Validation of the NOAH‐OSU land surface model using surface flux measurements in Oklahoma

Abstract

[1] Oklahoma Atmospheric Surface-Layer Instrumentation System (OASIS) measurements of net radiation (R n ), latent heat flux (LH), sensible heat flux (SH), and ground heat flux (GH) were used to validate the NOAH-Oregon State University Land Surface Model (NOAH-OSU LSM). A 1-year study period was used. R n , LH, SH and GH data from seven sites were screened based on an energy balance closure criterion (daily/ hourly sum of the flux components within the range of À10 to +10 W m À2). The vegetation fraction used in the model was computed using both the Gutman-Ignatov (G-I) and the Carlson-Ripley (C-R) schemes. The simulated net radiation and ground heat fluxes seem less sensitive to the choice of schemes for computing green vegetation fraction, while latent and sensible heat flux show more sensitivity particularly for soil dry-down period. Therefore, the G-I approach was used for the validation study, as it is widely used and linear in its form. The daily aggregated model outputs showed that the predicted R n had a positive bias of 0.

Effective soil moisture estimate and its uncertainty using multimodel simulation based on Bayesian Model Averaging

“…Additional model processes and assumptions are provided in Table 1 and by Ek et al [2003]. The model has been tested and showed good performance in humid and temperate hydroclimate regions [Koren et al, 1999;Sridhar et al, 2002;Ek et al, 2003]. However, it still has limitations in applying to arid hydroclimate regions.…”

A non-linear and stochastic response surface method for Bayesian estimation of uncertainty in soil moisture simulation from a land surface model

“…A four-layer soil configuration (comprising a total depth of 2 m) is adopted in the NOAH-LSM for captur- Gutman and Ignatov, 1998). The growth sequence applies for soybeans that were planted during 1998. ing daily, weekly and seasonal evolution of soil moisture and mitigating possible truncation error in discretization (Sridhar et al, 2002). The lower 1 m acts as gravity drainage at the bottom, and the upper 1meter of soil serves as root zone depth.…”

“…Since this study concerns the assessment of a parameter sampling technique, we have considered soil moisture observations and simulations only at the 5 cm depth for the sake of simplicity. For more details on the physical description of the model, one may refer to Sridhar et al (2002).…”

“…Furthermore, the requirement of multiple ordinary non-linear differential equations as the necessary condition for chaotic behavior in soil moisture dynamics has also been noted by Rodriguez-Iturbe Table 1) to intuitively expect a chaotic behavior relationship (between soil moisture prediction the hydraulic parameters). These notable sub-models are as follows: 1) The prognostic equation for volumetric soil water content (Richards Equation) (Sridhar et al, 2002);…”

“…2) The diffusion equation for soil temperature (Sridhar et al, 2002); 3) The Penman-based energy balance approach for potential evaporation (Sridhar et al, 2002); and, 4) The Mahrt and Ek (1984) formulation of surface skin temperature. There are three major steps involved in the algorithm formulation of this interpolator.…”