Sensitivity of Mesoscale Gravity Waves to the Baroclinicity of Jet-Front Systems

Abstract

ABSTRACT

Characteristics of gravity waves generated in the jet-front system in a baroclinic instability simulation

“…He detected vertically propagating GWs with horizontal and vertical wavelengths of ∼ 100-200 km and ∼ 2.5 km, respectively, which originate from the upper-tropospheric jet exit region. Wang and Zhang (2007) extended the work of Zhang (2004) and showed that the characteristics of the GWs near the upper-tropospheric jet exit vary depending on the baroclinicity. They demonstrated that the growth rate of the flow imbalance is correlated with that of the baroclinic wave and the intrinsic frequency of the GWs at the same time.…”

“…Previous studies have reported on the dominant phase velocities of the GWs simulated in jet-front systems. For example, Wang and Zhang (2007) showed that the dominant phase speed of the GWs in their four simulations ranged from 0 to 11 m s −1 in directions perpendicular to the background flow. PS07 showed that the zonal phase speeds of the GWs in their simulations were about 13-15 m s −1 .…”

Aircraft measurements of gravity waves in the upper troposphere and lower stratosphere during the START08 field experiment

“…This phenomenon has been identified repeatedly in both observational studies (Uccellini and Koch, 1987;Schneider, 1990;Fritts and Nastrom, 1992;Ramamurthy et al, 1993;Bosart et al, 1998;Koppel et al, 2000;Rauber et al, 2001; and numerical investigations of the observed cases (Powers and Reed, 1993;Pokrandt et al, 1996;Kaplan et al, 1997;Zhang and Koch, 2000;Zhang et al, 2001Zhang et al, , 2003Koch et al, 2001Koch et al, , 2005Lane et al, 2004). In addition, idealized simulations of dry baroclinic jet-front systems in a high-resolution mesoscale model have been performed to investigate the generation of mesoscale gravity waves (Zhang, 2004), the sensitivity of mesoscale gravity waves to the baroclinicity of jet-front systems (Wang and Zhang, 2007), and the source of gravity waves with multiple horizontal scales (Lin and Zhang, 2008). Most recently, Zhang (2014, 2015) studied the characteristics and potential source mechanisms of mesoscale gravity waves in moist baroclinic jetfront systems with varying degree of convective instability.…”

“…This will help to distinguish whether the sampled mesoscale and small-scale variances are gravity waves or artifacts of the observing system. In addition, under the idealized controllable atmosphere with varying degrees of convective instability and baroclinic instability (e.g., Zhang, 2004;Wang and Zhang, 2007;Wei and Zhang, 2014;Sun and Zhang, 2015), high-resolution simulations of baroclinic jet-front systems will be employed to understand (1) how to constrain the parameterizations of jet-front gravity waves in general circulation models, (2) the role of gravity waves in mesoscale predictability, and (3) the contribution of gravity waves to mesoscale energy spectra in global wavenumber distribution or in multi-dimensional wavenumber distribution.…”

“…Gravity waves, in particular, are known to play a significant role in determining the structure and composition of the ExUTLS. Tropopause jets and fronts are significant sources of gravity waves (O'Sullivan and Dunkerton, 1995;Reeder and Griffiths, 1996;Zhang, 2004;Wang and Zhang, 2007;Mirzaei et al, 2014;Zhang, 2014, 2015), along with surface topography (Smith, 1980) and moist convection (Lane et al, 2001). Gravity waves above the jet may be responsible for double or multiple tropopauses (Yamanaka et al, 1996;Pavelin et al, 2001) and may contribute to layered ozone or potential vorticity structures (Bertin et al, 2001).…”