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11 April 2017

MÉRA Frequently asked questions

What is MÉRA?
MÉRA, Met Éireann ReAnalysis is a 35-year (1981-2015) reanalysis of Ireland’s climate.

What is climate reanalysis?
Climate reanalysis is a systematic approach used to produce meteorological datasets for climate monitoring and research. They are created using a fixed version of a forecast model and a data assimilation system which utilises historical observations and they produce parameters that are physically consistent and often not routinely observed. Thus, climate reanalyses have the potential to extend the knowledge gained from current observation networks.  

What format are the reanalysis data in?
- Gridded binary (GRIB 1)

How do I convert the files to NetCDF format?
Using CDO:
    - install CDO:
    - cdo -f nc setgridtype,curvilinear input.filename output.filename

Where can I download the data?
A 1-month sample of some of the data (in GRIB 1 format) can be found below. To register for updates on the full release and launch of the data, e-mail

mean sea level pressure

2 m temperature

10 m wind - u component

10 m wind - v component

Parameter list and codes

File name convention:
    YYYY: Year (%Y, four-digit)
    MM: Month (%m, two-digit)
    PAR: GRIB1 parameter indicator (indicatorOfParameter), see Table 1
    TYP: GRIB1 level type indicator (indicatorOfTypeOfLevel), see Table 1
    LEV: GRIB1 Ievel indicator (level), see Table 1
    TRI: GRIB1 time range indicator (timeRangeIndicator), see Table 1
    DATA: ANALYSIS/FC3hr/FC33hr - see “What’s in each file?” question

What’s in each file (analysis, 3hr, 33hr)?
ANALYSIS: For each parameter, these files consist of a time-series of the parameter at the initial time-step of each data assimilation cycle (i.e. 0h, 3h, ….. , 21h).
FC3hr: For each parameter, these files consist of a time-series of 1h, 2h and 3h forecasts of the parameter for each data assimilation cycle.
FC33hr: For each parameter, these files consist of a time-series of 1h, 2h, …. 33h forecasts of the parameter for the 00 UTC data assimilation cycles.

There is one file of each type per parameter and per calendar month.

How do I cite the MÉRA reanalysis in my publication?
To cite MÉRA please use the following reference:

What is the resolution of the MÉRA data?
The HARMONIE-AROME canonical configuration of the ALADIN-HIRLAM Numerical Weather Prediction System was run on a 2.5 km horizontal grid.

What licence does the data come under?
The data will be available under the creative commons Attribution 4.0 International (CC BY 4.0) license:

When will the full dataset become available?
By summer 2017


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