A study of the chemical composition and transport of marine aerosols over the ocean near China

In this paper the authors cite the aerosol samples collected with a KA-200 Anderson cascade Impactor and a KB-120 sampler during the first cruise of the Kuroshio investigation operated by the People's Republic of China and Japan cooperative program, from July 23 to August 21, 1987. The concentration size distributions and composition of marine aerosols over the Kuroshio area are analyzed. Neutron activation analysis is used to determine the elemental composition of the aerosols. The authors also discuss some characteristics of marine aerosols relating to long-range transport of crustal and anthropogenic elements from the continent to the remote ocean. Analytical results indicate that elements Al, Fe, Sc and Sb over this area are obviously influenced by the continent of Asia, and the size distributions are changed after long-range transport. The concentration of large particles increase. The concentrations of the elements C1 and Na are closely related to ocean conditions; the source of the elements Cl and Na is mainly the ocean. Besides coal combustion, the ocean is also a very important source for the element Se. The amount of Se is related to the distribution of marine life.

Discrepancies in Simulated Ocean Net Surface Heat Fluxes over the North Atlantic

The change in ocean net surface heat flux plays an important role in the climate system.It is closely related to the ocean heat content change and ocean heat transport,particularly over the North Atlantic,where the ocean loses heat to the atmosphere,affecting the AMOC(Atlantic Meridional Overturning Circulation)variability and hence the global climate.However,the difference between simulated surface heat fluxes is still large due to poorly represented dynamical processes involving multiscale interactions in model simulations.In order to explain the discrepancy of the surface heat flux over the North Atlantic,datasets from nineteen AMIP6 and eight highresSST-present climate model simulations are analyzed and compared with the DEEPC(Diagnosing Earth's Energy Pathways in the Climate system)product.As an indirect check of the ocean surface heat flux,the oceanic heat transport inferred from the combination of the ocean surface heat flux,sea ice,and ocean heat content tendency is compared with the RAPID(Rapid Climate Change-Meridional Overturning Circulation and Heat flux array)observations at 26°N in the Atlantic.The AMIP6 simulations show lower inferred heat transport due to less heat loss to the atmosphere.The heat loss from the AMIP6 ensemble mean north of 26°N in the Atlantic is about10 W m–2 less than DEEPC,and the heat transport is about 0.30 PW(1 PW=1015 W)lower than RAPID and DEEPC.The model horizontal resolution effect on the discrepancy is also investigated.Results show that by increasing the resolution,both surface heat flux north of 26°N and heat transport at 26°N in the Atlantic can be improved.

The Role of Ocean Dynamics in the Cross-equatorial Energy Transport under a Thermal Forcing in the Southern Ocean

Under external heating forcing in the Southern Ocean,climate models project anomalous northward atmosphere heat transport(AHT)across the equator,accompanied by a southward shift of the intertropical convergence zone(ITCZ).Comparison between a fully coupled and a slab ocean model shows that the inclusion of active ocean dynamics tends to partition the cross-equatorial energy transport and significantly reduce the ITCZ shift response by a factor of 10,a finding which supports previous studies.To understand how ocean dynamics damps the ITCZ’s response to an imposed thermal heating in the Southern Ocean,we examine the ocean heat transport(OHT)and ocean circulation responses in a set of fully coupled experiments.Results show that both the Indo-Pacific and the Atlantic contribute to transport energy across the equator mainly through its Eulerian-mean component.However,different from previous studies that linked the changes in OHT to the changes in the wind-driven subtropical cells or the Atlantic meridional overturning circulation(AMOC),our results show that the cross-equatorial OHT anomaly is due to a broad clockwise overturning circulation anomaly below the subtropical cells(approximately bounded by the 5°C to 20°C isotherms and 50°S to 10°N).Further elimination of the wind-driven component,conducted by prescribing the climatological wind stress in the Southern Ocean heat perturbation experiments,leads to little change in OHT,suggesting that the OHT response is predominantly thermohaline-driven by air-sea thermal interactions.

Simulations and Projections of Winter Sea Ice in the Barents Sea by CMIP6 Climate Models

Dramatic changes in the sea ice characteristics in the Barents Sea have potential consequences for the weather and climate systems of mid-latitude continents,Arctic ecosystems,and fisheries,as well as Arctic maritime navigation.Simulations and projections of winter sea ice in the Barents Sea based on the latest 41 climate models from the Coupled Model Intercomparison Project Phase 6(CMIP6)are investigated in this study.Results show that most CMIP6 models overestimate winter sea ice in the Barents Sea and underestimate its decreasing trend.The discrepancy is mainly attributed to the simulation bias towards an overly weak ocean heat transport through the Barents Sea Opening and the underestimation of its increasing trend.The methods of observation-based model selection and emergent constraint were used to project future winter sea ice changes in the Barents Sea.Projections indicate that sea ice in the Barents Sea will continue to decline in a warming climate and that a winter ice-free Barents Sea will occur for the first time during 2042-2089 under the Shared Socioeconomic Pathway 585(SSP5-8.5).Even in the observation-based selected models,the sensitivity of winter sea ice in the Barents Sea to global warming is weaker than observed,indicating that a winter ice-free Barents Sea might occur earlier than projected by the CMIP6 simulations.

Modeling the circulation and sediment transport in the Beibu Gulf

Water circulation and sediment transport in the Beibu Gulf are important for its environmental protection and resource exploitation.By employing the Regional Ocean Modeling System（ROMS）,we studied the seasonal variation of circulation,sediment transport and long-term morphological evolution in the Beibu Gulf.The simulation results show that the circulation induced by tide and wind is cyclonic both in winter and summer in the gulf and that the wind-driven circulation is stronger in winter than that in summer.The sediment concentration is higher in the Qiongzhou Strait,west of the Hainan Island and the coast of Vietnam and the Leizhou Peninsula.The sediment is transported westwards in winter and eastwards in summer in the Qiongzhou Strait.The west entrance of the Qiongzhou Strait is dominated by westward transport all the year round.The sediment discharged by rivers is deposited near the river mouths.The simulated result demonstrates that the sediment transport is mainly controlled by tidal induced bottom resuspension in the Beibu Gulf.Four characteristics are summarized for the distribution patterns of erosion and deposition.（1） The erosion and deposition are insignificant in most area of the gulf.（2） Sediment deposition is more significant in the mouths of Qiongzhou Strait.（3） The erosion is observed in the seabed of Qiongzhou Strait.（4） Erosion and deposition occur alternatively in the west of Hainan Island.

The Asymmetric Connection of SST in the Tasman Sea with Respect to the Opposite Phases of ENSO in Austral Summer

This study uses linear regression and composite analyses to identify a pronounced asymmetric connection of sea surface temperature(SST)in the Tasman Sea with the two opposite phases of El Ni?o-Southern Oscillation(ENSO)during austral summer.In El Ni?o years,the SST anomalies(SSTAs)in the Tasman Sea exhibit a dipolar pattern with weak warmth in the northwest and modest cooling in the southeast,while during La Ni?a years the SSTAs exhibit a basin-scale warmth with greater amplitude.Investigations into the underlying mechanism suggest that this asymmetry arises from a mechanism related to oceanic heat transport,specifically the anomalous Ekman meridional heat transport induced by the zonal wind stress anomalies,rather than the surface heat fluxes on the air-sea interface.Further analysis reveals that the asymmetry of oceanic heat transport between El Ni?o and La Ni?a years is driven by the asymmetric atmospheric circulation over the Tasman Sea stimulated by the asymmetric diabatic heating in the tropical Pacific between the two opposite ENSO phases.

Impacts of atmospheric and oceanic factors on monthly and interannual variations of polynya in the East Siberian Sea and Chukchi Sea

As a key region of Northeast Passage,the polynya along the Siberian coast in the East Siberian and Chukchi Seas is important to local dynamic and thermodynamic processes,sea ice production and marine ecosystem.The detailed variations of polynya and the contributions of atmospheric and oceanic factors to the polynya have not been explored quantitatively.AMSR-E satellite data from January to April during the period 2003-2011 were used to study the impacts of wind stress and ocean heat transport on variations of polynya in the East Siberian Sea and Chukchi Sea.The study region was divided into six domains.Four sets of AMSR-E data with resolutions of 6.25 km and 12.5 km were compared based on two algorithms of sea ice concentration(referred to as 6.25 km-IC and 12.5 km-IC)and sea ice thickness(referred to as 6.25 km-h and 12.5 km-h).The monthly and yearly polynya areas in the four cases and six domains had remarkable differences.The two cases of 6.25 km-h and 12.5 km-h had larger areas of polynya than the other two cases of 6.25 km-IC and 12.5 km-IC.The difference in polynya area between the 6.25 km-h and 12.5 km-h cases was much smaller than the difference between the 6.25 km-IC and 12.5 km-IC cases.The study of atmospheric and oceanic mechanisms on polynya is influenced significantly by the sensitivity of polynya areas.In general,the impact of wind stress and ocean heat transport on the polynyas had noticeable monthly and interannual variations and was dependent on the locations of the polynyas.The alongshore and offshore wind had stronger correlations with the polynya area than ocean heat transport.Although the higher resolution(6.25 km)AMSR-E data are best for the study of atmospheric and oceanic impacts on polynya area,the coarse resolution(12.5 km)AMSR-E data based on sea ice thickness can also be used.Wind direction dominated the polynya area in the East Siberian Sea and wind speed dominated the polynya area in the Chukchi Sea.The variation in ocean heat transport was influenced mainly by variation in volume transport rather than variation in water temperature.

Simulated Spatiotemporal Response of Ocean Heat Transport to Freshwater Enhancement in North Atlantic and Associated Mechanisms

The Atlantic Meridional Overturning Circulation （AMOC） transports a large amount of heat to northern high latitudes, playing an important role in the global climate change. Investigation of the freshwater perturbation in North Atlantic （NA） has become one of the hot topics in the recent years. In this study, the mechanism and pathway of meridional ocean heat transport （OHT） under the enhanced freshwater input to the northern high latitudes in the Atlantic are investigated by an ocean-sea ice-atmosphere coupled model. The results show that the anomalous OHT in the freshwater experiment （FW） is dominated by the meridional circulation kinetic and ocean thermal processes. In the FW, OHT drops down during the period of weakened AMOC while the upper tropical ocean turns warmer due to the retained NA warm currents. Conversely, OHT recovers as the AMOC recovers, and the mechanism can be generalized as： 1） increased ocean heat content in the tropical Southern Ocean during the early integration provides the thermal condition for the recovery of OHT in NA; 2） the OttT from the Southern Ocean enters the NA through the equator along the deep Ekman layer; 3） in NA, the recovery of OHT appears mainly along the isopycnic layers of 24.70- 25.77 below the mixing layer. It is then transported into the mixing layer from the ＂outcropping points＂ in northern high latitudes, and finally released to the atmosphere by the ocean-atmosphere heat exchange.