As a new type of pollutant, microplastics widely exist in the marine environment and have attracted a lot of attention from the international community. In order to study the distribution of microplastics and the influence of ocean current, microplastic samples in seawater of the southern Indian Ocean were collected using a peristaltic pump equipped on-board and concentrated on site. Qualitative and quantitative analyses of microplastics were performed using a stereo-microscope and a micro-Fourier transform infrared spectroscope attenuated total reflection. The results showed that the average abundance of microplastics in seawater of the southern Indian Ocean was 2.3 ± 2.1 items/m³, which was consistent with that in other oceans. Polyethylene terephthalate (PET), polyethylene (PE), Rayon, polyamide (PA), and polyvinylidene chloride (PVDC) were the main polymers of microplastics in the southern Indian Ocean. The size range of all detected microplastics was 108.2–4703.0 µm. All microplastics had different colors, such as black, red, yellow, gray, blue, green, purple, and transparent. Fiber was the dominant shape of microplastics. The abundance distribution of microplastics fluctuated in the latitudinal direction. The abundance of microplastics from the present study area was higher in the coastal region of the South Africa continent and the Indian Ocean garbage patch, with an average abundance of 4.0 items/m³. The average abundance of microplastics was relatively high in the convergence area of the circulation, which revealed that the ocean current facilitated the agglomeration and transportation of microplastics.

Tropical cyclones (TCs), especially landfalling intense storms often pose serious threats to life and property in coastal areas. Although TC track forecast skill has been improved in the past decades, the progress of advancing the intensity forecast lags that of the track forecast. One possible limiting factor is the absence of ocean surface waves in forecast systems. To better represent the interaction of TC and underlying ocean, a regional atmosphere‐ocean‐wave coupled model is employed in this study. Twenty‐one TCs of a whole year in 2013 are retrospectively simulated through twin simulations, a Control and a Fully coupled run. Results show that TC intensity bias has been significantly reduced in the fully coupled simulation, in which five ocean surface wave related physical processes are considered, including wave modulation of momentum flux, sea spray effect on enthalpy flux, surface current and Stokes drift on air sea flux, non‐breaking wave induced mixing in the upper ocean as well as rain induced ocean surface cooling. A case study approach is used to diagnose the effect of individual surface wave related physical process on TC simulations. Similar to the effect of sea spray, surface waves also act as positive feedback on TC intensification by modulating air‐sea momentum flux. Absolute angular momentum budget analysis suggests that larger radial inflows and stronger updrafts near the eyewall promote the radial and vertical advections of absolute angular momentum and in turn lead to a stronger TC in Fully coupled simulation. The TC structure and size agree better with observations in Fully coupled simulation.

The global ocean has absorbed approximately 30% of anthropogenic CO₂ since the beginning of the industrial revolution. However, the spatiotemporal evolution of this important global carbon sink varies substantially on all timescales and has not yet been well evaluated. Here, based on a reconstructed observation‐based product of surface ocean pCO₂ and air–sea CO₂ flux (the MPI‐SOMFFN method), we investigated seasonal to decadal spatiotemporal variations of the ocean CO₂ sink during the past three decades using an adaptive data analysis method. Two predominant variations are modulated annual cycles and decadal fluctuations, which account for approximately 46% and 25% of all extracted components, respectively. Although the whole summer to non‐summer seasonal difference pattern is determined by the Southern Ocean, the non‐summer CO₂ sink at mid‐latitudes in both hemispheres shows an increasing trend (a total increase of approximately 1.0 PgC during the period 1982–2019), while it is relatively stable in summer. On decadal timescales for the global ocean carbon sink, unlike the weakening decade (1990–1999) and the reinvigoration decade (2000–2009) in which the Southern Ocean plays the dominant role, the reinforcement decade (2010–2019) is mainly the result from the weakening source effect in the equatorial Pacific Ocean. Our results suggest that except for the Southern Ocean's role in the global ocean carbon sink, the strengthening non‐summer's sink at mid‐latitudes in both hemispheres and the decadal or longer timescales of equatorial Pacific Ocean dynamics should be fully considered in understanding the oceanic carbon cycle on a global scale.

Marine disasters forecasting and prevention, resource sustainable development, ecological protection, global ocean governance are all new challenges under the climate change. It’s extremely urgent to develop a state-of-art and comprehensive toolkit for the coastal cities in managing those sustainable development challenges. Utilizing the marine scientific and technological advancements achieved since the implementation of the Ocean Decade, the Coastal city Ocean-bAsed Solution Toolkit for sustainable development (COAST, https://toolkit.dcc-occ.cn) was developed by UN Ocean Decade Collaborative Center on Ocean-climate Nexus and Coordination amongst Decade Implementing Partners in P. R. China (DCC-OCC) in a co-design framework, to provide showcase that addresses the challenges of marine disasters prevention and mitigation, maritime navigation safety, coastal ecosystem health, integrated coastal zone management, blue economy support, and ocean literacy. The toolkit builds on the significant innovations on data support, state-of-the-art models, digital twins technology and capacity building, to ensure the scientific basis for actionable knowledge. The toolkit is open and free for all the communities and link ocean science to end users in coastal cities worldwide for improved decision-making in a cost-effective manner.