基于随机森林模型的GRACE数据3种空间降尺度对比     

褚江东  粟晓玲  张特  雷逸甦  姜田亮  吴海江  王芊予 《湖泊科学》2024,36(3):951-962

陆地水储量是赋存在陆地上各种形式水的综合体现,研究其时空变化对认识区域水循环过程和水资源调控等具有重要意义。然而现有陆地水储量变化数据实际分辨率较低,限制了其在中小流域或地区中的应用。针对这一问题,本文基于GRACE重力卫星和其后续卫星GRACE-FO反演的陆地水储量变化数据,首先采用随机森林模型,分别基于格点、区域(流域)和区域(全国)3种空间降尺度思路将GRACE数据降尺度至0.25°×0.25°,后结合GLDAS模型数据,基于水量平衡原理计算得到地下水储量变化数据,最后基于降尺度模型模拟效果和实测地下水位数据评估3种降尺度思路在全国的适用性。结果表明:随机森林模型能够较好地模拟驱动数据(降水、气温、植被条件指数和土壤水储量)与GRACE数据的统计关系,验证期格点降尺度思路的平均相关系数总体在0.6左右,区域降尺度思路的平均纳什效率系数、相关系数和均方根误差分别>0.5、>0.75和<6.6 cm,3种空间降尺度思路的模拟精度均满足基本要求;2003—2021年间,GRACE数据、格点降尺度、区域降尺度(流域)和区域降尺度(全国)得到的我国陆地水储量亏缺量分别约为119.5×10⁸、62.4×10⁸、121.1×10⁸和121.8×10⁸ m³/a,地下水储量亏缺量分别约为230.0×10⁸、171.8×10⁸、235.6×10⁸和236.4×10⁸ m³/a,受制于样本数较少等原因,格点降尺度结果精度较差;两种区域降尺度思路得到的水储量变化速率均和原始GRACE数据基本一致,模拟结果均优于格点降尺度,且细化到流域的区域降尺度对地下水储量变化验证精度有一定的改善。区域降尺度具有适用性强、模拟精度高、计算效率高的优势,研究结果可为流域水资源可持续利用以及水资源规划等提供精细化的水储量变化数据。  相似文献   

气候变暖和营养水平对洱海浮游植物的长期影响(1980-2009年)   总被引：2，自引：1，他引：1  

吴功果  倪乐意  曹特  张敏  谢平  徐军 《湖泊科学》2013,25(2):209-212

气候变暖下湖泊富营养化进程是近年研究热点之一.本文对1980-2009年期间洱海富营养化进程研究发现,水体总磷、总氮与气温均呈升高趋势.气温、水体总磷和总氮均能显著促进浮游植物增长.统计分析表明,气温对浮游植物增长的促进作用不受水体总氮、总磷的影响;水体总磷对浮游植物增长的促进作用不受气温的影响,受水体总氮的影响;水体总氮对浮游植物增长的促进作用不受气温和水体总磷的单独影响,受它们共同的影响.因此,气候变暖与营养水平的增加共同促进了洱海的富营养化进程.  相似文献   

辽东黑沟地区古元古代碱长花岗岩年代学、地球化学、Hf同位素特征及其对辽吉造山带构造演化的制约     

杨玉伟  余超  王广伟  苏特  杨新宇  张天元 《地质学报》2020,94(8):2212-2226

华北克拉通东部造山带内古元古代中期(2.1～2.2Ga)岩浆记录了造山带早期重要的地壳演化信息,对探讨辽吉造山带古元古代地质演化过程具有十分重要的意义。本文选择了辽东黑沟地区古元古代碱长花岗岩进行岩石学、地球化学、锆石U-Pb年代学和Hf同位素研究。黑沟碱长花岗岩LA-ICP-MS锆石U-Pb测年结果为2186.5±6.5Ma,形成时代为古元古代。岩石为碱性、弱过铝质A型花岗岩,岩石富硅、碱,贫钙、镁、铝,极度富钠贫钾,富集Hf、Zr、Nb、Y等高场强元素,亏损Rb、K、Ba等大离子亲石元素,具有较高的(K_2O+Na_2O)/Al_2O_3、FeO~T/MgO、Ga/Al比值,负的Eu异常,稀土元素配分曲线呈右倾海鸥型配分模式。锆石饱和温度介于857～884℃之间,同时具有非常低Sr高Yb特征,指示岩石形成于低压高温的伸展构造背景。锆石ε_(Hf)(t)值为-0.96～+4.58,二阶段模式年龄t_(DM2)=2476～2821Ma,明显大于花岗岩的成岩时代,结合岩石地球化学特征指示黑沟碱长花岗岩岩浆源于太古宙TTG片麻岩在地壳浅部伸展条件下的部分熔融。综合区域已有的岩石学、地球化学和同位素特征等资料,辽吉地区在古元古代早期可能处于大陆弧后盆地构造环境,黑沟碱长花岗岩是弧后盆地伸展环境下的产物。  相似文献   

Bringing stakeholders,scientists, and managers together through an integrated ecosystem assessment process     

Yvonne L. deReynier  Phillip S. Levin  Noriko L. Shoji 《Marine Policy》2010

For decades, the scientific community has conducted essential background research and developed appropriate modeling tools in support of an ecosystem-based approach to natural resource management. Resource managers and the public, however, lack a clear roadmap for working with scientists to move beyond the traditional single-species approach. With current management processes so strongly focused on working in a species-by-species framework, there are entrenched cultural and institutional challenges to shifting those processes toward ecosystem-based management. We propose using the integrated ecosystem assessment process to both develop new management ideas for a particular ecosystem, and to help shift public policy processes and perceptions to embrace ecosystem approaches to management.  相似文献   

An investigation into intersex amphipods and a possible association with aquaculture     

Ford AT  Read PA  Jones TL  Michino F  Pang Y  Fernandes TF 《Marine environmental research》2007,64(4):443-455

The amphipod, Echinogammarus marinus, is common in sheltered coastal inlets, such as estuaries and sea lochs, in Scotland and exhibits increased levels of intersex in some contaminated areas. Sea lochs are commonly the location for coastal aquaculture development, and some chemicals used in fish-farming are specifically designed to target the crustacean nervous system. Therefore it was hypothesised that these chemicals may also affect neuro-endocrine pathways, causing morphological and reproductive abnormalities in non-target Crustacea. Based upon this hypothesis, Echinogammarus marinus amphipods from two different Scottish sea lochs containing salmon farms were investigated. Morphology, intersexuality, and the incidence of microsporidian parasites were recorded at sites close and at distance from fish-farms. Results suggest a higher incidence of intersexuality at sites within sea lochs, comparable to that observed in industrially contaminated sites elsewhere in Scotland. The data suggest that fish farming activity may influence the observed distributions of intersexuality within lochs. Intersex specimens were more likely to be infected by microsporidian parasites than non-intersex specimens. Normal females were found more likely to be infected by microsporidian parasites at sites associated with high intersexuality, suggesting the parasite as the probable feminiser. The cause(s) for the observed patterns of intersexuality are unclear, although suggestions relating to discharges from fish farms are discussed.  相似文献   

Modelling overland flow based on Saint‐Venant equations for a discretized hillslope system     

Guang‐Te Wang  Shulin Chen  Jan Boll  C. O. Stockle  D. K. McCooL 《水文研究》2002,16(12):2409-2421

Mathematical modelling of overland flow is a critical task in simulating transport of water, sediment and other pollutants from land surfaces to receiving waters. In this paper, an overland flow routing method is developed based on the Saint‐Venant equations using a discretized hillslope system for areas with high roughness and steep slope. Under these conditions, the momentum equation reduces to a unique relationship between the flow depth and discharge. A hillslope is treated as a system divided into several subplanes. A set of first‐order non‐linear differential equations for subsequent subplanes are solved analytically using Chezy's formula in lieu of the momentum equation. Comparison of the analytical solution of the first‐order non‐linear ordinary differential equations and a numerical solution using the Runge‐Kutta method shows a relative error of 0·3%. Using runoff data reported in the literature, comparison between the new approach and a numerical solution of the full Saint‐Venant equations showed a close agreement. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

The audacity of the ocean: Gendered politics of positionality in the Pacific     

Yvonne Te Ruki-Rangi-o-Tangaroa Underhill-Sem 《Singapore journal of tropical geography》2020,41(3):314-328

Throughout the contemporary Pacific, relationships that indigeneity makes possible are emerging as celebrated resistance to post-colonial development anxieties. In the process, lived experience heightens the commitment to decolonize thinking, language and practice in teaching and research. Not only because these imperatives are highly personalized but also because they are gendered and heavy with generational trauma. These gendered dynamics circulate around popular culture and imaginaries of Pacific paradise but also problematically around the challenges of long-standing intolerances especially around gender and race. The paper asks how a gendered politics of positionality engages with emerging positionalities that uncritically allow for such intolerances. I touch on two ways in which colonial continuities of belittlement are often reinforced, but are also offering hopeful and careful decolonial scholarly futures. The first is the naming of the Pacific and the second is supervising women doctoral candidates from the Pacific. In this paper, the audacity of the ocean offers a metaphorical opportunity to carefully reconcile these tensions and provide trajectories for decolonial knowledge-making. However, it also offers a material way of understanding the on-going work with ‘tensions’ and disruptions in their ever present but changeable forms. Oceanic tropes and a feminist Oceanic audacity of embodied engagement in the Pacific offer dynamic and gendered intellectual agility which runs counter to the tropical imageries of languid indifference.

black/is a state of mind like the colour of an island Teaiwa (2017) we sweat and cry salt water, so we know that the ocean is really in our blood Teaiwa (2008)

  相似文献   

侧扫声纳系统姿态参数平滑方法研究   总被引：1，自引：0，他引：1  

熊传梁  王特  高君  肖付民  刘雁春 《海洋测绘》2012,(3):5-7

针对侧扫声纳系统姿态参数采样率低于声纳Ping值采样率的问题,采用窗口移动多项式最小二乘平滑方法（Savitzky—Golay平滑法）,对阶梯状姿态数据进行平滑。结果证明了该法的可行性。在选取窗口宽度和多项式阶数时,通过实测数据比较表明,采用窗口为11的二阶多项式平滑后结果与原数据符合程度高。  相似文献   

A conceptual framework for multi-regional climate change assessments for international market systems with long-term investments     

Julie A. Winkler  Suzanne Thornsbury  Marco Artavia  Frank-M. Chmielewski  Dieter Kirschke  Sangjun Lee  Malgorzata Liszewska  Scott Loveridge  Pang-Ning Tan  Sharon Zhong  Jeffrey A. Andresen  J. Roy Black  Robert Kurlus  Denys Nizalov  Nicole Olynk  Zbigniew Ustrnul  Costanza Zavalloni  Jeanne M. Bisanz  Géza Bujdosó  Lesley Fusina  Yvonne Henniges  Peter Hilsendegen  Katarzyna Lar  Lukasz Malarzewski  Thordis Moeller  Roman Murmylo  Tadeusz Niedzwiedz  Olena Nizalova  Haryono Prawiranata  Nikki Rothwell  Jenni van Ravensway  Harald von Witzke  Mollie Woods 《Climatic change》2010,103(3-4):445-470

A conceptual framework for climate change assessments of international market systems that involve long-term investments is proposed. The framework is a hybrid of dynamic and static modeling. Dynamic modeling is used for those system components for which temporally continuous modeling is possible, while fixed time slices are used for other system components where it can be assumed that underlying assumptions are held constant within the time slices but allowed to vary between slices. An important component of the framework is the assessment of the “metauncertainty” arising from the structural uncertainties of a linked sequence of climate, production, trade and decision-making models. The impetus for proposing the framework is the paucity of industry-wide assessments for market systems with multiple production regions and long-term capital investments that are vulnerable to climate variations and change, especially climate extremes. The proposed framework is pragmatic, eschewing the ideal for the tractable. Even so, numerous implementation challenges are expected, which are illustrated using an example industry. The conceptual framework is offered as a starting point for further discussions of strategies and approaches for climate change impact, vulnerability and adaptation assessments for international market systems.  相似文献   

Determining stellar radii using large separations: an error analysis     

Sarbani Basu  William J. Chaplin  Yvonne Elsworth 《Astrophysics and Space Science》2010,328(1-2):79-82

The Kepler mission will provide large separations for many stars. One of the tasks of Kepler Asteroseismic Consortium is to determine radii of the observed stars from the large separations and other catalogued “classical” data such as effective temperature, metallicities, brightness, distance etc. We present the results of a detailed analysis of errors in the radius estimates caused by errors in the input parameters. This exercise enables us to determine which parameters will benefit from follow-up observations of the interesting cases.  相似文献