The Influence of Large-Scale Circulation on Carbon Dioxide

Carbon dioxide (CO2) has been shown to have adverse effects on a global scale as a major contributor to climate change, yielding changes to temperature, environments and habitats of all life on Earth. With improvements in satellite technology, newer and more precise measurements of CO2 concentrations have been collected. The Orbiting Carbon Observatory 2 (OCO-2), the first dedicated CO2 satellite launched by NASA, and the Greenhouse Gas Observing Satellite (GOSAT),first CO2 satellite developed by Japan, offer new insight to CO2 column measurements within the lower troposphere. First, the validity of the new OCO-2 and GOSAT CO2 data in comparison to in situ CO2 measurements from known TCCON sites was examined. Both OCO-2and GOSAT CO2 data agreed reasonably well with TCCON in situ measurements. Afterwards, the effects of the South Atlantic Walker Circulation on the distribution of OCO-2 and GOSAT CO2 in the lower troposphere in these regions was investigated. The research showed OCO-2 and GOSAT CO2 concentrations are lower over the South Atlantic Ocean than the South America by 1 parts per million (ppm) during December to March, which is consistent with the large-scale South Atlantic Walker Circulation. During December to March, surface temperatures are high over the South America, which causes air to rise. The rising air can bring high surface CO2 concentrations to the lower troposphere, which leads to a positive CO2 anomaly over the South America. Sinking air over South Atlantic Ocean can bring low upper-level CO2concentrations to the lower troposphere, causing a negative CO2 anomaly over the South Atlantic Ocean. Results in this study will lead to a better understanding of how large-scale atmospheric processes affect lower troposphere CO2 measurements regionally, therefore, lead to a better understanding of the CO2 global cycle.