Determination of the intrinsic frequency and other wave parameters from a single vertical temperature or density profile measurement

Abstract

[1] In order to examine internal gravity wave characteristics we have analyzed small-scale fluctuations of normalized temperature in the Earth's stratosphere using radio occultation data. An analysis to identify the observed fluctuations as wave-induced, assuming gravity wave shear saturation, is proposed. This technique is based upon a comparison of the experimental and theoretical values of the relative amplitude threshold which is defined as the wave amplitude required for shear instability. The theoretical amplitude threshold, assuming a minimum Richardson number of 1/4, is a function of f/w, where f and w are inertial and intrinsic frequencies, correspondingly. The theoretical threshold values are confined from zero to unity. In the case when this criterion is satisfied for its experimental counterpart and the analyzed fluctuations are positively identified as wave-induced, then the intrinsic frequency of the monochromatic gravity wave can be determined from only a single vertical temperature (or density) profile measurement. The results of the determination of the intrinsic frequency and other characteristics of internal gravity waves are presented and discussed.Citation: Gubenko, V. N., A. G. Pavelyev, and V. E. Andreev (2008), Determination of the intrinsic frequency and other wave parameters from a single vertical temperature or density profile measurement,

Fluctuations of radio occultation signals in sounding the Earth's atmosphere

“…Wang and Alexander (2010) and McDonald (2012), analyzing collocated temperature profiles from COSMIC observations, showed that in the stratosphere, the most large-scale dominant temperature perturbations are of wave nature. Gubenko et al (2008Gubenko et al ( , 2011 developed a method for the determination of the basic characteristics of dominant IGWs, including their intrinsic frequency and phase velocities from vertical profiles of temperature. The method was validated on high-resolution radiosonde observations of temperature and wind and then applied to the analysis of IGWs based on temperature profiles retrieved from RO observations in COSMIC and CHAMP missions.…”

“…The stability of GPS signals, complemented with its global coverage and high vertical resolution, draws the attention of researchers to the study of inhomogeneities in atmospheric refractivity in addition to the retrieval of mean profiles (Belloul and Hauchecorne, 1997;Gurvich et al, 2000;Tsuda et al, 2000;Wang and Alexander, 2010;Cornman et al, 2004Cornman et al, , 2012Shume and Ao, 2016;Gubenko et al, 2008Gubenko et al, , 2011. Occultation-based methods of sounding atmospheric inhomogeneities have a long and successful history.…”

Radio Wave Propagation Phenomena from GPS Occultation Data Analysis

“…Strong amplitude and phase frequency dependent variations in the RO signals are often surprisingly observed within the altitudes of the RO ray perigee () hT between 30 and 80 km above the main part of the neutral atmosphere and below the Elayer of the ionosphere. The effects of strong phase and amplitude variations of the RO signals at a low altitude provide a good source of information for the remote sensing of the atmosphere and ionosphere including detecting and studying the internal gravity waves propagating in the atmosphere and ionosphere [54]. Accurate knowledge of spatial location, height and inclination of the sporadic E-layers is important for the estimation of the offequatorial height-integrated conductivity [44,45].…”

“…The radio occultation (RO) method employs the highly-stable radio waves transmitted at two GPS frequencies 1 f  1575.42 MHz and 2 f  1227.60 MHz by the GPS satellites and recorded at a GPS receiver onboard low Earth orbiting (LEO) satellite to remote sense the Earth's ionosphere and neutral atmosphere [4,5,10,11,17,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]46,47,[52][53][54][55][56][59][60][61]. When applied to ionospheric investigations the RO method may be considered as a global tool and can be compared with the global Earth-and space-based radio tomography [42,43].…”

Analysis of internal gravity waves with GPS RO density profiles

“…In this section, we present a comparison between the normalized density perturbations resulting from the polynomial fits of N 2 (z) and the fit of the temperature profile with a cubic polynomial as used, for example, by Gubenko et al (2008). We have computed the mean vertical wave-number power spectrum for the sample of 60 profiles.…”