ACTION COST-ES0601

Advances in homogenisation methods of climate series: an integrated approach HOME

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ACTION COST-ES0601

 

The action is over, the main conclusions are:

1. Homogenisation improves climate data and does not cause artificial trends. Because the test was blind and because of the realism of the data, this can now be stated with confidence.
2. Modern algorithms, which are designed to also work with an inhomogeneous reference, are clearly better than traditional ones. It needed a realistic benchmark dataset with surrogate climate networks to see this difference clearly.

3. Two new software packages containing some of the methods recommended by HOME are now avalible. The code has been produced by Olivier Mestre, École Nationale de la Météorologie, Météo France, Tolouse". HOMER (for monthly data) and HOM/SPLIDHOM (for daily data)

 

The main article of HOME has been published in Climate of the Past. In this paper homogenisation methods were blindly tested on a dataset with unprecedented realism. All the most used and best algorithms have participated.

To view the article: "Benchmarking homogenization algorithms for monthly data"

 

Please, download the Monthly Benchmark Dataset .

Please, check our literature review on homogenisation .

 

Introduction to the Action Cost-ES0601

Long instrumental climate records are the basis of climate research. However, these series are usually affected by inhomogeneities (artificial shifts), due to changes in the measurement conditions (relocations, instrumentation and others).As the artificial shifts often have the same magnitude as the climate signal, such as long-term variations, trends or cycles, a direct analysis of the raw data series can lead to wrong conclusions about climate change.

In order to deal with this crucial problem many statistical homogenisation procedures have been developed for detection and  correction of these inhomogeneities. At present only a limited number of publications intercompare some common methods and their impact on the climate record.The large number of different methods could be seen as a weakness in the science and is a challenge for the climatological  community to address.

There is therefore a need for a coordinated European initiative in order to produce standard methods designed to facilitate such comparisons and promote the most efficient methods of homogenisation.

The Action's main objective is to achieve a general method for homogenising climate and environmental datasets.The method will be derived from the most adapted statistical procedures for detection and correction of varying parameters at different space and time scales.

See Memorandum of Understanding for more information.

Picture from the MC meeting Bucarest (19-20th of May, 2010).

The action is structured in 5 working groups:

 

 



MASH

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The original MASH (Multiple Analysis of Series for Homogenization; Szentimrey) procedure was developed for homogenization of monthly series. The present version has been developed also for homogenization of daily series.

MASH is a relative method and depending on the distribution of examined meteorological element additive (e.g. temperature) or multiplicative (e.g. precipitation) model can be applied. In the earlier program versions the following subjects were elaborated for monthly series: series comparison, break point (change point) and outlier detection, correction of series, missing data completion, automatic usage of metadata and last but not least a verification procedure to evaluate the homogenization results.

The next versions were developed for homogenization of daily data furthermore for quality control of daily data and missing data completion.

The main developments of the new version MASHv3.03 are connected with the automation in order to obtain such automatic procedures, which can facilitate the homogenization for the users.

The last developments of MASH were elaborated during the CARPATCLIM project. The objective of the project was to investigate the detailed temporal and spatial structure of the climate of Carpathian Region and the commonly used method and software was MASH for homogenization and quality control.

The detailed description of the software can be found in the manual of MASH.


 

 

COST Benchmark Workshop Zurich

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Sept. 14, 2010.
Participants: Victor Venema, Petr Štepánek, Gregor Vertacnik, Tamás Szentimrey, Jose A Guijarro, Barbara Chimani, Renate Kocen, Michele Brunetti, Lars Andresen.

The Report


 

Expert meeting in Oslo 25-26 November 2009

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Homogeneity testing of early instrumental series. Methods of testing long-term series from northern Europe in particular. The Report

 

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