Variational Estimation of the Large-scale Time-dependent Meridional Circulation in the Sun: Proofs of Concept with a Solar Mean Field Dynamo Model - Archive ouverte HAL Access content directly
Journal Articles The Astrophysical Journal Year : 2017

Variational Estimation of the Large-scale Time-dependent Meridional Circulation in the Sun: Proofs of Concept with a Solar Mean Field Dynamo Model

(1, 2) , (2) , (3) , (2, 4) , (5) , (1)
1
2
3
4
5

Abstract

We present in this work the development of a solar data assimilation method based on an axisym-metric mean field dynamo model and magnetic surface data, our mid-term goal is to predict the solar quasi cyclic activity. Here we focus on the ability of our algorithm to constrain the deep meridional circulation of the Sun based on solar magnetic observations. To that end, we develop a variational data assimilation technique. Within a given assimilation window, the assimilation procedure minimizes the differences between data and the forecast from the model, by finding an optimal meridional circulation in the convection zone, and an optimal initial magnetic field, via a quasi-Newton algorithm. We demonstrate the capability of the technique to estimate the meridional flow by a closed-loop experiment involving 40 years of synthetic, solar-like data. By assimilating the synthetic magnetic proxies annually, we are able to reconstruct a (stochastic) time-varying meridional circulation which is also slightly equatorially asymmetric. We show that the method is robust in estimating a flow whose level of fluctuation can reach 30% about the average, and that the horizon of predictive capability of the method is of the order of 1 cycle length.
Fichier principal
Vignette du fichier
HUNG.pdf (10.94 Mo) Télécharger le fichier
Origin : Files produced by the author(s)
Loading...

Dates and versions

cea-02127665 , version 1 (13-05-2019)

Identifiers

Cite

Ching Pui Hung, Allan Sacha Brun, Alexandre Fournier, Laurène Jouve, Olivier Talagrand, et al.. Variational Estimation of the Large-scale Time-dependent Meridional Circulation in the Sun: Proofs of Concept with a Solar Mean Field Dynamo Model. The Astrophysical Journal, 2017, 849 (2), pp.160. ⟨10.3847/1538-4357/aa91d1⟩. ⟨cea-02127665⟩
284 View
103 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More