Copula-based Correlation Structure for Multivariate Emission Distributions in Hidden Markov Models Reetam Majumder, University of Maryland Baltimore County; Nagaraj K Neerchal, University of Maryland, Baltimore County; Matthias K Gobbert, University of Maryland, Baltimore County; Amita Mehta, Joint Center for Earth Systems Technology, UMBC; Gerson Kroiz, University of Maryland, Baltimore County