Modelling the biological half-life and seasonality of ¹⁴C in Fucus vesiculosus from the east coast of Ireland: implications for the estimation of future trends

Radiocarbon levels were recorded in Fucus vesiculosus samples collected on a monthly basis over a three-year period at a site on the east coast of Ireland. The resulting data was analysed using a numerical model which estimates the transit times from the Sellafield plant to the sampling location, and the mean availability time of ¹⁴C in seaweed. With the inclusion of a model parameter allowing for seasonal variability in uptake by the Fucus, good correlation was observed between the predicted and measured concentrations. Future temporal trends of ¹⁴C Fucus concentrations along the eastern Irish coastline were modelled with the application of three possible prospective discharge scenarios, predicting ¹⁴C Fucus concentrations to reduce to ambient background levels within 2.5-years of discharges being set to zero. Such projections may prove helpful in assessing the consequences of discharge management and policy making in the context of the OSPAR convention.     

Ice raft formation, sediment load, and theoretical potential for ice-rafted sediment influx on northern coastal wetlands

Ice rafting is an important secondary sedimentation process that redistributes sediment form tidal flats, channel beds, and ponds to the vegetated marsh surface in northern temperate climates. Source location of ice-rafted sediment is identifiable based on distinct sediment properties. In New England salt marsh systems, ice raft thickness and entrained sediment load vary both during the season and interannually as a function of severity and duration of winter conditions; however, 97% of ice rafts carry measurable sediment loads. Thick rafts move sand or peat up to 100 m from source areas, whereas thinner rafts tend to transport mud still further onto the marsh platform, sometimes reaching the upland border. Based on these observations, we present relationships defining the theoretical sediment-carrying potential of ice rafts as well as empirical parameterizations for ice-rafted sediment with respect to ice volume. Our results suggest that ice-rafting deposits a volume of sediment contributing up to 5% of annual vertical accretion, an important input in a region where rates of vertical accretion barely compensate for sea-level rise. We provide conceptual models of ice-raft formation and sediment entrainment linking these processes to the general geomorphic evolution of northern temperate marshes, which must be understood in light of the modern acceleration in rates of sea-level rise.     

南京市城市不同功能区PM10和PM2.1质量浓度的季节变化特征

使用Anderson-Ⅱ型9级撞击采样器测量了南京市鼓楼商业区、江北工业区、钟山风景区和宁六高速公路交通源春、夏、秋三季的大气气溶胶质量浓度。分析结果表明:南京市PM_2.1和PM₁₀的质量浓度存在明显的季节变化,秋季>春季>夏季;ρ_PM10春季为167.47 μg/m³,夏季为 85.99 μg/m³,秋季为238.99 μg/m³;ρ_PM2.1春季为59.66 μg/m³,夏季为42.80 μg/m³,秋季为100.15 μg/m³。不同季节中ρ_PM10和ρ_PM2.1均存在较好的相关性,夏季相关性最好,相关系数为0.952;秋季次之,相关系数为0.783;春季相对较差,相关系数为0.613。城市不同功能区之间ρ_PM2.1和ρ_PM10的质量浓度值差异很大,交通源>工业区>商业区>风景区。城市不同功能区的质量浓度谱分布基本一致,均为双峰型分布,峰值分别位于0.43~0.65 μm/m³和9.0~10.0 μm/m³。南京市春、夏、秋三个季节大气粒子质量浓度谱为双峰分布,粒子主要集中在0.43~3.3 μm/m³的粒径段。江北工业区ρ_PM10和ρ_PM2.1质量浓度的相关系数为0.814,略高于鼓楼商业区的0.797。     

Creating usable science: Opportunities and constraints for climate knowledge use and their implications for science policy

In the past several decades, decision makers in the United States have increasingly called upon publicly funded science to provide “usable” information for policy making, whether in the case of acid rain, famine prevention or climate change policy. As demands for usability become more prevalent for publicly accountable scientific programs, there is a need to better understand opportunities and constraints to science use in order to inform policy design and implementation. Motivated by recent critique of the decision support function of the US Global Change Research Program, this paper seeks to address this issue by specifically examining the production and use of climate science. It reviews empirical evidence from the rich scholarship focused on climate science use, particularly seasonal climate forecasts, to identify factors that constrain or foster usability. It finds, first, that climate science usability is a function both of the context of potential use and of the process of scientific knowledge production itself. Second, nearly every case of successful use of climate knowledge involved some kind of iteration between knowledge producers and users. The paper argues that, rather than an automatic outcome of the call for the production of usable science, iterativity is the result of the action of specific actors and organizations who ‘own’ the task of building the conditions and mechanisms fostering its creation. Several different types of institutional arrangements can accomplish this task, depending on the needs and resources available. While not all of the factors that enhance usability of science for decision making are within the realm of the scientific enterprise itself, many do offer opportunities for improvement. Science policy mechanisms such as the level of flexibility afforded to research projects and the metrics used to evaluate the outcomes of research investment can be critical to providing the necessary foundation for iterativity and production of usable science to occur.     

1976-2017年乌鲁木齐市升温对季节的影响

本文采用乌鲁木齐市国家基准气象站463站的逐日平均、逐日最低和逐日最高气温资料,分析了乌鲁木齐市1976-2017年气温变化趋势和对四季的影响。结果表明：乌市气温有明显上升的趋势,年平均气温的线性增温速率为0.50℃/10a,1997年出现了最暖年,1976年以来最暖的10 a均出现在20世纪末至今;年平均最低气温升温趋势最为明显,倾向率为0.77℃/10a,上升速率约是年平均最高气温的2.5倍;气温上升导致春季和夏季的开始日期提前明显、秋季和冬季开始日期有推后的趋势,使得夏季明显延长,延长率为5.9d/10a,近42a来共增加25d,其他季节则有不同程度的缩短,其中冬季缩短最为明显,缩短率为-3.6d/10a,近42a来共缩短了15d;各季节开始日期不仅与年平均气温相关性很好,且开春期、入夏期分别与3月和6月平均气温显著负相关;入秋期与入冬期分别与9月和11月气温呈显著正相关;夏季和冬季的长度也与年平均气温显著相关,当年平均气温每上升1℃时,夏季将延长6d,而冬季则会缩短7 d。     

稻田土壤中甲烷产生率的实验研究

本实验旨在研究稻田土壤中甲烷产生率对稻田CH_4排放的影响.观测结果表明:土壤各深度的甲烷产生率有很大的变化范围(1—4639ng·h~(-1)·g~(-1)d.w.).主要的甲烷产生区域是7—17cm深的土壤层,其中以13cm深的土壤层上的生成速率最大.土壤中甲烷产生率与稻田CH_4排放率在水稻生长的某些阶段有较好的相关性,但它的季节变化却不能与排放的季节变化完全耦合.在水稻生长期,土壤中甲烷产生率随时间而增大,并在8月份水稻收割前达到最大,其日平均值在38—767 ng·h~(-1)·g~(-1)d.w.间变动.稻田土壤中甲烷产生率也存在日变化,一般在下午达到最大值,但却没有发现它与土壤温度有明显的相关关系.在不同施肥及水稻品种的稻田土壤中也观测到不同的甲烷产生率.在土壤中产生的甲烷最多只有28.8％被排放到大气中,而其余多于71.2％的则被氧化在土壤中.     

Conversion characteristics between barotropic and baroclinic circulations of the sah in its seasonal evolution

In the context of 1958-1997 NCEP/NCAR re-analyses, the South Asia high (SAH) was divided into two components, barotropic and baroclinic, the former based on mass weighed vertical integration and the latter on the difference between the measured circulation and the barotropic component counterpart, where upon the barotropic and baroclinic circulation conversion features were addressed of the research SAH during its seasonal variation. Evidence suggests that i) in summer (winter), the SAH is a thermal (dynamical) system, with dominant baroclinicity (barotropicity), either of the components accounting for approximately 70% of the total contribution; ii) as time progresses from winter to summer, accompanied by the barotropic SAH evolving into its baroclinic analog, the SAH is moving under the “thermal guidance” of its baroclinic component circulation, suggestion that the component circulation precedes the system itself in variation; iii) the reversal happens when it goes from summer to winter, with the SAH displacement under the “dynamic steering” of its barotropic component circulation.     

中国夏季降水的组合统计降尺度模型预测研究

现阶段的动力气候模式尚不能满足东亚区域气候预测的实际需求,这就需要动力和统计相结合的方法,将动力模式中具有较高预测技巧的大尺度环流信息应用到降水等气象要素的统计预测模型当中,以改善后者预测效果。本文中所介绍的组合统计降尺度模型,可将动力气候模式预测的大尺度环流变量和前期观测的外强迫信号作为预测因子来预测中国夏季降水异常。交叉检验结果显示,组合统计降尺度预测模型的距平相关系数较原始模式结果有较大提高。在实时夏季降水预测中,2013～2018年平均的预测技巧相对较高,趋势异常综合检验（PS）评分平均为71.5分,特别是2015～2018年平均的PS评分预测技巧达到72.7分,总体上高于业务模式原始预测和业务发布预测的技巧。该组合统计降尺度模型预测性能稳定,为我国季节预测业务提供了一种有效参考。     

青藏高原五道梁地区大气浑浊度的观测和分析

利用１９９３年８月～１９９５年５月青藏高原五道梁地区ＭＳ—１２０型太阳光度表的观测资料,分析了该地区大气浑浊度的特征。结果表明：（１）该地区上空的大气洁净,受人类活动影响很小,其浑浊度状况与珠峰地区的绒布寺（５０００ｍ）及南极地区有相似的量级,但比城市地区要小一个数量级。（２）本区的大气浑浊度具有较明显的季节变化特征,但日变化不明显。（３）大气浑浊度不仅与地面大气状况（地面风向、风速、降水等气象因子）关系密切,而且还与测站的地理环境等因素有关。     

涡分辨率全球海洋环流模式LICOM模拟的吕宋海峡流场的季节变化

分析了一个1/10°的涡分辨率全球环流模式LICOM(LASG/IAP Climate system Ocean Model)对吕宋海峡附近海洋环流的模拟能力。结果表明,模拟的吕宋海峡附近上层环流及输运具有明显的季节变化特征,除6月是东向净流出外,其余月份均为西向流入,冬季流量最大。年平均流量在-3.76 Sv(1 Sv=106 m3/s),其中上层(600 m以上)流量起主要贡献,为-3.60 Sv,与目前已有的研究结果基本一致。南海通过6个海峡完成与外界的水交换,其中吕宋海峡和巴拉巴克海峡是大洋水进入南海的主要通道,其余海峡均以流出为主,流出量最大的是台湾海峡(1.99 Sv),其次是卡里玛塔海峡(1.03 Sv)。进一步分析表明,由季风引起的埃克曼输送量约占吕宋海峡流量的11%,而由季风引起的吕宋海峡压力梯度形成的西向的地转流对吕宋海峡的输运起支配作用。作为黑潮源头的太平洋北赤道流流量对吕宋海峡输运的季节变化也有一定影响。