Global Floods and Water Availability Driven by Atmospheric Rivers

Paltán, Homero; Waliser, Duane E.; Lim, Wee Ho; Guan, Bin; Yamazaki, Dai; Pant, Raghav; Dadson, Simon

doi:10.1002/2017gl074882

Cited by 116 publications

(120 citation statements)

References 45 publications

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“…Specifically, the shape and size of the ARs occurring in our domain were generally shorter, and wider, than the long and narrow AR events observed in the United States and Europe, which had detection transect at higher latitudes (Lavers et al, ; Ralph et al, ). This variability in frequency and size could be attributed to the different modes of climate variability acting in the region, such as WDs, the Indian monsoon, and low‐level jets tied to the terrain and linked with deep convection (e.g., Cannon et al, ; Gimeno et al, ; Paltan et al, ). AR persistence and orientation are functions of the background synoptic‐scale flow patterns (e.g., Hecht & Cordeira, ).…”

Section: Resultsmentioning

confidence: 99%

Atmospheric Rivers Carry Nonmonsoon Extreme Precipitation Into Nepal

2018

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Atmospheric rivers (ARs) are concentrated bands of water vapor that can cause extreme precipitation and severe flooding. Fortunately, due to their 1,500+ km spatial extent, they may also be forecasted days in advance. The goals of this study were to investigate the seasonal climatology of ARs in the Himalayan region of Nepal and to determine the role of ARs in extreme precipitation events. Using the ERA‐Interim atmospheric reanalysis, we applied a standard integrated vapor transport AR detection approach for the 35‐year period from 1979 to 2013. We detected 433 ARs, or approximately 12 ARs yearly. Along our six (0.75°) grid detection transect, ARs explain 35% of grid annual maximum daily precipitation events and 70% of grid nonmonsoon (October–May) maximum daily precipitation events. In 89% and 71% of years, at least one of the six detection grids experienced an AR‐related nonmonsoon maximum or annual maximum event, respectively. Overall, ARs explain 78% of daily precipitation totals exceeding 33 mm in the nonmonsoon season in comparison to 18% if the entire year is considered. As we show, ARs constitute a valuable new lens through which extreme precipitation in the region may be understood and forecasted. However, follow‐on integrated vapor transport analyses that more closely investigate the interaction between ARs and their synoptic‐scale environment are needed to better differentiate January and February ARs from Western Disturbances and June–September ARs from the Indian monsoon.

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Section: Resultsmentioning

confidence: 99%

Atmospheric Rivers Carry Nonmonsoon Extreme Precipitation Into Nepal

2018

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“…There have been extensive studies on the relationship between ARs and water resources at regional to global scales (Dettinger et al, ; Paltan et al, ). They demonstrated that ARs could contribute to a significant fraction of annual runoff.…”

Section: Discussionmentioning

confidence: 99%

Impact of Atmospheric Rivers on Surface Hydrological Processes in Western U.S. Watersheds

et al. 2019

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Atmospheric rivers (ARs) can significantly modulate surface hydrological processes through the extreme precipitation they produce. However, there is a lack of comprehensive evaluation of ARs' impact on surface hydrology. This study uses a high‐resolution regional climate simulation to quantify the impact of ARs on surface hydrological processes across the western U.S. watersheds. The model performance is evaluated through extensive comparison against observations. Our analysis indicates that ARs produce heavy precipitation but suppress evapotranspiration. Snowpack ablates more during ARs, with higher air temperature and increased longwave radiation playing the primary and secondary roles, respectively. At the 0 °C to 10 °C temperature range, ARs increase the probability of snow ablation from 0.33 to 0.57. The runoff‐to‐precipitation ratio is primarily controlled by antecedent soil moisture, but it almost doubles in the northwestern watersheds due to the intensification of snow ablation during AR events. From the analysis of the relationship between the hydrological responses and different meteorological factors, precipitation, temperature, and radiation are identified as the key drivers that distinguish the hydrologic responses between AR and non‐AR events. Lastly, analysis of ARs and total runoff at annual scale and 1 April snowpack and winter precipitation shows that ARs explain 30% to 60% of the variability of annual total runoff and sharpen the seasonality of water resources availability in the west coast mountain watersheds.

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“…Atmospheric rivers (ARs) are elongated regions of intense horizontal water vapor transport, which are often associated with a baroclinic midlatitude cyclone (Neiman et al, ; Ralph et al, ; Ralph et al, ; Zhang et al, ; Zhu & Newell, ). Many studies have revealed the important link between ARs and annual precipitation over different regions around the globe (Dettinger et al, ; Lavers et al, ; Ralph & Dettinger ; Neiman et al, ; Lavers & Villarini, ; Lamjiri et al, ; and others), their association with global floods and water availability (Ralph et al, ; Leung & Qian, ; Ralph & Dettinger ; Paltan et al, ; Corringham, ), their relationship to snowpack over the western U.S. (Goldenson et al, ; Guan et al, ; Huning et al, , ), their importance to extratropical climate and hydrology (Gorodetskaya et al, ; Nash et al, ), and their projected changes in a warming climate (e.g., Espinoza et al, ; Guirguis et al, ). In addition, a new AR scale has recently been introduced which groups ARs into categories based on their intensity, duration, and beneficial or hazardous impacts on society (Ralph et al, ).…”

Section: Introductionmentioning

confidence: 99%

Experimental Subseasonal‐to‐Seasonal (S2S) Forecasting of Atmospheric Rivers Over the Western United States

et al. 2019

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A multimodel evaluation of subseasonal‐to‐seasonal (S2S) hindcast skill of atmospheric rivers (ARs) out to 4‐week lead over the western United States is presented for three operational hindcast systems: European Centre for Medium‐Range Weather Forecasts (ECMWF; Europe), National Centers for Environmental Prediction (NCEP; U.S.), and Environment and Canada Climate Change (ECCC; Canada). Ensemble mean biases and Brier Skill Scores are examined for no, moderate, and high levels of AR activity (0, 1–2, and 3–7 AR days/week, respectively). All hindcast systems are more skillful in predicting no and high AR activity relative to moderate activity. There are isolated regions of skill at week‐3 over 150–125°W, 25–35°N for the no and high AR activity levels, with larger magnitude and spatial extent of the skill in ECMWF and ECCC compared to NCEP. The spatial pattern of this skill suggests that for high AR activity, a southwest‐to‐northeast orientation is more predictable at subseasonal lead times than other orientations, and for no AR activity, more skill exists in the subtropical North Pacific, upstream of central and southern California. AR hindcast skill along the western U.S. is most strongly increased in hindcasts initialized during Madden‐Julian Oscillation (MJO) Phases 1 and 8, and hindcast skill is substantially decreased over California in hindcasts initialized during MJO Phase 4. Skill modulations in the ECMWF hindcast system conditioned on El Niño‐Southern Oscillation phase are weaker than those conditioned on particular MJO phases. This work provides hindcast skill benchmarks and uncertainty quantification for experimental real‐time forecasts of AR activity during winters 2019–2021 as part of the S2S Prediction Project Real‐time Pilot Initiative in collaboration with the California Department of Water Resources.

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Global Floods and Water Availability Driven by Atmospheric Rivers

Cited by 116 publications

References 45 publications

Atmospheric Rivers Carry Nonmonsoon Extreme Precipitation Into Nepal

Atmospheric Rivers Carry Nonmonsoon Extreme Precipitation Into Nepal

Impact of Atmospheric Rivers on Surface Hydrological Processes in Western U.S. Watersheds

Experimental Subseasonal‐to‐Seasonal (S2S) Forecasting of Atmospheric Rivers Over the Western United States

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