Does the normal stress parallel to the sliding plane affect the friction of ice upon ice?

The article discusses a study of the effect of normal stress parallel to the sliding plane on the frictional resistance of the ice. The study analyzed columnar-grained, polycrystalline ice with the S2 growth texture. Results show that the resistance to sliding is not affected by the normal component of the stress tensor parallel to sliding direction. It mentions the role of sliding speed and temperature in the friction of ice. According to the authors, there are similarities between the character of sliding within the sea-ice cover and within test specimens in light of the slopes of the brittle compressive failure envelop of the arctic sea-ice cover and a laboratory-generated one.