HR: 1340h
AN: H13D-0459    [Abstracts]
TI: Observational Analyses of Hydrologic Scaling: the Role of Non-Local Interactions as Inferred From Soil Moisture and Precpitation Data
AU: * Saleem Arrigo, J A
EM: jarrigo@worcester.edu
AF: Worcester State College, Department of Physical and Earth Sciences 486 Chandler Street, Worcester, MA 01602 United States
AU: Salvucci, G D
EM: gdsalvuc@bu.edu
AF: Boston University, Departments of Geography and Earth Sciences, 675 Commonwealth Avenue, Boston, MA 02215 United States
AB: Using sparsely and infrequently measured soil moisture data, and a technique using conditional averaging of precipitation to estimate outflow, we investigate the effect of non-local interactions and moisture anomalies present in scaling local moisture-outflow relationships from points to larger areas. To investigate the presence of non-local interactions, locations are modeled as a set of independent columns and the moisture-outflow relationships are aggregated in such a way as to account for heterogeneity; this estimate is compared statistically to the large-scale response estimated from aggregate data. Significant differences would suggest the system is not well represented by the independence assumption, i.e. local outflow is dependent on local moisture and also is independently influenced by large-scale moisture. We applied these methods to data from three systems - a hillslope, an intermediate-sized watershed, and the state of Illinois, and found that heterogeneity coupled with non-linearity of the governing processes significantly affected scaling in all three. After accounting for these, significant differences remained between the aggregated point-scale estimates and the large-scale response. This difference is attributable to non-local influences on the local systems; in each area studied, the effect is to decrease (increase) local outflow during large-scale dry (wet) anomalies; evidence in Illinois points to a possible atmospheric pathway through an effect on wind speed. The apparent effect of the interactions is to prolong small spatial anomalies of moisture, and at the same time to decrease the temporal variability of the large-scale system. The results here suggest possible common dynamic and scaling effects in water balance at various scales, as well as large-scale dependencies of local climate on larger-scale soil moisture anomalies.
DE: 1899 General or miscellaneous
DE: 1833 Hydroclimatology
DE: 1866 Soil moisture
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting