河西走廊东部冬季沙尘暴的典型个例及气候特征分析

应用1971—2016年河西走廊东部代表站的地面观测资料、NCEP 2.5°×2.5°月均地面至300 hPa高空资料,2006—2016年民勤逐日07和19时每隔10 m加密高空资料,分析了近45年河西走廊东部冬季沙尘暴天气的年际变化特征。同时选取2016年11月两次沙尘暴天气过程从天气学成因、物理量场及近地面边界层特征等方面进行了诊断分析。结果表明:近45年河西走廊东部冬季沙尘暴日数呈减少趋势,产生大风沙尘天气的主要原因不仅与大型冷暖空气强度及环流形势有关,还与冷锋过境时间、日变化、近地层风速和干湿程度关系密切。夜间至早晨近地面逆温厚且强,大气层结稳定,削弱沙暴强度,而午后到傍晚,逆温薄而弱,大气层结不稳定性强,加强了动量下传和风速,增强沙暴强度。近地层越干,风速越大,沙暴越强。     

2017-2018年冬季黑龙江省气温异常成因分析

2017-2018年冬季全省平均气温为-19.7℃,较历年同期偏低2.2℃,为1981年以来的第3位,仅次于2000年和2012年。本文利用NCEP再分析资料,对2017-2018年黑龙江省冬季气温异常成因进行分析,结果表明大气环流的异常是造成黑龙江省冬季气温异常偏低的直接原因。东亚季风环流系统表现为:东亚冬季风强度偏强,西伯利亚高压偏强,500hPa东亚大槽异常偏深。分析下垫面外强迫因素,2017-2018年赤道中东太平洋出现拉尼娜事件,分析显示拉尼娜事件发生可能导致冬季风偏强,从而也是造成全省气温偏低的主要原因之一。     

Analysis of the Decadal and Interdecadal Variations of the East Asian Winter Monsoon as Simulated by 20 Coupled Models in IPCC AR4

Using the output data of 20 coupled climate models used in IPCC AR4 and observational data from NCEP, the capability of the models to simulate the boreal winter climatology of the East Asian sea level pressure, 850-hPa wind, and surface air temperature; the decadal variations of the East Asian winter mon- soon (EAWM) intensity and EAWM-related circulation, and the interdecadal variations of EAWM-related circulation are systematically evaluated. The results indicate that 16 models can weakly simulate the declin- ing trend of the EAWM in the 1980s. More than half of the models produce relatively reasonable decadal variations of the EAWM-related circulation and the interdecadal di?erences of EAWM-related circulation between the boreal winters of 1960-1985 and 1986-1998, including the weakened Siberian high, Aleutian low, and East Asian trough, the enhanced Arctic oscillation and North Pacific oscillation, and a deepened polar vortex. It is found that the performance of the multi-selected-model ensemble in reproducing the spatial dis- tribution of the variations is encouraging, although the variational amplitudes are generally smaller than the observations. In addition, it is found that BCCR_BCM2.0, CGCM3.1_T63, CNRM_CM3, CSIRO_MK3.0, GISS-ER, INM_CM3.0, and MRI_CGCM2.3.2 perform well in every aspect     

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     

地表太阳紫外辐射强度变化对小麦影响的初步研究

研究表明，紫外辐射强度的增大，对小麦的生长、生理活动及产量的形成，均有不同程度的影响。紫外辐射增加的这些效应又和小麦的各种其他环境条件（如光、热、水等）存在着一定的关系，当某些环境条件处于胁迫状态时，则可能对紫外辐射的植物效应产生一定程度的遮掩作用，减弱其抑制强度。     

厄尼诺与东亚暖冬的数值模拟

应用全球大气环流谱模式（ＥＣＨＡＭ３），根据实际观测的海面温度资料，从１９７９年１月１日长期积分至１９９２年。模拟了厄尼诺年的东亚暧冬和弱冬季风现象。对于模拟的结果进行了初步讨论。     

利用NOAA NDVI数据集监测冬小麦生育期的研究

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。     

近40a江苏省冬季气温异常的演变及其涨气背景场特征

通过1961－1998年江苏省11个站点冬季平均气温的EOF分析，探讨江苏省冬温异常的演变特征，并分析其同期及前期500hPa高度距均，海温距平场的特征，指出冬季异常冷年，同期与前期500mPa高度距平场主要表现为亚洲－太平洋地区阻塞形势发展，经向环流加强，同期至前期6个月赤道东太平洋海温为持续负距平。而暖冬同期与前期500hPa高度距平场的特征特征是，西太平洋海温为持续负距平。而暖冬同期与前期500hPa高度距平场的特征是，西太平洋副高势力较强，亚欧大陆中高纬 纬向环流占优势，同期赤道东太平洋海温具有厄尔尼诺的特征，但前期赤道东太平洋海温距平具有由负向正转变特征。