A new method for detecting solar atmospheric gravity waves

Abstract

Internal gravity waves have been observed in the Earth’s atmosphere and oceans, on Mars and Jupiter, and in the Sun’s atmosphere. Despite ample evidence for the existence of propagating gravity waves in the Sun’s atmosphere, we still do not have a full understanding of their characteristics and overall role for the dynamics and energetics of the solar atmosphere. Here, we present a new approach to study the propagation of gravity waves in the solar atmosphere. It is based on calculating the three-dimensional cross-correlation function between the vertical velocities measured at different heights. We apply this new method to a time series of co-spatial and co-temporal Doppler images obtained by SOHO/MDI and Hinode/SOT as well as to simulations of upward propagating gravity wave-packets. We show some preliminary results and outline future developments. This article is part of the Theo Murphy meeting issue ‘High-resolution wave dynamics in the lower solar atmosphere’.

Multiheight Observations of Atmospheric Gravity Waves at Solar Disk Center

“…In local helioseismology, this quantity is normally computed from the inverse Fourier transform of the velocity power spectrum. For multiheight Doppler observations, one could obtain this quantity by computing the inverse transform of the cross-spectrum, which Calchetti et al (2021) demonstrated. A 2D slice through this quantity at a constant time produces a ring shape in the x-and ydirections.…”

“…To explore these features, we consider a very simple simulation of propagating AGWs comparable to that of Calchetti et al (2021). We use a numerical 2D box set in the x-z plane extending about 25 Mm wide and a few Mm in height to propagate perturbations due to AGW packets.…”

“…Studies of AGWs in the field of solar physics began with Whitaker (1963) and their proposed contribution to the coronal heating problem. Since then, phase difference analysis and other diagnostics using intensity and velocity fluctuations sampled simultaneously at different atmospheric heights near disk center on the quiet Sun (for instance, Staiger et al 1984;Deubner & Fleck 1989;Bonet et al 1991;Komm et al 1991;Deubner et al 1992;Kneer & von Uexkuell 1993;Straus & Bonaccini 1997;Krijger et al 2001;Rutten & Krijger 2003;Stodilka 2008;Straus et al 2008;Kneer & Bello González 2011;Nagashima et al 2014;Calchetti et al 2021) have provided observational evidence for the existence of AGWs from the low photosphere to the low chromosphere.…”

High-resolution wave dynamics in the lower solar atmosphere

“…Detection of the gravity waves in the solar atmosphere has, however, been a challenging task. Using a three-dimensional cross-correlation technique involving time series of vertical velocities measured at different atmospheric heights, Calchetti et al [35] propose a new approach to directly identify and characterize gravity waves in the lower solar atmosphere. The authors further validate their method using an observational dataset as well as a simple numerical model.…”

High-resolution wave dynamics in the lower solar atmosphere

“…Detection of the gravity waves in the solar atmosphere has, however, been a challenging task. Using a three dimensional cross-correlation technique involving time series of vertical velocities measured at different atmospheric heights, Calchetti et al [35] propose a new approach to directly identify and characterise gravity waves in the lower solar atmosphere. The authors further validate their method using an observational dataset as well as a simple numerical model.…”