Thermo-hygrometric characteristics of Local Climate Zones (LCZs) in the primary urban areas of north-eastern Romania investigated through multivariate tools

In this research, we outline the main thermo-hygrometric characteristics of local climate zones (LCZs) identified in four of the largest cities in north-eastern Romania (Iași, Bacău, Botoșani, and Suceava), which together have a population of over 1 million inhabitants. The urban structure of these cities could be considered typical for medium size cities in Eastern Europe, being characterized by their recent development, with residential and industrial areas developed intensively in the communist period, followed nowadays by the conversion of decaying industrial areas in commercial units and a new phase of largely unorganized residential expansion.

We used the LCZ Generator to assess local climate zones in these cities, resulting in the identification of eight LCZs, with the largest extension being specific to compact midrise and open midrise, covering approximately 40% of the cities' surface. The accuracy of the LCZ delimitation ranges from 0.80 to 0.90.

We described the thermo-hygrometric features within the identified LCZs using in-situ observations, mobile measurements, and LANDSAT LST products. We used 30 in-situ observation points for air temperature and humidity with hourly temporal resolution to describe the major features of LCZs. We also made two mobile measurements monthly between May 2022 and April 2023 for each city, during clear sky conditions, in the early morning and the first part of the night, in order to spatially cover the diversity of LCZs. The thermo-hygrometric profile of LCZs was completed with LANDSAT LST data analyzed for 1983-2021, enabling a multiannual trend analysis of the two main LCZs in the analyzed cities. 

We grouped the study results by advective and radiative conditions using a Self-Organizing Maps method for atmospheric circulation. We also explored the thermo-hygrometric features of the two main LCZs using EUROCORDEX data for 2025-2100. The main output of this analysis indicates that the magnitude of changes identified in either moderate or extreme climate scenarios overwhelms the differences observed nowadays between the current conditions imposed by each local climate zone.

The results of this study synthesize the progress made in assessing urban climate conditions in the cities of North-Eastern Romania, in the framework of UCLAR project, and are intended to serve as a basis for mitigation policies to be developed by local and regional stakeholders for the sustainable development of these cities in the actual context of climate change. 

Acknowledgement: This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CNCS - UEFISCDI, project number PN-III-P1-1.1-TE-2021-0882, within PNCDI III.