Climatologies or climate normals are an invaluable companion to weather data, enabling absolute values of parameters such as temperature, wind speed and precipitation, to be compared with average levels for that location and time period.
A climatology is an average/mean of a particular weather parameter over a period of time. Many maps, charts and graphs on Trading Weather will have reference to a climatology, either displaying this alongside absolute values or showing absolute values as an anomaly from climatology.
Climatologies are useful because they smooth out temporal differences over several years to provide a base expected level for parameters. Typically, in the world of meteorology, the climate average period is set at 30 years, so climate normals are often an average of 30 years of data. This is the default climate period on Trading Weather. While this means that some data in the climate sample will always be at least 30 years old (with some potential concerns with our warming climate making data multiple decades old potentially "out of date"), it is important that the sample period is long enough to encompass a range of different weather regimes and periodic global circulation drivers such as the El Nino Southern Oscillation which often varies over time scales of several years.
With the rapidly warming climate over recent decades, there is increasing interest in a shorter, more recent climatology, covering just the most recent decade/ 10 years, so users have the opportunity to switch to this 10 year climate for our Country Weighted Graphs. This setting can be changed in the 'preferences' menu, accessed from the drop-down menu at the top right of the screen - scroll to Preferences here for more info.
One map exception to the 30-year climatology is the IMS snow/ice cover maps on TW, which use all available data, continuously building a climatology back to 2004.
Climate normals are updated every decade. The current set of climatologies are built using data from the period 1991-2020 or 2011-2020 (dependent on whether 10 or 30 year climatologies are selected). This period moved forwards 10 years in 2021. The climatologies on TW were updated in Q2 of 2021. Because of the warming climate trend, the shift forward in decade between these two 30-year periods resulted in warmer climate normals for the vast majority of areas, on the scale of 0.1 to 1C for the year. Northern Europe had the most significant warming in the winter (vs the summer) and Scandinavia / NE Europe warmed most.
There are different data sources for calculating climate normals:
For power generation climates, the process has to be modified due to the regularity of capacity changes in certain countries or TSOs. Unlike year to year varibility in weather, which tends to move up and down from year to year, the installations of wind and solar power is only really increasing, so it is essential to keep climates up to date with the increasing capacity. MetDesk regularly adjusts power climate norms to reflect the scale changes in capacity.