2. Apply new techniques to study the partitioning of the terrestrial water cycle in the Arctic and resolve precipitation biases


The Arctic hydrological systemhas experienced dramatic changes over the past century and the rate of change has increased during recent decades. Changes in the Arctic terrestrial water cycle, especially the storage component, may significantly alter the soil moisture and thermal regimes, and therefore affect plant communities and exchanges between land-atmosphere water, energy and trace gas withpotentially large climate feedbacks. Changes in the water cycle, however, are difficult to quantify because they require precise knowledge of all components of the water cycle.

With the GRACE mission, we are able for the first time to measure changes in the total water column globally on land. We have demonstrated the use of this approach to monitor major changes in ground water storage. My analysis of GRACE data in India used in Rodell et al. (2009) produced a landmark study in ground water hydrology that is heavily cited.

In the Arctic, we are applying our methodology to study the partitioning of the water cycle. In Eurasia, we have shown that it is possible to quantitatively close the water budget for the first time, calculate biases in net precipitation and quantify large increases in ground water storage. We are working with scientific partners to determine how these changes in terrestrial water storage relate to changes in soil permafrost, active layer depth and Arctic ecosystems.


2009-2013 NASA ROSES-07 Hydrology Program. ‘Terrestrial water storage changes and boreal drought under a warming climate: Investigation with multi-sensor satellite observations, in-situ data, and hydro-ecological process modeling’.  P.I.

2008-2012 NASA Hydrology Program, ‘The Eurasian fresh water cycle from GRACE and in-situ hydrologic networks: distinguishing water behavior in permafrost and non-permafrost regions’. P.I.

2007-2012 NASA Hydrology Program, ‘Mass changes in Earth’s global water reservoirs’. Co P.I.


2011 -Velicogna I., Tong J., Zhang T., Kimball  J. ‘Increasing groundwater storage in discontinuous permafrost areas in the Lena river basin, Eurasia, detected from GRACE’. In revision, Geophys. Res. Lett.

2011 - Tong J, Velicogna I. , Kimball  J.‘Impact of terrestrial waters storage changes on vegetation productivity in Eurasia’.In revision, Environ Res. Lett.

2010 - Tong J, Velicogna  I. ‘A  Comparison of AMSR-E/Aqua  Snow Products with  in-situ Observations and MODIS Snow Cover Products in the Mackenzie River Basin, Canada’. Remote Sens., 2(10), 2313-2322; doi:10.3390/rs2102313.

2009 - Rodell M, Velicogna  I.,  Famiglietti  J,  ‘Satellite-based  estimates of groundwater depletion in India’.  Nature, VOL. 460, 999-U80, doi: 10.1038/nature08238.