Mausumi Dikpati

Analysis Of Short-term Solar Activity Variability and Estimating Timings of Next Enhanced Bursts

whawkins — Tue, 11 Nov 2025 21:45:29 +0000

Analysis Of Short-term Solar Activity Variability and Estimating Timings of Next Enhanced Bursts whawkins Tue, 11/11/2025 - 14:45

Author:

whawkins

Nov 11, 2025

Zoomed-in burst-envelope forecasts from January 2024 to April 2026. Top: The Northern Hemisphere SSN with inferred RF (Random Forest) bursts properties. Middle: The Southern hemisphere counterpart. Bottom: Total (Northern Hemisphere + Southern Hemisphere) SSN, highlighting the same burst timings and amplitudes.

The Astrophysical Journal: A novel machine-learning-based hybrid forecasting strategy for predicting next enhanced burst of solar activity is presented. This hybrid forecast-system combines numerical, statistical, and machine-learning techniques to detect the occurrence of the next bursts of solar activity. These enhanced bursts are called “space weather seasons” that occur on intermediate timescales (6–18 months). Monthly smoothed sunspot number (SSN) data from 1878 to 2025 are analyzed using Gaussian fitting techniques to identify burst events and their properties such as amplitude and duration. The SSN data are divided into training, test, and forecast, which shows hindcast and forecast. Each hemisphere is modeled via a Seasonal Autoregressive Integrated Moving Average (SARIMA) approach, refined with an asymmetric Gaussian override to capture rapid burst rise and gradual decay, and burst amplitudes and duration are predicted using a Random Forest (RF) regression model. This hybrid approach successfully hindcasts burst timing in between November 2024 and May 2025, with a peak SSN of ∼70 around March 2025 for the Northern Hemisphere. The next burst in the Northern Hemisphere is forecast to be in December 2025 with a slightly lower SSN of 60. By contrast, the Southern Hemisphere shows relatively complicated behavior, where the bursts show multiple amplitudes starting approximately in October 2024 and ending in October 2025. The main burst shows an amplitude of 130 SSN. The next burst in the Southern Hemisphere is forecast to occur approximately in December 2025. Combining SSN properties in both hemispheres, we find that the total SSN is mainly influenced by a stronger cycle in the Southern Hemisphere.

HAO research featured on AAS Nova

whawkins — Tue, 29 Jul 2025 21:03:34 +0000

HAO research featured on AAS Nova whawkins Tue, 07/29/2025 - 15:03

Mother's Day Superstorms: Pre- and Post-storm Evolutionary Patterns of AR 13664/8

whawkins — Tue, 24 Jun 2025 18:13:37 +0000

Mother's Day Superstorms: Pre- and Post-storm Evolutionary Patterns of AR 13664/8 whawkins Tue, 06/24/2025 - 12:13

Author:

whawkins

Jun 24, 2025

Top: Global-scale toroid patterns indicate ARs 13664 and 13668 were located in the south-toroid in such a way as to be sufficiently away from ARs in the north-toroid, indicating probability of their eruption; close proximity of ARs 13664 and 13668 indicates the possibility of complex interactions between them. Bottom: Small-scale evolution of AR13664/8 is shown with three snapshots from HMI continuum (left) and radial magnetic field(right). The active region at the right side of the first frame was denoted as AR13664 first, and AR 13668 emerged to the east of it. Multiple pairs of bipoles emerged with the positive and negative polarities seen in white and black, respectively.

The Astrophysical Journal: In the week including Mother's day 2024, active region (AR) 13664 became superactive when AR\,13668 emerged nearby, causing multiple X-class flares and CMEs, and activity level increased similar to that inferred from geomagnetic storms associated with the historic 1859 events. By analyzing bot global warped toroids on which the active regions are strung, and active-region-scale magnetic flux and helicity, we find: (i) North and South toroids have nearly identical warped patterns, with mostly longitudinal wave numbers $m=1-3$; (ii) in three longitude intervals North and South toroids were tipped away from each other in latitude, with a longitude phase-shift between them, creating locations most prone for AR eruptions; (iii) on active-region-scale, vector magnetic fields deviate far from potential fields, and therefore contain large amounts of magnetic 'free energy' available for conversion into kinetic energy and high temperature radiation; (iv) the positive and negative polarities converge toward each other, facilitating reconnection and magnetic energy release; (v) rapid changes in magnetic helicity caused by helicity injection from below that creates helicity imbalances. We conclude that the Mother's day superstorms were caused by enhanced magnetic complexity occurring due to intricate interactions among multiple active regions emerging at nearly the same locations. This suggests, predicting locations of magnetically complex ARs, and studying and tracking their eruptive states using different proxy parameters, can greatly improve our ability to forecast intense storms, not only hours but potentially weeks in advance.

A Magnetohydrodynamic Mechanism for the Formation of Solar Polar Vortices

whawkins — Wed, 13 Nov 2024 16:03:34 +0000

A Magnetohydrodynamic Mechanism for the Formation of Solar Polar Vortices whawkins Wed, 11/13/2024 - 09:03

Author:

whawkins

Nov 13, 2024

PNAS (Proceedings of National Academy of Sciences): Polar vortices are ubiquitous features of planetary atmospheric flows, from the Earth-like rocky planets to Jupiter- and Saturn-like gas giant planets. Very little is known about their existence or dynamics on the Sun. What should be expected near the Sun’s pole for the upcoming solar multi-viewpoint and polar missions? Here we report the first magnetohydrodynamic nonlinear simulations for the formation and evolution of solar polar vortices using a near-surface magnetohydrodynamic shallow-water model. Our findings indicate that the rush-to-the-poles, the migration of magnetic fields towards the pole following the Sun’s magnetic cycle, can positively contribute to the formation of polar vortices. The mechanism proposed here for the formation of polar vortices is the first one to involve the role of magnetic fields and may be relevant to any star with a magnetic cycle. The Sun’s polar vortices resulting from this mechanism are predominantly magnetohydrodynamic, consisting of a tight pair of cyclonic and anticyclonic swirls. This mechanism is likely to operate during all solar cycle phases except the peak, when the polar field reverses. Polar vortices can impact dynamical evolution of global flows and polar fields, which seed the next activity cycle, hence better knowledge of physics of polar regions may lead to improved solar cycle and space weather forecasts. See: NSF-NCAR news website.

Simulations of magnetohydrodynamically governed polar vortices for a 30-degree inclined view (left) and for a polar view (right). Magnetohydrodynamic simulations show that the initial mid-latitude perturbations tend to drift and cluster around the forming multiple complex cyclonic and anticyclonic swirls. Following the polar rush, these swirls ultimately lead to an evolved configuration consisting of a pair of tight swirls with m=1 pattern.

Spectra of solar shallow-water waves from bright point observations

whawkins — Tue, 05 Nov 2024 16:54:14 +0000

Spectra of solar shallow-water waves from bright point observations whawkins Tue, 11/05/2024 - 09:54

Author:

whawkins

Nov 5, 2024

Astronomy & Astrophysics: Rossby waves, large-scale meandering patterns drifting in longitude, detected in the Sun, were recently shown to a play a crucial role in understanding "seasons” of space weather. Unlike purely classical Earth's atmospheric Rossby waves, the solar counterparts are strongly magnetized and most likely originate in the tachocline. Because of their deeper origin, detecting these magnetized Rossby waves is a challenging task, relying on careful observations of long-lived longitudinally-drifting magnetic patterns at the surface and above.
Here, we utilize 3 years of global, synchronous observations of coronal bright point densities to obtain empirical signatures of dispersion relations that can be attributed to the simulated waves in tachocline. By tracking the bright point densities at selected latitudes, we compute their wave-number X frequency spectra. Wave-number X frequency spectra is computed utilizing the Wheeler-Kiladis method. This method has been extensively used in the identification of equatorial waves in Earth's atmosphere by highlighting spectral peaks in wave-number X frequency space.
Our results are compatible with the predictions of magneto-Rossby waves with typical periods of several months and inertio-gravity waves with typical periods of a few weeks, depending on the background magnetic field's strength and stratification at convection-zone base. Our analysis suggests that magnetized Rossby waves originate from the tachocline toroidal field of up to 15 kG. Global observations of bright points over extended periods will allow us better constraint the stratification and magnetic field strength in the tachocline.

(a) and (b) represent, respectively, the Hovmoller (time × longitude) diagram at 30◦ latitudes. (c) represents the wavenumber × frequency
spectrum at the same latitude.

Evolution Of Amplitude And Longitude Phase Of Tachocline Rossby Waves Diffusing To The Photosphere

whawkins — Tue, 29 Oct 2024 19:38:58 +0000

Evolution Of Amplitude And Longitude Phase Of Tachocline Rossby Waves Diffusing To The Photosphere whawkins Tue, 10/29/2024 - 13:38

Author:

whawkins

Oct 29, 2024

MNRAS— (Published: 05 November 2024) Physics of MHD Rossby waves in the tachocline-layer were studied by Dikpati, Gilman, Chatterjee et al. (2020) using a fluid-particle-trajectory approach along with solving vorticity and induction equations. By extending the 2020 MHD Rossby wave model to include a hydrodynamic turbulent convection zone (CZ), they were able to examine how MHD Rossby waves generated in the tachocline might diffuse upward through the CZ to the solar surface. Major findings from this current study include (i) pure hydrodynamic Rossby wave amplitudes decline with height due to viscous diffusion at a rate that is independent of viscosity and increases with longitude wavenumber, (ii) fast MHD Rossby waves amplitude declines faster with height for increasing toroidal field, due to their longitude-phase shifting with height, which increases dissipation of kinetic energy in the wave velocities, (iii) slow MHD Rossby waves decline even faster with height because their longitude-phase shifts more rapidly with height, due to their slow phase speed. Furthermore, it was also found that low wavenumber HD and fast MHD Rossby waves, originating in the tachocline, might be detected at the photosphere, but slow MHD Rossby waves should be virtually impossible to detect. An inference from fluid particle trajectories that wave amplitudes declining with height and longitude phase shifting with height associated with decline, implies a powerful mechanism for tangling of magnetic fields, distinct from convective turbulence effects.

Amplitude decline with height of fast and slow MHD Rossby waves at the top of the channel, centered at 45 degrees latitude, compared to the bottom as a function of toroidal field strength, in kiloGauss, for longitudinal wave numbers m = 1 − 10. Left frame: fast waves; right frame: slow waves. Waves for which amplitude at top is smaller than 10−5 compared to the bottom are not plotted. Amplitude decline with height of the zero kG slow wave is included as a limiting case, even though it does not actually exist in that limit. In the limit of zero toroidal field, the fast wave becomes the hydrodynamic Rossby wave.

Global and Local Dynamics of X-flare Producing Active Regions During Solar Cycle 25 Peak-Phase

whawkins — Fri, 06 Sep 2024 16:54:25 +0000

Global and Local Dynamics of X-flare Producing Active Regions During Solar Cycle 25 Peak-Phase whawkins Fri, 09/06/2024 - 10:54

Author:

whawkins

Sep 6, 2024

Astronomy & Astrophysics: As solar cycle (SC) 25 approaches its peak, a number of significant (X-class) flares have been produced. Here, we investigate the circumstances under which two of the most flare-prolific active regions of solar cycle 25, namely ARs 13590 and 13514, flared. Two aspects of the evolution of these active regions are investigated: the global-scale magnetic toroid configuration and small-scale magnetic field morphology and topology, prior, during and after the onset of major flares.

All active regions numbered by NOAA are spotted and marked on 21st February 2024 synoptic map constructed from SDO/HMI daily fits files. The double-arrowed top bar indicates which active regions are on the front side. Here, active regions resulting in X-class Flares are highlighted in red, while active regions resulting in M-class flares are highlighted in orange. Blue and red curves represent, respectively, the Northern and Southern Hemisphere magnetic toroid.

Exploring Spatial and Temporal Patterns in the Debrecen Solar Faculae Database

whawkins — Thu, 11 Apr 2024 21:47:05 +0000

Exploring Spatial and Temporal Patterns in the Debrecen Solar Faculae Database whawkins Thu, 04/11/2024 - 15:47

Author:

whawkins

Apr 11, 2024

The Astrophysical Journal: Photospheric faculae are markers of the solar magnetic field, appearing as bright regions along the edges of granules on the Sun's surface. Mausumi Dikpati et al., using data from the Debrecen Solar Faculae Database, investigated the spatiotemporal distribution of photospheric faculae between 2010 May 1 and 2014 December 31 and found the following. (i) At lower latitudes, there is an enhanced abundance of faculae appearing as stripes at given Carrington longitudes, which are interpreted as indicative of the presence of active longitudes. (ii) At higher latitudes, we identified so-called crisscross patterns of facular appearance. These patterns are likely the result of faculae in regions situated along the boundaries of supergranules. Last but not least, (iii) various periods of oscillatory phenomena were identified in this facular data set, including a longer periodic range consistent with the quasi-biennial oscillations and shorter ones with periods of 4–12 days. Our findings are supported by the visualization of a simple heuristic thought experiment and more complex magnetohydrodynami simulations, strengthening the proposed interpretation of the three observed solar phenomena reported.

Scenario of the faculae distribution where a more realistic signal-to-noise ratio is applied. The model recreates all the observed features such as the parallel stripe lines and the crisscross patterns.

HMI Science Nuggets features: Rossby waves and the organization of photospheric magnetic fields

whawkins — Fri, 06 Oct 2023 19:06:26 +0000

HMI Science Nuggets features: Rossby waves and the organization of photospheric magnetic fields whawkins Fri, 10/06/2023 - 13:06

Author:

whawkins

Oct 6, 2023

Comparison of the butterfly diagram based on the Shannon Entropy (top) and the butterfly diagram based on the Magnetic Field Strength (bottom), showing the evolution of level of longitudinal organization of the photospheric magnetic fields as a function of latitude and time.

HMI Science Nuggets: In recent years an increasing amount of evidence points to the crucial role of magnetically-modified Rossby waves in several solar phenomena. Rossby waves are large scale vortical oscillations that arise in rotating fluid/plasma systems as a result of the Coriolis force, being one of the most fundamental physical mechanisms in the understanding of Earths’s climate and weather. In Earth’s atmosphere one of their effects is to organize the spatial temporal formation of clouds and consequently rainfall and storms. Rays (paths) along which Rossby waves propagate are the origin of atmospheric stormtracks and teleconnection patterns.

Deciphering Pre-solar-storm Features Of September-2017 Storm From Global And Local Dynamics

whawkins — Tue, 01 Aug 2023 18:47:28 +0000

Deciphering Pre-solar-storm Features Of September-2017 Storm From Global And Local Dynamics whawkins Tue, 08/01/2023 - 12:47

Author:

whawkins

Aug 1, 2023

Evolution of the magnetic fields (left) and helicity density (right) for AR 12673.

We investigate how global toroid patterns and local magnetic field topology of solar active region AR12673 together can hindcast occurrence of the biggest X-flare of cycle 24. Magnetic toroid patterns (narrow latitude-belts warped in longitude, in which active regions are tightly stringed) derived from surface distribution of active regions, prior/during AR12673 emergence, reveal that the portions of South-toroid containing AR12673 was not tipped-away from its North-toroid counterpart at that longitude, unlike the 2003 Halloween storms scenario. During minimum-phase there were too few emergences to determine multi-mode warped toroid patterns in longitude. A new emergence within AR12673 produced a complex/non-potential structure, which led to rapid build-up of helicity and winding that triggered the biggest X-flare of cycle 24. Such a minimum-phase storm can be forecast with only hours' lead-time. However, global patterns and local dynamics for a peak-phase storm, such as that from AR11263, behaved like 2003 Halloween storms, producing the second biggest X-flare of cycle 24. AR11263 was present at the longitude where the North and South toroids tipped-away from each other. Both toroids were warped in longitude due to higher wave numbers and were slowly evolving. While global toroid patterns indicate that pre-storm features can be forecast with a lead-time of a few Carrington Rotations, observed complex/non-potential field structure development hours before the storm can improve the forecast further. We infer that minimum-phase storms can be forecast only hours ahead, while flare-prone active regions in peak-phase can be anticipated at least a month ahead from global toroid patterns.

Mausumi Dikpati

Analysis Of Short-term Solar Activity Variability and Estimating Timings of Next Enhanced Bursts

Recent News

HAO research featured on AAS Nova

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Mother's Day Superstorms: Pre- and Post-storm Evolutionary Patterns of AR 13664/8

Recent News

A Magnetohydrodynamic Mechanism for the Formation of Solar Polar Vortices

Recent News

Spectra of solar shallow-water waves from bright point observations

Recent News

Evolution Of Amplitude And Longitude Phase Of Tachocline Rossby Waves Diffusing To The Photosphere

Recent News

Global and Local Dynamics of X-flare Producing Active Regions During Solar Cycle 25 Peak-Phase

Recent News

Exploring Spatial and Temporal Patterns in the Debrecen Solar Faculae Database

Recent News

HMI Science Nuggets features: Rossby waves and the organization of photospheric magnetic fields

Recent News

Deciphering Pre-solar-storm Features Of September-2017 Storm From Global And Local Dynamics

Recent News