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基于0903,0906和0908号台风期间的FY-3A极轨卫星微波湿度计(FY-3A/MWHS)数据,借助于多元线性逐步回归方法,探讨了利用FY-3A极轨卫星定量估计降水的方法,同时结合自动气象站实测资料、TRMM和FY-2C卫星降水估计结果对FY-3A/MWHS降水估计精度进行了验证。结果表明,FY-3A/MWHS估计降水与地面实测降水具有较好的相关性,对不同等级雨量均有一定的估测能力,尤其对中等量级的降水无论是在降水落区还是在降水量级上均具有较高的准确率。与FY-2C静止卫星相比,无论是在对不同量级降水估计的"击中率",还是在估计精度方面,FY-3A/MWHS数据更具优势。利用FY-3A/MWHS对不同高度、不同角度的湿度响应特性开展定量降水估计,是降水估计方法的一种新的探索和必要的补充。 相似文献
995.
Giulio Alessandro De Leo Marco Bartoli Mariachiara Naldi Pierluigi Viaroli 《Marine Ecology》2002,23(S1):92-100
Abstract. In this work we have developed a very simple stochastic mathematical model of Ulva spp. growth to quantitatively evaluate the economic costs of algal harvesting and the related benefits in terms of avoided'economic loss'of clam production due to an effective prevention of algal blooms and the consequent anoxic crises. Algal growth was simulated by means of a discrete time difference equation of Ulva biomass where the finite growth rate depends only upon water temperature. In order to explicitly include environmental variability, a seasonal autoregressive model calibrated on available data was used to simulate water temperature. Different harvesting scenarios were analysed in terms of the number of harvesting vessels employed and the threshold biomass of Ulva at which vessels start to operate. Costs of algal harvesting and disposal, as well as monetary damages resulting from the collapse of clam production as a consequence of algal blooms, were assessed by interviewing the managers of the Clam Fishermen's Union of Goro. A Monte Carlo approach was used to estimate the mean and total statistical distribution of costs and benefits of different harvesting strategies. Our analysis shows that the most cost-effective management policy is attained with 4–6 vessels operating at low algal density able to harvest as much Ulva as possible with intensive and short interventions at the beginning of the seasonal growth. 相似文献
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大幅度、快速光变是BL Lac天体的重要特征之一,光变研究对探索BL Lac天体内部的物理过程和机理具有特殊的意义.从大量文献中收集了BL Lac天体S5 0716+714光学V,R,I 3个波段从1994年到2008年的有效观测数据,并将这些数据30天平均后进行自回归模型(AR)的双谱估计. 双谱的等高线图和对角切片图表明,双谱估计能消除噪声的干扰来提取有用信息,抑制了噪声、提高了信噪比,有很高的分辨率,避免了伪峰的出现,能准确地认证BL Lac天体的光变周期值.由V,R,I 3个波段的双谱等高线图和对 相似文献
998.
The design of fixed or floating offshore structures requires accurate information of the met-ocean data at the intended offshore site. In the design process it is recognized that this environmental data is modified in the near-field by the interaction with the particular geometrical configuration of the offshore structure. This transformation of the incident wave field around and beneath an offshore structure presents a challenge for ocean engineers when specifying the wave gap elevation to avoid impact loads on the underside of the deck and inundation of the topsides. Thus, the accurate estimation of the wave crest distributions from measurements at various locations near and under the offshore structure during model test studies is essential. A semi-empirical approach is presented herein that builds upon the findings of previous studies and introduces the Method of L-moments. A three parameter model for a wave crest probability distribution function is presented and explicit relationships between the parameters of the distribution and its’ first three L-Moments are established. Furthermore, three narrow-band models from earlier research studies are reviewed and compared with the new model. Wave measurements from a mini-TLP model test program are used as the basis for comparison of the four distributions. The root-mean-square error is used as a metric to quantify the overall fit of the data and its accuracy in the high end tail of the data. The L-Moment model is shown to be more robust in representing the data in both the far-field and beneath the deck of the mini-TLP where the wave field demonstrates increased non-linear behavior. 相似文献
999.
广东阳西近岸海域海浪谱分析 总被引:1,自引:0,他引:1
根据广东阳西近岸海域测站1a实测共4 949组的原始随机波面观测记录,用自相关函数法和快速傅里叶变换法进行谱估计,得到波谱各特征参数,并与实测波面统计的特征值进行比较,经分析,选用快速傅里叶变换法估计研究海域的实测谱,对粗谱进行平滑和分析,筛选出研究海域海浪的样本谱498个,将平滑后的谱形无维量化,得到广东阳西海域海浪无维量平均谱曲线并求出对应谱参数,计算得到谱峰频率f0为0.121,特征频率μ10、μ20分别为1.929、2.733,谱宽度ε、ν为0.83、1.39.采用5种理论频谱模式对实测无维量谱进行拟合,根据拟合结果推荐γ=1.920 5的JONSWAP谱或者b=5.7、δ=6.0、k=0.5的莆田谱作为广东阳西近岸海域的海浪谱型,对该海区的工程建设、海浪预报警报和海浪理论研究具有较好的参考作用,对我国其他类似海域也有一定的参考价值. 相似文献
1000.
R. W. Hickman 《新西兰海洋与淡水研究杂志》2013,47(4):641-644
Captive rock lobsters (Jasus edwardsii) were able to open and eat live dredge oysters (Ostrea lutaria) by progressively breaking away the shell edges with the mandibles and walking legs. Oysters are probably of only slight significance in the natural diet of rock lobsters. 相似文献