Последние статьи в Annales Geophysicae

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Combined list of the recent articles of the journal Annales Geophysicae and the recent discussion forum Annales Geophysicae Discussions
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Statistical analysis of magnetopause crossings at lunar distances

Thu, 03/21/2019 - 15:03
Statistical analysis of magnetopause crossings at lunar distances
Johannes Z. D. Mieth, Dennis Frühauff, and Karl-Heinz Glassmeier
Ann. Geophys., 37, 163-169, https://doi.org/10.5194/angeo-37-163-2019, 2019
The magnetopause (MP) is the primary interaction region between solar wind and the magnetic field of planet Earth and understanding of its behaviour also helps to better understand space weather. One famous model of the MP is the Shue et al. model, designed for the dayside and near-Earth situation. We take data of the ARTEMIS mission orbiting the moon and compare the MP position and shape to the model. We find differences in the location prediction but good agreement for the MP normal direction.
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Emergence of a localized total electron content enhancement during the severe geomagnetic storm of 8 September 2017

Tue, 03/19/2019 - 15:03
Emergence of a localized total electron content enhancement during the severe geomagnetic storm of 8 September 2017
Carlos Sotomayor-Beltran and Laberiano Andrade-Arenas
Ann. Geophys., 37, 153-161, https://doi.org/10.5194/angeo-37-153-2019, 2019
A localized total electron content enhancement (LTE) was observed as a product of the geomagnetic storm that happened on 8 September 2017. This result was unexpected because it was located south of the equatorial ionization anomaly (EIA). The origin of the enhancement of the TEC in the EIA is very likely due to the super-fountain effect. On the other hand, the LTE is suggested to be produced by the contribution of the super-fountain effect along with traveling ionospheric disturbances.
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Photospheric vortex flows close to the polarity inversion line of a fully emerged active region

Tue, 03/19/2019 - 15:03
Photospheric vortex flows close to the polarity inversion line of a fully emerged active region
Jean C. Santos and Cristiano M. Wrasse
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-33,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
We describe a technique used to locate and classify critical points in 2D flow fields at the solar photosphere obtained from the evolution of the line-of-sight magnetic field, in a region close to the magnetic polarity inversion line of a fully emerged active region. We apply this technique to locate a particular kind of critical point is associated to vortex flows, which are considered important since they can twist and interweave the footpoints of flux-tubes and generate magnetic reconnection.
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Ozone and temperature decadal solar-cycle responses, and their relation to diurnal variations in the stratosphere, mesosphere, and lower thermosphere, based on measurements from SABER on TIMED

Mon, 03/18/2019 - 15:03
Ozone and temperature decadal solar-cycle responses, and their relation to diurnal variations in the stratosphere, mesosphere, and lower thermosphere, based on measurements from SABER on TIMED
Frank T. Huang and Hans Mayr
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-38,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)

There is evidence that the ozone and temperature responses to the solar cycle of ~ 11 years depend on the local times of measurements. Here we present relevant results based on SABER data over a full diurnal cycle, not available previously. In this area, almost all satellite data used are made at only one or two fixed local times, which can be different among various satellites. Consequently, estimates of responses can be different depending on the specific data set. Also, over years, due to orbital drift, the local times of measurements of some satellites have also drifted. In contrast, SABER makes measurements at various local times, providing the opportunity to estimate diurnal variations over 24 hrs. We can then also estimate responses to the solar cycle over both a diurnal cycle and at the fixed local times of specific satellite data for comparison. Our results of responses, based on zonal means of SABER measurements, agree favorably with previous studies based on data from the HALOE instrument, which measured data only at sunrise and sunset, thereby supporting the analysis of both studies. We find that for ozone above ~ 40 km, zonal means reflecting specific local times (e.g., 6, 12, 18, 24 hrs) lead to different values of responses, and to different responses based on zonal means that are also averages over the 24 hours of local time, as in 3D models. For temperature, effects of diurnal variations on the responses are not negligible even at ~ 30 km and above. We also have considered the consequences of local-time variations due to orbital drifts of certain operational satellites, and for both ozone and temperature, their effects can be significant above ~ 30 km. Previous studies based other satellite data do not describe their treatment, if any, of local times. Some studies also analyzed data merged from different sources, with measurements made at different local times. Generally, the results of these studies do not agree so well among themselves. Although responses are a function of diurnal variations, this is not to say that they are the major reason for the differences, as there are likely other data-related issues. The effects due to satellite orbital drift may explain some unexpected variations in the responses, especially above 40 km.

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Monitoring potential ionospheric changes caused by the Van earthquake (Mw7.2)

Fri, 03/15/2019 - 15:03
Monitoring potential ionospheric changes caused by the Van earthquake (Mw7.2)
Samed Inyurt, Selcuk Peker, and Cetin Mekik
Ann. Geophys., 37, 143-151, https://doi.org/10.5194/angeo-37-143-2019, 2019

Many scientists from different disciplines have studied earthquakes for many years. As a result of these studies, it has been proposed that some changes take place in the ionosphere layer before, during or after earthquakes, and that the ionosphere should be monitored in earthquake prediction studies. This study investigates the changes in the ionosphere created by the earthquake with a magnitude of Mw=7.2 in the northwest of Lake Erçek, which is located to the north of the province of Van in Turkey on 23 October 2011 and at 13:41 local time (−3 UT) with the epicenter of 38.75∘ N, 43.36∘ E using the TEC values obtained by the global ionosphere models (GIMs) created by IONOLAB-TEC and CODE. In order to see whether the ionospheric changes obtained by the study in question were caused by the earthquake or not, the ionospheric conditions were studied by utilizing indices providing information on solar and geomagnetic activities (F10.7 cm, Kp, Dst).

One of the results of the statistical test of the TEC values obtained from both models is positive and negative anomalies obtained for the times before, on the day of and after the earthquake, and the reasons for these anomalies are discussed in detail in the last section of the study. As the ionospheric conditions on the analyzed days were highly variable, it was thought that the anomalies were caused by geomagnetic effects, solar activity and the earthquake.

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Variation in altitude of high-frequency enhanced plasma line by the pump near the 5th electron gyro-harmonic

Thu, 03/14/2019 - 15:03
Variation in altitude of high-frequency enhanced plasma line by the pump near the 5th electron gyro-harmonic
Jun Wu, Jian Wu, Michael T. Rietveld, Ingemar Haggstrom, Haisheng Zhao, Tong Xu, and Zhengwen Xu
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-23,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)

During an ionospheric heating campaign carried out at the European Incoherent Scatter Scientific Association (EISCAT), the ultra high frequency incoherent scatter (IS) radar observed a systematic variation in the altitude of the high-frequency enhanced plasma line (HFPL), which behaves depending on the pump frequency. Specifically, the HFPL altitude becomes lower when the pump lies above the 5th gyro-harmonic. The analysis shows that the enhanced electron temperature plays a decisive role in the descent in the HFPL altitude. That is, on the traveling path of the enhanced Langmuir wave, the enhanced electron temperature can only be matched by the low electron density at a lower altitude so that the Bragg condition can be satisfied, as expected from the dispersion relation of Langmuir wave.

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Notes on the correlation between SSWs and solar activity

Fri, 03/08/2019 - 15:03
Notes on the correlation between SSWs and solar activity
Ekaterina Vorobeva
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-21,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
We investigated the statistical relationship between solar activity and occurrence rate of major sudden stratospheric warmings (MSSWs). For this purpose, F10.7 radio flux has been used as a proxy for solar activity. The calculations have been performed based on two datasets of central day (NCEP-NCAR-I and combined ERA) for the period from 1958 to 2013. The analysis revealed a positive correlation between MSSW events and solar activity.
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Long-term trends in the ionospheric response to solar EUV variations

Fri, 03/08/2019 - 15:03
Long-term trends in the ionospheric response to solar EUV variations
Rajesh Vaishnav, Christoph Jacobi, and Jens Berdermann
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-34,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
We investigate the ionospheric response to the temporal and spatial dynamics of the solar activity using total electron content (TEC) maps and multiple solar proxies. The maximum correlation at 16–32 days time scale is observed between the He-II, Mg-II, and F30 with respect to global mean TEC, with an effective time delay of about one day. The most suitable proxy to represent the solar activity at the time scales of 16–32 days and 32–64 days is He-II.
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On the evaluation of the phase relation between temperature and wind tides based on ground-based measurements and reanalysis data in the middle atmosphere

Fri, 03/08/2019 - 15:03
On the evaluation of the phase relation between temperature and wind tides based on ground-based measurements and reanalysis data in the middle atmosphere
Kathrin Baumgarten and Gunter Stober
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-25,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
The paper presents the variability of thermal tides in the middle atmosphere from temperature observations as well as from horizontal wind data using a new diagnostic approach which takes into account a possible intermittency of tides. The data is analyzed from a local as well as from a global perspective to distinguish between different tidal modes. Surprisingly, there are dominating tidal modes, which are seen in the local data and a phase relation between temperature and winds is evaluated.
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Spring and summer time ozone and solar ultraviolet radiation variations over Cape Point, South Africa

Wed, 03/06/2019 - 15:03
Spring and summer time ozone and solar ultraviolet radiation variations over Cape Point, South Africa
David J. du Preez, Jelena V. Ajtić, Hassan Bencherif, Nelson Bègue, Jean-Maurice Cadet, and Caradee Y. Wright
Ann. Geophys., 37, 129-141, https://doi.org/10.5194/angeo-37-129-2019, 2019
Reduced atmospheric ozone results in increased solar ultraviolet radiation (UVR) at the surface which may potentially negative impact public health. We aimed to assess whether or not the break-up of the Antarctic ozone hole had an impact on ozone and UVR at Cape Point (South Africa). We found a moderate inverse relationship between ozone and UVR at midday on clear-sky days. The Antarctic ozone hole had a limited effect on ozone levels while tropical air masses more frequently affected the site.
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The linear growth rate of Rayleigh–Taylor instability in ionospheric F layer

Wed, 03/06/2019 - 15:03
The linear growth rate of Rayleigh–Taylor instability in ionospheric F layer
Kangkang Liu
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-28,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
When studying the Rayleigh-Taylor instability (RTI) in the ionosphere, I found that the physical description of RTI in ionosphere attribute the growth of RTI to charge accumulation, however, the current continuity equation was used during the calculation of the linear growth rate. Also, the linear growth rate widely used tends to infinity when the collision frequency tends to zero. In this paper, we derived the linear growth rate of RTI and rectified the physical description of the RTI process.
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Comparison of GNSS integrated water vapor and NWM reanalysis data over Central and South America

Wed, 03/06/2019 - 15:03
Comparison of GNSS integrated water vapor and NWM reanalysis data over Central and South America
Laura Isabel Fernández, Amalia Margarita Meza, María Paula Natali, and Clara Eugenia Bianchi
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-20,2019
Manuscript under review for ANGEO (discussion: open, 1 comment)
Integrated Water Vapor (IWV) values from ERA-Interim and MERRA-2 were compared to IWV from GNSS at 53 stations of Central and South America during a 7-year period (2007–2013). The comparison takes into account the geopotential height differences and the mean IWV value at each station. The discrepancies between IWV from the models and IWV GNSS raise as the geopotential height difference grows. We proposed a numerical correction that compensates this effect and it was tested with IWV ERA-Interim.
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The research on small-scale structures of ice particle density and electron density in the mesopause region

Tue, 03/05/2019 - 15:03
The research on small-scale structures of ice particle density and electron density in the mesopause region
Ruihuan Tian, Jian Wu, Jinxiu Ma, Yonggan Liang, Hui Li, Chengxun Yuan, Yongyuan Jiang, and Zhongxiang Zhou
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-10,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
The density distribution of ice particles and electrons near the boundary of PMSE region is studied. The results show that when the radius distribution function of condensation nucleus is Gaussian type, for a certain range of the condensation core radius, sharp peaks with scale of meters appear in the density profiles of ice particles and electrons. These small-scale structures of electron density may be one of the reasons of PMSE phenomenon.
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Evidence of vertical coupling: Meteorological storm Fabienne on 23 September 2018 and its related effects observed up to the ionosphere

Tue, 03/05/2019 - 15:03
Evidence of vertical coupling: Meteorological storm Fabienne on 23 September 2018 and its related effects observed up to the ionosphere
Petra Koucká Knížová, Kateřina Podolská, Kateřina Potužníková, Daniel Kouba, Zbyšek Mošna, Josef Boška, and Michal Kozubek
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-26,2019
Manuscript under review for ANGEO (discussion: open, 1 comment)
Severe meteorological storm Fabienne passing above Central Europe was observed. Significant variations of atmospheric and ionospheric parameters were detected. Above Europe, stratospheric temperature and wind significantly changed in coincidence with frontal transition. Within ionospheric parameters, we have detected significant wave-like activity shortly after the cold front crossed the observational point. During the storm event, we have observed strong horizontal plasma flow shears.
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Phenomena preceding major earthquakes interconnected through a physical model

Mon, 03/04/2019 - 15:03
Phenomena preceding major earthquakes interconnected through a physical model
Panayiotis A. Varotsos, Nicholas V. Sarlis, and Efthimios S. Skordas
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-29,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
In this paper, we summarize the anomalous phenomena that have been observed before the super-giant earthquake of magnitude 9.0 that occurred on 11 March 2011 in Japan. These phenomena have been detected by means of ground based measurements and satellite data. We find that all these phenomena are in agreement with a condensed matter physical model that motivated in the 1980s a short-term earthquake prediction method based on the detection of precursory electric signals.
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Global analysis for periodic variations of gravity wave squared amplitudes and momentum fluxes in the middle atmosphere

Mon, 03/04/2019 - 15:03
Global analysis for periodic variations of gravity wave squared amplitudes and momentum fluxes in the middle atmosphere
Dan Chen, Cornelia Strube, Manfred Ern, Peter Preusse, and Martin Riese
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-31,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
In this paper, for the first time, absolute gravity wave momentum flux (GWMF) on temporal scales from terannual variation up to solar cycle length are investigated. The systematic spectral analysis of SABER absolute GWMF are presented and physically interpreted. The various role of filtering and oblique propagating is discussed which is likely an important factor for MLT dynamics, and hence can be used as a stringent test bed of the reproduction of such features in global models.
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High Resolution Vertical Total Electron Content Maps Based on Multi-Scale B-spline Representations

Mon, 03/04/2019 - 15:03
High Resolution Vertical Total Electron Content Maps Based on Multi-Scale B-spline Representations
Andreas Goss, Michael Schmidt, Eren Erdogan, Barbara Görres, and Florian Seitz
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-32,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
The paper describes an approach to model VTEC from NRT GNSS observations only by generating a Multi-Scale-Representation (MSR) based on B-splines. The unknown model parameters are estimated by means of a Kalman-Filter. A number of products have been created which differ both in their spectral and temporal resolution. The validation studies show that the product of highest resolution, based on NRT input data is of higher accuracy than other used within the selected time span of investigation.
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Effects of Earth's magnetic field variation on high frequency wave propagation in the ionosphere

Wed, 02/27/2019 - 15:03
Effects of Earth's magnetic field variation on high frequency wave propagation in the ionosphere
Mariano Fagre, Bruno S. Zossi, Erdal Yiğit, Hagay Amit, and Ana G. Elias
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-27,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
Some systems, such as Over the Horizon Radars, use the ionosphere as a reflector for HF radio signals. In this work, HF propagation through the ionosphere is studied for different Earth’s magnetic field configurations during reversals using a numerical ray tracing technique. Our purpose is to highlight possible effects of dipole decrease, which is currently ongoing, on electromagnetic wave propagation through the ionosphere.
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Spread F occurrence features at different longitudinal regions during low and moderate solar activity

Wed, 02/27/2019 - 15:03
Spread F occurrence features at different longitudinal regions during low and moderate solar activity
Abimbola O. Afolayan, Singh J. Mandeep, Mardina Abdullah, Suhaila M. Buhari, Tatsuhiro Yokoyama, and Pornchai Supnithi
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-24,2019
Manuscript under review for ANGEO (discussion: open, 0 comments)
The equatorial spread F (ESF) is a nighttime phenomenon which has the potential to have a deleterious effect on the radio communication system. We investigated the parameters influencing the seasonal morphology of the ESF using the ionosonde data taken at different longitudinal sectors. The ESF occurrence features including the onset time and seasonal asymmetry showed distinct patterns across these sectors. The gravity wave was identified as a significant factor to these seasonal distributions.
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Measurements of Aerosols and Charged Particles On the BEXUS18 Stratospheric Balloon

Fri, 02/22/2019 - 15:03
Measurements of Aerosols and Charged Particles On the BEXUS18 Stratospheric Balloon
Erika Brattich, Encarnación Serrano Castillo, Fabrizio Giulietti, Jean-Baptiste Renard, Sachi N. Tripathi, Kunal Ghosh, Gwenael Berthet, Damien Vignelles, and Laura Tositti
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-12,2019
Manuscript under review for ANGEO (discussion: open, 1 comment)
This paper describes the aerosol measurements setup and results obtained during the BEXUS18 stratospheric balloon within the A5-Unibo (Advanced Atmospheric Aerosol Acquisition and Analysis) experiment performed on October 10th, 2014 in northern Sweden (Kiruna). The experiment and the results here presented broaden the understanding of the processes linking the presence of charges with particles all over the vertical heights from ground to the stratosphere.
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