Subjects: Astronomy submitted time 2023-07-14 Cooperative journals: 《天文学报》
Abstract： Ion cyclotron waves (ICWs) are one kind of plasma waves whose frequency is close to the ion cyclotron frequency. They exist widely in the upstream of Mars, and the frequency observed by satellites is generally near the proton cyclotron frequency. ICWs are byproducts in the production processes of pick-up ions. The occurrence of ICWs constitutes, in principle, an indirect signature of the presence of newborn planetary protons. ICWs upstream of Mars have received much attention since they were first reported in 1990. In this review, we summarize the research progress of ICWs in the upstream of Mars, including the observation of ICWs, the wave generation mechanism, their statistical properties and related future research trends.
Subjects: Geosciences >> Space Physics submitted time 2017-01-22
Abstract： A minor sudden stratospheric warming(SSW) event occurred in the early and middle January of 2014. The amplitude of increasing temperature was about 25K , the zonal eastward wind became weaker and shifted its direction until the early February. The planetary waves (PWs) are believed to have significant role in SSW events. So using the wind data detected by 5 meteor radars at low and middle latitude of northern hemisphere near 120 , we studied the PWs during this minor SSW event. Results show that the enhanced quasi 16-day PWs can be found at mesosphere and lower thermosphere (MLT) region. The enhancement of quasi 16-day waves were prior to the warming, and the quasi 16-day PWs had mostly the strongest amplitude when the polar temperature reach its peak. This demonstrates the coupling between low and middle latitude MLT region and SSW. Furthermore, we used the reanalysis data from the European Centre for Medium-range Weather Forecasts (ECMWF) to investigate the wave coupling between stratosphere and mesosphere. The band pass filter of the stratospheric temperature shows that quasi 16-day PWs propagated period lower latitude to the pole, meanwhile the zero-wind line moved from low latitude to high latitude, indicating a dynamical connection between the 16-day PWs and SSW.
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