Showing papers on "Space weather published in 2005"

Space Weather Modeling Framework: A new tool for the space science community

Abstract: [1] The Space Weather Modeling Framework (SWMF) provides a high-performance flexible framework for physics-based space weather simulations, as well as for various space physics applications. The SWMF integrates numerical models of the Solar Corona, Eruptive Event Generator, Inner Heliosphere, Solar Energetic Particles, Global Magnetosphere, Inner Magnetosphere, Radiation Belt, Ionosphere Electrodynamics, and Upper Atmosphere into a high-performance coupled model. The components can be represented with alternative physics models, and any physically meaningful subset of the components can be used. The components are coupled to the control module via standardized interfaces, and an efficient parallel coupling toolkit is used for the pairwise coupling of the components. The execution and parallel layout of the components is controlled by the SWMF. Both sequential and concurrent execution models are supported. The SWMF enables simulations that were not possible with the individual physics models. Using reasonably high spatial and temporal resolutions in all of the coupled components, the SWMF runs significantly faster than real time on massively parallel supercomputers. This paper presents the design and implementation of the SWMF and some demonstrative tests. Future papers will describe validation (comparison of model results with measurements) and applications to challenging space weather events. The SWMF is publicly available to the scientific community for doing geophysical research. We also intend to expand the SWMF in collaboration with other model developers.

Large-Scale Dynamics of the Convection Zone and Tachocline

Abstract: The past few decades have seen dramatic progress in our understanding of solar interior dynamics, prompted by the relatively new science of helioseismology and increasingly sophisticated numerical models. As the ultimate driver of solar variability and space weather, global-scale convective motions are of particular interest from a practical as well as a theoretical perspective. Turbulent convection under the influence of rotation and stratification redistributes momentum and energy, generating differential rotation, meridional circulation, and magnetic fields through hydromagnetic dynamo processes. In the solar tachocline near the base of the convection zone, strong angular velocity shear further amplifies fields which subsequently rise to the surface to form active regions. Penetrative convection, instabilities, stratified turbulence, and waves all add to the dynamical richness of the tachocline region and pose particular modeling challenges. In this article we review observational, theoretical, and computational investigations of global-scale dynamics in the solar interior. Particular emphasis is placed on high-resolution global simulations of solar convection, highlighting what we have learned from them and how they may be improved.

The association of coronal mass ejections with their effects near the Earth

Abstract: To this day, the prediction of space weather effects near the Earth suffers from a fundamental problem: The radial propagation speed of "halo" CMEs (ie CMEs pointed along the Sun-Earth-line that are known to be the main drivers of space weather disturbances) towards the Earth cannot be measured directly because of the unfavorable geometry From inspecting many limb CMEs observed by the LASCO coronagraphs on SOHO we found that there is usually a good correlation between the radial speed and the lateral expansion speed Vexp of CME clouds This latter quantity can also be determined for earthward-pointed halo CMEs Thus, Vexp may serve as a proxy for the otherwise inaccessible radial speed of halo CMEs We studied this connection using data from both ends: solar data and interplanetary data obtained near the Earth, for a period from January 1997 to 15 April 2001 The data were primarily provided by the LASCO coronagraphs, plus additional information from the EIT instrument on SOHO Solar wind data from the plasma instruments on the SOHO, ACE and Wind spacecraft were used to identify the arrivals of ICME signatures Here, we use "ICME" as a generic term for all CME effects in interplanetary space, thus comprising not only ejecta themselves but also shocks as well Among 181 front side or limb full or partial halo CMEs recorded by LASCO, on the one hand, and 187 ICME events registered near the Earth, on the other hand, we found 91 cases where CMEs were uniquely associated with ICME signatures in front of the Earth Eighty ICMEs were associated with a shock, and for 75 of them both the halo expansion speed Vexp and the travel time Ttr of the shock could be determined The function Ttr=203-2077*ln (Vexp) fits the data best This empirical formula can be used for predicting further ICME arrivals, with a 95% error margin of about one day Note, though, that in 15% of comparable cases, a full or partial halo CME does not cause any ICME signature at Earth at all; every fourth partial halo CME and every sixth limb halo CME does not hit the Earth (false alarms) Furthermore, every fifth transient shock or ICME or isolated geomagnetic storm is not caused by an identifiable partial or full halo CME on the front side (missing alarms)

Fair space weather for solar cycle 24

Abstract: [1] We discuss the polar field precursor method of solar activity forecasting, first developed 3 decades ago. Using this method the peak amplitude of the next solar cycle (24) is estimated at 124 ± 30 in terms of smoothed F10.7 Radio Flux and 80 ± 30 in terms of smoothed international or Zurich Sunspot number (Ri or Rz). This may be regarded as a “fair space weather” long term forecast. To support this prediction, direct measurements are obtained from the Wilcox and Mount Wilson Solar Observatories. Additionally, coronal features do not show the characteristics of well-formed polar coronal holes associated with typical solar minima, but rather resemble stunted polar field levels. The question is raised: why have the Sun's polar fields not strengthened comparably in the 2000–2005 time period, as in the previous few decades? The dramatic field changes seen suggest the importance of field motions associated with photospheric (e.g. meridional) flows for the Sun's dynamo. Flows may also play a role in active region development, e.g., it is possible that field magnification occurs through surface processes, namely active region field strengthening (sunspot growth) through the influx of like photospheric magnetic regions, and even the influx of ERs (ephemeral regions), wherein the same sign (like) flux could be differentially drawn into spots of that sign, leading to field growth.

Kp forecast models

Abstract: [1] Magnetically active times, e.g., Kp > 5, are notoriously difficult to predict, precisely the times when such predictions are crucial to the space weather users. Taking advantage of the routinely available solar wind measurements at Langrangian point (L1) and nowcast Kps, Kp forecast models based on neural networks were developed with the focus on improving the forecast for active times. To satisfy different needs and operational constraints, three models were developed: (1) a model that inputs nowcast Kp and solar wind parameters and predicts Kp 1 hour ahead; (2) a model with the same input as model 1 and predicts Kp 4 hour ahead; and (3) a model that inputs only solar wind parameters and predicts Kp 1 hour ahead (the exact prediction lead time depends on the solar wind speed and the location of the solar wind monitor). Extensive evaluations of these models and other major operational Kp forecast models show that while the new models can predict Kps more accurately for all activities, the most dramatic improvements occur for moderate and active times. Information dynamics analysis of Kp suggests that geospace is more dominated by internal dynamics near solar minimum than near solar maximum, when it is more directly driven by external inputs, namely solar wind and interplanetary magnetic field (IMF).

Callisto – A New Concept for Solar Radio Spectrometers

Abstract: A new radio spectrometer, CALLISTO, is presented. It is a dual-channel frequency-agile receiver based on commercially available consumer electronics. Its major characteristic is the low price for hardware and software, and the short assembly time, both two or more orders of magnitude below existing spectrometers. The instrument is sensitive at the physical limit and extremely stable. The total bandwidth is 825 MHz, and the width of individual channel is 300 kHz. A total of 1000 measurements can be made per second. The spectrometer is well suited for solar low-frequency radio observations pertinent to space weather research. Five instruments of the type were constructed until now and put into operation at several sites, including Bleien (Zurich) and NRAO (USA). First results in the 45–870 MHz range are presented. Some of them were recorded in a preliminary setup during the time of high solar activity in October and November 2003.

Predicting surface geomagnetic variations using ionospheric electrodynamic models

Abstract: [1] A technique is described for predicting ground surface geomagnetic variations from measurements of the approaching interplanetary magnetic field (IMF) and solar wind. The method uses twin, empirical representations of the ionospheric electric and magnetic Euler potentials' response to the IMF drivers. The magnetic potential model, originally derived for mapping the large-scale field-aligned current structure, describes the curl-free component of the horizontal ionospheric current, also called the “potential current.” Using approximations that the Hall and Pedersen conductances have a fixed ratio and that there are no conductivity gradients, then the Hall current is derived from the magnetic potentials. In this case the Hall current is the same as the divergence-free “equivalent current,” which is used to derive the geomagnetic variations at the ground surface. The assumption that the ionospheric conductances have no gradients is avoided if the empirical model for the ionospheric electric potentials is used in addition to the magnetic potentials. In this second method the electric field provides additional information about the direction of the estimated equivalent current. Despite the approximation of a fixed conductance ratio, both calculation methods perform remarkably well for predicting the large-scale and long-period geomagnetic variations. The method that includes the electric fields has a slightly better performance, particularly in the polar cap. Corrections for the effects of currents induced underground were not applied for this demonstration. Such corrections could in principle improve the predictions, particularly for the short-period variations for which the effect is the greatest.

Space weather conditions and spacecraft anomalies in different orbits

Abstract: [1] A large database of anomalies, registered by 220 satellites in different orbits over the period 1971–1994, has been compiled. For the first time, data of 49 Russian Kosmos satellites have been included in a statistical analysis. The database also contains a large set of daily and hourly space weather parameters. A series of statistical analyses made it possible to quantify, for different satellite orbits, space weather conditions in the days characterized by anomaly occurrences. In particular, very intense fluxes (>1000 particles cm−2 s−1 sr−1 (pfu) at energy >10 MeV) of solar protons are linked to anomalies registered by satellites in high-altitude (>15,000 km) near-polar (inclination >55°) orbits typical for navigation satellites such as those used in the GPS network, NAVSTAR, etc. (the rate of anomalies increases by a factor of ∼20) and to a much smaller extent to anomalies in geostationary orbits (the rate increases by a factor of ∼4). The efficiency in producing anomalies is found to be negligible for proton fluences 10 MeV. Elevated fluxes of energetic (>2 MeV) electrons >108 cm−2 d−1 sr−1 are observed by GOES on days with satellite anomalies occurring at geostationary (GOES, SCATHA, METEOSAT, MARECS A, etc.) and low-altitude ( 55°) orbits (Kosmos, SAMPEX, etc.). These elevated fluxes are not observed on days of anomalies registered in high-altitude near-polar orbits. Direct and indirect connections between anomaly occurrence and geomagnetic perturbations are also discussed.

Characteristic magnetic field and speed properties of interplanetary coronal mass ejections and their sheath regions

Abstract: [1] Prediction of the solar wind conditions in near-Earth space, arising from both quasi-steady and transient structures, is essential for space weather forecasting. To achieve forecast lead times of a day or more, such predictions must be made on the basis of remote solar observations. A number of empirical prediction schemes have been proposed to forecast the transit time and speed of coronal mass ejections (CMEs) at 1 AU. However, the current lack of magnetic field measurements in the corona severely limits our ability to forecast the 1 AU magnetic field strengths resulting from interplanetary CMEs (ICMEs). In this study we investigate the relation between the characteristic magnetic field strengths and speeds of both magnetic cloud and noncloud ICMEs at 1 AU. Correlation between field and speed is found to be significant only in the sheath region ahead of magnetic clouds, not within the clouds themselves. The lack of such a relation in the sheaths ahead of noncloud ICMEs is consistent with such ICMEs being skimming encounters of magnetic clouds, though other explanations are also put forward. Linear fits to the radial speed profiles of ejecta reveal that faster-traveling ICMEs are also expanding more at 1 AU. We combine these empirical relations to form a prediction scheme for the magnetic field strength in the sheaths ahead of magnetic clouds and also suggest a method for predicting the radial speed profile through an ICME on the basis of upstream measurements.

Surface electric fields and geomagnetically induced currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm

Abstract: A surface electric field model is used to estimate the UK surface E field during the 30 October 2003 severe geomagnetic storm. This model is coupled with a power grid model to determine the flow of geomagnetically induced currents (GIC) through the Scottish part of the UK grid. Model data are compared with GIC measurements at four sites in the power network. During this storm, measured and modeled GIC levels exceeded 40 A, and the surface electric field reached 5 V/km at sites in the United Kingdom (compared with quiet-time levels of less than 0.1 V/km). The electric field and grid models now form part of a GIC monitoring, analysis, and warning software package with Web interface, developed for use by the grid operator. This package also contains a daily geomagnetic activity forecast service, a solar wind shock detector for geomagnetic storm warning, and a near-real-time geomagnetic data stream for storm monitoring.

An event‐based approach to validating solar wind speed predictions: High‐speed enhancements in the Wang‐Sheeley‐Arge model

Abstract: [1] One of the primary goals of the Center for Integrated Space Weather Modeling (CISM) effort is to assess and improve prediction of the solar wind conditions in near-Earth space, arising from both quasi-steady and transient structures. We compare 8 years of L1 in situ observations to predictions of the solar wind speed made by the Wang-Sheeley-Arge (WSA) empirical model. The mean-square error (MSE) between the observed and model predictions is used to reach a number of useful conclusions: there is no systematic lag in the WSA predictions, the MSE is found to be highest at solar minimum and lowest during the rise to solar maximum, and the optimal lead time for 1 AU solar wind speed predictions is found to be 3 days. However, MSE is shown to frequently be an inadequate “figure of merit” for assessing solar wind speed predictions. A complementary, event-based analysis technique is developed in which high-speed enhancements (HSEs) are systematically selected and associated from observed and model time series. WSA model is validated using comparisons of the number of hit, missed, and false HSEs, along with the timing and speed magnitude errors between the forecasted and observed events. Morphological differences between the different HSE populations are investigated to aid interpretation of the results and improvements to the model. Finally, by defining discrete events in the time series, model predictions from above and below the ecliptic plane can be used to estimate an uncertainty in the predicted HSE arrival times.

A statistical solar flare forecast method

Abstract: [1] A Bayesian approach to solar flare prediction has been developed which uses only the event statistics of flares already observed. The method is simple and objective and makes few ad hoc assumptions. It is argued that this approach should be used to provide a baseline prediction for certain space weather purposes, upon which other methods, incorporating additional information, can improve. A practical implementation of the method for whole-Sun prediction of Geostationary Observational Environment Satellite (GOES) events is described in detail and is demonstrated for 4 November 2003, the day of the largest recorded GOES flare. A test of the method is described on the basis of the historical record of GOES events (1975–2003), and a detailed comparison is made with U.S. National Oceanic and Atmospheric Administration (NOAA) predictions for 1987–2003. Although the NOAA forecasts incorporate a variety of other information, the present method outperforms the NOAA method in predicting mean numbers of event days for both M-X and X events. Skill scores and other measures show that the present method is slightly less accurate at predicting M-X events than the NOAA method but substantially more accurate at predicting X events, which are important contributors to space weather.

Space weather risk

Abstract: [1] The importance of space weather to society is in a continuous increase since we are more and more dependent on reliable spaceborne and ground-based technological systems. Physical processes involved in space weather constitute a complicated chain from the Sun to the Earth's surface, so the management of space weather risks requires expertise in many disciplines of science and technology. In this paper, geomagnetically induced currents in electric power networks are considered in detail, referring particularly to research carried out in Finland. Today's monitoring systems of natural risks, such as floods and forest fires, are based on satellite observations. Spacecraft and communication between satellites and the ground are vulnerable to space weather. Thus, besides being a direct risk to technology, space weather may also indirectly have adverse effects on risk management. European efforts, which take into account both aspects, are also discussed in this paper.

Solar control on Jupiter's equatorial X-ray emissions: 26-29 November 2003 XMM-Newton observation

Abstract: During November 26-29,2003 XMM-Newton observed X-ray emissions from Jupiter for 69 hours. The 0.7-2.0 keV X-ray disk of Jupiter is observed to be brightest at the subsolar point, and limb darkening is seen in the 0.2-2.0 keV and 0.7-2.0 keV images. We present simultaneous lightcurves of Jovian equatorial X-rays and solar X-rays measured by the GOES, SOHO/SEM, and TIMED/SEE satellites. The solar X-ray flares occurring on the Jupiter-facing side of the Sun are matched by corresponding features in the Jovian X- rays. These results support the hypothesis that X-ray emissions from Jovian low-latitudes are solar X-rays scattered and fluoresced from the planet's upper atmosphere, and confirm that the Sun directly controls the non-auroral X-rays fiom Jupiter's disk. Our study suggest that Jovian equatorial X-rays; during certain Jupiter phase, can be used to predict the occurrence of solar flare on the hemisphere of the Sun that is invisible to space weather satellites.

On the effect of the initial magnetic polarity and of the background wind on the evolution of CME shocks

Abstract: The shocks and magnetic clouds caused by Coronal Mass Ejections (CMEs) in the solar corona and interplanetary (IP) space play an important role in the study of space weather. In the present paper, numerical simulations of some simple CME models were performed by means of a finite volume, explicit solver to advance the equations of ideal magnetohydrodynamics. The aim is to quantify here both the effect of the background wind model and of the initial polarity on the evolution of the IP CMEs and the corresponding shocks. To simulate the CMEs, a high density-pressure plasma blob is superposed on different steady state solar wind models. The evolution of an initially non-magnetized plasma blob is compared with that of two magnetized ones (with both normal and inverse polarity) and the differences are analysed and quantified. Depending on the launch angle of the CME and the polarity of the initial flux rope, the velocity of the shock front and magnetic cloud is decreased or increased. Also the spread angle of the CME and the evolution path of the CME in the background solar wind is substantially different for the different CME models and the different wind models. A quantitative comparison of these simulations shows that these effects can be quite substantial and can clearly affect the geo-effectiveness and the arrival time of the events.

Turbulence In The Solar Atmosphere: Manifestations And Diagnostics Via Solar Image Processing

Abstract: Intermittent magnetohydrodynamical turbulence is most likely at work in the magnetized solar atmosphere. As a result, an array of scaling and multi-scaling image-processing techniques can be used to measure the expected self-organization of solar magnetic fields. While these techniques advance our understanding of the physical system at work, it is unclear whether they can be used to predict solar eruptions, thus obtaining a practical significance for space weather. We address part of this problem by focusing on solar active regions and by investigating the usefulness of scaling and multi-scaling image-processing techniques in solar flare prediction. Since solar flares exhibit spatial and temporal intermittency, we suggest that they are the products of instabilities subject to a critical threshold in a turbulent magnetic configuration. The identification of this threshold in scaling and multi-scaling spectra would then contribute meaningfully to the prediction of solar flares. We find that the fractal dimension of solar magnetic fields and their multi-fractal spectrum of generalized correlation dimensions do not have significant predictive ability. The respective multi-fractal structure functions and their inertial-range scaling exponents, however, probably provide some statistical distinguishing features between flaring and non-flaring active regions. More importantly, the temporal evolution of the above scaling exponents in flaring active regions probably shows a distinct behavior starting a few hours prior to a flare and therefore this temporal behavior may be practically useful in flare prediction. The results of this study need to be validated by more comprehensive works over a large number of solar active regions. Sufficient statistics may also establish critical thresholds in the values of the multi-fractal structure functions and/or their scaling exponents above which a flare may be predicted with a high level of confidence.

Correlated measurements of secondary cosmic ray fluxes by the Aragats Space-Environmental Center monitors

Abstract: The Aragats Space-Environmental Center provides monitoring of different species of secondary cosmic rays at two altitudes and with different energy thresholds. One-minute data is available on-line from http://crdlx5.yerphi.am/DVIN/index2.php . We present description of the main monitors along with data acquisition electronics. Also we demonstrate the sensitivity of the different species of secondary cosmic ray flux to geophysical conditions, taking as examples the extremely violent events of October–November 2003. We introduce correlation analysis of the different components of registered time-series as a new tool for the classification of the geoeffective (events on earth affected by solar activity) events and for the forecasting of the severity of the upcoming geomagnetic storm.

Structure of magnetic fields in NOAA active regions 0486 and 0501 and in the associated interplanetary ejecta

Abstract: [1] Spectacular burst of solar activity in October–November 2003, when large solar spots and intense solar flares dominated the solar surface for many consecutive days, caused intense geomagnetic storms. In this paper we analyze solar and interplanetary magnetic fields associated with the storms in October–November 2003. We used space- and ground-based data in order to compare the orientations of the magnetic fields on the solar surface and at 1 AU as well as to estimate parameters of geomagnetic storms during this violent period of geomagnetic activity. Our study further supports earlier reports on the correlation between the coronal mass ejection speed and the strength of the magnetic field in an interplanetary ejecta. A good correspondence was also found between directions of the helical magnetic fields in interplanetary ejecta and in the source active regions. These findings are quite significant in terms of their potential to predict the severity of geomagnetic activity 1–2 days in advance, immediately after an Earth directed solar eruption.

Operational space weather service for GNSS precise positioning

Abstract: . The ionospheric plasma can significantly influence the propagation of radio waves and the ionospheric disturbances are capable of causing range errors, rapid phase and amplitude fluctuations (radio scintillations) of satellite signals that may lead to degradation of the system performance, its accuracy and reliability. The cause of such disturbances should be sought in the processes originating in the Sun. Numerous studies on these phenomena have been already carried out at a broad international level, in order to measure/estimate these space weather induced effects, to forecast them, and to understand and mitigate their impact on present-day technological systems. SWIPPA (Space Weather Impact on Precise Positioning Applications) is a pilot project jointly supported by the German Aerospace Centre (DLR) and the European Space Agency (ESA). The project aims at establishing, operating, and evaluating a specific space-weather monitoring service that can possibly lead to improving current positioning applications based on Global Navigation Satellite Systems (GNSS). This space weather service provides GNSS users with essential expert information delivered in the form of several products - maps of TEC values, TEC spatial and temporal gradients, alerts for ongoing/oncoming ionosphere disturbances, etc.

Space Weather. The Physics Behind a Slogan

Abstract: Introduction to Space Weather.- The Sun and its Restless Magnetic Field.- The Application of Radio Diagnostics to the Study of the Solar Drivers of Space Weather.- Interplanetary Disturbances.- The Magnetosphere.- Space Weather Effects in the Upper Atmosphere: Low and Middle Latitudes.- Space Weather Effects in the Upper Atmosphere: High Latitudes.- Space Weather Effects on Technology.- Radiation Risks From Space.- Index.

Statistical survey of earthbound interplanetary shocks, associated coronal mass ejections and their space weather consequences

Abstract: A comprehensive statistical analysis of events relevant to space weather over the 80 month period from January 1998 to August 2004 is presented. A database has been constructed using data from instruments from the SOHO, ACE, WIND and GOES spacecraft, as well as ground magnetometer data. Parameters investigated include times and epochs of halo and partial halo coronal mass ejections (HCMEs) along with details of the interplanetary shock at L1 (0.99 AU), namely the changes in the interplanetary magnetic field and solar wind density, and shock speed. Transit time to the Earth and average transient speed have also been determined, along with the projected speed and angular width of the HCME at the Sun. An estimate is made of the acceleration of the transients on their passage from the Sun to the Earth, and associated solar flare data are considered. Finally, the geoeffectiveness of the events are analysed using A p , Dst and sudden commencement data. We found that just over a quarter of the 938 HCMEs observed by LASCO were associated with a forward shock near L1, suggesting that around half of the Earthbound HCMEs are either deflected away from the Sun-Earth line or do not form a shock. Around half of the shocks went on to cause a geomagnetic storm, consistent with a southward B IMF occurring 50% of the time. There was a general tendency for HCME and shock speeds to be more varied (with more events at higher speeds) around solar maximum, and most events decelerated in transit to the Earth, implying a speed “equalisation” between the HCME shock and surrounding solar wind, although an assumption of a constant acceleration appears to be invalid. Only around 40% of the shock/storms were associated with an X or M class flare, and there appears to be no relationship between flare intensity and any physical parameter close to the Earth, except in extreme cases. There was a tendency for HCME speed near the Sun to increase with flare intensity. This casts doubt on the validity of using flare data alone as an effective space weather forecaster.

CORONAS‐F/SPIRIT EUV observations of October–November 2003 solar eruptive events in combination with SOHO/EIT data

Abstract: [1] The extraordinary solar activity of October–November 2003 manifested itself in many powerful eruptive events, including large coronal mass ejections (CMEs) and extremely powerful flares. A number of major events were accompanied by practically all known phenomena of the solar activity, both local and large-scale, and caused severe space weather disturbances. We study large-scale posteruptive activity manifestations on the Sun associated with CMEs, i.e., dimmings and coronal waves, observed with extreme-ultraviolet telescopes, the SPIRIT on the CORONAS-F spacecraft and the EIT on the SOHO. During that period, observations with a cadence of 15 to 45 min were carried out by the SPIRIT in the 175 A and 304 A bands simultaneously. The EIT observed with 12-min cadence in the 195 A band as well as with 6-hour cadence in the 171, 284, and 304 A bands. These data complement each other both in the temporal and spectral coverage. Our analysis reveals that largest-scale dimmings covered almost the whole southern part of the Sun's visible side and exhibited homology, with one homological structure being changed to another configuration on 28 October. These structures show connections between large superactive and smaller regions that constituted a huge activity complex responsible for the extraordinary solar activity of that period. Coronal waves were observed at 175 A as well as at 195 A in some events, in areas where there were no active regions, but in the 175 A images they look fainter. They were not accompanied by deep, long-living dimmings. By contrast, such dimmings were observed in active regions, in their vicinity, and between them. These facts rule out the direct relation of the phenomena of long-term dimmings and coronal waves. On 18 November, a motion of an ejecta was observed at the solar disk as a propagation of a dark feature only in the 304 A band, which can be interpreted as an absorption in a “cloud” formed from material of the eruptive filament, which probably failed to become a CME core.

Solar Control on Jupiter's Equatorial X-ray Emissions: 26-29 November 2003 XMM-Newton Observation

Abstract: During November 26-29, 2003 XMM-Newton observed soft (0.2-2 keV) X-ray emission from Jupiter for 69 hours. The low-latitude X-ray disk emission of Jupiter is observed to be almost uniform in intensity with brightness that is consistent with a solar-photon driven process. The simultaneous lightcurves of Jovian equatorial X-rays and solar X-rays (measured by the TIMED/SEE and GOES satellites) show similar day-to-day variability. A large solar X-ray flare occurring on the Jupiter-facing side of the Sun is found to have a corresponding feature in the Jovian X-rays. These results support the hypothesis that X-ray emission from Jovian low-latitudes are solar X-rays scattered from the planet's upper atmosphere, and suggest that the Sun directly controls the non-auroral X-rays from Jupiter's disk. Our study also suggests that Jovian equatorial X-rays can be used to monitor the solar X-ray flare activity on the hemisphere of the Sun that is invisible to space weather satellites.