A relative new way to obtain spatially averaged data directly and with a high spatial and temporal resolution is to apply tomographic methods in the atmospheric surface layer. One such method is acoustic travel time tomography that provides a cross section of the investigated area using the response of the medium of an external energy source. To prepare data for the application of a tomographic inversion, it is necessary to account for influences on the effective sound speed. Two techniques to obtain such data are the iterative solution and the reciprocal sound propagation. The former is especially suited to estimate area-averaged values, whereas the reciprocal method guarantees a clear separation of the influence of the wind and temperature effect on the effective sound speed.