Directional characteristics of low-level jet over the Arabian Sea and its impact on monsoon precipitation over the Western Ghats

IF 2.2 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics Pub Date : 2025-12-01 Epub Date: 2025-10-19 DOI:10.1016/j.jastp.2025.106665

Xinming Zhang , M.V. Subrahmanyam , Zhou Le , Dongxiao Wang

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引用次数: 0

Abstract

Previous studies have conducted a comprehensive examination of the impact of wind speed on monsoon precipitation; however, the significance of wind direction remains largely unexplored. This analysis utilizes ERA-5 reanalysis data to quantitatively investigate the directional characteristics of the Arabian Sea low-level jet (LLJ) over the last four decades. It applies wind angle metrics to evaluate the LLJ's direction and its influence on monsoon precipitation over the Western Ghats (WG), with a larger angle signifying that the LLJ is more aligned with the southerly wind. At 925 hPa, the LLJ exhibits a greater wind angle than at 850 hPa, showing an upward trend. This finding suggests a northerly movement of the LLJ, potentially associated with the Pacific Decadal Oscillation. Statistical analysis reveals that a larger LLJ angle is associated with heightened precipitation on the northern windward slopes of the WG, and precipitation decreases in the southern regions, suggesting the influence of the LLJ's directional changes on precipitation patterns. The results offer valuable perspectives for enhancing monsoon predictions and deepening our scientific comprehension of the relationship between the LLJ and precipitation.

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阿拉伯海低空急流的方向特征及其对西高止山脉季风降水的影响

以前的研究对风速对季风降水的影响进行了全面的研究；然而，风向的重要性在很大程度上仍未被探索。该分析利用ERA-5再分析数据定量研究了过去40年阿拉伯海低空急流（LLJ）的方向特征。应用风角度量来评价LLJ的方向及其对西高止山脉季风降水的影响，风角越大表明LLJ更偏向于南风。在925 hPa处，LLJ风角大于850 hPa，呈上升趋势。这一发现表明LLJ向北移动，可能与太平洋年代际振荡有关。统计分析表明，LLJ角的增大与北风坡降水增加有关，而南风坡降水减少有关，表明LLJ的方向变化对降水模式有影响。这些结果为加强季风预测和加深我们对LLJ与降水关系的科学理解提供了有价值的观点。

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来源期刊

Journal of Atmospheric and Solar-Terrestrial Physics 地学-地球化学与地球物理

CiteScore

4.10

自引率

5.30%

发文量

审稿时长

6 months

期刊介绍： The Journal of Atmospheric and Solar-Terrestrial Physics (JASTP) is an international journal concerned with the inter-disciplinary science of the Earth''s atmospheric and space environment, especially the highly varied and highly variable physical phenomena that occur in this natural laboratory and the processes that couple them. The journal covers the physical processes operating in the troposphere, stratosphere, mesosphere, thermosphere, ionosphere, magnetosphere, the Sun, interplanetary medium, and heliosphere. Phenomena occurring in other "spheres", solar influences on climate, and supporting laboratory measurements are also considered. The journal deals especially with the coupling between the different regions. Solar flares, coronal mass ejections, and other energetic events on the Sun create interesting and important perturbations in the near-Earth space environment. The physics of such "space weather" is central to the Journal of Atmospheric and Solar-Terrestrial Physics and the journal welcomes papers that lead in the direction of a predictive understanding of the coupled system. Regarding the upper atmosphere, the subjects of aeronomy, geomagnetism and geoelectricity, auroral phenomena, radio wave propagation, and plasma instabilities, are examples within the broad field of solar-terrestrial physics which emphasise the energy exchange between the solar wind, the magnetospheric and ionospheric plasmas, and the neutral gas. In the lower atmosphere, topics covered range from mesoscale to global scale dynamics, to atmospheric electricity, lightning and its effects, and to anthropogenic changes.