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Project Progress

We have visited and documented two high-altitude ice caves on Mauna Loa. The caves are at ~3,500m elevation in unvegetated lava flows about 700 years old, which places a maximum age on the ice. The lava tubes of both caves are several hundred meters long and slope downhill; hence cold air sinks into the cave. The ice is in the form of frozen ponds; water drips from the ceiling and freezes in layers. The ponds are several tens of meters long, and we estimate them to be a few meters deep. Large cm-sized bubbles are included in the ice, as expected for very low freezing rates. The ice appears to be layered, and thus the ponds may contain a record of the past. We have drawn up cave maps and started temperature and humidity time series and ice level monitoring.

Mauna Kea is located in the tropics (19°N), but the climate on the summit is classified as an alpine desert. Permafrost can be found in at least two of the cinder cones near the summit. The low annual mean temperatures necessary for the ice to last all year round are caused by shadowing by the crater rim and by nocturnal cold air lakes. We have placed several data loggers in the two cinder cones to begin a temperature time series and equipped an infrared camera with a time-lapse circuit for infrared imaging of the crater interiors. These measurements will be compared to numerical models of the thermal environment to better understand the microclimates in the craters.