A method of estimating lung motion (e.g., local lung motion and local lung ventilation) includes collecting a time series of ultrasound images of a lung surface, the time series including a plurality of frames, identifying a lung surface in one of the plurality of frames, and subsetting each of the plurality of frames into at least one sub-image. The method further includes applying a high pass temporal filter and a spatial filter. The method still further includes calculating inter-frame motion data from complex data sets associated with one or more pairs of temporally successive frames. In a further method, lung surface longitudinal strain is also calculated.