All Figures

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig1.ps}\end{figure}$ Figure 1: $\beta ={2 \mu _0 p}/{B_0^2}$ (solid line), $\beta _{\perp }={2 \mu _0 p}/{B_\perp ^2}$ (dotted line) and the amplitude of the transverse Alfvén wave in terms of the background magnetic field $\eta = B_\perp /B_0$ (dashed line) versus z/H for Run 1a.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig2.ps}\end{figure}$ Figure 2: a) Profile of Alfvén speed normalised to the sound speed in a stratified atmosphere versus z/H for Runs 1a-c (solid line) and Runs 2a-c (dotted line). b) The ratios of the wave length to the Alfvén speed scale height versus z/H for Runs 1a-c (solid line) and Runs 2a-c (dotted line).
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In the text

$\begin{figure} \par\includegraphics[width=12cm,clip]{1071fig3.ps}\end{figure}$ Figure 3: Low amplitude magnetohydrodynamic waves propagating through a stratified medium (Run 1a). $\Delta \rho / \rho_0=\frac{ \rho - \rho_0}{\rho_0}$ versus z/H at a) t/P= 9.4 and b) t/P= 14.6. c) and d) B_x/B_z (solid line) and $v_x/v_{\rm A0}$ (dotted line) versus z/H at the same times.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig4.ps}\end{figure}$ Figure 4: High amplitude magnetohydrodynamic waves in a stratified medium (Run 1c) at t/P= 14.6 plotted as functions of z/H. a) $\Delta \rho / \rho _0$ (solid line) and $v_z/c_{\rm s}$ (dotted line), b) B_x/B_z and $v_x/v_{\rm A0}$ , and c) the Poynting flux S_z/S₀ for Run 1c (solid line) compared to that of the low amplitude Run 1a (dotted line) at the same time. S₀ is the Poynting flux at z=0.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig5.ps}\end{figure}$ Figure 5: $\Delta \rho / \rho _0$ versus z/H for Run 1c. The solid line represents $\Delta \rho / \rho _0$ at t₁=6.25P, the dotted and the dashed lines represent $\Delta \rho / \rho _0$ for the M and H models respectively, at t₂=10.4P, t₃=12.5P and t₄=14.6P.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig6.ps}\end{figure}$ Figure 6: The two Elsasser vectors for Run 1a at t/P=17.7 (x-components: solid lines; y-components: dotted lines). a) ${\vec Z}_+/v_{A0}$ versus z/H, and $\pm \frac{1}{\eta}$ (dashed lines). b ${\vec Z}_-/v_{A0}$ versus z/H. Note the difference in scale between the two panels.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig7.ps}\end{figure}$ Figure 7: The two Elsasser vectors for Run 1c at t/P=17.5(x-components: solid lines; y-components: dotted lines). a) ${\vec Z}_+/v_{\rm A0}$ versus z/H (solid line), and $\pm \frac{1}{\eta}$ (dashed line). b) ${\vec Z}_-/v_{\rm A0}$ versus z/H (solid line) and $\Delta \rho / \rho _0$ (dashed line) at the same time. Note the difference in scale between the two panels.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{1071fig8.ps}\end{figure}$ Figure 8: The time average of the Poynting flux ( top left) and the integrated work the Alfvén wave performs on the medium via the Lorentz force ( bottom left) during one period of the Alfvén wave. Solid lines are for the high amplitude Run 1c and dashed lines for the low amplitude Run 1a. The curves have been scaled by the Poynting flux at z = 0. The vertical lines indicate the positions of the Alfvén wave fronts at the start of the averaging at t/P = 13.6.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig1.ps}\end{figure}$	Figure 1: $\beta ={2 \mu _0 p}/{B_0^2}$ (solid line), $\beta _{\perp }={2 \mu _0 p}/{B_\perp ^2}$ (dotted line) and the amplitude of the transverse Alfvén wave in terms of the background magnetic field $\eta = B_\perp /B_0$ (dashed line) versus z/H for Run 1a.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig2.ps}\end{figure}$	Figure 2: a) Profile of Alfvén speed normalised to the sound speed in a stratified atmosphere versus z/H for Runs 1a-c (solid line) and Runs 2a-c (dotted line). b) The ratios of the wave length to the Alfvén speed scale height versus z/H for Runs 1a-c (solid line) and Runs 2a-c (dotted line).
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$\begin{figure} \par\includegraphics[width=12cm,clip]{1071fig3.ps}\end{figure}$	Figure 3: Low amplitude magnetohydrodynamic waves propagating through a stratified medium (Run 1a). $\Delta \rho / \rho_0=\frac{ \rho - \rho_0}{\rho_0}$ versus z/H at a) t/P= 9.4 and b) t/P= 14.6. c) and d) B_x/B_z (solid line) and $v_x/v_{\rm A0}$ (dotted line) versus z/H at the same times.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig5.ps}\end{figure}$	Figure 5: $\Delta \rho / \rho _0$ versus z/H for Run 1c. The solid line represents $\Delta \rho / \rho _0$ at t₁=6.25P, the dotted and the dashed lines represent $\Delta \rho / \rho _0$ for the M and H models respectively, at t₂=10.4P, t₃=12.5P and t₄=14.6P.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig6.ps}\end{figure}$	Figure 6: The two Elsasser vectors for Run 1a at t/P=17.7 (x-components: solid lines; y-components: dotted lines). a) ${\vec Z}_+/v_{A0}$ versus z/H, and $\pm \frac{1}{\eta}$ (dashed lines). b ${\vec Z}_-/v_{A0}$ versus z/H. Note the difference in scale between the two panels.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1071fig7.ps}\end{figure}$	Figure 7: The two Elsasser vectors for Run 1c at t/P=17.5(x-components: solid lines; y-components: dotted lines). a) ${\vec Z}_+/v_{\rm A0}$ versus z/H (solid line), and $\pm \frac{1}{\eta}$ (dashed line). b) ${\vec Z}_-/v_{\rm A0}$ versus z/H (solid line) and $\Delta \rho / \rho _0$ (dashed line) at the same time. Note the difference in scale between the two panels.
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