Deconstruction of tropospheric chemical reactivity using aircraft
measurements: the ATom data
Abstract
From NASA’s Atmospheric Tomography (ATom) mission, we calculate the
average production/loss of O3 and CH4
for 10s air parcels along profiling transects through the
Pacific/Atlantic Oceans for four seasons. We find photochemically hot
air masses on all scales from 2 to 2000 km. Tropical production of
O3 is high (~2 ppb/day) throughout the
ATom profiles (0–12 km). In the Eastern Pacific we find large coherent
air masses of extremely high reactivities in August (monsoonal) and May
(biomass burning). The tropics dominate the O3 and
CH4 budgets. Sensitivity analysis identifies only five
critical species (NOx, O3, CH4, CO, and
H2O) responsible for driving the budgets. Sensitivity
analysis shows large 2nd-order effects for coupled
perturbations, indicating that 1st-order sensitivities
cannot simply be added. Feedback analysis indicates a
slower-than-expected timescale for decay of O3
perturbations. ATom data shows how global tropospheric chemistry is
constructed from a myriad of fine and large scales.