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contributor authorZhang, Ying
contributor authorMoges, Semu
contributor authorBlock, Paul
date accessioned2017-06-09T17:12:55Z
date available2017-06-09T17:12:55Z
date copyright2016/05/01
date issued2016
identifier issn0894-8755
identifier otherams-81202.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4224180
description abstractefining homogeneous precipitation regions is fundamental for hydrologic applications, yet nontrivial, particularly for regions with highly varied spatial?temporal patterns. Traditional approaches typically include aspects of subjective delineation around sparsely distributed precipitation stations. Here, hierarchical and nonhierarchical (k means) clustering techniques on a gridded dataset for objective and automatic delineation are evaluated. Using a spatial sensitivity analysis test, the k-means clustering method is found to produce much more stable cluster boundaries. To identify a reasonable optimal k, various performance indicators, including the within-cluster sum of square errors (WSS) metric, intra- and intercluster correlations, and postvisualization are evaluated. Two new objective selection metrics (difference in minimum WSS and difference in difference) are developed based on the elbow method and gap statistics, respectively, to determine k within a desired range. Consequently, eight homogenous regions are defined with relatively clear and smooth boundaries, as well as low intercluster correlations and high intracluster correlations. The underlying physical mechanisms for the regionalization outcomes not only help justify the optimal number of clusters selected, but also prove informative in understanding the local- and large-scale climate factors affecting Ethiopian summertime precipitation. A principal component linear regression model to produce cluster-level seasonal forecasts also proves skillful.
publisherAmerican Meteorological Society
titleOptimal Cluster Analysis for Objective Regionalization of Seasonal Precipitation in Regions of High Spatial–Temporal Variability: Application to Western Ethiopia
typeJournal Paper
journal volume29
journal issue10
journal titleJournal of Climate
identifier doi10.1175/JCLI-D-15-0582.1
journal fristpage3697
journal lastpage3717
treeJournal of Climate:;2016:;volume( 029 ):;issue: 010
contenttypeFulltext


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