The Stability of Incremental Analysis Update

• Published in: Monthly weather review Vol. 146; no. 10; pp. 3259 - 3275
• Main Authors: Takacs, Lawrence L., Suárez, Max J., Todling, Ricardo
• Format: Journal Article
• Language: English
• Published: United States American Meteorological Society 01.10.2018
• Subjects: Analysis; Atmospheric circulation; Control stability; Data assimilation; Digital filters; Frameworks; General circulation models; Harmonic oscillators; Hybrid systems; Instability; Modulation; Oceanic analysis; Stability analysis; United States > US; Maryland

A recent attempt to downscale the 50-km MERRA-2 analyses to 7 km revealed an instability associated with the incremental analysis update (IAU) procedure that has thus far gone unnoticed. A theoretical study based on a simple damped harmonic oscillator with complex frequency provides the framework to...