Annual Temperature Difference Research Articles

Effects of Disparate Water Temperatures and Food Bases on Humpback Chub Growth Rates within the Little Colorado River, Arizona

AbstractWe used translocation as a conservation measure to promote the recovery of an endangered freshwater fish species. We collected juvenile Humpback Chub Gila cypha from the lower 9.6 km of the Little Colorado River (LCR), Arizona, and translocated them upriver above a natural travertine structure called Chute Falls where the species was absent. The translocated fish were released at river kilometer (RKM) 16.2 above the mouth of the LCR. We measured growth rates across 14 size‐classes of Humpback Chub in three contiguous reaches of the LCR. Growth rates were usually highest in the 3.8‐km‐long reach above Chute Falls (translocation reach), slightly lower in a short 0.53‐km reach immediately below Chute Falls (Atomizer reach), and lowest in the lower 13.57 km of the LCR (lower reach). Most base flow of the LCR originates from relatively warm springs (20.6–22.8°C) that are located upriver from the translocation release site. The grand mean annual water temperature differences across eight years averaged 1.1°C/d warmer at RKM 16.2 than at RKM 1.05 and reflected a higher correlation to the growth rates of Humpback Chub in the translocation reach than in the lower reach. Moreover, this and other studies found that Humpback Chub's food base of prey fishes was also higher in the translocation reach than in the lower reach. High growth rates of juvenile Humpback Chub in the translocation and Atomizer reaches resulted in most reaching adulthood (200 mm TL) by age 2, a year earlier than most Humpback Chub in the lower reach did. Because higher growth rates of Humpback Chub in the translocation and Atomizer reaches provide a substantial head start for adult reproduction to commence, we suggest that translocating juvenile Humpback Chub to above Chute Falls is a management action that enhances recovery efforts of Humpback Chub in Grand Canyon, potentially at the population level.

<p><strong>The endemic and range restricted vascular plants of Croatia: diversity, distribution patterns and their conservation status</strong></p>

The Balkan Peninsula is recognized as an important centre of native and endemic plant species diversity as well as an important wildlife refuge area. However, although Croatia hosts more than half of plant species found on the Balkan Peninsula, the endemic taxa have never been evaluated or used to define conservation priorities. We analyzed the qualitative composition of the endemic and range restricted species, their spatial distribution, centres of endemism, and conservation status (non-IUCN). We generated an updated and annotated checklist of 349 endemic or range-restricted plant taxa (6.9% of the entire native flora), subdivided in 231 species, 103 subspecies and 15 hybrids and belonging to 149 genera and 43 families. Among the 231 species, 69 are considered endemic to Croatia and confined to a small area (< 4,500 km2), while 162 are considered range restricted species, which have larger ranges and/or are shared with neighbouring countries. The genera Centaurea and Hieracium have the highest number of endemic and range restricted taxa. Spatial analyses indicated two notable centres of species richness—the mountainous Dinaric Alps and the SE Adriatic coast, including the islands. Regions with a high richness of range-restricted taxa did not coincide with areas of high richness of endemic species. Taxa exhibited modest bimodality with respect to altitudinal distribution. In addition, the greatest diversity of taxa is concentrated in northwest of Croatia and could be related to differences in mean annual air temperatures and the duration of insolation. As regards their conservation status, 13 of the 349 taxa are endangered, and 62 are near threatened or vulnerable. Despite relatively strong legal protection of endemic and range restricted species, 37 taxa remain unprotected. Changes in conservation practice are therefore proposed.

Radiometric Stability of the SABER Instrument

AbstractThe SABER instrument on the National Aeronautics and Space Administration Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics satellite continues to provide a long‐term record of Earth's stratosphere, mesosphere, and lower thermosphere. The SABER data are being used to examine long‐term changes and trends in temperature, water vapor, and carbon dioxide. A tacit, central assumption of these analyses is that the SABER instrument radiometric calibration is not changing with time; that is, the instrument is stable. SABER stratospheric temperatures and those derived from Global Positioning System Radio Occultation measurements are compared to examine SABER's stability. Global Positioning System Radio Occultation measurements are inherently stable due to the accuracy and traceability of the measured phase delay rate to the Système Internationale definition of the second. Differences in global annual mean SABER and COSMIC lower stratospheric temperatures show little significant change with time in the 11 years spanning 2007–2017. From this analysis we infer that SABER temperatures are stable to better than 0.1 to 0.2 K per decade.

Transcriptomic evidences of local thermal adaptation for the native fish Colossoma macropomum (Cuvier, 1818).

Brazil has five climatically distinct regions, with an annual average temperature difference up to 14 ºC between the northern and southern extremes. Environmental variation of this magnitude can lead to new genetic patterns among farmed fish populations. Genetically differentiated populations of tambaqui (Colossoma macropomum Cuvier, 1818), an important freshwater fish for Brazilian continental aquaculture, may be associated with regional adaptation. In this study, we selected tambaquis raised in two thermally distinct regions, belonging to different latitudes, to test this hypothesis. De novo transcriptome analysis was performed to compare the significant differences of genes expressed in the liver of juvenile tambaqui from a northern population (Balbina) and a southeastern population (Brumado). In total, 2,410 genes were differentially expressed (1,196 in Balbina and 1,214 in Brumado). Many of the genes are involved in a multitude of biological functions such as biosynthetic processes, homeostasis, biorhythm, immunity, cell signaling, ribosome biogenesis, modification of proteins, intracellular transport, structure/cytoskeleton, and catalytic activity. Enrichment analysis based on biological networks showed a different protein interaction profile for each population, whose encoding genes may play potential functions in local thermal adaptation of fish to their respective farming environments.

A climate-architecture modeling to explore the effect of land use change scenario on building bioclimatic design pattern in order to provide human thermal comfort.

Given the role of different land uses in climate change, the present study seeks to identify the effect of land use change on the building bioclimatic design pattern in a dry climatic type. For this purpose, Yazd station in central regions of Iran has been analysed as a representative of dry climate type. The Air Pollution Modelling (TAPM) which is a regional climate software was used to identify the effect of forest cover on climate change in regional dimensions and finally its impact on heating and cooling solutions for buildings. For this study, two scenarios were considered. One scenario was the real situation in the area and the other one was the simulation of the effect of forest cover on climate change in the studied area. Finally, the results of this study revealed that if there is a forest cover, due to the temperature increase in all months of the year, the average annual temperature will increase by 9.20°C compared to the real conditions. On the other hand, in the forest cover simulation scenario, the relative humidity will increase by 13.4% per year. The findings also showed that, despite forest cover, the annual temperature difference and temperature fluctuations are reduced by 4°C. Furthermore, the results of this study indicated that if there is a forest cover, the heating requirements will be reduced in total and the demand for the bioclimatic design of cooling and dehumidification will be increased.

Insights into the Distribution Patterns, Habitat and Morphologic Differentiation of Cryptic Species of the Moss Hamatocaulis vernicosus in the Czech Republic

Manukjanová, A., Kouteckí, P., Štechová, T. & Kučera, J. 2019. Insights into the distribution patterns, habitat and morphologic differentiation of cryptic species of the moss Hamatocaulis vernicosus in the Czech Republic. – Herzogia 32: 183–199.We studied local distribution, morphological and ecological differences between the two cryptic species of Hamatocaulis vernicosus in the Czech Republic. Distribution was assessed at both regional scale and within localities using several barcoding methods including direct sequencing and PCR-RFLP of ITS region of nrDNA, as well as amplification of clade-specific SSR markers. The lineage known as clade 1 occurs on more than 90 % of the 70 investigated Czech localities, while clade 2 occurs at only about 10 % of localities, which moreover mostly support plants of both clades. Analysis of ITS sequences from Czech samples showed considerable variability in clade 1, while plants of clade 2 were invariable. Comparison of climatic characteristics did not reveal any significant differences in mean annual temperature, precipitation and frost days between localities of both clades, although clade 2 plants tends to grow at higher elevations. Statistical evaluation of morphometric data has not revealed any character which would morphologically distinguish plants of both clades.

Effects of artificial warming on stem radial changes in Qinghai spruce saplings in the Qilian Mountains of China

Climate change has been documented in the Qilian Mountains of China, and the response of tree stem growth to environmental factors may be changed, affecting regional estimates of seasonal growth patterns and carbon sequestration. The objective of this study was to provide initial evidence for responses of intra-annual tree stem radial changes of sapling Qinghai spruce (Picea crassifolia) to climate warming in the Qilian Mountains. We monitored stem radial changes of Qinghai spruce in an open-top chamber (OTC) and out of chamber (OC) over three growing seasons (2014–2016) using high-resolution point dendrometers. Statistical analysis indicated that the differences in annual average air temperature between OTC and OC were about 1 °C. Our results showed that the onset of the main growth period in OTC was about one week earlier than in OC, and soil temperature played an important role in controlling the onset of growth in sapling Qinghai spruce. However, the timing of radial growth cessation exhibited large variability in different growth conditions. These results indicated that the end of growth may not be related to environmental factors. Daily average air temperature, vapor pressure deficit, relative air humidity, and precipitation were significantly correlated with daily stem radial increment (SRI) and tree water deficit (TWD). Further, soil water content and TWD were also correlated. SRI in OTC was larger than that in OC, while TWD exhibited no significant differences between the two growth conditions. However, cumulative seasonal growth may not be influenced by air temperature alone, but by interacting environmental factors.

Evaluation and spatial distribution characteristics of freeze-thaw erosion intensity in the Yalu Tsangpo River basin on the basis of geographic information system

Freeze-thaw erosion is one of the main ways of soil erosion in three major erosion types, which are related to the development of regional economy and the protection of ecological environment. Therefore, its research is particularly important. This paper uses the Yalu Tsangpo River basin as the research area. The range of the freeze-thaw erosion area in the Yalu Tsangpo River basin was defined by using Shuttle Radar Topography Mission-Digital Elevation Model (STRM-DEM) data. Six factors, namely, annual temperature difference, annual precipitation, slope, aspect, vegetation coverage, and elevation, were selected as the evaluation indexes of the intensity of freeze-thaw erosion. Analytic hierarchy process (AHP) was used to determine the weight of each factor. A comprehensive evaluation index model was employed to obtain the range of freeze-thaw erosion intensity. The natural breaks method in ArcGIS was applied to grade the result. The classification chart of the freeze-thaw erosion intensity of the Yalu Tsangpo River basin was drawn to show the distribution of freeze-thaw erosion. Results showed that (1) the total area of freeze-thaw erosion in the Yalu Tsangpo River basin is 229,231.80 km2, which accounts for 93.5% of the total area of the Yalu Tsangpo River basin, with mild erosion and moderate erosion. (2) The distribution of freeze-thaw erosion intensity in spatial pattern is obvious; from west to east, the intensity of freeze-thaw erosion increases gradually. Severe erosion is mainly concentrated in the northeast and northern regions of the Yalu Tsangpo River basin. (3) The areas of freeze-thaw erosion are mainly distributed in the temperature zone with the annual temperature range of ≥40 °C, accounting for 86.4% of the total freeze-thaw erosion area. The freeze-thaw erosion area is mainly distributed in the slope ≥15° slope zone, which accounts for 62% of the total freeze-thaw erosion area, and has a severe effect on moderate erosion and severe erosion in this slope zone. Freeze-thaw erosion areas are mainly concentrated in vegetation belts with vegetation coverage less than 20%, accounting for 63.8% of the total freeze-thaw erosion area. With the increase in vegetation coverage, the proportion of freeze-thaw erosion area decreased. The freeze-thaw erosion area was mainly concentrated on the altitude zone of ≥4000 m, which accounted for 84.3% of the total freeze-thaw erosion area. Thus, the freeze-thaw erosion area increased with altitude.

Badania klimatu miejskiego w Toruniu prowadzone przez Katedrę Meteorologii i Klimatologii UMK – zarys historii i uzyskanych wyników

The article presents the history of research into the urban climate of Toruń initiated and conducted by the Department of Meteorology and Climatology of Nicolaus Copernicus University. Two periods of intensive research on the subject were identified: 1981–1993 and 2011–present. In the first period, measurements were taken at a significantly smaller number of points and covered a narrower scope than in the second period. The measuring equipment was also significantly different, with mercury thermometers and drum recorders (thermohygrographs) being used in the first period, and automatic meteorological stations in the second. Results from both periods, specifically from 1982 and 2012, confirmed the existence of an urban heat island (UHI) and significant differences in the spatial distribution of air humidity. In both analysed periods, differences in mean annual temperature and air humidity between the city centre and the reference station were about 1°C and 7%, respectively. The lack of changes in UHI intensity and spatial distribution of air humidity between the analysed years can be explained by the lack of significant changes in the development of Toruń’s Old Town.

편의보정된 다중지역기후모델 산출물의 불확실성 범위 추정 및 미래 전망

In this study, uncertainty ranges for bias-corrected temperature and precipitation in seven metro-cities were estimated using nine GCM-RCM Matrix, and climate changes were predicted based on the corrected temperature and precipitation. During the present climate (1981-2005), both uncertainties for annual temperature and precipitation and differences in regional uncertainties were reduced by bias correction methods. Model’s systematic errors such as cold bias of surface air temperature and underestimated precipitation during the second-Changma period were improved by a bias correction method. Uncertainties of annual variations for bias corrected temperature and precipitation were also decrease. Furthermore, not only mean values but also extreme values were improved by bias correction methods. During the future climate (2021-2050), differences in temperature and precipitation between two RCP scenarios (RCP4.5/8.5) were not quite large. Temperature had an obvious increasing tendency, while future precipitation did not change significantly compared to present one in terms of mean values. Uncertainties for future biascorrected temperature and precipitation were also reduced. In mid-21st centuries, models prospected that mean temperature increased thus lower extremes associated with cold wave decreased and upper extremes associated with heat wave increased. Models also predicted that variations of future precipitation increased thus the frequency and intensity of extreme precipitation increased.

Forecasting peak electricity demand for Los Angeles considering higher air temperatures due to climate change

Los Angeles County (LAC) is a large urbanized region with 9.7 million residents (as of 2010) and aging infrastructure. Population forecasts indicate that LAC will become home to an additional 1.2–3.1 million residents through 2060. Additionally, climate forecasts based upon representative concentration pathway (RCP) scenarios 4.5 and 8.5 indicate that average air temperatures will increase by 1–4 °C (2–7 °F) in the region. Both of these factors are expected to result in higher summertime peak electricity demand due to growth in the number of buildings, the percentage of installed air conditioners (ACs), and the additional cooling load on those air conditioners. In order to understand potential power reliability issues, and support infrastructure planning efforts, a long-term peak demand forecast was developed using hourly residential and commercial (R&C) building energy models. Peak hour electricity demand was estimated to increase from 9.5 to 12.8 GW for R&C sectors, to 13.0–17.3 GW (2–36%) and 14.7–19.2 GW (16–51%) by 2060 for the population forecasts from the California Department of Finance and the Southern California Association of Governments respectively. While marginal increases in ambient air temperature due to climate change accounted for only 4–8% of future increases in peak demand, differences in annual maximum temperatures within the 20-year periods affected results by 40–66% indicating a high sensitivity to heat waves. Population growth of at least 1 million people is anticipated to occur mostly in the northern cities of Palmdale, Lancaster, and Santa Clarita, bringing an additional 0.4–1 GW of peak demand in those regions. Building and AC efficiency are anticipated to improve as national and state efficiency standards increase, and as older, less efficient units are replaced; this could offset some of the projected increases in peak demand. Additionally, development of shared wall, multi-family dwelling units could enable population growth of up to 3 million people without increasing peak demand.

The establishment of hybrids of the Daphnia longispina complex explained by a mathematical model incorporating different overwintering life history strategies.

Interspecific hybridization (i.e. mating between species) occurs frequently in animals. Among cyclical parthenogens, hybrids can proliferate and establish through parthenogenetic reproduction, even if their sexual reproduction is impaired. In water fleas of the Daphnia longispina species complex, interspecific hybrids hatch from sexually produced dormant eggs. However, fewer hybrid genotypes contribute to the dormant egg bank and their hatching rate from dormant eggs is reduced, compared to eggs resulting from intraspecific crosses. Therefore, Daphnia hybrids would benefit from adaptations that increase their survival over winter as parthenogenetic lineages, avoiding the need to re-establish populations after winter from sexually produced dormant eggs. Here, we constructed a mathematical model to examine the conditions that could explain the frequently observed establishment of hybrids in the D. longispina species complex. Specifically, we compared the outcome of hybrid and parental taxa competition given a reduced contribution of hybrids to hatchlings from the sexually produced dormant egg bank, but their increased ability to survive winter as parthenogenetic lineages. In addition, different growth rates of parental species and differences in average annual temperatures were evaluated for their influence on hybrid production and establishment. Our model shows that increased overwinter performance as parthenogenetic females can compensate for reduced success in sexual reproduction, across all tested scenarios for varying relative growth rates of parental species. This pattern holds true for lower annual temperatures, but at higher temperatures hybrids were less successful. Consequently, hybrids might become less abundant as temperatures rise due to climate change, resulting in reduced diversity and faster differentiation of the parental species.

Adaptive genetic potential of European silver fir in Romania in the context of climate change

Five provenance tests with twenty-six European silver fir autochthonous populations were used in order to assess the response of populations to climate change. Height growth and diameter at breast height of trees at age 31 years were considered as response variables and eight climate variables as predictors. Climatic variables for the trial sites and for origin location of provenances were calculated from 1961 to 2010. The experiments revealed a large genetic variability within species level and a plastic response to climate change, which certainly has a genetic basis. The transfer to warmer climate has resulted in an increase of the provenances growth, in the trial sites situated on the lower vegetation layer. But growth is significantly influenced by mean annual temperature and annual precipitation of planting site and also by the differences in mean annual temperature, annual precipitation, monthly mean temperature in July and July precipitation between provenance site and test site. These are the climatic factors which should be associated with risk in case of the transfer of forest reproductive materials. The provenance origin should be especially considered if the species will be planted outside of its current climate optimum. The best provenances in terms of total height and diameter at 1.30 m came from origin climate close to site climate, small transfer distances. Based on growth response functions and RCP4.5 scenario, we could project the shifts in species distribution for 2050s and 2100s and identify vulnerable populations.

Variability in mean size of phytoplankton in two floodplain lakes of different climatic regions

Phytoplankton size has an important functional role in ecosystem processes, such as nutrient production and cycling. It has been suggested that warmer temperatures may favor the smaller organisms in biological communities. We evaluate the mean size of the phytoplankton organisms and apply a morphology-based functional groups (MBFG) approach. We use time series of two floodplain lakes that present mean annual temperature difference of 10°C and similar hydrodynamic, area, and mean depth. We expected that a smaller mean size of MBFGs would be associated with higher temperatures. The Akaike Information Criterion was used to investigate environmental factors predicting the mean size of MBFGs within each lake. The mean size was most associated to nutrients and dissolved oxygen in the subtropical lake, and to temperature in the temperate lake. Large filaments with aerotopes and the small flagellated with siliceous exoskeletal structures showed high mean size at higher temperatures, thus contradicting temperature–size rules. Probably the high variability of mean size was provided by the high variability observed around environmental factors. Our findings reveal that other functional traits may be associated with the phytoplankters mean size, which result in adaptation to high variability of various environmental factors.

The urban heat island and the features of the flora in the Lublin City area, SE Poland

Various forms of human activity in large cities contribute to the creation of a specific climate and new environmental conditions for plants. One of the most important results is the so-called atmospheric urban heat island (UHI). The aim of this study was to compare the thermal conditions in the Lublin City center with those of suburban areas, and so confirm the existence of the UHI and then analyze the influence of thermal conditions on features of the flora. The analysis of the air temperatures was based on data from 2000 to 2014 provided by meteorological stations in the Lublin City center and its nearest surroundings. Floristic data were collected during field studies between 2012–2014 and included species richness and frequency, life forms, and synecological groups of the flora and its elements. The thermal requirements of species were defined on the basis of ecological indicator values (EIVs). Our research confirmed the presence of the UHI in the Lublin City center. Over the study period, the mean temperature in the city center was by 0.87°C higher than that in the suburban areas. The largest differences in mean annual air temperature between the city center and the suburbs were recorded in 2007 and 2011–2013. In total, 552 species were recorded, including six life-form and synecological groups, 246 thermophilous and 436 heliophilous species. The species richness, proportion of therophytes, alien, thermo- and heliophilous species decreased with distance from the city center. The thermal conditions expressed by the EIV L and T ranged from L = 4.5, T = 3.8 in the city center, to L = 3.1, T = 3.4 in the suburbs. An ordination analysis facilitated determination of the relationships between characteristics of the flora, the EIV values, and land use classes. An increasing level of anthropopressure was found to be positively correlated with thermal conditions and the flora traits.

Refuge behaviour from outdoor thermal environmental stress and seasonal differences of thermal sense in tropical urban climate

Thermal sensation affects body temperature regulation. As a starting point for behavioral body temperature regulation taken to improve from a poor thermal environment to a more pleasant environment, thermal sense of thermal environment stimulus is important. The poupose of this sutudy is to use the outdoor thermal environment evaluation index ETFe to quantify effects on thermal sensations of the human body of a tropical region climate with small annual temperature differences, and to examine seasonal differences in thermal sensation. It was found temperature preferences were lower in the winter season than in the dry season, and that a tolerance for higher temperatures in the dry season than in the winter season. It was found effects of seasonal differences of the thermal environment appear in quantitative changes in thermal sensations. It was found that effects of seasonal differences of the thermal environment do not greatly affect quantitative changes in thermal comfort.

Identification of Floral Relicts Based on Spatial Distance of Isolation

The identification of climatic relicts is seldom straightforward. These species are threatened owing to current climatic trends, which underlines the importance of carrying out ecological and biogeographic investigations of them. Here we introduce a novel approach to improve the identification of climatic relicts. We are focusing on thermophilic relict plants of the Pannonian biogeographic region from the Holocene Thermal Maximum (HTM). We argue that a minimal mean annual temperature difference (MATD) of the HTM compared to the recent climate allowed a continuous northward expansion for the taxa investigated. We measured latitudinal distances between the recent occurrences of relicts and those of the main distribution found further south. Regarding estimates for MATD (1.0–2.5 °C), we only consider species with a distribution which has a 150–350 km North-South gap, since a latitudinally directed distance can be translated into temperature, showing a poleward cooling trend. Of the 15 selected species, 12 were recorded with values of 1.0–1.7 °C MATD, and three with values of 1.8–2.5 °C, some of which are presumably interglacial species. Woody species are over-represented among them (four species), using the Hungarian flora as a reference. The proposed method allows the prediction of potential climate-related changes in the future distribution of species, constrained by the topographic features of their habitats.

A diagnostic method for evaluating the condition index of cement-stabilised base using T-S fuzzy neural network

This paper presents a novel diagnostic model for evaluating the damage condition of a cement-stabilised base course using a T-S fuzzy neural network (FNN). An evaluation criterion for core damage rating, base core condition index (BCCI), was established based on the distress features observed in 369 core samples that had been collected from asphalt concrete pavements with cement-stabilised base courses. The core samples of cement-stabilised macadam (CSM) were classified into five levels according to the evaluation criterion. Ten parameters were chosen as inputs to establish non-linear mapping relationships in an FNN model. These input parameters include pavement distresses’ characteristics (crack depth, breadth and lumpiness), Pavement Surface Condition Index (PCI), Riding Quality Index (RQI), Pavement Structure Strength Index (PSSI), Cumulative Equivalent Single Axle Loads (ESALs), thickness of asphalt concrete (AC) layers, annual temperature difference and average annual precipitation. Out of the 369 samples, 169 field cores were used in the FNN model for recursive training, and the parameters for the neural network structure were optimised until the errors between the network outputs and the expected outputs were minimised. The established FNN model was then used for the calculations of predicted quantitative results for remaining sections. The calculation results showed the logical reasoning capability of the T-S fuzzy system and the quantitative data processing capability of the neural network (NN). The comparisons between the objectively predicted results with the subjectively evaluated scores of the testing samples showed a prediction accuracy of 88.4%. The objectively predicted results calculated by the FNN model were also compared with the measurements taken using a Ground Penetrating Radar (GPR). The two groups of results showed reasonable similarity, which again indicated the effectiveness of the developed FNN method.

Anti-icing of road surfaces using Hydronic Heating Pavement with low temperature

A traditional method to mitigate slippery conditions on a road surface is to spread out sand and salt. This method results in corrosion of the road infrastructures and damage to surrounding vegetation. A renewable alternative method for anti-icing the road surface is to use a Hydronic Heating Pavement (HHP). The HHP consists of embedded pipes in the road. A fluid as thermal energy carrier circulates through the pipe. The energy is harvested in summer and saved in seasonal thermal energy storages. The harvested energy, as the only source of energy, is released in winter for snow/ice melting. The aim of this study is to investigate the anti-icing performance of the HHP system during cold periods. A two-dimensional numerical model was developed to investigate how different design options, such as distance between the pipes, affect the efficiency of the HHP systems. The annual required energy for anti-icing and remaining hours of the slippery conditions on the road surface were numerically calculated using a finite element model. The numerical model was validated for two cases: (i) for a road without pipes using a one year measured data of an existing road and (ii) for a road with embedded pipes using an analytical solution. The validation results for a road without pipes showed that the mean annual temperature difference of the road surface is 0.28°C with standard deviation of 3.53°C between the measured data and numerical calculation. The validation results for the road with embedded pipes showed that the maximum relative error associated with the thermal resistance between the pipes and surface is less than 1% between the numerical model and the analytical solution. In order to investigate the anti-icing performance of the HHP system, the climate data from Östersund, an area in middle of Sweden, were selected. The results revealed that the anti-icing performance of the HHP system improves when the pipes are placed closer, the depth of embedded pipes is reduced, large pipe sizes are used and when the road surface has a lower emissivity value. Among all options, the distance between pipes has the most significant effect on improving the anti-icing performance, so changing the pipe distances from 400mm to 50mm results in approximately four times shorter hours of the slippery conditions on the road surface.

Electricity demand planning forecasts should consider climate non-stationarity to maintain reserve margins during heat waves

Climate non-stationarity is a challenge for electric power infrastructure reliability; recordbreaking heat waves significantly affect peak demand [1], lower contingency capacities, and expose cities to risk of blackouts due to component failures and security threats. The United States’ electric grid operates safely for a wide range of load, weather, and power quality conditions. Projected increases in ambient air temperatures could, however, create operating conditions that place the grid outside the boundaries of current reliability tolerances. Advancements in long-term forecasting, including projections of rising air temperatures and more severe heat waves, present opportunities to advance risk management methods for long-term infrastructure planning. This is particularly evident in the US Southwest—a relatively hot region expected to experience significant temperature increases affecting electric loads, generation, and delivery systems. Generation capacity is typically built to meet the 90th percentile (T90) hottest peak demand, plus an additional reserve margin of least 15%, but that may not be sufficient to ensure reliable power services if air temperatures are higher than expected. The problem with this T90 planning approach is that it requires a stationary climate to be completely effective. In reality, annual temperature differences can have more than a 15% effect on system performance. Current long-term infrastructure planning and risk management processes are biased climate data choices that can significantly underestimate peak demand, overestimate generation capacity, and result in major power outages during heat waves.This study used downscaled global climate models (GCMs) to evaluate the effects of non-stationarity on air temperature forecasts, and a new high-level statistical approach was developed to consider the subsequent effects on peak demand, power generation, and local reserve margins (LRMs) compared to previous forecasting methods. Air temperature projections in IPCC RCPs 4.5 and 8.5 are that increases up to 6°C are possible by the end of century, with highs of 58°C and 56°C in Phoenix, Arizona and Los Angeles, California respectively. In the hottest scenarios, we estimated that LRMs for the two metro regions would be on average 30% less than at respective T90s, which in the case of Los Angeles (a net importer) would require 5GW of additional power to meet electrical demand. We calculated these values by creating a structural equation model (SEM) for peak demand based on the physics of common AC units; physics-based models are necessary to predict demand under unprecedented conditions for which historical data do not exist. The SEM forecasts for peak demand were close to straight-line regression methods as in prior literature from 25–40°C (104°F), but diverged lower at higher temperatures. Power plant generation capacity derating factors were also modeled based on the electrical and thermal performance characteristics of different technologies. Lastly, we discussed several strategic options to reduce the risk of LRM shortages; including implementing technology, market incentives, and urban forms that reduce peak load and load variance per capita as well as their tradeoffs with several other stakeholder objectives.