Which forcing factors fit? Using ecosystem models to investigate the relative influence of fishing and changes in primary productivity on the dynamics of marine ecosystems

Fishing mortality and primary production (or proxy for) were used to drive the dynamics of fish assemblages in 9 trophodynamic models of contrasting marine ecosystems. Historical trends in abundance were reconstructed by fitting model predictions to observations from stock assessments and fisheries independent survey data. The model fitting exercise derives values for otherwise unknown parameters that specify the relative strength of trophic interactions and, in some instances, a time series anomaly for changes in primary production. We measured how much better or worse were model predictions when bottom-up forcing by primary production were added to top-down forcing by fishing. Searching for cross system patterns, the relative contribution of fishing and changes in primary production, mediated through trophic interactions, are evaluated for the ecosystems as a whole and for selected similar species in different ecosystems. The analysis provides a simple qualitative way to explain which forcing factors have most influence on modeled dynamics. Both fishing and primary production forcing were required to obtain the best model fits to data. Fishing effects more strongly influenced 6 of 9 of the ecosystems, but primary production was more often found to be the main factor influencing the selected pelagic and demersal fish stock trends. Examination of sensitivity to ecological and model parameters suggests that the results are the product of complex food-web interactions rather than simple deterministic responses of the models.     

灰霾天气期间南京气溶胶的化学组成及光学特性研究

利用2013年6月—12月灰霾天气期间南京城郊气溶胶采样结果,研究气溶胶中水溶性离子的特征和相关性;结合同期城区的大气成分逐时观测资料,分析黑碳的日变化及其与气态污染物的关系;运用光学参量计算模型(OPAC)和辐射传输模型(TUV)研究气溶胶的光学特性及辐射强迫。结果表明:发生灰霾天气时南京城郊主要大气污染物是细颗粒,其中SO2-4与NO-3是最主要的水溶性无机盐离子,NO-3/SO2-4质量比较高,呈现硫酸盐和硝酸盐混合型污染特征。黑碳浓度具有明显的日变化特征,呈双峰型结构。灰霾期间硫酸盐气溶胶在大气层顶和地面造成的平均辐射强迫分别为-10.6 W/m2和-10.8 W/m2,黑碳气溶胶在正午大气层顶和地面造成的平均辐射强迫分别为9.12 W/m2和-29.77 W/m2。     

Aerosol chemistry and the effect of aerosol water content on visibility impairment and radiative forcing in Guangzhou during the 2006 Pearl River Delta campaign

Optical and chemical aerosol measurements were obtained from 2 to 31 July 2006 at an urban site in the metropolitan area of Guangzhou (China) as part of the Program of Regional Integrated Experiment of Air Quality over Pearl River Delta (PRIDE-PRD2006) to investigate aerosol chemistry and the effect of aerosol water content on visibility impairment and radiative forcing. During the PRIDE-PRD2006 campaign, the average contributions of ammonium sulfate, organic mass by carbon (OMC), elemental carbon (EC), and sea salt (SS) to total PM_2.5 mass were measured to be 36.5%, 5.7%, 27.1%, 7.8%, and 3.7%, respectively. Compared with the clean marine period, (NH₄)₂SO₄, NH₄NO₃, and OMC were all greatly enhanced (by up to 430%) during local haze periods via the accumulation of a secondary aerosol component. The OMC dominance increased when high levels of biomass burning influenced the measurement site while (NH₄)₂SO₄ and OMC did when both biomass burning and industrial emissions influenced it. The effect of aerosol water content on the total light-extinction coefficient was estimated to be 34.2%, of which 25.8% was due to aerosol water in (NH₄)₂SO₄, 5.1% that in NH₄NO₃, and 3.3% that in SS. The average mass-scattering efficiency (MSE) of PM₁₀ particles was determined to be 2.2 ± 0.6 and 4.6 ± 1.7 m² g⁻¹ under dry (RH < 40%) and ambient conditions, respectively. The average single-scattering albedo (SSA) was 0.80 ± 0.08 and 0.90 ± 0.04 under dry and ambient conditions, respectively. Not only are the extinction and scattering coefficients greatly enhanced by aerosol water content, but MSE and SSA are also highly sensitive. It can be concluded that sulfate and carbonaceous aerosol, as well as aerosol water content, play important roles in the processes that determine visibility impairment and radiative forcing in the ambient atmosphere of the Guangzhou urban area.     

硫酸盐气溶胶直接和间接辐射气候效应的模拟研究

将大气化学模式引入到区域气候模式中，实现同步计算大气化学成分和气象要素，以中国地区1994年1、4、7、10月为研究对象，模拟了4个月的气候变化。通过分析发现，硫酸盐气溶胶的直接和间接辐射效应都使大气顶产生负的辐射强迫，使地面气温下降；间接效应的引入加剧了辐射强迫和地面降温，是一个不可忽视的重要过程，在模拟中风吹草动时考虑直接和间接效应是必须的。     

Radiative dryness index and potential productivity of vegetation in China

The Chikugo Model is used to estimate radiative dryness indexes (RDI) and net primary productivity (NPP) of vegetation zones in China by calculating cli-matic parameters. That provides the water-heat equilibrium condition, potential primary production for natural vegetation in various vegetation zones, and their geographical distribution pattern. That could be used as the basis for study the effect of global climate change on ecosystems.     

黑碳对气候的影响和中国黑碳减排措施

黑碳已经成为仅次于二氧化碳的气候影响因子,黑碳的排放问题越来越受到人们的关注。主要探讨了黑碳对气候的影响机理,并论述了黑碳主要是通过辐射强迫对全球气候产生影响,其中辐射强迫包括对可见光和部分红外光强吸附而造成的直接辐射强迫和通过云凝结核和冰雪反射影响等造成的间接辐射强迫。另外,还讨论了中国黑碳的排放问题,并且针对不同类别的排放源,提出了一些可行的减排建议。     

Regional differences of column-related aerosol parameters in Germany

With the development of satellite experiments supplementary and validating ground-based measurements are gaining growing importance for the inference and evaluation of radiation-related aerosol parameters. Both kinds of measurements have been conducted and interpreted mainly under globally or locally restricted aspects for a limited time period only. Results are presented from four rural regions (coastal zone, lowlands, highlands, high mountain); they are column-related aerosol parameters, deduced from monitoring programs of spectral aerosol optical depth (AOD) as well as almucantar sky irradiance measurements. After 13 years of continuous measurements of trends and variations in aerosol optical depths, these results are based on 5 years of data collection (1994–1998). There are significant differences among the parameters of the four regions when related to the inversion method of the AOD spectra. A clear interdependence was found between all column-related parameters and the real part of the refractive index, which in turn depends on the chosen retrieval method. The differences among the four regions are characterized mainly by their different altitudes, with relative humidity being responsible for their internal variation. An increase in the relative humidity from 35 to 55–60% influences the most interesting parameters such as refractive index (real part), hemispheric backscattered fraction b, and direct radiative forcing ΔF as follows: The real part of the refractive index decreases from 1.6±0.05 to 1.42±0.04, b decreases by 8–10%, and, due to the increase in AOD, ΔF increases by about 20% in the spectral region 0.4–1.0 μm. The quantities of the parameters depend on the retrieval methods too.     

华北地区沙尘气溶胶对云辐射强迫的影响

采用CERES SSF Aqua MODIS Edition 2B/2C和CALIPSO卫星探测资料结合地面台站沙尘观测资料,通过对强沙尘天气过程中纯云区与沙尘云区大气层顶处辐射强迫值的对比分析,研究了我国华北地区沙尘气溶胶对云辐射强迫的影响.研究发现, 2006年4月16日、5月16日、2007年3月30日3次过程沙尘云区大气层顶云的净辐射强迫绝对值比纯云区分别减小了7.1%,17.2%和3.1%,云的冷却效应受到不同程度抑制.纯云区与沙尘云区云的光学特性参量的对比分析结果表明,绝大部分沙尘云区的云粒径、云水路径和光学厚度值均比纯云区的要小.     

A simple Lagrangian model to simulate temporal variability of algae in the Elbe River

We present a five-year (1997–2001) numerical simulation of daily mean chlorophyll a concentrations at station Geesthacht Weir on the lower Elbe River (Germany) using an extremely simple Lagrangian model driven by (a) water discharge, global radiation, water temperature, and (b) silica observations at station Schmilka in the upper reach of the Elbe River. Notwithstanding the lack of many mechanistic details, the model is able to reproduce observed chlorophyll a variability surprisingly well, including a number of sharp valleys and ascents/descents in the observed time series. The model's success is based on the assumption of three key effects: prevailing light conditions, sporadic limitation of algal growth due to lack of silica and algae loss rates that increase above an empirically specified temperature threshold of 20 °C. Trimmed-down model versions are studied to analyse the model's success in terms of these mechanisms.In each of the five years the model consistently fails, however, to properly simulate characteristic steep increases of chlorophyll a concentrations after pronounced spring minima. Curing this model deficiency by global model re-calibration was found to be impossible. However, suspension of silica consumption by algae for up to 10 days in spring is shown to serve as a successful placeholder for processes that are disregarded in the model but apparently play an important role in the distinctly marked period of model failure. For the remainder of the year the very simple model was found to be adequate.     

自贸区效应下山东省渔业资源开发基准选择

国家间自贸区的设立,将更加有利于各签约国资源环境利用效率的提升。本文采用贸易指数测算方法,分析了中、挪、韩在海水产品生产、加工及贸易流通中的各自优势。挪威因丰富的渔业资源和先进的渔业技术,在海水产品养殖及加工领域中具有全球引领作用;韩国有相对更加严格的海水产品安全检疫检验体系,可以确保海水产品的品质安全。随着中韩自贸区的实施及中挪重启双边自贸协定谈判,三国海洋渔业彼此间将进入自贸型竞争态势。如何运用自贸区效应,积极促进渔业资源开发比较潜能的发挥,进一步融入全球化,对于我国,尤其是对山东省渔业实现跨越式发展都是一个亟待破解的课题。山东省作为中国第一渔业大省,在继"海上山东"战略实施基础上,又率先提出"海上粮仓"建设规划设想。针对目前山东省渔业发展中存在的瓶颈问题,本文结合全球贸易分析模型(GTAP)的模拟,在中挪、中韩自贸区背景下对各方海水产品贸易的影响进行了系统分析,提出:在当前海水养殖产量大于捕捞产量的格局下,山东"海上粮仓"建设应以自贸区制度所形成的倒逼机制为互动机理,切实落实海产品养殖生产的安全标准底线和生态系统水平提升的两个基准维度,全面践行可持续健康的渔业资源开发理念,在全国先行完成开放型"海上粮仓"示范体系的建设,以推动我国海水产品生产与加工从量到质的转型,实现海水资源开发与生态环境保护并举,提升我国海洋渔业的国际竞争力。