1. A method for controlling reductant injection into an exhaust aftertreatment system for an internal combustion engine, wherein the exhaust aftertreatment system includes a selective catalytic reduction device (SCR), a NOx sensor disposed to monitor the exhaust gas feedstream downstream relative to the SCR, and a reductant injection system disposed to inject reductant into the exhaust gas feedstream upstream relative to the SCR, the method comprising: monitoring engine operation; determining an initial reductant dosing rate responsive to the engine operation; inducing a dosing perturbation in the initial reductant dosing rate; monitoring, via the NOx sensor, the exhaust gas feedstream downstream relative to the SCR; determining, via a controller, a reductant dosing correction term based upon a signal output from the NOx sensor, including: estimating NOx breakthrough output from the SCR and an amount of ammonia stored on the SCR based upon engine and exhaust system operating parameters associated with the monitored engine operation, executing a time-synchronized correlation between the estimated NOx breakthrough output from the SCR, the signal output from the NOx sensor, and the amount of ammonia stored on the SCR, and determining the reductant dosing correction term based upon the time-synchronized correlation of the estimated NOx breakthrough output from the SCR, the amount of ammonia stored on the SCR and the signal output from the NOx sensor; determining a final dosing rate for controlling the reductant injection system based upon the initial reductant dosing rate, the dosing perturbation, and the reductant dosing correction term; and controlling the reductant injection system based upon the final dosing rate.