Multi-scale measurements of mesospheric aerosols and electrons during the MAXIDUSTY campaign
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Abstract. We present in situ measurements of small-scale fluctuations in aerosol populations as recorded through a mesospheric cloud system from the Faraday cups DUSTY and MUDD during on the MAXIDUSTY-1 and 1B sounding rocket payloads launched in the summer of 2016. Two mechanically identical DUSTY probes mounted with an inter-spacing of ∼10 cm recorded very different currents, with strong spin modulation, in certain regions of the cloud system. A comparison to auxiliary measurement show similar tendencies in the MUDD data. Fluctuations in the electron density are found to be generally anti-correlated to the negative aerosol charge density on all length scales; however, in certain smaller regions the correlation turns positive. We have also compared the spectral properties of the dust fluctuations, as extracted by wavelet analysis, to polar mesospheric summer echo (PMSE) strength. In this analysis, we find a relatively good agreement between the power spectral density (PSD) at the radar Bragg scale inside the cloud system; however the PMSE edge is not well represented by the PSD. A comparison of proxies for PMSE strength, constructed from a combination of derived dusty plasma parameters, shows that no simple proxy can reproduce PMSE strength well throughout the cloud system. Edge effects are especially poorly represented by the proxies addressed here.Keywords:
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Allowance (engineering)
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International Reference Ionosphere
Ionogram
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Ionospheric sounding
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Ionograms provide the main source of information about the electron densityprofile in the ionosphere. Some procedures have been presented for the calculation of real height profiles from ionograms. However, they usually have unacceptable errors within the valley layer of the electron density profile. In this paper, we derive a new estimating method which measures the electron density profile from propagation delay times. In order to verify the approach, the numerical experiments, which are carried out by taking the inverse fast Fourier transform of the reflection coefficient, are adopted. According to these results, it is possible to estimate the electron density profile in a one-peak profile within 1.5% errors, including the valley layer. The results show that our method gives a very accurate electron density profile.
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In this paper full‐wave calculations are described to investigate the propagation of MF radio waves in the range from 255 to 950 kHz in the lower ionosphere. The method of investigation makes use of matrix multiplications with the ionosphere divided into homogeneous layers of 100‐m thickness. The model calculations provide conclusions from MF pulse sounding results on electron density and collision frequency profiles in the height interval from 50 to 100 km. The diurnal variation of electron density in the lower ionosphere is presented. Reflections observed from heights of about 75 and 87 km during the day are shown to be produced by steep gradients of electron density.
Ionospheric sounding
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The height variation of the ionospheric electron density was measured with rocket-borne electron density probes from Alcântara (2.31ºS; 35.2ºW) in Brazil. A Black Brant X sounding rocket was launched on 14-th October 1994 at 19h55min (LT) to investigate the phenomenon of high-altitude equatorial spread-F events. Ground equipments were operated during the campaign to ensure that the rocket was launched under conditions favorable for the generation of plasma bubbles in the F-region. The electron density was measured by three different types of probes. A High Frequency Capacitance probe (HFC) gave density data with low height resolution, while a conventional Langmuir Probe (LP) and a Plasma Frequency Probe (PFP) measured the electron density and the spatial fluctuations in it. The k-spectra of the plasma irregularities were obtained by the spectral analysis of the electron density fluctuation data. An important feature observed was the continuous presence of plasma irregularities of a large range of vertical scale sizes in the altitude range of 340 km to 817 km. The electron number density varied considerably in these spatial structures, for example a decrease by a factor of 2.6 in a vertical extension of 1 km near the altitude of 497 km. Near 535 km altitude the electron density increased by a factor of 1.8 within a height range of 2.7 km. Density structures of vertical scale sizes in the range of hundreds of meters also were observed superposed on the large-scale structures. During the rocket upleg two height regions of intense irregularities were observed, one between 366 and 480 km and the other between 684 and 812 km. The Langmuir Probe (LP) could make measurements of irregularities of vertical scale sizes more than 8 m in these height ranges, while the Plasma Frequency Probe, could make measurements of irregularities of vertical scale sizes as small as 0.5 m. Spectral features of these irregularities as observed by the two plasma probes at different height regions are presented and discussed here.
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The photometers used and methods of calculation of the vertical ozone concentration profile are described. The results obtained in several series of MR-12 and M-100 sounding rocket launchings are presented and discussed.
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Atmospheric sounding
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Previously, methods of estimating the D layer electron density profile by using the VLF reflection coefficients were studied by solving a Fredholm integral equation of the first kind(1)(2). In this paper, a Fredholm integral equation not belonging to the first to third kinds is obtained for the receiving antenna output voltages for vertical polarizations, assuming known ground wave field strengths. The solution of this equation is iteratively calculated by a full wave technique(1)(2). A simulation of its solution is performed with simulated voltage measurements that include relative phase errors and multi-reflected components from the ionosphere. Voltages inferred from both exponential profiles and in-situ electron density profile measurements are used as input to the simulation. The estimated electron density profile shows fairly good agreement with both the exponential profiles and the insitu measurements.
Exponential decay
Ionospheric reflection
Reflection
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Electron density is a key physical quantity to characterize any plasma medium. Its measurement is thus essential to understand the physical processes occurring in the environment of a magnetized planet, both macroscopic and mi- croscopic. Since 2000, the four satellites of the European Space Agency (ESA) Cluster mission have been orbiting the Earth from 4 RE to 20 RE and probing the density with several types of instruments. In the magnetotail, this rare combination of experiments is particularly useful since the electron density and the tempera- ture fluctuate over several decades. Two of these experiments, a relaxation sounder and a high-time resolution wide-band receiver, have rarely been flown together in the far tail. Such wave data can be used as a means to estimate the electron den- sity via the identification of triggered resonances or the cutoffs of natural wave emissions, typically with an accuracy of a few percent. For the first time in the magnetotail .� 20 RE/, the Z-mode is proposed as the theoretical interpretation of the cutoff observed on spectrograms of wave measurements when the plasma fre- quency is greater than the electron gyrofrequency. We present examples found in the main regions of the magnetotail, comparing simultaneous density estimation from active and passive wave measurements with a particle instrument and calibrated spacecraft-to-probe potential difference data. With these examples, we illustrate the benefit of a multi-instrument approach for the estimation of the electron density in the magnetotail and the care that should be taken when determining the electron density from wave data.
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In this paper a method for the conversion of amplitude and phase interaction data to electron density profiles is developed. The method, using an iterative least squares error technique, synthesizes electron density profiles having a piece-wise linear functional form. With model studies the method is evaluated with respect to the errors that may be produced in the synthesized profile arising from uncertain values of collision frequency, disturbing pulse power, energy loss coefficient, and coefficients of interaction. Also, a demonstration of the effectiveness of the combined use of amplitude and phase interaction in producing a more accurate profile than could be obtained with amplitude data alone is presented. The method has been very successful in the synthesis of electron density profiles from actual interaction data and is presently being used for the reduction of data procured at the Ionosphere Research Laboratory during the International Quiet Sun Year. Some of these preliminary D-region profiles are presented.
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Collision frequency
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Abstract Previously, we reported a method (the previous method) for estimating by successive iterations electron density profile in the D layer in which if the absolute phase of the ionospheric reflection coefficient for the VLF wave is known, the perturbation of the reflection coefficient is found to solve the integral equation or the perturbation of the electron density by full‐wave analysis. In the present paper, the previous method has been studied theoretically and the following methods adopted: 1) successive calculation at each frequency; 2) restriction of the computed perturbation of the electron density and the successive extension to the altitude range for the corrected values of the electron density by use of the restricted value; 3) smoothing of the computed density by use of the restricted value; 3) smoothing of the computed results of the electron density; and 4) use of specific initial profile of the electron density. These methods have been applied to the exponential distributions and the measured profiles and simulations have been performed. Improved results over the previous method have been obtained. For instance, the cases that could not have been estimated by the previous method can now be estimated. the estimation range has been increased or the accuracy improved.
Smoothing
Reflection coefficient
Ionospheric reflection
Reflection
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