FY-3A/MERSI, ocean color algorithm, products and demonstrative applications

A medium resolution spectral imager (MERSI) on-board the first spacecraft of the second generation of China’s polar-orbit meteorological satellites FY-3A, is a MODIS-like sensor with 20 bands covering visible to thermal infrared spectral region. FY-3A/MERSI is capable of making continuous global observations, and ocean color application is one of its main targets. The objective is to provide information about the ocean color products of FY-3A/MERSI, including sensor calibration, ocean color algorithms, ocean color products validation and applications. Although there is a visible on-board calibration device, it cannot realize the on-board absolute radiometric calibration in the reflective solar bands. A multisite vicarious calibration method is developed, and used for monitoring the in-flight response change and providing post-launch calibration coefficients updating. FY-3A/MERSI ocean color products consist of the water-leaving reflectance retrieved from an atmospheric correction algorithm, a chlorophyll a concentration (CHL1) and a pigment concentration (PIG1) from global empirical models, the chlorophyll a concentration (CHL2), a total suspended mater concentration (TSM) and the absorption coefficient of CDOM and NAP (YS443) from China’s regional empirical models. The atmospheric correction algorithm based on lookup tables and ocean color components concentration estimation models are described. By comparison with in situ data, the FY-3A/MERSI ocean color products have been validated and preliminary results are presented. Some successful ocean color applications such as algae bloom monitoring and coastal suspended sediment variation have demonstrated the usefulness of FY-3A/MERSI ocean color products.     

HJ-1A/B在2012年黄河上中游洪水监测中的应用

以黄河内蒙古河段为例,介绍HJ-1A/B星CCD数据在2012年黄河上游洪水遥感监测中的应用,并利用水文、河势变化等实测数据对监测结果进行应用评价。结果表明,HJ-1A/B星CCD数据具有高时间、空间分辨率的特点,是进行大区域、高频次洪水监测的理想数据源,能有效跟踪监测洪水演进过程,并能精确提取河势变化、主河槽展宽、堤防偎水、洪水漫滩等汛情信息,为防洪决策提供及时可靠的汛情数据。     

FY-3A MWHS资料的质量控制——以四川“8.19”暴雨为例

FY-3A MWHS微波湿度计辐射率资料空间分辨率高,同化后能有效地提高中尺度系统的数值预报的准确率。但如果不进行质量控制,任由误差大的离群微波资料进入同化系统,将会降低分析场精度,影响预报准确率。本文选取2010年8月17~19日的暴雨个例,应用主成分分析(PCA)方法,找出FY-3A微波湿度计数据中的离群值。结果表明:采用PCA方法,3天的资料总共识别出148个离群值样本,占总数的19.3%,其中通道三离群值占5.5%,通道四离群值占8.2%,通道五占5.4%。去除这些离群值后的MWHS数据总体分布,更靠近数据中心,各EOF方差贡献更加平滑。这说明PCA方法是一种可以抵抗少数离群值对总平均值影响的有效质量控制方法。      

Estimations of net primary productivity and evapotranspiration based on HJ-1A/B data in Jinggangshan city, China

Net primary productivity(NPP) and evapotranspiration(ET) are two key variables in the carbon and water cycles of terrestrial ecosystems.In this study,to test a newly developed NPP algorithm designed for HJ-1 A/B data and to evaluate the usage of HJ-1 A/B data in the quantitative assessment of environments,NPP and ET in Jinggangshan city,Jiangxi province,are calculated using HJ-1 A/B data.The results illustrate the following:(1) The NPP and ET in Jinggangshan city in 2010 both show obvious seasonal variation,with the highest values in summer and the lowest values in winter,and relatively higher values were observed in autumn than in spring.(2) The spatial pattern indicates that the annual NPP is high in the southern area in Jinggangshan city and low in the northern area.Additionally,high NPP is distributed in forests located in areas with high elevation,and low NPP is found in croplands at low elevations.ET has no significant north-south difference,with high values in the southeast and northwest and low values in the southwest,and high ET is distributed in forests at low elevations in contrast to low ET in forests in high-elevation areas and in cropland and shrub grassland in low-elevation areas.(3) Compared to the MODIS product,the range of HJ-1 NPP is larger,and the spatial pattern is more coincident with the topography.The range of HJ-1 ET is smaller than that of the MODIS product,and ET is underestimated to some extent but can reflect the effect of topography.This study suggests that the algorithm can be used to estimate NPP and ET in a subtropical monsoon climate if remotely sensed images with high spatial resolution are available.     

柴达木盆地西部地区古近系下干柴沟组咸化湖相泥页岩储集层特征

中国已获得湖相页岩气勘探开发的重要突破,但对于咸化湖盆环境泥页岩储集层特征的研究较少。作者对柴达木盆地西部地区古近系下干柴沟组湖相泥页岩储集层开展有机地化、岩矿组成、储集层孔隙结构等特征的研究。(1)研究区泥页岩有机质丰度在0.12％～1.35％之间,具有强烈的非均质性,有机质类型以Ⅱ型为主,氯仿沥青“A”含量较高。(2)泥页岩中碳酸盐岩矿物含量最高,平均27.8％,黏土矿物和石英含量次之,有38.2％的样品检测出硬石膏,反映典型的咸化环境特征。(3)扫描电镜观察有机质孔隙发育较少,形状不规则且孔径较大,粒(晶)间孔隙直径多以微米级为主,微裂缝宽多小于1μm;低温气体吸附测试显示,中孔提供了主要的孔比表面积和孔隙体积,氯仿沥青“A”的存在对样品孔隙结构产生影响。(4)研究区泥页岩储集层中黏土矿物含量低而脆性矿物含量高,与北美页岩气产层及四川盆地龙马溪组页岩储集层岩矿特征类似,易于产生裂缝,有利于页岩气的后期开采。     

浙江外北山铝质A1型花岗岩成因：矿物学、年代学、地球化学及Hf同位素制约

外北山碱长花岗岩主要由条纹长石、更钠长石、石英和少量铁质黑云母组成,发育晶洞构造,晶洞由石英晶簇、钾长石充填。在岩石化学上,岩石富SiO2、K2O、FeO、F,贫Al_2O_3、MgO、CaO、P_2O_5;稀土元素组成上,富集REE(ΣREE变化范围为107.4×10~(-6)~330.71×10~(-6)),轻稀土分馏程度明显强于重稀土分馏,Eu负异常明显,稀土元素球粒陨石标准化配分曲线呈现"W"型四分组效应;微量元素上,富Rb、Th、Cs、U、Nb,贫Sr、Ba、P、Eu和Ti,显示出典型的铝质A型花岗岩特征。锆石LA-ICP-MS U-Pb同位素定年表明,该岩体形成时代为96.2±0.8Ma。与东南沿海其它晚中生代A型花岗岩体相比,外北山碱长花岗岩具有明显偏高的Nb/Ta和较低的Y/Nb比值,属A1型花岗岩。综合分析表明,晚白垩世早期东南沿海岩石圈强烈伸展及多组断裂活化,引发铁镁质下地壳在高温低压贫水的条件下部分熔融产生花岗质岩浆,并在结晶分异过程中受到富F流体的交代作用,形成外北山富Nb的铝质A型花岗岩。     

内蒙古阿巴嘎旗白音图嘎地区晚石炭世花岗岩地球化学特征、锆石U-Pb定年及其地质意义

内蒙古白音图嘎地区位于西伯利亚板块东南缘晚古生代陆缘增生带,地处二连—贺根山板块对接带西北侧,该区发育大量晚古生代花岗岩,主要岩石类型为斑状二长花岗岩和碱长花岗岩。本文对该区花岗岩进行了LA-ICP-MS锆石U-Pb测年和岩石地球化学测试。结果表明:斑状二长花岗岩和碱长花岗岩锆石U-Pb年龄分别为302.8±1.3Ma(MSWD=1.4)和301.1±0.6 Ma(MSWD=0.84),属于晚石炭世;岩石地球化学数据显示,岩体属钾玄岩系,具有高硅(SiO_2=70.83%~75.01%),富碱(Na_2O+K_2O=11.58%~13.20%),贫钙(CaO=0.50%~1.22%)和镁(MgO=0.11%~0.33%)特征。铝饱和指数A/CNK=0.81~1.01,为准铝—弱过铝质花岗岩。岩体整体富集Rb、Th、U等大离子亲石元素(LILEs),亏损Ba、Sr以及高场强元素(HFSEs)Nb、Ta、P、Ti;LERR富集,HERR相对亏损,具有明显的负Eu异常(δEu=0.11~0.43)。初始岩浆温度(759.33℃~801.81℃)和岩石地球化学分析表明,白音图嘎花岗岩具有A型花岗岩特征。同时,低的Nb/Ta(7.38~19.50)、Zr/Hf(29.61~35.26)和Sm/Nd(0.22~0.32)比值指示其源岩为壳源。综合研究表明,白音图嘎花岗岩为陆壳变杂砂岩部分熔融的产物,形成于晚石炭世早期西伯利亚板块和华北板块后碰撞作用的板内伸展环境,为兴蒙造山带晚古生代构造岩浆演化及古亚洲洋闭合的时限提供了新的约束和佐证实例。     

西天山阿吾拉勒成矿带群吉A型花岗岩成因、地质意义及成矿潜力评价

群吉钠长斑岩具有富Si O2(65.3%~76.9%)、Na_2O+K_2O(6.02%~9.66%)、FeOT/Mg O(6.01~21.4),中等的A/CNK(0.90~1.04),低Al2O3(9.82%~15.64%)、Ca O(0.47%~1.84%)、MgO(0.13%~0.45%)的主量元素特征,同时富集Th、U、Ta、Zr、Hf等HFSE,轻稀土富集、重稀土相对平坦分布。高的Zr(468×10~(-6)~707×10~(-6))、Y(20.7×10~(-6)~91.4×10~(-6))、Nb(21.3×10~(-6)~57.7×10~(-6))、Ga(11.2×10~(-6)~19.7×10~(-6))以及Ce(36.7×10~(-6)~98.2×10~(-6))和Zr饱和温度(880℃)特征表明岩体具有A型花岗岩的特征。群吉钠长斑岩的ISr值较低(0.70203~0.70549),εNd(t=303Ma)为正值(+4.1~+5.2),同时全岩Pb同位素落于地幔和下地壳之间的区域,表明形成该岩体的源岩可能为下地壳玄武质岩石。地壳的伸展引起了软流圈地幔底侵,在异常地温梯度下被底侵的玄武质下地壳发生部分熔融,形成该地区晚古生代A型花岗岩岩体。群吉地区A型花岗岩的发现,表明在晚石炭纪西天山阿吾拉勒地区为伸展的构造背景,同时岩石圈的拆沉、下地壳的加厚在晚石炭纪就已发生。群吉钠长斑岩中有局部或全部的铜矿化,该岩体是阿吾拉勒成矿带主要的含矿岩体。钠长斑岩基质中含有自形-半自形的黄铁矿及斑岩中锆石较低的Ce4+/Ce3+(19.5~93.0,平均为39.6),反映了岩浆低氧逸度的成岩条件,这种条件使得S从高价态变为了低价态,有利于成矿。岩浆中Zr的含量与岩浆中的水分含量成反比,H2O的加入也可以使岩浆具有高的氧逸度,因此岩浆中高的Zr含量及低的氧逸度,说明岩浆的源区为"干"体系,H2O的加入很少,而较"干"的体系对形成大型斑岩矿床不利。     

不同植被红边指数在城市草地健康判别中的对比研究

遥感红边指数与表征绿色植物生长状况的重要生化参数有密切的关系,是植被长势监测的重要因子。为寻找出最适用于城市草地生长状况监测的红边指数,本文基于Sentinel-2A数据,对比分析了不同红边指数在城市草地健康状况估算方面的差异。本文以福州市和厦门市的城市草地为例,在全面分析各种健康水平草地光谱响应特征差异的基础上,选取了6种与草地生化参数相关的红边指数,即红边位置REP、地面叶绿素指数MTCI、归一化差值红边指数NDRE1、新型倒红边叶绿素指数IRECI、红边叶绿素指数CI_red-edge以及叶绿素吸收指数MCARI2,然后采用独立样本T检验及欧式距离对这6种红边指数在草地健康判别中的优劣进行了定量对比。结果表明：IRECI指数对草地健康状况最为敏感,该指数在不同健康等级草地的值域区间和均值都存在显著性差异,其判别总精度均大于85%;NDRE1和MCARI2指数次之,其他3个指数则难以判别草地的健康状况。因此,在基于Sentinel-2A影像的城市草地健康遥感判别中,推荐使用IRECI指数。