In both pre and post-construction yield assessment studies, one key step corresponds to the long-range forecasting. To extrapolate measured data from short-term to longer-term, it is necessary to select relevant historical date (the reference source) that could be representative of the future site climatology.

In this context, the main data sources that can be used are:
• Measured data issued from land-based weather stations
• Reanalysis data issued from validated data assimilation systems

Over the last few years, the Modern-Era Retrospective analysis for Research and Applications (MERRA) dataset has been widely involved in numerous pre and post-construction studies because of its higher reliability compared to regional weather stations.

In February 2016, an updated version of the MERRA reanalysis dataset was launched to replace the original MERRA product.

The aim of over the next three databytes will be to understand the difference between these two datasets (MERRA and MERRA-2), and the impact on the existing yield assessment studies.

By Perrine Bugeat – Asset Manager