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Decadal Prediction Skill in the GEOS-5 Forecast SystemA suite of decadal predictions has been conducted with the NASA Global Modeling and Assimilation Office's (GMAO's) GEOS-5 Atmosphere-Ocean general circulation model. The hind casts are initialized every December 1st from 1959 to 2010, following the CMIP5 experimental protocol for decadal predictions. The initial conditions are from a multivariate ensemble optimal interpolation ocean and sea-ice reanalysis, and from GMAO's atmospheric reanalysis, the modern-era retrospective analysis for research and applications. The mean forecast skill of a three-member-ensemble is compared to that of an experiment without initialization but also forced with observed greenhouse gases. The results show that initialization increases the forecast skill of North Atlantic sea surface temperature compared to the uninitialized runs, with the increase in skill maintained for almost a decade over the subtropical and mid-latitude Atlantic. On the other hand, the initialization reduces the skill in predicting the warming trend over some regions outside the Atlantic. The annual-mean Atlantic meridional overturning circulation index, which is defined here as the maximum of the zonally-integrated overturning stream function at mid-latitude, is predictable up to a 4-year lead time, consistent with the predictable signal in upper ocean heat content over the North Atlantic. While the 6- to 9-year forecast skill measured by mean squared skill score shows 50 percent improvement in the upper ocean heat content over the subtropical and mid-latitude Atlantic, prediction skill is relatively low in the sub-polar gyre. This low skill is due in part to features in the spatial pattern of the dominant simulated decadal mode in upper ocean heat content over this region that differ from observations. An analysis of the large-scale temperature budget shows that this is the result of a model bias, implying that realistic simulation of the climatological fields is crucial for skillful decadal forecasts.
Document ID
20150008258
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Ham, Yoo-Geun
(Universities Space Research Association Greenbelt, MD, United States)
Rienecker, Michele M.
(Retired)
Suarez, Max J.
(Universities Space Research Association Greenbelt, MD, United States)
Vikhliaev, Yury
(Universities Space Research Association Greenbelt, MD, United States)
Zhao, Bin
(Science Applications International Corp. Greenbelt, MD, United States)
Marshak, Jelena
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Vernieres, Guillaume
(Science Systems and Applications, Inc. Greenbelt, MD, United States)
Schubert, Siegfried D.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
May 18, 2015
Publication Date
December 14, 2013
Publication Information
Publication: Climate Dynamics
Publisher: Springer
Volume: 42
Issue: 2-Jan
Subject Category
Oceanography
Earth Resources And Remote Sensing
Meteorology And Climatology
Report/Patent Number
GSFC-E-DAA-TN21507
Funding Number(s)
CONTRACT_GRANT: NNG12HP06C
CONTRACT_GRANT: NNG11HP16C
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
Decadal Prediction
AMOC
GEOS-5 AOGCM
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