Observation of Trace Gases Seasonal Variability in the Marine Boundary
Layer over the Atlantic Ocean during the ACTIVATE Field Campaign
Abstract
High resolution in-situ measurements of carbon monoxide (CO), carbon
dioxide (CO2), methane (CH4), and water vapor (H2O) were made onboard
the NASA HU-25 aircraft during the ACTIVATE (Aerosol Cloud meteorology
Interactions oVer the western Atlantic Experiment) campaign during 2020
and 2021 in different seasons (winter through summer) over the
mid-latitude western Atlantic Ocean. As most of the flights focused on
the marine boundary layer (MBL) during the campaign, these trace gas
observations are an excellent data set to examine seasonal variability
of trace gas background values in the MBL without the influence of
localized point sources. We will describe the variability of these trace
gases in the MBL background by filtering out concentrated point sources
using back trajectory analysis along with trace gas ratios.
Additionally, the ocean is a significant sink of anthropogenic CO2
capturing about one quarter of total anthropogenic carbon. By looking at
the MBL CO2 variation as a function of season, we discuss observed
changes in CO2 uptake over the ocean. These high accuracy observations
of trace gas backgrounds in the MBL along with characterizing seasonal
effects on oceanic sequestering of anthropogenic CO2 will improve the
understanding of seasonal variations and change in climate and inverse
modelling over the ocean.