Improvement of stomatal resistance and photosynthesis mechanism of Noah-MP-WDDM (v1.42) in simulation of NO<sub>2</sub> dry deposition velocity in forests

Abstract. Rapid urbanisation and economic development in China have led to a dramatic increase nitrogen oxide (NO2) emissions, causing serious atmospheric pollution relatively high levels of deposition. However, despite the importance deposition, dry deposition processes forested areas are still insufficiently represented current global regional chemistry models, which constrains our understanding prediction spatial temporal patterns transport forest ecosystems southern China. The offline 1-D community Noah land surface model with multi-parameterisation options (Noah-MP) is coupled WRF-Chem module (WDDM) applied further understand identify key that affect canopy stomatal resistance mechanism nitrogen-limiting scheme for photosynthesis Noah-MP-WDDM modified improve simulation reactive velocity. This study finds combined improved (BN-23) agree better observed NO2 velocity, mean bias being reduced by 50.1 %. At same time, comparing different mechanisms two leaf factors, this also diurnal changes velocity simulated each present four sets distributions. mainly due ways integrated handles opening closing stomata at noon way factor acts.