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Title: Northern Hemisphere Blocking in ~25-km-Resolution E3SM v0.3 Atmosphere-Land Simulations

Abstract

The fidelity of a prerelease Energy Exascale Earth System Model (E3SM) in reproducing atmospheric blocking is evaluated with ~100- and ~25-km horizontal resolution within ensembles of simulations with Atmospheric Modeling Intercomparison Protocol-type active atmosphere and land surface configurations. This evaluation is conducted via a hybrid bidimensional blocking index based on geopotential height. The lower-resolution model correctly reproduces the spatial distribution of blocking frequency maxima over the Northern Hemisphere. However, it overestimates the blocking frequency over western North America, the Pacific Northeast, and Eastern Europe regions and largely underestimates blocking frequency over the North Atlantic. The high-resolution model significantly reduces the bias over the North Pacific region, particularly over western North America, but the biases over the North Atlantic blocking sector mostly persist. A diagnosis of the mean flow reveals that the subtropical jet is displaced poleward in the high-resolution model with a jet core speed that is generally more realistic. A time scale analysis of eddies suggests that synoptic eddies associated with the blocking events are increased in the high-resolution configuration. The discrepancy between the models implies that both synoptic and low-frequency eddies play significant roles in determining North Pacific blocking, whereas North Atlantic blocking is mainly driven by low-frequencymore » eddies. The characteristic time scale associated with blocking events is also investigated, and it shows that both model resolutions produce events that are overly persistent. However, the bias in the high-resolution model is reduced, which reflects more efficient energy dispersion with higher resolution.« less

Authors:
 [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [2]; ORCiD logo [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. National Center for Atmospheric Research, Boulder, CO (United States)
  4. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1497951
Alternate Identifier(s):
OSTI ID: 1504024
Report Number(s):
LLNL-JRNL-760251
Journal ID: ISSN 2169-897X; 948907
Grant/Contract Number:  
AC52-07NA27344; AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 124; Journal Issue: 5; Journal ID: ISSN 2169-897X
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Jiang, Tianyu, Evans, Katherine J., Branstetter, Marcia, Caldwell, Peter, Neale, Richard, Rasch, Philip J., Tang, Qi, and Xie, Shaocheng. Northern Hemisphere Blocking in ~25-km-Resolution E3SM v0.3 Atmosphere-Land Simulations. United States: N. p., 2019. Web. doi:10.1029/2018jd028892.
Jiang, Tianyu, Evans, Katherine J., Branstetter, Marcia, Caldwell, Peter, Neale, Richard, Rasch, Philip J., Tang, Qi, & Xie, Shaocheng. Northern Hemisphere Blocking in ~25-km-Resolution E3SM v0.3 Atmosphere-Land Simulations. United States. doi:10.1029/2018jd028892.
Jiang, Tianyu, Evans, Katherine J., Branstetter, Marcia, Caldwell, Peter, Neale, Richard, Rasch, Philip J., Tang, Qi, and Xie, Shaocheng. Tue . "Northern Hemisphere Blocking in ~25-km-Resolution E3SM v0.3 Atmosphere-Land Simulations". United States. doi:10.1029/2018jd028892.
@article{osti_1497951,
title = {Northern Hemisphere Blocking in ~25-km-Resolution E3SM v0.3 Atmosphere-Land Simulations},
author = {Jiang, Tianyu and Evans, Katherine J. and Branstetter, Marcia and Caldwell, Peter and Neale, Richard and Rasch, Philip J. and Tang, Qi and Xie, Shaocheng},
abstractNote = {The fidelity of a prerelease Energy Exascale Earth System Model (E3SM) in reproducing atmospheric blocking is evaluated with ~100- and ~25-km horizontal resolution within ensembles of simulations with Atmospheric Modeling Intercomparison Protocol-type active atmosphere and land surface configurations. This evaluation is conducted via a hybrid bidimensional blocking index based on geopotential height. The lower-resolution model correctly reproduces the spatial distribution of blocking frequency maxima over the Northern Hemisphere. However, it overestimates the blocking frequency over western North America, the Pacific Northeast, and Eastern Europe regions and largely underestimates blocking frequency over the North Atlantic. The high-resolution model significantly reduces the bias over the North Pacific region, particularly over western North America, but the biases over the North Atlantic blocking sector mostly persist. A diagnosis of the mean flow reveals that the subtropical jet is displaced poleward in the high-resolution model with a jet core speed that is generally more realistic. A time scale analysis of eddies suggests that synoptic eddies associated with the blocking events are increased in the high-resolution configuration. The discrepancy between the models implies that both synoptic and low-frequency eddies play significant roles in determining North Pacific blocking, whereas North Atlantic blocking is mainly driven by low-frequency eddies. The characteristic time scale associated with blocking events is also investigated, and it shows that both model resolutions produce events that are overly persistent. However, the bias in the high-resolution model is reduced, which reflects more efficient energy dispersion with higher resolution.},
doi = {10.1029/2018jd028892},
journal = {Journal of Geophysical Research: Atmospheres},
number = 5,
volume = 124,
place = {United States},
year = {2019},
month = {3}
}

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