With the advent of the Heliophysics/Geospace System Observatory (H/GSO), a complement of multi-spacecraft missions and ground-based observatories to study the space environment, data retrieval, analysis, and visualization of space physics data can be daunting. The Space Physics Environment Data Analysis System (SPEDAS), a grass-roots software development platform ( www.spedas.org ), is now officially supported by NASA Heliophysics as part of its data environment infrastructure. It serves more than a dozen space missions and ground observatories and can integrate the full complement of past and upcoming space physics missions with minimal resources, following clear, simple, and well-proven guidelines. Free, modular and configurable to the needs of individual missions, it works in both command-line (ideal for experienced users) and Graphical User Interface (GUI) mode (reducing the learning curve for first-time users). Both options have “crib-sheets,” user-command sequences in ASCII format that can facilitate record-and-repeat actions, especially for complex operations and plotting. Crib-sheets enhance scientific interactions, as users can move rapidly and accurately from exchanges of technical information on data processing to efficient discussions regarding data interpretation and science. SPEDAS can readily query and ingest all International Solar Terrestrial Physics (ISTP)-compatible products from the Space Physics Data Facility (SPDF), enabling access to a vast collection of historic and current mission data. The planned incorporation of Heliophysics Application Programmer’s Interface (HAPI) standards will facilitate data ingestion from distributed datasets that adhere to these standards. Although SPEDAS is currently Interactive Data Language (IDL)-based (and interfaces to Java-based tools such as Autoplot), efforts are under-way to expand it further to work with python (first as an interface tool and potentially even receiving an under-the-hood replacement). We review the SPEDAS development history, goals, and current implementation. We explain its “modes of use” with examples geared for users and outline its technical implementation and requirements with software developers in mind. We also describe SPEDAS personnel and software management, interfaces with other organizations, resources and support structure available to the community, and future development plans. Electronic Supplementary Material The online version of this article (10.1007/s11214-018-0576-4) contains supplementary material, which is available to authorized users.

[1] An empirical model of the quiet daily geomagnetic field variation has been constructed based on geomagnetic data obtained from 21 stations along the 210 Magnetic Meridian of the Circum-pan Pacific Magnetometer Network (CPMN) from 1996 to 2007. Using the least squares fitting method for geomagnetically quiet days (Kp ≤ 2+), the quiet daily geomagnetic field variation at each station was described as a function of solar activity SA, day of year DOY, lunar age LA, and local time LT. After interpolation in latitude, the model can describe solar-activity dependence and seasonal dependence of solar quiet daily variations (S) and lunar quiet daily variations (L). We performed a spherical harmonic analysis (SHA) on these S and L variations to examine average characteristics of the equivalent external current systems. We found three particularly noteworthy results. First, the total current intensity of the S current system is largely controlled by solar activity while its focus position is not significantly affected by solar activity. Second, we found that seasonal variations of the S current intensity exhibit northsouth asymmetry; the current intensity of the northern vortex shows a prominent annual variation while the southern vortex shows a clear semi-annual variation as well as annual variation. Thirdly, we found that the total intensity of the L current system changes depending on solar activity and season; seasonal variations of the L current intensity show an enhancement during the December solstice, independent of the level of solar activity.

[1] The objective of this study is to understand better the propagation of Pi 2 waves in the nighttime region. We examined Pi 2 oscillations that showed high correlation between high-and low-latitude Magnetic Data Acquisition System/Circum Pan-Pacific Magnetometer Network stations (correlation coefficient: jgj ! 0.75). For each horizontal component (H and D) we examined the magnetic local time (MLT) dependence of the delay time of high-latitude Pi 2 oscillations that corresponds to the highest correlation with the low-latitude Pi 2 oscillation. We found the delay time of the high-latitude H showed remarkable MLT dependence, especially in the premidnight sector: we found that in the premidnight sector the high-latitude H oscillation tends to delay from the low-latitude oscillation (<100 s). On the other hand, the delay time of the high-latitude D oscillation was not significant ($±10 s) in the entire nighttime sector. We propose a Pi 2 propagation model to explain the observed delay time of high-correlation highlatitude H. The model quantitatively explains the trend of the event distribution. We also examined the spatial distribution of high-correlation Pi 2 events relative to the center of auroral breakups. It was found that the high-correlation Pi 2 events tend to occur away from the center of auroral breakups by more than 1.5 MLT. The present result suggests that the high-correlation H component Pi 2 oscillations at high latitude are a manifestation of forced Alfvén waves excited by fast magnetosonic waves.

[1] This paper describes ionospheric current systems associated with the counter-electrojet during sudden stratospheric warming (SSW) events in the northern winter months of 2001-2002 and 2002-2003. Magnetic data from 20 stations in the East Asian region, covering both the Northern Hemisphere and the Southern Hemisphere, are analyzed. Additional current systems that are superposed on the normal S q current system and related to the counter-electrojet during the SSW events show a global semidiurnal current pattern, which shifts to later local times approximately by 0.8 hour/day. The results indicate that abnormally large lunar tidal winds played a main role to produce the additional current system and counter-electrojet during the SSW events.

[1] We study the characteristics of the low-latitude ionospheric electric field and geomagnetic field in response to a sudden enhancement of the solar wind pressure. When the magnetosphere is compressed by an interplanetary shock, a significant enhancement in the dayside equatorial ionospheric ion vertical velocity occurs over 30-40 min and is measured by the Jicamarca incoherent scatter radar. A similar enhancement occurs in the high-latitude ionospheric convection and is detected by the SuperDRAN HF radars. The simultaneous enhancements of the ionospheric ion velocity at high and low latitudes provide strong evidence of the occurrence of penetration electric fields produced by solar wind pressure enhancements. The geomagnetic field first increases rapidly over 2-3 min and then falls over 30-40 min to an asymptotic value. The enhanced magnetic field occurs from the subauroral region to the equator at all local times. The time scale of 30-40 min is much longer than the conventional preliminary and main impulses of geomagnetic response to interplanetary shocks. There are two possible mechanisms that may be responsible for the generation of the enhanced ionospheric electric and magnetic fields. One mechanism is that the solar wind shock causes an over-compression of the magnetosphere, and the other is that the field-aligned and ionospheric currents driven by the solar wind shock cause the enhancements of the ionospheric electric and magnetic fields. However, neither of the mechanisms appears to be able to provide a complete explanation of all observed features.Citation: Huang, C.-S., K. Yumoto, S. Abe, and G. Sofko (2008), Low-latitude ionospheric electric and magnetic field disturbances in response to solar wind pressure enhancements,