1) (15 pts) Melting of the Alaska Permafrost https://www.pmel noaa.gov/arctic-zo

Question

1) (15 pts) Melting of the Alaska Permafrost https://www.pmel noaa.gov/arctic-zone/detect/land Permafrost is permanently frozen ground. For example, in Fairbanks, Alaska, the soil at a depth of 1m below the surface has been frozen for the last several thousand years and maybe even longer. Only the upper layer of soil (called the active layer) thaws every summer and then completely refreezes during the winter. Typical thickness of permafrost around Fairbanks is about 50 meters with an average temperature of -5 C in the permafrost. When permafrost degrades (melts), there are impacts on drainage, ground water, river runoffs, ecological systems (such as plants and ponds), release of carbon that has been sequestered in the frozen soil, and infrastructure (such as houses, roads, airports, pipelines, and other facilities based on permafrost). With global warming, the degradation (melting) of the permafrost has become a growing concern. ost.shtml Question: Based on the average daily high and low temperatures given below for the summer months of May, June, and July, how deep would you expect the melting of the permafrost layer to be? Average themal diffusivity of frozen ground (permafrost) a 0.3 x107 m'/sec Average Daily Air Temperature in Fairbanks, AK (www.usclimatedata.co May, June, July: Avg. High- 70 F, Avg. Low- 50 F Average Daily Temp. -60 IF

Explanation / Answer

Permafrost is the permanantly frozen soil and occurs mostly in high latitudes. In northern hemisphere it comprises 24% of the land and massive amounts of carbon. This stored carbon is released as carbondioxide and methane due to climate change and leads to severe global damage. In every summer it thaws and refreezes in every winter. In may, june, july when at avetage high temperature i.e at 70F whis is equal to 21degree Celsius the parmafrost melts several meters of depth and the diffusivity of the frozen ground will increase i.e square meter per sec will increase. The high low temperature in may, june and july is about 50 F which is equal to 10 degrees, it melts less deeper meters than at 70F.

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