Spatial and temporal variability in MLT turbulence inferred from in situ and ground-based observations during the WADIS-1 sounding rocket campaign

In summer 2013 the WADIS-1 sounding rocket campaign was conducted at the Andøya Space Center (ACS) in northern Norway (69° N, 16° E). Among other things, it addressed the question of the variability in mesosphere/lower thermosphere (MLT) turbulence, both in time and space. A unique feature of the WADIS project was multi-point turbulence sounding applying different measurement techniques including rocket-borne ionization gauges, VHF MAARSY radar, and VHF EISCAT radar near Tromsø. This allowed for horizontal variability to be observed in the turbulence field in the MLT at scales from a few to 100 km. We found that the turbulence dissipation rate, ε varied in space in a wavelike manner both horizontally and in the vertical direction. This wavelike modulation reveals the same vertical wavelengths as those seen in gravity waves. We also found that the vertical mean value of radar observations of ε agrees reasonably with rocket-borne measurements. In this way defined 〈εradar〉 value reveals clear tidal modulation and results in variation by up to 2 orders of magnitude with periods of 24 h. The 〈εradar〉 value also shows 12 h and shorter (1 to a few hours) modulations resulting in one decade of variation in 〈εradar〉 magnitude. The 24 h modulation appeared to be in phase with tidal change of horizontal wind observed by SAURA-MF radar. Such wavelike and, in particular, tidal modulation of the turbulence dissipation field in the MLT region inferred from our analysis is a new finding of this work

Simultaneous in Situ Measurements of Small-Scale Structures in Neutral, Plasma, and Atomic Oxygen Densities During the WADIS Sounding Rocket Project

In this paper we present an overview of measurements conducted during the WADIS-2 rocket campaign. We investigate the effect of small-scale processes like gravity waves and turbulence on the distribution of atomic oxygen and other species in the mesosphere–lower thermosphere (MLT) region. Our analysis suggests that density fluctuations of atomic oxygen are coupled to fluctuations of other constituents, i.e., plasma and neutrals. Our measurements show that all measured quantities, including winds, densities, and temperatures, reveal signatures of both waves and turbulence. We show observations of gravity wave saturation and breakdown together with simultaneous measurements of generated turbulence. Atomic oxygen inside turbulence layers shows two different spectral behaviors, which might imply a change in its diffusion properties

Combination of Lidar and Model Data for Studying Deep Gravity Wave Propagation

The paper presents a feasible method to complement ground-based middle atmospheric Rayleigh lidar temperature observations with numerical simulations in the lower stratosphere and troposphere to study gravity waves. Validated mesoscale numerical simulations are utilized to complement the temperature below 30-km altitude. For this purpose, high-temporal-resolution output of the numerical results was interpolated on the position of the lidar in the lee of the Scandinavian mountain range. Two wintertime cases of orographically induced gravity waves are analyzed. Wave parameters are derived using a wavelet analysis of the combined dataset throughout the entire altitude range from the troposphere to the mesosphere. Although similar in the tropospheric forcings, both cases differ in vertical propagation. The combined dataset reveals stratospheric wave breaking for one case, whereas the mountain waves in the other case could propagate up to about 40-km altitude. The lidar observations reveal an interaction of the vertically propagating gravity waves with the stratopause, leading to a stratopause descent in both cases

Atomic oxygen number densities in the mesosphere–lower thermosphere region measured by solid electrolyte sensors on WADIS-2

Absolute profiles of atomic oxygen number densities with high vertical resolution have been determined in the mesosphere–lower thermosphere (MLT) region from in situ measurements by several rocket-borne solid electrolyte sensors. The amperometric sensors were operated in both controlled and uncontrolled modes and with various orientations on the foredeck and aft deck of the payload. Calibration was based on mass spectrometry in a molecular beam containing atomic oxygen produced in a microwave discharge. The sensor signal is proportional to the number flux onto the electrodes, and the mass flow rate in the molecular beam was additionally measured to derive this quantity from the spectrometer reading

Nighttime O(1D) and corresponding Atmospheric Band emission (762 nm) derived from rocket-borne experiment

Based on common volume rocket-borne measurements of temperature, densities of atomic oxygen and neutral air, we derived O(1D) nighttime concentrations and corresponding Atmospheric band emission (762 nm). This is one of the first retrievals of the nighttime O(1D) concentration. Recently, Kalogerakis, Sharma and co-workers have suggested a new production path of O(1D) based on the reaction of vibrationally excited OH and O. We calculate Atmospheric band volume emission related to the population of O2(b1Σg+) from O(1D) and compare with total Atmospheric band emissions observed during the same rocket launch

Atmospheric band fitting coefficients derived from a self-consistent rocket-borne experiment

Based on self-consistent rocket-borne measurements of temperature, the densities of atomic oxygen and neutral air, and the volume emission of the atmospheric band (762 nm), we examined the one-step and two-step excitation mechanism of O2 for nighttime conditions. Following McDade et al. (1986), we derived the empirical Fitting coefficients, which parameterize the atmospheric band emission O2. This allows us to derive the atomic oxygen concentration from nighttime observations of atmospheric band emission O2. The derived empirical parameters can also be utilized for atmospheric band modeling. Additionally, we derived the fit function and corresponding coefficients for the combined (one- and two-step) mechanism