Team title: Precipitation of Energetic Particles from Magnetosphere and Their Effects on the Atmosphere
Team ID: G3-06
Team Leads:
Dedong Wang (GFZ Potsdam, Germany) dedong AT gfz-potsdam.dea
Chao Yue (Peking University, China) yuechao AT pku.edu.cn
Alexander Drozdov (UCLA, USA) adrozdov AT ucla.edu
Keywords (impact): Climate
Keywords (activity type): Understanding, Modeling, Data Utilization, Assessment
Introduction:
Energetic particles in the magnetosphere can precipitate into the atmosphere due to wave-particle interactions or other mechanisms, for example, field line curvature scattering. The interaction between the precipitated energetic particles and neutral particles in the atmosphere release photons, and form auroras. Energetic elaectrons from the aurora and the magnetosphere are known sources of nitric oxide (NOx) in the auroral region of the upper mesosphere and lower thermosphere (60 - 140 km). During polar winter, auroral nitric oxide is transported down to the mid-stratosphere (30 - 45 km), with values varying with geomagnetic activity and the dynamical state of the atmosphere. Here, nitric oxides destroy ozone very efficiently; as ozone is one of the key species of radiative heating and cooling in the stratosphere, downward transport of auroral NOx into the stratosphere leads to changes in temperatures and wind fields that can propagate throughout the atmosphere and even affect tropospheric weather systems. Geomagnetic activity is therefore now recommended as part of the solar forcing of the climate system for the CMIP-6 (IPCC) model experiments for the first time. However, the atmospheric ionization rates needed to drive these model experiments are based empirically on fluxes of precipitating electrons which carry a large uncertainty, and recent studies suggest that there may be serious problems with the accuracy of these data. Additionally, numerical modeling and data analysis of electrons in the ~keV energy range suggest the presence of a missing loss mechanism that could drive additional precipitation, which is not currently accounted for in existing models. In this team, we will study the mechanisms leading to the precipitation of energetic particles and the consequence effect of the precipitation using methods of satellite observation, theoretical analysis and modelling.
Objectives:
Our team will aim to answer the following scientific questions:
Q1: What is the missing loss mechanism of ring current electrons besides the diffusive scattering by whistler-mode waves?
Q2: What is the energy of electrons that are significantly influenced by EMIC waves? A related question is why the EMIC wave activity in the magnetosphere is not always accompanied by the energetic particle precipitation at the conjugate point on LEO orbit.
Q3: Which energy range of precipitating electrons has the largest impact on the chemistry and dynamics of the middle atmosphere?
To address these questions, spacecraft data analysis, numerical simulations and theoretical studies will be carried out synergistically. Our team will take full advantage of conjugate observations from space (e.g., MMS, THEMIS, Van Allen Probes, Arase, Cluster, NOAA POES, ASI, ELFIN, DMSP, Lomonosov) and ground (e.g., THEMIS ground stations, Chinese Arctic Yellow River Station, SuperDARN, SuperMag) in studying precipitation of particles, related auroral phenomenon, combined with the expertise of team members in wave research, kinetic simulations, MHD and diffusion simulations to conduct the research on the scattering mechanisms related to precipitation, including the effects of nonlinear particle scattering. We will also carry out theoretical analyses using quasilinear and nonlinear paradigms to understand plasma waves and their interactions with charged particles.
Action Topics:
- Understand and quantify trapped particles transport,
- Acceleration and loss,
- Assessment of quasi-linear and diffusive approximations for wave-particle interactions (from VLF to ULF frequencies) ,
- Advance modeling capability of the coupled geospace system (including ring current, plasmasphere, plasma sheet, ionosphere and thermosphere)
Cluster with overlapping topics:
G2A: Atmosphere variability, G2B: Ionosphere variability, G3: Near-end radiation and plasma environment