The purpose of the present investigation was to develop empirical formulae for the mean duration of storm and calm weather periods in the coastal and offshore regions of North Western Siberia in various seasons on the basis of existing sample series. These formulae were chosen to be simple and convenient to use. 19 year long series of wind data collected at seven coastal and island hydrometeorological stations were analyzed. It is shown that continuous duration of periods when wind velocity exceeds some certain velocity value is in inverse ratio to this value. So, new form formulae were proposed which allow estimates of the temporal characteristics of wind on the basis of reference book data. The results of this investigation can be applied to the design and operation of offshore installations and for the estimation of wind energetic sources of the region.
Duration of storm and calm weather periods determines conditions of navigation and other offshore activities. When planning the implementation of offshore installations there is a need for storm wind duration climatic features such as integral ratio of storm duration to calm weather duration, average and extreme duration of storms of certain strength. The most significant for offshore engineering and wind energetic applications is the continuous, uninterrupted duration of storm and calm weather periods. In terms of wind, it means the duration of continuous periods when wind velocity exceeds some certain velocity value and when it is weaker. Duration of storm winds is applied in estimations of wave height and drift current velocity. It is widely used in wave forecasting ("Guide to Marine Hydrological Forecasting", 1994, U.S. Army Corps of Engineers, 1984, WMO-No. 701, 1988). However, since it is current data that is significant for navigation purposes, climatological wind duration analysis is beyond the interest of marine navigation.
