Probing the Analytical Cancelation Factor of Short Scale Gravity Waves Using Na Lidar and Nightglow Data from the Andes Lidar Observatory (original) (raw)
Related papers
2020
The cancellation factor (CF) is a model for the ratio between gravity wave perturbations in the nightglow intensity to those in the ambient temperature. The CF model allows us to estimate the momentum and energy flux of gravity waves seen in nightglow images, as well as the divergence of these fluxes due to waves propagating through the mesosphere and lower thermosphere region, where the nightglow and the Na layers are located. This study uses a set of wind/temperature Na lidar data and zenith nightglow image observations of the OH and O(1S) emissions to test and validate the CF model from the experimental perspective. The dataset analyzed was obtained during campaigns carried out at the Andes Lidar Observatory (ALO), Chile, in 2015, 2016, and 2017. The modeled CF was compared with observed CF values calculated using the ratio of wave amplitude in nightglow images to that seen in lidar temperatures for vertically propagating waves. We show that, in general, the modeled CF underestim...
The cancellation factor (CF) is a model for the ratio between gravity wave perturbations in the airglow intensity to those in the ambient temperature, and is necessary to estimate the momentum and energy flux and flux divergence of gravity waves in the airglow emissions. This study tests the CF model using T/W Na Lidar data and zenith nightglow observations of the OH and O(1 S) emissions. The dataset analyzed was obtained during the campaigns carried out in 2015, 2016, and 2017 at the Andes Lidar Observatory (ALO) in Chile. We have used an empirical method to fit the analytical function that describes the CF for vertically propagating waves, and compared the quantities through the ratio of airglow wave amplitude registered as dominant event in the images to the the wave amplitude in the lidar temperature. We show that the analytical relationship underestimates the observational results. We obtained a good agreement respect to the theoretical value for O(1 S) emission line. In contrast, the observational CF ratio deviates by a factor of ∼ 2 from the analytical value for the OH emission.
Amplitude growth rates of monochromatic gravity waves were estimated and compared from multiple instrument measurements carried out in Brazil. Wave dynamic parameters were obtained from sodium density profiles from lidar observations carried out in Sao Jose dos Campos (23°S, 46°W), while all-sky images of multiple airglow layers provided amplitudes and parameters of waves over Cachoeira Paulista (23°S, 45°W). Growth rates of gravity wave amplitudes from lidar and airglow imager data were consistent with dissipative wave behavior. Only a small amount of the observed wave events presented freely propagating behavior. Part of the observed waves presented saturated amplitude. The general saturated/damped behavior is consistent with diffusive filtering processes imposing limits to amplitude growth rates of the observed gravity waves.
Journal of the Atmospheric Sciences, 2021
We 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 ...
Journal of Geophysical Research: Atmospheres, 2016
On 23 March 2012, our all-sky imager recorded a concentric, ring-like gravity wave pattern. The wave arose within the area covered by images of both OH and O(1 S) nightglow emissions taken at the Andes Lidar Observatory (ALO), Chile (30.3 ∘ S, 70.7 ∘ W). We have estimated the observed and intrinsic parameters of the event and located the wave source within the lower mesosphere altitude range using a reverse ray tracing method. By the analysis of GOES and LIS satellite images, we have not found evidence of neither convective nor lightning activity nearby ALO, indicating that the source of the ring-like wave was not directly in the troposphere. The absence of tropospheric activity and the height of the source of the event suggest that a secondary wave generation mechanism might be the cause of the ring-like wave. The secondary wave mechanism was likely triggered by a breaking, larger-scale primary wave excited by deep convection ∼1400 km northeast of ALO over Bolivia, as determined by a forward ray tracing scheme.
Gravity wave parameters and their seasonal variations derived from Na lidar observations at 23°S
Journal of Geophysical Research, 2006
1] The nightly and seasonal variability of gravity wave activity and spectra in the mesopause region are studied with 10 years of sodium lidar observations. From the linear layer density response to gravity wave forcing, the lidar data were analyzed to get the atmospheric density perturbations and their spectra. The atmospheric density perturbation, density variance for fluctuations with vertical scales between 2 and 10 km, and amplitudes of density perturbation spectra at m = 2p/8 km and 2p/4 km all exhibit large nightly variability as well as large seasonal variations, with the semiannual maxima occurring near the equinoxes. The mean RMS atmospheric density perturbation and the mean RMS horizontal wind perturbations over our site are 5.1% and 25 m/s, respectively. The growth lengths of the density perturbations in spring and autumn are lower than those in summer and winter, and the annual mean value is 38 km. The annual mean density shear variance is about 15 (%/km) 2 , and the maxima occur near the equinoxes. The mean Richardson number is about 1.0. The mean value of the RMS vertical wind perturbation is 0.85 m/s with a maximum occurring at the end of the year. The m spectra show power law shapes, and their range of variation is between À2.06 and À3.81 with an annual mean value of À2.93. The w spectra also show power law shapes, and their range of variation is between À1.06 and À2.32, with an annual mean of À1.64. The mean amplitudes of density perturbation spectrum, Fa(m) (m = 2p/4 km), and of the horizontal wind fluctuation, Fu(m) (m = 2p/4 km), are 1.35(m/cycles) and 3 Â 10 5 (m 2 s À2 /(cycles/m)), respectively. The value of l z * averaged around autumn equinox is 14.8 km, which is lower than the value of 16.8 km, averaged around spring equinox. The annual mean of T* is 23.5 hours. The fact that the joint (m,w) spectra are not separable, together with the large variability found in the m spectra slopes, is not compatible with linear instability theory but is compatible with Doppler spreading theories and diffusive filtering theory.
Journal of Geophysical Research: Atmospheres, 2018
Gravity wave (GW) activity is analyzed using temperature (T) data retrieved from a Rayleigh light detection and ranging (lidar) at Río Gallegos, Argentina (51.6°S, 69.3°W). GW characteristics are derived from 302 nights of observations providing more than 1,018 hr of high‐resolution lidar data between 20‐ and 56‐km height from August 2005 to December 2015. T measurements are performed by a Differential Absorption Lidar instrument. This lidar was the southernmost outside Antarctica until the end of 2017. Río Gallegos is an exceptional place to observe large amplitude GW. Every lidar measurement is classified according to its relative position to the polar vortex. The lidar measurements are compared with collocated Sounding of the Atmosphere using Broadband Emission Radiometry and Global Positioning System‐Radio Occultation data. The different instruments show different windows of the GW spectrum, providing complementary observations. In general, the geometric mean of the specific GW ...
Evidence of gravity wave breaking in lidar data from the mesopause region
Geophysical Research Letters, 2003
An outstanding question about the dynamics of the mesosphere is the temporal and spatial distribution of nonlinear events such as wave-breaking, wave saturation, and wave-critical layer interactions. A climatology of these events will help us understand how the mesoscale dynamical features, such as gravity waves, interact with the background mean wind and temperature structure. New lidar systems have the resolution to show us a height versus time ''picture'' of the dynamics so that identifying individual events within the observation window of the instrument is now possible. At the Starfire Optical Range (SOR) a sodium resonance lidar provides simulataneous sodium density, temperature, and three components of the winds. In this paper we present ''pictures'' of individual wave events apparent in the lidar data using the temperature (plotted as potential temperature and spectra) to show the time evolution of the wave structure.