Hypoxia is increasingly reported off the Changjiang River Estuary with the confluence of multiple high volume nutrient sources. The Regional Ocean Modeling System coupled with a biological model was used to analyze the effect of different nutrient sources on the development of hypoxia off the Changjiang River Estuary. By comparing to observed data, our model suitably captured the regional dynamics of chlorophyll a, dissolved oxygen, and nutrient concentration. A series of sensitivity experiments were conducted to investigate the hypoxia response to the various nutrient sources, such as loading from the Changjiang River, Kuroshio and Taiwan Warm Current. Our model results indicated that nutrients from different sources significantly influenced the hypoxia off the Changjiang River Estuary, and it was mostly affected by nutrients sourced from the Kuroshio. The nutrients input from the Changjiang River had larger impacts on the hypoxia in the north of 30°N than that in the south of 30°N. The nutrients sourced from the Taiwan Strait had a least influence on the hypoxia off the Changjiang River Estuary. 相似文献
Sea ice growth and consolidation play a significant role in heat and momentum exchange between the atmosphere and the ocean. However, few in situ observations of sea ice kinematics have been reported owing to difficulties of deployment of buoys in the marginal ice zone (MIZ). To investigate the characteristics of sea ice kinematics from MIZ to packed ice zone (PIZ), eight drifting buoys designed by Taiyuan University of Technology were deployed in the open water at the ice edge of the Canadian Basin. Sea ice near the buoy constantly increased as the buoy drifted, and the kinematics of the buoy changed as the buoy was frozen into the ice. This process can be determined using sea ice concentration, sea skin temperature, and drift speed of buoy together. Sea ice concentration data showed that buoys entered the PIZ in mid-October as the ice grew and consolidated around the buoys, with high amplitude, high frequency buoy motions almost ceasing. Our results confirmed that good correlation coefficient in monthly scale between buoy drift and the wind only happened in the ice zone. The correlation coefficient between buoys and wind was below 0.3 while the buoys were in open water. As buoys entered the ice zone, the buoy speed was normally distributed at wind speeds above 6 m/s. The buoy drifted mainly to the right of the wind within 45° at wind speeds above 8 m/s. During further consolidation of the ice in MIZ, the direct forcing on the ice through winds will be lessened. The correlation coefficient value increased to 0.9 in November, and gradually decreased to 0.7 in April. 相似文献
The Dongfang1-1 gas field (DF1-1) in the Yinggehai Basin is currently the largest offshore self-developed gas field in China and is rich in oil and gas resources. The second member of the Pliocene Yinggehai Formation (YGHF) is the main gas-producing formation and is composed of various sedimentary types; however, a clear understanding of the sedimentary types and development patterns is lacking. Here, typical lithofacies, logging facies and seismic facies types and characteristics of the YGHF are identified based on high-precision 3D seismic data combined with drilling, logging, analysis and testing data. Based on 3D seismic interpretation and attribute analysis, the origin of high-amplitude reflections is clarified, and the main types and evolution characteristics of sedimentary facies are identified. Taking gas formation upper II (IIU) as an example, the plane distribution of the delta front and bottom current channel is determined; finally, a comprehensive sedimentary model of the YGHF second member is established. This second member is a shallowly buried “bright spot” gas reservoir with weak compaction. The velocity of sandstone is slightly lower than that of mudstone, and the reflection has medium amplitude when there is no gas. The velocity of sandstone decreases considerably after gas accumulation, resulting in an increase in the wave impedance difference and high-amplitude (bright spot) reflection between sandstone and mudstone; the range of high amplitudes is consistent with that of gas-bearing traps. The distribution of gas reservoirs is obviously controlled by dome-shaped diapir structural traps, and diapir faults are channels through which natural gas from underlying Miocene source rocks can enter traps. The study area is a delta front deposit developed on a shallow sea shelf. The lithologies of the reservoir are mainly composed of very fine sand and coarse silt, and a variety of sedimentary structural types reflect a shallow sea delta environment; upward thickening funnel type, strong toothed bell type and toothed funnel type logging facies are developed. In total, 4 stages of delta front sand bodies (corresponding to progradational reflection seismic facies) derived from the Red River and Blue River in Vietnam have developed in the second member of the YGHF; these sand bodies are dated to 1.5 Ma and correspond to four gas formations. During sedimentation, many bottom current channels (corresponding to channel fill seismic facies) formed, which interacted with the superposed progradational reflections. When the provenance supply was strong in the northwest, the area was dominated by a large set of delta front deposits. In the period of relative sea level rise, surface bottom currents parallel to the coastline were dominant, and undercutting erosion was obvious, forming multistage superimposed erosion troughs. Three large bottom current channels that developed in the late sedimentary period of gas formation IIU are the most typical. 相似文献
We introduced the Coupled Model Intercomparison Project Phase 6 (CMIP6) Ocean Model Intercomparison Project CORE2-forced (OMIP-1) experiment by using the First Institute of Oceanography Earth System Model version 2.0 (FIO-ESM v2.0), and comprehensively evaluated the simulation results. Unlike other OMIP models, FIO-ESM v2.0 includes a coupled ocean surface wave component model that takes into account non-breaking surface wave-induced vertical mixing in the ocean and effect of surface wave Stokes drift on air-sea momentum and heat fluxes in the climate system. A sub-layer sea surface temperature (SST) diurnal cycle parameterization was also employed to take into account effect of SST diurnal cycle on air-sea heat ?uxes to improve simulations of air-sea interactions. Evaluations show that mean values and long-term trends of significant wave height were adequately reproduced in the FIO-ESM v2.0 OMIP-1 simulations, and there is a reasonable fit between the SST diurnal cycle obtained from in situ observations and that parameterized by FIO-ESM v2.0. Evaluations of model drift, temperature, salinity, mixed layer depth, and the Atlantic Meridional Overturning Circulation show that the model performs well in the FIO-ESM v2.0 OMIP-1 simulation. However, the summer sea ice extent of the Arctic and Antarctic is underestimated. 相似文献
During the self-weight penetration process of the suction foundation on the dense sand seabed, due to the shallow penetration depth, the excess seepage seawater from the outside to the inside of the foundation may cause the negative pressure penetration process failure. Increasing the self-weight penetration depth has become an important problem for the safe construction of the suction foundation. The new suction anchor foundation has been proposed, and the self-weight penetration characteristics of the traditional suction foundation and the new suction anchor foundation are studied and compared through laboratory experiments and analysis. For the above two foundation types, by considering five foundation diameters and two bottom shapes, 20 models are tested with the same penetration energy. The effects of different foundation diameters on the penetration depth, the soil plug characteristics, and the surrounding sand layer are studied. The results show that the penetration depth of the new suction foundation is smaller than that of the traditional suction foundation. With the same penetration energy, the penetration depth of the suction foundation becomes shallower as the diameter increases. The smaller the diameter of the suction foundation, the more likely it is to be fully plugged, and the smaller the height of the soil plug will be. In the stage of self-weight penetration, the impact cavity appears around the foundation, which may affect the stability of the suction foundation.