An Alternate Application of the Koppen Classification to Eastern Oregon
1959; University of Hawaii Press; Volume: 21; Issue: 1 Linguagem: Inglês
10.1353/pcg.1959.0000
ISSN1551-3211
Autores Tópico(s)Geology and Paleoclimatology Research
ResumoAN ALTERNATE APPLICATION OF THE KOPPEN CLASSIFICATION TO EASTERN OREGON R. D. Rudd Oregon State College Among the numerous classifications of world climates developed in the past half-century, the most widely known is the Koppen.1 This classification , or a modification of it, not only serves as the framework on which the study of climates is developed in many textbooks,- but it is also the most commonly used basis for the introductory study of climate in the United States,'1 In the Koppen-Geiger Handbuch der Klimatologie, reference is made to die "Oregon climate," so called because it seemed to be unique to die American Pacific Northwest and had its chief areal expression in Oregon, . . . the higher plateaus of Oregon, become so cold in winter, —3°C. Jan. (D), and also cool in summer (b), that tíiey are set off as a separate type (Dsb) called the Oregon climate, for it is found nowhere else in the world.1 Subsequently, the existence of small areas of Dsb climate have been noted in other locations/' It will be recalled that the symbol "D" indicates ¦ a humid continental climate, "s" a precipitation regime in which there is a marked summer drought, and "b" a cool summer. The latest Koppen-Geiger map" shows a considerable proportion of eastern Oregon as having this Dsb climate, a section along the Columbia and Snake Rivers and a larger area in the southeast being classified otherwise. 1 Wladimir Koppen, Grundriss der Klimakunde, de Gruyter Company, Berlin, 1931. - Among these arc Clarence E. Koeppc nud George C, DeLong, Weather and Climate, McGraw-Hill Company, New York, 195S; Glenn T. Trewartha, An Introduction to Climate, McGraw-Hill Company, New York, 1954; Henry M. Kendall et al, Introduction to Physical Geography, Harcourt, Brace and Company, New York, 1952; Bernhard Haurwitz nnd James M. Austin, Climatology, McGraw-Hill Company, 1944; Preston E. James, An Outline of Geography, Ginn nnd Company, Boston, 1935, and A Geography of Man, Ginn and Company, Boston, 1959. 8 See L, Dudley Stump, "Major Natural Regions, Herbertson after Fifty Years," Geography, Vol, XLII, Part 4, p. 210, November, 1957. 4 W, Koppen and R. Geiger, Handbuch der Klimatologie, Gebruder Borntraeger, Berlin, 1936, Vol. 2, Part J, p. 195.·G| An example is John D. Chapman, "The Climate of British Columbia," Transactions of thd Fifth British Columbia Natural Resources Conference, Victoria, 1952. p. S, 0WiUl map, W, Koppen and R. Geiger, Klima der Erde, Justus Perthes, Darmstadt , Geniiany, 1954. 31 In fact, fully one-half of eastern Oregon is indicated as humid (Fig. 1). Included in this area of humid climate are the Blue, Wallowa, and Ochocu Mountains which are forested and have an appearance indicative of a humid climate, but there are rather extensive areas of plateau and lowland , distinctly arid in appearance, which are also classified as humid. To delimit the areas of humid climate more precisely 55 stations in eastern Oregon were classified according to die Koppen system. Assuming a summer drought, or winter precipitation maximum, (Fig. 2) the area of humid climate appears overwhelmingly dominant in eostern Oregon, Climatic classification of the plateau country of eastern Oregon as humid seems inappropriate. Neither annual precipitation figures for stations in the area nor the general appearance of the area support such a classification, An alternate application of the Koppen classification, proposed in this paper, would result in most of the eastern Oregon plateau area being classified as semi-arid rather than humid. The Climate of Eastern Oregon A study of climatological data for the area is basic to understanding its climate. Four stations wore selected to illustrate the character of die climate graphically (Fig, 3). Located near one of the four corners of eastern Oregon, each station has a record exceeding 20 years in length,7 The following discussion utilizes data for many stations. Temperatures. The continentality of eastern Oregon is reflected in its temperatures. Mean July temperatures for 55 stations considered are all between 62e and 75° F., with a majority below 71° F. Mean January temperatures are mostly between 21° and 32° F., although ? few stations have averages slightly above freezing. Average annual temperature ranges vary from near 35° to 52° F...
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