Impacts of Atmospheric Rivers on Precipitation in Southern South America

Viale, Maximiliano; Valenzuela, Raúl A.; Garreaud, René D.; Ralph, F. Martin

doi:10.1175/jhm-d-18-0006.1

Cited by 153 publications

(159 citation statements)

References 41 publications

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“…This method performs well when the AR has an elongated shape but has difficulties when the AR is sharply curved or otherwise complicated in structure because the slicing may not be optimally placed/oriented in these cases. Such difficulties were also noted in Viale et al () where a similar method was used for finding the AR axis, and, in dealing with the issue, candidate ARs with complicated structure were discarded. In the current algorithm, the AR axis is identified by tapping the previously unused information in IVT direction.…”

Section: Data and Methodsologymentioning

confidence: 93%

Tracking Atmospheric Rivers Globally: Spatial Distributions and Temporal Evolution of Life Cycle Characteristics

2019

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The Tracking Atmospheric Rivers Globally as Elongated Targets (tARget) algorithm is further developed to Version 3, adding the capability to track atmospheric river (AR) life cycles along with other refinement. The results indicate AR genesis is more frequent toward the western boundaries of midlatitude ocean basins and nearby upstream land areas (~1 month−1) compared to the eastern boundaries (~0.5 month−1) and least frequent in tropical and polar areas (reaching toward 0). AR termination is more frequent toward the northeastern sectors of North Pacific/Atlantic and adjacent downstream land areas and in the Southern Ocean near Antarctica (~1 month−1) compared to the adjacent ocean sectors (~0.5 month−1) and least frequent in tropical areas and interior Antarctica where AR genesis is similarly infrequent. ARs tend to be longer‐lived when the genesis (termination) occurs toward the western (eastern) boundaries of midlatitude ocean basins and adjacent land areas (maximum lifetime >72 hr) compared to the opposite side of the ocean basins (24–72 hr) and when terminated at high latitudes. AR travel speed is higher in the midlatitude ocean basins and strongly steered by the zonal wind around 650 hPa. AR tracks are nearly linear in most cases, with the overall travel direction closely correlated with the direction of integrated water vapor transport (r = 0.69) although being more zonal than the latter. Temporally, ARs tend to be longer/stronger around the middle of the life cycle. Seasonal variations in AR life cycle characteristics are also examined. The handling of AR separations/mergers contributes the largest sensitivity in tracking result compared to selection/resolution of input data.

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Section: Data and Methodsologymentioning

confidence: 93%

Tracking Atmospheric Rivers Globally: Spatial Distributions and Temporal Evolution of Life Cycle Characteristics

2019

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“…For southern California, Harris and Carvalho () note that conditions prior to AR making landfall differ from those for the Pacific Northwest with the intraseasonal to interannual variability in AR frequency conditioned on phases of modes of climate variability such as ENSO and the Madden Julian Oscillation as Debbage et al () found for AR over the southeast of the United States. For South America, AR landfalls are most frequent over the latitudinal range 38°S–50°S, occurring on average 35–40 days per year (Viale, Valenzuela, Garreaud, & Ralph, ). North and south of this band AR decrease rapidly as they do east of the Andes.…”

Section: Atmospheric Riversmentioning

confidence: 99%

“…North and south of this band AR decrease rapidly as they do east of the Andes. Contributing 45–60% of the annual precipitation in subtropical Chile and 40–55% along the midlatitude west coast, AR for this region exceed the importance for annual precipitation in the Pacific Northwest, most likely due to the severe orographic forcing, achieved under the influence of the Andes (Viale et al, ).…”

Section: Atmospheric Riversmentioning

confidence: 99%

“…Importantly, they note warm season flash floods are not commonly associated with AR with convective storms the likely candidates for these. For Chile, Viale et al () demonstrate that approximately half of all top‐quartile precipitation intensities, across subtropical and midlatitudes, occur under AR conditions with median daily and hourly precipitation in ARs being two to three times that of other storms.…”

Section: Atmospheric Riversmentioning

confidence: 99%

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Climate and rivers

McGregor

2019

River Research & Apps

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Over the last few decades as hydrologists have slowly raised their line of sight above the watershed boundary, it has become increasingly recognised that what happens in the atmosphere, as a major source of moisture for the terrestrial branch of the hydrological cycle, can strongly influence river dynamics at a range of spatial and temporal scales. Notwithstanding this, there is still a tendency for some in the river research community to restrict their gaze to the river channel or floodplain. However, Geoff Petts, the person to which this special issue is dedicated, understood well and widely encouraged a holistic view of river catchment processes. This included an acknowledgment of the role of climate, in its broadest sense, in shaping what happens within and without the river channel. The purpose of this paper therefore is to offer a broad overview of the role of some aspects of climate science in advancing knowledge in river research. Topics to be addressed include the role of climate in influencing river flow regimes, a consideration of the large‐scale climate mechanisms that drive hydrological variability within river basins at interannual to decadal timescales and atmospheric rivers and their link to surface hydrology. In reviewing these topics, a number of key knowledge gaps have emerged including attributing the causes of river flow regime changes to any one particular cause, the nonstationary and asymmetric forcing of river regimes by modes of climate variability and establishing links between atmospheric rivers, and terrestrial river channel processes, fluvial habitats, and ecological change.

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“…Landslides in the Western U.S. are also more likely to occur in conjunction with ARs on lands affected by wildfires [12]. The importance of ARs has been documented in a variety of climate zones, and across the globe (e.g., References [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]).…”

Section: Introductionmentioning

confidence: 99%

An Expanded Investigation of Atmospheric Rivers in the Southern Appalachian Mountains and Their Connection to Landslides

Miller

Miniat²,

Wooten³

et al. 2019

Atmosphere

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Previous examination of rain gauge observations over a five-year period at high elevations within a river basin of the southern Appalachian Mountains showed that half of the extreme (upper 2.5%) rainfall events were associated with an atmospheric river (AR). Of these extreme events having an AR association, over 73% were linked to a societal hazard at downstream locations in eastern Tennessee and western North Carolina. Our analysis in this study was expanded to investigate AR effects in the southern Appalachian Mountains on two river basins, located 60 km apart, and examine their influence on extreme rainfall, periods of elevated precipitation and landslide events over two time periods, the ‘recent’ and ‘distant’ past. Results showed that slightly more than half of the extreme rainfall events were directly attributable to an AR in both river basins. However, there was disagreement on individual ARs influencing extreme rainfall events in each basin, seemingly a reflection of its proximity to the Blue Ridge Escarpment and the localized terrain lining the river basin boundary. Days having at least one landslide occurring in western North Carolina were found to be correlated with long periods of elevated precipitation, which often also corresponded to the influence of ARs and extreme rainfall events.

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Impacts of Atmospheric Rivers on Precipitation in Southern South America

Cited by 153 publications

References 41 publications

Tracking Atmospheric Rivers Globally: Spatial Distributions and Temporal Evolution of Life Cycle Characteristics

Tracking Atmospheric Rivers Globally: Spatial Distributions and Temporal Evolution of Life Cycle Characteristics

Climate and rivers

An Expanded Investigation of Atmospheric Rivers in the Southern Appalachian Mountains and Their Connection to Landslides

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