The length of the melt season averaged fromthe NEP test pointswas
133 days,with averages of 121, 107, 92, 109, and 246 days for the Chukchi,
East Siberian, Laptev, Kara, and Barents sectors, respectively. These
numbers were comparable with the open periods defined by the ice
concentration threshold of 75%. Compared with the onset of surface
melting, the melt season was more dependent on freeze-up (Table 4).
Most NEP test points (97%) showed a trend toward a longermelt season
significant at the 0.05 level, even though the trends of the surface melt
onset were mostly ambiguous. The long-term trend in the length of
the melt season averaged over the NEP test points was +1.65 days
per year.