In this paper, a unified trajectory model based on the stylization and the modelling of f0 variations simultaneously over various temporal domains is proposed. The syllable is used as the minimal temporal domain for the description of speech prosody, and short-term and long-term f0 variations are stylized and modelled simultaneously over various temporal domains. During the training, a context-dependent model is estimated according to the joint stylized f0 contours over the syllable and a set of long-term temporal domains. During the synthesis, f0 variations are determined using the long-term variations as trajectory constraints. In a subjective evaluation in speech synthesis, the stylization and trajectory modelling of short and long term speech prosody variations is shown to consistently model speech prosody and to outperform the conventional short-term modelling.