(iii) ZWDh values at the ERA Interim orography level have been computed from TCWV and 2T using the formula presented by Askne and Nordius (1987),in which the mean temperature of the troposphere was modelled from 2T according to Mendes et al.(2000). The corresponding ZWD value at station height, ZWDs, is obtained from ZWDh following the expression by Kouba (2008).