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ANGEO - recent papers



Combined list of the recent articles of the journal Annales Geophysicae and the recent discussion forum Annales Geophysicae Discussions



 



Meteor echo height ceiling effect and the mesospheric temperature estimation from meteor radar observation

Mon, 23 Apr 2018 17:31:37 +0200

Meteor echo height ceiling effect and the mesospheric temperature estimation from meteor radar observation
Changsup Lee, Geonhwa Jee, Jeong-Han Kim, and In-Sun Song
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-32,2018
Manuscript under review for ANGEO (discussion: open, 0 comments)
This study shows the width of the meteor height distribution (FWHM) is well correlated with the atmospheric pressure not only experimentally but theoretically. From the correlation analysis, we newly found that the FWHM provides best estimation of the temperature at the height layer below the meteor peak height by 2–3 km. We also proved a meteor echo height ceiling effect (MHC) is primarily controlled by the atmospheric condition and this enables the FWHM to estimate the temperature accurately.



Investigating the anatomy of magnetosheath jets – MMS observations

Mon, 23 Apr 2018 17:31:37 +0200

Investigating the anatomy of magnetosheath jets – MMS observations
Tomas Karlsson, Ferdinand Plaschke, Heli Hietala, Martin Archer, Xóchitl Blanco-Cano, Primož Kajdič, Per-Arne Lindqvist, Göran Marklund, and Daniel J. Gershman
Ann. Geophys., 36, 655-677, https://doi.org/10.5194/angeo-36-655-2018, 2018
We have studied fast plasma jets outside of Earth’s magnetic environment. Such jets are small-scale structures with a limited lifetime, which may be important in determining the properties of the near-Earth space environment, due to their concentrated kinetic energy. We have used data from the NASA Magnetospheric MultiScale (MMS) satellites to study their properties in detail, to understand how these jets are formed. We have found evidence that there are at least two different types of jets.



On application of asymmetric Kan-like exact equilibria to the Earth magnetotail modeling

Thu, 19 Apr 2018 17:31:37 +0200

On application of asymmetric Kan-like exact equilibria to the Earth magnetotail modeling
Daniil B. Korovinskiy, Darya I. Kubyshkina, Vladimir S. Semenov, Marina V. Kubyshkina, Nikolai V. Erkaev, and Stefan A. Kiehas
Ann. Geophys., 36, 641-653, https://doi.org/10.5194/angeo-36-641-2018, 2018
The Harris–Fadeev–Kan–Manankova family of exact two-dimensional equilibria is generalized to reproduce the slow decrease of the normal magnetic component in the tailward direction, and the magnetotail current sheet bending and shifting in the vertical plane, arising from the Earth dipole tilting and the solar wind nonradial propagation. The analytical solution is found to fit the empirical T96 model, especially, at distances beyond 10–15 Earth radii at high levels of magnetospheric activity.



Solar rotational cycle in lightning activity in Japan during the 18–19th centuries

Wed, 18 Apr 2018 17:31:37 +0200

Solar rotational cycle in lightning activity in Japan during the 18–19th centuries
Hiroko Miyahara, Ryuho Kataoka, Takehiko Mikami, Masumi Zaiki, Junpei Hirano, Minoru Yoshimura, Yasuyuki Aono, and Kiyomi Iwahashi
Ann. Geophys., 36, 633-640, https://doi.org/10.5194/angeo-36-633-2018, 2018
Old diaries kept in Japan tell us a surprising fact. The 27-day solar rotational period in thunder and lightning activities had been persistent for the past 300 years. The intensity is found to be more prominent as solar activity increases. The physical mechanism of the Sun–Climate connection is yet uncertain, an important link surely exists between the solar activity and terrestrial climate even at a meteorological timescale.



A critical note on the IAGA-endorsed Polar Cap (PC) indices: excessive excursions in the real-time index values

Mon, 16 Apr 2018 17:31:37 +0200

A critical note on the IAGA-endorsed Polar Cap (PC) indices: excessive excursions in the real-time index values
Peter Stauning
Ann. Geophys., 36, 621-631, https://doi.org/10.5194/angeo-36-621-2018, 2018
The Polar Cap (PC) indices, PCN (North) based on magnetic data from Qaanaaq (Thule) and PCS (South) based on Vostok data, reflect the transpolar convection of plasma and magnetic fields. The PC indices could be used, among others, to indicate the energy transfer from the solar wind to the magnetosphere–ionosphere–thermosphere system in space weather monitoring applications. The present IAGA-endorsed methods to derive PC indices in real time are found to generate inconsistent index values.



Estimating ocean tide model uncertainties for electromagnetic inversion studies

Fri, 13 Apr 2018 17:31:37 +0200

Estimating ocean tide model uncertainties for electromagnetic inversion studies
Jan Saynisch, Christopher Irrgang, and Maik Thomas
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-27,2018
Manuscript under review for ANGEO (discussion: open, 0 comments)
By induction, ocean tides generate electromagnetic signals. Since the launch of magnetometer satellite missions, these signals are used increasingly to infer electric properties of the Earth. In many of these inversions, ocean tide models are used to generate oceanic tidal electromagnetic signals via electromagnetic induction. The studies main goal is to provide tide model errors for the electromagnetic inversion studies.



Impact of disturbance electric fields in the evening on prereversal vertical drift and spread F developments in the equatorial ionosphere

Mon, 09 Apr 2018 17:31:37 +0200

Impact of disturbance electric fields in the evening on prereversal vertical drift and spread F developments in the equatorial ionosphere
Mangalathayil A. Abdu, Paulo A. B. Nogueira, Angela M. Santos, Jonas R. de Souza, Inez S. Batista, and Jose H. A. Sobral
Ann. Geophys., 36, 609-620, https://doi.org/10.5194/angeo-36-609-2018, 2018
Equatorial ionospheric irregularities have a significant detrimental impact on a variety of space application systems in navigation and communication areas that utilize satellites, especially the Global Navigation Satellite Systems (GNSS) network. The development of these irregularities in the nighttime ionosphere is controlled primarily by ionospheric electric fields and instabilities. The effect of magnetic disturbance on these electric fields and on the irregularities is investigated here.



An empirical model (CH-Therm-2018) of the thermospheric mass density derived from CHAMP

Fri, 06 Apr 2018 17:31:37 +0200

An empirical model (CH-Therm-2018) of the thermospheric mass density derived from CHAMP
Chao Xiong, Hermann Lühr, Michael Schmidt, Mathis Bloßfeld, and Sergei Rudenko
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-25,2018
Manuscript under review for ANGEO (discussion: open, 0 comments)
Thermospheric drag is the major non-gravitational perturbation acting on Low Earth Orbit (LEO) satellites at altitudes up to 1000 km. The drag depends on the thermospheric density, which is a key parameter in the planning of LEO missions, e.g. their lifetime, collision avoidance, precise orbit determination, as well as orbit and re-entry prediction. In this study, we present an empirical model, named CH-Therm-2018, of the thermospheric mass density derived from 9-year (from August 2000 to July 2009) accelerometer measurements at altitude from 460 to 310 km, from the CHAllenging Minisatellite Payload (CHAMP) satellite. The CHAMP dataset is divided into two 5-year periods with 1-year overlap (from August 2000 to July 2005 and from August 2004 to July 2009), to represent the high-to-moderate and moderate-to-low solar activity conditions, respectively. The CH-Therm-2018 model is a function of seven key parameters, including the height, solar flux index, season (day of year), magnetic local time, geographic latitude and longitude, as well as magnetic activity represented by the solar wind merging electric field. Predictions of the CH-Therm-2018 model agree well with the CHAMP observations (disagreements within ±20 %), and show different features of thermospheric mass density during solar activities, e.g. the March-September equinox asymmetry and the longitudinal wave pattern. We compare the CH-Therm-2018 predictions with the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended (NRLMSISE-00) model. The result shows that CH-Therm-2018 better predicts the density evolution during the last solar minimum (2008-2009) than the NRLMSISE-00 model. By comparing the Satellite Laser Ranging (SLR) observations of the ANDE-Pollux satellites during August-September 2009, we estimate 6-h scaling factors of thermospheric mass density and obtain a median value of 1.27 ± 0.60, indicating that our model, on average, slightly underestimates the thermospheric mass density at solar minimum.



On the short-term variability of turbulence and temperature in the winter mesosphere

Thu, 05 Apr 2018 17:31:37 +0200

On the short-term variability of turbulence and temperature in the winter mesosphere
Gerald A. Lehmacher, Miguel F. Larsen, Richard L. Collins, Aroh Barjatya, and Boris Strelnikov
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-30,2018
Manuscript under review for ANGEO (discussion: open, 0 comments)
We used sounding rockets to obtain 4 high-resolution profiles in the mesosphere over a limited area. We found consistent deep isothermal and adiabatic layers, but variable and finely structured turbulence preferentially in the lower stable mesosphere. Accompanying tracer releases showed horizontal winds in the lower thermosphere with extreme shears and 200 m/s winds under moderately disturbed geomagnetic conditions, and convective structures just below the mesopause.



Quantifying the relationship between the plasmapause and the inner boundary of small-scale field-aligned currents, as deduced from Swarm observations

Thu, 05 Apr 2018 17:31:37 +0200

Quantifying the relationship between the plasmapause and the inner boundary of small-scale field-aligned currents, as deduced from Swarm observations
Balázs Heilig and Hermann Lühr
Ann. Geophys., 36, 595-607, https://doi.org/10.5194/angeo-36-595-2018, 2018
This paper presents a statistical study of the equatorward boundary of small-scale field-aligned currents (SSFACs) as observed by ESA's Swarm satellites and investigates the relation between this boundary and NASA’s Van Allen probe observed plasmapause (PP). It is found that the two boundaries are closely coincident in the midnight LT sector, where the new PP is formed. Our results point to the role of SSFACs in the creation of the PP and offer a unique tool to monitor PP dynamics.



Semidiurnal solar tide differences between fall and spring transition times in the Northern Hemisphere

Tue, 03 Apr 2018 17:31:37 +0200

Semidiurnal solar tide differences between fall and spring transition times in the Northern Hemisphere
J. Federico Conte, Jorge L. Chau, Fazlul I. Laskar, Gunter Stober, Hauke Schmidt, and Peter Brown
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-29,2018
Manuscript under review for ANGEO (discussion: open, 0 comments)
Based on comparisons of meteor radar measurements with HAMMONIA model simulations, we show that the differences exhibited by the semidiurnal solar tide (S2) observed at middle and high latitudes of the Northern Hemisphere between equinox times are mainly due to distinct behaviors of the migrating semidiurnal (SW2) and the non-migrating westward propagating wave number 1 semidiurnal (SW1) tidal components.



New results on the mid-latitude midnight temperature maximum

Tue, 03 Apr 2018 17:31:37 +0200

New results on the mid-latitude midnight temperature maximum
Rafael L. A. Mesquita, John W. Meriwether, Jonathan J. Makela, Daniel J. Fisher, Brian J. Harding, Samuel C. Sanders, Fasil Tesema, and Aaron J. Ridley
Ann. Geophys., 36, 541-553, https://doi.org/10.5194/angeo-36-541-2018, 2018
The midnight temperature maximum (MTM) is a phenomenon resulting from the constructive interference of the atmospheric tides. This paper brings the analysis of a long data set (846 nights) from the NATION network along with new analysis techniques (harmonic background removal and 2-D temperature interpolation) to detect the MTM in the mid-latitude range.



Effects of solar activity and galactic cosmic ray cycles on the modulation of the annual average temperature at two sites in southern Brazil

Tue, 03 Apr 2018 17:31:37 +0200

Effects of solar activity and galactic cosmic ray cycles on the modulation of the annual average temperature at two sites in southern Brazil
Everton Frigo, Francesco Antonelli, Djeniffer S. S. da Silva, Pedro C. M. Lima, Igor I. G. Pacca, and José V. Bageston
Ann. Geophys., 36, 555-564, https://doi.org/10.5194/angeo-36-555-2018, 2018
Quasi-periodic variations in solar activity and galactic cosmic rays (GCRs) on decadal and bidecadal timescales have been suggested as a climate forcing mechanism for many regions on Earth. One of these regions is southern Brazil, where the lowest values during the last century were observed for the total geomagnetic field intensity at the Earth's surface. These low values are due to the passage of the center of the South Atlantic Magnetic Anomaly (SAMA), which crosses the Brazilian territory from east to west following a latitude of ∼ 26°. In areas with low geomagnetic intensity, such as the SAMA, the incidence of GCRs is increased. Consequently, possible climatic effects related to the GCRs tend to be maximized in this region. In this work, we investigate the relationship between the ∼ 11-year and  ∼ 22-year cycles that are related to solar activity and GCRs and the annual average temperature recorded between 1936 and 2014 at two weather stations, both located near a latitude of 26° S but at different longitudes. The first of these stations (Torres – TOR) is located in the coastal region, and the other (Iraí – IRA) is located in the interior, around 450 km from the Atlantic Ocean. Sunspot data and the solar modulation potential for cosmic rays were used as proxies for the solar activity and the GCRs, respectively. Our investigation of the influence of decadal and bidecadal cycles in temperature data was carried out using the wavelet transform coherence (WTC) spectrum. The results indicate that periodicities of 11 years may have continuously modulated the climate at TOR via a nonlinear mechanism, while at IRA, the effects of this 11-year modulation period were intermittent. Four temperature maxima, separated by around 20 years, were detected in the same years at both weather stations. These temperature maxima are almost coincident with the maxima of the odd solar cycles. Furthermore, these maxima occur after transitions from even to odd solar cycles, that is, after some years of intense GCR flux. The obtained results offer indirect mathematical evidence that solar activity and GCR variations contributed to climatic changes in southern Brazil during the last century. A comparison of the results obtained for the two weather stations indicates that the SAMA also contributes indirectly to these temperature variations. The contribution of other mechanisms also related to solar activity cannot be excluded.



Climatology of the scintillation onset over southern Brazil

Tue, 03 Apr 2018 17:31:37 +0200

Climatology of the scintillation onset over southern Brazil
Jonas Sousasantos, Alison de Oliveira Moraes, José H. A. Sobral, Marcio T. A. H. Muella, Eurico R. de Paula, and Rafael S. Paolini
Ann. Geophys., 36, 565-576, https://doi.org/10.5194/angeo-36-565-2018, 2018
This work presents an analysis of the scintillation onset over the southern Brazil based on data from two solar maximum periods and simulation of the ionospheric conditions before the scintillation onset. The results shows some patterns which may help to prevent several satellite-based technological applications suffering disruptions due to scintillation issues.



High-resolution vertical velocities and their power spectrum observed with the MAARSY radar – Part 1: frequency spectrum

Tue, 03 Apr 2018 17:31:37 +0200

High-resolution vertical velocities and their power spectrum observed with the MAARSY radar – Part 1: frequency spectrum
Qiang Li, Markus Rapp, Gunter Stober, and Ralph Latteck
Ann. Geophys., 36, 577-586, https://doi.org/10.5194/angeo-36-577-2018, 2018
With the powerful MAARSY radar, we detected 3D wind fields and the vertical winds show a non-Gaussian distribution. We further obtained the frequency spectrum of vertical wind. The distribution of the spectral slopes under different wind conditions is derived and their comparisons with the background horizontal winds show that the spectra become steeper with increasing wind velocities under quiet conditions, approach a slope of −5/3 at 10 m/s and then maintain this slope for even stronger winds.



Study of sporadic E layers based on GPS radio occultation measurements and digisonde data over the Brazilian region

Tue, 03 Apr 2018 17:31:37 +0200

Study of sporadic E layers based on GPS radio occultation measurements and digisonde data over the Brazilian region
Laysa C. A. Resende, Christina Arras, Inez S. Batista, Clezio M. Denardini, Thainá O. Bertollotto, and Juliano Moro
Ann. Geophys., 36, 587-593, https://doi.org/10.5194/angeo-36-587-2018, 2018
We present new results on the behavior of sporadic E layers (Es layers) using GPS (global positioning system) radio occultation (RO) measurements obtained from the FORMOSAT-3/COSMIC satellites and digisonde data over Cachoeira Paulista, a low-latitude station in Brazil.



The effect of subauroral polarization streams on the mid-latitude thermospheric disturbance neutral winds: a universal time effect

Thu, 29 Mar 2018 17:31:37 +0200

The effect of subauroral polarization streams on the mid-latitude thermospheric disturbance neutral winds: a universal time effect
Hui Wang, Kedeng Zhang, Zhichao Zheng, and Aaron James Ridley
Ann. Geophys., 36, 509-525, https://doi.org/10.5194/angeo-36-509-2018, 2018
For subauroral polarization streams (SAPS) commencing at different universal times (UT), the strongest westward neutral winds exhibit large variations in amplitudes. The effect of a sine-wave oscillation of SAPS on the neutral wind also exhibits UT variations in association with the solar illumination. The reduction in the electron density and enhancement in the air mass density are strongest when the maximum solar illumination collocates with the SAPS.



GREEN: A new Global Radiation Earth ENvironment model

Thu, 29 Mar 2018 17:31:37 +0200

GREEN: A new Global Radiation Earth ENvironment model
Angélica Sicard, Daniel Boscher, Sébastien Bourdarie, Didier Lazaro, Denis Standarovski, and Robert Ecoffet
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-26,2018
Manuscript under review for ANGEO (discussion: open, 0 comments)
GREEN (Global Radiation Earth ENvironment) is a new model providing particles fluxes at any location in the radiaiton belts, for energy between 1 keV to 10 MeV for electrons and between 1 keV and 800 MeV for protons. This model is composed of global models: AE8/AP8 and SPM and local models: SLOT model, OZONE, IGE-2006 for electrons and OPAL and geostationary model for protons.



Three-dimensional density and compressible magnetic structure in solar wind turbulence

Thu, 29 Mar 2018 17:31:37 +0200

Three-dimensional density and compressible magnetic structure in solar wind turbulence
Owen W. Roberts, Yasuhito Narita, and C.-Philippe Escoubet
Ann. Geophys., 36, 527-539, https://doi.org/10.5194/angeo-36-527-2018, 2018
In this study we use multi-point spacecraft measurements of magnetic field and electron density derived from spacecraft potential to investigate the three-dimensional structure of solar wind plasma turbulence. We see that there is a dependence on the plasma beta (ratio of thermal to magnetic pressure) as well as a dependence on the type of wind i.e. fast or slow.



Ionospheric and thermospheric response to the 27–28 February 2014 geomagnetic storm

Wed, 28 Mar 2018 17:31:37 +0200

Ionospheric and thermospheric response to the 27–28 February 2014 geomagnetic storm
Khalifa Malki, Aziza Bounhir, Zouhair Benkhaldoun, Jonathan J. Makela, Nicole Vilmer, Daniel J. Fisher, Mohamed Kaab, Khaoula Elbouyahyaoui, Brian J. Harding, Amine Laghriyeb, Ahmed Daassou, and Mohamed Lazrek
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-24,2018
Manuscript under review for ANGEO (discussion: open, 1 comment)
The novelty of this paper resides in the fact that it addresses the termosphere/ionosphere coupling in a mid-latitude site in north Africa. We have used Fabry-Perot measurements of the thermospheric winds and wide-angle camera detection of ionospheric structurers, at an altitude of about 250 km. We have also used GPS data to extract the TEC over the studied area. We have focused our study on the 27 Feb geomagnetic storm.