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Title: Simulations of Present and Future Climates in the Western United States with Four Nested Regional Climate Models

Abstract

We analyze simulations of present and future climates in the western U.S. performed with four regional climate models (RCMs) nested within two global ocean-atmosphere climate models. Our primary goal is to assess the range of regional climate responses to increased greenhouse gases in available RCM simulations. The four RCMs used different geographical domains, different increased greenhouse gas scenarios for future-climate simulations, and (in some cases) different lateral boundary conditions. For simulations of the present climate, we compare RCM results to observations and to results of the GCM that provided lateral boundary conditions to the RCM. For future-climate (increased greenhouse gas) simulations, we compare RCM results to each other and to results of the driving GCMs. When results are spatially averaged over the western U.S., we find that the results of each RCM closely follow those of the driving GCM in the same region, in both present and future climates. This is true even though the study area is in some cases a small fraction of the RCM domain. Precipitation responses predicted by the RCMs are in many regions not statistically significant compared to interannual variability. Where the predicted precipitation responses are statistically significant, they are positive. The models agree thatmore » near-surface temperatures will increase, but do not agree on the spatial pattern of this increase. The four RCMs produce very different estimates of water content of snow in the present climate, and of the change in this water content in response to increased greenhouse gases.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
882958
Report Number(s):
PNNL-SA-46110
KP1205030
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Climate, 19(6):873-895
Country of Publication:
United States
Language:
English
Subject:
increased atmospheric CO2; spectral model; Part 1: Change Scenarios; surface climate; precipitation; sensitivity; hydroclimate; California; resolution

Citation Formats

Duffy, Phil, Arritt, R., Coquard, J., Gutowski, William, Han, J., Iorio, J., Kim, Jongil, Leung, Lai R., Roads, J., and Zeledon, E. Simulations of Present and Future Climates in the Western United States with Four Nested Regional Climate Models. United States: N. p., 2006. Web. doi:10.1175/JCLI3669.1.
Duffy, Phil, Arritt, R., Coquard, J., Gutowski, William, Han, J., Iorio, J., Kim, Jongil, Leung, Lai R., Roads, J., & Zeledon, E. Simulations of Present and Future Climates in the Western United States with Four Nested Regional Climate Models. United States. doi:10.1175/JCLI3669.1.
Duffy, Phil, Arritt, R., Coquard, J., Gutowski, William, Han, J., Iorio, J., Kim, Jongil, Leung, Lai R., Roads, J., and Zeledon, E. Wed . "Simulations of Present and Future Climates in the Western United States with Four Nested Regional Climate Models". United States. doi:10.1175/JCLI3669.1.
@article{osti_882958,
title = {Simulations of Present and Future Climates in the Western United States with Four Nested Regional Climate Models},
author = {Duffy, Phil and Arritt, R. and Coquard, J. and Gutowski, William and Han, J. and Iorio, J. and Kim, Jongil and Leung, Lai R. and Roads, J. and Zeledon, E.},
abstractNote = {We analyze simulations of present and future climates in the western U.S. performed with four regional climate models (RCMs) nested within two global ocean-atmosphere climate models. Our primary goal is to assess the range of regional climate responses to increased greenhouse gases in available RCM simulations. The four RCMs used different geographical domains, different increased greenhouse gas scenarios for future-climate simulations, and (in some cases) different lateral boundary conditions. For simulations of the present climate, we compare RCM results to observations and to results of the GCM that provided lateral boundary conditions to the RCM. For future-climate (increased greenhouse gas) simulations, we compare RCM results to each other and to results of the driving GCMs. When results are spatially averaged over the western U.S., we find that the results of each RCM closely follow those of the driving GCM in the same region, in both present and future climates. This is true even though the study area is in some cases a small fraction of the RCM domain. Precipitation responses predicted by the RCMs are in many regions not statistically significant compared to interannual variability. Where the predicted precipitation responses are statistically significant, they are positive. The models agree that near-surface temperatures will increase, but do not agree on the spatial pattern of this increase. The four RCMs produce very different estimates of water content of snow in the present climate, and of the change in this water content in response to increased greenhouse gases.},
doi = {10.1175/JCLI3669.1},
journal = {Journal of Climate, 19(6):873-895},
number = ,
volume = ,
place = {United States},
year = {Wed Mar 15 00:00:00 EST 2006},
month = {Wed Mar 15 00:00:00 EST 2006}
}
  • We analyze simulations of present and future climates in the western U.S. performed with four regional climate models (RCMs) nested within two global ocean-atmosphere climate models. Our primary goal is to assess the range of regional climate responses to increased greenhouse gases in available RCM simulations. The four RCMs used different geographical domains, different increased greenhouse gas scenarios for future-climate simulations, and (in some cases) different lateral boundary conditions. For simulations of the present climate, we compare RCM results to observations and to results of the GCM that provided lateral boundary conditions to the RCM. For future-climate (increased greenhouse gas)more » simulations, we compare RCM results to each other and to results of the driving GCMs. When results are spatially averaged over the western U.S., we find that the results of each RCM closely follow those of the driving GCM in the same region, in both present and future climates. In present-climate simulations, the RCMs have biases in spatially-averaged simulated precipitation and near-surface temperature that seem to be very close to those of the driving GCMs. In future-climate simulations, the spatially-averaged RCM-projected responses in precipitation and near-surface temperature are also very close to those of the respective driving GCMs. Precipitation responses predicted by the RCMs are in many regions not statistically significant compared to interannual variability. Where the predicted precipitation responses are statistically significant, they are positive. The models agree that near-surface temperatures will increase, but do not agree on the spatial pattern of this increase. The four RCMs produce very different estimates of water content of snow in the present climate, and of the change in this water content in response to increased greenhouse gases.« less
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