Spicules have been observed on the sun for more than a century, typically in
chromospheric lines such as H-alpha and Ca II H. Recent work has shown that
so-called 'type II' spicules may have a role in providing mass to the corona
and the solar wind. In chromospheric filtergrams these spicules are not seen to
fall back down, and they are shorter-lived and more dynamic than the spicules
that have been classically reported in ground-based observations. Observations
of type II spicules with Hinode show fundamentally different properties from
what was previously measured. In earlier work we showed that these dynamic type
II spicules are the most common type, a view that was not properly identified
by early observations.The aim of this work is to investigate the effects of
spatio-temporal resolution in the classical spicule measurements. Making use of
Hinode data degraded to match the observing conditions of older ground-based
studies, we measure the properties of spicules with a semi-automated algorithm.
These results are then compared to measurements using the original Hinode data.
We find that degrading the data has a significant effect on the measured
properties of spicules. Most importantly, the results from the degraded data
agree well with older studies (e.g. mean spicule duration more than 5 minutes,
and upward apparent velocities of about 25 km/s). These results illustrate how
the combination of spicule superposition, low spatial resolution and cadence
affect the measured properties of spicules, and that previous measurements can
be misleading.Comment: Accepted for publication in ApJ. 5 pages, 3 figures. Movies of
figures 1 and 3 available via Data Conservanc