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SUMMARY:ENAC Seminar Series by Prof. Isabella Velicogna
DTSTART:20181221T083000
DTEND:20181221T093000
DTSTAMP:20260501T185238Z
UID:78ca44d5a3e8ee36bc6f89b0cb2a550f122e51e6ec1e191ddd5f8c57
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Isabella Velicogna\n8:30 – 9:30 – Prof. Isabella Vel
 icogna\nFull Professor\, Dept. of Earth System Science\, University of Cal
 ifornia Irvine\, USA\n \nTime-variable gravity studies of ice sheets and 
 glacier mass balance and partitioning of the water cycle in high mountain 
 environment \n \nTime series of time-variable monthly gravity data from t
 he Gravity Recovery and Climate Experiment (GRACE) mission (2002-2017) hav
 e revolutionized the way we look at water/ice mass changes at the surface 
 of the Earth despite a spatial resolution limited to about 350 km. Using G
 RACE data\, we established the first mass balance of the Antarctic ice she
 et in 2006\, illustrating that the ice sheet was losing mass\, the mass lo
 ss was concentrated in a few sectors and a few years later\, we added evid
 ence that the mass loss was increasing with time. The GRACE data were also
  compared with surface mass balance model output products to provide the f
 irst evaluation of these products\, hence establishing GRACE data are a to
 ol for validation climate models.\n\nIn Greenland\, we obtained the first 
 comprehensive\, monthly estimates of mass balance that showed that the mas
 s loss had spread around the entire ice sheet and was also accelerating wi
 th time. Comparison with surface mass balance products was used to detect 
 the weaknesses of these models or whether other processes were important\,
  e.g. ice dynamics. For the mountain glaciers and ice caps of the World (G
 IC)\, GRACE provided the first estimates based on a comprehensive survey w
 ith the same instrument\, instead of extrapolating numbers from a few in s
 itu observations. The results showed a large mass loss\, however\, negligi
 ble contribution from the Antarctic peripheral glaciers\, an acceleration 
 of the mass loss over the last 16 years\, a dominance of the mass loss fro
 m the Arctic and a mass loss from High Mountain Asia. In High Mountain Asi
 a\, we started a broad multidisciplinary project to investigate the role o
 f glaciers and climate change in controlling freshwater supply in the regi
 on.\n\nThe GRACE data have been instrumental to constrain the terrestrial 
 water storage and close the water budget of the upper and lower basins of 
 the main river in the region. This allows for the first time to understand
  the partitioning between glacier/snow runoff and precipitation in river d
 ischarge. The GRACE data are key to evaluate the climate models that will 
 be used to project the evolution of the freshwater supply in years to deca
 des to come. This work has been supported by research grants from NASA.
LOCATION:CE 1 100 https://plan.epfl.ch/?room=CE1100
STATUS:CONFIRMED
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