Ocean bottom pressure (OBP) variability serves as a proxy of ocean mass variability. A question how well it can modeled by the present general ocean circulation models on time scales of 1 day and more is addressed. It is shown that the models simulate consistent patterns of bottom pressure variability on monthly and longer scales except for areas with high mesoscale eddy activity, where high resolution is needed. The simulated variability is compared to a new data set from an array of PIES (Pressure-Inverted Echo Sounder) gauges deployed along a transect in the Southern Ocean. We show that while the STD of monthly averaged variability agrees well with observations except for the locations with high eddy activity, models lose a significant part of variability on shorter time scales. Furthermore, despite good agreement in the amplitude of variability, the OBP from the PIES and simulation show almost no correlation. Our findings point to limitations in geophysical background models required for space geodetic applications. We argue that major improvements in OBP modelling require data assimilation in order to increase the coherence between modelled and observed signals.