Classification of convective episodes in different climatic zones

The study of precipitation due to convective phenomena is one of the most challeging tasks in climate and meteorological research and especially from the perspective of collected surface precipitation since they can lead to natural disasters in various regions, impacting entire populations. This work aims to classify convective phenomena after identifying them based on a methodology that separates precipitation components into convective and stratiform.

Based on statistical properties of precipitation, a threshold value, or critical precipitation ratio, has been computed in order to classify every precipitation event into a stratiform or convective episode. The criterion to identify a convective phenomenon consists of knowing if rain rate exceeds such critical value. Rain events, particularly convective ones, may vary in intensity, duration, and frequency depending on the climatic zone, and thus they will be categorized according to these areas.

To conduct this study, precipitation data, both hourly and daily measurements, from surface rain gauge stations have been utilized. These data cover all of Peninsular Spain and Balearic Islands from 1998 to 2023 and have been provided by Aemet (the Spanish Meteorological Agency).

Previous findings indicate that convective episodes occur less frequently in the Eastern Iberian Peninsula compared to the Cantabrian area. However, they exhibit shorter duration and higher maximum rainfall intensity in the former. Despite these variations, the accumulated precipitation amounts per episode and per station are similar in both regions. Furthermore, it is noted that the number of rain gauge stations affected by convective phenomena is greater in the Cantabrian area, suggesting a broader distribution of these episodes in the northwest of Spain. It hints at potential atmospheric and geographical factors influencing convective processes in different parts of Spain.