Complex sentence: Greenberg and Petrie (1988) calculated a total transport of 7.6 Sv while the geostrophic transport was calculated to be just 4.1 Sv (based on IIP sections).
Split into simpler sentences: Greenberg and Petrie (1988) calculated a total transport of 7.6 Sverdrup. The geostrophic transport was calculated to be just 4.1 Sv (based on IIP sections).