粤港澳大湾区知识网络空间结构演化特征与影响机制

以2000—2018年国内外期刊数据库合作论文数据为基础,借助社会网络分析和空间结构指数法分析了粤港澳大湾区知识空间网络结构演化特征与影响因素,结果发现：1）知识网络格局由广州的“一家独大”逐渐演变为广州、深圳、香港“齐头并进”的发展态势。香港虽然处于知识网络的核心位置,但受行政壁垒的影响,主要与广州、深圳高等级的城市建立紧密的知识合作联系。2）粤港澳大湾区知识联系网络呈现“核心—边缘”结构,西部地区知识联系远低于东部地区,虽然研究期内湾区的知识网络的极化特征得到一定的缓解,但不均衡性仍然显著。3）湾区知识活动主体的自身需求是促进城市间知识合作的内在驱动力,知识环境和知识联系通道是区域知识合作网络外在推动力,在内生作用和外生作用的共同影响下,知识合作产出得以实现,粤港澳大湾区知识网络得以发展。     

东白令海三种经济鲽类捕捞群体结构与生长特性比较

对东白令海水域双线鲽(Lepidopsetta bilineata)、太平洋拟庸鲽(Hippoglosso-ides elassodon)和阿拉斯加鲽(Pleuronectes quadrituberculata)等三种经济鲽类的捕捞群体结构和生长特性进行比较。得出结论是:(1)捕捞群体结构复杂;(2)渐近体长和渐近体重较大、寿命长、K值小;(3)雌鱼比雄鱼个体大、生长快、寿命长;(4)三种鲽类的捕捞群体结构和生长特性有明显差异。     

Modeling the history of Lake of the Woods since 11,000 cal yr B.P. using GIS

Because of differential isostatic rebound, many lakes in Canada have continued to change their extent and depth since retreat of the Laurentide Ice Sheet. Using GIS techniques, the changing configuration and bathymetry of Lake of the Woods in Ontario, Manitoba, and Minnesota were reconstructed for 12 points in time, beginning at 11,000 cal yr B.P. (9.6 ¹⁴C ka B.P.), and were also projected 500 years into the future, based on the assumption that Lake of the Woods continued to have a positive hydrological budget throughout the Holocene. This modeling was done by first compiling a bathymetric database and merging that with subaerial data from the Shuttle Radar Topography Mission (SRTM). This DEM file was then adjusted by: (1) isobase data derived from Lake Agassiz beaches prior to 9000 cal yr B.P. (8.1 ¹⁴C ka B.P.) and (2) modeled isostatic rebound trend analysis after 9000 cal yr B.P. Just after the end of the Lake Agassiz phase of Lake of the Woods, only the northernmost part of the basin contained water. Differential rebound has resulted in increasing water depth. In the first 3000 years of independence from Lake Agassiz, the lake transgressed >50 km to the south, expanding its area from 858 to 2857 km², and more than doubling in volume. Continued differential rebound after 6000 cal yr B.P. (5.2 ¹⁴C ka B.P.) has further expanded the lake, although today it is deepening by only a few cm per century at the southern end. In addition, climate change in the Holocene probably played a role in lake level fluctuations. Based on our calculation of a modern hydrological budget for Lake of the Woods, reducing runoff and precipitation by 65% and increasing evaporation from the lake by 40% would end overflow and cause the level of the lake to fall below the outlets at Kenora. Because this climate change is comparable to that recorded during the mid-Holocene warming across the region, it is likely that the area covered by the lake at this time would have been less than that determined from differential isostatic rebound alone.     

Habitat associations of floating debris and marine birds in the North East Pacific Ocean at coarse and meso spatial scales

While many surface foraging seabirds ingest plastic, the spatial overlap of these far-ranging predators with debris aggregations at-sea is poorly understood. We surveyed concurrent distributions of marine birds and debris along a 4400 km cruise track within a debris accumulation area in the North East Pacific Ocean using line and strip transect methods. Analysis of debris and bird distributions revealed associations with oceanographic and weather variables at two spatial scales: daily surveys and hourly transects. Hourly bird abundance (densities; 0-9 birds km⁻²) was higher in lower wind and shallower water. Hourly debris abundance (densities; 0-15,222 pieces km⁻²) was higher in lower wind, higher sea-level atmospheric pressure and deeper water. These results suggest that debris and seabird abundance and community structure are influenced by similar environmental processes, but in opposing ways, with only three far-ranging seabird species (Black-footed Albatross, Cook’s Petrel and Red-tailed Tropicbird) overlapping with high debris concentrations over meso-scales.     

Estimation of size at first maturity in two South African coral species

The corals Acropora austera and Platygyra daedalea have been the subject of extensive reproductive and population genetic studies in the iSimangaliso Wetland Park (iSimangaliso), on the KwaZulu-Natal coast, eastern South Africa. Despite this, estimates of size at first maturity in these two species are lacking. This information could be used to provide a baseline to differentiate juveniles from adult sizes of corals, an important factor for assessing the condition of scleractinian communities in reefs. Here, we present the methods followed to provide such estimates for these two hard corals. Using generalised linear models and assuming knife-edge maturity (50% probability), it was estimated that A. austera from iSimangaliso matures at c. 15 cm mean colony diameter (MCD) (95% CI: 9.25–20.75 cm MCD) and P. daedalea matures at c. 7 cm MCD (95% CI: 4.55–8.39 cm MCD). These estimates were comparable to those for tropical species which is remarkable considering the high-latitude nature of the sampled reefs. It is expected that the findings from this study will assist in the assessment of reproduction, recruitment, survival and genetic variation in clonal organisms such as corals, and will provide a baseline to assess the effects of climate change on coral communities in the region.     

Contribution to the Global Warming Mitigation of Marshlands Conversion to Croplands in the Sanjiang Plain,Northeast China

Based on the estimation of greenhouse gases (GHG) emissions and carbon sequestration of the total conversion of marshlands (TMC), marshlands conversion to paddy fields (MCPFs) and marshlands conversion to uplands (MCULs), this study revealed the contribution to the global warming mitigation (CGWM) of paddy fields versus uplands converted from marshlands in the Sanjiang Plain (excluding the Muling‐Xingkai Plain on south of Wanda Mountain), Heilongjiang Province, northeast China. The results showed that the total area of MCPFs and MCULs was 504.23 × 10³ ha between 1982 and 2005. The CGWM per unit area was 45.53 t CO₂eq/ha for MCPFs and that was 23.95 t CO₂eq/ha for MCULs, with an obvious 47.40% reduction. The MCPFs and MCULs ecosystems acted as the carbon sink all of the year. As far as CGWM per unit area is concerned, MCPFs mitigated the greenhouse effect which was greater than MCULs. And it was effective that the implementation of the uplands transformed into paddy fields in Northeast China with regard to marshlands protection and croplands (including paddy fields and uplands) reclamation.     

澳门海洋空间资源利用研究——澳门的填海造地工程

澳门原系海中孤岛,由于利用了自然条件,进行填海造地工程,使孤岛相连,土地面积扩大,城市发展,交通改善,经济增长,成为利用海洋空间资源的典型地区。文章论述了澳门有利于填海工程实施的自然条件,海洋空间利用的发展过程,及填海造地工程的巨大作用和深远意义。     

Forecasting extreme events in the tropical Indian Ocean sector climate

Prospects for forecasting climate variability over the tropical Indian Ocean sector, specifically extreme positive events of the Indian Dipole Mode (IDM), with lead times of a season or more are investigated using the NASA Seasonal-to-Interannual Prediction Project (NSIPP) coupled-model system. The coupled system presents biases in its climatology over the Indian Ocean sector, which include (i) warmest sea-surface temperatures (SSTs) occurring in the central equatorial basin rather than on the eastside with the eastern (western) tropical SSTs up to 1 °C too cool (warm), (ii) a too northwest lying InterTropical Convergence Zonal over the ocean in boreal fall, (iii) a thermocline shallower (deeper) than observed west of Sumatra-Java (north of Madagascar), (iv) a delay of about a month in the onset (cessation) of the southwest (southeast) monsoon in the west (east) in boreal spring (fall). These biases affect the effectiveness of the SST-clouds-shortwave radiation negative feedback, the sensitivity of SST to wind-stress perturbations, and the character of equatorial coupled ocean-atmosphere modes. Despite these biases, ensemble hindcasts of the SST anomalies averaged over the eastern and western poles of the IDM for the decade 1993–2002, which included extreme positive events in 1994 and 1997/1998, are encouragingly good at 3-months lead. The onset of the 1997/1998-event is delayed by about a month, though the peak and decay are correctly timed. At 6-months lead-time, the forecast at the eastern pole deteriorates with either positive or negative false alarms generated each boreal fall. The forecast at the western pole remains good.     

Winkler地基梁在温度场中受简谐激励的主共振分析

研究W inkler地基梁在温度场中受简谐激励作用的主共振问题。应用弹性理论和Galerk in方法建立W inkler地基梁在温度场中受简谐激励作用的非线性动力方程。应用非线性振动的多尺度法,求得系统主共振的近似解。分析不同参数对主共振响应曲线的影响。     

Aerosol-Cloud-Precipitation Interactions in a Closed-cell and Non-homogenous MBL Stratocumulus Cloud

A closed-cell marine stratocumulus case during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) aircraft field campaign is selected to examine the heterogeneities of cloud and drizzle microphysical properties and the aerosol-cloud-precipitation interactions. The spatial and vertical variabilities of cloud and drizzle microphysics are found in two different sets of flight legs: Leg-1 and Leg-2, which are parallel and perpendicular to the cloud propagation, respectively. The cloud along Leg-2 was close to adiabatic, where cloud-droplet effective radius and liquid water content linearly increase from cloud base to cloud top with less drizzle. The cloud along Leg-1 was sub-adiabatic with lower cloud-droplet number concentration and larger cloud-droplet effective, but higher drizzle droplet number concentration, larger drizzle droplet median diameter and drizzle liquid water content. The heavier drizzle frequency and intensity on Leg-1 were enhanced by the collision-coalescence processes within cloud due to strong turbulence. The sub-cloud precipitation rate on Leg-1 was significantly higher than that along Leg-2. As a result, the sub-cloud accumulation mode aerosols and CCN on Leg-1 were depleted, but the coarse model aerosols increased. This further leads to a counter-intuitive phenomenon that the CCN is less than cloud-droplet number concentration for Leg-1. The average CCN loss rates are ?3.89 \begin{document}$\mathrm{c}{\mathrm{m}}^{-3}\;{\mathrm{h}}^{-1}$\end{document} and ?0.77 \begin{document}$\mathrm{c}{\mathrm{m}}^{-3}\;{\mathrm{h}}^{-1}$\end{document} on Leg-1 and Leg-2, respectively. The cloud and drizzle heterogeneities inside the same stratocumulus can significantly alter the sub-cloud aerosols and CCN budget. Hence it should be treated with caution in the aircraft assessment of aerosol-cloud-precipitation interactions.