Relative humidity is a measure of how much an air mass at a given temperature can hold.

Water.

Explanation:

The relative humidity can be defined as the amount of the water vapor that is present in the air and at a given temperature and this thus the ration of the columns of the air mass s held by the water in the air.

Water flows along the east coast and across the western tropical pacific towards south america, while they both are directed towards that way,  el niño does not directly affect the southern flow of water along the coast.