A statistical analysis of ionospheric joule heating driven by interplanetary coronal mass ejections and high speed streams using SWMF/BATS-R-US MHD model

Abstract

Space weather is the changes in the interplanetary space caused mainly by solar activity. Some of the space weather hazards are disruption of radio communication signals, disruption of electrical systems, increased satellite drag and increased radiation dosage on flights. Thus, the observations and predictions of these space weather events are significantly important with the developing space science and technology. Two major solar phenomena that affect the environment near Earth the most are classified as coronal mass ejections and high speed solar wind streams. Depending on the solar activity, the sunspot cycle, their occurrence rate changes. Due to their origin, occurrence, interplanetary structure and the geomagnetic disturbances they drive, they affect the space weather in different ways and intensities. Solar wind- magnetosphere-ionosphere coupling process is driven differently for each phenomena. The energy budget of the solar phenomena is dissipated into the magnetosphere-ionosphere system resulting in moderate to major geomagnetic disturbances, called geomagnetic storms. Geomagnetic storms are one of the highest contributions to this dissipation is via Joule heating, which is a frictional heating in the ionosphere caused by the electrical currents. Thus, in this study, the main aim is to reveal the differences of this two major phenomena (CMEs and HSSs) in the interplanetary space, then to investigate their driven geomagnetic storms in detail with their phases and finally to compare the Joule dissipation contributions (1) for their structural regions and (2) for the driven geomagnetic storm phases. Hereby, the differences of the coronal mass ejections and high speed solar wind streams would be tracked from their origin in the Sun, to the interplanetary space until they interact with the Earth's magnetosphere-ionosphere system. In the literature it is shown that the two phenomena have different structures and different driven geomagnetic storms. CMEs in the interplanetary space are named as interplanetary coronal mass ejections (ICMEs) that consist of sheath (SH) and magnetic obstacle (MO) regions. The sheath region is followed just after the shock, thut it is a turbulent region with high temperature and speeds. On the other hand, a magnetic obstacle is the highly magnetized part of the ICME, which is generally referred to magnetic cloud with flux-rope pattern. The coronal hole high speed streams in the interplanetary space are named as corotating interaction region high speed streams (CIR/HSS) due to their continuous pattern with the Sun's rotation and longer presence. CIR/HSSs do not have a fast forward shock, thus the parameters do not have an abrupt increase but the density and magnetic field parameters increase before the others due to the compression of the fast and solar wind interaction region. Due to these differences it is thought that both phenomena have different Joule dissipation rate. ICME driven storms are generally moderate to extreme in intensity, whereas the CIR/HSS driven storms are minor to moderate in intensity. Both phenomena have initial, main and recovery phases of their geomagnetic storms. But in the case of ICMEs, the initial phase starts with a storm sudden commencement (SSC) differently from CIR/HSSs due to the fast forward shock. Also the main phase in the ICME driven storms are more intense. The recovery phase in both phenomena can last longer, but in CIR/HSS cases the full recovery is not that clear. Thus, the disturbances can last longer. Overall, it is expected that each phase has a different contribution in Joule heating of the ionosphere. Joule dissipation is known as the heating of the upper atmosphere due to the ionospheric currents and friction of the ion-neutral collisions. It is not a directly observable parameter. And since it is a derived parameter, there are several techniques developed to estimate the heating rate. These methods include using ground based methods together with space-borne measurements and MHD models. Recently, the most preferred approach is to use physics-based models for the estimation of Joule heating. SWMF/BATS-R-US with RCM is one of the latest models developed by CCMC in order to obtain ionospheric electrodynamics parameters by solving MHD equations and then to estimate ionospheric dissipation. Thus, we decided to run the SWMF/BATS-R-US model to estimate Joule heating. Firstly in this study, as solar phenomena, three CME and three HSS cases were selected to investigate. Then, the CME events were selected by using the SOHO/LASCO C2 coronagraph and HSS events were observed from the SDO/AIA telescope images. After the remote sensing observations, WIND spacecraft in L1 point was used to obtain in-situ data measurements. The event intervals are corrected by using ICME and CIR/HSS catalogs. Secondly, the SWMF/BATS-R-US magnetospheric MHD model was run in order to obtain Joule dissipation data covering the event intervals. After obtaining the model outputs, the structural intervals of CMEs and HSSs were determined and the corresponding Joule heating rates per unit time were determined. After, the ICME-driven and CIR/HSS-driven geomagnetic storm phase intervals were determined and the Joule heating rates corresponding to these phases were determined for each. To make a detailed comparison, simple linear regression and multi linear regression analyses were performed for the structural intervals. To compare the structural correlations in order to find out the controlling parameters, energy efficiency analysis was also performed for the geomagnetic storm intervals referring to the magnetospheric processes. By the help of these analyses, it was found that the CMEs lead to the higher rates of Joule dissipation in the upper atmosphere rather than HSSs, mostly due to their magnetic obstacle regions. Also the geomagnetic storm interval resulted in more Joule heating for the CME cases. Main phases of the driven storms from both phenomena were found to relate with the highest Joule heating rate per unit time. With the SLR and MLR analyses, it was found for HSS that their controlling parameters are the geomagnetic activity parameters, whereas the controlling parameters of the CMEs are the solar wind parameters. This result revealed that the Joule heating driven by the HSSs are more effective and produced by the magnetospheric processes, whereas the Joule heating driven by CMEs are less effective and produced by the solar wind energy budget of the phenomena. In Chapter 1, the aim of this study and literature work is introduced. In Chapter 2, solar activity and space weather are defined. Then CME and HSS phenomena are investigated in detail, followed by a description of geomagnetic storms and their phases and energy exchange processes. Chapter 3 explains the Joule heating, existing methods for estimations and the SWMF/BATS-R-US model. Chapter 4 consists of the selection of CME and HSS cases, run details of the MHD model, structural analysis of CMEs and HSS, geomagnetic storm analysis of ICMEs and CIR/HSSs, simple and multi linear regression analyses for all cases and finally the energy efficiency analysis. In Chapter 5, the results are explained and the summary is given with future work recommendations.