A case study of the solar and lunar semidiurnal tide response to the
2013 sudden stratospheric warming
Abstract
This study investigates the response of the semidiurnal tide (SDT) to
the 2013 major sudden stratospheric warming (SSW) event using meteor
radar wind observations and mechanistic tidal model simulations. In the
model, the background atmosphere is constrained to meteorological fields
from the Navy Global Environmental Model - High Altitude analysis
system. The solar (thermal) and lunar (gravitational) SDT components are
forced by incorporating hourly global temperature tendency fields from
the ERA5 forecast model, and by specifying the M2 and N2 lunar
gravitational potentials, respectively. The simulated SDT response is
compared against meteor wind observations from the CMOR (43.3◦N,
80.8◦W), Collm (51.3◦N, 13.0◦E), and Kiruna (67.5◦N, 20.1◦E) radars,
showing close agreement with the observed amplitude and phase
variability. Numerical experiments investigate the individual roles of
the solar and lunar SDT components in shaping the net SDT response.
Further experiments isolate the impact of changing propagation
conditions through the zonal mean background atmosphere, non-linear
wave-wave interactions, and the SSW-induced stratospheric ozone
redistribution. Results indicate that between 80-97 km altitude in the
northern hemisphere mid-to-high latitudes the net SDT response is driven
by the solar SDT component, which itself is shaped by changing
propagation conditions through the zonal mean background atmosphere and
by non-linear wave-wave interactions. In addition, it is demonstrated
that as a result of the rapidly varying solar SDT during the SSW the
contribution of the lunar SDT to the total measured tidal field can be
significantly overestimated.