Weather Regime definition for the Euro-Atlantic sector (Daily, DFJM, 1979-2018) used for ACDC-ESM

Weather Regime definition for the Euro-Atlantic sector at daily resolution from 1979-2018 for December to March in CSV format

TL;DR: this is the weather regime assignment based the method as set out by Swinda K.J. Falkena in 'Revisiting the identification of wintertime atmosphericcirculation regimes in the Euro-Atlantic sector' (10.1002/qj.3818). Daily data is provided for December to March for the period 1979-2018.

Method Description
The weather regime assignment can be obtained by applying k-means clustering to the full field data of geopotential height data. Following the observed circulation in reanalysis data, the optimal number of clusters is six. By incorporating a weak persistence constraint in the clustering procedure the assignment is stabilized, without changing the weather regime occurrence rates.

The six regimes used have been labelled to indicate atmospheric state. Due to their symmetry, a name (Atlantic Ridge (AR), North Atlantic Oscillation (NAO) and Scandinavian Blocking (SB)) and state (positive (+) and negative (-)) are used to label each of the six weather regimes. It should be noted that the naming convention used, does not imply that the weather associated with these six weather regimes is similar to a definition that uses four or two clusters to classify the weather.

Full details on the method can be found in: Swinda K.J. Falkena, et al, 'Revisiting the identification of wintertime atmosphericcirculation regimes in the Euro-Atlantic sector' (DOI:10.1002/qj.3818). The original implementation and source code can be found on gitHub via: github.com/SwindaKJ/Regimes_Public.

Data structure description
The file is provided in CSV (.csv) format with a semicolon (;) as separator. The first row stores the column labels. The columns contain the following:

• first column (or A) contains the valid-time
  • Label: datetime
  • Contents represent time with text as [DD/MM/YYYY])
• second column (or B) contains the assigned weather regime
  • Label: WR
  • Contents represent the assigned cluster as an interger in the range [0,5]
  • Meaning: 0="SB-", 1="AR+", 2="NAO-", 3="SB+", 4="NAO+", 5="AR-"

DISCLAIMER: the content of this dataset has been created with the greatest possible care. However, we invite to use the original assignement of weather regimes for critical applications and studies.