Taklimakan Desert (TD), the second-largest shifting sand desert in the world, is located in the central Tarim Basin, north of the Tibetan Plateau, and is surrounded by high mountains in the shape of the letter C (Figure S1 in Supporting Information S1). It is characterized by an extremely arid landscape and is the main source of mineral dust. Through the dynamic coupling with the Tibetan Plateau, the TD has significant implications for the downwind areas, which makes it a key climate region in

Terrestrial ecosystems in China receive the world’s largest amount of reactive nitrogen (N) deposition. Recent controls on nitrogen oxides (NOx = NO + NO2) emissions in China to tackle air pollution are expected to decrease N deposition, yet the observed N deposition fluxes remain almost stagnant. Here we show that the effectiveness of NOx emission controls for reducing oxidized N (NOy = NOx + its oxidation products) deposition is unforeseen in Eastern China, with one-unit reduction in NOx emission leading to only 55‒76% reductions in NOy-N deposition, as opposed to the high effectiveness (around 100%) in both Southern China and the United States. Using an atmospheric chemical transport model, we demonstrate that this unexpected weakened response of N deposition is attributable to the enhanced atmospheric oxidizing capacity by NOx emissions reductions. The decline in N deposition could bear a penalty on terrestrial carbon sinks and should be taken into account when developing pathways for China’s carbon neutrality.

The dissimilarity between the turbulent transport of momentum and heat under unstable conditions and its physical mechanisms are investigated in this study, based on the multiple‐level turbulence observation from the Tianjin 255‐m meteorological tower. The transport dissimilarity is observed from the surface layer to the lower part of mixed layer as atmospheric instability increases. Although the transport dissimilarity is accompanied by the development of plumes and thermals under unstable conditions, plumes and thermals can produce intense transport both of momentum and heat simultaneously. It is convective circulations induced by vigorous thermals that cause transport dissimilarity. The horizontal divergence generated by convective circulations imposes a dominant large‐scale reduction in the along‐wind velocity component near the surface, which is related to increased counter gradient transport of momentum, while the temporal variations in temperature mainly reflect the role of plumes and thermals and thus the transport of heat is predominantly down‐gradient. This difference in respective physical processes subsequently leads to dissimilar transport between momentum and heat under unstable conditions. Therefore, it is of great interest to represent the influence of convective circulations on the momentum‐flux estimation in future investigations, aiming to improve the boundary‐layer parameterization schemes for mesoscale numerical weather models.

This study estimates long‐term PM2.5 exchange flux between the atmospheric boundary layer (ABL) and free troposphere (FT) in the North China Plain. The effect of PM2.5 long‐range transport (LRT) on air quality in downwind regions is also assessed. The PM2.5 exchange fluxes are calculated based on a mass budget method with data from WRF‐Chem simulations, during wintertime months (November, December, and January) in 2014, 2016, and 2017 (represent moderate, heavier, and less polluted years). The overall PM2.5 exchange exhibits clear topographical correlation and diurnal variation. The plain area is characterized by a considerable upward flux of −0.13 μg m−2 s−1 (in a 3‐year average), acting as an effective source for LRT. ABL height variation contributes significantly to the diurnal cycle of PM2.5 vertical exchange. Over the mountainside and ridge areas, the PM2.5 exchange flux is downward and its diurnal variation is weak, due to the dominant cross‐mountain descent flows. Four LRT patterns in the FT are identified, that is, eastward, southward, recirculation, and local stagnation. They can affect air quality in Northeast China, Yangtze River Delta, South Korea, and Japan. Indicating with averages and standard deviations, the PM2.5 concentration increases (relative contribution) for these four target regions over the 3‐year winter period are respectively 5.5 ± 4.8 μg m−3 (12.6 ± 10.9%), 4.6 ± 4.5 μg m−3 (8.4 ± 6.4%), 4.4 ± 3.9 μg m−3 (5.2 ± 4.4%), and 1.6 ± 0.9 μg m−3 (2.6 ± 1.6%). While the maximum impacts can be 36.7 μg m−3 (59%), 31.1 μg m−3 (41%), 25.7 μg m−3 (30%), and 7.2 μg m−3 (13%), respectively.

Turbulence intermittency driven by submeso motions limits the progress of turbulence theory. Field observations from the Horqin Atmospheric Boundary‐Layer and Environment Experimental Station, China were used to investigate turbulence intermittency. An automated algorithm to Separate and reconstruct Submeso and Turbulent motions (SST) was improved for more accurately extraction and quantitative characterization of submeso motions. The existing intermittency intensity indexes, the local intermittency strength of turbulence (LIST) and intermittency strength (IS), which are based on kinetic energy only, are revised by considering the potential energy of submeso and turbulent motions to quantify intermittency intensity more comprehensively. The analysis of eight cases revealed that turbulent intermittency events are characterized by quiescent (pulsation, material, and energy transportation are weak) and burst (pulsation, material, and energy transportation fluctuate violently) periods. The conversion of both the kinetic and potential energy of submeso to turbulent motion contributes to the transition from quiescent to burst periods. The transition always occurs after ∆normalTE$$ \Delta \mathrm{TE} $$ <0 (the total energy difference between the submeso motion and turbulence), followed by a significant increase in ∆normalTE$$ \Delta \mathrm{TE} $$. Atmospheric stability decreases during the transition from quiescent to burst periods in most cases. In a totally intermittent night, the burst periods take up most of the material and energy transport, and the amount transported is not smaller than that during a totally turbulent night. The weaker the intermittency at night, the greater the capacity of turbulent transport. A comparison of five types of turbulence intermittency intensity indexes highlights the consistency and advantages between LIST (IS) and indexes in the literature. Finally, we found that turbulent intermittency events tended to occur more easily in the atmospheric boundary layer (ABL) with small winds (U < 2 m s−1) or stable stratification (Rib > 1), although they can also occur in ABL with unstable stratification and in the non‐stationary state of the day–night transition.