北方麦收期间连阴雨天气环流特征   总被引：15，自引：0，他引：15  

王秀文  李月安 《气象》2005,31(9):52-56

利用1980-2004年5月下旬至6月中旬北方麦收区30个代表站降水实况资料，连阴雨期间亚欧范围500hPa逐日形势图和500hPa高度平均图等，分析总结了近25年来北方麦收期间连阴雨的天气气候和环流形势特征；对北方麦收期间出现的连阴雨天气过程与环流形势和影响系统的关系进行初步探讨，确定连阴雨天气的概念模型。分析表明，阻塞高压形势且贝加尔湖附近伴有冷涡是造成连阴雨天气最主要的环流特征；在500hPa地转风υ场上，麦收区多处于南北风交界处；长连阴雨期间，850hPa东亚地区中低纬度盛行南风为主要特征。  相似文献   

Sentinel-2与Landsat 8数据组合下的多特征冬小麦面积提取     

王晓晓  韩留生  杨骥  李勇  张大富  孙广伟  范俊甫 《测绘通报》2022,(3):111-115

遥感卫星的波段设置、信噪比及传感器观测角度等因素都会影响作物提取精度。为充分挖掘与发挥Sentinel-2卫星多光谱成像仪(MSI)与Landsat 8陆地成像仪(OLI)在冬小麦信息提取方面的优势,本文以商河县为研究区,基于两数据源的光谱特征、纹理特征、植被指数特征组合数据,利用随机森林(RF)与支持向量机(SVM)对冬小麦进行提取。结果表明:基于单一影像的最优Kappa系数与最优OA分别为0.89和95.13%,基于组合数据源的最优Kappa系数为0.92,最优OA为95.28%,两数据源组合的精度优于单一数据源提取精度;数据组合效果与分类器的性能有关,RF的Kappa系数相对于SVM分别提升0.04、0.20和0.11,OA分别提升2.41%、11.31%和6%,RF对冬小麦提取精度优于SVM。本文研究结果对于构建中高分辨率影像组合的典型农作物分类提取体系具有重要意义。  相似文献   

新疆巴楚浅层地温变化对春季物候的影响     

阿布都克日木.阿巴司 《沙漠与绿洲气象(新疆气象)》2014,8(6):53-55

本文利用1961-2010年巴楚0～40cm逐月平均地温资料,采用气候倾向率和累积距平气候统计方法,探讨近50a巴楚县不同深度的地温变化特征,研究巴楚县气候变化对当地农、林果业生产以及生态环境的影响。结果表明：这半世纪来,巴楚县浅层地温的年和季节平均值呈现出不同程度的上升趋势,其中40cm的年升温率和夏季的升温率最大。近10a来,巴楚县地温明显升高,浅层地温的年、季节平均或平均最高、最低等均明显高于前40a。随着巴楚县地温的上升,年极大冻土深度的下降趋势也很明显,当地冬小麦返青期和林果业的树木萌动期提前。  相似文献   

我国北方地区冬小麦干旱灾害风险评估   总被引：7，自引：0，他引：7  

张存杰  王胜  宋艳玲  蔡雯悦 《干旱气象》2014,32(6):883-893

选取我国粮食重要生产区——北方冬麦区作为研究区,基于干旱灾害对作物产量的影响开展冬小麦干旱灾害风险评估和区划。在确定干旱灾害危险性指标过程中,通过对比分析MCI、CWDIa、CI、Pa及Ma干旱指数的适应性,确定了干旱灾害风险危险性指数;在分析北方冬麦区干旱背景和脆弱性时,考虑了冬麦区的地形、土壤类型、土壤有效持水量、河网水系、灌溉条件、降水量及干燥度等环境因素,以及冬小麦的耕地面积、播种面积、主要生育期的水分敏感系数、历史产量等。与以往致灾因子危险性分析方法不同,本文首先建立了干旱指标与冬小麦减产率之间的关系,通过减产率等级来确定干旱致灾临界阈值,在此基础上计算分析了冬小麦全生育期和6个关键生育期不同等级干旱发生的频率。综合考虑干旱发生的危险性、不同地区干旱背景和脆弱性,建立了我国北方冬麦区全生育期和6个关键生育期的干旱灾害风险评估模型和区划方法,实现了我国北方冬麦区干旱灾害的风险评估和区划。结果表明,MCI更能反映北方冬麦区干旱的特征,故以MCI指数作为干旱灾害风险危险性指数;我国北方冬麦区中北部的干旱灾害风险较高,应该加强防旱抗旱能力建设,南部地区包括苏皖和河南东南部的干旱灾害风险较小。本文建立的北方冬麦区不同生育期干旱灾害风险评估模型可应用于干旱灾害风险动态评估实时业务中。  相似文献   

河北平原冬小麦播种面积收缩对农业水资源消耗的影响(英文)     

王学  李秀彬  辛良杰 《地理学报(英文版)》2014,(2)

This study firstly analyzed the shrinkage of winter wheat and the changes of cropping systems in the Hebei Plain from 1998 to 2010 based on the agricultural statistic data of 11 cities and meteorological data, including daily temperature, precipitation, water vapor, wind speed and minimum relative humidity data from 22 meteorological stations, and then calculated the water deficit and irrigation water resources required by different cropping systems, as well as the irrigation water resources conserved as a result of cropping system changes, using crop coefficient method and every ten-day effective precipitation estimation method. The results are as follows. 1) The sown areas of winter wheat in the 11 cities in the Hebei Plain all shrunk during the study period. The shrinkage rate was 16.07% and the total shrinkage area amounted to 49.62×104ha. The shrinkage was most serious in the Beijing-Tianjin-Tangshan metropolitan agglomerate, with a shrinkage rate of 47.23%. 2) The precipitation fill rate of winter wheat was only 20%–30%, while those of spring maize and summer maize both exceeded 50%. The irrigation water resources demanded by the winter wheat-summer maize double cropping system ranged from 400 mm to 530 mm, while those demanded by the spring maize single cropping system ranged only from 160 mm to 210 mm. 3) The water resources conserved as a result of the winter wheat sown area shrinkage during the study period were about 15.96×108m3/a, accounting for 27.85% of those provided for Beijing, Tianjin and Hebei by the first phase of the Mid-Route of the South-to-North Water Diversion Project.  相似文献   

Development and implementation of a multiscale biomass model using hyperspectral vegetation indices for winter wheat in the North China Plain     

《International Journal of Applied Earth Observation and Geoinformation》2014

Crop monitoring during the growing season is important for regional management decisions and biomass prediction. The objectives of this study were to develop, improve and validate a scale independent biomass model. Field studies were conducted in Huimin County, Shandong Province of China, during the 2006–2007 growing season of winter wheat (Triticum aestivum L.). The field design had a multiscale set-up with four levels which differed in their management, such as nitrogen fertilizer inputs and cultivars, to create different biomass conditions: small experimental fields (L1), large experimental fields (L2), small farm fields (L3), and large farm fields (L4). L4, planted with different winter wheat varieties, was managed according to farmers’ practice while L1 through L3 represented controlled field experiments. Multitemporal spectral measurements were taken in the fields, and biomass was sampled for each spectral campaign. In addition, multitemporal Hyperion data were obtained in 2006 and 2007. L1 field data were used to develop biomass models based on the relation between the winter wheat spectra and biomass: several published vegetation indices, including NRI, REP, OSAVI, TCI, and NDVI, were investigated. A new hyperspectral vegetation index, which uses a four-band combination in the NIR and SWIR domains, named GnyLi, was developed. Following the multiscale concept, the data of higher levels (L2 through L4) were used stepwise to validate and improve the models of the lower levels, and to transfer the improved models to the next level. Lastly, the models were transferred and validated at the regional scale using Hyperion images of 2006 and 2007. The results showed that the GnyLi and NRI models, which were based on the NIR and SWIR domains, performed best with R² > 0.74. All the other indices explained less than 60% model variability. Using the Hyperion data for regionalization, GnyLi and NRI explained 81–89% of the biomass variability. These results highlighted that GnyLi and NRI can be used together with hyperspectral images for both plot and regional level biomass estimation. Nevertheless, additional studies and analyses are needed to test its replicability in other environmental conditions.  相似文献   

畜禽粪便农用区土壤-小麦系统中重金属污染及迁移   总被引：4，自引：0，他引：4  

叶必雄  刘圆  虞江萍  杨林生  王五一  欧阳竹 《地理研究》2013,32(4):645-652

畜禽粪便农用导致农产品中重金属含量超标,通过生物链传递,最终会影响人体健康。以山东禹城典型畜禽粪便农用区为例,研究了不同畜禽粪便农用区土壤—小麦系统中重金属的污染及迁移累积情况。结果显示:某些区域存在着一定的重金属污染,鸡粪农用区、猪粪农用区污染较高,综合污染指数均值分别为0.83、0.78,都达到了警戒级,其中某些点的污染指数超过了1和2,达到了轻污染或中污染级;牛粪农用区污染较轻,综合污染指数为安全级。不同畜禽粪便农用区小麦中的Cr、Ni、Cd、As均存在不同程度超标情况,其中鸡粪农用区Cr的超标率达66.67%,Ni、Pb超标率都为16.67%;牛粪农用区小麦中Cr、Ni超标,Cr超标率达91.67%;猪粪农用区小麦中只有Cr超标,超标率为41.67%。研究区小麦显示出不同的重金属富集能力,小麦对Cd、Zn、Cu几种元素的富集情况较高,而对Pb、As的富集能力则较低。除Zn外,小麦茎叶对同一种重金属的富集能力要大于小麦的种子。  相似文献   

华北滹滏平原地下水位下降与灌溉农业关系   总被引：2，自引：0，他引：2       下载免费PDF全文

张光辉  费宇红  刘春华  冯慧敏  严明疆  王金哲 《水科学进展》2013,24(2):228-234

针对华北粮蔬主产区滹滏平原浅层地下水位不断下降成因问题,基于大量实测资料和相关分析方法与MapGIS技术,通过对近50年来区内地下水位、粮蔬播种强度、有效灌溉面积变化特征和降水量、气温变化下地下水位下降对粮蔬播种强度响应机制研究,结果表明:1980年前粮蔬播种强度每增加0.01或夏粮和蔬菜播种面积每增加1万hm2,研究区地下水位下降幅度为0.36 m或0.43 m;1980年以来随粮蔬播种强度增大,地下水位下降幅度明显增大,粮蔬播种强度每增加0.01或夏粮和蔬菜播种面积每增加1万hm2,地下水位降幅分别达0.69 m和1.15 m。不仅与因播种强度增大导致农业开采量增加有关,而且还与1980年以来降水量不断减少密切相关。降水量减少100 mm,区内农业开采量增加35.7 mm。  相似文献   

冬小麦冬季干旱时段灌溉气象适宜指数研究     

李德  张学贤  刘瑞娜 《气象》2012,38(12):1565-1571

对1955-2010年宿州市冬季降水量和气温变化的数理统计分析结果表明：宿州市冬小麦冬季仍处于缓慢生长状态,特别是在干旱和暖冬的双重影响下,冬季麦田一般需要灌溉一次。在此基础上,采用德尔菲法（Delphi technique）,确定了影响冬季麦田实施灌溉的降水、日最低气温和风速3个气象要素的各自的量化等级和影响灌溉适宜与否的权重系数,给出了冬季干旱时段灌溉气象适宜指数概念和计算模型,再结合天气预报产品的释用方法,得到了冬小麦冬季干旱时段灌溉农用天气预报产品。经实例应用,可适应对外发布冬季麦田灌溉农用天气产品的需要。  相似文献   

气候变化对河南省灌溉小麦的影响及对策初探   总被引：3，自引：0，他引：3       下载免费PDF全文

成林  刘荣花  王信理 《应用气象学报》2012,23(5):571-577

灌溉是河南省冬小麦最重要的种植管理模式。在DSSAT-CERES小麦模型参数调试和区域适用性验证的基础上,利用区域气候模式PRECIS输出的未来气候情景资料,量化分析了2021—2050年河南省灌溉条件下冬小麦产量的可能变化,结果表明:若不采取其他措施,未来A2,B2两种温室气体排放情景下,河南省冬小麦产量平均减少5%左右,A2情景减产率略高于B2;随着产量降低,产量波动区间略有缩小,但25%~75%的稳产区间也相应缩小,且B2情景下更容易出现极端低产的年份;冬小麦水分利用效率相应降低。采取适当应对措施,如延迟播种期、减小种植密度等有利于提高产量或缓解减产趋势。  相似文献