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Relative Influence of Initial Surface and Atmospheric Conditions on Seasonal Water and Energy BalancesWe constructed and analyzed wet and dry soil moisture composites for the mid-latitude GCIP region of the central US using long climate model simulations made with the NCAR CCM3 and reanalysis products from NCEP. Using the diagnostic composites as a guide, we have completed a series of predictability experiments in which we imposed soil water initial conditions in CCM3 for the GCIP region for June 1 from anomalously wet and dry years, with atmospheric initial conditions taken from June 1 of a year with 'near-normal' soil water, and initial soil water from the near-normal year and atmospheric initial conditions from the wet and dry years. Preliminary results indicate that the initial state of the atmosphere is more important than the initial state of soil water determining the subsequent late spring and summer evolution of sod water over the GCIP region. Surprisingly, neither the composites or the predictability experiments yielded a strong influence of soil moisture on the atmosphere. To explore this further, we have made runs with extreme dry soil moisture initial anomalies imposed over the GCIP region (the soil close to being completely dry). These runs did yield a very strong effect on the atmosphere that persisted for at least three months. We conclude that the magnitude of the initial soil moisture anomaly is crucial, at least in CCM3, and are currently investigating whether a threshold exists, below which little impact is seen. In a complementary study, we compared the impact of the initial condition of snow cover versus the initial atmospheric state over the western US (corresponding to the westward extension of the GAPP program follow-on to GCIP). In this case, the initial prescription of snow cover is far more important than the initial atmospheric state in determining the subsequent evolution of snow cover. We are currently working to understand the very different soil water and snow cover results.
Document ID
20010021339
Acquisition Source
Marshall Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Oglesby, Robert J.
(Purdue Univ. West Lafayette, IN United States)
Marshall, Susan
(NASA Marshall Space Flight Center Huntsville, AL United States)
Roads, John O.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Robertson, Franklin R.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Goodman, H. Michael
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Environment Pollution
Meeting Information
Meeting: Global Change Studies and Climate Variations
Location: Albuquerque, NM
Country: United States
Start Date: January 15, 2001
End Date: January 19, 2001
Sponsors: American Meteorological Society
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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