YOPPsiteMIP: Year of Polar Prediction site Model Inter-comparison Project

Improving the understanding and model representa­tion of critical processes – in polar regions and beyond – requires confronting our latest models with the best available observations. However, this is a challenging task as data are distributed across multiple archives, using different file formats and many different attributes.

As part of the Model Intercomparision and Improvement Project (MIIP), YOPP pioneered the YOPPsiteMIP concept, which is a game changer in terms of the ease of use – and hence uptake – of observational and modelling data from different sources. The aim was to enable efficient evaluation of process representation in models and speed up model improvement.

YOPPsiteMIP provided high-frequency multi-variate obser­vations taken from supersite observatories in combination with timestep model output at co-located grid points from the native model grid.

Initially eight Arctic sites and the MOSAiC expedition contributed observational data to the MIIP with data from more sites to be added during 2023. The sites are key polar observatories and many of them host multiple systems deployed for long-term monitoring and suites of instruments (such as lidars, radars, ceilometers, radiome­ters), that provided detailed measurements characterising the vertical column of the atmosphere as well as the surface and subsurface conditions.

Many major NWP centres provided column model output at the selected sites, including the MOSAiC drift site,in order to contribute to the YOPPsiteMIP sister project MOSAIC-Near Realtime Verification Project. This dataset provides a unique opportunity for in-depth process eval­uation of the representation of small-scale parameterised processes important for atmosphere-sea ice interactions.

The key to this activity was the common file format and semantics (netCDF with CF naming convention) for both models and observations that was established. FAIR principles are followed resulting in Merged Data Files (MDFs) with the two subgroups Merged Model Data Files (MMDF) and Merged Observatory Data Files (MODF) as well as tools to create and analyse them. Both MMDFs and MODFs can be accessed via the YOPP Data Portal.

Featured Publication

Uttal, T,. and co-authors, (2016): International Arctic systems for observing the atmosphere: an inter­national polar year legacy consortium. Bull. Amer. Meteor. Soc., 97(6), 1033-1056


A new article on when and how to get MOSAiC data for process-based model evaluation by Gunilla Svensson (Stockholm University) is now online.