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Title: Internal variability of a dynamically downscaled climate over North America

Abstract

This study investigates the internal variability (IV) of a regional climate model, and considers the impacts of horizontal resolution and spectral nudging on the IV. A 16-member simulation ensemble was conducted using the Weather Research Forecasting model for three model configurations. Ensemble members included simulations at spatial resolutions of 50 km and 12 km without spectral nudging and simulations at a spatial resolution of 12 km with spectral nudging. All the simulations were generated over the same domain, which covered much of North America. The degree of IV was measured as the spread between the individual members of the ensemble during the integration period. The IV of the 12 km simulation with spectral nudging was also compared with a future climate change simulation projected by the same model configuration. The variables investigated focus on precipitation and near-surface air temperature. While the IVs show a clear annual cycle with larger values in summer and smaller values in winter, the seasonal IV is smaller for a 50-km spatial resolution than for a 12-km resolution when nudging is not applied. Applying a nudging technique to the 12-km simulation reduces the IV by a factor of two, and produces smaller IV than the simulationmore » at 50 km without nudging. Applying a nudging technique also changes the geographic distributions of IV in all examined variables. The IV is much smaller than the inter-annual variability at seasonal scales for regionally averaged temperature and precipitation. The IV is also smaller than the projected changes in air-temperature for the mid- and late 21st century. However, the IV is larger than the projected changes in precipitation for the mid- and late 21st century.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
U.S. Department of Defense (DOD)
OSTI Identifier:
1411037
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Climate Dynamics; Journal Volume: 2017
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Internal variability; climate change; high spatial resolution; regional climate model; spectral nudging

Citation Formats

Wang, Jiali, Bessac, Julie, Kotamarthi, Rao, Constantinescu, Emil, and Drewniak, Beth. Internal variability of a dynamically downscaled climate over North America. United States: N. p., 2017. Web. doi:10.1007/s00382-017-3889-1.
Wang, Jiali, Bessac, Julie, Kotamarthi, Rao, Constantinescu, Emil, & Drewniak, Beth. Internal variability of a dynamically downscaled climate over North America. United States. doi:10.1007/s00382-017-3889-1.
Wang, Jiali, Bessac, Julie, Kotamarthi, Rao, Constantinescu, Emil, and Drewniak, Beth. 2017. "Internal variability of a dynamically downscaled climate over North America". United States. doi:10.1007/s00382-017-3889-1.
@article{osti_1411037,
title = {Internal variability of a dynamically downscaled climate over North America},
author = {Wang, Jiali and Bessac, Julie and Kotamarthi, Rao and Constantinescu, Emil and Drewniak, Beth},
abstractNote = {This study investigates the internal variability (IV) of a regional climate model, and considers the impacts of horizontal resolution and spectral nudging on the IV. A 16-member simulation ensemble was conducted using the Weather Research Forecasting model for three model configurations. Ensemble members included simulations at spatial resolutions of 50 km and 12 km without spectral nudging and simulations at a spatial resolution of 12 km with spectral nudging. All the simulations were generated over the same domain, which covered much of North America. The degree of IV was measured as the spread between the individual members of the ensemble during the integration period. The IV of the 12 km simulation with spectral nudging was also compared with a future climate change simulation projected by the same model configuration. The variables investigated focus on precipitation and near-surface air temperature. While the IVs show a clear annual cycle with larger values in summer and smaller values in winter, the seasonal IV is smaller for a 50-km spatial resolution than for a 12-km resolution when nudging is not applied. Applying a nudging technique to the 12-km simulation reduces the IV by a factor of two, and produces smaller IV than the simulation at 50 km without nudging. Applying a nudging technique also changes the geographic distributions of IV in all examined variables. The IV is much smaller than the inter-annual variability at seasonal scales for regionally averaged temperature and precipitation. The IV is also smaller than the projected changes in air-temperature for the mid- and late 21st century. However, the IV is larger than the projected changes in precipitation for the mid- and late 21st century.},
doi = {10.1007/s00382-017-3889-1},
journal = {Climate Dynamics},
number = ,
volume = 2017,
place = {United States},
year = 2017,
month = 9
}
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