Climatic Variability in the Kuparuk Region, North-central Alaska: Optimizing Spatial and Temporal Interpolation in a Sparse Observation Network

Abstract

Air temperature fields are required as input to spatial models in ecology, geocryology, and biogeochemistry. Air temperature data from a sparse, irregular meteorological network in the Kuparuk region of north-central Alaska were interpolated spatially and temporally to provide a 13-year (1987-1999) series of thawing degree-day fields at 1 km² resolution. Procedures involved standardizing diverse temperature records and applying topographically and climatologically aided interpolation, using station data and digital elevation models, to incorporate the effects of local topography. The accuracy of the interpolation procedures was assessed using cross validation. Considering the number of data points used for interpolation, their distribution, and the size of the area, the combination of climatologically assisted and topographically informed spatial interpolation procedures provides adequate representation of the annual degree-day fields for the Kuparuk region. Spatially integrated mean absolute error does not exceed 3% in any year. To investigate the spatial distribution of interpolation uncertainties, the cross-validation errors obtained at each station for each year were interpolated spatially to a regular 1 × 1 km grid consistent with the degree-day fields.