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Fig6.2.4-2 shows the contributions to the forecast errors from planetary-wave scales (scales greater than about 2500km, with zonal wave numbers 0-3; thick full lines) and synoptic scales (scales between 650-2500km, with zonal wave numbers 4-14; thin full lines).  The ensemble control has a similar lead-time advantage (just less than a day) over the single member for both scales. Up to about Day 7, the contributions from both scales to the total error are quite similar (the thick and thin full lines are on top of each other). Beyond Day 7, the contribution from the synoptic scales begins to saturate (i.e. have little skill) as it approaches the atmospheric activity at these scales (thin dotted and dashed lines). On the other hand, the planetary scales continue to include useful information beyond Day 7, and their error continues to increase towards the (higher) level of planetary scale activity (thick dotted and dashed lines.

(FUG Associated with Cy49r1)