A multi-method and multi-duration trend analysis of temperature and precipitation in Istanbul, Turkey, by using meteorological records, MERRA-2 reanalysis, and IMERG estimations

In this study, temperature and precipitation trends in Istanbul were analyzed using data from a ground-based station for the 1960–2019 interval, Integrated Multi-SatellitE Retrievals for Global Precipitation Measurement (GPM IMERG) for 2000–2019, and Modern-Era Retrospective Analysis for Research and Applications (MERRA-2) temperature reanalysis for 1980–2019. Single-duration analysis revealed significant increasing temperature trends with minor downward and major upward tendencies in precipitation. Multi-duration analysis resulted with dominant decreasing and increasing temperature trends, respectively, in 1980–1999 and 2000–2019, alongside decreasing precipitation trends in 1980–1999 winter and 2000–2019 spring, which were undetected in the single-duration analysis. As a novel attempt, trends based on MERRA-2 and IMERG data were compared with ground-based records in Istanbul and revealed better compatibility in MERRA-2, especially in 2000–2019 compared to IMERG data. By comparing various statistical methods and data sources, this study offers valuable insights into hydrometeorological trend analysis and aids transition from conventional to novel data sources.