The Performance of a Scale-Aware Nonlocal PBL Scheme for the Subkilometer Simulation of a Deep CBL over the Taklimakan Desert

Although realistic representation of the convective boundary layer (CBL) in the desert region in Northwest China is important for weather forecasts and climate simulations, evaluations of the performance of various planetary boundary layer (PBL) schemes in simulating the CBL in the region are rare. In this study, the performance of a scale-aware PBL scheme newly implemented into the Weather Research and Forecasting (WRF) model in simulating the CBL in the Taklimakan desert is evaluated based on a comparison with both the WRF-LES simulations and observations, with the focus on scale dependencies of the simulations compared to the conventional PBL scheme. A series of simulations are performed with a scale-aware PBL scheme (Shin-Hong) and the conventional PBL scheme (YSU) for a deep CBL observed at Tazhong station in the central Taklimakan on 1 July 2016. The CBL was over 5000 m deep with wider and deeper rolls than in a shallow boundary layer. The results showed that the vertical structure simulated with the Shin-Hong scheme was closer to that in both the WRF-LES (large-eddy-simulation) and observations than that simulated with the YSU. The simulation with the scale-aware scheme reproduced cellular rolls similar to those in the WRF-LES, while the conventional PBL scheme struggled to trigger intense convective cells rather than cellular rolls. The results strongly suggest that the scale-aware nonlocal PBL scheme can be used to adequately reproduce the scale and evolution of the observed rolls in the deep CBL in Taklimakan desert at subkilometer resolutions

Relation between the Atmospheric Boundary Layer and Impact Factors under Severe Surface Thermal Conditions

This paper reported a comprehensive analysis on the diurnal variation of the Atmospheric Boundary Layer (ABL) in summer of Badain Jaran Desert and discussed deeply the effect of surface thermal to ABL, including the Difference in Surface-Air Temperature (DSAT), net radiation, and sensible heat, based on limited GPS radiosonde and surface observation data during two intense observation periods of experiments. The results showed that (1) affected by topography of the Tibetan Plateau, the climate provided favorable external conditions for the development of Convective Boundary Layer (CBL), (2) deep CBL showed a diurnal variation of three- to five-layer structure in clear days and five-layer ABL structure often occurred about sunset or sunrise, (3) the diurnal variation of DSAT influenced thickness of ABL through changes of turbulent heat flux, (4) integral value of sensible heat which rapidly converted by surface net radiation had a significant influence on the growth of CBL throughout daytime. The cumulative effect of thick RML dominated the role after CBL got through SBL in the development stage, especially in late summer, and (5) the development of CBL was promoted and accelerated by the variation of wind field and distribution of warm advection in high and low altitude

Alterations of gut microbiota in a mouse model with partial small intestinal obstruction

IntroductionChanges in the gut microbiota of patients with partial small intestinal obstruction (PSIO) have not been widely clarified. We aimed to explore bacterial diversity in a PSIO mouse model.MethodsA PSIO mouse model was established using male C57BL/6 mice, and feces samples from the distal ileum and ileum epithelium tissues were collected. MiSeq sequencing of the 16S rRNA gene was conducted to characterize microbiota diversity and composition. RNA sequencing for differences in transcriptomic programming of the ileum tissue was performed between the PSIO and (Control) Ctrl groups.ResultsBacterial diversity in the PSIO group was significantly lower than that in the controls. Pseudomonadota was predominant in the feces of the PSIO group. Unclassified_Muribaculaceae (p = 0.008) and Akkermansia (p = 0.007) were more abundant in the Ctrl group than those in the PSIO group. Furthermore, Escherichia_Shigella (p = 0.008) was more predominant in the feces of the PSIO group. The Kyoto Encyclopedia of Genes and Genomes pathways related to metabolism were depleted in the PSIO group. Pathways associated with intestinal fibrosis, including extracellular matrix-receptor interaction, focal adhesion, phosphoinositide 3-kinase (PI3K)-Akt signaling pathway and transforming growth factor (TGF)-beta signaling pathway, which were enriched in ileum epithelial tissue in the PSIO group.ConclusionPSIO can lead to changes in the predominant intestinal bacterial groups. Depleted functional profiles of the gut microbiota were identified in the PSIO group. Functional pathways associated with intestinal fibrosis were activated by PSIO. The potential regulation by the microbiota needs to be explored in the future

Analyses of temperature and humidity profiles and heat balance of the surface boundary-layer in the hinterland of the Taklimakan Desert

The daily variation regularities of micro-meteorological features, such as the surface layer temperature and humidity profiles of the inner desert in summer, the temperature of sand bed, the radiation of the earth's surface and the heat balance, were analyzed by combination method and logarithm regression according to the data obtained from the Atmospheric Environmental Observation Station of Taklimakan Desert in July-August of 2006 and 2007. It has been shown that temperature inversion occurred near the surface layer at night in summer, the temperature increased with the height within a certain altitude range, and the reverse was true during the daytime. The ground surface radiation balance of the Taklimakan Desert was mainly positive; other radiation components (the global radiation, the reflective radiation, the ground upward long wave radiation and the net radiation) exhibited daily variation characteristics evidently and showed normal diurnal cycle, except for the downward atmospheric long-wave radiation. The heat exchange of the surface layer of the desert was dominated by turbulence sensible heat, and only a small portion of heat was transferred to the atmospheric surface layer in the form of latent heat. The surface sensible heat and latent heat changed with the increase and decrease of sun elevation angle, with maximum of the latent heat appearing in wee hours and the peak value of the sensible heat appearing at noon. Observation and analysis showed that heating effect of the underlying surface of the desert was great on the aerosphere; the surface was a high heat source during the day and became a weak cold source at night

Quantitative Detection of Dust Storms with the Millimeter Wave Radar in the Taklimakan Desert

In order to conduct real-time quantitative monitoring of dust storms, Ka-band millimeter wave radar (MMWR) was utilized for the consecutive detection of dust storms over the Taklimakan Desert from April to June 2018. The retrievals of the reflectivity factor, dust spectrum distribution and dust mass concentration were carried out with the power spectrum data detected by MMWR for three dust storm processes. The analysis shows that: The probability density distribution of dust conforms to the lognormal distribution. During the dust storm processes, the effective detection height of the reflectivity factor was within 2000 m and the range of the reflectivity factors was between − 25   dBZ and 25   dBZ . During the floating dust period, the effective height of the dust spectrum distribution was lower than 300 m and the values of dust mass concentration were less than 31.62 μ g · m − 3 , at a height of 200 m. Furthermore, during the blowing sand stage, the effective height of the dust spectrum distribution was normally lower than 600 m and the values of dust mass concentration were mainly less than 316.23   μ g · m − 3 , at a height of 200 m. During the dust storm period, the effective height of the dust spectrum distribution exceeded 1000 m; when the height was 100 m, the values of dust mass concentration were between 1220   μ g · m − 3   and   42,146   μ g · m − 3 and the average mass concentration was 9287   μ g · m − 3 ; whereas, the values of dust mass concentration were between 2   μ g · m − 3   and   820   μ g · m − 3 when the height was 1200 m and the average mass concentration was 24   μ g · m − 3 . The relationship between the reflectivity factor Z and the dust mass concentration M is defined as Z = 651.6 M 0.796 . Compared with the observational data from Grimm180 particle detector, the data of the retrieved dust mass concentration are basically accurate and this retrieved method proves to be feasible. Thus, the MMWR cans be used as a new device for quantitative monitoring of dust storms

The Impacts of Wind Shear on Spatial Variation of the Meteorological Element Field in the Atmospheric Convective Boundary Layer Based on Large Eddy Simulation

As wind shear increases, the quasi-two-dimensional structure of flows becomes more significant in the convective boundary layer (CBL), indicating that wind shear plays an essential role in the variation of the field of atmospheric flow. Therefore, sensitive numerical experiments based on Large Eddy Simulation (LES) techniques were conducted to comprehensively investigate the effects of wind shear on the spatial variations in the velocity and potential temperature (θ) horizontal fields. Under the constant surface heat flux condition, the main findings are summarized. Firstly, in the CBL, the variances of the streamwise velocity (u), cross-stream velocity (v), and θ enhance as wind shear increases, whereas the variance of vertical velocity (w) is insensitive to wind shear. Secondly, in the CBL, with increasing wind shear, low-wavenumber Power Spectrum Densities (PSDs) of u, v, w, and θ increase significantly, suggesting that the increasing wind shear always enhances the large-scale motions of the atmosphere (i.e., low-wavenumber PSD). Therefore, it is more likely that some mesoscale weather processes will be triggered. Thirdly, generally, in the high-wavenumber range, with increasing wind shear, the PSDs of u, v, and θ increase slightly, whereas the PSD of w decreases slightly. This study provides a new perspective for understanding the role of wind shear in the spatial variations of the horizontal fields of meteorological elements under the same conditions of surface heat flux

The Impacts of Wind Shear on Spatial Variation of the Meteorological Element Field in the Atmospheric Convective Boundary Layer Based on Large Eddy Simulation

As wind shear increases, the quasi-two-dimensional structure of flows becomes more significant in the convective boundary layer (CBL), indicating that wind shear plays an essential role in the variation of the field of atmospheric flow. Therefore, sensitive numerical experiments based on Large Eddy Simulation (LES) techniques were conducted to comprehensively investigate the effects of wind shear on the spatial variations in the velocity and potential temperature (θ) horizontal fields. Under the constant surface heat flux condition, the main findings are summarized. Firstly, in the CBL, the variances of the streamwise velocity (u), cross-stream velocity (v), and θ enhance as wind shear increases, whereas the variance of vertical velocity (w) is insensitive to wind shear. Secondly, in the CBL, with increasing wind shear, low-wavenumber Power Spectrum Densities (PSDs) of u, v, w, and θ increase significantly, suggesting that the increasing wind shear always enhances the large-scale motions of the atmosphere (i.e., low-wavenumber PSD). Therefore, it is more likely that some mesoscale weather processes will be triggered. Thirdly, generally, in the high-wavenumber range, with increasing wind shear, the PSDs of u, v, and θ increase slightly, whereas the PSD of w decreases slightly. This study provides a new perspective for understanding the role of wind shear in the spatial variations of the horizontal fields of meteorological elements under the same conditions of surface heat flux

Characterization of the Interaction between Gallic Acid and Lysozyme by Molecular Dynamics Simulation and Optical Spectroscopy

The binding interaction between gallic acid (GA) and lysozyme (LYS) was investigated and compared by molecular dynamics (MD) simulation and spectral techniques. The results from spectroscopy indicate that GA binds to LYS to generate a static complex. The binding constants and thermodynamic parameters were calculated. MD simulation revealed that the main driving forces for GA binding to LYS are hydrogen bonding and hydrophobic interactions. The root-mean-square deviation verified that GA and LYS bind to form a stable complex, while the root-mean-square fluctuation results showed that the stability of the GA-LYS complex at 298 K was higher than that at 310 K. The calculated free binding energies from the molecular mechanics/Poisson-Boltzmann surface area method showed that van der Waals forces and electrostatic interactions are the predominant intermolecular forces. The MD simulation was consistent with the spectral experiments. This study provides a reference for future study of the pharmacological mechanism of GA