Analysis of Cloud Scale Error of Low Resolution Satellite Based on GF-4 and Its Influence on Downward Radiation Calculation

In order to study the scale error of low resolution meteorological satellite cloud detection and its impact on the calculation of downlink radiation, cloud detection using high resolution stationary satellite GF-4 data and error analysis were carried out. Firstly, the cloud detection of GF-4 data is carried out by using visible channel threshold method and time series method, and the error of cloud detection results of Himawari-8 and FY-2 (FY-2G, FY-2E) is analyzed based on the results of GF-4 cloud detection.In the study area, FY-2G, FY-2E and Himawari-8 cloud images could distinguish the clouds and clear sky. The main reason for the error was the scale effect produced by different spatial resolution satellites(the differences caused by cloud detection algorithms are not discussed here).Most of the errors occurred in the areas of thin clouds and broken clouds.High resolution data could detect broken clouds, while low resolution data lead to false and missed detection. On this basis, the error of remote sensing calculation of short wave radiation was analyzed,and it was found that the error of the actual cloud amount in the pixel would bring significant error to the estimation of the downward radiation.The relative error of the instantaneous downward radiation in the selected test area was -173.52%, and the maximum relative error of shortwave radiation was -20.20%.The results show that the high resolution stationary satellite data can significantly improve the estimation accuracy of the downlink shortwave radiation in the regions with more broken clouds.     

卫星遥感监测我国沿海水色环境的研究

本文首先概要地介绍了国际上20世纪80年代以来卫星水色遥感器的发展,以及我国在90年代建立的海洋水色遥感应用技术系统,包括资料接收、处理、查询、分发、试应用和辐射验证等系统,重点论述了利用我国的FY-1C卫星以及美国的SeaWiFS和AVHRR卫星资料监测我国沿海的水色环境,包括沿海水体的叶绿素和悬浮泥砂浓度的时空分布,赤潮的监测以及沿海海区流场的研究。研究表明,卫星海洋水色遥感技术在海洋渔业资源的开发和保护、海岸带区牧化管理、河口港湾工程环境评价、海洋污染环境的监测和动力学研究等方面有广宽的应用前景。     

General introduction on payloads, ground segment and data application of Fengyun 3A

Fengyun 3 series are the second-generation polar-orbiting meteorological satellites of China. The first satellite of Fengyun 3 series, FY-3A, is a research and development satellite with 11 payloads onboard. FY-3A was launched successfully at 11 a.m. on May 27, 2008. Since the launch, FY-3A data have been applied to the services on the flood season and the Beijing 2008 Olympic Games. In this paper, the platform, payloads, and ground segment designs are introduced. Some typical images during the on-orbit commission test are rendered. Improvements of FY-3A on Earth observations are summarized at the end by comparing them with FY-1D, the last satellite of Fengyun 1 series.     

用气象卫星遥感监测沙尘暴的方法和初步结果

本文在简要介绍气象卫星探测特点的基础上,着重讨论了利用NOAA卫星、FY-1C卫星和GMS-5及FY-2B卫星上的星载扫描辐射仪监测沙尘暴的原理和方法.最后以2000年4月6～7日发生在我国内蒙古地区至华北一带的强沙尘暴为例,说明用这种手段不仅能监测到沙尘暴的发生,还能有效地监测其发展和演变,是监测和预警沙尘暴的重要手段和依据.     

Magmatic Gradients in the Cretaceous Caleu Pluton (Central Chile): Injections of Pulses from a Stratified Magma Reservoir

The Caleu pluton (Central Chile) extending over 338 km² and with more than 1, 400 m of vertical relief intrudes the N-S trending Lower Cretaceous volcano-sedimentary and volcanic successions at a depth equivalent to a pressure of 2 kb. The host, stratified volcanic successions, are tilted about 30°–40° E, whereas the pluton shows paleomagnetic evidence of either tilting of <15° E or clockwise rotation by few degrees.A gradient of westward increasing SiO₂ content is recognized across the pluton, giving rise to three N-S elongated zones: Gabbro/Diorite Zone (GDZ), Tonalite Zone (TZ) and Granodiorite Zone (GZ). Biotite and hornblende compositions also exhibit a westward decreasing gradient in Mg/(Mg+Fe), indicating that the more mafic the zone is, the more oxidizing is its crystallization condition. Horizontal inward gradients of progressively less evolved rocks are recognized across GDZ and TZ, whereas no horizontal gradients were found in the GZ. Vertical compositional gradients are recognized in the GDZ and TZ, which consist of an upward increase in SiO₂ and decrease in MgO, FeO, Fe₂O₃, and compatible trace elements. A vertical compositional boundary was recognized along a traverse across the TZ separating two magma pulses with similar trends of compositional variations.The three zones of the Caleu pluton were derived from a common isotopically (Sr-Nd) depleted source. Each zone probably evolved independently, as their compositional characteristics would have not been acquired in situ. The resulting compositional characteristics of the zones would have been developed prior to the intrusion, in a subjacent stratified reservoir placed at about seven kilometers below the pluton.     

FY-3 A/MERS I积雪制图中NDS I指标建立及积雪判识模型研究 ——以祁连山区为例

我国新型自主的极轨气象卫星风云3号A星（简称FY-3A）上搭载的中分辨率光谱成像仪（MERSI）为大面积雪监测提供了新的遥感数据源。以中国西北祁连山区为例,分析FY-3A/MERSI传感器积雪与其它地物的图谱特征差异,建立了适用于FY-3A/MERSI的归一化差分积雪指数（NDSI）,以此为基础,构建了综合利用多光谱判别指标及土地覆盖类型（LULC）定类辅助的积雪判识模型,生成250 m分辨率的日积雪制图产品。模型通过逐步逼近的树状判别结构,去除了易和积雪混淆的部分乔木林、云、云阴影、水体、湖冰、沙（盐）地等地物,并提出应考虑积雪下覆地表特性的影响,调整设定不同LULC类型的积雪判别阈值约束,实时结合区域LULC影像进行积雪的最终判定与优化。对祁连山区2010-2011年积雪季FY-3A/MERSI影像的积雪制图应用结果表明,该资料能够客观精细地反映积雪的空间分布与动态发展过程。同时利用气象台站积雪观测记录及Terra/MODIS积雪判识结果进行对比验证,结果表明基于FY-3A/MERSI建立的积雪判识模型具有较高的精度和稳定性,特别是提高了云雪区分的效能。     

Is there any detachment in the Lower Dolpo (western Nepal)?Y a-t-il un détachement dans le bas Dolpo (Népal occidental) ?

A structural transect in the Lower Dolpo highlights that the deformation and metamorphism of the Tibetan Zone (TZ) increase toward the bottom of the sequence. The contact with the underlying HHC is marked by a metamorphic jump from amphibolite facies in the carbonatic rocks of the upper part of the HHC to greenschist facies marbles in the TZ. Moreover, the HHC and the TZ show different metamorphic histories. The contact zone shows a strain increase accompanied by asymmetric folds with a top-to-the-northeast vergence, connected to a down-to-the-northeast tectonic transport. The contact is interpreted as an extensional shear zone, connected to the South Tibetan Detachment System. To cite this article: R. Carosi et al., C. R. Geoscience 334 (2002) 933–940.     

FY-3C VIRR大气可降水产品在新疆地区的精度评价

探讨FY-3C VIRR大气可降水产品在新疆地区的可靠性,基于探空数据,采用多评价指标,对FY-3C VIRR大气可降水量的旬产品和月产品进行全面评估.结果表明:FY-3C VIRR旬和月大气可降水产品与探空数据变化一致,但存在系统性高估;在一年时间中,旬产品和月产品均具有单峰变化特征,旬产品与探空数据的误差在4月上旬...     

On the water and energy cycles in the Tropics

The water and energy cycles are major elements of the Earth climate. These cycles are especially active in the intertropical belt where satellites provide the most suitable observational platform. The history of Earth observations of the water cycle and of the radiation budget viewed from space reveals that the fundamental questions from the early times are still relevant for today's research. The last 2 decades have seen a number of milestones regarding the documentation of rainfall, mesoscale convective systems (MCS), water vapour and radiation at the top of the atmosphere (TOA). Beyond dedicated missions that provided enhanced characterizations of some elements of the atmospheric water cycle and field campaigns that allowed the gathering of validation data, the advent of the long record of meteorological satellites lead to new questioning on the homogenisation of the data time series, etc. The use of this record to document the tropical climate brought new results of the distribution of humidity and reinforced the understanding of some robust features of the African monsoon. Challenges for the immediate future concerns the deepening of the understanding of the role of cloud systems in the monsoon circulation, the downscaling of the documentation of the water and energy cycle at the scale of these cloud systems, the research of better adequation between the users and the satellite estimate of rainfall and finally a much needed methodological effort to build exploitable time series for the estimation of climatic trends in the water and energy cycle in the Tropics. The required observations to address these challenges are rapidly presented with emphasis on the upcoming Megha-Tropiques (MT) mission.     

Snow cover depletion under changed climate with the help of remote sensing and temperature data

Snow cover depletion curve (SDC) is one of the important variables in snow hydrological applications, and these curves are very much required for snowmelt runoff modeling in a snowfed catchment. Remote sensing is an important source of snow cover area which is used for preparation of SDC. Snow cover maps produced by Moderate Resolution Imaging Spectroradiometer (MODIS) satellites are one of the best source of satellite-based snow cover area at a regular interval. Therefore, in this study, snow cover maps have been prepared for the years 2000?C2005 using MODIS data. The study area chosen viz. Beas basin up to Pandoh dam falls in western Himalayan region. For snowmelt runoff modeling, catchment is divided into number of elevation zones and SDC is required for each zone. When sufficient satellite data are not available due to cloud cover or due to some other reasons, then SDC can to be generated using temperature data. Under changed climate conditions also, modified SDC is required. Therefore, to have SDC under such situations, a relationship between snow cover area and cumulative mean temperature has been developed for each zone of the catchment. This procedure of having snow cover maps has two main purposes. First, it could potentially be used to generate snow cover maps when cloud-free satellite data are not available. Second, it can be used to generate snow-covered area in a new climate to see the impact of climate change on snowmelt runoff studies.     

Soil moisture from operational meteorological satellites

In recent years, unforeseen advances in monitoring soil moisture from operational satellite platforms have been made, mainly due to improved geophysical retrieval methods. In this study, four recently published soil-moisture datasets are compared with in-situ observations from the REMEDHUS monitoring network located in the semi-arid part of the Duero basin in Spain. The remotely sensed soil-moisture products are retrieved from (1) the Advanced Microwave Scanning Radiometer (AMSR-E), which is a passive microwave sensor on-board NASA’s Aqua satellite, (2) European Remote Sensing satellite (ERS) scatterometer, which is an active microwave sensor on-board the two ERS satellites and (3) visible and thermal images from the METEOSAT satellite. Statistical analysis indicates that three satellite datasets contribute effectively to the monitoring of trends in surface soil-moisture conditions, but not to the estimation of absolute soil-moisture values. These sensors, or rather their successors, will be flown on operational meteorological satellites in the near future. With further improvements in processing techniques, operational meteorological satellites will increasingly deliver high-quality soil-moisture data. This may be of particular interest for hydrogeological studies that investigate long-term processes such as groundwater recharge.     

脂肪酸在古土壤层和黄土层中的分布差异及其环境指示意义

陕西洛川黄土剖面中的黄土层及古土壤层中脂肪酸存在显著差异：黄土层中的正构脂肪酸以不对称的双峰分布，前峰高于后峰，Ｃ１６：０为主峰；古土壤层中，脂肪酸以三组峰分布，Ｃ９，Ｃ１６，Ｃ２８近乎相等；古土壤层中的异构脂肪酸有ｉＣ１７，ｉＣ１９，反异构脂肪酸有ａｉＣ１４，ａｉＣ１５，ａＩＣ１７，ａｉＣ２０等，黄土层中几乎不见它们的，均含有Ｃ１６；１，Ｃ１８：１不饱和脂肪酸，其中Ｃ１８；１含量高。Ｌ２，Ｓ２的     

Contaminant leaching from gold mining tailings dams in the Witwatersrand Basin,South Africa: A new geochemical modelling approach

In this study a new geochemical reaction modelling methodology is used to shed light on the geochemical processes within Witwatersrand tailings impoundments and the evaluation of the geochemical impacts for future mining projects is evaluated. Information from international and local studies on tailings sulphidic tailings impoundments is used to develop a conceptual understanding on a typical Witwatersrand gold tailings impoundment. The tailings impoundments consist of 3 distinct geochemical zones: Oxidation Zone (OZ), a Transition Zone (TZ) and a Reduction Zone (RZ). Individual reaction models are developed for each of the 3 zones. The output of one model is used as an input to the next in spatial order. The results of the final model represent the tailings basal seepage characteristics, which indicate the most likely impacts on groundwater resources. The model results agree with existing information on AMD in the Witwatersrand. The results indicate that the tailings basal seepage is likely to be acidic (pH of ∼3.5), containing elevated concentrations of SO₄ and trace metals (Al, Co, Cr, Cu, Mn, Ni, Zn and U). Predicted Fe concentrations are low, due to the low $f_{{\text{O}}_2}$ in the TZ and RZ and the buffering effect of the precipitation of K-jarosite in the OZ and TZ. This study therefore indicates that the methodology employed produces results that can be correlated to existing information and can thus be used as a methodology in the assessments of impacts from sulphidic tailings material for future mining projects.     

基于FY-3 MWRI数据的北极海冰密集度反演研究

以ASI算法（ARTIST sea ice algorithm）为基础, 得到基于风云3C气象卫星（FY-3C）微波辐射计（MWRI）数据的纯水与纯冰系点值, 利用插值方法确定基于FY-3 MWRI数据的ASI海冰密集度计算公式, 采用大津法（Otsu算法）得到基于MWRI数据的天气滤波器阈值。以2016年1月数据为例, 对北极海冰密集度进行反演, 并与美国国家冰雪数据中心（NSIDC）以及德国不莱梅大学提供的海冰密集度产品进行对比验证。结果表明： 基于MWRI数据得到的1月平均海冰面积以及平均密集度均介于二者之间, 其中平均密集度与不莱梅产品更接近, 仅相差1.310%。与风云卫星空间分辨率为250 m的中分辨率光谱成像仪（MERSI）数据得到的结果进行对比, 发现二者的海冰外缘线基本一致, MERSI数据得到的海冰密集度以及海冰面积比MWRI数据得到的结果分别高出5.029%、 9.318%。因此, 应用该方法可有效推进MWRI数据反演北极海冰密集度, 进而监测北极海冰分布和变化。     

Surveillance of Vrancea active seismic region in Romania through time series satellite data

Cumulative stress energy in active seismic regions caused by tectonic forces creates various earthquake precursors. This energy transformation may result in enhanced transient thermal infrared (TIR) emission, which can be detected through satellites equipped with thermal sensors like MODIS (Terra/Aqua) and AVHRR (NOAA). Satellite time-series data, coupled with ground based observations, where available, can enable scientists to survey pre-earthquake signals in the areas of strong tectonic activity. This paper presents observations made using time series MODIS and NOAA-AVHRR satellite data for derived multi-parameters including land surface temperature (LST), outgoing long-wave radiation (OLR), and mean air temperature (AT) for the moderate, 5.9 magnitude earthquake, which took place on the 27^th of October, 2004, inthe seismic region of Vrancea, in Romania. Anomalous thermal infrared signals, reflected by a rise of several degrees celsius (°C) in LSTs, and higher OLR values were seen several days before the earthquake. AT values in the epicentral area also increased almost two days prior to the earthquake and intensified three days after the main shock. Increases in LSTs and OLR disappeared three days after the main shock. The survey and joint analysis of geospatial and in-situ geophysical information on land surface temperatures and outgoing long-wave radiation provides new insights into the field of seismic hazard assessment in Vrancea, a significant area of tectonic activity in Romania and Europe.     

Quality Assessment of the Beidou-3 New Signal B1C and B2a Observation Data*

With the successful launch of the sixteen MEO satellites of the Beidou-3 global satellite navigation system and the broadcast of new signals, Beidou has officially entered the global construction stage while the international GNSS Monitoring and Assessment System (iGMAS) is also performing systematic testing and evaluation on various aspects of operational performance from satellite end to ground receiving end of Beidou-3 system. This paper analyzed and evaluated the observation quality of new signals B1C and B2a broadcasted by the twelve new Beidou-3 MEO satellites on the observation data integrity rate, multipath error, pseudorange noise and Carrier-to-Noise Ratio (CNR) compared with GPS and GALILEO. The results show that the observation data integrity rate of B1C signal is better than that of B2a signal in the Beidou-3 system. In the aspects of multipath error, pseudorange noise and CNR, B2a signal is better than that of B1C. The performances of the twelve MEO satellites of Beidou-3 are equivalent, that is, for Beidou-3, the consistency of satellites can be guaranteed. In terms of pseudo-range noise, Beidou-3 is slightly worse than GPS and GALILEO While the observation data integrity rate, multipath error and CNR of Beidou-3 are equivalent to those of GPS and GALILEO.     

我国海洋光学遥感应用科学研究的新进展

20世纪90年代以来,我国航天遥感事业的发展促进了海洋光学应用科学的发展,特别是通过近几年来,国家“863”高新技术计划的实施,在该方面有了新进展。文章将着重介绍光学遥感信息的大气校正、光学遥感海洋环境信息提取、光学遥感在赤潮与溢油监测等3个方面的应用科学新进展,并提出了在我国进一步深入开展海洋光学遥感应用科学技术研究的建议。     

Observation of the Earth's radiation budget from space

The planet's radiation budget includes practically all energy exchange between the Sun, the Earth, and space, and so is a fundamental factor of climate. The terms of this budget, observable only from space, are determined from sampled direct measurements of the solar and terrestrial radiation fields. On the contrary, however, it should be remembered that energy exchange between the Earth's surface and its atmosphere involves not only radiative but also non-radiative energy fluxes. Nevertheless, only observations from space can provide satisfactory global coverage of the different energy fluxes that determine climate at the Earth's surface, by way of indirect retrievals of radiative fluxes at the surface and at different heights in the atmosphere. We describe the methods, applied to measurements made with a variety of instruments on board different artificial satellites, that have led to our present knowledge of the Earth's radiation budget (ERB) at the “top of the atmosphere”: global annual mean values of the ERB terms, its annual cycle, its geographical structure, and its variations. We know that solar irradiance, averaged over the globe and the year, varies by only 0.1% with the solar activity cycle; we also know that planetary (Bond) albedo is close to 0.3, that the global annual mean emission of thermal infrared radiation to space is close to 240 Wm^?2, and that these terms exhibit a weak but well determined annual cycle. We also know that cloud cover plays a major role in the radiation budget, both in the “shortwave” domain (global SW “cloud radiative forcing” –50 Wm^?2) and in the “longwave” domain (+20 Wm^?2), thus a net forcing of –30 Wm^?2. Successive satellite missions give consistent results for the shape, the phase, and the amplitude of the annual cycle of the planetary radiation balance. However, the different estimates of its annual mean absolute value remain uncertain, not differing significantly from zero, although generally excessively positive. We also rapidly review the methods used to determine the surface radiation budget as well as that of the atmosphere. For the planetary (TOA) radiation budget, we examine to what extent interannual variations and interdecadal trends have been or could be detected. We conclude with a review of projects under way. We also discuss priorities for future efforts, considering in particular, on the one hand (Ringer, 1997), the need to better quantify the factors that govern climate sensitivity to modifications of the atmosphere's radiative properties, on the other hand, the importance of monitoring the evolution of the present disequilibrium situation.     

Stratigraphy,pollen analysis,and paleoclimatic interpretation of Pulbeena Swamp,northwestern Tasmania

Sedimentary, palynologic, and ¹⁴C analysis of 480 cm of freshwater marl and swamp-peat deposits, formed under the influence of fluctuating artesian springs, provides a paleoenvironmental and paleoclimatic record of approximately 65,000 yr for northwestern Tasmania.The Holocene (Pollen Zone 1, 11,000-0 yr B.P.) climate was warm and moist, and forest vegetation was dominant throughout the area. During the later part of the last glacial stage (Pollen Zone 2, 35,000–11,000 yr B.P.) the climate was generally drier, and grassy open environments were widespread. The driest part of this period occurred between 25,000 to 11,000 yr B.P., when temperatures in western Tasmania were markedly reduced during the last major phase of glaciation. Prior to 35,000 yr B.P. (Pollen Zones 3–9) a long “interstadial complex” dating to the middle of the last glacial stage is recognized. During this period the climate was generally moist, and forest and scrub communities were more important than during the later part of the last glacial stage, except during Pollen Zone 5 when high Gramineae plus Compositae values suggest drier conditions. High Gramineae and Compositae values also occur in Pollen Zone 10 at the base of the diagram. They suggest that a phase of drier and cooler climatic conditions occurred during the early part of the last glacial stage.     

Stable carbon-isotope stratigraphy and ammonite biochronology at Madotz,Navarra, northern Spain: implications for the timing and duration of oxygen depletion during OAE-1a

Detailed stable carbon-isotope and biostratigraphic data based on ammonites allow us to reinterpret the timing of the different units of the Madotz section (62 m thick) in Navarra, northern Spain, relative to OAE-1a. We also infer bulk sedimentary rates and the duration of the intervals that include facies indicative of oxygen depletion. The lowermost part of the sequence includes the predominately clastic unit 1 (3 m) overlain in ascending order by subunits 2a (20 m), 2b (24.4 m) and 2c (basal 15 m studied) of the “Madotz Limestone”. Subunits 2a and 2c consist of Urgonian-type pure carbonate rocks. In contrast, subunit 2b consists of mixed carbonate–clastic facies (24.4 m thick) including beds of claystone and clay/shale with dispersed pyrite and scarce or no benthic foraminifera suggestive of oxygen-depleted conditions, and intermittent orbitolinid-rich intervals. δ¹³C_org data within subunit 2b, between 26.6 and 49.2 m show two excursions of 4.21 and 3.34‰, separated by a central segment with more uniform values around 22.56%. Compared to the high-resolution δ¹³C stratigraphy of the Early Aptian of the Alpine Tethys, these two positive excursions correlate with segments C4 and C6 of OAE-1a, whereas the central segment correlates with segment C5. New ammonite findings include Deshayesites cf. forbesi Casey and Pseudohaploceras? sp. in the uppermost part of unit 1, and D. cf. forbesi Casey, Pseudosaynella bicurvata (Michelin) and P. raresulcata (d'Orbigny) in the middle part of subunit 2b. The presence of D. cf. forbesi in unit 1 (0–37.7 m) and subunit 2b (lower 14.7 m), the first appearance datum of Pseudosaynella in subunit 2b, and the high relative abundance of Pseudosaynella specimens, support a stratigraphic position correlative with at least the upper part of the D. forbesi Zone (formerly D. weissi Zone). Such an ammonite faunal assemblage implies a lower stratigraphic position in the Lower Aptian (Bedoulian) than previously assigned to the section. Segments C4 and most of C5 comprise the lower part of subunit 2b and correspond to the upper part of the D. forbesi Zone. Based on chemostratigraphic correlations with published Spanish sections (Barranco de las Calzadas, Cap de Vinyet and Cau) in which calibrations of δ¹³C_carb stages with ammonite zones was possible, we infer that the interval of the Madotz section between 37.7 and 53.1 m, or the upper part of subunit 2b and the basal part of subunit 2c, whose δ¹³C_org signal is indicative of stages C5, C6, and perhaps the beginning of stage C7, also correlates with the D. forbesi Zone. Average bulk sedimentation rate for C-isotope stages C4–C6 of OAE-1a ranges from 1.8 to 2.09 cm/kyr in the Madotz section. Facies indicative of oxygen deficiency are restricted to C-isotope stage C4 and part of C5 of OAE-1a. Hypoxic conditions lasted about 95.23–120 kyr and are coeval with deposition of the most prominent claystone and shale layers (1.8 m thick), which display the lowest TIC values (8.16–18.93 weight% CaCO₃) and the highest TOC in the section (0.4–0.97%).