Exploring new topography-based subgrid spatial structures for improving land surface modeling
Topography plays an important role in land surface processes through its influence on atmospheric forcing, soil and vegetation properties, and river network topology and drainage area. Land surface models with a spatial structure that captures spatial heterogeneity, which is directly affected by top...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-02-01
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| Series: | Geoscientific Model Development |
| Online Access: | http://www.geosci-model-dev.net/10/873/2017/gmd-10-873-2017.pdf |
| Summary: | Topography plays an important role in land surface processes through its
influence on atmospheric forcing, soil and vegetation properties, and river
network topology and drainage area. Land surface models with a spatial
structure that captures spatial heterogeneity, which is directly affected
by topography, may improve the representation of land surface processes. Previous studies found
that land surface modeling, using subbasins instead of structured grids as
computational units, improves the scalability of simulated runoff and streamflow
processes. In this study, new land surface spatial structures are explored
by further dividing subbasins into subgrid structures based on topographic
properties, including surface elevation, slope and aspect. Two methods (local
and global) of watershed discretization are applied to derive two types of
subgrid structures (geo-located and non-geo-located) over the
topographically diverse Columbia River basin in the northwestern United
States. In the global method, a fixed elevation classification scheme is
used to discretize subbasins. The local method utilizes concepts of
hypsometric analysis to discretize each subbasin, using different elevation
ranges that also naturally account for slope variations. The relative
merits of the two methods and subgrid structures are investigated for their
ability to capture topographic heterogeneity and the implications of this on
representations of atmospheric forcing and land cover spatial patterns.
Results showed that the local method reduces the standard deviation (SD) of
subgrid surface elevation in the study domain by 17 to 19 % compared
to the global method, highlighting the relative advantages of the local
method for capturing subgrid topographic variations. The comparison between the
two types of subgrid structures showed that the non-geo-located subgrid
structures are more consistent across different area threshold values than
the geo-located subgrid structures. Overall the local method and
non-geo-located subgrid structures effectively and robustly capture
topographic, climatic and vegetation variability, which is important for land surface
modeling. |
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| ISSN: | 1991-959X 1991-9603 |