ALBERT

Description: Rossby waves, present in both the Northern and Southern hemispheres, have a significant impact on severe weather patterns. The North Atlantic Oscillation (NAO) affects climate and weather in Europe and North America, and has been linked to extreme weather events (e.g., Hurrell et al., JC, 2003). Additionally, recurrent Rossby wave packets (RRWP) that possess strong zonal wavenumber 4 and 5 components have been associated with heatwaves in southeastern Australia (Mubashshir et al., WCD, 2022). Despite extensive research over the last century, fundamental questions regarding the nature of these high-impact Rossby waves remain unanswered. This study investigates their resonant characteristics, revealing that the NAO exhibits resonant behavior over a 35-day period, while the variability of the aforementioned RRWPs is linked to a quasi-mode (Zadra et al., JAS, 2002) resonating around 10 days. We will discuss the implications of these resonant behaviors in terms of teleconnections and forcing frequencies.

Description: La Réunion, an island in the Indian Ocean, hosts the shield volcano Piton de la Fournaise that recently tends to erupt up to twice per year. The seismic recordings show a great signal diversity including tectonic and volcano-tectonic (VT) earthquakes, eruption tremor, (very) long period events along with a variety of rockfalls.With the aim of testing the rotational sensor performance in comparison with a conventional seismic array, one rotational sensor and an array of seven seismometers were installed within the Enclos-Fouqué caldera. A permanent station of the monitoring network of the Observatoire Volcanologique du Piton de la Fournaise (OVPF) is included in the temporal network. Recordings of (volcano-) seismic signals, detected by the OVPF’s network, are compared to those of the rotational sensor and the array.We calculate the signal-to-noise ratio (SNR), derive the rotation rate using three array stations for array derived rotation (ADR) and compare the backazimuth (BAZ) results using different approaches. The rotational sensor and the array BAZ are furthermore compared to the OVPF’s localizations.Whereas the array BAZ for summit VT events and the rockfall agree with the locations of the OVPF network, the rotational sensor BAZ indicates possible agreement for the rockfall event. Further BAZ results from the rotational sensor are interpreted to be affected by site inhomogeneity. The array stations show higher SNR results than the rotational sensor. As burying of the instruments on site was not possible, the sensors are affected by wind, increasing the noise floor and decreasing the instruments’ sensitivity.

Description: During the second half of 2019, the Earth’s magnetosphere was impacted by a sequence of Corotating Interaction Regions (CIRs) during four consecutive solar rotations. Based on the solar wind properties, the CIRs can be divided in four groups, with the 3rd group, which arrived on August-September 2019, resulting in significant multi-MeV electron enhancements, up to ultra-relativistic energies of 9.9 MeV. Each CIR group has a different effect on the outer radiation belt electron populations; we investigate them by exploiting combined measurements from the Van Allen Probes, THEMIS, and Arase satellites. We produce Phase Space Density (PSD) radial profiles and inspect their dependence on the values of the first and second adiabatic invariants (μ,K), ranging from seed to ultra-relativistic electrons and from near-equatorial to off equatorial mirroring populations, respectively. Focusing on the 3rd CIR group, and in order to assess the relative contribution of radial diffusion and gyro-resonant acceleration, we perform numerical simulations of the radiation belt environment, combining several relevant models: EMERALD (NKUA), GEO model (NKUA), Salammbô (ONERA), VLF model (IAP), Plasmaspheric model (BIRA-IASB), FARWEST (ONERA). We further compare the temporal evolution of the simulated electron PSD with the above observations. This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870437 for the SafeSpace project. ______ Additional co-authors: Viviane Pierrard (5), Edith Botek (5), Benjamin Grison (3), Ivana Kolmasova (3), David Pisa (3), Takefumi Mitani (10), Ayako Matsuoka (11), Iku Shinohara (10), Takeshi Takashima (10), Tomoaki Hori (6) (10) ISAS, JAXA, Japan, (11) Kyoto University, Japan