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At specified depths, ground temperature remains almost constant at 15°C, above atmospheric temperatures in winter and below those in summer. Ground thermal energy systems technology circulates water or brine through a heat‐collection tube buried underground and uses the ground thermal energy for air conditioning. However, depending on the facility, the total length of the heat‐collection tube can be several hundred meters. As a result, the pump can require significant electric power. In this study, we adopted a drag‐reduction technique using a cationic surfactant and a counter‐ion system. The optimal addition conditions of additives were investigated with a laboratory‐grade device. We also investigated corrosion inhibitors that do not interfere with the drag‐reduction effect. According to demonstration tests using practical ground thermal energy systems at two locations in Japan, we found that pump power consumption could be reduced by 10%–20% with suitable additive conditions. [ABSTRACT FROM AUTHOR]

Although feeding damage caused by black sea bream Acanthopagrus schlegelii has become severe in the nori Neopyropia yezoensis cultivation industry, the behavioral ecology of black sea bream in nori farms remains unclear. In this study, we monitored black sea bream around a nori farm using acoustic telemetry in order to understand the behavioral characteristics of this species. Of the 23 fish specimens tagged with acoustic transmitters, 18 fish were traced over periods > 100 days, with 8 fish considered to be feeding on cultivated nori. It is thought that the black sea bream, which were inferred to have been feeding on nori, exhibited periodicity in their behavior, feding on cultivated nori near the water surface during the day and settling on the seafloor or around seabed structures during the night. Furthermore, the feeding on nori gradually lessened when the water temperature in the cultivation grounds fell below 13 °C. Some methods aimed at reducing feeding damage are proposed that take advantage of the diurnal behavior of black sea bream to catch individuals around nori sets with gill nets or set nets during the season when the water temperature exceeds 13 °C. [ABSTRACT FROM AUTHOR]

At active volcanoes, the surface temperature and its spatial distribution can indicate changes in the underlying magmatic and hydrothermal system. Surface temperature monitoring has been widely performed using thermal remote sensing with thermal infrared (TIR) cameras. One of the drawbacks of this method is that the unknown viewing orientation of TIR images inhibits quantitative evaluations of the spatial extent and distributions of thermal anomalies. Therefore, many studies have performed 3D temperature-field reconstructions by processing TIR images photogrammetrically. However, these studies have not included the correction of TIR wave atmospheric attenuation and viewing-angle variation in emissivity in the reconstruction procedure, which can result in significant temperature misestimation. We propose a simple method that incorporates the correction into the reconstruction process, which can improve the estimation of surface temperature, especially in rugged terrains. We demonstrate our method for the active crater of Aso volcano in Japan. We create digital elevation models by applying the Structure from Motion–Multi-view Stereo algorithm to aerial visible images taken at the same time as the TIR images and then project the TIR images onto the DEM with the direct georeferencing method. The correction is carried out using the geometric parameters acquired in the process. We create 1-m resolution orthorectified thermal images of the crater on two separate dates (18 August 2020 and 16 March 2022) and calculate the heat discharge rates from steaming grounds and a volcanic lake. We find that the heat discharge rate from the fumarolic field on the south crater wall showed a sevenfold increase after the phreatic explosions that occurred on 14 and 20 October 2021. [ABSTRACT FROM AUTHOR]

This work introduces a pilot-scale experiment conducted for 18 months to study the soil heating performance of solar collectors in Japan for borehole thermal energy storage and thermal consolidation applications. In this experiment, water was heated using a solar collector and then circulated in three heat exchangers inserted into a 2.63-m3 box of kaolin clay installed in sandy ground. The solar collector had a heat collection area of 4 m2 and was attached to a 200-L water tank. The tank containing the clay was internally lined by a 6-cm-thick box of polyethylene foam to reduce heat exchange with the environment. The average clay temperature reached a maximum value of 41.1°C in the summer and a minimum of 14.9°C in the winter. The circulation water temperature varied seasonally between a daytime maximum of 77.5°C in summer and a daytime minimum of 22.5°C in winter. The experiment was simulated using a finite-element analysis model based on thermal conduction. The model used the Dittus–Boelter equation to model the heat exchangers' energy output and adopted an environmental heat exchange boundary condition using ambient temperature, wind speed, and total daily solar flux data. The numerical results accurately predicted the ground and average kaolin temperature within a 2°C–3°C margin of error. The numerical and experimental spatial distributions of kaolin temperature suggest that gravity and temperature-induced moisture transport was sufficient to measurably change the kaolin water content. Additionally, the numerical results of the sandy ground temperature revealed its sensitivity to variation of moisture content induced by evapotranspiration. Last, changing the boundary condition of the kaolin box to thermal insulation revealed that environmental heat loss accounted for a 13.5°C–19.5°C difference in the average kaolin temperature between the numerical and experimental results, emphasizing the importance of adequate thermal insulation in ground heating applications. [ABSTRACT FROM AUTHOR]

This study predicts the long-term performance of ground source heat pump (GSHP) systems in different climatic regions of Japan. The research model calculates the dynamic heat load of a typical Japanese building in various cities using their meteorological data, considering different schedules for heating and cooling seasons. The model aims to analyze the performance degradation of the GSHP system after 15 years of operation due to the imbalanced heating and cooling loads. Additionally, it compares ground temperature changes, coefficient of performance (COP) variations, and annual operation times based on different thermal imbalance ratios (TIR) for the case studies. The results demonstrate that TIR serves as an appropriate factor for comprehensively evaluating system aspects, including GHE length, ground temperature, and COP degradation, across various climates. It was found that ground temperatures increased by a maximum of up to 4 °C in cooling-dominated regions due to higher thermal imbalance accumulative loads, while it decreased to around 1 °C in heating-dominated regions. The model also revealed that the COP decreased in the dominant operation for each case study due to induced thermal imbalance and soil temperature change. The thermal imbalance caused the system cooling COP decreased by 0.015/year in the worst case (Okinawa City) and 0.006/year in average for other cases. (1) The climatic regions of japan and the color-coded average hourly temperature for the different cities. (2) This variety causes different cooling and heating season schedules, imbalance load, and (3) Changes the ground temperature in long-term operation. [Display omitted] [ABSTRACT FROM AUTHOR]

Sustainable methods are required to reduce the risks of thermal strain and heat-related illness without exacerbating greenhouse gas emissions. We investigated the effects of sun-shade use on safe heat exposure limit on a sunny summer day using historical climate data in Japan. We simulated a heat-acclimatised person standing at rest (metabolic heat production, 70 W·m−2) and during light work (100 W·m−2) on an asphalt pavement in the sun and sun-shade. Japan has three Köppen climate regions: tropical, temperate and cold. We analysed one city in the tropical region (24°N), three cities in the temperate region (31°N, 35°N and 39°N) and one city in the cold region (40°N). Hourly data were collected from 7 AM to 6 PM, June to September, from 2010 to 2019. The day with the longest daylight hours and the greatest solar radiation intensity was used for analysis. With sun-shade (a white polyester tarpaulin/awning), ambient temperature, global solar radiation and ground surface temperature were assumed to be 0.5°C, 45% and 6°C lower than in the sun, respectively. Sun-shade use eliminated the days with at least 1 hour exceeding safe heat exposure limit at rest in all cities. The same was observed for light work in the temperate and cold cities, although the tropical city had 2 days exceeding safe heat exposure limit during the decade. Sun-shade use on a sunny summer day can be an effective and sustainable method to reduce heat exposure hazard at rest and during light work in tropical, temperate and cold climate regions. [ABSTRACT FROM AUTHOR]

In lowland areas, carabid beetles show diurnal or nocturnal activity patterns depending on habitat type. However, the diel activity patterns of carabid beetles in alpine areas are poorly understood. We conducted fi eld studies in the alpine area of Mt. Hakusan in central Japan to determine the diel activity patterns of carabid beetles according to habitat type and ground surface temperature. Using baited pitfall traps, we collected samples every three hours over a 24-hour period in the summers of 2015 and 2016 in Pinus scrub, snowbed, and fellfield sites. In both years, the numerically dominant species were Pterostichus janoi Jedlicka, 1952 in the Pinus scrub, Bembidion sp. in the snowbed, and Bembidion sp. and Colpodes xestus (Bates, 1883) in the fellfield. Carabid beetles on alpine Hakusan showed activity patterns that varied depending on habitat type or ground surface temperature. Bembidion sp. showed diurnal activity patterns in the snowbed but nocturnal activity patterns in the fellfield when the diurnal temperature range was large. However, this species was active throughout the day and night in these habitats when the diurnal temperature range was small. By contrast, P. janoi in the Pinus scrub and C. xestus in the fellfield were mainly active nocturnally in both years, regardless of temperature fl uctuations. Because alpine areas are generally characterized by harsh and changeable climates, some alpine carabids such as Bembidion sp. are probably adapted to show versatile activity patterns in response to changeable microclimatic conditions. [ABSTRACT FROM AUTHOR]

The zero load readings of cone resistance (qc) and sleeve friction (fs) measured by a piezocone (uCPT) shift with the ambient temperature. A method of correcting the effect of temperature on uCPT measurements in seabed sediments has been proposed for the case where there is no temperature sensor in the uCPT probe. This method is based on the assumption that the "actual" profile of fs of soft shallow seabed sediments linearly increases with depth, and a rate of increase of α = 0.2 kPa/m was obtained using measured ground temperatures and fs values in seabed sediments in Isahaya Bay, Japan. An "actual" fs profile can then be constructed using the measured fs value at the shallow surface and the value of α. Using the differences between the measured and the estimated "actual" fs profiles, the ground temperature profile can be obtained, and then the effect of temperature on the uCPT measurements can be corrected. The proposed method was used for temperature corrections on uCPT measurements in Isahaya Bay, Japan. The values of undrained shear strength (su) from the temperature-corrected uCPT measurements agree well with the laboratory measured values of su using the undisturbed soil samples. [ABSTRACT FROM AUTHOR]

The climatological features of surface air temperature variations on time scales of a few minutes to 1 h were examined using 1 min data spanning a 4-year period from 917 automated stations in Japan. The temperature time series was spectrally analyzed after the application of a Gaussian high-pass filter, and the variances with periods of 64 min or less were statistically analyzed as sub-hourly temperature variations. The result obtained shows that daytime temperature variation is observed throughout the country with relatively small regional differences. The amplitudes of daytime temperature variations were larger during spring and summer than during autumn and winter and were larger under high temperature and sunny weather than under low temperature, no sunshine, and precipitation. A cross-spectral analysis of temperature and wind speed reveals that temperature peaks tend to coincide with or lag behind wind speed minima. The variation is likely to correspond to the convective motion in the mixing layer. On the other hand, the intensity of nighttime temperature variation showed a large amount of scatter among stations, with exceptionally large variations during winter at some stations in northern and eastern Japan. Nighttime temperature variation tends to be in phase with wind speed variation, with longer periods than daytime temperature variation and with more intensity under low temperature and low wind speed than under high temperature, high wind speed, and precipitation. Stations with large winter nighttime temperature variations tend to be located on a col or a slope, where the surface inversion layer is likely to be easily disturbed by any kind of atmospheric motion. [ABSTRACT FROM AUTHOR]

The Aizu volcanic region located in NE Japan is one of the Quaternary volcanic clusters resulting from the subduction of the oceanic Pacific Plate beneath the North American Plate. This volcanic region is characterised by Early Pleistocene large Shirakawa ignimbrites resulting from repeated caldera-forming eruptions and has been examined by several previous studies that established the eruptive sequence, the correlations of proximal ignimbrites with distal fall-out tephras and the eruptive history. However, the proximal sequence of ignimbrites proposed by previous studies is inconsistent with that of distal fall-out tephras, suggesting the necessity to re-examine the sequence. We present a revised stratigraphical framework of the ignimbrites included in the Nanaorezaka Formation exposed in the West Hills of the Aizu Basin, together with their petrographic description and correlations with distal fall-out tephras. From the glass chemistries and refractive indices of glass shards and phenocrysts, we identified six Early Pleistocene ignimbrites: in ascending order, the Kumado, Akai, Ashino, Nishigo, Kachikata and Ten-ei ignimbrites. In addition, the vitric widespread Kurokawa Tephra originated from a distant volcano. Four distal fall-out tephras associated with four ignimbrites (Kumado, Akai, Ashino and Kachikata) are distributed broadly in the Kanto and Niigata regions. Each combination of both the proximal and distal tephras was labelled Sr-Kmd, Sr-Aki-Kd18, Sr-Asn-Kd8 and Sr-Kc-U8, respectively. We re-examined their ages considering the stratigraphic positions of distal tephras identified in the Kanto region where calcareous nannofossil bio-stratigraphic and magneto-stratigraphic frameworks were available and many radiometric ages have been determined: Sr-Kmd (1.542–1.504 Ma), KK (1.533–1.485 Ma), Sr-Aki-Kd18 (1.522–1.460 Ma), Sr-Asn-Kd8 (1.219 Ma) and Sr-Kc-U8 (0.922–0.910 Ma). In addition, we estimated the volume of each fall-out tephra for Sr-Kmd, Sr-Aki-Kd18, Sr-Asn-Kd8 and Sr-Kc-U8 to be approximately 23 km 3 . It is concluded that the total volume of each eruptive event, except the Ten-ei eruption, ranges between 38 km 3 and 173 km 3 . This indicates that these eruptions can be classified as VEI 6–7. The total volume of the Shirakawa ignimbrite and its associated fall-out tephra is 498 km 3 (DRE: 199 km 3 ). In addition, we estimated the eruption rate of the tephra associated with caldera-forming eruptions during the period from the Sr-Kmd to Sr-Kc-U8 eruptions to be 0.3 km 3 /kyr in DRE, an average value for the Quaternary volcanoes in the area of the Japanese Islands. The four repose periods between the successive eruptions were variable, ranging from approximately 0.3 My to less than 0.08 My. [ABSTRACT FROM AUTHOR]

An extremely long ice pellet event with extensive episodic ice pellet falls occurred over northern Japan on 10 April 2005. The synoptic-scale environmental features of this event were examined based on Japan Meteorological Agency (JMA) mesoscale model (MSM) datasets. Asynoptic-scale dry environment was formed under the melting layer ahead of the surface warm front by an intense secondary circulation. Back-trajectory analysis suggested that dry air was located to the south of the precipitating area and was conveyed to the precipitating area by strong geostrophic winds. The surface air at Sapporo, Japan, originated from the ocean surface to the southeast and was cooled to almost the same temperature as that of the sea surface (+3°C); that is, the minimum temperature at 600m progressively decreased to -3°C at the dry adiabatic lapse rate, during the ice pellet event. Sapporo and its surrounding areas, which were at the southern edge of the precipitating area until the passage of the low pressure center and continued to experience midlevel dry and low-level cold inflows maintained by persistent synoptic-scale structures, were identified as the favorable locations for longlasting ice pellets. [ABSTRACT FROM AUTHOR]

Major change in the Earth’s surface temperature appears to be the most critical and universal factor for inducing coevally multiple kill mechanisms for organisms during the global environmental change episodes. Among the major extinction events during the Phanerozoic, the end-Ordovician episode shares almost the same environmental background with that of the end-Guadalupian (middle Permian). These two major extinction-relevant episodes, however, occurred respectively before and after the mid-Palaeozoic botanical revolution, i.e., the first mass development of land plants/forests. Owing to the enhanced terrestrial photosynthesis, the atmospheric CO2 content decreased irreversibly from ca. 2800–800 ppm in the Ordovician down to 400–300 ppm in the Permian. This highlights an apparent contradiction between the end-Ordovician glaciation and distinctly high atmospheric pCO2, which may suggest that one or more agents on global scale were likely responsible for the prominent global cooling besides atmospheric pCO2 with respect to the greenhouse effect. The same conundrum is much clearer in the cases of Proterozoic snowball Earth events. Ancient mid-oceanic sedimentary rocks, i.e., deep-sea cherts and atoll carbonates on top of seamounts, are valuable in recording the average regional/global changes of past oceanic domains without receiving tectonic disturbances along continental margins. The Permian mid-oceanic deep-sea cherts and paleo-atoll carbonates in South-West Japan were deposited in the mid-Panthalassa superocean that occupied nearly 70% of the Earth’s surface (the rest 30% by Pangea). The latest research results from these unique sedimentary archives in Japan are introduced with particular focus on the hiatus-bearing sea-level drop and a unique signature of extraordinarily high ³He enrichment in the extinction-relevant interval. These new lines of evidence imply non-bolide extraterrestrial agent for driving global cooling/sea-level drop. Comparative discussion with the end-Ordovician episode may open a new window for extinction study. [ABSTRACT FROM AUTHOR]

This study investigates future changes in the accumulated and daily heavy winter snowfall in central Japan and the surrounding regions. We analyze outputs of the 48-member ensemble regional climate simulations in the historical and future climates. In the historical climate simulations, each ensemble member has a 61-year simulation from September 1950 to August 2011. For the future climate simulations, we also conduct 61-year simulations assuming the climate at the end of the twenty-first century (2080-2099) when the global mean surface air temperature is about 4 °C warmer than the pre-industrial climate (1861-1880) as projected under the Representative Concentration Pathway (RCP) 8.5 scenario. Our simulations show that the heavy snowfall occurring at a frequency of every 10 years is enhanced in the inland areas of the central part of the Japanese archipelago (central Japan) where the total winter snowfall amount decreases significantly. Heavy snowfall is also intensified in the northern part of the Asian continent where the surface air temperature is much colder than over central Japan. A composite analysis of heavy snowfall events in central Japan indicates that such events occur when the Japan Sea polar air mass convergence zone (JPCZ) appears during the East Asian winter monsoon season. In the future climate projections, the JPCZ is intensified since the warm ocean supplies more moisture due to warming. An upward wind anomaly is also found over the windward side of mountains where the upward flow is prevalent climatologically. The intensification of both the JPCZ and the upward wind over the mountain ranges result in the enhancement of heavy snowfall in inland areas where the surface air temperature is still below 0 °C. [ABSTRACT FROM AUTHOR]

The total mass discharged by the phreatic eruption of Ontake Volcano, central Japan, on September 27, 2014, was estimated using several methods. The estimated discharged mass was 1.2 × 10 t (segment integration method), 8.9 × 10 t (Pyle's exponential method), and varied from 8.6 × 10 to 2.5 × 10 t (Hayakawa's single isopach method). The segment integration and Pyle's exponential methods gave similar values. The single isopach method, however, gave a wide range of results depending on which contour was used. Therefore, the total discharged mass of the 2014 eruption is estimated at between 8.9 × 10 and 1.2 × 10 t. More than 90 % of the total mass accumulated within the proximal area. This shows how important it is to include a proximal area field survey for the total mass estimation of phreatic eruptions. A detailed isopleth mass distribution map was prepared covering as far as 85 km from the source. The main ash-fall dispersal was ENE in the proximal and medial areas and E in the distal area. The secondary distribution lobes also extended to the S and NW proximally, reflecting the effects of elutriation ash and surge deposits from pyroclastic density currents during the phreatic eruption. The total discharged mass of the 1979 phreatic eruption was also calculated for comparison. The resulting volume of 1.9 × 10 t (using the segment integration method) indicates that it was about 1.6-2.1 times larger than the 2014 eruption. The estimated average discharged mass flux rate of the 2014 eruption was 1.7 × 10 kg/h and for the 1979 eruption was 1.0 × 10 kg/h. One of the possible reasons for the higher flux rate of the 2014 eruption is the occurrence of pyroclastic density currents at the summit area. [ABSTRACT FROM AUTHOR]

White mica (phengite and paragonite) K–Ar ages of eclogite-facies Sanbagawa metamorphic rocks (15 eclogitic rocks and eight associated pelitic schists) from four different localities yielded ages of 84–89 Ma (Seba, central Shikoku), 78–80 Ma (Nishi-Iratsu, central Shikoku), 123 and 136 Ma (Gongen, central Shikoku), and 82–88 Ma (Kotsu/Bizan, eastern Shikoku). With the exception of a quartz-rich kyanite-bearing eclogite from Gongen, white mica ages overlap with the previously known range of phengite K–Ar ages of pelitic schists of the Sanbagawa metamorphic belt and can be distinguished from those of the Shimanto metamorphic belt. The similarity of K–Ar ages between the eclogites and surrounding pelitic schists supports a geological setting wherein the eclogites experienced intense ductile deformation with pelitic schists during exhumation. In contrast, phengite extracted from the Gongen eclogite, which is less overprinted by a ductile shear deformation during exhumation, yielded significantly older ages. Given that the Gongen eclogite is enclosed by the Higashi-Akaishi meta-peridotite body, these K–Ar ages are attributed to excess40Ar gained during an interaction between the eclogite and host meta-peridotite with mantle-derived noble gas (very high40Ar/36Ar ratio) at eclogite-facies depth. Fluid exchange between deep-subducted sediments and mantle material might have enhanced the gain of mantle-derived extreme40Ar in the meta-sediment. Although dynamic recrystallization of white mica can reset the Ar isotope system, limited-argon-depletion due to lesser degrees of ductile shear deformation of the Gongen eclogite might have prevented complete release of the trapped excess argon from phengites. This observation supports a model of deformation-controlled K–Ar closure temperature. [ABSTRACT FROM AUTHOR]

This study demonstrates that urban heat island (UHI) intensity can be estimated by comparing observational data and the outputs of a well-developed high-resolution regional climate model. Such an estimate is possible because the observations include the effects of UHI, whereas the model used does not include urban effects. Therefore, the errors in the simulated surface air temperature, defined as the difference between simulated and observed temperatures (simulated minus observed), are negative in urban areas but 0 in rural areas. UHI intensity is estimated by calculating the difference in temperature error between urban and rural areas. Our results indicate that overall UHI intensity in Japan is 1.5 K and that the intensity is greater in nighttime than in daytime, consistent with the previous studies. This study also shows that root mean square error and the magnitude of systematic error for the annual mean temperature are small (within 1.0 K). [ABSTRACT FROM AUTHOR]

Surface air temperature (SAT) over the globe, particularly the Northern Hemisphere continents, has rapidly risen over the last 2--3 decades, leading to an abrupt shift toward a warmer climate state after 1997/98. Whether the terrestrial warming might be caused by local response to increasing greenhouse gas (GHG) concentrations or by sea surface temperature (SST) rise is recently in dispute. The SST warming itself may be driven by both the increasing GHG forcing and slowly varying natural processes. Besides, whether the recent global warming might affect seasonal-to-interannual climate predictability is an important issue to be explored. Based on the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) climate prediction system in which only observed SSTs are assimilated for coupled model initialization, the present study shows that the historical SST rise plays a key role in driving the intensified terrestrial warming over the globe. The SST warming trend, while negligible for short lead predictions, has substantial impact on the climate predictability at long lead times (>1 yr) particularly in the extratropics. The tropical climate predictability, however, is little influenced by global warming. Given a perfect warming trend and/or a perfect model, global SAT and precipitation could be predicted beyond two years in advance with an anomaly correlation skill above ∼∼0.6. Without assimilating ocean subsurface observations, model initial conditions show a strong spurious cooling drift of subsurface temperature; this is caused by large negative surface heat flux damping arising from the SST-nudging initialization. The spurious subsurface cooling drift acts to weaken the initial SST warming trend during model forecasts, leading to even negative trends of global SAT and precipitation at long lead times and hence deteriorating the global climate predictability. Concerning the important influence of the subsurface temperature on the global SAT trend, future efforts are required to develop a good scheme for assimilating subsurface information particularly in the extratropical oceans. [ABSTRACT FROM AUTHOR]

Abstract: Changes in the ground surface temperature (GST), propagating underground, can be recorded as thermal perturbations to the background thermal field. This paper presents a forward model of conductive propagation of GST in a layered material model with uniform thermal properties in each layer and a series of step functions as GST history. This model, which is expressed using the same mathematical form of that for a uniform thermal property model with a series of step functions as GST history, calculates subsurface temperature perturbations that originate from the GST change by superimposing numerically solved solutions of the model with surface boundary condition of a unit function. Using this model, we reconstruct the recent 500-year GST history from borehole temperature data in northern Awaji Island, southwest Japan, by Bayesian inversion. The reconstructed GST history shows the onset of warming in the mid-18th century to the early 19th century and an increase of 1.1–1.3K up to the mid-20th century. From the middle to late 20th century, the GST decreased by about 0.2K. The GST change in the 20th century fits the trend of mean annual surface air temperature records in Kobe, opposite the coast of northern Awaji Island. The GST history in northern Awaji Island differs from that in Ulsan, in the southeastern Republic of Korea, which is located at the same latitude as northern Awaji Island. Differences of the GST histories of these regions most likely reflect differences in sea surface temperatures in these regions. [ABSTRACT FROM AUTHOR]

Abstract: Tremendous efforts have been devoted to improve our understanding of the anthropogenic effects on the atmospheric temperature change. In comparison, little has been done in the study of the human impacts on the subsurface thermal environment. The objective of this study is to analyze surface air temperature records and borehole subsurface temperature records for a better understanding of the urban heat island effects across the ground surface. The annual surface air temperature time series from six meteorological stations and six deep borehole temperature profiles of high qualities show that Osaka has been undergoing excess warming since late 19th century. The mean warming rate in Osaka surface air temperature is about 2.0 °C/100a over the period from 1883 to 2006, at least half of which can be attributed to the urban heat island effects. However, this surface air temperature warming is not as strong as the ground warming recorded in the subsurface temperature profiles. The surface temperature anomaly from the Osaka meteorological record can only account for part of the temperature anomaly recorded in the borehole temperature profiles. Surface air temperature is conventionally measured around 1.5 m above the ground; whereas borehole temperatures are measured from rocks in the subsurface. Heat conduction in the subsurface is much less efficient than the heat convection of the air above the ground surface. Therefore, the anthropogenic thermal impacts on the subsurface can be more persistent and profound than the impacts on the atmosphere. This study suggests that the surface air temperature records alone might underestimate the full extent of urban heat island effects on the subsurface environment. [Copyright &y& Elsevier]

Subjective thermal comfort and outdoor activity in a park and a square in a satellite city northeast of Tokyo were investigated through structured interviews, observations, and comprehensive micrometeorological measurements. Results showed that the park was on an average 1.1°C cooler than the square. The relatively warmer thermal conditions in the square in comparison to the park resulted in a heat load of greater intensity for humans in the square. In general, there was a low relation between the thermal environment and the use of the two places in terms of total attendance. However, the use of the park was influenced more by the thermal conditions than by the use of the square, which can mainly be attributed to the different functions of the two places. Finally, examples of the differences between the use of the sun, the attitudes toward it, and outdoor exposure in Japan and Sweden are highlighted and discussed. [ABSTRACT FROM AUTHOR]

The article offers information on the remote weather related to North Pacific (NP) subtropical sea-level properties. It is mentioned that the variability of climate in NP during summer is dominated by midlatitude events than in South Pacific (SP). The dominant climate in midlatitude is a pattern of weather composites, correlations, and regressions. Lower sea-level pressure (SLP) over central Canada and western tropical Pacific, and higher SLP in east of Japan led to stronger NP high properties. To force or reinforce the NP high, several mechanisms was proposed including suppressed convection.

Abstract: Most of the slope failure disasters in a humid area such as that of Japan are caused by heavy rain. However, even for the case of heavy rainfall that occurs once in every 10 years, total area of slope failures seldom exceeds 10% of a watershed. From this background, we focused on the vein-like groundwater flows that increase pore-water pressure, and clarified the relationship between distributions of slope failures and groundwater veins. In this study, a 1-m-depth ground temperature survey and water-chemistry analyses at springs and boreholes were conducted in Zentoku area of Shikoku Island, southwestern Japan, to grasp the distribution of groundwater veins and their sources. Subsequently, slope-stability was analyzed to investigate the relationship between groundwater veins and slope failures at study sites. These results lead to the following conclusions: The slope failures appear to concentrate around shallow groundwater veins and groundwater veins rising from deep layers. This means that slope failures caused by these groundwater veins in addition to rainfall. Two types of groundwater originate in the deep layers: one has short storage time as indicated by the fact that dissolved substances are low; the other is stored for a lengthy period as noted by a high concentration of dissolved substances. By combining the results of stability analyses and distribution of groundwater veins, it is suggested that prediction of zones with high potential for slope failure can be more accurate. [Copyright &y& Elsevier]

Detailed heat flow measurements were carried out in the central part of the Nankai Trough off eastern Shikoku, where the fossil spreading center of the Shikoku Basin is subducting beneath the southwest Japan arc. The quality of temperature gradient values was examined for all the existing and new heat flow data and the average of new thermal conductivity data was used at all the stations. Reliable heat flow on the floor of the trough was found to be very high and rather uniform, with an average of about 200 ± 20 mW/m2. Taking account of the effect of recent rapid sedimentation on the surface heat flow, the heat flow from the deeper part is estimated to be even higher by 20–30%, almost twice as high as the value expected from the age of the subducting Shikoku Basin, about 15 m.y. Such a large heat flow anomaly cannot be attributed solely to advective heat transfer by pore fluid flows associated with subduction and accretion of the sediments brought into the trough, suggesting that the underlying Shikoku Basin lithosphere is anomalously warm in the study area. A possible cause of the anomaly is reheating of the lithosphere by post-spreading thermal activities along the fossil spreading center, which produced the Kinan Seamount Chain and continued until about 7 Ma. However, such reheating even at 6 Ma cannot produce a heat flow high enough to explain the observed values. A steep landward decrease in the heat flow is observed at the toe of the accretionary prism. The scale of this decrease indicates that its origin is not deep seated, and thus a part of the anomalous heat flow on the trough floor may result from some processes in relatively shallow layers. The thermal structure of the Shikoku Basin is a critical boundary condition for thermal models of the Nankai subduction zone and its seismogenic zone for large thrust earthquakes. More heat flow measurements need to be made around the study area in order to clarify the extent and origin of the high heat flow anomaly. [Copyright &y& Elsevier]

Examines the relations between surface temperature and air temperature on a local meteorological scale during winter nights in Japan. Use of optimum interpolation; Relationship of spatial scales with atmospheric boundary layer vertical thermal structure; Impact of vegetation density on atmospheric temperature.

• The horizontal directional drilling technology is used for GSHP systems. • Horizontal Directional Drilling technology can reduce capital cost of GSHPs. • Larger Diameter of directional GHE enhances heat exchange rates, significantly. • The depth and length of the directional GHE are critical parameters. • Groundwater flow presence causes significant enhancement in heat exchange rate. The drilling cost of Ground Heat Exchangers (GHEs), which increases the capital cost, is one of the main obstacles to their widespread development. Horizontal Directional Drilling (HDD) is a lower cost no-dig drilling technology commonly used for drilling tunnels or for the installation of urban infrastructure such as pipes, cables, etc., using the prescribed underground path. Thus, using HDD technology for horizontal GHE (HGHE) is expected to improve the competitiveness of ground source heat pump (GSHP) systems, since its drilling cost and the requirement of surface land area are significantly smaller than those of conventional excavation. In this research, a horizontal U-shaped hole was drilled as an experimental GHE in Saga City, western Japan. This hole with diameter of 230 mm, length 63 m, and a maximum depth of 8 m was used to place a polyethylene pipe with a 52 mm ID as GHE, inside. The thermal response test (TRT) with a heat load of 35−45 W/m effectively demonstrated the good heat exchange ability of the HGHE due to the larger heat exchange surface and the lack of thermal interference between pipes. The developed numerical model in FEFLOW and based on GHE design as well as the field's geological condition were validated through the history matching of the heat medium temperatures measured during the TRT. This model was then used to carry out a sensitivity analysis under different design conditions. The results showed that the heat exchange rates were significantly enhanced in larger diameter of GHEs, while the unit heat exchange rates declined in longer lengths of GHE. The deeper installation of GHE was found to be insignificant due to the delayed seasonal change of the ground temperature, not to mention the consequent higher drilling cost. In addition, the effect of groundwater flow indicated that faster groundwater velocities, and in perpendicular direction, show the maximum system improvement. Finally, an economic and comparative study was performed to calculate and compare the merits of HDD with equivalent conventional GSHPs including single and double U-tube, coaxial and slinky GHE. The results of economic analysis showed that HDD technology can reduce GHSP cost up to a maximum of 78 %. [ABSTRACT FROM AUTHOR]