Using Microwave Limb Sounder Observations and the Match Technique to Assess the Validity of Analysis Winds and Heating Rates

The long-standing "Match" technique uses Lagrangian trajectories to
identify cases where the composition of an airmass is observed on two or
more occasions. This approach accounts for the impact of advection on
the airmass, enabling observed changes in airmass composition to be
ascribed to chemical or microphysical processes, or to irreversible
mixing. The Match technique was pioneered with ozonesonde observations,
and used to quantify chemical destruction of Arctic stratospheric
ozone. The technique has previously been applied to the far denser ozone
observations from the Microwave Limb Sounder (MLS) instrument on NASA's
Aura satellite, launched in 2004, and used to quantify both Arctic and
Antarctic ozone loss for multiple years. We extend that prior work to
MLS observations of other trace gases, including nitrous oxide and
methyl chloride, both long-lived trace gases, and water vapor, which
behaves as a long-lived trace gas in most circumstances. In the absence
of chemical or microphysical processes, observed changes in the
abundance of these species in matched airmasses can be indicative of
irreversible mixing and/or of errors in the trajectory calculations used
to identify matched observations. Accordingly, this technique can
provide insights into the accuracy of analysis fields used to drive the
trajectories. We present preliminary results from such an analysis,
focused on the winds and heating rates in the MERRA-2 reanalysis
dataset.