All Figures

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{4407_f2.eps}\hspace*{6mm} \includegraphics[width=7.5cm,clip]{4407_f3.eps} \end{figure}$ Figure 2: Time series of the average values of the CDS and SUMER radiances, together with linear fits (solid lines) and the two extreme curves obtained by adding or subtracting the standard uncertainties to the fit coefficients (dashed lines). The uncertainties are discussed in the text.

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{4407_f4.eps}\hspace*{4mm} \includegraphics[width=7.6cm,clip]{4407_f5.eps} \end{figure}$ Figure 3: Time series of the areal fractions of CDS radiance within the intervals given above each panel. Higher flux values correspond to intranetwork, quiet network, enhanced network, active network.

In the text

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{4407_f6.eps} \end{figure}$ Figure 4: The mean (upper frame) and standard deviation (square root of the variance, lower frame) of the unsigned magnetic flux density values in the MDI images of the full solar disk ( $\mu > 0.6$ , stars) and of the quiet-Sun areas overlapping with the CDS scans (diamonds) as a function of time.

In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{4407_f7.eps}\hspace*{6mm} \includegraphics[width=7.7cm,clip]{4407_f8.eps} \end{figure}$ Figure 5: Time series of the areal fractions of different activity ranges in the MDI images for the full disk and a quiet area of 120 $^{\prime \prime }$ $\times$ 400 $^{\prime \prime }$ .

In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{4407_f9.eps}\hspace*{6mm} \includegraphics[width=7.7cm,clip]{4407_f10.eps} \end{figure}$ Figure 6: Time series of the summed (total) flux (left) present in fields lying in the ranges 20 G to 40 G, 40 G to 60 G, and above 60 G. The right panels show the relative contributions of the flux in these flux-density ranges to the total flux (above a 20 G noise level). For this plot, all MDI pixels with $B/\mu$ -values below 20 G have been omitted.

In the text

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{4407_f11.eps}\hspace*{4mm} \includegraphics[width=8.2cm,clip]{4407_f12.eps} \end{figure}$ Figure 7: Time series of the average values of the CDS and SUMER radiances and corresponding MDI magnetic fluxes. The solid lines represent the radiance data and their linear fits, the dashed and dot-dashed lines refer to the MDI data and their corresponding fits. The plotted fits indicate an increase between 15% (MDI in CDS sampling) and 22% (SUMER) within the four years from June 1996 to June 2000. For uncertainties see Fig. 2 and the explanations in the text, especially for the effect of noise on the MDI data.

In the text