A long-term perspective of the hydroclimatological impacts of atmospheric rivers over the central United States

Water Resources Research | Nayak & Villarini [2017]

Abstract

The focus of this study is on the climatology of atmospheric rivers (ARs) over the central United States using six atmospheric reanalysis products. This climatology is used to understand the long-term impacts of ARs on annual precipitation, precipitation extremes, and flooding over the central United States. The relationship between the frequency of ARs and three prominent large-scale atmospheric modes [Pacific-North American (PNA) teleconnection, Artic Oscillation (AO), and North Atlantic Oscillation (NAO)] is investigated, and the results are used to statistically model the frequency of ARs at the seasonal scale.

AR characteristics (e.g., frequency, duration) are generally robust across the different reanalysis products. ARs exhibit a marked seasonality, with the largest activity in winter (more than ten ARs per season on average), and the lowest in summer (less than two ARs per season on average). Overall, the duration of most ARs is less than three days, but exceptionally persistent ARs (more than six days) are also observed.

The year-to-year variations in the total annual precipitation over the central United States are largely explained by the variations in AR-related precipitation. Moreover, 40% of the top 1% daily precipitation extremes are associated with ARs, and more than 70% of the annual instantaneous peak discharges and peaks-over-threshold floods are associated with these storms, in particular during winter and spring.

The seasonal frequency of ARs can be described in terms of large-scale atmospheric modes, with PNA playing a major role in particular in winter and spring.

Full text can be found here.

 

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