The thermal and hydrological regime of permafrost in the arid Andes is unique due to the combination of extreme aridity, high solar radiation, and significant diurnal temperature fluctuations. Drilling at Chachani (6,057 m.a.s.l.), Aucanquilcha (6,176 m.a.s.l.), Chajnantor (5,640 m.a.s.l.), and Ojos del Salado (6,893 m.a.s.l.) volcanoes revealed both dry permafrost and ice-rich permafrost in one of the driest areas on Earth. We monitored solar radiations and ground temperature conditions at twenty-four sites on eleven mountains between 1° and 33° S. At elevations above 5,800 m, the active layer is about 10 to 30 cm thick and is controlled by diurnal fluctuations. Near the lower limit of mountain permafrost (LLMP), the thermal offset is positive and ice-rich terrains are found that are associated with moisture percolating from penitentes. Above 6,400 m, the surface energy balance is dom...

Permafrost is present in the high-altitude mountains of the Trans-Mexican Volcanic Belt as well as the Andes, even in the extreme dry Atacama highland. The permafrost and active layer termal state are characterized at Latin American Permafrost Network study sites. Ice rich or extremely dry permafrost was observed during drilling operations from Mexico (Pico de Orizaba, 5636m a.s.l. Iztaccíhuatl, 5230m a.s.l.), Colombia, Ecuador (Chimborazo, 6263m a.s.l.), Peru (Coropuna 5250 m a.s.l., Ampato 5850 m a.s.l., Chachani 5600 m a.s.l.) including the highest human habitation in the world: La Rinconada 5100 m a.s.l., Bolivia (Chacaltaya 5300 m a.s.l. where glacier disappeared in 2005), and the Chilean/Argentinian border (up to 6750 m a.s.l. including Parinacota, Aucanquilcha, Ojos del Salado, Llullaillaco, Tupungato and Tupungatito). The Lower Limit of Alpine Permafrost (LLAP) is redrawn from t...