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The Signature of the March 31, 2001 Geomagnetic Storm

in Aurora Dx Communication on Very High Frequencies

Actual results of a data analysis project in ham radio

Volker Grassmann, DF5AI

Last update: June 01, 2005


Note: Readers not yet familar with amateur radio propagation studies are requested to read this special introduction first: more ...

There is a long history of Auroral backscatter analyses using amateur radio observations on very high frequencies (see, e.g., [1], [2]-[5], [26], [27], [28], [31], [35]). On the other hand, no analysis has yet considered simultaneous Auroral backscatter observations from radio amateurs located in different continents. Geomagnetic storms represent global events, we may therefore conclude that Aurora dx openings develop on a global scale too. This assumption is supported, for example, by the dx reports distributed by the dx cluster networks: having identified an Aurora dx opening in the European sector, the dx cluster also provides information on dx QSOs in North America, and vice versa. The regional characteristic of Aurora dx openings is indeed well known, we however lack detailed information when considering Aurora band openings from a global perspective (note: when using the term global we actually focus on polar and mid-latitudes, excluding equatorial regions because Auroral backscatter is not available there).

About this project

In this project, we will analyse the global characteristics of Aurora dx communication associated with a major geomagnetic storm. Initially, a number of recent storm events was taken into consideration when preparing this project - it is the March 31, 2001 event which was finally selected here. That choice results from the requirements in data acquisition, i.e. this event can provide sufficient material from radio amateurs and from scientific internet resources as well.

The project separates into individual work packages allowing the author to organize data acquisition, data analyses and discussions in modular tasks. The reader is therefore confronted with an ensemble of living documents which may change look and content depending on the actual progress (all documents therefore show an individual date information in the header).

Please note, that the documents deal with two types of references, i.e. numbers in brackets and highlighted text, respectively. For example: the reference [10] denotes material which is explicitly used in this document, see the list of references at the bottom of this page. Terms such as solar wind, on the other hand, denote hyperlinks to general background information available in the internet. The reader may visit this internet locations to access additional information from professional web sites edited by experts and scientists.

Outlook and actual results

Project structure and work packages

The following paragraphs provide an overview on the individual work packages which are organized in three main categories, i.e. organizational aspects, data acquisition and data analysis methods and, finally, the result section, respectively. The author appreciates comments, suggestions and ideas at all times. This project may be considered an open project, i.e. radio amateurs wishing to suggest alternative methods of data processing, special analyses and creative concepts in data visualization are requested to contact the author by email, see the box on the right.


To contact the author, please follow this link.

Objectives & organisation

Because of the huge amount of data, this project requires some sort of organizational framework. View the project's objectives, the road map and the actual status report. More...


Data acquisition, tools and analysis methods


This project received special support from the POES team at NASA that has contributed a sequence of data files documenting the Auroral activity on March 31, 2001. Information on more than 3.800 Aurora QSO was obtained in the data acquisition phase between December 2002 and May 2003. Eliminating double counts, the analysis now considers around 2.200 Aurora QSOs. The European sector contributes around 1.900 QSOs, 240 QSOs originate from North America and 21 from Australia. The data covers the observation period from 0010 UT to 2356 UT on March 31, 2001. More...

data acquisition


Number and data crunching software tools are most important in this data analysis project, of course. The BeamFinder software will in particular play an important role here because it can easily handle thousands of QSOs and it can analyse the individual backscatter geometry of all dx QSOs. More...



Reliable information on the dx stations' actual antenna heading is not available, i.e. we cannot locate Aurora positions by applying the geometrical method of triangulation. In this analysis, we will therefore refer to an innovative method which can estimate Aurora positions without using antenna headings or any other type of directional information. More...

locating Aurora

Data analysis, results and interpretation


On March 28, 2001, a coronal mass ejection (CME) near the active sunspot region 9393 hurled a high-speed solar wind stream of electrified, magnetic gas towards the Earth. On March 31, 0053 UT, this shock front pushed into the dayside magnetosphere causing geomagnetic field disturbances and other types of phenomena including wide spread Aurora band openings on very high frequencies. More...

storm history


The sequence of POES data plots has been assembled to an animated view of the Auroral activity in the northern hemisphere. Watch the Auroral oval rotating around the geomagnetic pole and see the variation of the hemispheric input power during the day. A broadband internet connection is recommended to load the animation (1.7 megabytes) in reasonable time. More...

Auroral activity


An impressive correlation was found between the QSO data and the actual direction of the interplanetary magnetic field (IMF) - which is no surprising result but it is this project that documents the feature for the first time. More...



The intensity of Auroral backscattering shows significant fluctuations which are also present in the QSO activity, of course. 50 percent of the QSO data has been contributed by 90 percent of the stations, i.e. the second half of the QSO data originates from only 10 percent of the stations. More...

operational results


To compare the POES satellite data with the QSO data, the POES polar plots have been transfered to BeamFinder's Maidenhead grid locator map together with the Aurora QSO data from VHF radio amateurs. A broadband internet connection is recommended to load the animation (2.1 megabytes) in reasonable time. More...



The distribution of QSO distances shows two unusual maxima in the European sector which cannot be explained. In North America, the distribution is shifted to shorter paths lengths for on unknown reason. More...

QSO distances

... to be continued


The author is grateful to D. Evans and S. Greer (NOAA/POES) and Dr. Phillips (Science@NASA, for providing scientific background data. Many thanks also to A. Kantola (OH2AQ DX Cluster), the Dubus magazine, 9A1CAL, DD0VF, DF2ZC, DG3GAG, DG9MAQ, DH0GHU, DK1GS, DK1KO, DK3XT, DK5YA, DL1EJA, DL1ELY, DL1SUZ, DL2FDL, DL2OM, DL6WU, DL6YEH, DL8HCZ, DL8LAQ, DL9YBZ, DM2DXG, G0AEV, G1OGY, G3LTF, G3UYM, G3YYD, G4ASR, G4IFX, G8HGN, GM0ONN, GM4AFF, GW8IZR, HA6NN, HB9DFG, I1JTQ, I3LGP, I5WBE, IK2YXK, IZ1BPN, LA0BY, LA3BO, LY2SA, OE1SOW, OE3FVU, OE3MWS, OH1HSC, OH5LK, OH5IY, OH6FX, OH6MAZ, OK1TEH, OK2POI, OK2PM, OM5UM, ON4LN, OY9JD, OZ4VW, PA4VHF, PA5DD, PE1HWO, RK3AF, S53VV, SP2IQW, SP4MPB, UA3TCF, VE5UF, VK3AFW, VK3BJM, VK3CAT, W0VB, W3ZZ, W8WN, W9JN and M. Farrell for providing observation data and valuable assistance.


Due to limitations with the HTML environment which does not support document management functions, the following list of references does not follow any specific order, neither chronologically nor alphabetically. The author apologizes for any inconveniences caused by the present arrangement.



Analyse von Rückstreubeobachtungen ultrakurzer Wellen an Polarlichtern

Czechowsky, P., Diplomarbeit, Max-Planck-Institute for Aeronomie, 1966


Einfluß der solar-terrestrischen Beziehungen auf die Rückstreuausbreitung in 2m- und 10-m-Band, Teil 1

Kochan, H., cq-DL 6, 346-350, 1974


Einfluß der solar-terrestrischen Beziehungen auf die Rückstreuausbreitung in 2m- und 10-m-Band, Teil 2

Kochan, H., cq-DL 7, 386-391, 1974


Einfluß der solar-terrestrischen Beziehungen auf die Rückstreuausbreitung in 2m- und 10-m-Band, Teil 3

Czechowsky, P., cq-DL 10, 601-605, 1974


Einfluß der solar-terrestrischen Beziehungen auf die Rückstreuausbreitung in 2m- und 10-m-Band, Teil 4

Czechowsky, P., cq-DL 11, 666-669, 1974


NCDXF/IARU International Beacon Network


The DX Summit (OH9W/OH2AQ DX Cluster)


Review of March 31, 2001 Geomagnetic Storm Activity - Metatech Corp.

Kappenman, J. G.,


March 2001 Solar Storm

Odenwald, S.,


March 31 - April 1, 2001 Aurora Gallery

Phillips, T.,,


Aurora Australis - 31 March 2001

Picking, C. J.,


Realtime Magnetometer Data - Swedish Institute of Space Physics

Aparicio, B., Häggström, I., Luspa, M.,


ACE RTSW (Estimated) Mag from March 31, 2001

Phillips, T.,,


Phillips, T.,


Phillips, T.,


The Interplanetary Magnetic Field

Phillips, T.,


Space weather worecast: Sunny again, very sunny



Giant sunspot erupts

BBC News,


A tail current dominated storm main phase: March 31, 2001

Skough, R. M., et al,


Geomagnetic effects on power systems

Natural Resources Canada,


Space Weather Impact on Communications at Solar Maximum

Caner, Lj. R., D53-3 Propagation project 53 Report,


Ionospheric Signatures of Plasmaspheric Tails

submitted to J. Geophys. Res. Letters, Foster, J.C. et al,


MIT Reports to the President 2000-2001, Haystack Observatory


Dx radius in Aurora and FAI radio propagation, part 1: Europe

Grassmann, V., DF5AI,


Dx radius in Aurora and FAI radio propagation

Grassmann, V., DF5AI, Dubus, 3, 2002, p. 23-32


VHF Biststic Auroral Backscatter Communication

Lange-Hesse, G., Ionospheric Radio Communication, New York 1968, p. 174-206


The Boundary Fence

Newton, C.E., G2FKZ, Dubus, 1, 1984, p. 24-32


Aurora Opening of 15-16 July 2000

Mack, J., NA3T,


The Aurora Email Forum

P., N1BUG,


The DX Robot

Munters, A., PE1NWL,


Radio in Observing Auroras

Yrjölä, I., OH5IY,


Aurora Echoes with Narrowband Radar

Asbrink, L., SM5BSZ,


SAM - Simple Aurora Monitor - ein Weg zu mehr Aurora QSOs

Hansky, K., DL3HRT, Langenbach, D., DG3DA, Dubus, 2, 2003, p. 36-53


Amateur Magnetometer Network Europe


Unusual Aurora observations in the 144 MHz band

Grassmann, V., DF5AI, Dubus, 4, 2002, p. 35-41, see also


The BeamFinder Analysis Software

Grassmann, V., DF5AI, and


Aurora - Ein Computerprogramm zur Analyse von Aurora- und FAI-Rückstreuungen

Grassmann, V., DF5AI, Dubus, 1, p. 18-21, 1988, see also


Aurora - A computer program to analyse Auroral- and FAI-scattering

Grassmann, V., DF5AI, Dubus, 2, p. 125-126, 1988, see also


The VHF/UHF dx book

White, I., G3SEK (editor); see chapter 2 (by Grayer, G., G3NAQ), RSGB 1995


Radio Auroras

Newton, C., G2FKZ, RSGB 1991


International Geomagnetic Reference Field

Web site of the World Data Center for Geomagnetism, Kyoto,



Copyright (C) of Volker Grassmann. All rights reserved. The material, or parts thereof, may not be reproduced in any form without prior written permission of the author.