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- Title
Influence of cracking clays on satellite observed and model simulated soil moisture.
- Authors
Liu, Y. Y.; McCabe, M. F.; Evans, J. P.; van Dijk, A. I. J. M.; de Jeu, R. A. M.; Su, H.
- Abstract
Vertisols are clay soils that are common in the monsoonal and dry warm regions of the world. A defining feature of these soils is the development of shrinking cracks during dry periods, the effects of which are not described in land surface models nor considered in the surface soil moisture estimation from passive microwave satellite observations. To investigate the influence of this process we compared the soil moisture (θ in m³ m-3) from AMSR-E observations and the Community Land Model (CLM) simulations over vertisols across mainland Australia. Both products agree reasonably well during wet seasons. However, during dry periods, AMSR-E θ falls below values for surrounding non-clays, while CLM simulations are higher. The impacts of soil property used in the AMSR-E algorithm, vegetation density and rainfall patterns were investigated, but do not explain the observed θ patterns. Analysis of the retrieval model suggests that the most likely reason for the low AMSR-E θ is the increase in soil porosity and surface roughness through cracking. CLM does not consider the behavior of crack15 ing clay, including the further loss of moisture from soil and extremely high infiltration rates that would occur when cracks develop. Analyses show that the corresponding water fluxes can be different when cracks occur and therefore modeled evaporation, surface temperature, surface runoff and groundwater recharge should be interpreted with caution. Introducing temporally dynamic roughness and soil porosity into retrieval algorithms and adding a "cracking clay" module into models, respectively, may improve the representation of vertisol hydrology.
- Subjects
AUSTRALIA; VERTISOLS; CLAY soils; SOIL moisture; VEGETATION &; climate; RAINFALL
- Publication
Hydrology & Earth System Sciences Discussions, 2010, Vol 7, Issue 1, p907
- ISSN
1812-2108
- Publication type
Article
- DOI
10.5194/hessd-7-907-2010