Spatial verification of global precipitation forecasts

Skok, Gregor (author), Lledó, Llorenç (author)

Verification of global high-resolution precipitation forecasts is challenging. Spatial verification techniques address some shortcomings of traditional verification. However, most existing methods do not account for the non-planar geometry of a global domain, or their computational complexity is too large for global assessments. We present an adaptation of the recently developed precipitation attribution distance (PAD) metric, designed for verifying precipitation, enabling its use on the Earth’s spherical geometry. PAD estimates the magnitude of location errors in the forecasts employing the mathematical theory of optimal transport, as it provides a close upper bound for the Wasserstein distance. The method is fast and flexible with time complexity O(n log(n)). Its behavior is analyzed using idealized cases and 7 years of operational global deterministic six-hourly precipitation forecasts from the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts. The summary results for the whole period show how location errors in the IFS model grow steadily with increasing lead time for all regions analyzed. Moreover, by examining the time series of the results, we can determine the trends in the score’s value and identify the regions where there is a statistically significant improvement (or worsening) of the forecast performance. The results can also be analyzed separately for different intensities of precipitation. Overall, the PAD provides meaningful results for estimating location errors in global high-resolution precipitation forecasts at an affordable computational cost.

• Language: English
• Keywords: meteorology, precipitation, verification, displacement error, distance metrics, global domain, optimal transport, spatial verification
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 23 str.
• Numbering: Vol. 151, iss. 771, pt. B, art. e5006
• PID: 20.500.12556/RUL-176706
• UDC: 551.577
• ISSN on article: 0035-9009
• DOI: 10.1002/qj.5006
• COBISS.SI-ID: 235697411
• Publication date in RUL: 09.12.2025

Record is a part of a journal

• Title: Quarterly journal of the Royal Meteorological Society
• Shortened title: Q. j. R. Meteorol. Soc.
• Publisher: Wiley, Royal Meteorological Society
• ISSN: 0035-9009
• COBISS.SI-ID: 26227200

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: meteorologija, padavine, verifikacija

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P1-0188
• Name: Astrofizika in fizika atmosfere

• Funder: EC - European Commission