scholarly journals Investigating the Spatio-Temporal Distribution of Gravity Wave Potential Energy over the Equatorial Region Using the ERA5 Reanalysis Data

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 311
Author(s):  
Shih-Sian Yang ◽  
Chen-Jeih Pan ◽  
Uma Das
Keyword(s):  
Potential Energy ◽  
Gravity Wave ◽  
Zonal Wind ◽  
Thermal Structure ◽  
Temporal Distribution ◽  
Energy Coupling ◽  
Equatorial Region ◽  
Mean Flow ◽  
Wave Potential ◽  
Wind Shears

Atmospheric gravity waves play a crucial role in affecting atmospheric circulation, energy transportation, thermal structure, and chemical composition. Using ERA5 temperature data, the present study investigates the tropospheric to the lower mesospheric gravity wave potential energy (EP) over the equatorial region to understand the vertical coupling of the atmosphere. EP is mainly controlled by two factors. The first is zonal wind through wave–mean flow interactions, and thus EP has periodic variations that are correlated to the zonal wind oscillations and enhances around the altitudes of zero-wind shears where the zonal wind reverses. The second is the convections caused by atmospheric circulations and warm oceans, resulting in longitudinal variability in EP. The lower stratospheric and the lower mesospheric EP are negatively correlated. However, warm oceanic conditions can break this wave energy coupling and further enhance the lower mesospheric EP.

scholarly journals Seasonal Cycle of Gravity Wave Potential Energy Densities from Lidar and Satellite Observations at 54° and 69°N

2021 ◽  
Vol 78 (4) ◽  
pp. 1359-1386
Author(s):  
Irina Strelnikova ◽  
Marwa Almowafy ◽  
Gerd Baumgarten ◽  
Kathrin Baumgarten ◽  
Manfred Ern ◽  
...  
Keyword(s):  
Potential Energy ◽  
Gravity Wave ◽  
Seasonal Cycle ◽  
Middle Atmosphere ◽  
Reanalysis Data ◽  
Vertical Wavelength ◽  
Wave Potential ◽  
Broadband Emission ◽  
The Difference ◽  
Lidar Observations

AbstractWe present gravity wave climatologies based on 7 years (2012–18) of lidar and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperatures and reanalysis data at 54° and 69°N in the altitude range 30–70 km. We use 9452 (5044) h of lidar observations at Kühlungsborn [Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR)]. Filtering according to vertical wavelength (λz < 15 km) or period (τ < 8 h) is applied. Gravity wave potential energy densities (GWPED) per unit volume (EpV) and per unit mass (Epm) are derived. GWPED from reanalysis are smaller compared to lidar. The difference increases with altitude in winter and reaches almost two orders of magnitude around 70 km. A seasonal cycle of EpV with maximum values in winter is present at both stations in nearly all lidar and SABER measurements and in reanalysis data. For SABER and for lidar (with λ < 15 km) the winter/summer ratios are a factor of ~2–4, but are significantly smaller for lidar with τ < 8 h. The winter/summer ratios are nearly identical at both stations and are significantly larger for Epm compared to EpV. Lidar and SABER observations show that EpV is larger by a factor of ~2 at Kühlungsborn compared to ALOMAR, independent of season and altitude. Comparison with mean background winds shows that simple scenarios regarding GW filtering, etc., cannot explain the Kühlungsborn–ALOMAR differences. The value of EpV decreases with altitude in nearly all cases. Corresponding EpV-scale heights from lidar are generally larger in winter compared to summer. Above ~55 km, EpV in summer is almost constant with altitude at both stations. The winter–summer difference of EpV scale heights is much smaller or absent in SABER and in reanalysis data.

General characteristics of Gravity Wave Potential Energy Density at 54 ºN and 69 ºN

2021 ◽  
Author(s):  
Irina Strelnikova ◽  
Gerd Baumgarten ◽  
Kathrin Baumgarten ◽  
Manfred Ern ◽  
Michael Gerding ◽  
...  
Keyword(s):  
Energy Density ◽  
Potential Energy ◽  
Gravity Wave ◽  
Reanalysis Data ◽  
Wave Potential ◽  
Doppler Shifts ◽  
Analysis Technique ◽  
Potential Impact ◽  
The Difference ◽  
Selection Of

&lt;p&gt;&lt;span&gt;We present results of seven years of gravity waves (GW) observations between 2012 and 2018. The measurements were conducted by ground-based lidars in K&amp;#252;hlungsborn (54&amp;#176;N, 12&amp;#176;E) and at ALOMAR (69&amp;#176;N, 16&amp;#176;E). Our analysis technique includes different types of filtering which allow for selection of different ranges from the entire GW-spectrum. We studied &lt;/span&gt;&lt;span&gt;wave&lt;/span&gt;&lt;span&gt; properties as a function of altitude and location and summarized the results in monthly and seasonally mean profiles. &lt;/span&gt;&lt;span&gt;Complementary&lt;/span&gt;&lt;span&gt; data is taken from the satellite-based SABER instrument. Additionally, we consistently applied our analysis technique to the reanalyses data from MERRA-2 and ERA-5. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;A&lt;span&gt; seasonal cycle of &lt;/span&gt;&lt;span&gt;gravity wave potential energy density &lt;/span&gt;&lt;span&gt;(&lt;/span&gt;&lt;span&gt;GWPED&lt;/span&gt;&lt;span&gt;)&lt;/span&gt;&lt;span&gt; with maximum values in winter is present at both stations in nearly all lidar/SABER measurements and in reanalysis data. For SABER and for lidar the winter &lt;/span&gt;&lt;span&gt;to &lt;/span&gt;&lt;span&gt;summer ratios are a factor of &lt;/span&gt;&lt;span&gt;about&amp;#160;3&lt;/span&gt;&lt;span&gt;. The winter &lt;/span&gt;&lt;span&gt;to &lt;/span&gt;&lt;span&gt;summer ratios are nearly identical at both stations. &lt;/span&gt;&lt;span&gt;GWPED&lt;/span&gt;&lt;span&gt;s&lt;/span&gt;&lt;span&gt; from reanalysis are smaller compared to lidar. The difference increases with altitude in winter and reaches almost two orders of magnitude around 70&amp;#160;km.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;GWPEDs per volume&lt;/span&gt;&lt;span&gt; decrease&lt;/span&gt;&lt;span&gt;s&lt;/span&gt;&lt;span&gt; with height &lt;/span&gt;&lt;span&gt;differently for the winter and summer seasons,&lt;/span&gt;&lt;span&gt; irrespective of filtering method and location. &lt;/span&gt;&lt;span&gt;In summer for altitudes above roughly 5&lt;/span&gt;&lt;span&gt;0&lt;/span&gt;&lt;span&gt;&amp;#160;km, GWPED is nearly constant or even increases with height. &lt;/span&gt;&lt;span&gt;T&lt;/span&gt;&lt;span&gt;his feature is very pronounced at ALOMAR and to a lesser extent also &lt;/span&gt;&lt;span&gt;at&lt;/span&gt;&lt;span&gt; K&amp;#252;hlungsborn. This behavior is seen &lt;/span&gt;&lt;span&gt;by both, lidar and SABER&lt;/span&gt;&lt;span&gt;. The observed variation of GWPED with height can not be explained by conservation of wave action alone. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;The &lt;/span&gt;&lt;span&gt;GWPED at K&lt;/span&gt;&lt;span&gt;&amp;#252;&lt;/span&gt;&lt;span&gt;hlungsborn is significantly larger compared to ALOMAR. This observation is opposite to simple scenarios which take into account the potential impact of background winds on GW filtering and Doppler shifts of vertical wavelengths and periods. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;W&lt;/span&gt;&lt;span&gt;e present results of &lt;/span&gt;&lt;span&gt;observations and&lt;/span&gt;&lt;span&gt; analyses &lt;/span&gt;&lt;span&gt;and suggest geophysical explanations of our findings.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Derivation of gravity wave potential energy density from NDMC measurements

2016 ◽  
Vol 138-139 ◽  
pp. 32-46 ◽  
Author(s):  
Sabine Wüst ◽  
Verena Wendt ◽  
Carsten Schmidt ◽  
Sabrina Lichtenstern ◽  
Michael Bittner ◽  
...  
Keyword(s):  
Energy Density ◽  
Potential Energy ◽  
Gravity Wave ◽  
Wave Potential

scholarly journals Characteristics of gravity waves generated in a convective and a non-convective environment revealed from hourly radiosonde observation under CPEA-II campaign

2011 ◽  
Vol 29 (12) ◽  
pp. 2259-2276 ◽  
Author(s):  
S. K. Dhaka ◽  
R. Bhatnagar ◽  
Y. Shibagaki ◽  
H. Hashiguchi ◽  
S. Fukao ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Zonal Wind ◽  
Wind Shear ◽  
Radiosonde Data ◽  
Strong Wind ◽  
Mean Flow ◽  
Vertical Wavelength ◽  
Short Period ◽  
Radiosonde Observation ◽  
Wind Shears

Abstract. Analyses of hourly radiosonde data of temperature, wind, and relative humidity during four days (two with convection and two with no convection) as a part of an intensive observation period in CPEA-2 campaign over Koto Tabang (100.32° E, 0.20° S), Indonesia, are presented. Characteristics of gravity waves in terms of dominant wave frequencies at different heights and their vertical wavelengths are shown in the lower stratosphere during a convective and non-convective period. Gravity waves with periods ~10 h and ~4–5 h were found dominant near tropopause (a region of high stability) on all days of observation. Vertical propagation of gravity waves were seen modified near heights of the three identified strong wind shears (at ~16, 20, and 25 km heights) due to wave-mean flow interaction. Between 17 and 21 km heights, meridional wind fluctuations dominated over zonal wind, whereas from 22 to 30 km heights, wave fluctuations with periods ~3–5 h and ~8–10 h in zonal wind and temperature were highly associated, suggesting zonal orientation of wave propagation. Gravity waves from tropopause region to 30 km heights were analyzed. In general, vertical wavelength of 2–5 km dominated in all the mean-removed (~ weekly mean) wind and temperature hourly profiles. Computed vertical wavelength spectra are similar, in most of the cases, to the source spectra (1–16 km height) except that of zonal wind spectra, which is broad during active convection. Interestingly, during and after convection, gravity waves with short vertical wavelength (~2 km) and short period (~2–3 h) emerged, which were confined in the close vicinity of tropopause, and were not identified on non-convective days, suggesting convection to be the source for them. Some wave features near strong wind shear (at 25 km height) were also observed with short vertical wavelengths in both convective and non-convective days, suggesting wind shear to be the sole cause of generation and seemingly not associated with deep convection below. A drop in the temperature up to ~4–5 K (after removal of diurnal component) was observed at ~16 km height near a strong wind shear (~45–55 m s−1 km−1) during active period of convection.

scholarly journals Variability of the Brunt-Väisälä frequency at the OH*-layer height

2017 ◽  
Author(s):  
Sabine Wüst ◽  
Michael Bittner ◽  
Jeng-Hwa Yee ◽  
Martin G. Mlynczak ◽  
James M. Russell III
Keyword(s):  
Time Series ◽  
Potential Energy ◽  
Gravity Wave ◽  
Temperature Data ◽  
Alpine Region ◽  
Layer Height ◽  
Wave Potential ◽  
Annual Variability ◽  
Mesopause Temperature

Abstract. In and near the Alpine region, the most dense sub-network of identical NDMC instruments (Network for the Detection of Mesospheric Change, http://wdc.dlr.de/ndmc) can be found: five stations are equipped with OH*-spectrometers which deliver a time series of mesopause temperature each cloudless or only partially cloudy night. These measurements are suitable for the derivation of the density of gravity wave potential energy—knowledge about the Brunt-Väisälä frequency provided. However, OH*-spectrometers do not deliver vertically-resolved temperature information, which are necessary for the calculation of the Brunt-Väisälä frequency. Co-located measurements or climatological values are needed. We use 14 years of satellite-based temperature data (TIMED-SABER, 2002–2015) to investigate the inter- and intra-annual variability of the Brunt-Väisälä frequency at the OH*-layer height between 43.93–48.09° N and 5.71–12.95° E and provide a climatology.

scholarly journals Application of deep learning to estimate stratospheric gravity wave potential energy

2022 ◽  
Vol 6 (0) ◽  
pp. 0-0
Author(s):  
Yue Wu ◽  
◽  
Zheng Sheng ◽  
and XinJie Zuo ◽  
◽  
...  
Keyword(s):  
Deep Learning ◽  
Potential Energy ◽  
Gravity Wave ◽  
Wave Potential

scholarly journals Convective gravity wave propagation and breaking in the stratosphere: comparison between WRF model simulations and lidar data

2015 ◽  
Vol 33 (9) ◽  
pp. 1155-1171 ◽  
Author(s):  
L. Costantino ◽  
P. Heinrich ◽  
N. Mzé ◽  
A. Hauchecorne
Keyword(s):  
Potential Energy ◽  
Gravity Wave ◽  
Drag Force ◽  
Lower Stratosphere ◽  
Lidar Data ◽  
Time Averaging ◽  
Grid Spacing ◽  
Mean Flow ◽  
Energy Propagation ◽  
Vertical Grid

Abstract. In this work we perform numerical simulations of convective gravity waves (GWs), using the WRF (Weather Research and Forecasting) model. We first run an idealized, simplified and highly resolved simulation with model top at 80 km. Below 60 km of altitude, a vertical grid spacing smaller than 1 km is supposed to reliably resolve the effects of GW breaking. An eastward linear wind shear interacts with the GW field generated by a single convective thunderstorm. After 70 min of integration time, averaging within a radius of 300 km from the storm centre, results show that wave breaking in the upper stratosphere is largely dominated by saturation effects, driving an average drag force up to −41 m s−1 day−1. In the lower stratosphere, mean wave drag is positive and equal to 4.4 m s−1 day−1. In a second step, realistic WRF simulations are compared with lidar measurements from the NDACC network (Network for the Detection of Atmospheric Composition Changes) of gravity wave potential energy (Ep) over OHP (Haute-Provence Observatory, southern France). Using a vertical grid spacing smaller than 1 km below 50 km of altitude, WRF seems to reliably reproduce the effect of GW dynamics and capture qualitative aspects of wave momentum and energy propagation and transfer to background mean flow. Averaging within a radius of 120 km from the storm centre, the resulting drag force for the study case (2 h storm) is negative in the higher (−1 m s−1 day−1) and positive in the lower stratosphere (0.23 m s−1 day−1). Vertical structures of simulated potential energy profiles are found to be in good agreement with those measured by lidar. Ep is mostly conserved with altitude in August while, in October, Ep decreases in the upper stratosphere to grow again in the lower mesosphere. On the other hand, the magnitude of simulated wave energy is clearly underestimated with respect to lidar data by about 3–4 times.

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