\begin{table}%t3
\caption{Wind statistics at Dome C and South Pole over the
period of time covered by the balloon launches.} \label{spdc}
%\centering
\par
\begin{tabular}{lllll}
  \hline \hline
   & Dome C &  &  &   \\
  \hline
   & {\em ground} & {\em trop.$-$330 mB} & {\em 200 mB-11 km} & {\em 50 mB}  \\
  $N$ data & 8741 & 145 & 123 & 75  \\
  Mean w speed & 3.6 & 12.2 & 7.4 & 6.6  \\
  Med. w speed & 3.5 & 10.7 & 5.9 & 4  \\
  W speed std dev & 2.5 & 7.2 &  5.3 & 6.1  \\
  Max w speed & 10.5 & 41 & 25.7 & 34.4  \\
  Mean direc. & 180.3 & 187.6 & 211.6 & 193  \\
  Direc. std dev & 74.4 & 92.6 & 90.8 & 121.6  \\
  \hline
  & South Pole &  &  &   \\
  \hline
  &{\em ground} & {\em trop.$-$330 mB} & {\em 200 mB-11 km} & {\em
  50 mB}\\
\par
  $N$ data &  668 & 666 & 662 & 621 \\
  Mean w speed &  4.7 & 10 & 7 & 9.2 \\
  Med. w speed &  4.5 & 8.1 & 5.7 & 4.7 \\
  W speed std dev &  2 & 7 & 4.9 & 9.6 \\
  Max w speed &  13 & 47.8 & 35.4 & 56 \\
  Mean direc. &  105.9 & 213.7 & 203.6 & 155.3 \\
  Direc. std dev &  112.3 & 113.3 & 114.4 & 100.4 \\
  \hline
\end{tabular}
\end{table}