共查询到19条相似文献，搜索用时 312 毫秒
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近年来沙尘暴发生越来越频繁,严重危害人类的生产生活。张掖市、武威市位于甘肃省河西走廊地区,是我国北方沙尘暴频发地区,民勤县更是沙尘暴频发中心。本文利用MODIS数据和沙尘暴识别模型SVI对2010年4月22~26日该地区沙尘情况进行连续监测,并进行分级讨论,结合地面观测数据,分析沙尘暴发生时的地面情况。 相似文献
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依据甘肃兰州市1955-2010年沙尘暴、 浮尘天气事件年变化资料, 划分年强度分级, 应用Markov模型对其不同强度发生概率进行分析, 在此基础上预测和检验了2011年兰州沙尘暴浮尘天气事件的发生概率.结果显示: 2011年沙尘暴发生的特强年、 强烈年、 强发生年、 一般发生年和少发年的概率为,而事实上2011年发生沙尘暴0次,属于少发年, 符合预测结果; 2011年浮尘天气发生的特强年、 强烈年、 强发生年、 一般发生年和少发年的概率为,而事实上2011年发生浮尘9次,介于平常年和少发年范围, 符合预测结果.随着时间序列的延长, Markov模型可成为短期沙尘暴浮尘天气变化预测的有效途径. 相似文献
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中国北方沙尘灾害影响因子分析 总被引：8，自引：0，他引：8
利用中国北方1951—2000年188个沙尘暴代表站的气象观测数据和1983—2000年EROS数据中心NDVI数据，对我国北方沙尘灾害的影响因子进行了分析。主要结论有：①在影响沙尘暴发生、发展、演化的自然因子中，植被覆盖度、降水、大风日数和温度起关键作用，夏季植被覆盖度对来年春季沙尘暴发生频次影响较大，降水和温度主要表现在对地表植被覆盖等与沙尘暴有关的地表参数的影响；②大风日数和温度是沙尘暴形成的动力因子，植被覆盖度和降水是阻力因子。沙尘暴日数和持续时间的变化，主要取决于动力因子与阻力因子的综合作用；③遏制沙尘灾害的治本办法，不在于治理沙尘暴本身，而在于消除产生土地退化、生态安全下降的社会原因，处理好发展与生态环境建设的关系。 相似文献
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本文利用1954～1998年中国681个站的气象实测资料,分析了近45年我国扬沙和沙尘暴天气的时空分布特征.结果表明,我国西北、华北、东北和青藏高原地区是扬沙和沙尘暴的主要影响区,其中西北地区是多发区,并有两个明显的高频中心;扬沙和沙尘暴的季节变化大致可划分为3种类型;45年间除青海、内蒙古和新疆的小部分地区扬沙和沙尘暴日数呈增长趋势外,我国北方大部分地区扬沙和沙尘暴日数在减少.进一步分析表明,扬沙、沙尘暴日数与大风日数的年际振荡及多年变化趋势有一致性;70年代以后由大风日数减少所引起的扬沙、沙尘暴减少可能是气候准周期性变化的反映. 相似文献
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自3月11日遭遇今年首场沙尘暴天气以来，短短20天，六次沙尘天气集中侵袭中国。尤其是3月19日至21日出现的强沙尘暴，不仅影响新疆、青海、内蒙古、华北、黄淮北部等北方地区，沙尘还伴随大风一路南下，蔓延至黄淮、江汉、江淮、华南东北部等，一度横跨海峡影响台湾，累计影响全国21个省市。中国气象局预测，4月中下旬，中国北方还将出现沙尘天气。这也就意味着，即将到来的第41个地球日，广阔地域上的中国居民很可能将在漫天黄沙中度过。 相似文献
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沙尘暴是甘肃近年来的主要灾害天气之一。文章主要从年均变化、季节变化、空间分布上分析了甘肃沙尘暴的发生特征、沙尘暴产生的自然及人为原因,最后就甘肃主要生态系统的环境整治、沙尘暴治理提出了一些建议。 相似文献
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阿拉善高原干涸湖床沉积物与华北地区沙尘暴 总被引：16，自引：3，他引：13
文章通过内蒙古阿拉善高原古居延泽干涸湖床沉积物、周缘活动沙丘、沙质草原地表土壤及古代弃荒土地的粒度组成分析,论述干涸湖床沉积物对沙尘天气的影响。古居延泽湖床沉积粒度分析结果表明,干涸湖床的地表湖相沉积物粒径小于10μm的颗粒占64%以上,可以在一般风暴条件下在大气中搬运几千公里,这意味着西北地区干涸湖床产生的粉尘在风暴作用下可以横扫整个东亚北部地区。中国西北地区冬、春季多西北风造成沙尘暴或扬沙天气,西部沙漠、沙地或沙质草场遭遇强风时沙尘被席卷进气流,但其中粗砂粒扬起的高度、搬运的距离有限,当风力稍稍减弱,粗颗粒砂粒沉降,而粉尘继续悬浮运移。当强风途径下一个沙区时新的沙尘加入,沙尘暴呈“接力方式”继续向东南部移动。 相似文献
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苏干湖沉积物粒度组成记录尘暴事件的初步研究* 总被引：6，自引：13，他引：6
文章通过分析苏干湖表层沉积物、流域表层沉积物、大气降尘以及湖泊冰面囚固碎屑颗粒等的粒度组成,比较了流域地表沉积与湖泊沉积物粒度组成的差异和苏干湖表层沉积粒度组成的空间变化。初步认为苏干湖沉积物粗颗粒组分(>63μm)主要由风力搬运入湖,>63μm组分的含量可以用来指示研究区尘暴事件的演化。结合湖泊沉积岩芯纹层计数年龄,重建的1000年来尘暴演化历史显示,在1210A.D.之前尘暴事件较弱,且变化幅度较小;1210A.D.以来则表现出高频率或者高强度,其中13世纪上半叶以及17世纪的高值段与东部降尘变化历史一致。就气候变化的特征时段(中世纪暖期、小冰期等)而言,尘暴事件主要与气候变冷情况下较强的盛行风场有关;而极端干旱区有效湿度的增加可能有利于地表粉尘的释放,助长了尘暴事件的发生。 相似文献
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沙粒不能“远走高飞”———有关“尘暴”的一条根本原理 总被引：3，自引：0，他引：3
沙与尘虽然都是岩石物理风化的产物, 但在风力作用下, 习性截然不同。拜格诺用严格的物理实验证明, 尘粒能随风远走高飞, 而沙粒却只能在地面附近跳跃前进。从北方侵袭华北平原的所谓沙尘暴, 实质上都是尘暴。对历次重大天气事件沉积物的分析, 也完全证明了这一点。因此, 尘暴物质的源头不是来自有沙, 而是有尘的地方; 从而可以使人们采取正确的治理方法。 相似文献
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SEDIMENTARY CHARACTERISTICS AND CLIMATIC ANALYSIS OF EASTERLY DUST STORMS IN THE NEGEV (ISRAEL) 总被引：1，自引：0，他引：1
Sedimentary and meteorological characteristics of easterly dust storms causing severe damage in the Negev in November 1958 are analysed. Though the heavy storm originated in weather conditions outside of the affected area, the intense dustiness was of a more local nature. The sedimentological character of the dust indicates that the largest portion was of local origin, picked up by the turbulent current in the loess area of the northern Negev on its passage westward. Total quantity of sediment transported in the Beersheba Basin is estimated to be 10–20 million tons. The analysis of climatic data and of sedimentary characteristics of several other dust samples indicates that though severe dust storms can produce dramatic effects in transporting and deposition of aeolian dust, the rare occurrence of easterly dust storms does not make it likely that they were responsible for the import of aeolian sediments found in the northern Negev. 相似文献
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北京2002年3月20～21日尘暴过程的降尘量与降尘粒度特征 总被引：27，自引：3，他引：24
本文对2002年3月20～21日发生在北京地区的一次尘暴过程进行了降尘量和降尘粒度的研究。通过对分时段监测取得的13组降尘样品进行降尘量和粒度测定,结合风速变化情况,可将本次尘暴分为尘暴前期和尘暴后期两个过程。降尘量和粒度参数值在尘暴前期和后期都呈现不同特征。结论认为,风速是降尘量变化的重要因素。当风速进一步增大时,降尘量反而有所下降。说明北京地区尘暴降尘量除受本地风速影响外,还与粉尘浓度等特征有关。尘暴降尘的粒度基本呈双峰态分布。本次尘暴初始降尘主要为细粒径颗粒,尘暴前期降尘粒径随风速而变化,尘暴后期降尘粒径基本维持在5～6之间 相似文献
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A wind tunnel simulation and field verification of desert dust deposition (Avdat Experimental Station, Negev Desert) 总被引：1，自引：0，他引：1
The deposition of natural dust in an area of 53 ha, situated in the northern Negev desert, is investigated in detail both in the wind tunnel (dust storm simulations over a topographic scale model) and in the field. The wind tunnel results and the field results show a high degree of agreement, indicating that scale-model simulation may be considered an important technique for future loess and desert research. More dust settles on windward slopes than on leeward slopes, which is in contradistinction with the widespread wind shadow concept. Air-flow separation zones immediately downwind of steep windward slopes have an important impact on dust deposition too. In the case of dust deposition on topographic scale models, a restricted height distortion of the model will not necessarily lead to serious problems. In addition, wind tunnel blockage percentages up to 13% may be allowed in order to obtain acceptable dust deposition patterns for the scale model. A mean gross dust deposition of about 200–250 g m?2 year?1 is calculated for the northern Negev desert for 1987. Thus, if the settled dust can be protected against erosion in the cultivated areas in the Negev, the dust content of the top soil will markedly increase with time. However, it has to be borne in mind that cultivation activities themselves may also contribute to a higher soil erosion and, hence, to a higher dust content in the atmosphere. At any rate, a higher dust content in the top soil will unquestionably have an important positive effect on agricultural yields. From the air dust concentration data and the dust deposition data, a deposition velocity of 4.7cms?1 can be calculated for Avdat dust. 相似文献
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Sand and dust storms are causing hazards and problems in aviation as well as the dangers and distresses they cause on living things. The low meteorological visibility, the presence of strong winds with gust, and the transport of dust and sand particles by the wind are dangerous on landing and departure of aircrafts, and even on planes that are parked. The main aim of the study is to examine the meteorological conditions causing the dust storm that took place in the Arabian Peninsula on February 28, 2009, and to determine the source of dust caused dust storm, sand storm, blown sand, and blown dust at the airports. Within the scope of the study, aviation routine weather report (METAR) and aviation selected special weather report (SPECI) reports have been assessed at many airports over Arabian Peninsula (AP), the northern part of the AP and North Africa. As model outputs; NCEP–DOE Reanalysis 2 data, BSC–DREAM8B, and HYSPLIT model were used. In the satellite images; METEOSAT MSG dust RGB images, MODIS, and Kalpana-1 data were used. According to obtained results, dust storms were detected in Bahrain, Kuwait, Saudi Arabia, and United Arab Emirates (UAE). At Al-Ahsa Airport in Saudi Arabia, the lowest visibility measured on February 28, 2009, dropping to 200 m, which was dominated by blowing sand. The source region of the dust observed at Dubai Airport in UAE is the eastern regions of the Rub’al Khali Desert located between Saudi Arabia, Oman, and UAE. 相似文献
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In this research, the frequency of dust storms was prepared at 87 synoptic stations for the period of 1987–2013. These data were classified by means of Fuzzy c-means clustering algorithm. Satellite images of MODIS and brightness temperature index were also used for detection and tracking dust storm of 30 Jun 4 July 2008. The results indicated that Iran is classified in five clusters by the dust-storm-frequencies from which, cluster 5 is reclassified in three clusters because of its wide range. The maximum number of days with dust storms was observed in cluster 1 that includes only Zabol station with the frequency of 790 days with the duration 1987–2013. The minimum number of days with dust storms was observed in cluster 5-3 that includes the stations located in portions of North, Northwest, Northeast Iran and the higher elevations of the Zagros in western Iran. A case study about a severe dust storm in Iran using satellite images indicate that brightness temperature index (BTI) is a desired index for detection and monitoring of dust storms. The source of the investigated dust storms is Iraq and South of the Arabian Peninsula that had influenced the western half of Iran in several days. The frequency of dust storms increased markedly in the west, southwest of Iran and Persian Gulf around as main receptors from emerging dusty areas but it increased slightly in the eastern half of Iran. 相似文献