Identifying atmospheric river events and their paths into Iran

Esfandiari, Neda; Lashkari, H

doi:10.1007/s00704-020-03148-w

Cited by 24 publications

(19 citation statements)

References 42 publications

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“…This is consistent with previous studies highlighting the midlatitude upper-level troughs and associated thermal instability and low-pressure systems over the eastern Mediterranean region, which lead to warm air advection and precipitation events over the NE highlands (e.g., Lolis & Türkeş, 2016;Lolis et al, 2008;Türkeş, 2010;Ziv, 2001). In particular, consistent with our findings, similar trough-ridge patterns with different locations (depending on the AR target region) were characterized as the most favorable synoptic conditions favoring the ARs influencing the similar or neighboring study areas (Dezfuli, 2020;Esfandiari & Lashkari, 2020). Furthermore, as illustrated in several works, ARs are largely triggered by extratropical cyclones/troughs/cut-off lows, and often occur along the upstream flank of a blocking anticyclone (e.g., Bozkurt et al, 2018;Liu & Barnes, 2015;Mattingly et al, 2020;Mundhenk et al, 2016), which is also valid for the ARs reported here.…”

Section: Concluding Remarks and Discussionsupporting

confidence: 90%

“…Relative to other algorithms, this algorithm has the potential benefit of improved depiction of impacts of ARs far inland (Rutz et al., 2019), as are the focus of the current study. Furthermore, previous AR events studied in several recent papers for similar or neighboring study areas (e.g., Akbary et al., 2019; Dezfuli, 2020; Esfandiari & Lashkari, 2020) are well represented in the current AR tracking data (not shown), which gives further confidence on the quality of this AR catalog. It should be emphasized that the present study did not apply any tracking algorithm but directly used the global AR catalog of Guan and Waliser (2019).…”

Section: Methodssupporting

confidence: 68%

“…Indeed, recent studies also use AR term to refer to poleward moisture transport over North Africa and the NE (e.g., Akbary et al., 2019; Dezfuli, 2020; Esfandiari & Lashkari, 2020). For instance, Esfandiari and Lashkari (2020) identified ARs reaching Iran as well as their paths using the AR tracking conditions developed by Guan and Waliser (2015) for 2007–2018 period. In the same study, they showed that more than half of the ARs originated from the Gulf of Aden and the Red Sea.…”

Section: Introductionmentioning

confidence: 99%

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Influence of African Atmospheric Rivers on Precipitation and Snowmelt in the Near East's Highlands

et al. 2021

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Atmospheric rivers (ARs) are important components of the global water cycle as they are responsible for over 90% of the poleward moisture transport at midlatitudes (Zhu & Newell, 1998). Estimations indicate that a typical AR over the North Pacific could carry much more water than some of the world's largest rivers (e.g., Ralph & Dettinger, 2011; Ralph et al., 2017). Three to five ARs are present in each hemisphere at any moment (Zhu & Newell, 1998), and they mostly prevail over the extratropical oceans, where they gain vast amounts of water vapor, and primarily make landfall on the western coasts of the midlatitude continents as a result of westerly flow (Guan & Waliser, 2015). In this respect, the mountainous western coasts of North Abstract Atmospheric rivers (ARs) traveling thousands of kilometers over arid North Africa could interact with the highlands of the Near East (NE), and thus affect the region's hydrometeorology and water resources. Here, we use a state-of-the-art AR tracking database, and reanalysis and observational datasets to investigate the climatology (1979-2017) and influences of these ARs in snowmelt season (March-April). The Red Sea and northeast Africa are found to be the major source regions of these ARs, which are typically associated with the eastern Mediterranean trough positioned over the Balkan Peninsula and a blocking anticyclone over the NE-Caspian region, triggering southwesterly air flow toward the NE's highlands. Approximately 8% of the ARs are relatively strong (integrated water vapor transport >∼275 kg m −1 s −1). AR days exhibit enhanced precipitation over the crescent-shaped orography of the NE region. Mean AR days indicate wetter (up to + 2 mm day −1) and warmer (up to + 1.5°C) conditions than all-day climatology. On AR days, while snowpack tends to decrease (up to 30%) in the Zagros Mountains, it can show decreases or increases in the Taurus Mountains depending largely on elevation. A further analysis with the observations and reanalysis indicates that extreme ARs coinciding with large scale sensible heat transport can significantly increase the daily discharges. These results suggest that ARs can have notable impacts on the hydrometeorology and water resources of the region, particularly of lowland Mesopotamia, a region that is famous with great floods in the ancient narratives. Plain Language Summary Atmospheric rivers (ARs) are important components of the global water cycle as they are responsible for over 90% of the poleward moisture transport at middle to high latitudes. ARs mostly prevail over the oceans and primarily landfall on the western coasts of the midlatitude continents as a result of westerly flow of the midlatitudes. Apart from the large ocean basins, certain ARs can develop and propagate over continents, which has received less scientific attention. In this respect, this study aims to show how overland African ARs developing in the snowmelt season can influence the Near East's highlands, which are essential for satisfying the water need of lowland areas of M...

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Section: Concluding Remarks and Discussionsupporting

confidence: 90%

Section: Methodssupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

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Influence of African Atmospheric Rivers on Precipitation and Snowmelt in the Near East's Highlands

et al. 2021

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“…The agreement rate mentioned above for other regions gives us confidence that the results we investigate in our current study would not heavily change if another detection algorithm was to be developed or used. In that regard, it is noted that the Iran-focused study in Esfandiari and Lashkari (2020ab) [49,50] used AR IVT percentile and geometry criteria largely following our global algorithm used here. We direct readers to Guan and Waliser (2015) for more information on the AR detection algorithm used in our study.…”

Section: Ar Detection Algorithmmentioning

confidence: 99%

Atmospheric Rivers and Precipitation in the Middle East and North Africa (MENA)

Massoud

Guan

et al. 2020

Water

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This study investigates the historical climatology and future projected change of atmospheric rivers (ARs) and precipitation for the Middle East and North Africa (MENA) region. We use a suite of models from the Coupled Model Intercomparison Project Phase 5 (CMIP5, historical and RCP8.5 scenarios) and other observations to estimate AR frequency and mean daily precipitation. Despite its arid-to-semi-arid climate, parts of the MENA region experience strong ARs, which contribute a large fraction of the annual precipitation, such as in the mountainous areas of Turkey and Iran. This study shows that by the end of this century, AR frequency is projected to increase (~20–40%) for the North Africa and Mediterranean areas (including any region with higher latitudes than 35 N). However, for these regions, mean daily precipitation (i.e., regardless of the presence of ARs) is projected to decrease (~15–30%). For the rest of the MENA region, including the Arabian Peninsula and the Horn of Africa, minor changes in AR frequency (±10%) are expected, yet mean precipitation is projected to increase (~50%) for these regions. Overall, the projected sign of change in AR frequency is opposite to the projected sign of change in mean daily precipitation for most areas within the MENA region.

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“…A number of studies have also investigated AR impacts in Europe (Lavers and Villarini, 2013), including Britain (Lavers et al, 2011), Norway (Azad and Sorteberg, 2017), the Iberian Peninsula and European Macronesian Islands (Ramos et al, 2015;Ramos et al, 2018). Recently, AR impacts have also been investigated in South America (Viale e al., 2018), South Africa (Blamey et al, 2018), Iran (Esfandiari and Lashkari, 2020), and East Asia (Kamae et al, 2017;Pan and Lu, 2020). In several regions, the term 'atmospheric river' has entered the mainstream lexicon.…”

Section: Global and Regional Ar Studiesmentioning

confidence: 99%

Drivers and Impacts of Atmospheric Rivers in New Zealand

Kennett¹

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Atmospheric Rivers (ARs) are long, narrow jets of intense water vapour flux that are a fundamental component of the global atmospheric circulation, transporting moisture and heat from the tropics to higher latitudes. When an AR makes landfall, especially in areas of steep topography, it releases much of its water vapour as precipitation through orographic uplift. Thus, although ARs play a positive role in the distribution and maintenance of water resources in the mid-latitudes, they are also associated with extreme precipitation and flooding. AR events in New Zealand have had major socio-economic consequences with losses to property, farmland, stock, roads and bridges. However, despite knowledge of their occurrence, focused investigations of ARs in New Zealand have received relatively little scientific attention. In particular, little is known about how large-scale climate patterns, such as the Southern Annular Mode (SAM) and El Niño-Southern Oscillation (ENSO), influence ARs and AR-related precipitation extremes. The aim of this study is to quantify the impacts and large-scale drivers of AR landfalls in New Zealand. We employ a new AR detection algorithm, developed specifically for the New Zealand case, to investigate landfalling ARs over a 41-year period from 1979-2019. We investigate the general climatology of ARs, and evaluate the synoptic conditions that drive these events. Using a comprehensive daily rainfall dataset comprising 189 stations, we also investigate the impacts of ARs on NZ rainfall and flooding events. For northern and western regions, over 45% of rainfall fell directly under AR conditions, contributing to daily rainfall totals 2.5 times higher on average compared to non-AR days. Further, we find that AR days were associated with up to 70% of daily rainfall totals above the 99th percentile, with insurance damages exceeding NZ $1.4 billion since 1980. Finally, for the first time in New Zealand, we investigate how large-scale climate patterns influence the occurrence of ARs. We find that changes in the leading modes of climate variability can alter seasonal and regional AR frequency by upwards of 30%. The SAM is identified as the dominant driver of AR activity (other than the seasonal cycle), with the positive SAM phase associated with a 16% reduction in AR occurrence during summer (30-35% reduction for the North Island). The links between AR occurrence and ENSO were less clear, though a few statistically significant relationships were found. The Madden-Julian Oscillation (MJO), the leading mode of intraseasonal tropical variability, was found to significantly influence the frequency and timing of AR landfalls (particularly for the northern North Island). Favourable MJO phases were associated with positive AR frequency anomalies +60% above the mean. These results demonstrate potential use of the AR framework in skilful subseasonal-to-seasonal forecasts of extreme rainfall in New Zealand.

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Identifying atmospheric river events and their paths into Iran

Cited by 24 publications

References 42 publications

Influence of African Atmospheric Rivers on Precipitation and Snowmelt in the Near East's Highlands

Influence of African Atmospheric Rivers on Precipitation and Snowmelt in the Near East's Highlands

Atmospheric Rivers and Precipitation in the Middle East and North Africa (MENA)

Drivers and Impacts of Atmospheric Rivers in New Zealand

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