Measured average noise rates of 120 DOMs as function of DOM temperature. The excess of short time intervals due to bursts (solid) is fitted to the empirical model of Meyer (2010). The Poissonian contribution (dashed) has not been corrected for the depth (and thus temperature) dependent contribution of atmospheric muons (see Fig. 7). The dotted line is a comparison to the predicted thermal noise from Richardson’s law plus a constant rate of C = 225 ± 6 Hz.