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;

scholarly journals Long-term Lidar Observations of the Gravity Wave Activity near the Mesopause at Arecibo

2018 ◽  
Author(s):  
Xianchang Yue ◽  
Jonathan S. Friedman ◽  
Qihou Zhou ◽  
Xiongbin Wu ◽  
Jens Lautenbach
Keyword(s):  
Potential Energy ◽  
Gravity Wave ◽  
Inversion Layer ◽  
Lower Thermosphere ◽  
Temperature Inversion ◽  
Temperature Structure ◽  
Mean Temperature ◽  
The Mean ◽  
Highly Correlated ◽  
Lidar Observations

Abstract. 11-years long K Doppler lidar observations of temperature profiles in the mesosphere and lower thermosphere (MLT) between 85 and 100 km, conducted at the Arecibo Observatory, Puerto Rico (18.35° N, 66.75° W), are used to estimate seasonal variations of the mean temperature, the squared Brunt-Väisälä frequency, and the gravity wave potential energy in a composite year. The following unique features are obtained: (1) The mean temperature structure shows similar characteristics as a prior report based on a smaller dataset: (2) The profiles of the squared Brunt-Väisälä frequency usually reach the maxima at or just below the temperature inversion layer when that layer is present. The first complete range-resolved climatology of potential energy of temperature fluctuations in the tropical MLT exhibits an altitude dependent combination of annual oscillation (AO) and semiannual oscillation (SAO). Between 88 to 96 km altitude, the amplitudes of AO and SAO are comparable, and their phases are almost the same and quite close to day of year (DOY) 100. Below 88 km, the SAO amplitude is significantly larger than AO and the AO phase shifts to DOY 200 and after. At 97 to 98 km altitude, the amplitudes of AO and SAO reach their minima, and both phases shift significantly. Above that, the AO amplitude becomes greater. The annual mean potential energy profile reaches the minimum at 91 to 92 km altitude. The altitude-dependent SAO of the potential energy is found to be highly correlated with the satellite observed mean zonal winds reported in the literature.

scholarly journals Sea surface temperature as a proxy for convective gravity wave excitation: a study based on global gravity wave observations in the middle atmosphere

2014 ◽  
Vol 32 (11) ◽  
pp. 1373-1394 ◽  
Author(s):  
J. Y. Jia ◽  
P. Preusse ◽  
M. Ern ◽  
H.-Y. Chun ◽  
J. C. Gille ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Gravity Wave ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Correlation Coefficients ◽  
Sea Surface ◽  
Broadband Emission ◽  
Global Gravity ◽  
Ray Tracing Simulation

Abstract. Absolute values of gravity wave momentum flux (GWMF) deduced from satellite measurements by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument and the High Resolution Dynamics Limb Sounder (HIRDLS) are correlated with sea surface temperature (SST) with the aim of identifying those oceanic regions for which convection is a major source of gravity waves (GWs). Our study identifies those latitude bands where high correlation coefficients indicate convective excitation with confidence. This is based on a global ray-tracing simulation, which is used to delineate the source and wind-filtering effects. Convective GWs are identified at the eastern coasts of the continents and over the warm water regions formed by the warm ocean currents, in particular the Gulf Stream and the Kuroshio. Potential contributions of tropical cyclones to the excitation of the GWs are discussed. Convective excitation can be identified well into the mid-mesosphere. In propagating upward, the centers of GWMF formed by convection shift poleward. Some indications of the main forcing regions are even shown for the upper mesosphere/lower thermosphere (MLT).

scholarly journals A comprehensive observational filter for satellite infrared limb sounding of gravity waves

2014 ◽  
Vol 7 (10) ◽  
pp. 10771-10827
Author(s):  
Q. T. Trinh ◽  
S. Kalisch ◽  
P. Preusse ◽  
H.-Y. Chun ◽  
S. D. Eckermann ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Tangent Point ◽  
Vertical Wavelength ◽  
Broadband Emission ◽  
Filter Process ◽  
High Level ◽  
Observation Geometry ◽  
Horizontal Wavelength ◽  
Wavelength Distribution

Abstract. This paper describes a comprehensive observational filter for satellite infrared limb sounding of gravity waves. The filter considers instrument visibility and observation geometry with a high level of accuracy. It contains four main processes: visibility filter, projection of the wavelength on the tangent-point track, aliasing effect, and calculation of the observed vertical wavelength. The observation geometries of the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) and HIRDLS (High Resolution Dynamics Limb Sounder) are mimicked. Gravity waves (GWs) simulated by coupling a convective GW source (CGWS) scheme and the gravity wave regional or global ray tracer (GROGRAT) are used as an example for applying the observational filter. Simulated spectra in terms of horizontal and vertical wave numbers (wavelengths) of gravity wave momentum flux (GWMF) are analyzed under the influence of the filter. We find that the most important processes, which have significant influence on the spectrum are: visibility filter (for both SABER and HIRDLS observation geometries), aliasing for SABER and projection on tangent-point track for HIRDLS. The vertical wavelength distribution is mainly affected by the retrieval as part of the "visibility filter" process. In addition, the short-horizontal-scale spectrum may be projected for some cases into a longer horizontal wavelength interval which originally was not populated. The filter largely reduces GWMF values of very short horizontal wavelength waves. The implications for interpreting observed data are discussed.

scholarly journals Derivation of gravity wave intrinsic parameters and vertical wavelength using a single scanning OH(3-1) airglow spectrometer

2018 ◽  
Vol 11 (5) ◽  
pp. 2937-2947 ◽  
Author(s):  
Sabine Wüst ◽  
Thomas Offenwanger ◽  
Carsten Schmidt ◽  
Michael Bittner ◽  
Christoph Jacobi ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Spatial Information ◽  
Rotational Transition ◽  
Horizontal Wind ◽  
Vertical Temperature ◽  
Vertical Wavelength ◽  
Broadband Emission ◽  
Wind Measurements ◽  
First Time

Abstract. For the first time, we present an approach to derive zonal, meridional, and vertical wavelengths as well as periods of gravity waves based on only one OH* spectrometer, addressing one vibrational-rotational transition. Knowledge of these parameters is a precondition for the calculation of further information, such as the wave group velocity vector. OH(3-1) spectrometer measurements allow the analysis of gravity wave ground-based periods but spatial information cannot necessarily be deduced. We use a scanning spectrometer and harmonic analysis to derive horizontal wavelengths at the mesopause altitude above Oberpfaffenhofen (48.09∘ N, 11.28∘ E), Germany for 22 nights in 2015. Based on the approximation of the dispersion relation for gravity waves of low and medium frequencies and additional horizontal wind information, we calculate vertical wavelengths. The mesopause wind measurements nearest to Oberpfaffenhofen are conducted at Collm (51.30∘ N, 13.02∘ E), Germany, ca. 380 km northeast of Oberpfaffenhofen, by a meteor radar. In order to compare our results, vertical temperature profiles of TIMED-SABER (thermosphere ionosphere mesosphere energetics dynamics, sounding of the atmosphere using broadband emission radiometry) overpasses are analysed with respect to the dominating vertical wavelength.

scholarly journals The Seasonal Cycle of Gravity Wave Drag in the Middle Atmosphere

2008 ◽  
Vol 21 (18) ◽  
pp. 4664-4679 ◽  
Author(s):  
Manuel Pulido ◽  
John Thuburn
Keyword(s):  
Gravity Wave ◽  
Seasonal Cycle ◽  
Middle Atmosphere ◽  
Three Dimensional ◽  
Wave Drag ◽  
Smooth Transition ◽  
Quasi Biennial Oscillation ◽  
Summer Hemisphere ◽  
Jet Streaks ◽  
Biennial Oscillation

Abstract Using a variational technique, middle atmosphere gravity wave drag (GWD) is estimated from Met Office middle atmosphere analyses for the year 2002. The technique employs an adjoint model of a middle atmosphere dynamical model to minimize a cost function that measures the differences between the model state and observations. The control variables are solely the horizontal components of GWD; therefore, the minimization determines the optimal estimate of the drag. For each month, Met Office analyses are taken as the initial condition for the first day of the month, and also as observations for each successive day. In this way a three-dimensional GWD field is obtained for the entire year with a temporal resolution of 1 day. GWD shows a pronounced seasonal cycle. During solstices, there are deceleration regions of the polar jet centered at about 63° latitude in the winter hemisphere, with a peak of 49 m s−1 day−1 at 0.24 hPa in the Southern Hemisphere; the summer hemisphere also shows a deceleration region but much weaker, with a peak of 24 m s−1 day−1 centered at 45° latitude and 0.6 hPa. During equinoxes GWD is weak and exhibits a smooth transition between the winter and summer situation. The height and latitude of the deceleration center in both winter and summer hemispheres appear to be constant. Important longitudinal dependencies in GWD are found that are related to planetary wave activity; GWD intensifies in the exit region of jet streaks. In the lower tropical stratosphere, the estimated GWD shows a westward GWD descending together with the westward phase of the quasi-biennial oscillation. Above, GWD exhibits a semiannual pattern that is approximately out of phase with the semiannual oscillation in the zonal wind. Furthermore, a descending GWD pattern is found at those heights, similar in magnitude and sign to that in the lower stratosphere.

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
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