First Comparison of Mesospheric Winds Measured with a Fabry-Perot

A Fabry-Perot interferometer (FPI) for mesospheric observations was installed at King Sejong Station (62.2°S, 58.9°W) in Antarctica in 2017. For the initial validation of the FPI measurements, we compare neutral wind data recorded with the FPI with those from a Meteor Radar (MR) located nearby. The overall characteristics of the FPI and MR winds of both OH 892.0 nm (87 km) and OI 557.7 nm (97 km) airglow layers are similar. The FPI winds of both layers generally match the MR winds well on the observed days, with a few exceptions. The correlation analysis of the FPI and MR wind data shows that the correlation coefficients for the zonal winds at 87 and 97 km are 0.28 and 0.54, respectively, and those for the meridional winds are 0.36 and 0.54, respectively. Based on the assumption that the distribution of the airglow emissions has a Gaussian function with respect to the altitude, we calculated the weighted mean winds from the MR wind profile and compared them with the FPI winds. By adjusting the peak height and full width at half maximum of the Gaussian function, we determined the change of the correlation between the two winds. The best correlation for the OH and OI airglow layers was obtained at a peak height of 88–89 km and 97–98 km, respectively

VHF meteor radar at King Sejong Station, Antarctica

Since 2002, we have been observing the mesosphere and lower thermosphere (MLT) region over King Sejong Station (KSS; 62.22°S, 58.78°W), Antarctica, using various instruments such as the Spectral Airglow Temperature Imager (SATI), All Sky Camera (ASC) and VHF meteor radar. The meteor radar, installed in March 2007, continuously measures neutral winds in the altitude region 70–110 km and neutral temperature near the mesopause 24 h∙d-1, regardless of weather conditions. In this study, we present results of an analysis of the neutral wind data for gravity wave activity over the tip of the Antarctic Peninsula, where such activity is known to be very high. Also presented is temperature estimation from measurement of the decay times of meteor trails, which is compared with other temperature measurements from SATI and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere Ionosphere Mesosphere Energy and Dynamics (TIMED) satellite

Wind variations in the mesosphere and lower thermosphere near 60°S latitude during the 2019 Antarctic sudden stratospheric warming

Sudden Stratospheric Warmings (SSWs) could act as an important mediator in the vertical coupling of atmospheric regions and dramatic variations in the mesosphere and lower thermosphere (MLT) in response to SSWs have been documented. However, due to rare occurrences, SSWs in the Southern Hemisphere (SH) and their impacts on the MLT dynamics are not well understood. This study presents an analysis of MLT winds at ∼80‐98 km altitudes measured by meteor radars located at Tierra del Fuego (53.7°S, 67.7°W), King Edward Point (54.3°S, 36.5°W) and King Sejong Station (62.2°S, 58.8°W) near 60°S latitude during the Antarctic winter. Eastward zonal winds from these stations are observed to decrease significantly near the peak date of the 2019 Antarctic SSW, and both zonal and meridional winds in 2019 exhibit considerable differences to the mean winds averaged over other non‐SSW years. A quasi 6‐day oscillation is observed at all three radar locations, being consistent with the presence of the westward propagating zonal wave‐1 planetary wave. The vertical wavelength of this wave is estimated to be ∼55 km, and the enhancement of the wave amplitude during this SSW is noticeable. Evidence of the interaction between the 6‐day wave and the semidiurnal diurnal tide is provided, which suggests a possible mechanism for SSWs to impact the upper atmosphere. This study reports the large‐scale variations in winds in the MLT region at SH mid‐to‐high latitudes in a key dynamic but largely unexplored latitudinal band in response to the 2019 Antarctic SSW

Observations of the Polar Ionosphere by the Vertical Incidence Pulsed Ionospheric Radar at Jang Bogo Station, Antarctica

Korea Polar Research Institute (KOPRI) installed an ionospheric sounding radar system called Vertical Incidence Pulsed Ionospheric Radar (VIPIR) at Jang Bogo Station (JBS) in 2015 in order to routinely monitor the state of the ionosphere in the auroral oval and polar cap regions. Since 2017, after two-year test operation, it has been continuously operated to produce various ionospheric parameters. In this article, we will introduce the characteristics of the JBS-VIPIR observations and possible applications of the data for the study on the polar ionosphere. The JBS-VIPIR utilizes a log periodic transmit antenna that transmits 0.5–25 MHz radio waves, and a receiving array of 8 dipole antennas. It is operated in the Dynasonde B-mode pulse scheme and utilizes the 3-D inversion program, called NeXtYZ, for the data acquisition and processing, instead of the conventional 1-D inversion procedure as used in the most of digisonde observations. The JBS-VIPIR outputs include the height profiles of the electron density, ionospheric tilts, and ion drifts with a 2-minute temporal resolution in the bottomside ionosphere. With these observations, possible research applications will be briefly described in combination with other observations for the aurora, the neutral atmosphere and the magnetosphere simultaneously conducted at JBS

HL‐TWiM Empirical Model of High‐Latitude Upper Thermospheric Winds

We present an empirical model of thermospheric winds (High‐latitude Thermospheric Wind Model [HL‐TWiM]) that specifies F region high‐latitude horizontal neutral winds as a function of day of year, latitude, longitude, local time, and geomagnetic activity. HL‐TWiM represents the large‐scale neutral wind circulation, in geomagnetic coordinates, for the given input conditions. The model synthesizes the most extensive collection to date of historical high‐latitude wind measurements; it is based on statistical analyses of several decades of F region thermospheric wind measurements from 21 ground‐based stations (Fabry‐Perot Interferometers and Scanning Doppler Imaging Fabry‐Perot Interferometers) located at various northern and southern high latitudes and two space‐based instruments (UARS WINDII and GOCE). The geomagnetic latitude and local time dependences in HL‐TWiM are represented using vector spherical harmonics, day of year and longitude variations are represented using simple harmonic functions, and the geomagnetic activity dependence is represented using quadratic B splines. In this paper, we describe the HL‐TWiM formulation and fitting procedures, and we verify the model against the neutral wind databases used in its formulation. HL‐TWiM provides a necessary benchmark for validating new wind observations and tuning our physical understanding of complex wind behaviors. Results show stronger Universal Time variation in winds at southern than northern high latitudes. Model‐data intra‐annual comparisons in this study show semiannual oscillation‐like behavior of GOCE winds, rarely observed before in wind data.Key PointsWe developed a comprehensive empirical model of high‐latitude F region thermospheric winds (HL‐TWiM)Universal Time variations in high‐latitude winds are stronger in the Southern than Northern HemisphereHL‐TWiM provides a necessary benchmark for validating new high‐latitude wind observations and tuning first principal modelsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153588/1/jgra55363_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153588/2/jgra55363-sup-0001-Figure_SI-S01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153588/3/jgra55363.pd

Ground-based Observations of the Polar Region Space Environment

Jang Bogo Station (JBS), the second Korean Antarctic research station, was established in Terra Nova Bay, Antarctica (74.62°S 164.22°E) in February 2014 in order to expand the Korea Polar Research Institute (KOPRI) research capabilities. One of the main research areas at JBS is space environmental research. The goal of the research is to better understand the general characteristics of the polar region ionosphere and thermosphere and their responses to solar wind and the magnetosphere. Ground-based observations at JBS for upper atmospheric wind and temperature measurements using the Fabry-Perot Interferometer (FPI) began in March 2014. Ionospheric radar (VIPIR) measurements have been collected since 2015 to monitor the state of the polar ionosphere for electron density height profiles, horizontal density gradients, and ion drifts. To investigate the magnetosphere and geomagnetic field variations, a search-coil magnetometer and vector magnetometer were installed in 2017 and 2018, respectively. Since JBS is positioned in an ideal location for auroral observations, we installed an auroral all-sky imager with a color sensor in January 2018 to study substorms as well as auroras. In addition to these observations, we are also operating a proton auroral imager, airglow imager, global positioning system total electron content (GPS TEC)/scintillation monitor, and neutron monitor in collaboration with other institutes. In this article, we briefly introduce the observational activities performed at JBS and the preliminary results of these observations

Review of Environmental Monitoring by Means of Radio Waves in the Polar Regions: From Atmosphere to Geospace

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

Rethinking place-making: aligning placeness factors with perceived urban design qualities (PUDQs) to improve the built environment in historical district

Understanding the concept of place is critically important for urban design and place-making practice, and this research attempted to investigate the pathways by which perceived urban design qualities (PUDQs) influence placeness factors in the Chinese context. Twelve hypotheses were developed and combined in a structural equation model for validation. The Tanhualin historical district in Wuhan, China was selected for the analysis. As a result, place attachment was verified as a critical bridge factor that mediated the influence of PUDQs on place satisfaction. Among the five selected PUDQs, walkability and space quality were revealed as the most influential factors associated with place attachment and place satisfaction. Accessibility was actually indirectly beneficial to place-making via the mediation of walkability. Corresponding implications and strategies were discussed to maintain the sense of place for historic districts

Ground-based Observations for the Upper Atmosphere at King Sejong Station, Antarctica

Since the operation of the King Sejong Station (KSS) started in Antarctic Peninsula in 1989, there have been continuous efforts to perform the observation for the upper atmosphere. The observations during the initial period of the station include Fabry-Perot Interferometer (FPI) and Michelson Interferometer for the mesosphere and thermosphere, which are no longer in operation. In 2002, in collaboration with York University, Canada, the Spectral Airglow Temperature Imager (SATI) was installed to observe the temperature in the mesosphere and lower thermosphere (MLT) region and it has still been producing the mesopause temperature data until present. The observation was extended by installing the meteor radar in 2007 to observe the neutral winds and temperature in the MLT region during the day and night in collaboration with Chungnam National University. We also installed the all sky camera in 2008 to observe the wave structures in the MLT region. All these observations are utilized to study on the physical characteristics of the MLT region and also on the wave phenomena such as the tide and gravity wave in the upper atmosphere over KSS that is well known for the strong gravity wave activity. In this article, brief introductions for the currently operating instruments at KSS will be presented with their applications for the study of the upper atmosphere