http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
role of continental moisture recycling in climate model precipitation and climate change impacts research
This research examines the effect of continental moisture recycling on climate model precipitation to determine the extent to which land surface hydrology approximations contribute to imprecise precipitation simulations. The inability of climate models to accurately simulate regional precipitation patterns may be attributed to inaccuracies in atmospheric moisture transport processes, and moisture exchanges between the land surface and the atmosphere. It is difficult, however, to quantify the relative role each of these plays in the problem. Estimation of model moisture recycling is evaluated as a potential method of differentiating between the sources of model error. Moisture recycling is estimated from two separate climate model runs and using results from a reanalysis climate modeling project. Model precipitation is partitioned into contributions from moisture transported into the region and moisture recycled locally through evaporation. Moisture recycling, net inward moisture flux, moisture divergence, precipitation and evaporation quantities are compared as monthly means to observations of those quantities for each of the regions, and to estimates of the quantities published by Brubaker et at. (1993). Differences in monthly mean precipitation are clarified by comparing the annual cycles. Results show that recycled moisture makes a minor contribution to total cycles. Results show that recycled moisture makes a minor contribution to total precipitation compared to adverted moisture. The models generally reproduce observed evaporation patterns, but overestimate inward moisture flux and underestimate moisture divergence. This suggests that moisture recycling processes make a minor contribution to precipitation error as well. Model precipitation is also tested for its sensitivity to forced changes in model recycling in off-line experiments on monthly and daily time scales. Results suggest that adjusting recycling is likely to create only minor improvements in model precipitation simulation. The recycling model appears to be appropriately sensitive to variations in scale. Further, because results from the different climate models showed large similarities, it appears that the recycling model is less sensitive to differences in climate models than might have been expected.
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Includes bibliographical references (leaves 68-72).