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D.f. Smart - One of the best experts on this subject based on the ideXlab platform.
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Space Weather and the Ground-Level Solar Proton Events of the 23rd Solar Cycle
Space Science Reviews, 2012Co-Authors: M.a. Shea, D.f. SmartAbstract:Solar Proton events can adversely affect space and ground-based systems. Ground-level events are a subset of Solar Proton events that have a harder spectrum than average Solar Proton events and are detectable on Earth’s surface by cosmic radiation ionization chambers, muon detectors, and neutron monitors. This paper summarizes the space weather effects associated with ground-level Solar Proton events during the 23rd Solar cycle. These effects include communication and navigation systems, spacecraft electronics and operations, space power systems, manned space missions, and commercial aircraft operations. The major effect of ground-level events that affect manned spacecraft operations is increased radiation exposure. The primary effect on commercial aircraft operations is the loss of high frequency communication and, at extreme polar latitudes, an increase in the radiation exposure above that experienced from the background galactic cosmic radiation. Calculations of the maximum potential aircraft polar route exposure for each ground-level event of the 23rd Solar cycle are presented. The space weather effects in October and November 2003 are highlighted together with on-going efforts to utilize cosmic ray neutron monitors to predict high energy Solar Proton events, thus providing an alert so that system operators can possibly make adjustments to vulnerable spacecraft operations and polar aircraft routes.
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Solar Proton events for 450 years: The Carrington event in perspective
Advances in Space Research, 2006Co-Authors: M.a. Shea, D.f. Smart, K. G. Mccracken, Gisela A. M. Dreschhoff, Harlan E. SpenceAbstract:Abstract Using high resolution measurements of the impulsive nitrate events in polar ice as identifiers of Solar Proton events in the past, we have identified 19 events over the period 1561–1950 that equal or exceed the >30 MeV fluence measured during the August 1972 episode of Solar Proton events. The largest nitrate impulsive deposition event (and largest Solar Proton fluence above 30 MeV) occurred in late 1859 in time association with the Carrington flare of September 1859. The Carrington flare occurred near the central meridian of the sun; the interplanetary disturbance associated with the Solar activity rapidly traveled toward the earth resulting in an extremely large geomagnetic storm commencing within 17.1 h of the visual observation of the Solar flare. While this event was remarkable by itself, historical records indicate that the Carrington event was part of a sequence of Solar activity as an active region traversed the Solar disk. We compare the derived omni-directional Solar Proton fluence for the Carrington event of 1.9 × 10 10 cm −2 above 30 MeV with the Solar Proton fluence from the past and from more recent episodes of Solar activity. The Carrington event is the largest Solar Proton event identified in our ∼450 year period, having almost twice the >30 MeV Solar Proton fluence than the second largest event in 1895, and approximately four times the Solar Proton fluence of the August 1972 events.
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Two groups of extremely large >30 MeV Solar Proton fluence events
Advances in Space Research, 2006Co-Authors: D.f. Smart, M.a. Shea, Harlan E. Spence, Larry KepkoAbstract:Abstract The very large Solar Proton events, those having an omni-directional Solar Proton fluence greater than 10 9 cm −2 at energies >30 MeV, are the events that impose operational constraints on manned space missions and equipment. A systematic survey of these very large omni-directional fluence Solar Proton events shows an association with two Solar source group locations. One group is the classical situation, where the spacecraft is well connected to the Solar active region by the interplanetary magnetic field. The other and most often-occurring group is the interplanetary shock dominated event resulting from a fast coronal mass ejection (CME) shock near the location of the spacecraft-Sun line. This result is consistent with observations of Solar particle data from Earth-orbiting spacecraft for the last 4 Solar cycles and also with Earth-based observations of very large Solar particle events for the last 7 Solar cycles. We now have an ∼450-year record of these very large Solar Proton events from the analysis of the impulsive nitrate deposition events found in polar ice. The frequency distribution of these large events is consistent with the frequency distribution derived from the analysis of radionuclides found in moon rocks. These frequency distributions show that Solar Proton events with > 30 MeV omni-directional fluence exceeding 6 × 10 9 cm −2 are very rare.
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The Carrington event: Possible Solar Proton intensity time profile
Advances in Space Research, 2006Co-Authors: D.f. Smart, M.a. Shea, Ken MccrackenAbstract:Abstract A possible >30 MeV Solar Proton intensity–time profile associated with the Carrington Solar flare event of 1 September 1859 is constructed. The derived profile is consistent with a >30 MeV Proton omni-directional fluence of 1.9 × 10 10 cm −2 found by the analysis of Solar Proton generated NOy radicals that are deposited in polar ice. The intensity–time profile of the Solar particle flux is constructed by assuming that the Carrington Solar event is part of the class of interplanetary shock-dominated events where the maximum particle flux is observed as the shock passes the Earth. This assumption is based on the knowledge that the very large Solar Proton fluence events (those with >30 MeV omni-directional fluence exceeding 1.0 × 10 9 cm −2 ) associated with central meridian Solar activity during the last 50 years belong to this class of event. The absence of a statistically significant increase in the observed concentration of the cosmogenic nuclide 10 Be for 1859 indicates that the Solar cosmic radiation produced in the Carrington event had a soft spectrum, similar to other interplanetary shock-dominated events.
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Solar Proton event patterns: the rising portion of five Solar cycles
Advances in Space Research, 2002Co-Authors: M.a. Shea, D.f. SmartAbstract:Using Solar Proton data from the past four Solar cycles we have found that while there is no consistent pattern in the distribution of Solar Proton events throughout each cycle, there is a surprising consistency in the total number of events over each cycle. In comparing the distribution of Solar Proton events during the rising portion of cycles 19–23, we find a similarity between the 20th and the 23rd Solar cycles. During Solar cycle 20, only 17% of the Proton events for the entire cycle had occurred during the first three years of the cycle and 28% had occurred during the first four years. If cycles 20 and 23 are similar, we would expect the majority of Solar Proton events to occur during years 5–8 of the 23rd cycle (i.e. from 2001–2004).
M.a. Shea - One of the best experts on this subject based on the ideXlab platform.
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Space Weather and the Ground-Level Solar Proton Events of the 23rd Solar Cycle
Space Science Reviews, 2012Co-Authors: M.a. Shea, D.f. SmartAbstract:Solar Proton events can adversely affect space and ground-based systems. Ground-level events are a subset of Solar Proton events that have a harder spectrum than average Solar Proton events and are detectable on Earth’s surface by cosmic radiation ionization chambers, muon detectors, and neutron monitors. This paper summarizes the space weather effects associated with ground-level Solar Proton events during the 23rd Solar cycle. These effects include communication and navigation systems, spacecraft electronics and operations, space power systems, manned space missions, and commercial aircraft operations. The major effect of ground-level events that affect manned spacecraft operations is increased radiation exposure. The primary effect on commercial aircraft operations is the loss of high frequency communication and, at extreme polar latitudes, an increase in the radiation exposure above that experienced from the background galactic cosmic radiation. Calculations of the maximum potential aircraft polar route exposure for each ground-level event of the 23rd Solar cycle are presented. The space weather effects in October and November 2003 are highlighted together with on-going efforts to utilize cosmic ray neutron monitors to predict high energy Solar Proton events, thus providing an alert so that system operators can possibly make adjustments to vulnerable spacecraft operations and polar aircraft routes.
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Two groups of extremely large >30 MeV Solar Proton fluence events
Advances in Space Research, 2006Co-Authors: D.f. Smart, M.a. Shea, Harlan E. Spence, Larry KepkoAbstract:Abstract The very large Solar Proton events, those having an omni-directional Solar Proton fluence greater than 10 9 cm −2 at energies >30 MeV, are the events that impose operational constraints on manned space missions and equipment. A systematic survey of these very large omni-directional fluence Solar Proton events shows an association with two Solar source group locations. One group is the classical situation, where the spacecraft is well connected to the Solar active region by the interplanetary magnetic field. The other and most often-occurring group is the interplanetary shock dominated event resulting from a fast coronal mass ejection (CME) shock near the location of the spacecraft-Sun line. This result is consistent with observations of Solar particle data from Earth-orbiting spacecraft for the last 4 Solar cycles and also with Earth-based observations of very large Solar particle events for the last 7 Solar cycles. We now have an ∼450-year record of these very large Solar Proton events from the analysis of the impulsive nitrate deposition events found in polar ice. The frequency distribution of these large events is consistent with the frequency distribution derived from the analysis of radionuclides found in moon rocks. These frequency distributions show that Solar Proton events with > 30 MeV omni-directional fluence exceeding 6 × 10 9 cm −2 are very rare.
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Solar Proton events for 450 years: The Carrington event in perspective
Advances in Space Research, 2006Co-Authors: M.a. Shea, D.f. Smart, K. G. Mccracken, Gisela A. M. Dreschhoff, Harlan E. SpenceAbstract:Abstract Using high resolution measurements of the impulsive nitrate events in polar ice as identifiers of Solar Proton events in the past, we have identified 19 events over the period 1561–1950 that equal or exceed the >30 MeV fluence measured during the August 1972 episode of Solar Proton events. The largest nitrate impulsive deposition event (and largest Solar Proton fluence above 30 MeV) occurred in late 1859 in time association with the Carrington flare of September 1859. The Carrington flare occurred near the central meridian of the sun; the interplanetary disturbance associated with the Solar activity rapidly traveled toward the earth resulting in an extremely large geomagnetic storm commencing within 17.1 h of the visual observation of the Solar flare. While this event was remarkable by itself, historical records indicate that the Carrington event was part of a sequence of Solar activity as an active region traversed the Solar disk. We compare the derived omni-directional Solar Proton fluence for the Carrington event of 1.9 × 10 10 cm −2 above 30 MeV with the Solar Proton fluence from the past and from more recent episodes of Solar activity. The Carrington event is the largest Solar Proton event identified in our ∼450 year period, having almost twice the >30 MeV Solar Proton fluence than the second largest event in 1895, and approximately four times the Solar Proton fluence of the August 1972 events.
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The Carrington event: Possible Solar Proton intensity time profile
Advances in Space Research, 2006Co-Authors: D.f. Smart, M.a. Shea, Ken MccrackenAbstract:Abstract A possible >30 MeV Solar Proton intensity–time profile associated with the Carrington Solar flare event of 1 September 1859 is constructed. The derived profile is consistent with a >30 MeV Proton omni-directional fluence of 1.9 × 10 10 cm −2 found by the analysis of Solar Proton generated NOy radicals that are deposited in polar ice. The intensity–time profile of the Solar particle flux is constructed by assuming that the Carrington Solar event is part of the class of interplanetary shock-dominated events where the maximum particle flux is observed as the shock passes the Earth. This assumption is based on the knowledge that the very large Solar Proton fluence events (those with >30 MeV omni-directional fluence exceeding 1.0 × 10 9 cm −2 ) associated with central meridian Solar activity during the last 50 years belong to this class of event. The absence of a statistically significant increase in the observed concentration of the cosmogenic nuclide 10 Be for 1859 indicates that the Solar cosmic radiation produced in the Carrington event had a soft spectrum, similar to other interplanetary shock-dominated events.
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Solar Proton event patterns: the rising portion of five Solar cycles
Advances in Space Research, 2002Co-Authors: M.a. Shea, D.f. SmartAbstract:Using Solar Proton data from the past four Solar cycles we have found that while there is no consistent pattern in the distribution of Solar Proton events throughout each cycle, there is a surprising consistency in the total number of events over each cycle. In comparing the distribution of Solar Proton events during the rising portion of cycles 19–23, we find a similarity between the 20th and the 23rd Solar cycles. During Solar cycle 20, only 17% of the Proton events for the entire cycle had occurred during the first three years of the cycle and 28% had occurred during the first four years. If cycles 20 and 23 are similar, we would expect the majority of Solar Proton events to occur during years 5–8 of the 23rd cycle (i.e. from 2001–2004).
J V Rodriguez - One of the best experts on this subject based on the ideXlab platform.
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validation of the effect of cross calibrated goes Solar Proton effective energies on derived integral fluxes by comparison with stereo observations
Social Work, 2017Co-Authors: J V Rodriguez, I. Sandberg, I A Daglis, R A Mewaldt, Piers JiggensAbstract:The derivation of integral fluxes from instrument coincidence rates requires accurate knowledge of their effective energies. Recent cross calibrations of GOES with the high-energy-resolution Interplanetary Monitoring Platform (IMP) 8 Goddard Medium Energy Experiment (GME) (Sandberg et al., Geophys. Res. Lett, 41, 4435, 2014a) gave significantly lower effective energies than those currently used by the NOAA Space Weather Prediction Center to calculate Solar Proton integral fluxes from GOES rates. This implies systematically lower integral fluxes than currently produced. This paper quantifies the differences between the current and the cross-calibrated GOES integral fluxes and validates the latter. Care is taken to rule out the spectral resolution of the measurements or different integration algorithms as major contributors to differences in the magnitudes of the derived integral fluxes. The lower effective energies are validated by comparison with the independent, high-resolution observations by the STEREO Low-Energy Telescope (LET) and High-Energy Telescope (HET) during the December 2006 Solar Proton events. The current GOES product is similar to the >10 MeV integral fluxes recalculated by using the Sandberg et al. [2014a] effective energies but is substantially greater at higher energies. (The median ratios of the current to the recalculated fluxes are 1.1 at >10 MeV, 1.7 at >30 MeV, 2.1 at >60 MeV, and 2.9 at >100 MeV.) By virtue of this validation, the cross-calibrated GOES integral fluxes should be considered more accurate than the current NOAA product. The results of this study also demonstrate good consistency between the two long-term IMP 8 GME and STEREO LET and HET Solar Proton data sets.
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intercalibration of goes 8 15 Solar Proton detectors
Social Work, 2014Co-Authors: J V Rodriguez, J C Krosschell, J C GreenAbstract:This work provides a relative intercalibration of the high-energy Proton channels from the Energetic Particle Sensors (EPS) flown on the Geostationary Operational Environmental Satellites (GOES) since 1994 using a technique that depends on features that arise during high Solar wind dynamic pressure. Based on observations of Solar energetic Protons from polar-orbiting and geostationary satellites (1998–2013), Solar Proton fluxes are isotropic at geostationary orbit during periods of high Solar wind dynamic pressure (Pdyn>5−10 nPa). The observed isotropy results from the Solar Proton fluxes having rigidities (momenta per unit charge) greater than their geomagnetic cutoffs over the complete energy and angular responses of the satellite-borne detector. (The cutoff in a given direction is the rigidity below which an interplanetary particle cannot reach that location.) Under these conditions, we determine the relative responses of the EPS flown on GOES 8 through 15. These detectors are widely used for alerts of the radiation hazard posed to spacecraft and humans by Solar energetic particle events; therefore, it is important to know their relative responses. The results of this low-scatter intercalibration analysis show that the relative responses agree to 20% or better (sometimes better than 1%). The effect of such relative calibration differences on the derived integral fluxes used by NOAA for its real-time Solar radiation storm alerts is shown to be small (<10%). This method can be used to intercalibrate Solar Proton detectors of different design if their broad energy response functions are carefully accounted for.
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the east west effect in Solar Proton flux measurements in geostationary orbit a new goes capability
Geophysical Research Letters, 2010Co-Authors: J V Rodriguez, T G Onsager, J E MazurAbstract:[1] Since 1998, the GOES system has made eastward and westward observations of multi-MeV Solar Proton fluxes. The gyrocenters of the fluxes observed looking westward (eastward) lie outside (inside) geostationary orbit. Due to this “east-west effect,” eastward observations of 4.2–82 MeV Protons vary with respect to their westward equivalents. At times of high Solar wind dynamic pressure (Pdyn > 10 nPa), the “inside” and “outside” fluxes are approximately equal. As Pdyn decreases to ∼1 nPa and the ring current decreases, the “inside” fluxes decrease as much as an order of magnitude with respect to the “outside” fluxes. Under low Pdyn, the “inside” fluxes exhibit short-lived (1–3 hr) increases, sometimes to the levels of the “outside” fluxes, during periods of enhanced AE index activity. This association suggests that magnetotail topologies associated with substorms enhance the access of Solar Protons to lower L shells under low Pdyn.
Piers Jiggens - One of the best experts on this subject based on the ideXlab platform.
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The virtual enhancements − Solar Proton event radiation (VESPER) model
Journal of Space Weather and Space Climate, 2018Co-Authors: Sigiava Aminalragia-giamini, I. Sandberg, Constantinos Papadimitriou, Ioannis A. Daglis, Piers JiggensAbstract:A new probabilistic model introducing a novel paradigm for the modelling of the Solar Proton environment at 1 AU is presented. The virtual enhancements − Solar Proton event radiation model (VESPER) uses the European space agency's Solar energetic particle environment modelling (SEPEM) Reference Dataset and produces virtual time-series of Proton differential fluxes. In this regard it fundamentally diverges from the approach of existing SPE models that are based on probabilistic descriptions of SPE macroscopic characteristics such as peak flux and cumulative fluence. It is shown that VESPER reproduces well the dataset characteristics it uses, and further comparisons with existing models are made with respect to their results. The production of time-series as the main output of the model opens a straightforward way for the calculation of Solar Proton radiation effects in terms of time-series and the pairing with effects caused by trapped radiation and galactic cosmic rays.
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two Solar Proton fluence models based on ground level enhancement observations
Journal of Space Weather and Space Climate, 2018Co-Authors: Osku Raukunen, Piers Jiggens, D. Heynderickx, Rami Vainio, Allan J Tylka, William F Dietrich, Mark Dierckxsens, Norma Crosby, Urs Ganse, Robert SiipolaAbstract:Solar energetic particles (SEPs) constitute an important component of the radiation environment in interplanetary space. Accurate modeling of SEP events is crucial for the mitigation of radiation hazards in spacecraft design. In this study we present two new statistical models of high energy Solar Proton fluences based on ground level enhancement (GLE) observations during Solar cycles 19–24. As the basis of our modeling, we utilize a four parameter double power law function (known as the Band function) fits to integral GLE fluence spectra in rigidity. In the first model, the integral and differential fluences for Protons with energies between 10 MeV and 1 GeV are calculated using the fits, and the distributions of the fluences at certain energies are modeled with an exponentially cut-off power law function. In the second model, we use a more advanced methodology: by investigating the distributions and relationships of the spectral fit parameters we find that they can be modeled as two independent and two dependent variables. Therefore, instead of modeling the fluences separately at different energies, we can model the shape of the fluence spectrum. We present examples of modeling results and show that the two methodologies agree well except for a short mission duration (1 year) at low confidence level. We also show that there is a reasonable agreement between our models and three well-known Solar Proton models (JPL, ESP and SEPEM), despite the differences in both the modeling methodologies and the data used to construct the models.
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validation of the effect of cross calibrated goes Solar Proton effective energies on derived integral fluxes by comparison with stereo observations
Social Work, 2017Co-Authors: J V Rodriguez, I. Sandberg, I A Daglis, R A Mewaldt, Piers JiggensAbstract:The derivation of integral fluxes from instrument coincidence rates requires accurate knowledge of their effective energies. Recent cross calibrations of GOES with the high-energy-resolution Interplanetary Monitoring Platform (IMP) 8 Goddard Medium Energy Experiment (GME) (Sandberg et al., Geophys. Res. Lett, 41, 4435, 2014a) gave significantly lower effective energies than those currently used by the NOAA Space Weather Prediction Center to calculate Solar Proton integral fluxes from GOES rates. This implies systematically lower integral fluxes than currently produced. This paper quantifies the differences between the current and the cross-calibrated GOES integral fluxes and validates the latter. Care is taken to rule out the spectral resolution of the measurements or different integration algorithms as major contributors to differences in the magnitudes of the derived integral fluxes. The lower effective energies are validated by comparison with the independent, high-resolution observations by the STEREO Low-Energy Telescope (LET) and High-Energy Telescope (HET) during the December 2006 Solar Proton events. The current GOES product is similar to the >10 MeV integral fluxes recalculated by using the Sandberg et al. [2014a] effective energies but is substantially greater at higher energies. (The median ratios of the current to the recalculated fluxes are 1.1 at >10 MeV, 1.7 at >30 MeV, 2.1 at >60 MeV, and 2.9 at >100 MeV.) By virtue of this validation, the cross-calibrated GOES integral fluxes should be considered more accurate than the current NOAA product. The results of this study also demonstrate good consistency between the two long-term IMP 8 GME and STEREO LET and HET Solar Proton data sets.
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cross calibration of noaa goes Solar Proton detectors using corrected nasa imp 8 gme data
Geophysical Research Letters, 2014Co-Authors: I. Sandberg, Piers Jiggens, D. Heynderickx, I A DaglisAbstract: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.
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Cross calibration of NOAA GOES Solar Proton detectors using corrected NASA IMP‐8/GME data
Geophysical Research Letters, 2014Co-Authors: I. Sandberg, Piers Jiggens, D. Heynderickx, Ioannis A. DaglisAbstract: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.
Charles H. Jackman - One of the best experts on this subject based on the ideXlab platform.
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Nitrate ion spikes in ice cores not suitable as proxies for Solar Proton events
Journal of Geophysical Research: Atmospheres, 2016Co-Authors: Katharine A. Duderstadt, Harlan E. Spence, Charles H. Jackman, Jack E. Dibb, Nathan A. Schwadron, Stanley C. Solomon, Valery A. Yudin, Cora E. RandallAbstract:Nitrate ion spikes in polar ice cores are contentiously used to estimate the intensity, frequency, and probability of historical Solar Proton events, quantities that are needed to prepare for potentially society-crippling space weather events. We use the Whole Atmosphere Community Climate Model to calculate how large an event would have to be to produce enough odd nitrogen throughout the atmosphere to be discernible as nitrate peaks at the Earth's surface. These hypothetically large events are compared with probability of occurrence estimates derived from measured events, sunspot records, and cosmogenic radionuclides archives. We conclude that the fluence and spectrum of Solar Proton events necessary to produce odd nitrogen enhancements equivalent to the spikes of nitrate ions in Greenland ice cores are unlikely to have occurred throughout the Holocene, confirming that nitrate ions in ice cores are not suitable proxies for historical individual Solar Proton events.
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the Solar Proton events in 2012 as observed by mipas
Geophysical Research Letters, 2013Co-Authors: T. Von Clarmann, B. Funke, G. P. Stiller, Charles H. Jackman, M Lopezpuertas, S Kellmann, A Linden, V L HarveyAbstract:[1] During the Solar Proton events (SPE) on 23–30 January and 7–15 March 2012, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat monitored atmospheric temperature and composition with global coverage. In the Northern Hemisphere, the January SPE started at the end of a polar stratospheric warming period. The SPE effect is superimposed by large-scale subsidence of mesospheric NOx-rich air, which partly masks direct chemical SPE effects. SPE-induced NOx increases by 5, 20, 50, and 100 ppbv at altitudes of 50, 57, 60, and 70 km, respectively, are observed during the January SPE and those by 2, 5, 10, 20, 30, and 35 ppbv at altitudes of 47, 50, 53, 60, 63, and 66 km, respectively, during the March SPE. SPE-related ozone loss is clearly observed in the mesosphere, particularly in the tertiary ozone maximum. A sudden short-term HNO4 increase immediately after the January SPE hints at SPE-triggered HOx chemistry. In the Southern Hemisphere, a large NOx response is observed (increases by 2, 5, 10, 20, and 30 ppbv at 52, 56, 59, 63, and 70 km in January and by 2, 5, 10, 20, 30, and 35 ppbv at 47, 50, 53, 60, 63, and 66 km in March), while the effect on other species seems much less pronounced than in the Northern Hemisphere. SPE-related destruction of mesospheric ozone in the Southern Hemisphere was much more pronounced after the March SPE than the January SPE but in both cases, ozone recovered within about a day.
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long term middle atmospheric influence of very large Solar Proton events
Journal of Geophysical Research, 2009Co-Authors: Charles H. Jackman, Eric L. Fleming, Daniel R Marsh, Francis Vitt, Rolando R Garcia, C E Randall, S M FrithAbstract:[1] The Whole Atmosphere Community Climate Model (WACCM3) has been used to study the long-term (more than a few months) effects of Solar Proton events (SPEs). Extremely large Solar Proton events occurred in 1972, 1989, 2000, 2001, and 2003 and caused some longer-lasting atmospheric changes. The highly energetic Solar Protons produced odd hydrogen (HOx) and odd nitrogen (NOy), which then led to ozone variations. Some statistically significant long-term effects on mesospheric ozone were caused by the HOx increases due to a very active time period for SPEs (years 2000–2004), even though the HOx increases were short-lived (days). The long-term stratospheric ozone effects were caused by the NOy enhancements. Very large NOy enhancements lasted for months in the middle and lower stratosphere after a few of the largest SPEs. SPE-caused NOy increases computed with WACCM3 were statistically significant at the 95% level throughout much of the polar stratosphere and mesosphere in the recent Solar maximum 5-year period (2000–2004). WACCM3-computed SPE-caused polar stratospheric ozone decreases of >10% continued for up to 5 months past the largest events; however, statistically significant ozone decreases were computed for only a relatively small fraction of this time in relatively limited altitudes in the lower mesosphere and upper stratosphere. Annually averaged model output showed statistically significant (to 95%) stratospheric ozone loss in the polar Northern Hemisphere for years 2000–2002. The computed annually averaged temperature and total ozone change in these years were not statistically significant.
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Short- and medium-term atmospheric effects of very large Solar Proton events
Atmospheric Chemistry and Physics Discussions, 2007Co-Authors: Charles H. Jackman, M. López-puertas, Daniel R Marsh, Francis Vitt, Rolando R Garcia, C E Randall, E. L. Fleming, G. J. Labow, B. FunkeAbstract:Solar eruptions sometimes produce Protons, which impact the Earth's atmosphere. These Solar Proton events (SPEs) generally last a few days and produce high energy particles that precipitate into the Earth's atmosphere. The Protons cause ionization and dissociation processes that ultimately lead to an enhancement of odd-hydrogen and odd-nitrogen in the polar cap regions (>60° geomagnetic latitude). We have used the Whole Atmosphere Community Climate Model (WACCM3) to study the atmospheric impact of SPEs over the period 1963?2005. The very largest SPEs were found to be the most important and caused atmospheric effects that lasted several months to years after the events. We present the short- and medium-term (days to a few months) atmospheric influence of the four largest SPEs in the past 45 years (August 1972; October 1989; July 2000; and October?November 2003) as computed by WACCM3 and observed by satellite instruments. The polar effects can be summarized as follows: 1) Mesospheric NOx (NO+NO2) increased by over 50 ppbv and mesospheric ozone decreased by over 30% during these very large SPEs; 2) upper stratospheric and lower mesospheric NOx increased by over 10 ppbv and was transported during polar night down to the middle stratosphere in a few weeks; 3) mid- to upper stratospheric ozone decreased over 20%; and 4) enhancements of HNO3, HOCl, ClO, ClONO2, and N2O5 were indirectly caused by the very large SPEs, although the model results suggest impacts at higher altitudes than indicated by the measurements for the October?November 2003 SPE period.
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Mesospheric dynamical changes induced by the Solar Proton events in October-November 2003
Geophysical Research Letters, 2007Co-Authors: Charles H. Jackman, Raymond G. Roble, Eric L. FlemingAbstract:[1] The Thermosphere Ionosphere Mesosphere Electrodynamic General Circulation Model (TIME-GCM) was used to study the atmospheric dynamical influence of the Solar Protons that occurred in Oct–Nov 2003, the fourth largest period of Solar Proton events (SPEs) measured in the past 40 years. The highly energetic Solar Protons produced odd hydrogen (HOx) and odd nitrogen (NOy). Significant short-lived ozone decreases (10–70%) followed these enhancements of HOx and NOy and led to a cooling of most of the lower mesosphere. Temperature changes up to ±2.6 K were computed as well as wind (zonal, meridional, vertical) perturbations up to 20–25% of the background winds as a result of the Solar Protons. The Solar Proton-induced mesospheric temperature and wind perturbations diminished over a period of 4–6 weeks after the SPEs. The Joule heating in the mesosphere, induced by the Solar Protons, was computed to be relatively insignificant for these Solar storms.