WCD-28. Achieving Comparability of Model and Observatory Datasets in YOPPsiteMIP: Challenges and Solutions

Abstract
The YOPPsiteMIP is designed to facilitate process-based validation of numerical weather prediction (NWP) models during a few Special Observing Periods (SOPs). One key component of YOPPsiteMIP is the Merged Observatory Data Files (MODFs) being created for several well-instrumented polar locations. MODFs have been designed in collaboration with interested scientists at NWP centers and will contain, to the extent possible, high-resolution observations of the same geophysical variables that will be provided in the model output data files produced by participating NWP centers for those same locations. How do we ensure that multivariate observational files created by researchers at several institutions are as similar as possible, in terms of nomenclature, metadata, and structure — and also comparable to model-output files created by scientists at multiple NWP centers? A series of tables in a 2018 white paper, listing model variables and the measurements against which they could be compared, has evolved into a published tool providing guidelines for creating MODFs with consistent variable names and metadata. This updatable "H-K Table" is available in both human- and computer-readable forms. It relies on standards and conventions commonly used in the earth sciences, including netCDF encoding with CF Conventions. The prescribed metadata make data provenance clear and encourage proper attribution of the observations. The H-K Table enables observational groups to create modeller-ready MODFs using current requirements and their software of choice, and gives NWP partners guidance in creating comparable model output files.