UNCLASSIFIED
UNCLASSIFIED
Data Inconsistencies
Ship Reports
•Average wind speed error rate from ship reports are 0.6 knots per Beaufort Scale division
•Coverage over vast ocean areas is limited
•Wind directions have an average error of + 10 degrees
Ship data is going to be less accurate than land data.  There are many reasons for this, and you should be aware of these reasons.  That is not to say that this data cannot be used or relied upon.  Any data is better than no data.
1.  Wind speeds can be off by as much as .6 knots per Beaufort Scale division.  This can be a very substantial error with winds associated with a tropical storm or typhoon.

2.  Coverage is extremely limited over vast ocean areas.  Of course this is also the reason for it’s value.  As improvement are made in the accuracy of satellite derived winds, this problem becomes less important.

3.  Wind directions reported have an average error of +10 degrees.  Human error comes into effect here as well as the wind direction taken on a moving ship has a world of reasons for being inaccurate.  The very motion of the ship can cause inaccuracies in the observed direction. This is especially true if the wind speeds are fairly light.