E-ISSN 3033-179X

Blagoevgrad, Bulgaria

Spatiotemporal Analysis of Surface Air Temperature in Bulgaria (1950–2024) Based on ERA5-Land Data and Google Earth Engine

Miroslav Ivanov1, Vladimir Karadzhov2, Emilia Patarchanova3, Veselina Dalgacheva4

1,2,3,4 Department of Geography, Ecology, and Environmental Protection, Faculty of Mathematics and Natural Sciences, South-West University “Neofit Rilski” – Blagoevgrad

ORCID IDs: 1 0000-0002-2347-8029, 2 0000-0002-7514-5517, 3 0000-0002-1806-557X, 4 0000-0002-1976-5367

Corresponding Author: Miroslav Ivanov, m_ivanov@swu.bg

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https://doi.org/10.63711/ijdr.net20250410


ABSTRACT

This study examines the spatiotemporal dynamics of surface air temperature change in Bulgaria for the period 1950–2024, with particular emphasis on the accelerating warming trends observed during the last two decades. Using data from the ERA5-Land reanalysis and Stefan Velev’s climatic regionalization, the analysis demonstrates that Bulgaria is warming significantly faster than the global terrestrial average. Over the full seventy-five-year period, decadal warming rates ranged between 0.32 °C and 0.48 °C. However, a comparative assessment reveals a pronounced acceleration during the most recent sub-period (2005–2024), when warming rates nearly doubled, reaching between 0.60 °C and 0.85 °C per decade. This intensification culminated in 2024, which registered a national mean temperature approximately 2.1 °C above climatic norms, making it the warmest year in Bulgaria since the beginning of instrumental records in 1930. Regional results indicate that the Moderate Continental and Transitional Continental zones act as primary “heat engines,” while high-altitude mountainous regions exhibit elevation-dependent warming driven by snow–albedo feedback mechanisms. Statistical validation using the Mann–Kendall test confirms a systemic shift beginning around the 1987 climatic breakpoint, after which extreme heat events have become increasingly frequent. These findings identify Bulgaria as a critical climate hotspot in Southeastern Europe and underscore the urgent need for targeted adaptation strategies in agriculture, water resource management, and urban planning.

Keywords: Climate acceleration, Bulgaria, Surface air temperature, ERA5-Land, Remote sensing

Research Area: Climate Change, Remote Sensing, Environmental Analysis

Copyright © 2025 The Author(s). This article is licensed under CC BY 4.0. 

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