Description: We characterise the representation of the Southern Ocean water mass structure and sea ice within a suite of 15 global ocean-ice models run with the Coordinated Ocean-ice Reference Experiment Phase II (CORE-II) protocol. The main focus is the representation of the present (1988-2007) mode and intermediate waters, thus framing an analysis of winter and summer mixed layer depths; temperature, salinity, and potential vorticity structure; and temporal variability of sea ice distributions. We also consider the interannual variability over the same 20 year period. Comparisons are made between models as well as to observation-based analyses where available. The CORE-II models exhibit several biases relative to Southern Ocean observations, including an underestimation of the model mean mixed layer depths of mode and intermediate water masses in March (associated with greater ocean surface heat gain), and an overestimation in September (associated with greater high latitude ocean heat loss and a more northward winter sea-ice extent). In addition, the models have cold and fresh/warm and salty water column biases centred near 50 degrees S. Over the 1933-2007 period, the CORE-II models consistently simulate spatially variable trends in sea-ice concentration, surface freshwater fluxes, mixed layer depths, and 200-700 in ocean heat content. In particular, sea-ice coverage around most of the Antarctic continental shelf is reduced, leading to a cooling and freshening of the near surface waters. The shoaling of the mixed layer is associated with increased surface buoyancy gain, except in the Pacific where sea ice is also influential. The models are in disagreement, despite the common CORE-II atmospheric state, in their spatial pattern of the 20-year trends in the mixed layer depth and sea-ice

Description: Highlights: • Inter-annual to decadal variability in AMOC from CORE-II simulations is presented. • AMOC variability shows three stages, with maximum transports in mid- to late-1990s. • North Atlantic temporal variability features are in good agreement among simulations. • Such agreements suggest variability is dictated by the atmospheric data sets. • Simulations differ in spatial structures of variability due to ocean dynamics. Simulated inter-annual to decadal variability and trends in the North Atlantic for the 1958–2007 period from twenty global ocean – sea-ice coupled models are presented. These simulations are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The study is Part II of our companion paper (Danabasoglu et al., 2014) which documented the mean states in the North Atlantic from the same models. A major focus of the present study is the representation of Atlantic meridional overturning circulation (AMOC) variability in the participating models. Relationships between AMOC variability and those of some other related variables, such as subpolar mixed layer depths, the North Atlantic Oscillation (NAO), and the Labrador Sea upper-ocean hydrographic properties, are also investigated. In general, AMOC variability shows three distinct stages. During the first stage that lasts until the mid- to late-1970s, AMOC is relatively steady, remaining lower than its long-term (1958–2007) mean. Thereafter, AMOC intensifies with maximum transports achieved in the mid- to late-1990s. This enhancement is then followed by a weakening trend until the end of our integration period. This sequence of low frequency AMOC variability is consistent with previous studies. Regarding strengthening of AMOC between about the mid-1970s and the mid-1990s, our results support a previously identified variability mechanism where AMOC intensification is connected to increased deep water formation in the subpolar North Atlantic, driven by NAO-related surface fluxes. The simulations tend to show general agreement in their temporal representations of, for example, AMOC, sea surface temperature (SST), and subpolar mixed layer depth variabilities. In particular, the observed variability of the North Atlantic SSTs is captured well by all models. These findings indicate that simulated variability and trends are primarily dictated by the atmospheric datasets which include the influence of ocean dynamics from nature superimposed onto anthropogenic effects. Despite these general agreements, there are many differences among the model solutions, particularly in the spatial structures of variability patterns. For example, the location of the maximum AMOC variability differs among the models between Northern and Southern Hemispheres.

Description: Highlights: • Mean circulation patterns are assessed and Kuroshio transport is underestimated. • Water mass distribution is compared and analyzed within COREII models. • Main biases of deep MLDs result from the inaccurate Kuroshio separation. • Reasonable modeled tropical dynamics but a discrepancy from the surface wind. Abstract: We evaluate the mean circulation patterns, water mass distributions, and tropical dynamics of the North and Equatorial Pacific Ocean based on a suite of global ocean-sea ice simulations driven by the CORE-II atmospheric forcing from 1963-2007. The first three moments (mean, standard deviation and skewness) of sea surface height and surface temperature variability are assessed against observations. Large discrepancies are found in the variance and skewness of sea surface height and in the skewness of sea surface temperature. Comparing with the observation, most models underestimate the Kuroshio transport in the Asian Marginal seas due to the missing influence of the unresolved western boundary current and meso-scale eddies. In terms of the Mixed Layer Depths (MLDs) in the North Pacific, the two observed maxima associated with Subtropical Mode Water and Central Mode Water formation coalesce into a large pool of deep MLDs in all participating models, but another local maximum associated with the formation of Eastern Subtropical Mode Water can be found in all models with different magnitudes. The main model bias of deep MLDs results from excessive Subtropical Mode Water formation due to inaccurate representation of the Kuroshio separation and of the associated excessively warm and salty Kuroshio water. Further water mass analysis shows that the North Pacific Intermediate Water can penetrate southward in most models, but its distribution greatly varies among models depending not only on grid resolution and vertical coordinate but also on the model dynamics. All simulations show overall similar large scale tropical current system, but with differences in the structures of the Equatorial Undercurrent. We also confirm the key role of the meridional gradient of the wind stress curl in driving the equatorial transport, leading to a generally weak North Equatorial Counter Current in all models due to inaccurate CORE-II equatorial wind fields. Most models show a larger interior transport of Pacific subtropical cells than the observation due to the overestimated transport in the Northern Hemisphere likely resulting from the deep pycnocline

Description: [1]  Based on the in situ data and ADCP observation in fall, it is found that a northeastward current at inter-middle level flows on the Northern South China Sea (NSCS) continental shelf. This current flows almost along the isobaths, and it deflects from the isobaths veering toward deep water when flowing over the Dongsha Islands. Geographic currents derived from the climatologic hydrography data (WOA01) and absolute dynamic topography (ADT) data confirm the deflection of the northeastward current on NSCS continent. A fine resolution regional ocean model which can well reproduce the large scale circulation in the NSCS is used to analyze the dynamic about the deflection. The vorticity term balances shows that JEBAR (Joint Effect of Baroclinicity and Relief) drives the water column to depart from the isobaths. To the east of the Dongsha Islands, the isopycnal is almost orthogonal to the isobaths. The joint effect of the topographic and the baroclinic effect supplies negative vorticity and drives the water column to deflect from the isobaths and veer to deeper water. Momentum analysis along the stream line shows that, when the sea water flows around the Dongsha islands, the pressure gradient along the isobath pushes the sea water to accelerate, and then the Coriolis force orthogonal to the isobath increases and overcomes the corresponding pressure gradient, which drives the water deflected from the isobath toward the deep sea.

Description: Correct representations of root functioning, such as root water uptake and hydraulic redistribution, are critically important for modeling the responses of vegetation to droughts and seasonal changes in soil moisture content. However, these processes are poorly represented in global land surface models. In this study, we incorporated two root functions: a root water uptake function which assumes root water uptake efficiency varies with rooting depth, and a hydraulic redistribution function into a global land surface model, CABLE. The water uptake function developed by Lai and Katul (2000) was also compared with the default one (see Wang et al., 2010) that assumes that efficiency of water uptake per unit root length is constant. Using eddy flux measurements of CO2 and water vapor fluxes at three sites experiencing different patterns of seasonal changes in soil water content, we showed that the two root functions significantly improved the agreement between the simulated fluxes of net ecosystem exchange and latent heat flux and soil moisture dynamics with those observed during the dry season while having little impact on the model simulation during the wet seasons at all three sites. Sensitivity analysis showed that varying several model parameters influencing soil water dynamics in CABLE did not significantly affect the model's performance. We conclude that these root functions represent a valuable improvement for land surface modeling and should be implemented into CABLE and other land surface models for studying carbon and water dynamics where rainfall varies seasonally or interannually.

Description: Highlights • The crustal thickness of the Zhongsha Block ranging from ~6 to ~25 km. • Rapid transition from the Zhongsha Block to the adjacent oceanic basins was revealed. • Different oceanic structures were observed in the adjacent oceanic basins. • The pre-rift lithospheric configuration may affect the process of rifting and seafloor spreading. Abstract Continental rifting, break-up, and onset of seafloor spreading are inherently controlled by the segmentation and structure of the continental domain suffering from extension. Today, the Zhongsha Atoll (ZS) is wedged between the Northwest Sub-basin (NWSB) and the Southwest Sub-basin (SWSB), two oceanic abyssal basins of the South China Sea (SCS). The nature of the crust and the structure of the transition from continental to oceanic domain are key to revealing the processes and dynamics during the rifting and break-up of the Zhongsha block. In this paper, we present a P-wave velocity model obtained from both forward modeling and tomographic inversion of wide-angle seismic line OBS2017-2. The results support the continental nature of the Zhongsha Block with a thickness of up to ~25 km. However, the transition from the thick continental domain of the ZS into both adjacent abyssal basins shows clear differences. To the north, a ~120 km wide domain of extended continental crust was observed. Farther north, the NWSB is characterized as a narrow basin with typical oceanic crust. The transitional domain between the continental and oceanic crust shows a ~30–40 km wide region with a high-velocity lower crust reflecting excessive magmatism. In contrast, the SWSB is characterized by a sharp transition from the thick continental crust of the ZS to thin oceanic crust which is probably underlain by serpentinized mantle. The strong rheological properties of the pre-rift crust in the western part of the SCS margin may be the reason that rifting concentrated on narrow rifts and thinning focused on necking domains, while the ZS avoided any intense extension. The configuration of rigid blocks thereafter affected the break-up position and the style of oceanic crust.

Description: A total of 1502 samples, including feces of sheep (793) and cattle (348), pasture soil (118), dung compost (147) and barn soil (96), were examined between October 2012 and August 2014 to discover potential strains of nematophagous fungi for the biological control of livestock-parasitic nematodes. These samples were collected from 87 sites located in 48 counties of 20 provinces (autonomous regions/municipalities) of China. Fungi were identified down to a species level. Four hundred and seventy-seven isolates, which were distributed in 8 genera and 28 taxa, were identified as nematophagous fungi. Nematode-trapping fungi included 17 species and one unidentified species of Arthrobotrys , two of Dactylella , Drechslerella dactyloides , and Duddingtonia flagrans . Five identified species and two unidentified species of endoparasitic fungi were isolated. The predominant species from all regions were Arthrobotrys oligospora , followed by Arthrobotrys musiformis , Arthrobotrys ( Monacrosporium ) thaumasiun , and Arthrobotrys ( Monacrosporium ) microscaphoides . Species with adhesive networks were the most frequently isolated. Among the endoparasitic fungi, Podocrella harposporifera ( Harposporium anguillulae ) was the most common species, followed by Harposporium lilliputanum and Harposporium arcuatum . Based on Shannon diversity index, the diversity levels of nematophagous fungi were relatively higher in samples associated with cattle, barn soil, and subtropical monsoon climate zone. Three species isolated from this study, namely, Duddingtonia flagrans , Arthrobotrys salina ( Monacrosporium salinum ), and Arthrobotrys oligospora var. sarmatica , are newly recorded in China, and 20 species (including one unidentified species) are newly recorded in sheep and cattle barn soils worldwide.

Description: Condensate oil is a kind of light crude oil with API gravity higher than 50 degrees. The increasing production of condensate oil due to shale gas/natural gas booming has economically motivate refiners to add this valuable and abundant crude source into their feedstock. Many refineries, however, were originally built to process heavier crudes, whose design must be retrofitted to enable the processing of the changed feedstock. In this paper, the conceptual retrofit design of crude distillation units for processing condensate oil has been studied. Four retrofit designs are proposed and simulated including facilities of preflash column, atmospheric distillation unit, and vacuum distillation unit. All retrofit designs are comprehensively evaluated by steady-state modeling for feasibility check, energy consumption analysis for operating cost evaluation, and retrofit cost evaluation. With the help of Aspen Plus, Aspen Energy Analyzer, and Aspen Capital Cost Estimator, the developed methodology provides a quantitative technology support to identify the optimal retrofit design. A comparison of the results shows that the retrofit design with preflash columns in sequence potentially could be the most economical case.

Description: A cadmium–thiocyanate complex, poly[(1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane-κ 4 N )octakis-μ 2 -thiocyanato-κ 8 N : S ;κ 8 S : N -tricadmium(II)], [Cd 3 (C 8 H 14 N 3 ) 2 (NCS) 8 ] n , was synthesized by the reaction of 1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride, cadmium nitrate tetrahydrate and potassium thiocyanide in aqueous solution. In the crystal structure, there are two independent types of Cd II cation (one on a centre of inversion and one in a general position) and both are in distorted octahedral coordination environments, coordinated by N and S atoms from different ligands. Neighbouring Cd II cations are linked together by thiocyanate bridges to form a two-dimensional network. Hydrogen-bonding interactions are involved in the formation of a three-dimensional supramolecular network.

Description: The separation of liquid-gas flows is essential for many industrial processes. Computational fluid dynamics method that contains Algebraic Slip Mixture model and Reynolds Stress model is firstly adopted to analyze the impact of number of inlets, column-diameter ratio on the degassing performance of hydrocyclone. For separating the bubbles that are 5-50µm in size, the structures with 1-6 inlets and seven different column-diameter ratios (2.0-5.0) are simulated. The results show that multiport designs are more suitable for liquid-gas separation, particularly separation of small bubbles. However, as the number of inlets increases, the growth trend of separation efficiency becomes slow. In addition, the structure with H c =3.9·D n obtains the optimal separation performance. Moreover, a longer column section is beneficial to small bubbles, but results in a greater loss of fluid energy.