The sum of the climatic mass balance and the basal mass balance. The expression b csfc asfc ci ai cb ab states that the climatic-basal mass balance b is the sum of surface accumulation csfc, surface ablation asfc, internal accumulation ci, internal ablation ai, basal accumulation cb and basal ablation ab. The sum of cb and ab is the basal mass balance. The sum of ci and ai is the internal mass balance. The sum of csfc and asfc is the surface mass balance. The sum of the surface mass balance and internal mass balance (the first four quantities on the right of the expression) is the climatic mass balance. The sum of the six quantities on the right (that is, of the climatic mass balance and the basal mass balance) is the climatic-basal mass balance. The climatic-basal mass balance includes all those components of mass change that do not arise from glacier flow or frontal ablation. The qualifier 'basal' does not exclude a role for the climate, for example through interactions between the atmosphere and the ocean.