EM 1110-2-1100 (Part II)
(Change 1) 31 July 2003
the best two-parameter fit to observed pressure profiles or on the combination of an Rmax value with the data
shown in Figure II-2-16. It is worth noting here that the Holland model is similar to several other parametric
models, except that it uses two parameters rather than one in describing the shape of the wind profile. This
second parameter allows the Holland model to represent a range of peakedness rather than only a single
peakedness in applications.
Figure II-2-16. Climatological variation in Holland's "B" factor
(Holland 1980)
(11) As a final element in application of the Holland wind model, it is necessary to consider the effects
of storm movement on the surface wind field. Since a hurricane moves most of its mass along with it (unlike
an extratropical storm), this step is a necessary adjustment to the storm wind field and can create a marked
asymmetry in the storm wind field, particularly for the case of weak or moderate storms. Hughes' (1952)
composite wind fields from moving hurricanes indicated that the highest wind speeds occurred in the right
rear quadrant of the storm. This supports the interpretation that the total wind in a hurricane can be obtained
by adding a wind vector for storm motion to the estimated winds for a stationary storm. On the other hand,
Chow's (1971) numerical results suggest that winds in the front right and front left quadrants are more likely
to contain the maximum wind speeds in a moving hurricane. These contradictory results have made it
difficult to treat the effects of storm movement of surface wind fields in a completely satisfactory fashion.
Various researchers have either ignored the problem or suggested that, at least in simple parametric models,
the effects of storm movement can be adequately approximated by adding a constant vector representative
of the forward storm motion to the estimated wind for a stationary storm. In light of the overall lack of
definitive information on this topic, the latter approach is considered sufficient.
(12) At this point, it should be stressed that Equations II-2-18, 19, and 21 and superposition of the storm
motion vector are only applicable to winds above the surface boundary layer. In order to convert these winds
to winds at a 10-m reference level, it is necessary to apply a model of the type described in Part II-2-1-c-(3)-
II-2-30
Meteorology and Wave Climate
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