Effects of Drought on Winter Wheat Yield in North China During 2012-2100

Winter wheat is one of China's most important staple food crops, and its production is strongly influenced by weather, especially droughts. As a result, the impact of drought on the production of winter wheat is associated with the food security of China. Simulations of future climate for scenarios A2 and A1B provided by GFDL_CM2, MPI_ECHAM5, MRI_CGCM2, NCAR_CCSM3, and UKMO_HADCM3 during 2001- 2100 are used to project the influence of drought on winter wheat yields in North China. Winter wheat yields are simulated using the crop model WOFOST (WOrld FOod STudies). Future changes in temperature and precipitation are analyzed. Temperature is projected to increase by 3.9-5.5℃ ? for scenario A2 and by 2.9-5.1℃ ? for scenario A1B, with fairly large interannual variability. Mean precipitation during the growing season is projected to increase by 16.7 and 8.6 mm (10 yr)-1, with spring precipitation increasing by 9.3 and 4.8 mm (10 yr)-1 from 2012-2100 for scenarios A2 and A1B, respectively. For the next 10-30 years (2012- 2040), neither the growing season precipitation nor the spring precipitation over North China is projected to increase by either scenario. Assuming constant winter wheat varieties and agricultural practices, the influence of drought induced by short rain on winter wheat yields in North China is simulated using the WOFOST crop model. The drought index is projected to decrease by 9.7% according to scenario A2 and by 10.3% according to scenario A1B during 2012-2100. This indicates that the drought influence on winter wheat yields may be relieved over that period by projected increases in rain and temperature as well as changes in the growth stage of winter wheat. However, drought may be more severe in the near future, as indicated by the results for the next 10-30 years.     

非充分灌溉制度设计优化模型

研究了缺水地区冬小麦灌溉问题.分析了作物模型,作物水分影响函数,并以农作物产量最大为目标,提出了非充分灌溉制度优化设计二维动态规划模型和相应的动态规划逐次逼近(DPSA)求解方法.针对山东省临沂市小埠东灌区的实际情况进行研究,求得了冬小麦三个典型年不同供水水平的最优灌溉制度、排水过程及相应产量.实例表明,模型及方法是合理的.     

澳洲夏季风热源低频变化对北半球冬季风影响的数值研究

采用ｐ－σ混合坐标系的５层原始方程模式研究了与澳洲夏季风低频变化相伴随的对流性低频加热源所激发的大气强迫波和东亚冬季风的关系，结果表明澳洲夏季风低频热源可引起北半球副热带高低层环流、东西向Ｗａｌｋｅｒ环流。经向环流、越赤道气流的低频振荡，其振荡周期、强度与热源的振荡周期、强度有关。结果还进一步表明，澳洲低频热源可激发出扰动的北传，从而引起北半球副热带环流、副热带西风急流的低频振荡，澳洲夏季风活跃后     

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探索了利用NDVI研究作物生育期的方法，对黄淮海冬麦区的返青期、抽穗期、成熟期进行了估测，并利用地面实际观测资料进行了验证。结果表明，NDVI数据对大范围农作物生育期监测是可行的。冬小麦遥感反青期由南到北依次推迟，符合春季绿波由南到北推移规律。对冬小麦遥感生育期年际变化分析表明，黄淮海平原返青期变化相对较大，而抽穗期和成熟期变化较小。根据历年月平均温度与返青期分析，冬小麦返青日期与2月份平均温度密切相关。对于局部地区，利用5d合成1km分辨率数据，且按农业生态分区分别制定生育期判别标准，估测效果将更好。     

北疆冬季降水异常与前期环流特征的相关分析

用相关分析法计算了北疆冬季降水与前期各月北半球500hPa平均高度场的相关系数，选择相关好的域计算了北疆冬季降水异常年份对应的前期相关月的500hPa距平场，结果表明当年9月欧洲脊的强弱及新疆上空急锋锋区的位置与前冬降水异常有一定的相关，6月北欧-极区冷空气的强度及12月西西伯利亚脊的位置和强弱与后冬降水异常有一定的相关。     

桂林冷冬和暖冬的环流特征分析

采用计算距平积温的方法 ,对桂林 195 7- 1999年冬季各月的旬平均气温进行统计 ,确定冷、暖冬年的标准 ,找出 7个暖冬年 ,9个冷冬年 ,并对这些年冬季的环流特征进行对比分析 ,找出造成桂林冷冬或暖冬的主要环流特征     

Water status in winter wheat grown under salt stress

1 IntroductionSalinization is one of the major problems in arid and semi-arid regions in relation to land use and in particular to agricultural production[1]. Excessive salinity leads to toxicity in crops and reduction of the availability of water to crops, by reducing the osmotic potential of the soil solution[2]. Movement of soil water induces solute transport, and solutes are transferred towards the ground surface by the upward soil-water movement caused by evaporation, resulting in an accu…     

加拿大东海岸冬季风暴的分析

利用加拿大大气环境局第二次冬季风暴观测（简称ＣＡＳＰⅡ）的部分资料，对加拿在东海岸冬季风暴的发生，发展情况进行了分析，结果表明，大多数风暴能达到爆发性发展程度，并对其中一个形成眼区的强风暴例子做了进一步讨论。     

1995年世界气候概况

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用气象卫星资料监测冬麦长势和估测产量的研究

利用１９９２、１９９３年的气象卫星资料，分析植被指数与甘肃省冬麦区３３个县市冬麦产量的关系，发现绿峰植被指数与产量存在极好的相关性。另外，从预测产量的角度和预报时限要求出发，可用４月中下旬累积植被指数预测冬麦产量，并给出了预报方程。