Analysis of the Trends of Thunderstorms in 1951–2007 in Jiangsu Province

Based on the 1951–2007 thunderstorms in Jiangsu, a study is conducted for their climate trends, periodicity, spatiotemporal patterns, and the distributions of the first and last days of the thunderstorms at different guarantee rates (GRs) using climate tendency rate, wavelet analysis, and GR for diagnosis. Results suggest that the inter-annual number of thunderstorm days (TSDs) exhibits a decreasing trend in this province. The trend is displayed mainly in the decreasing TSD number in summer and autumn except in spring, when the variation is not significant in the study period. In this province, the TSD number declines by ~2 days per 10 years. On an inter-annual basis, the pronounced positive departures of the number take place chiefly in the early 1960s, the late 1960s to the early-mid-1970s, the late 1980s, and the late 1990s compared with the negative anomalies dominant in the late 1970s to the mid-1980s, the mid-to-late-1990s, and the late 1990s to 2007. There are vast differences in the initial and ending days at diverse GRs in different areas of the province. At 50% GR, the earliest (last) days occur from mid-March to early April (early to late September) while at 80% GR, the initial (last) days are from late March to early May (early to late October). For the distribution of periods, the periods >8–10 years are relatively stable for the entire province. Based on 1951–2007 period analysis, the region north (south) of the Huaihe River experiences TSDs less (more) than normal days in recent years.     

珠江三角洲城市群对夏季降雨影响的初步研究

利用TRMM 2A25卫星降水数据和CMORPH同化数据对珠三角洲地区的降水分布特征进行了探讨,观测表明：珠三角城市群区域总体处于降水的低值中心,且对流降雨的低值中心尤为明显;同时近10 a珠三角核心城市区域降雨有减少的趋势,这种降水减少的趋势可能与珠三角城市化效应有关。本文进一步利用WRF模式模拟分析了珠三角城市群发展对夏季降雨的影响,结果表明珠三角城市化使得该区域降雨减少,其原因为城市化使得地表的蒸发减弱及其大气中的水分供应减少,同时也抬升了珠三角区域边界层高度相应增强了低层大气水汽垂直混合。     

基于雷达回波最大重叠率的一种临近降水预报方法

基于天气雷达的临近降水预报是雷达短时预报业务系统的重要组成部分,本文在回顾雷达临近降水预报技术发展的基础上,充分考虑新一代天气雷达高时间、空间分辨率的优点,提出两个相邻时刻雷达回波具有最大重叠率的移向、移速是与降水系统整体的移向、移速密切相关的论点,再用此移向、移速对当前雷达回波进行平移,最后采用九点平均的回波生消模型...     

大连市蒸发量变化特征及影响因子

采用线性倾向估计法和累积距平曲线和完全相关系数法,分析了1951—2001年大连市蒸发量变化特征及其影响因子。结果表明：大连市年蒸发量呈增加趋势,其中夏季蒸发量的增加趋势最为明显,其次为春季,秋季和冬季蒸发量增加趋势不显著;年蒸发量的增加主要来自夏季的贡献。大连市年及四季蒸发量与日照时数、平均地面温度、平均气温日较差和平均风速总体上呈正相关,与平均相对湿度呈负相关。平均相对湿度减小和平均地面温度上升是大连市蒸发量增加的主要原因。     

中国区域蒸发潜力不均性发展趋势及其气候成因分析

气象台站20 cm蒸发皿观测资料自然正交分解显示,1980～2000年中国区域气温显著增加期间,长江中游至河套、东北等区域地表年蒸发潜力呈增加趋势;相反在长江以南、东部和西南等地区年蒸发潜力呈下降趋势.辐射观测资料分析结果表明,自20世纪70年代中国区域太阳入射能整体呈下降趋势,因此对于蒸发潜力增加的地区,太阳辐射产生...     

纳米铁还原脱氮动力学及其影响因素

饮用水中硝酸盐(NO3-)对人体健康有危害。为了去除水溶液中NO3-,在实验室制得纳米铁颗粒。它的粒径为20～40 nm,比表面积(BET)为49.16 m2/g。本研究通过批实验考察了纳米铁对NO3-还原脱氮动力学性质和影响NO3-脱氮快慢的主要因素,如反应pH、纳米铁投加量和NO3-起始浓度。实验结果表明,pH越低越有利于NO 3-还原。在一定范围内,NO 3-还原速率随纳米铁投加量增加而增大,而随NO 3-起始浓度升高而降低,反应遵循准一级反应动力学方程,表面吸附和氧化还原反应是纳米铁对NO3-脱氮的主要去除机理。纳米铁对NO3-还原过程中可能反应的途径进行了讨论,NO3-还原产物取决于反应条件。在本研究条件下,纳米铁对NO3-脱氮的最终产物主要为NH4+-N而不是N2,必须进行更多的研究来解决这一问题。     

末次冰消期以来东海内陆架沉积速率及其气候环境响应

对位于东海内陆架浙-闽沿岸泥质带的EC2005孔岩性、粒度以及AMS14C年代进行了分析,着重探讨了研究区自末次冰消期以来的沉积速率变化,划分出4个大的沉积阶段和4次快速沉积事件.千年时间尺度上大的沉积阶段主要受控于物源供应、海平面变化以及可容空间的大小.百年时间尺度上揭示的4次快速沉积事件主要受控于东亚冬季风的增强或...     

Linking invertebrate burrow distributions (neoichnology) to physicochemical stresses on a sandy tidal flat: implications for the rock record

Invertebrate burrow distributions (neoichnology) across a modern tidal flat are presented as an analogue for interpreting the ichnology of palaeo‐tidal‐flat successions. Burrow distributions are linked to physical and chemical (physicochemical) stresses to establish the main controls on the distribution of biosedimentary structures. Across the tidal flat, there is clear heterogeneity in both the diversity of traces and the intensity of burrowing. This heterogeneity reflects a myriad of physicochemical stresses, with the sedimentation rate dominating burrow distributions. Across all substrates, the total area occupied by organisms rarely exceeds 3% of the tidal‐flat surface, and is commonly <1%; this equates to a bioturbation index value of one. To reach bioturbation index values of two to six, sediments must be available to biogenic reworking and/or recolonization. With an increasing sedimentation rate, substrates are rapidly buried and re‐exposed, which limits the time when a substrate is available to colonization. For palaeo‐ichnological studies, this research presents several key results. (i) Burrow cross‐cutting relationships in tidal‐flat successions commonly reflect natural heterogeneities in the areal distribution of infaunal communities, rather than infaunal tiering. (ii) Ichnofabric analysis of palaeo‐tidal flats with a high sedimentation rate would yield fabrics that reflect heterogeneities in the areal distribution of infaunal communities rather than variability in the physicochemical stresses of the environment. (iii) The composite trace‐fossil assemblage of tidal flats cannot be attributed to a single ichnofacies, but instead comprises elements typical of multiple ichnofacies. (iv) The main controls on trace assemblages across tidal flats in fully marine settings are sedimentological and include the sedimentation rate and, to a lesser extent, grain size.     

坡缕石粘土固定辣根过氧化酶处理硝基酚废水

以坡缕石粘土、淀粉、水玻璃为原料,研究了固定化酶载体的制备工艺,探究了固定化酶载体在辣根过氧化酶(HRP)降解硝基酚废水中的作用,并探讨了反应时间、酶浓度、H2O2及硝基酚浓度对降解效果的影响。结果表明,固定化酶载体的最佳制备工艺为:水玻璃12%,淀粉20%,煅烧温度550℃,煅烧时间2 h;固定化酶对硝基酚的去除效果明显高于原酶;固定化酶去除水中硝基酚的最佳反应条件为:反应时间1.5 h,加酶量150 U,H2O2浓度0.12%,硝基酚浓度100 mg/L;固定化酶重复使用7次后对硝基酚的去除率仍高于60%。     

黄土的湿陷性与击实试验指标关系研究

进行了黄土的击实试验,提出了击实率的概念,拓展了CART(classification and regression trees)决策树算法的功能。将其用于相关性挖掘,进行了原状黄土湿陷性与击实率等指标的相关性挖掘,结果表明,击实率与湿陷系数具有相关性,击实率与最优含水率状态的击实率呈显著负相关性。根据试验及分析结果提出黄土在击实过程中的变形特性可反映黄土的湿陷性,黄土的击实效果同其湿陷性具相关性。这一研究为黄土湿陷性的评价提出了一条新的思路,同时成果具有实用性。