Abstract

Abstract. The seasonal cycle of radiation intensity often causes a marked seasonal cycle in the inhomogeneities (IHs) of observed temperature time series, since a substantial portion of them have direct or indirect connection to radiation changes in the micro-environment of the thermometer. Therefore the magnitudes of temperature IHs tend to be larger in summer than in winter. A new homogenisation method, the Adapted Caussinus – Mestre Algorithm for Networks of Temperature series (ACMANT) has recently been developed which treats appropriately the seasonal changes of IH-sizes in temperature time series. The performance of ACMANT was proved to be among the best methods (together with PRODIGE and MASH) in the efficiency test procedure of COST ES0601 project. A further improved version of the ACMANT is described in this paper. In the new version the ANOVA procedure is applied for correcting inhomogeneities, and with this change the iterations applied in the earlier version have become unnecessary. Some other modifications have also been made, from which the most important one is the new way for estimating the timings of IHs. With these modifications the efficiency of the ACMANT has become even higher, therefore its use is strongly recommended when networks of monthly temperature series from mid- or high geographical latitudes are subjected to homogenisation. The paper presents the main properties and the operation of the new ACMANT.

Highlights

  • The investigation of climate change and climate variability needs a large amount of observed data of high quality

  • In the ACMANT the ANOVA is applied to the two annual variables (T M and T D) separately, and thereafter monthly adjustments are calculated as a composition of the shift in annual mean and the relevant value of the seasonal cycle

  • The results show that the efficiency of the ACMANT is 0.545 in monthly root mean squared errors (RMSE), 0.666 in annual RMSE and 0.753 in trend-slope RMSE

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Summary

Data Abstract

The seasonal cycle of radiation intensity often causes a marked seasonal cycle in the inhomogeneities (IHs) of observed temperature time series, since a substantial portion of them have direct or indirect connection to radiation changes in the micro-environment of the thermometer. A new homogenisation method, the Adapted Caussinus – Mestre Algorithm for Networks of Temperature series (ACMANT) has recently been developed which treats appropriately the seasonal changes of IH-sizes in temperature time series. Some other modifications have been made, from which the most important one is the new way for estimating the timings of IHs. Some other modifications have been made, from which the most important one is the new way for estimating the timings of IHs With these modifications the efficiency of the ACMANT has become even higher, its use is strongly recommended when networks of monthly temperature series from mid- or high geographical latitudes are subjected to homogenisation. The paper presents the main properties and the operation of the new ACMANT

Introduction
Main properties of ACMANT
Constructing relative time series
Detecting IHs with Main Detection
Calculation of timings of change-points with monthly preciseness
Homogenisation-adjustment with ANOVA
Some further details of ACMANT
The efficiency of ACMANT
Findings
Conclusions
Full Text
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