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Sandberg I.,Institute of Accelerating Systems and Applications | Sandberg I.,National and Kapodistrian University of Athens | Sandberg I.,National institute for astrophysics | Jiggens P.,European Space Agency | And 3 more authors.
Geophysical Research Letters | Year: 2014

Solar proton flux measurements onboard Geostationary Operational Environmental Satellites (GOES) are of great importance as they cover several solar cycles, increasingly contributing to the development of long-term solar proton models and to operational purposes such as now-casting and forecasting of space weather. A novel approach for the cross calibration of GOES solar proton detectors is developed using as reference energetic solar proton flux measurements of NASA IMP-8 Goddard Medium Energy Experiment (GME). The spurious behavior in a part of IMP-8/GME measurements is reduced through the derivation of a nonlinear intercalibration function. The effective energy values of GOES solar proton detectors lead to a significant reduction of the uncertainties in spectra and may be used to refine existing scientific results, available models, and data products based on measurements over the last three decades. The methods presented herein are generic and may be used for calibration processes of other data sets as well. Key Points Calibration of NOAA GOES/EPS energy proton channels Correction of NASA IMP-8/GME data set Novel generic calibration techniques are presented ©2014. American Geophysical Union. All Rights Reserved.


Sandberg I.,National institute for astrophysics | Sandberg I.,National and Kapodistrian University of Athens | Daglis I.A.,National and Kapodistrian University of Athens | Daglis I.A.,National institute for astrophysics | And 5 more authors.
IEEE Transactions on Nuclear Science | Year: 2014

In this work we present the development of the electron Slot Region Radiation Environment Model (e-SRREM). e-SRREM is a data-based statistical model which has been built on fifteen years of electron flux measurements. The model describes the trapped electron radiation in a region that includes the slot region between the inner and the outer electron radiation belts. The model provides energetic electron fluxes with their uncertainties determined by confidence levels for user-defined mission orbit and duration. First comparisons of e-SRREM with the AE8 and International Radiation Environment Near Earth (IRENE) AE9 models show that the aforementioned models underestimate the electron flux levels along highly elliptic orbit that crosses the slot region. Extensive testings and comparisons will follow in future work. © 2013 IEEE.


Yu Ganushkina N.,Finnish Meteorological Institute | Yu Ganushkina N.,University of Michigan | Amariutei O.A.,Finnish Meteorological Institute | Welling D.,University of Michigan | Heynderickx D.,DH Consultancy
Space Weather | Year: 2015

We present the nowcast model for low-energy (< 200 keV) electrons in the inner magnetosphere, which is the version of the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) for electrons. Low-energy electron fluxes are very important to specify when hazardous satellite surface-charging phenomena are considered. The presented model provides the low-energy electron flux at all L shells and at all satellite orbits, when necessary. The model is driven by the real-time solar wind and interplanetary magnetic field (IMF) parameters with 1 h time shift for propagation to the Earth's magnetopause and by the real time Dst index. Real-time geostationary GOES 13 or GOES 15 (whenever each is available) data on electron fluxes in three energies, such as 40 keV, 75 keV, and 150 keV, are used for comparison and validation of IMPTAM running online. On average, the model provides quite reasonable agreement with the data; the basic level of the observed fluxes is reproduced. The best agreement between the modeled and the observed fluxes are found for <100 keV electrons. At the same time, not all the peaks and dropouts in the observed electron fluxes are reproduced. For 150 keV electrons, the modeled fluxes are often smaller than the observed ones by an order of magnitude. The normalized root-mean-square deviation is found to range from 0.015 to 0.0324. Though these metrics are buoyed by large standard deviations, owing to the dynamic nature of the fluxes, they demonstrate that IMPTAM, on average, predicts the observed fluxes satisfactorily. The computed binary event tables for predicting high flux values within each 1 h window reveal reasonable hit rates being 0.660-0.318 for flux thresholds of 5·104-2·105 cm-2 s-1 sr-1 keV-1 for 40 keV electrons, 0.739-0.367 for flux thresholds of 3·104 -1·105 cm-2 s-1 sr-1 keV-1 for 75 keV electrons, and 0.485-0.438 for flux thresholds of 3·103 -3.5·103 cm-2 s-1 sr-1 keV-1 for 150 keV electrons but rather small Heidke Skill Scores (0.17 and below). This is the first attempt to model low-energy electrons in real time at 10 min resolution. The output of this model can serve as an input of electron seed population for real-time higher-energy radiation belt modeling. ©2014. American Geophysical Union. All Rights Reserved.


Ganushkina N.Y.,University of Michigan | Amariutei O.A.,Finnish Meteorological Institute | Welling D.,University of Michigan | Heynderickx D.,DH Consultancy
Space Weather | Year: 2015

We present the nowcast model for low-energy (<200 keV) electrons in the inner magnetosphere, which is the version of the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) for electrons. Low-energy electron fluxes are very important to specify when hazardous satellite surface-charging phenomena are considered. The presented model provides the low-energy electron flux at all L shells and at all satellite orbits, when necessary. The model is driven by the real-time solar wind and interplanetary magnetic field (IMF) parameters with 1 h time shift for propagation to the Earth's magnetopause and by the real time Dst index. Real-time geostationary GOES 13 or GOES 15 (whenever each is available) data on electron fluxes in three energies, such as 40 keV, 75 keV, and 150 keV, are used for comparison and validation of IMPTAM running online. On average, the model provides quite reasonable agreement with the data; the basic level of the observed fluxes is reproduced. The best agreement between the modeled and the observed fluxes are found for <100 keV electrons. At the same time, not all the peaks and dropouts in the observed electron fluxes are reproduced. For 150 keV electrons, the modeled fluxes are often smaller than the observed ones by an order of magnitude. The normalized root-mean-square deviation is found to range from 0.015 to 0.0324. Though these metrics are buoyed by large standard deviations, owing to the dynamic nature of the fluxes, they demonstrate that IMPTAM, on average, predicts the observed fluxes satisfactorily. The computed binary event tables for predicting high flux values within each 1 h window reveal reasonable hit rates being 0.660-0.318 for flux thresholds of 5 ·104-2 ·105 cm-2 s-1 sr-1 keV-1 for 40 keV electrons, 0.739-0.367 for flux thresholds of 3 ·104-1 ·105 cm-2 s-1 sr-1 keV-1 for 75 keV electrons, and 0.485-0.438 for flux thresholds of 3 ·103-3.5 ·103 cm-2 s-1 sr-1 keV-1 for 150 keV electrons but rather small Heidke Skill Scores (0.17 and below). This is the first attempt to model low-energy electrons in real time at 10 min resolution. The output of this model can serve as an input of electron seed population for real-time higher-energy radiation belt modeling. © 2014 American Geophysical Union.


Horne R.B.,Natural Environment Research Council | Glauert S.A.,Natural Environment Research Council | Meredith N.P.,Natural Environment Research Council | Boscher D.,ONERA | And 3 more authors.
Space Weather | Year: 2013

Satellites can be damaged by high energy charged particles in the Earth's radiation belts and during solar energetic particle (SEP) events. Here we review the growing reliance on satellite services, new vulnerabilities to space weather, and previous events that have led to loss of service. We describe a new European system to forecast the radiation belts up to 3 h ahead, which has three unique features: first, it uses physics-based models, which include wave-particle interactions; second, it provides a forecast for the whole outer radiation belt including geostationary, medium, and slot region orbits; third, it is a truly international effort including Europe, United States, and Japan. During the 8-9 March 2012 storm and SEP event, the models were able to forecast the >800 keV electron flux to within a factor of 2 initially, and later to within a factor of 10 of the GOES data. Although ACE and GOES data became unreliable during the SEP event, the system continued forecasting without interruption using ground-based magnetometers. A forecast of the 24 h electron fluence >2 MeV is used to provide a risk index for satellite operators. We show that including wave-particle interactions for L* > 6.5 improves the agreement with GOES data substantially and that a fast inward motion of the magnetopause to L* < 8 is related to rapid loss of relativistic electrons at geostationary orbit. Thus, we suggest that better wave-particle models and better coupling between the solar wind and the models of the magnetopause and radiation belts should lead to better forecasting. Key Points New physics based radiation belt forcasting system Wave-particle interactions can improve radiation belt forecasting significantly Increasing dependence on satelites poses new risk ©2013. American Geophysical Union. All Rights Reserved.

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