CIMAs: A multi-source climate dataset for high-mountain environments in the Iberian Central System

The Climate research initiative for Iberian Mountain Areas (CIMAs) is a collaborative framework involving several Spanish institutions: the Spanish Meteorological Office (AEMET), Complutense University of Madrid (UCM), Institute of Geosciences (IGEO, CSIC-UCM) and CIEMAT. The main goal of the initiative is to advance the characterization and understanding of climate variability and change in the Central System of the Iberian Peninsula. Mountain regions are particularly sensitive to climate change, however observational data in these environments remain scarce, heterogeneous and difficult to maintain. CIMAs addresses this challenge by integrating multi-source meteorological datasets from institutions with different measurement protocols, temporal resolutions and data formats, such as AEMET, the Guadarrama Monitoring Network (GuMNet), the Portuguese Meteorological Office (IPMA), hydrological agencies operating Automatic Hydrological Information Systems in Spain (SAIH Duero, SAIH Tajo) and the Portuguese National Water Resources Information System (SNIRH). In this work, the development of the CIMAs observational database is presented. The workflow includes harmonization of formats and units, metadata consolidation, systematic quality control, temporal aggregation and a version-controlled architecture that ensures traceability and facilitates future updates. The temperature and precipitation databases are currently operational, incorporating station records distributed across Spain and Portugal. As part of the evaluation of the current data releases, spatial summaries of data availability and temporal coverage are also presented, together with preliminary climatological fields used to assess the internal consistency of the integrated datasets. The system additionally provides web-based tools for data visualization and access. Ongoing developments include the integration of wind and snow products and the coupling of the observational database with simulations. The CIMAs framework provides a structured and interoperable basis for integrating climate observations across high-mountain areas of the Iberian Peninsula. Its aim is to improve data accessibility, consistency and usefulness for scientific and operational purposes. In addition, it offers an observational basis for assessing simulation performance and for the development of climate-service applications.