Normal period
The normal period (often air standard value period , climate reference period , climatological reference period ) is a period of climate observation , of the World Meteorological Organization was established (WMO) to 30 years. The reference period of the WMO is, as of 2019, the period from 1961–1990. According to the usual practice of the WMO, this normal period will continue to apply until at least 2020 and then replaced by 1991–2020. Previous normal periods were 1901–1930 and 1931–1960.
For the period of the normal period, the mean values of the climate data of a location, region or global are calculated, a prominent example is the global average temperature . These values then serve as a reference for the evaluation and comparative consideration of the climate, for example in the calculation of temperature anomalies or as a planning basis for decisions that depend on climatic conditions.
For statistical reasons, normal periods other than those of the WMO are then in use in order to have a closed but close interval available, for example currently 1971-2000 for Austria on the part of the ZAMG , the Austrian glacier inventory and other geosciences. The completed 30-year normal period is also based on the term thirty-year extreme event ( annuality > 30). The WMO recommended a further comparison period (1981–2010) to its members, especially for shorter-term comparisons, parallel to the 30-year comparison period (1961–1990). Meteo Schweiz and many others have already followed this recommendation.
The increasing temperatures in the course of global warming cause the global mean value of current comparison periods to rise compared to earlier comparison periods. The consequences: A current year like 2012, which is “too warm” compared to the reference period 1961–1990 with the lower average values, is suddenly a “normal” compared to the reference period 1981–2010, in which the warm years are already taken into account. Year.
Other periods are also used as norms, such as secular periods such as 1851–1950, or 50-year periods such as 1881–1930 (for which largely complete weather records are already available) - the reference is then explicitly stated here. These reference periods are used to determine fifty or hundred year old weather anomalies (century events).
Individual evidence
- ↑ Climatological reference period. In: Weather Lexicon. German Weather Service , accessed on May 12, 2019 .
- ↑ Explanations of the maps of normal values. In: German Climate Atlas. German Weather Service, accessed on May 12, 2019 .
- ^ A b Anthony Arguez, Russell S. Vose: The Definition of the Standard WMO Climate Normal - The Key to Deriving Alternative Climate Normals . In: Bulletin of the American Meteorological Society . June 2011, doi : 10.1175 / 2010BAMS2955.1 .
- ↑ Why climate change is no longer happening , International Economic Forum for Renewable Energies on January 23, 2013