publications | Shibaji Chakraborty

2023

GRL
Substorms and Solar Eclipses: A Mutual Information Based Study

S. E. Coyle, J. B. H. Baker, S. Chakraborty, and 5 more authors

Geophysical Research Letters, 2023

e2023GL106432 2023GL106432

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Abstract Solar eclipses present a rare glimpse into the impact of ionospheric electrodynamics on the magnetosphere independent of other well studied seasonal influences. Despite decades of study, we still do not have a complete description of the conditions for geomagnetic substorm onset. We present herein a mutual information based study of previously published substorm onsets and the past two decades of eclipses which indicates the likelihood of co-occurrence is greater than random chance. A plausible interpretation for this relation suggests that the abrupt fluctuations in ionospheric conductivity during an eclipse may influence the magnetospheric preconditions of substorm initiation. While the mechanism remains unclear, this study presents strong evidence of a link between substorm onset and solar eclipses.
@article{Coyle2023GL106432, author = {Coyle, S. E. and Baker, J. B. H. and Chakraborty, S. and Hartinger, M. D. and Freeman, M. P. and Clauer, C. R. and Xu, Z. and Weimer, D. R.}, title = {Substorms and Solar Eclipses: A Mutual Information Based Study}, journal = {Geophysical Research Letters}, volume = {50}, number = {24}, pages = {e2023GL106432}, keywords = {solar eclipse, substorm, mutual information, conductivity}, doi = {https://doi.org/10.1029/2023GL106432}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2023GL106432}, note = {e2023GL106432 2023GL106432}, year = {2023}, dimensions = {true}, }

ApJS

A Community Dataset for Comparing Automated Coronal Hole Detection Schemes

Martin A Reiss, Karin Muglach, Emily Mason, and 8 more authors

Astrophysical Journal Supplement, 2023

@article{reiss2023community,
  title = {A Community Dataset for Comparing Automated Coronal Hole Detection Schemes},
  author = {Reiss, Martin A and Muglach, Karin and Mason, Emily and Davies, Emma E and Chakraborty, Shibaji and Delouille, Veronique and Downs, Cooper and Garton, Tadhg M and Grajeda, Jeremy A and Hamada, Amr and others},
  journal = {Astrophysical Journal Supplement},
  year = {2023},
  publisher = {American Astronomical Society/IOP Publishing},
  dimensions = {true},
}

Transmission Line Modelling of Geomagnetic Induction in the Ocean/Earth Conductivity Structure

D. Boteler, S. Chakraborty, X. Shi, and 2 more authors

International Journal of Geosciences, 2023

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Abstract Solar eclipses present a rare glimpse into the impact of ionospheric electrodynamics on the magnetosphere independent of other well studied seasonal influences. Despite decades of study, we still do not have a complete description of the conditions for geomagnetic substorm onset. We present herein a mutual information based study of previously published substorm onsets and the past two decades of eclipses which indicates the likelihood of co-occurrence is greater than random chance. A plausible interpretation for this relation suggests that the abrupt fluctuations in ionospheric conductivity during an eclipse may influence the magnetospheric preconditions of substorm initiation. While the mechanism remains unclear, this study presents strong evidence of a link between substorm onset and solar eclipses.
@article{Botelerijg.2023.148041, author = {Boteler, D. and Chakraborty, S. and Shi, X. and Hartinger, M. and Wang, X.}, title = {Transmission Line Modelling of Geomagnetic Induction in the Ocean/Earth Conductivity Structure}, journal = {International Journal of Geosciences}, volume = {14}, pages = {767-791}, keywords = {Geomagnetic Induction, Generalised Thin Sheet, Transmission Line Modelling, Coast Potentials, Submarine Cables}, doi = {https://doi.org/10.4236/ijg.2023.148041}, year = {2023}, dimensions = {true}, }
The Growth of Ring Current/SYM-H Under Northward IMF Bz Conditions Present During the 21–22 January 2005 Geomagnetic Storm

Diptiranjan Rout, S. Patra, S. Kumar, and 6 more authors

Space Weather, 2023

e2023SW003489 2023SW003489

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Abstract The total energy transfer from the solar wind to the magnetosphere is governed by the reconnection rate at the magnetosphere edges as the Z-component of interplanetary magnetic field (IMF Bz) turns southward. The geomagnetic storm on 21–22 January 2005 is considered to be anomalous as the SYM-H index that signifies the strength of ring current, decreases and had a sustained trough value of −101 nT lasting more than 6 hr under northward IMF Bz conditions. In this work, the standard WINDMI model is utilized to estimate the growth and decay of magnetospheric currents by using several solar wind-magnetosphere coupling functions. However, it is found that the WINDMI model driven by any of these coupling functions is not fully able to explain the decrease of SYM-H under northward IMF Bz. A dense plasma sheet along with signatures of a highly stretched magnetosphere was observed during this storm. The SYM-H variations during the entire duration of the storm were only reproduced after modifying the WINDMI model to account for the effects of the dense plasma sheet. The limitations of directly driven models relying purely on the solar wind parameters and not accounting for the state of the magnetosphere are highlighted by this work.
@article{Rout2023SW003489, author = {Rout, Diptiranjan and Patra, S. and Kumar, S. and Chakrabarty, D. and Reeves, G. D. and Stolle, C. and Pandey, K. and Chakraborty, S. and Spencer, E. A.}, title = {The Growth of Ring Current/SYM-H Under Northward IMF Bz Conditions Present During the 21–22 January 2005 Geomagnetic Storm}, journal = {Space Weather}, volume = {21}, number = {10}, pages = {e2023SW003489}, keywords = {ring current, space weather, northward IMF Bz, WINDMI model, solar wind-magnetosphere-ionosphere coupling}, doi = {https://doi.org/10.1029/2023SW003489}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2023SW003489}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2023SW003489}, note = {e2023SW003489 2023SW003489}, year = {2023}, dimensions = {true}, }
Transient Response of Polar-Cusp Ionosphere to an Interplanetary Shock

Jianjun Liu, Shibaji Chakraborty, Xiangcai Chen, and 11 more authors

Journal of Geophysical Research: Space Physics, 2023

e2022JA030565 2022JA030565

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Abstract Interplanetary (IP) shock-driven sudden compression of the Earth’s magnetosphere produces electromagnetic disturbances in the polar ionosphere. Several studies have examined the effects of IP shock on magnetosphere-ionosphere coupling systems using all-sky cameras and radars. In this study, we examine responses and drivers of the polar ionosphere following an IP shock compression on 16 June 2012. We observe the vertical drift and concurrent horizontal motion of the plasma. Observations from digisonde located at Antarctic Zhongshan station (ZHO) showed an ionospheric thick E region ionization and associated vertical downward plasma motion at F region. In addition, horizontal ionospheric convection reversals were observed on the Super Dual Auroral Radar Network ZHO and McMurdo radar observations. Findings suggest that the transient convective reversal breaks the original shear equilibrium, it is expected that the IP shock-induced electric field triggers an enhanced velocity shear mapping to the E region. The horizontal motion of the plasma was attributed to only the dusk-to-dawn electric field that existed during the preliminary phase of sudden impulse. We also found that ionospheric convection reversals were driven by a downward field-aligned current. The results of these observations reveal, for the first time, the immediate and direct cusp ionosphere response to the IP shock, which is critical for understanding the global response of the magnetosphere following an abrupt change in Interplanetory Magnetic Field (IMF) and solar wind conditions.
@article{Liu2022JA030565, author = {Liu, Jianjun and Chakraborty, Shibaji and Chen, Xiangcai and Wang, Zhiwei and He, Fang and Hu, Zejun and Liu, Erxiao and Bat-Erdene, Amarjargal and Han, Desheng and Ruohoniemi, J. Michael and Baker, Joseph B. H. and Yang, Huigen and Zong, Qiugang and Hu, Hongqiao}, title = {Transient Response of Polar-Cusp Ionosphere to an Interplanetary Shock}, journal = {Journal of Geophysical Research: Space Physics}, volume = {128}, number = {3}, pages = {e2022JA030565}, keywords = {space weather, IP shock, SSC, SuperDARN, reverse convection, vertical drift}, doi = {https://doi.org/10.1029/2022JA030565}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2022JA030565}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022JA030565}, note = {e2022JA030565 2022JA030565}, year = {2023}, dimensions = {true}, }
Crowdsourced Doppler measurements of time standard stations demonstrating ionospheric variability

K. Collins, J. Gibbons, N. Frissell, and 15 more authors

Earth System Science Data, 2023

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Ionospheric variability produces measurable effects in Doppler shift of HF (high-frequency, 3–30 MHz) skywave signals. These effects are straightforward to measure with low-cost equipment and are conducive to citizen science campaigns. The low-cost Personal Space Weather Station (PSWS) network is a modular network of community-maintained, open-source receivers, which measure Doppler shift in the precise carrier signals of time standard stations. The primary goal of this paper is to explain the types of measurements this instrument can make and some of its use cases, demonstrating its role as the building block for a large-scale ionospheric and HF propagation measurement network which complements existing professional networks. Here, data from the PSWS network are presented for a period of time spanning late 2019 to early 2022. Software tools for the visualization and analysis of this living dataset are also discussed and provided. These tools are robust to data interruptions and to the addition, removal or modification of stations, allowing both short- and long-term visualization at higher density and faster cadence than other methods. These data may be used to supplement observations made with other geospace instruments in event-based analyses, e.g., traveling ionospheric disturbances and solar flares, and to assess the accuracy of the bottomside estimates of ionospheric models by comparing the oblique paths obtained by ionospheric ray tracers with those obtained by these receivers. The data are archived at https://doi.org/10.5281/zenodo.6622111 (Collins, 2022).
@article{essd-15-1403-2023, author = {Collins, K. and Gibbons, J. and Frissell, N. and Montare, A. and Kazdan, D. and Kalmbach, D. and Swartz, D. and Benedict, R. and Romanek, V. and Boedicker, R. and Liles, W. and Engelke, W. and McGaw, D. G. and Farmer, J. and Mikitin, G. and Hobart, J. and Kavanagh, G. and Chakraborty, S.}, title = {Crowdsourced Doppler measurements of time standard stations demonstrating ionospheric variability}, journal = {Earth System Science Data}, volume = {15}, year = {2023}, number = {3}, pages = {1403--1418}, url = {https://essd.copernicus.org/articles/15/1403/2023/}, doi = {10.5194/essd-15-1403-2023}, dimensions = {true}, }

2022

Modeling geomagnetic induction in submarine cables

Shibaji Chakraborty, David H. Boteler, Xueling Shi, and 5 more authors

Frontiers in Physics, 2022

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Submarine cables have become a vital component of modern infrastructure, but past submarine cable natural hazard studies have mostly focused on potential cable damage from landslides and tsunamis. A handful of studies examine the possibility of space weather effects in submarine cables. The main purpose of this study is to develop a computational model, using Python, of geomagnetic induction on submarine cables. The model is used to estimate the induced voltage in the submarine cables in response to geomagnetic disturbances. It also utilizes newly acquired knowledge from magnetotelluric studies and associated investigations of geomagnetically induced currents in power systems. We describe the Python-based software, its working principle, inputs/outputs based on synthetic geomagnetic field data, and compare its operational capabilities against analytical solutions. We present the results for different model inputs, and find: 1) the seawater layer acts as a shield in the induction process: the greater the ocean depth, the smaller the seafloor geoelectric field; and 2) the model is sensitive to the Ocean-Earth layered conductivity structure.
@article{scubas2022, author = {Chakraborty, Shibaji and Boteler, David H. and Shi, Xueling and Murphy, Benjamin S. and Hartinger, Michael D. and Wang, Xuan and Lucas, Greg and Baker, Joseph B. H.}, title = {Modeling geomagnetic induction in submarine cables}, journal = {Frontiers in Physics}, volume = {10}, year = {2022}, url = {https://www.frontiersin.org/articles/10.3389/fphy.2022.1022475}, doi = {10.3389/fphy.2022.1022475}, issn = {2296-424X}, dimensions = {true}, }
Driving Influences of the Doppler Flash Observed by SuperDARN HF Radars in Response to Solar Flares

S. Chakraborty, L. Qian, J. B. H. Baker, and 3 more authors

Journal of Geophysical Research: Space Physics, 2022

e2022JA030342 2022JA030342

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Abstract Sudden enhancement in high-frequency absorption is a well-known impact of solar flare-driven Short-Wave Fadeout (SWF). Less understood, is a perturbation of the radio wave frequency as it traverses the ionosphere in the early stages of SWF, also known as the Doppler flash. Investigations have suggested two possible sources that might contribute to it’s manifestation: first, enhancements of plasma density in the D-and lower E-regions; second, the lowering of the F-region reflection point. Our recent work investigated a solar flare event using first principles modeling and Super Dual Auroral Radar Network (SuperDARN) HF radar observations and found that change in the F-region refractive index is the primary driver of the Doppler flash. This study analyzes multiple solar flare events observed across different SuperDARN HF radars to determine how flare characteristics, properties of the traveling radio wave, and geophysical conditions impact the Doppler flash. In addition, we use incoherent scatter radar data and first-principles modeling to investigate physical mechanisms that drive the lowering of the F-region reflection points. We found, (a) on average, the change in E- and F-region refractive index is the primary driver of the Doppler flash, (b) solar zenith angle, ray’s elevation angle, operating frequency, and location of the solar flare on the solar disk can alter the ionospheric regions of maximum contribution to the Doppler flash, (c) increased ionospheric Hall and Pedersen conductance causes a reduction of the daytime eastward electric field, and consequently reduces the vertical ion-drift in the lower and middle latitude ionosphere, which results in lowering of the F-region ray reflection point.
@article{Chakraborty2022JA030342, author = {Chakraborty, S. and Qian, L. and Baker, J. B. H. and Ruohoniemi, J. M. and Kuyeng, K. and Mclnerney, J. M.}, title = {Driving Influences of the Doppler Flash Observed by SuperDARN HF Radars in Response to Solar Flares}, journal = {Journal of Geophysical Research: Space Physics}, volume = {127}, number = {6}, pages = {e2022JA030342}, keywords = {space weather, shortwave fadeout, Doppler flash, solar flare, magnetic crochet, SuperDARN}, doi = {https://doi.org/10.1029/2022JA030342}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022JA030342}, note = {e2022JA030342 2022JA030342}, year = {2022}, dimensions = {true}, }
AnGeo
Multi-instrument observations of polar cap patches and traveling ionospheric disturbances generated by solar wind Alfvén waves coupling to the dayside magnetosphere

Paul Prikryl, Robert G. Gillies, David R. Themens, and 3 more authors

Annales Geophysicae, Nov 2022

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During minor to moderate geomagnetic storms, caused by corotating interaction regions (CIRs) at the leading edge of high-speed streams (HSSs), solar wind Alfvén waves modulated the magnetic reconnection at the dayside magnetopause. The Resolute Bay Incoherent Scatter Radars (RISR-C and RISR-N), measuring plasma parameters in the cusp and polar cap, observed ionospheric signatures of flux transfer events (FTEs) that resulted in the formation of polar cap patches. The patches were observed as they moved over the RISR, and the Canadian High-Arctic Ionospheric Network (CHAIN) ionosondes and GPS receivers. The coupling process modulated the ionospheric convection and the intensity of ionospheric currents, including the auroral electrojets. The horizontal equivalent ionospheric currents (EICs) are estimated from ground-based magnetometer data using an inversion technique. Pulses of ionospheric currents that are a source of Joule heating in the lower thermosphere launched atmospheric gravity waves, causing traveling ionospheric disturbances (TIDs) that propagated equatorward. The TIDs were observed in the SuperDual Auroral Radar Network (SuperDARN) high-frequency (HF) radar ground scatter and the detrended total electron content (TEC) measured by globally distributed Global Navigation Satellite System (GNSS) receivers.
@article{2022AnGeo.40.619P, author = {{Prikryl}, Paul and {Gillies}, Robert G. and {Themens}, David R. and {Weygand}, James M. and {Thomas}, Evan G. and {Chakraborty}, Shibaji}, title = {{Multi-instrument observations of polar cap patches and traveling ionospheric disturbances generated by solar wind Alfv{\'e}n waves coupling to the dayside magnetosphere}}, journal = {Annales Geophysicae}, year = {2022}, month = nov, volume = {40}, number = {6}, pages = {619-639}, doi = {10.5194/angeo-40-619-2022}, adsurl = {https://ui.adsabs.harvard.edu/abs/2022AnGeo..40..619P}, adsnote = {Provided by the SAO/NASA Astrophysics Data System}, dimensions = {true}, }
pyDARN: A Python software for visualizing SuperDARN radar data

Shi X, Schmidt M, Martin CJ, and 10 more authors

Front. Astron. Space Sci., Nov 2022

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The Super Dual Auroral Radar Network (SuperDARN) is an international network of high frequency coherent scatter radars that are used for monitoring the electrodynamics of the Earth’s upper atmosphere at middle, high, and polar latitudes in both hemispheres. pyDARN is an open-source Python-based library developed specifically for visualizing SuperDARN radar data products. It provides various plotting functions of different types of SuperDARN data, including time series plot, range-time parameter plot, fields of view, full scan, and global convection map plots. In this paper, we review the different types of SuperDARN data products, pyDARN’s development history and goals, the current implementation of pyDARN, and various plotting and analysis functionalities. We also discuss applications of pyDARN, how it can be combined with other existing Python software for scientific analysis, challenges for pyDARN development and future plans. Examples showing how to read, visualize, and interpret different SuperDARN data products using pyDARN are provided as a Jupyter notebook.
@article{pydarn, author = {X, Shi and M, Schmidt and CJ, Martin and DD, Billett and E, Bland and FH, Tholley and NA, Frissell and K, Khanal and S, Coyle and S, Chakraborty and M, Detwiller and B, Kunduri and K, McWilliams}, title = {pyDARN: A Python software for visualizing SuperDARN radar data}, journal = {Front. Astron. Space Sci.}, volume = {9}, year = {2022}, number = {1022690}, doi = {10.3389/fspas.2022.1022690}, dimensions = {true}, }
Data-based optimization of a simple shortwave fadeout absorption model

R.A.D. Fiori, S. Chakraborty, and L. Nikitina

Journal of Atmospheric and Solar-Terrestrial Physics, Nov 2022

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Electron density enhancement caused by electromagnetic radiation emitted during a solar X-ray flare has the potential to increase high frequency (HF; 3–30 MHz) absorption in the dayside D-region ionosphere, impacting shortwave radio signals by reducing the signal strength, a phenomenon commonly referred to as shortwave fadeout. Data-based optimization of a simple absorption model is performed incorporating solar X-ray flux data and 30 MHz riometer data from stations distributed across Canada. In a single event study the data-based optimization model is shown to overestimate absorption by 1% for the duration of an X2.1 solar X-ray flare. This corrects an underestimation by the NOAA D-region Absorption Prediction (D-RAP) model. In a statistical study, based on 87 events, data-based optimization performed on an event-by-event basis showed excellent overall agreement between measured and modelled data: the Pearson correlation coefficient was R = 0.88, and the slope of the best-fit line to the data was m = 0.91. A generalized model was developed using data from all 87 events collectively. Although good agreement was found between the measured and modelled data sets, correlation and slope were slightly reduced to R = 0.75 and m = 0.80. Model accuracy is characterized by prediction efficiency (PE) which peaked at PE = 0.78 for the event-by-event evaluation and PE = 0.48 for the collective data set. The results of this study highlight the advantages of data-based optimization in modelling absorption due to shortwave fadeout.
@article{FIORI2022105843, title = {Data-based optimization of a simple shortwave fadeout absorption model}, journal = {Journal of Atmospheric and Solar-Terrestrial Physics}, volume = {230}, pages = {105843}, year = {2022}, issn = {1364-6826}, doi = {https://doi.org/10.1016/j.jastp.2022.105843}, author = {Fiori, R.A.D. and Chakraborty, S. and Nikitina, L.}, keywords = {Shortwave fadeout, Ionospheric HF absorption, HF absorption Model, HF radiowave Propagation}, dimensions = {true}, }

2021

The Role of Flare-Driven Ionospheric Electron Density Changes on the Doppler Flash Observed by SuperDARN HF Radars

S. Chakraborty, L. Qian, J. M. Ruohoniemi, and 3 more authors

Journal of Geophysical Research: Space Physics, Nov 2021

e2021JA029300 2021JA029300

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Abstract Trans-ionospheric high frequency (HF: 3–30 MHz) signals experience strong attenuation following a solar flare-driven sudden ionospheric disturbance (SID). Solar flare-driven HF absorption, referred to as short-wave fadeout, is a well-known impact of SIDs, but the initial Doppler frequency shift phenomena, also known as “Doppler flash” in the traveling radio wave is not well understood. This study seeks to advance our understanding of the initial impacts of solar flare-driven SID using a physics-based whole atmosphere model for a specific solar flare event. First, we demonstrate that the Doppler flash phenomenon observed by Super Dual Auroral Radar Network (SuperDARN) radars can be successfully reproduced using first-principles based modeling. The output from the simulation is validated against SuperDARN line-of-sight Doppler velocity measurements. We then examine which region of the ionosphere, D, E, or F, makes the largest contribution to the Doppler flash. We also consider the relative contribution of change in refractive index through the ionospheric layers versus lowered reflection height. We find: (a) the model is able to reproduce radar observations with an root-median-squared-error and a mean percentage error (δ) of 3.72 m/s and 0.67%, respectively; (b) the F-region is the most significant contributor to the total Doppler flash (∼48%), 30% of which is contributed by the change in F-region’s refractive index, while the other ∼18% is due to change in ray reflection height. Our analysis shows lowering of the F-region’s ray reflection point is a secondary driver compared to the change in refractive index.
@article{Chakraborty2021JA029300, author = {Chakraborty, S. and Qian, L. and Ruohoniemi, J. M. and Baker, J. B. H. and Mclnerney, J. M. and Nishitani, N.}, title = {The Role of Flare-Driven Ionospheric Electron Density Changes on the Doppler Flash Observed by SuperDARN HF Radars}, journal = {Journal of Geophysical Research: Space Physics}, volume = {126}, number = {8}, pages = {e2021JA029300}, keywords = {solar flare effects, Doppler flash, sudden ionospheric disturbances, HF propagation}, doi = {https://doi.org/10.1029/2021JA029300}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021JA029300}, note = {e2021JA029300 2021JA029300}, year = {2021}, dimensions = {true}, }
A Modeling Framework for Estimating Ionospheric HF Absorption Produced by Solar Flares

S. Chakraborty, J. B. H. Baker, R. A. D. Fiori, and 2 more authors

Radio Science, Nov 2021

e2021RS007285 2021RS007285

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Abstract Over-the-Horizon communication is strongly dependent on the state of the ionosphere, which is susceptible to solar flares. Trans-ionospheric high frequency (HF, 3–30 MHz) signals can experience strong attenuation following a solar flare that lasts typically for an hour, commonly referred to as shortwave fadeout (SWF). In this study, we examine the role of dispersion relation and collision frequency formulations on the estimation of SWF in riometer observations using a new physics-based model framework. The new framework first uses modified solar irradiance models incorporating high-resolution solar flux data from the GOES satellite X-ray sensors as input to compute the enhanced ionization produced during a flare event. The framework then uses different dispersion relation and collision frequency formulations to estimate the enhanced HF absorption. The modeled HF absorption is compared with riometer data to determine which formulation best reproduces the observations. We find the Appleton-Hartree dispersion relation in combination with the averaged collision frequency profile reproduces riometer observations with an average skill score of 0.4, representing 40% better forecast ability than the existing D-region Absorption Prediction model. Our modeling results also indicate that electron temperature plays an important role in controlling HF absorption. We suggest that adoption of the Appleton-Hartree dispersion relation in combination with the averaged collision frequency be considered for improved forecasting of ionospheric absorption following solar flares.
@article{Chakraborty2021RS007285, author = {Chakraborty, S. and Baker, J. B. H. and Fiori, R. A. D. and Ruohoniemi, J. M. and Zawdie, K. A.}, title = {A Modeling Framework for Estimating Ionospheric HF Absorption Produced by Solar Flares}, journal = {Radio Science}, volume = {56}, number = {10}, pages = {e2021RS007285}, keywords = {shortwave fadeout, HF absorption, modeling, collision frequency, dispersion relations, electron temperature}, doi = {https://doi.org/10.1029/2021RS007285}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021RS007285}, note = {e2021RS007285 2021RS007285}, year = {2021}, dimensions = {true}, }
Ionospheric Sluggishness: A Characteristic Time-Lag of the Ionospheric Response to Solar Flares

S. Chakraborty, J. M. Ruohoniemi, J. B. H. Baker, and 3 more authors

Journal of Geophysical Research: Space Physics, Nov 2021

e2020JA028813 2020JA028813

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Abstract The term “sluggishness” was coined by E. V. Appleton in the 1950s to describe the time delay between peak irradiance at solar noon and the resulting peak in ionospheric electron density. Sluggishness can be understood as an inertial property of the ionosphere that manifests as a lag of the ionospheric response to a solar driver. As shown by Appleton, estimates of sluggishness can be used to study the chemistry of the lower ionosphere, of the D-region in particular. In this study, for the first time, we have examined ionospheric sluggishness in terms of the time delay between the peak irradiance during a solar flare and the resulting peak in ionospheric electron density using HF instruments. Estimates of the delay are obtained using HF observations from riometers and SuperDARN radars that are primarily sensitive to absorption in the D-region. Two new methods for measuring delay are introduced. Sluggishness is shown to be anti-correlated with peak solar X-ray flux and positively correlated with zenith angle and latitude. The choices of instrument, method, and reference solar waveband affect the sluggishness estimation. A simulation study was performed to estimate the effective recombination coefficient in the D-region. The coefficient was found to vary by orders of magnitude with peak flare intensity. We argue that the variation in effective recombination coefficient with peak flare intensity is highly sensitive to changes in the negative and positive ion chemistry of the D-region, which is sensitive to the incoming solar X-ray and EUV radiation.
@article{Chakraborty2020JA028813, author = {Chakraborty, S. and Ruohoniemi, J. M. and Baker, J. B. H. and Fiori, R. A. D. and Bailey, S. M. and Zawdie, K. A.}, title = {Ionospheric Sluggishness: A Characteristic Time-Lag of the Ionospheric Response to Solar Flares}, journal = {Journal of Geophysical Research: Space Physics}, volume = {126}, number = {4}, pages = {e2020JA028813}, keywords = {ion chemistry, ionosphere, photo-ionization, recombination coefficient, sluggishness, solar flare}, doi = {https://doi.org/10.1029/2020JA028813}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020JA028813}, note = {e2020JA028813 2020JA028813}, year = {2021}, dimensions = {true}, }
IEEE
Probabilistic Short-wave Fadeout Detection in SuperDARN Time Series Observations

Shibaji Chakraborty, Joseph B. H. Baker, and J. Michael Ruohoniemi

In 2021 IEEE International Conference on Wireless for Space and Extreme Environments (WiSEE), Nov 2021

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Short-wave fadeout (SWF) is one of the first space weather effects to occur in the ionosphere following a solar flare and leads to severe disruption of ionospheric HF systems. The disruption is produced by flare-enhanced energetic radiations that penetrate to the D-layer where they enhance ionization that leads to heavy absorption of high-frequency (HF, 3–30 MHz) radio signal over much of the dayside for an hour or more. In this paper, we describe two probabilistic anomaly detection schemes that have been used to detect SWF events produced by M and X class flares in Super Dual Auroral Radar Network (SuperDARN) observations. The two schemes are based on statistical Z-score and nonlinear energy operators. Performance of the detection schemes varies with flare intensity and parameters of the detection schemes. We find a correlation coefficient 0.73 between flare counts per month and SWF counts per month detected using the Z-score scheme.
@inproceedings{9613835, author = {Chakraborty, Shibaji and Baker, Joseph B. H. and Ruohoniemi, J. Michael}, booktitle = {2021 IEEE International Conference on Wireless for Space and Extreme Environments (WiSEE)}, title = {Probabilistic Short-wave Fadeout Detection in SuperDARN Time Series Observations}, year = {2021}, volume = {}, number = {}, pages = {43-48}, doi = {10.1109/WiSEE50203.2021.9613835}, dimensions = {true}, }

2020

Probabilistic prediction of geomagnetic storms and the Kp index

Chakraborty, Shibaji, and Morley, Steven Karl

J. Space Weather Space Clim., Nov 2020

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@article{refId0,
  author = {{Chakraborty, Shibaji} and {Morley, Steven Karl}},
  title = {Probabilistic prediction of geomagnetic storms and the Kp index},
  doi = {10.1051/swsc/2020037},
  journal = {J. Space Weather Space Clim.},
  year = {2020},
  volume = {10},
  pages = {36},
  dimensions = {true},
}

Conductance Model for Extreme Events: Impact of Auroral Conductance on Space Weather Forecasts

Agnit Mukhopadhyay, Daniel T. Welling, Michael W. Liemohn, and 3 more authors

Space Weather, Nov 2020

e2020SW002551 10.1029/2020SW002551

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Abstract Ionospheric conductance is a crucial factor in regulating the closure of magnetospheric field-aligned currents through the ionosphere as Hall and Pedersen currents. Despite its importance in predictive investigations of the magnetosphere-ionosphere coupling, the estimation of ionospheric conductance in the auroral region is precarious in most global first-principles-based models. This impreciseness in estimating the auroral conductance impedes both our understanding and predictive capabilities of the magnetosphere-ionosphere system during extreme space weather events. In this article, we address this concern, with the development of an advanced Conductance Model for Extreme Events (CMEE) that estimates the auroral conductance from field-aligned current values. CMEE has been developed using nonlinear regression over a year’s worth of 1-min resolution output from assimilative maps, specifically including times of extreme driving of the solar wind-magnetosphere-ionosphere system. The model also includes provisions to enhance the conductance in the aurora using additional adjustments to refine the auroral oval. CMEE has been incorporated within the Ridley Ionosphere Model (RIM) of the Space Weather Modeling Framework (SWMF) for usage in space weather simulations. This paper compares performance of CMEE against the existing conductance model in RIM, through a validation process for six space weather events. The performance analysis indicates overall improvement in the ionospheric feedback to ground-based space weather forecasts. Specifically, the model is able to improve the prediction of ionospheric currents, which impact the simulated dB/dt and ΔB, resulting in substantial improvements in dB/dt predictive skill.
@article{Mukhopadhyay2020SW002551, author = {Mukhopadhyay, Agnit and Welling, Daniel T. and Liemohn, Michael W. and Ridley, Aaron J. and Chakraborty, Shibaji and Anderson, Brian J.}, title = {Conductance Model for Extreme Events: Impact of Auroral Conductance on Space Weather Forecasts}, journal = {Space Weather}, volume = {18}, number = {11}, pages = {e2020SW002551}, keywords = {ionospheric conductance}, doi = {https://doi.org/10.1029/2020SW002551}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020SW002551}, note = {e2020SW002551 10.1029/2020SW002551}, year = {2020}, dimensions = {true}, }

2019

A Study of SuperDARN Response to Co-occurring Space Weather Phenomena

S. Chakraborty, J. B. H. Baker, J. M. Ruohoniemi, and 3 more authors

Space Weather, Nov 2019

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Abstract The Sun was remarkably active during the first week of September 2017 producing numerous solar flares, solar radiation storms, and coronal mass ejections. This activity caused disruption to terrestrial high-frequency (HF, 3–30 MHz) radio communication channels including observations with the Super Dual Auroral Radar Network (SuperDARN) HF radars. In this paper, we analyze the response of SuperDARN groundscatter observations and decreases in background sky noise level in response to multiple solar flares occurring in quick succession and co-occurring with solar energetic protons and auroral activity. We estimate the attenuation in HF signal strength using an approach similar to riometry and find that the radars exhibit a nonlinear response to compound solar flare events. Additionally, we find that the three different space weather drivers have varying degrees of influence on the HF signal properties at different latitudes. Our study demonstrates that in addition to monitoring high-latitude convection, SuperDARN observations can be used to study the spatiotemporal evolution of disruption to HF communication during extreme space weather conditions.
@article{Chakraborty2019SW002179, author = {Chakraborty, S. and Baker, J. B. H. and Ruohoniemi, J. M. and Kunduri, B. and Nishitani, N. and Shepherd, S. G.}, title = {A Study of SuperDARN Response to Co-occurring Space Weather Phenomena}, journal = {Space Weather}, volume = {17}, number = {9}, pages = {1351-1363}, keywords = {space weather, radio wave, absorption, shortwave fadeout, polar cap absorption, auroral absorption}, doi = {https://doi.org/10.1029/2019SW002179}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019SW002179}, year = {2019}, dimensions = {true}, }

2018

Characterization of Short-Wave Fadeout Seen in Daytime SuperDARN Ground Scatter Observations

S. Chakraborty, J. M. Ruohoniemi, J. B. H. Baker, and 1 more author

Radio Science, Nov 2018

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Abstract Short-wave fadeout (SWF) is a well-known radio wave anomaly which follows Earth-directed solar flares and leads to severe disruption of transionospheric high-frequency systems. The disruption is produced by flare-enhanced soft and hard X-rays that penetrate to the D layer where they dramatically enhance ionization leading to heavy high-frequency absorption over much of the dayside for an hour or more. In this paper, we describe how Super Dual Auroral Radar Network (SuperDARN) observations can be exploited to analyze SWF events. Superposed epoch analysis of multiple signatures reveals the typical characteristics of SWF. The number of SuperDARN ground scatter echoes drops suddenly (≈100 s) and sharply after a solar flare, reaching a maximum depth of suppression within a few tens of minutes, and then recovering to pre-SWF conditions over half an hour or so. The depth of echo suppression depends on the solar zenith angle, radio wave frequency, and intensity of the flare. Furthermore, ground scatter echoes typically exhibit a sudden phase change leading to a dramatic increase in apparent Doppler velocity (the so-called “Doppler flash”), which statistically precedes the dropout in ground scatter echoes. We report here on the characterization of SWF effects in SuperDARN ground scatter observations produced by several X class solar flares. We also describe the functional dependence of peak Doppler flash on solar zenith angle, frequency, and peak intensity of solar flux.
@article{Chakraborty2017RS006488, author = {Chakraborty, S. and Ruohoniemi, J. M. and Baker, J. B. H. and Nishitani, N.}, title = {Characterization of Short-Wave Fadeout Seen in Daytime SuperDARN Ground Scatter Observations}, journal = {Radio Science}, volume = {53}, number = {4}, pages = {472-484}, keywords = {short-wave fadeout, characterization, SuperDARN, SWF, ground scatter}, doi = {https://doi.org/10.1002/2017RS006488}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017RS006488}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017RS006488}, year = {2018}, dimensions = {true}, }
Examining the Potential of the Super Dual Auroral Radar Network for Monitoring the Space Weather Impact of Solar X-Ray Flares

R. A. D. Fiori, A. V. Koustov, S. Chakraborty, and 4 more authors

Space Weather, Nov 2018

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Abstract Increased electron density in the ionosphere due to photoionization by radiation emitted during a solar X-ray flare impacts high-frequency (HF) radio wave propagation. Shortwave fadeout (SWF) due to the enhanced D region absorption that results is characterized by the level of cosmic radio noise attenuation derived from riometer measurements. SWF impacts HF radio propagation and has been identified in the Super Dual Auroral Radar Network (SuperDARN) data. An X2.1 solar X-ray flare that erupted on 11 March 2015 is examined to determine its effects on HF radio propagation. Riometer data indicate a sharp enhancement in absorption, which falls off with increasing solar zenith angle. SuperDARN radars observed a suppression of both ground scatter and ionospheric echoes. Ground scatter data indicated a rapid weakening of signal from far to near ranges followed by a 20-min interval of complete signal loss. Recovery lasted 30 min and proceeded from near to far ranges. Prior to the complete signal loss, an apparent sharp velocity impulse (Doppler flash) lasting 1–2 min was observed in the ground scatter data. The peak of this flash preceded the onset of enhanced absorption. The onset of signal loss by SuperDARN preceded the onset of enhanced absorption observed by riometers. Both data sets observed a positive correlation between increasing delay in onset and increasing solar zenith angle with onset progressing at an average rate of 16.7°/min (0.060 min/°). Agreement between riometer and SuperDARN indicates the possibility of using a joint data set for improved monitoring of the space weather impact of solar X-ray flares.
@article{Fiori2018SW001905, author = {Fiori, R. A. D. and Koustov, A. V. and Chakraborty, S. and Ruohoniemi, J. M. and Danskin, D. W. and Boteler, D. H. and Shepherd, S. G.}, title = {Examining the Potential of the Super Dual Auroral Radar Network for Monitoring the Space Weather Impact of Solar X-Ray Flares}, journal = {Space Weather}, volume = {16}, number = {9}, pages = {1348-1362}, keywords = {D region absorption, riometer, SuperDARN, solar X-ray flare, space weather}, doi = {https://doi.org/10.1029/2018SW001905}, eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2018SW001905}, year = {2018}, dimensions = {true}, }