Nitrous oxide mapping

One of our most recent projects, executed entirely by an undergraduate student, Elisabeth Boles ’18, for her Senior Thesis, investigated how air masses measured in American Samoa (western/central South Pacific) can be traced backward in time to the eastern Pacific off of central and South America. In so doing, she was able to not only observe that the air overlying the low-oxygen zones of the eastern tropical Pacific exhibit high nitrous oxide compared to a global average, this high feature gets even higher during La NiƱa climate states.

Nitrous oxide is an important molecule for climate. It is both a greenhouse gas 300 times more potent than carbon dioxide and its breakdown products in the stratosphere can catalyze ozone loss. However, its natural sources and variability are poorly constrained, largely due to the characteristic nature of the molecule’s emissions in localized hotspots. Because of the high degree of spatial heterogeneity and temporal variability associated with nitrous oxide’s production, we sought a different strategy than one we normally execute… we opted to analyze large atmospheric datasets to achieve spatial and temporal resolution far beyond what is normally possible for ship-based measurements.

Map of nitrous oxide anomalies mapped across the Pacific after 15 days of transit to Samoa (orange circle). Reds are higher than Samoan mean whereas blues are lower than average. The contour lines in the eastern Pacific actually show the 10% (more eastern contour) and 20% (more western) dissolved oxygen saturation horizons at ~200 m ocean depth. Figure from Babbin et al. (2020) Nature Communications in press