MODELS FOR CLIMATIC RECONSTRUCTION UPON GLACIER EQUILIBRIUM-LINE ALTITUDE VARIATION

The glacier ELA (equilibrium-line altitude) is one of the important parameters responding to climate change. Glacier behaviors such as advancing or retreating are controlled by the variations in ELA. In contrast to variations in glacier length or area, variations in ELA respond almost simultaneously to climate change; therefore, it could be used to analyze the characteristics of climate change in different regions. The statistical models of climatic reconstruction based on variations in ELA (e.g., the model based on the relationship between temperature and precipitation at ELA, Lapse-rate model and Temperature index melt model) have simple structure, and can get better simulation results. However, all of them could not be derived from physical causes influencing the ELA variation (e.g., climatic factors). Furthermore, they became limited in use and unconvincing in theory when lacking sufficient data. The physical methods (e.g., Energy and mass balance model) are based on the energy factor influencing glacier change and related to the mechanism of ELA variation. Although this model has many parameters and is very complicated in algorithm, it could get more accurate results. Due to the effect of glacier types and the limitation of each model, the applicability and accuracy of the different models are variable.