Role of large-scale climate oscillations in precipitation extremes associated with atmospheric rivers: nonstationary framework

ABSTRACT

Atmospheric rivers (ARs) are filamentary regions of high-water vapour flux in the lower troposphere that contribute significantly to poleward moisture movement in mid-latitude regions. Key characteristics (frequency, duration, and intensity) of ARs have been explored to recognize the regions vulnerable to AR-flood. To investigate the association of ARs with large-scale climate oscillations (LSCOs), precipitation extremes (PEs) maximum 1-day precipitation (Rx1day), maximum consecutive 5-day precipitation (Rx5day), precipitation amount from very wet days (R95pTOT) are explored in a non-stationary framework of generalized extreme value distribution, taking the Arctic Oscillation, North Atlantic Oscillation, El Niño Southern Oscillation, and Pacific Decadal Oscillation (PDO) as covariates. In almost 30% of regions around the globe, May-June-July-August-September (MJJAS) season PDO was found to be the relatively most influential covariate for capturing PEs. The west coast of North America and of Europe, southernmost South America, central East Asia, New Zealand, and Australia have been identified as the most critical regions associated with AR linked with PE-associated LSCOs.

KEYWORDS:

• atmospheric rivers
• large-scale climate oscillations
• nonstationary
• integrated water vapour transport
• precipitation extremes

Editor A. Castellarin Associate Editor M. Ionita

Editor A. Castellarin Associate Editor M. Ionita

Acknowledgements

The authors are thankful to the European Centre for Medium-Range Weather Forecasts (ECMWF) for providing Reanalysis datasets (ERA-5) data for providing our datasets of specific density, zonal and meridional wind velocities at 21 pressure levels and precipitation data from 1979 to 2018. We are also grateful to the Physical Science Laboratory of NOAA for providing the teleconnection (AO, NAO, ENSO [SST (Nino 3.4)] and PDO) datasets.

Data availability

The ERA-5 reanalysis data (specific density; zonal and meridional wind velocities) at 21 pressure levels from 1000 to 300 hPa, and precipitation data at the surface level from 1979 to 2018, were received from ECMWF and are openly accessible (https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-pressure-levels?tab=form). The teleconnections (NAO, AO, SST (Nino 3.4) and PDO) data were obtained from the Physical Science Laboratory of NOAA and are available for open access (https://www.ncdc.noaa.gov/teleconnections/).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/02626667.2022.2159412