Aeration raises pH due to outgassing of CO2. As I understand it, the lower the pH, the faster CO2 is outgassed by aeration.
This doesn't really lower the TA, but it is part of the process by which TA is lowered. Acid lowers both TA and pH, then pH is raised by aeration, then more acid to lower the TA and pH, aeration to raise the ph again, etc., with the result being that the TA is reduced without taking the pH too low.