Demistify: a large-eddy simulation (LES) and single-column model (SCM) intercomparison of radiation fog

An intercomparison between 10 single-column (SCM) and 5 large-eddy simulation (LES) models is presented for a radiation fog case study inspired by the Local and Non-local Fog Experiment (LANFEX) field campaign. Seven of the SCMs represent single-column equivalents of operational numerical weather prediction (NWP) models, whilst three are research-grade SCMs designed for fog simulation, and the LESs are designed to reproduce in the best manner currently possible the underlying physical processes governing fog formation. The LES model results are of variable quality and do not provide a consistent baseline against which to compare the NWP models, particularly under high aerosol or cloud droplet number concentration (CDNC) conditions. The main SCM bias appears to be toward the overdevelopment of fog, i.e. fog which is too thick, although the inter-model variability is large. In reality there is a subtle balance between water lost to the surface and water condensed into fog, and the ability of a model to accurately simulate this process strongly determines the quality of its forecast. Some NWP SCMs do not represent fundamental components of this process (e.g. cloud droplet sedimentation) and therefore are naturally hampered in their ability to deliver accurate simulations. Finally, we show that modelled fog development is as sensitive to the shape of the cloud droplet size distribution, a rarely studied or modified part of the microphysical parameterisation, as it is to the underlying aerosol or CDNC.

A fast, single column extraction chromatography method for the isolation of Neodymium from iron-rich materials prior to radiogenic isotope ratio measurements

A novel separation method is described for the separation of Nd from Fe-rich, silicate samples in view of isotopic analyses. The procedure is based on the synergistic enhancement of the...

Assessment of the sea surface temperature diurnal cycle in CNRM-CM6-1 based on its 1D coupled configuration

A single column version of the CNRM-CM6-1 global climate model has been developed to ease development and validation of the boundary layer physics and air-sea coupling in a simplified environment. This framework is then used to assess the ability of the coupled model to represent the sea surface temperature (SST) diurnal cycle. To this aim, the atmospheric-ocean single column model (AOSCM), called CNRM-CM6-1D, is implemented on a case study derived from the Cindy-Dynamo field campaign over the Indian Ocean, where large diurnal SST variabilities have been well documented. Comparing the AOSCM and its uncoupled components (atmospheric SCM and oceanic SCM, called OSCM) highlights that the impact of coupling in the atmosphere results both from the possibility to take in to account the diurnal variability of SST, not usually available in forcing products, and from the change in mean state SST as simulated by the OSCM, the ocean mean state not being heavily impacted by the coupling. This suggests that coupling feedbacks are more due to advection processes in the 3D model than to the model physics. Additionally, a sub-daily coupling frequency is needed to represent the SST diurnal variability but the choice of the coupling time-step between 15 min and 3 h does not impact much on the diurnal temperature range simulated. The main drawback of a 3-h coupling being to delay the SST diurnal cycle by 5 h in asynchronous coupled models. Overall, the diurnal SST variability is reasonably well represented in the CNRM-CM6-1 with a 1 h coupling time-step and the upper ocean model resolution of 1 m. This framework is shown to be a very valuable tool to develop and validate the boundary layer physics and the coupling interface. It highlights the interest to develop other atmosphere-ocean coupling case studies.

Study on the Influence of Initiation Model on the Forming Characteristics of MEFP Warhead

To study the influence of different initiation modes on the forming characteristics of the MEFP warhead, numerical simulations were carried out on three types of initiation modes. The numerical simulation results showed that the number of EFPs was the least by double-column multipoint synchronous initiation, the number of EFPs was the largest by the central single-point (multipoint) initiation, and single-column single-point (multipoint synchronous) detonation forms the number of EFPs between central single-point (multipoint synchronous) detonation and double-column multipoint synchronous detonation. For the MEFP warhead of a small-caliber grenade, whether it is center detonation or eccentric detonation, the EFP velocity of multipoint detonation is higher than that of the single-point detonation, the velocity of double-column multipoint eccentric synchronous detonation is 2%–9% higher than that of the single-column single-point (multipoint eccentric synchronous) detonation, the velocity of double-column multipoint eccentric synchronous detonation is 10%–17% higher than that of the central single-point (multipoint synchronous) detonation, and the velocity of single-column single-point (multipoint eccentric synchronous) detonation is 5%–17% higher than that of the central single-point (multipoint synchronous) detonation. Research results show that although the number of EFPs is reduced during eccentric single-point (multipoint simultaneous) detonation of MEFP warheads, a higher velocity can be obtained.

Rhodamine-B dye removal using aliquat-336 modified amberlite XAD-4 resin in fixed-bed columns in series

The present work reports studies on the effective removal of Rhodamine-B (RhB) using Aliquat-336 modified Amberlite XAD-4 resin in the fixed-bed columns in series. The effect of flow rate (Q = 2 to 6 mL·min−1), bed height (h = 3.5 to 7 cm) and initial RhB dye concentration (Cin = 10 to 20 mg·L−1) was studied. When a single column was used, 93% RhB dye was removed in 3 h at Q = 2 mL·min−1, Cin = 10 mg·L−1, and h = 7 cm. When three columns in series were used, almost 100% dye was removed until 80 h. The maximum breakthrough time (142 h) and saturation time (244 h) were found by keeping Q = 2 mL·min−1, h = 7 cm of each column and Cin = 10 mg·L−1. Mathematical modeling of the breakthrough curves was done by using Yoon-Nelson, Clark, Wolborska, and pore diffusion models. The Clark model best fitted the experimental data. The possible interaction mechanism between Aliquat-336 and RhB dye was proposed. The column was regenerated in continuous mode using 1 M HCl solution and maintaining a flow rate of 2 mL·min−1.