Intrinsic sample methods for mineral exploration and resource assessment

We report on an objective methodology, referred to as intrinsic sample methodology, for the delineation of exploration target areas or resource areas for assessment. Important features of the methodology include (1) identification of recognition criteria for critical genetic factors, (2) synthesis of new variables from enhanced geodata, (3) estimation of logit probability models, and (4) cutting of estimated logit probabilities to delineate exploration targets or resource areas. The methodology is demonstrated on the Walker Lake quadrangle of Nevada and California.     

DMC＋4小卫星在国际灾害监测中的应用与评价

针对国际灾害监测星座应用技术和中国各种自然灾害的现状,着重研究了DMC(DisasterMonitoringConstellation)星座应用技术和DMC 4小卫星的数据特点,研究了利用小卫星星座对防灾、抗灾救灾的突出作用,研究了小卫星地面系统集成技术和星地一体化运营、管理和控制体系,以便进一步推动国内小卫星技术、遥感应用技术、卫星星座技术、天地一体化运管控技术和机制创新的发展。促进中国灾害监测星座的研制,最终实现对各种自然灾害的实时、动态监测。     

LINKAGE BETWEEN INDIAN OCEAN DIPOLE AND TWO TYPES OF El NI?O AND ITS POSSIBLE MECHANISMS

After compositing three representative ENSO indices,El Nio events have been divided into an eastern pattern(EP) and a central pattern(CP).By using EOF,correlation and composite analysis,the relationship and possible mechanisms between Indian Ocean Dipole(IOD) and two types of El Nio were investigated.IOD events,originating from Indo-Pacific scale air-sea interaction,are composed of two modes,which are associated with EP and CP El Ni o respectively.The IOD mode related to EP El Nio events(named as IOD1) is strongest at the depth of 50 to 150 m along the equatorial Indian Ocean.Besides,it shows a quasi-symmetric distribution,stronger in the south of the Equator.The IOD mode associated with CP El Nio(named as IOD2) has strongest signal in tropical southern Indian Ocean surface.In terms of mechanisms,before EP El Nio peaks,anomalous Walker circulation produces strong anomalous easterlies in equatorial Indian Ocean,resulting in upwelling in the east,decreasing sea temperature there;a couple of anomalous anticyclones(stronger in the south) form off the Equator where warm water accumulates,and thus the IOD1 occurs.When CP El Nio develops,anomalous Walker circulation is weaker and shifts its center to the west,therefore anomalous easterlies in equatorial Indian Ocean is less strong.Besides,the anticyclone south of Sumatra strengthens,and the southerlies east of it bring cold water from higher latitudes and northerlies west of it bring warm water from lower latitudes to the 15° to 25°S zone.Meanwhile,there exists strong divergence in the east and convergence in the west part of tropical southern Indian Ocean,making sea temperature fall and rise separately.Therefore,IOD2 lies farther south.     

Impact of the thermal state of the tropical western Pacific on onset date and process of the South China Sea summer monsoon

Since the early or late onset of the South China Sea summer monsoon （SCSM） has a large impact on summer monsoon rainfall in East Asia, the mechanism and process of early or late onset of the SCSM are an worthy issue to study. In this paper, the results analyzed by using the observed data show that the onset date and process of the SCSM are closely associated with the thermal state of the tropical western Pacific in spring. When the tropical western Pacific is in a warming state in spring, the western Pacific subtropical high shifts eastward, and twin cyclones are early caused over the Bay of Bengal and Sumatra before the SCSM onset. In this case, the cyclonic circulation located over the Bay of Bengal can be early intensified and become into a strong trough. Thus, the westerly flow and convective activity can be intensified over Sumatra, the Indo-China Peninsula and the South China Sea （SCS） in mid-May. This leads to early onset of the SCSM. In contrast, when the tropical western Pacific is in a cooling state, the western Pacific subtropical high anomalously shifts westward, the twin cyclones located over the equatorial eastern Indian Ocean and Sumatra are weakened, and the twin anomaly anticyclones appear over these regions from late April to mid-May. Thus, the westerly flow and convective activity cannot be early intensified over the Indo-China Peninsula and the SCS. Only when the western Pacific subtropical high moves eastward, the weak trough located over the Bay of Bengal can be intensified and become into a strong trough, the strong southwesterly wind and convective activity can be intensified over the Indo-China Peninsula and the SCS in late May. Thus, this leads to late onset of the SCSM. Moreover, in this paper, the influencing mechanism of the thermal state of the tropical western Pacific on the SCSM onset is discussed further from the Walker circulation anomalies in the different thermal states of the tropical western Pacific.     

温室气体的卫星遥感—进展与趋势

二氧化碳和甲烷减排是控制全球增温最核心的手段,传统的人为碳排放计算主要依赖于在线监测和清单算法,2019年第49届1PCC全会明确了利用大气观测通过"自上而下"通量计算对排放清单进行支撑和验证,因此了解大气遥感碳监测发展趋势以及同化反演技术方法成为了中国应对国际气候变化事务亟待探明的重要问题.根据卫星遥感技术发展进程和...     

卫星导航增强系统建设与发展

自卫星导航系统诞生以来,人们发展了多种增强技术和手段,并建立了大批增强系统,以满足用户更高精度和完好性的需求.由于卫星导航增强技术客观上晚于基本系统出现,且都是按需独立建立,因此不可避免地存在着"碎片"和"补丁"式发展问题,相互之间功能重叠,缺乏统一的规划和标准,未成体系化建设.本文回顾和总结了卫星导航增强技术的产生和发展历程,梳理了相关技术内涵与定义,并重点介绍了中国北斗卫星导航系统(BDS)增强体系的建设和发展情况.在此基础上,结合5G通信、低轨卫星等新兴技术,对卫星导航增强体系未来发展动态进行了展望和分析,并对未来北斗定位、导航与授时(PNT)综合服务中的增强体系建设提出了建议.     

利用多频多系统GNSS OEM板卡实现高精度变形监测

针对近年来被广泛应用的多频多系统GNSS OEM板卡,设计并实现了一套基于多频多系统OEM板卡的低成本变形监测系统,包括数据解码、基线处理、网平差和坐标转换等,能够实时获取测站点高精度空间坐标。以某高层建筑形变监测为例,通过串口通信获取板卡多频多系统观测信息,并经过该系统解算,实现了监测点实时定位,且系统成本相比市场上测量型GNSS接收机系统下降了约40%。实验结果表明,该系统解码精度可达0.2 mm,静态模式定位精度可达到平面2 mm以内,高程5 mm以内,动态模式定位精度可达到平面5 mm以内,高程10 mm以内,验证了该系统的可靠性和适用性。     

Interdecadal Variability of the East Asian Summer Monsoon and Associated Atmospheric Circulations

Based on the National Centers for Environmental Prediction and National Center for Atmospheric Research （NCEP/NCAR） reanalysis data from 1950-1999, interdecadal variability of the East Asian Summer Monsoon （EASM） and its associated atmospheric circulations are investigated. The EASM exhibits a distinct interdecadal variation, with stronger （weaker） summer monsoon maintained from 1950-1964 （1976-1997）. In the former case, there is an enhanced Walker cell in the eastern Pacific and an anti-Walker cell in the western Pacific. The associated ascending motion resides in the central Pacific, which flows eastward and westward in the upper troposphere, descending in the eastern and western ends of the Pacific basin. At the same time, an anomalous East Asian Hadley Cell （EAHC） is found to connect the low-latitude and mid-latitude systems in East Asia, which strengthens the EASM. The descending branch of the EAHC lies in the west part of the anti-Walker cell, flowing northward in the lower troposphere and then ascending at the south of Lake Baikal （40°-50°N, 95°- 115°E） before returning to low latitudes in the upper troposphere, thus strengthening the EASM. The relationship between the EASM and SST in the eastern tropical Pacific is also discussed. A possible mechanism is proposed to link interdecadal variation of the EASM with the eastern tropical Pacific SST. A warmer sea surface temperature anomaly （SSTA） therein induces anomalous ascending motion in the eastern Pacific, resulting in a weaker Walker cell, and at the same time inducing an anomalous Walker cell in the western Pacific and an enhanced EAHC, leading to a weaker EASM. Furthermore, the interdecadal variation of summer precipitation over North China is found to be the south of Lake Baikal through enhancing and reducing strongly regulated by the velocity potential over the regional vertical motions.     

BDS卫星失效对区域定位精度的影响评估

基于STK软件实现了2016-09 BDS系统星座结构的仿真,并选取可见卫星数、DOP值、系统可用性作为评估BDS卫星星座设计结构的指标,分析单颗与全部倾斜轨道卫星（IGSO）、地球静止轨道卫星（GEO）失效后对我国大陆地区BDS系统可用性的影响。结果表明,IGSO4卫星与GEO5卫星失效后对BDS在区域的定位性能影响较大,失效后的GDOP值分别为1.98、2.16。取BDS卫星正常运行时区域平均GDOP最大值(S=2.60)作为系统可用性阈值时,系统可用性分别降低了1.79%、32.63%;阈值取2S(5.20)、3S(7.80)、4S(10.40)、5S(13.00)时,系统可用性均可达100.00%。GEO整体失效后BDS系统在高精度定位中仍部分可用,而IGSO整体失效后BDS系统可用性受到大幅度限制。因此,增加在轨备份卫星时需重点考虑GEO5、IGSO4,并适当增加IGSO卫星的数目。     

北斗混合星座分层约束下的精密定轨方法

针对北斗导航卫星系统首创的GEO+IGSO+MEO混合星座设计,本文研究了根据不同星座,采取不同约束条件和数据处理策略的北斗卫星精密定轨方法,提出了一种针对北斗系统混合星座的分层约束精密定轨方案.该方案首先将北斗卫星分为非GEO(IGSO/MEO)和GEO两部分进行解算,利用GPS解算的公共参数对北斗IGSO/MEO精...