• Arctic tidal characteristics at Eureka (80 degrees N, 86 degrees W) and Svalbard (78 degrees N, 16 degrees E) for 2006/07 : seasonal and longitudinal variations, migrating and non-migrating tides 

      Hall, Chris; Manson, Alan; Meek, Chris; Chshyolkova, Tatyana; Xu, X.; Aso, Takehiko; Drummond, J. R.; Hocking, Wayne; Jacobi, Ch.; Tsutsumi, Masaki; Ward, W. (Journal article; Tidsskriftartikkel; Peer reviewed, 2009)
    • Atmospheric tomography using the Nordic Meteor Radar Cluster and Chilean Observation Network de Meteor Radars: Network details and 3D-Var retrieval 

      Stober, Gunter; Kozlovsky, A.; Liu, Alan; Qiao, Zishun; Tsutsumi, Masaki; Hall, Chris; Nozawa, Satonori; Lester, Mark; Belova, Evgenia; Kero, Johan; Espy, Patrick Joseph; Hibbins, Robert E.; Mitchell, N. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-08)
      Ground-based remote sensing of atmospheric parameters is often limited to single station observations by vertical profiles at a certain geographic location. This is a limiting factor for investigating gravity wave dynamics as the spatial information is often missing, e.g., horizontal wavelength, propagation direction or intrinsic frequency. In this study, we present a new retrieval algorithm for ...
    • A case study of gravity wave dissipation in the polar MLT region using sodium LIDAR and radar data 

      Takahashi, Toru; Nozawa, Satonori; Tsutsumi, Masaki; Hall, Chris; Suzuki, Shin; Tsuda, Takuo T.; Kawahara, Takuya D.; Saito, Norihito; Oyama, Shinichiro; Wada, Satoshi; Kawabata, Tetsuya; Fujiwara, Hitoshi; Brekke, Asgeir; Manson, Alan; Meek, Chris; Fujii, Ryoichi (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • A case study on generation mechanisms of a sporadic sodium layer above Tromsø (69.6° N) during a night of high auroral activity 

      Takahashi, Toru; Nozawa, Satonaori; Tsuda, Takuo T.; Ogawa, Yasunobu; Saito, Norihito; Hidemori, Takehiro; Kawahara, Takuya D.; Hall, Chris; Fujiwara, Hitoshi; Matuura, Nobuo; Brekke, Asgeir; Tsutsumi, Masaki; Wada, Satoshi; Kawabata, Tetsuya; Oyama, Shinichiro; Fujii, Ryoichi (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-05)
      We have quantitatively evaluated generation mechanisms of a sporadic sodium layer (SSL) based on observational data obtained by multiple instruments at a high-latitude station: Ramfjordmoen, Tromsø, Norway (69.6° N, 19.2° E). The sodium lidar observed an SSL at 21:18 UT on 22 January 2012. The SSL was observed for 18 min, with a maximum sodium density of about 1.9 × 1010 m−3 at 93 km with a 1.1 km ...
    • Characteristics of Arctic tides at CANDAC-PEARL (80 degrees N, 86 degrees W) and Svalbard (78 degrees N, 16 degrees E) for 2006-2009 : radar observations and comparisons with the model CMAM-DAS 

      Manson, Alan; Meek, Chris; Xu, X.; Aso, Takehiko; Drummond, J. R.; Hall, Chris; Hocking, W. K.; Tsutsumi, Masaki; Ward, W. E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      Operation of a Meteor Radar (MWR) at Eureka, Ellesmere Island (80° N, 86° W) began in February 2006: this is the location of the Polar Environmental and Atmospheric Research Laboratory (PEARL), operated by the "Canadian Network for the Detection of Atmospheric Change" (CANDAC). The first 36 months of tidal wind data (82–97 km) are here combined with contemporaneous tides from the Meteor Radar (MWR) ...
    • Climatology of the mesopause relative density using a global distribution of meteor radars 

      Yi, Wen; Xue, Xianghui; Reid, Iain; Murphy, Damian J.; Hall, Chris; Tsutsumi, Masaki; Ning, Baiqi; Li, Guozhu; Vincent, Robert; Chen, Jinsong; Wu, Jianfei; Chen, Tingdi; Dou, Xiankang (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-06)
      The existing distribution of meteor radars located from high- to low-latitude regions provides a favorable temporal and spatial coverage for investigating the climatology of the global mesopause density. In this study, we report the climatology of the mesopause relative density estimated using multiyear observations from nine meteor radars, namely, the Davis Station (68.6∘ S, 77.9∘ E), Svalbard ...
    • First observations of Polar Mesospheric Echoes at both 31MHz and 53.5MHz over Svalbard (78.2°N 15.1°E) 

      Hall, Chris; Adami, Chris; Tsutsumi, Masaki (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-09)
      During summer 2020, observations of the mesosphere using a 53.5 MHz radar on Svalbard, at 78.2°N 15.1°E, revealed the well-known Polar Mesospheric Summer Echoes (PMSE). At the same time, a co-located meteor detection radar, operating at 31 MHz detected corresponding echoes very distinct from those associated with meteor trails. Comparing as many days as possible during 2020, incontestable evidence ...
    • Four dimensional quantification of Kelvin-Helmholtz instabilities in the polar summer mesosphere using volumetric radar imaging 

      Chau, Jorge L.; Urco, Miguel; Avsarkisov, Victor; Vierinen, Juha; Latteck, Ralph; Hall, Chris; Tsutsumi, Masaki (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-13)
      We present and characterize in time and three spatial dimensions a Kelvin‐Helmholtz Instability (KHI) event from polar mesospheric summer echoes (PMSE) observed with the Middle Atmosphere Alomar Radar System. We use a newly developed radar imaging mode, which observed PMSE intensity and line of sight velocity with high temporal and angular resolution. The identified KHI event occurs in a narrow layer ...
    • Identifying gravity waves launched by the Hunga Tonga-Hunga Ha′apai volcanic eruption in mesosphere/lower-Thermosphere winds derived from CONDOR and the Nordic Meteor Radar Cluster 

      Stober, Gunter; Liu, Alan; Kozlovsky, Alexander; Qiao, Zishun; Krochin, Witali; Shi, Guochun; Kero, Johan; Tsutsumi, Masaki; Gulbrandsen, Njål; Nozawa, Satonori; Lester, Mark; Baumgarten, Kathrin; Belova, Evgenia; Mitchell, Nicholas (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-18)
      The Hunga Tonga–Hunga Ha'apai volcano eruption was a unique event that caused many atmospheric phenomena around the globe. In this study, we investigate the atmospheric gravity waves in the mesosphere/lowerthermosphere (MLT) launched by the volcanic explosion in the Pacific, leveraging multistatic meteor radar observations from the Chilean Observation Network De Meteor Radars (CONDOR) and the ...
    • Impact of sudden stratospheric warmings on the neutral density, temperature and wind in the MLT region 

      Zhou, Baozhu; Yi, Wen; Xue, Xianghui; Ye, Hailun; Zeng, Jie; Li, Guozhu; Tsutsumi, Masaki; Gulbrandsen, Njål; Chen, Tingdi; Dou, Xiankang (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-04)
      In this study, the neutral density and horizontal wind observed by the four meteor radars, as well as the temperature measured by the Microwave Limb Sounder (MLS) onboard the Aura satellite are used to examine the response of neutral density, wind, and temperature in the MLT region to the stratospheric sudden warmings (SSWs) during 2005 to 2021 in the Northern Hemisphere. The four meteor radars ...
    • Inferring neutral winds in the ionospheric transition region from atmospheric-gravity-wave traveling-ionospheric-disturbance (AGW-TID) observations with the EISCAT VHF radar and the Nordic Meteor Radar Cluster 

      Günzkofer, Florian; Pokhotelov, Dimitry; Stober, Gunter; Mann, Ingrid Brigitte; Vadas, Sharon L.; Becker, Erich; Tjulin, Anders; Kozlovsky, Alexander; Tsutsumi, Masaki; Gulbrandsen, Njål; Nozawa, Satonori; Lester, Mark; Belova, Evgenia; Kero, Johan; Mitchell, Nicholas J.; Borries, Claudia (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-18)
      Atmospheric gravity waves and traveling ionospheric disturbances can be observed in the neutral atmosphere and the ionosphere at a wide range of spatial and temporal scales. Especially at medium scales, these oscillations are often not resolved in general circulation models and are parameterized. We show that ionospheric disturbances forced by upward-propagating atmospheric gravity waves can be ...
    • Long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the Northern Hemisphere 

      Jaen, Juliana; Renkwitz, Toralf; Chau, Jorge L.; He, Maosheng; Hoffmann, Peter; Yamazaki, Yosuke; Jacobi, Christoph; Tsutsumi, Masaki; Matthias, Vivien; Hall, Chris (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-20)
      Specular meteor radars (SMRs) and partial reflection radars (PRRs) have been observing mesospheric winds for more than a solar cycle over Germany (∼ 54◦ N) and northern Norway (∼ 69◦ N). This work investigates the mesospheric mean zonal wind and the zonal mean geostrophic zonal wind from the Microwave Limb Sounder (MLS) over these two regions between 2004 and 2020. Our study focuses on the ...
    • Long-Term studies of the summer wind in the mesosphere and lower thermosphere at middle and high latitudes over Europe 

      Jaen, Juliana; Renkwitz, Toralf; Liu, Huixin; Jacobi, Christoph; Wing, Robin; KuchaÅ™, Aleš; Tsutsumi, Masaki; Gulbrandsen, Njål; Chau, Jorge L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-01)
      Continuous wind measurements using partial-reflection radars and specular meteor radars have been carried out for nearly 2 decades (2004–2022) at middle and high latitudes over Germany (∼ 54<sup>∘</sup> N) and northern Norway (∼ 69<sup>∘</sup> N), respectively. They provide crucial data for understanding the long-term behavior of winds in the mesosphere and lower thermosphere. Our investigation ...
    • Meteor radar observations of polar mesospheric summer echoes over Svalbard 

      Younger, Joel P.; Reid, Iain M.; Adami, Chris L.; Hall, Chris M.; Tsutsumi, Masaki (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-21)
      A 31 MHz meteor radar located in Svalbard was used to observe polar mesospheric echoes (PMSEs) during summer 2020. Data from 19 July were selected for detailed analysis, with a focus on extracting additional information to characterize the atmosphere in the PMSE region. The use of an all-sky meteor radar adds an additional use to data collected for meteor observations and enables the detection ...
    • Meteor radar vertical wind observation biases and mathematical debiasing strategies including the 3DVAR+DIV algorithm 

      Stober, Gunter; Liu, Alan; Kozlovsky, Alexander; Qiao, Zishun; Kuchar, Ales; Jacobi, Christoph; Meek, Chris; Janches, Diego; Liu, Guiping; Tsutsumi, Masaki; Gulbrandsen, Njål; Nozawa, Satonori; Lester, Mark; Belova, Evgenia; Kero, Johan; Mitchell, Nicholas (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-13)
      Meteor radars have become widely used instruments to study atmospheric dynamics, particularly in the 70 to 110 km altitude region. These systems have been proven to provide reliable and continuous measurements of horizontal winds in the mesosphere and lower thermosphere. Recently, there have been many attempts to utilize specular and/or transverse scatter meteor measurements to estimate vertical ...
    • Neutral atmosphere temperature trends and variability at 90 km, 70°N, 19°E, 2003-2014 

      Holmen, Silje Eriksen; Hall, Chris; Tsutsumi, Masaki (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-06-27)
      Neutral temperatures at 90 km height above Tromsø, Norway, have been determined using ambipolar diffusion coefficients calculated from meteor echo fading times using the Nippon/Norway Tromsø Meteor Radar (NTMR). Daily temperature averages have been calculated from November 2003 to October 2014 and calibrated against temperature measurements from the Microwave Limb Sounder (MLS) on board Aura. ...
    • Neutral temperatures at 90 km altitude over Svalbard (78°N 16°E), 2002-2019, derived from meteor radar observations 

      Hall, Chris; Tsutsumi, Masaki (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06)
      Neutral air temperatures at 90 km altitude over Svalbard (78°N, 16°E) for the period 2002 to 2019 inclusive have been estimated from observations by the Nippon/Norway Svalbard Meteor Radar (NSMR). The data are presented per se and we shall not attempt to identify contributions from extra-terrestrial or anthropogenic driving. On the other hand, comparison with the corresponding period of solar UV ...
    • Polar vortex evolution during Northern Hemispheric winter 2004/05 

      Hall, Chris; Chshyolkova, Tatyana; Manson, Alan; Meek, Chris; Aso, Takehiko; Avery, S. K.; Hocking, W. K.; Igarashi, K.; Jacobi, C.; Makarov, N.; Mitchell, Nick; Murayama, Y.; Singer, Werner; Thorsen, D.; Tsutsumi, Masaki (Journal article; Tidsskriftartikkel; Peer reviewed, 2007)
    • Relationship between variability of the semidiurnal tide in the Northern Hemisphere mesosphere and quasi-stationary planetary waves throughout the global middle atmosphere 

      Hall, Chris; Xu, X; Manson, Alan; Meek, Chris; Chshyolkova, Tatyana; Drummond, J. R.; Jacobi, Ch.; Riggin, D.; Hibbins, R.E.; Tsutsumi, Masaki; Hocking, W. K.; Ward, W. (Journal article; Tidsskriftartikkel; Peer reviewed, 2009)
    • Zonal Wave Number Diagnosis of Rossby Wave-Like Oscillations Using Paired Ground-Based Radars 

      He, Maosheng; Yamazaki, Yosuke; Hoffmann, Peter; Hall, Chris; Tsutsumi, Masaki; Li, Guozhu; Chau, Jorge L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-03)
      Free traveling Rossby wave normal modes (RNMs) are often investigated through large-scale space-time spectral analyses, which therefore is subject to observational availability, especially in the mesosphere. Ground-based mesospheric observations were broadly used to identify RNMs mostly according to the periods of RNMs without resolving their horizontal scales. The current study diagnoses zonal ...