Journal of Atmospheric and Solar-Terrestrial Physics

Spatial interpolation of meteorological fields using a multilevel parametric dynamic stochastic low-order model

Fri, 11/23/2018 - 19:10

Publication date: December 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 181, Part A

Author(s): A.V. Lavrinenko, E.A. Moldovanova, D.F. Mymrina, A.I. Popova, K.Y. Popova, Y.B. Popov

Abstract

The paper focuses on a new method of spatial interpolation of air temperature and wind velocity fields in the troposphere. The method is based on Kalman filtering and a multilevel parametric dynamic stochastic low-order model. The key feature of the proposed model is that it has parameters, which are responsible for the altitude levels. Generally, models use so-called “shallow water” (shallow water approximation), and altitude correlation is not taken into account, or they may rely only on mandatory isobaric levels data, thus ignoring the data obtained for significant levels. Standard levels are located at considerable distances in altitude from each other and the altitude correlation there is not usually significant. By using parameters that are responsible for the altitude levels, this model allows us to estimate the effect that information coming from neighbouring altitude levels may have on the final estimate. The paper presents the results of a statistical estimation of the proposed spatial interpolation algorithm. A comparison of the results statistical estimation spatial interpolation of the proposed algorithm with a four-dimensional dynamic-stochastic model is given.

Validation of NeQuick 2 model over West African equatorial region using GNSS-derived Total Electron Content data

Fri, 11/23/2018 - 19:10

Publication date: December 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 181, Part A

Author(s): J.N. Yao, B. Nava, O.K. Obrou, S.M. Radicella

Abstract

The NeQuick 2 has been implemented as a climatological model with the goal to represent the typical median conditions of the ionosphere. Several investigations have been made to test its performances at global and regional scale. In order to provide a 3D specification of the electron density of the ionosphere at a given geographic location and time, specific data ingestion techniques, based on NeQuick 2 adaptation to Total Electron Content (TEC) data, have been introduced. In the present work, the performance of the NeQuick 2 model for climate prediction of TEC has been evaluated in the west African equatorial region. Several types of solar indexes such as the smoothed monthly mean sunspot number (R12), the daily solar radio flux at 10.7 cm wavelengths (F10.7) and the daily sunspot number (Rz) have been used as input parameters for the model. The monthly medians of the modeled vertical TEC (vTEC) have been compared to the corresponding monthly medians of the vTEC obtained from two Global Navigation Satellite System (GNSS) stations located in Côte d'Ivoire. Furthermore, to assess the “weather-like” capabilities of the model, a data ingestion technique has been implemented through the computation of an effective parameter Az at a single GNSS station in Côte d'Ivoire (Yamoussoukro). For geomagnetically disturbed and quiet days, this Az parameter has been used as input for NeQuick to estimate the vertical TEC values in another station (Abidjan) located at about 200 km from the previous one. Additional tests based on the evaluation of Az at the station of Cotonou in Benin allowed analysing the model capability of reconstructing TEC at different distances (up to 850 km from the reference station) according to the north-south and east-west directions of displacement. The statistical analysis has been based on relative frequencies distribution of the difference between reconstructed and the corresponding observed TEC.

Variability of the Sun and Its Terrestrial Impacts

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): Katya Georgieva, Kazuo Shiokawa

Editorial Board

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s):

Current sheets in corona and X-ray sources for flares above the active region 10365

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): A.I. Podgorny, I.M. Podgorny, N.S. Meshalkina

Abstract

The coincidence of current sheets positions obtained from results of numerical MHD simulation for flares May 27, 2003 at 02:53 UT and May 29, 2003 at 00:51 UT with positions of observed X-ray sources confirm the mechanism of solar flare according to which the magnetic energy of the current sheet is released in corona above an active region. To study the magnetic field configuration obtained from 3D MHD simulation, the system of graphic presentation is developed. Magnetic field lines in 3D space have a complex configuration near a current sheet above the active region which can be investigated using the developed system of visualization. The physical meaning of the processes in the current sheet is best demonstrated by the lines in the plane of the current sheet configuration which are tangential to the projections of the magnetic field vectors on this plane. Position of such lines defines the magnetic forces, which create the current sheet and then destroy it, when the system turns into an unstable state. Analysis of magnetic lines in large area above the active region allows make a preliminary conclusion about existence of the magnetic lines that connect the hard X-ray sources and the current sheet.

Statistic study of the geoeffectiveness of compression regions CIRs and Sheaths

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): Yu I. Yermolaev, I.G. Lodkina, N.S. Nikolaeva, M.Yu Yermolaev, M.O. Riazantseva, L.S. Rakhmanova

Abstract

We statistically study the geoeffectiveness of two types of compression regions: corotating interaction regions (CIRs) before the solar wind high-speed streams (HSSs) from the coronal holes and Sheaths before the fast interplanetary CMEs (ICMEs) including flux-rope magnetic clouds (MCs) and non-MC Ejecta using the OMNI dataset (http://omniweb.gsfc.nasa.gov (King and Papitashvili, 2004)) and our Catalog of large-scale solar wind phenomena for 1976–2000 (ftp://ftp.iki.rssi.ru/pub/omni/(Yermolaev et al., 2009)). Our analysis shows that the magnitude of the interplanetary magnetic field B in CIRs and Sheaths increases with increasing speed of both types of pistons: HSS and ICME; the increase of the piston speed results in the increase of geoeffectiveness of both compression regions. The value B in Sheaths before Ejecta is higher than B in Ejecta. The value B in Sheaths before MCs in the beginning of phenomena interval is lower than in MCs but in the end of interval it is close to B in MCs. The contribution of Sheath in storm generation can be significant for so-called "CME-induced" storms and Sheath-induced storms should be identified and analyzed separately.

Disturbances of the thermosphere-ionosphere-plasmasphere system and auroral electrojet at 30°E longitude during the St. Patrick's Day geomagnetic storm on 17–23 March 2015

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): M.V. Klimenko, V.V. Klimenko, I.V. Despirak, I.E. Zakharenkova, B.V. Kozelov, S.M. Cherniakov, E.S. Andreeva, E.D. Tereshchenko, A.M. Vesnin, N.A. Korenkova, A.D. Gomonov, E.B. Vasiliev, K.G. Ratovsky

Abstract

This study presents an analysis of geomagnetic disturbances and ionospheric electron density distribution during the 2015 St. Patrick's Day geomagnetic storm. To study those we have used the satellite-borne and ground-based observations. The St. Patrick's geomagnetic storm covers the interval of 15–23 March 2015, when solar eruptive phenomena (a long-enduring C9-class solar flare and associated CME's on 15 March) and a strong geomagnetic storm on 16–18 March (Dst dropped as strong as –228 nT) were reported. This geomagnetic storm is still the strongest one observed in the current solar cycle. The severe geomagnetic storm on 17-18 March 2015 led to complex effects on the ionosphere. We consider major features of the positive and negative ionospheric storms development at European mid- and high-latitudes. One of the interesting phenomena was observation of the positive ionospheric disturbances during the recovery phase. Using the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) we examined the main physical processes that played a major role in dramatic changes of the total electron content and the F2 layer peak electron density during this storm event.

Response of the total ozone to energetic electron precipitation events

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): Arseniy Karagodin, Irina Mironova, Anton Artamonov, Natalia Konstantinova

Abstract

In this paper we investigate response of the total ozone column to energetic electron precipitation (EEP) observed by bremsstrahlung effect. The list of EEP events was prepared by members of the balloon experiments of the Lebedev Physical Institute. Here we used superposed epoch analysis and the days with EEP events are registered during winter (November–February) and summer (June–August) months from 1970 to 2012 were chosen as key dates. This period corresponds approximately to three solar cycles. Data of the total ozone column were collected by single coherent total ozone dataset, called the Multi Sensor Reanalysis (MSR). A long series of data of the total ozone column is allowed us to study the response of ozone content to 90 winter and 103 summer EEP events. The obtained ozone sensitivity to the events of energetic electron precipitation is clearly pronounced during local winters in the high latitudes of the Northern and Southern Hemispheres (60–80 NH and 60–80 SH). In the high latitudes of the Northern Hemisphere, during winter months, the total ozone content can be reduced by up to 10 DU after energetic electron precipitation with minimum observed on the first day after EEP events. Response of the total ozone, over high latitudes of the Northern Hemisphere, to EEP events can be opposite during summer months.

Proton acceleration in the solar flare

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): I.M. Podgorny, A.I. Podgorny

Abstract

Hundred years of cosmic ray investigations have not lead to the ultimate understanding the mechanisms of particle acceleration. Most popular theoretical mechanisms of solar comic ray generation are associated with shock waves. The discovery of sources of protons with relativistic energies, generated by the Sun (solar cosmic ray), gives us hope for the opportunity to clarify the mechanism of cosmic rays generation. The important information about the mechanism of proton acceleration in the Sun has been obtained from results by GOES of measurements. The association of a proton event with a particular flare is beyond doubt. The GOES measurements indicate propagation of the high-energy protons front without collisions from the flares that appeared on the western part of the solar disk. These protons can move along the helical magnetic field lines to the Earth. The protons from flares on the back side of the Sun can also come to the Earth's magnetosphere along magnetic lines. Protons from eastern part of the solar disk can come to the GOES across the magnetic lines. The front of the proton flux from eastern flares comes to Earth with a delay of several hours. The series of 2–3 weeks long proton events produced by several proton flares are observed one - two times in the 11 year cycle of solar activity. Nature of a trigger for initiating such series of proton events is not clear.

Graphical abstract

The ionosphere response to severe geomagnetic storm in March 2015 on the base of the data from Eurasian high-middle latitudes ionosonde chain

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): B.G. Shpynev, N.A. Zolotukhina, N.M. Polekh, K.G. Ratovsky, M.A. Chernigovskaya, A.Yu. Belinskaya, A.E. Stepanov, V.V. Bychkov, S.A. Grigorieva, V.A. Panchenko, N.A. Korenkova, J. Mielich

Abstract

In the paper we study the ionosphere response to the March 2015 severe geomagnetic storm according to Eurasian high-middle latitude ionosonde chain. On the basis of the ionosonde chain data we have restored the time/longitude dynamics of the high-middle latitude ionosphere over the Eurasian continent. The data showed that during the main storm phase that developed in the nighttime Siberian sector, a disturbed thermosphere region was created. This region moved westward with 50–70 m/s velocity and which was registered two-three days after the storm in the Eastern and Western Europe. Characteristics of the geomagnetic field variations showed that three active zones occurred during the storm. One is shifted from the geographic pole toward magnetic pole at ∼270° longitude. Two other zones were formed symmetrically opposite to the geomagnetic pole at longitudes ∼40° and ∼130°; the major electron density depletions at these longitudes were observed in the high-middle latitude ionosphere. On the contrary, longitudinal sector ∼80–110° showed electron density maximum in quiet conditions and fast ionosphere restoration after the storm decaying.

<em>PC</em> index as a proxy of the solar wind energy that entered into the magnetosphere: 3. Development of magnetic storms

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): O.A. Troshichev, D.A. Sormakov

Abstract

Relationships between the 30-min smoothed PC and SymH indices in course of 430 magnetic storms observed in period of 1998–2015 have been examined. The storms were classified, by features of the PC evolution, as classic, pulsed and composite magnetic storms. It is shown these storm types are related, correspondingly, to such solar drivers as Interplanetary Coronal Mass Ejections (ICME), Stream Interaction Regions (SIR), and their joint action. Results of the statistical analysis demonstrate that depression of geomagnetic field (“Dst variation”) starts to develop as soon as PC index steadily excess the threshold level ∼1.5 mV/m, like to case of magnetic substorms. SymH index in course of magnetic storms (during 48 h preceding and succeeding the maximal depression of geomagnetic field) generally follows the time evolution of the PC index with typical delay time of ΔT ∼ 1 ± 0.5 h. The storm intensity (SymHMIN) is linearly related to maximal value of the foregoing PC index (PCMAX) observed ∼0.5÷2 h before the moment of maximal depression. The conclusion is made that the PC index can be successfully used for nowcasting the magnetic storm development.

Hurricane genesis modelling based on the relationship between solar activity and hurricanes II

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): Yaroslav Vyklyuk, Milan M. Radovanović, Gorica B. Stanojević, Boško Milovanović, Taras Leko, Milan Milenković, Marko Petrović, Anatoly A. Yamashkin, Ana Milanović Pešić, Dejana Jakovljević, Slavica Malinović Milićević

Abstract

This research presents improved results on modelling relationship between the flow of charged particles that are coming from the Sun and hurricanes. For establishing eventual link, the methods of Big Data, such as Adaptive Neuro Fuzzy Inference System (ANFIS), Parallel Calculations, Fractal analysis etc., are applied. The parameters of solar activity were used as model input data, while data on hurricane phenomenon were used as model output, and both of these on daily level for May–October in period 1999–2013. The nonlinear R/S analysis was conducted to determine the degree of randomness for time series of input and output parameters. The time lag of 0–10 days was taken into account in the research. It led to growing input parameters up to 99. The problem of finding hidden dependencies in large databases refers to the problems of Data Mining. The ANFIS with Sugeno function of zero order was selected as a method of output fuzzy system. The “brute-force attack” method was used to find the most significant factors from all data. To do this, more than 3 million ANFIS models were tested on Computer Cluster using Parallel Calculation. Within the experiments, eight input factors were calculated as a base for building the final ANFIS models. These models can predict up to 39% of the hurricanes. This means, if causal link exists, approximately every third penetration of charged particles from coronary hole(s) or/and from the energetic region(s) toward the Earth precede the hurricanes.

Effects of the 2016 February minor sudden stratospheric warming on the MLT and ionosphere over Eastern Siberia

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): Irina Medvedeva, Konstantin Ratovsky

Abstract

We present the results of studying the behavior of parameters of the mesosphere and lower thermosphere (MLT) and the ionosphere over the Eastern Siberia region during a minor winter sudden stratospheric warming (SSW) in early February 2016. We used the data from spectrometric measurements of OH ((6-2), 834.0 nm, ∼87 km) and O2 At ((0–1), 864.5 nm, ∼94 km), emissions from the Geophysical Observatory at the Institute of Solar-Terrestrial Physics of the Siberian Branch of the Russian Academy of Sciences (51.8°N, 103.1°E, Tory). These emissions originate at the MLT heights. We also used the vertical sounding data on the peak electron density (NmF2), and on the peak height (hmF2). These data were obtained with the DPS-4 Irkutsk ionosonde (52.3°N, 104.3°E). For the analysis, we also involved the MLS Aura satellite data of measuring vertical temperature profiles and the MERRA reanalysis data.

We found the MLT and ionospheric signatures for the 2016 February SSW. At the MLT heights, the OH and O2 emissions intensities increased by a factor of ∼2 and ∼3, respectively, and the temperature fell by ∼20 K. Analyzing the mesopause temperature variability and comparing the mean seasonal values showed an essential increase in the wave activity at the MLT. At the F2-region ionospheric heights, we revealed significant (up to ∼80%) NmF2 positive disturbances in the postmidnight hours and an essential increase (up to ∼ 2 times relative to root-mean-square values) in the amplitudes of the tidal component of the NmF2 disturbance. The results of the study show that a minor SSW may significantly impact the state of the MLT and the ionosphere at midlatitudes.

Onset mechanism of solar eruptions

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): Satoshi Inoue, Yumi Bamba, Kanya Kusano

Abstract

Solar eruptions are the most energetic phenomena observed in the solar system observed as flares, coronal mass ejections (CMEs) and filament/prominence eruption. The helically twisted flux tube is widely thought to be the source and driver of solar eruptions and to carry the plasma into the interplanetary space. Those may eventually reach the magnetosphere and cause strong disturbances of the geomagnetic field. Therefore, the understanding of the onset of solar eruptions is important not only in the framework of solar physics but also for the space weather forecast. In this paper, we report on new insight into the onset mechanism of solar eruptions recently obtained from our new studies. We perform the studies in terms of the observational approach with state-of-the-art solar physics satellites and the numerical one with the latest super computer system. We specified two types of small magnetic perturbations of the photospheric magnetic field. These can enhance the magnetic reconnection in the pre-existing non-potential magnetic field, which produces a large flux tube and then drives the eruption. We further confirmed that this reconnection is a key process for the eruption in our latest data-constrained simulation. We report our latest results and our interpretation of the onset mechanism of solar eruptions.

The induced surface electric response in Europe to 2015 St. Patrick's Day geomagnetic storm

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): C. Demetrescu, V. Dobrica, R. Greculeasa, C. Stefan

Abstract

The largest geomagnetic storm in solar cycle 24 is investigated from the dual perspective of (1) solar source – solar wind – geomagnetic storm chain and (2) the hazardous induced response as shown by the surface electric field. The study is based on heliospheric magnetic field and solar wind data, on one hand, and on recorded 1-min geomagnetic data from the INTERMAGNET network of European geomagnetic observatories, on the other. The lateral distribution of the induced electric response for the European continent during the considered storm is shown, and the timing of the maximum induced horizontal geoelectric vector is discussed in terms of specific moments of the storm development.

Ionospheric response to winter stratosphere/lower mesosphere jet stream in the Northern Hemisphere as derived from vertical radio sounding data

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): M.A. Chernigovskaya, B.G. Shpynev, K.G. Ratovsky, A.Yu. Belinskaya, A.E. Stepanov, V.V. Bychkov, S.A. Grigorieva, V.A. Panchenko, N.A. Korenkova, J. Mielich

Abstract

We study the effects of the middle atmosphere dynamics on the mid-latitude and subauroral ionosphere during the winter jet stream that occurred at the stratosphere/lower mesosphere heights in the Northern Hemisphere over 2008–2013. The used ionospheric data were obtained from measurements taken at the vertical sounding ionosonde chain covering the entire Eurasian continent. We reveal regional features of the F2-layer ionospheric response to dynamic processes during the winter circumpolar vortex evolution in the strato-mesosphere. The variations in the ionospheric parameters observed at different longitudes in the Northern Hemisphere significantly depended on the ionosonde position relative to the jet stream zone in the strato-mesosphere. The difference in critical frequency values for the ionosondes spaced longitudinally by only 15–20° could reach about 1.5–2 MHz, depending on the observation point location under the jet stream or off the latter. We consider the molecular gas upwelling/downwelling to/from the lower thermosphere in active regions of circulation as a mechanism for the underlying atmosphere impact on the ionosphere. Irregular variations in the ionospheric parameters could also be caused by wave disturbances of various spatial and temporal scales (including internal gravity waves) propagating into the thermosphere from the underlying atmosphere. The mesoscale wave generation source at the strato-mesospheric heights was associated with baroclinic instabilities in the spatially non-uniform, high-velocity winter jet stream.

IMF-driven change to the Antarctic tropospheric temperature due to the global atmospheric electric circuit

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): Mai Mai Lam, Mervyn P. Freeman, Gareth Chisham

Abstract

We use National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis data to investigate the Antarctic mean tropospheric temperature anomaly associated with changes in the dawn-dusk component By of the interplanetary magnetic field (IMF). We find that the mean tropospheric temperature anomaly for geographical latitudes ≤ −70° peaks at about 0.7 K and is statistically significant at the 5% level between air pressures of 1 000 and 500 hPa (∼0.1–5.6 km altitude above sea level) and for time lags with respect to the IMF of up to 7 days. The peak values of the air temperature anomaly occur at a greater time lag at 500 hPa (∼5.6 km) than at 1 000 - 600 hPa (∼0.1–4.2 km), which may indicate that the signature propagates vertically. The characteristics of prompt response and possible vertical propagation within the troposphere have previously been seen in the correlation between the IMF and high-latitude air pressure anomalies, known as the Mansurov effect, at higher statistical significances (1%). For time lags between the IMF and the troposphere of 0–6 days and altitudes between 1 000 and 700 hPa (∼0.1–3 km), the relationship between highly statistically significant (1% level) geopotential height anomaly values and the corresponding air temperature anomaly values is consistent with the standard lapse rate in atmospheric temperature. We conclude that we have identified the temperature signature of the Mansurov effect in the Antarctic troposphere. Since these tropospheric anomalies have been associated with By-driven anomalies in the electric potential of the ionosphere, we further conclude that they are caused by IMF-induced changes to the global atmospheric electric circuit (GEC). Our results support the view that variations in the ionospheric potential act on the troposphere, possibly via the action of consequent variations in the downwards current of the GEC on tropospheric clouds.

Extreme solar storms based on solar magnetic field

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): Brigitte Schmieder

Abstract

Many questions have to be answered before understanding the relationship between the emerging magnetic flux through the solar surface and the extreme geoeffective events. Which threshold determines the onset of the eruption? What is the upper limit in energy for a flare? Is the size of sunspot the only criteria to get extreme solar events?

Based on observations of previous solar cycles, and theory, the main ingredients for getting X ray class flares and large Interplanetary Corona Mass Ejections e.g. the built up of the electric current in the corona, are presented such as the existence of magnetic free energy, magnetic helicity, twist and stress in active regions. The upper limit of solar flare energy in space research era and the possible chances to get super-flares and extreme solar events can be predicted using MHD simulation of coronal mass ejections.

Coronal flux ropes and their interplanetary counterparts

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): N. Gopalswamy, S. Akiyama, S. Yashiro, H. Xie

Abstract

We report on a study comparing coronal flux ropes inferred from eruption data with their interplanetary counterparts constructed from in situ data. The eruption data include the source-region magnetic field, post-eruption arcades, and coronal mass ejections (CMEs). Flux ropes were fit to the interplanetary CMEs (ICMEs) considered for the 2011 and 2012 Coordinated Data Analysis Workshops (CDAWs). We computed the total reconnected flux involved in each of the associated solar eruptions and found it to be closely related to flare properties, CME kinematics, and ICME properties. By fitting flux ropes to the white-light coronagraph data, we obtained the geometric properties of the flux ropes and added magnetic properties derived from the reconnected flux. We found that the CME magnetic field in the corona is significantly higher than the ambient magnetic field at a given heliocentric distance. The radial dependence of the flux-rope magnetic field strength is faster than that of the ambient magnetic field. The magnetic field strength of the coronal flux ropes is also correlated with that in interplanetary flux ropes constructed from in situ data, and with the observed peak magnetic field strength in ICMEs. The physical reason for the observed correlation between the peak field strength in ICMEs is the higher magnetic field content in faster coronal flux ropes and ultimately the higher reconnected flux in the eruption region. The magnetic flux ropes constructed from the eruption data and coronagraph observations provide a realistic input that can be used by various models to predict the magnetic properties of ICMEs at Earth and other destination in the heliosphere.

Inferring geoeffective solar variability signature in stratospheric and tropospheric Northern Hemisphere temperatures

Sat, 11/17/2018 - 19:10

Publication date: November 2018

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 180

Author(s): V. Dobrica, R. Pirloaga, C. Stefan, C. Demetrescu

Abstract

Possible climatic effects related to geoeffective solar variability have been investigated by means of long-term statistical correlations between stratospheric and tropospheric temperature and solar/geomagnetic indices. Our previous work on solar variability signature in the long records of air temperature in Europe showed that there were significant solar signals at Schwabe (11 years) and Hale (22 years) solar cycles, with peak to trough amplitudes of several degrees, and, respectively, of 0.6–0.8 °C. In the present study we extend the investigation using NCEP/NCAR reanalyzed data for the temperate climate zone of the Northern Hemisphere (35–65ºN), from Earth's surface to stratospheric levels. Features of these signals are discussed on various spatial scales of the Northern Hemisphere and at specific levels in troposphere and stratosphere. The long-term statistical correlation between reanalyzed temperatures and indices describing solar variability (R, aa) is also investigated.

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