General characteristics of Gravity Wave Potential Energy Density at 54 ºN and 69 ºN
- Leibniz Institute of Atmospheric Physics, Optical Soundings and Sounding Rockets, Kühlungsborn, Germany (strelnikova@iap-kborn.de)
We present results of seven years of gravity waves (GW) observations between 2012 and 2018. The measurements were conducted by ground-based lidars in Kühlungsborn (54°N, 12°E) and at ALOMAR (69°N, 16°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 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 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 km, GWPED is nearly constant or even increases with height. This feature is very pronounced at ALOMAR and to a lesser extent also at Kühlungsborn. 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 Kühlungsborn 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.
How to cite: Strelnikova, I., Baumgarten, G., Baumgarten, K., Ern, M., Gerding, M., and Lübken, F.-J.: General characteristics of Gravity Wave Potential Energy Density at 54 ºN and 69 ºN, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9116, https://doi.org/10.5194/egusphere-egu21-9116, 2021.
