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Updated: Jul 4, 2026
11:34
Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
Chromospheric dynamics and turbulence regulate the solar FIP effect.
Andy S H To1, J Martin Laming2, Jeffrey Reep3
1European Space Agency, ESTEC , Noordwijk, The Netherlands.
Summary
Solar coronal abundance variations are explained by the ponderomotive force model, even under dynamic chromospheric conditions. Turbulence suppresses fractionation, impacting elemental composition during solar flares and nanoflares.
Area of Science:
- Solar physics
- Plasma astrophysics
- Stellar atmospheric science
Background:
- Elemental abundance variations in the solar corona, known as first ionization potential (FIP) bias, are key indicators of chromospheric processes.
- The ponderomotive force model, linked to Alfvén wave propagation, has explained these abundance patterns in solar features.
- Previous models assumed a static chromosphere, neglecting the impact of dynamic processes.
Purpose of the Study:
- To investigate the influence of chromospheric dynamics on FIP bias using a novel integrated modeling approach.
- To assess the consistency of the ponderomotive force model under varying chromospheric conditions, including nanoflare events.
- To explore how acoustic flux and turbulence affect elemental fractionation in the solar atmosphere.
Main Methods:
- Combined hydrodynamic simulations (HYDRAD) with ponderomotive force calculations using the new open-source code, FIPpy.
- Compared model predictions for a static VAL-C chromosphere versus a dynamic, heated chromosphere after nanoflare-like events.
- Analyzed the impact of varying acoustic flux and turbulence levels on FIP bias and elemental fractionation.
Main Results:
- The ponderomotive force model remains consistent with observed FIP bias even in dynamic chromospheric conditions.
- Changes in acoustic flux and turbulence significantly alter fractionation behavior.
- Below an acoustic wave flux of ~5×10^6 erg cm^-2 s^-1, thermal velocities dominate, leading to unusual FIP bias patterns (e.g., Fe > Ca).
- Chromospheric turbulence suppresses FIP bias, and increased turbulence during flares may explain observed abundance variations.
Conclusions:
- Coronal abundances reflect a balance between ponderomotive acceleration and turbulent velocity.
- The ponderomotive force model is robust under dynamic solar atmospheric conditions.
- Turbulence plays a critical role in modulating FIP bias, especially during energetic events like flares.
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