Figure 6. Two typical snapshots of raw one-day period plankton movements (w-data) around −1000 m at mooring LOC164 (22.5°N, 27°W) for winter and summer.

In winter, the more diffuse downward migration peaks later than expected as compared with the summer-data. The discrepancy between the absolute time difference between plankton movement (w-peaks) in summer and winter (dashed lines in lower panel) is larger in the morning than in the evening. This explains the larger amplitude of DVM-variations with day length observed in Figure 5 for peak-w (*) by about 40 minutes on average.