Gravity Recovery and Climate Experiment (GRACE) Derived Water Equivalent Changes of the Arctic Watersheds

The Arctic permafrost regions compose the largest component of the cryosphere. Observations from the Gravity Recovery and Climate Experiment (GRACE) mission offer to provide a greater understanding of changes in water mass within these regions. We investigate GRACE monthly time series, snow water equivalent from the Special Scanning Microwave Imager (SSM/I) and discharge from the Lena, Yenisei, Ob’, Mackenzie and Yukon River watersheds. GRACE water equivalent mass change respond to mass loading by snow accumulation in winter and mass unloading by runoff in spring. Comparison of secular trends from GRACE to runoff indicates groundwater storage is increasing in the Lena and Yenisei watersheds, decreasing in the Mackenzie and Yukon watersheds, and is steady in the Ob’ watershed. We also note that groundwater storage is increasing in the Alaska Arctic coastal plain. We hypothesize that the groundwater storage changes are linked to the development of closed talik (unfrozen material acting as aquifers) in the continuous permafrost zone and decrease of permafrost lateral extent and new open talik formation in the discontinuous permafrost zone of the watersheds. The increase in talik may be linked to increase in surface and sub-surface water associated with thaw bogs, ponds, lakes and river-beds in the continuous permafrost zone and decrease in surface and sub-surface water associated with draining of thaw bogs, ponds and lakes in the discontinuous permafrost zone.