植被因素对无定河流域沙尘暴的影响及其侵蚀产沙意义

运用基于遥感方法提取的植被指标NDVI资料、水土保持面积的统计资料、从气象站获取的沙尘暴频率资料以及从水文站获取的悬沙粒度资料,研究了植被因素对无定河流域沙尘暴频率和悬移质泥沙粒径的影响.全流域年平均NDVI的变化在总体上表现出增大的趋势,流域内毛乌素风沙区NDVI的增大更为显著.历年累积的造林和种草面积也表现出显著的增大趋势.植被覆盖状况的改善,特别是作为本区沙尘暴主要物源区的毛乌素沙地植被覆盖状况的改善,导致了沙尘暴发生频率的减小.沙尘暴的减少使得进入河道的风成沙数量减少,进入河道的风成沙数量减少导致了悬沙粒度变细.建立了无定河悬沙中值粒径与沙尘暴频率Dss、全流域汛期(6—9月)面平均雨量P6-9、全流域平均NDVI和全流域林草面积Afg等4个影响变量之间的多元回归方程,并对各个影响变量变化对悬沙粒变化的贡献率进行了估算.按照贡献率的大小,各个影响变量的顺序如下:(1)林草面积;(2)沙尘暴频率;(3)NDVI;(4)汛期降雨量.     

沙尘暴不光发生在中国

近年来,我国北方地区沙尘暴灾害较前些年增多,影响范围扩大,危害程度也大为增强。今年3月18～21日,内蒙古、甘肃中部、宁夏北部、河北北部、北京、吉林西北部等地出现了强沙尘暴和沙尘天气,其中甘肃鼎新、内蒙古乌拉特后旗能见度曾经为零。沙尘暴天气的频繁发生,引起政府和公众的高度重     

沙尘暴过程观测数据与实测数据的综合分析

不断加深沙尘暴起沙、传输、沉降机制及其辐射强迫机理认识,提高沙尘暴的预测预警以及防治水平,已成为科研界和政府部门共同关注的问题.我们充分利用已观测的数据进行了深入的综合研究和方法探索,在数据处理本身和多元数据分析方面均取得一些新进展.本文充分利用遥感观测和地面实测手段,对亚洲沙尘暴进行监测.通过对多元数据进行分析和综合,建立了遥感监测结果与地面观测结果之间的关联关系,这些监测结果能够为综合风侵蚀模型系统和GCM(全球尺度沙尘模拟模型)模型系统提供参数和验证数据,同时为沙尘暴的预警预报提供基础数据和客观依据.     

毛乌素沙地、腾格里沙漠南缘带土地利用与气候变化关系研究——以宁夏中部为例

利用1978年MSS及1987,1996和2007年Landsat TM/ETM遥感影像,借助GIS技术,对腾格里沙漠与毛乌素沙地南缘地带土地利用与气候变化的响应关系进行了研究.结果表明,研究区年均温升高,降水量减少,气候趋于暖干化,土地利用开发程度差异显著,表现出30 a来,毛乌素沙地南缘土地利用开发强度整体较大,高于腾格里沙漠南缘地带,在变化速度上,毛乌素沙地高于腾格里沙漠南缘地区.     

2000～2018年黄土高原沙尘天气遥感监测及尘源分析

利用19年（2000~2018）MODIS L1B数据对黄土高原102次沙尘天气过程进行遥感监测与分析,以探究黄土高原沙尘天气发生的时空规律。结果表明,黄土高原沙尘天气呈减少趋势,沙尘频发季节为春季。黄土高原沙尘源地主要分布在其西北部,位于沙地和沙漠区、农灌区与黄土丘陵沟壑区、黄土高原沟壑区等生态脆弱的原生沙尘暴带。黄土高原典型的沙尘源为活动沙丘及丘间沙地、干涸湖泊河道和农田等,表明沙尘天气频发是由自然因素和人为因素共同导致的。沙尘天气的遥感监测捕捉了黄土高原沙尘活动的时空变化特征,高效地识别了沙尘源地和尘源类型,对黄土高原气候变化、生态环境变化研究和环境修复与评价具有重要指导意义。     

毛乌素沙地南缘风沙滩区生态调查与研究

每年春秋两季的沙尘暴天气已经严重影响了人们的生活,越来越多的人开始关注沙漠化的治理问题。毛乌素沙地是我国严重沙漠化的地区之一,由于其所处地理位置的特殊性,使其成为一个农、林、牧交错出现的生态脆弱带。本作品利用大量毛乌素沙地南缘风沙滩区的数据资料,以GIS为平台处理了各方面近50年来的数据,运用ISM（解释结构模型）建模,SPSS相关性分析,驱动力研究等方法分析影响当地沙漠化的重要因素;     

沙尘天气对内蒙古草原城市大气环境质量的影响研究

沙尘不仅是生态环境恶化的重要标志,也会污染大气环境,影响气象、气候和人体健康。为了探讨沙尘天气对内蒙古草原城市大气环境的影响,综合利用遥感影像与地面观测数据,研究了沙尘天气对锡林郭勒盟草原城市大气环境质量的影响,以期为沙尘天气环境影响评价提供理论依据。研究表明利用MODIS(the moderate resolution imaging spectroradiometer)数据可以实现沙尘活动的遥感监测,结果与基于地面观测发生规律一致;并得到气溶胶自动观测网(aerosol robotic network,AERONET)AOD(aerosol optical depth)产品验证。沙尘天气引起草原城市能见度下降,空气环境质量下降。大气污染主要由颗粒物的增加引起;但伴随沙尘天气的大风使CO、NO_2、SO_2等污染物浓度下降,具有清除人为源所排放污染物作用。     

沙尘天气对内蒙古草原城市大气环境质量的影响

沙尘不仅是生态环境恶化的重要标志,也会污染大气环境,影响气象、气候和人体健康。为了探讨沙尘天气对内蒙古草原城市大气环境的影响,综合利用遥感影像与地面观测数据,研究了沙尘天气对锡林郭勒盟草原城市大气环境质量的影响,以期为沙尘天气环境影响评价提供理论依据。研究表明利用MODIS(the moderate resolution imaging spectroradiometer)数据可以实现沙尘活动的遥感监测,结果与基于地面观测发生规律一致;并得到气溶胶自动观测网(aerosol robotic network,AERONET)AOD(aerosol optical depth)产品验证。沙尘天气引起草原城市能见度下降,空气环境质量下降。大气污染主要由颗粒物的增加引起;但伴随沙尘天气的大风使CO、NO_2、SO_2等污染物浓度下降,具有清除人为源所排放污染物作用。     

SPOT5遥感影像不同融合方法对地物识别精度的影响

以河南省开封市北部及郊区的SPOT5遥感影像为基础数据,对SPOT5全色波段影像与多光谱影像的几种融合方式进行了比较研究;基于各种融合结果影像进行实验区域的计算机监督和非监督分类,提取各类地物面积数据,比较影像融合前后各类地物面积变化率;分析不同融合影像对地物识别精度的影响,确定适宜不同地物判识的融合影像和方法,旨在为土地利用类型调查中的影像融合方法的选择提供参考.     

造林种草与沙尘暴

随着社会的发展,人们对环境问题愈来愈关注,我国北方一些地区每年春天频繁出现的沙尘暴天气,就是大家关心的热点问题之一。沙尘暴的形成沙尘暴是一种天气现象,正如刮风、下雨、下雪一样都是不可避免的。沙尘暴的发生需要具备两个基本条件:第一是气象条件,即高空有强气流运动而形成大风天气,大风是沙尘暴发生的原动力;第二是地面要有充足的沙尘物质来源。大量松散的沙尘物质在强劲风力作用下,被卷入气流中形成了沙     

Distribution of sand dunes and sand shifts along the southern fringe of the Mu Us Desert since the Ming Dynasty

This article takes the two segments of the Ming Great Walls, Dabian and Erbian, and their associated barracks and forts as geographical references. Based on a detailed scrutiny of historical records of the Ming and Qing dynasties, and on field surveys, the southern boundaries of the sand dunes and sand shifts of the Mu Us Desert in the Ming and Qing dynasties are carefully reconstructed. A comparison of the southern boundaries of the sand dunes and sand shifts of the Mu Us Desert in Ming and Qing with the modern boundary revealed in remote sensing imagery clearly shows that the southern boundary of dunes and shifts in the Mu us Desert has expanded only in a few areas and on a small scale. In the area to the south of Changle Fort, along the direction of annually prevailing winds, sand drifts have penetrated through the Jialu River valley into the loess region and have formed a sand strip of 32 km long and 3 km wide. To the east of Qingping Fort, sand drifts penetrated toward the eastern loess region through the Luhe River valley and have formed another sand strip of 8 km long and 2 km wide. Generally speaking, though the intensity of human activity has been increasing in this area since the Ming Dynasty, the Mu Us Desert has not significantly expanded toward the southeast or southwest. The sand-loess boundary in the southern fringe of the Mu Us Desert has been almost unchanged since the Ming Dynasty.     

远源地下水入侵阿拉善高原沙漠:酸溶物Sr同位素证据

选取北方西－东向气候剖面上物质组成相似的四个沙漠（塔克拉玛干、巴丹吉林、腾格里和毛乌素）,测定其地表沙酸溶物87Sr/86Sr比值、Ca2+和Sr2+浓度。Ca2+和Sr2+浓度相关性极好,在降雨量低的塔克拉玛干沙漠中最高,向东逐渐降低,在降雨量多的毛乌素沙漠中最低。降雨量是控制阳离子浓度变化的主导因素。酸溶物87Sr/86Sr比值在四个沙漠中有不同于阳离子变化的区域特征。塔克拉玛干沙漠酸溶物87Sr/86Sr比值在0.71以下,巴丹吉林和腾格里沙漠的大于0.7112,而毛乌素沙漠的在0.71-0.7112之间变化。塔克拉玛干和毛乌素沙漠地表沙酸溶物87Sr/86Sr比值仅受气候变化的制约。巴丹吉林和腾格里沙漠除了受气候因素影响外还受其它因素的制约,最可能的就是远源地下水。经计算,远源地下水对巴丹吉林沙漠的影响份额为47%,对腾格里沙漠为44%,接近气候因素的影响。     

Stepwise advance of the Mu Us Desert since late Pliocene: Evidence from a red clay-loess record

Analyses of paleomagnetic polarity reversals, magnetic susceptibility and grain size on the red clay-loess sequence, about 280 m thick, at Jingbian show that this sequence contains most of the stratigraphic units recorded in the standard red clay-loess sections of the Loess Plateau over the past 3.5 Ma. Using sand particle percentage ( > 63 μm%) of the eolian sequence as a proxy indicator of desert extent and aridity in the dust source regions, it is found that during the past 3.5 Ma, there are three important climatic events indicating the advance of the Mu Us Desert. The events occurred at about 2.6, 1.1 and 0.6 MaBP, respectively. The stepwise advance of the Mu Us Desert may be linked closely to increase in global ice volume and uplift of the Tibetan Plateau in the late Cenozoic.     

Validating a dust production model by field experiment in Mu Us Desert, China

It is essential for validation and improvement of a dust production model to perform field observations on dust emissions. The dust production model (DPM model) consists of two physically explicit sub-models, namely saltation model [1, 2] (eq. (1)) and sandblasting model [3] (eqs. (2) and (3)). Fh is saltation flux, E is fraction of erodible surface, C is a dimensional constant, ρa is air density, g is gravitational acceleration, U* is the wind friction velocity, Ut*(Dp) is threshold frict…     

Typical severe dust storms in northern China during 1954 —2002

Based on China抯 available daily observation data from 681 national meteorological stations from 1954 to 2002, a time series of typical severe dust storms in northern China is constructed in terms of the weather process, and the temporal and spatial distribution, and their evolution ten-dency is analyzed. The results indicate that there were 223 relatively typical severe dust storms in northern China from 1954 to 2002, among which the event on April 10—12, 1979 had the largest affected area. Closely associated with the geographical distribution of deserts, sandy lands and the tracks of strong cold air outbreaks, severe dust storms mainly occurred in the Tarim Basin, the eastern part of Northwest China and the northern part of North China. The season with the most frequent severe dust storms was spring, in which the frequency accounts for 82.5% in the whole year, while the least occurrence was in summer and autumn. Dur-ing the past 49 years, the highest frequency of severe dust storms occurred in the 1950s and the lowest was in the 1990s with a general descending tendency, but during 2000—2002 the occurrence was relatively increasing. On the average, the duration of severe dust storms was shortest in the 1990s, about 0.5—1 h shorter than that in the other 4 decades.     

Seasonal variations of dust record in the Muztagata ice cores

Based on the oxygen isotope ratio and microparticle record in ice cores recovered at Mt. Muztagata, Eastern Pamirs, the seasonal variations of atmospheric dust have been reconstructed for the past four decades. High dust concentrations and coarser particle grains have the similar trend with oxygen isotope value. Our statistical results indicate that 50%--60% high dust concentration samples occur during the season with high oxygen isotope values （summer）, while low dust storm frequency during spring and winter. Back-trajectory analysis shows that the air mass hitting Muztagata predominately came from West Asia （such as Iran-Afghanistan Plateau） and Central Asia, which are the main dust source area for Muztagata. Dust storms in those source areas most frequently occur during summer （from May to August）, while frequent dust storm events in northern China mainly occur during spring （March to May）. Regions in the path of Asian dust transport, such as in Japan, the North Pacific, and Greenland, also show high dust concentrations during spring （from March to May）. Our results indicate that dust storms have different seasonality in different regions within Asia.     

近50年来毛乌素沙地草地生态脆弱性评价——以内蒙古乌审旗为例

选择位于毛乌素沙地腹地的乌审旗作为研究区,基于1960年代,1978,1988,2000和2008年土地覆被数据,借助GIS空间分析技术,通过建立＂敏感性-弹性-压力＂生态脆弱性评价模型,对研究区近半个世纪的草地生态脆弱性进行动态评价。结果表明：乌审旗草地生态系统大部分属于中、低度脆弱区。50年间,草地生态脆弱性经历了...     

Dust storms and loess accumulation on the Tibetan Plateau：A case study of dust event on 4 March 2003 in Lhasa

Whether the Tibetan Plateau is a significant dust source area is of great importance, because this is related to the understanding of sources, accumulation and environmental effects of dusts on the Tibetan Plateau and inthe Far East-Pacific Ocean regions as well as to the evointion of coupling of the Tibetan Plateau and atmaspbere-oeean-continent exchange. Synoptic dynamics and remote sensing tracing of a dust storm on 3 to 5 March, 2003 in Lhasa onSouth Tibet demonstrate that the Tibetan Plateau possessesall factors and conditions of generating dust storms. Accompanied with this dust storm is a strong ascending stream onthe Plateau which has raised various sizes of durst particlesinto different levels. The lifted coarse particles were largelyfallen down and accumulated as loess on the eastern TibetanPlateau, and the fine particles were translated by the westerly jet and subsided in the northern Pacific Ocean. The spa-tial-temporal distribution of dust-storms between years 1961and 2000 ou the Plateau shows that duststorms mainly occurin winter and early spring with high frequency, and tile pathof dust storm moves gradually from south to north, which isclosely coupled with the northward moving of the westerlyjet from winter to spring over the Tibetan Plateau. Com-pared with other twelve dust source areas in China. the Ti-betan Plateau is one of the key dust souree areas for thelong-distance transport because its high occurring frequencyand elevation cause fine particles easily to be lifted into thezone of the westerly jet.     

Great progress in study on aerosol and its impact on the global environment

The transport from atmosphere is a more important pathway than that from rivers for certain elements and compounds in the remote ocean. The desert and those arid/semi-arid areas in the northwest of China and the Loess Plateau are the sources of those aerosols over the Pacific. Atmospheric iron is the limiting factor of the productivity in certain ocean regions. The dust storms must now be seen as repeated sources of pollution elements as well as soil elements to the East China Sea and, farther out, to the North Pacific Ocean and even to the USA. The long-range transport of aerosols, especially the dust storm, from China and the positive feedbacks of iron coupled with sulfur in atmosphere might be one of the important mechanisms that would affect the primary productivity in the Pacific and/or the global climate change and deserve to be further studied. It can be seen clearly that the dust storms would affect not only the health of human beings and the local or regional climate, but also the global climate change that has been the focus of environmental study internationally.     

海表面流场微波遥感研究进展及其关键技术问题分析

海表面流场是海洋学中十分重要的研究对象,本文综述了海表面流场微波遥感所涉及的海表面建模、计算电磁学、合成孔径雷达(synthetic aperture radar,SAR)海面成像及SAR信号等基础研究领域,梳理了海表面流场微波反演的研究进展,分析了目前已有反演方法的利弊并找出待研究的科学问题,逐一剖析这些问题并提出解决方法。针对海表面流场微波遥感中有待解决的在动态海表面建模中如何引入海表面流场因素、运动海面电磁散射特征的表征中如何选取参数和反演过程中需要注意的图像分辨率等问题,提出了研究策略,指明了海表面流场微波遥感的技术路线和研究方向,最后对海表面流反演工作进行了展望,探讨了高分辨率海流反演的下一步工作。