Some magnetic impulse events observed in the polar region are related to vortices associated with plasma convection in the ionosphere. Recent analyses of satellite and ground data suggest that the interaction of solar wind dynamic pressure pulses and the magnetosphere may lead to the formation of velocity vortices in the magnetopause boundary layer region. This can in turn lead to the presence of vortices in the polar ionosphere. However, before reaching the Earth's magnetopause, these interplanetary pressure pulses must interact with and pass through the bow shock. A variation of the solar wind dynamic pressure (ApV 2) may be associated with shocks, magnetic holes, or tangential discontinuities (TDs) in the interplanetary medium. We study the interaction of interplanetary TDs with the Earth's bow shock (BS) using both theoretical analysis and MHD computer simulations. It is found that as a result of the collision between a TD and the BS, the jump in the solar wind dynamic pressure associated with the TD is significantly modified, the bow shock moves, and a new fast shock or fast rarefaction wave, which propagates in the downstream direction, is excited. Our theoretical analysis shows that the change in the plasma density across the interplanetary TD plays the most important role in the collision process. In the case with an enhanced dynamic pressure behind the interplanetary TD, the bow shock is intensified in strength and moves in the earthward direction. The dynamic pressure jump associated with the transmitted TD is generally reduced from the value before the interaction. A fast compressional shock is excited ahead of the transmitted TD and propagates toward the Earth's magnetosphere. For the case in which the dynamic pressure is reduced behind the interplanetary TD, the pressure jump across the transmitted TD is substantially weakened, the bow shock moves in the sunward direction, and a rarefaction wave which propagates downstream is excited. We also simulate and discuss the interaction of a pair of tangential discontinuities, which may correspond to a magnetic hole, with the BS. to infer that solar wind dynamic pressure variations (ApV 2) may lead to the presence of velocity vortices near the magnetopause [Friis-Christensen et al., 1988; Glassmeier et al., 1989; Southwood and Kivelson, 1990; Kivelson and Southwood, 1991]. Vortices in the low latitude-boundary layer (LLBL) map into the ionosphere via a field-aligned current system and can generate the convecting Hall current loops of a single vortex or twin vortices. Therefore one expects that a traveling ionospheric vortex or an induced unipolar (bipolar) magnetic pulse will be observed during such an event [Sibeck, 1990]. This suggestion is supported by the work of Lee [1991] in which MHD simulations of the interaction between the solar wind dynamic pressure pulses and the magnetopause boundary region were studied. The simulation results always show that flow vortices are formed in the LLBL when a shear pressure pulse impinges upon the magnetopause. In fac...
will be launched in late 2005. Its goal is to deploy a constellation of six low Earth orbit (LEO) microsatellites for weather and space weather forecast, climate monitoring, and atmospheric, ionospheric and geodesy research. There are three payloads on each satellite built to pursue these scientific objectives. The GPS Occultation Experiment (GOX) payload tracks Global positioning system (GPS) signals, the Tiny Ionospheric Photometer (TIP) payload measures the night sky photon emission, and the triband beacon (TBB) payload transmits three-frequency phase coherent signals.GPS Occultation experiment payload consists of GPS receivers, high-gain occultation antennas and precise orbit determination (POD) antennas to collect data for radio occultation (RO) sounding and precise orbit. An average of 2,500 globally distributed atmospheric soundings will be obtained each day. The GPS radio signal passing through the ionosphere and atmosphere will be refracted and/or diffracted resulting in the signal bending and slowing. Therefore, the GPS receiver onboard a FORMOSAT-3 satellite can track GPS signals in an atmospheric RO event when the GPS satellite is occulted behind the Earth's limb. GOX will measure the phase and amplitude of the L1 and L2 GPS carrier frequencies with high precision.The phase delays and amplitude attenuations of GPS signal are related to the air density and humidity in the troposphere and the electron density in the ionosphere. The relative movement and the clock error between GPS and LEO satellites also cause a phase shift. Therefore, the tropospheric delay can be obtained by removing the effects of the ionosphere, the relative movement and the Abstract The FORMOSAT-3/COS-MIC mission is a microsatellite mission for weather forecast, climate monitoring, and atmospheric, ionospheric and geodesy research. This mission is a collaborative Taiwan-USA science experiment to deploy a constellation of six microsatellites in low Earth orbits. The mission life is 2 years with a goal of 5 years. The final mission orbit has an altitude of 750-800 km. Each satellite consists of three science payloads: global positioning system (GPS) occultation experiment (GOX) payload, tiny ionospheric photometer (TIP) and tri-band beacon (TBB). The GOX will collect the GPS signals for the study on atmosphere, ionosphere, and geodesy. The TIP and TBB can provide the electron distribution information for ionospheric research. The deployment of the FORMOSAT-3 constellation and the resulting influence on the occultation sounding distributions are reported. Details are also given on GOX, TIP, and TBB payload operations and the contributions of the Taiwan Science Team. GPS Solut (2005) 9: 111-121
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.