Temperature-precipitation equilibrium-line altitude (TP-ELA) and temperature-precipitation- wind equilibrium-line altitude (TPW-ELA) in High Zagros

The equilibrium-line altitude (ELA) is generally dependent on the accumulation of snow which is influenced by the regional distribution of snow precipitation and local redistribution of snow by wind. Due to the effect of wind-blown snow on ELAs, the terms temperature-precipitation equilibrium-line altitude (TP-ELA) and temperature-precipitation wind equilibrium-line altitude (TPW-ELA) is introduced to distinguish between glacier ELAs reflecting the general winter precipitation and ablation season temperature in a region and glacier ELAs that are influenced by either snow deflation or accumulation (such as on cirque glaciers). In this study the TP-ELA in presently glaciated (Zardkuh and Oshtorankuh) and non-glaciated (Dena, Garein and Shahoo) areas is calculated. The altitude of small glaciers is also used to estimate the TPW-ELA. Based on this approach, regional climatic TP-ELA in Zardkuh, Oshtorankuh, Garein, Shahoo and Dena mountains is between 4400 to 4500 m a.s.l.(above main summits of the Zagros Mountains) TPW-ELA is around 3850 m a.s.l. in Zardkuh and Oshtorankuh Mountains which is 650 m lower than the regional TP-ELA. The present small glaciers in Zardkuh and Oshtorankuh are the result of leeward accumulation of wind-blown snow on small glacial cirques.