Southern Ocean Zonal Scale Summertime Oxygen Outgassing and Carbon Dioxide Ingassing
Abstract
We made intensive and extensive observations of atmospheric O2 and CO2 distributions over the Southern Ocean adjacent to Drake Passage and the Antarctic Peninsula during January and February of 2016 as part of the O2/N2 Ratio and Carbon Dioxide Airborne Southern Ocean (ORCAS) Study. These measurements revealed consistent large scale patterns indicating strong O2 outgassing and CO2 ingassing over the previous several months. The magnitudes and O2:CO2 ratios of these signals, and their broad spatial representativeness, provide valuable tests for Earth system models in this climatically important region, and in particular invalidate those predicting Southern Ocean CO2 outgassing at this time of year. We use O2 and CO2 mass balance estimates based on measured curtain averages, in comparison to station observations and model predictions, to quantify the seasonal net outgassing (SNO) of O2 and seasonal net ingassing (SNI) of CO2 for the Southern Ocean south of 40 S. In this analysis, we use atmospheric transport models to adjust for synoptic conditions and spatial undersampling on individual flights in order to obtain zonal mean seasonal estimates. We also calculate O2:CO2 ratios for vertical gradients in the mid-troposphere that are representative of large spatial and temporal scales, after correcting for remote continental and Northern Hemisphere influences on these gradients, and compare these ratios to that obtained for SNO:SNI. Finally, we compare our results to predictions from a tailored version of the Community Earth System Model, as well as other available flux estimates, and discuss potential reasons for discrepancies with the observations.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMOS43B2052S
- Keywords:
-
- 4805 Biogeochemical cycles;
- processes;
- and modeling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICALDE: 4806 Carbon cycling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICALDE: 4815 Ecosystems;
- structure;
- dynamics;
- and modeling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICALDE: 4845 Nutrients and nutrient cycling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL