Pacific Northwest climate sensitivity simulated by a regional climate model driven by a GCM. Part 1: Control simulations

Journal Article · Thu Jul 01 04:00:00 EDT 1999 · Journal of Climate

DOI:https://doi.org/10.1175/1520-0442(1999)012<2010:PNCSSB>2.0.CO;2· OSTI ID:6429710

Leung, L R; Ghan, S J ^[1]

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1. Pacific Northwest National Lab., Richland, WA (United States)

A model nesting approach has been used to simulate the regional climate over the Pacific Northwest. The present-day global climatology is first simulated using the NCAR Community Climate Model (CCM3) driven by observed sea surface temperature and sea ice distribution at T42 (2.8[degree]) resolution. This large-scale simulation is used to provide lateral boundary conditions for driving the Pacific Northwest National Laboratory Regional Climate Model (RCM). One notable feature of the RCM is the use of subgrid parameterizations of orographic precipitation and vegetation cover, in which subgrid variations of surface elevation and vegetation are aggregated to a limited number of elevation-vegetation classes. An airflow model and a thermodynamic model are used to parameterize the orographic uplift/descent as air parcels cross over mountain barriers or valleys. The 7-yr climatologies as simulated by CCM3 and RCM are evaluated and compared in terms of large-scale spatial patterns and regional means. Biases are found in the simulation of large-scale circulations, which also affect the regional model simulation. Therefore, the regional simulation is not very different from the CCM3 simulation in terms of large-scale features. However, the regional model greatly improves the simulation of precipitation, surface temperature, and snow cover at the local scales. This is shown by improvements in the spatial correlation between the observations and simulations. The RCM simulation is further evaluated using station observations of surface temperature and precipitation to compare the simulated and observed relationships between surface temperature-precipitation and altitude. The model is found to correctly capture the surface temperature-precipitation variations as functions of surface topography over different mountain ranges, and under different climate regimes.

• Sponsoring Organization: EPA; DOE; Environmental Protection Agency, Washington, DC (United States); USDOE, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6429710
• Journal Information: Journal of Climate, Journal Name: Journal of Climate Vol. 12:7; ISSN 0894-8755; ISSN JLCLEL
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring &amp; Transport-- (1990-)
ATMOSPHERIC CIRCULATION
C CODES
CLIMATE MODELS
CLIMATIC CHANGE
COMPUTER CODES
GENERAL CIRCULATION MODELS
MATHEMATICAL MODELS
R CODES
REGIONAL ANALYSIS