State of High‐Altitude Permafrost on Tropical Maunakea Volcano, Hawaii

Arctic, Antarctic, and Alpine Research

Hardy

Narita

et al. 2021

Self Cite

Tropical mountain permafrost has a unique thermal regime due to ground surface exposure to strong solar radiation. The intensity of the surface offset resulting from snow cover also strongly affects the absence or presence of permafrost. Latent heat transfer and reflected solar radiation (higher albedo) that occur during the snow-covered season contribute to a positive feedback that cools the ground. Eleven ground temperature monitoring sites were established on the mountain at 2,780 to 5,820 m.a.s.l. The geothermal heat flow is locally high in the caldera of this volcano, as shown by borehole temperature data. Permafrost is located near the only glacier entirely within the caldera (Furtwängler). These threeyear continuous records of ground temperature data encompass years of high and low snow cover. Our results show that the current lower boundary of permafrost is slightly above summit altitude and relict permafrost is present due to the influence of saturated sand on latent heat transfer. Permafrost tends to be lost more rapidly during drought years. The remaining permafrost seems likely to disappear in the future. The presence of permafrost and its thermal resistance depends on the ice content of caldera sand and the duration of snow cover.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ground thermal regimes and implications for permafrost distribution on Kilimanjaro, Tanzania

Arctic, Antarctic, and Alpine Research

Hardy

Narita

et al. 2021

Self Cite

“…have been eroded only by the latest glacial advances. Those lava flows have been dated by 3 He and 36 Cl to~14.0-6.0, 2.1-2.0 and~1.6-0.7ka, respectively, supporting evidence of recent volcanic activity at Coropuna. 20,22,23 About 140 km southeast of Nevado Coropuna is Nevado Chachani (16 11 0 S, 71 31 0 W; 6,057 m a.s.l.…”

Section: Study Areamentioning

confidence: 71%

“…Tropical high‐mountain permafrost has been reported from Mauna Kea, Hawaii, 1–3 Iztaccíhuatl 4 and Pico de Orizaba, Mexico, 5 Kilimanjaro, Tanzania, 2,6 and the Southern Peruvian Andes 2,6 . Typically, the lower boundary of the permafrost is reported to be over 5,000 m on the polar‐facing slopes (between 15° and 23°N and S) and around 6,000 m on the equatorial‐facing slopes.…”

Section: Introductionmentioning

confidence: 99%

Current thermal state of permafrost in the southern Peruvian Andes and potential impact from El Niño–Southern Oscillation (ENSO)

Permafrost & Periglacial

Úbeda

Masías

et al. 2020

Self Cite

Tropical high-mountain permafrost has a unique thermal regime due to its exposure to strong solar radiation and to rough surface snow morphology, which reduce ground heat transfer from the surface. Latent heat transfer and higher albedo that occur during the snow-covered season contribute to positive feedback that supports the presence of permafrost. This preliminary study reports on the thermal state characteristics of tropical mountain permafrost in Peru. This work also evaluates the potential combined impact of the El Niño-Southern Oscillation (ENSO) in the mountain permafrost of the Coropuna and Chachani volcanic complexes, both located at the western edge of the southern Peruvian Altiplano. Temperature monitoring boreholes were established at 5,217 m at Coropuna and 5,331 m at Chachani, and electrical resistivity was surveyed in both sites. This 7-year discontinuous record of permafrost temperature data encompasses historically extreme El Niño/La Niña events. Our results show that the current lower-altitude permafrost boundary (~5,100 m a.s.l.) is critically influenced by the balance of wet and dry seasons: permafrost tends to deplete during drought years. Typical permafrost thickness was 10-20 m and contained ice-rich pore spaces. The presence of permafrost and its thermal resistance depends on ice content and on higher albedo, usually due to: (a) hydrothermal alteration, which transforms the volcanic rocks into surfaces with ideal albedo for permafrost resilience; and (b) sublimation of the snow cover, forming ice-pinnacles named penitentes.

“…Tropical high mountain permafrost has been reported in Hawaii on Mauna Kea (Woodcock 1974;Schorghofer, Leopold, and Yoshikawa 2017), Iztaccíhuatl (Andrés et al 2011) and Pico de Orizaba (Vizoto 2018) in Mexico, Kilimanjaro Tanzania (Yoshikawa 2013), the southern Peruvian Andes (Yoshikawa et al 2020), and Chile (Nagy et al 2018). In order to understand the thermal state of tropical desert mountain permafrost and active layer cycles, we consider four conditions, each substantially different from polar regions: (1) minimal seasonal temperature variation, resulting in low numbers of thawing and freezing degree days (FDD) and shallow active layer depth and (2) diurnal ground surface temperature amplitude exceeding the annual amplitude.…”

Section: Introductionmentioning

confidence: 99%

Freeze–thaw cycles and snow impact at arid permafrost region in Chajnantor Volcano, Atacama, northern Chile

Mena

Arctic, Antarctic, and Alpine Research

Schörghofer

et al. 2021

Self Cite

Permafrost occurs in the high Atacama Desert, and its thermal state was characterized at a study site 5,075 m a.s.l., at the lower regional altitude boundary for permafrost. The permafrost body is about 5 m thick and located in the hydrothermal alteration zone. The freeze-thaw layer and upper part of the permafrost layer temperatures were measured at 0 to 39 cm depth at 1-cm resolution throughout the year. The upper 3 cm of the ground experienced more than 100 freeze-thaw cycles in 2019. The maximum thaw depth was 14 cm. No significant thermal offset is observed between the annual mean of the surface temperature and the top permafrost boundary. The 14-m borehole reveals that the geothermal gradient was quite high at 200°C/km. In 2019 the seventy days of snow cover impacted the surface energy budget. Winter and summer snow conditions contribute to cooling the surface temperature regime in different ways.