地表反射率产品支持的GF-1 PMS气溶胶光学厚度反演及大气校正

GF-1卫星PMS(GF-1 PMS)数据具有高空间分辨率、短重访周期的特点,可以在地表类型识别、参数提取中发挥重要作用。但由于缺少2.1μm附近的短波红外波段,使得气溶胶反演时地表反射率的精确确定非常困难,从而导致其高精度大气校正难以开展,限制了该数据的应用。本文提出了一种地表反射率数据支持的气溶胶反演方法,用于GF-1PMS数据的大气校正。其基本思想是:使用现有的地表反射率数据集为GF-1PMS数据提供地表反射率,用于确定GF-1PMS图像中浓密植被像元(DDV)的分布,基于确定的浓密植被像元反演气溶胶光学厚度(AOD),并用于大气校正。这里使用的地表反射率数据集为合成的无云MODIS地表反射率产品,对GF-1PMS数据做了空间尺度的转换。为降低两类数据配准误差对地表反射率确定的影响,提出了使用区域NDVI分布百分比匹配的方法,回避了像元的直接匹配,为GF-1PMS数据提供DDV的空间分布。为验证该方法的有效性,利用北京、太湖两个AERONET站点观测的气溶胶光学厚度对气溶胶反演结果进行精度验证,结果表明,气溶胶反演算法精度较高,稳定性较强。AOD反演结果应用于北京和敦煌地区的GF-1PMS数据大气校正,获得的地表反射率与地面实测的地表反射率的误差低于0.015,且大气校正后影像对比度明显提高。     

木瓜蛋白酶结合运动装置建立兔膝关节创伤性滑膜炎模型的实验研究

目的：探讨木瓜蛋白酶联合运动装置建立膝关节创伤性滑膜炎动物模型的方法。方法：将10只新西兰兔随机分为空白组和模型组,每组各5只。从造模实验开始的第1、4、7天将0.1 ml 4%的木瓜蛋白酶水溶液注射于模型组兔的右后肢关节腔内,第8天开始,将模型组麻醉后,将其四肢固定于运动装置上继续造模,共造模7 d。测量兔造模肢膝关节周径变化,并观察其跛行情况。造模结束后,取右后肢膝关节腔积液、滑膜、软骨及周围肌肉,检测白细胞介素-1（IL-1β）、肿瘤坏死因子-α（TNF-α）的水平;观察滑膜、软骨、肌肉的病理组织情况。结果：2组关节周径及膝关节积液,滑膜,肌肉中IL-1β、TNF-α比较,差异均有统计学意义（P<0.05）;滑膜、软骨、肌肉组织的病理结果显示炎性改变。结论：运动结合木瓜蛋白酶完善了单一使用木瓜蛋白酶建立膝关节创伤性滑膜炎模型的不足,造模成功且效果好。     

3S技术在石狮市“两违”执法中的应用实践

随着城市建设和发展,违法用地和违法建设现象愈演愈烈,制止“两违”是一项长期复杂的工作。一直以来,“两违”执法程序烦琐,缺乏有效的技术手段,无法及时发现和制止违法行为。利用遥感(RS)技术可以实时监测土地违法现象,结合地理信息系统(GIS)和全球定位系统(GPS)技术构建“两违”执法管理平台,能准确快速地定位“两违”图斑并指导现场执法巡查。本文以石狮市为例,研究了3S(RS、GIS、GPS,遥感(Rernote Sensing,RS)、地理信息系统(Geographic Information System,GIS)、全球定位系统(Global Positioning System,GPS))技术在“两违”执法工作中的实践应用。结果表明,“3S”技术可以全面及时地发现土地违法行为,极大地提高执法效率。     

Financing for sustainability: Empirical analysis of green bond premium and issuer heterogeneity

More recently, investors’ preference for green bonds is of particular interest for researchers. The possible non-pecuniary motive in sustainable finance can be identified by the green bond premium. But no consensus has been achieved owing to differences in samples and market settings. This paper specifically focuses on the estimation of the green bond premium in China. We introduced three issuance motivation theories to explain the drivers of green premium and convinced them through a set of empirical tests. The propensity score matching method was employed to claim that compared with matched conventional bonds, green bonds are priced at an average negative premium of 7.8bps, implying that green projects may be issued at a lower cost. Considering that a financial group has a higher negative premium than a corporate group, green financing for sustainable development is still led by indirect finance. Furthermore, empirical results convince that a negative premium is pronounced for state-owned enterprises and varies across the financial and corporate groups. Central SOEs have more advantage in raising funds than local SOEs. In addition, the effect of ownership on the green premium will significantly change if bond issues with a third-party verification. The role of verification is important in reducing information asymmetry and avoiding greenwashing behavior. We suggest that financial resources need to be properly allocated to the real enterprises through third-party verification or government supportive measures.

     

Northern poleward edge of regional Hadley cell over western Pacific during boreal winter: year-to-year variability,influence factors and associated winter climate anomalies

Compared to the zonal-mean Hadley cell (HC), our knowledge of the characteristics, influence factors and associated climate anomalies of the regional HC remains quite limited. Here, we examine interannual variability of the northern poleward HC edge over western Pacific (WPHCE) during boreal winter. Results suggest that interannual variability of the WPHCE is impacted by the El Niño-Southern Oscillation (ENSO) Modoki, North Pacific Oscillation (NPO) and North Atlantic Oscillation (NAO). The WPHCE tends to shift poleward during negative phase of the ENSO Modoki, and positive phases of the NPO and NAO, which highlights not merely the tropical forcing but also the extratropical signals that modulate the WPHCE. ENSO modoki, NPO and NAO modulate the WPHCE via inducing atmospheric anomalies over the western North Pacific. We further investigate the climatic impacts of the WPHCE on East Asia. The poleward shift of the northern descending branch of the WPHC results in anomalous upward (downward) motions and upper-level divergence (convergence) anomalies over south-central China (northern East-Asia), leading to increased (decreased) rainfall there. Moreover, pronounced cold surface air temperature anomalies appear over south-central China when the sinking branch of the WPHC moves poleward. Based on the temperature diagnostic analysis, negative surface temperature tendency anomalies over central China are mostly attributable to the cold zonal temperature advection and ascent-induced adiabatic cooling, while the negative anomalies over South China are largely due to the cold meridional temperature advection. These findings could improve our knowledge of the WPHCE variability and enrich the knowledge of forcing factors for East Asian winter climate.

     

CBERS-02星CCD波段平均太阳辐照度反演及应用

卫星图像波段平均太阳辐照度是计算表观反射率的重要参数。本文采用两种方法对CBERS-02星CCD波段平均太阳辐照度进行了计算,一种方法是利用大气辐射传输软件SBDART模拟大气顶部的太阳光谱曲线,结合CBERS-02星CCD波段响应曲线,计算1～4波段的平均太阳辐照度;另一种方法是用6S模型对波段平均太阳辐照度进行计算。为验证计算结果,用同样的方法,计算了LandsatTM5和ETM的波段平均太阳辐照度,与Landsat公布的数据进行对比,结果表明,用模拟的太阳光谱曲线的计算结果更准确。以2005年8月24日的一景图像为例,计算了图像的表观反射率,经6S模型大气校正后,反演了地表反射率,与地面实测的地表反射率进行了对比,除第四波段误差为4%外,其余1～3波段误差仅为0.01%。     

Effects of surface waves and sea spray on air–sea fluxes during the passage of Typhoon Hagupit

Air–sea exchange plays a vital role in the development and maintenance of tropical cyclones(TCs). Although studies have suggested the dependence of air–sea fluxes on surface waves and sea spray, how these processes modify those fluxes under TC conditions have not been sufficiently investigated based on in-situ observations.Using continuous meteorological and surface wave data from a moored buoy in the northern South China Sea,this study examines the effects of surface waves and sea spray on air–sea fluxes during the passage of Typhoon Hagupit. The mooring was within about 40 km of the center of Hagupit. Surface waves could increase momentum flux to the ocean by about 15%, and sea spray enhanced both sensible and latent heat fluxes to the atmosphere,causing Hagupit to absorb 500 W/m~2 more heat flux from the ocean. These results have powerful implications for understanding TC–ocean interaction and improving TC intensity forecasting.     

一种改进的UKF滤波算法在BDS/SINS组合导航系统中的应用研究

将自适应估计原理引入UKF(unscented Kalman filter)算法中,该改进算法可以自适应地调节系统模型信息在导航解中的比重,从而减少滤波器初值偏差和系统模型异常扰动对导航解的影响.将改进的UKF算法应用于BDS/SINS(北斗/捷联惯导)组合导航系统中,仿真结果验证了其有效性,且该算法可提高组合导航系统...     

管道穿越滑坡下静力学与数值模拟对比分析

以管道横穿一滑坡工程实例为背景,利用ANSYS有限元分析软件建立管道横穿滑坡的力学数值模拟模型,采用FLAC3D软件对管道受力变形进行模拟研究,并采用静力学解析计算的方法,对管道变形受力状态进行分析研究,获得了管道临界破坏时管道的应变及应力和滑坡位移等特征。两种分析方法结果基本一致,结果均表明：管道横穿滑坡时,管道两端最易发生破坏。滑坡体管道正中部位变形最大,两侧变形变小,挠度变形曲线表现为正态分布;管道两端应力最大,中部正弯两侧负弯,和两端固定简支梁承受均布荷载弯矩形态一致。在静力学分析的基础上进行数值模拟分析对管道地质灾害的预测预警更准确。