ETAS Model Analysis on the Chang Island Earthquake Swarm in Shandong Province,China

Influenced by the layout of seismic network and the location of earthquakes,earthquake catalogs are often incomplete;such incompleteness of earthquake catalogue directly affects the analysis of sequence activity characteristics.In this paper,the GPU-acceleration-based g template matching method is used to scan the continuous waveforms of Chang Island earthquake swarm in Shandong Province from February 9 to August 20,2017.In total,15,286 earthquakes events were detected,which was more than 6 times compared with those in network catalogue and thus reduced the magnitude of completeness from 1.0 to 0.5.Based on the intergrated catalogue of earthquakes,the characteristics of Chang Island earthquake swarm were then analyzed using the Epidemic Type Aftershock Sequences(ETAS)model.The stochastic components in the ETAS model are used as a proxy for possible earthquake triggered by external forces(fluids).The results show that the proportion of earthquakes triggered by external forces of Chang Island swarm increases gradually(from 31.9%to 63.5%)and then decreases.The latter stage of swarm development is mainly affected by the self-excitation of earthquakes,suggesting that the fluids play an important role in the development of the Chang Island swarm.However,the triggering intensity of fluids to microseismicity is divergent in different periods,which may be related to the process of fluid permeation.

The Effective Ecological Factors and Vegetation at Koh Chang Island, Trat Province, Thailand

This study aims to characterize the tropical rain forest present in the Chang Island, Trat Province, Thailand, and to analyze the environmental factors to determine its composition and structure. Thirty one plots were sampled, plant cover was measured in 20 × 40 m2 plots, and the importance value index was calculated. A total of 78 species belonging to 32 families were identified.Twenty soil samples were analyzed, and cluster analysis was employed to classify the vegetation communities. Floristic and environmental data were evaluated and ordered using canonical correspondence analysis. The results showed that the vegetation communities could be divided into 4 types and were significantly (p Calophyllum thorelii Pierrecommunity (Type 2). The Dipterocarpus (Hopea pierrei Heim) community (Type 3) was more likely to occur in regions with moderate to high levels of TWI, but the result from cluster analysis showed that some of the plot samples from the Dipterocarpus community were separated by characteristic importance value index (IVI) values. There was also evidence that the area was impacted by an old disturbance created by a rubber plantation. This impact was referred to as a secondary succession community (Type 4).

Land Use-Related Changes in Soils of Hainan Island During the Past Half Century

During the past half century, the land utilization of Hainan Island has undergone a rapid development,but in the meanwhile, soil degradation occurs. Analysis on some basic data of the soil series collected frommore than 100 soil profiles at the end of the 1990s and beginning of this century, in combination with dataavailable, showed that soils there suffered significant decline in organic matter, experienced P and K deficiencywith soil K going on losing and undergone acidification with continuing trend. The current situation calls forstrategies to build up Hainan into an important province of sound ecology by restoring forests, to improvefood quality by implementing K supplement projects, to combat soil acidification by ameliorating the soils andgrowing leguminous crops and to ensure health of the people by developing dairy production and increasingthe daily Ca uptake by the people.

WISE EXPLOITATION OF NEWLY GROWING LAND RESOURCES——An Assessment on Land-use Change of Chongming Island Using GIS

Chongming Island, the third largest island in China and the largest alluvial island in the world, is situated in the north of Shanghai Municipality at the mouth of the Changjiang (Yangtze) River. Along the fertile and prosperous sea coast there are a total area of over 120×103ha, with a population of 735 0 00, accruing some 500ha of new tidal land resources come from silt, sand and mud carried by the Changjiang River every year, extending about 140m per year. This dynamic process of alluvial growth has run for some 1500 years. Mudflat on Chon gming Island at the mouth of the Changjiang River is a resting ground for migrat ory birds and host more than a hundred species, including rare cranes and geese. But the local people keep reclaiming the tidal land for economic development. O bviously, it is crucial to have a well-concerted plan for future exploitation. In this study, we attempted to investigate the status changes of land use and wi ld life habitats on Chongming Island in recent 10 years, and then analyzed diffe rent human activities and their effects on wild life habitats using satellite im age data (1990, 1997 and 2000) as well as field survey. Based on the analysis, t his study explored the relationships between island growth and land use/cover ch ange (LUCC), predicted what the habitat would be like in the future and tried to find more effective use of this new growing resource. At last, this study provi ded some preliminary management plans for Chongming Island that will coordinate the development of local economies and the conservation of wild life and their h abitats.

Assessing the vulnerability of changing coasts,Hainan Island,China

Knowledge of coastline changes and vulnerability is of great importance to local government departments that are responsible for the management and development of coastal zones.To study the nature of change and vulnerability along the coasts of the Hainan Island,we collected a large number of sediment samples through the last few years,and reconstructed the changes of the coastline by combining the data of sediment grain-size analysis and the nautical charts/TM RS imaginary.Contrary to being almost free from erosion（as expected from the findings that the coastlines are in a relatively stable state）,four major cities in Hainan（i.e.,Haikou,Wenchang,Sanya and Changjiang） turned out to be suffered from a moderate coastal vulnerability primarily because of the large populations that impose considerable pressure on the coastlines.Thus,the assessment methodology utilized in this study,including both anthropogenic and natural factors,serves as a useful tool to obtain a comprehensive understanding of coastline vulnerability for local government,in terms of coastal management and adaptation.

Impacts of land cover change on plant and bird species diversity in Hainan Island,China

Hainan Island, located at the southern end of China, has less than 0.4% of land area but contains 13% of plant and animal species in China. During the last four decades many primary forests have been converted to shrub land, grassland, and tree planation (e.g., eucalyptus forest). As a result, area of primary tropical forest has been reduced from 25.8% in the 1950s to 4% in the 1990s. To assess impacts of land conversion on plant and bird species diversity, a series of samples in primary forest and four types of converted lands were took. The land conversion had tremendously reduced both plant and bird species diversity. Specifically, plant species richness per site was 83.7 in primary forest, 28.3 in shrub land, 12.5 in grassland, 14.4 in eucalyptus forest, and 21.4 in Acacia forest. Bird species richness showed a similar trend: 22.0 in primary forest, 14.5 in shrub land, 2.5 in grassland, 4.9 in eucalyptus forest, and 9.0 in Acacia forest. The Shannon species diversity indices for plants in the five types of land cover were 3.69, 1.99, 0.97, 1.47 and 2.07, respectively. Similarly, the Shannon indices for bird species diversity were the highest in primary forest, and lowest in grassland, and intermediate in shrub land and eucalyptus forest.

Monitoring Intra-annual Spatiotemporal Changes in Urban Heat Islands in 1449 Cities in China Based on Remote Sensing

This study aimed to accurately study the intra-annual spatiotemporal variation in the surface urban heat island intensities(SUHIIs) in 1449 cities in China.First, China was divided into five environmental regions.Then, the SUHIIs were accurately calculated based on the modified definitions of the city extents and their corresponding nearby rural areas.Finally, we explored the spatiotemporal variation of the mean, maximum, and minimum values, and ranges of SUHIIs from several aspects.The results showed that larger annual mean daytime SUHIIs occurred in hot-humid South China and cold-humid northeastern China, and the smallest occurred in arid and semiarid west China.The seasonal order of the SUHIIs was summer > spring > autumn > winter in all the temperate regions except west China.The SUHIIs were obviously larger during the rainy season than the dry season in the tropical region.Nevertheless, significant differences were not observed between the two seasons within the rainy or dry periods.During the daytime, the maximum SUHIIs mostly occurred in summer in each region, while the minimum occurred in winter.A few cold island phenomena existed during the nighttime.The maximum SUHIIs were generally significantly positively correlated with the minimum SUHIIs during the daytime, nighttime and all-day in all environmental regions throughout the year and the four seasons.Moreover, significant correlation scarcely existed between the daytime and nighttime ranges of the SUHIIs.In addition, the daytime SUHIIs were also insignificantly correlated with the nighttime SUHIIs in half of the cases.

Study on ecosytem service function change of island based on remote sensing

Based on the interpretation of the remote sensing data presented by the resource satellite, this paper states the fact that the land-use area in Donghai Island, which is located in the south of Zhanjiang, Guangdong Province, had expanded by 576.71 hm2 in the 25 years from 1986 to 2010 because of human activities such as land reclamation; in the meantime, great changes in types of land cover on the island have occurred. The definite change in land use leads to the remarkable transition in its ecosystem service value. Therefore, by applying the Costanza method in this paper to quantificationally analyze the changes in its ecosystem services on this island; the Costanza method is a calculation technique that shows the service value per unit area of island. It is found that from 1986 to 2010, especially in the recent years, due to the rapid development in the petrifaction, steel and port industries, the areas of cultivated land, woodland, grassland and desert have decreased in different degrees, while the lands for residence, industry and traffic construction and the areas of water and wetlands have increased. Consequently, compared with the number of RMB 547.57x10^6 yuan per year in 1986, the ecosystem service value of Donghai Island was greatly reduced to RMB 493.94x10^6 yuan per year in 2010. As for the spatial distribution, it presents a feature that it is higher in the west and low in the east. The results manifest that it is of great significance to analyze the changes in the ecosystem service function on the basis of the service value of the island presented by the remote sensing data in a quantificational way, which will contribute to the promotion of ecological compensation.

Mean Sea Level Changes near Weizhou Island from 1969 to 2010

Tidal data from Weizhou, Zhapo, and Shanwei stations between 1969 and 2010 and from five gauging stations in the western Pacific Ocean provided by PSMSL, and the global mean sea level data recorded between December 1992 and December 2010 by TOPEX and Jason satellites were compiled and analyzed. The results show that the perennial mean sea level near Weizhou Island is 211.7 cm(relative to the water gauge zero), and the relative mean sea level rising rate is 2.2 mm yr-1 from 1969 to 2010, which is consistent with the relative mean sea level rising rate recorded at other gauging stations in the western Pacific regions and with the global mean sea level rising rate. The absolute mean sea level rising rate at Weizhou Island is 3.0 mm yr-1 from 1993 to 2010, also conforming with the global mean sea level rising rate(3.1±0.4 mm yr-1) during the same time period. The highest annual tide level at Weizhou Island has a rising rate of 4.6 mm yr-1 and shows a 20-year quasi-periodic variation from 1966 to 2010. The primary cause of the mean sea level rising is global warming.

末次冰期东海嵊山岛黄土粒度端元分析及其环境意义

【目的】东海岛屿晚更新世风尘黄土堆积是我国黄土在东部长三角及外延海域重要的拓展,深化这一区域风尘黄土沉积的物源特征和后期演化问题研究,对于认识晚更新世区域古环境变化尤为重要。【方法】在OSL测年和磁化率测试基础上,基于东海岛屿典型风尘黄土剖面(嵊山岛黄土)的粒度分析,开展了粒度组成的端元分析,探讨了其蕴含的古环境信息。【结果与结论】嵊山岛黄土沉积可提取出3个粒度端元(EM1~EM3),进一步分析发现EM1可能代表通过高空西风气流传输的远源黏粒组分,EM2可能代表以浮尘形式远距离悬浮搬运并随风力减弱而沉降堆积的细粉砂组分,EM3可能代表冬季风驱动下的近地表短距离搬运堆积的粗粉砂组分。粒度端元分析结果表明,高空西风输送的黏粒端元组分和远距离悬浮运移的浮尘端元组分可能是沉积剖面主要粉尘来源;综合年代学结果、百分频率磁化率和颗粒中值粒径等参数分析,认为东海嵊山岛黄土沉积过程在MIS3阶段先后经历暖湿—冷干—暖湿的旋回波动;并且,所记录的MIS3阶段气候波动以及MIS2阶段末次冰盛期和冰消期的古环境变化同深海氧同位素和古海平面变化趋势相对应,说明东海陆架区域该时期环境演变与全球性气候波动相协同。

中国人对西沙群岛历史认知与风力、潮流、海浪作用下的变迁研究

通过研究西沙群岛的历史认识和地理环境演变,强调了地理特征和稳定性的重要性,以及风力、潮流和海浪对其造成的影响。研究表明:1)中国人至迟在汉代对“岛”和“沙洲”就有了较为理性的认知,岛屿的形成具有悠久的历史,形成于4000年以上,地势相对较高,不易被海水淹没。相反,沙洲是相对年轻的地貌,其地势较低,容易受到自然因素的影响。2)风力、潮流和巨浪对西沙群岛地貌的变化有重要影响。风力和巨浪堆积沙洲,但同时也能导致其消失在海平面以下。潮流的周期性变化也对这些岛屿和沙洲的稳定性产生重要影响。这些变迁不仅是地貌的动态展现,也与海洋生物数量下降趋势密切相关。综合分析表明,岛和沙洲在地理特征和稳定性上存在明显差异。西沙群岛地貌的变迁是自然因素与人类活动交互作用的结果。文章有助于更好地了解西沙群岛的演化过程,以及保护和改善这一地区的生态环境方面的实际需求。

渤海湾海面变化

【研究目的】海面上升,是渤海湾泥质海岸带地区全新世海陆变化最主要的影响因素。通过重建海面变化历史,有助于预测今后的变化趋势。【研究方法】全球基于实际调查的建模研究,恢复了过去数万年来较高分辨率的海面变化历史、分析了导致这种变化的各类分量的贡献。我们通过地区性相对海面变化研究,着重对地区性和区域性分量或做了定量评估、或进行了半定量推理分析,并做了具体的案例研究。【研究结果】这些研究表明,距今10~7 ka时全球海面平均上升速率是~9 mm/a,同期渤海湾西岸相对海面平均上升速率是~5.6 mm/a。这一较快的上升造成了包括渤海湾在内全球沿海平原海岸线后退(以及渤海海盆-渤海湾可能的数道沿岸堤被淹没)。但是,7 ka至今,全球与冰融水等效海面(ice-equivalent sea level,ESL)的平均上升速率降至~0.64 mm/a;5 ka以来,甚至不再上升。7 ka以来,渤海湾西岸相对上升速率是~0.46 mm/a;5.5 ka之后,进一步减弱到~0.18 mm/a。上述全球和渤海湾西岸海面变化,显示出明显的“二段式”上升特点。以~7 ka为转折点:之前与之后的上升速率相差一个数量级。对于渤海湾西岸而言,叠加在这个长达~7000年的明显减速但仍缓慢上升背景上的,是均衡掀升分量与下沉(新构造下沉+沉积自压实下沉)分量的相互抵消。于是,全球性海面的缓慢上升、区域性均衡调整造成的掀升与局地下沉,这三者的复杂博弈,形成了长达~7000年的、经常受高潮水影响的渤海湾西岸障壁岛型贝壳堤-潟湖盐沼洼地周期性交替的沿海地形地貌格局。1870 CE至今的150余年间,全球海面平均上升速率~1.7 mm/a,近10余年来更加速至3.7 mm/a,渤海湾同时期I堤海岸线向海侧的前凸岸段平均蚀退1~3 km。【结论】我们推断1870CE以来的全球气温上升-海面上升与渤海湾同时期海岸线蚀退可能具因果关系。21世纪全球变暖及因此引起海面~6~8 mm/a上升的预测,是1870 CE至今全球加速升温-海面加速上升的必然延续。从地质学角度,这将导致渤海湾今后的“可容空间”逐步增加,为海岸线-潮间带蚀退、盐沼湿地退化提供条件,从而将可能导致持续了~7000年的贝壳堤障壁岛-潟湖盐沼地貌过程的终止,转入与7 ka之前相似的海面上升加速时的沿岸堤-沿海低地模式。以上基于全球研究及渤海湾实际调查结果做出的推断,将对渤海湾泥质海岸带的中长期发展产生影响。

海南岛土地覆盖变化对海风锋结构演变影响的数值模拟

本文利用WRF-Noah陆气耦合中尺度模式,针对海南岛一次典型的海风锋事件进行了高分辨率的数值模拟,研究了海南岛土地覆盖(下垫面)变化对海风锋结构演变的影响及其机制。结果表明,海南岛土地覆盖变化对海风锋的作用是通过多种地表和植被属性的综合影响决定的。森林化试验中动力和热力作用分别抑制和促进海风锋的发展,对海风锋的影响是两者共同作用的结果;反照率的减小引起净辐射的增大,从而使感热通量小幅增加,使低层大气增温而增加海陆温度梯度,这在一定程度上增强了海风驱动力,但地表粗糙度的增大减弱了海风风速,进一步减弱了海风锋传播距离和上升速度。然而,由于海南岛森林覆盖面积较大,导致森林化试验与控制试验中海风锋的整体差异较小。相比之下,荒漠化试验中热力和动力作用均有利于海风锋的发展;反照率的增大和叶面积指数的降低,改变了地表能量分配,造成潜热通量显著减小,感热通量先减少后增大,对低层大气的增温效应非常明显,从而加大了海陆温度梯度。另一方面,地表粗糙度显著减小,下垫面对海风的阻挡作用减弱,海风风速增大。因此,荒漠化试验海风锋传播距离、上升速度以及海风厚度都显著增大。

莲花洲港不同涵养区域底栖动物群落短期变化研究

为了解生态涵养区不同区域底栖动物随着时间的变化情况,2019年10月、2020年11月、2021年10月在东流水道莲花洲港对底栖动物群落结构进行了研究。结果显示:总体水平上底栖动物种类逐年增加;底栖动物密度、生物量、丰富度指数(D)、多样性指数(H′)、均匀度指数(J)均呈现逐年上升的趋势。从不同区域来看,透水框架区底栖动物物种类数增加,鱼巢排区物种种类数先降低后稳定,其他区域物种数呈现先降低后升高的趋势;鱼巢排区密度、透水框架区底栖动物密度和生物量,其他区域生物量均呈现逐年上升的趋势;鱼巢排区、其他区域底栖动物丰富度指数(D)、多样性指数(H′)、均匀度指数(J)均呈现逐年上升的趋势;透水框架区多样性指数(H′)、均匀度指数(J)呈现逐年上升的趋势,2021年丰富度指数(D)相对于2020年略微下降,但远大于2019年水平。研究结果表明,生态涵养区营造的水体环境促进了底栖动物的生存繁殖,且随着年份的增加,底栖动物种类、密度和生物量、多样性变化指数呈现逐渐上升的趋势。

1956—2020年海南岛极端降雨气候及旱雨季变化趋势分析

研究围绕国家气象信息中心提供的1956—2020年海南岛5个气象站点的日降雨数据,通过气候要素倾向率法、累计距平法和Mann-Kendall非参数检验法分析诊断其变化特征,并着重检验了旱季(12月—来年3月)与雨季(4月—11月)分界线,以及4月和11月的降雨年际变化。结果表明,海南岛近65年极端降雨量与极端降雨频次都呈现上升趋势,极端降雨事件主要集中在雨季并具有逐年连续性;旱季最长无有效降雨天数呈上升趋势,降雨量增加趋势极小,旱季干旱程度在逐年加剧。4月降雨量呈现上升趋势,11月降雨量呈现下降趋势,旱雨季均呈现前移趋势,即提前到来、提前结束的趋势。对比筛选极端降雨事件前后的4月和11月降雨量,极端降雨对旱雨季划分影响极小。此外,总体降雨量呈上升趋势且增加量集中在雨季。

台湾海峡西侧海湾-岛屿系统影响下的流场年季变化——以南日水道为例

台湾海峡地理位置独特,西侧海域海湾-岛屿系统普遍发育,显著影响了海域流场分布。同时,海峡西岸经济区的快速发展对区域海洋动力环境背景场及其变化的精细认识提出了更高的要求。福建莆田南日岛西侧南日水道是连通兴化湾与平海湾的主要水道,是区域海洋动力环境的“咽喉”所在,在区域海洋环境保护与科学开发利用中居于至关重要的位置。为了全面认识台湾海峡西侧海湾-岛屿系统影响下区域海洋动力环境背景场的年季变化,本研究利用布放在南日水道的座底观测系统获得的周年海流资料,结合同期气象风场资料,通过数据统计分析、调和分析、滤波处理和小波变化等手段,研究了南日水道内海流的季节变化规律和驱动余流的动力要素,初步探讨了热带气旋等对海洋动力演化过程的影响。研究结果表明,研究海域潮流为不正规半日浅海潮流,并具有明显的半月周期,涨潮流大于落潮流,涨潮流主方向为WNW向,落潮流主方向为SE—ESE向。旋转谱结果表明,研究海域以半日潮为主,逆时针能量强于顺时针,惯性周期无明显的谱峰。潮流强度的季节变化特征为冬季最强,秋季、春季次之,夏季最弱。夏、秋季的余流流速较其他季节明显偏大,表层余流有明显的季节特征,底层余流全年为北向流。观测点余流主要由风引起,二者有很好的相关性,但频率统计结果显示二者方向不一致,表明余流在地形的作用下发生了转向,其中潮致余流对表层余流贡献较小。小波能量图表明,双台风(热带气旋)期间风和余流均存在1 d及6 d左右的周期信号,二者密切相关。本研究成果对于区域海洋环保以及海域科学开发与应用具有重要的现实意义。

城市热屿的时空变化特征及其与绿地的相关性研究——以南京主城区为例

在全球气候变化的背景下,热岛效应成为城市面临的重要挑战之一,但针对热岛自身组成和分布的时空异质性研究还比较少。以南京主城区2017和2022年的热环境为例,将热岛细分为多个独立的热屿(heatislets),识别出不同的时空变化类型,并探索城市绿地与热屿变化的相关性。结果表明,破碎与融合是热屿时空变化的主要类型,其中破碎之后热屿的热岛强度会明显降低,而融合类型则正好相反。破碎或融合前后热屿的变化与其中绿地的变化有极显著的相关性。假设其他因素一致的情况下,绿地面积每增加1.00hm^(2),热屿面积会平均减少14.25hm^(2),热屿破碎后的数量会平均增加1.86个;绿地面积每减少1.00hm^(2),就有平均1.51个热屿融合在一起,热屿的面积也会平均增加3.89hm^(2)。根据不同热屿的特征进行针对性的绿地规划布局,能更加有效地降低热岛强度。研究结果有望为缓解城市热岛效应提供新的研究和实践思路。

基于MODIS时序数据的北京市植被物候时空变化特征分析

植被是生态环境变化的指示器,分析植被物候的时空变化特征及其影响因素对分析陆地生态系统的碳、水和能量平衡具有重要意义。该文利用MOD13Q1 EVI数据集,采用D-L拟合法和动态阈值法提取了北京市2001—2020年植被生长季开始期(start of season,SOS)、植被生长季长度(growing season length,GSL)和植被生长季结束期(end of season,EOS)。通过构建城乡梯度带,分析了北京市城乡区域植被物候的时空变化特征。利用回归分析和趋势分析方法探讨了植被物候参数对气温、降水、日照、风速等气候因子以及城市热岛强度和城市化影响因子的响应。研究表明:2001—2020年间北京市植被物候呈现出SOS提前、GSL延长和EOS推迟的趋势。林地和灌木的SOS比草地早,EOS较草地晚,说明木本植物生长季开始期早,结束期晚。通过分析气候因子与物候之间的关系发现气温、降水、日照和风速都对北京市植被物候有一定的影响,其中SOS对日照的变化最为敏感,EOS对风速的变化最为敏感。植被物候沿城区—郊区—农村方向呈现明显的梯度变化,城区SOS比农村平均提前12.2 d、EOS平均推迟18.9 d。城市夜晚热岛强度与SOS在城乡梯度带上具有显著相关性(p<0.01),SOS,GSL和EOS与人口密度、城市建成区面积、地均GDP均存在显著相关关系(p<0.01),说明城市化发展对北京市SOS提前、GSL延长和EOS推迟具有重要作用。

COVID-19大流行对南昌市热岛效应的影响评估

COVID-19疫情对城市环境产生了显著而广泛的影响。以南昌市为研究对象,运用劈窗算法,利用多时相遥感数据反演城市地表温度,由此对疫情不同阶段不同土地利用类型的热岛效应的时空分布特征进行了分析,从而揭示了COVID-19疫情防控不同时期城市热环境变化的规律。结果表明,与疫情之前同时期的情况对比,在2次封控管理期间,城市热岛效应分别下降了57%和49.3%,且这种下降幅度随着距离城市中心的增加而减小。此外,不同土地覆盖类型的热岛效应变化幅度存在差异。水体、森林、荒地和农田的热岛效应下降幅度相对较小,而城镇区域的热岛效应下降幅度较大。这些发现对深入理解疫情防控的不同阶段城市热环境的时空变化提供了重要的实证研究支持,也为优化城市规划和管理策略,减轻城市热岛效应,并为未来类似的突发事件提供参考。