Abstract. Rapid urbanisation and economic development in China have led to a dramatic increase in nitrogen oxide (NO2) emissions, causing serious atmospheric nitrogen pollution and relatively high levels of nitrogen deposition.
However, despite the importance of nitrogen deposition, dry deposition processes in forested areas are still insufficiently represented in current global and regional atmospheric chemistry models, which constrains our understanding and prediction of spatial and temporal patterns of nitrogen transport in forest ecosystems in southern China.
The offline 1-D community Noah land surface model with multi-parameterisation options (Noah-MP) is coupled with the WRF-Chem dry deposition module (WDDM) and is applied to further understand and identify the key processes that affect forest canopy dry deposition.
The canopy stomatal resistance mechanism and the nitrogen-limiting scheme for photosynthesis in Noah-MP-WDDM are modified to improve the simulation of reactive nitrogen oxide dry deposition velocity.
This study finds that the combined improved stomatal resistance mechanism and nitrogen-limiting scheme for photosynthesis (BN-23) agree better with the observed NO2 dry deposition velocity, with the mean bias being reduced by 50.1 %.
At the same time, by comparing the different mechanisms of the two processes of canopy stomatal resistance and leaf nitrogen-limiting factors, this study also finds that the diurnal changes in dry deposition velocity simulated by each regional model present four sets of distributions.
This is mainly due to the different ways that each integrated mechanism handles the opening and closing of stomata at noon and the way the nitrogen-limiting factor acts.
Land surface processes play a vital role in the exchange of momentum, energy, and mass between the land and the atmosphere. However, the current model simplifies the canopy structure using approximately three to six parameters, which makes the representation of canopy radiation and energy distribution uncertain to a large extent. To improve the simulation performance, more specific canopy structure parameters were retrieved by a UAV-LiDAR observation system and updated into the multiparameterization version of the Noah land surface model (Noah-MP) for a typical forest area. Compared with visible-light photogrammetry, LiDAR retrieved a more accurate vertical canopy structure, which had a significant impact on land–air exchange simulations. The LiDAR solution resulted in a 35.0∼48.0% reduction in the range of perturbations for temperature and another 27.8% reduction in the range of perturbations for moisture. This was due to the canopy structure affecting the radiation and heat fluxes of the forest, reducing their perturbation range by 7.5% to 30.1%. To reduce the bias of the land surface interaction simulation, it will be necessary to improve the method of retrieving the canopy morphological parameterization through UAV-LiDAR on a continued basis in the future.
Abstract. The rapid urbanization and economic development of China has led to a dramatic increase in nitrogen oxide (NO2) emissions, causing serious atmospheric nitrogen pollution and relatively high levels of nitrogen deposition. However, despite the importance of nitrogen deposition, dry deposition processes in forested areas are still insufficiently represented in current global and regional atmospheric chemistry models, which constrains our understanding and prediction of spatial and temporal patterns of nitrogen transport in forest ecosystems in South China. The offline 1-D community Noah land surface model with multi-parameterization options (Noah-MP) is coupled with the WRF-Chem dry deposition module (WDDM) and is applied to further understand and identify the key processes that affect forest canopy dry deposition. The canopy stomatal resistance mechanism and the nitrogen-limitings scheme for photosynthesis in Noah-MP-WDDM are modified to improve the simulation of reactive nitrogen oxide dry deposition velocity. This study finds that the combined improved stomatal resistance mechanism and nitrogen-limitings scheme for photosynthesis (BN-23) agrees better with the observed NO2 dry deposition velocity, with mean bias reduced by 50.1 %, respectively. At the same time, by comparing the different mechanisms of the two processes of canopy stoma resistance and leaf nitrogen-limiting factors, this study also finds that the diurnal changes in dry deposition velocity simulated by each regional model present four sets of distributions. This is mainly due to the different ways that each integrated mechanism handles the opening and closing of stomata at noon and the way the nitrogen-limiting factor acts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.