In the Canadian Circumpolar Flaw Lead System Study, the physical and optical properties of first-year ice during the freezing season were observed at the Amundsen Gulf from November 24th, 2007 to January 26th, 2008. The results show that the thickness of sea ice during this period ranged from 27 cm to 108 cm, while the snow depth varied between 0 cm and 6 cm. The changes of temperature, salinity and density in the interior of sea ice are respectively: temperature within the sea ice rose monotonically along with the increasing of depth, reaching a maximum of −2.2℃ at the surface and a minimum of −22.4℃ at the bottom; the salinity ranged from 3.30 to 11.70 with a C-shaped pattern in its vertical section, which means that the salinity of upper surface and bottom layer is larger than that in the middle part; the average density of the sea ice was slightly larger, which is (0.91±0.03) g/cm³. With the special designing of artificial light source and in-situ instrumentation, an obvious two-peek structure at 490 nm and 589 nm was found in the spectral distribution of the transmitted radiation through the first-year ice. The two-peak structure weakens as the thickness of sea ice increases, indicating the spectrum dependence of the attenuation. In the visible band, the spectral absorbance of both bare ice and snow-covered ice reaches its minimum at 490 nm, and rises as the wavelength moves towards 443 nm or 683 nm. However, for snow-covered ice, the variation of absorption rate is little enough to present a spectral independence. In addition, the spectral distribution of the attenuation coefficient was U-shaped in the visible band, with a minimum of 1.7 m⁻¹ at 589 nm. The integral diffuse attenuation coefficient of the first-year ice in visible band was about 2.3 m⁻¹, which was slightly higher than 1.5 m⁻¹, the diffuse attenuation coefficient of multi-year floe ice. The difference of the optical properties between first-year ice in the Amundsen Gulf and multi-year ice in the north of Canada Basin is mainly attributed to various components of the sea ice inclusions caused by the input of terrestrial materials with different absorption and scattering properties.

The GPS radiosonde data obtained during the 6th to 9th Chinese National Arctic Research Expedition was used to analyze the spatial and temporal variation characteristics of boundary layer temperature inversions over the seasonal ice zone in Arctic. The results show that: (1) There were strong interannual and spatial changes in the temperature inversions. There were more strong inversions over the pack ice zone at high latitude. And the thickness of inversions and the temperature change through the inversions had a significant logarithmic relationship. (2) The main factors controlling inversion properties were various in different years. The differences in sea ice cover leaded to different characteristics of inversions. Surface melt, radiative cooling, multi-layer cloud and warm-air advection provided different degrees of contribution to inversions in different years. (3) There were different reasons over the open water and sea ice zone. Both surface melt and warm-air advection played a very important role in the formation of inversions in sea ice zone. However, radiative cooling was one of the main factors in the generation of inversions over the open water.

Based on tropical cyclone (TC) disaster data and the best-track database from Shanghai Typhoon Institute of China Meteorological Administration (CMA-STI) during 1984 to 2017, this study analyzed the spatial-temporal characteristics of TC disaster in China and their differences for the three prevailing tracks, along with the discussion of the overland duration and its potential risk. Main results of this study were summarized as follows: (1) There was a significant upward trend with direct TC-associated economic losses, while the proportion of losses to Gross Domestic Product (GDP) and the deaths showed a downward trend. (2) TC-associated economic losses accompanied with the three prevailing TC tracks showed a substantial difference. The recurving TCs tended to be less and lower impact, while westward and west-northward TCs appeared to be more and higher impact in China. Particularly, more frequent TCs with westward movement affected the Guangdong, Guangxi and Hainan provinces. TCs tending to west-northward tracks mainly caused a serious TC-associated disaster in Guangdong, Fujian, and Zhejiang provinces. (3) The average overland duration, as a potential index for TC-associated disaster, showed an upward trend. Note that the reasons on the changes of TC overland duration for the three prevailing tracks appeared to be different. The increased average overland duration for recurving TCs were likely to relate to the decreased in TC average overland translation speed. In contrast, the increased average overland duration of westward and west-northward moving TCs were possibly due to the increased average distance that TCs traveled over land.

The study of tidal changes is of great significance in marine engineering, marine mapping as well as marine transportation. Because nearly all tide gauges are located in the coastal waters, previous studies mainly focus on tidal changes in the shallow waters. In the deep sea, due to the lack of long-term high-frequency sea level observations, tidal changes are remained unclear. Based on the tide gauge observations and satellite altimeter data, non-stationary tidal harmonic analysis toolbox S_TIDE to extract the long-term trend of amplitudes of four major constituents in the South China Sea is first used in this paper. Results show that in most areas of the South China Sea, the amplitudes of four major constituents are stable and have no significant positive or negative trends. In minor areas of the South China Sea, the amplitudes of four major constituents have significant trends. The largest positive trends can reach 2.91 mm/a and the largest negative trends can reach 3.50 mm/a. The long-term trends of tidal amplitudes in this area may be related to the change of the surface expression of internal tides. The tides observed by satellite contain not only barotropic tides but also the surface expression of internal tides. The internal tides as well as their surface expression in the South China Sea are strongest in the world. The changes of ocean stratification can influence the generation, propagation and dissipation of internal tides as well as their surface expression and eventually induce the long-term trends of tidal amplitudes in the South China Sea.

Ommastrephes bartramii is an economically important species for Chinese squid jigging fleet. Understanding the spatio-temporal distribution on fishing ground is crucial to the sustainable utilization of fish resources. The study constructed BP (back propagation) neural network models with different scenarios to speculate the dynamics of O. bartramii abundance based on fishery data in the months of July to October during 2000 to 2015. The model with year, month, longitude, latitude, sea surface temperature (SST), and sea surface salinity (SSS) as independent variables, 8 neurons in hidden layers, had the smallest mean square error, and thus selected as optimal model. The results showed that the significant fluctuation in CPUE between years, the local abundance was low and scattered in July and October, whereas was high and concentrated at 41.5°−43.5°N, 155°−160°E in August and September. Environmental factors, including SST and SSS affect the spatio-temporal distribution of local abundance, and should be considered in stock assessment and management.

After the launch of China’s HY-2B altimeter in October 2018, NSOAS (National Satellite Ocean Application Service) conducted a HY-2B altimetry calibration experiment in Wanshan, Zhuhai. The experiment used the tide gauge along the coast to conduct the calibration experiment from November 3, 2018 to December 12, 2018, near the sub-satellite point of the HY-2B transit orbit 375 on Zhiwan Island. During the experiment period, HY-2B revisited the calibration point three times, and the results showed that the three-period HY-2B altimetry calibration bias were (3.06±3.48) cm, (2.85±1.03) cm, −7.41 cm; there was a certain drift in the calibration bias in the first three cycles, and subsequent calibration work was required to determine the cause of the drift.

The instabilities of longshore currents are the far infragravity band waves. The study of its propagation characteristics will help us to understand its influence on the evolution of coastal beach and the transport and migration of pollutants, fish eggs and other organisms. Based on the wavelet coherence spectrum, this paper analyzes the propagation characteristics of the unsteady motion under regular and random waves, and discusses the influence of the wave height, period and slope on it. The results show that the irregular wave is easier to induce the unsteady motion, and the positive or negative phase difference of the unsteady motion is about 30° in the case of irregular waves, which is similar to the incident angle of waves; with the increase of the incident wave height, nonlinear effects become stronger and the period range of the unsteady motion will be wider, that is to say, it is easier to induce the unsteady motion; the incident wave period has a little effect on the propagation; the steeper the slope is, the more likely it is to induce the instabilities of longshore currents.

Samples of Jumbo flying squid (Dosidicus gigas) were collected from Chinese squid jigging vessels in the high seas of Ecuador, Peru and Chile in the southeast Pacific Ocean in 2015 and 2017. The trace elements in the eye lenses of D. gigas were measured to study the geographical differences and their relationship with sea surface temperature. The results showed that elements such as Mg²⁵, Ni⁶⁰, Cu⁶³, Sr⁸⁸ and Ba¹³⁷ in the peripheral part of eye lenses of D. gigas in the high seas of Ecuador, Peru and Chile were significant difference, while there were no significant differences between each two sea areas in the elements of Na²³, Al²⁷, Si²⁹, P³¹, Ca⁴³, Mn⁵⁵, Zn⁶⁶ and Pb. Except for Sr⁸⁸, Ba¹³⁷, Fe⁵⁷ and Ni⁶⁰, which showed significantly linear negative correlations with SST (p<0.05), there were no significant correlations with SST in the other elements (p>0.05). Sr⁸⁸, Ba¹³⁷, Fe⁵⁷ and Ni⁶⁰ could be regarded as indicator elements of the ambient temperature of D. gigas, and Ba¹³⁷ could also be regarded as indicator element of the water depth and upwelling. Consequently, trace elements in eye lenses could be used to reconstruct the habitat environment of cephalopod.

Trophic level among main organisms in costal water of Lüsi fishing ground in summer, 2018, were analyzed in this study by stable isotope method. Using IsoSource model, we calculated potential carbon source contribution of the phytoplankton, POM and SOM of consumers, and then compared the former and latter TLs variation of main organisms by overlapping potential carbon source influence. Results showed that phytoplankton and SOM were main potential carbon source of main organisms in costal water of Lüsi fishing ground in summer. Two trophic level spectrums were constructed by overlapping three potential carbon sources and a single species as the baseline organisms, respectively. The trophic level of the right trophic level spectrum ranged from 1.74 to 3.92, which was averagely 0.19 lower than that of the left trophic level spectrum. Although the overall trend was unchanged, the trophic positions of some fish and most shrimps were changed in two spectrums. The baseline organisms in the right trophic level spectrum changed with the different stacking ratio of potential carbon sources, which could reflect the trophic level more effectively and was more suitable for organisms at low trophic levels, such as shrimp and crabs. However, this had little impact on fish in the position of middle and advanced consumers.

Online monitoring of pollutants exporting into coastal waters is one of the key technique to realize marine pollution control and coordination of monitoring and management. In this study, based on salinity and fluorescence dissolved organic matter (FDOM) sensor data between 2014−2018 from a multi-parameter buoy deployed in Jiulong River Estuary, a rapid inversion model of chemical oxygen demand (COD) was established. Daily river end member COD concentrations were then extrapolated by effective concentration method. Combined with daily runoff data, daily estuarine export fluxes of COD between 2014 and 2017 were estimated. The factors controlling the flux variations were quantified by flux decomposition model. The results indicated: (1) The average concentration deviation of the inversion was (10.4±8.8)%, indicating the good reliability and stability of inversion model. (2) On seasonal scale, COD concentration in dry season of 2016 was lower than the other dry seasons, which was regulated by 2015−2016 super El Niño events. However, the sharp increase of runoff still significantly increased the COD export flux. (3) On annual scale, the COD export flux in 2016 from the Jiulong River 4.4 ×10⁴ t/a was significantly higher than the other three years (3.0−3.2)×10⁴ t/a. The abnormal precipitation in 2016 caused by 2015−2016 El Niño event was the major reason for such yearly variation. This study highlighted the application of online FDOM sensor system for high frequency monitoring of COD export. This would help to achieve long-term continuous high-frequency monitoring of land-based pollutants and their fluxes into the sea and their regulatory factors. This would provide important technical support for marine ecological environmental protection and management.