Measurements from the Magnetospheric Multiscale (MMS) mission indicate that the density gradients associated with nonlinear compressional structures (shocklets) in a quasi-parallel bow shock trigger sequentially two instabilities that heat ions and electrons. The Lower-Hybrid-Drift (LHD) instability, triggered by the diamagnetic drift of ions, produces electric fields and ExB drift of electrons that triggers the Electron-Cyclotron-Drift (ECD) instability. Both instabilities create large amplitude electric fields $\sim$20–200 mV/m at wavelengths comparable to the electron gyroradius. Strong gradients of the electric field lead to stochastic heating of both ions and electrons, controlled by a dimensionless function $\chi = m_iq_i^{-1} B^{-2}\mathrm{div}(\mathbf{E}_\perp)$, which represents a universal, non-resonant heating mechanism for particles species with mass $m_i$ and charge $ q_i$, independent of the type of waves and instabilities.

The MAVEN/EUVM solar soft x-ray (SXR) and Lyman-α measurements are compared with analogous measurements made from Earth to characterize the typical error introduced when phase-shifting solar EUV irradiance measurements made from Earth to other points in the solar system according to the 27.27 day synodic solar rotation period. The phase-shifting error, ε, measured at SXR and Lyman-α are extrapolated to the full EUV spectrum by assuming it is proportional to the variability that occurs over the 27-day timescale of solar rotation. Values for ε as a function of wavelength are reported and used to find the typical error for estimates of photoionization frequencies of some major species found in planetary upper atmospheres derived by phase-shifted EUV irradiance. This study finds that the typical extrapolation error for the CO photoionization frequency is 5.7% of the solar cycle mean value, and 87% of the typical 27-day variability.

We present observations in Earth’s magnetotail by the Magnetospheric Multiscale spacecraft that are consistent with magnetic field annihilation, rather than magnetic topology change, causing fast magnetic-to-electron energy conversion in an electron-scale current sheet. Multi-spacecraft analysis for the magnetic field reconstruction shows that an electron-scale magnetic island was embedded in the observed electron diffusion region (EDR), suggesting an elongated shape of the EDR. Evidence for the annihilation was revealed in the form of the island growing at a rate much lower than expected for the standard collisionless reconnection, which indicates that magnetic flux injected into the EDR was not ejected from the X-point or accumulated in the island, but was dissipated in the EDR. This energy conversion process is in contrast to that in the standard EDR of a reconnecting current sheet where the energy of antiparallel magnetic fields is mostly converted to electron bulk-flow energy. Fully kinetic simulation also demonstrates that an elongated EDR is subject to the formation of electron-scale magnetic islands in which fast but transient annihilation can occur. Consistent with the observations and simulation, theoretical analysis shows that fast magnetic diffusion can occur in an elongated EDR in the presence of nongyrotropic electron effects. We suggest that the annihilation in elongated EDRs may contribute to the dissipation of magnetic energy in a turbulent collisionless plasma.

Nowadays, it is so important in saving our economic activity and evading the disasters caused by terrestrial electromagnetic effects to predict both temporal and spatial scales of the geomagnetic disturbances based on in-situ solar wind observations. Recently, Neural Network (NN) is one of the notable techniques for the predictions of the magnetospheric activities. However, NN has a problem referred to as ‘black box’, which is difficult to extract which solar wind parameters are the most important for prediction. In this study, we examine a significant relationship between Kp index, which represents the magnetospheric activity, and the solar wind conditions based on an interpretable neural network: ‘Potential Learning (PL)’. A feature of the PL is to make a network that can understand the input variables by learning the “input potentialities”, which are indices calculated using the variances of the solar wind parameters as input variables. In this study, we investigate the magnetospheric activity profile when the Interplanetary Magnetic Field (IMF) oriented southward (Bz < 0). As the input solar wind data, we utilize the two components of the magnetic field (Bx, By) in GSE, and solar wind flow speed, and number density during 20 years between 1999 and 2018. Furthermore, we divide the associated values of Kp into two groups (targets): ‘Kp = 6- to 9 (positive target)’ and ‘Kp = 0 to 1+ (negative target)’. Because the data number of positive target was smaller than that of negative target, the negative target samples are randomly selected so that the data numbers of both targets become equal. Based on the PL neural network, we obtain two important results; 1) the solar wind plasma flow speed might have the most influential in the increase of the Kp index, and 2) as the secondary influential parameter for the Kp increase, the solar wind proton density is considered. In the presentation, we will discuss feasibility of the application to the prediction of the magnetospheric activity based on the solar wind parameters.

Due to the lower ionospheric thermal pressure and existence of the crustal magnetism at Mars, the Martian ionopause is expected to behave differently from the ionopause at Venus. We study the solar wind interaction and pressure balance at the ionopause of Mars using both in situ and remote sounding measurements from the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument on the Mars Express orbiter. We show that the magnetic pressure usually dominates the thermal pressure to hold off the solar wind in the ionopause at Mars, with only 13% unmagnetized ionopauses observed over a 11-year period. We also find that the ionopause altitude decreases as the normal component of the solar wind dynamic pressure increases. Moreover, our results show that the ionopause thickness at Mars is mainly determined by the ion gyromotion and equivalent to about 5.7 ion gyroradii.

Gamma-Ray Glows (GRGs) are high energy radiation originating from thunderclouds, in the MeV energy regime, with typical duration of seconds to minutes, and sources extended over several to tens of square kilometers. GRGs have been observed from detectors placed on ground, inside aircraft and on balloons. In this paper, we present a general purpose Monte-Carlo model of GRG production and propagation. This model is first compared to a model from Zhou et al. (2016) relying on another Monte-Carlo framework, and small differences are observed. We then have built an extensive simulation library, made available to the community. This library is used to reproduce five previous gamma-ray glow observations, from five airborne campaigns: balloons from Eack et al. (1996b), Eack et al. (2000); and aircrafts from ADELE (Kelley et al., 2015), ILDAS (Kochkin et al., 2017) and ALOFT (Østgaard et al., 2019). Our simulation results confirm that fluxes of cosmic-ray secondary particles present in the background at a given altitude can be enhanced by several percent (MOS process), and up to several orders of magnitude (RREA process) due to the effect of thunderstorms’ electric fields, and explain the five observations. While some GRG can be explained purely by the MOS process, E-fields significantly larger than E_th (the RREA threshold) are required to explain the strongest GRGs observed. Some of the observations also came with in-situ electric field measurements, that were always lower than E_th , but may not have been obtained from regions where the glows are produced. This study supports the claim that kilometer-scale E-fields magnitudes of at least the level of E_th must be present inside some thunderstorms.

One of the prominent effects of space weather is the variation of electric currents in the magnetosphere and ionosphere, which give rise to rapid geomagnetic field variations on the surface of the Earth. These Geomagnetic Disturbances (GMDs) can be highly localized and large amplitude. Because the causes of localized GMDs are unresolved, we seek to identify the physical drivers of these localized dB/dt spikes measured by ground magnetometers. We use the Space Weather Modeling Framework (SWMF) models to simulate the magnetosphere and reproduce these small-scale spikes. We use the operational Geospace configuration, which couples a global magnetohydrodynamic model to a height-integrated ionospheric electrodynamics solver and a kinetic ring current model. We run a series of simulations with increasingly higher spatial resolution to resolve small scale dB/dt dynamics. We quantify the success of the model against observation using Regional Station Difference (RSD), a metric calculated using dB/dt or geoelectric field to pinpoint when a single magnetometer station records a significantly different value than others within a given radius. We discuss future work to improve the model’s accuracy and our understanding of these small-scale structures.

In the Jovian magnetosphere, an electric current system within the ‘current sheet’ generates a magnetic field, which is comparable to or dominating the Jovian intrinsic field in the nightside magnetosphere. However, update of an existing model of the magnetospheric field using newly acquired data by Galileo and Juno have never been conducted since it was first formulated in 1997. Here we used the data by Voyager 1/2, Galileo and Juno to revise the current sheet model as well as the magnetospheric field model based on each spacecraft data. We derived models that reproduced each data well, and revealed long-term variations of both current sheet and magnetospheric field over several decades. The updated models were found useful to detect dynamic events in the magnetosphere such as magnetopause deformation and plasmoid generation. They can also be used as external fields necessary for probing into the Galilean icy moons by electromagnetic induction methods.

As there are strong crustal magnetic fields in some Martian concentrated regions. it has long been a goal of Martian science to understand how crustal magnetic field affects surrounding space environment. In the paper, using the data measured by MAVEN, the ratio of electron/CO2 density ( Ne/NCO2) in region with different levels of Martian ionospheric magnetic fields are studied. It seems that ratio of dayside Ne/NCO2 in region with stronger ionospheric magnetic field is larger while the altitude is more than 260 km. On the other hand, the effect of crustal magnetic field intensity on the nightside ratio of Ne/NCO2 is weak. Since the topological structure of magnetic field is very vulnerable to the solar wind, the correlation between Ne/NCO2 and solar wind parameters are analyzed. We find that there is obvious negative correlation between dayside ratio of Ne/NCO2 and solar wind dynamic pressure in the region with strong ionospheric magnetic field, which may imply that the ionospheric plasmas are significantly escaped in response to enhanced solar wind dynamic pressure pulses in the dayside region. However, the effect of solar wind on nightside ratio of Ne/NCO2 is very little. These results can be useful for understanding the dynamic process in the Martian ionosphere.

Crater morphology and surface age of asteroid (162173) Ryugu are characterized using the high-resolution images obtained by the Hayabusa2 spacecraft. Our observations reveal that the abundant boulders on and under the surface of the rubble-pile asteroid affect crater morphology. Most of the craters on Ryugu exhibit well-defined circular depressions, unlike those observed on asteroid Itokawa. The craters are typically outlined by boulders remaining on the rim. Large craters (diameter >100 m) host abundant and sometimes unproportionally large boulders on their floors. Small craters (<20 m) are characterized by smooth circular floors distinguishable from the boulder-rich exterior. Such small craters tend to have dark centers of unclear origin. The correlation between crater size and boulder number density suggests that some processes sort the size of boulders in the shallow (<30 m) subsurface. Furthermore, the crater size-frequency distributions (CSFDs) of different regions on Ryugu record multiple geologic events, revealing the diverse geologic history on this 1-km asteroid. Our crater counting analyses indicate that the equatorial ridge is the oldest structure of Ryugu and was formed 23-29 Myr ago. Then, Ryugu was partially resurfaced, possibly by the impact that formed the Urashima crater 5-12 Myr ago. Subsequently, a large-scale resurfacing event formed the western bulge and the fossae 2-9 Myr ago. Following this process, the spin of Ryugu slowed down plausibly due to the YORP effect. The transition of isochrons in a CSFD suggests that Ryugu was decoupled from the main belt and transferred to a near-Earth orbit 0.2-7 Myr ago.

Remote sensing observations are our primary method of studying planetary surfaces, and in the inner solar system, in situ exploration quickly provided ground truth to these remote sensing observations. Our view of the surface appearance of worlds like the Moon, Mars, and even Venus has grown in tandem with our understanding of the large-scale structure from remote sensing. However, our knowledge of the icy worlds of the outer solar system is based solely on decades of remote sensing observations without any in situ surface data to help understand how geological processes are manifest on these worlds. The surfaces of icy worlds like Europa are likely to be truly alien in appearance, dominated by processes such as impact gardening, sputtering, sintering, and other types of physical and chemical weathering that act together in ways we have never yet observed in situ. Remote sensing has revealed that Europa’s surface consists of an icy layer, exposed to the vacuum of space at cryogenic temperatures. The airless rocky Moon may be the best landed analog for Europa’s surface, but the Moon is an old, battered world covered with impact craters, which have gardened the surface to a highly-mixed regolith depth of 5-15 meters overlying kilometers of broken-up megaregolith. Europa’s young surface, approximately tens of millions of years old, likely has a gardening depth on the scale of centimeters up to a meter (Costello et al., AGU Fall Meeting, 2019). The rocky Moon is also compositionally different from icy Europa, and the thermal and radiolytic processes that shape the texture of the uppermost surface of an icy body have no rocky analog. As study of icy worlds has continued on the basis of remote sensing data only, multiple competing models exist for the formation of various surface features. Follow-up flyby and orbital missions may not be able to resolve these situations even with higher-resolution remote sensing data and digital elevation models. Images taken by an in situ surface lander on an icy world such as Europa, coupled with ground truth compositional and other measurements, will be essential to our understanding of how geologic processes work on these worlds. A mission such as a Europa Lander is the necessary next step, and will revolutionize our ability to interpret remote sensing data from myriad other bodies in the outer solar system.

Horse collar aurora (HCA) are an auroral feature where the dawn and dusk sector auroral oval moves polewards and the polar cap becomes teardrop shaped. They form during prolonged periods of northward IMF, when the IMF clock angle is small. Their formation has been linked to dual-lobe reconnection (DLR) closing magnetic flux at the dayside magnetopause. The conditions necessary for DLR are currently not well-understood therefore understanding HCA statistics will allow DLR to be studied in more detail. We have identified over 600 HCA events between 2010 and 2016 in UV images captured by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instrument on-board the Defense Meteorological Satellite Program (DMSP) spacecraft F16, F17 and F18. As expected, there is a clear preference for HCA occurring during northward IMF. We find no clear seasonal dependence in their occurrence, with an average of 8 HCA events per month. The occurrence of HCA events does not appear to depend on the Bx component of the IMF, suggesting that Bx does not modulate the rate of lobe reconnection. Considering the average radiance intensity across the dusk-dawn meridian shows the HCA as a separate bulge inside the auroral oval and that the dawn side arc of the HCA is usually brighter than the dusk in the Lyman-Birge-Hopfield short band (LBHs). We relate this to the expected field aligned current (FAC) pattern of HCA formation. We further suggest that transpolar arcs observed in the dawn sector simultaneously in both northern and southern hemispheres are misidentified HCA.

The Earth’s magnetosheath and cusps are the sources of soft X-rays. In the accompanying paper (Part 1) and this paper, we discuss the methods of finding the magnetopause position by analyzing the X-ray images. We use the software developed for the Soft X-ray Imager (SXI) on board the forthcoming Solar wind - Magnetosphere - Ionosphere Link Explorer (SMILE) mission. We show how to find the maximum SXI count rate in noisy count maps. We verify the assumption that the maximum of the X-ray emissivity integrated along the Line-of-Sight (Ix) is tangent to the magnetopause. We consider two cases using two MHD models and apply different methods of magnetospheric masking. Overall, the magnetopause is located close to the maximum Ix gradient or between the maximum Ix gradient and the maximum Ix depending on the method used. But since the angular distance between the maximum Ix gradient and the maximum Ix is relatively small (about 3{degree sign}), the maximum Ix might be used as an indicator of the outer boundary of a wide magnetopause layer usually obtained in MHD simulations.

Recent estimates of the crustal thickness of Mars show a bimodal result of either ∼20 km or ∼40 km beneath the InSight lander. We propose an approach based on random matrix theory applied to receiver functions to further constrain the subsurface structure. Assuming a spiked covariance model for our data, we first use the phase transition properties of the singular value spectrum of random matrices to detect coherent arrivals in the waveforms. Examples from terrestrial data show how the method works in different scenarios. We identify three new converted arrivals in the InSight data, including the second multiply reflected phase from a deeper third interface. We then use this information to jointly invert receiver functions with the absolute S-wave velocity information in the polarization of body waves. Results show a crustal thickness of 43±5 km beneath the lander with two mid-crustal interfaces at depths of 8.5±1.5 km and 22±3 km.

The magnetopause standoff distance characterizes global magnetospheric compression and deformation in response to changes in the solar wind dynamic pressure and interplanetary magnetic field orientation. We cannot derive this parameter from in-situ spacecraft measurements. However, time-series of the magnetopause standoff distance can be obtained in the near future using observations by soft X-ray imagers. In two companion papers, we describe methods of finding the standoff distance from X-ray images. In Part 1, we present the results of MHD simulations which we use for the calculation of the X-ray emissivity in the magnetosheath and cusps. Some MHD models predict relatively high density in the magnetosphere, larger than observed in the data. Correcting this, we develop magnetospheric masking methods to separate the magnetosphere from the magnetosheath and cusps. We simulate the X-ray emissivity in the magnetosheath for different solar wind conditions and dipole tilts.

Lower-band whistler-mode chorus waves are important to the dynamics of Earth’s radiation belts, playing a key role in accelerating seed population electrons (100’s of keV) to relativistic ($>$ 1 MeV) energies, and in scattering electrons such that they precipitate into the atmosphere. When constructing and using statistical models of lower-band whistler-mode chorus wave power, it is commonly assumed that wave power is spatially distributed with respect to magnetic L-shell. At the same time, these waves are known to drop in power at the plasmapause, a cold plasma boundary which is dynamic in time and space relative to L-shell. This study organizes wave power and propagation direction data with respect to distance from the plasmapause location to evaluate what role the location of the plasmapause may play in defining the spatial distribution of lower band whistler-mode chorus wave power. It is found that characteristics of the statistical spatial distribution of equatorial lower band whistler mode chorus are determined by L-shell, and are largely independent of plasmapause location. The primary physical importance of the plasmapause is to act as an Earthward boundary to lower band whistler mode chorus wave activity. This behavior is consistent with an equatorial lower band whistler mode chorus wave power spatial distribution that follows the L-shell organization of the particles driving wave growth.

Jupiter displays many distinct auroral structures, among which auroral dawn storms and auroral injections are often observed contemporaneously. However, it is unclear if the contemporaneous nature of the observations is a coincidence or part of an underlying physical connection. We show six clear examples from a recent Hubble Space Telescope campaign (GO-14634) that each display both auroral dawn storms and auroral injection signatures. We found that these conjugate phenomena could exist during intervals of either relatively low or high auroral activity, as evidenced by the varied levels of total auroral power. In-situ observations of the magnetosphere by Juno, show a strong magnetic reconnection event inside of 45 Jupiter Radii (RJ) on the predawn sector, followed by two dipolarization events within the following two hours, coincident with the auroral dawn storm and auroral injection event. We therefore suggest that the auroral dawn storm is the manifestation of magnetic reconnection in the dawnside magnetosphere. The dipolarization region mapped to the auroral injection, strongly suggesting that this was associated with the auroral injection. Since magnetic reconnection and dipolarization are physically connected, we therefore suggest that the often-conjugate auroral dawn storm and auroral injection events are also physically connected consequences.

We investigate types of turbulence generated during particle acceleration in 3D Harris-type reconnecting current sheets (RCSs) with magnetic islands, using the particle-in-cell approach. When a guiding magnetic field is present in the RCS, protons and electrons become separated at ejection into the opposite semi-planes, or footpoints of reconnecting magnetic loops, due to the opposite gyration. The particles of the same charge (ions or electrons) ejected from the RCS from the opposite side where they enter called ‘transit’ particles. They are strongly energized and form unidirectional beams in the pitch-angle distribution. While the particles that move back to the same side where they enter the RCS are called ‘bounced’ particles. They gain less energy and form more diffusive pitch-angle distributions. In the RCS with magnetic islands, these two groups of particles are ejected from the X-nullpoint at the end of the islands forming the similar asymmetric distributions in the opposite separatrices. The energy difference between ‘transit’ and ‘bounced’ particles forms ‘bump-on-tail’ velocity distributions that naturally generate plasma turbulence. Lower-hybrid waves are generated into the magnetic islands, owing to the two-stream instabilities. The presence of the anisotropic temperature inside the RCS can introduce whistler waves. High-frequency fluctuations, upper hybrid waves or electron Bernstein waves, pile up near X-nullpoints, which are consistent with MMS observations. We present the wavelet analysis and energy spectra of the turbulent electric and magnetic field fluctuations for different frequencies. The results can be beneficial for understanding in-situ observations of energetic particles in the heliosphere with modern space missions.

Mesospheric winds from two longitudinal sectors at 53$^\circ$N latitude are combined to investigate quasi-two-days (Q2DWs) and their nonlinear interactions with tides. In a summer 2019 case study, we diagnose the zonal wavenumber $m$ of spectral peaks at expected frequencies through two dual-station approaches, a phase differencing technique (PDT) on individual spectral peaks and a least-squares procedure on family-batched peaks. Consistent results from the approaches verify the occurrences of Rossby-gravity modes ($m$=3 and 4 at periods $T$= 2.1d and 1.7d), and their secondary waves (SWs) generated from interactions with diurnal, semi-diurnal, ter-diurnal and quatra-diurnal migrating tides. We further extend the PDT to 2012$\textendash$2019, illustrating that Q2DWs exhibit significant interannual variability. Composite analysis reveals seasonal and altitude variations of the Rossby-gravity modes and their SWs. The Rossby-gravity modes maximize in local summer, whereas their 16- and 9.6-hr SWs appear more in winter, potentially originating from Q2DW-tide interactions in the opposite hemisphere.

Sun is the key driver of the Earth’s climate system, it is essential to understand the interaction between the Sun and the Earth. In this paper, the past space based Total Solar Irradiance (TSI) measurement is presented. According to the instrument operation mode and whether there is a sun tracking platform or not, the space based TSI measurements are divided into three groups: passive sun tracking, dedicated TSI missions and the experiment with an accurate sun tracking system. The configuration and characteristics of solar radiometers of each kind is introduced in detail. The TSI value, which used to be named as solar constant normalized at one astronomical unit is changed from 1365 W/m-2 to 1361 W/m-2 (during the 2008 solar minimum period). The justification of the new lower TSI value is briefly recalled and discussed. A series of solar irradiance references such as International Pyrheliometric Scale (IPS) 1956, World Radiometric Reference (WRR), and the TSI Radiometer Facility (TRF) are also separately recalled. The WRR has an estimated accuracy of 0.3% and guarantees the worldwide homogeneity of radiation measurements within 0.1% precision, which is 0.34%$ higher than the international system of units (SI), while the uncertainty of the TRF facilities to the SI is evaluated and both systems agrees in $0.01\%$. The Solar Irradiance Monitoring (SIM) experiment on FY-3C meteorological satellite measured a TSI value consistent with the new lower values after tracing to the SI scale. % Please include a maximum of seven keywords \keywords{TSI, WRR, SI, Absolute Radiometer}

This paper discusses the mathematical aspects of band fitting and introduces the mathematics of the Asymmetric Gaussian shape and its tangent space for the first time. First, we derive an equation for an Asymmetric Gaussian shape. We then use this equation to derive a rule for the resolution of two Gaussian shaped bands. We then use the Asymmetrical Gaussian equation to derive a Master Equation to fit two overlapping bands. We identify regions of the fitting space where the Asymmetric Gaussian fit is optimal, sub optimal and not optimal. We then demonstrate the use of the Asymmetric Gaussian to fit four overlapping Gaussian bands, and show how this is relevant to the olivine spectral complex at 1 ?m. We develop a new model of the olivine family spectrum based on previous work by Runciman and Burns. The limitations of the asymmetric band fitting method and a critical assessment of three commonly used numerical minimization methods are also provided.

We have to face an important and urgent problem: even though according to spectral detection, we cannot conclude that there is much water ice on the Moon as the prevailing theory claims. We might have overlooked the widespread presence of methanol on the Moon. After the interstellar methanol ice fell onto the Moon, the methanol in it was retained due to the strong adsorption of methanol in the carbon-rich lunar regolith and the water in it could be divided into two situations: one involved in catalytic reactions with methanol on lunar surface and another one escaped to the deep space because of harsh environment. The rest of methanol might still be widespread on lunar surface. M3 is unable to distinguish between hydroxyl radicals from water ice and hydroxyl groups from methanol because the absorption strengths of the two are all 2.9 μm, and there are no established methods to distinguish them using the 2.9μm band. Thus, most of the lunar water detected by M3 might be lunar methanol. Attention should be paid to previous misreading of the spectrum. The so-called surficial water illogically appeared at lunar equator, seriously shaking the credibility of M3 spectra data analysis. The vast quantities of hydrogen found in lunar polar craters should be hydrogen ice, which easy to confuse with water ice. The author has also made a preliminary study of the physical / chemical process chains on lunar surface. It is necessary to conduct in-depth research in this field in the future.

The Wang-Sheeley-Arge (WSA) model estimates the solar wind speed and interplanetary magnetic field polarity at any point in the inner heliosphere using global photospheric magnetic field maps as input. WSA employs the Potential Field Source Surface (PFSS) and Schatten Current Sheet (SCS) models to determine the Sun’s global coronal magnetic field configuration. The PFSS and SCS models are connected through two radial parameters, the source surface and interface radii, which specify the overlap region between the inner SCS and outer PFSS model. Though both radii are adjustable within the WSA model, they have typically been fixed to 2.5 R sol. Our work highlights how the solar wind predictions improve when the radii are allowed to vary over time. Data assimilation using particle filtering (sequential Monte Carlo) is used to infer the optimal values over a fixed time window. The Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model generates an ensemble of photospheric maps that are used to drive WSA. When the solar wind model predictions and satellite observations are used in a newly-developed quality-of- agreement metric, sets of metric values are generated. These metric values are assumed to roughly correspond to the probability of the two key model radii. The highest metric value implies the optimal radii. Data assimilation entails additional choices relating to input realization and timeframe, with implications for variation in the solar wind over time. We present this work in its theoretical context and with practical applications for prediction accuracy.

We will present signal processing techniques based on shape analysis of the time-frequency signatures of chorus elements in the Van Allen Radiation Belts. Specifically, we will employ the Radon transform and the Distance Transform, which are well-known for isolating local shapes and patterns in the image processing literature, to achieve automated detection of the spectral morphology of chorus elements. In particular, we will introduce “shrink-wrapping” techniques that quantify the salient features defining the microstructure of chorus elements. We will present preliminary results based on case studies of the EMFISIS data from the Van Allen Radiation Belts mission.