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Evaluation of alternative Markovian models for precipitation occurrence in Oregon

ScholarsArchive at Oregon State University

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Title Evaluation of alternative Markovian models for precipitation occurrence in Oregon
Names Adotevi-Akue, George Modesto (creator)
Lowry, W. P. (advisor)
Date Issued 1965-05-13 (iso8601)
Note Graduation date: 1965
Abstract Precipitation occurrence in three winter periods and three
summer periods is examined for two Oregon stations: Seaside and
Squaw Butte. The winter periods are January, February, and the
interval January 15 to February 20. The summer periods are July,
August, and the interval July 10 to August 15. The two intervals
were selected as representing stable periods in the Natural Calendar
of the Atmosphere proposed in the literature. Seaside is a coastal
station with a marine climate, while Squaw Butte is in the high
desert of eastern Oregon. At both stations winter is the rainy season
and summer is dry.
By first defining a wet day as any on which .01 inch or more
of precipitation is measured, and then proceeding from the assumption
that daily precipitation occurrence is a two-state Markov Chain
of order 4, the hypotheses are tested that the order of dependence
is 0, 1, 2, and 3 within the fourth order. At Seaside for the winter periods another threshold was employed, with wet days being those
having .20 inch or more of precipitation.
In no case did a Chi-square test for goodness of fit show a
model of zero order to be suitable. For winter periods at Squaw
Butte, a model of order as high as 3 was not clearly suitable. For
all other tests, however, a Markovian model of an order within the
range tested was judged suitable. The variation of threshold tested
at Seaside in winter has no major significance for the periods
examined.
The tests as conducted neither confirm nor deny the validity
of the concept of the Natural Calendar. As a result, however,
recommendations for further tests of this validity are made.
Genre Thesis/Dissertation
Topic Mathematical statistics
Identifier http://hdl.handle.net/1957/48377

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