Sensitivity of planetary waves to initial conditions and forcing

Abstract

The sensitivity of planetary waves to various initial conditions and thermal forcing is examined using a linear global primitive equation spectral model. Initial conditions are obtained by switching on a analytic heat source and then integrating the model equations out to 30 days. An averaging procedure is used to eliminate any transient modes which remained after integration so that the initial conditions represent steady state solutions. Additional integrations are performed in which 'errors' are introduced into the forcing and initial conditions. Results of the amplitude plots study are examined using polar phase vs amplitude plots (harmonic dials) of various spherical harmonics. Results indicate that planetary waves are not sensitive to errors in the forcing or initial conditions. However, this lack of sensitivity is most likely due to the simplified initial conditions used in the model rather than to the inherent sensitivity of planetary waves.