Document Type : Research Paper

Authors

• Reza Norooz-Valashedi ¹
• Mohammadreza Noroozian-Rostami ²

¹ Department of Water Engineering, Faculty of Agricultural Engineering, University of Sari Agricultural Sciences and Natural Resources, Sari, Iran

² Department of Water Engineering, Faculty of Agricultural Engineering, Sari University of Agricultural Sciences and Natural Resources

Abstract

Mountain snow, as a key component of the hydrological cycle, plays a crucial role in supplying both surface and subsurface water resources. This study employed an ecohydrological approach and remote sensing data to investigate the impact of black carbon (BC) pollution on snow surface albedo in the Alborz Mountains at elevations above 2000 meters during 2000–2024. Albedo data were obtained from the MOD10A1 V6.1 product, and BC data from the MERRA-2 reanalysis. Statistical analyses, including linear regression and the Generalized Additive Model (GAM), were conducted to examine temporal and monthly relationships between these variables. Results revealed a significant negative correlation between BC concentration and snow albedo during winter and early spring, highlighting the direct role of pollutants in reducing reflectivity and accelerating snowmelt. GAM results showed a nonlinear relationship between BC concentration and albedo sensitivity: sensitivity increased when BC exceeded 0.38 µg/m² but declined after reaching a saturation point of 0.45 µg/m². This identifies a critical BC concentration range of 0.40–0.50 µg/m², where snow albedo experiences the greatest reduction. Additionally, temporal trends indicated a significant increase in BC for most months and a continuous decline in albedo during cold periods. Factor analysis further demonstrated that, although the temperature–moisture factor remained stable over many years, increasing fluctuations in the pollution–radiation factor over the past decade have been the main driver of early snowmelt.

Keywords

• Albedo
• Black Carbon
• Generalized Additive Model
• Factor Analysis
• Snow Reserves