Abstract
We evaluate a high-resolution (0.25°), four-member ensemble simulation of the global climate (1979–2005) with the U.S. Department of Energy's Energy Exascale Earth System Model v0.3—forced with observed ocean surface temperatures and sea ice extent—for its ability to represent the North Atlantic Oscillation (NAO) teleconnections to winter precipitation extremes over western Europe. As compared to the low-resolution model (1°), it simulates a stronger impact of NAO on daily precipitation extremes over the western slopes of mountain ranges over southwestern Norway, northwestern United Kingdom, and the Western Balkan states. Precipitation extremes and their linear relationship with NAO are quantified using the generalized extreme value distribution. NAO-dependent large-scale (stratiform) precipitation intensity strengthens in the high-resolution model on seasonal time scales and plays a dominant role during simulated daily precipitation extremes. Improvements in the high-resolution model over these varied-topography regions largely appear to be due to finer resolved scales of motion that amplify NAO-dependent seasonal vertical moisture fluxes and enhance stable condensation. However, the high-resolution model simulates a weaker than observed impact of NAO on extratropical cyclone activity and total precipitable water, generally underperforming the low-resolution model These effects possibly offset the impact of enhanced vertical moisture fluxes on NAO-dependent precipitation extremes in the high-resolution model in these regions. Over the southwestern Iberian peninsula, the high-resolution model underperforms the low-resolution model simulating weaker than observed impact of NAO on precipitation extremes. This appears to be due to the reduction in total precipitable water despite an increase in NAO-dependent extratropical activity there.
| Original language | English |
|---|---|
| Pages (from-to) | 11,392-11,409 |
| Journal | Journal of Geophysical Research: Atmospheres |
| Volume | 123 |
| Issue number | 20 |
| DOIs | |
| State | Published - Oct 27 2018 |
Funding
All the data used are listed in the references. The E3SM code that produced the simulations as stated in section 3 is open source and can be accessed from https://e3sm.org/model. This research was supported as part of the Energy Exascale Earth System Model (E3SM) project, funded by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research. This manuscript has been authored by UT-Battelle, LLC, which is supported by the Office of Science of the U.S. Department of Energy under Contract DE-AC05-00OR22725. Work at Lawrence Livermore National Laboratory was performed under the auspices of the U.S. DOE under contract DE-AC52-07NA27344. This research used the resources of the Oak Ridge and Argonne Leadership Computing Facilities at the Oak Ridge and Argonne National Laboratories, respectively, and the National Energy Research Scientific Computing Center, which are supported by the Office of Science of the U.S. Department of Energy under Contracts DE-AC05-00OR22725, DE-AC02-06CH11357, and DE-AC02-05CH11231. We would like to thank two anonymous reviewers whose comments helped improve this work.
| Funders | Funder number |
|---|---|
| National Energy Research Scientific Computing Center | DE-AC02-05CH11231, DE-AC02-06CH11357 |
| Office of Biological and Environmental Research | DE-AC05-00OR22725 |
| U.S. Department of Energy | DE-AC52-07NA27344 |
| Office of Science | |
| Oak Ridge National Laboratory |