Formation, Thermodynamic Structure, and Airflow of a Japan Sea Polar-Airmass Convergence Zone

The Sea of Japan (SOJ) coast and adjoining orography of central Honshu, Japan receive substantial snowfall each winter. A frequent contributor during cold-air outbreaks (CAOs) is the Japan Sea Polar-Airmass Convergence Zone (JPCZ), which forms downstream of the Korean Highlands, extends southeastward to Honshu, and generates a mesoscale band of precipitation. Mesoscale polar vortices (MPVs) ranging in horizontal scale from tens (i.e., meso-β-scale cyclones) to several hundred kilometers (i.e., “polar lows”) are also common during CAOs and often interact with the JPCZ. Here we use satellite imagery and Weather Research and Forecast model (WRF) simulations to examine the formation, thermodynamic structure, and airflow of a JPCZ that formed in the wake of an MPV during a CAO from 2–7 February 2018. The MPV and its associated warm seclusion and bent-back front developed in a locally warm, convergent, and convective environment over the SOJ near the base of the Korean Peninsula. The nascent JPCZ was structurally continuous with the bent-back front and lengthened as the MPV migrated southeastward. Trajectories illustrate how flow splitting around the Korean Highlands, channeling through low passes and valleys along the Asian coast, and air-sea interactions affect the formation and thermodynamic structure of the JPCZ. Contrasts in airmass origin and thermodynamic modification over the SOJ affect the cross-JPCZ temperature gradient, which reverses in sign along the JPCZ from the Asian coast to Honshu. These results provide new insights into the thermodynamic structure of the JPCZ, which is an important contributor to hazardous weather over Japan.

Mesoscale Predictability in Moist Mid-Latitude Cyclones Is Not Sensitive to the Slope of the Background Kinetic Energy Spectrum

We investigate the sensitivity of mesoscale atmospheric predictability to the slope of the background kinetic energy spectrum E by adding initial errors to simulations of idealized moist midlatitude cyclones at several wavenumbers k for which the slope of E(k) is significantly different. These different slopes arise from 1) differences in the E(k) generated by cyclones growing in two different moist baroclinically unstable environments, and 2) differences in the horizontal scale at which initial perturbations are added, with E(k) having steeper slopes at larger scales. When small-amplitude potential temperature perturbations are added, the error growth through the subsequent 36-hour simulation is not sensitive to the slope of E(k) nor to the horizontal scale of the initial error. In all cases with small-amplitude perturbations, the error growth in physical space is dominated by moist convection along frontal boundaries. As such, the error field is localized in physical space and broad in wavenumber (spectral) space. In moist mid-latitude cyclones, these broadly distributed errors in wavenumber space limit mesoscale predictability by growing up-amplitude rather than by cascading upscale to progressively longer wavelengths. In contrast, the error distribution in homogeneous turbulence is broad in physical space and localized in wavenumber space, and dimensional analysis can be used to estimate the error growth rate at a specific wavenumber k from E(k). Predictability estimates derived in this manner, and from the numerical solutions of idealized models of homogeneous turbulence, depend on whether the slope of E(k) is shallower or steeper than k−3, which differs from the slope-insensitive behavior exhibited by moist mid-latitude cyclones.

Scale sensitivity of the Gill circulation, Part II: Off-equatorial case

We investigate the steady dynamical response of the atmosphere on the equatorial β-plane to a steady, localized, mid-tropospheric heating source. Following Part I which investigates the case of an equatorial diabatic heating, we explore the sensitivity of the Gill circulation to the latitudinal location of the heating, together with the sensitivity to its horizontal scale. Again, we focus on characteristics of the response which would be particularly important if the circulation interacted with the hydrologic and energy cycles: overturning circulation and low-level wind. In the off-equatorial case, the intensity of the overturning circulation has the same limit as in the equatorial case for small horizontal extent of the diabatic heating, which is also the limit in the f-plane case. The decrease in this intensity with increasing horizontal scale of the diabatic heating is slightly faster in the off-equatorial case than in the equatorial case, which is due to the increase of rotational winds at the expense of divergent winds. The low-level westerly jet is more intense than in the equatorial case, with larger maximum wind and eastward mass transport that tend to infinity for small horizontal extent of the diabatic heating. In terms of spatial characteristics, this jet has a similar latitudinal extent as in the equatorial case but, unlike in the equatorial case, it extends further equatorward than poleward of the diabatic-heating center. It also extends further eastward than in the equatorial case.

Scaling Up Tobacco Cessation within TB Programmes: Findings from a Multi-Country, Mixed-Methods, Implementation Study.

Background: Brief behavioural support can effectively help TB patients to quit smoking and improve their outcomes. In collaboration with TB programmes in Bangladesh, Nepal and Pakistan, we evaluated implementation and scale-up of cessation support using four strategies: i) brief tobacco cessation intervention ii) integration of tobacco cessation within routine training iii) inclusion of tobacco indicators in routine records and iv) embedding research within TB programmes.Methods: We used mixed methods of observation, interviews and routine data within WHO’s ExpandNet framework for scale-up. We aimed to understand the extent of, and strategies which facilitated vertical scale-up (institutionalisation) within 59 health facility learning sites in Pakistan, 18 in Nepal and 15 in Bangladesh and horizontal scale-up (increased coverage beyond learning sites). We observed training and surveyed 169 TB health workers to measure changes in their confidence to deliver cessation. Routine TB data from the learning sites was analysed to assess delivery of the intervention and use of TB forms revised to report smoking status and cessation support provided. A purposive sample of TB health workers, managers and policymakers were interviewed (Bangladesh: n=12; Nepal n=13; Pakistan n=19;). Costs of scale-up were estimated using activity-based cost-analysis. Results: Routine data indicated health workers in learning sites asked all TB patients about tobacco use and offered them cessation support. Qualitative data showed use of intervention materials, often with adaptation and partial implementation in busy clinics. Short (1-2 hours) training integrated within existing programmes increased mean confidence to deliver cessation by 17% (95% CI: 14% to 20%). A focus on health system changes (reporting, training, supervision) facilitated vertical scale-up. Dissemination of materials beyond learning sites and changes to national reporting forms and training indicated horizontal scale-up. Embedding research within TB health systems was crucial for horizontal scale-up and required dynamic use of tactics e.g. alliance-building, engagement in wider policy process, use of insider-researchers, and deep understanding of health system actors and processes. Conclusions: System-level changes within TB programmes may enable routine delivery of cessation support to TB patients. These strategies are inexpensive and, with concerted efforts from TB programmes and donors, tobacco cessation can be institutionalised at-scale.

Prediction for cloud spacing confirmed using stereo cameras

Using three years of the Clouds Optically Gridded by Stereo (COGS) product, the mean cloud base, cloud top, cloud width, and cloud spacing are described with respect to their seasonal and/or diurnal evolution at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site. In addition to confirming and extending prior results, the data show that the effective diameter of shallow cumuli are approximately equal to the height above ground of the lifting condensation level (LCL). Furthermore, the cloud spacing is found to closely match a prediction by Thuburn and Efstathiou for the horizontal scale of the largest unstable eddies in an unsheared convective boundary layer.

Implementation and Scale Up of Tobacco Cessation Within TB Programmes: Findings from a Multi-Country, Mixed-Methods Implementation Study

Background: Brief behavioural support can effectively help TB patients to quit smoking and improve their outcomes. In collaboration with TB programmes in Bangladesh, Nepal and Pakistan, we evaluated implementation and scale-up of cessation support using four strategies: i) brief tobacco cessation intervention ii) integration of tobacco cessation within routine training iii) inclusion of tobacco indicators in routine records and iv) embedding research within TB programmes.Methods: We used mixed methods of observation, interviews and routine data within WHO’s ExpandNet framework for scale-up. We aimed to understand the extent of, and strategies which facilitated vertical scale-up (institutionalisation) within 59 health facility learning sites in Pakistan, 18 in Nepal and 15 in Bangladesh and horizontal scale-up (increased coverage beyond learning sites). We observed training and surveyed 169 TB health workers to measure changes in their confidence to deliver cessation. Routine TB data from the learning sites was analysed to assess delivery of the intervention and use of TB forms revised to report smoking status and cessation support provided. A purposive sample of TB health workers, managers and policymakers were interviewed (Bangladesh: n=12; Nepal n=13; Pakistan n=19;). Costs of scale-up were estimated using activity-based cost-analysis. Results: Routine data indicated health workers in learning sites asked all TB patients about tobacco use and offered them cessation support. Qualitative data showed use of intervention materials, often with adaptation and partial implementation in busy clinics. Short (1-2 hours) training integrated within existing programmes increased mean confidence to deliver cessation by 17% (95% CI: 14% to 20%). A focus on health system changes (reporting, training, supervision) facilitated vertical scale-up. Dissemination of materials beyond learning sites and changes to national reporting forms and training indicated horizontal scale-up. Embedding research within TB health systems was crucial for horizontal scale-up and required dynamic use of tactics e.g. alliance-building, engagement in wider policy process, use of insider-researchers, and deep understanding of health system actors and processes. Conclusions: System-level changes within TB programmes may enable routine delivery of cessation support to TB patients. These strategies are inexpensive and, with concerted efforts from TB programmes and donors, tobacco cessation can be institutionalised at-scale.

Influence of Soil Heterogeneity on the Contact Problems in Geotechnical Engineering

Contact problems are widely encountered in geotechnical engineering, such as the contact between soils and concrete used in earth and rockfill dams, tunnels and coastal levees. Due to the unknown contact region and contact forces, the contact problems have strong boundary nonlinearity. In addition, soils have been recognized as heterogeneous materials in geotechnical engineering. The existence of the soil heterogeneity increases the nonlinearity of the contact problems. Currently, the contact problems are mostly analysed without considering the soil heterogeneity, which may not reflect the contact behavior well. In order to investigate the influence of soil heterogeneity on the contact problems, in this paper, a simple plane-strain contact problem is analysed as an example. In this example, Young’s modulus is taken to be a spatially variable. The local average subdivision (LAS) is used to model the heterogeneity of Young’s modulus. The penalty method is utilised to determine the contact behavior. By the first use of linking the penalty method with the LAS, the proposed approach can be used to analyse the contact problems considering soil heterogeneity. The results show that the influence of soil heterogeneity on the elastic contact problems is significant. The contact forces of the heterogeneous case present apparent variation compared to the results of the homogeneous case. The distribution of the contact force at a specific point is also normal when Young’s modulus is normally distributed, moreover, the coefficient of variation (COV) and the horizontal scale of fluctuation of Young’s modulus affect the extent of variation of the normal contact forces. The standard deviation of the normal contact force increases with the increase of the COV and decreases with the increase of the horizontal scale of fluctuation of Young’s modulus. From the analyses, to better predict the deformation/stress in the contact problems, heterogeneity needs to be considered.

Probabilistic Bearing Capacity of a Pavement Resting on Fibre Reinforced Embankment Considering Soil Spatial Variability

This paper intends to examine the influence of spatial variability of soil properties on the probabilistic bearing capacity of a pavement located on the crest of a fibre reinforced embankment. An anisotropic random field, in combination with the finite difference method, is used to carry out the probabilistic analyses. The cohesion and internal friction angle of the soil are assumed to be lognormally distributed. The Monte Carlo simulations are carried out to obtain the mean and coefficient of variation of the pavement bearing capacity. The mean bearing capacity of the pavement is found to decrease with the increase in horizontal scale of fluctuation for a constant vertical scale of fluctuation; whereas, the coefficient of variation of the bearing capacity increases with the increase in horizontal scale of fluctuation. However, both the mean and coefficient of variation of bearing capacity of the pavement are observed to be increasing with the increase in vertical scale of fluctuation for a constant horizontal scale of fluctuation. Apart from the different scales of fluctuation, the effects of out of the plane length of the embankment and randomness in soil properties on the probabilistic bearing capacity are also investigated in the present study.

Horizontal scale of large-scale convective self-aggregation and their sensitivity to SST

<p>We conducted radiative convective equilibrium (RCE) experiments with varying domain size and sea surface temperature (SST) using the global cloud-system-resolving model NICAM (Satoh et al. 2014) to investigate the dependence of the maximum horizontal scale of the convective cluster on SST.</p><p>Convective self-aggregation in RCE simulations are widely studied, where convections spontaneously organize into a humid convective cluster even in the absence of inhomogeneities in boundary conditions and forcing. Previous studies show that convective self-organization does not occur when the domain size is too small, and that convective region become single-connected regions within a certain domain size, whereas when the domain size is large enough, multiple convective clusters are generated. In a previous study, although the maximum horizontal scale of the convective cluster was estimated to be about 4000 km, but the domain size of the simulation was smaller than the Earth surface, so it is not certain whether the preferable size of the convective aggregation exists over the realistic domain of the Earth. Moreover, it is now well understood how the horizontal size of the aggregation depends on SST; this aspect is relevant to understanding of the climate sensitivity.</p><p>The experiments were conducted with the NICAM simulations with switching off convective parameterization over a non-rotating spherical domain over the area of the region by varying the radius (the Earth radius R, R/2, R/4, R/8, and R/16). The horizontal uniform constant SST was changed as 295, 300, and 305K. The results show that there was a single convective cluster at a radius of R/4 or less, while there were multiple convective clusters at a radius of R/2 or more. The threshold for the transition between multiple convective clusters and a single convective cluster is found to be between R/4 and R/2. Physical variables such as vertical profiles of temperature and humidity gradually changes as the radius becomes larger, and converged at the radius R/2. For the SST dependency, the result robustly indicates that the maximum horizontal scale of the convection cluster is not monotonic with SST and it was largest for SST 300K.</p><p>As the domain size increases, the domain average moistens, and the boundary layer wind speed increases. Because the diabatic radiative cooling is constrained by the temperature and humidity structure, the surface evaporation and thus the surface wind speed must also be constrained with an upper limit; this is why the maximum horizontal scale exists and there are multiple convective clusters for the domain size larger than R/2. We also found that the moist static energy transport from the convective region decreases as the domain becomes larger, as pointed out by Patrizio and Randall (2019). The horizontal scale dependence of the convective cluster is related to two factors: the effect of the horizontal pressure difference in the boundary layer and the circulation structure of free troposphere. The energy budget analysis also explains the SST dependence of the maximum horizontal scale of the convective clusters.</p>