The AAR at the end of the mass-balance year. Annual AARs can vary greatly from year to year, but an average over a number of years, when compared with the Balanced-budget AAR, gives a measure of the h
ealth of the glacier. If the difference is large and in the same direction over a considerable time, a prolonged period of non-zero mass balance can be expected as the glacier seeks equilibrium.
Ablation integrated over the mass-balance year. Annual ablation is the sum of winter ablation and summer ablation where winter and summer are well-differentiated. Formerly it was referred to as 'total
ablation' when working in the stratigraphic system.
Accumulation integrated over the mass-balance year. Annual accumulation is the sum of winter accumulation and summer accumulation where winter and summer are well-differentiated. Formerly it was refer
red to as 'total accumulation' when working in the stratigraphic system.
The ELA at the end of the mass-balance year. The Annual ELA is not in general the same as the average altitude of the Annual snowline. The superimposed ice zone lies below the Annual snowline and abov
e the Annual ELA. However, if there is no superimposed ice, the Annual snowline can be used as a proxy for the Annual ELA.
An irregularity in the Moon's orbit, which can amount to 11 degrees in a period of one year. It results from the Sun's disturbing effect on the motion of the Moon due to varying distance between them.