NH3 emissions management in a nox reduction system

A system includes an internal combustion engine producing an exhaust gas, an aftertreatment system receiving the exhaust gas, the aftertreatment system including a particulate filter positioned upstream of an SCR catalyst component, and a urea injector operatively coupled to the aftertreatment system at a position upstream of the SCR catalyst component. The system further includes a controller that interprets an exhaust temperature value, an ambient temperature value, and a urea injection amount. The controller determines a urea deposit amount in response to the exhaust temperature value, the ambient temperature value, and the urea injection amount, and initiates a desoot regeneration event in response to the urea deposit amount. The desoot regeneration event includes operating the engine at a urea decomposition exhaust temperature.