利用短期静态PPP结果反演海潮负荷位移     

魏国光  王琪洁  彭葳  郭良琦 《大地测量与地球动力学》2019,39(6):607-612

采用香港11个GPS测站的观测资料进行1 h、2 h、3 h和4h静态PPP解算，获得4组PPP坐标序列，利用调和分析求取11个测站处8个主要分潮的负荷位移参数（振幅和相位），将其与海潮模型计算的负荷位移参数进行对比，并比较分析PPP反演值与海潮模型值改正海潮负荷信号的效果。结果表明，垂直和水平方向上，不同PPP结果反演8个分潮的负荷位移分别具有约5 mm和7 mm的差异；PPP反演8个分潮垂向负荷位移优于全球海潮模型，但水平方向上的反演效果稍弱。  相似文献   

Cover crops and precipitation influence soluble reactive phosphorus losses via tile drain discharge in an agricultural watershed     

Matt T. Trentman  Jennifer L. Tank  Todd V. Royer  Shannon L. Speir  Ursula H. Mahl  Lienne R. Sethna 《水文研究》2020,34(23):4446-4458

Subsurface tile drainage speeds water removal from agricultural fields that are historically prone to flooding. While managed drainage systems improve crop yields, they can also contribute tothe eutrophication of downstream ecosystems, as tile-drained systems are conduits for nutrients to adjacent waterways. The changing climate of the Midwestern US has already altered precipitation regimes which will likely continue into the future, with unknown effects on tile drain water and nutrient loss to waterways. Adding vegetative cover (i.e., as winter cover crops) is one approach that can retain water and nutrients on fields to minimize export via tile drains. In the current study, we evaluate the effect of cover crops on tile drain discharge and soluble reactive phosphorus (SRP) loads using bi-monthly measurements from 43 unique tile outlets draining fields with or without cover crops in two watersheds in northern Indiana. Using four water years of data (n = 844 measurements), we examined the role of short-term antecedent precipitation conditions and variation in soil biogeochemistry in mediating the effect of cover crops on tile drain flow and SRP loads. We observed significant effects of cover crops on both tile drain discharge and SRP loads, but these results were season and watershed specific. Cover crop effects were identified only in spring, where their presence reduced tile drain discharge in both watersheds and SRP loads in one watershed. Varying effects on SRP loads between watersheds were attributed to different soil biogeochemical characteristics, where soils with lower bioavailable P and higher P sorption capacity were less likely to have a cover crop effect. Antecedent precipitation was important in spring, and cover crop differences were still evident during periods of wet and dry antecedent precipitation conditions. Overall, we show that cover crops have the potential to significantly decrease spring tile drain P export, and these effects are resilient to a wide range of precipitation conditions.  相似文献   

Modelling the effect of changing precipitation inputs on deep soil water utilization          下载免费PDF全文

Ji Qi  Daniel Markewitz  David Radcliffe 《水文研究》2018,32(5):672-686

Forests in the Southeastern United States are predicted to experience future changes in seasonal patterns of precipitation inputs as well as more variable precipitation events. These climate change‐induced alterations could increase drought and lower soil water availability. Drought could alter rooting patterns and increase the importance of deep roots that access subsurface water resources. To address plant response to drought in both deep rooting and soil water utilization as well as soil drainage, we utilize a throughfall reduction experiment in a loblolly pine plantation of the Southeastern United States to calibrate and validate a hydrological model. The model was accurately calibrated against field measured soil moisture data under ambient rainfall and validated using 30% throughfall reduction data. Using this model, we then tested these scenarios: (a) evenly reduced precipitation; (b) less precipitation in summer, more in winter; (c) same total amount of precipitation with less frequent but heavier storms; and (d) shallower rooting depth under the above 3 scenarios. When less precipitation was received, drainage decreased proportionally much faster than evapotranspiration implying plants will acquire water first to the detriment of drainage. When precipitation was reduced by more than 30%, plants relied on stored soil water to satisfy evapotranspiration suggesting 30% may be a threshold that if sustained over the long term would deplete plant available soil water. Under the third scenario, evapotranspiration and drainage decreased, whereas surface run‐off increased. Changes in root biomass measured before and 4 years after the throughfall reduction experiment were not detected among treatments. Model simulations, however, indicated gains in evapotranspiration with deeper roots under evenly reduced precipitation and seasonal precipitation redistribution scenarios but not when precipitation frequency was adjusted. Deep soil and deep rooting can provide an important buffer capacity when precipitation alone cannot satisfy the evapotranspirational demand of forests. How this buffering capacity will persist in the face of changing precipitation inputs, however, will depend less on seasonal redistribution than on the magnitude of reductions and changes in rainfall frequency.  相似文献   

基于EEMD-SARIMA的对流层延迟预测模型研究     

任超  刘中流  梁月吉  甘祥前 《大地测量与地球动力学》2018,38(9):953-957

在无气象数据的条件下，提出一种基于集合经验模态分解（EEMD）和季节性自回归移动平均模型（SARIMA）的对流层延迟（ZTD）预报新方法，并分别选取长春、上海、乌鲁木齐3个地区4个季节的ZTD数据进行预测分析。结果表明，基于EEMD-SARIMA的ZTD改正预报模型能够满足不同地区、不同季节下的ZTD估计需求，是一种高精度的ZTD预报方法。  相似文献   

全球海潮模型最新进展及在中国沿海精度评估     

范长新 《大地测量与地球动力学》2019,39(5):476-481

介绍TPXO、FES、Chinatide、MIKE Global Tide、Utide等典型海潮模型，总结归纳其同化潮汐数据来源和最新的海洋地形数据，利用我国沿岸长期验潮站以外的26个中短期潮位观测站评估TPXO等海潮模型预报精度。结果表明，全球海潮模型对我国沿海M2分潮的预报精度普遍较低，且主导了几种海潮模型在中国海域的整体预报精度；相比MIKE Global Tide和TPXO7.2,TPXO8、TPXO_Yellow Sea 2010和TPXO_China&Ind模型在我国沿海的预报精度更高。  相似文献   

基于全球分布的地震观测数据估计0S0模态的特征频率及品质因子     

周丰森  王迪晋  旦增 《大地测量与地球动力学》2019,39(10):1013-1016

选取2011-03-11日本MW9.3地震后全球地震台站记录的约220 h波形数据，基于一定的判断准则，筛选出质量较高的448个垂向观测数据，采用频域AR方法对0S0模态的特征频率和品质因子进行估值，并以信噪比为权重进行加权平均，得到特征频率f=0.814 658 4±5.3×10-7，品质因子Q=5 586±12。该结果与已有研究成果相比精度更高，有助于约束现有地球介质密度和衰减模型，使其更接近真实地球。  相似文献   

云南武定县朱家坝尾矿库渗漏原因浅析     

周南  李卿  喻涌麒 《云南地质》2020,(1):118-124

位于云南省楚雄州武定县朱家坝新建尾矿库,在使用过程中,该尾矿库下游一泉水点出现尾矿粉渗漏污染,通过地质勘查,发现该尾矿库下伏昆阳群绿汁江组(Pt2lz)的白云岩基底,存在一隐伏断层,渗漏污染原因与该断层及其形成的岩溶裂隙有直接的关系。  相似文献   

基于时间序列遥感数据的嵯岗国家沙化土地封禁保护成效评估     

田海静  孙涛  刘旭升  孔祥吉 《中国沙漠》2019,39(3):155-162

2013年中国启动实施了内蒙古自治区新巴尔虎左旗嵯岗国家沙化土地封禁保护区试点。本研究利用2001—2017年生长季NDVI数据分析了嵯岗封禁保护区及周边区域植被长势时空演变特征，分析了多年的生长季降水量和历年旱情，之后利用植被降水利用效率和NDVI残差趋势分析对保护成效进行了评估。结果表明：（1）封禁项目实施之前，封禁区内外植被长势变化趋势基本一致，而在项目实施后的2016、2017年，封禁区内NDVI距平明显高于封禁区外；（2）降水为影响该区域植被长势的主导气候因素，在封禁实施后的2015—2017年该区域连续3 a干旱，极大地限制了区域植被生长；（3）封禁区内植被降水利用效率和NDVI残差均呈现明显的增加趋势，而封禁区外变化不明显，说明封禁提升了植被的自我修复能力；（4）嵯岗封禁保护区由3个地块组成，其中嵯岗林场封禁效果比牧场八队和牧场十一队明显。国家沙化土地封禁保护措施有效促进了植被自我修复，提高了沙漠生态系统应对气候变化的能力。  相似文献   

An extreme wave event in eastern Yucatán,Mexico: Evidence of a palaeotsunami event during the Mayan times     

Javier Lario  Chris Spencer  Teresa Bardají  Ángel Marchante  Victor H. Garduño-monroy  Jorge Macias  Sergio Ortega 《Sedimentology》2020,67(3):1481-1504

The Yucatán Peninsula, Mexico, has typically been considered a tectonically stable region with little significant seismic activity. The region though, is one that is regularly affected by hurricanes. A detailed survey of ca 100 km of the eastern Yucatán and Cozumel coast identified the presence of ridges containing individual boulders measuring >1 m in length. The boulder ridges reach 5 m in height and their origin is associated with extreme wave event activity. Previously modelled tsunami waves from known seismically active zones in the region (Muertos Thrust Belt and South Caribbean Deformed Belt) are not of sufficient scale in the area of the Yucatán Peninsula to have produced the boulder ridges recorded in this study. The occurrence of hurricanes in this region is more common, but two of the most destructive (Hurricane Gilbert 1988 and Hurricane Wilma 2005) produced coastal waves too small to have created the ridges recorded here. In this paper, a new tsunami model with a source area located on the Motagua/Swan Island Fault System has been generated that indicates a tsunami event may have caused the extreme wave events that resulted in the deposition of the boulder ridges.  相似文献   

河北省怀安县朱家洼矿区地球化学特征与找矿方向     

王占彬 《地质与勘探》2020,56(1):102-112

河北怀安朱家洼矿区位于华北板块北缘中段太古宙、元古宙、中生代金银铅锌铁硫铁矿成矿带,为火山热液型金多金属矿。为查明该区成矿规律,明确找矿方向,在区内开展了水系沉积物测量、土壤地球化学测量等工作。通过对元素分布、元素相关性、元素异常等特征研究表明,Au、Mo为本区主成矿元素;各元素异常平面分布具有分带性,高温元素W、Sn、Bi异常位于骆驼山火山机构中心,中低温元素Pb、Zn、As、Ag等异常分布于火山机构边部及周边围岩中,成矿元素Au、Mo异常主要位于火山机构西侧围岩中。异常查证发现金钼矿化体2条,金钼矿化受火山机构和北西向构造带控制。依据成矿地质条件、地球化学异常及查证成果认为,朱家洼矿区Au、Mo成矿潜力大,火山机构西侧围岩区是该区重点找矿地段。  相似文献