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1. Introduction The overarching objectives of the Deep Propagating Gravity Wave Experiment (DEEPWAVE; see appendix A for a list of key acronyms used in this paper) were to observe, model, understand, and predict the deep vertical propagation of internal gravity waves from the troposphere to the lower thermosphere and to study their impacts on the atmospheric momentum and energy budget ( Fritts et al. 2016 ). Convection, fronts, flow over mountains, and spontaneous adjustments occurring at the
1. Introduction The overarching objectives of the Deep Propagating Gravity Wave Experiment (DEEPWAVE; see appendix A for a list of key acronyms used in this paper) were to observe, model, understand, and predict the deep vertical propagation of internal gravity waves from the troposphere to the lower thermosphere and to study their impacts on the atmospheric momentum and energy budget ( Fritts et al. 2016 ). Convection, fronts, flow over mountains, and spontaneous adjustments occurring at the
1. Introduction Inertia–gravity waves (IGWs) become dominant modes of motion at mesoscales of the atmosphere, i.e., at horizontal scales smaller than about 500 km ( Callies et al. 2014 ; Žagar et al. 2017 ), thereby contributing to the loss of predictability in weather prediction ( Judt 2018 ) and model uncertainty in climate prediction ( Liu 2019 ). For current general circulation models (GCMs), the resolvable scales of atmospheric phenomena are on the order of 100 km. Resolving smaller
1. Introduction Inertia–gravity waves (IGWs) become dominant modes of motion at mesoscales of the atmosphere, i.e., at horizontal scales smaller than about 500 km ( Callies et al. 2014 ; Žagar et al. 2017 ), thereby contributing to the loss of predictability in weather prediction ( Judt 2018 ) and model uncertainty in climate prediction ( Liu 2019 ). For current general circulation models (GCMs), the resolvable scales of atmospheric phenomena are on the order of 100 km. Resolving smaller
1. Introduction The parameterization of gravity waves (GWs) is of significant importance in atmospheric global circulation models (GCM), in global numerical weather prediction (NWP) models, and in ocean models. In spite of the increasing available computational power and the corresponding increase of spatial resolution of GCMs and NWP models, for the time being, an important range of GW spatial scales remains unresolved both in climate simulations and in global NWP ( Alexander et al. 2010
1. Introduction The parameterization of gravity waves (GWs) is of significant importance in atmospheric global circulation models (GCM), in global numerical weather prediction (NWP) models, and in ocean models. In spite of the increasing available computational power and the corresponding increase of spatial resolution of GCMs and NWP models, for the time being, an important range of GW spatial scales remains unresolved both in climate simulations and in global NWP ( Alexander et al. 2010
wave excitation and propagation. Our results should encourage other scientists to apply this kind of an approach to past and future datasets of middle atmospheric lidar measurements. Section 2 provides an overview of the methodological approach of this study, starting with a description of the instruments and tools used. The results are presented in section 3 and discussed in detail in section 4 . Finally, the conclusions are given in section 5 . 2. Methodology a. Ground-based lidar
wave excitation and propagation. Our results should encourage other scientists to apply this kind of an approach to past and future datasets of middle atmospheric lidar measurements. Section 2 provides an overview of the methodological approach of this study, starting with a description of the instruments and tools used. The results are presented in section 3 and discussed in detail in section 4 . Finally, the conclusions are given in section 5 . 2. Methodology a. Ground-based lidar
1. Introduction Internal gravity waves (GWs) play a significant role in atmospheric dynamics on various spatial scales ( Fritts and Alexander 2003 ; Kim et al. 2003 ; Alexander et al. 2010 ; Plougonven and Zhang 2014 ). Already in the lower atmosphere GW effects are manifold. Examples include the triggering of high-impact weather (e.g., Zhang et al. 2001 , 2003 ) and clear-air turbulence ( Koch et al. 2005 ), as well as the effect of small-scale GWs of orographic origin on the predicted
1. Introduction Internal gravity waves (GWs) play a significant role in atmospheric dynamics on various spatial scales ( Fritts and Alexander 2003 ; Kim et al. 2003 ; Alexander et al. 2010 ; Plougonven and Zhang 2014 ). Already in the lower atmosphere GW effects are manifold. Examples include the triggering of high-impact weather (e.g., Zhang et al. 2001 , 2003 ) and clear-air turbulence ( Koch et al. 2005 ), as well as the effect of small-scale GWs of orographic origin on the predicted
numerical simulation and NCEP GFS = National Centers for Environmental Prediction Global Forecast System. MOTIVATIONS. GWs, or buoyancy waves, for which the restoring force is due to negatively (positively) buoyant air for upward (downward) displacements, play major roles in atmospheric dynamics, spanning a wide range of spatial and temporal scales. Vertical and horizontal wavelengths, λ z and λ h , respectively, for vertically propagating GWs are dictated by their sources and propagation conditions
numerical simulation and NCEP GFS = National Centers for Environmental Prediction Global Forecast System. MOTIVATIONS. GWs, or buoyancy waves, for which the restoring force is due to negatively (positively) buoyant air for upward (downward) displacements, play major roles in atmospheric dynamics, spanning a wide range of spatial and temporal scales. Vertical and horizontal wavelengths, λ z and λ h , respectively, for vertically propagating GWs are dictated by their sources and propagation conditions
1. Introduction Atmospheric gravity waves (GWs) play a key role in defining the large-scale global circulation and thermal structure of the middle and upper atmosphere, and they are important drivers of global atmospheric variability on various time scales. They are the main driver of the mesospheric summer to winter pole-to-pole circulation ( Holton 1982 , 1983 ) and the reason for the cold summer mesopause ( Björn 1984 ). In the stratosphere, GWs affect the timing of the springtime
1. Introduction Atmospheric gravity waves (GWs) play a key role in defining the large-scale global circulation and thermal structure of the middle and upper atmosphere, and they are important drivers of global atmospheric variability on various time scales. They are the main driver of the mesospheric summer to winter pole-to-pole circulation ( Holton 1982 , 1983 ) and the reason for the cold summer mesopause ( Björn 1984 ). In the stratosphere, GWs affect the timing of the springtime
1. Introduction Atmospheric gravity waves generated in the lee of mountains extend over scales across which the background may change significantly. The wave field can persist throughout the layers from the troposphere to the deep atmosphere, the mesosphere and beyond ( Fritts et al. 2016 , 2018 ). On this range background temperature and therefore stratification and background density may undergo several orders of magnitude in variation. Also, dynamic viscosity and thermal conductivity cannot
1. Introduction Atmospheric gravity waves generated in the lee of mountains extend over scales across which the background may change significantly. The wave field can persist throughout the layers from the troposphere to the deep atmosphere, the mesosphere and beyond ( Fritts et al. 2016 , 2018 ). On this range background temperature and therefore stratification and background density may undergo several orders of magnitude in variation. Also, dynamic viscosity and thermal conductivity cannot
modeling of subgrid-scale inertia–gravity waves (IGWs) in a rotating compressible atmosphere. The first approach, denoted as a pseudomomentum scheme, is closely related to the fundamental result of Andrews and McIntyre (1978) that in a Lagrangian-mean reference frame GW effects on the large-scale flow only occur in the momentum equation. It can be shown that this holds also in the Eulerian-mean reference frame used by atmospheric models, at least if the large-scale flow is in hydrostatic and
modeling of subgrid-scale inertia–gravity waves (IGWs) in a rotating compressible atmosphere. The first approach, denoted as a pseudomomentum scheme, is closely related to the fundamental result of Andrews and McIntyre (1978) that in a Lagrangian-mean reference frame GW effects on the large-scale flow only occur in the momentum equation. It can be shown that this holds also in the Eulerian-mean reference frame used by atmospheric models, at least if the large-scale flow is in hydrostatic and
( Kim et al. 2003 ; Fritts et al. 2016 ). For an inviscid, adiabatic, nonrotating, steady, Boussinesq flow across mountains, linear theory gives total critical levels whenever the scalar product of horizontal wind and horizontal wave vector is zero for all wavenumbers ( Teixeira 2014 ). Thus, the DEEPWAVE campaign offered the opportunity to study transient tropospheric forcing and the corresponding deep atmospheric wave response for the first time. The steady-state assumption is the basis of
( Kim et al. 2003 ; Fritts et al. 2016 ). For an inviscid, adiabatic, nonrotating, steady, Boussinesq flow across mountains, linear theory gives total critical levels whenever the scalar product of horizontal wind and horizontal wave vector is zero for all wavenumbers ( Teixeira 2014 ). Thus, the DEEPWAVE campaign offered the opportunity to study transient tropospheric forcing and the corresponding deep atmospheric wave response for the first time. The steady-state assumption is the basis of
