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> Abstract: Daly et al 1994
Daly, C.; Neilson, R.; Phillips, D. 1994. A statistical-topographic
model for mapping climatological precipitation over mountainous terrain.
Journal of Applied Meteorology. 33(2): 140-158.
The demand for climatological precipitation fields on a regular grid
is growing dramatically as ecological and hydrological models become increasingly
linked to geographic information systems that spatially represent and
manipulate model output. This paper presents an analytical model that
distributes point measurements of monthly and annual precipitation to
regularly spaced grid cells in midlatitude regions. PRISM (Precipitation-Elevation
Regressions on Independent Slopes Model) brings a combination of climatological
and statistical concepts to the analysis of orographic precipitation.
Specifically, PRISM (1) uses a digital elevation model (DEM) to estimate
the orographic elevations of precipitation stations; (2) uses
the DEM and a windowing technique to group stations onto individual topographic
facets; (3) estimates precipitation at a DEM grid cell through a regression
of precipitation versus DEM elevation developed from stations on the cell's
topographic facet; and (4) when possible, calculates a prediction interval
for the estimate, which is an approximation of the uncertainty involved.
PRISM exhibited the lowest cross-validation bias and absolute error when
compared to kriging, detrended kriging, and cokriging in the Willamette
River basin, Oregon. PRISM was also applied to northern Oregon and to
the entire Western United States; detrended kriging and cokriging could
not be used, because there was no overall relationship between elevation
and precipitation. Cross-validation errors in these applications were
confined to relatively low levels because PRISM continually adjusts its
frame of reference by using localized precipitation-DEM elevation relationships.