Analysis of electron density calculations using deterministic-probabilistic model of the ionospheric D-region

The work is devoted to the development of a fundamentally new way of modeling the ionospheric D-region – deterministic-probabilistic. The results of Ne calculations using this technique are analyzed. Research of this kind is of fundamental importance, related to the rejection of a purely deterministic description of a continuously changing environment such as the ionosphere. In this work, the electron density is calculated using a five-component system of ionization-recombination cycle equations. Probability density functions (PDFs) of input parameters of the model are used to solve the system. The most important sources of the D-region ionization are taken into account to calculate PDFs of the ionization rate. The necessary number of iterations is determined by the convergence of PDFs of the electron density from 50 km to 85 km at midlatitudes under different heliogeophysical conditions. Theoretical Ne PDFs have been shown to be in good agreement with two experimental databases on electron density, especially at large D-region heights. The next important stage of modeling is the thorough verification of Ne PDFs from experimental radiophysical data on VLF–LF propagation.

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Analysis of electron density calculations using deterministic-probabilistic model of the ionospheric D-region

Solnechno-Zemnaya Fizika ◽

10.12737/szf-43201809 ◽

2018 ◽

Vol 4 (3) ◽

pp. 84-94

Author(s):

Сусанна Беккер ◽

Susanna Bekker

Keyword(s):

Probability Density ◽

Electron Density ◽

Probabilistic Model ◽

Ionization Rate ◽

Probability Density Functions ◽

Density Functions ◽

Component System ◽

D Region ◽

Number Of Iterations ◽

Good Agreement

The work is devoted to the development of a fundamentally new way of modeling the ionospheric D-region — deterministic-probabilistic. The results of electron density (Ne) calculations using this technique are analyzed. Research of this kind is of fundamental importance, related to the rejection of a purely deter-ministic description of a continuously changing envi-ronment such as the ionosphere. In this work, Ne is cal-culated using a five-component system of ionization-recombination cycle equations. Probability density functions (PDFs) of input parameters of the model are used to solve the system. The most important sources of the D-region ionization are taken into account to calculate PDFs of the ionization rate. The necessary number of iterations is determined by the convergence of PDFs of the electron density from 50 to 85 km at midlatitudes under different heliogeophysical conditions. Theoretical Ne PDFs have been shown to be in good agreement with two experimental databases on electron density, especially at large D-region heights. The next important stage of modeling is the thorough verification of PDFs from experimental radiophysical data on VLF—LF propagation.

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Bimodal and multimodal descriptions of soil-water characteristic curves for structural soils

Water Science & Technology ◽

10.2166/wst.2013.046 ◽

2013 ◽

Vol 67 (8) ◽

pp. 1740-1747 ◽

Cited By ~ 5

Author(s):

Shiyu Liu ◽

Noriyuki Yasufuku ◽

Qiang Liu ◽

Kiyoshi Omine ◽

Hazarika Hemanta

Keyword(s):

Probability Density Function ◽

Probability Density ◽

Soil Water ◽

Lognormal Distribution ◽

Probability Density Functions ◽

Density Functions ◽

Characteristic Curves ◽

Physically Based ◽

Soil Water Characteristic Curves ◽

Good Agreement

In the last decades several approaches have been developed to describe bimodal or multimodal soil-water characteristic curves (SWCCs). Unfortunately, most of these models were derived empirically. In the presented study, physically based bimodal and multimodal SWCC functions have been developed for structural soils. The model involved two or more continual pore series; the probability density functions for each pore series were assumed to be lognormal distribution and can be superposed to obtain the overall probability density function of the structural soils. The proposed functions were capable of simulating bimodal or multimodal SWCCs using parameters which can be related to physical properties of the structural soils. The experimental SWCC data were used to verify the proposed method. The fitting results showed that the proposed approaches resulted in good agreement between measurement and simulation. These functions can potentially be used as effective tools for indentifying hydraulic porosities in the structural mediums.

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Electron density profiles in the quiet lower ionosphere based on the results of modeling and experimental data

Annales Geophysicae ◽

10.5194/angeo-30-1345-2012 ◽

2012 ◽

Vol 30 (9) ◽

pp. 1345-1360 ◽

Cited By ~ 20

Author(s):

V. Barabash ◽

A. Osepian ◽

P. Dalin ◽

S. Kirkwood

Keyword(s):

Solar Activity ◽

Electron Density ◽

Lower Ionosphere ◽

Ionization Rate ◽

Number Density ◽

Density Profiles ◽

Oxide Concentration ◽

D Region ◽

Nitric Oxide Concentration ◽

Electron Density Profiles

Abstract. The theoretical PGI (Polar Geophysical Institute) model for the quiet lower ionosphere has been applied for computing the ionization rate and electron density profiles in the summer and winter D-region at solar zenith angles less than 80° and larger than 99° under steady state conditions. In order to minimize possible errors in estimation of ionization rates provided by solar electromagnetic radiation and to obtain the most exact values of electron density, each wavelength range of the solar spectrum has been divided into several intervals and the relations between the solar radiation intensity at these wavelengths and the solar activity index F10.7 have been incorporated into the model. Influence of minor neutral species (NO, H2O, O, O3) concentrations on the electron number density at different altitudes of the sunlit quiet D-region has been examined. The results demonstrate that at altitudes above 70 km, the modeled electron density is most sensitive to variations of nitric oxide concentration. Changes of water vapor concentration in the whole altitude range of the mesosphere influence the electron density only in the narrow height interval 73–85 km. The effect of the change of atomic oxygen and ozone concentration is the least significant and takes place only below 70 km. Model responses to changes of the solar zenith angle, solar activity (low–high) and season (summer–winter) have been considered. Modeled electron density profiles have been evaluated by comparison with experimental profiles available from the rocket measurements for the same conditions. It is demonstrated that the theoretical model for the quiet lower ionosphere is quite effective in describing variations in ionization rate, electron number density and effective recombination coefficient as functions of solar zenith angle, solar activity and season. The model may be used for solving inverse tasks, in particular, for estimations of nitric oxide concentration in the mesosphere.

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Simulation of Gravity Wave D-region disturbance and its effect on the LWPC simulated VLF signal

10.5194/angeo-2020-68 ◽

2021 ◽

Author(s):

Abdellatif Benchafaa ◽

Samir Nait Amor ◽

Ghazali Mebarki

Keyword(s):

Gravity Wave ◽

Electron Density ◽

Gravity Waves ◽

Low Frequency ◽

Ionization Rate ◽

Neutral Atmosphere ◽

Long Wave ◽

Reflection Height ◽

D Region ◽

Atmosphere Density

Abstract. In this work we show the result of the numerical simulation of the gravity waves (GWs) D region disturbance. Effectively, using the Glukhov-Pasko-Inan (GPI) model of the electron density in the D region we were figured out the response of the electron density due to gravity wave neutral atmosphere oscillation. As a consequence to the D region disturbance, the electron density sometimes increases when the neutral atmosphere density decreases and vice versa. This behavior was interpreted by the decreases or increases of ionization rate by chemical loss process. In a second simulation work, we used the Long Wave Propagation Capability (LWPC) code to simulate the Very Low Frequency (VLF) signal when the gravity wave disturbance crossed the VLF path. The effect of the disturbance is to decrease the VLF signal reflection height below the ambient altitude (87 km) when the electron density increases. On the other hand and when the electron density drops, the VLF reflection altitude increased higher than 87 km.

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Comparison of satellite limb-sounding humidity climatologies of the uppermost tropical troposphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-309-2008 ◽

2008 ◽

Vol 8 (2) ◽

pp. 309-320 ◽

Cited By ~ 15

Author(s):

M. Ekström ◽

P. Eriksson ◽

W. G. Read ◽

M. Milz ◽

D. P. Murtagh

Keyword(s):

Probability Density ◽

Infrared Region ◽

Probability Density Functions ◽

Climate Modelling ◽

Density Functions ◽

Upper Troposphere ◽

Upper Tropospheric Humidity ◽

Tropical Troposphere ◽

Sky Conditions ◽

Good Agreement

Abstract. Humidity climatologies of the tropical uppermost troposphere from satellite limb emission measurements have been compared. Four instruments are considered; UARS-MLS, Odin-SMR, and Aura-MLS operating in the microwave region, and MIPAS in the infrared region. A reference for the comparison is obtained by MOZAIC in-situ measurements. The upper tropospheric humidity products were compared on basis of their empirical probability density functions and seasonally averaged horizontal fields at two altitude layers, 12 and 15 km. The probability density functions of the microwave datasets were found to be in very good agreement with each other, and were also consistent with MOZAIC. The average seasonal humidities differ with less than 10%RHi between the instruments, indicating that stated measurement accuracies of 20–30% are conservative estimates. The systematic uncertainty in Odin-SMR data due to cloud correction was also independently estimated to be 10%RHi. MIPAS humidity profiles were found to suffer from cloud contamination, with only 30% of the measurements reaching into the upper troposphere, but under clear-sky conditions there is a good agreement between MIPAS, Odin-SMR and Aura-MLS. Odin-SMR and the two MLS datasets can be treated as independent, being based on different underlying spectroscopy and technology. The good agreement between the microwave limb-sounders, and MOZAIC, is therefore an important step towards understanding the upper tropospheric humidity. The found accuracy of 10%RHi is approaching the level required to validate climate modelling of the upper troposphere humidity. The comparison of microwave and infrared also stresses that microwave limb-sounding is necessary for a complete view of the upper troposphere.

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Comparison of Numerical Simulations of the Electron Density in the D-Region Ionosphere with Measurements of the Radar of Partial Reflections

EPJ Web of Conferences ◽

10.1051/epjconf/201922403011 ◽

2019 ◽

Vol 224 ◽

pp. 03011

Author(s):

Aleksandr Gomonov ◽

Roman Yurik ◽

Yulia Shapovalova ◽

Sergei Cherniakov ◽

Olga Ogloblina

Keyword(s):

Experimental Data ◽

Numerical Simulations ◽

Electron Density ◽

High Electron ◽

High Electron Density ◽

Geophysical Institute ◽

Partial Reflection ◽

Polar Geophysical Institute ◽

D Region ◽

Good Agreement

The paper reports results of a comparison of the measured electron density in the ionospheric D-region measured using the partial reflection facility at the observatory. Tumanny of the Polar Geophysical Institute (69.0°N, 35.7°E) with numerical simulations performed using the theoretical model of the Polar Geophysical Institute (PGI) (Murmansk, Russian Federation). The model was examined using experimental data obtained under quiet geomagnetic conditions in March, 2017. The comparative analysis carried out in this study shows a very good agreement of the PGI model with experimental data and indicates that the IRI-2016 model fails to adequately reproduce measurements in regions with high electron density gradients.

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A Refinement of the Millionshchikov Quasi-Normality Hypothesis for Convective Boundary Layer Turbulence

Journal of the Atmospheric Sciences ◽

10.1175/jas3457.1 ◽

2005 ◽

Vol 62 (7) ◽

pp. 2632-2638 ◽

Cited By ~ 33

Author(s):

Vladimir M. Gryanik ◽

Jörg Hartmann ◽

Siegfried Raasch ◽

Michael Schröter

Keyword(s):

Fourth Order ◽

Probability Density Functions ◽

Density Functions ◽

Convective Conditions ◽

Convective Boundary ◽

Velocity Fluctuations ◽

Boundary Layer Turbulence ◽

Eddy Simulation ◽

Large Eddy ◽

Good Agreement

Abstract The Millionshchikov hypothesis of quasi-normal distribution of fourth-order moments fails for convective conditions where the probability density functions of temperature and vertical velocity fluctuations are skewed. This is shown for aircraft and large-eddy simulation (LES) data, and new closures for fourth-order moments that take the skewness into account are suggested. These new closures are in very good agreement with the data.

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Hydrological Probabilistic Model MARCS and Its Application to Simulate the Probability Density Functions of Multi-year Maximal Runoff: The Russian Arctic as a Case of Study

The Interconnected Arctic — UArctic Congress 2016 - Springer Polar Sciences ◽

10.1007/978-3-319-57532-2_8 ◽

2017 ◽

pp. 77-87 ◽

Cited By ~ 1

Author(s):

Elena Shevnina ◽

Ekaterina Gaidukova

Keyword(s):

Probability Density ◽

Probabilistic Model ◽

Probability Density Functions ◽

Density Functions ◽

Russian Arctic ◽

Maximal Runoff

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Comparison of satellite limb-sounding humidity climatologies of the uppermost tropical troposphere

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-12617-2007 ◽

2007 ◽

Vol 7 (4) ◽

pp. 12617-12655

Author(s):

M. Ekström ◽

P. Eriksson ◽

W. G. Read ◽

D. P. Murtagh

Keyword(s):

Probability Density ◽

Probability Density Functions ◽

Climate Modelling ◽

Density Functions ◽

Upper Troposphere ◽

Clear Sky ◽

Upper Tropospheric Humidity ◽

Tropical Troposphere ◽

Sky Conditions ◽

Good Agreement

Abstract. Humidity climatologies of the tropical uppermost troposphere from satellite limb emission measurements have been compared. Four instruments are considered; UARS-MLS, Odin-SMR, and Aura-MLS operating in the microwave region, and MIPAS in the IR region. A reference for the comparison is obtained by MOZAIC in-situ measurements. The upper tropospheric humidity products were compared on basis of their empirical probability density functions and seasonally averaged horizontal fields at two altitude layers, 12 and 15 km. The probability density functions of the microwave datasets were found to be in very good agreement with each other, and are also consistent with MOZAIC. The average seasonal humidities differ with less than 10%RHi between the instruments, indicating that stated measurement accuracies of 20–30% are conservative estimates. The systematic uncertainty in Odin-SMR data due to cloud correction was also independently estimated to be 10%RHi. MIPAS humidity profiles were found to suffer from cloud contamination, with only 30% of the measurements reaching into the upper troposphere, but under clear-sky conditions there is a good agreement between MIPAS, Odin-SMR and Aura-MLS. Odin-SMR and the two MLS datasets can be treated as independent, being based on different underlying spectroscopy and technology. The good agreement between the microwave limb-sounders, and MOZAIC, is therefore an important step towards understanding the upper tropospheric humidity. The found accuracy of 10%RHi is approaching the level required to validate climate modelling of the upper troposphere humidity. The comparison of microwave and IR also stresses that microwave limb-sounding is necessary for a complete view of the upper troposphere.

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