Sea-ice retreat suggests re-organization of water mass transformation in the Nordic and Barents Seas

Water mass transformation in the Nordic and Barents Seas, triggered by air-sea heat fluxes, is an integral component of the Atlantic Meridional Overturning Circulation (AMOC). These regions are undergoing rapid warming, associated with a retreat in ice cover. Here we present an analysis covering 1950−2020 of the spatiotemporal variability of the air-sea heat fluxes along the region’s boundary currents, where water mass transformation impacts are large. We find there is an increase in the air-sea heat fluxes along these currents that is a function of the currents’ orientation relative to the axis of sea-ice change suggesting enhanced water mass transformation is occurring. Previous work has shown a reduction in heat fluxes in the interior of the Nordic Seas. As a result, a reorganization seems to be underway in where water mass transformation occurs, that needs to be considered when ascertaining how the AMOC will respond to a warming climate.

Spatial distribution of turbulent diapycnal mixing along the Mindanao current inferred from rapid-sampling Argo floats

The Mindanao Current (MC) bridges the North Pacific low-latitude western boundary current system region and the Indonesian Seas by supplying the North Pacific waters to the Indonesian Throughflow. Although the previous study speculated that the diapycnal mixing along the MC might be strong on the basis of the water mass analysis of the gridded climatologic dataset, the real spatial distribution of diapycnal mixing along the MC has remained to be clarified. We tackle this question here by applying a finescale parameterization to temperature and salinity profiles obtained using two rapid-sampling profiling Argo floats that drifted along the MC. The western boundary (WB) region close to the Mindanao Islands and the Sangihe Strait are the two mixing hotspots along the MC, with energy dissipation rate ε and diapycnal diffusivity Kρ enhanced up to ~ 10–6 W kg−1 and ~ 10–3 m2 s−1, respectively. Except for the above two mixing hotspots, the turbulent mixing along the MC is mostly weak, with ε and Kρ to be 10–11–10–9 W kg−1 and 10–6–10–5 m2 s−1, respectively. Strong mixing in the Sangihe Strait can be basically attributed to the existence of internal tides, whereas strong mixing in the WB region suggests the existence of internal lee waves. We also find that water mass transformation along the MC mainly occurs in the Sangihe Strait where the water masses are subjected to strong turbulent mixing during a long residence time.

Investigation of Thermal Performance of Evacuated Tube with Parabolic Trough Collector with and without Porous Media

In this paper a new model has demonstrated that it operates in a moderate performance scale to generate hot water. In its early stage, the preliminary model, which built with double pass water tube inside evacuated tube, was investigated experimentally. The model was tested inside room under different operation conditions in terms of solar radiation 300, 400, 500 and 600 W/m2 and water mass flow rates 0.00305 and 0.0083kg/s. In the first case, there was a problem because of the air gap inside the tube and surrounding the double pass water tube, so In the second stage, two different filling medium inside the evacuated tube was proposed to modify the preliminary model. The mediums cases include porous media (stainless steel wire mesh and Aluminum fiber metallic). The results show that maximum efficiency without porous media was 62.4% at 0.0083 kg/s and heat flux 600 W/m2, but after porous media applied, the efficiency reached 79.4% at 99.997% porosity of Aluminum fiber metallic and heat flux 600 W/m2 with same water mass flow.

Water aeration researches using fine air bubble generators

The paper presents experimental researches able to demonstrate that the aeration installations with mobile fine bubble generators are more efficient than the classic ones with fixed, fine bubble generators. The paper develops water aeration researches by introducing two types of fine air bubble generators: I. Fixed fine air bubble generators, which generate Ø <1 mm bubbles; II. Mobile fine air bubble generators that move in the volume of water subject to aeration. The theoretical and experimental results are presented for the two versions. According to experimental data, aeration with mobile FBG is more efficient in terms of oxygen transfer from atmospheric air to a stationary water mass.

Assessment of the quality of honey apiaries central agroecological zone of Yakutia

This article discusses the results of a study of the quality of honey from different apiaries of the Central agroecological zone of Yakutia. The data of organoleptic evaluation of honey samples are given. The mass fractions of water, mass fractions of recoding sugars, sucrose and insoluble substances in both samples comply with the standards. The diastase number in honey samples is higher than standard indicators, which with the above organoleptic and other physico-chemical indicators confirm the quality and high biological activity. Keywords: BEE COLONIES, APIARY, AGROECOLOGICAL ZONE, HONEY, HONEY PRODUCTIVITY, ORGANOLEPTIC INDICATORS, PHYSICOCHEMICAL INDICATORS, BIOLOGICAL ACTIVITY

The Levantine Intermediate Water in the western Mediterranean and its interactions with the Algerian Gyres: insights from 60 years of observation

The presence of two large scale cyclonic gyres in the Algerian basin influences the general and eddy circulation, but their effect on water mass transfer remain poorly characterized. Our study has confirmed the presence of these gyres using the first direct current measurements of the whole water column collected during the SOMBA-GE2014 cruise, specifically designed to investigate these gyres. Using cruise sections and a climatology from 60 years of in situ measurements, we have also shown the effect of these gyres on the distribution at intermediate depth of Levantine Intermediate Water (LIW) with warmer (~0.15 °C) and saltier (~0.02 g.kg−1) characteristics in the Algerian basin than in the Provençal basin. The Algerian gyres also impact horizontal density gradients with sinking of the isopycnals at the gyres’ centres. Temporal cross-correlation of LIW potential temperature referenced to the signal observed south of Sardinia reveal timescale of transit of 4 months to get to the centre of the Algerian basin. The LIW temperature and salinity trends over various periods are estimated to: +0.0017 ± 0.0014 °C.year−1 and +0.0017 ± 0.0003 year−1 respectively over the 1960–2017 period, and accelerating to +0.059 ± 0.072 °C.year−1 and +0.013 ± 0.006 year−1 over the 2013–2017 period.

Development of a Semi-analytical Dynamic Thrust Force Model

A moving water mass generates force which is exerted on its moving path. Cyclone generated storm surge or earthquake generated tsunami are specific examples of moving water mass the generates force along the coasts. In addition to human lives, these moving water masses cause severe damages to the coastal infrastructure due to tremendous force exerted on these structures. To assess the damage on these infrastructures, an essential parameter is the resultant force exerted on these structures. To evaluate the damages, there is hardly any quantitative method available to compute this force. In this paper we have developed a semi-analytical model, named as Dynamic Force Model (DFM), by using Variational Iteration Method to compute this force. As governing equations, we have used the Saint Venant equations which are basically 1D shallow water equations derived from the Navier-Stokes equations. The verified, calibrated and validated DFM is applied in Bangladesh coastal zone to compute dynamic thrust force due to tropical cyclone SIDR.

Swelling Effects on the Conductivity of Graphene/PSS/PAH Composites

Graphene/poly-(sodium-4-styrene sulfonate)(PSS)/poly-(allylamine hydrochloride) (PAH) composite is a frequently adopted system for fabricating polyelectrolyte multilayer films. Swelling is the bottleneck limiting its applications, and its effects on the conductivity is still controversial. Herein, we report successful swelling of a graphene/PSS/PAH composite in a vapor atmosphere, and the relation with the mass fraction of water is uncovered. The composite was prepared via a layer-by-layer assembly technique and systematically characterized. The results indicated that the average thickness for each bilayer was about 0.95 nm. The hardness and modulus were 2.5 ± 0.2 and 68 ± 5 GPa, respectively, and both were independent of thickness. The sheet resistance decreased slightly with the prolongation of immersion time, but was distinct from that of the water mass fraction. It reduced from 2.44 × 105 to 2.34 × 105 ohm/sq, and the change accelerated as the water mass fraction rose, especially when it was larger than 5%. This could be attributing to the lubrication effect of the water molecules, which sped up the migration of charged groups in the polyelectrolytes. Moreover, molecular dynamics simulations confirmed that a microphase separation occurred when the fraction reached an extreme value owing to the dominated interaction between PSS and PAH. These results provide support for the structural stability of this composite material and its applications in devices.