COVID-19疫情前后长三角城市群人口流动结构变化研究

基于互联网平台提供的2019年、2020年、2021年3月份的人口流动数据,依次代表疫情前、疫情中和疫情稳定后3个节点,运用空间分析和社会网络分析,测度长三角城市群26个城市间的人口流动网络结构时空演化特征,讨论疫情对城市群人口流动的影响.结果发现:长三角城市群整体人口流动强度正逐步向更高一级上升,但疫情的出现暂缓了这...     

基于PCA算法的星载GNSS-R海面目标反演

提出使用主成分分析(principal components analysis,PCA)抑制时延多普勒图(delay Doppler map, DDM)中的海杂波,提高海面目标反演精度。以挪威Snøhvit采气平台作为海面目标,采用2016-11-13的DDM数据进行目标反演。结果显示,未使用PCA抑制海杂波前,反演位置平均误差为17.65 km;抑制海杂波后,反演位置平均误差为11.42 km,位置精度提升35.30%。     

科学合作地域倾向性研究——以中国雾霾研究为例

科学合作是促进知识传播和共享的重要途径,已有研究表明,地理因素是影响科学合作的主要因素之一。然而,目前针对该问题的研究大多只是从科学计量学的角度,对科学合作强度与地理距离的函数关系进行描述,无法揭示科学合作在空间上的分布特征和内部差异性。因此,本文从地理学的角度,以中国雾霾研究的合作网络为例,通过对文献题录中的位置信息进行解析,将虚拟的科学合作网络映射到地理合作网络。在此基础上,提出了一种考虑地理距离的科学合作网络社区发现方法,挖掘科学合作网络中蕴含的空间聚类特征,从而对科学合作的地域倾向性进行反映。通过比较发现,基于合作频次与地理距离的社区发现算法,能够使社区内部的平均地理距离最小而合作强度最大,既反映了科学合作在地理上的近似性,又体现了科学合作强度特征。该方法能够直观地揭示科学合作中隐含的空间分布模式和联系,对其他复杂网络的地理社区划分也有一定的借鉴意义。     

GPS天线相位中心校正对GRACE卫星精密定轨的影响

使用GRACE卫星星载GPS观测数据,研究地面获取的先验PCV模型和利用残差法估计的在轨PCV模型对低轨卫星精密定轨的影响,并采用GFZ精密轨道对比和SLR检核手段对其进行评估。结果表明,使用先验PCV模型会降低GRACE卫星定轨精度,相反利用在轨PCV模型可以提高定轨精度,提升数量级可达mm级。     

Simulation Study of Potential Impacts of Tidal Farm in the Eastern Waters of Chengshan Cape,China

The sea area east of Chenshan Cape has peak tidal current flows that exceed 2.3 m s-1, which make it a promising site for the development of tidal current energy. Before these resources can be exploited, a comprehensive assessment is needed of the potential environmental impacts of the extraction of this energy. In this paper, we describe our construction of a three-dimensional hydrodynamic model of the waters near Chengshan Cape, and verify the performance of the model using continuous data measured in situ. We modeled the potential impacts of the exploitation of these resources on the flow field by adding a momentum loss term in the governing equation of the model. Simulation results show that an assumed tidal farm with an estimated power output of 20.34 MW would have a significant impact on the surrounding water level, especially next to the farm, where fluctuation could reach 6 cm. The maximum drop in the flow velocity in the wake of the farm was predicted to be more than 0.8 m s-1, and this influence would extend 10 km downstream.     

Evaluation of the integrated multi-satellite retrievals for global precipitation measurement over the Tibetan Plateau

The availability of high-resolution satellite precipitation measurement products provides an opportunity to monitor precipitation over large and complex terrain and thus accurately evaluate the climatic, hydrological and ecological conditions in those regions. The Global Precipitation Measurement(GPM) mission is an important new program designed for global satellite precipitation estimation, but little information has been reported on the applicability of the GPM’s products for the Tibetan Plateau(TP). The object of this study is to evaluate the accuracy of the Integrated Multi-Satellite Retrievals for GPM(IMERG) Final Run product under different terrain and climate conditions over the TP by using 78 ground gauges from April 2014 to December 2017. The results showed the following:(1) the 3-year average daily precipitation estimation in the IMERG agrees well with the rain gauge observations(R~2=0.58, P0.01), and IMERG also has a considerable ability to detect precipitation, as indicated by a high probability of detection(78%-98%) and critical success index(65%-85%);(2) IMERG performed better at altitudes from 3000 m to 4000 m with a small relative bias(RB) of 6.4%. Precipitation change was not significantly affected by local relief;(3) the climate system of the TP was divided into four climate groups with a total of 12 climate types based on the K?ppen climate classification system, and IMERG performed well in all climate types with the exception of the arid-desert-cold climate(Bwk) type. Furthermore, although IMERG showed the potential to detect snowfall, it still exhibits deficiencies in identifying light and moderate snow. These results indicate that IMERG could provide more accurate precipitation data if its retrieval algorithm was improved for complex terrain and arid regions.     

不规则网土壤测量在水系沉积物异常查证中的应用

在大兴安岭森林沼泽景观区,植被茂盛、土壤表层腐殖质发育,且通视条件差,运用传统的规则网土壤测量方法进行1/5万水系沉积物异常查证,工作周期长、劳动强度大;采用不规则网土壤测量方法进行异常查证,取得了快速评价异常、追踪异常源,缩短找矿周期的效果。     

自贡市近50年来气候变化特征分析

本文利用自贡市1955~2006年的气温、降水资料,采用线性倾向估计、累计距平、Mann-Kendall等方法,研究了自贡市近52年来气温、降水的年、季变化特征。结果表明:在全球气候变化背景下,近52年来,自贡年平均气温略上升,年降水量略减少。秋季气候表现为明显的暖干趋势,春季气候则具有明显的变湿趋势。近10年来自贡气候变暖趋势明显。     

浅析律师角色的社会定位——兼谈律师法对律师权利义务的设计

运用法制给律师一个准确定位是法治社会发展的需要，也是发挥律师作用的重要前提。我国现行律师法将律师定位于为社会提供法律服务的执业人员，对律师职业定位不准确，造成律师社会地位低下，缺乏社会责任感，容易造成律师角色失败。社会需求和价值取向决定着律师角色的社会定位，我国的律师法对律师权利义务的制度设计应成为律师定位和发挥其作用的法律保障。     

Estimating the Budgets of Nutrients for Phytoplankton Bloom in the Central Yellow Sea Using a Modified Lower Tropic Ecosystem ModelDOI 10.1007/s11802-014-1900-6

A modified lower trophic ecosystem model(NEMURO) is coupled with a three-dimensional hydrodynamic model for an application in the central Yellow Sea. The model is used to simulate the horizontal distributions and annual cycles of chlorophyll-a and nutrients with results consistent with historical observations. Generally, during the winter background and spring bloom periods, the exchange with neighboring waters constitutes the primary sources of nutrients. Howerver, during the winter background period, the input of silicate from the layer deeper than 50 m is the most important source that contributes up to 60% to the total sources. During the spring bloom period, the transport across the thermocline makes significant contribution to the input of phosphate and silicate. During the post spring bloom period, the relative contribution of relevant processes varies for different nutrients. For ammonium, atmospheric deposition, excretion of zooplankton and decomposition of particulate and dissolved nitrogen make similar contributions. For phosphate and silicate, the dominant input is the transport across the thermocline, accounting for 62% and 68% of the total sources, respectively. The N/P ratio averaged annually and over the whole southern Yellow Sea is up to 51.8, indicating the potential of P limitation in this region. The important influence of large scale sea water circulation is revealed by both the estimated fluxes and the corresponding N/P ratio of nutrients across a section linking the northeastern bank of the Changjiang River and Cheju Island. During the winter background period, the input of nitrate, ammonium, phosphate and silicate by the Yellow Sea Warm Current is estimated to be 4.6×1010, 2.3×1010, 2.0×109 and 1.2×1010 mol, respectively.