Substorm Activity during CME and CIR Driven Storms Smitha Thampi, Diwakar Tiwari, Ruigang Wang, Hui Zhang, Ling Qian Zhang, Yihua Zheng Tutor: Robert L. McPherron

Introduction & Scientific Background Geomagnetic storms, in which the global geomagnetic field intensity decreases on the order of tens to hundreds nT, are large scale phenomena in the solar wind- magnetosphere-ionosphere coupling. Geomagnetic storms develop when solar wind- magnetosphere couplings are intensified by solar wind disturbances (coronal holes and CMEs). Types of Geomagnetic storms: CME driven, CIR driven, (others) Solar minimum (CIRs) Solar maximum (CMEs)

Characteristics (view of the present): the storms driven by the fast CMEs are usually very intense (Dst <-100 nT), while the storms diven by CIRs are usually weaker and their main phase has irregular profile and long recover phase lasting many days to weeks and cause High Intensity Long Duration Continuous AE Activity (HILDCAAs). Since they are caused by recurrent high speed streams, they are ordered in time. Importance: Although CIR storms are weak, they may be very important in generating relativitic electrons (semiannual variation of killer electrons and Dst in solar minimum), which are detremental to spacecraft, human in space and so on. ====> Focus of the proposal: Characteristics of CIR storms and the differences and similarities between the two types of magnetic storms Introduction & Scientific Background --- continued

High flux of killer electrons appear in solar minimum Killer electrons' semiannual variations Dst also has semiannual variations ==> solar min storms correlate with killer electron fluxes CIR storms ~ killer e- fluxes

Scientific objectives: to understand the characteristics, and the differences and similarities of the solar origin (the driver) of the two types of magnetic storms and the differences and similarities of the ionosphere's responses to the two-type storms via auroral activities. Specifically, we will use 40 years of solar wind and IMF data along with other necessary parameters to study: Difference (if any) between CME and CIR Storms (solar wind and IMF para.) Distribution of AE during CME and CIR storms Duration of AE disturbances in the recovery phase of two types of storms The role of Russell-McPherron effect on CIR storms Effects of the two storm types on relativistic electrons Other Ionospheric effects caused by the two types. (???? more specific?) Scientific Objectives

Scientifically: this investigation will help in better understanding the following outstanding questions related to geomagnetic storms: a) the role of solar wind density in storm growth? b) How do the properties of storms change with the solar cycle? c) Does storm development depend on season and universal time? Pratically: with better understanding of the driver characteristics of two types of storms during solar minimum and solar maximum, it will help us in a better definition of forecasting procedure from the solar origin, which is crucial in space weather forecasting. Relativistic (killer) electrons are detremental to satellites, human in space and can also create great damage on the ground. They are known to have high fluxes during solar minimum and are possibly correlated to CIR driven storms. Understanding their relationship is very important for reducing or minimizing their damaging effects. Significance of the proposal

Approach Data sets required OMNI data Synchronous relativistic electron fluxes ISCAT/SuperDARN Range-Time-Intensity/Velocity Preprocessing Data editing and creation of Matlab binary files Analysis tools Plot solar wind and IMF data along with AE and Dst indices to select events and then the significant times for further analysis==> Use Matlab built-in functions and/or procedures and also develop necessary software to perform statistical analysis and display tools

An example of how to find CIR recurrent high speed stream interface Details on analysis approaches

Preliminary results

Preliminary Results

Work Plan (1 year) Data Downloading: Ruigang Wang and Hui Zhang (1month) Software development: Diwakar Tiwari, Smitha Thampi (1 month) Literature search and knowledge enhancement: Yihua Zheng and Ling Qian Zhang (1 month) These are done simultaneously. Event selection and data analysis: divide and conquer, each of the team members perform the investigation for several years (10 month) nterpretation of the results: all (1 month)

References 1. Gonzalez, W. D., B. T. Tsurutani and A. L. C. Gonzalez, Interplanetary origin of geomagnetic storms, Space Sci. Rev. 88, , Kamide, Y., R.L. McPherron, W.D. Gonzalez, D.C. Hamilton, H.S. Hudson, J.A. Joselyn, S.W. Kahler, L.R. Lyons, H. Lundstedt, and E. Szuszczewicz, Magnetic storms: Current understanding and outstanding questions, in Proceedings of the Chapman Conference on Magnetic Storms, pp. 1-19, American Geophysical Union, Jet Propulsion Laboratory, Pasadena, CA, McPherron, R.L., Physical processes producing magnetospheric substorms and magnetic storms, in Geomagnetism, Vol 4, edited by J. Jacobs, pp , Academic Press Ltd., London, England, O'Brien, T.P., Empirical Analysis of Storm-Time Energetic Electron Enhancements, Unviersity of California Los Angeles, Los Angeles, O'Brien, T.P., R.L. McPherron, D. Sornette, G.D. Reeves, R. Friedel, and H.J. Singer, Which magnetic storms produce relativistic electrons at geosynchronous orbit?, Journal of Geophysical Research, 106 (A8), , Tsurutani, B. T., and W. D. Gonzalez, The cause of high-intensity long-duration continuous AE activity (HILDCAAS): Interplanetary Alfven wave trains, Planet. Space Sci., 35, , Tsurutani, B.T., and W.D. Gonzalez, The causes of geomagnetic storms during solar maximum, presented at Eos Trans. AGU, Tsurutani, B.T., W.D. Gonzalez, and Y. Kamide, Magnetic storms, Surveys in Geophysics, 18, , 1997.

Extras

Motivation---some open questions in Solar Cycle Variations in Storms ● Is there a difference between storms at solar minimum and maximum? Do solar minimum storms develop differently from solar-max storms? Do these storms last longer? Does the occurrence rate of substorms, SMC, Sawtooths in different phases of a storm change with solar cycle? Why are there more killer electrons at solar minimum? Why is there a strong semiannual and universal time variation in occurrence and size of storms at solar minimum? What physical effects are the cause of the semiannual variation in Dst? What effects do Alfen waves in high speed streams have on storms?