Infrasound as a remote sensing technique for the upper atmosphere

Abstract

Understanding and specification of the higher altitudes of the atmosphere with global overage over all local times is hampered by the challenges of obtaining direct measurements in the upper atmosphere. Methods to measure the properties of the atmosphere above the stratopause is an active area of scientific research. In this presentation, we revisit the use of infrasound as a passive remote sensing technique for the upper atmosphere. In the past, various studies focused on the sensitivity of infrasound to various upper atmospheric processes. It has been shown that the current state-of-the-art climatologies for the middle and upper atmosphere are not always in agreement with the acoustic data, suggesting a use of infrasound as a complementary remote sensing technique. Previously, we reported on the error in thermospheric celerities which was found to be in accord with the typical uncertainty in upper atmospheric winds and temperature. In this presentation, we report on the expected variation of the various infrasound observables from a forward modeling perspective. This information, in combination with the experimental measurement error provides constraints on the expected resolution from the inverse problem. With this information, we minimize misfits in travel time and source location using a Levenberg-Marquardt search algorithm in combination with ray theory.