Abstract
The travel time of infrasound through the stratosphere depends on the
temperature profile and the wind speed. These atmospheric conditions can
be estimated by determining the travel times between different receivers
(microbarometers). Therefore the determination of the travel time of
infrasound between different receivers becomes more and more important.
An approach to determine the travel time is infrasound interferometry.
In this work, the infrasound interferometry is applied to synthetic data
of active and passive sources refracted by the stratosphere is tested.
The synthetic data were generated with a raytracing model. The inputs of
the raytracing model are the atmospheric conditions and a source
wavelet. As source wavelet we used blast waves and microbaroms. With the
atmospheric conditions and the source wavelet the raytracing model
calculates the raypath and the travel time of the infrasound. In order
to simulate the measurement of a receiver the rays which reach the
receiver need to be found. The rays which propagate from a source to the
receiver are called eigen rays. The simulation of the receiver
measurements takes into account the travel time along the eigen rays,
the attenuation of the different atmospheric layers, the spreading of
the rays and the influence of caustics. The simulated measurements of
the different receivers are combined to synthetic barograms. Two
synthetic experiments were performed with the described model. In the
first experiment the interferometry was applied to barograms of active
sources like blast waves. The second experiment with microbaroms tests
the applicability of interferometry to barograms of passive sources. In
the next step infrasound interferometry will be applied to measured
barograms. These barograms are measured with the 'Large Aperture
Infrasound Array' (LAIA). LAIA is being installed by the Royal
Netherlands Meteorological Institute (KNMI) in the framework of the
radio-astronomical 'Low Frequency Array' (LOFAR) initiative. LAIA will
consist of thirty microbarometers with an aperture of around 100 km. The
in-house developed microbarometers are able to measure infrasound up to
a period of 1000 seconds, which is in the acoustic-gravity wave regime.
The results will also be directly applicable to the verification of the
'Comprehensive Nuclear-Test-Ban Treaty' (CTBT), where uncertainties in
the atmospheric propagation of infrasound play a dominant role. This
research is made possible by the support of the 'Netherlands
Organisation for Scientific Research' (NWO).
| Original language | English |
|---|---|
| Pages | A53B-0146 |
| Publication status | Published - 1 Dec 2012 |
| Event | American Geophysical Union Fall Meeting 2012 - San Francisco, USA Duration: 3 Dec 2012 → 7 Dec 2012 |
Conference
| Conference | American Geophysical Union Fall Meeting 2012 |
|---|---|
| City | San Francisco, USA |
| Period | 3/12/12 → 7/12/12 |
Keywords
- [0300] ATMOSPHERIC COMPOSITION AND STRUCTURE