Assessment of surface exchange coefficients in the Noah‐MP land surface model for different land‐cover types in China. (10th January 2021)

• Record Type: Journal Article
• Authors: Zhang, Xia; Chen, Liang; Ma, Zhuguo; Gao, Yanhong
• Is Part Of: International journal of climatology. Volume 41:Number 4(2021)
• Page Start: 2638
• Page End: 2659
• Publication Date: 2021-01-10
• Subjects: land–atmosphere interaction -- surface coupling strength -- surface exchange coefficient -- surface fluxes; Climatology -- Periodicals; Climat -- Périodiques; Climatologie -- Périodiques; 551.605
• DOI: 10.1002/joc.6981
• Languages: English
• ISSNs: 0899-8418

Abstract

Abstract: The parameterization of surface exchange coefficients ( C h ) representing land–atmosphere coupling strength plays a key role in land surface modelling. Previous studies have found that land–atmosphere coupling in land surface models (LSMs) is largely overestimated, which affects the predictability of weather and climate evolution. To improve the representation of land–atmosphere interactions in LSMs, this study investigated the impact of dynamic canopy‐height‐dependent coupling strength in an offline Noah LSM with multi‐parameterization options (Noah‐MP) when applied to China. Comparison with the default Noah‐MP LSM showed that the dynamic scheme significantly improved the C h calculations and realistically reduced the biases of simulated surface energy and water components against observations. It is noteworthy that the improvements brought about by the dynamic scheme differed across land‐cover types. The scheme was superior in reproducing the observed C h as well as surface energy and water variables for short vegetation (grass, crops, and shrubs), whereas the improvement for tall canopy vegetation (forest) was not significant although the estimations were reasonable. The improved version benefits from the treatment of the roughness length for heat. Further, the scheme can better reproduce the observed surface thermal components, while the improvement in hydraulic variables (such as soil moisture) remains limited. Overall, the dynamic coupling scheme markedly affects the simulation of land–atmosphere interactions, and altering the dynamics of surface coupling has the potential to improve the representation of land–atmosphere interactions and, thus, the further development of LSM. Abstract : Impacts of C zil in an offline Noah LSM with multi‐parameterization options (Noah‐MP) on land–atmosphere coupling strength as well as on surface energy and water components in China were evaluated. The dynamic canopy‐height‐dependent C zil scheme was found superior in reproducing observations. The dynamic scheme performed better for short vegetation (such as grass) because of the treatment of the roughness length for heat.