Colloquium

Energetic Electron Precipitation into Earth’s Upper Atmosphere by Plasma Waves: The Role of Nonlinear Interactions

sheryls — Mon, 24 Nov 2025 18:55:42 +0000

Energetic Electron Precipitation into Earth’s Upper Atmosphere by Plasma Waves: The Role of Nonlinear Interactions sheryls Mon, 11/24/2025 - 11:55

When (times in MT)

Wed, Dec 3 2025, 2pm - 1 hour

Event Type

Colloquium

Speaker

Longzhi Gan

Affiliation

Boston University

Building & Room

CG1-3131

Webcast or Recording Link

https://www.youtube.com/watch?v=bAbQUXCf9GM&list=PLUJIX4Fd9achZyUgsRG--vYg7cRry…

Energetic electron precipitation (EEP) into Earth’s upper atmosphere is a key mechanism regulating the dynamics of the outer radiation belt. By scattering electrons into the atmospheric loss cone, precipitation both depletes the radiation belt population and couples magnetospheric processes to the upper atmosphere. Plasma waves play a central role in this process. In particular, whistler-mode chorus waves and lightning-generated whistlers drive pitch-angle scattering that produces short-lived but intense bursts of precipitation, as well as more continuous fluxes. Recent observations from CubeSats (ELFIN), balloon campaigns (BARREL), and LEO satellites (SAMPEX) provide detailed measurements of such precipitation. Simulations of events observed by these spacecrafts reveal multiple linear and quasi-linear processes that together drive precipitation, which will be discussed in this presentation.

Beyond these linear and quasi-linear processes, nonlinear wave–particle interactions are increasingly recognized as critical. For intense chorus waves, anomalous nonlinear interactions—recently revisited after being overlooked for decades—can inhibit precipitation by trapping electrons outside the loss cone. This challenges long-standing theoretical assumptions and modifies estimates of radiation belt loss rates. Recent studies on the role of nonlinear interactions in precipitation will also be presented.

About the Speaker

I am a research scientist at the Center for Space Physics, Boston University. I am currently visiting LASP host by Professor Lauren Blum. I got my PhD at the Astronomy department, Boston University with dissertation focused on nonlinear wave particle interactions and continued to work in Professor Wen Li’s group afterwards. My current research focuses on both the development of a global kinetic model that incorporates nonlinear interactions and the energetic electron precipitation driven by various plasma waves.

Neural Enhancement of the Traditional WSA Solar Wind Relation

sheryls — Tue, 18 Nov 2025 21:39:15 +0000

Neural Enhancement of the Traditional WSA Solar Wind Relation sheryls Tue, 11/18/2025 - 14:39

When (times in MT)

Wed, Dec 10 2025, 2pm - 1 hour

Event Type

Colloquium

Speaker

Prateek Mayank

Affiliation

NASA Jack Eddy Postdoctoral Fellow at UCAR CPAESS & SWx TREC, CU Boulder

Building & Room

CG1-3131

Webcast or Recording Link

https://www.youtube.com/watch?v=duV8NoCoYmc&list=PLUJIX4Fd9achZyUgsRG--vYg7cRry…

The Wang–Sheeley–Arge (WSA) model has been the cornerstone of operational solar wind forecasting for nearly two decades, owing to its simplicity and physics-based formalism. However, its performance is strongly dependent on several empirical parameters that are typically fixed or tuned manually, limiting its adaptability across varying solar conditions. In this colloquium, I will present a neural enhancement to the WSA framework (referred to as WSA+) that systematically optimizes the WSA solar wind speed using in situ observations within a differentiable physics-constrained pipeline. The approach operates in two stages: first, a neural optimizer adjusts WSA parameters independently for each Carrington rotation to better match the observed solar wind data. Then, a neural network learns to predict these optimized speed maps directly from magnetogram-derived features. This enables generalization of the optimization process and allows inference for new solar conditions without manual tuning. WSA+ preserves the interpretability of the original relation while significantly improving the match with OMNI in situ data across multiple performance metrics, including correlation and error statistics. It consistently outperforms the traditional WSA relation across both low and high solar activity periods, with average improvements of approximately 40%. By integrating data-driven learning with physical constraints, WSA+ offers a robust and adaptable enhancement, with immediate utility as a drop-in replacement in global heliospheric modeling pipelines. I will also showcase the open-source Python package for WSA+, enabling the broader community to apply, reproduce, and extend the framework.

About the Speaker

I completed my PhD at the Indian Institute of Technology Indore, India, supported by the prestigious Prime Minister’s Research Fellowship. During my PhD, I developed the SWASTi framework - a MHD-based solar wind and CME model. After my PhD, I joined SWx TREC as a NASA Jack Eddy Postdoctoral Fellow with Enrico Camporeale. My current research focuses on enhancing physics-based space weather forecasting models through AI/ML approaches.

What is that? Observing in the Sun’s corona at 63 kilometers resolution…

sheryls — Thu, 13 Nov 2025 19:12:36 +0000

What is that? Observing in the Sun’s corona at 63 kilometers resolution… sheryls Thu, 11/13/2025 - 12:12

When (times in MT)

Wed, Nov 19 2025, 2pm - 1 hour

Event Type

Colloquium

Speaker

Dirk Schmidt

Affiliation

NSO

Building & Room

CG1-3131

“Observing plasma phenomena in the Sun’s corona at the diffraction limit of large ground-based telescopes” - what still sounded like a keen vision only 3 years ago is now reality.

Ever since HAO’s founder Walter Orr Roberts produced his captivating videos of prominences in the 1940’s at the Climax Observatory, turbulence in Earth’s atmosphere has limited the resolution from the ground to many hundreds of kilometers, and little is still known about plasma dynamics in the corona at scales below 100 km.

Adaptive optics (AO) that compensate turbulence and recover the diffraction limit became a standard technique since their advent in the late 90’s, revolutionizing observations and our picture of the Sun. However, until recently, even the most advanced AO systems were only capable to target within the solar disk and hence they still left fine detail far above the limb hidden in the atmospheric blur.

Join this talk to see prominences in unparalleled clarity and features well below 100 km thanks to a breakthrough in AO with the Goode Solar Telescope (GST).

Cona, the first coronal adaptive optics system, was developed by the National Solar Observatory and the New Jersey Institute of Technology and enables observations in the Sun’s corona at the H⍺ diffraction limit of 63 km. Cona revealed the finest strands in coronal rain to date and a puzzling short-lived feature with not-readily explained dynamics far below the resolution of other observations from the ground and from space.

Over 30 hours of high-resolution H⍺ and He I line-scan data from GST/VIS and NIRIS of various types of prominences, coronal rain, plasmoids, spicules, plumes, and bubbles, as well as other features are now publicly available. We will take a look at the highlights and most intriguing examples.

About the Speaker

Dirk Schmidt develops next-generation adaptive optics at NSO for DKIST. He works closely with Big Bear Solar Observatory implementing adaptive optics and maturing advanced concepts for science operations at the Goode Solar Telescope.

Introduction to Surya: A Foundation Model in Heliophysics

sheryls — Mon, 10 Nov 2025 20:45:37 +0000

Introduction to Surya: A Foundation Model in Heliophysics sheryls Mon, 11/10/2025 - 13:45

When (times in MT)

Wed, Nov 12 2025, 2pm - 1 hour

Event Type

Colloquium

Speaker

Andrés Muñoz-Jaramillo

Affiliation

SwRI

Building & Room

CG1-3131

Webcast or Recording Link

https://www.youtube.com/watch?v=J27Cxy47n4g&list=PLUJIX4Fd9achZyUgsRG--vYg7cRry…

Artificial Intelligence (AI) has emerged as a transformative tool for establishing connections between data and acting as a tool that empowers humans to solve a wide variety of problems for which there were no easy solutions. In heliophysics, AI has been applied to a wide variety of problems including space weather forecast, data calibration and homogenization, computer vision (i.e. segmentation), coronal field extrapolation, etc. To this date, the overwhelming majority of AI applications in Heliophysics are targeted and designed to address specific problems. However, the rise of very powerful multi-purpose models has revolutionized natural language applications (e.g. GPT) and have the potential to revolutionize how we derive scientific value from vast quantities of data.

Large multi-purpose AI models, i.e. “Foundation Models”, are large AI models that are self-trained on vast quantities of data to enable a wide range of applications, while paying the lionshare of the training cost upfront. Successful foundation models, such as GPT-4, can then be fine-tuned at a fraction of the cost by anyone with access to the pre-trained model. In this talk we will introduce the concept of Foundation models, how they are built, and how they can be used. We will focus on Surya, a NASA-funded foundation model, constructed using data from the Solar Dynamics Observatory (SDO). We’ll show preliminary results, our validation strategies, and how we aim to push the Surya project beyond the training of large models with vast quantities of data. Our vision involves the creation of frameworks alongside the trained model that enable an entire community to use the foundation model for scientific inference and we’ll discuss our efforts to achieve that. Finally, we will discuss some interesting potential applications of Surya that can elevate our use of foundation models.

Andrés Muñoz-Jaramillo, SwRI, Madhulika Guhathakurta, NASA HQ, and the Surya team

About the Speaker

I am originally from Colombia where I did my Undergrads in Physics and Electric Engineering. I came to Montana State University for my PhD, which I finished in 2010. My focus was solar dynamo simulations. After my PhD I did a postdoc at the Harvard-Smithsonian CfA and a Jack Eddy Fellowship. Then I became a Researcher for Georgia State University in 2013. My focus during my postdoc, and GSU years was historic data restoration including faculae, sunspot areas, and magnetograms. All focused towards understanding long-term solar variability. Since 2017, I joined SwRI and my focus has been on different applications of Artificial Intelligence. This includes space weather forecast, instrument calibration, pattern finding and pattern classification, integration of physics with AI models, and more recently, training and using foundation models.

Flashes, Flares, and Aftershocks: Uncovering Unique Solar Flare Signatures with the Dunn Solar Telescope

sheryls — Sun, 09 Nov 2025 15:35:05 +0000

Flashes, Flares, and Aftershocks: Uncovering Unique Solar Flare Signatures with the Dunn Solar Telescope sheryls Sun, 11/09/2025 - 08:35

When (times in MT)

Thu, Nov 13 2025, 2pm - 1 hour

Event Type

Colloquium

Speaker

Juie Shetye

Affiliation

New Mexico State University

Building & Room

CG1-3131

Webcast or Recording Link

https://www.youtube.com/watch?v=q70TT0w4hb0&list=PLUJIX4Fd9achZyUgsRG--vYg7cRry…

Solar flares are sudden releases of magnetic energy, driving adverse space weather that can disrupt radio communications, degrade GPS accuracy, and pose risks to satellites and astronauts. While multi-day forecasts exist, operational entities require actionable, minute-scale nowcasts for immediate mitigation. This talk presents a new, observationally-driven nowcasting approach to address this critical gap.

We introduce a real-time method using high-cadence observations of the chromosphere in the Ca II K line (393.4 nm) from the Dunn Solar Telescope. An efficient algorithm monitors intensity in active regions to detect the sharp, impulsive rise phase of a flare, a direct thermal response to initial particle beams. We compare the timing of these Ca II K peaks against the standard 1-8 Å soft X-ray (SXR) flux curves from NOAA’s GOES satellites, which define the official flare peak.
Our analysis of C- to M-class flares demonstrates a consistent, operationally significant result: the impulsive Ca II K peak typically precedes the GOES SXR peak by 20 to 30 minutes. This lead time provides a reliable warning signal, offering a crucial window for stakeholders to take protective action before the flare's most intense phase.

Additionally, we present a complementary analysis of an X-class event, revealing a distinct pattern of multiple, sequential secondary brightenings deep into the post-flare decay phase. These "aftershocks" suggest continued, smaller-scale energy release not captured by standard models. We will discuss representative examples and explore working hypotheses for their drivers.

This talk connects the development of a high-impact operational nowcast with new scientific questions about flare energy release. We will conclude by charting next steps for refining this method and its potential for adoption across a global network of ground-based solar observatories.

About the Speaker

Dr. Juie Shetye is an Assistant Professor of Astronomy at New Mexico State University and the Science Lead/Director for the Dunn Solar Telescope at Sunspot Solar Observatory. Her research focuses on high-cadence observations of the solar chromosphere, including jets, swirls, and practical flare nowcasting, and she is a co-author on the Sunspot Solar Observatory Data Archive operations paper. Recent work includes first high-resolution observations of chromospheric swirls from the Dunn. She completed a master’s in Space Science at University College London and a PhD in Physics at Queen’s University Belfast.

Invert Everything Everywhere All at Once

sheryls — Thu, 16 Oct 2025 21:03:19 +0000

Invert Everything Everywhere All at Once sheryls Thu, 10/16/2025 - 15:03

When (times in MT)

Wed, Nov 5 2025, 2pm - 1 hour

Event Type

Colloquium

Speaker

Christoph Keller

Affiliation

NSO

Building & Room

CG1-3131

Webcast or Recording Link

https://www.youtube.com/watch?v=Jv-uBHUe1Gk&list=PLUJIX4Fd9achZyUgsRG--vYg7cRry…

What if we could give any combination of observations of a particular area or event on the Sun along with equations describing the physics to a universal code that creates a physically self-consistent model that explains all the observations? What if we do not need to tell the code how to solve the physics equations? What if the resulting model lives in a space-time continuum without any grid? What if the model could even predict how the Sun evolves after the observations have stopped? What if this inversion science fiction could become reality? In this presentation, I will explain how this could be done using physics-informed neural networks and illustrate it with an extreme inversion problem: deriving velocities, densities, and temperatures as a function of three spatial dimensions and time using only a sequence of continuum images.

About the Speaker

Christoph Keller’s research expertise spans exoplanets, solar and stellar magnetic fields, planetary atmospheres, and innovative optical instruments for astronomy, remote sensing, and biomedical imaging. He authored or co-authored over 450 publications and received the Friedrich Wilhelm Bessel award for outstanding astrophysics research. Christoph’s career includes a decade at the National Solar Observatory in Tucson, where he led the iconic McMath-Pierce Solar Telescope. He then joined Utrecht University, becoming its Astronomical Institute director. He served on oversight and visiting committees and chaired the board of the Isaac Newton Group of telescopes on the Canary Islands. After 10 years at Leiden University, he joined Lowell Observatory as Director of Science in 2022 and returned to NSO as Director in May 2024, focusing on fostering a conducive environment for scientific research.

Multiscale features in ICMEs and CIRs and Their Space Weather Implications

sheryls — Tue, 30 Sep 2025 18:08:46 +0000

Multiscale features in ICMEs and CIRs and Their Space Weather Implications sheryls Tue, 09/30/2025 - 12:08

When (times in MT)

Tue, Oct 7 2025, 1pm - 1 hour

Event Type

Colloquium

Speaker

Anil Raghav

Affiliation

University of Mumbai

Building & Room

CG1-3131

Webcast or Recording Link

https://www.youtube.com/watch?v=jBBVx0KTnR4&list=PLUJIX4Fd9achZyUgsRG--vYg7cRry…

Interplanetary Coronal Mass Ejections (ICMEs) and Corotating Interaction Regions (CIRs) are central drivers of heliospheric variability and space weather disturbances. The talk will focus on multiscale characterization of ICMEs and CIRs, including the identification of Alfvén waves and kinetic scale waves, planarity features, and thermodynamic studies through the polytropic index. Local structures such as current sheets, small-scale flux ropes, highly fluctuating magnetic field patches, and high-temperature regions inside ICMEs and CIRs will also be discussed. Finally, the talk will highlight the linkages between these multiscale plasma processes and their implications for space weather, particularly their role in driving magnetospheric disturbances.

The magnetic origin of the solar wind and CMEs

sheryls — Thu, 25 Sep 2025 16:50:27 +0000

The magnetic origin of the solar wind and CMEs sheryls Thu, 09/25/2025 - 10:50

When (times in MT)

Wed, Oct 29 2025, 2pm - 1 hour

Event Type

Colloquium

Speaker

BC Low

Affiliation

HAO, retired

Building & Room

CG1-3131

Webcast or Recording Link

https://youtu.be/AyBHUYISRNk

The polytropic fluid provides an elementary but conceptually complete understanding of natural failings of gravitational confinement in the open atmosphere of the Sun, giving rise to the solar wind filling interplanetary space out to beyond Pluto, and the almost daily expulsions of CMEs from the low corona. Magnetic fluxes continually emerging from the interior solar dynamo play central roles. The ubiquitous Parker spontaneous current-sheets by their resistive dissipation maintain the million-degree hot, fully ionized corona as a near-perfect conductor of heat and electricity. Excessive accumulated magnetic fluxes in the corona drive CMEs with a self-similarity shared with solar gravity. These pretty hydromagnetic properties will be described with a minimum of mathematical details.

Helicity turbulence model: Validations and application to stellar angular-momentum transport

sheryls — Mon, 22 Sep 2025 16:49:53 +0000

Helicity turbulence model: Validations and application to stellar angular-momentum transport sheryls Mon, 09/22/2025 - 10:49

When (times in MT)

Tue, Oct 14 2025, 11am - 1 hour

Event Type

Colloquium

Speaker

Nobumitsu Yokoi

Affiliation

Institute of Industrial Science, University of Tokyo

Building & Room

CG1-3131

Webcast or Recording Link

https://www.youtube.com/watch?v=dMQQKvLiGus&list=PLUJIX4Fd9achZyUgsRG--vYg7cRry…

Helicity, as an inviscid invariant of a system of fluid equations, may contribute in a crucial way to the dynamic behaviors and statistical properties of turbulence [1,2]. It is shown that the inhomogeneous turbulent helicity enters the Reynolds-stress expression as the coupling coefficient of the mean absolute vorticity (anti-symmetric part of velocity shear), and counter-balances the eddy-viscosity coupled with the mean velocity strain (symmetric part of velocity shear) [3,4]. A subgrid-scale (SGS) turbulence model with structural effects incorporated through the SGS helicity is constructed [5] and validated with the aid of a series of high-resolution numerical simulations [6]. The helicity turbulence model is applied to the stellar convection as one of the possible prescriptions of the effective angular-momentum transport problem in a star [7].

References
[1] Pouquet, A. and Yokoi, N. Phil. Trans. Roy. Soc. A 387, 2021-0087-1-18 (2022). https://doi.org/10.1098/rsta.2021.0087
[2] Yokoi, N. "Transport in helical fluid turbulence," in Helicities in Geophysics, Astrophysics, and Beyond (Eds.) Kuzanyan, Yokoi, Gregoulis, and Stepanov, pp. 25-50 (2024). https://doi.org/10.1002/9781119841715.ch3
[3] Yokoi, N. and Yoshizawa, A. "Statistical analysis of the effects of helicity in inhomogeneous turbulence," Phys. Fluids A 5, 464-477 (1993). https://doi.org/10.1063/1.858869
[4] Yokoi, N. and Brandenburg, A. "Large-scale ﬂow generation by inhomogeneous helicity," Phys. Rev. E, 93, 033125-1-14 (2016). https://doi.org/10.1103/PhysRevE.93.033125
[5] Yokoi, N. and Yoshizawa, A. "Subgrid-scale model with structural effects incorporated through the helicity," Progress in Turbulence VII 115-121 (2017). https://doi.org/10.1007/978-3-319-57934-4_17
[6] Yokoi, N., Mininni, P., Pouquet, A., Rosenberg, D., and Marino, R. "Helicity subgrid-scale model and its numerical validation," Phys. Fluids 1-34 (to be submitted).
[7] Yokoi, N. and Miesch, M. S. "Kinetic helicity effects in stellar angular-momentum transport," Geophys. Astrophys. Fluid Dyn. 119, 1-32 (2025). https://doi.org/10.1080/03091929.2025.2502908

About the Speaker

Nobu Yokoi is a physicist working on analytical theories and modeling of hydrodynamic and magnetohydrodynamic turbulence. He got his PhD in 1995 at Department of Physics, University of Tokyo with the work on helicities: "Relationship of pseudoscalar invariants with the sustainment of global structures in hydrodynamic and magnetohydrodynamic turbulence". With the aid of the multiple-scale direct-interaction approximation: a combination of renormalized perturbation expansion theory and multiple-scale analysis, Nobu has explored the turbulent fluxes in inhomogeneous, anisotropic, and non-equilibrium turbulence from the fundamental equations. His interests range over the formation of large-scale vortical structures, turbulent dynamos in geophysical and astrophysical bodies, magnetic reconnection in turbulent media, transport suppression in fusion and engineering devices, the electromotive force, mass and heat transports in strongly compressible MHD turbulence, angular-momentum and energy fluxes in stellar convection, shock-wave / turbulent-boundary-layer interaction. He has collaborated with lots of applied mathematicians, physicists, astrophysicists, space and fusion plasma scientists, engineers, as well as solar physicists.

Inter-hemispheric asymmetry in the high-latitude electrodynamics and its impact on the coupled magnetosphere-ionosphere-thermosphere

sheryls — Fri, 19 Sep 2025 19:02:44 +0000

Inter-hemispheric asymmetry in the high-latitude electrodynamics and its impact on the coupled magnetosphere-ionosphere-thermosphere sheryls Fri, 09/19/2025 - 13:02

When (times in MT)

Wed, Oct 1 2025, 2pm - 1 hour

Event Type

Colloquium

Speaker

Yu Hong (Jonas)

Affiliation

NCAR ASP Postdoc

Building & Room

CG1-3131

Webcast or Recording Link

https://www.youtube.com/watch?v=lZFcO0H3bFg&list=PLUJIX4Fd9achZyUgsRG--vYg7cRry…

Our understanding of geospace often assumes the northern and southern hemispheres respond symmetrically to Sun–Earth interactions—but this is not the case. Our studies investigate inter-hemispheric asymmetries (IHAs) in the high-latitude electrodynamics and their impacts on the coupled magnetosphere-ionosphere-thermosphere (M-I-T) system, using multi-satellite observations and advanced numerical model simulations. The work addresses three key questions: (1) Why are the ionosphere and thermosphere different between hemispheres? (2) How do these differences influence the geospace environment? and (3) How can we better detect and quantify these asymmetries across scales? Our results show that the IHA is not a minor phenomenon but has important implications for understanding the coupled magnetosphere-ionosphere-thermosphere.

About the Speaker

Dr. Hong is an NCAR ASP Postdoc Fellow I at HAO, hosted by Drs. Kevin Pham, Wenbin Wang, and Gang Lu. He received his Ph.D. in Space Physics from the University of Texas at Arlington in August 2025, where he was advised by Dr. Yue Deng. His research focuses on understanding inter-hemispheric asymmetries in the ionosphere-thermosphere and their impacts on geospace, through a combination of observational data and numerical models, including the Space Weather Modeling Framework (SWMF) and the Global Ionosphere Thermosphere Model (GITM). Now at HAO, Dr. Hong will investigate mass transfer between the ionosphere-thermosphere and the magnetosphere using coupled TIEGCM and HIDRA-SAMI3 simulations.