Climate Atlas of extremes in Catalonia (1991-2020)

As we acknowledge the increasing frequency, broader distribution, and heightened intensity of extreme weather events due to climate change, it becomes crucial to gain a deeper understanding of their behaviour. These extreme events have significant societal impacts, requiring better knowledge and tools for assessment.The Climate Atlas of Extremes in Catalonia, covering the period from 1991 to 2020, serves as a vital reference tool. It provides valuable information to government bodies, regional authorities, businesses, and citizens about the specific characteristics of climate extremes in Catalonia over the past three decades.In this study, we present the methodology behind the creation of the Catalonia Climate Extremes Atlas. Our goal is to provide a comprehensive analysis of extreme climate events in the Catalonia territory. We will present the key steps involved in this process.Data Preparation: we collect and preprocess daily climate data, including mean, maximum, and minimum temperatures, as well as precipitation records. Rigorous quality control procedures are applied to ensure data accuracy. Homogeneity analysis: artificial biases in the data series are addressed using the ACMANTv5 method. This step ensures that the dataset accurately represents the true climate conditions. To obtain descriptive indices to evaluate extreme events, we utilize the CLIMPACT tool (https://climpact-sci.org/indices/). These indices were defined by the joint CCl/CLIVAR/JCOMM Expert Team (ET) on Climate Change Detection and Indices (ETCCDI) and provide valuable insights into extreme weather phenomena. Digital cartography: we interpolate extreme normals to create georeferenced climate data on a regular grid. The resulting high-resolution digital cartography includes precipitation indices mapped at a 1-kilometer resolution, and temperature indices mapped at a 100-meter resolution. Different time scales (monthly, seasonal, and annual) are considered based on relevance. The extreme normals will be freely accessible through the SIG portal of the Government of Catalonia (https://sig.gencat.cat/visors/hipermapa.html). Ongoing research involves trend calculations and statistical approaches. We will compare different periods of extremes and assess changes. Additionally, we plan to compare our findings with model-projected changes in the same extremes.