Polar View Research Articles

Pollen morphology of Liliaceae and its systematic significance

The pollen morphology of 63 species, one subspecies and six varieties of 11 genera in the family Liliaceae was studied in detail using light microscopy (LM) and scanning electron microscopy (SEM). Among them, 22 species and one variety are reported for the first time. Ten pollen characteristics (shape in polar view, ends in polar view, width of colpus, depth of colpus, length of colpus, colpus costa, colpus membranes, type of surface ornamentation, muri, lumina) were selected for cluster analysis of the genera Gagea and Lloydia and for cluster analysis and principal component analysis of the genera Lilium and Nomocharis. The results show that the polar view, colpus morphology and surface ornamentation of pollen grains have important systematic significance. The surface ornamentation of pollen grains in this study can be divided into five types, namely gemmate, reticulate, rugulate, rugulate-perforate and verrucate. In combination with the results of previous research, our results suggest that (i) Clintonia and Streptopus should be included in the family Liliaceae; (ii) Fritillaria and Lilium should be considered independent genera; (iii) Lloydia should belong to Gagea; and (iv) Nomocharis should be merged into Lilium. But our results do not support dividing Lilium into seven sections.

Application of spore morphology to solve identification problems in certain species of family Dryopteridaceae from Malakand Division, Pakistan.

Here we investigate the morphology of the spores of 12 native taxa of Dryopteridaceae that grow in Malakand division, Pakistan; most of these species not fully described before. This study intends to survey the taxonomic significance of spore morphological features and their variation useful for species identification in 7 species of Polystichum and 5 taxa of Dryopteris. The spores examinations were accomplished utilizing a light microscope (LM), and scanning electron microscope (SEM). The spores are monolete, medium-sized, with variable shapes in both equatorial and polar views. The mean estimation of equatorial diameter ranging from 28.3 to 58.3 μm and the polar diameter varied from 27.6 to 45.8 μm. The exospore thickness ranges between 1.6 to 3.8 μm, and the thickness of perispore is 0.8-6.7 μm. The perispore is perforated, ornamentation elements occur in different ways in the studied taxa of Polystichum. In investigated Dryopteris taxa, rugate perispore type is found. Results of multivariate statistical analysis (UPGMA, and PCA) established on quantitative and qualitative morphological traits of spores demonstrate that the species form distinct groups, not reflecting any phylogenetic relationships. A key to the spores types is provided for species identification, which dependent on the diagnostic characters of spores. The results of this study indicate that variation of spore morphological traits; in particular, the ornamentation and perispore characteristics, which is surface texture, have diagnostic value at the species level. Our data will help in the identification of spores of the family Dryopteridaceae in palynological and taxonomic studies.

Practexological dimension of ecumenism and its main dialogue form

The article analyzes the elements of theoretical and methodological knowledge on the successful functioning of the ecumenical paradigm and attempts to actualize them in the context of interfaith dialogue, which would be marked by concretized productivity. A short historical digression was also made in order to consider the influence of educational philosophical and ideological tendencies on the formation of the modern ecumenical paradigm.Examples of key elements that contribute to the effectiveness of the main dialogical forms of ecumenism are given. The explication of the concept of such a component of the ecumenical concept as "spiritual ecumenism" provides an opportunity to outline its significance as an integral element in the integrity of Catholic ecumenism and proves the practical benefits of this component for the ecumenical movement. It was found that the Second Vatican Council made adjustments to the Catholic understanding of ecclesiology, and the focus of the Catholic Church's teaching government on "Eucharistic ecclesiology." Also in the article, based on official documents of the Catholic Church, the attitude of modern Catholicism to the issue of restoring Eucharistic communion with the participants in the ecumenical dialogue is revealed. The main purpose of the article is to analyze the historical and cultural impact on the formation of the praxeological element of the ecumenical paradigm, the correlation of controversial views on the functionality and effectiveness of key forms of ecumenical dialogue. In the course of the research, such research tasks were achieved as the analysis of the historical formation of the main aspects of the ecumenical movement; a comparative analysis of the polar views of researchers and theologians on the ecumenical concept in general; a comparative analysis of the main vectors of ecumenism development under the influence of socio-cultural transformations; the common religious elements of Christian denominations, which are key in the process of constructing the main dialogical forms, were highlighted.

Pollen morphology of different species of Iris barbata and its systematic significance with scanning electron microscopy methods.

Forty-eight cultivars of Iris barbata were used as research materials, and observations of their pollen morphologies were made using scanning electron microscopy (SEM). The pollen of I. barbata consisted of a single grain, which was subspheroidal or subprolate and boat-shaped in equatorial view and oval or nearly round in polar view. The pollen was symmetrical or radially symmetrical on both sides, and there were five types of germination furrows: monocolpate, dicolpate, monocolpate-colpoidal, 2-syncolpate, and parasyncolpate. The exine ornamentation was mostly crass-reticulate and occasionally verrucate or pilate. Variation in the equatorial axis length of I. barbata pollen was the lowest, and variation in pollen morphology was stable. Q-type cluster analysis was conducted using seven indexes: polar axis length (P), equatorial axis length (E), P/E, mesh diameter (D), net ridge width (W), D/W, and germination furrow width (WG). The 48 cultivars were divided into three groups. Three dwarf cultivars were clustered in one group, and the degree of evolution of this group was higher than that of the other two groups. This paper systematically describes the characteristics of I. barbata for the first time, and thus provides important palynological insights into the classification and cross-breeding of I. barbata.

Populist polarization in postcolonial Philippines: Sociolinguistic rifts in online drug war discourse

AbstractSocial psychological scholarship on populism explains polarization processes in terms of individual differences and group‐level divisions. However, predominant approaches often elide wider historical contexts, implicitly assuming the structural features of Western settings. Invoking insights from postcolonial psychology, we posit that populist polarization dynamics in the Global South are structurally shaped by colonial histories. Turning to the Philippines under populist President Rodrigo Duterte, we examine polarized online constructions of his controversial war on drugs. Employing a discourse‐historical approach, we uncover a structurally bifurcated view of populist polarization. We specifically unpack sociolinguistic rifts acrossvernacular discourses of community securityuttered in Filipino versuscosmopolitan discourses of democratic integrityuttered in English. Our findings expand prevailing scholarship by illustrating postcolonial discursive possibilities of populism from above and resistance from below. We conclude with insights for studying populist polarization at the nexus of local and global inequalities.

<p><strong>Morphology of pollen in Apiales (Asterids, Eudicots)</strong></p>

In this monograph, for the first time, the pollen morphology was analysed in the context of modern taxonomic treatment of the order and statistically evaluated in search of traits that could be utilised in further taxonomic and evolutionary studies. Our research included pollen sampled from 417 herbarium specimens representing 158 species belonging to 125 genera distributed among all major lineages of Apiales. The pollen was mechanically isolated, acetolysed, suspended in pure glycerine and mounted on paraffin-sealed slides for light microscopy investigation. Although most of the analysed traits were highly homoplastic and showed significant overlap even between distantly related lineages, we were able to construct a taxonomic key based on characters that bear the strongest phylogenetic signal: P/E ratio, mesocolpium shape observed in polar view and ectocolpus length relative to polar diameter. All the investigated traits are easy to observe with light microscopy and defined by clear and well-documented typology. Early diverging lineages of Apiales constitute a distinct group due to subprolate pollen grains (P/E ratio < 1.25). Among four subfamilies of Apiaceae, Mackinlayoideae can be easily identified based on a combination of traits shared with Klotzschia and Platysace—enigmatic umbllifers with highly uncertain phylogenetic position. Pollen of Azorelloideae is much more diverse but retains many plesiomorphic traits found in early-diverging Apioideae. In contrast, Saniculoideae and most representatives of Apioideae are characterised by evolutionary advanced morphology (perprolate pollen grains with relatively short ectocolpus and bone-shaped outline in colpus view). However, it remains unclear whether similarities between Saniculoideae and higher apioids are an example of convergent evolution or reflect common ancestry. Pollen of Hermas shows a unique combination of traits some of which are typical for Azorelloideae while others resemble Saniculoideae.

Study of Morphological Characters of Pollen Grains Sweet Chestnut (Castanea sativa Mill.) by Scanning Electron Microscopy

The studying of Castanea sativa Mill. pollen allows us to determine the details of morphological characteristics and described the most important parameters and pollen sculpture that can be used to identify representatives of species. The general characteristics and significant morphological traits of pollen grains of 16 genotypes Castanea sativa Mill. collected from M.M. Gryshko National Botanical Garden of Ukraine(Kyiv) were observed via a scanning electron microscope (SEM). The measurement of morphometric parameters was carried out on 50 pollen grains from each genotype using the AxioVision Rel. 4.8.2.0 program. The length of the polar axis (P) and the equatorial diameter (E) of grain, P/E ratio were measured and their variation was compared among studied genotypes. SEM investigations showed that the pollen grains of Castanea sativa are small-sized, the equatorial view is elliptic, the polar view is angular, with convex mesocolpia, more or less circular. This study showed the small differences between the genotypes in all measured factors. The average polar axis and equatorial diameter of pollen grains values varied in the interval 19.10 ±0.21–20.53 ±0.21 and 8.86 ±0.05–9.85 ±0.08, respectively. We determined the variation coefficient in the range of 3.37–8.93 %. It was noted that diversity of surface sculpturing of pollen grains in combination with shape and sizes enables to use of a complex of thin morphological signs for Castanea sativa pollen identifications.

The political crisis of power in modern Venezuela: Reasons, dynamics, prospects of resolution

The article examines the features and contradictions of resolving the political crisis in Venezuela. The authors analyze the activities of the direct parties to the conflict (the ruling regime led by current President Nicolas Maduro and the political opposition supported by the country’s Parliament) to resolve it and get the country out of the impasse. The work emphasizes the importance of socio-economic reasons that led to the emergence of the political crisis and the emergence of political forces, on the one hand, defending the ideas of socialist development, and, on the other, the values of the liberal — democratic structure of the state. The authors focus on the mechanisms and ways of resolving the political crisis implemented by Latin American countries, non-regional states and international organizations. However, their activities, as the study shows, are not effective enough since the national interests of states have a superior influence over the needs of stabilizing the political situation in the country and resolving the crisis. The authors examine the contradictions that prevent the beginning of a constructive dialogue between the parties of the conflict, supported by various segments of the population. The effectiveness of various international platforms and negotiation formats aimed at finding and developing solutions to the current crisis, compromises, and areas of joint activity is analyzed. As a result of the research, the authors come to the conclusion that at present it is necessary to cooperate more closely with both the ruling political elite and the opposition, despite the polar views of their representatives, as well as to expand the number of states in order to form a more objective negotiation process and achieve mutually acceptable solutions.

Automatic Multiple LiDAR Calibration Based on the Plane Features of Structured Environments

The multiple light detection and ranging (LiDAR) system has been attached to numerous autonomous vehicles to reduce blind spot risks and increase measurement resolution. It is also important to accurately aligning multi-LiDAR data because misaligned sensor data can affect the localization and perception algorithms of LiDAR sensors. However, precise extrinsic parameter estimation is a challenging research area because the feature points in LiDAR data cannot be precisely aligned owing to the LiDAR resolution. In this paper, we proposed a targetless multi-LiDAR calibration method without any initial information. In the proposed approach, a random sample consensus (RANSAC)-based plane fitting technique was utilized for plane extraction, and cross-feature points were extracted from the polar view transform of segmented planes. To resolve the discontinuity problem of optimization, a nonlinear optimization method was utilized, and the experiments were performed within a structured environment. Overall, the experimental results showed that the proposed method yields comparable results with state-of-the-art methods.

Use of Pollen Morphology Traits for Identifying Species of Centaurea L. Asteraceae in Kurdistan-Iraq

The polleniferous material of Centaurea taxa grow in Kurdistan-Iraq was collected. Samples were tested using scanning electron microscopy (SEM) and light microscopy (LM). In the polar view, pollen grain outlines are mostly triangular or triangular-circular. In equatorial view, the elliptic shape is common, while circulars or semicircular shapes are rare. The exine sculpture is scabrate, and the tectum is perforate. Number of sculpture microspinules/ µm², and their heights together with the number of wall perforations provide significant characters for taxa delimitation. Pollen grains of all species are of medium size, very few of some species pollen are larger or smaller in size. Species producing subprolate pollen shape is common, while oblate spheroidal and Prolate spheroidal shapes are less common. The principal component analysis and the discriminant analysis can recognize 65.478% and 87.54% of the total variability respectively; moreover, the discriminant function can correctly classify 125 or 78.125% out of 160 observations for pollen traits.

Паліноморфологічні особливості видів роду Hypericum L. (Hypericaceae Juss.) флори України

The palinomorphological features of six species of the genus Hypericum (H. аlpigenum, H. elegans, H. hirsutum, H. maculatum, H. montanum, H. perforatum) of the flora of Ukraine have been investigated. All species studied are valuable medicinal plants. However, only two species of raw material are officially permitted: H. perforatum and H. maculatum. Raw materials of other species can also be harvested from natural habitats, as they are wide spread in some regions of Ukraine and morphologically similar to pharmacopoeial species, but their admixture to the raw materials reduces its quality. The aim of research was to make a comparative morphological analysis of pollen grains six species of genus Hypericum of Ukrainian flora for determine the common and distinctive features that will identify the species of raw materials. We used a scanning electron microscope to investigate the pollen grains ultrascultures (CEM, JSM 6060 LA). The studies were performed according to the standard method. As a result of palynomorphological studies of six species of the genus Hypericum of the flora of Ukraine established, that the pollen grains of the species studied are small-sized, 3-colporate, ellipsoidal or spheroidal, outline in polar view ‒ trilobate, rounded-triangular, in equatorial elliptical. In all studied species the colpi are long, mostly with distinct margins, pointed ends and a granular membrane. The pores are undistinct. Sculpture exine in the investigated species of the genus Hypericum of the flora of Ukraine are microreticulate (H. perforatum, H. alpigenum) and reticulate (all other species studied). Morphometric features of pollen grains of the studied species: the length of the polar axis, equatorial diameter, colpus width, mesocolpium width, the diameter of the apocolpium, the ratio of the length of the polar axis to the equatorial diameter, the ratio of the mesocolpium widths and aperture widths can be used as additional diagnostic features in identification species of the genus Hypericum of Ukrainian flora.

Application of multimicroscopic techniques (LM and SEM) in comparative palynological study of Asteroideae members, inhabited in Pakistan.

In the present study light and scanning electron microscopic approaches were used to study the palynological variations among 30 Asteroideae members. Variety of qualitative and quantitative palynological characters like pollen shape and type, pollen sculpturing, pollen size, P/E ratio, exine and intine thickness, interspecific difference, colpi size, pore size, spines length, spine width, and pollen fertility were observed. Results reported remarkable variations among pollen characters of studied taxa. The shape of pollen grains in polar and equatorial views varied from specie to specie such as spheroidal, prolate, oblate, subspheroidal, oblate spheroidal, prolate spheroidal, suboblate, and sub prolate. Bidens pilosa L. showed maximum pollen size in both polar and equatorial views, whereas minimum pollen size in polar view was found in Tetraneuris scaposa (DC.) Greene. (i.e., 30.5 μm) and in equatorial view was found in Cosmos sulphureus Cav. (25.5 μm).The highest P/E ratio (1.39 μm) was measured in Glebionis coronaria L. The values of exine and intine thickness also varied. Tricolporate, tetracolporate, trizonocolporate, pentoporate, and polypentoporate pollen types were examined. Spinateand echinate pollen sculpturingobserved under SEM. Variations in spine length and width also recorded. The maximum pollen fertility (98%) was measured in Chrysanthemum morifolium Ramat. and the lowest (56%) was recorded in Thymophylla tenuiloba (DC.) Small. It was concluded that the variations in qualitative and quantitative characters were seemed to be valuable for the taxonomic investigations of Asteroideae taxa.

Social and Political Consequences of the Pandemic for the Russian Orthodox Church

In the article analyzed the social and political consequences of pandemic of coronavirus for the Russian Orthodox Church in the context of the reaction of different European churches on the quarantine rules and critics towards the church inside Russia. The author used the structural-functional and institutional approaches for the evaluation of the activity of the Russian Orthodox Church, was analyzed the sources of mass-media and the public claims of the clergy. In the article was made a conclusion that Orthodox Church expressed itself during the struggle with coronavirus as national civic institute where could be represented various even polar views. Also the parish activity leads to the formation of the democratic society affiliated with the Church and the role of that phenomenon have to be explored in a future. The coronacrisis makes open the inner potential of the civic activity and different forms of the social service in Russian Church. In the same time pandemic provoked the development of the volunteer activity in the around-church environment and also in the non-church circles among the young people and the generation of 40th age where the idea of the social responsibility for themselves and people around and the significance of the civil rights was one of the popular ideas till 2019. The conditions of the self-isolation also forced the clergy to struggle for their parishioners and once again renovate the role of the church in the society and in the cyber space.

Scanning Electron Microscopy-based palynological characterization of selected Euphorbiaceae taxa colonized in Pakistan.

The present study was carried out on scanning electron microscopic-based palynological characterization of selected 20 Euphorbiaceae taxa. In this study, important pollen qualitative and quantitative features of selected Euphorbiaceae species such as polar diameter, equatorial diameter, P/E ratio, sculpturing of pollen, exine thickness, intine thickness, presence or absence of colpi and length of colpi, and pollen fertility were examined. Remarkable variations in these pollen characters had been observed among these species. In both polar and equatorial views, Riccinus communis L. exhibited the highest pollen size (polar = 264.1 μm, Equatorial = 270 μm), while Acalypha wilkesiana Mull Arg. showed lowest pollen size (Polar = 17 μm, Equatorial = 18.5 μm). Most of the pollen varied from oblate to spheroidal in shape. With regard to the P/E ratio, Sapium sebiferum L. Roxb showed the highest ratio while Bischofia javanica Blume showed minimum, that is, 1.18 and 0.85, respectively. Intine and exine thickness also varied. Most of the pollen grains were monade. Tricolporate, tricolpate, monocolpate, pentaporate, and polyporate pollen aperture types have been observed. Most of the plants showed regular, reticulate, and echinate pollen sculpturing. Pollen fertility also varied from species to species but most of the plant showed pollen fertility between 70 and 80%. Through this work, it has been concluded that quantitative and qualitative pollen features are helpful at the specific level as well as the generic level and can provide a fruitful taxonomic solution.

Scanning electron microscopy observations of pollen morphology in common vetch (Vicia sativa) subspecies

AbstractCommon vetch (Vicia sativa) is an important forage and green manure crop that is widely cultivated around the world. However, the large number of subspecies and accessions of common vetch has made taxonomic research on this species difficult. Pollen morphology data can provide important evidence in the study of plant phylogeny. Therefore, in this research, light microscopy and scanning electron microscopy were used to observe seven morphological traits of pollens from 22 common vetch accessions, and residual maximum likelihood and pattern analysis was conducted. The results showed that the pollen grains of the 22 accessions were all monad pollen and the polar view revealed three-lobed circular and triangular shapes, while the equatorial view mainly revealed an oblate shape; only one accession showed an oblate spherical shape. All accessions were 3-zonocolporate and the colpus length extended close to the poles. The polar axis length was (19.39 ± 0.97)–(42.12 ± 0.76) μm and the equatorial axis length was (35.97 ± 1.27)–(45.25 ± 0.81) μm. We found that qualitative traits of pollen shape, aperture polar view and ornamentation were highly stable. Among them, polar axis length, equatorial axis length and colpus length and width had significant differences among the accessions. The ratios of the equatorial and polar axes had significant differences among the subspecies. This trait information could be used for the classification and identification of common vetch accessions and subspecies.

Morphological peculiarities of flowers, pollen grains and fruits of Valeriana tuberosa (Valerianaceae)

The results of the study of flowers, pollen grains and fruits of Valeriana tuberosa (sect. Tuberosae, Valerianaceae) are presented. Materials of the National Herbarium of the M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine (KW) were studied. The morphological structures of flowers, pollen grains and fruits were examined using both light microscopy and scanning electron microscopy; detailed descriptions of the elements of the flower, pollen grains and fruits were made and their specific features were established. The morphological features of the inflorescence, bracteoles, and the elements of the hermaphrodite flowers have been clarified. The pollen grains of V. tuberosa are 3-colpate, suboblate to subprolate (P/E = 0.85–1.33), medium- or large-sized. Their outline in equatorial view is elliptic, rarely circular, in polar view slightly trilobate or trilobate. Exine sculpture is echinate-microechinate with verrucae. The known and new carpological features are specified. In particular, papillate growth of periclinal walls of exocarp with stroke-shaped, jet and warty cuticular formations of the surface were noted the first time; details of exocarp stomatal system were revealed; features of trichomes and their cuticular structure on fruit wall are described. The obtained data are important additional characters for identification of the species and for the issues of taxonomy and phylogeny.

Pollen morphology of some species of the genus Cephalaria Schrad. (Caprifoliaceae) and its significance for taxonomy.

Palynology gives the evidence for identification and elimination of taxonomically complex genera. Pollen morphology of nine species (three subg., three sect.) of the genus Cephalaria Schrad. was studied using light microscopy and scanning electron microscopy. Pollen grains of all investigated species are triporate, suboblate to subprolate (P/E = 0.75-1.28), and large-sized (P = 58.52 μm-114.38, E = 63.84-119.70 μm). The outline of pollen grains in equatorial view is circular or elliptic, in polar view circular, circular-triangular, or triangular. Pores are distinct, lolongate, elliptic, or circular, with an annulus, operculum, and distinct or indistinct, wide halo surrounding the aperture. Exine sculpture is echinate-microechinate or echinate-microechinate-nanoechinate. Additional diagnostic characters at the species level in Cephalaria Schrad. that can be used for the purposes of taxonomy are size of pollen grains and pores, the shape of pores, the width of the annulus, structure of the exine, dimension of echini and microechini, location of microechini, and presence/absence of nanoechini. Palynomorphological data are compared with the taxonomical classification system of investigated taxa. It is shown that pollen grains morphology of the genus Cephalaria Schrad. is similar to the pollen morphology of the genus Dipsacus L., which confirms their inclusion in the Dipsaceae tribe.

Application and implication of scanning electron microscopy for evaluation of palyno-morphological features of Vitaceae from Pakistan.

The present study aimed to investigate the palyno-morphological features of species of family Vitaceae from Pakistan. A total of nine species, belonging to four genera were collected, pressed, identified, and then analyzed microscopically. Both quantitative and qualitative characters of the pollen grains were recorded including polar and equatorial diameter, P/E ratio, number of colpi and pores, exine thickness and shapes of the pollen in both polar and equatorial view, and exine sculpturing using Leica microscope fitted with camera Meiji Infinity 1 and then analyzed statistically using software IBM SPSS Statistics 20. The results of the present study demonstrated the variations in polar and equatorial diameter, exine thickness, P/E ratio, pollen shape, and exine sculpturing of the studied species and highlighted the significance of pollen morphology as an identification tool. The present study may contribute to better understand the classification at genus level, which will support the future phylogenetic characterization of the family.

Pollen Transport to Lycium cooperi (Solanaceae) Flowers by Flies and Moths

Lycium cooperi (Solanaceae) is a woody shrub found along the eastern, northern, and western edges of the Mojave Desert in Arizona, Nevada, and California and along the western edge of the Sonoran Desert in California and Mexico. The plant produces funnel-shaped flowers during spring with stamens and a pistil that extend to near the top of a greenish-white corolla. I investigated the pollination of L. cooperi in southern Nevada during 30 March–21 April 2019 by aspirating insects from flowers, determining where they carried pollen on their bodies, and estimating the proportions of conspecific pollen in their pollen loads. Flowers were mostly visited at night by 8 species of moths (Lepidoptera) in Noctuidae and Geometridae and less frequently during the day by 3 species of flies (Diptera) in Syrphidae. The most frequent visitor to flowers was Euxoa serricornis (Noctuidae), followed by Digrammia colorata (Geometridae) and Peridroma saucia (Noctuidae), a widespread agricultural pest. Most flies at flowers were 2 large species of Copestylum. Flowers were also visited by the migratory butterfly Vanessa cardui (Lepidoptera: Nymphalidae). Pollen was carried mainly on the proboscis of moths and butterflies and on the anterior thorax of flies. Lycium cooperi pollen grains in brightfield microscopy are trilobed in polar view, elliptic in equatorial view, and grainy in appearance. A higher mean proportion of L. cooperi pollen was carried by moths and butterflies (0.50) compared with flies (0.21), and moths in Noctuidae carried a higher proportion of conspecific pollen (0.59) compared with moths in Geometridae (0.25). Insects pollinated only 19.8% of the profuse flowers produced by shrubs. Pollination of L. cooperi primarily by moths corresponds with the shrub's partially white and tubular flowers. Similar flowers on most other Lycium species in the Mojave and Sonoran Deserts indicate a likelihood of similar pollination by moths.

Calibrating Geosynchronous and Polar Orbiting Satellites: Sharing Best Practices

Earth remote sensing optical satellite systems are often divided into two categories—geosynchronous and sun-synchronous. Geosynchronous systems essentially rotate with the Earth and continuously observe the same region of the Earth. Sun-synchronous systems are generally in a polar orbit and view differing regions of the Earth at the same local time. Although similar in instrument design, there are enough differences in these two types of missions that often the calibration of the instruments can be substantially different. Thus, respective calibration teams develop independent methods and do not interact regularly or often. Yet, there are numerous areas of overlap and much to learn from one another. To address this issue, a panel of experts from both types of systems was convened to discover common areas of concern, areas where improvements can be made, and recommendations for the future. As a result of the panelist’s efforts, a set of eight recommendations were developed. Those that are related to improvements of current technologies include maintaining sun-synchronous orbits (not allowing orbital decay), standardization of spectral bandpasses, and expanded use of well-developed calibration techniques such as deep convective clouds, pseudo invariant calibration sites, and lunar methodologies. New techniques for expanded calibration capability include using geosynchronous instruments as transfer radiometers, continued development of ground-based prelaunch calibration technologies, expansion of RadCalNet, and development of space-based calibration radiometer systems.