A Scenario for Origin of Global 4 mHz Oscillations in Solar Corona

We establish a spherically symmetric model of solar atmosphere, which consists of the whole chromosphere and low corona below the $1.25$ solar radius. It is a hydrodynamic model with heating in the chromosphere through an artificial energy flux. We performed a series of simulations with our model and found oscillations with a peak frequency of $\sim$4 $\mathrm{m}\mathrm{H}\mathrm{z}$ in the power spectrum. We confirmed that this resulted from the $p$-mode excited in the transition region and amplified in a resonant cavity situated in the height range $\sim$$4\times {10}^3$–$2\times {10}^4$ km. This result is consistent with global observations of Alfvénic waves in corona and can naturally explain the observational ubiquity of $4\mathrm{m}\mathrm{H}\mathrm{z}$ without the difficulty of the $p$-mode passing through the acoustic-damping chromosphere. We also confirmed that acoustic shock waves alone cannot heat the corona to the observed temperature, and found mass upflows in the height range $\sim$$7\times {10}^3$–$7\times {10}^4$ km in our model, which pumped the dense and cool plasma into the corona and might be the mass supplier for solar prominences.