Several dry-runs of SSMIS Cal/Val have been carried out to prepare for post-launch Cal/Val. One of them was conducted in April 2002. The primary objective was to evaluate the accuracy of radiative transfer calculations as a means of calibrating sounding channels. Temperature and water vapor profiles were measured by The Aerospace Corporation lidar at Barking Sands, Hawaii. Collocated and coincident data from SSM/I, SSM/T-1, SSM/T-2 and AMSU were collected by Aerospace personnel at Air Force Weather Agency (AFWA). Temperature and water vapor profiles from operational radiosonde network as well as numerical meteorological forecast models were also gathered to provide broader spatial and temporal coverage. Radiative transfer calculations have been performed to generate simulated brightness temperatures. Simulations from lidar and radiosonde measured atmospheric profiles were compared with collocated and coincident observations from SSM/I, SSM/T-1 and SSM/T-2. Comparison results will be presented at the conference.