Earth's Sphere Research Articles

Earth’s spheres: Conceptual and definitional debates

Eduard Suess’s invention of the word ‘biosphere’ sparked a trend of coining sphere-words, which has since evolved into something of a craze. Some of these words, such as atmosphere and hydrosphere, are simply name tags for their respective Earth spheres. Others, such as geosphere, are also used mainly as names but they carry more than one meaning. However, many sphere-words, including pedosphere, biosphere, ecosphere, anthroposphere, sociosphere, and technosphere, are far more than just names, bearing as they do, weighty conceptual connotations that fuel considerable debate. At a time when Earth and life scientists are attempting to understand the workings of the planet as a whole by modelling the interaction of its component spheres, and when they are collaborating with sociologists, anthropologists, and members of other human sciences to tackle current environmental challenges, it seems an opportune moment to probe the origin and meaning of words for the Earth spheres they investigate. To be sure, Earth System modelling is helping understand changes resulting from the interaction of all the Earth’s spheres, including the anthroposphere, over various time and space scales, while multidisciplinary, interdisciplinary, and transdisciplinary research is helping to address such global problems as sustainable development, climate change, water supply, and biodiversity loss. An awareness of the origin, development, and disputed meanings of many sphere-words that these approaches employ should prove salutary for their multifarious practitioners.

Hungry herbivores and thirsty plants: Browsing wildlife shape savanna tree transpiration independently of water use strategies

Abstract Plant transpiration is a key component of the hydrological cycle that moves water from the soil through plants to the atmosphere and is largely determined by environmental conditions. The challenges of highly variable climatic conditions and water scarcity in the semi‐arid savannas of southern Africa drive trees to exhibit different water use strategies. An additional challenge for savanna trees arises from the browsing of large mammals, and its potential impact on transpiration has largely been overlooked. To assess water use strategies and the impact of browsing on transpiration in three common savanna woody species (Colophospermum mopane, Catophractes alexandri, Senegalia mellifera), we conducted an extensive field experiment in a wildlife reserve in Namibia. We established a browsing gradient ranging from 0% to 100% leaf removal to disentangle complex relationships, and we measured sap flow representing whole‐tree transpiration, stomatal conductance as a proxy for leaf level transpiration, and environmental factors including soil moisture, solar radiation, air temperature and air humidity. We discovered a unimodal relationship between browsing intensity and sap flow, consistent across all species, and peaking at low to moderate browsing levels equivalent to approximately 30% leaf removal. This universal pattern is remarkable since we found water use strategies to differ among species: Colophospermum mopane and C. alexandri exhibit a water‐saving behaviour to reduce water loss under unfavourable conditions while S. mellifera demonstrates water‐spending characteristics. The deviation from a negative linear effect of browsing does not meet the functional expectation when browsing is translated into a simple leaf area reduction. Instead, it can be attributed to stomatal adjustments that partially compensate for transpiratory surface loss. We propose that this conceptual mechanism can be generalised to other woody species and various ecosystems. In addition, common transpiration models relying solely on leaf area indices and abiotic factors can be improved by including a non‐linear relationship to reproduce the effect of browsing accurately. Our findings highlight the role of herbivores in shaping the connection between the Earth's spheres and improve our understanding of ecohydrological and vegetation dynamics in Southern African savannas. Read the free Plain Language Summary for this article on the Journal blog.

Geochemistry of Weathering Cover and the Main Influencing Factors in Karst Area of Guilin, Southwest China

The chemical weathering of carbonate rocks is the main form of interaction between earth spheres in the karst critical zone. The karst weathering cover, which is composed by residua from carbonate rocks weathering, contains important information about the climate environment and material cycle. We present the chemical composition of weathering covers in karst area of Guilin, Guangxi province, analyze their weathering process and strength, and compare them with the other weathering covers in other karst area in China, including Yunnan, Guizhou, Hunan, and Qinghai Tibet Plateau. The results showed: (1) the chemical composition of Guilin weathering covers were similar to that of carbonate weathering covers in other areas of China, and had the common characteristics of uniform distribution of chemical composition in the profile and obvious enrichment of Fe, Al and trace elements. During the formation of carbonate weathering cover and the residua, the rapid dissolution of Ca and Mg had an important impact on the migration and enrichment of other elements. (2) The chemical index of alteration (CIA) of carbonate weathering covers in Guilin and other karst areas of China was much larger than that in the upper crust (UCC) (60.13), which showed strong chemical weathering characteristics of the humid and hot climate. (3) The weathering process of carbonate rock was different from that of silicate and loess. In the early stage of carbonate rock weathering, soluble components (calcite and dolomite) had been rapidly dissolved and leached. All the carbonate weathering residua was measured to be in the stage of K2O weathering and Al2O3 increasing. Therefore, the weathering degree of carbonate weathering cover was mainly determined by the leaching of K2O and the increase of Al2O3. As a result, there was no correlation between CIA and Na/K (molar ratio), but was a significant negative correlation between CIA and K/Al (molar ratio) in the carbonate weathering cover. (4) The CIA values of weathering residua and carbonate weathering cover in southern China were negatively correlated with latitude, reflecting the influence of climate factors. From the influence of lithology, the chemical compositions of parent rock can affect the CIA of weathering cover, and the content of insoluble matter in carbonate rock was negatively correlated with CIA. From the influence of topography, the CIA value of weathering residua decreased from the high to the low position and from the shallow to the deep part of the profile.

Scenic perennial plants classification

Earth sphere flora most of them a lot yearly plants enters. A lot yearly scenic plants floral landscape harvest in doing important important has of plants land over part each year in winter dead will be, the root or onions preserved remains. In the spring while from him new stems grow up comes out A lot yearly of plants to live term sharp differs and one how many from from 10 to 100 years, sometimes even 1000 years can A lot yearly scenic plants to the group tulip, velvet or bellflower, marigold, chamomile, potato flower, safflower, safflower and others enters.

Impossible Voyages: Wangechi Mutu at Storm King

Impossible VoyagesWangechi Mutu at Storm King Irina Sheynfeld (bio) "My work is for my daughters and my sons and the next generation who will hopefully continue to create new ways of telling our histories and of stitching us all back together."1 —Wangechi Mutu Kenyan-born American multidisciplinary visual artist Wangechi Mutu (b. 1972) brings her fantastical menagerie of beings to the expansive landscape of Storm King Art Center, an open-air museum about ninety miles north of New York City. The artist divides her time in the studio between Nairobi and New York City and in her practice, she incorporates elements from both worlds. Her work has been described as deeply feminist and informed by both Afrofuturism—a cultural aesthetic that combines science fiction, history, and fantasy to explore the African American experience—and Symbiocene, a term coined in 2011 by Glen Albrecht, that describes a new era in human history that is characterized by harmonious interactions between humans and all other living beings. Eight large-scale sculptures populate the museum hill and about twenty additional works, including two films, span two floors of the main museum building. This is perhaps one of the artist's most comprehensive solo shows to date. Mutu's work is an intervention into Storm King's pastoral, hilly landscape and it encourages a conversation between museums past and present. It also makes us think anew about the importance of ritual and its creation, as well as the new meaning of one's journey through life. In her practice, Mutu doesn't just rethink existing mythologies but she often creates new ones. She conjures fantastical, futuristic female beings and creates worlds for them to travel through. Mutu deals with themes of reinventing the journey, rewriting mythology, and reconstructing ritual. The artist creates new creatures on a voyage through unknown territory. Both of her most recent sculptural groups, In Two Canoe (2022) and Crocodylus (2020), depict travelers whose destination and purpose are [End Page 101] Click for larger view View full resolution Figure 1. In Two Canoe, 2022 Bronze 180 × 68 × 72 in (457.2 × 172.7 × 182.9 cm) Edition 1/3 unknown, while Shavasana I and II (2019) present us with those whose journey has just ended. On top of Museum Hill, at the center of the park and right in front of the museum building, there is a fifteen-foot-long bronze fountain, In Two Canoe. It consists of two patinated olive-green humanoid female figures seated inside a water-filled boat. Both women's legs are spread wide and hang down over the sides of the canoe into the earth as slender mangrove roots. In an interview with the New York Times, Mutu explains that, "Mangroves are migratory. This plant has moved everywhere and has made journeys like those who were kidnapped from Africa and taken to the Americas. The water seals this unified story we've created for ourselves. We are all connected on this sphere of earth and the water is how we go and find each other." But where are two giantesses going in a boat that is filled to the brim with water? The unexpected placement of the water—inside rather than outside of the boat—makes one wonder how these woodland leaf-covered aliens are going to get anywhere. Does it mean that their mysterious journey is doomed from the get-go? Mutu's beings are simultaneously awe- and fear-inspiring. The couple in Canoe recalls a small stone plaque from the mid-fourteenth century [End Page 102] Click for larger view View full resolution Figure 2. In Two Canoe, 2022 Bronze 180 × 68 × 72 in (457.2 × 172.7 × 182.9 cm) Edition 1/3 BCE, Akhenaten, Nefertiti and Their Three Daughters Under the Strahlenaton. The stele, which is housed at the Neues Museum in Berlin, is unique in the three-thousand-year history of Egyptian Art, as it depicts Pharaoh and his wife not idealized in a canonical way but as equals seated in front of each other.2 One notices a striking resemblance between the figures [End Page 103] of Mutu's Canoe and those depicted on the Akhenaten plaque; they share...

A problem in ‘Basic Cartography’

ABSTRACT In cartographic literature, map projections are usually interpreted as mapping to auxiliary development surfaces, and then these surfaces are developed into a plane. The so-called secant projections, i.e. projections in which the auxiliary surface intersects the Earth's sphere or ellipsoid are especially emphasized. It is stated and taken as a fact without proof that the parallels in which the auxiliary surface intersects the sphere are mapped without distortions. An example of such an approach is the publication Basic Cartography, published several years ago by the International Cartographic Association. This paper proves that standard parallels and secant parallels generally do not match. It turns out that the widely accepted facts about secant and standard parallels, which can also be found even in the most recent literature, are wrong and need to be revised. The paper concludes that explaining cylindrical projections as mapping on a cylindrical surface is not a good approach, because it leads to misunderstanding important properties of projection.

LES SIGNIFICATIONS DU NOM ȘOAPTĂ DANS LA POÉSIE DE TRAIAN DORZ

This paper aims to discuss some meanings of the noun șoaptă/ ‘whisper’ (derived by backformation), as reflected in the confessional poetry of Traian Dorz - a contemporary Romanian author whose work is undoubtedly the fruit of the spiritual experiences that have decisively marked his existential route. In fact, the relationship of the human being with God (in the earthly sphere, but also from the perspective of eternity) remains a constant theme of this work dedicated to the astonishing feeling of His unmistakable love, in connection with which everything is situated, more than once, within the coordinates of the unspeakable: it is a special kind of “verbalization,” which offers the opportunity to live in a true spiritual discipline, substituting (and suppressing) any other form of confession through ordinary words. In addition to simply illustrating such expressive valences that contribute to the achievement of the textual construction, the meanings of the above-mentioned noun highlight the deep feelings of the authorial ego, always ascending on the path of mystical knowledge, and are placed on a positive semantic direction, as a special way of inner “speech”, in the absence of which communication would be inconceivable.

Determining the scale and map projection of Stjepan Glavač’s map from 1673

ABSTRACT The uniqueness and detail in the depiction of Croatian regions gives Glavač's map exceptional importance as part of the Croatian cultural heritage. Since Glavač left behind as written evidence of map creation only its title and an exhaustive dedication, other information about the map remains unknown. The appearance of the cartographic network indicates that it is a normal aspect of cylindrical projection. From the relationship between the coordinates from the map, we concluded that Glavač used the equidistant cylindrical projection with the equator as a standard parallel. After that we have calculated that the ratio of the radius of the Earth's sphere to the scale of the map is 2292.7. The numerical scale of the map can be determined from a graphical scale and from the calculated ratio of the radius to the map scale. Since there were several attempts to determine the Earth's dimensions at the time of Glavač's map, there are several possible radii of the Earth's sphere. At the end of the paper, calculating the interval of the numerical scale of the map enabled us to refute and/or accept the theses of other authors who cited different scales of Glavač's map in their works.

Analysis and Discussion on Ellipsoidal and virtual sphere models used for transverse arrangement INS

AbstractTransverse arrangement is one of the main methods used in the polar inertial navigation system (INS). In the traditional algorithm, the calculation of using the earth ellipsoid model is complex, while using the earth sphere model cannot satisfy a high-accuracy application. Therefore, an approach based on the virtual sphere model is proposed, which has been proved in simulation experiments to reduce the computational complexity and maintain the same accuracy as the ellipsoid algorithm, but its accuracy has not yet been proved in theory. Starting from the basic principles of the ellipsoid and virtual sphere model algorithm, this paper compares the key formulations of the two. Finally, it is proved that the two arrangements are actually the same.

Natural Resources and the Tipping Points of Political Power—A Research Agenda

A general assumption concerning the relationship between natural recourses and politics is that the degradation of natural resources will destabilize political regimes causing civil wars, mass migration, or the erosion of democratic systems. Despite individual attempts to explore the relationship between different political regimes and various resources in more detail, a systematic explanation of the complex relationship between natural resources and political regimes is still lacking. In this paper, we suggest a research agenda in order to better understand their interconnectedness. We start by exploring the respective potentials of Earth system science (ESS) and the logic of Earth spheres. We argue that the notion of distinct Earth spheres has its merits but also significant disadvantages. We then propose to concentrate on a resource perspective as the more expedient starting point for investigating the nature of the interconnection between the ecosphere and humans. We refine our argument by suggesting to also reflect on the socioeconomic properties of natural resources in order to estimate their implications for political regime stability. Finally, this paper proposes three different political regime types and how each organizes its relationship vis-a-vis natural resources, especially regarding sustainable resource use.

Climate-driven provenance variation and sedimentary system evolution at the Changjiang distal mud since the mid-Holocene

The Changjiang (i.e., Yangtze River) distal mud is a typical region for studying source-to-sink systems in the world. The coupling between climate change and the sedimentary system evolution of the Changjiang distal mud since the Holocene is widely debated. In this study, based on a 14C chronological framework, we investigated the sedimentary system evolution of the Changjiang distal mud since 8 ka. The provenance identification and climate conditions indicated that the climate oscillation largely determined the sediment source-to-sink processes. The sedimentary system was controlled by monsoon system oscillation from 8 to 3 ka. Specifically, during 8–5.4 ka, the prevailing Indian and east Asian summer monsoons increased the sediment flux to the Changjiang distal mud, and the proportion of the Changjiang sediments increased across the entire Changjiang distal mud. Notably, the southern regions were significantly influenced by western Taiwan rivers. Additionally, the prevailing east Asian winter monsoon enhanced the Zhejiang-Fujian coastal current, resulting in the deposition rates increased in south while declined in north. During 5.4–3.0 ka, the summer monsoon systems attenuated, causing decreased sediment discharges from the Changjiang and Taiwan, and the deposition rates declined across the entire Changjiang distal mud. In the southern regions, the intensified Taiwan warm current increased the proportion of Taiwan sediments. Since 3 ka, the monsoon system has become stable, and anthropogenic activities in south China have increased remarkably. The anthropogenic activities resulted in increased Changjiang sediments and rose deposition rates across the entire Changjiang distal mud. During 1.2–0 ka, the frequent floods in the Changjiang basins and typhoons in Taiwan, caused by increased El Niño–Southern Oscillation (ENSO) frequency, resulted in provenance fluctuation at the Changjiang distal mud. In addition, the attenuated east Asian winter monsoon caused a northward depocenter shift, which was reflected in spatially different deposition rates, i.e., retained high values in the north but declined in the south. Our findings emphasized the dominant roles of different climatic factors in different stages, and enhance our understanding of the east Asia land-ocean interactions and the relationships among the Earth's spheres since the mid-Holocene.

Quantitative Study of the T-AVIM-Based Simulated IMU Error in Polar Regions.

For solving the problem of polar performance of the inertial navigation system (INS) at mid-low latitudes, the simulation test system constructed by the “attitude and velocity invariant method of trajectory transfer rule based on the transverse coordinate system (T-AVIM)” of the Earth sphere model is used. The test system structure, especially the IMU conversion formula from mid-low latitudes to polar region simulation test, is introduced, and it is proved that the IMU conversion error can be equivalently superimposed on the bias error of the polar simulated IMU. According to the marine estimation formula for the effect of the reference error on the IMU conversion error, the specific influence of the constant error component and the random error component of the reference system on the simulated IMU is analyzed. The calculation method of the simulated IMU error is given with examples and intuitively explained, and the correctness of the theory is verified through simulation experiments.

Multi-instrument observations of microseisms generated by typhoon Kalmaegi (2014) over the Northwestern Pacific

The typhoon-generated microseisms, originating from the complex energy coupling and transferring among the Atmosphere-Ocean-Solid Earth spheres, can be detected remotely by seismometers as the strongest ambient seismic noise. The lack of in situ observations during the passage of typhoons has hampered numerical modeling of wind fields and ocean waves, and limited our understanding of the generation mechanisms of microseisms associated with typhoons. Here we present a comprehensive investigation of microseisms generated by typhoon Kalmaegi (September 2014) based on multiple-instrument constraints from observations including terrestrial and ocean-bottom seismic stations as well as ocean buoys. To understand the generation mechanisms, we apply an improved frequency-domain beamforming method to seismic array data leading to successful location of double-frequency (DF) microseism source regions. For comparison, we calculate the typhoon-induced ocean waves and theoretical source regions of the DF microseisms using the coupled ocean–atmosphere–wave–sediment transport modeling system with validation by ocean buoy observations. Both observations and numerical modeling results reveal two different generation mechanisms for typhoon-induced DF microseisms during the lifespan of Kalmaegi. When over the Philippine Sea, the DF microseisms were generated mainly by opposing ocean waves from two distinct storms. After Kalmaegi entered the South China Sea, the DF microseisms were generated mainly by the fast-moving typhoon with source regions just trailing behind, with the minimum frequencies determined by the typhoon translation speed. DF microseisms generated in coastal source regions were not detected by ocean bottom seismometers, suggesting that DF microseisms might not effectively propagate across the ocean-basin seafloor covered by thick sediments, owing to severe seismic attenuation and spreading losses. This information is crucial for the use of DF microseisms for future tracking and monitoring of typhoons.

ORGANIZATION OF TECHNOLOGY OF DRIP IRRIGATION OF COTTON CROP AND THEIR TYPES

Rational use of Water Resources in the conditions of Global climate change, further improvement of the system of use of Water Resources, increasing the efficiency of irrigation and melioration works, water saving, wide introduction of innovative technologies of saving irrigation is topical. two-thirds of the Earth's sphere is covered with water, 98% of which is depleted salt water. Of the available water resources there are 2,0% fresh water reserves, 79% of which are eternal glaciers, 20% groundwater and 1,0% Lake and river waters. In this article, ideas and opinions are made about the organization of the technology of drip irrigation of cotton crops and their types.

Cyano-Bridged Dy(III) and Ho(III) Complexes with Square-Wave Structure of the Chains

Four new cyano-bridged DyIII-CrIII, DyIII-FeIII, HoIII-CrIII and HoIII-FeIII bimetallic coordination polymers were synthesized by the reaction of [Ln(H2dapsc)(H2O)4](NO3)3 (Ln = Dy, Ho); H2dapsc = 2,6-diacetylpyridinebis(semicarbazone)) with K3[M(CN)6] (M = Cr, Fe) in H2O, resulting in the substitution of two water molecules in the coordination sphere of rare earth by paramagnetic tricharged hexacyanides of Fe and Cr. The complexes are isostructural and consist of alternating [Ln(H2dapsc)(H2O)2]3+ and [M(CN)6]3− units linked by bridges of two cis-cyano ligands of the anion to form square-wave chains. The ac magnetic measurements revealed that the DyCr and DyFe complexes are field-induced single molecule magnets, while their Ho analogs do not exhibit slow magnetic relaxation.

INTERNACIONALNI MOTIV ZMAJEUBISTVA U JAPANSKOM MITU I LEGENDI

Systematic comparative studies of international significance indicate that there are con- siderable similarities between ideas, beliefs, and customs of various nations, even in the tradi- tions of geographically distant countries with completely different cultural, religious, historical, and social background. One of these links is the dragon-slaying motif, which appears in myth and folklore. This paper deals with a comparative analysis of different narrative types, in which the international motif of the duel between a hero and a supernatural being is stylized. Despite the differences, these plots generally have common elements, such as: a monstrous devouring serpent/dragon that is taking control over the water; a hero arriving from afar; slay- ing the monster and rescuing a virgin offered to the monster as a human sacrifice; marrying the rescued girl. In Japanese culture there are such heroe, too. In legends, even a woman can be a dragon-slayer. The mythical dragon-slayer is the God of storm and natural forces, Take Haja Susanoo. He demonstrates all the characteristics of a trickster in the Heavenly sphere through destroying and even causing death. However, with his descent into the earthly sphere, his good qualities are emphasized. One of his achievements includes the very slaying of the monster − Yamata no Orochi, and setting his potential victim free. In the Japanese myth, we discover links with related tales from distant cultures, even from these regions. Thus, for example, such heroes of Serbian folk tales fight dragons. We can find the most famous Chris- tian dragon slayer in Christian hagiographic legends. Saint George shows the characteristics of mythical and legendary heroes, saves the emperor’s daughter from a beast , as well as the whole kingdom.

Народные образы предвестников Великой Отечественной войны: опыт систематизации и дешифровки

The article presents an experience of systematization and decryption of images of the harbingers of the Great Patriotic War from the oral stories of the Russian-speaking population of Russia. Considering the signs of war as elements of collective folk memory of crisis situations, the author solves the problem of identifying the main differentiating features for the development of future typology and of deciphering these images and related folk ritual practices and the constant alternation of periods of prosperity and disaster. Adhering to the methodology based on the understanding that typological schemes of cultural elements in folklore and ethnography should be based on folk ideas about their most important properties (i.e., on folk typology), the author suggests using two main features as differentiating signs of images-signs of war: the symbolization of the violation of the norm (in the direction of diminution or overabundance) and the place of the violation (the celestial sphere, the earth, channels of communication between them). Thus, the status of a sign could automatically acquire any image first recorded in the sky due to the sacralization of the heavens themselves in the folk tradition. Most of these images can be interpreted as warning signs of the coming war (comets, new stars, pillars of light); many of them are associated with the theme of confrontation and struggle (fighting riders, roosters, troops), they, in fact, reproduce the picture of the future. As for the earth sphere, most of the signs associated with it symbolize the violation of a certain norm, correlated, according to the author, with the popular concept of the fate (including the common fate), which is violated in the direction of loss or, conversely, abundance, and therefore (to resolve the crisis) must be updated and re-shared in the course of special rites. Finally, part of the images-signs of war in folk stories is associated with the so-called communication channels between the earth and celestial spheres (wells, springs, streams). Violations occurring in this system (channels are either “clogged”, or, on the contrary, functioning with excess) lead to violations of the norm - the fate in the sphere of the earth (in the direction of material abundance), and in the sacred (in the direction of its impoverishment). Images of naked women and wolves appearing to travelers on the road can also be considered as symbols of such violations. Identifying the semantics of these images, the author also shows the implementation of the ideas embodied in them in folk ritual practices aimed at “overcoming” the war and its consequences associated with the concept of the fate, its collective renewal, new redistribution and collective responsibility. It is also shown that the oral stories especially actualize Christian motives (deviation from the faith, service to the devil's forces) related to the large-scale destruction that took place in the religious life of the country in the pre-war period and the people's understanding of its consequences.

Colony Collapse Disorder, Neonicotinoids, CO<sub>2</sub>, Climate Change, and the Four Spheres

This analysis focuses on what effects the decline of both domestic and wild bee populations has on the environment. It will analyze the 21st century-coined phenomenon known as “Colony Collapse Disorder,” and will investigate research methods that have improved numbers within bee populations over the last two decades. Within this study, the impacts and interactions between the Colony Collapse Disorder phenomenon and various environmental factors will be discussed, as well as the interactions between the four main spheres of the Earth (i.e., the biosphere, lithosphere, atmosphere, and hydrosphere). In so doing, this study will evidence how and why bee populations are declining, why that decline affects each Earth sphere, as well as how this condition could create both loophole and contagion effects. Finally, this analysis will also briefly touch upon NASA’s increasing involvement with replenishing the world’s bee populations, the agency’s monitoring of CO2 levels, various ecosystems, and other such relevant and ongoing research.

A four-point direction search heuristic algorithm applied to facility location on plane, sphere, and ellipsoid surfaces

A facility location problem (FLP) refers to the best location for establishing a facility to optimally connect and meet the requirements of the demand points. In a supply chain on the earth’s surface, the cost function essentially includes a distance metric to compute the objective function. If the data points are located in a small area, Euclidean Distance (ED) can be considered. When the data points are fairly separated on the earth’s surface, ED cannot give a correct estimate and we have to opt for either a spherical model or an ellipsoidal model. This paper proposes a simple four-point direction search algorithm and a model which can be used for locating a facility on a plane, sphere, and ellipsoid model of earth. The main advantage of the proposed algorithm is that it can be used with any distance metric without changing the algorithm.

The 30 m annual land cover dataset and its dynamics in China from 1990 to 2019

Abstract. Land cover (LC) determines the energy exchange, water and carbon cycle between Earth's spheres. Accurate LC information is a fundamental parameter for the environment and climate studies. Considering that the LC in China has been altered dramatically with the economic development in the past few decades, sequential and fine-scale LC monitoring is in urgent need. However, currently, fine-resolution annual LC dataset produced by the observational images is generally unavailable for China due to the lack of sufficient training samples and computational capabilities. To deal with this issue, we produced the first Landsat-derived annual China land cover dataset (CLCD) on the Google Earth Engine (GEE) platform, which contains 30 m annual LC and its dynamics in China from 1990 to 2019. We first collected the training samples by combining stable samples extracted from China's land-use/cover datasets (CLUDs) and visually interpreted samples from satellite time-series data, Google Earth and Google Maps. Using 335 709 Landsat images on the GEE, several temporal metrics were constructed and fed to the random forest classifier to obtain classification results. We then proposed a post-processing method incorporating spatial–temporal filtering and logical reasoning to further improve the spatial–temporal consistency of CLCD. Finally, the overall accuracy of CLCD reached 79.31 % based on 5463 visually interpreted samples. A further assessment based on 5131 third-party test samples showed that the overall accuracy of CLCD outperforms that of MCD12Q1, ESACCI_LC, FROM_GLC and GlobeLand30. Besides, we intercompared the CLCD with several Landsat-derived thematic products, which exhibited good consistencies with the Global Forest Change, the Global Surface Water, and three impervious surface products. Based on the CLCD, the trends and patterns of China's LC changes during 1985 and 2019 were revealed, such as expansion of impervious surface (+148.71 %) and water (+18.39 %), decrease in cropland (−4.85 %) and grassland (−3.29 %), and increase in forest (+4.34 %). In general, CLCD reflected the rapid urbanization and a series of ecological projects (e.g. Gain for Green) in China and revealed the anthropogenic implications on LC under the condition of climate change, signifying its potential application in the global change research. The CLCD dataset introduced in this article is freely available at https://doi.org/10.5281/zenodo.4417810 (Yang and Huang, 2021).