Bayesian Hidden Markov Modelling Using Circular-Linear General Projected Normal Distribution

We introduce a multivariate hidden Markov model to jointly cluster observations with different support, i.e. circular and linear. Relying on the general projected normal distribution, our approach allows us to have clusters with bimodal marginal distributions for the circular variable. Furthermore, we relax the independence assumption between the circular and linear components observed at the same time. Such an assumption is generally used to alleviate the computational burden involved in the parameter estimation step, but it is hard to justify in empirical applications. We carry out a simulation study using different simulation schemes to investigate model behavior, focusing on how well the hidden structure is recovered. Finally, the model is used to fit a real data example on a bivariate time series of wind velocity and direction.