Cascading effect of Meteorological forcing on Extreme Precipitation events: Role of Atmospheric Rivers in Southeastern US

Abstract. Extreme precipitation events in the Mediterranean region during the cool season are strongly affected by the export of moist air from tropical and subtropical areas into the extratropics. The aim of this paper is to present a discussion of the major research efforts on this subject and to formulate a summary of our understanding of this phenomenon, along with its recent past trends from a climate change perspective. The issues addressed are: a discussion of several case studies; the origin of the air moisture and the important role of atmospheric rivers for fueling the events; the mechanism responsible for the intensity of precipitation during the events, and the possible role of global warming in recent past trends in extreme weather events over the Mediterranean region.

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Discussing the role of tropical and subtropical moisture sources in cold season extreme precipitation events in the Mediterranean region from a climate change perspective

Natural Hazards and Earth System Science ◽

10.5194/nhess-16-269-2016 ◽

2016 ◽

Vol 16 (1) ◽

pp. 269-285 ◽

Cited By ~ 12

Author(s):

S. O. Krichak ◽

S. B. Feldstein ◽

P. Alpert ◽

S. Gualdi ◽

E. Scoccimarro ◽

...

Keyword(s):

Climate Change ◽

Extreme Precipitation ◽

Mediterranean Region ◽

Cold Season ◽

Tropical Atlantic ◽

Moist Air ◽

Atmospheric Rivers ◽

Extreme Precipitation Events ◽

Precipitation Events

Abstract. This paper presents a review of a large number of research studies performed during the last few decades that focused on the investigation of cold season extreme precipitation events (EPEs) in the Mediterranean region (MR). The publications demonstrate the important role of anomalously intense transports of moist air from the tropical and subtropical Atlantic in the occurrence of EPEs in the MR. EPEs in the MR are directly or indirectly connected to narrow bands with a high concentration of moisture in the lower troposphere, i.e., atmospheric rivers, along which a large amount of moisture is transported from the tropics to midlatitudes. Whereas in a significant fraction of the EPEs in the western MR moisture is transported to the MR from the tropical Atlantic, EPEs in the central, and especially the eastern, MR are more often associated with intense tropical moisture transports over North Africa and the Red Sea. The moist air for the EPEs in the latter part of the MR also mainly originates from the tropical Atlantic and Indian oceans, and in many cases it serves as a temporary moisture reservoir for future development. The paper is supplemented by the results of a test for a possible connection between declining Arctic sea ice and the climatology of intense precipitation in the eastern MR. Based on the results of the evaluation supporting those from the earlier climate change analyses and modeling studies, it is concluded that a further anthropogenic global warming may lead a greater risk of higher rainfall totals and therefore larger winter floods in western and central parts of the MR as a consequence of stronger and more numerous Atlantic atmospheric rivers, possibly accompanied by a decline in the number of EPEs in the eastern part of the MR.

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Applying a storyline approach to explore the impact of future Atmospheric River induced floods in western Norway

10.5194/egusphere-egu21-8309 ◽

2021 ◽

Author(s):

Trine Jahr Hegdahl ◽

Kolbjørn Engeland ◽

Malte Müller ◽

Jana Sillman

Keyword(s):

Extreme Precipitation ◽

Initial Conditions ◽

Future Climate ◽

Meteorological Forcing ◽

Extreme Precipitation Events ◽

Western Norway ◽

Current Climate ◽

The Future ◽

Climate Events ◽

Precipitation Events

<p>Atmospheric rivers (AR) are responsible for the most extreme precipitation events causing devastating landslides and floods in western Norway. In this study an event-based storyline approach is used to compare the flood impact of extreme AR events in a warmer climate to those of the current climate.&#160; The four most extreme precipitation events were selected from 30 years of present and future climate simulations from the high-resolution global climate model, the EC-Earth model. For each of the four events, EC-Earth was rerun creating 10 perturbed realizations. A regional convective permitting weather prediction model, AROME-MetCoOp, was used to further downscale the events, and thereafter the operational Norwegian flood-forecasting model was used to estimate the flood levels for 37 catchments in western Norway. The magnitude and the spatial impact were analyzed, and different hydrological initial conditions, which affect the total flooding, were analyzed.</p><p>The results show that more catchments were affected with larger floods in the future climate events compared to the current climate events. In addition, the combination of multiple realizations of meteorological forcing and different hydrological initial conditions, for example soil saturation and snow storage, were important for the estimation of the maximum flood level. The meteorological forcing had the highest overall effect on flood magnitude; however, varying and depending on event and catchment. Finally, operational flood warning levels were used to visualize the difference between future and current climate flood events. Applying a setup similar to the one used operationally and relating the future events to known current events associated with ARs, enables a common reference and ease communication with end-users and decision makers.</p>

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Large-Scale Flow Patterns Associated with Extreme Precipitation and Atmospheric Rivers over Norway

Monthly Weather Review ◽

10.1175/mwr-d-18-0362.1 ◽

2019 ◽

Vol 147 (4) ◽

pp. 1415-1428 ◽

Cited By ~ 7

Author(s):

Imme Benedict ◽

Karianne Ødemark ◽

Thomas Nipen ◽

Richard Moore

Keyword(s):

Extreme Precipitation ◽

Large Scale ◽

Moisture Flux ◽

Cold Season ◽

Fuzzy Cluster ◽

The South ◽

Atmospheric Rivers ◽

The North ◽

Extreme Precipitation Events ◽

Precipitation Events

Abstract A climatology of extreme cold season precipitation events in Norway from 1979 to 2014 is presented, based on the 99th percentile of the 24-h accumulated precipitation. Three regions, termed north, west, and south are identified, each exhibiting a unique seasonal distribution. There is a proclivity for events to occur during the positive phase of the NAO. The result is statistically significant at the 95th percentile for the north and west regions. An overarching hypothesis of this work is that anomalous moisture flux, or so-called atmospheric rivers (ARs), are integral to extreme precipitation events during the Norwegian cold season. An objective analysis of the integrated vapor transport illustrates that more than 85% of the events are associated with ARs. An empirical orthogonal function and fuzzy cluster technique is used to identify the large-scale weather patterns conducive to the moisture flux and extreme precipitation. Five days before the event and for each of the three regions, two patterns are found. The first represents an intense, southward-shifted jet with a southwest–northeast orientation. The second identifies a weak, northward-shifted, zonal jet. As the event approaches, regional differences become more apparent. The distinctive flow pattern conducive to orographically enhanced precipitation emerges in the two clusters for each region. For the north and west regions, this entails primarily zonal flow impinging upon the south–north-orientated topography, the difference being the latitude of the strong flow. In contrast, the south region exhibits a significant southerly component to the flow.

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Impacts of Atmospheric Rivers in Extreme Precipitation on the European Macaronesian Islands

Atmosphere ◽

10.3390/atmos9080325 ◽

2018 ◽

Vol 9 (8) ◽

pp. 325 ◽

Cited By ~ 3

Author(s):

Alexandre M. Ramos ◽

Ricardo M. Trigo ◽

Ricardo Tomé ◽

Margarida L. R. Liberato

Keyword(s):

Canary Islands ◽

Extreme Precipitation ◽

Daily Precipitation ◽

Comprehensive Assessment ◽

Atmospheric Rivers ◽

Extreme Precipitation Events ◽

Macaronesian Islands ◽

Weather Stations ◽

The Relationship ◽

Precipitation Events

The European Macaronesia Archipelagos (Azores, Madeira and Canary Islands) are struck frequently by extreme precipitation events. Here we present a comprehensive assessment on the relationship between atmospheric rivers and extreme precipitation events in these three Atlantic Archipelagos. The relationship between the daily precipitation from the various weather stations located in the different Macaronesia islands and the occurrence of atmospheric rivers (obtained from four different reanalyses datasets) are analysed. It is shown that the atmospheric rivers’ influence over extreme precipitation (above the 90th percentile) is higher in the Azores islands when compared to Madeira or Canary Islands. In Azores, for the most extreme precipitation days, the presence of atmospheric rivers is particularly significant (up to 50%), while for Madeira, the importance of the atmospheric rivers is reduced (between 30% and 40%). For the Canary Islands, the occurrence of atmospheric rivers on extreme precipitation is even lower.

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