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

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.

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Variability of the Brunt–Väisälä frequency at the OH* layer height

Atmospheric Measurement Techniques ◽

10.5194/amt-10-4895-2017 ◽

2017 ◽

Vol 10 (12) ◽

pp. 4895-4903 ◽

Cited By ~ 9

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 subnetwork of identical NDMC (Network for the Detection of Mesospheric Change, https://www.wdc.dlr.de/ndmc/) instruments can be found: five stations are equipped with OH* spectrometers which deliver a time series of mesopause temperature for each cloudless or only partially cloudy night. These measurements are suitable for the derivation of the density of gravity wave potential energy, provided that the Brunt–Väisälä frequency is known. However, OH* spectrometers do not deliver vertically resolved temperature information, which is 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.

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Variability of the Brunt–Väisälä frequency at the OH∗-airglow layer height at low and midlatitudes

Atmospheric Measurement Techniques ◽

10.5194/amt-13-6067-2020 ◽

2020 ◽

Vol 13 (11) ◽

pp. 6067-6093

Author(s):

Sabine Wüst ◽

Michael Bittner ◽

Jeng-Hwa Yee ◽

Martin G. Mlynczak ◽

James M. Russell III

Keyword(s):

Potential Energy ◽

Gravity Waves ◽

Local Thermodynamic Equilibrium ◽

Temperature Data ◽

Kinetic Temperature ◽

Temperature Variations ◽

Layer Height ◽

Wave Potential ◽

Broadband Emission ◽

Low Latitudes

Abstract. Airglow spectrometers, as they are operated within the Network for the Detection of Mesospheric Change (NDMC; https://ndmc.dlr.de, last access: 1 November 2020), for example, allow the derivation of rotational temperatures which are equivalent to the kinetic temperature, local thermodynamic equilibrium provided. Temperature variations at the height of the airglow layer are, amongst others, caused by gravity waves. However, airglow spectrometers do not deliver vertically resolved temperature information. This is an obstacle for the calculation of the density of gravity wave potential energy from these measurements. As Wüst et al. (2016) showed, the density of wave potential energy can be estimated from data of OH∗-airglow spectrometers if co-located TIMED-SABER (Thermosphere Ionosphere Mesosphere Energetics Dynamics, Sounding of the Atmosphere using Broadband Emission Radiometry) measurements are available, since they allow the calculation of the Brunt–Väisälä frequency. If co-located measurements are not available, a climatology of the Brunt–Väisälä frequency is an alternative. Based on 17 years of TIMED-SABER temperature data (2002–2018), such a climatology is provided here for the OH∗-airglow layer height and for a latitudinal longitudinal grid of 10∘×20∘ at midlatitudes and low latitudes. Additionally, climatologies of height and thickness of the OH∗-airglow layer are calculated.

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Variability of the Brunt-Väisälä frequency at the OH-airglow layer height at low and mid latitudes

10.5194/amt-2020-73 ◽

2020 ◽

Author(s):

Sabine Wüst ◽

Michael Bittner ◽

Jeng-Hwa Yee ◽

Martin G. Mlynczak ◽

James M. Russell III

Keyword(s):

Potential Energy ◽

Gravity Waves ◽

Local Thermodynamic Equilibrium ◽

Temperature Data ◽

Kinetic Temperature ◽

Temperature Variations ◽

Layer Height ◽

Wave Potential ◽

Broadband Emission ◽

Low Latitudes

Abstract. Airglow spectrometers as they are operated within the Network for the Detection of Mesospheric Change (NDMC, https://ndmc.dlr.de, for example, allow the derivation of rotational temperatures which are equivalent to the kinetic temperature, local thermodynamic equilibrium provided. Temperature variations at the height of the airglow layer are amongst others caused by gravity waves. However, airglow spectrometers do not deliver vertically-resolved temperature information. This is an obstacle for the calculation of the density of gravity wave potential energy from these measurements. As Wüst et al. (2016) showed, the density of wave potential energy can be estimated from data of OH* airglow spectrometers if co-located TIMED-SABER (Thermosphere Ionosphere Mesosphere Energetics Dynamics, Sounding of the Atmosphere using Broadband Emission Radiometry) measurements are available since they allow the calculation of the Brunt-Väisälä frequency. If co-located measurements are not available, a climatology of the Brunt-Väisälä frequency is an alternative. Based on 17 years of TIMED-SABER temperature data (2002–2018) such a climatology is provided here for the OH* airglow layer height and for a latitudinal longitudinal grid of 10° × 20° at mid and low latitudes. Additionally, climatologies of height and thickness of the OH* airglow layer are calculated.

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Analysis of synoptic scale controlling factors in the distribution of gravity wave potential energy

Journal of Atmospheric and Solar-Terrestrial Physics ◽

10.1016/j.jastp.2015.10.020 ◽

2015 ◽

Vol 135 ◽

pp. 126-135 ◽

Cited By ~ 4

Author(s):

Shih-Sian Yang ◽

C.J. Pan ◽

Uma Das ◽

H.C. Lai

Keyword(s):

Potential Energy ◽

Gravity Wave ◽

Controlling Factors ◽

Synoptic Scale ◽

Wave Potential

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Vertical distribution of gravity wave potential energy from long-term Rayleigh lidar data at a northern middle-latitude site

Journal of Geophysical Research Atmospheres ◽

10.1002/2014jd022035 ◽

2014 ◽

Vol 119 (21) ◽

pp. 12,069-12,083 ◽

Cited By ~ 17

Author(s):

N. Mzé ◽

A. Hauchecorne ◽

P. Keckhut ◽

M. Thétis

Keyword(s):

Potential Energy ◽

Vertical Distribution ◽

Gravity Wave ◽

Middle Latitude ◽

Lidar Data ◽

Wave Potential ◽

Rayleigh Lidar

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

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-20-0247.1 ◽

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.

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

10.5194/egusphere-egu21-9116 ◽

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

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&#252;hlungsborn (54&#176;N, 12&#176;E) and at ALOMAR (69&#176;N, 16&#176;E). Our analysis technique includes different types of filtering which allow for selection of different ranges from the entire GW-spectrum. We studied wave properties as a function of altitude and location and summarized the results in monthly and seasonally mean profiles. Complementary 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. A seasonal cycle of gravity wave potential energy density (GWPED) 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 to summer ratios are a factor of about&#160;3. The winter to summer ratios are nearly identical at both stations. GWPEDs from reanalysis are smaller compared to lidar. The difference increases with altitude in winter and reaches almost two orders of magnitude around 70&#160;km.GWPEDs per volume decreases with height differently for the winter and summer seasons, irrespective of filtering method and location. In summer for altitudes above roughly 50&#160;km, GWPED is nearly constant or even increases with height. This feature is very pronounced at ALOMAR and to a lesser extent also at K&#252;hlungsborn. This behavior is seen by both, lidar and SABER. The observed variation of GWPED with height can not be explained by conservation of wave action alone. The GWPED at K&#252;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. We present results of observations and analyses and suggest geophysical explanations of our findings.&#160;&#160;

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