Summer Solstice Research Articles

Estimating the drift velocity of plasma bubbles in airglow images using the scale invariant feature transform and the speeded up robust feature algorithms

Equatorial plasma bubbles (EPBs) are ionospheric irregularities that can significantly impact radio communication, causing signal scintillation that leads to signal loss and error in position calculations. In this study, we introduced a new technique to estimate the eastward and northward drift velocities of the EPB from ASI data by tracking the Scale Invariant Feature Transform (SIFT) and the Speeded Up Robust Features (SURF) points. The technique has been tested by studying multiple EPBs events detected over the Brazilian sector during the autumn equinox, spring equinox and summer solstice. The chosen events occurred during quiet nights (Kp index ≤ 3) and were observable through two All-Sky imager (ASI) stations. Moreover, the study shows the performance of the technique under different circumstances. It achieves optimal performance on clear-sky nights; however, cloud presence within the ASI field of view increases the error within the estimated values. The estimated velocities were found to be within the range reported by previous studies in the Brazilian sector.

Effect of Thermal Environment on Heat Transfer Mechanism of Solar-Powered Balloon

Solar energy units, as an ideal alternative, can be supplied to the balloons by mounting them over the envelope of the balloon. To avoid superheating and superpressure, the solar-powered balloon’s thermal efficiency should be controlled. In the current research, the thermal model of a solar-powered zero-pressure balloon has been built up and simulated in FORTRAN via iterative techniques and validated with published experimental data. The simulation of stratospheric solar-powered balloon flight has been carried out in real seasonal atmospheric conditions. The temperature variation of solar panels, interior helium, and balloon envelope material has been observed and compared with the unpowered balloon in winter and summer atmospheric conditions. The output power performance of the photovoltaic panel placed over the balloon with and without thermal effect has been reported. Furthermore, the characteristic length, angle, and area of the solar panel effects on photovoltaic panel temperature and output power are discussed in detail. The maximum temperature of the helium and envelope of the solar-powered balloon is obtained as 350.03 K and 351.19 K, respectively, and is notable in the summer solstice compared with the unpowered balloon. This research would help design the energy unit of the stratospheric balloon for long endurance.

Multi-scale correlation analysis between geometric parameters and solar radiation in high density urban environment——Case study in Nanjing

This study explores the impact of multi-scale urban morphology on solar radiation in high-density environments, focusing on Nanjing as a case study. Using Grasshopper, the research decomposed urban models into four scales—district, block group, block, and plot—and analyzed eight morphological indicators, including site coverage (SC), floor area ratio (FAR), and block surface ratio (BSR). Solar radiation was simulated for the entire year, the summer solstice, and the winter solstice. Key findings reveal that different scales exhibit varying influences on solar radiation. At the district scale, BSR shows the highest correlation with annual solar radiation (R2 = 0.96), while at the neighborhood cluster scale, the minimum distance between buildings (DBmin) is most correlated (R2 = 0.7). At the block scale, BSR significantly correlates with summer solar radiation (R2 = 0.55). At the plot scale, no single indicator strongly correlates with solar radiation, but a combination of indicators is more relevant. These findings enable rapid solar performance assessments in urban design, promoting efficient solar energy use.

Theoretical analysis of upward-heating multiple-effect diffusion solar still with parabolic dish concentrator

Upward-heating multiple-effect diffusion solar still (UHMEDS) coupled with a parabolic dish concentrator (PDC) was proposed and analyzed theoretically. UHMEDS has cover glass, several partitions and preheating cover, and wicks are placed on the upper surfaces of partitions and preheating cover. Saline water preheated on the preheating cover flows down the partitions by gravitational force. The lowermost partition of UHMEDS was heated by solar energy collected by PDC. The basic behavior of UHMEDS at Fukuoka, Japan was analyzed theoretically by modeling heat and mass transfer in the still. The theoretical results show that PDC can collect the sunrays to the lowermost partition of UHMEDS effectively, and the overall daily productivity of the still was predicted to be about 18.5, 24.5 and 10.4 kg/m2day on spring equinox, summer and winter solstice days, respectively, which values are almost equivalent to those of other types of multiple-effect diffusion solar still.

Seasonal and Interhemispheric Variations of the Afternoon Auroral Responses to the Interplanetary Magnetic Field By Polarity

AbstractThis work investigates seasonal and interhemispheric variations of the afternoon auroral responses to the interplanetary magnetic field (IMF) By effects. The auroral observations are adopted from the global ultraviolet imager instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite during 2002–2007. The results show that in both summer and winter solstices, the stronger afternoon auroral intensity is associated with negative IMF By (By < 0) in the northern hemisphere, and with By > 0 in the southern hemisphere. This suggests stronger contributions from the upward field‐aligned currents (FACs), which can be induced by the By‐associated north‐south oriented electric field and the By‐associated flow shear in the ionosphere. In addition, the strongest afternoon aurora occurs in summer in each hemisphere. In summer, the absolute difference between the auroral peak intensity under the two By polarities is greater and occurs earlier than in winter, which may be related to changes in FACs and conductivity from winter to summer. Differently, in equinoxes stronger auroral intensity favors By conditions associated with more frequent occurrence of southward IMF Bz, such as By < 0 and By > 0 conditions in March and in September, respectively. Therefore, in equinoxes the effects of the favorable By, which were seen in solstices, are masked. We suggest that these are caused by the Russell‐McPherron effect, which leads to more southward Bz conditions, resulting in more energy deposited and subsequent stronger aurora in polar ionosphere. These results contribute to our deeper understanding of the asymmetrical phenomena in the Earth's magnetosphere‐ionosphere induced by IMF By.

On the Possible Astronomical Function of Portasar’s (G¨obekli Tepe) Pillar 27

The examination of Portasar’s Pillar 27 in Enclosure C from an archaeoastronomical point of view reveals four distinct directions. Considering the directions obtained as observational shows that they could have served to observe the simultaneous culminations of Pleiades, α Persei, and 36 Draconis pointing towards the North Ecliptic Pole during the activity period of the September ε-Perseid meteor shower. On the same day (perhaps a few days apart) before sunrise, it was most likely possible to observe the star disappearance of the constellations Hercules and Centaurus at their culmination points. At the same time, the T-shaped structure of Pillar 27 could serve as a shadow meter (gnomon) to show the specified day of the mentioned observations. Additionally, 36 days after the summer solstice (Perseids activity period), the simultaneous appearance of the stars β Andromedae and γ Draconis at their culmination points was observable. On the other hand, there are principal parallels with the possible observations with the help of Portasar’s Pillar 27 and the function of Platform 3 (as well as some angular stones (No. 7, 12, 158, etc.)) of the Zorats Qarer megalithic monument, which refer to the same millennium (9000 BC). There are also commonalities with ancient calendar patterns that relate to ancient mythological concepts. Their detailed analysis is still in progress.

On the Astronomical Significance of Stone Number 137 of Zorats Qarer Megalithic Monument

The work is dedicated to discovering a new type of “observational device” in the Zorats Qarer megalithic monument and uncovering a new layer of the continuous function of the monument using the “new device.” The possible use of the “new device” significantly differs from the observation platforms and angular stones in the same monument. Stone No. 137 in question was previously considered a ”periscope” based on some assumptions. By examining the astronomical and structural application of the mentioned stone in more detail and without preconceived assumptions (or with much simpler, obvious suppositions), new functions of its application are revealed. One relates to the observations of circumpolar stars in the direction of the stone hole. The other relies on the puddle and the special structure of the stone. The latter makes it possible to determine the days of the equinoxes and the summer solstice due to the Sun’s positions. By combining these two functions, the probable date of the use of the stone is determined: 15500 BC, when it was possible to observe the appearance of the star γ Cygni (Sadr, Swan constellation) after sunset on the summer solstice in the direction of the hole. Thus, a new layer of the “calendar observations” (15500 BC) is added to the already identified layers (9000, 5800, and 2341 BC), which is in harmony with the logic regarding this and other similar monuments (for example, G¨obekli Tepe) and essentially complements the evolutionary chain of ancient cultural concepts with its content and time.

The possibilities of GIS technologies for assessing and monitoring the climatic conditions of the Makazhoy Fepression (Chechen Republic, Russia)

Modeling based on a digital relief model of the spatiotemporal change in the amount of total solar radiation and the assessment of the contribution of locations to the distribution of meteorological elements.DEM analysis was conducted in a GIS environment to assess the spatial and temporal distribution of total solar radiation, and statistical analysis of retrospective climatic and actual (2023) meteorological data was conducted.Based on a digital model of the relief of average spatial resolution in a GIS environment, changes in the spatial and temporal magnitude of solar radiation were estimated. A prospective analysis of climatic conditions made it possible to assess the general features of the climate of the Makazhoy basin Field observations made it possible to characterize modern climatic conditions, as well as to calculate gradients.Depending on the locations, it was determined that the amount of total solar radiation in the Makazhoy basin varies by almost 3 times. Within the same altitude intervals, the difference between the slopes of the southern and northern exposures reaches up to 50 %. The smallest differences in the amount of radiation were observed on the days of the summer solstice, and the largest on the days of the winter solstice. The average annual air temperature in the altitude range of 1960–2264 m in 2023 varied from 8.6 to 5.8°, and the amount of precipitation – from 481 to 525 mm, respectively. The intra‐annual course of meteorological parameters (air temperature and leaf surface, precipitation and relative humidity) within the meteorological transect has been revealed. The data obtained make it possible to proceed to the formation of a GIS system for monitoring the climatic conditions of the carbon landfill of the Kadyrov Chechen State University.

Through Sun Tunnels: radical subjectivity and the radiant drive

ABSTRACT This essay considers the aesthetic stakes of light in Nancy Holt’s installation Sun Tunnels (1973–1976), emphasising their relation to subjective consciousness and time. Taking into account the question of systems Holt’s oeuvre also developed, the essay meditates on the rupture Holt’s installation in the Basin Desert in Utah provokes today, when the prevalence of social systems of immediate visibility and communication eliminate remoteness and deny unobservable, irreducibly intimate experience, or subjective time. A direct exploration of Sun Tunnels on the summer solstice 2022 grounds the essay’s proposal to seriously engage with the creative potentialities of the drive, and to furthermore consider, beyond Robert Smithson’s notion of the drive’s entropic character, a radiant or anthropic principle.

Strong Localized Pumping of Water Vapor to High Altitudes on Mars During the Perihelion Season

AbstractHere we present water vapor vertical profiles observed with the ExoMars Trace Gas Orbiter/Nadir and Occultation for MArs Discovery instrument during the perihelion and Southern summer solstice season (LS = 240°–300°) in three consecutive Martian Years 34, 35, and 36. We show the detailed latitudinal distribution of H2O at tangent altitudes from 10 to 120 km, revealing a vertical plume at 60°S–50°S injecting H2O upward, reaching abundance of about 50 ppmv at 100 km. We have observed this event repeatedly in the three Martian years analyzed, appearing at LS = 260°–280° and showing inter‐annual variations in the magnitude and timing due to long term effects of the Martian Year 34 Global Dust Storm. We provide a rough estimate of projected hydrogen escape of 3.2 × 109 cm−2 s−1 associated to these plumes, adding further evidence of the key role played by the perihelion season in the long term evolution of the planet's climate.

Determination of Rhythmicity and Gestational Stage-Related Distribution of Blood Plasma Melatonin Concentrations in Donkey Mares.

The aim of this study is to obtain a more complete picture of blood plasma melatonin concentrations in the donkey mares. To this purpose, sampling and statistical processing were carried out in such a way that allowed the researchers to establish the annual and daily rhythms. Based on human observations, according to the hypothesis of the authors, the blood plasma melatonin concentration of pregnant individuals rises during the late gestational period, before parturition. To confirm this, the melatonin concentrations of pregnant and non-pregnant jennies were monitored and compared. In regard to the circannual rhythm, the significantly lowest midnight melatonin value (27.67 pg mL-1) was typical for the summer solstice. Under consideration of circadian changes, a significantly strongest melatonin production (45.16 pg mL-1) was observed on the night of the winter solstice (p < 0.001). Considering gestational age, the blood plasma melatonin concentration (around 38 pg mL-1) does not change as gestation progresses (p = 0.136). The results obtained in this studied population of the domestic ass usefully expand the little knowledge previously gathered about the development of the blood plasma melatonin concentrations of this species.

The effectiveness and safety of acupoint herbal patching for allergic rhinitis: protocol for a systematic review and meta-analysis

BackgroundAllergic rhinitis (AR) is a common inflammatory disease of the nasal mucosa that is characterized by symptoms such as sneezing, nasal congestion, nasal itching, and rhinorrhoea. In recent years, acupoint herbal patching (AHP) therapy has gained a growing interest as a potential management option for AR. This systematic review and meta-analysis will evaluate the clinical research evidence on the effectiveness and safety of AHP as a treatment option for AR outside of the Sanfu or Sanjiu days (summer or winter solstice). The results of this review will provide up-to-date evidence-based guidance for healthcare providers and individuals seeking alternative treatments for AR.MethodsA comprehensive search of electronic databases (PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, China National Knowledge Infrastructure (CNKI), CQVIP, Sino-Med, and Wanfang Databases) will be conducted from their inception to June 2023. The inclusion criteria will be limited to randomized controlled trials that evaluate the effectiveness or efficacy of non-Sanfu or non-Sanjiu AHP for AR. The primary outcome measure will be the total nasal symptom score. The methodological quality of included studies will be assessed using the Revised Cochrane risk-of-bias tool for randomized trials (RoB 2), and meta-analyses will be performed using RevMan (V.5.3) statistical software. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach will be used to determine the certainty of evidence.DiscussionThis systematic review and meta-analysis will provide valuable insights into the effectiveness and safety of non-Sanfu or non-Sanjiu AHP as a treatment option for AR. The study aims to produce a high-quality review by adhering to PRISMA-P guidelines and using clinical guideline recommended outcome measures. The results of this review may offer additional treatment options for AR patients who seek complementary and alternative therapies, and hold significant implications for future research in this field. Overall, this study has the potential to inform clinical practice and improve patient outcomes.Systematic review registrationPROSPERO CRD42022181322.

Projected changes in ultraviolet index and UV doses over the twenty-first century: impacts of ozone and aerosols from CMIP6.

This study evaluated the health-related weighted ultraviolet radiation (UVR) due to the total ozone content (TOC) and the aerosol optical depth (AOD) changes. Clear-sky Ultraviolet Index (UVI), daily doses, and exposure times for erythema induction (Dery and Tery) and vitamin D synthesis (DvitD and TvitD) were computed by a radiative transfer estimator. TOC and AOD data were provided by six Earth System Models (ESMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6). For projections, we consider four Shared Socioeconomic Pathways scenarios-SSPs (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5)-and two time-slices (near: 2041-2060 and far future: 2081-2100). UVR projections showed pronounced changes for the summer hemispheres in the far future. TOC increases in mid- and high latitudes of the Southern Hemisphere caused decreases in UVR at the summer solstice. However, projections did not indicate sun-safe exposure conditions in South America, Australia, and Southern Africa. On the contrary, exposure around solar noon from 10 to 20min will still be sufficient to induce erythema in skin type III individuals throughout this century. In southern Argentina and Chile, the UVR insufficiency for vitamin D synthesis at solar noon in skin type III remains the same during this century at the winter solstice. In the Northern Hemisphere, UVI and Dery at the summer solstice should remain high (UVI ≥ 8; Dery ~ 7.0kJm-2) in highly populated locations. Above 45 °N, UVR levels cannot be enough to synthesize vitamin D in skin type III during the boreal winter. Our results show that climate change will affect human health through excess or lack of solar UVR availability.

The Feature Analysis and Modeling of Upper Atmospheric Midnight Density Maximum

The features of upper atmospheric midnight density maximum (MDM) around low geographic latitudes are studied based on neutral mass densities data at altitudes 360–480 km, derived from the accelerometer measurements aboard on the three polar orbiting satellites CHAMP (CHAllenging Minisatellite Payload), GRACE-A (Gravity Recovery and Climate Experiment-A), and SWARM-C (The Earth's Magnetic Field and Environment Explorers-C). The MDM appears during the local times from 23:00 to 02:00 LT (Local Time), whose peak locates at the low latitudes within 15∘ and two valleys locate at the middle latitudes between 35∘ and 45∘ on both hemispheres separately. The structure of MDM drifts toward the southern hemisphere overall. The MDM's amplitude decreases with increases in altitude and solar radiation level. The seasonal effect weakens the MDM's amplitudes around the summer and winter solstices, while the amplitudes around the spring and autumn equinoxes are extremely significant due to the slight seasonal difference between both hemispheres. Three atmospheric density models DTM2000 (Drag Temperature Model 2000), NRLMSISE00 (US Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar Extended atmosphere model), and JB2008 (Jacchia-Bowman 2008 model) are used to simulate the MDM along these three satellites' orbits, and compared with the observations. It is found that the JB2008 model is failed to describe the MDM, and the other two models underestimate the MDM's amplitudes at altitudes 360 km and 480 km: the simulated amplitudes by the DTM2000 model are 46% and 53% of the observed amplitudes, respectively, and only 33% and 26% for the NRLMSISE00 model. These three models are also failed to depict the MDM's variation with altitude, solar radiation level, and seasonal effects. In order to correct the model prediction, a 6th-order Legendre polynomial of geographic latitude, coupled with arguments of local time and altitude, is designed to fit the MDM signals from the three satellites' observations. In terms of amplitude and phase of the MDM, the fitting results agree with the observations very well, and the correlation coefficient is 0.923. It indicates that this empirical polynomial could be helpful to the density model correction and high accuracy prediction of spacecrafts in low Earth orbits.

Morphology of equatorial F-region irregularities over the Indian longitude sector using GPS-derived ROTI observations

The occurrence characteristics of Equatorial F-region Irregularities (EFIs) along the Indian longitude sector are investigated using GPS-derived ROTI observations from 2010 to 2023, under both quiet and disturbed geomagnetic conditions. The analysis of the results emphasizes a strong dependence of EFIs occurrence on solar cycle variation. Additionally, the EFIs are more intense at the EIA regions under maximum solar activity periods attributed to the high ambient electron density in the F-layer. The occurrence of EFIs is found to be severe and frequently observed in equinox seasons in contrast to solstice seasons. Also, the occurrence of EFIs exhibits equinoctial asymmetry with more intense EFIs in the spring equinox than autumn equinox during the peak and declining periods of the solar cycle. Conversely, severe EFIs are observed during autumn equinox than spring equinox in the ascending phase of the solar cycle. The seasonal occurrence probability of EFIs is highest in the equinox seasons, following the winter solstice, and summer solstice in high solar activity conditions. Investigations of EFIs during two prominent geomagnetic storm events (17 March 2015 and 08 September 2017) during the study period show that the storm-induced Prompt Penetration Electric Fields (PPEFs) modulated the regular intensity of dusk time Pre-Reversal Enhancement (PRE), resulting in poleward expansion of ionospheric irregularities up to mid-latitude regions with spatial time lag. However, storm-induced westward electric fields and oscillating IMF Bz created Counter Electrojet (CEJ) like conditions, suppressing the dusk time ionospheric irregularities over dip equatorial and low-latitude regions on 17 March 2013. This study provides a comprehensive understanding of how ionospheric irregularities manifest under varying conditions, thereby supporting further research on substantiating the spatiotemporal EFIs characteristics and their predictions over the region.

Optimal design of multilayer optical thin film structure for smart energy saving applications using needle optimization approach

In this work, a novel design of a one dimensional photonic crystal (1D PC) is investigated. The 1DPC structure is composed of alternating layers of tantalum pentoxide (Ta2O5) and silicon dioxide (Sio2). The proposed 1D PC structure is designed to act as short wave pass (SWP) edge filter that selectively passes light of short wavelengths, while the infrared light is blocked. In this study, Essential Macleod software is used to create the optimal design with the computational support of the needle synthesis technique. By varying the incidence angle of the mean polarized light mode, we can determine the features of the optimal SWP edge filter design, which leads to an important application for this filter. It can shed light on the filter’s suitability as a smart energy saving window coating for hot climate regions. The study includes different hot regions in Saudi Arabia such as Mecca, Riyadh, Dammam, Arar and Alaqiq. They were used as case studies in this research. According to the study of the optimal design of SWP edge filter applied in Mecca, Riyadh, Dammam, Arar and Alaqiq provinces, the light transmittance in the visible region is more than 99% during the summer solstice and more than 96% during the winter solstice. The photonic band gab (PBG) is almost constant during the summer solstice without shifting or decreasing in size whereas in the winter solstice, the PBG shifts toward the short wavelengths and decreases in size by increasing the angle of incidence. This allows an amount of solar energy to enter in winter. Riyadh, Dammam, and Arar provinces experienced a significant increase in solar energy during the winter solstice, more than Mecca and Alaqiq provinces.

Study on saline-alkali water distillation system by reflection enhanced solar heating

A saline-alkali water distillation system by reflection enhanced solar heating is proposed to treat the saline-alkali soil washing water. In this system, the heat concentration collector employs heat collecting plate to receive solar radiation energy, and converges to small-area steam generating tube through efficiently heat transfer. Without expensive optical tracking equipment, the system also employs an external reflector to reflect the solar radiation to the surface of the heat concentration collector. Thereby the energy flow density is further increased, and the useful energy and vaporization intensity is promoted. The latent heat of the steam is reused by heat recovery to enhance the energy utilization efficiency. The optimal inclination angles of reflector in different seasons and system performance were theoretically calculated. In the spring equinox, summer solstice, autumn equinox, and winter solstice, the optimal inclination angles of the reflector were 30°, 45°, 30°, and 15°, respectively. The freshwater production, useful energy, and heat recovery efficiency of the system were investigated by experiments. The daily freshwater production of the system was 17.04 kg, and the maximum production rate was 3.44 kg/h. The reflector increased the useful energy and freshwater production of the system by 33.68% and 35%, respectively. With heat recovery, the initial temperature of the saline-alkali water was increased to 53.8 °C and the freshwater production was increased by 13.16%.

Seasonal variation of melatonin secretion across various segments of the gastrointestinal tract in rats

ObjectiveTo investigate whether melatonin (MT) secretion in different parts of the gastrointestinal tract (GIT) exhibits seasonal variations and its correlation with immune regulation. MethodsSixty Sprague-Dawley rats were divided into control and model groups, and the pineal gland was removed in the model group. Stomach, jejunum, ileum, and colon tissues were obtained during the spring equinox, summer solstice, beginning of autumn, autumn equinox, and winter solstice. The levels of MT, MT receptors (MR), arylalkylamine N-acetyltransferase (AANAT), hydroxyindole-O-methyltransferase (HIOMT), interleukin-2 (IL-2), and interleukin-10 (IL-10) in the GIT were measured using enzyme-linked immunosorbent assay. ResultsExcept for the stomach, the jejunum, ileum, and the colon showed seasonal tendencies in MT secretion. In the control group, MT secretion in the jejunum and ileum was the highest in the long summer, and colonic MT secretion was the highest in winter. In the model group, MT levels in the colon were highest in the summer. The seasonal rhythms of the MR, AANAT, HIOMT, IL-2, and IL-10 in the colon were roughly similar to those of MT, and changed accordingly after pinealectomy. ConclusionsGastrointestinal MT secretion is related to seasonal changes, and MT secretion in each intestinal segment is influenced by different seasons. The biological effects of MT in the gut are inextricably linked to the mediation of MR, and a hormone-receptor linkage exists between MT and MR. The effect of seasonal changes on the gastrointestinal immune system may be mediated through the regulation of seasonal secretion of MT.

Variability of Atomic Hydrogen Brightness in the Martian Exosphere: Insights From the Emirates Ultraviolet Spectrometer on Board Emirates Mars Mission

AbstractThe Emirates Mars Ultraviolet Spectrometer (EMUS), aboard the Emirates Mars Mission (EMM), has been conducting observations of ultraviolet emissions within the Martian exosphere. Taking advantage of the distinctive orbit of the EMM around Mars, EMUS utilizes a dedicated strafe observation strategy to scan the illuminated Martian exosphere at tangential altitudes ranging from 130 to over 20,000 km. To distinguish between emissions of Martian origin and those from the interplanetary background, EMUS conducts specialized background observations by looking away from the planet. This approach has allowed us to investigate the radial and seasonal variations in Martian coronal emission features at H Lyman‐α, β and γ wavelengths. Our analysis supports the previous studies indicating that Martian exospheric hydrogen Lyman emission brightness attains its highest levels around the southern summer solstice and reaches its lowest levels when Mars is near aphelion. Additionally, a secondary peak emission at all altitudes is observed after perihelion during Martian Year (MY) 36, which can be attributed to a Class C dust storm. Our study establishes a strong correlation between solar flux and coronal brightness for these emissions, highlighting the impact of solar activity on the visibility of Martian corona. In addition, we have examined interannual variability and found that emission intensities in MY 37 surpassed those in MY 36, primarily due to increased solar activity. These observations help to understand potential seasonal patterns of exospheric hydrogen, which is driven by underlying mechanisms in the lower atmosphere and solar activity, eventually suggesting an impact on water loss in the Martian atmosphere.

Caring for herd animals in Isluga

Chapter 3 of the book Earth, Water, Fleece and Fabric, first published in 2002, is presented in this article. It is based on periods of fieldwork carried out between 1986 and the late 1990s. In the previous chapter of the book, it was suggested that camelid domestication arose from the taming of successive generations of animals as part of the daily practices of herding. Domestication was not a once and forall event in the distant past. The present article focuses on the thick description of Isluga people’s herding strategies duringthe 1980s and 1990s. Isluga is an Aymara community in the Chilean highlands, bordering with Bolivia. Caring for camelidsin this community constitutes a process whereby herders sustain and renew lasting relationships between human beingsand herd animals. Cycles of time and space are described in order to contextualisehow and where the herders look after their llamas, alpacas and sheep. All Souls Day marks the arrival of the rainy seasonand Carnival is the event which brings it to an end. The austral summer solstice occurs on the cusp between these two festivalsand coincides with the fiesta of St. Thomas. Isluga people call themselves the «children of Saint Thomas», in a tradition which is inscribed in the topography of their territory. The other season of the year is cold and dry. It is associated with the winds of St. James the Greater and St. Anthony of Padua.The annual cycle therefore unfolds in a calendar of saints’ days accompanied by atmospheric phenomena, which nurturethe pasture grounds. The herding activities take place in a volcanic landscape associatedwith land forms which are perceived to be animated and gendered. The earth is personified as the Wirjin Tayka or Pachamama and the hills as Uywiri. Isluga people engage with these beings on a daily basis. These land forms can serve as aviadores, «providers», associated with the fertility and wellbeing of camelids and sheeps. The composition of the herds of llamas and alpacas is analysed, as well as the classifications Isluga people make accordingto age and gender. Camelid nomenclature is based on the disposition of dark and light colours in the coat of llamas and alpacas. Isluga people use names for their camelids which are intimately related to birds and other beings in their surroundings.The dense description offered makes it possible to analyse the regenerative cycle of water, pasture and fleece in a comparative ethnography, in the light of themes developed in other parts of the book, from which this article has been extracted.