\begin{table}%t2
      \caption{Mean values of the mesogranular characteristics as
    function of four segmentation levels; most values are given
    together with their $\pm$$ 1 \sigma$ scatter around the mean.
         \label{tab2}}
     $$
         \begin{array}{p{0.9\linewidth}ccccc}
            \hline\hline
            \noalign{\smallskip}
             \rm{segmentation level} & 80\% & 85\% & 90\% & 95\% \\
            \noalign{\smallskip}
            \hline 
            \noalign{\smallskip}
             Number of & 2812 & 2483 & 2022 & 1220   \\
             tracked mesogranules\\
             Area [$\rm Mm^{2}$] & 16.4 & 12.7 & 9.9 & 7.7  \\
                                 &\pm9.2&\pm6.3&\pm4.0&\pm2.2 \\
             Drift velocity [m/s] & 321 & 314 & 304 & 286 \\
				  &\pm193&\pm189&\pm180&\pm172 \\
            Lifetime [min] & 131 & 150 & 158 & 151         \\
			   &\pm84&\pm104&\pm107&\pm96 \\
            Decay time [min]& 65 &85 & 96 & 99 \\
            Travel distance [Mm] & 2.2 & 2.5 & 2.5 & 2.3 \\
				 &\pm1.4&\pm1.6&\pm1.8&\pm1.6 \\
            \noalign{\smallskip}
            \hline
         \end{array}
     $$
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   \end{table}