How does the change in pressure conditions over the Southern oceans affect the monsoons?

How does the change in pressure conditions over the Southern oceans affect the monsoons?

The change in pressure conditions over the Southern oceans affects the monsoon as
(i) When the tropical Eastern South Pacific Ocean experiences high pressure, the tropical Eastern Indian Ocean experiences low pressure. In this condition, the monsoon rainfall will be average.
(ii) In some years, it is reverse when pressure difference is negative - means below average and late monsoon.
(iii) The change in pressure conditions is connected to the EL Nino.