MSIS‐86 Thermospheric Model

Hedin, A. E.

doi:10.1029/ja092ia05p04649

Cited by 1,613 publications

(932 citation statements)

References 15 publications

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“…On the other hand, the value of NmF2 is a function of production and loss rate of unexcited and electronically excited O + ions (see, e.g., Pavlov and Pavlova, 2005). As a result, the F2-layer peak electron density depends on the neutral temperature and densities whose values are functions of F10.7 solar activity index for a previous day (Hedin, 1987). Hence, we find a difference between F10.7 solar activity indexes for days preceding the winter and summer days examined.…”

Section: Statistical Study Of the Nmf2 Winter Anomaly: Results And DImentioning

confidence: 99%

“…The characteristic time of the neutral composition recovery after a storm impulse event ranges from 7 to 12 h on average (Hedin, 1987), while it may need days for all altitudes down to 120 km in the atmosphere to recover completely back to the undisturbed state of the atmosphere (Richmond and Lu, 2000). Therefore, we believe that the values of NmF2 and hmF2 at given UT are the geomagnetically quiet ionospheric parameters if K p ≤3 at UT under consideration and for 24-h time period prior to given UT.…”

Section: Datamentioning

confidence: 99%

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Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study

Павлов

Павлова

2009

Ann. Geophys.

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Abstract. We present a statistical study of variations in the F2-layer peak electron density, NmF2, and altitude, hmF2, over the Argentine Islands ionosonde. The critical frequencies, foF2, and, foE, of the F2 and E-layers, and the propagation factor, M(3000)F2, measured by the ionosonde during the 1957-1959 and 1962-1995 time periods were used in the statistical analysis to determine the values of NmF2 and hmF2. The probabilities to observe maximum and minimum values of NmF2 and hmF2 in a diurnal variation of the electron density are calculated. Our study shows that the main part of the maximum diurnal values of NmF2 is observed in a time sector close to midnight in November, December, January, and February exhibiting the anomalous diurnal variations of NmF2. Another anomalous feature of the diurnal variations of NmF2 exhibited during November, December, and January when the minimum diurnal value of NmF2 is mainly located close to the noon sector. These anomalous diurnal variations of NmF2 are found to be during both geomagnetically quiet and disturbed conditions. Anomalous features are not found in the diurnal variations of hmF2. The statistical study of the NmF2 winter anomaly phenomena over the Argentine Islands ionosonde was carried out. The variations in a maximum daytime value, R, of a ratio of a geomagnetically quiet daytime winter NmF2 to a geomagnetically quiet daytime summer NmF2 taken at a given UT and for approximately the same level of solar activity were studied. The conditional probability of the occurrence of R in an interval of R, the most frequent value of R, the mean expected value of R, and the conditional probability to observe the F2-region winter anomaly during a daytime period were calculated for low, moderate, and high solar activity. The calCorrespondence to: A. V. Pavlov (pavlov@izmiran.ru) culations show that the mean expected value of R and the occurrence frequency of the F2-region winter anomaly increase with increasing solar activity.

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Section: Statistical Study Of the Nmf2 Winter Anomaly: Results And DImentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study

Павлов

Павлова

2009

Ann. Geophys.

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“…Only a brief description of the most important features will be given here. [Hedin, 1987], and the neutral wind pattern used is that described by Sojka et al [1981].…”

Section: Model Descriptionsmentioning

confidence: 99%

Seasonal and solar cycle variations of the polar wind

Demars¹,

Schunk²

2001

J. Geophys. Res.

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Abstract. Until recently, theoretical models of the polar wind were one-dimensional. In these models, reasonable but ad hoc boundary conditions were fed to a mathematical model, which was then solved to provide either a steady state or time-dependent description of the plasma along a particular field line. These models were inherently unable to address the three-dimensional structure of the polar wind. Now, a truly global model of the polar wind has been developed. This model is a three-dimensional, time-dependent, fluid model that self-consistently couples the ionosphere and the polar wind. It describes the plasma dynamics in a large number of high-latitude flux tubes as they move under the combined influence of corotational and convection electric fields. The model incorporates realistic models of the high-latitude convection and auroral electron precipitation. In this study, the global model of the ionosphere and polar wind was used to illuminate the seasonal and solar cycle variability of the polar wind's three-dimensional structure. In particular, the threedimensional distribution of both H + and O + ions in the polar wind was examined for both solar maximum and minimum conditions and for both summer and winter solstices, as well as for various levels of geomagnetic activity. Over 1000 flux tubes of plasma are modeled for each set of geophysical conditions considered in this study, providing a horizontal resolution that is much finer than in previous applications of the global model. The modeling results are compared with relevant observational databases.

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“…where the values of jv and i Ã j are given in g. There is no possibility to di erentiate the vibrationally unexcited O 2 from the vibrationally excited O 2 during the mass-spectrometer measurements of the neutral species in the atmosphere, and we therefore believe that the MSIS-86 neutral model (Hedin, 1987) …”

Section: Energy Balance Equations For Ions and Electronsmentioning

confidence: 99%

Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

Павлов

1997

Ann. Geophys.

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Abstract. This study compares the OV1-10 satellite measurements of the integral airglow intensities at 630 nm in the SAR arc regions observed in the northern and southern hemisphere as a conjugate phenomenon, with the model results obtained using the time-dependent one-dimensional mathematical model of the Earth ionosphere and plasmasphere (the IZMIRAN model) during the geomagnetic storm of the period 15±17 February 1967. The major enhancements to the IZ-MIRAN model developed in this study are the inclusion of He ions (three major ions: O , H , and He , and three ion temperatures), the updated photochemistry and energy balance equations for ions and electrons, the di usion of NO and O 2 ions and O 1 D and the revised electron cooling rates arising from their collisions with unexcited N 2 Y O 2 molecules and N 2 molecules at the ®rst vibrational level. The updated model includes the option to use the models of the Boltzmann or nonBoltzmann distributions of vibrationally excited molecular nitrogen. Deviations from the Boltzmann distribution for the ®rst ®ve vibrational levels of N 2 were calculated. The calculated distribution is highly nonBoltzmann at vibrational levels v b 2 and leads to a decrease in the calculated electron density and integral intensity at 630 nm in the northern and southern hemispheres in comparison with the electron density and integral intensity calculated using the Boltzmann vibrational distribution of N 2 . It is found that the intensity at 630 nm is very sensitive to the oxygen number densities. Good agreement between the modeled and measured intensities is obtained provided that at all altitudes of the southern hemisphere a reduction of about factor 1.35 in MSIS-86 atomic oxygen densities is included in the IZMIRAN model with the non-Boltzmann vibrational distribution of N 2 . The e ect of using of the O 1 D di usion results in the decrease of 4±6% in the calculated integral intensity of the northern hemisphere and 7±13% in the calculated integral intensity of the southern hemisphere. It is found that the modeled intensities of the southern hemisphere are more sensitive to the assumed values of the rate coe cients of O 4 S ions with the vibrationally excited nitrogen molecules and quenching of O 2 D by atomic oxygen than the modeled intensities of the northern hemisphere.

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MSIS‐86 Thermospheric Model

Cited by 1,613 publications

References 15 publications

Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study

Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study

Seasonal and solar cycle variations of the polar wind

Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

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MSIS‐86 Thermospheric Model

Cited by 1,613 publications

References 15 publications

Anomalous variations of &lt;I&gt;Nm&lt;/I&gt;F2 over the Argentine Islands: a statistical study

Anomalous variations of &lt;I&gt;Nm&lt;/I&gt;F2 over the Argentine Islands: a statistical study

Seasonal and solar cycle variations of the polar wind

Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

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Product

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Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study

Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study