The Autosegmental-Metrical model of American English distinguishes three pitch accents with rising F0 trajectories (H*, L+H*, L*+H), differing in peak alignment and presence vs. absence of a low pitch marking the rise onset. Empirical studies report additional distinctions in the dynamics and scaling of the F0 rise, raising the question of which properties best capture variation among accents. We use functional principal components analysis (FPCA) to examine dynamic properties of accentual F0 trajectories in data from an intonation imitation experiment. F0 trajectories from 70 speakers producing rising accents on the phrase-final (nuclear) accented word were submitted to FPCA. The first three PCs account for 95% of variation in F0 trajectories and each shows significant differences between the three rising accents. Variation in PC1 primarily relates to differences in the overall F0 level of the trajectory, PC2 captures differences in rise shape (scooped vs. domed rise) and PC3 captures fine variation from a following Low phrase accent. Alignment distinctions are distributed across all three PCs. Examination of individual speakers shows all use PC1 and PC2 to some degree to distinguish rising accents, with no trading relations. Rises are variously implemented through level or shape distinctions, to varying degrees across individuals.