The progressive onset and evolution of Precambrian subduction and plate tectonics

Science China Earth Sciences - The regime of plate tectonics on early Earth is one of the fundamental problems in Earth sciences. Precambrian era takes the majority (ca. 88%) of Earth’s...     

Jacobian matrix for near-infrared remote sensing based on vector radiative transfer model

Due to the polarization effects of the Earth's surface reflection and atmospheric particles' scattering, high-precision retrieval of atmospheric parameters from near-infrared satellite data requires accurate vector atmospheric radiative transfer simulations. This paper presents a near-infrared vector radiative transfer model based on the doubling and adding method. This new model utilizes approximate calculations of the atmospheric transmittance, reflection, and solar scattering radiance for a finitely thin atmospheric layer. To verify its accuracy, the results for four typical scenarios(single molecular layer with Rayleigh scattering, single aerosol layer scattering, multi-layer Rayleigh scattering, and true atmospheric with multi-layer molecular absorption, Rayleigh and aerosol scattering) were compared with benchmarks from a well-known model. The comparison revealed an excellent agreement between the results and the reference data, with accuracy within a few thousandths. Besides, to fulfill the retrieval algorithm, a numerical differentiation-based Jacobian calculation method is developed for the atmospheric and surface parameters. This is coupled with the adding and doubling process for the radiative transfer calculation. The Jacobian matrix produced by the new algorithm is evaluated by comparison with that from the perturbation method. The relative Jacobian matrix deviations between the two methods are within a few thousandths for carbon dioxide and less than 1.0×10~(-3)% for aerosol optical depth. The two methods are consistent for surface albedo, with a deviation below 2.03×10~(-4)%. All validation results suggest that the accuracy of the proposed radiative transfer model is suitable for inversion applications. This model exhibits the potential for simulating near-infrared measurements of greenhouse gas monitoring instruments.     

A long-range forecasting model for the thermosphere based on the intelligent optimized particle filtering

The uncertainties associated with the variations in the thermosphere are responsible for the inaccurate prediction of the orbit decay of low Earth orbiting space objects due to the drag force.Accurate forecasting of the thermosphere is urgently required to avoid satellite collisions,which is a potential threat to the rapid growth of spacecraft applications.However,owing to the imperfections in the physics-based forecast model,the long-range forecast of the thermosphere is still primitive even if the accurate prediction of the external forcing is achieved.In this study,we constructed a novel methodology to forecast the thermosphere for tens of days by specifying the uncertain parameters in a physics-based model using an intelligent optimized particle filtering algorithm.A comparison of the results suggested that this method has the capability of providing a more reliable forecast with more than 30-days leading time for the thermospheric mass density than the existing ones under both weak and severe disturbed conditions,if solar and geomagnetic forcing is known.Moreover,the accurate estimation of the state of thermosphere based on this technique would further contribute to the understanding of the temporal and spatial evolution of the upper atmosphere.     

The Silurian-Devonian boundary in East Yunnan (South China) and the minimum constraint for the lungfish-tetrapod split

The Silurian-Devonian interval is an essential period in Earth history for witnessing the rise of sarcopterygian fishes and terrestrial vascular plants. In addition to its implication in global stratigraphic correlation, the precise location of the SilurianDevonian boundary(SDB) in East Yunnan closely relates to the minimal and maximal estimated dates for the lungfish-tetrapod split. Several geochemical indicators including the values and curves of δ13 Corg, δ13 Ccarband TOC are obtained from the continuous SDB sequence in Dahe, Yiliang County, East Yunnan. The results reveal the significant positive δ13 Corgshifts in the upper part of the Yulungssu Formation and the lower part of the Xishancun Formation, and the peak value(-20.0‰) in the sample YD-25 from the lowermost of the Xishancun Formation, replicating the δ13 Corgvariation trend from the uppermost Silurian to the lowermost Devonian worldwide. The δ13 Corgvariation across the SDB at the Dahe Section resembles the SDB curve from the borehole Klonk-1 drilled at the top of the Klonk GSSP in the Prague Basin, Czech Republic. As such, we place the SDB in the Dahe Area between the samples of YD-17 and YD-18 from the lowermost part of the Xishancun Formation. This SDB assignment is corroborated by new findings of Early Devonian thelodont Parathelodus from the lower part of the Xishancun Formation in Qujing Area. The resolution of the SDB in Dahe, coupled with available paleontological data and the biostratigraphic zonation in East Yunnan, has provided vital data for the geological ages of the fish-bearing strata in East Yunnan.The earliest rhipidistian Youngolepis from the Xishancun Formation(Lochkovian, Devonian) and earliest stem-sarcopterygian Psarolepis from the Kuanti Formation(Ludfordian, Silurian) in East Yunnan indicate that the split between lungfish and tetrapods occurred between 426.5 and 416.0 Ma.     

Growth of continental crust in intra-oceanic and continental-margin arc systems: Analogs for Archean systems

Science China Earth Sciences - Earth’s continental crust has grown and been recycled throughout geologic history along convergent plate margins. The main locus of continental crustal growth...     

3D finite-element modeling of Earth induced electromagnetic field and its potential applications for geomagnetic satellites

Science China Earth Sciences - The accumulated large amount of satellite magnetic data strengthen our capability of resolving the electrical conductivity of Earth’s mantle. To invert these...     

Shifting from homogeneous to heterogeneous surfaces in estimating terrestrial evapotranspiration: Review and perspectives

Terrestrial evapotranspiration(ET)is a crucial link between Earth’s water cycle and the surface energy budget.Accurate measurement and estimation remain a major challenge in geophysical,biological,and environmental studies.Pioneering work,represented by Dalton and Penman,and the development of theories and experiments on turbulent exchange in the atmospheric boundary layer(ABL),laid the foundation for mainstream methodologies in ET estimation.Since the 1990s,eddy covariance(EC)systems and satellite remote sensing have been widely applied from cold to tropical and from arid to humid regions.They cover water surfaces,wetlands,forests,croplands,grasslands,barelands,and urban areas,offering an exceptional number of reports on diverse ET processes.Surface nocturnal ET,hysteresis between ET and environmental forces,turbulence intermittency,island effects on heterogeneous surfaces,and phase transition between underlying surfaces are examples of reported new phenomena,posing theoretical and practical challenges to mainstream ET methodologies.Additionally,based on non-conventional theories,new methods have emerged,such as maximum entropy production and nonparametric approaches.Furthermore,high-frequency on-site observation and aerospace remote sensing technology in combination form multi-scale observations across plant stomata,leaves,plants,canopies,landscapes,and basins.This promotes an insightful understanding of diverse ET processes and synthesizes the common mechanisms of the processes between and across spatial and temporal scales.All the recent achievements in conception,model,and technology serve as the basis for breaking through the known difficulties in ET estimation.We expect that they will provide a rigorous,reliable scientific basis and experimental support to address theoretical arguments of global significance,such as the water-heat-carbon cycle,and solve practical needs of national importance,including agricultural irrigation and food security,precise management of water resources and eco-environmental protection,and regulation of the urban thermal environment and climate change adaptation.     

Distribution characteristics of lipids from salt sediments in Qaidam Basin and their astrobiological significance

On Earth,salt environments are the most relevant analogues to Martian salt deposits with regard to the search for preserved biomolecules.In this study,we analyzed the distribution of lipids in salt samples from Dalangtan and Qarhan in the Qaidam Basin,which is the most important area to carry out analog research of Mars in China.Furthermore,we compared the lipids distribution results with that from other typical Martian analog sites such as the Atacama Desert.Salt samples in the Qaidam Basin are enriched with fatty acid compounds,including normal fatty acids,unsaturated fatty acids,branched fatty acids,and acyclic isoprene acids.In addtion,glycerol dialkyl glycerol tetraethers(GDGTs)and archaeol compounds were also detected in these salt samples.Compared with the hypersaline samples,the clay samples not only have higher abuandance of fatty acids,GDGTs and archaeol compounds,but also a more diversed lipids composition.Only a few lipids were detected in the pure-saline samples,such as archaeol compounds.These clues suggest that content of salt minerals is the major factor affecting the distribution of lipids.This study provides an analogy for detecting and evaluating the traces of life that may exist on Mars.     

长江流域碎屑锆石U-Pb年龄物源示踪研究进展

长江的演化对于了解现代亚洲地貌格局的演变,以及探讨河流发育对构造隆升和季风演化的响应均具有十分重要的意义。前人已采用多种方法厘定长江的演化历史,但对长江贯通时限等问题仍存在较大的争议。目前物源示踪是进行河流演化研究的重要方法之一,其关键在于选取的示踪剂能够有效地代表源区信息并能准确定年。锆石的封闭温度高,可十分稳定地记录源区信息,且在河流中广泛存在,采集样品方便,锆石U-Pb年代学分析方法成熟,因而广泛应用于长江流域物源示踪研究。但长江流域面积广泛,流经的地质单元岩性复杂,流域内热历史信息丰富,这导致单纯利用该方法进行物源示踪研究面临诸多亟待解决的问题。文中在国内外研究资料的基础上,基于从"源"到"汇"系统的研究思路,通过对比分析,指出基于碎屑锆石U-Pb年代学进行长江流域物源示踪研究的局限性以及需要注意的问题。     

Two types of hyperthermal events in the Mesozoic-Cenozoic: Environmental impacts,biotic effects,and driving mechanisms

A deeper understanding of hyperthermal events in the Earth's history can provide an important scientific basis for understanding and coping with global warming in the Anthropocene. Two types of hyperthermal events are classified based on the characteristics of the carbon isotope excursion(CIE) of the five representative hyperthermal events in the Mesozoic and Cenozoic. The first type is overall characterized by negative CIEs(NCHE) and represented by the Permian-Triassic boundary event(PTB, ～252 Ma), the early Toarcian oceanic anoxic event(TOAE, ～183 Ma), and the Paleocene-Eocene Thermal Maximum event(PETM, ～56 Ma). The second type is overall characterized by positive CIEs(PCHE) and represented by the early Aptian oceanic anoxic event(OAE1 a, ～120 Ma) and the latest Cenomanian oceanic anoxic event(OAE2, ～94 Ma).Hyperthermal events of negative CIEs(NCHE), lead to dramatic changes in temperature, sedimentation, and biodiversity. These events caused frequent occurrence of terrestrial wildfires, extreme droughts, acid rain, destruction of ozone layer, metal poisoning(such as mercury), changes in terrestrial water system, and carbonate platform demise, ocean acidification, ocean anoxia in marine settings, and various degree extinction of terrestrial and marine life, especially in shallow marine. In contrast,hyperthermal events of positive CIEs(PCHE), result in rapid warming of seawater and widespread oceanic anoxia, large-scale burial of organic matter and associated black shale deposition, which exerted more significant impacts on deep-water marine life,but little impacts on shallow sea and terrestrial life. While PCHEs were triggered by volcanism associated with LIPs in deep-sea environment, the released heat and nutrient were buffered by seawater due to their eruption in the deep sea, thus exerted more significant impacts on deep-marine biota than on shallow marine and terrestrial biota. This work enriches the study of hyperthermal events in geological history, not only for the understanding of hyperthermal events themselves, large igneous provinces, marine and terrestrial environment changes, mass extinctions, but also for providing a new method to identify the types of hyperthermal events and the inference of their driving mechanism based on the characteristics of carbon isotopic excursions and geological records.     

重力技术在地球自由振荡检测研究中的应用

地球自由振荡是一种十分重要的地球动力学现象,用重力技术检测地球自由振荡,结合地震技术可为获得地球内部精细结构提供一种重要手段.本文概要综述了地球自由振荡理论研究的发展和重力技术检测现状,详细讨论了利用我国武汉超导重力仪检测到的地球自由振荡本征周期和谱峰分裂现象,结合我国实际情况提出了研究展望,旨在给出需解决的学科问题和相应的策略探讨.     

Relationship between polar motion and key hydrological elements at multiple scales

Science China Earth Sciences - Changes in the elements of the Earth system are closely related. Finding the key factors linked with hydrological changes is significant for in-depth analysis of...     

Co-varying temperatures at 200 hPa over the Earth’s three poles

The Earth’s three poles,the North Pole,South Pole,and Third Pole(i.e.,the Tibetan Plateau and its surroundings),hold the largest amount of fresh water on Earth as glaciers,sea ice,and snow.They are sensitive to climate change.However,the linkages between climate variations of the three poles,particularly between the South Pole and Third Pole,remain largely unknown.The temperatures at 200 hPa over the three poles are the highest in the summer and are less affected by surface conditions,which could reflect large-scale dynamic linkages.Temperatures at 200 hPa peak the three poles during their respective hemispheric summer and exhibit in-phase variations on interdecadal timescales(10–100 years).The 200 hPa temperatures over the North Pole and South Pole were significantly correlated with the Brewer-Dobson circulation(BDC),which transports stratospheric ozone poleward,heating the air at 200 hPa.Tropopause warming over the Third Pole was found to enhance the poleward BDC,particularly to the South Pole,linking the Third Pole’s climate to the other two poles.Additionally,the Interdecadal Pacific Oscillation(IPO)also exhibits links with the 200 hPa temperatures of the three poles.     

Acceleration of global mean ocean circulation under the climate warming

正In the context of continued greenhouse gas emissions, the Earth has experienced very rapid warming over the past several decades. As the main reservoir of the Earth’s climate system, the ocean transfers much of the extra heat, which leads to long-term atmospheric warming, from sea surface to the deep oceans (IPCC, 2019). Large-scale ocean circulation is one of the basic forms of sea water movement, which     

A new mechanism of atmospheric CO2 absorption promoted by iron-nitrogen coupling in low-latitude oceans during ice age

It has been confirmed by a large number of studies that iron can significantly improve the carbon fixation level in the high-latitude oceans (Martinez-Garcia et al., 2014). Although there are many studies on the mechanism of ironcarbon coupling in the modem ocean, the research on ironnitrogen-carbon coupling is rare (Tagliabue et al., 2014;Song, 2010). It is of great significance for the prediction of future ocean changes to identify the key processes of modem ocean and analyze the past ocean changes.     

Erratum to: Understanding and building upon pioneering work of Nobel Prize in Physics 2021 laureates Syukuro Manabe and Klaus Hasselmann: From greenhouse effect to Earth system science and beyond

Science China Earth Sciences -     

The Tibetan Plateau is a natural laboratory for studying organic evolution and environmental change

Today’s fauna and flora are a continuation from their geological past. In order to better understand how patterns of biodiversity form and organic evolution takes place, it is necessary to study these flora and fauna over time.     

Spatiotemporal changes of epidemics and their relationship with human living environments in China over the past 2200 years

正Epidemics are biological disasters resulting from the widespread occurrence of acute and severe infectious diseases that are normally caused by viruses, bacteria and parasites.They are amongst the most destructive of all natural disasters suffered by humans (Gong, 2019). The pathogens that cause epidemics have always existed in nature, understanding the spatiotemporal distribution of past epidemics is important for preventing and controlling future epidemics.     

Stratosphere amplifies the global climate effect of wildfires

The summer of 2019 witnessed a great number of wildfires around the globe.For example,wildfires scorched huge swaths of Alaska,British Columbia in Canada,and parts of Greenland.And forest fires in Siberia and the Far East of Russia were also very serious,affecting nearly 3 million hectares of land,and putting some parts of Russia into a state of emergency.In particular,forest fires in the Amazon region had attracted global attention.According to Science,as of August 24,BraziPs National Institute for Space Research had counted more than 41000 fires this year,86%more than last year,compared with 22000 in the same period last year.Scientists in Brazil and elsewhere believe that the recent increase of wildfires is closely related to the increasing ac・tivities of deforestation(Arruda et al.,2019;Escobar,2019).     

Status and prospect of 3D inversions in EM geophysics

1.Current status Three-dimensional(3D)inversion of geophysical EM data is generally underdetermined,non-linear,and of large-scale that is very difficult to solve by optimization.In the past two decades,with the advancement of computational equipment and numerical algorithms,3D geophysical EM inversion has made great progress.Numerous inversion codes and platforms based on the regularizations have been successfully developed and are being widely used in the industry and scientific research.The development of 3D EM inversions mainly involve the following aspects.