(13) using the Theil-Sen slope estimation, yielding: $$\frac{{{d}}{U}}}{{{d}}t}} = - 0.08\;{\mathrm{m}}\;{\mathrm{s}}^{-1} \;{{{\mathrm{decade}}}^{ - 1}\;{{{\mathrm{and}}}\;\frac{{\partial S}}{{\partial {U}}}\frac{{{d}}{U}}}{{{d}}t}}\; = \...