Seasonal mass balance components b(w) (winter balance) and b(s) (summer balance) as well as c(t) (rotal accumulation) and a, (total ablation), can be used directly to infer climate variables. In contrast, a(c) (net balance of the accumulation area) and a(a) (net balance of the ablation area), and b(a) or b(n) (annual or net balance) can not. The traditional Alpine system of observations of a(c) and a(a), however, can be converted to true seasonal values b(w) and b(s) if both pairs of components are simultaneously observed for some years, because a correlation between the two pairs of components exists. We analyzed b(w) and b(s) data and their mean, standard deviations and ratios of these to the corresponding net or annual balances for 50 glaciers with relatively long records representing different regions in the northern hemisphere. We also investigated correlations between seasonal components. A negative correlation between b(w) and b(s) exists at many glaciers. About two-thirds of the glaciers show insignificant correlations (-0.3<r<0.3). implying independence of summer and winter balances. In a few unusual cases the correlations are positive. These different correlations, or lack thereof, may offer insight into feedback conditions that must exist in this climate-related system. The correspondence of the b(w) and c(t), and b(s) and a(t), appears to depend largely on the relative amounts of summer snowfall, a function of their climatic environment expressed as ct [alpha = (b(w) + b(s))/2]. The contribution of variability of b(s) to the net balance increases markedly with decreasing values of alpha. The variability of b(w) and b(s), and therefore the net balance, has been increasing with time; whether this is due to an increase in climate variability or to other causes is not clear. It appears that b(w) has been increasing with time at the highest altitudes, but b(s) has been increasing more rapidly especially at low altitudes; the many-glacier average net balance is becoming more negative.
