scholarly journals Assessing the performance of GPS tomography at retrieving water vapour fields during landfalling atmospheric rivers over southern California

2020 ◽  
Vol 27 (4) ◽  
Author(s):  
Biyan Chen ◽  
Wenkun Yu ◽  
Wujiao Dai ◽  
Hao Wu ◽  
Wei Wang
Keyword(s):  
Water Vapour ◽  
Southern California ◽  
Atmospheric Rivers

Identification and Synoptic Analysis of the Highest Precipitation Linked to Ars in Iran

2021 ◽  
Vol 3 (2) ◽  
pp. 20-32
Author(s):  
Hassan Lashkari ◽  
Neda Esfandiari ◽  
Abbas Kashani
Keyword(s):  
Water Vapour ◽  
Heavy Rainfall ◽  
Daily Rainfall ◽  
Horn Of Africa ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
Atmospheric Rivers ◽  
Factors Affecting ◽  
North West ◽  
Integral Data

Atmospheric rivers are long, narrow, concentrated structures of water vapour that are highly associated with rainfall and floods. To identify and introduce the highest rainfall occurring during the presence of atmospheric rivers from November to April (2007-2018) while showing the importance of this phenomenon in creating super heavy rainfall and introducing the areas affected by it, analyzed the synoptic factors affecting them slowly. In order to identify atmospheric rivers, vertical integral data of water vapour flow were used and thresholds were documented on them. The date of occurrence of each atmospheric river with their daily rainfall was examined and ten of the highest rainfall events Station (equivalent to the 95th percentile of maximum rainfall) related to atmospheric rivers was introduced and analyzed. It is found that the South Gram has been directly and indirectly the main source of atmospheric rivers associated with heavy rainfall. The source of most of these atmospheric rivers is at the peak of the Red Sea, the Gulf of Aden and the Horn of Africa. Synonymously, the origins of 7 cases from Atmospheric rivers have been of the Sudanese low pressure and in the remaining three cases have been integrated systems. In Sudanese systems, the predominant structure of the meridional inclination jet and in Integration systems has been oriented. Due to the dominance of a strong upstream current in the vicinity of the highest flux, moisture of heavy convective currents has caused super heavy rainfall and the station with the highest rainfall in the east and North West of the negative omega field or upstream streams.

scholarly journals Hourly Analyses of the Large Storms and Atmospheric Rivers that Provide Most of California’s Precipitation in Only 10 to 100 Hours per Year

2018 ◽  
Vol 16 (4) ◽  
Author(s):  
Maryam Lamjiri ◽  
Michael Dettinger ◽  
F. Martin Ralph ◽  
Nina Oakley ◽  
Jonathan Rutz
Keyword(s):  
San Francisco ◽  
Sierra Nevada ◽  
Southern California ◽  
Extreme Rainfall ◽  
Annual Rainfall ◽  
North Coast ◽  
Northern California ◽  
Rainfall Events ◽  
Atmospheric Rivers ◽  
The North

California is regularly impacted by floods and droughts, primarily as a result of too many or too few atmospheric rivers (ARs). This study analyzes a two-decade-long hourly precipitation dataset from 176 California weather stations and a 3-hourly AR chronology to report variations in rainfall events across California and their association with ARs. On average, 10-40 and 60-120 hours of rainfall in southern and northern California, respectively, are responsible for more than half of annual rainfall accumulations. Approximately 10-30% of annual precipitation at locations across the state is from only one large storm. On average, northern California receives 25-45 rainfall events annually (40-50% of which are AR-related). These events typically have longer durations and higher event-precipitation totals than those in southern California. Northern California also receives more AR landfalls with longer durations and stronger Integrated Vapor Transport (IVT). On average, ARs contribute 79%, 76%, and 68% of extreme-rainfall accumulations (i.e., top 5% events annually) in the north coast, northern Sierra, and Transverse Ranges of southern California, respectively. The San Francisco Bay Area terrain gap in the California Coast Range allows more AR water vapor to reach inland over the Delta and Sacramento Valley, and thus, influences precipitation in the Delta’s catchment. This is particularly important for extreme precipitation in the northern Sierra Nevada, including river basins above Oroville Dam and Shasta Dam. This study highlights differences between rainfall and AR characteristics in coastal versus inland northern California, differences that largely determine the regional geography of flood risks and water-reliability. These analyses support water resource, flood, levee, wetland, and ecosystem management within the catchment of the San Francisco estuary system by describing regional characteristics of ARs and their influence on rainfall on an hourly timescale.

Evaluating atmospheric rivers and their influence on precipitation in the Arctic - comparing observational with reanalysis data

2021 ◽  
Author(s):  
Melanie Lauer ◽  
Annette Rinke ◽  
Irina Gorodetskaya ◽  
Susanne Crewell
Keyword(s):  
Sea Ice ◽  
Water Vapour ◽  
Moisture Transport ◽  
Collaborative Research ◽  
Surface Processes ◽  
Research Center ◽  
The Arctic ◽  
Arctic Amplification ◽  
Feedback Mechanisms ◽  
Atmospheric Rivers

<p>The Arctic as a whole has been experiencing significant warming and moistening with several potential factors at play. In general, the warming amplifies the Arctic hydrological cycle. There are two processes which could affect the water vapour content in the Arctic. These are the enhanced local evaporation due to reduced sea-ice concentration and extent and the modified poleward moisture transport from lower latitudes due to changing circulation patterns. An important contribution to the total poleward moisture transport comes from Atmospheric rivers (ARs). ARs have rare occurrence but are associated with anomalously high moisture transport compared to tropical cyclones. ARs are typically associated with not only moisture but also with significant heat advection. They can bring precipitation as rain and/or snow. Moreover, additional feedbacks can occur: the warming effect of the ARs on the surface, coupled with rain lowering surface albedo, can cause thinning and melting of Arctic sea ice and snow. This, in turn, could increase the relative role of the local evaporation compared to the moisture transported from lower latitudes.</p><p>In this study, we investigate the relationship between the poleward moisture transport by ARs and the precipitation in the Arctic. The focus is on AR events during the ACLOUD (May/June 2017) and AFLUX (March/April 2018) campaign within the Collaborative Research Center “Arctic Amplification: Climate Relevant Atmospheric and Surface Processes, and Feedback Mechanisms (AC)<sup>3</sup>”. For these campaigns, existing AR catalogues with the input of ERA5 reanalyses are used to detect AR events. Six ARs are detected: two coming from Siberia and four from the Atlantic.</p><p>These AR events are analysed in terms of the macro- and microphysical precipitation properties, including frequency, intensity, and type of precipitation (rain or snow).  For this purpose, we use ERA5 reanalyses data for the water vapour transport, precipitation amount and type, rain and snow profiles (convective, large-scale, total), as well as vertical profile of hydrometeors. Reanalysis products are evaluated using a set of observational data (satellite data and ground-based remote sensing measurements). This new multi-parameter, multi-dataset set will allow to investigate the occurrence of ARs and its influence on precipitation in the Arctic for the last decades.</p><p> </p><p>“We gratefully acknowledge the funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) –Projektnummer 268020496 –TRR 172, within the Transregional Collaborative Research Center “ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)3.“</p>

scholarly journals Drivers and Impacts of Atmospheric Rivers in New Zealand

2021 ◽  
Author(s):  
◽  
Daemon Kennett
Keyword(s):  
New Zealand ◽  
Water Vapour ◽  
Large Scale ◽  
Southern Oscillation ◽  
Daily Rainfall ◽  
Seasonal Forecasts ◽  
Positive Role ◽  
Atmospheric Rivers ◽  
Synoptic Conditions ◽  
Climate Patterns

<p><b>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.</b></p> <p>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.</p> <p>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.</p>

scholarly journals Drivers and Impacts of Atmospheric Rivers in New Zealand

2021 ◽  
Author(s):  
◽  
Daemon Kennett
Keyword(s):  
New Zealand ◽  
Water Vapour ◽  
Large Scale ◽  
Southern Oscillation ◽  
Daily Rainfall ◽  
Seasonal Forecasts ◽  
Positive Role ◽  
Atmospheric Rivers ◽  
Synoptic Conditions ◽  
Climate Patterns

<p><b>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.</b></p> <p>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.</p> <p>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.</p>

Dynamic Mapping of the Movement of Landfalling Atmospheric Rivers Over Southern California With GPS Data

2019 ◽  
Vol 46 (6) ◽  
pp. 3551-3559 ◽  
Author(s):  
Minghua Wang ◽  
Jiexian Wang ◽  
Yehuda Bock ◽  
Hong Liang ◽  
Danan Dong ◽  
...  
Keyword(s):  
Southern California ◽  
Gps Data ◽  
Atmospheric Rivers ◽  
Dynamic Mapping

scholarly journals Atmospheric rivers in the Australia-Asian region: a BoM–CMA collaborative study

2020 ◽  
Author(s):  
Chengzhi Ye ◽  
Huqiang Zhang ◽  
Aurel Moise ◽  
Ruping Mo
Keyword(s):  
Water Vapour ◽  
Moisture Transport ◽  
Weather Prediction ◽  
Boreal Summer ◽  
Atmospheric Moisture ◽  
Atmospheric Rivers ◽  
Extreme Precipitation Events ◽  
Set Up ◽  
Atmospheric Moisture Transport

The name ‘atmospheric river’ (AR) could easily be misinterpreted to mean rivers flowing in the sky. But, ARs actually refer to narrow bands of strong horizontal water vapour transport that are concentrated in the lower troposphere. These bands are called ‘atmospheric rivers’ because the water vapour flux they carry is close to the volume of water carried by big river systems on the ground. ARs can cause heavy rainfall events if some physical mechanisms, such as orographic enhancement, exist to set up the moisture convergence and vertical motions necessary to produce condensation. In recent decades, these significant moisture plumes have attracted increasing attention from scientific communities, especially in North America and western Europe, to further understand the connections between ARs and extreme precipitation events which can trigger severe natural disasters such as floods, mudslides and avalanches. Yet very limited research has been conducted in the Australia-Asian (A-A) region, where the important role of atmospheric moisture transport has long been recognised for its rainfall generation and variations. In this paper, we introduce a collaborative project between the Australian Bureau of Meteorology and China Meteorological Administration, which was set up to explore the detailed AR characteristics of atmospheric moisture transport embedded in the A-A monsoon system. The project in China focused on using AR analysis to explore connections between moisture transport and extreme rainfall mainly during the boreal summer monsoon season. In Australia, AR analysis was used to understand the connections between the river-like Northwest Cloud Band and rainfall in the region. Results from this project demonstrate the potential benefits of applying AR analysis to better understand the role of tropical moisture transport in rainfall generation in the extratropics, thus achieve better rainfall forecast skills at NWP (Numerical Weather Prediction), sub-seasonal and seasonal time scales. We also discuss future directions of this collaborative research, including further assessing potential changes in ARs under global warming.

scholarly journals Atmospheric Rivers over the Arctic with the ICON model

2020 ◽  
Author(s):  
Hélène Bresson ◽  
Annette Rinke ◽  
Vera Schemann ◽  
Susanne Crewell ◽  
Carolina Viceto ◽  
...  
Keyword(s):  
Water Vapour ◽  
Temporal Structure ◽  
Arctic Region ◽  
Surface Energy Budget ◽  
The Arctic ◽  
Limited Area ◽  
Polar Regions ◽  
Relative Role ◽  
Atmospheric Rivers ◽  
The Impact

&lt;div&gt;The Arctic climate changes faster than the ones of other regions, but&amp;#160;the relative role of the individual feedback mechanisms contributing to Arctic amplification is still unclear. Atmospheric Rivers (ARs) are narrow and&amp;#160;transient river-style moisture flows arriving from the sub-polar regions. The&lt;div&gt;integrated water vapour transport associated with ARs can explain up to&amp;#160;70% of the precipitation variance north of 70&amp;#176;N. However, there are still un-&lt;/div&gt;&lt;div&gt;certainties regarding the specific role and the impact of ARs on the Arctic&amp;#160;climate variability.&lt;/div&gt;&lt;div&gt;For the first time, the high-resolution ICON modelling framework is used&amp;#160;over the Arctic region (from 13 km down to ca. 6 and 3 km) to investigate processes&amp;#160;related with anomalous moisture transport into the Arctic. Based on a case&amp;#160;study for Svalbard, the representation of the atmospheric circulation and the&amp;#160;spatio-temporal structure of water vapour, temperature, and precipitation&amp;#160;and snowfall within the limited-area mode (LAM) of the ICON model is&amp;#160;assessed. Preliminary results show that the moisture intrusion is relatively well represented in the ICON-LAM simulations. The impact on the surface energy budget will also be calculated.&lt;/div&gt;&lt;/div&gt;

Characteristics of southern California atmospheric rivers

2017 ◽  
Vol 132 (3-4) ◽  
pp. 965-981 ◽  
Author(s):  
Sarah M. Harris ◽  
Leila M. V. Carvalho
Keyword(s):  
Southern California ◽  
Atmospheric Rivers
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