重力恢复与气候实验(gravity recovery and climate experiment,GRACE)数据解算出的时变重力场模型为陆地水储量的研究提供了一种全新的途径,然而,GRACE数据只能解算出格网点分辨率上总体的水储量变化,包括地表水、土壤水、地下水和植...重力恢复与气候实验(gravity recovery and climate experiment,GRACE)数据解算出的时变重力场模型为陆地水储量的研究提供了一种全新的途径,然而,GRACE数据只能解算出格网点分辨率上总体的水储量变化,包括地表水、土壤水、地下水和植被水等,却无法分离垂直层面上不同深度的水储量成分。采用小波分解方法,将扣除全球陆地数据同化系统水文模型地表水成分的GRACE信号进行分解,利用分解得到的小波子函数结合美国区域内的水井实测数据对地下水成分进行回归分析,并通过二维曲面插值的方法得到全美地区不同小波子函数的回归系数,以此来重构长时间连续的地下水储量变化序列。结果表明,在测试点位中61.84%以上的点位其相关系数达到0.4以上,62.90%的点位其均方根值在1.0 m以下,此方法可以得到地下水时空分布特征,为地下水资源的利用与研究提供数据支撑。展开更多
干旱是全球范围内普遍存在的自然灾害,对环境、生态、经济和社会等多个方面产生深远影响。GRACE(Gravity Recovery and Climate Experiment)重力卫星通过测量地球重力场变化数据可动态监测陆地水储量变化。应用GRACE获得的水储量时空分...干旱是全球范围内普遍存在的自然灾害,对环境、生态、经济和社会等多个方面产生深远影响。GRACE(Gravity Recovery and Climate Experiment)重力卫星通过测量地球重力场变化数据可动态监测陆地水储量变化。应用GRACE获得的水储量时空分布信息,可监测干旱,以研究干旱事件的发生、发展与演变过程。采用文献计量法分析总结了GRACE卫星数据在地下水储量变化、气象与水文干旱演变规律与响应、干旱预警等方面的应用现状及存在数据验证与数据插补重建方面的问题,并展望了变化环境下水储量变化、构建更适合干旱监测的干旱指数、提高GRACE数据精度、提升GRACE数据时空分辨率、干旱预警和决策支持以及区域水循环和生态系统响应等研究方向,可为后续的相关应用研究提供一定参考价值。展开更多
相较于传统的两步法,动力学一步法能充分利用观测数据的原始信息,理论上可获得更合理的时变重力场产品,同时也因其涉及的参数维度更多样、函数模型更复杂,一直是当前研究的热点和难点.本文研究并实现了动力学一步法恢复时变重力场,给出...相较于传统的两步法,动力学一步法能充分利用观测数据的原始信息,理论上可获得更合理的时变重力场产品,同时也因其涉及的参数维度更多样、函数模型更复杂,一直是当前研究的热点和难点.本文研究并实现了动力学一步法恢复时变重力场,给出了合理的数据处理策略,而后基于GRACE-FO(GRACE Follow-On)星载GPS数据和KBR(K/Ka Band Ranging)距离变率数据反演了2021—2022年60阶全球月时变重力场模型.对于一步法中诸多技术细节,本文重点分析了先验权和经验参数对轨道确定和模型反演的影响,研究表明:当采用30 s采样率的GPS数据时,需适当对GPS数据降权,以免引入过多噪声,码伪距、载波相位和KBR距离变率数据的先验权比应为1:104:1014;为了保证轨道和模型质量,在反演过程中有必要引入经验参数以吸收残余的摄动力误差,相较其他经验参数(分段周期经验加速度、几何经验参数),分段常经验加速度在保证定轨精度的同时可更有效地吸收模型中的噪声.此外,在采用相同动力学参数配置时,动力学一步法反演的时变重力场模型无论是与官方模型的一致性还是内符合精度均优于两步法.最后,综合评估了整个时间跨度的轨道和时变重力场模型质量,结果显示,动力学一步法确定的轨道可满足厘米级需求,双星的卫星激光测距残差标准差均为1.6 cm,重力场模型与官方机构CSR(Center for Space Research)、JPL(Jet Propulsion Laboratory)、GFZ(GeoForschungsZentrum Potsdam)最新发布的RL06.1模型一致性较好,在保留完整时变信号特征的前提下,噪声表现与CSR模型相当,优于JPL、GFZ模型.展开更多
The occurrence of earthquakes is closely related to the crustal geotectonic movement and the migration of mass,which consequently cause changes in gravity.The Gravity Recovery And Climate Experiment(GRACE)satellite da...The occurrence of earthquakes is closely related to the crustal geotectonic movement and the migration of mass,which consequently cause changes in gravity.The Gravity Recovery And Climate Experiment(GRACE)satellite data can be used to detect gravity changes associated with large earthquakes.However,previous GRACE satellite-based seismic gravity-change studies have focused more on coseismic gravity changes than on preseismic gravity changes.Moreover,the noise of the north–south stripe in GRACE data is difficult to eliminate,thereby resulting in the loss of some gravity information related to tectonic activities.To explore the preseismic gravity anomalies in a more refined way,we first propose a method of characterizing gravity variation based on the maximum shear strain of gravity,inspired by the concept of crustal strain.The offset index method is then adopted to describe the gravity anomalies,and the spatial and temporal characteristics of gravity anomalies before earthquakes are analyzed at the scales of the fault zone and plate,respectively.In this work,experiments are carried out on the Tibetan Plateau and its surrounding areas,and the following findings are obtained:First,from the observation scale of the fault zone,we detect the occurrence of large-area gravity anomalies near the epicenter,oftentimes about half a year before an earthquake,and these anomalies were distributed along the fault zone.Second,from the observation scale of the plate,we find that when an earthquake occurred on the Tibetan Plateau,a large number of gravity anomalies also occurred at the boundary of the Tibetan Plateau and the Indian Plate.Moreover,the aforementioned experiments confirm that the proposed method can successfully capture the preseismic gravity anomalies of large earthquakes with a magnitude of less than 8,which suggests a new idea for the application of gravity satellite data to earthquake research.展开更多
青藏高原东北部位于季风交汇的敏感区域,其区域水储量变化对水资源管理具有重要意义。本研究基于GRACE(Gravity Recovery and Climate Experiment)重力卫星数据,分析了2003年1月至2022年12月期间青藏高原东北部的陆地水储量变化特征。...青藏高原东北部位于季风交汇的敏感区域,其区域水储量变化对水资源管理具有重要意义。本研究基于GRACE(Gravity Recovery and Climate Experiment)重力卫星数据,分析了2003年1月至2022年12月期间青藏高原东北部的陆地水储量变化特征。为校正重力卫星反演过程中可能存在的信号泄露问题,采用GLDAS水文模型进行尺度因子恢复。研究结果表明:(1)青藏高原东北部陆地水储量变化总体呈上升趋势,其长期变化趋势为(3.88±0.46)mm/yr,主要由地下水和地表水储量变化共同驱动,其中降水在水文变化中起关键作用;(2)从空间分布来看,青藏高原东北部陆地水储量变化由东北向西南逐渐增加,地表水储量变化东高西低,而地下水储量变化西高东低。(3)各区域陆地水储量变化速率存在显著差异,柴达木盆地年增长速率最大[(4.34±0.50)mm/yr],河西走廊最低[(1.53±0.45)mm/yr],青海湖水系和黄河流域增量相似;各区域的陆地水储量变化主要是由于其地下水和地表水分量变化受自然因素和人为活动的综合影响。展开更多
In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively understood.In this article,we discuss the effects of mesoscale G...In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively understood.In this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MISE-1D(one-dimensional Model of Ionospheric Sporadic E),with low numerical dissipation and high resolution.Driven by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MISE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower altitudes.The effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the GWs.The mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their thickness.In addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.展开更多
文摘干旱是全球范围内普遍存在的自然灾害,对环境、生态、经济和社会等多个方面产生深远影响。GRACE(Gravity Recovery and Climate Experiment)重力卫星通过测量地球重力场变化数据可动态监测陆地水储量变化。应用GRACE获得的水储量时空分布信息,可监测干旱,以研究干旱事件的发生、发展与演变过程。采用文献计量法分析总结了GRACE卫星数据在地下水储量变化、气象与水文干旱演变规律与响应、干旱预警等方面的应用现状及存在数据验证与数据插补重建方面的问题,并展望了变化环境下水储量变化、构建更适合干旱监测的干旱指数、提高GRACE数据精度、提升GRACE数据时空分辨率、干旱预警和决策支持以及区域水循环和生态系统响应等研究方向,可为后续的相关应用研究提供一定参考价值。
文摘相较于传统的两步法,动力学一步法能充分利用观测数据的原始信息,理论上可获得更合理的时变重力场产品,同时也因其涉及的参数维度更多样、函数模型更复杂,一直是当前研究的热点和难点.本文研究并实现了动力学一步法恢复时变重力场,给出了合理的数据处理策略,而后基于GRACE-FO(GRACE Follow-On)星载GPS数据和KBR(K/Ka Band Ranging)距离变率数据反演了2021—2022年60阶全球月时变重力场模型.对于一步法中诸多技术细节,本文重点分析了先验权和经验参数对轨道确定和模型反演的影响,研究表明:当采用30 s采样率的GPS数据时,需适当对GPS数据降权,以免引入过多噪声,码伪距、载波相位和KBR距离变率数据的先验权比应为1:104:1014;为了保证轨道和模型质量,在反演过程中有必要引入经验参数以吸收残余的摄动力误差,相较其他经验参数(分段周期经验加速度、几何经验参数),分段常经验加速度在保证定轨精度的同时可更有效地吸收模型中的噪声.此外,在采用相同动力学参数配置时,动力学一步法反演的时变重力场模型无论是与官方模型的一致性还是内符合精度均优于两步法.最后,综合评估了整个时间跨度的轨道和时变重力场模型质量,结果显示,动力学一步法确定的轨道可满足厘米级需求,双星的卫星激光测距残差标准差均为1.6 cm,重力场模型与官方机构CSR(Center for Space Research)、JPL(Jet Propulsion Laboratory)、GFZ(GeoForschungsZentrum Potsdam)最新发布的RL06.1模型一致性较好,在保留完整时变信号特征的前提下,噪声表现与CSR模型相当,优于JPL、GFZ模型.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFC1509202)the National Natural Science Foundation of China(Grant Nos.41772350,61371189,and 41701513).
文摘The occurrence of earthquakes is closely related to the crustal geotectonic movement and the migration of mass,which consequently cause changes in gravity.The Gravity Recovery And Climate Experiment(GRACE)satellite data can be used to detect gravity changes associated with large earthquakes.However,previous GRACE satellite-based seismic gravity-change studies have focused more on coseismic gravity changes than on preseismic gravity changes.Moreover,the noise of the north–south stripe in GRACE data is difficult to eliminate,thereby resulting in the loss of some gravity information related to tectonic activities.To explore the preseismic gravity anomalies in a more refined way,we first propose a method of characterizing gravity variation based on the maximum shear strain of gravity,inspired by the concept of crustal strain.The offset index method is then adopted to describe the gravity anomalies,and the spatial and temporal characteristics of gravity anomalies before earthquakes are analyzed at the scales of the fault zone and plate,respectively.In this work,experiments are carried out on the Tibetan Plateau and its surrounding areas,and the following findings are obtained:First,from the observation scale of the fault zone,we detect the occurrence of large-area gravity anomalies near the epicenter,oftentimes about half a year before an earthquake,and these anomalies were distributed along the fault zone.Second,from the observation scale of the plate,we find that when an earthquake occurred on the Tibetan Plateau,a large number of gravity anomalies also occurred at the boundary of the Tibetan Plateau and the Indian Plate.Moreover,the aforementioned experiments confirm that the proposed method can successfully capture the preseismic gravity anomalies of large earthquakes with a magnitude of less than 8,which suggests a new idea for the application of gravity satellite data to earthquake research.
文摘青藏高原东北部位于季风交汇的敏感区域,其区域水储量变化对水资源管理具有重要意义。本研究基于GRACE(Gravity Recovery and Climate Experiment)重力卫星数据,分析了2003年1月至2022年12月期间青藏高原东北部的陆地水储量变化特征。为校正重力卫星反演过程中可能存在的信号泄露问题,采用GLDAS水文模型进行尺度因子恢复。研究结果表明:(1)青藏高原东北部陆地水储量变化总体呈上升趋势,其长期变化趋势为(3.88±0.46)mm/yr,主要由地下水和地表水储量变化共同驱动,其中降水在水文变化中起关键作用;(2)从空间分布来看,青藏高原东北部陆地水储量变化由东北向西南逐渐增加,地表水储量变化东高西低,而地下水储量变化西高东低。(3)各区域陆地水储量变化速率存在显著差异,柴达木盆地年增长速率最大[(4.34±0.50)mm/yr],河西走廊最低[(1.53±0.45)mm/yr],青海湖水系和黄河流域增量相似;各区域的陆地水储量变化主要是由于其地下水和地表水分量变化受自然因素和人为活动的综合影响。
基金supported by the Project of Stable Support for Youth Teams in Basic Research Field,Chinese Academy of Sciences(CASGrant No.YSBR-018)+2 种基金the B-type Strategic Priority Program of CAS(Grant No.XDB41000000)the National Natural Science Foundation of China(Grant No.42204165)the National Key Research and Development Program(Grant No.2022YFF0504400).
文摘In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively understood.In this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MISE-1D(one-dimensional Model of Ionospheric Sporadic E),with low numerical dissipation and high resolution.Driven by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MISE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower altitudes.The effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the GWs.The mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their thickness.In addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.
