Climatic mass balance, snow conditions and runoff in Svalbard (1957-2018), supplement to: van Pelt, Ward; Pohjola, Veijo A; Pettersson, Rickard; Marchenko, Sergey; Kohler, Jack; Luks, Bartłomiej; Hagen, Jon Ove; Schuler, Thomas V; Dunse, Thorben; Noël, Brice P Y; Reijmer, Carleen (2019): A long-term dataset of climatic mass balance, snow conditions, and runoff in Svalbard (1957-2018). The Cryosphere, 13(9), 2259-2280