_SOM_FFN.html.

Best regards,

Christoph

Remote sensing is a tool for acquiring data regarding physical properties only. We can not exactingly calculate concentration of carbon di oxide in water by using satellite. 

You should have been measuring the alkalinity and the pH of the sea water concurrently with your other measurements, which would have been easy to do. Other agencies may have been doing that but if not, then I suggest that you perform some measurements yourself in order to get a feel for the diurnal variation which may be significant.

You may find this paper relevant:

http://rsta.royalsocietypublishing.org/content/361/1810/1977

I am very grateful for the answer that is helping me a lot, and I would like to inform you that we are not working in the ocean but in an area of the Amazon River, which has appearance of a bay (-1°46.785; -51°25.385).

Glad to hear I have helped.  If I had know that you were talking about fresh water rather than sea water  I might not have responded.

A maritime diurnal cycle of CO2 is produced by coral reefs, but I do not know whether freshwater vegetation has the same effect.

By the way, would you be willing to upvote my answer? I am trying to get my RG Score into double figures :-)