Nikolov et al. (2025) Contemporary Tendencies in Snow Cover, Winter Precipitation, and Winter Air Temperatures in the Mountain Regions of Bulgaria

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Identification

• Journal: Climate
• Year: 2025
• Date: 2025-10-11
• Authors: Dimitar B. Nikolov, Cvetan Dimitrov
• DOI: 10.3390/cli13100212

Research Groups

Not explicitly mentioned in the provided text, but the study implies a national Bulgarian research effort focused on its mountainous regions.

Short Summary

This study addresses a national knowledge gap by systematically investigating snow conditions in Bulgarian mountains from 1961 to 2020, revealing mixed trends for snow depth and precipitation but a predominant and significant increase in mean winter air temperature, particularly between 1000 meters and 1700 meters altitude.

Objective

• To fill the national knowledge gap regarding snow conditions (snow depth maximums, mean air temperatures, and precipitation amounts) in the mountainous regions of Bulgaria.

Study Configuration

• Spatial Scale: Bulgarian mountains, utilizing data from 31 meteorological stations with altitudes ranging from 527 meters to 2925 meters above sea level.
• Temporal Scale: 60-year period from 1961 to 2020, covering the winter season (October to April), with a primary focus on December, January, and February.

Methodology and Data

• Models used: Statistical analysis including trend analysis, change point detection, and nonlinear fitting approaches.
• Data sources: Ground-based observational data from 31 meteorological stations, providing measurements of snow cover maximums, mean air temperatures, and precipitation amounts.

Main Results

• Snow Depth Maximums: Most stations showed no significant trends. Significant increases were observed at three lower stations in central west Bulgaria, while two of the highest stations demonstrated notable decreases.
• Precipitation Amounts: Trends were predominantly indefinite. Significant decreasing trends were found at the three highest alpine stations.
• Mean Seasonal Air Temperature: A predominant positive trend was observed, with 17 stations showing positive trends and 12 of these increases being statistically significant. The strongest seasonal temperature rise occurred at altitudes between 1000 meters and 1700 meters.
• Change Points: Nonlinear analysis revealed general changes in the investigated characteristics occurring from the beginning of the 1970s to the middle of the 1980s.

Contributions

• Provides the first systematic and up-to-date study on snow conditions in Bulgarian mountains, addressing a significant national knowledge gap.
• Utilizes a long-term dataset (60 years) across a wide altitudinal range to analyze trends in snow depth, precipitation, and air temperature.
• Identifies specific altitudinal bands (1000 meters to 1700 meters) experiencing the strongest seasonal temperature increases.
• Incorporates change point analysis and nonlinear approaches to better understand the temporal evolution of snow-related variables.

Funding

Not explicitly mentioned in the provided text.

Citation

@article{Nikolov2025Contemporary,
  author = {Nikolov, Dimitar B. and Dimitrov, Cvetan},
  title = {Contemporary Tendencies in Snow Cover, Winter Precipitation, and Winter Air Temperatures in the Mountain Regions of Bulgaria},
  journal = {Climate},
  year = {2025},
  doi = {10.3390/cli13100212},
  url = {https://doi.org/10.3390/cli13100212}
}