Why is the atmospheric presure measured at sea level?

Atmospheric pressure is measured by a

Atmospheric pressure is measured by

The density of air in atomsphere decreases with height and can be expressed by the relation. rho=rho_(0)e^(-Ah) Where rho_(0) is the density at sea-level, A is a constant and h is the height. Calculate the atmospheric pressure at sea -level. assume g to be constant.

On the surface of earth, the atmospheric pressure is minimum at the sea-level.

Estimate the pressure deep inside the sea at a depth h below the surface. Assume that the density fo water is rho_(0) at sea level and its bulk modulus is B. P_(0) is the atmosphere pressure at sea level P is the pressure at depth 'h'