Document Type : Research Paper
Authors
1
Faculty Member, Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran
2
PhD student in climatology at the Faculty of Social Sciences, University of Mohaghegh Ardabili , Ardabil, Iran.
3
Faculty Member, Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran.
10.22034/gp.2026.68560.3440
Abstract
Fog, a critical meteorological phenomenon, plays a supplementary role in meeting vegetation water demands during the summer season, particularly in areas with minimal or absent precipitation. This study examines the temporal behavior of foggy days in the eastern region of Ardabil over a two-decade span from 2003 to 2022, focusing specifically on summer months. Given the unavailability of a synoptic station within the defined spatial scope, MODIS satellite data were utilized to detect fog occurrence. To evaluate temporal trends, non-parametric statistical tools—namely the Mann-Kendall test and Sen’s slope estimator—were applied. The findings indicate that, on average, summer experiences approximately 20 foggy days. The Mann-Kendall test for the summer season yielded a Z value of 0.43, suggesting no statistically significant trend in foggy days at the 95% and 99% confidence levels. Similarly, Sen’s slope estimator produced a Q value of zero, indicating no meaningful increasing or decreasing trend at these confidence levels. The graphical Mann-Kendall test also confirmed the absence of a statistically significant trend at the 95% confidence level. It is noteworthy that the repeated intersection of two curves within the ±1.96 range implies that the average number of foggy days varies annually during summer. The Sen’s slope trend line appears flat, with an R² of zero, reinforcing the conclusion that no significant trend exists in the number of foggy days during summer in eastern Ardabil Province.
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