Autocorrelation
; Correlation detectors
; Time series
; Change-point analysis
; Computational speed
; Daily temperatures
; Detection precision
; Seasonal cycle
; Simulation studies
; Statistical characteristics
; Temperature anomaly
; Time series analysis
; autocorrelation
; climatology
; diurnal variation
; temperature anomaly
; time series
; Michigan
; United States
英文摘要:
This paper develops a method for homogenizing daily temperature series. While daily temperatures are statistically more complex than annual or monthly temperatures, techniques and computational methods have been accumulating that can now model and analyze all salient statistical characteristics of daily temperature series. The goal here is to combine these techniques in an efficient manner for multiple changepoint identification in daily series; computational speed is critical as a century of daily data has over 36 500 data points. The method developed here takes into account 1) metadata, 2) reference series, 3) seasonal cycles, and 4) autocorrelation. Autocorrelation is especially important: ignoring it can degrade changepoint techniques, and sample autocorrelations of day-to-day temperature anomalies are often as large as 0.7. While daily homogenization is not conducted as commonly as monthly or annual homogenization, daily analyses provide greater detection precision as they are roughly 30 times as long as monthly records. For example, it is relatively easy to detect two changepoints less than two years apart with daily data, but virtually impossible to flag these in corresponding annually averaged data. The developed methods are shown to work in simulation studies and applied in the analysis of 46 years of daily temperatures from South Haven, Michigan.
Department of Statistics and Computer Science, University of Kelaniya, Kelaniya, Sri Lanka; Department of Mathematical Sciences, Clemson University, Clemson, SC, United States; Department of Statistical Science, Southern Methodist University, Dallas, TX, United States; Cooperative Institute for Climate and Satellites-North Carolina, North Carolina State University, Raleigh, NC, United States; NOAA/National Center for Environmental Information, Asheville, NC, United States
Recommended Citation:
Hewaarachchi A.P.,Li Y.,Lund R.,et al. Homogenization of daily temperature data[J]. Journal of Climate,2017-01-01,30(3)