A transatlantic scientific balloon flight (TRANSAT) was conducted in June 2024. The TRANSAT balloon floated in the stratosphere at approximately 40 km altitude between Sweden and Canada for about 4 days. An optical imager was installed on the TRANSAT balloon to study noctilucent cloud (NLC). Nearly continuous observations of NLC were obtained during the entire flight. A complex NLC structures exhibiting different motions were found to result from wind rotation with altitude between 80 and 94 km.

We studied gravity waves using a unique lidar that measures both temperature and wind. This is the first long-term study of how their energies vary with height and season in the middle atmosphere near the Arctic. Waves were stronger and varied more in winter, while in summer slow waves tied to Earth's rotation dominated. We also observed new patterns in how energy is shared between both energy types and height-dependent changes in wave behaviour. These results refine our view of such waves.

Noctilucent clouds (NLCs) are silvery clouds that can be viewed during twilight and indicate atmospheric conditions like temperature and water vapor in the upper mesosphere. High-resolution measurements from a remote sensing laser instrument provide NLC height, brightness, and occurrence rate since 2017. Most observations occur in the morning hours, likely caused by strong tidal winds, and NLC ice particles are thus transported from elsewhere to the observing location in the Southern Hemisphere.

This article describes the current status of a lidar installed at ALOMAR in northern Norway. It has investigated the Arctic middle atmosphere on a climatological basis for 30 years. We discuss major upgrades of the system implemented during recent years, including methods for reliable remote operation of this complex lidar. We also show examples that illustrate the performance of the lidar during measurements at different altitude ranges and timescales.

Imagine you want to determine how quickly the pitch of a passing ambulance’s siren changes. If the vehicle is traveling slowly, the pitch changes only slightly, but if it is traveling fast, the pitch also changes rapidly. In a similar way, the wind in the middle atmosphere modulates the wavelength of atmospheric gravity waves. We have investigated the question of how strong the maximum wind may be so that the change in wavelength can still be determined with the help of wavelet transformation.