Carmel-by-the-Sea, CA, United States
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Intriligator D.S.,Carmel Research Center | Detman T.,Carmel Research Center | Dryer M.,Carmel Research Center | Intriligator J.,Carmel Research Center | And 6 more authors.
AIP Conference Proceedings | Year: 2012

We extended the three-dimensional (3D) time-dependent magnetohydrodynamic (MHD) Hybrid Heliospheric Modeling System with Pickup Protons (HHMS-PI) [1] out to Voyager 2 (V2) and to 75 AU. HHMS-PI starts at the Sun and uses pre-and post-event background mode source surface (SS) solar inputs and solar event inputs. Our scientific results include good agreement between the HHMS-PI simulated parameters of the solar wind (SW) and interplanetary magnetic field (IMF) measurements at ACE, Ulysses, and Cassini. HHMS-PI simulates well the strong shocks observed at ACE, Ulysses, and Cassini associated with the Halloween 2003 solar events. This agreement indicates that HHMS-PI can provide good simulations for the Sedov strong shock limit. Comparisons between HHMS-PI simulated shock propagation from the Sun to Ulysses and Cassini and the spacecraft measurements of shock arrivals indicates that pickup protons slow the propagation of shocks to Ulysses and Cassini. Our simulations also demonstrate the importance of asymmetric flows in latitude and in longitude. For the Halloween 2003 solar events the HHMS-PI simulations show the large extent in latitude and in longitude of the shocks. The HHMS-PI simulations also indicate that IMF sector boundaries are greatly affected by the SW/IMF. © 2012 American Institute of Physics.


Intriligator D.S.,Carmel Research Center | Sun W.,Carmel Research Center | Sun W.,University of Alaska Fairbanks | Dryer M.,Carmel Research Center | And 5 more authors.
Journal of Geophysical Research A: Space Physics | Year: 2015

The July 2012 major solar events gave rise to manifestations observed at many longitudes/latitudes/radial locations throughout the heliosphere, heliosheath, and into the interstellar medium. For these solar events we present our initial results at 1 AU from our HAFSS (Hakamada-Akasofu-Fry Source Surface) three-dimensional time-dependent kinematic modeling. Our simulations, using Wang-Sheeley-Arge maps and solar event observations, start at 2.5 RS from the center of the Sun. We use both the quiescent background solar conditions and the solar events (e.g., coronal mass ejections (CMEs)) as inputs and propagate outward. We compare HAFSS predictions with in situ spacecraft measurements and conclude that the July 2012 solar events caused a metaphorical "tsunami" in the plasma and magnetic field throughout the heliosphere/heliosheath/interstellar medium. The simulations show evidence of shocks, interaction regions, and rarefaction regions in the inner heliosphere (1 AU) and shocks, global merged interaction regions (GMIRs) and rarefaction regions in the heliosheath. The shocks/interaction regions/GMIRs and the rarefaction regions are, respectively, analogous to the tsunami "crests" and "troughs". To provide important insights into 3-D processes, we simulated 1 AU observations (STEREO A and ACE) and observations at Voyager 2 (V2) and Voyager 1 (V1) far off the ecliptic plane: V2 at ~ 30°S, 217° longitude, and 102 AU; V1 at 34°N, 174° longitude, and 124 AU. HAFSS successfully predicted observed CME arrival times at 1 AU. Our results for this tsunami are the first simulations for these events in the distant V2/V1 radial/latitudinal/longitudinal regions based on 3-D time-dependent modeling originating at the Sun. ©2015. American Geophysical Union. All Rights Reserved.


Intriligator D.S.,Carmel Research Center | Detman T.,Carmel Research Center | Intriligator J.,Carmel Research Center | Intriligator J.,Bangor University | And 8 more authors.
AIP Conference Proceedings | Year: 2012

We have analyzed space weather throughout the heliosphere using the three-dimensional (3D) timedependent magnetohydrodynamic (MHD) Hybrid Heliospheric Modeling System with Pickup Protons (HHMS-PI) [1] out to Voyager 2 (V2) and beyond by comparing the HHMS-PI model results with the available spacecraft data. We also have analyzed space weather throughout the heliosphere through in-depth analyses of the available simultaneous data from a number of instruments on spacecraft at various locations. In this paper we focus on our HHMS-PI modeling (starting at the Sun) of the Halloween 2003 solar events by comparing the model results with spacecraft data at ACE and Ulysses. For the Halloween 2003 solar events we also summarize our inter-comparisons of the in-situ V2 data from many of the V2 instruments. These analyses of the comparisons ("benchmarking") of HHMS-PI simulations and the various spacecraft data and of our in-depth analyses of the V2 particle and field data indicate that particle acceleration and other important physical processes are associated with the heliospheric propagation of these large solar cycle 23 space weather events. We conclude that space weather, originating at the Sun, can have important affects throughout the heliosphere to distances as great as 73 AU and beyond. © 2012 American Institute of Physics.


Webber W.R.,New Mexico State University | Intriligator D.S.,Carmel Research Center | Decker R.B.,Johns Hopkins University
AIP Conference Proceedings | Year: 2012

Motivated by the recent observation that two separate periods of enhanced intensities of solar wind ions at ∼2 times the normal solar wind energy were observed at times of the shock arrival and at the magnetic field maximum at Voyager 2 at 73 AU, arising from the 2003 Halloween event at the Earth, we have re-examined the higher energy proton data from 0.06 to 20 MeV from the LECP and CRS instruments on V2 for this event. We find that there are two separate regions of particle acceleration in this outward propagating merged interaction region. The one near the shock has a much harder proton spectrum extending up to ∼20 MeV, but with a relative paucity of particles below ∼1.0 MeV. The other, near the time of maximum magnetic field fluctuations, is dominated by protons at energies ∼1 MeV or less with a sharp cutoff above 2 MeV. The two regions are separated spatially and the half width of the respective radial intensity distributions at each energy can be used to estimate a local diffusion coefficient. The composite spectrum from these two regions is a power law with a spectral index ∼-1.4 below 1 MeV steepening to-3.2 above ∼2 MeV. This observation has important implications astrophysically, beyond what is seen locally, because most astrophysical observations of accelerated spectra cannot resolve the two components and therefore miss the clues that help identify the particle acceleration mechanisms. © 2012 American Institute of Physics.


Intriligator D.S.,Carmel Research Center | Intriligator J.,Carmel Research Center | Intriligator J.,Bangor University | Miller W.D.,Carmel Research Center | And 8 more authors.
AIP Conference Proceedings | Year: 2010

We present results on the recurrence of High Energy Ions (HEIs) in the V2 data about 90 days after the initial sunward-moving termination shock (TS) crossings of V2 in Aug.-Sept. 2007. We associate the HEIs in Nov.-Dec. 2007 with the outward motion of the TS or with a ripple in the TS so that the TS is again near V2. Comparisons of the timings of the recurrence of the HEI detections and the simultaneous V2 convective plasma, energetic particle, and magnetic field data indicate that the variations in all these V2 data sets are consistent with the TS re-approach to V2 in Nov.-Dec. 2007. We use our three-dimensional (3D) kinematic HAFSS model to investigate whether the timing of the arrival at V2 of the increase in solar wind dynamic pressure associated with the December 2006 solar events could have been responsible for the dynamic pressure pulse that moved the TS outward toward V2 ∼90 days after the initial TS crossings of V2. This explanation or, alternatively, a 3D solar wind inhomogeneity-caused TS ripple (on the scale of ∼1 AU) could be viable scenarios to explain the recurrence of the HEIs in the V2 data in Nov.-Dec. 2007. © 2010 American Institute of Physics.


Two of the most recent outer heliospheric kHz emissions detected by the University of Iowa plasma wave detector on Voyager 1 started at about 2004.64 and 2006.39, respectively. Large interplanetary shocks reached V1 and V2, which are near the heliospheric termination shock, at almost the same time that the two kHz radio emissions turned-on. So, in fact, the arrivals of these large shocks near the heliospheric termination shock were coincident with the onset of these kHz emissions. These two large shocks were unusual in that they were the two strongest shocks in solar cycle 23 seen in the outer heliosphere at V2. They had developed maximum dynamic pressures ∼4-6 times the average solar wind dynamic pressure for periods >26 days by the time they reached V2. © 2010 American Institute of Physics.


Webber W.R.,New Mexico State University | Intriligator D.S.,Carmel Research Center
Journal of Geophysical Research: Space Physics | Year: 2011

We have extended our earlier calculations of the distance to the heliospheric termination shock (HTS), which covered the period from the launch of V1 and V2 in 1977 to 2005, to the period from 2006 to 2011. During this latter period, the solar wind speed, ram pressure, and magnetic field decreased to the lowest levels in recent history, related to the sunspot minimum in 2008-2009. The HTS distance has decreased correspondingly so that V1, which was crossed by the HTS at 94 AU in late 2004, would now, in early 2011, be expected to reach the HTS at a distance of ∼80 AU, when the HTS distance would be expected to be at its minimum. Similarly, V2, which was crossed by the HTS at 84 AU in mid-2007, would, in early 2011, reach the HTS at a distance of only 74 AU. These distances, in early 2011, are ∼15% less than those at which V1 and V2 initially reached the HTS. The distance to the heliopause (HP) is more uncertain, but recent calculations place its equilibrium distance at between 1.4 and 1.6 times the HTS distance. Allowing for an additional 1 year for the HP to reach its equilibrium minimum distance relative to the HTS would mean that, assuming this distance remains a constant fraction larger than the HTS distance, the HP distance would be at its minimum distance of (1.4-1.6) × 80 AU = 112-128 AU at V1 in early 2012. At this time, V1 will be in the direction of a distance of ∼120 AU so that there is a possibility that V1 could cross the HP and enter interstellar space at the time 2012.0 ± 1 year. If the crossing does not happen during this time period, then it is unlikely that V1 will reach this defining boundary before about 2016 because of the expected outward motion of the HTS and the HP toward their more normal distances of 85-96 and ∼120-140 AU, coincident with the maximum of the new sunspot cycle. Copyright 2011 by the American Geophysical Union.


Intriligator D.S.,Carmel Research Center | Sun W.,Carmel Research Center | Sun W.,University of Alaska Fairbanks | Miller W.D.,Carmel Research Center | And 6 more authors.
Journal of Physics: Conference Series | Year: 2015

Using our three dimensional (3D) time-dependent kinematic HAFSS model we propagate the March 2012 solar events from the Sun to Voyager 1 (V1) to investigate if these solar events could be responsible for the V1 April-May 2013 Plasma Wave Spectrometer (PWS) measurements of enhanced 2-3 kHz signals. These PWS measurements provided the basis for the confirmation that V1 entered the interstellar medium (ISM). These enhanced PWS signals also were associated with significantly increased plasma densities consistent with expectations for the ISM. The origin of these enhanced plasma densities was attributed to the April-May 2013 arrival at the heliopause of the disturbances associated with the March 2012 solar events. Using HAFSS we propagate from the Sun the March 2012 solar wind ambient background and the solar wind impulsive events for comparisons with in-situ spacecraft measurements at Earth, V1 (at 34 degrees North), and Voyager 2 (at 30 degrees South). The in-situ measurements of the March 2012 events were obtained over a wide range in radial distance, longitude, and latitude. This emphasizes the importance of using a 3D time-dependent model that originates at the Sun. From our analyses we conclude that the March 2012 solar events could have been responsible for the April-May 2013 V1 enhanced plasma wave signals and their associated increased plasma densities measured by the PWS indicating V1 was in the ISM. © Published under licence by IOP Publishing Ltd.


Kartalev M.,Bulgarian Academy of Science | Keremidarska V.,Bulgarian Academy of Science | Keremidarska V.,Microsoft | Dryer M.,National Oceanic and Atmospheric Administration | Dryer M.,Carmel Research Center
Earth, Moon and Planets | Year: 2016

Earlier developed single fluid gas-dynamic model of solar wind–comet ionosphere interaction is applied to reveal some specifics in the morphology of the shocked “contaminated” solar wind region (cometosheath). The model is based on the Euler equations with added mass-loading, mass-loss and frictional force terms. Numerous reactions are taken into account in these terms including photoionization, charge transfer, dissociative recombination and ion-neutral frictional force. The electromagnetic terms are omitted, thus reducing the MHD single-fluid system of equations to gas-dynamic one. The used shock-fitting numerical scheme allows the separation of distinct areas formed by the considered interaction and exploration of their properties in detail. Attention is focused on the region between the shock wave and the contact surface as well as on the positions of these boundaries. Accurate examination of the distribution of density, temperature and velocity reveals spatial variations that resemble the variations registered by a number of spacecraft in the vicinity of comets. No specific comparisons with data are made at this stage. Two very first events of the Rosetta spacecraft’s crossing of the magnetic cavity boundary around Comet 67P/Churyumov–Gerasimenko are discussed using a “faux-transient” application of our steady-state model. © 2016 Springer Science+Business Media Dordrecht


Detman T.R.,Carmel Research Center | Intriligator D.S.,Carmel Research Center | Dryer M.,Carmel Research Center | Dryer M.,National Oceanic and Atmospheric Administration | And 6 more authors.
Journal of Geophysical Research: Space Physics | Year: 2011

We describe our 3-D, time-dependent, MHD solar wind model that we recently modified to include the physics of pickup protons from interstellar neutral hydrogen. The model has a time-dependent lower boundary condition, at 0.1 AU, that is driven by source surface map files through an empirical interface module. We describe the empirical interface and its parameter tuning to maximize model agreement with background (quiet) solar wind observations at ACE. We then give results of a simulation study of the famous Halloween 2003 series of solar events. We began with shock inputs from the Fearless Forecast real-time shock arrival prediction study, and then we iteratively adjusted input shock speeds to obtain agreement between observed and simulated shock arrival times at ACE. We then extended the model grid to 5.5 AU and compared those simulation results with Ulysses observations at 5.2 AU. Next we undertook the more difficult tuning of shock speeds and locations to get matching shock arrival times at both ACE and Ulysses. Then we ran this last case again with neutral hydrogen density set to zero, to identify the effect of pickup ions. We show that the speed of interplanetary shocks propagating from the Sun to Ulysses is reduced by the effects of pickup protons. We plan to make further improvements to the model as we continue our benchmarking process to 10 AU, comparing our results with Cassini observations, and eventually on to 100 AU, comparing our results with Voyager 1 and 2 observations. Copyright 2011 by the American Geophysical Union.

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