Spatio‐Temporal Analysis of Pan Evaporation in Iran Using Quantile Trend Regression and Mann‐Kendall Methods

Abstract Trends in pan evaporation are regarded as indicators for studying climate change. This study analyzed the spatial and temporal changes in pan evaporation (PE) from 130 stations with at least 40 years of data in Iran. For this purpose, the quantile trend method at the 10th, 50th and 90th qua...

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Main Authors: Ahmad Reza Ghasemi, Marziyeh Esmaeilpour
Format: Article
Language:English
Published: American Geophysical Union (AGU) 2025-03-01
Series:Earth and Space Science
Subjects:
Online Access:https://doi.org/10.1029/2024EA003933
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author Ahmad Reza Ghasemi
Marziyeh Esmaeilpour
author_facet Ahmad Reza Ghasemi
Marziyeh Esmaeilpour
author_sort Ahmad Reza Ghasemi
collection DOAJ
description Abstract Trends in pan evaporation are regarded as indicators for studying climate change. This study analyzed the spatial and temporal changes in pan evaporation (PE) from 130 stations with at least 40 years of data in Iran. For this purpose, the quantile trend method at the 10th, 50th and 90th quantiles, along with the Mann‐Kendall and Sen's slope methods, were employed. The findings revealed that, on average, significant negative and positive trends changed by 16.4 and 17.8 mm/decade, respectively. The most significant negative trends were observed near water bodies in the north and south of Iran. Meanwhile, air temperatures increased significantly from 0.20 to 0.28°C/decade in the north and from 0.13 to 0.24°C/decade in the south. This rise in temperature led to a corresponding increase in specific humidity, which could reduce pan evaporation. The quantile trend analysis showed that, at stations with significant negative trends, the monthly high evaporation values generally decreased (−3.3 to −11 mm/decade) more than the monthly low evaporation values (−2.2 to −6.5 mm/decade). Conversely, at significant positive trends, the slopes in low evaporation values (2.0–6.7 mm/decade) exceeded those in high evaporation (1.8–4.0 mm/decade). On the seasonal time scale the reduction in pan evaporation during summer was more than in spring. Forthermore, the results suggested that the evaporation paradox in the western and northwestern regions was more pronounced than in other areas.
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spelling doaj-art-3633e4724fee4d7f8c2ea6a7cc4543a32025-08-20T03:47:13ZengAmerican Geophysical Union (AGU)Earth and Space Science2333-50842025-03-01123n/an/a10.1029/2024EA003933Spatio‐Temporal Analysis of Pan Evaporation in Iran Using Quantile Trend Regression and Mann‐Kendall MethodsAhmad Reza Ghasemi0Marziyeh Esmaeilpour1Department of Water Engineering Shahrekord University Shahrekord IranDepartment of Geography and Urban Planning University of Maragheh Maragheh IranAbstract Trends in pan evaporation are regarded as indicators for studying climate change. This study analyzed the spatial and temporal changes in pan evaporation (PE) from 130 stations with at least 40 years of data in Iran. For this purpose, the quantile trend method at the 10th, 50th and 90th quantiles, along with the Mann‐Kendall and Sen's slope methods, were employed. The findings revealed that, on average, significant negative and positive trends changed by 16.4 and 17.8 mm/decade, respectively. The most significant negative trends were observed near water bodies in the north and south of Iran. Meanwhile, air temperatures increased significantly from 0.20 to 0.28°C/decade in the north and from 0.13 to 0.24°C/decade in the south. This rise in temperature led to a corresponding increase in specific humidity, which could reduce pan evaporation. The quantile trend analysis showed that, at stations with significant negative trends, the monthly high evaporation values generally decreased (−3.3 to −11 mm/decade) more than the monthly low evaporation values (−2.2 to −6.5 mm/decade). Conversely, at significant positive trends, the slopes in low evaporation values (2.0–6.7 mm/decade) exceeded those in high evaporation (1.8–4.0 mm/decade). On the seasonal time scale the reduction in pan evaporation during summer was more than in spring. Forthermore, the results suggested that the evaporation paradox in the western and northwestern regions was more pronounced than in other areas.https://doi.org/10.1029/2024EA003933evaporation paradoxIranMann‐Kendall testquantile trend analysis
spellingShingle Ahmad Reza Ghasemi
Marziyeh Esmaeilpour
Spatio‐Temporal Analysis of Pan Evaporation in Iran Using Quantile Trend Regression and Mann‐Kendall Methods
Earth and Space Science
evaporation paradox
Iran
Mann‐Kendall test
quantile trend analysis
title Spatio‐Temporal Analysis of Pan Evaporation in Iran Using Quantile Trend Regression and Mann‐Kendall Methods
title_full Spatio‐Temporal Analysis of Pan Evaporation in Iran Using Quantile Trend Regression and Mann‐Kendall Methods
title_fullStr Spatio‐Temporal Analysis of Pan Evaporation in Iran Using Quantile Trend Regression and Mann‐Kendall Methods
title_full_unstemmed Spatio‐Temporal Analysis of Pan Evaporation in Iran Using Quantile Trend Regression and Mann‐Kendall Methods
title_short Spatio‐Temporal Analysis of Pan Evaporation in Iran Using Quantile Trend Regression and Mann‐Kendall Methods
title_sort spatio temporal analysis of pan evaporation in iran using quantile trend regression and mann kendall methods
topic evaporation paradox
Iran
Mann‐Kendall test
quantile trend analysis
url https://doi.org/10.1029/2024EA003933
work_keys_str_mv AT ahmadrezaghasemi spatiotemporalanalysisofpanevaporationiniranusingquantiletrendregressionandmannkendallmethods
AT marziyehesmaeilpour spatiotemporalanalysisofpanevaporationiniranusingquantiletrendregressionandmannkendallmethods