Citation: Piticar, A.;Andrei, S.; Tudor, A. Spatiotemporal Variability of Convective Events in Romania Based on METAR Data. Sustainability 2024, 16, 3243. https://doi.org/ 10.3390/su16083243 Academic Editor: Shenming Fu Received: 20 February 2024 Revised: 26 March 2024 Accepted: 10 April 2024 Published: 12 April 2024 Copyright: © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). sustainability Article Spatiotemporal Variability of Convective Events in Romania Based on METAR Data Adrian Piticar 1, *, Simona Andrei 2 and Alexandru Tudor 1,3 1 Faculty of Aeronautical Management, “Henri Coandă” Air Force Academy, 500187 Bra¸ sov, Romania; alexandru.tudor@afahc.ro 2 National Institute of Research and Development for Optoelectronics INOE2000, 077125 Măgurele, Romania; simona.andrei@inoe.ro 3 Faculty of Geography, Babe¸ s-Bolyai University, 400006 Cluj Napoca, Romania * Correspondence: adrian.piticar@afahc.ro Abstract: Convective weather, through its heavy showers, strong winds and hail, significantly impacts human activities, having the potential to inflict serious damage on social and environmental sectors. Limited research has been conducted on this phenomenon within Romanian territory, and currently there is no referenced climatological study primarily aimed at air traffic management users in this context. This study aims to assess the climatological aspects related to convective events based on sub-hourly observation data recorded at 17 airport weather stations throughout Romania during an 11-year period (2012–2022). The spatiotemporal distribution of convective events was analyzed based on occurrences of Cumulus Congestus (TCU) clouds, Cumulonimbus (CB) clouds, thunderstorms (TSs), heavy showers (+SHs), and hail (GR). With the data being extracted from meteorological aerodrome reports (METARs) and special meteorological aerodrome reports (SPECIs). Short-term trends were determined using Sen’s slope estimator, and statistical significance was assessed through the Mann–Kendall test. The main findings indicated that the highest occurrence of convective events is located over central and western Romania, with June emerging as the extreme month in terms of convective events, while the hourly distribution emphasizes that the highest frequency of convective events occurred in the afternoon. Trend analysis in TCU, CB, and TS show tendencies toward higher frequency of convective events while the results related to +SH and GR indicate a high variability across Romanian territory. Trend analysis disclosed more substantial changes in the TS variable. The results of this study bear potential significance for a broad spectrum of human activities and the management of natural environments. Keywords: climate change; convective weather; METAR; SPECI; Romania 1. Introduction Convective weather has a substantial influence on human activities, generating heavy showers, strong winds, and hailfalls, with the potential to cause serious damages to social and environmental sectors. Moreover, severe convective weather possesses strong destructive power, significantly exacerbating economical losses [1]. For instance, convective events can severely damage crops and affect the supply of electricity, communications, and air traffic [2]. This type of weather poses a serious risk to aircraft flights through associated hazardous phenomena [3]. Furthermore, convective weather is affected by the ongoing climate change, which can significantly increase its impact on society and the environment [4–6]. However, different sustainable measures and concepts for protection should be regularly developed based on the newest scientific results. Convective weather is quite frequent during the warm season (April–September) in temperate regions of the globe [7–10]. The main elements for convection development in- clude a high amount of moisture in the lower and mid-atmosphere, atmospheric instability, Sustainability 2024, 16, 3243. https://doi.org/10.3390/su16083243 https://www.mdpi.com/journal/sustainability