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Reduced space optimal interpolation of daily rain gauge precipitation in Switzerland
Author(s) -
Schiemann R.,
Liniger M. A.,
Frei C.
Publication year - 2010
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2009jd013047
Subject(s) - interpolation (computer graphics) , principal component analysis , multivariate interpolation , precipitation , calibration , environmental science , remote sensing , rain gauge , curse of dimensionality , meteorology , computer science , geology , mathematics , statistics , physics , artificial intelligence , motion (physics) , bilinear interpolation
The coarse spacing of automatic rain gauges complicates near‐real‐time spatial analyses of precipitation. We test the possibility of improving such analyses by considering, in addition to the in situ measurements, the spatial covariance structure inferred from past observations with a denser network. To this end, a statistical reconstruction technique, reduced space optimal interpolation (RSOI), is applied over Switzerland, a region of complex topography. RSOI consists of two main parts. First, principal component analysis (PCA) is applied to obtain a reduced space representation of gridded high‐resolution precipitation fields available for a multiyear calibration period in the past. Second, sparse real‐time rain gauge observations are used to estimate the principal component scores and to reconstruct the precipitation field. In this way, climatological information at higher resolution than the near‐real‐time measurements is incorporated into the spatial analysis. PCA is found to efficiently reduce the dimensionality of the calibration fields, and RSOI is successful despite the difficulties associated with the statistical distribution of daily precipitation (skewness, dry days). Examples and a systematic evaluation show substantial added value over a simple interpolation technique that uses near‐real‐time observations only. The benefit is particularly strong for larger‐scale precipitation and prominent topographic effects. Small‐scale precipitation features are reconstructed at a skill comparable to that of the simple technique. Stratifying the reconstruction method by the types of weather type classifications yields little added skill. Apart from application in near real time, RSOI may also be valuable for enhancing instrumental precipitation analyses for the historic past when direct observations were sparse.

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