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The new MARS client with the MIR interpolation library is currently in BETA, and it is meant for tests only. Do not use it for any operational purpose. You can try now considered ready for production and suitable for operational use. It is not yet the default version. You can use the new MIR-enabled MARS client on any ECMWF computing platform with:
You are encouraged to test this new version of the MARS client and report any issues to servicedesk@ecmwf.int. If you are using the the ECMWF WebAPI you can test it by adding an extra keyword to your requests:
You are encouraged to test this new version of the MARS client and report any issues to servicedesk@ecmwf.int. |
MIR stands for Meteorological Interpolation and Regridding and is a library of routines for interpolation and regridding of meteorological fields. This new piece of software is replacing the veteran EMOSLIB when it comes to perform those operations in MARS. Beyond this, MIR’s flexible design facilitates scalability improvements and additional features. These include efficiency gains, a high degree of user configurability, and support for a wider range of grids than in the current package. See the related article in the ECMWF newsletter no.152 for a more complete description of this new library.
Table of contents
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News
1 November 2018
MARS/MIR (1.0.0) is released. This new version of MARS/MIR is the first version considered ready for operational use.
24 July 2018
MARS/MIR (0.10.0) is released. This new version of MARS/MIR remains a a BETA version version and is not yet ready for operational use. It introduces two important changes versus previous versions of MARS/MIR:
- Improvements have been made to enhance the performance of spectral to grid transformations when the target is a subarea.
- Interpolation of unclassified parameters will fail.
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Important dates
- August/September 1 November 2018: Release of a MARS MARS/MIR which will be is considered ready for production. The old MARS/EMOSLIB client would still be the default.operations, but it is not the default version at ECMWF.
- End of January 2019Late autumn 2018: MARS/MIR becomes the default version at ECMWF, with the exact date to be confirmed at a later stage. The old MARS/EMOSLIB will still be accessible through mars -e, but there will be no further updates to it.
The exact dates for each milestone will be communicated closer to their times.
Questions and Answers
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The EMOSLIB interpolation package was written in the 1980s and much has changed since then: the model grid resolution has steadily increased, a variety of grid types have been introduced, and many new parameters have been added over the years, often associated with different processing requirements. Both software and hardware technologies, such as programming languages, design paradigms, supporting libraries and hardware architectures, have evolved significantly. These aspects, together with new numerical methods and ECMWF's improved understanding of user requirements, have prompted ECMWF to design the new, extensible and easy-to-maintain MIR package |
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At the moment MIR is only made available through the MARS client. In the medium term, a standalone command line tool based on MIR may become available. Other release options may also be considered in the future. |
Highlights and main differences
We have compiled a few examples illustrating the differences between EMOSLIB and MIR for a number of representative parameters:
- Temperature at 2m
- Total precipitation
- 10m winds
- Land-sea mask
- Mean sea-level pressure
- Soil type
- Temperature at 1000 hPa
- Winds at 1000 hPa
- Wave fields
- Significant wave height
Interpolation methods and distance computation
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When doing spectral to grid transformations, MIR may produce smoother fields compared to EMOSLIB. This is due to the fact that MIR uses the intermediate gaussian grid, while EMOSLIB does this transformation directly. | ||
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Starting with MARS/MIR (0.10.0) relative humidity on pressure levels is transformed with "RESOL=AV" by default. This improves the quality of the output field but will make the retrieval of relative humidity more expensive when the target grid is at a relatively low resolution. Users wishing to override this behaviour can specify "RESOL=AUTO". |
Waves
Due to the differences mentioned above, the nearest neighbour method selects different points due to the difference in the computation of the distance (3D versus 2D). Different treatment of neighbouring missing values produces a smoother interpolation close to coasts.
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