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A Technique Using Principal Component Analysis to Compare Seasonal Cycles of Earth Radiation from CERES and Model ComputationsA method for quantitatively comparing the seasonal cycles of two global data sets is presented. The seasonal cycles of absorbed solar radiation (ASR) and outgoing longwave radiation (OLR) have been computed from an eight-year data set from the Clouds and Earth's Radiant Energy System (CERES) scanning radiometers and from a model data set produced by the NASA Goddard Space Flight Center Global Modeling and Assimilation Office. To compare the seasonal cycles from these two data sets, principal component (PC) analysis is used, where the PCs express the time variations and the corresponding empirical orthogonal functions (EOFs) describe the geographic variations. Ocean has a long thermal response time compared to land, so land and ocean are separated for the analysis. The root-mean square values for the seasonal cycles of ASR and OLR are extremely close for the two data sets. The first three PCs are quite close, showing that the time responses and magnitudes over the globe are very similar. The agreement between the two sets of PCs is quantified by computing the matrix of inner products of the two sets. For ASR over land, the first PCs of CERES and the model agree to better than 99.9%. The EOF maps are similar for most of the globe, but differ in a few places, and the agreement of the EOF maps is likewise quantified. Maps of differences between the annual cycles show regions of agreement and disagreement.
Document ID
20140000597
Acquisition Source
Langley Research Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Smith, G. Louis
(Science Systems and Applications, Inc. Hampton, VA, United States)
Mlynczak, Pamela E.
(Science Systems and Applications, Inc. Hampton, VA, United States)
Potter, Gerald L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
February 7, 2014
Publication Date
May 11, 2012
Publication Information
Publication: Journal of Geophysical Research
Volume: 117
Issue: D9
Subject Category
Meteorology And Climatology
Report/Patent Number
NF1676L-16574
Funding Number(s)
WBS: WBS 921266.04.07.07
Distribution Limits
Public
Copyright
Other

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