The wind energy industry has grown since the days when most project developers relied exclusively on public met station data for long-term historical references. These public weather stations were generally not built primarily for wind energy use, and much of the data they provide is at lower heights than needed for wind energy assessment.
A reanalysis data set is a global, gridded, three-dimensional description of all weather variables over a period of several decades. Reanalysis time series include snapshots of these weather variables at different times (generally hourly). Reanalysis data sets are produced by feeding weather observations and historical data into a "data assimilation" system and using modeling to fill in any gaps. The modeling and data assimilation are done in a consistent manner, ensuring that the estimates of climate conditions throughout the data set will be consistent.
For wind, the reanalysis approach models wind conditions at given heights and locations, and provides this data as a time series for any given time period within the scope of the data set. Wind developers can use reanalysis data - drawn from several publicly available data sets - as a valuable input into wind resource assessment.
Tools such as Vaisala's Wind Time Series offer subscription-based access to more than one reanalysis data set. Why would a wind developer pay for this data, when it's available for free? Here's how the Wind Time Series tool adds value.
Consistency. The time series tool takes publicly available data sets and interpolates them all to an hourly resolution as well as spatially to any specific geographic location. Not all reanalysis data sets are equal, and some are better suited than others for a specific region and a specific time period. Having the data in a format that can be easily compared at an hourly interval eliminates a lot of the number-crunching you would have to do to compare the data sets yourself outside of the tool.
Context. If you have any observations at a project site, reanalysis data are an excellent choice for providing long-term context as well as a sense of the long-term variability of the wind resource.
Comparison. Being able to easily compare multiple time series in a graphical interface gives you the ability to compare data sets, assess the differences, and choose the reanalysis data set or data sets that will best suit your location. The tools show the spread between different data sets, and a wider spread means there is greater uncertainty about the wind resource at the location.
Convenience. By having subscription-based access to time series and a web-based interface such as Vaisala’s dashboard and map controller, you can easily choose any location, visually compare the data, and receive your chosen time series within a few hours.
We've made the subscription process even easier - now you can subscribe to the time series tools online. Your data sets are just a few clicks away!