Extremes

Meteonorm's default climate data represents a median, average climate, meaning there's a 50% probability of exceedance (PoE 50). When generating hourly data, the software typically uses PoE 50 monthly averages as its basis, ensuring that the resulting hourly values reflect a typical distribution for that month, including typical hourly extremes (e.g., average highest or lowest hourly temperatures).

However, you have the option to generate extreme values corresponding to PoE 10 and PoE 90.

• PoE 10 (P10): This represents a scenario where only 10% of values of a parameter (e.g., yearly Global Horizontal Irradiance) are higher than the given one. In practical terms for Meteonorm, choosing PoE 10 for monthly averages of temperature and global irradiance will simulate a warm month with high solar irradiance.
• PoE 90 (P90): Conversely, this means 90% of all values of a parameter are higher than the given one. In Meteonorm, selecting PoE 90 for monthly averages of temperature and global irradiance will simulate a cold month with low solar irradiance.

These extreme values (PoE 10 and PoE 90) apply to both global irradiance and temperature together, and can be applied to both monthly averages and yearly averages:

• Yearly averages: Applying PoE 10 or PoE 90 here means you are generating a year with a statistical probability of occurring once in a decade (e.g., the warmest or coldest year in a 10-year period).
• Monthly averages: If you apply PoE 10 or PoE 90 to monthly averages, it implies that every single month in the year corresponds to that extreme (e.g., every month is a PoE 10 warm month). This is a very strong assumption and statistically highly unlikely to happen in reality.

It is important to note that within the context of Meteonorm, "P" is used interchangeably with "PoE" (Probability of Exceedance). This aligns with common usage in the solar and wind power industries, which differs from a purely statistical context where "P" typically refers to a percentile

Extremes can be selected by setting the extreme_setting query parameter in the /climate/tmy endpoint.