Open Access

ARTICLE

A New Normalized Climate Index (U2) for Türkiye: Comparison with Classical Methods

Erdinç Uslan^1,*, Emin Ulugergerli²

1 Department of Risk Management of Natural Disasters, Canakkale Onsekiz Mart University, Canakkale, Türkiye
2 Geophysical Engineering, Canakkale Onsekiz Mart University, Canakkale, Türkiye

* Corresponding Author: Erdinç Uslan. Email:

Revue Internationale de Géomatique 2026, 35, 31-51. https://doi.org/10.32604/rig.2026.075081

Received 24 October 2025; Accepted 31 December 2025; Issue published 05 February 2026

Abstract

Climate classification systems are essential tools for analyzing regional climatic behavior, assessing long-term aridity patterns, and evaluating the impacts of climate change on water resources and ecosystem resilience. This study introduces a new Climate Classification Method based on uniform and unitless variables, referred to as the U2 Climate Classification (U2CC). The proposed U2 Index was designed to overcome structural limitations of the classical De Martonne (1942) and Erinç (1949) indices, which rely on raw precipitation–temperature ratios and are sensitive to extreme values, particularly subzero temperatures. The U2 methodology consisted of two key steps: (i) normalization of temperature and precipitation relative to their long-term provincial means, and (ii) restructuring of the climatic year to begin on 1 April, aligning the index with hydrological and agricultural cycles. This approach provided a more stable and comparable representation of climatic moisture balance across Türkiye. Using long-term meteorological observations covering the period 1927–2023 obtained from the Turkish State Meteorological Service, national-scale climate maps based on the U2 Index were produced and evaluated in comparison with the De Martonne and Erinç classifications. The results indicated that U2CC captured broad-scale climatic patterns consistent with established methods while providing improved representation of transitional climatic zones. Spatial patterns revealed increasing aridity across Central Anatolia associated with declining winter precipitation, whereas the Black Sea and southwestern coastal regions retained humid characteristics due to persistent maritime influence. Overall, the findings demonstrated that U2CC offered a refined and robust framework for climate zoning, agricultural planning, drought assessment, and sustainable water resource management under ongoing climate change conditions.

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