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Land surface model performance using cosmic-ray and point-scale soil moisture measurements for calibration

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)2843-2861
Number of pages19
JournalHydrology and Earth System Sciences
Volume21
Issue number6
DOIs
DateAccepted/In press - 10 May 2017
DatePublished (current) - 9 Jun 2017

Abstract

At very high resolution scale (i.e. grid cells of 1 km2), land surface model parameters can be calibrated with eddy-covariance flux data and point-scale soil moisture data. However, measurement scales of eddy-covariance and point-scale data differ substantially. In our study, we investigated the impact of reducing the scale mismatch between surface energy flux and soil moisture observations by replacing point-scale soil moisture data with observations derived from Cosmic-Ray Neutron Sensors (CRNSs) made at larger spatial scales. Five soil and evapotranspiration parameters of the Joint UK Land Environment Simulator (JULES) were calibrated against point-scale and Cosmic-Ray Neutron Sensor soil moisture data separately. We calibrated the model for 12 sites in the USA representing a range of climatic, soil, and vegetation conditions. The improvement in latent heat flux estimation for the two calibration solutions was assessed by comparison to eddy-covariance flux data and to JULES simulations with default parameter values. Calibrations against the two soil moisture products alone did show an advantage for the cosmic-ray technique. However, further analyses of two-objective calibrations with soil moisture and latent heat flux showed no substantial differences between both calibration strategies. This was mainly caused by the limited effect of calibrating soil parameters on soil moisture dynamics and surface energy fluxes. Other factors that played a role were limited spatial variability in surface fluxes implied by soil moisture spatio-temporal stability, and data quality issues.

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    Rights statement: This is the final published version of the article (version of record). It first appeared online via the European Geosciences Union at https://doi.org/10.5194/hess-21-2843-2017 . Please refer to any applicable terms of use of the publisher.

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