Short-term periodic features observed in the infrared cooling of the thermosphere and in solar and geomagnetic indexes from 2002 to 2009

We report derivations of short-term periodic features observed in time series of the radiative cooling of the Earth’s thermosphere. In particular, we diagnose observations of the infrared emission from nitric oxide (NO) at 5.3 μm to reveal periodicities equal to the solar rotation period (27 days) and its next three harmonics. From 2002 to 2009 we observe 27 day, 13.5 day, 9 day and (occasionally) 6.75 day periods in the thermospheric NO cooling, the solar wind speed and the K p geomagnetic index. Periodic features shorter than 27 days are absent in the time series of the 10.7 cm radio flux (F10.7) over this same time period. The periodic features in the NO cooling are found to occur throughout the depth of the thermosphere and are strongest at high latitudes. These results confirm the persistent coupling between the solar corona, the solar wind and the energy budget of the thermosphere.

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The 30 cm radio flux as a solar proxy for thermosphere density modelling

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2017008 ◽

2017 ◽

Vol 7 ◽

pp. A9 ◽

Cited By ~ 8

Author(s):

Thierry Dudok de Wit ◽

Sean Bruinsma

Keyword(s):

Solar Rotation ◽

Rotation Period ◽

Density Variation ◽

Temperature Model ◽

Radio Flux ◽

Model Bias ◽

Solar Forcing ◽

Radio Emissions ◽

Solar Uv ◽

Density Modelling

The 10.7 cm radio flux (F10.7) is widely used as a proxy for solar UV forcing of the upper atmosphere. However, radio emissions at other centimetric wavelengths have been routinely monitored since the 1950 s, thereby offering prospects for building proxies that may be better tailored to space weather needs. Here we advocate the 30 cm flux (F30) as a proxy that is more sensitive than F10.7 to longer wavelengths in the UV and show that it improves the response of the thermospheric density to solar forcing, as modelled with DTM (Drag Temperature Model). In particular, the model bias drops on average by 0–20% when replacing F10.7 by F30; it is also more stable (the standard deviation of the bias is 15–40% smaller) and the density variation at the the solar rotation period is reproduced with a 35–50% smaller error. We compare F30 to other solar proxies and discuss its assets and limitations.

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Prediction of the Dst Geomagnetic Index Using Adaptive Methods

Meteorologiya i Gidrologiya ◽

10.52002/0130-2906-2021-3-38-46 ◽

2021 ◽

Vol 3 ◽

pp. 38-46

Author(s):

I. N. Myagkova ◽

◽

V. R. Shirokii ◽

R. D. Vladimirov ◽

O. G. Barinov ◽

...

Keyword(s):

Magnetic Field ◽

Neural Networks ◽

Time Series ◽

Solar Wind ◽

Artificial Neural Networks ◽

Adaptive Methods ◽

Gradient Boosting ◽

Multilayer Perceptrons ◽

Lagrange Point ◽

Geomagnetic Index

The potential is investigated of predicting the time series of the Dst geomagnetic index using various adaptive methods: artificial neural networks (classical multilayer perceptrons), decision trees (random forest), gradient boosting. The prediction is based on the parameters of the solar wind and interplanetary magnetic field measured at the Lagrange point L1 in the ACE spacecraft experiment. It is shown that the best prediction skill of the three adaptive methods is demonstrated by gradient boosting.

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Formation of current sheets and plasmoids within corotating/stream interaction regions

10.5194/egusphere-egu2020-2102 ◽

2020 ◽

Author(s):

Timofey Sagitov ◽

Roman Kislov

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Coronal Hole ◽

High Speed ◽

Solar Rotation ◽

Coronal Holes ◽

Rotation Period ◽

The Sun ◽

Current Sheets ◽

Interaction Regions

High speed streams originating from coronal holes are long-lived plasma structures that form corotating interaction regions (CIRs) or stream interface regions (SIRs) in the solar wind. The term CIR is used for streams existing for at least one solar rotation period, and the SIR stands for streams with a shorter lifetime. Since the plasma flows from coronal holes quasi-continuously, CIRs/SIRs simultaneously expand and rotate around the Sun, approximately following the Parker spiral shape up to the Earth&#8217;s orbit.Coronal hole streams rotate not only around the Sun but also around their own axis of simmetry, resembling a screw. This effect may occur because of the following mechanisms: (1) the existence of a difference between the solar wind speed at different sides of the stream, (2) twisting of the magnetic field frozen into the plasma, and&#160; (3) a vortex-like motion of the edge of the mothering coronal hole at the Sun. The screw type of the rotation of a CIR/SIR can lead to centrifugal instability if CIR/SIR inner layers have a larger angular velocity than the outer. Furthermore, the rotational plasma movement and the stream distortion can twist magnetic field lines. The latter contributes to the pinch effect in accordance with a well-known criterion of Suydam instability (Newcomb, 1960, doi: 10.1016/0003-4916(60)90023-3). Owing to the presence of a cylindrical current sheet at the boundary of a coronal hole, conditions for tearing instability can also appear at the CIR/SIR boundary. Regardless of their geometry, large scale current sheets are subject to various instabilities generating plasmoids. Altogether, these effects can lead to the formation of a turbulent region within CIRs/SIRs, making them filled with current sheets and plasmoids.&#160;We study a substructure of CIRs/SIRs, characteristics of their rotation in the solar wind, and give qualitative estimations of possible mechanisms which lead to splitting of the leading edge a coronal hole flow and consequent formation of current sheets within CIRs/SIRs.

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Selective acceleration of O+ by drift-bounce resonance in the Earth’s magnetosphere: MMS observations

10.5194/egusphere-egu2020-2832 ◽

2020 ◽

Author(s):

Satoshi Oimatsu ◽

Masahito Nosé ◽

Guan Le ◽

Stephan A Fuselier ◽

Robert E Ergun ◽

...

Keyword(s):

Solar Wind ◽

High Speed ◽

Solar Wind Speed ◽

Density Ratio ◽

Flux Ratio ◽

Recovery Phase ◽

Wave Number ◽

Azimuthal Component ◽

Time Period ◽

Speed Solar Wind

We studied O+drift-bounce resonance using Magnetospheric Multiscale (MMS) data. A case study of an event on 17 February 2016 shows that O+&#160;flux oscillations at ~10&#8211;30 keV occurred at MLT ~ 5 hr and L~ 8&#8211;9 during a storm recovery phase. These flux oscillations were accompanied by a toroidal Pc5 wave and a high-speed solar wind (~550 km/s). The azimuthal wave number (m-number) of this Pc5 wave was found to be approximately &#8211;2. The O+/H+&#160;flux ratio was enhanced at ~10&#8211;30 keV corresponding to the O+&#160;flux oscillations without any clear variations of H+&#160;fluxes, indicating the selective acceleration of O+&#160;ions by the drift-bounce resonance. A search for the similar events in the time period from September 2015 to March 2017 yielded 12 events. These events were mainly observed in the dawn to the afternoon region at L~ 7&#8211;12 when the solar wind speed is high, and all of them were simultaneously identified on the ground, indicating low m-number. Correlation analysis revealed that the O+/H+&#160;energy density ratio has the highest correlation coefficient with peak power of the electric field in the azimuthal component (Ea). This statistical result supports the selective acceleration of O+&#160;due to the N&#160;= 2 drift-bounce resonance.

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Radial Differential Rotation of Solar Corona using Radio Emissions

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slab042 ◽

2021 ◽

Author(s):

Vivek Kumar Singh ◽

Satish Chandra ◽

Sanish Thomas ◽

Som Kumar Sharma ◽

Hari Om Vats

Keyword(s):

Time Series ◽

Solar Corona ◽

Solar Rotation ◽

Rotation Period ◽

Solar Radio Emission ◽

Correlation Technique ◽

Emission Data ◽

Height Range ◽

Data Gaps ◽

Frequency Radiation

Abstract The present work is an effort to investigate possible radial variations in the solar coronal rotation by analyzing the solar radio emission data at 15 different frequencies (275-1755 MHz) for the period starting from July 1994 to May 1999. We used a time series of disk-integrated radio flux recorded daily at these frequencies through radio telescopes situated at Astronomical Observatory of the Jagellonian University in Cracow. The different frequency radiation originates from different heights in the solar corona. Existing models, indicate its origin at the height range from nearly ∼12, 000 km (for emission at 275 MHz), below up to ∼2, 400 km (for emission at 1755 MHz). There are some data gaps in the time series used for the study, so we used statistical analysis using the Lomb-Scargle Periodogram (LSP). This method has successfully estimated the periodicity present in time series even with such data gaps. The rotation period estimated through LSP shows variation in rotation period, which is compared with the earlier reported estimate using auto correlation technique. The present study indicates some similarity as well as contradiction with studies reported earlier. The radial and temporal variation in solar rotation period are presented and discussed for the whole period analyzed.

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On the Origin of ULF Magnetic Waves Before the Taiwan Chi-Chi 1999 Earthquake

Frontiers in Earth Science ◽

10.3389/feart.2021.730162 ◽

2021 ◽

Vol 9 ◽

Author(s):

Georgios Anagnostopoulos

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Interplanetary Space ◽

Solar Rotation ◽

Rotation Period ◽

Wave Activity ◽

Alfven Wave ◽

Ulf Waves ◽

Storm Activity ◽

Data Set

The ultra low frequency (ULF) electromagnetic (EM) wave activity usually recorded on Earth’s ground has been found to depend on various types of space weather. In addition ULF waves observed before an earthquake have been hypothesized to be a result of geotectonic processes. In this study we elaborate for the first time the origin of sub-ULF (<1 msec) magnetic field waves before an earthquake (Chi-Chi/Taiwan, 20.9.1999) by comparing simultaneously obtained measurements in the interplanetary space (ACE satellite) and on the Earth’s ground (Taiwan). The most striking result of our data analysis, during a period of 7 weeks, is that the detection of four groups of sub-ULF waves in Taiwan coincide in time with the quasi-periodic detection of two solar wind streams by the satellite ACE with approximately the solar rotation period (∼28 days). The high speed solar wind streams (HSSs) in the interplanetary space were accompanied by sub-ULF Alfvén wave activity, quasi-periodic southward IMF and solar wind density perturbations, which are known as triggering agents of magnetic storm activity. The four HSSs were followed by long lasting decreases in the magnetic field in Taiwan. The whole data set examined in this study strongly suggest that the subULF magnetic field waves observed in Taiwan before the Chi-Chi 1999 earthquake is a normal consequence of the incident of HSSs to the magnetosphere. We provide some observational evidence that the sub-ULF electromagnetic radiation on the Earth was most probably a partner to (not a result of) geotectonic processes preparing the Taiwan 1999 earthquake.

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Investigation of the coronal heating through phase relation of solar activity indexes

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2019.43 ◽

2020 ◽

Vol 37 ◽

Cited By ~ 1

Author(s):

K. J. Li ◽

J. C. Xu ◽

Z. Q. Yin ◽

J. L. Xie ◽

W. Feng

Keyword(s):

Solar Wind ◽

Solar Activity ◽

Phase Relation ◽

Large Scale ◽

Solar Rotation ◽

Rotation Period ◽

Magnetic Activity ◽

Coronal Heating ◽

Small Scale

Abstract The coronal heating problem is a long-standing perplexing issue. In this study, 13 solar activity indexes are used to investigate their phase relation with the sunspot number (SSN). Only three of them are found to statistically significantly lag the SSN (large-scale magnetic activity) by about one solar rotation period; the three indexes are total solar irradiance (TSI), the modified coronal index, and the solar wind velocity; the former two indexes may represent the long-term variation of energy quantity of the heated photosphere and corona, respectively. The Mount Wilson Sunspot Index (MWSI) and the Magnetic Plage Strength Index (MPSI), which reflect the large- and small-scale magnetic field activities, respectively, are also utilised to investigate their phase relations with the three indexes. The three indexes are found to be much more intimately related to MPSI than to MWSI, and MWSI statistically significantly leads TSI by about one rotation period. The heated corona is found to pulse perfectly in step with the small-scale magnetic activity rather than the large-scale magnetic activity; furthermore, combined with observations, our statistical evidence should thus attribute coronal heating firmly to small-scale magnetic activity phenomena, such as spicules, micro-flares, nano-flares, and others. The photosphere and the corona are synchronously heated, which should seemingly prefer magnetic reconnection heating to wave heating. In the long term, such a coronal heating way is inferred effective. Statistically, it is also small-scale magnetic activity phenomena that produce TSI enhancement. Coronal heating and solar wind acceleration are found to be synchronous, as standard models require.

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Evolution of solar wind flows from the inner corona to 1 AU: constraints provided by SOHO UVCS and SWAN data

10.5194/egusphere-egu21-11921 ◽

2021 ◽

Author(s):

Alessandro Bemporad ◽

Olga Katushkina ◽

Vladislav Izmodenov ◽

Dimitra Koutroumpa ◽

Eric Quemerais

Keyword(s):

Solar Wind ◽

Interstellar Medium ◽

Mass Flux ◽

Solar Rotation ◽

Numerical Models ◽

Rotation Period ◽

Resonant Scattering ◽

The Sun ◽

Hydrogen Distribution ◽

First Results

The Sun modulates with the solar wind flow the shape of the whole Heliosphere interacting with the surrounding interstellar medium. Recent results from IBEX and INCA experiments, as well as recent measurements from Voyager 1 and 2, demonstrated that this interaction is much more complex and subject to temporal and heliolatitudinal variations than previously thought. These variations could be also related with the evolution of solar wind during its journey through the Heliosphere. Hence, understanding how the solar wind evolves from its acceleration region in the inner corona to the Heliospheric boundaries is very important.In this work, SWAN Lyman-&#945; full-sky observations from SOHO are combined for the very first time with measurements acquired in the inner corona by SOHO UVCS and LASCO instruments, to trace the solar wind expansion from the Sun to 1 AU. The solar wind mass flux in the inner corona was derived over one full solar rotation period in 1997, based on LASCO polarized brightness measurements, and on the Doppler dimming technique applied to UVCS Lyman-&#945; emission from neutral H coronal atoms due to resonant scattering of chromospheric radiation. On the other hand, the SWAN Lyman-&#945; emission (due to back-scattering from neutral H atoms in the interstellar medium) was analyzed based on numerical models of the interstellar hydrogen distribution in the heliosphere and the radiation transfer. The SWAN full-sky Lyman-&#945; intensity maps are used for solving of the inverse problem and deriving of the solar wind mass flux at 1 AU from the Sun as a function of heliolatitude. First results from this comparison for a chosen time period in 1997 are described here, and possible future applications for Solar Orbiter data are discussed.

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Study of Coronal Rotation using X-ray images observed by Hinode

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318001436 ◽

2018 ◽

Vol 13 (S340) ◽

pp. 179-180

Author(s):

Satish Chandra ◽

Vivek Kumar Singh ◽

Sanish Thomas

Keyword(s):

Time Series ◽

Time Series Data ◽

Solar Rotation ◽

Solar Physics ◽

Rotation Period ◽

Modulation Method ◽

Series Data ◽

X Ray ◽

Flux Modulation ◽

Coronal Rotation

AbstractSolar rotation is still one of the unresolved concern of solar physics. We performed time series analysis on the bins formed on equally separated latitude regions on the soft X-ray images. These images are observed with the X-ray telescope (XRT) on board the Hinode satellite. The flux modulation method traces the passage of X-ray feature over the solar disc and statistical analysis of the time series data of the SXR images (one per day) for the period extends from year 2015 to 2017 gives the coronal rotation period as a function of latitude. The investigation provided quite systematic information of the solar rotation and its variability.

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Deterministic dynamics of the magnetosphere: results of the 0–1 test

Nonlinear Processes in Geophysics ◽

10.5194/npg-20-11-2013 ◽

2013 ◽

Vol 20 (1) ◽

pp. 11-18 ◽

Cited By ~ 9

Author(s):

S. Prabin Devi ◽

S. B. Singh ◽

A. Surjalal Sharma

Keyword(s):

Magnetic Field ◽

Time Series ◽

Solar Wind ◽

Time Series Data ◽

Nonlinear Dynamical System ◽

Series Data ◽

Nonlinear Dynamical ◽

Deterministic Dynamics ◽

Time Period ◽

Solar Wind Magnetic Field

Abstract. A test for deterministic dynamics in a time series data, namely the 0–1 test (Gottawald and Melbourne, 2004, 2005), is used to study the magnetospheric dynamics. The data, corresponding to the same time period, of the auroral electrojet index AL and the magnetic field component Bz of the solar wind magnetic field measured at 1 AU are used to compute the parameter K, which is zero for non-chaotic and unity for chaotic systems. For the magnetosphere and also for the turbulent solar wind, K has values corresponding to a nonlinear dynamical system with chaotic behaviour. This result is consistent with the Lyapunov exponents computed from the same time series data.

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