Analysis of wave fields by Fourier integral operators and their application for radio occultations

Горбунов, М. Е.; Lauritsen, K. B.

doi:10.1029/2003rs002971

Cited by 112 publications

(166 citation statements)

References 24 publications

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“…These methods allow enhancing the retrieval accuracy and resolution (e.g., Gorbunov and Gurvich, 1998a, b;Gorbunov, 2002a;Gorbunov and Lauritsen, 2004) as well as obtaining new information on the structure of the atmosphere (Pavelyev et al, 2012, 2015, andreferences therein). In particular, Pavelyev et al (2015) demonstrated the potential of the locality principle for the localization and estimation of the parameters of layered structures as well as the separation of the contributions of layered structures and turbulence in RO signals.…”

Section: Discussionmentioning

confidence: 99%

“…We position the phase screen in the plane crossing the Earth's center and perpendicular to the incident rays. The occultation geometry has been discussed in many papers: Vorob'ev and Krasil'nikova (1994), Ware et al (1996), Gorbunov and Lauritsen (2004), Cornman et al (2004), and Pavelyev et al (2012), as well as further references therein. The phase screen has been discussed in Hubbard et al (1978), Woo et al (1980), Gurvich (1984), and Gurvich and Brekhovskikh (2001).…”

Section: -D Models Of Refractivity Fluctuation Spectramentioning

confidence: 99%

“…In processing RO observations, neutral atmospheric meteorological variables are retrieved from amplitude and phase measurements (Gorbunov and Lauritsen, 2004;Gorbunov et al, 2005;Gorbunov and Lauritsen, 2006), while the ionospheric contribution is removed by using the double-frequency linear combination at the same ray impact height (Vorob'ev and Krasil'nikova, 1994;Gorbunov, 2002b). The impressive success of the GPS/MET experiment stimulated further development of RO satellites and constellations, including CHAMP and COSMIC experiments.…”

Section: Introductionmentioning

confidence: 99%

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

2018

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Abstract. We discuss the relationships that link the observed fluctuation spectra of the amplitude and phase of signals used for the radio occultation sounding of the Earth's atmosphere, with the spectra of atmospheric inhomogeneities. Our analysis employs the approximation of the phase screen and of weak fluctuations. We make our estimates for the following characteristic inhomogeneity types: (1) the isotropic Kolmogorov turbulence and (2) the anisotropic saturated internal gravity waves. We obtain the expressions for the variances of the amplitude and phase fluctuations of radio occultation signals as well as their estimates for the typical parameters of inhomogeneity models. From the GPS/MET observations, we evaluate the spectra of the amplitude and phase fluctuations in the altitude interval from 4 to 25 km in the middle and polar latitudes. As indicated by theoretical and experimental estimates, the main contribution into the radio signal fluctuations comes from the internal gravity waves. The influence of the Kolmogorov turbulence is negligible. We derive simple relationships that link the parameters of internal gravity waves and the statistical characteristics of the radio signal fluctuations. These results may serve as the basis for the global monitoring of the wave activity in the stratosphere and upper troposphere.

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Section: Discussionmentioning

confidence: 99%

Section: -D Models Of Refractivity Fluctuation Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2018

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“…For basic understanding of the retrieval process, we here briefly (Gorbunov, 2002), using a two-parameter fit of background (MSISE-90) to data >40 km combined with a global background search (Lauritsen et al, 2011); background error fixed at 50 %. Optimization after Sokolovskiy and Hunt (1996) with MSISE-90 (>40 km), obs.…”

Section: Ro Data and Processing Descriptionmentioning

confidence: 99%

Quantification of structural uncertainty in climate data records from GPS radio occultation

et al. 2013

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Global Positioning System (GPS) radio occultation (RO) has provided continuous observations of the Earth's atmosphere since 2001 with global coverage, all-weather capability, and high accuracy and vertical resolution in the upper troposphere and lower stratosphere (UTLS). Precise time measurements enable long-term stability but careful processing is needed. Here we provide climate-oriented atmospheric scientists with multicenter-based results on the long-term stability of RO climatological fields for trend studies. We quantify the structural uncertainty of atmospheric trends estimated from the RO record, which arises from current processing schemes of six international RO processing centers, DMI Copenhagen, EUM Darmstadt, GFZ Potsdam, JPL Pasadena, UCAR Boulder, and WEGC Graz. Monthly-mean zonal-mean fields of bending angle, refractivity, dry pressure, dry geopotential height, and dry temperature from the CHAMP mission are compared for September 2001 to September 2008. We find that structural uncertainty is lowest in the tropics and mid-latitudes (50° S to 50° N) from 8 km to 25 km for all inspected RO variables. In this region, the structural uncertainty in trends over 7 yr is <0.03% for bending angle, refractivity, and pressure, <3 m for geopotential height of pressure levels, and <0.06 K for temperature; low enough for detecting a climate change signal within about a decade. Larger structural uncertainty above about 25 km and at high latitudes is attributable to differences in the processing schemes, which undergo continuous improvements. Though current use of RO for reliable climate trend assessment is bound to 50° S to 50° N, our results show that quality, consistency, and reproducibility are favorable in the UTLS for the establishment of a climate benchmark record

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“…Due to strong refractivity gradients and multipath effects, the GO bending angle retrieval can be inadequate in the troposphere, and therefore wave-optics (WO) algorithms are applied to reconstruct the geometric optical ray structure of the wave field (e.g., Gorbunov, 2002a;Gorbunov and Lauritsen, 2004).…”

Section: Wo Bending Angle Retrievalmentioning

confidence: 99%

Integrating uncertainty propagation in GNSS radio occultation retrieval: from excess phase to atmospheric bending angle profiles

Schwarz¹,

Kirchengast²,

Schwaerz³

2017

Preprint

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Abstract. Global Navigation Satellite System (GNSS) radio occultation (RO) observations are highly accurate, long-term stable data sets, and are globally available as a continuous record since 2001. Essential climate variables for the thermodynamic state of the free atmosphere, such as pressure, temperature and tropospheric water vapor profiles (involving background information), can be derived from these records, which therefore have the potential to serve as climate benchmark data. However, to exploit this potential, atmospheric profile retrievals need to be very accurate and the remaining uncertainties quantified and 5 traced throughout the retrieval chain from raw observations to essential climate variables. The new Reference Occultation Processing System (rOPS) at the Wegener Center aims to deliver such an accurate RO retrieval chain with integrated uncertainty propagation. Here we introduce and demonstrate the algorithms implemented in the rOPS for uncertainty propagation from excess phase to atmospheric bending angle profiles, for estimated systematic and random uncertainties, including vertical error correlations and resolution estimates. We estimated systematic uncertainty profiles with the same operators as used for the ba-10 sic state profiles retrieval. The random uncertainty is traced through covariance propagation and validated using Monte-Carlo ensemble methods. The algorithm performance is demonstrated using test-day ensembles of simulated data as well as real RO event data from the satellite missions CHAMP and COSMIC. The results of the Monte-Carlo validation show that our covariance propagation delivers correct uncertainty quantification from excess phase to bending angle profiles. The results from the real RO event ensembles demonstrate that the new uncertainty estimation chain performs robustly. Together with the other 15 parts of the rOPS processing chain this part is thus ready to provide integrated uncertainty propagation through the whole RO retrieval chain for the benefit of climate monitoring and other applications.

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Analysis of wave fields by Fourier integral operators and their application for radio occultations

Cited by 112 publications

References 24 publications

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

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

Quantification of structural uncertainty in climate data records from GPS radio occultation

Integrating uncertainty propagation in GNSS radio occultation retrieval: from excess phase to atmospheric bending angle profiles

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