journal article Feb 09, 2026

Homogenisation and Trend Analysis of Sunshine Duration in Romania for the 1961–2024 Period

View at Publisher Save 10.1002/joc.70275
Abstract
ABSTRACT

The study presents the national‐scale homogenisation and trend analysis of sunshine duration (SD) observations across Romania for the period 1961–2024. Daily data from 153 weather stations operated by National Meteorological Administration of Romania were subjected to quality control, gap‐filling and homogenisation using the
climatol
R package. Outlier detection and Standard Normal Homogeneity Test (SNHT) identified 25 discontinuities, highlighting the importance of quality checks. Following homogenisation, about 52% of daily observations were adjusted or gap‐filled, yielding a consistent, long‐term SD dataset. Trend analysis was conducted with the Mann–Kendall test and Theil–Sen estimator on annual and seasonal scales. Results indicate a general increase in SD, with statistically significant positive trends in winter and spring, modest increases in summer and widespread negative but mostly non‐significant trends in autumn. Comparison with climate normal (1961–1990, 1971–2000, 1981–2010, 1991–2020) reveals coherence with internationally reported dimming, brightening and recent stabilisation phases, including European evidence. The homogenised dataset strengthens the reliability of detected trends, reducing artificial variability from instrumentation changes and measurement errors. Beyond scientific relevance, the dataset provides a robust reference for solar energy assessments, agriculture and climate services in Romania and offers a replicable workflow for homogenisation of other climatological variables in national networks.
Topics

No keywords indexed for this article. Browse by subject →

References
67
[2]
A homogeneity test applied to precipitation data

Hans Alexandersson

Journal of Climatology 10.1002/joc.3370060607
[12]
Copernicus Climate Change Service (2024)
[19]
Guijarro J. A. (2004)
[20]
Guijarro J. A. (2025)
[22]
Institutul Meteorologic (1965)
[23]
Kappler T. (2024)
[24]
Kendall M. G. (1975)
[26]
Kuya E. K. H. M.Gjelten andO. E.Tveito.2021.Homogenization of Norwegian monthly precipitation series for the period 1961–2018. No. MET Report 04/2021. Norwegian Meteorological Institute. 10.5194/ems2021-211
[32]
Nonparametric Tests Against Trend

Henry B. Mann

Econometrica 10.2307/1907187
[33]
Marin L. "An Overview of Annual Climatic Changes in Romania: Trends in Air Temperature, Precipitation, Sunshine Hours, Cloud Cover, Relative Humidity and Wind Speed During the 1961–2013 Period" Carpathian Journal of Earth and Environmental Sciences (2014)
[45]
Estimates of the Regression Coefficient Based on Kendall's Tau

Pranab Kumar Sen

Journal of the American Statistical Association 10.1080/01621459.1968.10480934

Showing 50 of 67 references

Metrics
0
Citations
67
References
Details
Published
Feb 09, 2026
Vol/Issue
46(5)
License
View
Funding
HORIZON EUROPE Climate, Energy and Mobility Award: 101081377
Cite This Article
Giorgiana‐Daiana Lüftner, Georgeta Bandoc, Elena Aurelia Țene, et al. (2026). Homogenisation and Trend Analysis of Sunshine Duration in Romania for the 1961–2024 Period. International Journal of Climatology, 46(5). https://doi.org/10.1002/joc.70275