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Showing 42 results for حجازی زاده

Zahra Hedjazizadeh, Al Karbalaee, Mokhtar Fatahian,
Volume 26, Issue 80 (3-2026)
Abstract

This study investigates the spatial dynamics of the subtropical anticyclone over Iran during boreal summer, using daily ERA5 reanalysis data (1980–2020) and the Getis-Ord Gi* statistic to identify statistically significant hotspots (p < 0.01) in 500-hPa geopotential height (Z500) anomalies for June–August. Results reveal that the peak statistical hotspot occurs in July: a prominent warm cluster with Z-scores up to +4.1 (99% confidence level) forms over southwestern Iran (27°–32°N, 48°–60°E), reflecting the strongest positive departure from the long-term Z500 climatology. Conversely, a cold cluster with Z-scores reaching −10.2 emerges over the northwest (West Azerbaijan and Kurdistan provinces) the lowest value recorded over the entire period indicating pronounced geopotential depression driven by the orographic influence of the Alborz–Zagros ranges and incursions of mid-latitude systems. Histogram analysis of Z-scores confirms a distinctly bimodal distribution in July, with high frequencies in the [+2.5, +4.1] and [−10.2, −2.5] ranges and a pronounced trough near Z ≈ 0, underscoring strong spatial segregation between warm and cold clusters. Notably, the eastern half of Iran (central and eastern regions) consistently lacks significant hotspots across all three months, suggesting the presence of a dynamic transition zone shaped by the competition between subtropical and mid-latitude circulations. In August, although absolute Z500 exceeds 5890 m, the Z-score diminishes (+4.0), indicating that cumulative surface heating elevates the mean geopotential height but its anomalous intensity relative to climatology weakens compared to July. Collectively, these findings suggest that the dynamical peak of the Iranian subtropical high lags the peak of surface heating by approximately one month.

Ms Atefeh Bosak, Dr Zahra Hejazizadeh, Dr Akbar Heydari Tashekaboud,
Volume 26, Issue 81 (6-2026)
Abstract

Air pollution has significant impacts on human health, environmental quality, and the sustainable development of cities. This study aimed to evaluate PM10 using meteorological data from the city of Ahvaz through statistical methods and artificial neural networks. Daily meteorological data and air quality control station data for 4485 days (from 2011 to 2023) were obtained from the National Meteorological Organization and the Khuzestan Department of Environment. Initially, the data were processed and refined, and their normality was assessed using the Kolmogorov-Smirnov test. Given the non-normality of the data, Spearman's and Kendall's Tau-b methods were employed to examine their correlations. The time series and statistical information of the data were obtained using Python programming language. Furthermore, to predict future PM10 levels, the Multilayer Perceptron (MLP) neural network method was utilized. The results of these analyses indicated a significant correlation between meteorological variables and PM10. The Spearman and Kendall Tau-b correlations showed that PM10 had a positive and significant correlation with wind speed (0.094 and 0.061) and temperature (0.284 and 0.187) at a 99% confidence level. Conversely, PM10 exhibited a negative and significant correlation with visibility (-0.408 and -0.300), wind direction (-0.048 and -0.034), precipitation (-0.159 and -0.125), and relative humidity (-0.259 and -0.173) at the 99% confidence level. For future PM10 predictions, the MLP neural network was used. The model was of the Sequential type with an input layer consisting of 6 neurons, three hidden layers of Dense type with 16, 32, and 64 neurons, and an output layer with a linear activation function. The mean squared error (MSE) for the training set was 0.0034, and for the validation data, it was 0.0012. For the test set, the obtained validation accuracy was mse_mlp=0.0048 and val_loss=0.0012. The results indicate a significant direct or inverse correlation between meteorological data and PM10. Additionally, the outcomes of the MLP neural network demonstrated that the network provided satisfactory performance and acceptable predictions for PM10 data in Ahvaz.


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