SA43B-01 13:45h
Solar flare evolution predictions for operations
Solar spectral irradiances shortward of 31 nm, i.e., XUV (0.1 - 10 nm) and some EUV (10 - 31 nm) irradiances, are the dominant source of 180-450 km altitude thermospheric heating and F1 and F2 ionospheric layer photoionization. These spectral irradiances are mostly absorbed by atomic oxygen which is the dominant species in this altitude region at most levels of solar activity. Wavelengths in this spectral range are highly variable during solar flares and, at the shortest wavelengths, can increase by up to two orders of magnitude in a few minutes from flare start to flare peak. There currently is not a consistent method for operational solar XUV and EUV flare spectral, magnitude, and duration estimation although the geoeffectiveness of these characteristics on short time scales is significant. We report on three new integrated irradiance indices, Xb10, Xhf, and X10.7, that provide space weather users the knowledge of flare spectral characteristics, magnitude, and duration once a flare has started. The solar X-ray flux reported by NOAA/SEC, specifically the GOES one-minute 0.1-0.8 nm band XUV 0.1-0.8, are irradiance measurements that combine flaring and non-flaring sources. We separate the flare and background components to create X-ray indices that are geoeffectively-relevant. In order to provide flare magnitude and duration once it has started, we demonstrate a flare model using the correlation between dXhf/dt, flare magnitude, and duration. The time rate of change of Xhf, i.e., dXhf/dt, is obtained after separating the Xb10 background so that the actual flare start time, rise phase, and decay shape can be determined. Additionally, the daily Xb10 can be more useful than the daily mean value for comparing solar X-ray variability to other daily solar indices. Results for the October-November 2003 storm period are presented.
http://SpaceWx.com
SA43B-02 14:00h
Forecasting and Real-Time Diagnostics of Solar Coronal Mass Ejections
We discuss an operational, fully automated, algorithm to follow the dynamical evolution and the buildup of magnetic instabilities that give rise to coronal mass ejections (CMEs) in solar active regions. The tool relies on vector magnetic field measurements of the active region photosphere / chromosphere and performs the following tasks: (1) resolution of the 180-degree ambiguity in the magnetic field measurements and preparation for further use, (2) calculation of the magnetic forces and electric currents in the active region photosphere/chromosphere, (3) reconstruction of a magnetohydrodynamic velocity field corresponding to the measured magnetic field to calculate the buildup rate of the magnetic helicity in the active region atmosphere, and (4) estimation of the total magnetic helicity in the active region corona. We present examples showing that (I) flare- and CME-prolific active regions have much higher magnetic helicity, stronger magnetic forces and more intense cross-field electric currents than quiescent active regions, and (II) the magnetic helicity, chirality, magnetic flux, and magnetic energy of a CME can be calculated in real time from the results of the algorithm before and after the CME. As a result, we can both identify potentially eruptive areas on the visible solar disk and provide detailed quantitative diagnostics of the resulting CMEs. Additional work is required to predict the geoeffectiveness of these CMEs. For the algorithm to be useful we need full-disk, ideally uninterrupted, coverage of the solar magnetic field vector. This information will be available in a few years with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO; launch 2008). At the moment, full-disk vector magnetograms will be provided by the ground-based Vector Spectro-Magnetograph (VSM) of the Synoptic Optical Long-Term Investigation of the Sun (SOLIS) telescope. We will utilize the SOLIS vector magnetograms as soon as they become available.
SA43B-03 14:10h
Operational warning of interplanetary shock arrivals using energetic particle data from ACE: Real-time Upstream Monitoring System
We report on an operational system which provides advance warning and predictions of arrival times at Earth of interplanetary (IP) shocks that originate at the Sun. The data stream used in our prediction algorithm is real-time and comes from the Electron, Proton, and Alpha Monitor (EPAM) instrument on NASA's Advanced Composition Explorer (ACE) spacecraft. Since locally accelerated energetic storm particle (ESP) events accompany most IP shocks, their arrival can be predicted using ESP event signatures. We have previously reported on the development and implementation of an algorithm which recognizes the upstream particle signature of approaching IP shocks and provides estimated countdown predictions. A web-based system (see (http://sd-www.jhuapl.edu/UPOS/RISP/index.html) combines this prediction capability with real-time ACE/EPAM data provided by the NOAA Space Environment Center. The most recent ACE data is continually processed and predictions of shock arrival time are updated every five minutes when an event is impending. An operational display is provided to indicate advisories and countdowns for the event. Running the algorithm on a test set of historical events, we obtain a median error of about 10 hours for predictions made 24-36 hours before actual shock arrival and about 6 hours when the shock is 6-12 hours away. This system can provide critical information to mission planners, satellite operations controllers, and scientists by providing significant lead-time for approaching events. Recently, we have made improvements to the triggering mechanism as well as re-training the neural network, and here we report prediction results from the latest system.
http://sd-www.jhuapl.edu/UPOS/RISP/index.html
SA43B-04 14:25h
Linking a Solar Wind Model With an Empirical Prediction Model of MeV Electron Intensity at the Geostationary Altitude
Prediction of MeV electron intensity at the geostationary altitude constitutes an integral part of space weather forecast. Several techniques have been developed to forecast MeV electron intensity at this altitude. In this work, we present a semi-empirical technique to forecast the daily average MeV electron intensity at geostationary orbit with linkage to a solar wind model. The accuracy of the prediction procedure will be determined as a whole as well as for each of the two components of this prediction scheme. Comparison of this technique with others will also be discussed.
SA43B-05 14:40h
Critical Temperature for the Onset of Spacecraft Charging at Geosynchronous Altitudes in a `Cut-Off' Maxwellian Space Plasma
Spacecraft charging at geosynchronous altitudes occurs more likely on the dawn side than on the dusk side of midnight. The conventional wisdom says that hot electrons drift to the morning side because of convection and the Earth's magnetic field curvature and gradient. We point out that there is a supplementary reason: the cutoff energy of the electron distribution is lower on the dusk side than on the dawn side of midnight. We have derived a critical temperature formula for a `cutoff' Maxwellian distribution and obtained the critical temperature values for various surface materials at normal and isotropic incidence of ambient electrons with the cutoff energy as a variable parameter. Lowering the cutoff energy raises the critical temperature.
SA43B-06 14:55h
Realtime magnetosphere simulation at CCMC
The 24/7 realtime simulations running at the CCMC have been implemented three years ago and have seen many challenges during the development. Improvements during the years include the addition of data postprocessing steps such as the computation of the polar cap boundary, the current conditions at various satellite positions, and the provision of overwiev plots of recent ionospheric potentials. A major milestone was the addition of the Fok ring current model using the MHD results to the simulation. This paper describes the challenges encountered during the setup of the real time run system and outlines the benefits to operational space weather forecasting today and in the future.
SA43B-07 15:10h
Space Environmental Anomalies Expert System, Real-Time (SEAESRT)
The Aerospace Corporation has developed a real-time version of its Space Environmental Anomalies Expert System. Given that a geosynchronous vehicle has experienced an anomaly, SEAESRT analyzes 5 different space environment effects that might have caused the anomaly. We use cumulative probability distributions obtained from historical observations to develop situational awareness levels for real-time data. We presently use the 97th percentile to indicate the severe level for each parameter, based on the 97th percentile of Kp, which is Kp$>$7. SEAESRT provides confidences between +1.0 (Definitely For) to -1.0 (Definitely Against) for each environmental effect being the possible cause of the anomaly. We have also developed a front end and graphical user interface to automatically manage the available environment measurements and prepare the inputs to SEAESRT. This new system includes heads-up status displays as well as the ability to ingest new data in real-time either using the GUI or using batch programs.
SA43B-08 15:25h
US-TEC: A new Data Assimilation Product from the Space Environment Center Characterizing the Ionospheric Total Electron Content
The potential of data assimilation for operational numerical weather forecasting has been appreciated for many years. For space weather it is a new path that we are just beginning to explore. With the emergence of satellite constellations and the networks of ground based observations, sufficient data sources are now available to make the application of data assimilation techniques a viable option. The first ionospheric space weather product to be launched by SEC utilizing data assimilation techniques will be available in the fall of this year. The product, US-TEC, characterizes the ionospheric total electron content. Extensive validation has quantified the differential and absolute accuracy of the product, which shows great promise for application to GPS users. This is the first step along a path that will likely lead to major improvement in space weather forecasting, paralleling the advances achieved in meteorological weather forecasting.