Simulation of January 1-7, 1978 events

The solar wind disturbances of January 1 to 7, 1978 are reconstructed by a modeling method. First, the interplanetary magnetic field (IMF) background pattern, including a corotating shock, is reproduced using the Stanford source surface map. Then, two solar flares with their onset times on January 1, 0717 UT at S17 deg E10 deg and 2147 UT S17 deg E32 deg, respectively, are selected to generate two interplanetary transient shocks. It is shown that these two shocks interacted with the corotating shock, resulting in a series of interplanetary events observed by four spacecraft, Helios 1 and 2, IMP-8 (Interplanetary Monitoring Platform 8), and Voyager 2. Results show that these three shock waves interact and coalesce in interplanetary space such that Helios 2 and Voyager 2 observed only one shock and Helios 1 and IMP-8 observed two shocks. All shocks observed by the four spacecraft, except the corotating shock at Helios 1, are either a transient shock or a shock which is formed from coalescing of the transient shocks with the corotating shock. The method is useful in reconstructing a very complicated chain of interplanetary events observed by a number of spacecraft

Reply to comment by H. Q. Feng, D. J. Wu, and J. K. Chao on “Comparison of small‐scale flux rope magnetic properties to large‐scale magnetic clouds: Evidence for reconnection across the HCS”?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94887/1/jgra20830.pd

Heliospheric evolution of solar wind small‐scale magnetic flux ropes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94774/1/jgra19974.pd

Probabilistic forecasting analysis of geomagnetic indices for southward IMF events

Geomagnetic disturbances that drive space weather impacts such as ground‐induced currents and radiation belt enhancements are usually driven by strong southward interplanetary magnetic field (IMF) intervals. However, current heliospheric models either do not predict or provide low‐accuracy forecasts of IMF Bz. Here we examine the probability distribution function of geomagnetic activity indices for southward IMF intervals. We analyze the in situ plasma and magnetic field measurements long‐duration large‐amplitude southward IMF intervals (called Bs events). The statistical profiles of other solar wind and IMF parameters show significant differences during the periods 1 day before the Bs events for different solar wind transients (such as interplanetary coronal mass ejections and stream interaction regions). As is well known, we find that the solar wind speed is positively correlated with geomagnetic indices and that strong southward IMF is the key in storm triggering but not necessarily for substorms. We find that the solar wind density weakly affects geomagnetic field activity, but the response depends on the type of solar wind transient that includes the strong Bs events. We also find that magnetospheric ultralow‐frequency waves are induced by both strong southward IMF and solar wind dynamic pressure disturbances. We suggest that strong Bs events could be predicted from the preceding characteristics of solar wind and IMF changes and that probabilistic forecasting of geomagnetic activity occurrence is potentially useful in space weather forecasting. We present preliminary analysis to demonstrate the out‐of‐sample ability to predict IMF Bs events with in situ solar wind data.Key PointsSW/IMF shows significant difference before strong IMF Bs for different transientsSW density weakly affects magnetosphere, depending on the type of transientULF waves are induced by strong IMF Bs and SW dynamic pressure disturbancesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111269/1/swe20207.pd

Probabilistic forecasting analysis of geomagnetic indices for southward IMF events

Geomagnetic disturbances that drive space weather impacts such as ground‐induced currents and radiation belt enhancements are usually driven by strong southward interplanetary magnetic field (IMF) intervals. However, current heliospheric models either do not predict or provide low‐accuracy forecasts of IMF Bz. Here we examine the probability distribution function of geomagnetic activity indices for southward IMF intervals. We analyze the in situ plasma and magnetic field measurements long‐duration large‐amplitude southward IMF intervals (called Bs events). The statistical profiles of other solar wind and IMF parameters show significant differences during the periods 1 day before the Bs events for different solar wind transients (such as interplanetary coronal mass ejections and stream interaction regions). As is well known, we find that the solar wind speed is positively correlated with geomagnetic indices and that strong southward IMF is the key in storm triggering but not necessarily for substorms. We find that the solar wind density weakly affects geomagnetic field activity, but the response depends on the type of solar wind transient that includes the strong Bs events. We also find that magnetospheric ultralow‐frequency waves are induced by both strong southward IMF and solar wind dynamic pressure disturbances. We suggest that strong Bs events could be predicted from the preceding characteristics of solar wind and IMF changes and that probabilistic forecasting of geomagnetic activity occurrence is potentially useful in space weather forecasting. We present preliminary analysis to demonstrate the out‐of‐sample ability to predict IMF Bs events with in situ solar wind data.Key PointsSW/IMF shows significant difference before strong IMF Bs for different transientsSW density weakly affects magnetosphere, depending on the type of transientULF waves are induced by strong IMF Bs and SW dynamic pressure disturbancesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111269/1/swe20207.pd

Similarities between interstitial cystitis/bladder pain syndrome and vulvodynia: implications for patient management

Interstitial cystitis/bladder pain syndrome (IC/BPS) and vulvodynia are chronic pain syndromes that appear to be intertwined from the perspectives of embryology, pathology and epidemiology. These associations may account for similar responses to various therapies

Alfvén waves as a possible source of long‐duration, large‐amplitude, and geoeffective southward IMF

The southward component ( B s ) of the interplanetary magnetic field (IMF) is a strong driver of geomagnetic activity. Well‐defined solar wind structures such as magnetic clouds and corotating interaction regions are the main sources of long‐duration, large‐amplitude IMF B s . Here we analyze IMF B s events ( t > 1 h, Bz <−5nT) unrelated with any well‐defined solar wind structure at 1 AU using ACE spacecraft observations from 1998 to 2004. We find that about one third of these B s events show Alfvénic wave features; therefore, those Alfvén waves in the solar wind are also an important source of long‐duration, large‐amplitude IMF southward component. We find that more than half of the Alfvén wave (AW)‐related B s events occur in slow solar wind ( V sw < 400 km/s). One third of the AW‐type B s events triggered geomagnetic storms, and half triggered substorms. Key Points Alfvén wave is a possible source of strong IMF Bs AW‐type Bs events are geoeffective AW‐type Bs events are mainly in slow solar windPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/107524/1/jgra50985.pd

The effect of magnetopause motion on fast mode resonance

The Earth's magnetosphere supports several types of ultralow frequency (ULF) waves. These include fast mode resonance (FMR): cavity modes, waveguide modes, and tunneling modes/virtual resonance. The magnetopause, often treated as the outer boundary for cavity/waveguide modes in the dayside magnetosphere, is not stationary. A rapidly changing outer boundary condition—e.g., due to rapid magnetopause motion—is not favorable for FMR generation and may explain the sparseness of FMR observations in the outer magnetosphere. We examine how magnetopause motion affects the dayside magnetosphere's ability to sustain FMR with idealized Space Weather Modeling Framework (SWMF) simulations using the BATS‐R‐US global magnetohydrodynamic (MHD) code coupled with the Ridley Ionosphere Model (RIM). We present observations of FMR in BATS‐R‐US, reproducing results from other global MHD codes. We further show that FMR is present for a wide range of solar wind conditions, even during periods with large and rapid magnetopause displacements. We compare our simulation results to FMR observations in the dayside magnetosphere, finding that FMR occurrence does not depend on solar wind dynamic pressure, which can be used as a proxy for dynamic pressure fluctuations and magnetopause perturbations. Our results demonstrate that other explanations besides a nonstationary magnetopause—such as the inability to detect FMR in the presence of other ULF wave modes with large amplitudes—are required to explain the rarity of FMR observations in the outer magnetosphere. Key Points Typical magnetopause motion does not affect fast mode resonance occurrence Magnetopause motion cannot explain why FMR is rarely observed Selection criteria and non‐FMR wave activity affect FMR occurrence ratePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109612/1/2014JA020401readme.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109612/2/Auxiliary_Material_fs01.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109612/3/Auxiliary_Material_fs02.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109612/4/jgra51354.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109612/5/Auxiliary_Material_fs03.pd

Quiet time variability of the geosynchronous magnetic field and its response to the solar wind

We present a survey of the variability of the geosynchronous magnetic field strength on the dayside using observations by the GOES satellites over a period exceeding 4 years. Only intervals of reduced geomagnetic activity, as defined by Dst \u3e −20 nT, were considered in this study. The magnetic field strength data were filtered with a passband of 1.7 mHz to 17 mHz (1–10 minutes), a process that eliminates the diurnal variation of the field strength and the effects of most of the higher frequency (\u3e17 mHz) ultralow-frequency (ULF) waves. The geosynchronous field strength appears to exhibit the greatest variability in the prenoon sector for spiral interplanetary magnetic fields (IMF) and in the postnoon sector for orthospiral IMF, suggesting that pressure pulses generated in the foreshock/bow shock region may have a significant influence on the geosynchronous field. The seasonal dependence of the variability was determined to be positively correlated to the seasonal dependence of ground-based observations of magnetic impulse events. The response of the variability of the geosynchronous magnetic field strength around local noon to solar wind parameters was also studied. Here, we observed that the variability was strongly affected by changes in the solar wind dynamic pressure but was seemingly independent of the northward/southward direction of the interplanetary magnetic field. However, for high solar wind dynamic pressures, the variability was found to be greater for northward IMF than for southward IMF