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Reliable modelling of the solar potential of urban surfaces (i.e. roofs, facades and ground) in the built environment can contribute to boost the exploitation of solar energy. Empirical and quasi-physical models are combined into model chains for this scope. Among these models, the decomposition models are used to separate the direct from the diffuse solar irradiance. Such variables are rarely measured, thus making necessary their computation. Studies in literature pointed out that Yang4 is the best-performing decomposition model globally. However, in geographically limited applications, quasi-universal decomposition models like Yang4 and Engerer4 can be outperformed by local models (i.e. models parametrized with climate-specific data) such as Skartveit3 and Starke3. This makes necessary to perform local validation studies to verify the findings from worldwide validation studies. In this study, the four best-performing decomposition models are implemented in Python and experimentally validated against 1-min solar irradiance data (i.e. direct and diffuse irradiance) of Trondheim (Lat. 63°26′N, Norway). More than 1-year long data are considered. The study confirms that the Yang4 model performed the best for high-latitude applications, but Starke3 can achieve a level of performance close to Yang4. [ABSTRACT FROM AUTHOR]

The high latitude ionospheric evolution of the May 10‐11, 2024, geomagnetic storm is investigated in terms of Total Electron Content and contextualized with Incoherent Scatter Radar and ionosonde observations. Substantial plasma lifting is observed within the initial Storm Enhanced Density plume with ionospheric peak heights increasing by 150–300 km, reaching levels of up to 630 km. Scintillation is observed within the cusp during the initial expansion phase of the storm, spreading across the auroral oval thereafter. Patch transport into the polar cap produces broad regions of scintillation that are rapidly cleared from the region after a strong Interplanetary Magnetic Field reversal at 2230UT. Strong heating and composition changes result in the complete absence of the F2‐layer on the eleventh, suffocating high latitude convection from dense plasma necessary for Tongue of Ionization and patch formation, ultimately resulting in a suppression of polar cap scintillation on the eleventh. Plain Language Summary: The intense geomagnetic storm of May 2024 caused a plethora of different responses within the Earth's ionosphere. In the early phases of the storm, the auroral oval quickly expands to upper midlatitudes and induces strong variations in Global Navigation Satellite System (GNSS) phase measurements. Concurrently, midlatitude plasma is repeatedly lifted by 100–300 km on timescales of about an hour resulting in enhanced plasma densities. This intensified and lifted plasma is then drawn into the polar cap inducing variations in GNSS amplitude and phase. As the storm evolves, heating drives mixing of the thermosphere and causes an extreme depletion in ionospheric plasma. After 24 hr, despite severe geomagnetic conditions persisting, the depleted plasma environment results in only relatively weak plasma transport into the polar cap and significantly reduced impacts on GNSS. Key Points: Plasma lifting during the storm caused midlatitude displacements of ionospheric peak height by as much as 300 km over the course of 1 hourSporadic‐E is observed at the sub‐auroral convective boundary edge of the storm‐enhanced density with strong plasma drift shears presentSevere depletion of electron density at mid and high latitudes significantly reduced the impact of subsequent geomagnetic activity on GNSS [ABSTRACT FROM AUTHOR]

A solar eclipse (SE) leads to perturbations of all subsystems in the Earth–atmosphere–ionosphere–magnetosphere system and to perturbations of geophysical fields. Each SE leads to a whole series of physical and chemical processes occurring in the ionosphere. Along with common features, each SE has its own peculiarities with regard to these processes. These processes depend on the solar activity phase, time of the year, time of the day, geographic coordinates, atmospheric weather, space weather, magnitude of eclipse, etc. Therefore, studying these effects during each SE is an urgent task. The aim of this study is to describe the results of the analysis of the effects features of the SE which was observed shortly after sunrise on October 25, 2022 mainly at high latitudes. The data obtained from a network of space stations and navigation satellites moving over the region of partial SE were used for observations. It is found that the maximum decrease in the total electron content (TEC) in the ionosphere in these observations was 1.6–4.1 TECU, and its relative decrease reached 12–25%. The maximum decrease in the TEC was delayed 18–33 min in time with respect to the point in time when the maximum magnitude of the SE was reached. The duration of the response of the ionosphere to the SE was 120–180 min, which exceeded the eclipse duration. [ABSTRACT FROM AUTHOR]

In this paper, we examine the features of RSDN-20 signal propagation in a high-latitude Earth–ionosphere waveguide during solar proton events, using computational experiment methods. We have analyzed two proton ground-level enhancement (GLE) events of December 13, 2006 (GLE70) and September 10, 2017 (GLE72). Electron density profiles were constructed using the Global Dynamic Model of Ionosphere (GDMI) and the RUSCOSMICS model, developed at PGI. We present estimated phase and amplitude changes in RSDN-20 signals during precipitation of high-energy protons in the high-latitude region of the Earth–ionosphere waveguide. From the results of computational experiments and the analysis of the electromagnetic signal attenuation based on analytical Maxwell’s equation system solution in magnetized ionospheric plasma, we have found a pattern in the signal attenuation frequency dependence associated simultaneously with the signal reflection height, electron density profiles, and the collision frequency of electrons with neutral particles and ions. We discuss limitations of the computational experiment method and compare simulation results with data from Lovozero and Tuloma observatories.

To investigate the impact of short summers and long summer solar periods at high latitudes on the behavior of a nocturnal, hibernating mammal, we recorded the phenology of Myotis lucifugus (little brown myotis) at 60° N in the Northwest Territories (NWT), Canada. In particular, we assessed the timing of spring emergence from, and autumn entry into, hibernation, reproduction, and seasonal mass fluctuations. We used a combination of acoustic monitoring and capture surveys at two hibernacula and two maternity roosts during 2011 and 2012. Myotis spp. were active at the hibernacula from late April to late September/early October, suggesting that the "active" season length is similar to that of populations farther south. At maternity colonies, we detected M. lucifugus activity from early May to early October, with peaks during mid‐July in both years. Lactation, fledging, and weaning all occurred later in the NWT than at more southern locations, and reproductive rates were significantly lower than rates observed farther south. The average mass of individuals fluctuated throughout the season, with an initial decline immediately following emergence from hibernation likely reflecting increased energy expenditure due to flight and decreased use of torpor, coupled with relatively low prey intake due to low prey abundance associated with cool temperatures. Females did not appear to have lower pre‐hibernation masses than those in more southern populations, suggesting that despite the cool spring and autumn temperatures, and short summer nights, bats are able to obtain enough energy for reproduction and mass accumulation for hibernation. However, the lower reproductive rates may indicate that there are limitations to life at the northern limits of the species' range. [ABSTRACT FROM AUTHOR]

In the northern high latitudes, warmer spring temperatures generally lead to earlier leaf onsets, higher vegetation production, and enhanced spring carbon uptake. Yet, whether this positive linkage has diminished under climate change remains debated. Here, we used atmospheric CO2 measurements at Barrow (Alaska) during 1979–2020 to investigate the strength of temperature dependence of spring carbon uptake reflected by two indicators, spring zero‐crossing date (SZC) and CO2 drawdown (SCC). We found a fall and rise in the interannual correlation of temperature with SZC and SCC (RSZC‐T and RSCC‐T), showing a recent reversal of the previously reported weakening trend of RSZC‐T and RSCC‐T. We used a terrestrial biosphere model coupled with an atmospheric transport model to reproduce this fall and rise phenomenon and conducted factorial simulations to explore its potential causes. We found that a strong–weak–strong spatial synchrony of spring temperature anomalies per se has contributed to the fall and rise trend in RSZC‐T and RSCC‐T, despite an overall unbroken temperature control on net ecosystem CO2 fluxes at local scale. Our results provide an alternative explanation for the apparent drop of RSZC‐T and RSCC‐T during the late 1990s and 2000s, and suggest a continued positive linkage between spring carbon uptake and temperature during the past four decades. We thus caution the interpretation of apparent climate sensitivities of carbon cycle retrieved from spatially aggregated signals. [ABSTRACT FROM AUTHOR]

The isotope values of fossil snail shells can be important archives of climate. Here, we present the first carbon (δ13C) and oxygen (δ18O) isotope values of snail shells in interior Alaska to explore changes in vegetation and humidity through the late-glacial period. Snail shell δ13C values were relatively consistent through the late glacial. However, late-glacial shell δ13C values are 2.8‰ higher than those of modern shells. This offset is best explained by the Suess effect and changes in the δ13C values of snail diet. Snail shell δ18O values varied through the late glacial, which can be partially explained by changes in relative humidity (RH). RH during the snail growing period was modeled based on a published flux balance model. Results suggest a dry period toward the beginning of the Bølling–Allerød (~14 ka) followed by two distinct stages of the Younger Dryas, a wetter stage in the early Younger Dryas from 12.9 to 12.3 ka, and subsequent drier stage in the late Younger Dryas between 12.3 and 11.7 ka. The results show that land snail isotopes in high-latitude regions may be used as a supplementary paleoclimate proxy to help clarify complex climate histories, such as those of interior Alaska during the Younger Dryas. [ABSTRACT FROM AUTHOR]

Aim: Bergman patterns, the tendency of organisms to be larger at higher latitudes and lower temperatures, are a well‐studied biogeographic pattern. Yet, there is no consensus on the driver or underlying mechanisms. We aim to scrutinize the influence of several key proposed drivers of Bergmann patterns (temperature, seasonal light availability, prey size and seasonal abundance) on optimal body size in planktivorous fishes across high latitudes in the Northeast Atlantic. Location: Northeast Atlantic between 55 and 75° N, with implications for high‐latitude oceans globally. Time period: Present day. Major taxa studied: Pelagic planktivorous fishes, with Atlantic herring (Clupea harengus) as model organism. Methods: We use a model that incorporates explicit mechanisms for vision‐based feeding and temperature‐dependent physiology of a planktivorous fish to explore how intrinsic and extrinsic constraints affect energy budgeting and thereby expected optimal body size based on bioenergetics. We run the model at latitudes with increasing seasonality and test the individual and joint effects of relevant drivers. Results: A Bergmann pattern emerges from the interaction between visual feeding opportunities and temperature‐dependent physiology. Small individuals profit from faster energy processing at higher temperatures in the south, whereas large individuals benefit from a lower metabolic cost at colder temperatures and more daylight hours for feeding in the north. In isolation temperature, daylight hours, and prey size each produced Bergmann patterns, but the most pronounced pattern arose from all drivers combined. Main conclusions: Studying biogeographic body size patterns requires a holistic view, accounting for interactions between drivers and both intrinsic and extrinsic constraints on energy budgeting. Across latitudes, temperature effects on digestion and metabolism interact with effects of light availability, prey size and abundance on food accessibility, and thereby shape the optimal size. Our study highlights how details of ecological mechanisms and lifestyles are important for improving predictive ability. [ABSTRACT FROM AUTHOR]

Abstract To investigate the impact of short summers and long summer solar periods at high latitudes on the behavior of a nocturnal, hibernating mammal, we recorded the phenology of Myotis lucifugus (little brown myotis) at 60° N in the Northwest Territories (NWT), Canada. In particular, we assessed the timing of spring emergence from, and autumn entry into, hibernation, reproduction, and seasonal mass fluctuations. We used a combination of acoustic monitoring and capture surveys at two hibernacula and two maternity roosts during 2011 and 2012. Myotis spp. were active at the hibernacula from late April to late September/early October, suggesting that the “active” season length is similar to that of populations farther south. At maternity colonies, we detected M. lucifugus activity from early May to early October, with peaks during mid‐July in both years. Lactation, fledging, and weaning all occurred later in the NWT than at more southern locations, and reproductive rates were significantly lower than rates observed farther south. The average mass of individuals fluctuated throughout the season, with an initial decline immediately following emergence from hibernation likely reflecting increased energy expenditure due to flight and decreased use of torpor, coupled with relatively low prey intake due to low prey abundance associated with cool temperatures. Females did not appear to have lower pre‐hibernation masses than those in more southern populations, suggesting that despite the cool spring and autumn temperatures, and short summer nights, bats are able to obtain enough energy for reproduction and mass accumulation for hibernation. However, the lower reproductive rates may indicate that there are limitations to life at the northern limits of the species' range.

The Galileo High-Accuracy Service (HAS) was declared operational (initial service) in January 2023 after an intense testing phase aimed at assessing its service performance through the transmission of live HAS corrections. The HAS performance at high latitudes is evaluated by analyzing data collected at the Polish Polar Station located in Hornsund, in the Norwegian Svalbard archipelago. At such a location, the reception conditions can be affected by poor satellite geometries and ionospheric scintillation may degrade the signal quality. In this respect, data affected by scintillation events were identified and used for the performance analysis. The assessment is carried out by comparing the HAS corrections with the International GNSS Service (IGS) precise products. Moreover, the retrieved HAS corrections are used to assess the Precise Point Positioning (PPP) performance. [ABSTRACT FROM AUTHOR]

This study relates answers to the Munich Chronotype Questionnaire (MCTQ) and Pittsburgh Sleep Quality Index (PSQI) from Arctic Sojourn Workers (ASW) of Yamburg Settlement, 68° Latitude North, 75° Longitude East (n = 180; mean age ± SD; range: 49.2 ± 7.8; 25–66 y; 45% women) to Arctic Sojourn Work Experience (ASWE), age and health status. Chronotype, Mid Sleep on Free Days sleep corrected (MSFsc) and sleep characteristics of ASW were compared to those of age-matched Tyumen Residents (TR, n = 270; mean age ± SD; range: 48.4 ± 8.4; 25–69 y; 48% women), 57° Latitude North, 65° Longitude East. ASW have earlier MSFsc than TR (70 min in men, p < 0.0001, and 45 min in women, p < 0.0001). Unlike TR, their MSFsc was not associated with age (r = 0.037; p = 0.627) and was linked to a larger Social Jet Lag (+21 min in men; p = 0.003, and +18 min in women; p = 0.003). These differences were not due to outdoor light exposure (OLE): OLE on work (OLEw) or free (OLEf) days was not significantly different between ASW and TR in men and was significantly less in ASW than in TR women (OLEw: −31 min; p < 0.001; OLEf: −24 min; p = 0.036). ASWE, but not age, was associated with compromised lipid metabolism in men. After accounting for multiple testing, when corrected for age and sex, higher triglycerides to high-density lipoprotein ratio, TG/HDL correlated with ASWE (r = 0.271, p < 0.05). In men, greater SJL was associated with lower HDL (r = -0.204; p = 0.043). Worse proxies of metabolic health were related to unfavorable components of the Pittsburgh Sleep Quality Index in ASW. Higher OLE on free days was associated with lower systolic (b = -0.210; p < 0.05) and diastolic (b = -0.240; p < 0.05) blood pressure. [ABSTRACT FROM AUTHOR]

This review focuses on the solar irradiance model chain for horizontal-to-tilted irradiance conversion at high latitudes. The main goals of the work are 1) to assess the extent to which the literature accounts for decomposition and transposition models specifically developed for high-latitude application; 2) to evaluate existing validation studies for these particular conditions; 3) to identify research gaps in the optimal solar irradiance model chain for high-latitude application (i.e., latitude ≥60°). In total, 112 publications are reviewed according to their publication year, country, climate, method, and keywords: 78 publications deal with decomposition models and 34 deal with transposition models. Only a few models (6) have been parameterized using data from Nordic countries. Here, we compare 57 decomposition models in terms of their performance in Nordic climate zones and analyze the geographical distribution of the data used to parametrize these models. By comparing the Normalized Root Mean Square Deviation coefficients for direct normal irradiation, the decomposition models Skartveit1 and Mondol1 are most effective on one-hour scale and Yang4 on one-minute scale. Recent studies on the empirical transposition models estimating the global tilted irradiation on vertical surfaces show the best performance for Perez4 and Muneer models. In addition, innovative methods such as artificial neural networks have been identified to further enhance the model chain. This review reveals that a validated model chain for estimating global tilted irradiation at high latitudes is missing from the literature. Moreover, there is a need for a universal validation protocol to ease the comparison of different studies.

This paper describes a field study of the illumination and lighting energy use in a full-scale test office in a building located in southern Norway. Natural light is provided to the office via southwest-oriented windows and a horizontal light pipe (HLP) with a daylight entrance facing the south. The study is a full-scale field study, and it is a continuation of the recently published study addressing a scale model and a theoretical model. The novelty of this study is a custom-made reflector for the HLP’s daylight distribution to preserve the features of natural light noted as the primary human association with daylight. The main research aim was to determine if the daylighting level in the back of the office was improved as a consequence of the daylighting provision from the HLP compared to a reference situation without a HLP, as well as whether the lighting energy use for the electric lighting system that was supposed to provide the recommended light level was reduced. This study includes monitoring of the outdoor and indoor illuminance levels as well as the energy consumption of the luminaires throughout the study’s test period and a corresponding reference period. The recorded data were used to test hypothesis applying inferential statistical analyses. In conclusion, this paper reports an increased daylight level on the working area in the rear part of the office of approximately 200 to 300 lx during clear and sunny days at equinox. The increased daylight level on the working area near the window of approximately 50 lx was also recorded. These findings have important implications for energy balance in the Zero Energy Buildings (ZEB) and the ‘peak load’ for energy consumption.

Forages are the most important kind of crops at high latitudes and are the main feeding source for ruminant-based dairy industries. Maximizing the economic and ecological performances of farms and, to some extent, of the meat and dairy sectors require adequate and timely supportive field-specific information such as available biomass. Sentinel-2 satellites provide open access imagery that can monitor vegetation frequently. These spectral data were used to estimate the dry matter yield (DMY) of harvested forage fields in northern Sweden. Field measurements were conducted over two years at four sites with contrasting soil and climate conditions. Univariate regression and multivariate regression, including partial least square, support vector machine and random forest, were tested for their capability to accurately and robustly estimate in-season DMY using reflectance values and vegetation indices obtained from Sentinel-2 spectral bands. Models were built using an iterative (300 times) calibration and validation approach (75% and 25% for calibration and validation, respectively), and their performances were formally evaluated using an independent dataset. Among these algorithms, random forest regression (RFR) produced the most stable and robust results, with Nash–Sutcliffe model efficiency (NSE) values (average ± standard deviation) for the calibration, validation and evaluation of 0.92 ± 0.01, 0.55 ± 0.22 and 0.86 ± 0.04, respectively. Although relatively promising, these results call for larger and more comprehensive datasets as performances vary largely between calibration, validation and evaluation datasets. Moreover, RFR, as any machine learning algorithm regression, requires a very large dataset to become stable in terms of performance. [ABSTRACT FROM AUTHOR]

In this article, a cluster comprised of eight Continuously Operating Reference Station (CORS) receivers surrounding five supplemental test stations located on much shorter baselines is used to form a composite multi-scale network for the purpose of isolating, extracting, and analyzing ionospheric spatial gradient phenomena. The purpose of this investigation is to characterize the levels of spatial decorrelation between the stations in the cluster during the periods with increased ionospheric activity. The location of the selected receiver cluster is at the auroral zone at night-time (cluster centered at about 69.5° N, 19° E) known to frequently have increased ionospheric activity and observe smaller size of high-density irregularities. As typical CORS networks are relatively sparse, there is a possibility that spatially small-scale ionospheric delay gradients might not be observed by the network/closest receiver cluster but might affect the user, resulting in residual errors affecting system accuracy and integrity. The article presents high level statistical observations based on several hundred manually validated ionospheric spatial gradient events along with low level analysis of specific events with notable temporal/spatial characteristics. [ABSTRACT FROM AUTHOR]

Landsliding is among the most massive and active exogenous processes. Such processes are now occurring more and more actively in permafrost zones due to climate change, and require close attention and careful study. Analysis of a territory highly prone to these processes, namely Banks Island, one of the largest islands in northern Canada, confirms earlier studies of landslide processes in this zone, which indicate a relationship between increased activation of landslides and abnormally warm summers. The study and assessment of the landslide focus parameters in the southern part of Banks Island shows that in 1976–1999, the development of landslides was relatively uniform. Nevertheless, after 1999 there was a sharp increase in their size. We identify two types of landslide activation: broad activations in 1999, 2011, 2012, and 2013 with corresponding annual occurrence rates of 20–30 landslides; and occasional (local) activations, with landslides occurring at a rate of 1–2 annually in the intervals between the broad ones. The landslide foci have a random spatial distribution, though these processes take place in particular geological conditions and topography. The largest landslides reach 100 m along the slope and 50 m across the slope. With the help of cluster analysis according to the parameters of the sum of the length and width of landslides, six classes are distinguished, which differ primarily in the intensity and scale of movements. The spatial distribution of landslides by class of behavior in time is even more random than the distribution by year. No new activations after 2015 were identified within the research area. Undoubtedly, the study of the landslide frequency should be continued in the future. [ABSTRACT FROM AUTHOR]

Ongoing global warming particularly affects the coldest regions of our planet, where thunderstorm activity is considered to be the lowest. Scientific studies usually predict that lightning will become more frequent in polar areas in a warmer world. The aim of this study is to test this hypothesis and present the current knowledge on thunderstorm occurrence at high latitudes (>60°) based on SYNOP data from manned WMO stations operating from 2000 to 2019. According to this source, most thunderstorm events at high latitudes occur in summer (85%), when the air temperature ranges from 15 to 25°C (70%), during the days with positive temperature anomalies (75%) and negative sea‐level pressure anomalies (65%). The highest thunderstorm activity is observed over inland areas, especially in the European part of Russia. The changes in thunderstorm frequency are only visible at certain WMO manned stations and mostly during the summer months. The regional Kendall test revealed a statistically significant increase in the number of thunderstorm days north of 60°N in Interior Alaska, northwestern Canada, much of Siberia and European Russia. A decrease in thunderstorm frequency over a larger area was detected only on the shores of the southern Norwegian Sea, and seasonally in spring in the northern Urals. The observed trends were strongest in the Central Siberia and Interior Alaska regions, where the increase in the number of thunderstorm days exceeded 5 per decade. For the entire high‐latitude area, the change in the number of days with thunderstorms was statistically insignificant, but for stations located 250–1,000 km from the coastline, the averaged increase amounted 1 day per decade. [ABSTRACT FROM AUTHOR]

Phenological shifts not only alter the growing season length, but also modify land‐atmosphere exchanges of water and energy, which in turn affects ecosystem carbon uptake. However, how changes in the start of the growing season (SOS) affect carbon uptake throughout growing season has not been fully explored for high‐latitude ecosystems. Here, we investigated the impacts of SOS shifts on carbon uptake and the mechanisms over 2000–2020 in the northern high latitudes (>50°N) using multiple satellite and climate data sets. We found a contrasting response of gross primary productivity (GPP) in the early (April–June) and late (July–September) growing season to SOS shifts. Advanced SOS resulted in increased early‐season GPP, whereas slightly decreased late‐season GPP. The earlier SOS resulted from a warmer early season, which induced a decline of snow to precipitation ratio, therefore drier soil and atmosphere. In the early season, when water requirement of vegetation was low, the warm and dry conditions ensured favorable solar radiation and improved vegetation water use efficiency (WUE), thus enhancing photosynthesis. The dry soil and atmosphere conditions extended to the late season due to less snow and excessive water utilization by vegetation in the early season, which therefore slightly suppressed photosynthesis by weakening WUE. Conversely, the delayed SOS resulted in reduced early‐season GPP and slightly enhanced late‐season GPP due to the opposite thermal and moisture conditions to that of advanced SOS. The SOS is likely to be further advanced as warming continues in the high latitudes, intensifying seasonal contrasts in vegetation photosynthesis capacity. Plain Language Summary: Spring phenology shifts not only change the length of growing season, but modify local and regional climate that in turn affects the magnitude of ecosystem carbon uptake, which is not well understood, particularly in the high‐latitude ecosystems. Here, we investigated the effects of a shifting spring phenology on subsequent seasonal carbon uptake and explored the underlying mechanisms in the northern high latitudes (>50°N) using satellite data and climate data sets. We found that warming‐induced earlier spring resulted in an enhanced carbon uptake in the early season (April–June), but slightly weakened carbon uptake in the late season (July–September). Early season warming caused advanced spring greenup dates and drier conditions with improved vegetation water use efficiency (WUE). The warm and dry conditions improved vegetation WUE because of the low water requirement, thus enhancing vegetation productivity. The dry conditions extended to the late season due to less snow. With the higher temperature in the late season, water stress reduced the WUE of vegetation and therefore resulted in a slight decrease in vegetation productivity. Key Points: There was a contrasting response of carbon uptake to spring phenology shifts between the early (April–June) and late (July–September) seasonEarly season warming caused earlier spring phenology and drier conditions with improved water use efficiency (WUE), thus enhancing photosynthesisThe dry conditions extended to the late season due to less snow, and slightly suppressed photosynthesis by weakening WUE [ABSTRACT FROM AUTHOR]

This paper describes a field study of the illumination and lighting energy use in a full-scale test office in a building located in southern Norway. Natural light is provided to the office via southwest-oriented windows and a horizontal light pipe (HLP) with a daylight entrance facing the south. The study is a full-scale field study, and it is a continuation of the recently published study addressing a scale model and a theoretical model. The novelty of this study is a custom-made reflector for the HLP's daylight distribution to preserve the features of natural light noted as the primary human association with daylight. The main research aim was to determine if the daylighting level in the back of the office was improved as a consequence of the daylighting provision from the HLP compared to a reference situation without a HLP, as well as whether the lighting energy use for the electric lighting system that was supposed to provide the recommended light level was reduced. This study includes monitoring of the outdoor and indoor illuminance levels as well as the energy consumption of the luminaires throughout the study's test period and a corresponding reference period. The recorded data were used to test hypothesis applying inferential statistical analyses. In conclusion, this paper reports an increased daylight level on the working area in the rear part of the office of approximately 200 to 300 lx during clear and sunny days at equinox. The increased daylight level on the working area near the window of approximately 50 lx was also recorded. These findings have important implications for energy balance in the Zero Energy Buildings (ZEB) and the 'peak load' for energy consumption. [ABSTRACT FROM AUTHOR]

The Galileo High-Accuracy Service (HAS) was declared operational (initial service) in January 2023 after an intense testing phase aimed at assessing its service performance through the transmission of live HAS corrections. The HAS performance at high latitudes is evaluated by analyzing data collected at the Polish Polar Station located in Hornsund, in the Norwegian Svalbard archipelago. At such a location, the reception conditions can be affected by poor satellite geometries and ionospheric scintillation may degrade the signal quality. In this respect, data affected by scintillation events were identified and used for the performance analysis. The assessment is carried out by comparing the HAS corrections with the International GNSS Service (IGS) precise products. Moreover, the retrieved HAS corrections are used to assess the Precise Point Positioning (PPP) performance.

The widespread impacts of projected global and regional climate change on rice yield have been investigated by different indirect approaches utilizing various simulation models. However, direct approaches to assess the impacts of climatic variabilities on rice growth and development may provide more reliable evidence to evaluate the effects of climate change on rice productivity. Climate change has substantially impacted rice production in the mid-high latitudes of China, especially in Northeast China (NEC). Climatic variabilities occurring in NEC since the 1970s have resulted in an obvious warming trend, which made this region one of the three major rice-growing regions in China. However, the projections of future climate change have indicated the likelihood of more abrupt and irregular climatic changes, posing threats to rice sustainability in this region. Hence, understanding the self-adaptability and identifying adjustive measures to climate variability in high latitudes has practical significance for establishing a sustainable rice system to sustain future food security in China. A well-managed field study under randomized complete block design (RCBD) was conducted in 2017 and 2018 at two study sites in Harbin and Qiqihar, located in Heilongjiang province in NEC. Four different cultivars were evaluated: Longdao-18, Longdao-21 (longer growth duration), Longjing-21, and Suijing-18 (shorter growth duration) to assess the inter-relationships among grain-filling parameters, grain yield and yield components, and grain quality attributes. To better compare the adaptability mechanisms between grain-filling and yield components, the filling phase was divided into three sub-phases (start, middle, and late). The current study evaluated the formation and accumulation of the assimilates in superior and inferior grains during grain-filling, mainly in the middle sub-phase, which accounted for 59.60% of the yield. The grain yields for Suijing-18, Longjing-21, Longdao-21, and Longdao-18 were 8.02%, 12.78%, 17.19%, and 20.53% higher in Harbin than those in Qiqihar, respectively in 2017, with a similar trend observed in 2018. At Harbin, a higher number of productive tillers was noticed in Suijing-18, with averages of 17 and 15 in 2017 and 2018, respectively. The grain-filling parameters of yield analysis showed that the filling duration in Harbin was conducive to increased yield but the low dry weight of inferior grains was a main factor limiting the yield in Qiqihar. The average protein content values in Harbin were significantly higher (8.54% and 9.13%) than those in Qiqihar (8.34% and 9.14%) in 2017 and 2018, respectively. The amylose content was significantly higher in Harbin (20.03% and 22.27%) than those in Qiqihar (14.44% and 14.67%) in 2017 and 2018, respectively. The chalkiness percentage was higher in Qiqihar, indicating that Harbin produced good quality rice. This study provides more direct evidence of the relative changes in rice grain yield due to changes in grain-filling associated with relative changes in environmental components. These self-adaptability mechanisms to climatic variability and the inter-relationships between grain-filling and grain yield underscore the urgent to investigate and explore measures to improve Japonica rice sustainability, with better adaptation to increasing climatic variabilities. These findings may also be a reference for other global rice regions at high latitudes in addressing the impacts of climate change on future rice sustainability. [ABSTRACT FROM AUTHOR]

Snow cover is an important part of the Earth's surface and its changes affect local and even global climates due to the high albedo and heat insulation. However, it is difficult to directly compare the results of previous studies on changes in snow cover in the Northern Hemisphere mainland (NH) due to the use of different datasets, research methods, or study periods, and a lack comparison in terms of the differences and similarities at high latitudes and high altitudes. By using snow depth datasets, we analyzed the spatio-temporal distributions and variations in snow depth (SD) and snow phenology (SP) in the NH and nine typical areas. This study revealed that SD in the NH generally decreased significantly (p < 0.01) from 1988 to 2018, with a rate of −0.55 cm/decade. Changes in SD were insignificant at high altitudes, but significant decreases were found at high latitudes. With regard to SP, the snow cover onset day (SCOD) advanced in 31.57% of the NH and was delayed in 21.10% of the NH. In typical areas such as the Rocky Mountains, the West Siberian Plain, and the Central Siberian Plateau, the SCOD presented significant advancing trends, while a significant delay was the trend observed in the Eastern European Plain. The snow cover end day (SCED) advanced in 37.29% of the NH and was delayed in 14.77% of the NH. Negative SCED trends were found in most typical areas. The snow cover duration (SCD) and snow season length (SSL) showed significant positive trends in the Rocky Mountains, while significant negative trends were found in the Qinghai–Tibet Plateau. The results of this comprehensive comparison showed that most typical areas were characterized by decreased SD, advanced SCOD and SCED, and insignificantly increasing SCD and SSL trends. The SCD and SSL values were similar at high latitudes, while the SSL value was larger than the SCD value at high altitudes. The SD exhibited similar interannual fluctuation characteristics as the SCD and SSL in each typical area. The SCD and SSL increased (decreased) with advanced (delayed) SCODs. [ABSTRACT FROM AUTHOR]

The widespread impacts of projected global and regional climate change on rice yield have been investigated by different indirect approaches utilizing various simulation models. However, direct approaches to assess the impacts of climatic variabilities on rice growth and development may provide more reliable evidence to evaluate the effects of climate change on rice productivity. Climate change has substantially impacted rice production in the mid-high latitudes of China, especially in Northeast China (NEC). Climatic variabilities occurring in NEC since the 1970s have resulted in an obvious warming trend, which made this region one of the three major rice-growing regions in China. However, the projections of future climate change have indicated the likelihood of more abrupt and irregular climatic changes, posing threats to rice sustainability in this region. Hence, understanding the self-adaptability and identifying adjustive measures to climate variability in high latitudes has practical significance for establishing a sustainable rice system to sustain future food security in China. A well-managed field study under randomized complete block design (RCBD) was conducted in 2017 and 2018 at two study sites in Harbin and Qiqihar, located in Heilongjiang province in NEC. Four different cultivars were evaluated: Longdao-18, Longdao-21 (longer growth duration), Longjing-21, and Suijing-18 (shorter growth duration) to assess the inter-relationships among grain-filling parameters, grain yield and yield components, and grain quality attributes. To better compare the adaptability mechanisms between grain-filling and yield components, the filling phase was divided into three sub-phases (start, middle, and late). The current study evaluated the formation and accumulation of the assimilates in superior and inferior grains during grain-filling, mainly in the middle sub-phase, which accounted for 59.60% of the yield. The grain yields for Suijing-18, Longjing-21, Longdao-21, and Longdao-18 were 8.02%, 12.78%, 17.19%, and 20.53% higher in Harbin than those in Qiqihar, respectively in 2017, with a similar trend observed in 2018. At Harbin, a higher number of productive tillers was noticed in Suijing-18, with averages of 17 and 15 in 2017 and 2018, respectively. The grain-filling parameters of yield analysis showed that the filling duration in Harbin was conducive to increased yield but the low dry weight of inferior grains was a main factor limiting the yield in Qiqihar. The average protein content values in Harbin were significantly higher (8.54% and 9.13%) than those in Qiqihar (8.34% and 9.14%) in 2017 and 2018, respectively. The amylose content was significantly higher in Harbin (20.03% and 22.27%) than those in Qiqihar (14.44% and 14.67%) in 2017 and 2018, respectively. The chalkiness percentage was higher in Qiqihar, indicating that Harbin produced good quality rice. This study provides more direct evidence of the relative changes in rice grain yield due to changes in grain-filling associated with relative changes in environmental components. These self-adaptability mechanisms to climatic variability and the inter-relationships between grain-filling and grain yield underscore the urgent to investigate and explore measures to improve Japonica rice sustainability, with better adaptation to increasing climatic variabilities. These findings may also be a reference for other global rice regions at high latitudes in addressing the impacts of climate change on future rice sustainability.

The paper investigates a total of 725 combinations of decomposition and transposition models for calculating the solar potential of building-integrated photovoltaics. Model outputs were experimentally validated against one-minute data from the six building surfaces – the four facades, the tilted roof, and the southwards pergola – of the Zero Emission Building Laboratory, in Trondheim (Norway). The surrounding built environment was considered through shadow masks and sky view factors. We proposed a new cumulative performance indicator, which was comprehensive of the commonest statistical indicators in validation studies, to identify the models that best fitted the observations, for each surface. Perez2/Temps and Perez1/Perez1 optimally handled the tilted roof and pergola, respectively, but they were outperformed by Perez1/Perez1 and Perez3/Perez1 in case of vertical facades. These model chains were further analysed by mapping the distribution of residuals according to the time and the predictor values. The availability of data points influenced the model chain performance as observed for the fourth trimester (November, December, January) in the monthly analysis and the sunrise/sunset hours in the hourly analysis. Re-parametrizing the models by giving greater weight to these time frames can enhance the model's reliability. Additionally, larger and/or more dispersed residuals were found for clearness index values lower than 0.40 and for angle of incidence values higher than 50 ° or close to 20 °. Similarly, rooms for improvement for model chain performance were identified in the case of relative airmass values from 5 to 10 and low global horizontal clear-sky irradiance. • 725 model chains were implemented and validated for six orientations at high latitudes. • A new cumulative performance index was proposed and used for ranking the model chains. • Perez1/Olmo2, Perez2/Temps, Perez1/Perez1, and Perez3/Perez1 achieved the best scores. • Temporal domain and conditions in which model chains perform the best were outlined. [ABSTRACT FROM AUTHOR]

The harsh environment of high-latitude areas with large amounts of snow and ice cover makes it difficult to carry out full geological field surveys. Uranium resources are abundant within the Ilimaussaq Complex in the Narsaq region of Greenland, where the uranium ore body is strictly controlled by the Lujavrite formation, which is the main ore-bearing rock in the complex rock mass. Further, large aggregations of radioactive minerals appear as thermal anomalies on remote sensing thermal infrared imagery, which is indicative of deposits of highly radioactive elements. Using a weight-of-evidence analysis method that combines machine-learned lithological classification information with information on surface temperature thermal anomalies, the prediction of radioactive element-bearing deposits at high latitudes was carried out. Through the use of Worldview-2 (WV-2) remote sensing images, support vector machine algorithms based on texture features and topographic features were used to identify Lujavrite. In addition, the distribution of thermal anomalies associated with radioactive elements was inverted using Landsat 8 TIRS thermal infrared data. From the results, it was found that the overall accuracy of the SVM algorithm-based lithology mapping was 89.57%. The surface temperature thermal anomaly had a Spearman correlation coefficient of 0.63 with the total airborne measured uranium gamma radiation. The lithological classification information was integrated with surface temperature thermal anomalies and other multi-source remote sensing mineralization elements to calculate mineralization-favorable areas through a weight-of-evidence model, with high-value mineralization probability areas being spatially consistent with known mineralization areas. In conclusion, a multifaceted remote sensing information finding method, focusing on surface temperature thermal anomalies in high-latitude areas, provides guidance and has reference value for the exploration of potential mineralization areas for deposits containing radioactive elements. [ABSTRACT FROM AUTHOR]

Many global climate models (GCMs) have difficulty in simulating climate variabilities over high northern latitudes. One of the main reasons is the inability of GCMs to simulate proper cloud fraction and the amount of liquid-containing cloud over the region. This study assessed the impact of cloud simulation in high latitudes by comparing the long-term parallel simulations of Community Atmosphere Model version 6 (CAM6) and CAM5, the previous version. The results show that the CAM6 simulation exhibits a considerable improvement in the Arctic, especially by reducing the cold bias of CAM5 throughout the year. Over the sub-Arctic region, however, CAM6 produces an excessive cold bias in summer and a warm bias in winter compared to the observation, which is closely related to the overestimation of cloud fraction and the amount of cloud liquid. In summer, the overestimation of the cloud in CAM6 tends to alleviate the cold bias compared to CAM5 due to an increase in downward longwave radiation over the high latitudes, while causing the excessive cold bias by blocking downward shortwave radiation over the sub-Arctic land area. In winter, when there is little incidence of shortwave radiation, the overestimation of the cloud in CAM6 increases the downward longwave radiation, which alleviates the cold bias in CAM5 over the Arctic but induces an excessive warm bias over the sub-Arctic land. The excessive cloudiness in CAM6 could weaken the high-latitude internal variability, exacerbating the deteriorating climate variability and long-term trend simulations in the region. [ABSTRACT FROM AUTHOR]

Impacts of climate change on ocean productivity sustaining world fisheries are predominantly negative but vary greatly among regions. We assessed how 39 fisheries resources—ranging from data‐poor to data‐rich stocks—in the North East Atlantic are most likely affected under the intermediate climate emission scenario RCP4.5 towards 2050. This region is one of the most productive waters in the world but subjected to pronounced climate change, especially in the northernmost part. In this climate impact assessment, we applied a hybrid solution combining expert opinions (scorings)—supported by an extensive literature review—with mechanistic approaches, considering stocks in three different large marine ecosystems, the North, Norwegian and Barents Seas. This approach enabled calculation of the directional effect as a function of climate exposure and sensitivity attributes (life‐history schedules), focusing on local stocks (conspecifics) across latitudes rather than the species in general. The resulting synopsis (50–82°N) contributes substantially to global assessments of major fisheries (FAO, The State of World Fisheries and Aquaculture, 2020), complementing related studies off northeast United States (35–45°N) (Hare et al., PLoS One, 2016, 11, e0146756) and Portugal (37–42°N) (Bueno‐Pardo et al., Scientific Reports, 2021, 11, 2958). Contrary to prevailing fisheries forecasts elsewhere, we found that most assessed stocks respond positively. However, the underlying, extensive environmental clines implied that North East Atlantic stocks will develop entirely different depending upon the encountered stressors: cold‐temperate stocks at the southern and Arctic stocks at the northern fringes appeared severely negatively impacted, whereas warm‐temperate stocks expanding from south were found to do well along with cold‐temperate stocks currently inhabiting below‐optimal temperatures in the northern subregion. [ABSTRACT FROM AUTHOR]

Accurate irradiance forecasts are needed for the growing solar energy industry also in Northern Europe. We have compared irradiance forecasts from an operational numerical weather prediction (NWP) model, a satellite‐based model, and persistence models. We aim to determine whether operational NWP models are suitable for forecasting irradiance at the high latitudes, and how their accuracy compares to the satellite‐based model. We have included all members and the ensemble average of the MetCoOp ensemble prediction system (MEPS), the MetCoOp‐Nowcasting (MNWC) system, the satellite‐based Solis‐Heliosat model, and two persistence models. The comparison is made as a point comparison against in situ irradiance observations in Finland and Sweden, for intra‐day forecasts with hourly and 15‐min output and the full forecast of MEPS with hourly output. In addition, we show two energy market case studies. We find the operational NWP models to be very suitable for irradiance forecasting in the area, up to the full horizon of the forecasts. Solis‐Heliosat errors grow with lead time, while the NWP model errors are largest in the beginning, settling to smaller values after the first hours. Solis‐Heliosat has more accuracy for the first 2–3 h of the forecast, after which NWP models produce better forecasts. However, during morning periods Solis‐Heliosat is found to have limited accuracy, while conversely, MNWC performs better in the morning than in the afternoon. The energy market case study highlights the same results: NWP models do well with forecasting irradiance in Fennoscandia, but the optimal selection of forecast model depends on the required forecast horizon and time. [ABSTRACT FROM AUTHOR]

This article presents the preliminary stage of a wider study that aims to determine the effect of a densification process on solar accessibility in a consolidated Nordic built environment through the use of a multi-domain approach. A set of solar accessibility analyzes are conducted for actual and future scenarios at three urban domains of analysis: (i) outdoor, (ii) envelope, and (iii) indoor, using as metrics (i) hours of direct sunlight on the 21st of March, (ii) seasonal and annual irradiation, and (iii) average daylight factor. The approach is applied to a case study located at high latitude (Trondheim, Norway; latitude 63.43° N) for the development of the university campus. The results show a reduction in solar accessibility fin all the tested domains when the new project is inserted into the plot. Almost two-thirds of the outdoor area fails to comply with the recommended target of five hours of direct sunlight access, while none of the 21 analyzed facades is considered suitable for the installation of active solar systems. The indoor daylight level is also severely compromised, with all four ground floors of the tested buildings falling short of the target 2% average daylight factor in the future scenario. However, the selection of high reflective materials as the finishing cladding for the newly designed buildings can compensate for the losses due to the new buildings’ masses. This study demonstrates how a set of solar analyzes in different urban domains can identify the critical aspects of a densification process in its preliminary design stages and open future possibilities for urban morphology, districts and buildings’ design optimization.

Seven satellite scatterometers, namely, the C-band MetOp-A/Advanced Scatterometer (ASCAT), MetOp-B/ASCAT, MetOp-C/ASCAT, Ku-band HY-2A/SCAT, HY-2B/SCAT, Chinese-French Oceanography Satellite (CFOSAT)/SCAT, and SCATSAT-1/OceanSat Satellite Scatterometer (OSCAT2), are operating in orbits. These satellites make a high-frequency observation of sea surface winds possible, particularly at high latitudes. This work analyzes the passing time, passing frequency, coverage of these seven scatterometers, and the quality of high-latitude surface wind products. All the scatterometer wind products were reproduced with the same processing procedures, in terms of backscatter calibration, wind retrieval, numerical weather prediction (NWP) wind, and quality control. The target region (74–78 N, 167°–171 W) was chosen to analyze the passing frequency. A spatial grid of $0.25^{\circ } \times 0$.25° in the range of 60° N–88° N was chosen to analyze the spatial coverage of the scatterometers. The results show that more than 40 observation times can be provided daily by all the seven scatterometers; however, there is a 9-h gap between UTC 9:00 and UTC 18:00, suggesting that international cooperation is needed for optimizing the equatorial crossing time in future scatterometer missions, such that an optimal virtual scatterometer constellation can be achieved. The scatterometer winds are compared with the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis 5th Generation (ERA5) winds, and with each other. The comparison results confirmed noticeable wind speed biases due to sea surface temperature (SST) in all Ku-band scatterometer winds with respect to the C-band scatterometer and ERA5 winds. [ABSTRACT FROM AUTHOR]

Over‐the‐horizon radar (OTHR) systems operating in the high‐frequency (HF) band (3–30 MHz) are unique in their ability to detect targets at extreme ranges, offering cost‐effective large‐area surveillance. Due to their reliance on the reflective nature of the ionosphere in this band, OTHR systems are extremely sensitive to ionospheric conditions and can expect significant variations in operational performance. At high latitudes, the presence of auroral enhancements in the E‐Region electron density can substantially modify the coverage area and frequency management of OTHR systems. In this study, HF raytracing is utilized to investigate these impacts for a hypothetical radar under different auroral conditions simulated using the Empirical Canadian High Arctic Ionospheric Model. Aurora were seen to increase maximum usable frequency from 8.5 to 26 MHz whilst also reducing median available range from 2,541 to 1,226 km and changing coverage area by −50.4% to 58.6%, for the greatest differences. Target interception showed large variations in path coverage of between 33%–115% and 0%–107% for two flight paths tested with precipitation toggled. Two distinct auroral propagation modes were observed, noted as the F‐E ducted and Auroral E‐modes. Long‐range coverage provided by the auroral F‐E ducted mode was of limited capacity with low solar activity due to reduced NmF2. F‐mode propagation transitioned to the dominating Auroral E‐mode between Auroral Electrojet index values of 50‐ and 200‐nT. The significant variations in both frequency and coverage observed within this study highlight some aspects of the importance of considering aurora in OTHR modeling and design. Plain Language Summary: Over‐the‐horizon radar (OTHR) systems can detect targets at extreme ranges by reflecting high‐frequency radio waves in the 3–30 MHz band off the ionosphere, an ionized portion of the upper atmosphere, to beyond the horizon. Due to the large coverage area provided by a single radar, OTHR can be a cost‐effective solution to monitoring expansive areas; however, as OTHR relies on the ionosphere to reflect radio waves, any disturbances that may be present within the ionosphere, such as aurora, can have a profound effect on the operation of OTHR systems. This may be realized as a drastic change in available coverage area and a disruption to operational frequency, amongst other effects. To better understand the direct implications of aurora on OTHR operation, we model a hypothetical OTHR using specialized computer code to represent the ionosphere and trace the path of radio waves under different conditions. We find that principally, aurora act to increase the maximum frequency available to the radar whilst also reducing the overall range of the covered area. In addition to this, we observed aurora reflecting radio waves in two new manners, unavailable without aurora present; this included the ducting of radio waves and the introduction of lower altitude reflections. Key Points: Auroral conditions associated with Auroral Electrojet index >100 nT substantially modify the coverage of a hypothetical over‐the‐horizon radar (OTHR) in northern UKEnhanced auroral activity causes a significant variation in the coverage area of a northern UK OTHR system and an increase in overall maximum usable frequencyIn instances of low background electron density, such as solar minimum winter, aurora may be the only available mode for OTHR operation [ABSTRACT FROM AUTHOR]

Abstract Over‐the‐horizon radar (OTHR) systems operating in the high‐frequency (HF) band (3–30 MHz) are unique in their ability to detect targets at extreme ranges, offering cost‐effective large‐area surveillance. Due to their reliance on the reflective nature of the ionosphere in this band, OTHR systems are extremely sensitive to ionospheric conditions and can expect significant variations in operational performance. At high latitudes, the presence of auroral enhancements in the E‐Region electron density can substantially modify the coverage area and frequency management of OTHR systems. In this study, HF raytracing is utilized to investigate these impacts for a hypothetical radar under different auroral conditions simulated using the Empirical Canadian High Arctic Ionospheric Model. Aurora were seen to increase maximum usable frequency from 8.5 to 26 MHz whilst also reducing median available range from 2,541 to 1,226 km and changing coverage area by −50.4% to 58.6%, for the greatest differences. Target interception showed large variations in path coverage of between 33%–115% and 0%–107% for two flight paths tested with precipitation toggled. Two distinct auroral propagation modes were observed, noted as the F‐E ducted and Auroral E‐modes. Long‐range coverage provided by the auroral F‐E ducted mode was of limited capacity with low solar activity due to reduced NmF2. F‐mode propagation transitioned to the dominating Auroral E‐mode between Auroral Electrojet index values of 50‐ and 200‐nT. The significant variations in both frequency and coverage observed within this study highlight some aspects of the importance of considering aurora in OTHR modeling and design.

Summertime atmospheric teleconnection patterns over Eurasia have a significant influence on regional weather and climate. Despite extensive studies on the subtropical patterns, the high-latitude counterpart has received relatively less attention. This study proposes physical mechanisms for the formation and maintenance of the dominant high-latitude teleconnection pattern. The formation of the pattern is associated with variability in synoptic-scale eddy activity due to the meridional gradient of sea surface temperature anomalies in the vicinity of the Gulf Stream, causing a meridional shift of the central axis of storm track at the exit of Atlantic jet. The resultant convergence of transient vorticity fluxes to the west of the British Isles induces low-frequency cyclonic circulation anomalies and continued propagation of Rossby waves downstream along northern Eurasia. Once these circulation anomalies are formed, the subsequent latent heat-related diabatic anomalies over the northern Eurasian landmass act as another source of Rossby waves to maintain the teleconnection pattern. Regional temperature and precipitation variability is closely linked to the wave pattern along a route through northern Eurasia, and even precipitation over the East Asian summer monsoon region is influenced by the teleconnection pattern.

Abstract In this study, the Global Ionosphere Thermosphere Model is utilized to investigate the inter‐hemispheric asymmetry in the ionosphere‐thermosphere (I‐T) system at mid‐ and high‐latitudes (|geographic latitude| > 45°) associated with inter‐hemispheric differences in (a) the solar irradiance, (b) geomagnetic field, and (c) magnetospheric forcing under moderate geomagnetic conditions. Specifically, we have quantified the relative significance of the above three causes to the inter‐hemispheric asymmetries in the spatially weighted averaged E‐region electron density, F‐region neutral mass density, and horizontal neutral wind along with the hemispheric‐integrated Joule heating. Further, an asymmetry index defined as the percentage differences of these four quantities between the northern and southern hemispheres (|geographic latitude| > 45°) was calculated. It is found that: (a) The difference of the solar extreme ulutraviolet (EUV) irradiance plays a dominant role in causing inter‐hemispheric asymmetries in the four examined I‐T quantities. Typically, the asymmetry index for the E‐region electron density and integrated Joule heating at solstices with F10.7 = 150 sfu can reach 92.97% and 38.25%, respectively. (b) The asymmetric geomagnetic field can result in a strong daily variation of inter‐hemispheric asymmetries in the F‐region neutral wind and hemispheric‐integrated Joule heating over geographic coordinates. Their amplitude of asymmetry indices can be as large as 20.81% and 42.52%, which can be comparable to the solar EUV irradiance effect. (c) The contributions of the asymmetric magnetospheric forcing, including particle precipitation and ion convection pattern, can cause the asymmetry of integrated Joule heating as significant as 28.43% and 34.72%, respectively, which can be even stronger than other causes when the geomagnetic activity is intense.

Global warming has boosted vegetation growth to a large extent, but this stimulation effect has significantly weakened in recent years. Among the set of possible driving forces, the asymmetric daytime and nighttime warming effect has been largely neglected. To improve our understanding on the relationship between vegetation growth and global warming, this study tries to attribute the respective effects of daytime and nighttime temperature on vegetation growth and reveal their temporal trends in the extratropical Northern Hemisphere (30–90 °N). The results showed there had been significant warming trends in growing season maximum (TMX, 0.37 °C per decade) and minimum temperatures (TMN, 0.38 °C per decade) during 1982–2015, especially in high latitudes of the NH. Under the asymmetric diurnal warming, the effects of TMX and TMN on normalized difference vegetation index (NDVI) exhibited distinct temporal variations between mid- (55 °N). The positive correlation between NDVI and TMX (RNDVI-TMX) weakened in high latitudes, as well as the negative correlation between NDVI and TMN (RNDVI-TMN). However, the RNDVI-TMX and RNDVI-TMN changed little in mid-latitudes. Moreover, the weakening effect of TMX on NDVI was more apparent than that of TMN in high latitudes. The area with significantly (p

In this study, the Global Ionosphere Thermosphere Model is utilized to investigate the inter‐hemispheric asymmetry in the ionosphere‐thermosphere (I‐T) system at mid‐ and high‐latitudes (|geographic latitude| > 45°) associated with inter‐hemispheric differences in (a) the solar irradiance, (b) geomagnetic field, and (c) magnetospheric forcing under moderate geomagnetic conditions. Specifically, we have quantified the relative significance of the above three causes to the inter‐hemispheric asymmetries in the spatially weighted averaged E‐region electron density, F‐region neutral mass density, and horizontal neutral wind along with the hemispheric‐integrated Joule heating. Further, an asymmetry index defined as the percentage differences of these four quantities between the northern and southern hemispheres (|geographic latitude| > 45°) was calculated. It is found that: (a) The difference of the solar extreme ulutraviolet (EUV) irradiance plays a dominant role in causing inter‐hemispheric asymmetries in the four examined I‐T quantities. Typically, the asymmetry index for the E‐region electron density and integrated Joule heating at solstices with F10.7 = 150 sfu can reach 92.97% and 38.25%, respectively. (b) The asymmetric geomagnetic field can result in a strong daily variation of inter‐hemispheric asymmetries in the F‐region neutral wind and hemispheric‐integrated Joule heating over geographic coordinates. Their amplitude of asymmetry indices can be as large as 20.81% and 42.52%, which can be comparable to the solar EUV irradiance effect. (c) The contributions of the asymmetric magnetospheric forcing, including particle precipitation and ion convection pattern, can cause the asymmetry of integrated Joule heating as significant as 28.43% and 34.72%, respectively, which can be even stronger than other causes when the geomagnetic activity is intense. Plain Language Summary: There are significant differences between the Earth's two hemispheres. Understanding the inter‐hemispheric asymmetries in the mid‐ and high‐latitudes and their impacts on the upper atmosphere is a grand challenge to our geospace community. The main contributions to these asymmetries include: (a) the displacement between Earth's magnetic poles and geographic poles, (b) the seasonal solar EUV irradiation, and (c) the magnetospheric forcing, including the electric field and the auroral particle precipitation. However, it is still unclear to what extent the asymmetries can be generated in the ionosphere‐thermosphere (I‐T) quantities such as the electron density and neutral density between the northern and southern hemispheres due to the above three different causes. In this study, the asymmetric contributions of the above causes on I‐T quantities have been estimated through comparing groups of numerical runs using the Global Ionosphere and Thermosphere Model (GITM). For example, in order to examine the seasonal effects, the GITM runs with the spring equinox, northern summer, and northern winter solstices are compared, keeping the other causes the same. It is found that seasonal dependence of solar extreme ultraviolet irradiance plays a dominant role in causing hemispheric asymmetries in all the examined quantities; our results also suggest that the contribution of the asymmetric magnetospheric forcing could be even more important during intense storms than the other causes shown in this work. Key Points: Solar irradiance in the solstices causes significant asymmetries in the ionosphere‐thermosphere (I‐T) quantities as examined in this studyDisplacement between the geomagnetic and geographic coordinates produces a diurnal asymmetric variation in the I‐T systemMagnetospheric forcing affects the I‐T quantities especially the Joule heating, with stronger precipitation/electric field favoring more heating [ABSTRACT FROM AUTHOR]

Abstract We document the configuration, tuning, and evaluation of a modified version of the Community Earth System Model version 1 (Hurrell et al., 2013, https://doi.org/10.1175/BAMS-D-12), introduced here as E3SMv0‐HiLAT, intended for study of high‐latitude processes. E3SMv0‐HiLAT incorporates changes to the atmospheric model affecting aerosol transport to high northern latitudes and to reduce shortwave cloud bias over the Southern Ocean. An updated sea ice model includes biogeochemistry that is coupled to an extended version of the ocean model's biogechemistry. This enables cloud nucleation to depend on the changing marine emissions of aerosol precursors, which may be expected in scenarios with strongly changing sea ice extent, oceanic stratification and associated nutrient availability, and atmospheric state. An evaluation of the basic preindustrial state of E3SMv0‐HiLAT is presented in order to ensure that its climate is adequate to support future experimentation. Additional capability is not achieved without some cost, relative to the extraordinarily well‐tuned model from which it was derived. In particular, a reduction of bias in cloud forcing achieved over the Southern Hemisphere also allows for greater Southern Ocean sea ice extent, a tendency that has been partially but not fully alleviated through experimentation and tuning. The most interesting change in the behavior of the model may be its response to greenhouse gas forcing: While the climate sensitivity is found to be essentially unchanged from that of Community Earth System Model version 1, the adjusted radiative forcing has increased from within one standard deviation above that of Coupled Model Intercomparison Project Phase 5 models to nearly two standard deviations.

Daylight provision to the indoor space is affected by different building elements that cannot be fully controlled by the users, such as the window size of a space. The dimensions of the fenestration not only affect the lighting levels, but they also affect how the space is perceived by its users. The present study examines three different window sizes via virtual reality, to study how they affect the perception of both a small and a large space at high latitudes. Additionally, two context scenarios (socializing and working), as well as three different sky types (overcast sky and clear skies with either high or low sun angle) were evaluated. The experimental study applied a mixed design with within-subjects and between-subjects factors. A total of 150 participants evaluated the scenes using a Likert-type scale to rate eight different subjective attributes. The statistical results showed that both window size and space type significantly affect the participants' spatial perception, as well as their satisfaction with the amount of outside view. Larger windows led to more positively evaluated spaces for all studied attributes. Moreover, a significant interaction was found between window size and type of space for the satisfaction with the amount of view in the space, indicating that the window size was dependent on the type of space in which the windows are located. Specifically, the window sizes were rated higher in the small space than in the large space for the evaluation of amount of view. The findings show that window size affects how people perceive a space, and additionally, that other spatial features, such as space type, affect window size preferences. [ABSTRACT FROM AUTHOR]

Abstract In this study, a new high‐latitude empirical model is introduced, named for Auroral energy Spectrum and High‐Latitude Electric field variabilitY (ASHLEY). This model improves specifications of soft electron precipitations and electric field variability that are not well represented in existing high‐latitude empirical models. ASHLEY consists of three components, ASHLEY‐A, ASHLEY‐E, and ASHLEY‐Evar, which are developed based on the electron precipitation and bulk ion drift measurements from the Defense Meteorological Satellite Program (DMSP) satellites during the most recent solar cycle. On the one hand, unlike most existing high‐latitude electron precipitation models, which have assumptions about the energy spectrum of incident electrons, the electron precipitation component of ASHLEY, ASHLEY‐A, provides the differential energy fluxes in the 19 DMSP energy channels under different geophysical conditions without making any assumptions about the energy spectrum. It has been found that the relaxation of spectral assumptions significantly improves soft electron precipitation specifications with respect to a Maxwellian spectrum (up to several orders of magnitude). On the other hand, ASHLEY provides consistent mean electric field and electric field variability under different geophysical conditions by ASHLEY‐E and ASHLEY‐Evar components, respectively. This is different from most existing electric field models which only focus on the large‐scale mean electric field and ignore the electric field variability. Furthermore, the consistency between the electric field and electron precipitation is better taken into account in ASHLEY.

Ongoing climate change is already affecting crop production patterns worldwide. Our aim was to investigate how increasing temperature and CO2 as well as changes in precipitation could affect potential yields for different historical pedoclimatic conditions at high latitudes (i.e., >55°). The APSIM crop model was used to simulate the productivity of four annual crops (barley, forage maize, oats, and spring wheat) over five sites in Sweden ranging between 55 and 64°N. A first set of simulations was run using site-specific daily weather data acquired between 1980 and 2005. A second set of simulations was then run using incremental changes in precipitation, temperature and CO2 levels, corresponding to a range of potential future climate scenarios. All simulation sets were compared in terms of production and risk of failure. Projected future trends showed that barley and oats will reach a maximum increase in yield with a 1°C increase in temperature compared to the 1980–2005 baseline. The optimum temperature for spring wheat was similar, except at the northernmost site (63.8°N), where the highest yield was obtained with a 4°C increase in temperature. Forage maize showed best performances for temperature increases of 2–3°C in all locations, except for the northernmost site, where the highest simulated yield was reached with a 5°C increase. Changes in temperatures and CO2 were the main factors explaining the changes in productivity, with ~89% of variance explained, whereas changes in precipitation explained ~11%. At the northernmost site, forage maize, oats and spring wheat showed decreasing risk of crop failure with increasing temperatures. The results of this modeling exercise suggest that the cultivation of annual crops in Sweden should, to some degree, benefit from the expected increase of temperature in the coming decades, provided that little to no water stress affects their growth and development. These results might be relevant to agriculture studies in regions of similar latitudes, especially the Nordic countries, and support the general assumption that climate change should have a positive impact on crop production at high latitudes.

The high northern latitudes (>50°) experienced a pronounced surface stilling (i.e., decline in winds) with climate change. As a drying factor, the influences of changes in winds on the date of autumn foliar senescence (DFS) remain largely unknown and are potentially important as a mechanism explaining the interannual variability of autumn phenology. Using 183,448 phenological observations at 2,405 sites, long-term site-scale water vapor and carbon dioxide flux measurements, and 34 y of satellite greenness data, here we show that the decline in winds is significantly associated with extended DFS and could have a relative importance comparable with temperature and precipitation effects in contributing to the DFS trends. We further demonstrate that decline in winds reduces evapotranspiration, which results in less soil water losses and consequently more favorable growth conditions in late autumn. In addition, declining winds also lead to less leaf abscission damage which could delay leaf senescence and to a decreased cooling effect and therefore less frost damage. Our results are potentially useful for carbon fluxmodeling because an improved algorithm based on these findings projected overall widespread earlier DFS than currently expected by the end of this century, contributing potentially to a positive feedback to climate. [ABSTRACT FROM AUTHOR]

Abstract Afforestation is gaining popularity as a climate mitigation policy in many countries, including high latitude regions such as Norway. However, the impacts of afforestation on local‐to‐regional climate is poorly understood. This study uses the Weather Research and Forecasting model to investigate the biogeophysical impacts of different forestry scenarios on the local‐to‐regional climate of Norway. The forestry scenarios considered are the conversion of open spaces to either evergreen forest by active afforestation or to mixed forest by natural succession. Results show both forestry scenarios lead to additional warming of surface temperatures in winter and spring (between 1.0°C and 1.5°C) and cooling in summer (between −1.6°C and −1.3°C). A temperature decomposition analysis shows that the warming in winter and spring is driven by surface albedo changes while summer cooling is driven by changes in sensible heat fluxes for afforestation and surface albedo for natural succession. Maximum 2 m air temperature increases considerably in spring in both forestry scenarios (∼0.8°C to 1.0°C). Analysis of precipitation, multiple climate indices and extremes, reveal little or no response to the different forestry scenarios. The largest societally relevant response to the forestry scenarios is the partial mitigation of the reduction in snow days expected from global warming by 10–20 days. This suggests that implementing current afforestation policies for climate mitigation in Norway may adversely exacerbate some effects of global warming locally while mitigating others. As such, the impacts of afforestation on the local‐to‐regional climate at high latitudes are complex and cannot support or dismiss afforestation as a climate mitigation policy.

Abstract Global Navigation Satellite System (GNSS) signals strongly depend on the ionospheric conditions, which are composed of electrons and ions generated by solar radiation and particle precipitation. Ionospheric plasma irregularities may cause the scintillation of the GNSS signals or even the loss of signal lock, resulting in the reduction of positioning accuracy and timing precision. Phase scintillation phenomenon is known to occur frequently at high latitudes and primarily related to a significant plasma density gradient, which is due to fast plasma flows in the polar region, energetic particle precipitation in the auroral region, polar cap patches, or several instability mechanisms. Statistical studies are required to understand the characteristics of ionospheric (both phase and amplitude) scintillations at high latitudes. Here, we report the results of ionospheric scintillation measurements at Jang Bogo Station (JBS; 74.62°S, 164.22°E), located inside the polar cap region in Antarctica. The occurrence rates of ionospheric scintillations over the JBS are recorded for 2 years (2017–2018) during solar minimum conditions. The occurrence rates of amplitude scintillations increase only at lower elevation angles (below 30°), which are hard to determine whether the source is ionospheric irregularity or ambient noise such as multipath. In contrast, the occurrence rates of phase scintillations depend on the azimuth angle, season, magnetic activity, magnetic local time, and signal frequency. The results of our analysis suggest that users of the GNSS should consider these parameters to prepare for the degradation of the GNSS performance at high latitudes in the Southern Hemisphere.

Abstract High-latitude, small-scale plasma density irregularities are observed by the Advanced Land Observation Satellite 2, Phase Array type L-band Synthetic Aperture Radar-2 and the European Incoherent Scatter radar in Tromsø, Norway. Under high levels of ionization of up to approximately 300 km in height triggered by nighttime particle precipitation, high-resolution SAR images detect horizontal distributions of azimuth shifts resulting from the spatial gradients of electron density. The irregular electron density is characterized by tens of kilometers of band-like structures aligned in the east–west direction with small patch-like structures. We present a method for estimating the local change of TEC gradient and the height of ionospheric irregularities by using single-image SAR sub-band data. The results suggest that these observed structures are likely to be associated with density irregularities caused by precipitating electrons that may have been cascaded into smaller scales by plasma instability processes at F region altitudes. This study presents the first coordinated observations of high-latitude ionosphere features by using SAR satellites and incoherent scatter radar.

Afforestation is gaining popularity as a climate mitigation policy in many countries, including high latitude regions such as Norway. However, the impacts of afforestation on local‐to‐regional climate is poorly understood. This study uses the Weather Research and Forecasting model to investigate the biogeophysical impacts of different forestry scenarios on the local‐to‐regional climate of Norway. The forestry scenarios considered are the conversion of open spaces to either evergreen forest by active afforestation or to mixed forest by natural succession. Results show both forestry scenarios lead to additional warming of surface temperatures in winter and spring (between 1.0°C and 1.5°C) and cooling in summer (between −1.6°C and −1.3°C). A temperature decomposition analysis shows that the warming in winter and spring is driven by surface albedo changes while summer cooling is driven by changes in sensible heat fluxes for afforestation and surface albedo for natural succession. Maximum 2 m air temperature increases considerably in spring in both forestry scenarios (∼0.8°C to 1.0°C). Analysis of precipitation, multiple climate indices and extremes, reveal little or no response to the different forestry scenarios. The largest societally relevant response to the forestry scenarios is the partial mitigation of the reduction in snow days expected from global warming by 10–20 days. This suggests that implementing current afforestation policies for climate mitigation in Norway may adversely exacerbate some effects of global warming locally while mitigating others. As such, the impacts of afforestation on the local‐to‐regional climate at high latitudes are complex and cannot support or dismiss afforestation as a climate mitigation policy. Plain Language Summary: The conversion of existing open spaces such as grasslands and shrublands to forests is gaining popularity as a climate mitigation policy in many countries, including high latitude regions such as Norway. However, the impacts of such afforestation policies on the local‐to‐regional climate is poorly understood, particularly at high latitudes. This study uses a state‐of‐the‐art regional climate model to show that at high latitudes afforestation warms surface (or skin) temperature in winter and spring (between 1.0°C and 1.5°C) and cooling in summer (between −1.6°C and −1.3°C). This study also shows that afforestation considerably increases the maximum 2 m air temperature in spring (∼0.8°C to 1.0°C) but has no impact on precipitation, multiple climate indices, and extremes. The largest societally relevant response to the forestry scenarios is the partial mitigation of the reduction in snow days expected from global warming by 10–20 days. This suggests that implementing current afforestation policies for climate mitigation in Norway may adversely exacerbate some effects of global warming locally while mitigating others. As such, the impacts of afforestation on the local‐to‐regional climate at high latitudes are complex and cannot support or dismiss afforestation as a climate mitigation policy. Key Points: Impacts of land use and land cover changes on temperature and snow are localized and most pronounced in springTemperature response to land use and land cover changes is largely independent of forestry scenario in these experimentsAfforestation enhances surface warming under RCP8.5 but mitigates other impacts [ABSTRACT FROM AUTHOR]

Global Navigation Satellite System (GNSS) signals strongly depend on the ionospheric conditions, which are composed of electrons and ions generated by solar radiation and particle precipitation. Ionospheric plasma irregularities may cause the scintillation of the GNSS signals or even the loss of signal lock, resulting in the reduction of positioning accuracy and timing precision. Phase scintillation phenomenon is known to occur frequently at high latitudes and primarily related to a significant plasma density gradient, which is due to fast plasma flows in the polar region, energetic particle precipitation in the auroral region, polar cap patches, or several instability mechanisms. Statistical studies are required to understand the characteristics of ionospheric (both phase and amplitude) scintillations at high latitudes. Here, we report the results of ionospheric scintillation measurements at Jang Bogo Station (JBS; 74.62°S, 164.22°E), located inside the polar cap region in Antarctica. The occurrence rates of ionospheric scintillations over the JBS are recorded for 2 years (2017–2018) during solar minimum conditions. The occurrence rates of amplitude scintillations increase only at lower elevation angles (below 30°), which are hard to determine whether the source is ionospheric irregularity or ambient noise such as multipath. In contrast, the occurrence rates of phase scintillations depend on the azimuth angle, season, magnetic activity, magnetic local time, and signal frequency. The results of our analysis suggest that users of the GNSS should consider these parameters to prepare for the degradation of the GNSS performance at high latitudes in the Southern Hemisphere. Key Points: Occurrence rates of ionospheric scintillation indices at high latitudes during two years from a single station are statistically analyzedOccurrence rates of phase scintillation index strongly depend on the signal frequency, geomagnetic activity, season, and magnetic local timePolar cap patch, polar cusp, field‐aligned currents, and auroral oval are strongly related to the climatology of phase scintillation index [ABSTRACT FROM AUTHOR]