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Engebretson, Mark
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Engebretson, Mark
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Engebretson, Mark J
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- PublicationOpen AccessReview of Environmental Monitoring by Means of Radio Waves in the Polar Regions: From Atmosphere to Geospace(2022)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ;; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ;The Antarctic and Arctic regions are Earth’s open windows to outer space. They provide unique opportunities for investigating the troposphere–thermosphere–ionosphere–plasmasphere system at high latitudes, which is not as well understood as the mid- and low-latitude regions mainly due to the paucity of experimental observations. In addition, different neutral and ionised atmospheric layers at high latitudes are much more variable compared to lower latitudes, and their variability is due to mechanisms not yet fully understood. Fortunately, in this new millennium the observing infrastructure in Antarctica and the Arctic has been growing, thus providing scientists with new opportunities to advance our knowledge on the polar atmosphere and geospace. This review shows that it is of paramount importance to perform integrated, multi-disciplinary research, making use of long-term multi-instrument observations combined with ad hoc measurement campaigns to improve our capability of investigating atmospheric dynamics in the polar regions from the troposphere up to the plasmasphere, as well as the coupling between atmospheric layers. Starting from the state of the art of understanding the polar atmosphere, our survey outlines the roadmap for enhancing scientific investigation of its physical mechanisms and dynamics through the full exploitation of the available infrastructures for radio-based environmental monitoring.406 86 - PublicationOpen AccessGround based observations of Pc3-Pc5 geomagnetic pulsation power at Antarctic McMurdo station(1998-06)
; ; ; ; ;Ballatore, P.; Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, U.S.A ;Engebretson, M. J.; Department of Physics, Augsburg College, Minneapolis, MN 55454, U.S.A ;Maclennan, C. G.; Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, U.S.A ;Candidi, M.; IFSI/CNR, Roma, Italy; ; ; The two horizontal geomagnetic components and, measured by a fluxgate magnetometer at Antarctic McMurdo station (corrected geomagnetic coordinates 80.0° S, 327.5° E), are analyzed for the period May-June 1994; the spectral powers are calculated and integrated over three frequency intervals corresponding to the nominal ranges. The time dependence of those integrated powers and their correlations with northern auroral indices and solar wind speed are considered. The observations are compared with previous results reported from Terra Nova Bay station (located near McMurdo at the same corrected geomagnetic latitude) during Antarctic summer intervals. The differences found between the two stations are discussed in terms of the seasonal dependence of geomagnetic field line configurations in the near cusp region.138 172 - PublicationRestrictedTwo-dimensional structure of long-period pulsations at polar latitudes in Antarctica(2004)
; ; ; ; ; ; ; ;Yagova, N.; Institute of the Physics of the Earth, Moscow, Russia ;Pilipenko, V.; Institute of the Physics of the Earth, Moscow, Russia ;Lanzerotti, L.; Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey, USA ;Engebretson, M.; Department of Physics, Augsburg College, Minneapolis, Minnesota, USA ;Rodger, A.; British Antarctic Survey, Cambridge, UK ;Lepidi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Papitashvili, V.; University of Michigan, Ann Arbor, Michigan, USA; ; ; ; ; ; Two-dimensional (2-D) statistical distributions of spectral power and coherence of polar geomagnetic variations with quasi-periods about 10 min are analyzed using data from magnetometer arrays in Antarctica. Examination of the 2-D patterns of spectral power and coherence shows the occurrence of significant variations in geomagnetic power levels but with low spatial coherence near the cusp projection and in the auroral region. At the same time, low-amplitude pulsations, which we coin Picap3 pulsations, are very coherent throughout the polar cap. The region occupied by coherent Picap3 pulsations is shifted toward local MLT night from the geomagnetic pole and is decoupled from the regions of auroral and cusp ULF activity. The spectral power varies with time at polar latitudes in a manner different from that at auroral latitudes. Diurnal variations of power at different stations at the same geomagnetic latitude exhibit different behavior depending on the station’s position relative to geomagnetic and geographic poles. This asymmetry is shown to be partly attributed to the variations of the ionospheric conductance. The primary source of polar pulsations is probably related to intermittent magnetosheath turbulence and tail lobe oscillations, though a particular propagation mechanism has not as yet been identified274 88