Document Type : Research Paper
Author
Department of Irrigation and reclamation, Faculty of Agriculture and Natural Resource, Tehran University, Karaj.Iran
Abstract
Keywords
Main Subjects
The Earth's climate system is a complex interplay among various geospheres—including the atmosphere, lithosphere, biosphere, hydrosphere, and cryosphere—each contributing significantly to the manifestation of climatic phenomena such as precipitation, snowfall, drought, pluvial conditions, and extreme weather events. Among the most consequential modulators of these dynamics are teleconnection patterns, which reflect large-scale atmospheric oscillations and circulation anomalies that shape regional to hemispheric weather conditions. One such prominent pattern is the Scandinavian Index (SCAND), a semi-permanent wave-train structure that exerts profound influences on synoptic-scale weather regimes, particularly across Eurasia, Europe, and parts of the Middle East.
The present study was designed to investigate the relationship between the SCAND teleconnection pattern and two critical climate parameters—precipitation and relative humidity—across 21 synoptic meteorological stations distributed across Iran’s diverse climatic regions. Specifically, the aim was to determine whether the SCAND index could significantly explain temporal variability in these parameters and to what extent these effects are spatially heterogeneous. This inquiry aligns with broader theoretical frameworks concerning atmospheric blocking, mid-latitude circulation variability, and moisture transport mechanisms. The findings have practical implications for seasonal forecasting, hydrological risk management, and climate impact assessments.
A mixed-methods research design was employed, integrating quantitative statistical analysis with interpretive climatological inference. The study utilized time-series climate data derived from synoptic weather stations across Iran in conjunction with the SCAND index values over a defined temporal window. Principal Component Analysis (PCA) was applied to discern dominant variance structures and identify the relative sensitivity of precipitation and relative humidity to the SCAND index. Pearson correlation analysis was used to determine the degree and directionality of relationships.
This approach enables both the statistical isolation of significant patterns and the interpretive linkage to underlying atmospheric dynamics, including the propagation of Rossby waves and the modulation of polar jet streams. The study also incorporated qualitative climatological synthesis to interpret the mechanistic role of upper-level circulation in mediating the teleconnection's surface-level impacts.
The selected 21 synoptic stations span diverse geographical and climatic zones of Iran, ensuring comprehensive spatial representation. Sampling was based on climatological zoning and data continuity. The temporal scope included multiple cold-season periods to capture the seasonal prominence of SCAND-related blocking events. Data collection adhered to standard meteorological protocols, and all datasets were quality-controlled using internationally accepted procedures for climatological research. Ethical considerations were not directly applicable due to the non-human subject nature of the data. However, institutional standards for data integrity, source attribution, and methodological transparency were strictly followed.
The results revealed spatially and temporally variable correlations between SCAND index phases and climatic parameters across Iran. The Rasht station exhibited the highest positive correlation with SCAND in terms of precipitation (r = 0.40), indicating a significant enhancement of moisture flux and convergence under positive SCAND phases. In contrast, the Kerman station demonstrated a relatively high correlation in relative humidity (r = 0.47), reflecting regional sensitivity to upper-tropospheric anticyclonic anomalies.
Interestingly, stations such as Tabriz and Yazd showed no statistically significant correlations between SCAND and relative humidity, suggesting either shielding from upper-level wave propagation or dominance of local-scale climatic controls. Moreover, the influence of polar front jet streams, modulated by SCAND-induced Rossby wave propagation, was markedly stronger across the northern synoptic stations. This asymmetry underlines the geographical specificity of SCAND's climatic imprint.
The findings substantiate the role of the Scandinavian teleconnection pattern as a significant driver of precipitation and humidity variability across Iran, particularly during the cold season. The implications extend to the realms of seasonal climate forecasting and long-range hydrometeorological modeling. The study underscores the necessity of integrating teleconnection indices such as SCAND into predictive climate models, especially in the context of global warming, which is poised to alter the frequency and intensity of blocking patterns and wave dynamics. Future research should adopt a scenario-based modeling framework to assess the evolution of SCAND-climate relationships under projected warming trajectories. Given the central role of sea surface temperature anomalies in modulating teleconnection strength, the integration of coupled ocean-atmosphere models is recommended. The value of a mixed-methods approach is highlighted by the capacity to triangulate statistical relationships with synoptic-scale process understanding, thereby yielding richer insights than either approach alone.
Mr. SaadatMoghaddasi: Gathering the experimental data, Data curation, Software; Methodology; Investigation, Conceptualization, Methodology, Writing-Reviewing and Editing, Formal analysis, Analyzing the experimental data.
Data available on request from the author.
The research was supported by the University of Tehran. The author would like to express their special thanks to the vice chancellor for research affairs. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
The author avoided data fabrication, falsification, plagiarism, and misconduct.
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