Uncertainty in Simulating the Impact of Cultivar Improvement on Winter Wheat Phenology in the North China Plain

The phenology model is one of the major tools in evaluating the impact of cultivar improvement on crop phenology. Understanding uncertainty in simulating the impact is an important prerequisite for reliably interpreting the effect of cultivar improvement and climate change on phenology. However, uncertainty induced by different temperature response functions and parameterization methods have not been properly addressed. Based on winter wheat phenology observations during 1986–2012 in 47 agro-meteorology observation stations in the North China Plain (NCP), the uncertainty of the simulated impacts caused by four widely applied temperature response functions and two parameterization methods were investigated. The functions were firstly calibrated using observed phenology data during 1986–1988 from each station by means of two parameterization methods, and were then used to quantify the impact of cultivar improvement on wheat phenology during 1986–2012. The results showed that all functions and all parameterization methods could reach acceptable precision (RMSE < 3 days for all functions and parameterization methods), however, substantial differences exist in the simulated impacts between different functions and parameterization methods. For vegetative growth period, the simulated impact is 0.20 day (10 yr)^–1 [95% confidence interval:–2.81–3.22 day (10 yr)^–1] across the NCP, while for reproductive period, the value is 1.50 day (10 yr)^–1 [–1.03–4.02 day (10 yr)^–1]. Further analysis showed that uncertainty can be induced by both different functions and parameterization methods, while the former has greater influence than the latter. During vegetative period, there is a significant positive linear relationship between ranges of simulated impact and growth period average temperature, while during reproductive period, the relationship is polynomial. This highlights the large inconsistency that exists in most impact quantifying functions and the urgent need to carry out field experiment to provide realistic impacts for all functions. Before applying a simulated effect, we suggest that the function should be calibrated over a wide temperature range.     

Statistics of the Z–R Relationship for Strong Convective Weather over the Yangtze–Huaihe River Basin and Its Application to Radar Reflectivity Data Assimilation for a Heavy Rain Event

The relationship between the radar reflectivity factor(Z) and the rainfall rate(R) is recalculated based on radar observations from 10 Doppler radars and hourly rainfall measurements at 6529 automatic weather stations over the Yangtze–Huaihe River basin. The data were collected by the National 973 Project from June to July 2013 for severe convective weather events. The Z–R relationship is combined with an empirical qr–R relationship to obtain a new Z–qr relationship, which is then used to correct the observational operator for radar reflectivity in the three-dimensional variational(3 DVar) data assimilation system of the Weather Research and Forecasting(WRF) model to improve the analysis and prediction of severe convective weather over the Yangtze–Huaihe River basin. The performance of the corrected reflectivity operator used in the WRF 3 DVar data assimilation system is tested with a heavy rain event that occurred over Jiangsu and Anhui provinces and the surrounding regions on 23 June 2013. It is noted that the observations for this event are not included in the calculation of the Z–R relationship. Three experiments are conducted with the WRF model and its 3 DVar system, including a control run without the assimilation of reflectivity data and two assimilation experiments with the original and corrected reflectivity operators. The experimental results show that the assimilation of radar reflectivity data has a positive impact on the rainfall forecast within a few hours with either the original or corrected reflectivity operators, but the corrected reflectivity operator achieves a better performance on the rainfall forecast than the original operator. The corrected reflectivity operator extends the effective time of radar data assimilation for the prediction of strong reflectivity. The physical variables analyzed with the corrected reflectivity operator present more reasonable mesoscale structures than those obtained with the original reflectivity operator. This suggests that the new statistical Z–R relationship is more suitable for predicting severe convective weather over the Yangtze–Huaihe River basin than the Z–R relationships currently in use.     

基于特征空间匹配的激光雷达点云配准算法

针对传统基于特征的粗配准效率低、误匹配较多的不足,提出一种基于特征空间匹配的配准方法。利用简化的PointNet模型实现特征空间的提取,以优化的点云PPF信息作为输入,根据提取的特征空间向量计算欧氏距离以筛选匹配点,通过RANSAC剔除误匹配点对完成粗配准,利用ICP实现精配准。实验结果表明,本文算法相比FPFH和SHOT算法与ICP结合可有效提升配准效率,且配准结果的均方根误差较小。     

STUDY ON THE GENESIS OF ASYMMETRICAL DISTRIBUTION CHARACTERISTICS OF PRECIPITATION ASSOCIATED WITH THE TYPHOON HAITANG (2005) FROM THE VIEW OF ATMOSPHERIC FACTOR

The distribution of precipitation field from the typhoon Haitang (2005) during its landing on Fujian province shows obvious asymmetric feature. Based on the NCEP/NCAR FNL (Final Analysis) data, this study reveals the contributions of atmospheric factor to the asymmetrical distribution characteristics of precipitation associated with the typhoon, through the analysis of water vapor condition, vertical ascending motion condition, the calculation of the dry Q vector and its decomposition, and adiabatic heating in the air column of 1000hPa -600hPa (lower atmosphere) and 500hPa-100hPa (upper atmosphere). The results are as follows: (1) In the lower atmosphere, the humidity on both sides of typhoon path can be equivalent, while it is more wet on the right side than left in the upper atmosphere, which obviously presents asymmetric distribution characteristics. (2) Both range and intensity of the vertical motion on the right side are wider and stronger than counterparts on the left side no matter in the lower or upper atmosphere. (3) In the upper atmosphere, forcing role of atmosphere in vertical upward motion on the right side of typhoon path is the same as that on the left, while it is significantly different in the lower atmosphere, which is significantly broader in scope and stronger in the intensity, along with obvious asymmetric distribution characteristics. In addition, the further analysis of the Q vector decomposition indicates that the forcing effect of mesoscale weather systems on vertical upward motion is stronger than that of large scale weather systems in the lower atmosphere. (4) The adiabatic heating always exists on both lower and upper atmosphere, and the range and intensity of the adiabatic heating forcing showed asymmetric distribution on both lower and upper atmosphere. (5) In a summary, the upper atmosphere humidity conditions, the forcing role of lower atmosphere in vertical upward motion, especially, to mesoscale weather system, and adiabatic heating in the lower atmosphere, all show similar asymmetric distribution characteristics to that of precipitation field from the typhoon Haitang (2005), that is to say, the atmospheric factors as mentioned above are all contributed to genesis of the asymmetric distribution characteristics of precipitation.     

基于模糊评价的福建沿海水质卫星遥感监测模型

卫星遥感技术对于开展连续、实时、大尺度的海洋水质状况监测具有明显优势。该文充分利用卫星遥感的标准算法模型和半分析算法模型分别反演得到叶绿素a、颗粒状有机碳、黄色物质和透明度等海洋生态参数,并选取与福建沿海海水受污染程度密切相关的溶解氧、化学耗氧量、无机氮和活性磷酸盐作为海洋水质的评价因子,通过建立海洋生态参数与海洋水质评价因子两者之间的统计关系模型,在海洋水质综合评价中引入模糊综合评价法,最终建立一套基于卫星遥感和模糊评价的海洋水质监测模型,并利用2009—2013年福建沿海同步获取的海洋水质现场实测数据对模型的反演精度进行验证。结果表明:使用该监测模型开展对福建沿海海洋水质卫星遥感监测是可行的,监测准确率为81%,具有较好的业务化应用前景,由于模型对于Ⅳ类海洋水质监测的准确率明显高于Ⅱ类和Ⅲ类海洋水质,因此,比较适合于福建近岸海域的海洋水质监测。     

珠海凤凰山陆气相互作用与碳通量观测塔的基本观测及晴天主要观测量的日变化特征

珠海凤凰山地处北回归线以南,森林植被覆盖率达90%,植被类型为南亚热带常绿阔叶林群落,是岭南地区典型的城市或村庄周边的再生森林,我们选择在凤凰山麓森林冠层较为平缓的低矮坡地建立了陆-气相互作用和碳通量的观测铁塔塔站。本文详细介绍了观测塔的地理环境、初步的仪器布设和基本观测,并利用已获得的资料分析了旱季典型晴天主要观测量的日变化特征。太阳总辐射及其分光辐射和反射辐射的日变化都是比较常规的中午最高的对称结构;冠层接收到的长波辐射比向上长波辐射低;气温日变化的峰值比太阳辐射滞后,白天达到最高值前的气温是低层高于高层,达到最高值后到落日前气温陡然下降,夜晚的气温是低层低于高层。相对湿度凌晨最大,下午最小,夜晚是低层相对偏湿,白天正好相反;11月份,珠海地区盛行旱季的偏北季风,有明显的海陆风的作用,白天的海风较强,夜晚的陆风较弱;森林冠层向大气释放的感热和潜热的量值基本相当,潜热基本为正;感热白天为正,夜晚基本为负;森林冠层吸收的二氧化碳的最高值出现在午后,此时空气中水汽浓度达到最低,向大气释放的二氧化碳在日出后的清晨最大,此时空气中的二氧化碳浓度达到最大,同时空气密度也最大;由于森林冠层高、密度大,土壤湿度基本没有日变化;表层土壤温度日变化的振幅随土壤深度加深而变小,土壤热流的变化是下午高,清晨低。本文还发现了一些值得深入探讨的现象,需要以后根据充沛的资料分析论证。     

基于相位导数的GBSAR影像自适应滤波算法研究

GBSAR影像由于受到自身和周围环境的影响,在影像中易产生噪声,如不及时滤除噪声,将对后续的处理造成很大的影响,以往的滤波算法大部分是基于影像的幅度信息,没有将相位信息考虑在内,没达到真正滤波的效果。本文提出一种基于相位导数的算法对GBSAR影像进行滤波处理,并将结果与Lee函数滤波结果进行对比,结果表明基于相位导数的算法在GBSAR影像中具有良好的去噪效果,对GBSAR影像的后续处理提供了一种新的方法。     

杭州湾南部主水道内温度、盐度、潮流的变化特征

本文基于船载及锚定ADCP、CTD观测,获得了大、小潮时的温度、盐度、浊度、潮位、流速等观测数据,研究杭州湾南部的一个主要弯曲航道——螺头水道内的潮流动力学特性。螺头水道水深超过100 m、最大潮差大于2.5 m。涨潮时,强潮流速出现在水道北岸,落潮时,强潮流速出现在水道南岸,最大流速值分别为约2 m/s和1.8 m/s。受压强梯度、密度梯度、科氏力和离心力影响,涨落潮过渡时在水道的横断面产生较为明显的环流。夏季存在较弱的层化现象,深水处受环流的影响,盐度、温度的混合较强。锚定观测数据表明,温度、盐度的变化频率与潮流的变化频率相似,但存在高于M2分潮频率的谱峰值。因此,笔者认为潮流与横向环流的相互作用,可能导致更高频率的盐度和温度变化。     

基于AMMI模型分析凡纳滨对虾选育家系基因型与环境互作效应

为选育出具有广适性和适应某一特定环境的凡纳滨对虾(Litopenaeus vannamei)家系,实验采用巢式交配设计建立了凡纳滨对虾选育家系,并从中选出7个体质量性状优良的家系进行主效可加互作可乘模型(AMMI)分析,得出7个凡纳滨对虾选育家系体质量基因型与环境互作效应。结果表明,凡纳滨对虾7个家系的基因型与环境互作效应(G×E)达极显著水平(P<0.01);G×E效应平方和占总平方和的20.608%,家系效应平方和占总平方和的12.814%,环境效应平方和占总平方和的64.289%,说明家系体质量差异受环境效应影响显著,此外环境与基因型互作效应对体质量也存在影响,且影响力大于家系效应;基于双标图AMMI模型分析和稳定性参数分析,家系G2产量较高,为12.90 g,但G2对环境的选择能力以及依赖性较强,不适合广泛推广;G6产量为9.00 g,与G2相比虽然产量稍低,但其家系稳定性较高,对环境选择能力以及依赖性较弱,适合在多种类型环境下养殖,因此G6为中产、稳定、广适应性的家系,其基因型适合新品系的选育及推广;通过AMMI模型双标图功能形态分析,G11在E1环境中体质量最高产,适合与在E1环境下推广;G2在E2环境中最高产,适合在E2环境下推广;G5在E3环境中体质量最高产,适于在E3环境下推广。     

北斗三频与双频相对定位性能分析

对北斗三频与双频相对定位的性能进行分析。鉴于目前对北斗三频相对于双频的优势分析较少,本文利用北斗及GPS实测数据在定位精度与质量上,分析对比了二者的性能且对北斗频率的变化对定位产生的影响进行了分析。同时区分GEO、IGSO、MEO不同类型卫星对整周模糊度解算的影响进行了实验分析。