Aj. Grundstein et Ml. Bentley, A growing-season hydroclimatology, focusing on soil moisture deficits, forthe Ohio Valley region, J HYDROMETE, 2(4), 2001, pp. 345-355
A hydroclimatology, or description of long-term means and interannual varia
tion, that focuses on soil moisture deficits was constructed for the period
of 1895-1998 for a six-state region composing the Ohio Valley. The term "d
eficit'' is considered from an agricultural point of view whereby moisture-
induced crop stress is a combination of insufficient precipitation and soil
moisture. Of particular concern are deficits that occur during the growing
season (May-September) when vegetation is most susceptible to moisture-ind
uced stress. Evidence suggests that there is considerable temporal variabil
ity but no long-term trend toward either wetter or drier conditions in the
Ohio Valley. The pattern of growing-season deficit is characterized by mult
iyear and multidecadal cycles of wet and dry periods. Decreases in precipit
ation during years with anomalously large growing-season deficits, however,
are associated more with the reduced frequency of precipitation events tha
n with any changes in intensity. These variations in precipitation frequenc
y and the conditions conducive to droughts are intimately linked with large
-scale atmospheric conditions, including the low-level and upper-level flow
patterns.