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et al. 2003 ; Hoskins and James 2014 ; De Vries et al. 2010 ; Davies 2015 ). The present study is concerned with the inverse problem of using the balanced omega equation to estimate diabatic forcing for the processes involving inertia–gravity waves (IGWs) associated with unbalanced motion and their parameterization. As gravity waves modified by Earth’s rotation ( Holton and Hakim 2013 ), the IGWs play an important role in the atmosphere by transferring momentum and energy ( Fritts and
et al. 2003 ; Hoskins and James 2014 ; De Vries et al. 2010 ; Davies 2015 ). The present study is concerned with the inverse problem of using the balanced omega equation to estimate diabatic forcing for the processes involving inertia–gravity waves (IGWs) associated with unbalanced motion and their parameterization. As gravity waves modified by Earth’s rotation ( Holton and Hakim 2013 ), the IGWs play an important role in the atmosphere by transferring momentum and energy ( Fritts and
1. Introduction Orographic gravity waves (GWs), or mountain waves (MWs), are internal GWs within the atmosphere forced by stratified flow over topography. MW generation is one way the atmosphere exchanges momentum with Earth. Positive and negative pressure perturbations upstream and downstream of a mountain, respectively, exert a net force by the atmosphere on the mountain. An equal and opposite force is exerted by the mountain on the atmosphere. Often, an MW is generated, which
1. Introduction Orographic gravity waves (GWs), or mountain waves (MWs), are internal GWs within the atmosphere forced by stratified flow over topography. MW generation is one way the atmosphere exchanges momentum with Earth. Positive and negative pressure perturbations upstream and downstream of a mountain, respectively, exert a net force by the atmosphere on the mountain. An equal and opposite force is exerted by the mountain on the atmosphere. Often, an MW is generated, which
1. Introduction As one of the most fundamental physical modes in meteorology, gravity waves (GWs) are ubiquitous buoyancy oscillations in the atmosphere. The sources of excited gravity waves include, among others, topographic forcing ( Smith 1980 ; Menchaca and Durran 2017 ), convection ( Alexander et al. 1995 ; Lane et al. 2001 ), the jets ( Zhang 2004 ; Plougonven and Zhang 2014 ; Hien et al. 2018 ), frontal systems ( Snyder et al. 1993 ; Griffiths and Reeder 1996 ), and shear
1. Introduction As one of the most fundamental physical modes in meteorology, gravity waves (GWs) are ubiquitous buoyancy oscillations in the atmosphere. The sources of excited gravity waves include, among others, topographic forcing ( Smith 1980 ; Menchaca and Durran 2017 ), convection ( Alexander et al. 1995 ; Lane et al. 2001 ), the jets ( Zhang 2004 ; Plougonven and Zhang 2014 ; Hien et al. 2018 ), frontal systems ( Snyder et al. 1993 ; Griffiths and Reeder 1996 ), and shear
can reach the winter MLT ( Pautet et al. 2019 ), where high-frequency gravity wave responses transported the most momentum and eastward (upwind) gravity wave propagation correlated with elevated tropospheric forcing below. Given that small-scale gravity waves have been observed above the PNJ in the winter MLT, and given that several orographic and nonorographic sources have been shown to generate these scales of mesospheric gravity wave responses, it is essential to evaluate how tropospheric
can reach the winter MLT ( Pautet et al. 2019 ), where high-frequency gravity wave responses transported the most momentum and eastward (upwind) gravity wave propagation correlated with elevated tropospheric forcing below. Given that small-scale gravity waves have been observed above the PNJ in the winter MLT, and given that several orographic and nonorographic sources have been shown to generate these scales of mesospheric gravity wave responses, it is essential to evaluate how tropospheric
disturbance, on the assumption of steady state forcing by a propagating submesoscale GW packet. In section 4d , the simulation results of different test cases are presented and compared against the theoretical predictions. Finally, the article concludes with a summary and discussion of the main findings in section 5 . 2. Theory: Basics and formalism For simplicity the interaction between mesoscale and submesoscale GWs is studied in a rotating, incompressible, and inviscid Boussinesq atmosphere with
disturbance, on the assumption of steady state forcing by a propagating submesoscale GW packet. In section 4d , the simulation results of different test cases are presented and compared against the theoretical predictions. Finally, the article concludes with a summary and discussion of the main findings in section 5 . 2. Theory: Basics and formalism For simplicity the interaction between mesoscale and submesoscale GWs is studied in a rotating, incompressible, and inviscid Boussinesq atmosphere with
tilt of the PNJ generally found in climatological means (see Schoeberl and Newman 2015 ). Fig . 4. Horizontal wind V H (m s −1 , color shaded) and geopotential height (m, solid lines) at (a) 1, (b) 5, and (c) 10 hPa at 1200 UTC 12 Jan 2016. Fig . 5. Horizontal wind V H (m s −1 , color shaded) along the (a) 10° and (b) 50°E meridians at 1200 UTC 12 Jan 2016. The thin solid lines are isentropes in logarithmic scaling. 3. Conditions for gravity wave excitation a. Low-level forcing Low-level winds
tilt of the PNJ generally found in climatological means (see Schoeberl and Newman 2015 ). Fig . 4. Horizontal wind V H (m s −1 , color shaded) and geopotential height (m, solid lines) at (a) 1, (b) 5, and (c) 10 hPa at 1200 UTC 12 Jan 2016. Fig . 5. Horizontal wind V H (m s −1 , color shaded) along the (a) 10° and (b) 50°E meridians at 1200 UTC 12 Jan 2016. The thin solid lines are isentropes in logarithmic scaling. 3. Conditions for gravity wave excitation a. Low-level forcing Low-level winds
mean flow (blue), and their sum (red). (b) Hovmöller diagram of the wave energy (kg m −1 s −2 ). (c) Induced mean wind (m s −1 ). 5. Summary and conclusions The steady-state approximation to WKB theory used nowadays in GW-drag parameterizations implies that the only GW forcing on the mean flow is due to wave breaking. Transient GW–mean flow interactions can, however, act as another important coupling mechanism. This study provides an assessment of the comparative importance of these processes in
mean flow (blue), and their sum (red). (b) Hovmöller diagram of the wave energy (kg m −1 s −2 ). (c) Induced mean wind (m s −1 ). 5. Summary and conclusions The steady-state approximation to WKB theory used nowadays in GW-drag parameterizations implies that the only GW forcing on the mean flow is due to wave breaking. Transient GW–mean flow interactions can, however, act as another important coupling mechanism. This study provides an assessment of the comparative importance of these processes in
used winds, temperature, and specific humidity from radiosonde data at T3 (3.2°S, 60.6°W). Important supplementary products including apparent heating ( Q 1 ), apparent drying ( Q 2 ), and large-scale vertical motion ( ω ), were obtained from variational analysis ( Tang et al. 2016 ), which are available to the community at the Atmospheric Radiation Measurement (ARM) program archive ( https://iop.archive.arm.gov/arm-iop/0eval-data/xie/scm-forcing/iop_at_mao/GOAMAZON/2014-2015/ ). Twice
used winds, temperature, and specific humidity from radiosonde data at T3 (3.2°S, 60.6°W). Important supplementary products including apparent heating ( Q 1 ), apparent drying ( Q 2 ), and large-scale vertical motion ( ω ), were obtained from variational analysis ( Tang et al. 2016 ), which are available to the community at the Atmospheric Radiation Measurement (ARM) program archive ( https://iop.archive.arm.gov/arm-iop/0eval-data/xie/scm-forcing/iop_at_mao/GOAMAZON/2014-2015/ ). Twice
transition from westerly to easterly winds with important consequences for the propagation and drag of planetary and synoptic waves ( Scaife et al. 2002 ). They also contribute to the forcing of the Brewer–Dobson circulation and thus to the transport of trace gases like ozone and water vapor ( Alexander and Rosenlof 1996 ). Convectively generated GWs are important for generating the quasi-biennial oscillation (QBO) in the tropics ( Labitzke 2005 ; Marshall and Scaife 2009 ), which has a strong influence
transition from westerly to easterly winds with important consequences for the propagation and drag of planetary and synoptic waves ( Scaife et al. 2002 ). They also contribute to the forcing of the Brewer–Dobson circulation and thus to the transport of trace gases like ozone and water vapor ( Alexander and Rosenlof 1996 ). Convectively generated GWs are important for generating the quasi-biennial oscillation (QBO) in the tropics ( Labitzke 2005 ; Marshall and Scaife 2009 ), which has a strong influence
; Snyder et al. 2007 ). In the second stream, the focus has been on the main characteristics of the IGWs including the frequency and horizontal and vertical wavelengths ( Plougonven and Snyder 2005 , 2007 ; Zülicke and Peters 2006 ). However, no attempt has been made to connect the two streams by comparing their measures of IGW activity. The importance of the problem has been recognized by Plougonven and Zhang (2007) , who used scaling arguments to provide a wave equation describing the forcing of
; Snyder et al. 2007 ). In the second stream, the focus has been on the main characteristics of the IGWs including the frequency and horizontal and vertical wavelengths ( Plougonven and Snyder 2005 , 2007 ; Zülicke and Peters 2006 ). However, no attempt has been made to connect the two streams by comparing their measures of IGW activity. The importance of the problem has been recognized by Plougonven and Zhang (2007) , who used scaling arguments to provide a wave equation describing the forcing of
