Short review of permafrost research in Hawaii

1. Norbert Schörghofer
Planetary Science Institute
in collaboration with:
Matthias Leopold (University of Western Australia)
Kenji Yoshikawa (University of Alaska, Fairbanks)
and others
Field studies 1968-1973 and 2012-2018
Permafrost in Hawaii

2. Hawaii Island 20°N
shield volcanoes
Mauna Kea &
Mauna Loa
~4,200m a.s.l.
• Tropical latitude
• Small seasonal &
diurnal
temperature
amplitude
• Seasonal snow
• Past glaciation
Image credit: Wikimedia
Commons

3. Mauna Kea, Hawaii
Summit (4,207m)
Mauna Loa
Puu Wekiu Crater
Permafrost
Mean Annual Air Temperature (MAAT) +4°C
permafrost beneath north-facing slope (Woodcock, 1974)
tropics 20°N, summits: 4200m a.s.l., seasonal snow,
annual mean temperatures well above freezing

4. Permafrost on Mauna Kea
Woodcock (1974) documented permafrost

5. Electrical Resistivity Tomography
(ERT) Results in Puuwekiu
ice = electrical insulator
Ice still present in 2015/2016, but has retreated
significantly (hence relic, not active permafrost)

6. Retreat of Permafrost in Puuwekiu

7. Climate Warming in Hawaii
1°C warming at MLO since Woodcock’s observations
(1969-1973), possibly more on Mauna Kea summit
Giambelluca et al.
(2008)
Malamud (2011)
McKenzie et al. (2019)
MLO = Mauna Loa
Observatory (3397m)

8. Electrical Resistivity Tomography (ERT)
Ground Penetrating Radar (GPR)

10. Multi-Year Ground Temperatures

11. Permafrost is NOT
responsible for the
impermeability of
some of the cinder
cones
Lake Waiau (3,970m)
Puupohaku Pond (4,008m)
Temperatures are well
above freezing beneath
both ponds.

12. Topography and Annual Mean Insolation
Permafrost only found in interior slopes of cinder cones
Model code: https://github.com/nschorgh/Planetary-Code-Collection/EarthAnalogs/
Permafrost
Permafrost

13. 8-day air temperature time series;
CAPs (cold air pools)
data from weather station, Sep 2008
black dots = no detectable wind (<0.4 m/s)
nocturnal cold air pools (CAP)
coldest temperatures in Hawaii (-20°C)

14. Influence of Snow Cover on
Ground Temperature:
• Temperatures at 1m depth
• Snow cover from MODIS
• Fresh snow has high albedo

15. Conclusions
• Two ice-rich permafrost bodies (still) exist on Mauna
Kea, above 4,000m asl.
• Permafrost is shrinking and out of equilibrium with the
current climate (relic). ➾ Last permafrost in Hawaii
• Nocturnal cold air pools in craters are responsible for the
lowest temperature ever reported from Hawaii (-20°C).
• Factors for permafrost stability:
– high-altitude; terrain shadowing; north-facing slopes
– cold air accumulates in craters and inter-boulder
spaces during calm nights
– snow cover (albedo feedback)

16. Further Reading
1. Woodcock, A.H. (1974). Permafrost and climatology of a Hawaii
volcano crater. Arctic and Alpine Research 6, 49-62.
2. Leopold, M., A. Morelli, N. Schorghofer (2016). Subsurface
architecture of two tropical alpine desert cinder cones that hold
water. Journal of Geophysical Research 121, 1148-1160.
3. Schorghofer, N., M. Leopold, K. Yoshikawa (2017). State of high-
altitude permafrost on tropical Maunakea volcano, Hawaii.
Permafrost and Periglacial Processes 28, 685-697.
4. Schorghofer, N., S. Businger, M. Leopold (2018). The coldest
places in Hawaii: The ice-preserving microclimates of high altitude
craters and caves. Bulletin of the American Meteorological Society
99(11), 2313-2324.
5. Schorghofer, N. (2018). “Permafrost Survey on the Maunakea
Summit Plateau.” Final Report prepared for the Office of Maunakea
Management and the Hawaii Department of Land and Natural
Resources, 28pp.