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2.25.8. Inundated Fraction Prediction¶
A simplified dynamic representation of spatial inundation based on recent work by Prigent et al. (2007) is used. Prigent et al. (2007) described a multi-satellite approach to estimate the global monthly inundated fraction (\({F}_{i}\)) over an equal area grid (0.25 \(\circ\) \(\times\)0.25\(\circ\) at the equator) from 1993 - 2000. They suggested that the IGBP estimate for inundation could be used as a measure of sensitivity of their detection approach at low inundation. We therefore used the sum of their satellite-derived \({F}_{i}\) and the constant IGBP estimate when it was less than 10% to perform a simple inversion for the inundated fraction for methane production (\({f}_{s}\)). The method optimized two parameters (\({fws}_{slope}\) and \({fws}_{intercept}\)) for each grid cell in a simple model based on simulated total water storage (\({TWS}\)):
(2.25.20)¶\[f_{s} =fws_{slope} TWS + fws_{intercept} .\]
These parameters were evaluated at the 0.5° resolution, and aggregated for coarser simulations. Ongoing work in the hydrology submodel of CLM may alleviate the need for this crude simplification of inundated fraction in future model versions.