A New Topography-based Subgrid Architecture for Land ......Global and Local Methods have been...
Transcript of A New Topography-based Subgrid Architecture for Land ......Global and Local Methods have been...
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A New Topography-based Subgrid Architecture for Land Surface Modeling Teklu K. Tesfa and L. Ruby Leung
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Outline • Motivation • Methods and Subgrid Structures Explored • Results • Summary and Conclusions
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Motivation: Topography Matters Topography exerts major control on land surface processes.
Spatial structures that capture topographic spatial
heterogeneity may improve representation of land surface processes.
Subbasin-based land surface modeling demonstrated better scalability (Tesfa et al., 2014 a&b).
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Methods and Subgrid Structures Explored Two Methods:
Global Method: Elevation classification of the whole domain following Leung and Ghan [1995 and 1998] is combined with slope and aspect, and area threshold to delineate each subbasin into subgrid land units (LUs).
Local Method: Elevation classification based on elevation-area profile of each subbasin is combined with aspect and area threshold to delineate each subbasin into subgrid land units.
Two Types of Subgrid Structures: Geo-located Subgrid structure: Subbasins are delineated into
spatially contiguous land units. Non geo-located Subgrid structure: Subbasins are delineated into
spatially non-contiguous land units represented as fractional area.
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Results Local vs. Global Method in generating Non geo-located LUs for the Columbia River Basin
Local method is generally less sensitive to threshold values than the global method
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Results Local vs. Global Methods in capturing topographic patterns
Local method captures the topographic pattern better than the global method.
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Results Non geo-located vs. geo-located LUs using Local Method for the Columbia River Basin
The non geo-located LUs are less sensitive to threshold values than the geo-located LUs.
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Results A globally consistent high resolution DEM
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Results
Frequency distribution of Subbasin size (ha)
Freq
uenc
y
No of Subbasins
Mean Size (ha)
South America 59,650 ~260 km2
Australia 24,621 ~290 km2
New Subbasin Dataset for South America and Australia
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Summary and Conclusions Global and Local Methods have been developed to derive a new topography-based land surface spatial structure for CLM.
Both methods have been tested over the Columbia River Basin in deriving both geo-located and non geo-located LUs.
The Local Method captures the topographic pattern better than the Global Method and is more consistent across threshold values in the number of LUs per subbasin.
A new subbasin dataset for Australia and South America has been developed from the globally consistent high resolution DEM developed in this effort. The Local Method for Non geo-located LUs is being applied globally to generate a global topography-based land surface structure for CLM.