Variable anisotropy of small-scale stratospheric irregularities retrieved from stellar scintillation measurements by GOMOS/Envisat

Kan, V.; Sofieva, Viktoria; Dalaudier, Francis

doi:10.5194/amt-7-1861-2014

Cited by 13 publications

(18 citation statements)

References 32 publications

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“…As noted in Sect. 2.1, observations of stellar occultations with grazing geometry (Kan et al, 2014), together with the data about the anisotropy of dominant IGWs (e.g., Ern et al, 2004, the description of CRISTA experiment) and GPS occultations in Wang and Alexander (2010) have revealed that the anisotropy coefficient is not uniform. It increases from about 10-20 for the IGW breaking scale (10-20 m in the vertical direction) to the saturation value of several hundred for dominant IGWs.…”

Section: Discussionmentioning

confidence: 99%

“…We will use a model of the IGW spectrum with a constant anisotropy η = const 1, although the latest studies of stellar scintillations (Kan et al, 2012(Kan et al, , 2014 indicate that the anisotropy increases and saturates with increasing scale; the saturation value being about 100 for vertical scales of about 100 m. We will show that RO signal fluctuations are determined primarily by the Fresnel scale ρ F and the outer scale L. For radio waves with λ = 20 cm at a GPS-LEO path, ρ F equals about 1 km, while the vertical outer scale L W is several kilometers. For inhomogeneities with scales ≥ 1 km, the anisotropy η significantly exceeds its critical value η cr = √ R e /H 0 ≈ 30, where R e is the Earth's radius, and H 0 = 6-8 km is the atmospheric-scale height (Gurvich and Brekhovskikh, 2001).…”

Section: -D Models Of Refractivity Fluctuation Spectramentioning

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%

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

2018

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“…It turned out that this correction is almost perfect when the star sets along the orbital plane but does not work properly for very oblique occultations due to the presence of residual scintillation caused by horizontal turbulent structures. Photometer data have also been used to investigate atmospheric turbulence (Kan et al, 2014) and to derive high-resolution temperature profiles (Dalaudier et al, 2006) from the time delay induced by chromatic refraction. Here we focus on the low-frequency part of the refractive effects by showing how to apply the ARID algorithm to the photometer data for the retrieval of refractive angle profiles.…”

Section: Gomos Instrumentsmentioning

confidence: 99%

“…The subject of stellar scintillations is very broad and directly related to the study of atmospheric turbulence (Wheelon, 2001(Wheelon, , 2003. Star occultations have been the main technique used by the GOMOS instrument and allowed the reconstruction of atmospheric irregularities in air density and temperature profiles (see Kan et al (2014) and reference therein).…”

Section: Introductionmentioning

confidence: 99%

Retrieval of vertical profiles of atmospheric refraction angles by inversion of optical dilution measurements

Fussen¹,

Tétard²,

Dekemper³

et al. 2015

Atmos. Meas. Tech.

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Abstract. In this paper, we consider occultations of celestial bodies through the atmospheric limb from low Earth orbit satellites and we show how the usual change of tangent altitude associated with atmospheric refraction is inseparably connected to a variation of the observed apparent intensity, for extended and pointlike sources. We demonstrate, in the regime of weak refraction angles, that atmospheric optical dilution and image deformation are strictly concomitant. The approach leads to the integration of a simple differential equation related to the observed transmittance in the absence of other absorbing molecules along the optical path. The algorithm does not rely on the absolute knowledge of the radiometer pointing angle that is related to the accurate knowledge of the satellite attitude. We successfully applied the proposed method to the measurements performed by two past occultation experiments: GOMOS for stellar and ORA for solar occultations. The developed algorithm (named ARID) will be applied to the imaging of solar occultations in a forthcoming pico-satellite mission.

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“…We will use a model of the IGW spectrum with a constant anisotropy η = const ≫ 1, although the latest studies of stellar scintillations (Kan et al, 2012(Kan et al, , 2014 indicate that the anisotropy increases and saturates with increasing scale; the saturation value being about 100 for vertical scales of about 100 m.…”

mentioning

confidence: 99%

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

Kan¹,

Горбунов²,

Sofieva³

2017

Preprint

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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 5 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 10 global monitoring of the wave activity in the stratosphere and upper troposphere.

show abstract

Variable anisotropy of small-scale stratospheric irregularities retrieved from stellar scintillation measurements by GOMOS/Envisat

Cited by 13 publications

References 32 publications

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

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

Retrieval of vertical profiles of atmospheric refraction angles by inversion of optical dilution measurements

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

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