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The transition from moderate to weak turbulence regimes remains a grand challenge for stable boundary layer parameterizations in weather and climate models. In this study, a critical horizontal Froude number (≈0.28) is proposed to characterize such a transition, which corresponds to the development of quasi two‐dimensional pancake vortices. Traditionally defined stability parameters corresponding to the critical horizontal Froude number are estimated and are consistent with values in the literature. The critical horizontal Froude number can recover previously used height‐ and site‐dependent mean wind speed thresholds. These findings offer a way to constrain the validity range of Monin‐Obukhov similarity theory in numerical models for weather and pollutants dispersion. Plain Language Summary: The transition from moderate to weak turbulence regimes in stable atmospheric boundary layers presents a grand challenge for numerical models. Our results show that such a transition occurs when the horizontal Froude number is equal to a critical value of about 0.28, which is physically connected to the development of quasi two‐dimensional pancake vortices. These findings can help improve turbulence parameterizations in numerical models for weather and pollutants dispersion. Key Points: A critical horizontal Froude number (≈0.28) is proposed to characterize the transition from moderate to weak turbulence regimesThe critical horizontal Froude number corresponds to the development of pancake vorticesPreviously used height‐ and site‐dependent mean wind speed thresholds can be recovered from the critical horizontal Froude number [ABSTRACT FROM AUTHOR]

Cloud Layers Unified By Binormals (CLUBB) adopts the joint probability density function (PDF) to close higher‐order turbulence and diagnose the cloud fraction. CLUBB assumes the equal PDF width of vertical velocity (w $w$) as the default closure scheme, called Analytic Double Gaussian 1 (ADG1). In this study, a new unequal width PDF closure scheme is adopted in CLUBB, in which the PDF width of w $w$ is assumed to be associated with skewness and kurtosis of vertical velocity. Offline calculation shows that the updated closure scheme improves the tail in the joint PDF and produces the saturation area from the joint PDF of the total water and liquid water potential temperature closer to that derived from large‐eddy simulations than ADG1. The new PDF scheme implemented in Community Atmosphere Model Version 6 is shown to increase low cloud fraction by 20%–30% in most stratocumulus‐to‐cumulus transition regions. The updated closure scheme is found to improve the low cloud simulation by simulating more symmetric turbulence in stratocumulus and stronger turbulent transport in shallow cumulus. Furthermore, the updated closure scheme enhances the cloud fraction near the cloud base by interacting with the microphysical scheme. Our work indicates the importance of continuous improvement in the PDF closures for higher‐order turbulence schemes. Plain Language Summary: Low clouds play an important role in global energy and water cycles, and their simulations in global climate models remain challenging. Here we improved the turbulence parameterization scheme in a climate model. The new scheme updates the width assumption of vertical velocity, temperature and moisture distribution, which improves the representation of extreme skewed turbulence and makes the turbulence parameterization closer to physical reality. The updated scheme is shown to improve the distribution of moisture and temperature in better agreement with high‐resolution simulation results, and increase low cloud fraction by 20%–30% in most low cloud regions compare with observations. Key Points: An updated unequal width probability density function (PDF) closure scheme is implemented in Community Atmosphere Model Version 6The new PDF closure scheme produces the joint PDF of vertical velocity, total water and liquid water potential temperature closer to large‐eddy simulation resultsThe new PDF closure scheme improves low cloud fraction simulations by 20%–30% in most stratocumulus‐to‐cumulus transition regions [ABSTRACT FROM AUTHOR]

The impacts of urban hydrological processes, such as anthropogenic latent heat (ALH), multilayer green roof systems (GRO), evaporation from impervious surfaces (EIMP), urban irrigation (IRR), and the urban "oasis effect" (OASIS) on regional hydrometeorology in Nanjing, are assessed by the Weather Research and Forecasting Single‐Layer Urban Canopy Models (WRF‐SLUCM). The results show that including all five urban hydrological processes, ALL best improves the prediction of near‐surface meteorology and has the largest correlation coefficients, the smallest root mean square errors, and the most accurate diurnal variations compared with observations. The improvements of ALH, GRO, and OASIS are larger than those of IRR and EIMP. The influence of ALH, GRO, and OASIS is comparable in commercial areas, whereas the influence of OASIS is significantly greater and plays essential roles in low‐intensity residential areas. Therefore, the overall effect of urban hydrological processes is especially large over low‐intensity residential areas, where the ALL case‐simulated monthly mean 2‐m air temperature (surface temperature) is reduced by approximately 1.3 (5.0) °C, the 2‐m specific humidity increases by 0.8 g kg–1, and the sensible heat (latent heat) flux is reduced (increased) at most by 90 W m–2. The changes in the vertical profiles indicate that urban hydrological processes reduce the potential temperature and wind speed, whereas they increase specific humidity over the entire urban boundary layer, leading to a more stable atmospheric conditions, reduced vertical mixing, and weaker convective rolls. These effects could mitigate the intensity of urban heat/dry islands while simultaneously exacerbating low‐level air pollution. Key Points: Adding urban hydrological processes improves WRF model representation of the near‐surface meteorology and energy balanceUrban hydrological processes cool and wet the entire urban PBL reduce wind speed and lead to more stable atmospheric conditionsThese effects of urban hydrological processes may mitigate urban heat/dry islands while simultaneously exacerbating low‐level pollution [ABSTRACT FROM AUTHOR]

Abstract: Eddy correlation measurements have been carried out at six different heights above the urban canopy in three cities of China, that is, Nanjing, Changzhou, and Suzhou. Observations at these heights are used to evaluate the dependence of normalized standard deviations of velocity components σi/u*l ( i = u, v, w) and temperature σ T v / T v * l on local atmospheric stability ζ ( =(z − zd)/Λ), where u*l is the local friction velocity, Tv*l is the local temperature scale, zd is the displacement height, and Λ is the local Obukhov length. It is found that the universal functions ai(1 + bi| ζ| )1/3 and b T v ζ − 1 / 3, in which ai, bi, and b T v are empirical coefficients, are suitable for describing the behaviors of σi/u*l and σ T v / T v * l, respectively. Under neutral conditions ( |ζ| < 0.05), the value of σi/u*l (approximately equal to ai) decreases with height. On the other hand, bi increases with height under both unstable ( ζ <  − 0.05) and stable ( ζ > 0.05) conditions, suggesting that the thermal effect of stratification on the standard deviations of velocity components increases with height in the urban roughness sublayer. However, the behavior of σ T v / T v * l is different from that of σi/u*l. b T v remains constant with height under unstable conditions but increases with height under stable conditions. Vertical variations of these coefficients in the universal functions are consistent with the concept of local similarity, suggesting that the turbulence behavior in the urban roughness sublayer is different from that over the flat terrain. [ABSTRACT FROM AUTHOR]

Panax notoginseng saponins ( PNS) are major components of Panax notoginseng, a herb with established clinical efficacy against vascular diseases. SHRSP.Z- Lepr fa/IzmDmcr ( SHRSP. ZF) rats, a new animal model for metabolic syndrome, display an impaired vasorelaxation response in aortas and mesenteric arteries that is mediated by nitric oxide ( NO). This study investigated whether PNS and its components can ameliorate this vascular dysfunction in SHRSP. ZF rats. In an in vitro study, in the presence or absence of PNS and its components, vasodilation in response to nitroprusside was determined from myographs under isometric tension conditions in aortas and mesenteric arteries from male SHRSP. ZF rats at 18-20 weeks of age. In an in vivo study, PNS (30 mg/kg per day) was orally administered to SHRSP. ZF rats from 8 to 20 weeks of age. In vitro treatment with PNS and Ginsenoside Rb1 increased nitroprusside-induced relaxation of aortas and mesenteric arteries in SHRSP. ZF rats. The PNS-induced increase was not affected by a nitric oxide ( NO) synthase inhibitor or endothelium denudation. Relaxation in response to a cell-permeable cGMP analogue was increased by PNS, but cGMP accumulation by nitroprusside was not altered. In vivo treatment with PNS in SHRSP. ZF rats lowered blood pressure and increased relaxation and the expression of soluble guanylyl cyclase protein in arteries, without affecting metabolic abnormalities. These results indicate that PNS causes an increase in vasodilation in response to NO and a decrease in blood pressure, resulting in protection against vascular dysfunction in SHRSP. ZF rats. PNS might be beneficial in alleviating impaired vasodilation in metabolic syndrome. [ABSTRACT FROM AUTHOR]

ABSTRACT Oligodeoxynucleotides containing CpG motifs (CpG ODNs) are potent immune activators and are being tested as anti-tumor, antimicrobial agents and as adjuvants in vaccines. Little has been reported, however, about the systematic and comprehensive safety evaluation on repeated CpG ODN administration. To investigate the safety profile of a newly developed CpG ODN, CpG 684, we conducted a 28-day repeated dose toxicity study in rats, at dose levels of 5, 20 and 150 µg CpG 684 per rat. No abnormalities in clinical observations, growth, urinalysis and bone marrow cell counts were found in CpG 684 treated rats. CpG 684 was proved biologically active, capable of up-regulating the expressions of CD40 and CD86 molecules. The monocyte numbers were increased at the dose levels of 20 and 150 µg per rat. The spleen weights were increased in female rats at the dose level of 150 µg per rat. Microscopically, 5, 20 and 150 µg per rat CpG 684 caused local inflammatory cell infiltration and hyperplasia of fibrous tissue at injection sites; the treatment of 5 and 150 µg per rat CpG 684 induced enhanced inflammatory reaction in inguinal lymphoid tissue, and the dose of 150 µg per rat induced cell hyperplasia in white pulp of spleen and white pulp expansion. CpG 684 at 150 µg per rat led to decreases in peripheral lymphocyte, serum globulin, glucose, alkaline phosphatase and K+ levels in female rats, and induced the decrease in serum albumin and total protein in rats of both sexes. The data from this study will provide an important reference for developing CpG 684 as an adjuvant for vaccines of human use. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Panax notoginseng saponins (PNS) are major components of Panax notoginseng, a herb with established clinical efficacy against vascular diseases. SHRSP.Z-Lepr(fa) /IzmDmcr (SHRSP.ZF) rats, a new animal model for metabolic syndrome, display an impaired vasorelaxation response in aortas and mesenteric arteries that is mediated by nitric oxide (NO). This study investigated whether PNS and its components can ameliorate this vascular dysfunction in SHRSP.ZF rats. In an in vitro study, in the presence or absence of PNS and its components, vasodilation in response to nitroprusside was determined from myographs under isometric tension conditions in aortas and mesenteric arteries from male SHRSP.ZF rats at 18-20 weeks of age. In an in vivo study, PNS (30 mg/kg per day) was orally administered to SHRSP.ZF rats from 8 to 20 weeks of age. In vitro treatment with PNS and Ginsenoside Rb1 increased nitroprusside-induced relaxation of aortas and mesenteric arteries in SHRSP.ZF rats. The PNS-induced increase was not affected by a nitric oxide (NO) synthase inhibitor or endothelium denudation. Relaxation in response to a cell-permeable cGMP analogue was increased by PNS, but cGMP accumulation by nitroprusside was not altered. In vivo treatment with PNS in SHRSP.ZF rats lowered blood pressure and increased relaxation and the expression of soluble guanylyl cyclase protein in arteries, without affecting metabolic abnormalities. These results indicate that PNS causes an increase in vasodilation in response to NO and a decrease in blood pressure, resulting in protection against vascular dysfunction in SHRSP.ZF rats. PNS might be beneficial in alleviating impaired vasodilation in metabolic syndrome., (© 2016 John Wiley & Sons Australia, Ltd.)