When: 1 June – 31 July 2021
To meet the overall AEROMMA science objectives the NOAA WP-3D aircraft will deploy to Ontario, CA and Portsmouth, NH.
Ontario, CA will provide the NOAA WP-3D access to the urban areas of Los Angeles together with regions where dimethyl sulfide (DMS) chemistry is known to be active of the coast of Los Angeles and the Salton Sea, where high DMS and halogen emissions have previously been observed. From Ontario, CA flight plans will be developed to sample the Los Angeles urban center and conduct sampling throughout the gradient between urban and marine atmosphere in a single flight. The close proximity of Ontario, CA to marine environments with limited anthropogenic influence limits the loss of flight hours due to transit times. Elevated marine sulfur chemistry in coastal areas is a common feature globally and was validated during an AEROMMA concept flight performed during FIREX-AQ project in September 2019, where hydroperoxymethyl thioformate (HPMTF) mixing ratios ranged 100 - 300 ppt immediately off the coast of the LA basin. Flights in these regions additionally provide the opportunity to identify the impacts from neighboring agricultural influences in the California Central Valley. On the transit from Florida to California, Houston could be investigated.
From Portsmouth, NH the NOAA WP-3D can survey all the major urban areas on the east coast such as New York, Chicago, and Toronto, together with the agriculture in Wisconsin, Iowa and Illinois. Deployment in the Northeastern US provides the ability to access regions in the Northern Atlantic which are highly impacted by DMS oxidation chemistry. Anthropogenic outflow on the Eastern coast of the US provides ideal conditions to study the composition and aging of urban emission at the interface of marine environments. A TROPOMI monthly average NO2 map clearly shows the large urban areas, but also regions with low NOx and strong NOx gradients of the east and west coast within the study region overlapping with high seawater DMS concentrations making for ideal conditions to study the transition from isomerization chemistry forming HPMTF to bimolecular NO chemistry forming SO2.