Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

An Assessment of Intraseasonal Variability from 13-Yr GCM Simulations

An Assessment of Intraseasonal Variability from 13-Yr GCM Simulations An assessment of 13-yr simulations of three atmospheric general circulation models (AGCMs) forced by observed sea surface temperatures (SSTs) is presented. The National Centers for Environmental Prediction (NCEP) reanalysis data are used as a baseline for the comparisons. Daily circulation characteristics and interannual variability are investigated in order to improve understanding of the causes of systematic model errors. The focus is to determine the utility of these models in the field of seasonal forecasting. Daily circulation statistics are well represented by the Hadley Centre Atmospheric Climate Model (HADAM3) but the specific versions of the Center for Ocean–Land–Atmosphere Studies (COLA) and Commonwealth Scientific and Industrial Research Organization (CSIRO9) models examined here produce flow patterns biased toward atmospheric archetype modes characteristic of low spatial variability. All three models show relatively large errors in kinetic energy fields of the vertical mean and shear flow, both in latitudinal placement of the midlatitude jet and geographical location of energy maxima. Evidence suggests that model resolution and model physics affect the accuracy of these simulations. AGCM interannual variability as forced by sea surface temperatures is realistic in terms of a quasi-SOI (Southern Oscillation index) series and reproduces the El Niño–Southern Oscillation (ENSO) signal above noise levels that are determined from simulations using climatological SSTs. However, rainfall fields over southern Africa show little skill in interannual variability and daily rainfall characteristics indicate that some models are producing too many rain days by up to a factor of 2. Notwithstanding these difficulties, AGCMs, if used carefully, do provide sufficient skillful information for guidance in seasonal forecasting. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Monthly Weather Review American Meteorological Society

An Assessment of Intraseasonal Variability from 13-Yr GCM Simulations

Monthly Weather Review , Volume 131 (9) – Aug 13, 2002

Loading next page...
 
/lp/american-meteorological-society/an-assessment-of-intraseasonal-variability-from-13-yr-gcm-simulations-tQiGioZ2vn

References (49)

Publisher
American Meteorological Society
Copyright
Copyright © 2002 American Meteorological Society
ISSN
1520-0493
DOI
10.1175/1520-0493(2003)131<1975:AAOIVF>2.0.CO;2
Publisher site
See Article on Publisher Site

Abstract

An assessment of 13-yr simulations of three atmospheric general circulation models (AGCMs) forced by observed sea surface temperatures (SSTs) is presented. The National Centers for Environmental Prediction (NCEP) reanalysis data are used as a baseline for the comparisons. Daily circulation characteristics and interannual variability are investigated in order to improve understanding of the causes of systematic model errors. The focus is to determine the utility of these models in the field of seasonal forecasting. Daily circulation statistics are well represented by the Hadley Centre Atmospheric Climate Model (HADAM3) but the specific versions of the Center for Ocean–Land–Atmosphere Studies (COLA) and Commonwealth Scientific and Industrial Research Organization (CSIRO9) models examined here produce flow patterns biased toward atmospheric archetype modes characteristic of low spatial variability. All three models show relatively large errors in kinetic energy fields of the vertical mean and shear flow, both in latitudinal placement of the midlatitude jet and geographical location of energy maxima. Evidence suggests that model resolution and model physics affect the accuracy of these simulations. AGCM interannual variability as forced by sea surface temperatures is realistic in terms of a quasi-SOI (Southern Oscillation index) series and reproduces the El Niño–Southern Oscillation (ENSO) signal above noise levels that are determined from simulations using climatological SSTs. However, rainfall fields over southern Africa show little skill in interannual variability and daily rainfall characteristics indicate that some models are producing too many rain days by up to a factor of 2. Notwithstanding these difficulties, AGCMs, if used carefully, do provide sufficient skillful information for guidance in seasonal forecasting.

Journal

Monthly Weather ReviewAmerican Meteorological Society

Published: Aug 13, 2002

There are no references for this article.