A. Chulaki’s research while affiliated with Catholic University of America and other places

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Publications (40)


Temporal span of the individual models within the Arrival Time Scoreboard. Each dot represents an individual prediction and is colored according to the unsigned error in the arrival time. Predictions without a corresponding observed impact are shown in black.
Scatter plot of the error in arrival time over time. Each dot is colored according to the model used for that prediction.
Heat map timeline of the errors in arrival time for all predictions. The top panel shows the signed error and the bottom panel shows the absolute (unsigned) error. The lines show a rolling mean (blue) or median (cyan) over ±6 months.
Scatter timeline of the number of predictions for each individual observed Coronal mass ejection. Each point is colored by the unsigned arrival time error.
Scatter of arrival time error versus transit time for each coronal mass ejection, colored by the number of predictions for that event. The left panel shows the mean error and the right the mean absolute error over all predictions. In the left panel the dashed horizontal line indicates zero error.

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Updating Measures of CME Arrival Time Errors
  • Article
  • Full-text available

July 2024

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76 Reads

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4 Citations

C. Kay

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P. Riley

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[...]

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A. Chulaki

Coronal mass ejections (CMEs) drive space weather effects at Earth and the heliosphere. Predicting their arrival is a major part of space weather forecasting. In 2013, the Community Coordinated Modeling Center started collecting predictions from the community, developing an Arrival Time Scoreboard (ATSB). Riley et al. (2018, https://doi.org/10.1029/2018sw001962) analyzed the first 5 years of the ATSB, finding a bias of a few hours and uncertainty of order 15 hr. These metrics have been routinely quoted since 2018, but have not been updated despite continued predictions. We revise analysis of the ATSB using a sample 3.5 times the size of that in the original study. We find generally the same overall metrics, a bias of −2.5 hr, mean absolute error of 13.2 hr, and standard deviation of 17.4 hr, with only a slight improvement comparing between the previously‐used and new sets. The most well‐established, frequently‐submitted model results tend to outperform those from seldomly‐contributed models. These “best” models show a slight improvement over the 11 year span, with more scatter between the models during early times and a convergence toward the same error metrics in recent years. We find little evidence of any correlations between the arrival time errors and any other properties. The one noticeable exception is a tendency for late predictions for short transit times and vice versa. We propose that any model‐driven systematic errors may be washed out by the uncertainties in CME reconstructions in characterization of the background solar wind, and suggest that improving these may be the key to better predictions.

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A Model of an Integrated Research and Education Program in Space Weather at a Community College

January 2020

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135 Reads

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3 Citations

Community Colleges provide a great opportunity to diversify the space sciences or other science, technology, engineering, and math (STEM) !elds due to their large population of underrepresented students. However, since the primary mission of community colleges is teaching, there is a challenge to support undergraduate research training and promote undergraduate research opportunities. Undergraduate research experiences are one of the leading high!impact practices (HIPs) to encourage students to pursue STEM majors, graduate degrees, and careers. Space weather provides the opportunity to engage undergraduate students in real!world research due to the accessibility of space mission data sets within open access data repositories. Space weather's impact on Earth's geospace environment, life, and society also provides a compelling real!world hook to engage students in activities that have a number of impacts including (1) long!term integration of space weather into the undergraduate curricula; (2) experience in analyzing large geospace data sets, which increases students' computational, critical thinking, and analytical skills, useful for any career; and (3) increase in students' interest in and motivation to study STEM, as well as preparing them for choosing a career path in space science and related !elds. The model presented below has the potential to increase the retention, graduation, and transfer rate of community college students to four!year STEM programs, as well as increase representation and inclusion in space sciences and other related STEM !elds.


Data Constrained Coronal Mass Ejections in A Global Magnetohydrodynamics Model

May 2016

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1 Read

We present a first-principles-based coronal mass ejection (CME) model suitable for both scientific and operational purposes by combining a global magnetohydrodynamics (MHD) solar wind model with a flux rope-driven CME model. Realistic CME events are simulated self-consistently with high fidelity and forecasting capability by constraining initial flux rope parameters with observational data from GONG, SOHO/LASCO, and STEREO/COR. We automate this process so that minimum manual intervention is required in specifying the CME initial state. With the newly developed data-driven Eruptive Event Generator Gibson-Low (EEGGL), we present a method to derive Gibson-Low (GL) flux rope parameters through a handful of observational quantities so that the modeled CMEs can propagate with the desired CME speeds near the Sun. A test result with CMEs launched with different Carrington rotation magnetograms are shown. Our study shows a promising result for using the first-principles-based MHD global model as a forecasting tool, which is capable of predicting the CME direction of propagation, arrival time, and ICME magnetic field at 1 AU (see companion paper by Jin et al. 2016b).


Data Constrained Coronal Mass Ejections in A Global Magnetohydrodynamics Model

May 2016

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208 Reads

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121 Citations

The Astrophysical Journal

We present a first-principles-based coronal mass ejection (CME) model suitable for both scientific and operational purposes by combining a global magnetohydrodynamics (MHD) solar wind model with a flux rope-driven CME model. Realistic CME events are simulated self-consistently with high fidelity and forecasting capability by constraining initial flux rope parameters with observational data from GONG, SOHO/LASCO, and STEREO/COR. We automate this process so that minimum manual intervention is required in specifying the CME initial state. With the newly developed data-driven Eruptive Event Generator Gibson-Low (EEGGL), we present a method to derive Gibson-Low (GL) flux rope parameters through a handful of observational quantities so that the modeled CMEs can propagate with the desired CME speeds near the Sun. A test result with CMEs launched with different Carrington rotation magnetograms are shown. Our study shows a promising result for using the first-principles-based MHD global model as a forecasting tool, which is capable of predicting the CME direction of propagation, arrival time, and ICME magnetic field at 1 AU (see companion paper by Jin et al. 2016b).


Transitioning EEGGL to the CCMC

-The new EEGGL tool recently developed at the CCMC in collaboration with the University of Michigan, provides a capability to simulate the CME as well as its magnetic field evolution at 1 AU -Based on the magnetogram and evaluation of the CME initial location and speed, the user may choose the active region from which the CME originates and then the EEGGL tools provides the parameters of the Gibson-Low magnetic configuration to parameterize the CME. -The recommended parameters may be used then to drive the CME propagation from the low solar corona to 1 AU using the global code for simulating the solar corona and inner heliosphere. -At the CCMC The Community Coordinated Modeling Center (CCMC) provides the capability for CME runs-on-request, to the heliophysics community. -EEGGL is a new animal in the CCMC Zoo, which is well integrated with the other animals (Donki, STEREOCat).



New Publicly Available EEGGL Tool for Simulating Coronal Mass Ejections

December 2015

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111 Reads

We present and demonstrate a new tool, EEGGL (Eruptive Event Generator using Gibson-Low configuration) for simulating CMEs (Coronal Mass Ejections). CMEs are among the most significant space weather events, producing the radiation hazards (via the diffuse shock acceleration of the Solar Energetic Particles – SEPs), the interplanetary shock waves as well as the geomagnetic activity due to the drastic changes of the interplanetary magnetic field within the “magnetic clouds” ("flux ropes”). Some of this effects may be efficiently simulated using the “cone model”, which is employed in the real-time simulations of the ongoing CMEs at the NASA-Goddard Space Flight Center. The cone model provides a capability to predict the location, time, width and shape of the hydrodynamic perturbation in the upper solar corona (at ~0.1 AU), which can be used to drive the heliospheric simulation (with the ENLIL code, for example). At the same time the magnetic field orientation in this perturbation is uncertain within the cone model, which limits the capability of the geomagnetic activity forecast. The new EEGGL tool http://ccmc.gsfc.nasa.gov/analysis/EEGGL/recently developed at the Goddard Space Flight Center in collaboration with the University of Michigan provides a new capability for both evaluating the magnetic field configuration resulting from the CME and tracing the CME through the solar corona. In this way not only the capability to simulate the magnetic field evolution at 1 AU may be achieved, but also the more extensive comparison with the CME observations in the solar corona may be achieved. Based on the magnetogram and evaluation of the CME initial location and speed, the user may choose the active region from which the CME originates and then the EEGGL tools provides the parameters of the Gibson-Low magnetic configuration to parameterize the CME. The recommended parameters may be used then to drive the simulation of CME propagation from the low solar corona to 1 AU using the global code for simulating the solar corona and inner heliosphere. The Community Coordinated Modeling Center (CCMC) provides the capability for CME runs-on-request, to the heliophysics community.


Forecasting propagation and evolution of CMEs in an operational setting: What has been learned

October 2013

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33 Reads

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25 Citations

of the major types of solar eruption, coronal mass ejections (CMEs) not only impact space weather, but also can have significant societal consequences. CMEs cause intense geomagnetic storms and drive fast mode shocks that accelerate charged particles, potentially resulting in enhanced radiation levels both in ions and electrons. Human and technological assets in space can be endangered as a result. CMEs are also the major contributor to generating large amplitude Geomagnetically Induced Currents (GICs), which are a source of concern for power grid safety. Due to their space weather significance, forecasting the evolution and impacts of CMEs has become a much desired capability for space weather operations worldwide. Based on our operational experience at Space Weather Research Center at NASA Goddard Space Flight Center (http://swrc.gsfc.nasa.gov), we present here some of the insights gained about accurately predicting CME impacts, particularly in relation to space weather operations. These include: 1. The need to maximize information to get an accurate handle of three-dimensional (3-D) CME kinetic parameters and therefore improve CME forecast; 2. The potential use of CME simulation results for qualitative prediction of regions of space where solar energetic particles (SEPs) may be found; 3. The need to include all CMEs occurring within a ~24 h period for a better representation of the CME interactions; 4. Various other important parameters in forecasting CME evolution in interplanetary space, with special emphasis on the CME propagation direction. It is noted that a future direction for our CME forecasting is to employ the ensemble modeling approach.


Community Coordinated Modeling Center (CCMC): Providing Access to Space Weather Models and Research Support Tools

December 2011

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52 Reads

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2 Citations

The Community Coordinated Modeling Center at NASA, Goddard Space flight Center, provides access to state-of-the-art space weather models to the research community. The majority of the models residing at the CCMC are comprehensive computationally intensive physics-based models. The CCMC also provides free services and tools to assist the research community in analyzing the results from the space weather model simulations. We present an overview of the available tools and services at the CCMC: the Runs-On-Request system, the online visualization, the Kameleon access and interpolation library and the Metrics Challenge tools suite.


Citations (14)


... The halo CME causing the Dragon Day Event is missed by forecasters, and it is not included in the Community Coordinated Modeling Center (CCMC) CME Scoreboard 69 (refer to Kay et al. 70 for more information). Viewing from the Earth, it is an very slow and tenuous CME with a faint, intermittent front connected to a clearer southward-propagating part. ...

Reference:

Unexpected major geomagnetic storm caused by faint eruption of a solar trans-equatorial flux rope
Updating Measures of CME Arrival Time Errors

... UREs have also been reported to lead to increased graduation rates among populations underrepresented in STEM (Nagda et al., 1998;Krim et al., 2019). While the majority of URE studies in the literature were conducted at colleges and universities, Damas et al. (2020) and Nerio et al. (2019) report that URES at CCs have the potential to increase graduation rates and transfer from CCs into bachelor's degree-granting STEM programs (Nerio et al., 2019;Damas et al., 2020). However, it is important to note that data regarding transfer of underrepresented students from CCs to STEM programs at bachelor's degreegranting institutions can be challenging to track (Ashcroft et al., 2020) and do not always take into account that many workforce students have an intent to enter occupational programs rather than seek a bachelor's degree. ...

A Model of an Integrated Research and Education Program in Space Weather at a Community College

... This model prediction proved to be a little early, with the main CME actually arriving at around 0100 UTC on 18 February. By using the SWMF model, a series of research works [65][66][67][68][69] were conducted on the formation and propagation of CMEs and their interaction with the surrounding solar wind environment, successfully reproducing the morphology and evolutionary characteristics of CMEs. The CMEs in these cases were modeled by the Titov and Dmoulin [70] flux rope or the analytical Gibson-Low (GL) [71] flux rope and its improved version, called Eruptive Event Generator Gibson-Low (EEGGL), which was developed to automatically determine the GL flux rope parameters from the observations. ...

Data Constrained Coronal Mass Ejections in A Global Magnetohydrodynamics Model

The Astrophysical Journal

... However, in specific instances such as equipment maintenance, network failures, holiday periods, etc., the timely acquisition of geomagnetic and solar indices might pose limitations. These conditions may limit the use of the model and fail to meet the requirements of operational forecasting [30][31][32][33]. Real-time collection of monitoring data emerges as a crucial factor in the transition from Space Weather Research to Operations (R2O) [34][35][36]. ...

Forecasting propagation and evolution of CMEs in an operational setting: What has been learned
  • Citing Article
  • October 2013

... This led to the fast magnetotail reconnection rates observed in kinetic simulations and quasi-periodic loading-unloading (multiple reconnection) in the magnetotail for steady southward IMF B z conditions. [5] In our previous studies [Taktakishvili et al., 2007] we used the FRC model to investigate the buildup of the ring current during the quasi-periodic loading-unloading in the magnetotail for steady southward IMF. As input to the FRC model we used the results of the simulation obtained with the method of Kuznetsova et al. [2007]. ...

Buildup of the Ring Current During Periodical Loading-Unloading Cycle in the Magnetotail Driven by the Steady Southward IMF
  • Citing Article
  • May 2006

... There is now an extensive suite of simulation tools to study virtually every area of space physics. Many computational tools have been gathered at NASA's Community Coordinated Modeling Center (CCMC) [Chulaki, 2017], which provides an arena for anyone to request simulations for space physics research. In summary, Earth's home in space is being studied using a diverse array of approaches. ...

Research Tools Available at the Community Coordinated Modeling Center
  • Citing Article
  • December 2007

... There is now an extensive suite of simulation tools to study virtually every area of space physics. Many computational tools have been gathered at NASA's Community Coordinated Modeling Center (CCMC) [Chulaki, 2017], which provides an arena for anyone to request simulations for space physics research. In summary, Earth's home in space is being studied using a diverse array of approaches. ...

IHY Modeling Support at the Community Coordinated Modeling Center
  • Citing Article
  • January 2005

... Most of these models have versions implemented that undergo testing in NRT, e.g., at the NASA integrated Space Weather Analysis system (iSWA, http://iswa.gsfc.nasa.gov) [Maddox et al., 2010]. Furthermore, many of these models undergo verification and validation with archival data, in particular for evaluating their performance at the Community-Coordinated Modeling Center (CCMC, http://ccmc.gsfc.nasa.gov), ...

Utilizing real-time and near real-time data in the iNtegrated Space Weather Analysis System
  • Citing Article
  • December 2010

... One well-known and widely used model is the WSA-ENLIL+Cone model, which provides ambient solar wind simulations (by Wang-Sheeley-Arge (WSA) model), CME propagation (by ENLIL), and considers CME geometry (via the cone model). The version of the WSA-ENLIL+Cone model presented by NASA is described in [6]. The WSA model requires solar magnetograms to derive solar wind speed at the ENLIL inner boundary [7,8]. ...

Validation of the coronal mass ejection predictions at the Earth orbit estimated by ENLIL heliosphere cone model
  • Citing Article
  • March 2009

Space Weather: The International Journal of Research and Applications

... In a wider approach, CCMC has effectively established an "Open Model Policy" that gives access to modern space science simulations through one-of-a-kind Runs-on Request (RoR) system (Webb et al., 2009) for anyone interested in the subject. A full list of models accessible through CCMC services, including also ionospheric prediction models is available at https://ccmc.gsfc.nasa.gov/models/. ...

Ionosphere-thermosphere models at the Community Coordinated Modeling Center
  • Citing Article
  • February 2009