Climatology of Gravity Wave Activity From Two Martian Years of ACS/TGO
Observations
Abstract
We report the gravity wave (GW) statistics accumulated over two Martian
years from the second half of Martian Year 34 (MY34) to the middle of
MY36 (May 2018 - February 2022). The observations were performed by the
middle- and near-infrared (MIR and NIR, respectively) spectrometers of
Atmospheric Chemistry Suite (ACS) on board ExoMars Trace Gas Orbiter
(TGO). Temperature profiles obtained independently of both channels
during simultaneous measurements show a good agreement, thus providing
verification and additional confidence in the data. GW parameters such
as temperature fluctuations, potential energy per unit mass, and wave
drag are retrieved at altitudes up to 160 km from the MIR channel and up
to 100 km from the NIR channel. We present seasonal, intraday and
latitude distributions of the wave potential energy and drag, serving to
represent the wave activity and impact on the dynamics. A comparison of
data obtained during the global dust storm (GDS) of MY34 with the
corresponding period of MY35 without a storm reveals a reduction of GW
activity in mid-latitudes in agreement with previous observations, and
enhancement in the polar regions of both hemispheres, which was
predicted by theoretical studies using simulations with a
high-resolution circulation model. Seasonal variations of the derived GW
activity can be linked to changes in the solar tide.