Using ground-based ionosonde observations in the American longitudinal sector at the geomagnetic equator (Huancayo and Jicamarca) and stations located in the vicinity of the Equatorial Ionization Anomaly (EIA) crests (Bogota and Tucuman) cases of NmF2 enhancements similar to those discussed in recent publications were analyzed for their possible relationship with the following magnetic disturbances. For recent years ground-based NmF2 observations were supported by TEC data and CHAMP in-situ electron density measurements. By analogy with earlier obtained results on middle and sub-auroral latitudes it is possible to conclude that there are no convincing arguments that the observed cases of NmF2 and TEC prestorm enhancements at low latitudes considered by Liu et al.
[2008a,b] bear a relation to the following magnetic storms, i.e. there is no such an effect as the prestorm NmF2 enhancement at the EIA crests as a phenomenon inalienably related to the following magnetic storm. A spotty longitudinal structure of TEC at the EIA crests contradicts the conclusion about TEC enhancements which "confined at narrow longitude ranges with centers at around longitude 120E". TEC enhancements with the same magnitude can be observed in different longitudinal sectors. Strong NmF2 enhancements at the EIA crests are observed under very quiet magnetic conditions and they can be attributed to the class of quiet-time F2-layer disturbances which are due to vertical ExB plasma drifts.
According to recent publications such quiet-time longitudinally dependent ExB drifts are due to nonmigrating tidal winds or planetary waves and they have nothing to do with geomagnetic activity.

On May, 2005, at 02:38 UT an interplanetary shock was recorded by ACE. The following interplanetary structure produced an important geomagnetic storm (minimal value of the Dst index=-263 nT). Analysis of interplanetary (plasma and magnetic) observations has shown that these disturbances could correspond to the arrival of magnetic clouds.

The main trigger of the geomagnetic storm is definitively the fast halo CME of May 13 (LASCO) observed consequently to the falre occurring at 17:22 UT in the active region 10759. However the analysis of different possible scenarios for the interpretation. The existence of two clouds produced by two different solar events on May 13 (two different filament eruption) is the more probable scenario.
The agreement between the magnetic helicity sign in the source region and the magnetic clouds, together with the agreement between the MC axis orientations and the polarity inversion line directions, support this view. The scintillation experiment of Ooty observes an enhancement of the density produce by the clouds.

The galactic cosmic rays (CR) create ionization in the terrestrial atmosphere, particularly in the stratosphere and the troposphere. They present a basic ionization source under the altitude 35 km towards the sea level. The solar CR are generated in their great part by solar proton events. The coronal mass ejections (CME) also generate energetic particles. Usually the solar cosmic rays have energy of a few hundreds MeV, rarely - a little above several GeV. The primary cosmic ray particles create Bremsstrahlung in the terrestrial atmosphere from nuclear cascade processes in it. The high energy primary particles penetrate in the terrestrial atmosphere, collide with the atmospheric nuclei and create new energetic particles. The secondary particles give up their energy in the terrestrial atmosphere. As a result from it the atmosphere is ionized.

The corpuscular-electromagnetic cascades in the atmosphere play important role in the physics and the chemistry of the ion balance there. It is well known, that the low energy particles intensity is greater than that of the high energy particles. Therefore the ionization appreciation for different events will be very interesting, because the ion balance in the atmosphere will be also different. On that basis the influences and changes concerning the minor constituents' density, as the ozone density, will be determined. The following cosmic ray events are investigated: 28, 29 October and 2 November 2003, i.e. Ground Level Enhancements numbers 65, 66 and 67 (GLE 65, 66 and 67), according international CR event classification. For this purpose the energy spectra of particles in two different moments for every proton event are calculated. After that the ionization rate in the middle atmosphere is evaluated in these moments.

The ozone production rate in the atmosphere is determined on the basis of this ionization rate for these different moments. After that the ozone quantity in these time intervals is calculated by integration in time. For the computation of cascade processes ionization the model CORSIKA 6.52 is used. The hadron interactions are modeled with the subroutines GHEISHA and QGSJET II. As a result some interesting results are obtained. It turns out that the low energy flux is more important for the ozone density changes than the high energy particles. The results from the statistical processing present a basis to seek a physical explanation for the ozone increase in the lower stratosphere. A quantitative estimation is made for this purpose concerning the possibility for creation of ozone by the solar cosmic ray flux. The calculations are made for the first 15 hours after the event which corresponds to the delay from the statistical processing. This estimation includes the following steps:

1. Differential energy spectrum determination for the proton flux in two different moments.
2. Evaluation of the ionization rate in the atmosphere at these two different moments.
3. Evaluation of the ozone production rate in the atmosphere at these two different moments.
4. Evaluation of the ozone quantity which is created in the time interval between these two different moments.

On the basis of the cosmic ray impact the nuclear cascade processes in the terrestrial atmosphere are modeled. The ionization rate can be estimated from the Earth’s surface until the upper atmosphere for the given solar proton flare. The model CORSIKA 6.52 with the corresponding hadron interaction modules GHEISHA and QGSJET II is applied for the cascade processes. The electromagnetic interactions are modeled in CORSIKA with the module EGS4. The atmosphere is divided in 103 steps from 10 g/cm2 which secures high accuracy. The lowest cut-off energy value from 10 MeV is applied. Now the vertical distribution of the ozone production rate in the atmosphere as a result from the proton flux impact must be appreciated. It can be calculated using the experimental data for estimation of the oxygen – nitrogen gas mixture radiolysis. Ozone and nitrogen oxides are generated by irradiation of oxygen - nitrogen mixture. The oxygen - nitrogen mixture can be assumed as a good description of air.

The quantitative considerations in the present work give us the possibility for research of the latitudinal dependence of the solar cosmic ray ionization and therefore the latitudinal distribution of the ozone production. Up to now this effect has been a little investigated. But the differences between the ozone production at middle and polar latitudes is significant. This fact gives new information about the processes of redistribution of ozone during the solar CR events.

REFERENCES

Velinov P.I.Y., A. Mishev. C. r. Acad. Bulg. Sci. v. 60, 2007, ¹ 5, pp. 493-500.
Heck D. et al., CORSIKA: Monte Carlo Code to Simulate Extensive Air Showers. Rep. FZKA 6019 Forschungszent. Karlsruhe, 1997.
A.Mishev, P.I.Y.Velinov, C. r. Acad. Bulg. Sci. v. 61, 2008, ¹ 8, pp. 1047-1054.

Coronal Mass Ejections (CMEs) are very energetic events initiated in the solar atmosphere, resulting in the expulsion of magnetized plasma clouds that propagate into interplanetary space. It has been proposed that CMEs can play an important role in shedding magnetic helicity, avoiding its endless accumulation in the corona. We therefore investigated the behavior of magnetic helicity accumulation in sites where the initiation of CMEs occurred, in order to determine whether and how changes in magnetic helicity accumulation are temporally correlated with CME occurrence. After identifying the active regions (AR) where the CMEs were initiated by means of a double cross-check based on the flaring-eruptive activity and the use of SOHO/EIT difference images, we use MDI magnetograms to calculate magnetic flux evolution magnetic helicity injection rate and magnetic helicity injection in 10 active regions that gave rise to 12 halo CMEs observed during the period February 2000 - June 2003.
No unique behavior in magnetic helicity injection accompanying halo CME occurrence is found. In fact, in some cases there is an abrupt change in helicity injection timely correlated with the CME event, while in some others no significant variation is recorded. However, our analysis show that the most significant changes in magnetic flux and magnetic helicity injection are associated with impulsive CMEs rather than gradual CMEs. Moreover, the most significant changes in magnetic helicity are observed when X-class flares or eruptive filaments occur, while the occurrence of flares of class C or M seems not to affect significantly the magnetic helicity accumulation. Finally, this study shows that magnetic helicity accumulation in our sample of ARs generating halo CMEs has sudden and abrupt changes only in 40 % of the cases examined and that a correlation between the helicity injection changes and the nature (gradual or impulsive) of the CMEs seems to exist.

Predicting the geo-effects of major space weather events, such as Coronal Mass Ejection (CMEs), is complicated by the fact that we have no direct measurements of initial CME parameters at the Sun, such as speed and propagation direction. We evaluate two different methods of extracting input parameters for a heliospheric propagation model, using SOHO/LASCO images. One method is estimating by eye and hand and the other is estimating through an automated conic method. In order to achieve multipoint comparison of the model and to be able to assess the longitudinal extent of the Interplanetary CMEs (ICMEs), we use both near Earth solar wind measurements and particle and field measurements from the Mars Global Surveyor (MGS) MAG/ER instrument.
We use the ENLIL 3D Magneto-Hydro-Dynamic (MHD) model, available online through the Community Coordinated Modeling Center at Goddard Space Flight Center, to try and replicate data for the ICMEs. The event list consists of 18 CMEs, primarily events picked when Earth and Mars are separated by less than ~60 degrees in heliocentric longitude. The list includes all major events visible at Mars and Earth where we can identify the source on the Sun in the period 1999-2006 (MGS operation span), with a reasonable degree of certainty. Specific parameters of interest are arrival time, signal amplitude and longitudinal span of the ICMEs. At Earth the model estimates of velocity, density and magnetic field strength are compared to Ace, Wind and Geotail data, while at Mars the modeled solar wind dynamic pressure is compared to a dynamic pressure proxy estimated from magnetic field data from MGS.

Solar radio bursts in the metric range correspond dominantly to plasma emission. Since electron plasma frequency f is linked to electron density n (f ≈ n ^1/2), radio bursts can provide an estimation of the coronal electron density. EUV observations show that the corona overlying active regions is not uniform. Therefore, a single density profile is not adequate to explain all types of radio bursts, possibly associated with different types of coronal structures.
To be able to compare density profiles corresponding to different coronal structures of the same active region, we analyzed two types of radio emission, type II and type III bursts. The density profiles were obtained using the Nançay Radioheliograph imaging observations and dynamic radio spectra recorded by radiospectrographs of the Astrophysical Institute Potsdam. The observations of the plasma dynamics in the low corona were provided by the Extreme-ultraviolet Imaging Telescope (EIT instrument onboard SOHO).
The study showed that the type III bursts were mostly associated with the coronal structures having significantly larger density gradients than the generally used coronal density models. On the other hand, the coronal density models correspond rather well with the density profiles obtained from the type II bursts.

The existence of a long-term trend in the Total Solar Irradiance (TSI) is a topic of considerable societal importance, and has also been hotly disputed in the last few years. Different TSI composites have been built out of the nine observations that have been made since 1978, and they disagree. Recently, empirical or semi-empirical models have been used to support one or the other composite.

Here, we use a newly developed gap filling technique to investigate this problem from a statistical point of view, with no model bias. The strong correlation between the different observations is used to extrapolate the record from each instrument. This allows us to reconstruct the missing observations as if each instrument had been continuously operating since 1978, by assuming that the statistical properties of each record with respect to the others has not changed. Interestingly, these reconstructions readily reveal which records suffer from instrumental artefacts. This allows us to intercompare the different TSI records and to show when the observations have started to disagree. This information is crucial for improving present composites and obtaining a better estimate of the long-term trend in the TSI.

We compare these reconstructions with a TSI estimation based on the semi-empirical model of solar magnetograms, and evaluate the pertinence of the different existing composites.

Characterization of the three-dimensional structure of solar transients using incomplete plane of sight data is a difficult problem whose solutions have potential for societal benefit in terms of space weather applications. In this paper transients are characterized in three dimensions by means of conic coronal mass ejection (CME) approximation. A novel method for the automatic determination of cone model parameters from observed halo CMEs is introduced. The method uses both standard image processing techniques to extract the CME mass from white-light coronagraph images and a novel inversion routine providing the final cone parameters. A Bootstrap technique is used to provide model parameter distributions. When combined with heliospheric modeling, the cone model parameter distributions will provide direct means for ensemble predictions of transient propagation in the heliosphere.

An initial validation of the automatic method is carried by comparison to manually determined cone model parameters. It is shown using 14 halo CME events that there is reasonable agreement, especially between the heliocentric locations of the cones derived with the two methods. It is argued that both the heliocentric locations and the opening half-angles of the automatically determined cones may be more realistic than those obtained from the manual analysis.

With the limited availability of coronagraph observations that are needed to monitor CME activity, it becomes increasingly important to recognize the onset of a geoeffective CME using disk-observations alone. Relating CMEs to on-disk signatures is a less obvious task than it sounds. CMEs erupting from outside active regions do not always leave a clear trace. Some signatures are so subtle that they are only noticeable by the trained eye. In this talk we will discuss our recent understanding of the dimming phenomenon that often coincides with CMEs. From multi-wavelength observations of filament eruptions, it is evident that these dimmings are much more pronounced in 19.5 nm than in the lower-temperature line 17.1 nm, as viewed either on the disk or above the limb. We conclude that most of the cooler coronal plasma is not ejected but remains gravitationally bound when the loops open up. When the open flux reconnects and closes down again, the trapped plasma is initially heated to such high temperatures that it is no longer visible at 17.1 nm. Correspondingly, 17.1 nm images show a dark ribbon or "heat wave" propagating away from the polarity inversion line and coinciding with the brightened 28.4 nm and 19.5 nm post-eruptive loops and their footpoint areas. Such dark ribbons provide a clear example of dimmings that are not caused by a density depletion. The propagation of the "heat wave" is driven by the closing-down, not the opening-up, of the flux and can be observed both off-limb and on-disk.

This presentation will summarise the results from the NASA STEREO since launch until fall 2010 on the properties and geo-effectiveness of earthward propagating coronal mass ejections (CMEs) tracked with the SECCHI imaging suite.

Compressions of interplanetary magnetic field (IMF) associated with interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs) cause short-term decreases (so-called Forbush decreases, FDs) in galactic cosmic ray (CR) flux. The mechanism of this modulation is still a matter of research. In this report we analyze the influence of different parameters on the amplitude and the duration of Forbush decreases, using ground-based neutron monitor data and in situ solar wind data from the Advanced Composition Explorer (ACE). Solar wind disturbances were identified as increases of solar wind speed, IMF and magnetic field fluctuations and sorted by the type (ICME/CIR) and the association with a shock. Furthermore, FDs were treated separately for cases showing the over-recovery phase in CR flux. We analyzed correlations between CR depression amplitudes and solar wind speed, IMF and IMF fluctuations. Time profiles of the FDs and solar wind disturbances were also examined. An extensive statistical analysis was made regarding the delay of the depression after the onset of the IMF increase and also magnitude and the duration of the depression. The analysis of relative timing of CR depressions revealed that in the majority of cases the decrease follows the onset in IMF increase. Very high correlation between FD magnitude and IMF fluctuations is indicative of important role of reduced parallel diffusion as a modulation mechanism. Furthermore, the modulation effect was found to be more pronounced when proxies of time integrals are used. The differences obtained for the data sorted by type, shock association and presence of over-recovery are discussed regarding both FD magnitude and time profiles. These results can be used to test theoretical models.

There is a ground-based technique which can track travelling interplanetary disturbances (TID) from about 0.35 AU to beyond the Earth’s orbit. These disturbances can perturb the geomagnetic field, and the technique has been used to demonstrate the ability to provide, typically, 24 hours notice of a significant geomagnetic disturbance and/or proton shower, with the potential of forecasting such events 48 hours in advance. The technique uses the scintillation of extragalactic radio sources, such as radio galaxies and quasars, as a background to the interplanetary medium. Fluctuations in the electron density of the medium cause the scintillations which can be observed on the surface of the Earth using antenna arrays (monitoring stations) operating at a radio frequency of around 100 MHz. Such arrays are relatively inexpensive to construct and operate, but can provide valuable additional data to that from current instruments and the potential for an order-of-magnitude improvement in solar-weather forecasting reliability.

We propose the construction of a network of ground-based monitoring stations which will provide hourly maps of the total electron content along lines of sight through the interplanetary medium. The maps are of the ratio between the observed scintillation of a given radio source, and that expected on average for that radio source. A travelling interplanetary disturbances enhances the scintillation on observations of radio sources whose lines of sight pass through it, so the maps reveal the position and extent of the disturbance and, by comparison of maps made a few hours apart, can provide an estimate of the velocity and trajectory.

The technique of interplanetary scintillations (IPS) was developed in radio astronomy, during the period from the mid sixties to nineties, as a method of measuring the sub-arcsecond angular sizes of ‘hot spots’ in radio sources at metre wavelengths, but its use for studying moving interplanetary transients and co-rotating streams was also pioneered. Although the radio telescopes available at that time were limited in their capabilities, the use of the technique for synoptic monitoring of the solar wind was recognised, and a pilot study was undertaken by NOAA which received a daily feed from the 36,000 square metre array at Cambridge, UK, operating at a frequency of 81.5 MHz, to establish the link between the arrival at the Earth of a moving interplanetary transient and the geomagnetic index.

In this paper, we describe the processing techniques and show some results which were obtained using the Cambridge data. We propose the architecture of a new system of dedicated low-frequency low-cost monitoring stations to provide for a dedicated facility to give 24-hour coverage. The facility would have the capability of monitoring and tracking moving disturbances in the solar wind, and of providing advance warning of the impact of a solar-wind stream with the Earth. By digitising the signal from every dipole individually, the latest computational techniques can be utilised for the array processing so that all directions can be simultaneously observed in zenith angles less than about 45 degrees. This provides for the production of hourly synoptic maps of interplanetary weather, together with estimates of the velocities and sizes of the disturbances.

ESA's microsatellite PROBA2 was launched in November 2009, with two instruments on board which are commanded from the Royal Observatory of Belgium: The imager SWAP and the radiometer LYRA observe solar radiation in extreme ultraviolet and soft X-ray. LYRA delivers solar irradiances with high temporal resolution in four spectral intervals, while SWAP delivers approx. one image per minute of the solar corona. These observations will be used to describe the passing of active region 1087 across the disk, between 06 and 23 July 2010, with respect to short-term (flare) and long-term variability. One aim is to separate the SXR and the EUV influences on two of the LYRA channels with the help of SWAP data (EUV) integrated over the whole disk, and GOES data (SXR). SWAP and LYRA flare intensities observed during this period will be compared to the GOES X-ray flux for the same flares.

Magnetospheric ULF waves strongly influence radiation belt dynamics and are therefore of particular relevance for space weather nowcasting and forecasting efforts. We have used novel algorithms based on wavelet spectral analysis methods to study multipoint observations of ULF wave activity by the Cluster and THEMIS missions and ground-based magnetometers. Wavelet analysis is becoming a common tool for analyzing localized variations of power within a time series. By decomposing a time series into time-frequency space, one is able to determine both the dominant modes of variability and how those modes vary in time. The advantage of analyzing a signal with wavelets as the analyzing kernel is that it enables one to study features of the signal locally with a detail matched to their scale. Owing to its unique time-frequency localization, wavelet analysis is especially useful for signals that are non-stationary, have short-lived transient components, have features at different scales, or have singularities. Our long-term aim is to develop automatic identification tools that will allow the detection, identification and classification of various categories of ULF waves according to well-defined criteria.

Two halo CMEs were observed by the LASCO/SOHO coronagraph on 3 and 8 April 2010. These events were observed as limb CMEs by STEREO-A and -B spacecraft. On-disk, EUV images recorded by SWAP/PROBA2, EUVI/STEREO and EIT/SOHO show EIT waves, EUV dimmings, as well as post-eruptive arcades. Both CMEs were associated with flares (observed by LYRA/PROBA2) and erupting filaments. Slowly drifting radio continuum in the frequency range of 70-20 MHz was observed in association with 3 April 2010 event. The CMEs were detected in-situ by ACE and they both produced geomagnetic storms when interacting with the Earth magnetic field. We apply the reconstruction techniques described in Mierla et al. 2009 to these events in order to infer their 3D structure, the true speed and the direction of propagation. The travel time to the Earth is calculated using the speeds derived from the 3D reconstruction techniques. Comparison of the calculated travel time with the true arrival time is done in order to improve the reconstruction results. Analysis and comparison of the source regions will be also presented and discussed.

The HELIO project aims at providing interoperability between data related to the Sun and Heliosphere. One of the HELIO workpackages, entitled 'Tools for the 4D Heliosphere', is dedicated to the possibility of automatically detecting heliospheric features, and to connecting them as they evolve or propagate.

The results of this workpackage will be included in a Heliophysics Feature Catalogue. This catalogue will be used in the workflow together with other metadata catalogues and propagation models allowing Heliospheric features to be tracked from the Sun to the environment of various planets.

HELIO is funded under EC's Seventh Framework Programme (FP7) and involves groups from seven counties. The project started in mid 2009 and will last for 3 years. For more information see www.helio-vo.eu

Radiation belt enhancements have long been associated with increased geospace activity. Earthward displacements of radiation belt maxima, in particular, have been observed during intense geospace magnetic storms. On the other hand, it has been noticed that not all magnetic storms result in more intense radiation belts; actually a large percentage of storms result in weaker radiation belts. It has been recently suggested by Selesnick et al. [2010] that a decisive factor of radiation belt enhancements may be the occurrence of solar energetic particle (SEP) events and the injection and trapping of solar energetic protons in the inner magnetosphere. The operation of the Standard Radiation Environment Monitor (SREM) on several ESA spacecraft, which efficiently monitor SEP events, provides an opportunity to investigate the competing role magnetic storms and SEP events in radiation belt variability.