Automatic detection, classification, and long‐term investigation of temporal–spatial changes of atmospheric rivers in the Middle East

Abstract

Most water vapour in various subtropical regions is transported by atmospheric rivers (ARs). It is crucial to study this phenomenon, especially in regions more vulnerable to climate change due to population growth and aridity. The study's primary purpose was to detect ARs in the Middle East. According to expectations, ARs were classified based on strength and temporal–spatial distribution and their changes were examined to characterize the risks of the phenomenon. The results showed that ARs had significantly increased over the past 50 years (1971–2020). The most positive increase was related to weak ARs (Cat 1) in the last two decades and exceptional events (Cat 5) in the last decade. The results also indicated the role of terrain in limiting the path of the AR axis and multiple sources of moisture in their strongest form. The occurrence of hazardous events (Cat 4 and 5) was estimated at up to 22% of all ARs in the Middle East, with the highest frequency in the last three decades. It was also found that events with a maximum IVT of >1,000 kg·m−1·s−1 occurred 10 times during the last half of the last century. Also, an AR with a maximum IVT of 1,102 kg·m−1·s−1 occurred once in the region. The temporal distribution of these extreme events showed that they could occur at any time, depending on the conditions of AR formation. However, extreme events mainly occurred in March.

Recent and projected changes in climate patterns in the Middle East and North Africa (MENA) region

“…1 a). Such excursions of tropical moisture into the higher latitudes can take the form of atmospheric rivers 140 , which are becoming more frequent in the region 56 , 141 , a trend which is likely to continue in a future warming climate 142 .…”

“…For example, a change in the position and/or strength of the thermal (heat) lows and subtropical highs over the Middle East and North Africa will impact the atmospheric circulation and wind patterns locally 54 , 55 . This can in turn impact the transport of moisture 56 and the dust/aerosol emissions and transport 57 , 58 and hence the atmospheric radiation fields 59 . Such circulation changes in a warming climate have not been comprehensively discussed, and will be explored here for a CMIP6 MME for the extended MENA region.…”

Trend analysis of widespread heat days in the Middle East and North Africa region between 1871 and 2012

“…A nonparametric Mann–Kendall test was used to determine the trend. The nonparametric Mann–Kendall test is widely used in detecting trends of variables in meteorology and hydrology fields (Aalijahan et al, 2021, 2023; Ahn & Merwade, 2014; Esfandiari & Rezaei, 2022; Liang et al, 2010; Rezaei et al, 2022; Wang et al, 2019) Statistic s can be obtained by Equation (). where n is the length of the sample, 𝑥 k and 𝑥 j are from k = 1, 2, …, n − 1 and 𝑗 = k + 1, …, n . If n is bigger than 8, statistic s approximates to normal distribution.…”

“…The study area for reconstruction of widespread heat days along with 1.87 × 1.9-degree grid points based on the 20CRv2 dataset. [Colour figure can be viewed at wileyonlinelibrary.com] and hydrology fields (Aalijahan et al, 2021(Aalijahan et al, , 2023Ahn & Merwade, 2014;Esfandiari & Rezaei, 2022;Liang et al, 2010;Rezaei et al, 2022;Wang et al, 2019) Statistic s can be obtained by Equation (1).…”

Atmospheric River Rapids and Their Role in the Extreme Rainfall Event of April 2023 in the Middle East

“…The Red Sea Trough is more active during spring and autumn compared to winter (Tsvieli & Zangvil, 2007), while cyclogenesis in parts of the southern Mediterranean is more frequent in spring (Flaounas et al., 2022; Lionello et al., 2016). ARs in the Middle East tend to be less intense, in terms of the associated IVT, compared to those in Europe and North America, owing to the aridity of the neighboring north Africa and Sahara (Bozkurt et al., 2021; Eiras‐Barca et al., 2021; Esfandiari & Rezaei, 2022). However, their horizontal and vertical structures are similar to those of ARs elsewhere, despite regional variations in intensity and impact (e.g., Bozkurt et al., 2021; Dezfuli, 2020; Dezfuli et al., 2021; Payne et al., 2020).…”