scholarly journals Enhanced internal gravity wave activity and breaking over the Northeastern Pacific/Eastern Asian region

2015 ◽  
Vol 15 (13) ◽  
pp. 18285-18325
Author(s):  
P. Sacha ◽  
A. Kuchar ◽  
C. Jacobi ◽  
P. Pisoft
Keyword(s):  
Gravity Wave ◽  
Radio Occultation ◽  
Coastal Region ◽  
Internal Gravity Wave ◽  
Wave Activity ◽  
Density Profiles ◽  
Cycle Amplitude ◽  
Northeastern Pacific ◽  
Middle Atmospheric Dynamics ◽  
The Mean

Abstract. We have found a stratospheric area of anomalously low annual cycle amplitude and specific dynamics in the stratosphere over the Northeastern Pacific/Eastern Asia coastal region. Using GPS radio occultation density profiles from FORMOSAT-3/COSMIC, we have discovered an internal gravity wave activity and breaking hotspot in this region. Conditions supporting orographic wave sourcing and propagation were found. Other possible sources of wave activity in this region are listed. The reasons, why this particular IGW activity hotspot was not discovered before nor the specific dynamics of this region was pointed out, are discussed together with weaknesses of using the mean potential energy as a wave activity proxy. Possible consequences of the specific dynamics in this region on the middle atmospheric dynamics and transport are outlined.

scholarly journals Enhanced internal gravity wave activity and breaking over the northeastern Pacific–eastern Asian region

2015 ◽  
Vol 15 (22) ◽  
pp. 13097-13112 ◽  
Author(s):  
P. Šácha ◽  
A. Kuchař ◽  
C. Jacobi ◽  
P. Pišoft
Keyword(s):  
Gravity Wave ◽  
Coastal Region ◽  
Internal Gravity Wave ◽  
Wave Activity ◽  
Satellite Mission ◽  
Density Profiles ◽  
Cycle Amplitude ◽  
Northeastern Pacific ◽  
Middle Atmospheric Dynamics ◽  
The Mean

Abstract. We have found a stratospheric area of anomalously low annual cycle amplitude and specific dynamics in the stratosphere over the northeastern Pacific–eastern Asia coastal region. Using GPS radio occultation density profiles from the Formosat Satellite Mission 3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC), we have discovered an internal gravity wave (IGW) activity and breaking hotspot in this region. Conditions supporting orographic wave sourcing and propagation were found. Other possible sources of wave activity in this region are listed. The reasons why this particular IGW activity hotspot was not discovered before as well as why the specific dynamics of this region have not been pointed out are discussed together with the weaknesses of using the mean potential energy as a wave activity proxy. Possible consequences of the specific dynamics in this region on the middle atmospheric dynamics and transport are outlined.

scholarly journals Reconstruction of internal gravity wave parameters from radio occultation retrievals of vertical temperature profiles in the Earth's atmosphere

2011 ◽  
Vol 4 (10) ◽  
pp. 2153-2162 ◽  
Author(s):  
V. N. Gubenko ◽  
A. G. Pavelyev ◽  
R. R. Salimzyanov ◽  
A. A. Pavelyev
Keyword(s):  
Gravity Wave ◽  
Wind Velocity ◽  
Radio Occultation ◽  
Internal Gravity Wave ◽  
Shear Instability ◽  
Temperature Profiles ◽  
Vertical Temperature ◽  
Earth’S Atmosphere ◽  
Wave Parameters ◽  
Earth's Atmosphere

Abstract. A new method for the reconstruction of internal gravity wave (IGW) parameters from a single vertical temperature profile measurement in the Earth's atmosphere has been developed. This method does not require any additional information not contained in the profile and may be used for the analysis of profiles measured by various techniques. The criterion for the IGW identification has been formulated and argued. In the case when this criterion is satisfied, then analyzed temperature fluctuations can be considered as wave-induced. The method is based on the analysis of relative amplitude thresholds of the temperature wave field and on the linear IGW saturation theory in which amplitude thresholds are restricted by dynamical (shear) instability processes in the atmosphere. When the amplitude of an internal gravity wave reaches the shear instability limit, energy is assumed to be dissipated in such a way that the amplitude is maintained at the instability limit as the wave propagates upwards. In order to approbate the method we have used data of simultaneous high-resolution balloon measurements of the temperature and wind velocity in the Earth's stratosphere over France where a long-period inertia-gravity wave has been detected. Using the radiosonde temperature data only, we have reconstructed all wave parameters, which were determined by radiosondes, with relative deviations not larger than 30%. An application of the method to the radio occultation (RO) data has given the possibility to identify the IGWs in the Earth's stratosphere and to determine the magnitudes of key wave parameters such as the intrinsic frequency, amplitudes of vertical and horizontal perturbations of the wind velocity, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase (and group) speeds, kinetic and potential energy, vertical fluxes of the wave energy and horizontal momentum. The obtained results of internal wave studies in the Earth's stratosphere deduced from the COSMIC and CHAMP GPS occultation temperature profiles are presented and discussed.

scholarly journals Analysis of internal gravity waves with GPS RO density profiles

2014 ◽  
Vol 7 (12) ◽  
pp. 4123-4132 ◽  
Author(s):  
P. Šácha ◽  
U. Foelsche ◽  
P. Pišoft
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Internal Gravity Wave ◽  
Internal Gravity Waves ◽  
Atmospheric Density ◽  
Retrieval Process ◽  
Density Profiles ◽  
Height Range ◽  
Upper Troposphere ◽  
The Past

Abstract. GPS radio occultation (RO) data have proved to be a great tool for atmospheric monitoring and studies. In the past decade, they were frequently used for analyses of the internal gravity waves in the upper troposphere and lower stratosphere region. Atmospheric density is the first quantity of state gained in the retrieval process and is not burdened by additional assumptions. However, there are no studies elaborating in detail the utilization of GPS RO density profiles for gravity wave analyses. In this paper, we introduce a method for density background separation and a methodology for internal gravity wave analysis using the density profiles. Various background choices are discussed and the correspondence between analytical forms of the density and temperature background profiles is examined. In the stratosphere, a comparison between the power spectrum of normalized density and normalized dry temperature fluctuations confirms the suitability of the density profiles' utilization. In the height range of 8–40 km, results of the continuous wavelet transform are presented and discussed. Finally, the limits of our approach are discussed and the advantages of the density usage are listed.

scholarly journals Reconstruction of internal gravity wave parameters from radio occultation retrievals of vertical temperature profiles in the Earth atmosphere

2011 ◽  
Vol 4 (2) ◽  
pp. 1397-1425
Author(s):  
V. N. Gubenko ◽  
A. G. Pavelyev ◽  
R. R. Salimzyanov ◽  
A. A. Pavelyev
Keyword(s):  
Gravity Wave ◽  
Wind Velocity ◽  
Radio Occultation ◽  
Internal Gravity Wave ◽  
Shear Instability ◽  
Temperature Profiles ◽  
Earth Atmosphere ◽  
Vertical Temperature ◽  
Wave Parameters ◽  
The Earth

Abstract. The new method for the reconstruction of internal gravity wave (IGW) parameters from a single vertical temperature profile measurement in the Earth atmosphere has been developed. This method does not require any additional information not contained in the profile and may be used for the analysis of profiles measured by various techniques. The criterion for the IGW identification has been formulated and argued. In the case when this criterion is satisfied, then analyzed temperature fluctuations can be considered as wave-induced. The method is based on the analysis of relative amplitude thresholds of the temperature wave field and on the linear IGW saturation theory in which amplitude thresholds are restricted by dynamical (shear) instability processes in the atmosphere. When the amplitude of an internal gravity wave reaches the shear instability limit, energy is assumed to be dissipated in such a way that the amplitude is maintained at the instability limit as the wave propagates upwards. In order to approbate the method we have used in situ data of simultaneous balloon high-resolution measurements of the temperature and wind velocity in the Earth stratosphere (France) where a long-period inertia-gravity wave has been detected. Using the temperature data only, we have reconstructed all the measured wave parameters with uncertainties not larger than 30%. An application of the method to the radio occultation data has given the possibility to identify the IGWs in the Earth stratosphere and to determine the magnitudes of key wave parameters such as the intrinsic frequency, amplitudes of vertical and horizontal perturbations of the wind velocity, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase (and group) speeds, kinetic and potential energy, vertical fluxes of the wave energy and horizontal momentum. The obtained results of internal wave studies in the Earth stratosphere deduced from the COSMIC and CHAMP GPS occultation temperature profiles have been presented and discussed.

scholarly journals Influence of the spatial distribution of gravity wave activity on the middle atmospheric circulation and transport

2016 ◽  
Author(s):  
Petr Šácha ◽  
Friederike Lilienthal ◽  
Christoph Jacobi ◽  
Petr Pišoft
Keyword(s):  
Spatial Distribution ◽  
Gravity Wave ◽  
Atmospheric Circulation ◽  
Large Scale ◽  
Mechanistic Model ◽  
Polar Vortex ◽  
Wave Activity ◽  
Residual Circulation ◽  
Density Profiles ◽  
Longitudinal Variability

Abstract. Analyzing GPS radio occultation density profiles, we have recently pointed out a localized area of enhanced gravity wave (GW) activity and breaking in the lower stratosphere of the Eastern Asia/North-western Pacific (EA/NP) region. With a mechanistic model for the middle and upper atmosphere (MUAM), experiments are performed to study a possible effect of such a localized IGW breaking region on the large-scale circulation and transport and also more generally, possible influence of spatial distribution of gravity wave activity on the middle atmospheric circulation and transport. The results indicate an important role of the spatial distribution of GW activity for the polar vortex stability, formation of planetary waves (PW) and for the strength and structure of the zonal mean residual circulation. Also, a possible effect of a zonally asymmetric GW breaking in the longitudinal variability of Brewer–Dobson circulation is analyzed. Finally, consequences of our results for a variety of research topics (Sudden Stratospheric Warmings, atmospheric blocking, teleconnections and a compensation mechanism between resolved and unresolved drag) are discussed.

On strongly nonlinear gravity waves in a vertically sheared atmosphere

2021 ◽  
Author(s):  
Georg Sebastian Voelker ◽  
Mark Schlutow
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Internal Gravity Wave ◽  
Internal Gravity Waves ◽  
Wave Drag ◽  
Mean Flow ◽  
Flow Strength ◽  
Weakly Nonlinear ◽  
Strongly Nonlinear ◽  
The Mean

<p>Internal gravity waves are a well-known mechanism of energy redistribution in stratified fluids such as the atmosphere. They may propagate from their generation region, typically in the Troposphere, up to high altitudes. During their lifetime internal waves couple to the atmospheric background through various processes. Among the most important interactions are the exertion of wave drag on the horizontal mean-flow, the heat generation upon wave breaking, or the mixing of atmospheric tracers such as aerosols or greenhouse gases.</p><p>Many of the known internal gravity wave properties and interactions are covered by linear or weakly nonlinear theories. However, for the consideration of some of the crucial effects, like a reciprocal wave-mean-flow interaction including the exertion of wave drag on the mean-flow, strongly nonlinear systems are required. That is, there is no assumption on the wave amplitude relative to the mean-flow strength such that they may be of the same order.</p><p>Here, we exploit a strongly nonlinear Boussinesq theory to analyze the stability of a stationary internal gravity wave which is refracted at the vertical edge of a horizontal jet. Thereby we assume that the incident wave is horizontally periodic, non-hydrostatic, and vertically modulated. Performing a linear stability analysis in the vicinity of the jet edge we find necessary and sufficient criteria for instabilities to grow. In particular, the refracted wave becomes unstable if its incident amplitude is large enough and both mean-flow horizontal winds, below and above the edge of the jet, do not exceed particular upper bounds.</p>

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