The relationship between the large-scale relative vorticity fields and precipitation over Iran

IF 2.6 4区环境科学与生态学 Q2 WATER RESOURCES

Hydrology Research Pub Date : 2023-10-12 DOI:10.2166/nh.2023.301

Azita Amiri, Bohloul Alijani, Ebrahim Fattahi, Maral Habibi

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Abstract

Abstract This study examines the relationship between relative vorticity, a key variable in mid-latitude synoptic motions, and precipitation in Iran. Using the S-mode PCA, activity centers of relative vorticity and precipitation were identified. Canonical correlation analysis (CCA) was applied to the factor scores of these centers to reveal coupled patterns of relative vorticity and precipitation. The analysis is based on 500- and 850-hPa relative vorticity fields at 2.5° grid points (10°–70° E and 10°–70° N) and uses monthly relative vorticity values from NCEP-DOE reanalysis databases (1981–2020) along with standardized rainfall data from 97 Iranian synoptic stations. Three main CCA patterns reveal connections: 500-hPa relative vorticity changes in the eastern Mediterranean, Middle East, and Iran relate to eastern Iran's precipitation. Relative vorticity over Eastern Europe inversely correlates with southern Caspian Sea coast precipitation. Changes over Turkey and Cyprus can affect northwestern Iran's rainfall. The changes in 850-hPa relative vorticity over the Arabian Sea inversely link to eastern Iran's precipitation, while those over the eastern Mediterranean directly connect to western Iran's precipitation. Relative vorticity changes in Eastern Europe negatively correlate with southwestern Caspian Sea coast precipitation.

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伊朗大尺度相对涡度场与降水的关系

摘要本文研究了伊朗中纬度天气运动的关键变量相对涡度与降水之间的关系。利用s型主成分分析，确定了相对涡度和降水的活动中心。应用典型相关分析(CCA)对这些中心的因子得分进行分析，揭示相对涡度与降水的耦合模式。该分析基于2.5°网格点(10°- 70°E和10°- 70°N)的500和850 hpa相对涡度场，并使用NCEP-DOE再分析数据库(1981-2020年)的每月相对涡度值以及来自97个伊朗天气站的标准化降雨数据。地中海东部、中东和伊朗地区的500 hpa相对涡度变化与伊朗东部降水有关。东欧上空的相对涡度与里海南部沿岸降水呈负相关。土耳其和塞浦路斯的变化会影响伊朗西北部的降雨。阿拉伯海上空850-hPa相对涡度的变化与伊朗东部降水呈负相关，而地中海东部上空850-hPa相对涡度的变化与伊朗西部降水直接相关。东欧相对涡度变化与里海西南海岸降水呈负相关。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Hydrology Research WATER RESOURCES-

CiteScore

5.00

自引率

7.40%

发文量

审稿时长

3.8 months

期刊介绍： Hydrology Research provides international coverage on all aspects of hydrology in its widest sense, and welcomes the submission of papers from across the subject. While emphasis is placed on studies of the hydrological cycle, the Journal also covers the physics and chemistry of water. Hydrology Research is intended to be a link between basic hydrological research and the practical application of scientific results within the broad field of water management.