Award: OCE-2138890

Nitrous oxide is a potent greenhouse gas that also leads to reduced ozone concentrations in the stratosphere. It is produced by microorganisms, particularly in areas where dissolved oxygen concentrations are very low. While many estimates of global budgets for natural and anthropogenic emissions of this gas have been made, the contribution by the oceans remains uncertain due to sparse direct measurements in marine hotspots. Further, how emissions vary with time due to seasonal or El Nio cycles is not well-constrained. We established a new nitrous oxide monitoring station on the island San Cristbal in the Galapagos to continuously measure nitrous oxide concentrations in the air overlying this site. Coupling these measurements to observations of regional wind patterns, we have used modeling techniques to estimate the emission patterns across the region and how the emissions vary with time. The instrument and all necessary calibration air tanks and ancillary equipment were fully installed at the Galapagos Science Center (GSC) in May 2023 in coordination with scientists and staff from the GSC, University of North Carolina, and Universidad San Francisco de Quito. The instrument is calibrated against four air samples certified by the NOAA Global Monitoring Laboratory using an automated switching system. A sample intake line was installed on the roof, and plumbed with a vacuum pump, line dryer to remove water vapor, and custom-built heater to prevent condensation. The repeatability of the measurements for nitrous oxide is comparable to other high-quality global measurement sites, making this an important new measurement station for analyzing natural marine nitrous oxide emissions and variability. A methodology was developed to identify stagnant samples from simultaneous carbon monoxide measurements and local wind observations. These samples are filtered from further analyses as they are thought to more reflect local pollution on the islands than pristine marine air, but such events account for only about 5% of the data. In the first year of operation, we produced over 150,000 new daily nitrous oxide flux estimates across the eastern tropical South Pacific Ocean at a 1-degree spatial resolution. The primary measurements of nitrous oxide, carbon monoxide, and water vapor (after partial drying) content in air are available at the BCO-DMO data repository, Project #859617.The first year of data shows reliable results, with winds bringing air to the Galapagos from across the eastern tropical Pacific. Sometimes the air parcels come from hundreds of miles offshore and sometimes from along the continental boundary, and this difference allows us to distinguish between hotspots of emissions and regions of low atmospheric exchange.This project trained a graduate student at MIT, developed and maintained a bilingual (English and Spanish) website to report the data and the science to the public, and supported materials used in classes at MIT and in high school presentations. Last Modified: 01/30/2025 Submitted by: AndrewRBabbin