东亚沙尘区域时空变化特征分析     

包春玲  咏梅  金额尔德木吐  包玉龙  图布新巴雅尔  包玉海 《地理研究》2021,40(11):3002-3015

沙尘天气是东亚地区常见的灾害性天气之一,强沙尘天气的发生不仅导致建筑物倒塌、人畜伤亡、植被破坏,还会导致火灾、空气污染等环境问题,对人体健康、社会经济活动及其全球沙尘循环产生重要影响。然而从东亚地区沙尘天气在长时间序列区域特征角度上系统分析的研究较少。基于此,本文利用1981—2019年东亚地区697个地面气象站点沙尘数据,分析了其区域时空分布特征。结果表明：空间上,东亚沙尘天气集中在位于内陆干旱区的蒙古国和中国西北地区,其中弱沙尘天气集中在中国北方地区,而强沙尘天气则集中在蒙古国。月变化上,东亚沙尘天气集中在春季（3—5月份）,在相对低纬度的中国青藏高原北麓沙尘天气3月份最多,位于中纬度的中国北方大部分地区4月份最多,而较高纬度的哈萨克斯坦东部和蒙古国5月份最多。年际变化上,40a间东亚沙尘呈减少趋势,尤其是在2000年之后多项生态工程的有效实施下中国北方大部分区域沙尘天气显著减少,但近几年内蒙古中西部地区强沙尘天气呈增长趋势;在生态环境较脆弱的蒙古国和塔克拉玛干沙漠等区域弱沙尘天气和强沙尘天气均呈增长趋势。本研究对准确地掌握东亚沙尘分布特征和防范沙尘灾害具有重要意义。  相似文献   

2000—2019年秦岭南北实际蒸散发时空变化特征   总被引：1，自引：0，他引：1  

李双双  张玉凤  张立伟  王婷  延军平 《地理科学进展》2021,40(11):1900-1910

基于遥感数据全面认识复杂地形单元实际蒸散发时空规律,对区域可持续水资源管理具有重要的意义。论文基于MODIS实际蒸散发(ET)数据,对2000—2019年秦岭南北ET时空变化特征进行分析,探究不同分区ET对植被变化的响应关系,进而识别ET趋势和年代变化的高相关海气环流因素。结果表明：① 在变化趋势上,以1000 m等高线为界,即秦岭地区北亚热带和山地暖温带的分界线,低海拔河谷地带为ET显著增加区,山地高海拔地区为ET下降区;② 除城市、乡镇周边地区,研究期间秦岭南北下垫面相对稳定,转为生态用地的活跃区主要分布在山地1000 m过渡带,其是ET与NDVI变化显著相关区,而1000 m以上高海拔地区两者相关性较低;③ ENSO、青藏高原北部气压异常,与秦岭山地、汉江谷地ET的趋势变化和年代波动显著相关,而西太平洋副热带高压与ET的趋势显著相关,与年代波动特征相关较弱。即发生中部型厄尔尼诺事件时,西太平洋副热带高压偏强,对流层低层形成异常反气旋,导致中国东部雨带北移,秦岭山地和汉江谷地降水偏少,气温偏高,ET往往偏大。研究结果启示：秦岭南北科学适应气候变化时,应关注秦岭山地、汉江谷地ET变化显著相关的环流信号;应深刻理解秦岭高海拔地区蒸散发下降趋势对区域水资源管理的影响。  相似文献   

Method for UAV-based 3D topography reconstruction of tidal creeks     

ZHANG Xuhui  LI Huan  GONG Zheng  ZHOU Zeng  DAI Weiqi  WANG Lizhu  Samuel DARAMOLA 《地理学报(英文版)》2021,31(12):1852-1872

It is common to obtain the topography of tidal flats by the Unmanned Aerial Vehicle(UAV) photogrammetry,but this method is not applicable in tidal creeks.The residual water will lead to inaccurate depth inversion results,and the topography of tidal creeks mainly de-pends on manual survey.The present study took the tidal creek of Chuandong port in Jiangsu Province,China,as the research area and used UAV oblique photogrammetry to reconstruct the topography of the exposed part above the water after the ebb tide.It also proposed a Trend Prediction Fitting (TPF) method for the topography of the unexposed part below the water to obtain a complete 3D topography.The topography above the water measured by UAV has the vertical precision of 12 cm.When the TPF method is used,the cross-section should be perpendicular the central axis of the tidal creek.A polynomial function can be adapted to most shape of sections,while a Fourier function obtains better results in asym-metrical sections.Compared with the two-order function,the three-order function lends itself to more complex sections.Generally,the TPF method is more suitable for small,straight tidal creeks with clear texture and no vegetation cover.  相似文献   

莫高窟PM10浓度与气象要素的关系     

杨小菊  赵学勇  武发思  张正模  薛平  陈章  汪万福  张国彬 《中国沙漠》2021,41(6):54-64

采用2018年敦煌莫高窟第16窟窟内与窟区PM₁₀浓度及气象数据,分析PM₁₀时空分布特征及其影响因素。结果表明：（1）两处监测点PM₁₀浓度主要分布在50 μg·m^-3以下,受重污染天气影响较小;春、冬、秋、夏季依次降低,窟区PM₁₀浓度在春、冬季高于窟内,夏、秋季反之。（2）PM₁₀浓度3月最高,9月最低,5—9月窟内月均值高于窟区。PM₁₀污染日数窟内5月最多,而窟区3、5月较多。（3）PM₁₀浓度日变化曲线在春季和秋季呈“双峰”型,夏季和冬季呈“单峰”型。（4）在半封闭环境的洞窟内,沙尘暴发生前后,PM₁₀浓度达到极值及恢复至原来水平的时间均滞后于窟区。（5）在不同季节PM₁₀浓度与气温、风速和降水呈负相关。除秋季外,PM₁₀浓度与相对湿度、气压呈正相关。（6）窟区全年主风向为ESE,在冬春两季,此风向PM₁₀浓度最高,PM₁₀主要来自三危山前的戈壁滩、干涸的大泉河河道以及窟前裸露的地表积尘。  相似文献   

京津冀水资源利用多效率指标的变化特征比较     

姚亭亭  刘苏峡 《地理科学进展》2021,40(7):1195-1207

提高水资源利用效率,缓解用水压力,是解决京津冀缺水问题的有效措施,对各行业用水效率历史状况的全局把握有助于未来政策的调整。论文比较了京津冀三地的万元GDP用水量、万元工业增加值用水量、管网漏损率、人均日生活用水量、污水处理率、作物水分利用效率共6项指标组成的综合用水效率,分析了2002—2017年京津冀用水效率的Mann-Kendall突变点和趋势变化,并基于Burg算法功率谱估计分析了各指标的周期变化特征,计算了各指标基于Burg算法的功率谱。结果表明,在产业结构优化调整和节水技术提升等措施的共同作用下,三地用水效率指标的差异在逐渐缩小,显示了京津冀协同发展的效应,但仍有明显的发展差异。北京、河北的综合用水效率整体呈增长趋势,河北的增长率(0.16)明显高于北京(0.07),而天津的综合用水效率整体上呈下降趋势(-0.03),重点表现在万元GDP用水量和万元工业增加值用水量的增加(0.18、0.19)。北京综合用水效率整体呈现5 a(周期强度为77 dB)、3 a(73 dB)左右的周期,天津综合用水效率整体呈现7 a(88 dB)、2 a(81 dB)左右的周期,河北综合用水效率整体呈现3 a(81 dB)左右的周期。相比于北京和河北,天津综合用水效率的周期性更强,这意味着可以适时地利用其内在周期调控用水效率的变化趋势。  相似文献   

Geographical Variation and Influencing Factors of Spartina alterniflora Expansion Rate in Coastal China     

ZHANG Danhua  HU Yuanman  LIU Miao  CHANG Yu  SUN Lishuang 《中国地理科学(英文版)》2020,(1):127-141

Biological invasion poses a huge threat to ecological security.Spartina alterniflora was introduced into China in 1979,and its arrival corresponded with negative effects on native ecosystems.To explore geographical variation of its expansion rate in coastal China,we selected 43 S.alterniflora sites from Tianjin Coastal New Area to Beihai.The area expansion rate,expansion rate paralleling and vertical to the shoreline were analysed based on Landsat images and field survey in 2015.Simple Ocean Data Assimilation(SODA)and climate data were collected to statistically analyse the influential factors of expansion rate.Results showed that significant difference of S.alterniflora area expansion rate among different latitude zones(P<0.01),increasing from 6.08%at southern(21°N–23°N)to 19.87% in Bohai Bay(37°N–39°N)along latitude gradient.There was a significant difference in expansion rate vertical to shoreline in different latitude zones(P<0.01)with the largest occurring in Bohai Bay(256m/yr,37°N–39°N),and showed an decreasing tendency gradually from north to south.No significant difference and latitudinal clines in expansion rate paralleling to shoreline were observed.Expansion rate had significant negative correlation with mean seawater temperature,the lowest seawater temperature,current zonal velocity and meridional velocity and presented a reducing trend as these biotic factors increased;however,they were not significantly correlated with the highest seawater temperature and mean seawater salinity.We identified significant correlations between expansion rate and annual mean temperature,the lowest temperature in January and annual precipitation,but there was little correlation with annual diurnal difference in temperature and the highest temperature in July.The rapid expansion rate in high-latitude China demonstrated a higher risk of potential invasion in the north;dynamic monitoring and control management should be established as soon as possible.  相似文献   

基于地面三维激光扫描强度数据的潮滩表层含水量估算     

陈锦  谭凯  张卫国 《地球信息科学学报》2020,22(2):290-297

大面积潮滩表层含水量的测定是潮滩研究中的难题,传统的测量方法难以同时满足高效和精度的要求。地面三维激光扫描技术凭借其高精度、高分辨率以及主动性强等优点,已经高效运用在潮滩地形研究中。但是,对潮滩含水量进行有效分析,仅利用点云的空间几何信息是不够的,还需要对点云的强度数据进行挖掘。地面激光扫描仪提供了包含目标表面光谱反射特性的点云强度数据,利用强度数据可以有效地进行目标表面特性提取。本文提出了一种新的长距离地面激光扫描仪强度数据改正方法,对入射角和距离效应进行有效改正。利用Riegl VZ-4000长距离地面激光扫描仪建立室内含水量模型并对上海市崇明岛一处潮滩进行测试分析,同时收集26个潮滩沉积物样品并利用传统干湿称重法进行含水量验证计算。结果表明：相比于传统技术,利用改正后的激光强度值估算大面积潮滩沉积物表层含水量是一种精确和高效的方法。改正后的激光强度值与潮滩表层含水量存在幂函数关系,相关系数为0.961,估算精度为91.94%。  相似文献   

基于MODIS数据的太湖浮游植物物候变化及其对水表温度的响应     

洪恬林  李云梅  吕恒  孟斌  毕顺  周玲 《地球信息科学学报》2020,22(10):1935-1945

浮游植物物候能够反映浮游植物的生长变化与湖泊生态系统的变化,水温、营养盐浓度等因素对物候有重要影响。太湖富营养化程度较高,水温的影响作用日趋显著,物候与水温关系的研究对理解、控制和改善太湖生态系统具有重要意义。本研究利用2003—2018年MODIS遥感数据计算浮游植物物候指标和湖泊水表温度（Temperature of Water Surface,LSWT）,通过分析太湖浮游植物物候时空变化特点探究了不同区域的物候特征,并结合LSWT揭示了浮游植物物候对LSWT变化的响应关系。结果表明：① 不同浮游植物物候指标具有不同空间分布特点,水华发生次数、峰值叶绿素a（Chla）浓度和水华总持续时间呈现由西部沿岸向湖心区递减的趋势;浮游植物生长开始时间和峰值Chla发生时间分布复杂但在沿岸区域相对较早;② 太湖可被划分为4种具有不同物候特征的区域,Ⅰ类区域主要位于贡湖湾、东部沿岸以及太湖中部开阔水域,该区Chla浓度范围为50~60 μg/L,且波动平缓,水华发生次数最少、开始最晚、持续时间最短;Ⅱ类区域主要分布于太湖西部沿岸,Chla浓度范围为50~90 μg/L且变化剧烈,该区水华发生次数最多、开始最早、持续时间最长;Ⅲ和Ⅳ类属于过渡区域,前者主要分布于梅梁湾、竺山湾及入湾口,后者主要位于南部沿岸以及太湖中部;③ 浮游植物物候对LSWT变化的响应受营养水平影响,当营养水平较高时,浮游植物的生长受LSWT的促进作用显著,LSWT年际变化的升高趋势对浮游植生长物候提前、生物量增加的影响明显,反之,则LSWT变化对浮游植物生长的影响减弱。  相似文献   

Interannual Variability and Scenarios Projection of Sea Ice in Bohai Sea Part I: Variation Characteristics and Interannual Hindcast     

Yan Jiao  Fei Huang  Qingrong Liu  Ge Li  Yaru Li  Qingxi Yu  Yiding Zhao 《中国海洋大学学报(英文版)》2020,19(2):272-280

The Bohai Sea is one of the southernmost areas for sea ice formation in the northern hemisphere.Sea ice disasters in this body of water severely affect marine activities and the safety of coastal residents.In this study,we analyze the variation characteristics of the sea ice in the Bohai Sea and establish an annual regression model based on predictable mode analysis method.The results show the following:1)From 1970 to 2018,the average ice grade is(2.6±0.8),with a maximum of 4.5 and a minimum of 1.0.Liaodong Bay(LDB)has the heaviest ice conditions in the Bohai Sea,followed by Bohai Bay(BHB)and Laizhou Bay(LZB).Interannual variation is obvious in all three bays,but the linear decreasing trend is significant only in BHB.2)Three modes are obtained from empirical orthogonal function analysis,namely,single polarity mode with the same sign of anomaly in all of the three bays and strong interannual variability(82.0%),the north–south dipole mode with BHB and LZB showing an opposite sign of anomalies to that in LDB and strong decadal variations(14.5%),and a linear trend mode(3.5%).Critical factors are analyzed and regression equations are established for all the principal components,and then an annual hindcast model is established by synthesizing the results of the three modes.This model provides an annual spatial prediction of the sea ice in the Bohai Sea for the first time,and meets the demand of operational sea ice forecasting.  相似文献   

Dynamical Control of Asymmetrically Oblique Tidal Currents to the Sedimentary Characteristics and Development of Linear Sand Ridges in the Liaodong Shoal,East Bohai Sea     

ZHANG Lianjie  ZHU Longhai  WU Jianzheng  HU Rijun  WANG Peng  ZHANG Pan 《中国海洋大学学报(英文版)》2020,19(1):101-112

The Liaodong Shoal is a group of linear sand ridges located in the east Bohai Sea of China.In this study,54 surface sediment samples have been collected,current measurements at 4 stations have been carried out and bathymetric data were obtained.The current directions are rightward deflected relative to the strikes of the sand ridges.Affected by the narrowing effect of the ridge,the current velocities exhibited an anti-‘C’type vertical profile.The velocities of the lower currents linearly correlate with the water depths.The near-bed current velocities over the troughs are estimated to be higher than those over the ridges,and this feature could be explained by the loss of kinetic energy together with the conversion between kinetic energy and gravitational potential energy.The sedimentary characteristics that are compatible with the tidal dynamics are developed across the ridges and troughs,including grain size compositions,grain size parameters,mineral compositions and Dhm indexes.The existence of the angles between the current directions and the strikes of the sand ridges is the key factor for the growth of the sand ridges.The asymmetric hydrodynamic features between the flood and ebb currents lead to the differences in the topographical and sedimentary characteristics on both sides of a sand ridge.Insufficient material supply led to the degradation of the sand ridges,and the reduction of the tidal current intensity has led to the development of the subordinate sand ridges in the troughs.Sand ridges are migrating.  相似文献