(a) Hydrographic stations A and B are 100 km apart at 30° of latitude. Temperature and salinity measurements at the two stations indicate that PA = 1.0265 x 10³ kg m-3 and PB = 1.0262 x 10³ kg m-³. Calculate the geostrophic velocity u at depth z₁ = 1000 m, taking your reference level (zo) as 2000 m (in order to apply Equation 3.13 you will have to make the assumption that hg and zo-z₁ are equal). The value for g is 9.8 ms-2. (b) (i) Use Equation 3.12 to calculate the difference hB - hĄ. How valid was the assumption, made above, that hB = Zo-z₁? (ii) Use your value for hв - hA to calculate tan 0 (i.e. the slope of the isobar at 1000 m depth), and the angle 0 itself. (c) If stations A and B are in the Southern Hemisphere, with B due east of A, in which direction is the geostrophic current flowing? Given that the conventional symbols for indicating flow direction are for 'flow into the page' and for 'flow out of the page', draw a simple diagram to illustrate this situation (A on the left, B on the right). Show the sloping sea-surface and the sloping isobar at 1000 m depth, and arrows representing the horizontal pressure gradient force and the Coriolis force either side of the appropriate symbol for flow direction.