Neumayer Station (GVN)
Till 1998-02-17 the direct radiation was measured on a one axis tracker (Eppley ST1). For the diffuse radiation a shadow band (diameter = 58 cm, width = 5 cm) was used. Thus, a certain fraction of the diffuse radiation could not be measured and SumSW stays normally below SWD.
Later, the one axis tracker was replaced by a two axis tracker (SCI-TEC 2AP) including shadow balls for the diffuse radiation.