Frequency spectra of wind fluctuations in the mesosphere

Frequency spectra of zonal wind fluctuations and vertical flux of zonal momentum in the mesosphere. The mesospheric winds can be observed only during the daytime when the solar radiation ionizes the mesosphere. Due to continuous solar radiation in summer in the polar region, continuous observation over 50 days is possible. Therefore, the PANSY radar could successfully obtained the spectra over a wide range of frequency first for the mesosphere. It was discovered that low-frequency gravity waves are responsible for momentum transport, rather than theoretically expected high-frequency ones. Different color shows results for different years.

cite: Sato et al., JGR, 2017

Broadband spectral characteristics of atmospheric gravity waves

Annual mean of frequency spectra of zonal wind fluctuations and vertical flux of zonal momentum at each height in the troposphere and stratosphere observed by the PANSY radar. Unlike the mesosphere, continuous observation is possible anytime in the troposphere and stratosphere. In the stratosphere (above the tropopause at ~10km), a distinct peak is seen in the inertial period (~13 h corresponding to a half period of Foucault‘s pendulum shown by a red dashed line). This peak is accompanied by negative momentum flux.

cite: Minamihara et al., JGR, 2018

Energy Dissipation Rate Estimated From the Radar Spectral Width

Turbulent kinetic energy dissipation rates were estimated from spectral widths of the scattering echoes utilizing a newly developed algorithm for removing spectral broadening due to non‐turublent processes. The PANSY radar gave the first estimate on the turbulent parameters in the troposphere, lower stratosphere, and mesosphere in the Antarctic.

cite: Kohma et al., JGR, 2020

First Incoherent Scatter Measurement by the PANSY radar

Fig.1: First height profile of the electron density over the Antarctic region measured by the PANSY radar.
Fig.2: Time series of height profiles. The lowermost panel shows FAI occurrence. Red boxes shows an example of results.

In 2015, the PANSY radar conducted the first incoherent scatter measurement in the Antarctic region (Fig. 1). A novel signal processing technique was later developed in 2017 to cope with the interference from the irregularity of the electron density along the geomagnetic field line called Field Aligned Irregularities or FAIs (Fig. 2).

cite: Hashimoto et al., J. Atmos. Oceanic Technol., 2019