| Abstract | The study of the Earth's glaciers and ice sheets is of tremendous importance as their fluctuation has consequences on sea-level, river flow, ecosystem functioning, ocean circulation and climate
stability. Recent studies have shown that the Earth's small glaciers are in measurable decline on account of secular atmospheric warming (Kaser et al., 2007; UNEP/WGMS, 2009), and whose environmental services (e.g., hydrological regulation) vary
regionally - from short-term flow augmentation to long-term decline (Bonardi, 2008; Cassasa et al., 2008; Sauchyn et al., 2009). There is considerable concern regarding the state and evolution of the Earth's larger glacier systems and the ice
sheets, and their effect on global sea levels (Abdalati, et al., 2002; Arendt et al., 2004; Zwalley et al., 2002; Rignot and Thomas, 2002; Thomas et al., 2006; Bamber, et al., 2007; van de Wal et al., 2008; Alley et al., 2009; Thomas et al., 2009;
Vinther, et al., 2009).
Increasingly, remote sensing tools have been used to study and understand in a more comprehensive, regional manner, the sign, magnitude, rate and causality of the Earth's glacier and ice sheet mass balance changes.
Reflecting on the Greenland ice sheet, Reeh (1999) suggested that modern observation methods in combination with trimline observations, large-scale snow accumulation and mass flux estimates, and ice sheet modeling could, in combination, reduce the
uncertainty associated with understanding its mass balance variation. It has also been recognized for some time that the worldwide glacier surveillance strategy has historically been biased to relatively small glacier sizes, with large glacier
systems being relatively under represented (Haeberli et al., 1998). The application of laser-based detection and ranging strategies, including the support they provide for glacier and ice sheet mass and energy balance studies, plays a key role in
addressing these thematic concerns, methodological opportunities and surveillance biases.
The following reviews the principle of lidar, its integration as an instrument in typical glacier surveillance applications, and important error
considerations. The capability of lidar is illustrated with numerous examples from the available literature. Survey planning considerations and specific technical challenges are also discussed. |