Suppose I have two bivariate time series:
$$ ts1 = [<a_1, b_1>, <a_2, b_2>, \cdots, <a_N, b_N>] $$
$$ ts2 = [<c_1, d_2>, <c_2, d_2>, \cdots, <c_N, d_N>] $$
Which metrics can I use to measure the "similarity" of $ts1$ and $ts2$? And which test can I use to determine if the "similarity" is significant or not?