In the GPM era, physical retrievals of precipitation over land using passive microwave radiometers will require the ability to separate emission contributions from the atmosphere from those of the surface. This requires information about the nature of the surface, it's dynamic properties, and the effective result of these (along with their heterogeneity) as viewed from the space borne sensor. In an effort to gain insight into these parameters and how they might effect future physical retrievals of precipitation, three datasets are assembled for analysis. Oklahoma is chosen as a study area so as to utilize it's high-density network of available observations. Nine years of clear sky satellite emissivity retrievals are performed over the region using AMSR-E satellite overpasses. Retrieved values are compared with 9 years of modeled values compiled from a combination of land surface model results and a forward emissivity model. Brightness temperatures computed from each will then be compared to the observations. In addition, data from the recent MC3E field campaign over the region will be analyzed comparing brightness temperatures measured using instruments above the ER2 high altitude aircraft with coincident surface measurements. Results will be interpreted in terms of their correlation to surface parameters such as soil type, soil moisture, and vegetation, in an attempt to pinpoint information that will be necessary for a future physical precipitation retrieval for passive microwave sensors.