Atmospheric wind and temperature profiles inversion using infrasound: an
ensemble model context
We present an inversion methodology aimed at updating an atmospheric
model to be consistent with a set of infrasound-derived observations.
Compared to previous approaches, we apply a more flexible
parameterization. This permits to incorporate physical and numerical
constraints without the need to reformulate the inversion. On the other
hand, the optimization conveys an explicit search over the solution
space, making the solver computationally expensive. Nevertheless,
through a parallel implementation and the use of tight constraints we
demonstrate that the methodology is computationally tractable.
Constraints to the solution space are derived from the spread (variance)
of ERA5 ensemble reanalysis members, which summarize the best current
knowledge of the atmosphere from assimilated measurements and physical
models. Similarly, the initial model temperature and winds for the
inversion are chosen to be the average of these parameters in the
ensemble members. The performance of the inversion is demonstrated with
the application to infrasound observations from an explosion generated
by the destruction of ammunition at Hukkakero, Finland. The acoustic
signals are recorded at an array station located at 178 km range, which
is within the classical shadow zone distance. The observed returns are
assumed to come from stratospheric reflections. Therefore, in this
example, the altitude of reflection is also an unknown that is inverted
for, together with the updated atmospheric model.