{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T06:27:37Z","timestamp":1770964057488,"version":"3.50.1"},"reference-count":100,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2024,1,5]],"date-time":"2024-01-05T00:00:00Z","timestamp":1704412800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Internal gravity waves (IGWs) in the middle atmosphere are the main source of mesoscale fluctuations of wind and temperature. The parameterization of IGWs and study of their climatology is necessary for the development of global atmospheric circulation models. In this review, we focus on the application of Radio Occultation (RO) observations for the retrieval of IGW parameters. (1) The simplest approach employs the retrieved temperature profiles. It is based on the fact that IGWs are highly anisotropic structures and can be accurately retrieved by RO. The basic assumption is that all the temperature fluctuations are caused by IGWs. The smoothed background temperature profile defines the the Brunt\u2013V\u00e4is\u00e4l\u00e4 frequency, which, together with the temperature fluctuations, defines the IGW specific potential energy. Many studies have derived the distribution and climatology of potential energy, which is one of the most important characteristics of IGWs. (2) More detailed analysis of the temperature profiles is based on the derivation of the temperature fluctuation spectra. For saturated IGWs, the spectra must obey the power law with an exponent of \u22123. Such spectra are obtained by using Wave Optical (WO) processing. (3) More advanced analysis employs space\u2013frequency analysis. It is based on phase-sensitive techniques like cross S- or wavelet transforms in order to identify propagating IGWs. (4) Another direction is the IGW parameter estimate from separate temperature profiles applying the stability condition in terms of the Richardson number. In this framework, a necessary condition is formulated that defines whether or not the temperature fluctuations can be related to IGW events. The temperature profile retrieval involves integral transforms and filtering that constitute the observation filter. (5) A simpler filter is implemented by the analysis of the RO amplitude fluctuation spectra, based on the diffraction theory in the framework of the phase screen and weak fluctuation approximations. The two spectral parameters, the external scale and the structural characteristic, define the specific potential energy. This approach allows the derivation of the spacial and seasonal distributions of IGW activity. We conclude that the success of IGW study by RO is stimulated by a large number of RO observations and advanced techniques based on Fourier and space\u2013time analysis, physical equations describing IGWs, and diffraction theory.<\/jats:p>","DOI":"10.3390\/rs16020221","type":"journal-article","created":{"date-parts":[[2024,1,5]],"date-time":"2024-01-05T10:06:43Z","timestamp":1704449203000},"page":"221","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["The Study of Internal Gravity Waves in the Earth\u2019s Atmosphere by Radio Occultations: A Review"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2738-0547","authenticated-orcid":false,"given":"Michael","family":"Gorbunov","sequence":"first","affiliation":[{"name":"A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, Pyzhevsky Per. 3, Moscow 119017, Russia"},{"name":"Hydrometcenter of Russia, Bolshoy Predtechensky Per. 13, Building 1, Moscow 123376, Russia"}]},{"given":"Valery","family":"Kan","sequence":"additional","affiliation":[{"name":"A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, Pyzhevsky Per. 3, Moscow 119017, Russia"}]}],"member":"1968","published-online":{"date-parts":[[2024,1,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1003","DOI":"10.1029\/2001RG000106","article-title":"Gravity waves dynamics and effects in the middle atmosphere","volume":"41","author":"Fritts","year":"2003","journal-title":"Rev. Geophys."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"17265","DOI":"10.1029\/91JD01944","article-title":"Spectral analysis of temperature and Brunt-Vaisala frequency fluctuations observed by radiosondes","volume":"96","author":"Tsuda","year":"1991","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"17971","DOI":"10.1029\/2000JD900196","article-title":"Gravity waves in the tropical lower stratosphere: An observational study of seasonal and interannual variability","volume":"105","author":"Vincent","year":"2000","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1175\/JAS-3364.1","article-title":"Spatial and Temporal Variations of Gravity Wave Parameters. Part I: Intrinsic Frequency, Wavelength, and Vertical Propagation Direction","volume":"62","author":"Wang","year":"2005","journal-title":"J. Atmos. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1175\/1520-0469(1990)047<0051:SOVFIT>2.0.CO;2","article-title":"Studies of velocity fluctuations in the lower atmosphere using the MU radar. II. Momentum fluxes and energy densities","volume":"47","author":"Fritts","year":"1990","journal-title":"J. Atmos. Sci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"23057","DOI":"10.1029\/94JD01717","article-title":"Seasonal variation of gravity wave activity in the lower atmosphere observed with the MU radar","volume":"99","author":"Murayama","year":"1994","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"9441","DOI":"10.1029\/95JD03835","article-title":"Stratospheric horizontal wavenumber spectra of winds, potential temperature and atmospheric tracers observed by high-altitude aircraft","volume":"101","author":"Bacmeister","year":"1996","journal-title":"J. Geophys. Res."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"5697","DOI":"10.1029\/98JD01825","article-title":"Horizontal wavenumber spectra of winds, temperature, and trace gases during the Pacific Exploratory Missions: 1. Climatology","volume":"104","author":"Cho","year":"1999","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"D15S18","DOI":"10.1029\/2007JD008807","article-title":"Global estimates of gravity wave momentum flux from High Resolution Dynamics Limb Sounder observations","volume":"113","author":"Alexander","year":"2008","journal-title":"J. Geophys. Res."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"D20103","DOI":"10.1029\/2004JD004752","article-title":"Absolute values of gravity wave momentum flux derived from satellite data","volume":"109","author":"Ern","year":"2004","journal-title":"J. Geophys. Res."},{"key":"ref_11","first-page":"300","article-title":"Structure of air density irregularities in the stratosphere from spacecraft observations of stellar scintillation: 1. Three-dimensional spectrum model and recovery of its parameters","volume":"39","author":"Gurvich","year":"2003","journal-title":"Izv. Atm. Ocean. Phys."},{"key":"ref_12","first-page":"311","article-title":"Structure of air density irregularities in the stratosphere from spacecraft observations of stellar scintillation: 2. Characteristic scales, structure characteristics, and kinetic energy dissipation","volume":"39","author":"Gurvich","year":"2003","journal-title":"Izv. Atm. Ocean. Phys."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"D12113","DOI":"10.1029\/2006JD007483","article-title":"Reconstruction of internal gravity wave and turbulence parameters in the stratosphere using GOMOS scintillation measurements","volume":"112","author":"Sofieva","year":"2007","journal-title":"J. Geophys. Res."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"L03812","DOI":"10.1029\/2006GL028132","article-title":"Global analysis of scintillation variance: Indication of gravity wave breaking in the polar winter upper stratosphere","volume":"34","author":"Sofieva","year":"2007","journal-title":"Geophys. Res. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"29849","DOI":"10.1029\/97JD02400","article-title":"Analysis and validation of GPS\/MET data in the neutral atmosphere","volume":"102","author":"Rocken","year":"1997","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1","DOI":"10.3319\/TAO.2000.11.1.1(COSMIC)","article-title":"A History of GPS Sounding","volume":"11","author":"Yunck","year":"2000","journal-title":"Terr. Atmos. Ocean. Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"3263","DOI":"10.1029\/2001GL013117","article-title":"Atmosphere sounding by GPS radio occultation: First results from CHAMP","volume":"28","author":"Wickert","year":"2001","journal-title":"Geophys. Res. Lett."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1007\/s10291-009-0142-3","article-title":"Metop-GRAS in-orbit instrument performance","volume":"14","author":"Bonnedal","year":"2010","journal-title":"GPS Solut."},{"key":"ref_19","unstructured":"Chu, C.H., Fong, C.J., Xia-Serafino, W., Shiau, A., Taylor, M., Chang, M.S., Chen, W.J., Liu, T.Y., Liu, N.C., and Martins, B. (2018). An Era of Constellation Observation-FORMOSAT-3\/COSMIC and FORMOSAT-7\/COSMIC-2. J. Aeronaut. Astrnaut. Aviat."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1109\/MAES.2019.2924133","article-title":"Toward the Most Accurate Thermometer in Space: FORMOSAT-7\/COSMIC-2 Constellation","volume":"34","author":"Fong","year":"2019","journal-title":"IEEE Aerosp. Electron. Syst. Mag."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Ho, S.P., Zhou, X., Shao, X., Zhang, B., Adhikari, L., Kireev, S., He, Y., Yoe, J.G., Xia-Serafino, W., and Lynch, E. (2020). Initial Assessment of the COSMIC-2\/FORMOSAT-7 Neutral Atmosphere Data Quality in NESDIS\/STAR Using In Situ and Satellite Data. Remote Sens., 12.","DOI":"10.3390\/rs12244099"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Qiu, C., Wang, X., Zhou, K., Zhang, J., Chen, Y., Li, H., Liu, D., and Yuan, H. (2023). Comparative Assessment of Spire and COSMIC-2 Radio Occultation Data Quality. Remote Sens., 15.","DOI":"10.3390\/rs15215082"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1029\/2000RS002592","article-title":"Canonical transform method for processing radio occultation data in the lower troposphere","volume":"37","author":"Gorbunov","year":"2002","journal-title":"Radio Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"RS3009","DOI":"10.1029\/2003RS002899","article-title":"Geometrical optics phase matching of radio occultation signals","volume":"39","author":"Jensen","year":"2004","journal-title":"Radio Sci."},{"key":"ref_25","first-page":"RS4010","article-title":"Analysis of wave fields by Fourier integral operators and its application for radio occultations","volume":"39","author":"Gorbunov","year":"2004","journal-title":"Radio Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"7257","DOI":"10.1029\/1999JD901005","article-title":"A global morphology of gravity wave activity in the stratosphere revealed by the GPS occultation data (GPS\/MET)","volume":"105","author":"Tsuda","year":"2000","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2815","DOI":"10.1029\/2001GL013076","article-title":"Gravity waves and ionospheric irregularities over tropical convection zones observed by GPS\/MET radio occultation","volume":"28","author":"Hocke","year":"2001","journal-title":"Geophys. Res. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1610","DOI":"10.1175\/1520-0469(2004)061<1610:GASVOS>2.0.CO;2","article-title":"Global and Seasonal Variations of Stratospheric Gravity Wave Activity Deduced from the CHAMP\/GPS Satellite","volume":"61","author":"Ratnam","year":"2004","journal-title":"J. Atmospheric Sci."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"D04107","DOI":"10.1029\/2007JD008938","article-title":"Characteristics of atmospheric gravity wave activity in the polar regions revealed by GPS radio occultation data with CHAMP","volume":"113","author":"Hei","year":"2008","journal-title":"J. Geophys. Res."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1251","DOI":"10.1002\/2014GL062891","article-title":"Seasonal variation of gravity wave activity at midlatitudes from 7years of COSMIC GPS and Rayleigh lidar temperature observations","volume":"42","author":"Khaykin","year":"2015","journal-title":"Geophys. Res. Lett."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"543","DOI":"10.1016\/j.asr.2015.10.047","article-title":"An improvement of the sensitivity of GPS radio occultation data to detect gravity waves through observational and modeling factors","volume":"57","author":"Alexander","year":"2016","journal-title":"Adv. Space Res."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1031","DOI":"10.5194\/amt-11-1031-2018","article-title":"An intercomparison of stratospheric gravity wave potential energy densities from METOP GPS radio occultation measurements and ECMWF model data","volume":"11","author":"Rapp","year":"2018","journal-title":"Atmos. Meas. Tech."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Yu, D., Xu, X., Luo, J., and Li, J. (2019). On the Relationship between Gravity Waves and Tropopause Height and Temperature over the Globe Revealed by COSMIC Radio Occultation Measurements. Atmosphere, 10.","DOI":"10.3390\/atmos10020075"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Luo, J., Hou, J., and Xu, X. (2021). Variations in Stratospheric Gravity Waves Derived from Temperature Observations of Multi-GNSS Radio Occultation Missions. Remote Sens., 13.","DOI":"10.3390\/rs13234835"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Chen, Z., Gao, Y., Li, L., He, X., Yang, W., Luo, H., Gong, X., and Lv, K. (2022). An Investigation of the Lower Stratospheric Gravity Wave Activity in Tibetan Plateau Based on Multi-GNSS RO Dry Temperature Observations. Remote Sens., 14.","DOI":"10.3390\/rs14225671"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"682","DOI":"10.1029\/2018GL079142","article-title":"Large Midlatitude Stratospheric Temperature Variability Caused by Inertial Instability: A Potential Source of Bias for Gravity Wave Climatologies","volume":"45","author":"Rapp","year":"2018","journal-title":"Geophys. Res. Lett."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1740","DOI":"10.1029\/2018GL081142","article-title":"Beware of Inertial Instability Masquerading as Gravity Waves in Stratospheric Temperature Perturbations","volume":"46","author":"Harvey","year":"2019","journal-title":"Geophys. Res. Lett."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"495","DOI":"10.1175\/1520-0426(2000)017<0495:GWSFGM>2.0.CO;2","article-title":"Gravity Wave Spectra from GPS\/MET Occultation Observations","volume":"17","author":"Steiner","year":"2000","journal-title":"J. Atmos. Oceanic Technol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"925","DOI":"10.2151\/jmsj.80.925","article-title":"Vertical Wave Number Spectrum of Temperature Fluctuations in the Stratosphere using GPS Occultation Data","volume":"80","author":"Tsuda","year":"2002","journal-title":"J. Meteor. Soc. Japan. Ser. II"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1627","DOI":"10.5194\/amt-4-1627-2011","article-title":"Analysis of vertical wave number spectrum of atmospheric gravity waves in the stratosphere using COSMIC GPS radio occultation data","volume":"4","author":"Tsuda","year":"2011","journal-title":"Atmos. Meas. Tech."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"4123","DOI":"10.5194\/amt-7-4123-2014","article-title":"Analysis of internal gravity waves with GPS RO density profiles","volume":"7","author":"Foelsche","year":"2014","journal-title":"Atmos. Meas. Tech."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"515","DOI":"10.5194\/amt-11-515-2018","article-title":"Revisiting internal gravity waves analysis using GPS RO density profiles: Comparison with temperature profiles and application for wave field stability study","volume":"11","author":"Pisoft","year":"2018","journal-title":"Atmos. Meas. Tech."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"D21122","DOI":"10.1029\/2010JD013860","article-title":"Global estimates of gravity wave parameters from GPS radio occultation temperature data","volume":"115","author":"Wang","year":"2010","journal-title":"J. Geophys. Res."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"D15406","DOI":"10.1029\/2011JD016715","article-title":"Gravity wave occurrence statistics derived from paired COSMIC\/FORMOSAT3 observations","volume":"117","author":"McDonald","year":"2012","journal-title":"J. Geophys. Res."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"3169","DOI":"10.5194\/amt-6-3169-2013","article-title":"On the determination of gravity wave momentum flux from GPS radio occultation data","volume":"6","author":"Faber","year":"2013","journal-title":"Atmos. Meas. Tech."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"7797","DOI":"10.5194\/acp-15-7797-2015","article-title":"The southern stratospheric gravity wave hot spot: Individual waves and their momentum fluxes measured by COSMIC GPS-RO","volume":"15","author":"Hindley","year":"2015","journal-title":"Atmos. Chem. Phys."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"3523","DOI":"10.5194\/amt-11-3523-2018","article-title":"Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events \u2013 a case study","volume":"11","author":"Hierro","year":"2018","journal-title":"Atmos. Meas. Tech."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"222","DOI":"10.1002\/2017EA000342","article-title":"A Method to Determine Gravity Wave Net Momentum Flux, Propagation Direction, and \u201cReal\u201d Wavelengths: A GPS Radio Occultations Soundings Case Study","volume":"5","author":"Alexander","year":"2018","journal-title":"Earth Space Sci."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"4443","DOI":"10.1002\/2015JD024135","article-title":"Stratospheric gravity wave momentum flux from radio occultations","volume":"121","author":"Schmidt","year":"2016","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"757","DOI":"10.1007\/s00704-014-1146-7","article-title":"Climatology of stratospheric gravity waves and their interaction with zonal mean wind over the tropics using GPS RO and ground-based measurements in the two phases of QBO","volume":"119","author":"Nath","year":"2014","journal-title":"Theor. Appl. Climatol."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"D08109","DOI":"10.1029\/2007JD008920","article-title":"Determination of the intrinsic frequency and other wave parameters from a single vertical temperature or density profile measurement","volume":"113","author":"Gubenko","year":"2008","journal-title":"J. Geophys. Res."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1134\/S0010952512010029","article-title":"A method for determination of internal gravity wave parameters from a vertical temperature or density profile measurement in the Earth\u2019s atmosphere","volume":"50","author":"Gubenko","year":"2012","journal-title":"Cosmic Res."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"435","DOI":"10.1134\/S0001433820050072","article-title":"The Reconstruction of the Parameters of Internal Gravity Waves in the Atmosphere from Amplitude Fluctuations in the Radio Occultation Experiment","volume":"56","author":"Kan","year":"2020","journal-title":"Izv. Atm. Ocean. Phys."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"564","DOI":"10.1134\/S0001433820060055","article-title":"Latitudinal Distribution of the Parameters of Internal Gravity Waves in the Atmosphere Derived from Amplitude Fluctuations of Radio Occultation Signals","volume":"56","author":"Kan","year":"2020","journal-title":"Izv. Atm. Ocean. Phys."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"012008","DOI":"10.1088\/1755-1315\/1040\/1\/012008","article-title":"The parameters of internal gravity waves in the atmosphere from the amplitude fluctuations of radio occultation signals","volume":"1040","author":"Kan","year":"2022","journal-title":"IOP Conf. Ser. Earth Environ. Sci."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"2742","DOI":"10.1029\/JD091iD02p02742","article-title":"Saturation and the \u201cuniversal\u201d spectrum for vertical profiles of horizontal scalar winds in the atmosphere","volume":"91","author":"Dewan","year":"1986","journal-title":"J. Geophys. Res."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1007\/BF00874464","article-title":"A review of gravity wave saturation processes, effects, and variability in the middle atmosphere","volume":"130","author":"Fritts","year":"1989","journal-title":"Pure Appl. Geophys."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1080\/13616670109409781","article-title":"Study of the turbulence and inner waves in the stratosphere based on the observations of stellar scintillations from space: A model of scintillation spectra","volume":"11","author":"Gurvich","year":"2001","journal-title":"Waves Random Media"},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"856","DOI":"10.1007\/s00585-997-0856-x","article-title":"A heuristic model of three-dimensional spectra of temperature inhomogeneities in the stably stratified atmosphere","volume":"15","author":"Gurvich","year":"1997","journal-title":"Ann. Geophys."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"2037","DOI":"10.5194\/angeo-26-2037-2008","article-title":"Three-dimensional spectrum of temperature fluctuations in stably stratified atmosphere","volume":"26","author":"Gurvich","year":"2008","journal-title":"Ann. Geophys."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1029\/97RS02762","article-title":"The two-dimensional resolution kernel associated with retrieval of ionospheric and atmospheric refractivity profiles by abelian inversion of radio occultation phase data","volume":"33","author":"Ahmad","year":"1998","journal-title":"Radio Sci."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"1730","DOI":"10.1016\/j.jastp.2005.10.019","article-title":"Tropopause to mesopause gravity waves in August: Measurement and modeling","volume":"68","author":"Preusse","year":"2006","journal-title":"J. Atmos. Sol. Terr. Phys."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"1323","DOI":"10.1029\/RS020i006p01323","article-title":"A model for gravity wave spectra observed by Doppler sounding systems","volume":"20","author":"VanZandt","year":"1985","journal-title":"Radio Sci."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1016\/S1364-6826(97)00056-4","article-title":"Modeling the impact of the Earth\u2019s oblateness on the retrieval of temperature and pressure profiles from limb sounding","volume":"60","author":"Syndergaard","year":"1998","journal-title":"J. Atmos. Sol. Terr. Phys."},{"key":"ref_65","first-page":"602","article-title":"Estimation of the Accuracy of the Atmospheric Refractive Index Recovery from Doppler Shift Measurements at Frequencies Used in the NAVSTAR System","volume":"29","year":"1994","journal-title":"Izv. Atm. Ocean. Phys."},{"key":"ref_66","unstructured":"Gorbunov, M.E., Sokolovskiy, S.V., and Bengtsson, L. (1996). Space Refractive Tomography of the Atmosphere: Modeling of Direct and Inverse Problems, Max-Planck Institute for Meteorology. Report No. 210."},{"key":"ref_67","doi-asserted-by":"crossref","unstructured":"Gorbunov, M., Stefanescu, R., Irisov, V., and Zupanski, D. (2019). Variational Assimilation of Radio Occultation Observations into Numerical Weather Prediction Models: Equations, Strategies, and Algorithms. Remote Sens., 11.","DOI":"10.3390\/rs11242886"},{"key":"ref_68","unstructured":"Jensen, A.S., Benzon, H.H., and Lohmann, M.S. (2002). A New High Resolution Method for Processing Radio Occultation Data, Danish Meteorological Institute. Scientific Report 02-06."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"1040","DOI":"10.1029\/2002RS002763","article-title":"Full spectrum inversion of radio occultation signals","volume":"38","author":"Jensen","year":"2003","journal-title":"Radio Sci."},{"key":"ref_70","unstructured":"Gorbunov, M.E., Gurvich, A.S., and Bengtsson, L. (1996). Advanced Algorithms of Inversion of GPS\/MET Satellite Data and Their Application to Reconstruction of Temperature and Humidity, Max-Planck Institute for Meteorology. Report No. 211."},{"key":"ref_71","unstructured":"Sokolovskiy, S., and Hunt, D. (1996, January 21\u201324). Statistical optimization approach for GPS\/MET data inversions. Proceedings of the URSI GPS\/MET Workshop, Tucson, AZ, USA."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1029\/2000RS002370","article-title":"Ionospheric correction and statistical optimization of radio occultation data","volume":"37","author":"Gorbunov","year":"2002","journal-title":"Radio Sci."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"RS3011","DOI":"10.1029\/2004RS003117","article-title":"Application of dynamical error estimation for statistical optimization of radio occultation bending angles","volume":"40","author":"Lohmann","year":"2005","journal-title":"Radio Sci."},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"1398","DOI":"10.1175\/2009JTECHA1192.1","article-title":"Optimal Noise Filtering for the Ionospheric Correction of GPS Radio Occultation Signals","volume":"26","author":"Sokolovskiy","year":"2009","journal-title":"J. Atmos. Oceanic Technol."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"D10105","DOI":"10.1029\/2005JD006427","article-title":"Radio holographic filtering, error estimation, and quality control of radio occultation data","volume":"111","author":"Gorbunov","year":"2006","journal-title":"J. Geophys. Res."},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"13022","DOI":"10.1002\/2013JD020763","article-title":"A new dynamic approach for statistical optimization of GNSS radio occultation bending angles for optimal climate monitoring utility","volume":"118","author":"Li","year":"2013","journal-title":"J. Geophys. Res."},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"1159","DOI":"10.1029\/90JA02125","article-title":"Extension of MSIS thermosphere model into the middle and lower atmosphere","volume":"96","author":"Hedin","year":"1991","journal-title":"J. Geophys. Res."},{"key":"ref_78","unstructured":"Rycroft, M.J., Keating, G., and Rees, D. (1989). Upper Atmosphere Models and Research: Proceedings of Workshops X, XI and of the Topical Meeting of the COSPAR Interdisciplinary Scientific Commission C (Meeting C1) of the COSPAR Twenty-seventh Plenary Meeting Held in Espoo, Finland, 18\u201329 July 1988, Committee on Space Research Pergamon Press."},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"109","DOI":"10.5194\/amt-8-109-2015","article-title":"Generation of a bending angle radio occultation climatology (BAROCLIM) and its use in radio occultation retrievals","volume":"8","author":"Syndergaard","year":"2015","journal-title":"Atmos. Meas. Tech."},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"622","DOI":"10.1134\/S0001433816060050","article-title":"Statistically average atmospheric bending angle model based on COSMIC experimental data","volume":"52","author":"Gorbunov","year":"2016","journal-title":"Izv. Atm. Ocean. Phys."},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"1819","DOI":"10.1029\/JA073i005p01819","article-title":"On the radio occultation method for studying planetary atmospheres","volume":"73","author":"Phinney","year":"1968","journal-title":"J. Geophys. Res."},{"key":"ref_82","first-page":"401","article-title":"Determining Atmospheric Density from Satellite Phase and Refraction Angle Measurements","volume":"4","author":"Tatarskii","year":"1968","journal-title":"Izv. Atm. Ocean. Phys."},{"key":"ref_83","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1086\/111096","article-title":"The Neutral Atmosphere of Venus as Studied with the Mariner-5 Radio Occultation Experiments","volume":"76","author":"Fjeldbo","year":"1971","journal-title":"Astron. J."},{"key":"ref_84","unstructured":"Gorbunov, M.E., and Sokolovskiy, S.V. (1993). Remote Sensing of Refractivity from Space for Global Observations of Atmospheric Parameters, Max-Planck Institute for Meteorology. Report 119."},{"key":"ref_85","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1175\/1520-0477(1996)077<0019:GSOTAF>2.0.CO;2","article-title":"GPS Sounding of the Atmosphere from Low Earth Orbit: Preliminary Results","volume":"77","author":"Ware","year":"1996","journal-title":"Bull. Amer. Meteor. Soc."},{"key":"ref_86","doi-asserted-by":"crossref","first-page":"21","DOI":"10.3319\/TAO.2000.11.1.21(COSMIC)","article-title":"COSMIC System Description","volume":"11","author":"Rocken","year":"2000","journal-title":"Terr. Atmos. Ocean. Sci."},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"417","DOI":"10.2151\/jmsj.83.417","article-title":"Measurement Noise and Stratospheric Gravity Wave Characteristics Obtained from GPS Occultation Data","volume":"83","author":"Marquardt","year":"2005","journal-title":"J. Meteor. Soc. Japan. Ser. II"},{"key":"ref_88","first-page":"511","article-title":"Background fluctuations measured by the radio sounding of the ionosphere in the GPS-Microlab-1 experiment","volume":"XLII","author":"Kan","year":"1999","journal-title":"Radiophys. Quantum Electron."},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"1086","DOI":"10.1002\/2015RS005730","article-title":"Uncertainty propagation through wave optics retrieval of bending angles from GPS radio occultation: Theory and simulation results","volume":"50","author":"Gorbunov","year":"2015","journal-title":"Radio Sci."},{"key":"ref_90","doi-asserted-by":"crossref","first-page":"998","DOI":"10.1109\/78.492555","article-title":"Localization of the complex spectrum: The S transform","volume":"44","author":"Stockwell","year":"1996","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_91","doi-asserted-by":"crossref","first-page":"941","DOI":"10.1109\/5.30749","article-title":"Time-frequency distributions\u2014A review","volume":"77","author":"Cohen","year":"1989","journal-title":"Proc. IEEE"},{"key":"ref_92","doi-asserted-by":"crossref","first-page":"D03102","DOI":"10.1029\/2004JD005006","article-title":"Kelvin wave variability near the equatorial tropopause observed in GPS radio occultation measurements","volume":"110","author":"Randel","year":"2005","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_93","doi-asserted-by":"crossref","first-page":"D24115","DOI":"10.1029\/2008JD010039","article-title":"Global distribution of atmospheric waves in the equatorial upper troposphere and lower stratosphere: COSMIC observations of wave mean flow interactions","volume":"113","author":"Alexander","year":"2008","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_94","first-page":"149","article-title":"Gravity wave and equatorial wave morphology of the stratosphere derived from long-term rocket soundings","volume":"121","author":"Eckermann","year":"1995","journal-title":"Quart. J. Roy. Meteor. Soc."},{"key":"ref_95","doi-asserted-by":"crossref","first-page":"1247","DOI":"10.1029\/RS020i006p01247","article-title":"Convective and dynamical instabilities due to gravity wave motions in the lower and middle atmosphere: Theory and observations","volume":"20","author":"Fritts","year":"1985","journal-title":"Radio Sci."},{"key":"ref_96","doi-asserted-by":"crossref","first-page":"2713","DOI":"10.5194\/amt-5-2713-2012","article-title":"Anisotropy of small-scale stratospheric irregularities retrieved from scintillations of a double star \u03b1-cru observed by GOMOS\/ENVISAT","volume":"5","author":"Kan","year":"2012","journal-title":"Atmos. Meas. Tech."},{"key":"ref_97","doi-asserted-by":"crossref","first-page":"1861","DOI":"10.5194\/amt-7-1861-2014","article-title":"Variable anisotropy of small-scale stratospheric irregularities retrieved from stellar scintillation measurements by GOMOS\/ENVISAT","volume":"7","author":"Kan","year":"2014","journal-title":"Atmos. Meas. Tech."},{"key":"ref_98","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1186\/s40623-022-01667-6","article-title":"Performance assessment of radio occultation data from GeoOptics by comparing with COSMIC data","volume":"74","author":"Chang","year":"2022","journal-title":"Earth Planets Space"},{"key":"ref_99","unstructured":"Kursinski, E.R. (2019, January 19\u201325). Weather & Space Weather RO Data from PlanetiQ Commercial GNSS RO. Proceedings of the Joint 6th ROM SAF Data User Workshop and 7th IROWG Workshop, Konventum, Elsinore, Denmark."},{"key":"ref_100","doi-asserted-by":"crossref","first-page":"13819","DOI":"10.1029\/98JD00806","article-title":"Microlab-1 experiment: Multipath effects in the lower troposphere","volume":"103","author":"Gorbunov","year":"1998","journal-title":"J. Geophys. Res."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/16\/2\/221\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T13:40:59Z","timestamp":1760103659000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/16\/2\/221"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,1,5]]},"references-count":100,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2024,1]]}},"alternative-id":["rs16020221"],"URL":"https:\/\/doi.org\/10.3390\/rs16020221","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,1,5]]}}}