TY - JOUR
T1 - The August 2011 URSI World Day campaign
T2 - Initial results
AU - Immel, Thomas J.
AU - Liu, Guiping
AU - England, Scott L.
AU - Goncharenko, Larisa P.
AU - Erickson, Philip J.
AU - Lyashenko, Mykhaylo V.
AU - Milla, Marco
AU - Chau, Jorge
AU - Frey, Harald U.
AU - Mende, Stephen B.
AU - Zhou, Qihou
AU - Stromme, Anja
AU - Paxton, Larry J.
N1 - Funding Information:
This research work was supported by the National Science Foundation's CEDAR program through Award AGS-1042261 , NSF's Aeronomy program through Award AST-1019065 and the National Aeronautics and Space Administration’s Heliophysics Research program through Award NNX12AD48G . We thank the URSI incoherent scatter radar working group (ISWG) for helping with the organization of this world day campaign. The Arecibo Observatory is operated by SRI International under a cooperative agreement with NSF (AST-1100968), an in alliance with Ana G. Mendez-Universidad Metropolitana, and the Universities Space Research Association. Work at the MIT Haystack Observatory has been supported by NSF Co-operative Agreement ATM-0733510 with the Massachusetts Institute of Technology. The Jicamarca Radio Observatory is a facility of the Intituto Geofisico del Peru operated with support from the NSF AGS-0905448 through Cornell University. The Sondrestrom Radar measurements and analysis are supported under cooperative agreement NSF EAR-0836152 between NSF and SRI International. Work at Miami University was supported by NSF CEDAR Grant AGS-1042223 . The ACE satellite data are obtained from the ACE Science Center and we acknowledge E. Ness and D. McComas for their provision of these data. The Dst and Kp index data are available at the World Data Center for Geomagnetism. THEMIS data are provided by NASA contract NAS5-02099. Specifically we thank K.H. Glassmeier, U. Auster and W. Baumjohann for the use of THEMIS FGM data provided under the lead of the Technical University of Braunschweig and with financial support through the German Center for Aviation and Space (DLR) under contract 50 OC 0302 .
PY - 2015/11/1
Y1 - 2015/11/1
N2 - During a 10-day URSI World Day observational campaign beginning on August 1, 2011, an isolated, major geomagnetic storm occurred. On August 5, Kp reached values of 8- and Dst dropped to -113nT. The occurrence of this isolated storm in the middle of a 10-day URSI World Day campaign provides and unprecedented opportunity to observe the coupling of solar wind energy into the magnetosphere and to evaluate the varied effects that occur in the coupled magnetosphere-ionosphere-thermosphere system. Dramatic changes in the ionosphere are seen at every one of the active radar stations, extending from Greenland down to equatorial Peru in the American sector and at middle latitudes in Ukraine. Data from TIMED and THEMIS are shown to support initial interpretations of the observations, where we focus on processes in the middle latitude afternoon sector during main phase, and the formation of a dense equatorial ionosphere during storm recovery. The combined measurements strongly suggest that the changes in ionospheric conditions observed after the main storm phase can be attributed in large part to changes in the stormtime thermosphere. This is through the generation of disturbance dynamo winds and also global neutral composition changes that either reduce or enhance plasma densities in a manner that depends mainly upon latitude. Unlike larger storms with possibly more sustained forcing, this storm exhibits minimal effects of persistent meridional stormtime wind drag, and little penetration of solar wind electric potentials to low latitudes. It is, therefore, an outstanding example of an impulsive event that exhibits longer-term effects through modification of the background atmosphere.
AB - During a 10-day URSI World Day observational campaign beginning on August 1, 2011, an isolated, major geomagnetic storm occurred. On August 5, Kp reached values of 8- and Dst dropped to -113nT. The occurrence of this isolated storm in the middle of a 10-day URSI World Day campaign provides and unprecedented opportunity to observe the coupling of solar wind energy into the magnetosphere and to evaluate the varied effects that occur in the coupled magnetosphere-ionosphere-thermosphere system. Dramatic changes in the ionosphere are seen at every one of the active radar stations, extending from Greenland down to equatorial Peru in the American sector and at middle latitudes in Ukraine. Data from TIMED and THEMIS are shown to support initial interpretations of the observations, where we focus on processes in the middle latitude afternoon sector during main phase, and the formation of a dense equatorial ionosphere during storm recovery. The combined measurements strongly suggest that the changes in ionospheric conditions observed after the main storm phase can be attributed in large part to changes in the stormtime thermosphere. This is through the generation of disturbance dynamo winds and also global neutral composition changes that either reduce or enhance plasma densities in a manner that depends mainly upon latitude. Unlike larger storms with possibly more sustained forcing, this storm exhibits minimal effects of persistent meridional stormtime wind drag, and little penetration of solar wind electric potentials to low latitudes. It is, therefore, an outstanding example of an impulsive event that exhibits longer-term effects through modification of the background atmosphere.
UR - http://www.scopus.com/inward/record.url?scp=84943578335&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84943578335&partnerID=8YFLogxK
U2 - 10.1016/j.jastp.2015.09.005
DO - 10.1016/j.jastp.2015.09.005
M3 - Article
AN - SCOPUS:84943578335
VL - 134
SP - 47
EP - 55
JO - Journal of Atmospheric and Solar-Terrestrial Physics
JF - Journal of Atmospheric and Solar-Terrestrial Physics
SN - 1364-6826
ER -