两广地区前、后汛期降水异常反位相现象及可能机理

利用1961—2018年中国地面气象台站2 400站中广东省和广西壮族自治区(两广地区)134站逐日降水资料、英国Hadley中心逐月海表温度资料、NCEP/NCAR逐月再分析资料,筛选了两广地区前汛期降水正(负)异常、后汛期降水负(正)异常的年份,即前、后汛期降水异常反位相年份。结果表明,近60 a来,两广地区前、后汛期降水反位相现象与热带西太平洋海温异常存在密切联系。前汛期期间,当热带西太平洋海温为负异常时,大气对该冷源的Rossby波响应引起西北太平洋反气旋环流异常,且水汽由热带西太平洋向两广地区输送并辐合,同时两广地区为水汽的湿平流区域、风场异常辐合区域,其上空受异常上升运动控制,这样的环流配置有利于两广前汛期期间降水正异常。热带西太平洋海温负异常可持续至后汛期期间,大气的Rossby波响应所致的西太平洋反气旋较前汛期偏西北,两广地区为水汽异常辐散区域,同时水汽干平流且风场异常辐散,受异常下沉运动控制,不利于两广地区降水的产生。反之亦然。     

适应数值模式垂直坐标的GPS掩星反演资料稀疏化方案

GPS掩星反演大气温湿资料具有高垂直分辨率、高精度、受云和降水影响小等优点,针对GRAPES同化预报系统,发展设计了一种既考虑预报模式高度-地形追随垂直坐标不均匀分层特点,又结合掩星反演资料特性的新适应性垂直稀疏化方案。通过个例试验和批量试验,探索了该适应性稀疏化方案对分析预报质量的影响。试验结果表明:选取合适的稀疏参数,新稀疏化方案的GPS掩星反演资料对背景场的调整更加有效,分析场质量更高;位势高度、比湿、温度和风场等预报场的均方根误差均更小;适应性稀疏化方案对改善台风路径预报具有积极作用。批量试验则进一步证实了适应性稀疏化方案对分析场质量有明显的改善作用。     

Time-Dependent Tsunami Source Following the 2018 Anak Krakatau Volcano Eruption Inferred from Nearby Tsunami Recordings

The eruption of the Anak Krakatau volcano,Indonesia,on 22 December 2018 induced a destructive tsunami(the Sunda Strait tsunami),which was recorded by four nearby tidal gauges.In this study we invert the tsunami records and recover the tsunami generation process.Two tsunami sources are obtained,a static one of instant initial water elevation and a time-dependent one accounting for the continuous evolution of water height.The time-dependent results are found to reproduce the tsunami recordings more satisfactorily.The complete tsunami generation process lasts approximately 9 min and features a two-stage evolution with similar intensity.Each stage lasts about 3.5 min and elevates a water volume of about 0.13 km3.The time,duration and volume of the volcano eruption in general agree with seismic records and geomorphological interpretations.We also test different sizes of the potential source region,which lead to different maximum wave height in the source area,but all the results of time-dependent tsunami sources show the robust feature of two stages of wave generation.Our results imply a time-dependent and complex process of tsunami generation during the volcano eruption.     

关于南海北部滨海断裂带的研究

南海北部的滨海断裂带是位于南澳岛之东粤东南滨海地区的一条北东东走向的构造带。由于其所处的构造位置而一直被地球科学工作者所关注,并从不同角度作了不少研究。在广泛收集有关断裂带的资料和研究成果的基础上,对前人关于断裂带存在的依据、断裂带发育的时代、断裂带的构造属性和第四纪活动情况的认识作了简要归纳,并就断裂带的分布、构造属性等作了初步分析。     

国内外防灾减灾科技应用的思考

我国是世界上自然灾害最严重的国家之一,依靠科技进步来提高全国防灾减灾的综合能力已成为防灾减灾工作的重要内容之一。介绍了国内外防灾减灾领域科技应用与建设的现状,讨论了我国在这方面存在的主要问题;总结了国内外防灾减灾领域科技支撑建设的经验与启示,提出了增强我国防灾减灾领域科技应用能力的措施及建议。     

深圳西涌滨海旅游区海滩裂流风险评估及特征分析

基于海滩地形动力学、遥感影像的风险预识别以及现场排查等方法,对西涌滨海旅游区海滩裂流风险进行了初步评估.评估结果表明:地形动力分析结果显示,西涌滨海旅游区泳场逐月平均沙滩类型大部分是沿岸沙坝和裂流沟槽交替的沙坝型(B),风险等级高;影像特征判断该沙滩属于沿岸沙坝和裂流沟槽交替的沙坝型(B)或者低潮位附近伴有冲流沙坝及裂...     

Rapid Urbanization Induced Extensive Forest Loss to Urban Land in the Guangdong-Hong Kong-Macao Greater Bay Area,China

China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot regions, the Guangdong-Hong KongMacao Greater Bay Area(GBA) has undergone a dramatic urban expansion. To better understand forest dynamics and protect forest ecosystem, revealing the processes, patterns and underlying drivers of forest loss is essential. This study focused on the spatiotemporal evolution and potential driving factors of forest loss in the GBA at regional and city level. The Landsat time-series images from 1987 to2017 were used to derive forest, and landscape metrics and geographic information system(GIS) were applied to implement further spatial analysis. The results showed that: 1) 14.86% of the total urban growth area of the GBA was obtained from the forest loss in1987–2017;meanwhile, the forest loss area of the GBA reached 4040.6 km2, of which 25.60%(1034.42 km2) was converted to urban land;2) the percentages of forest loss to urban land in Dongguan(19.14%), Guangzhou(18.35%) and Shenzhen(15.81%) were higher than those in other cities;3) the forest became increasingly fragmented from 1987–2007, and then the fragmentation decreased from2007 to 2017);4) the landscape responses to forest changes varied with the scale;and 5) some forest loss to urban regions moved from low-elevation and gentle-slope terrains to higher-elevation and steep-slope terrains over time, especially in Shenzhen and Hong Kong.Urbanization and industrialization greatly drove forest loss and fragmentation, and, notably, hillside urban land expansion may have contributed to hillside forest loss. The findings will help policy makers in maintaining the stability of forest ecosystems, and provide some new insights into forest management and conservation.     

关于黑潮延伸体海域水体的三维热结构时-空变化特征研究

基于西北太平洋Argo数据资料,利用参数化方法,从Argo温盐剖面数据中提取出一系列特征动力参数,定量分析黑潮延伸体海域水体的三维热结构的时-空变化特征、季节变化特征及其与地形和环流的关系.结果表明:黑潮延伸体海域水体的海表面温度存在着明显的冬春弱,夏秋强的季节变化特征,冬季平均海表面温度为15℃,夏季则达到了27℃;...     

鹤庆—剑川地区岩溶发育特征及其控制因素

滇中鹤庆—剑川地区碳酸盐岩岩溶极为发育,其空间展布广,以连续纯碳酸盐岩型岩溶层组类型为主,岩溶形态多样,包括溶蚀平原、溶丘谷地、溶丘洼地等类型.滇中鹤庆—剑川岩溶系统具有沿断裂走向展布的显著特点,同时沿断层、褶皱轴部和构造裂隙岩溶发育程度明显较大.结合区域地质构造背景,研究认为鹤庆—剑川地区岩溶系统的发育主要受控于物质...     

航空重力弱信号提取的卡尔曼滤波方法研究

航空重力测量以飞机为载体对重力场数据进行采集.由于气流、飞行状态及机体自身振动等因素的影响,航空重力测量原始数据含有大量的噪声,信噪比高达上万级分之一,因此从原始测量数据中获取弱小重力信号成为航空重力测量系统发展的一个技术难题.本文针对航空重力测量系统将通用卡尔曼滤波公式进行了适应性调整,建立了航空重力异常的数学模型,...