SM41A-0310
The Michigan Space Weather Modeling Framework (SWMF)
The Space Weather Modeling Framework (SWMF) developed at the University of MIchigan has been used to model a wide variety of space environments. It is especially well suited to space weather modeling and can follow the complete system from CME initiation to interaction with the upper atmosphere at Earth. A graphical user interface (GUI) has been developed to facilitate setup, execution, and visualization of model runs. This GUI has been enhanced to allow more complete visualization and model result analysis, including comparisons with data. Examples will be shown of the SWMF use through the GUI for a variety of space weather events.
SM41A-0311
A Robust MHD Scheme in Space Weather Modeling: A Carbuncle-Free HLL-type Solver
In the space weather modeling, it is indispensable to numerically reproduce severe plasma environments accurately. Therefore, shock capturing solvers for MHD have been applied to space MHD simulations so far. However, it has been found that, at hypersonic shock waves, high-resolution shock capturing solvers cause multi- dimensional numerical instabilities like the carbuncle phenomenon in neutral fluid (HD). In this study, numerical tests of the numerical instabilities at hypersonic MHD shocks are performed adopting typical high-resolution shock capturing solvers for MHD. Moreover, a robust multi-state HLL-type solver for MHD that can suppress the numerical instabilities is newly proposed. Numerical tests show that the numerical instabilities are generated in the high-resolution solvers, the Roe and the HLLD solvers, even for MHD. On the other hand, we find that newly developed solver, named as HLLD- solver, is free from the carbuncle instabilities. In addition, an application of the HLLD- solver to magnetospheric MHD simulations will be also presented.
SM41A-0312
Interlocked MHD modeling of the Launching and Propagation of Coronal Mass Ejections
Coronal mass ejections (CMEs) are not only one of the most energetic phenomena in the solar corona but also a key process in the space weather study. The numerical modeling of the launching and propagation of CMEs play a crucial role for space weather forecast. However, due to the vast difference in the spatial scale among solar, solar wind, and terrestrial plasmas, it is difficult and wasteful of numerical resource to simulate the whole process associated with the initiation and propagation of CMEs with a single simulation model. Therefore, we have recently developed a new numerical model, which can continuously calculate the whole process from the onset of CMEs to the geomagnetic impact of that, using the interlocking of several numerical models. The model consists of four numerical models; the solar active region model, the global corona model, the interplanetary space model, and the geospace model. In this paper, we explain the basic algorithm of the interlocked modeling, and show some important results obtained with it. First, we investigate the physical relationship between the solar magnetic field structure and the launching of CMEs. CMEs are ejections of a large amount of mass and magnetic flux, which result from eruptions of coronal magnetic field. Although the eruptions may cause solar flares, many observations show that all flares are not necessarily associated with CMEs, implying that there are some kinds of criteria. For example, it is likely that an eruption is confined by the ambient global magnetic field if the eruption is not large enough or if its direction of magnetic field is not appropriate. In order to examine the condition whether the eruption of coronal field can be launched as a CME, we performed a three-dimensional MHD simulation of an eruption in various global coronal magnetic fields, and succeeded to distinguish the condition capable of a CME. For example, an eruption of a small and strong magnetic field active region cannot be ejected as a CME due to magnetic tension force of anchored field. In this paper, we summarize the relationship between the key parameters for the ejection; the amount of magnetic flux and field directions. Second, our interlocked model is applied onto the CME event caused by the X-class flare occurring on the active region NOAA 10930 on December 13, 2006. The numerical experiment is initiated by the magnetic field model, which is constructed based on the magnetogram data observed by the Solar Optical Telescope (SOT) boarded on Hinode satellite, and the simulated variation of magnetic field and plasma state at the Earth orbit is compared with the in-situ observation by ACE. As a result, it is found that a relatively good agreement can be obtained between the simulation and observation if we parameterize the magnetic field on the CME launching site.
SM41A-0313
MHD Simulation of the Magnetic Storm on the Solar Flare Event in December 2006
It is an important subject on space weather study to make a physical model and to simulate a series of phenomena from origins of disturbances in the sun to the responses of magnetosphere and ionosphere in earth. Under the Creative Scientific Research "The Basic Study of Space Weather Prediction", we have tried such a series of modeling on the solar flare event in December 13-16 2006 and the geomagnetic storms. Following the space weather modeling (1) from the sun to solar wind, we present the space weather modeling (2) from the solar wind to the magnetosphere-ionosphere response in the earth. Large interplanetary disturbances were generated in association with the strong solar activity of X-class flare. Characteristic features of the event are two X-class flares on 12/13 and 12/14 in the interval of rather quiet solar activity, north-south fluctuation of IMF and a long duration of southward IMF from 12/14, arrival of a high speed solar wind during the time for southward IMF. Propagation of the disturbances from the sun to the earth is simulated by using 3D global solar wind model following evolution of solar disturbances. A 3D global MHD simulation of interaction between the solar wind and earth's magnetosphere is carried out by using the output of the 3D solar wind simulation. In the simulation, the high speed solar wind compresses the magnetosphere and magnetic reconnection occurs in the tail as long as at the dayside magnetopause for rapid southward turning of IMF from northward IMF and hot plasmas are injected around the geosynchronous orbit from plasma sheet. Moreover, the magnetosphere and ionosphere coupling and the ionosphere convection in the polar region are discussed in association with geomagnetic storms generated by the solar flare event.
SM41A-0314
A Comparison of Flare Forecasting Parameters Derived From Photospheric Magnetograms
A variety of researchers have proposed parameters for use in forecasting of solar flares. However, the parameters have been calculated from different data sources, and their performance has been judged based on various different criteria. We present here a systematic comparison of a small number of parameters which can be derived from the photospheric magnetic field, some of which characterize the photospheric field itself, and some which characterize the coronal magnetic topology. We compute the parameters for a collection of over 1200 vector magnetograms from the Imaging Vector Magnetograph at Haleakala, and judge their ability to forecast flares based on discriminant analysis, climatological skill scores, and the ability to provide an "all-clear" forecast.
SM41A-0315
Global Circulation and Impact of Plasmaspheric Plumes
We report results from the global circulation model of Lyon, Fedder, and Mobarry with an embedded model of the inner magnetosphere including the plasmasphere. The combination is used to initiate large numbers of representative protons on the geosynchronous orbit L shell, to assign particle weightings, to track their subsequent trajectories in the 3D fields. This permits us to study the global circulation of plasmaspheric plumes and to compare these with Polar observations from the dayside magnetopause region. A range of events is studied from an isolated period of SBz in the solar wind, to a large storm sequence. We consider effects on circulating plasmas reaching the dayside reconnection X-line, the population of the plasma sheet with ionospheric protons, and the generation of ring current pressure from this source, compared with solar wind, polar wind, and auroral wind sources. We find that the transient plasmaspheric plume source is large in terms of total fluence, but of modest proportions in terms of contribution to the ring current. Implications of this and other results for improved space weather modeling and prediction will be discussed. http://ipb.gsfc.nasa.gov/public/traj/
SM41A-0316
Ensemble Filters in Space Weather Forecasting
Ensemble filters have grown in popularity as a data assimilation tool for geophysical systems in recent years. This is largely due to their ability to handle highly nonlinear models without requiring detailed knowledge of the underlying dynamical equations. The Data Assimilation Research Testbed (DART) at NCAR is a powerful and flexible ensemble filter-based data assimilation framework whose well-defined programming interface and modular design provide a straight-forward means to apply advanced data assimilation algorithms to almost any dynamical model. We demonstrate several DART capabilities using both a relatively simple (but operationally relevant) radiation belt model, and by assimilating a limited portion of the Lyon-Fedder-Mobarry (LFM) magnetospheric state, namely electron precipitation generated at the MHD inner boundary.
SM41A-0317
Extreme flux enhancement of killer electrons due to the magnetosphere inflation during the recovery phase of geomagnetic storms
Extreme flux enhancement of outer radiation belt electrons was observed during the recovery phase of a large magnetic storm on 27-30 July 2004. The storm main phase is driven by a very fast magnetic cloud of ~1000 km/s associated with a coronal mass ejection (CME). The high-speed stream of ~600 km/s originated from a coronal hole follows the magnetic cloud and the coronal hole stream (CHS) is rarefied due to the speed difference between the CME and CHS. During the storm recovery phase, the magnetosphere is surrounded by the very low- density CHS, causing an inflation of the magnetosphere. It is found that such a combination of the CME and CHS can be one of the most dangerous solar wind structures for the outer radiation belt, and the associated very low dynamic pressure can cause the magnetosphere inflation during the storm recovery phase as an excellent magnetic confinement of killer electrons. We report our space weather modeling effort to reproduce the magnetosphere inflation effect using a radiation belt simulation and a 3D-MHD solar wind simulation based on IPS observation.
SM41A-0318
GPU Multi-Scale Particle Tracking and Multi-Fluid Simulations of the Radiation Belts
The properties of the radiation belts can vary dramatically under the influence of magnetic storms and storm-time substorms. The task of understanding and predicting radiation belt properties is made difficult because their properties determined by global processes as well as small-scale wave-particle interactions. A full solution to the problem will require major innovations in technique and computer hardware. The proposed work will demonstrates liked particle tracking codes with new multi-scale/multi-fluid global simulations that provide the first means to include small-scale processes within the global magnetospheric context. A large hurdle to the problem is having sufficient computer hardware that is able to handle the dissipate temporal and spatial scale sizes. A major innovation of the work is that the codes are designed to run of graphics processing units (GPUs). GPUs are intrinsically highly parallelized systems that provide more than an order of magnitude computing speed over a CPU based systems, for little more cost than a high end-workstation. Recent advancements in GPU technologies allow for full IEEE float specifications with performance up to several hundred GFLOPs per GPU and new software architectures have recently become available to ease the transition from graphics based to scientific applications. This allows for a cheap alternative to standard supercomputing methods and should increase the time to discovery. A demonstration of the code pushing more than 500,000 particles faster than real time is presented, and used to provide new insight into radiation belt dynamics.
SM41A-0319
Solar Data Assimilation Engine for Ionospheric Forecasts
The Space Weather Modeling System (SWMS) is a Battlespace Environments Institute (BEI) project that couples space environment models together under the Earth System Modeling Framework, while ensuring that the component models are scalable and portable. BEI is sponsored by the High Performance Computing Modernization Office and managed by Air Force Weather Agency and Naval Research Laboratory. The Hakamada-Akasofu-Fry version 2 (HAFv2) solar wind model and the Global Assimilation of Ionospheric Measurements (GAIM) model are the first two coupled components in the SWMS. Serving as a data assimilation engine, the HAFv2 model uses solar observations to prepare its initial solar wind conditions. Then, the HAFv2 internal algorithms and the initial conditions determine the present and future states of the solar wind conditions at Earth. The outputs of HAFv2 are provided to GAIM to forecast the time-dependent energy input into the high- latitude ionosphere. This presentation describes how the HAFv2 model is being used as a solar data assimilation engine for producing forecasts of solar wind parameters, that then serve as inputs to drive GAIM and other near-Earth space environment models. The overarching goal is to extend the lead time and skill of forecasts of space weather conditions and their corresponding impacts on operational customers.
SM41A-0320
A new simulation tool for coupling global magnetohydrodynamic models to ionosphere- thermosphere models
We report on a newly developed simulation tool that provides a framework for coupling global magnetohydrodynamic (MHD) models to models of the ionosphere-thermosphere. This simulation code combines two main capabilities. Firstly, it serves as an interface between the physical models by implementing the necessary grid interpolation manipulations using generic grid-independent algorithms. Secondly, it solves for the ionospheric electrostatic potential using the well-established approach based on current continuity. The algorithm for the numerical solution of the elliptic equation is very flexible and allows virtually arbitrary choice of a solution grid and boundary conditions. We demonstrate the capabilities of this simulation code by coupling the parallelized version of the Lyon-Fedder-Mobarry (LFM) global MHD model to two different ionosphere-thermosphere models developed at NCAR, TING and TIEGCM. To this end, we choose an event that has previously been studied using the conventional LFM model and compared to Iridium and DMSP observations of the ionospheric field-aligned currents and convection pattern. We compare the results obtained by coupling to the two ionosphere-thermosphere models as well as by using the empirical model of the ionospheric conductance implemented in the conventional LFM model.
SM41A-0321 [WITHDRAWN]
The use of long-time EISCAT data series for improving ionospheric corrections models - First results
Plasma turbulence in the ionosphere is considered of significant importance for communication, navigation, and surveillance systems based on trans-ionospheric radio links, since radio scintillation caused by electron density irregularities in the ionosphere may result in signal degradation and outage. In addition, some remote sensing techniques may also experience severe disturbances. With the help of ionospheric models it is possible to correct for these disturbances up to certain levels. However, these models do not represent very well the real ionosphere at high latitudes, since the models have been built with the use of empirical data obtained at mid- and low-latitudes. Thus, one of the purposes of Work package 10 of the EISCAT 3D project is to investigate the feasibility and utility of employing long incoherent scatter radar data time series to improve the integrity of trans- ionospheric radio communication signals, especially at high latitudes. One critical area in which this contribution can be important is in improving the ionospheric models used by the GPS and the future Galileo global navigation satellite systems. We present the first results of comparisons between ionospheric models and long-time EISCAT data series and suggest ways for further progress of this part of work package 10 within the EISCAT 3D project.
SM41A-0322
Radio tomography of the ionosphere: Analysis of an under-determined, ill-posed inverse problem, and regional application
After an analysis of the forward and inverse problems of radio tomography, a time varying three-dimensional imaging method of the ionosphere through GPS slant TEC data is described, justified and applied at regional scale. Our approach is based on local basis parametrisation of electron density, and constrained by NeQuick ionosphere model and its space gradients. Our inversion scheme is fundamentally different from the data assimiliation approach because it is not based on a physical ionosphere model. However, because our imaging method is able to retreive small scale ionosphere features in properly resolved volumes, these two approaches appear to be very complementary. The preliminary results obtained with european GPS receiver data validate the method and its stability, even if a lot of improvements are still possible on the algorithm and a careful validation of inverted models by independent data is still necessary. http://w3.dtp.obs- mip.fr/~garcia/iono.html
SM41A-0323
Skill Scores for Ionospheric Modeling
This paper examines two ionospheric models, Themosphere Ionosphere Nested Grid (TING) and International Reference Ionosphere (IRI), and compares them to each other and to ionosonde data from the SPIDR data base for the time period of July 1995 from the 4th through the 17th. We make this comparison by calculating standard skills scores. TING had a much larger dynamic range than IRI and overall both were bad fits to the data being at times as far off as 20% or more.
SM41A-0324
Coupling of a Global Ionosphere-Plasmasphere Module to an Extended Global Atmosphere Model
As part of the efforts within the Integrated Dynamics through Earth's Atmosphere (IDEA) project, a global ionosphere-plasmasphere module is coupled to an extended global atmosphere model. The extended global atmosphere model is based on the NOAA/NCEP's GFS (Global Forecast System), which is extended to about 600 km in the vertical, along with new physical and chemical processes/parameterizations that are important for the upper mesosphere and thermosphere. These parameterizations include CO2 cooling, molecular diffusion, and photochemistry, etc. The extended GFS also includes effects of ionosphere plasmas, e.g., Joule heating and ion drag. The global ionosphere-plasmasphere module, denoted as GIP, is based on the CTIP (Coupled Thermosphere- Ionosphere-Plasmasphere) model. While the CTIP model uses the modified dipole geomagnetic field, the GIP module uses the IGRF (International Geomagnetic Reference Field) geomagnetic field. It solves the continuity equations and the steady-state momentum equations for densities and velocities of O+ and H+ ions along the geomagnetic flux tubes using the finite difference schemes. These flux tubes have a fixed geographic base height of 90 km and maximum heights up to about 10,000 km. GIP also has an option of solving the quasi- steady-state energy equations for temperatures of O+ and H+ ions and electrons. GFS is a parallel model using MPI (Message Passing Interface) while GIP is a serial code module. In coupling the GIP module to the extended GFS, the neutral atmosphere temperature, velocity, and O, O2 and N2 densities, etc. from GFS are collected onto one computational node and then interpolated to the GIP grids as input to GIP. Output from the GIP module, such as ion velocities, ion and electron temperature and densities, etc, are then interpolated to the GFS grids and scattered back to the corresponding GFS computational nodes. In the future, the ESMF (Earth System Modeling Framework) libraries and regridding utilities will be used for coupling GFS with GIP. This presentation will focus on analyses of results from one-way coupling, i.e., forcing of GIP by the extended GFS.
SM41A-0325 [WITHDRAWN]
Modeling Ionospheric HF/VHF Radio-Wave Absorption due to Solar Energetic Proton Events
Abstract Simple, one-parameter, algorithms have been applied to the observed energetic proton flux as provided by the GOES series of satellites to yield estimates of the high latitude HF and VHF radio-wave absorption for both day and night respectively. The twilight response is obtained as a bi-linear function of the solar zenith angle at the observation positions, and the latitude dependence of the absorption region near the edge of the absorbing region (the polar caps) are estimated from extant models of geomagnetic cut-offs and their dependence on geomagnetic activity. The approximate inverse square frequency dependence of ionospheric absorption is used to translate across the HF/VHF range and predictions of the minimum duration of events are determined. Calculations of the polar cap absorption of HF radio waves have been performed for eleven larger Solar Energetic Proton (SEP) events during the period from 1992 through 2002 and the results compared to observations of 30 MHz Riometers operated by the AFGL and located at Thule, Greenland. While discrepancies between the estimated and observed absorption using these procedures occur, especially at low absorption levels, this model has operational value in view of its simplicity and its being the only extant model, to our knowledge, which treats solar-illumination, geomagnetic cutoff variation, and frequency effects, at least to first order. Specimen graphical representations of the north and south polar caps illustrate the output of the model for the peak of the 12 December 2006 solar proton event. Given sufficient interest, improvements to the methodology used here are practicable and could be expected to achieve accuracies to the order of 25% or better.
SM41A-0326
Probability Distributions of Electron Precipitation at High Magnetic Latitudes
Starting in the early 1980s investigators at the Air Force Research Laboratory have sought to exploit information contained in the massive database accumulated by the electron and ion spectrometers on spacecraft of the Defense Meteorological Satellite Program (DMSP). One objective has been to characterize particle precipitation at high latitudes by determining the average properties of precipitating electrons as functions of magnetic latitude (MLat), magnetic local time (MLT) and the level of geomagnetic activity specified by the Kp index. Parameters used in the present analysis, integral number flux, integral energy flux, and average energy of precipitating electrons are widely used in the space weather community to estimate auroral ionospheric conductance. In the original Hardy-85 model data from the SSJ3 sensor on DMSP F2 and F4 were used to calculate "average" quantities for given MLat-MLT-Kp bins, assuming that sampled populations were reasonably singular and normally distributed. The current investigation tests these assumptions using the much larger SSJ4 data set from DMSP F7 though F15. We find that at all local times and latitudes probability distributions for detecting any of the three parameters is always lognormal and often nonsingular. Lognormal distributions have inherent positive skews with the average value larger than the most probable value. Consequently, ionospheric conductance maps based on average values provide conductance values that are too high. Using the most probable value of each distribution would provide a better estimate of the conductivities but given the lognormal and nonsingular character of the distributions even the most probable value is an unlikely predictor of actual conditions.
SM41A-0327
The Typical Auroral Substorm: A Bifurcated Oval
Utilizing global auroral images obtained by Polar VIS Earth Camera we have analyzed the UV emissions from 116 classical auroral substorms. Average auroral emission patterns were deduced for 11 time steps of the substorm covering 20 min prior to the onset until well into the recovery phase. These average patterns were based on a three step normalization technique, one temporal and two spatial. Based on this study we can make the following conclusions. The normalization technique is highly efficient in minimizing the smearing of key features in the auroral emission pattern. We can conclude that even though the individual events may vary significantly in intensity, size, position and lifetime all have the same key emission features and can be represented by our average patterns. Thus our normalization results quantitatively validate the Akasofu assumption that key auroral features exist in the bulge-type auroral substorm. After the onset the auroral oval is clearly bifurcated consisting of two components: the oval aurora in the latitude range of the pre-onset oval, and the bulge aurora, which emerges out of the oval, expanding poleward and both east and west in MLT. Due to the pronounced difference in spatiotemporal behavior of the two auroral components we speculate that they are quasi independent, and thus the sources of electrons must also be independent.
SM41A-0328
Specification of Ionospheric Dynamics at Low- and Mid-Latitude Using the Global Assimilation of Ionospheric Measurements (GAIM) Model
It is well known that the ionosphere-plasmasphere-thermosphere system at low and middle latitudes is strongly coupled, and therefore, a study of ionospheric dynamics must take into account the interaction between the different domains. As shown by meteorologists and oceanographers, a powerful way of modeling complex systems is with the use of data assimilation models. At USU, we have developed two GAIM data assimilation models with different complexity and both provide global and regional specifications of the 3-dimensional ionosphere-plasmasphere plasma densities. One of these models is our Full Physics-Based Kalman filter data assimilation model, which is based on a physics-based model for the ionosphere-plasmasphere system, a diverse array of data sources, and an ensemble Kalman filter data assimilation technique. This model covers the ionosphere-plasmasphere system from 90 to 30,000 km altitude and includes 6 ion species (NO+, N2+, O2+, O+, He+, H+). The strength of this model is that in addition to the global and regional 3-D ionosphere electron density distribution it also self-consistently determines the corresponding ionospheric drivers, including the thermospheric neutral winds and composition and the electric fields. The model can assimilate a variety of different data types, including GPS/TEC from up to 1000 ground receivers, in situ Ne from several DMSP satellites, bottomside Ne profiles from tens of ionosondes, and radio occultation data from the six COSMIC satellites. We have used this model to study the dynamics of the low- and mid-latitude ionosphere on a case-by-case basis to determine the various driving forces and to study their temporal and spatial variability. We will present examples of the ionospheric and driver variability obtained from our model and compare the results with independent data.
SM41A-0329
Pairs of Solar Wind-Magnetosphere Coupling Functions: Combining a Merging Term with a Pressure Term Works Best
We have investigated the behavior of 10 different characterizations of the magnetosphere, including traditional geomagnetic indices such as Kp and AE, and also using satellite based data such as global auroral power from Polar UVI, cusp latitude from DMSP, and magnetotail stretching from GOES. Multi-year data (typically a solar cycle) was studied at relatively high cadence (usually 1 hr) to provide better statistical consistency. Simple two parameters best fits to a wide variety of candidate solar wind coupling functions were considered, with no hidden variables or adjustable parameters. Previously we showed that the best performing coupling functions all were estimators of the global merging rate, with the best results from dFMP/dt =v4/3BT2/3sin8/3(tc/2). Here we investigate the best performing viscous candidates, and the best performing pairs of solar wind coupling functions, in predicting these same 10 characterizations of the magnetosphere. The top viscous functions all are closely related to the solar wind pressure, but n1/2v2 performs best, accounting for 22.3 percent of the variance, versus 14.7 for v and 12.5 for p. Altogether we considered 32 different candidate solar wind magnetosphere coupling functions, and all 32 x 32 = 1024 possible pairs of functions. Because of the large number of function pairs, some statistical fluctuations are expected. Nonetheless, certain patterns emerged. The best performing overall pair (predicting 60.6 percent of variance across all indices) was dFMP/dt coupled with n1/2v2, i.e., the best individual merging and best viscous terms make the best combination. All the top pairs consisted of one merging and one viscous term. Combining two estimators of the merging rate always has less predictive power. However any merging term, such as Bs, vBs, or EKL, when coupled with almost any pressure term, such as v, p, n1/3v2, p1/2, etc, performs reasonably well, with the merging term accounting for much the greater variance.
SM41A-0330
Evaluation of Solar-Wind Magnetosphere Coupling Functions Using the WINDMI Model
Solar-wind Magnetosphere coupling functions from Newell et. al. 2007 are used as inputs into the WINDMI physics based nonlinear dynamical model of the Earth's nightside magnetosphere. The coupling functions are scaled to the rectified vBs coupling function of Burton et. al. 1975 for this purpose. The outputs of the model are the AL and Dst indices that are compared to the indices measured on the ground. The physical parameters of the model are optimized using a genetic algorithm (GA) computation scheme for each different input using the October 3-7 2000 and April 15-24 2002 Geomagnetic Storm Datasets. The optimization of the model parameters is performed over 3-6 hour intervals to incorporate the changing physical state of the nightside magnetosphere. The predictive capability of each input and the AL and Dst index are compared through using the average relative variance (ARV) and the cross-correlation (COR) measures. The coupling functions are ranked according to performance against the ARV and COR measures. The physical parameters of the WINDMI model obtained from the optimization is also presented. The best performing coupling function will be used as part of a hybrid physics black-box space weather prediction tool in future.
SM41A-0331
What Can We Learn about Geoffectiveness of Solar Wind Turbulence?
The interest of space weather and its forecasts grow and studies of geoeffective processes in coupled Sun - Solar wind - Magnetosphere - Ionoshere system rises. Recent results in understanding of the dynamical processes within this brought new questions in role of the fluctuations in solar wind plasma. In this paper we asked question whether these fluctuations do not play one of the important roles in geoeffective processes beside all these well-known parameters studied earlier and conditions which lead to the exchanges of mass, energy and momentum via reconnection processes. We examined changes in properties of magnetospheric disturbances characterized by Symh index by changes in properties of solar wind plasma and magnetic field fluctuations.
SM41A-0332
Forecasting geomagnetic activity indices
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 and Dst 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 hr ahead; (2) a model with the same input as model 1 and predicts Kp 4 hr ahead; and (3) a model that inputs only solar wind parameters and predicts Kp 1 hr 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. Similar Dst models were developed. 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).
SM41A-0333
Statistical modeling of storm-level Kp occurrences: Solar-cycle modulation
We consider the non-stationary, statistical modeling of the occurrence in time of large Kp geomagnetic storms over the course of multiple solar cycles. Previous work showed that wait times between storms can be represented by an exponential density function, consistent with the realization of a Poisson process. Here we also assume a Poisson process, but to account for solar-cycle modulation of storm likelihood, we assume an occurrence rate given by a parametric constant plus a simple sinusoidal function of time. Parameter estimation is accomplished using maximum likelihood, yielding good fits to the Kp data. We find that the relative phase between storms and sunspots depends on storm size. We quantify previous observations that small storms tend to occur during the declining phase of the solar cycle, whilst large storms tend to occur very close to solar maximum. We predict average wait time between storms and the storm occurrence rate up through the year 2018. http://geomag.usgs.gov
SM41A-0334
Structure and Dynamics of the Storm-Time Inner Magnetosphere: A new View Emerging From the Dynamical Empirical Geomagnetic Field Model With High Spatial Resolution
Modeling the storm-time inner magnetosphere is central to space weather science. At the same time, it is particularly difficult using the first principle approaches because of significant non-MHD effects. A complementary approach may be data-based modeling, including empirical models of the magnetospheric magnetic field. Until recently these models were limited in their spatial resolution because they were constructed of a limited number of special modules representing major magnetospheric current systems. A new approach, based on a high- resolution extensible approximation for the field of equatorial currents and making use of large sets of spacecraft data that became available in recent years, is shown to dramatically improve the resolution of empirical geomagnetic field models [Tsyganenko and Sitnov, 2007]. However, increasing the spatial resolution may limit the resolution in time, because to get a good image one needs a long enough exposure, providing sufficiently dense coverage of the magnetosphere by the data points. We show that the problem can be resolved using the nearest-neighbor approach, in which the spatial structure of each new state of the magnetosphere is described by fitting the empirical model with a local subset of the basic set of data. This subset includes both the actual data available for the given state of the magnetosphere and data for other states (e.g., similar phases of other storms), neighboring the present state in the space of global parameters, such as Sym-H index, solar wind electric field, and their time derivatives. The new dynamical model reveals important spatio-temporal features of magnetospheric storms, such as the peak density of the ring current in the postmidnight sector during the main phase, consistent with IMAGE data [Brandt et al., 2002] and maximum depression of the equatorial magnetic field in the premidnight sector, consistent with earlier results [Ohtani et al., 2007]. It also predicts new effects, such as the strong erosion of the dayside part of the ring current at the early main phase and its enhancement near the Sym-H minimum in a broad area in the evening sector extending from the geostationary orbit to the magnetopause and adjacent to the plume region of the plasmasphere.
SM41A-0335
Surface Charging Application Tests for Geosynchronous Spacecraft
The testing of a geosynchronous spacecraft surface charging application that combines the charged particle environment (~ 1 eV to 200 keV electron and proton fluxes) of the Magnetospheric Specification Model (MSM) with algorithms from the NASCAP-2K surface charging program is described. Spacecraft frame charging (chassis potential) is determined from low energy ion data collected by the Charge Control System (CCS) on a DSCS III B- 7 spacecraft at 307° E. Longitude. Several simple descriptions of satellite geometry and materials are employed, including one which approximates features of the DSCS satellite [i.e., Mandell and Cooke, AIAA-2004-986, 42nd AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, Jan. 5-8, 2004]. Preliminary tests compared modeled and observed chassis potentials for three days when observed peak charging levels ranged from -200 to -600 volts [Hilmer et al. (2005), EOS Trans. AGU, 86(52), Fall Meet. Suppl., Abstract SM41A-1169]. While the electron and proton spectra generated by the MSM proved to be suitable for the charging calculation, the MSM does not produce all of the low energy electrons (< 20 eV) usually present in geosynchronous orbit to keep spacecraft from charging positive so only negative charging is assumed. Frame charging details vary greatly with MSM input parameter selection. The charging application works best with MSM spectra generated using the input parameter set that statistically produces the best electron fluxes in the midnight-dawn local time sector where surface charging is most often observed. Comparisons in the present study will concentrate on utilizing MSM particle fluxes generated using this "best set" of the input parameters. These tests will help us refine the MSM and NASCAP-2K algorithm configurations needed to best address spacecraft surface charging.
SM41A-0336
Evaluation of Radiation Belt Space Environments for Internal Charging Analyses
A variety of static electron radiation belt models, space environment prediction tools, and energetic electron datasets are used by spacecraft designers and operations support personnel as internal charging code inputs. These inputs are used to evaluate electrostatic discharge risks in space systems due to exposure to relativistic electron environments. Evaluating the environments inputs is often accomplished by comparing whether the data set or forecast tool reliability predicts the measured electron flux (or fluence over a given period) for some chosen period. While this technique is useful as a model metric, it does not provide the information necessary to evaluate whether short term deviances of the predicted flux is important in the charging evaluations. In this paper, we use a 1-D internal charging model to compute electric fields generated in insulating materials as a function of time when exposed to relativistic electrons in the Earth's magnetosphere. The resulting fields are assumed to represent the 'true' electric fields and are compared with electric field values computed from relativistic electron environments derived form a variety of space environment and forecast tools. Deviances in predicted fields compared to the 'true' fields which depend on insulator charging time constants will evaluated as a potential metric for determining the importance of predicted and measured relativistic electron flux deviations over a range of time scales.
SM41A-0337
Using Space Weather Variability in Evaluating the Radiation Environment Design Specifications for NASA'S Constellation Program
NASA's Constellation program, initiated to fulfill the Vision for Space Exploration, will create a new generation of vehicles for servicing low Earth orbit, the Moon, and beyond. Space radiation specifications for hardware design are necessarily conservative to assure system robustness for a wide range of space environments. Spectral models of solar particle events and trapped radiation belts are necessary for the design requirements of total ionizing radiation dose, dose rate effects, displacement damage, and single event effects. This presentation first describes the rationale in using the spectra to establish the environment design specifications. We then compare the variability within the spectral models to evaluate the applicability and potential vulnerabilities to extreme space weather events.
SM41A-0338
SOTERIA: SOlar-TERrestrial Investigations and Archives
The SOTERIA project realizes a wide synergy in the fields of solar- space- and geophysics to achieve a higher level of processed data and better understanding of solar and space events having terrestrial impact. The study of these events has an increasing importance with the increasing amount of technical equipment (e.g. power lines and telecommunication satellites) that can be damaged during these events. The project mobilizes more than 50 experts and significant resources from EU (including new EU member states) for the process, analysis, and interpretation of a large set of relevant data of more than 20 satellites (including 5 ESA missions) and the complementing ground-based data. It aims at providing better data bases and new methods to access and analyze them. The new databases go beyond the present state-of-the-art in details, and their on-line publication facilitates fast access to the open data acquired during these missions. The data will be further connected with new theoretical and simulation models and their usage will provide the expected impact of improvement of the scientific results that can be obtained from collected space data. The outputs will provide a long-term dissemination contributing to a higher level space monitoring system, and more reliable space weather forecast ability.