Ensemble reanalysis of regional temperature variability and teleconnection impacts in Odisha

Understanding regional-scale temperature variability is essential for climate assessment in vulnerable regions such as eastern India. This study examines long-term trends, spatial variability, and large-scale climatic associations of near-surface air temperature over Odisha during 1980–2020 using a multi-reanalysis ensemble constructed from the Indian Monsoon Data Assimilation and Analysis (IMDAA), ERA5, and the MERRA-2 datasets. The ensemble was developed at a common 0.5° spatial resolution and evaluated against gridded observations from the India Meteorological Department (IMD). Trends in mean (Tmean), maximum (Tmax), and minimum (Tmin) temperatures were analyzed using the Modified Mann–Kendall (MMK) test with autocorrelation correction, and magnitudes were estimated using Sen's slope. Spatial analyses indicate predominantly positive trends in Tmean and Tmax across most of Odisha, suggesting widespread daytime warming. Temporal analysis shows modest warming rates of ~0.1–0.3 °C decade⁻¹, stronger over interior regions than coastal areas. In contrast, Tmin exhibits weaker and spatially heterogeneous behavior, with statistically significant cooling detected only in the North Interior region. Empirical Orthogonal Function (EOF) analysis shows that variability is dominated by a leading large-scale mode, while secondary modes capture regional differences. Teleconnection analysis suggests modest linear associations with large-scale climate drivers, including the El Niño–Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and All-India Summer Monsoon Rainfall (AISMR), whereas Tmin shows weak and statistically non-significant relationships. These results provide a baseline assessment of regional temperature variability over Odisha, supporting climate-resilient planning and sustainable development initiatives in this environmentally vulnerable region.