2010 Alum

John J. Braswell

Theresa Carranza-Fulmer

Years participated in RESESS:
2011 →

An Overview

Analysis of three real-time geomagnetic storm indices

Academic Affiliation: Senior, The City College of New York, Physics and Geology
Science Research Mentors: Jennifer Gannon, Jeffrey J. Love, USGS
Writing Mentor: Hartmut Spetzler, University of Colorado at Boulder
Community Mentor: Melissa Weber, UNAVCO


At an early age Theresa’s mother introduced her to the natural world and to the science that explained how all of the intricate systems worked together. This experience gave her the opportunity to explore the many fields of science and has enabled her to find her passion for both geoscience and physics. She is currently attending The City College of New York, studying physics and geology. The RESESS internship has helped her discover a passion for the field of space weather and she hopes to pursue this area for graduate studies. Besides going to school, she enjoys rock climbing, hiking, camping, and crossing Iowa on bike. In her down time she likes to play the drums, go star gazing, and listen to talk radio from science to politics.


The Dst, or geomagnetic storm index, was first created by the Kyoto World Data Center and is commonly used to specify geomagnetic disturbance periods and characterize the resulting ring current enhancements from ground-based horizontal magnetic field intensity measurements. Real-time versions of the Dst index are produced for operational purposes, and are of interest to many users, including the US military, airline industry, and power companies. USGS Real time Dst, Kyoto Quicklook Dst, and Space Environment Corporation RDst use preliminary data and use a variety of contributing observatories and methods. Both USGS and RDst use a combination time and frequency domain method and Kyoto uses a time domain method in creating the Dst index. We perform an analysis of these three real-time Dst indices for the time period of October 1, 2009 to May 31, 2010. The USGS 3, using three observatories instead of the standard four, and the Kyoto Sym-H index are introduced in the analysis for comparison of observatory location with the three main Dst indices. We present a statistical study of the differences due to algorithm, output time resolution, and location of contributing observatories. Increased time resolution shows higher frequency fluctuations during disturbances and more defined storm features. There was no measurable difference in mid- to low-latitude observatories during quiet-to-moderate storm time periods. The average impact on the index due to the different algorithms used was approximately 9 nT during active time periods.