Atmospheric wind and temperature profiles inversion using infrasound: an
ensemble model context
Abstract
We present an inversion methodology where acoustic observations of
infrasound waves are used to update an atmospheric model. We sought a
flexible parameterization that 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. Thus, the reflection
altitude is also an inverted parameter.