Data sources and references

Poland's national meteorological and hydrological institute. KLIMAT-P uses real-time synoptic station readings from the IMGW-PIB open data programme, covering temperature, wind, precipitation, humidity and pressure across the Polish station network. Readings are published approximately hourly.

Published 30-year climatological baseline (1991–2020) for Polish regions, used as the reference period for all anomaly computations. This is the WMO-standard reference period adopted by meteorological services worldwide for the current generation of climate normals.

Monthly NAO index, standardised. The NAO is the dominant mode of atmospheric variability over the North Atlantic and is one of the primary large-scale signals influencing precipitation and temperature patterns over Poland. Positive NAO phases are associated with warm, dry conditions in central Europe; negative phases with cold, wet patterns.

Monthly AO index, standardised. The Arctic Oscillation describes the dominant pattern of non-seasonal sea-level pressure variations north of 20°N latitude. It influences the strength of westerly winds and affects the position of storm tracks across Europe.

Three-month running mean of sea surface temperature anomalies in the Niño 3.4 region (5°N–5°S, 120°–170°W), used as the standard ENSO indicator. ENSO phase influences seasonal temperature and precipitation patterns across Europe through teleconnection pathways, typically with a 1–3 month lag.

The primary accuracy metric used to evaluate KLIMAT-P probability estimates. For each prediction, the Brier Score computes (predicted probability − actual outcome)². A perfect score is 0.0; a naive model that always predicts 50% scores 0.25. The score is computed automatically each week using actual IMGW station observations as ground truth.

KLIMAT-P follows WMO guidelines for the construction and communication of probabilistic forecasts, including the use of the 1991–2020 standard reference period for climatological anomaly calculations and the calibration of probabilistic outputs against historical observations.

The primary Polish climatological reference atlas published by IMGW-PIB. Used as a secondary source for regional temperature and precipitation characteristics across Polish voivodeships, supplementing the 1991–2020 normals for regional model configuration.

A key methodological reference for the Bayesian approach used in KLIMAT-P's probability updating framework. The paper describes how prior seasonal climate probabilities can be updated using observed anomalies and large-scale atmospheric indices.

Provides the theoretical basis for using multiple independent signals (station anomalies, teleconnection indices, historical analogs) in combination rather than relying on a single predictor — a core principle of the KLIMAT-P model design.