The authors wish to thank Dr. Chris Snyder for valuable discussions on the quasigeostrophic model and adjoint coding, and Dr. Carolyn Reynolds for insightful discussion and thoughtful comments on an earlier version of the manuscript. The authors also acknowledge Dr. Eugenia Kalnay for useful discussions at an earlier stage of the work. Some of the results were generated using computing resources at the National Center for Atmospheric Research, and the authors especially appreciate Pat Waukau allowing the use of those resources. The authors are very grateful to Dr. James Hansen, Dr. Thomas Hamill, Linda Keller, and an anonymous reviewer for their valuable comments that helped improve this manuscript. This work was supported by National Science Foundation Grants ATM- 9810916 and ATM-0121186 and “A Study on the Global Ocean/Climate Variability and Predictability with Array for Real-Time Geostrophic Oceanography (ARGO) Program” at the Meteorological Research Institute of the Korea Meteorological Administration.
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