Effects of subgrid heterogeneities in soil infiltration capacity and precipitation on regional climate: a sensitivity study |
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| Authors: | X-M Zeng M Zhao B-K Su J-P Tang Y-Q Zheng Y-J Zhang J Chen |
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| Institution: | (1) Key Laboratory for Mesoscale Severe Weather of Ministry of Education, Nanjing University, Nanjing, China, CN;(2) Department of Earth Science, Nanjing University, Nanjing, China, CN;(3) Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China, CN |
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| Abstract: | Summary ?One of the most pronounced features of the land surface is its heterogeneity. In order to further understand land-atmosphere
interactions and improve climate modeling it is very important to investigate effects of subgrid scale heterogeneities, especially
hydrological-process heterogeneities. In this paper, after the construction and sensitivity tests of a hydrological model
(VXM), which accounts for precipitation heterogeneity (PH) and infiltration heterogeneity (IH), we incorporated VXM into the
NCAR (National Center for Atmospheric Research) regional climate model RegCM2 and thus obtained the augmented regional climate
model (hereafter, ARCM). By using 3-month (May–July) observational data of 1991 Meiyu season, we conducted numerical experiments
with ARCM, analyzed the sensitivities, and found that: (1) The regional climate and surface hydrology are very sensitive to
IH as well as PH, i.e., the simulations for the surface fluxes, soil temperature, soil moisture, precipitation and surface
runoff can be greatly affected by those heterogeneities. (2) ARCM can effectively improve the simulation of hydrological processes,
i.e., it can greatly enhance the surface runoff ratio (i.e., the ratio of surface runoff to precipitation), which is consistent
with observations over humid areas in China. (3) It seems that the IH influence on the surface climate is larger than the
PH influence. (4) The modeled climate is sensitive to the VXM parameters. For example, it is significantly modified after
the surface impermeable fraction has been accounted for, suggesting some features of aridification.
Received June 18, 2001; revised February 14, 2002; accepted March 3, 2002 |
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