scholarly journals SPLIDHOM: A Method for Homogenization of Daily Temperature Observations

2011 ◽  
Vol 50 (11) ◽  
pp. 2343-2358 ◽  
Author(s):  
Olivier Mestre ◽  
Christine Gruber ◽  
Clémentine Prieur ◽  
Henri Caussinus ◽  
Sylvie Jourdain
Keyword(s):  
Time Scale ◽  
Smoothing Splines ◽  
Temperature Series ◽  
High Order ◽  
Daily Temperature ◽  
Daily Series ◽  
Nonlinear Regression Method ◽  
Daily Temperature Series ◽  
Selection Of ◽  
Daily Time

AbstractOne major concern of climate change is the possible rise of temperature extreme events, in terms of occurrence and intensity. To study this phenomenon, reliable daily series are required, for instance to compute daily-based indices: high-order quantiles, annual extrema, number of days exceeding thresholds, and so on. Because observed series are likely to be affected by changes in the measurement conditions, adapted homogenization procedures are required. Although a very large number of procedures have been proposed for adjustment of observed series at a monthly time scale, few have been proposed for adjustment of daily temperature series. This article proposes a new adjustment method for temperature series at a daily time scale. This method, called spline daily homogenization (SPLIDHOM), relies on an indirect nonlinear regression method. Estimation of the regression functions is performed by cubic smoothing splines. This method is able to adjust the mean of the series as well as high-order quantiles and moments of the series. When using well-correlated series, SPLIDHOM improves the results of two widely used methods, as a result of an optimal selection of the smoothing parameter. Applications to the Toulouse, France, temperature series are shown as a real example.

Homogenization of Daily Temperature Data

2017 ◽  
Vol 30 (3) ◽  
pp. 985-999 ◽  
Author(s):  
Anuradha P. Hewaarachchi ◽  
Yingbo Li ◽  
Robert Lund ◽  
Jared Rennie
Keyword(s):  
Temperature Series ◽  
Daily Temperature ◽  
Statistical Characteristics ◽  
Efficient Manner ◽  
Daily Data ◽  
Computational Speed ◽  
Daily Series ◽  
Data Points ◽  
South Haven ◽  
Daily Temperature Series

Abstract 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.

scholarly journals Extreme value and cluster analysis of European daily temperature series

2011 ◽  
Vol 38 (12) ◽  
pp. 2793-2804 ◽  
Author(s):  
Manuel G. Scotto ◽  
Susana M. Barbosa ◽  
Andrés M. Alonso
Keyword(s):  
Cluster Analysis ◽  
Extreme Value ◽  
Temperature Series ◽  
Daily Temperature ◽  
And Cluster Analysis ◽  
Daily Temperature Series

scholarly journals Homogenization of daily temperature series in the European Climate Assessment & Dataset

2018 ◽  
Vol 39 (3) ◽  
pp. 1243-1261 ◽  
Author(s):  
Antonello A. Squintu ◽  
Gerard van der Schrier ◽  
Yuri Brugnara ◽  
Albert Klein Tank
Keyword(s):  
Temperature Series ◽  
Daily Temperature ◽  
Climate Assessment ◽  
European Climate ◽  
Daily Temperature Series

scholarly journals Comparison of homogenization methods for daily temperature series against an observation-based benchmark dataset

2020 ◽  
Vol 140 (1-2) ◽  
pp. 285-301 ◽  
Author(s):  
Antonello Angelo Squintu ◽  
Gerard van der Schrier ◽  
Petr Štěpánek ◽  
Pavel Zahradníček ◽  
Albert Klein Tank
Keyword(s):  
Temperature Series ◽  
Benchmark Dataset ◽  
Daily Temperature ◽  
Reference Series ◽  
The Czech Republic ◽  
Benchmark Datasets ◽  
Homogenization Methods ◽  
Daily Temperature Series ◽  
Almost All ◽  
Station Density

AbstractHomogenization of daily temperature series is a fundamental step for climatological analyses. In the last decades, several methods have been developed, presenting different statistical and procedural approaches. In this study, four homogenization methods (together with two variants) have been tested and compared. This has been performed constructing a benchmark dataset, where segments of homogeneous series are replaced with simultaneous measurements from neighboring homogeneous series. This generates inhomogeneous series (the test set) whose homogeneous version (the benchmark set) is known. Two benchmark datasets are created. The first one is based on series from the Czech Republic and has a high quality, high station density, and a large number of reference series. The second one uses stations from all Europe and presents more challenges, such as missing segments, low station density, and scarcity of reference series. The comparison has been performed with pre-defined metrics which check the statistical distance between the homogenized versions and the benchmark. Almost all homogenization methods perform well on the near-ideal benchmark (maximum relative root mean square error (rRMSE): 1.01), while on the European dataset, the homogenization methods diverge and the rRMSE increases up to 1.87. Analyses of the percentages of non-adjusted inhomogeneous data (up to 39%) and substantial differences in the trends among the homogenized versions helped identifying diverging procedural characteristics of the methods. These results add new elements to the debate about homogenization methods for daily values and motivate the use of realistic and challenging datasets in evaluating their robustness and flexibility.

Frequency-Weighted Variable-Length Controllers Using Anytime Control Strategies

2011 ◽  
Author(s):  
Gundula B. Runge ◽  
Al Ferri ◽  
Bonnie Ferri
Keyword(s):  
Time Scale ◽  
Weighting Function ◽  
Control Strategies ◽  
Low Frequency ◽  
Low Frequencies ◽  
High Frequencies ◽  
Frequency Components ◽  
Computational Resources ◽  
Weighted Variable ◽  
Selection Of

This paper considers an anytime strategy to implement controllers that react to changing computational resources. The anytime controllers developed in this paper are suitable for cases when the time scale of switching is in the order of the task execution time, that is, on the time scale found commonly with sporadically missed deadlines. This paper extends the prior work by developing frequency-weighted anytime controllers. The selection of the weighting function is driven by the expectation of the situations that would require anytime operation. For example, if the anytime operation is due to occasional and isolated missed deadlines, then the weighting on high frequencies should be larger than that for low frequencies. Low frequency components will have a smaller change over one sample time, so failing to update these components for one sample period will have less effect than with the high frequency components. An example will be included that applies the anytime control strategy to a model of a DC motor with deadzone and saturation nonlinearities.

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