Tokyo Skytree Research Articles

Cover Photograph

Front cover: The Tokyo Skytree, Japan (634m (2080ft) high). Taken at 2129 local time on the 21 May 2023 looking eastwards. Two layers of cloud were clearly visible, one of Stratus and the other of Stratocumulus. (© Grahame King) image

松戸市の市民景観選好における眺望景観に関する研究

This study analyses the characteristics of scenic viewing landscape in Matsudo City based on citizens’ preferences determined from their nominated scenic viewpoints, as well as related photos and comments submitted during the activity ‘My Favorite Scenic Spots of Matsudo City’ from 2009 to 2018. Through sorting out ten-year data, there are a total of 47 scenic viewpoints in Matsudo City, based on 64 contributors with 82 photos. Matsudo citizens’ preferences of scenic views, including the types and distribution characteristics of the scenic viewing subjects, and distribution characteristics of the viewpoints in Matsudo City, were classified and analyzed. The analysis results showed that the scenic viewpoints in Matsudo City are mainly concentrated in the western part, whereas the most preferred scenic viewing subjects are landmarks, both artificial and natural, mainly located outside of Matsudo City, especially Mt. Fuji and Tokyo Skytree. Most of the scenic viewing subjects could still be viewed clearly until now. Areas along the Edo River, areas surrounding Matsudo Station, and the Yakiri area have great potential for vitalizing the scenic viewing landscape of the city. This study suggests that Matsudo City’s landscape planning in the future should focus more on the scenic views and the preservation of these locations.

New bounds on macroscopic scalar-field topological defects from nontransient signatures due to environmental dependence and spatial variations of the fundamental constants

We point out that in models of macroscopic topological defects composed of one or more scalar fields that interact with standard model fields via scalar-type couplings the back action of ambient matter on the scalar field(s) produces an environmental dependence of the fundamental constants of nature as well as spatial variations of the fundamental constants in the vicinity of dense bodies such as Earth due to the formation of a ``bubblelike'' defect structure surrounding the dense body. In sufficiently dense environments, spontaneous symmetry breaking may be inhibited altogether for ${\ensuremath{\phi}}^{2}$ interactions, potentially delaying the cosmological production of topological defects to rather late times. We derive bounds on nontransient variations of the fundamental constants from torsion-pendulum experiments that search for equivalence-principle-violating forces, experiments comparing the frequencies of ground- and space-based atomic clocks as well as ground-based clocks at different heights in the recent Tokyo Skytree experiment, and measurements comparing atomic and molecular transition frequencies in terrestrial and low-density astrophysical environments. Our results constrain the present-day mass-energy fraction of the Universe due to a network of infinite domain walls produced shortly after the big bang nucleosynthesis or cosmic microwave background epochs to be ${\mathrm{\ensuremath{\Omega}}}_{\text{walls},0}\ensuremath{\ll}{10}^{\ensuremath{-}10}$ for the symmetron model with a ${\ensuremath{\phi}}^{4}$ potential and ${\ensuremath{\phi}}^{2}$ interactions, improving over cosmic microwave background quadrupolar temperature anisotropy bounds by at least 5 orders of magnitude. Our newly derived bounds on domain walls with ${\ensuremath{\phi}}^{2}$ interactions via their effects of nontransient variations of the fundamental constants are significantly more stringent than previously reported clock- and cavity-based limits on passing domain walls via transient signatures (regardless of their possible degradation due to previously neglected effects of the strongly repulsive potential generated by Earth on the passing domain walls) and previous bounds from different types of nontransient signatures (by about 10 orders of magnitude for wall thicknesses comparable to the size of Earth), under the same set of assumptions.

Seasonal Trends of Atmospheric Ice Nucleating Particles Over Tokyo

AbstractIce nucleating particles (INPs) originating from Asia are expected to have large impacts on aerosol‐cloud‐precipitation interactions on local, regional, and global scales. However, their seasonal variability is poorly understood. Here, we present a year‐round record of atmospheric INPs measured on Tokyo Skytree, which is the world's tallest broadcasting tower located in the Tokyo Metropolitan area. The INP number concentrations showed relatively small variations in the temperature regime below −20°C, whereas the values were episodically enhanced by long‐range transported Asian dusts. On the other hand, the INP spectra in the temperature regime warmer than −20°C exhibited measurable seasonal variations. Notably, the INP number concentrations in the temperature regime between −15°C and −10°C tended to indicate higher values in warm/wet seasons and lower values in cold/dry seasons. Our results suggest that Asian dust events and seasonal variations in certain particles of biological origin linked to local/regional meteorology might influence the seasonal trends of the INP spectra over the Tokyo Metropolitan area.

Frequency difference between two clocks at Tokyo Skytree: Contribution of Earth’s self-rotation

We focus on a fundamental issue about the physical meaning of the results of the experiment by Takamoto et al. (2020). Specifically, one must address the time dilation effect associated with the motion of the clocks around the self-rotational axis of Earth as seen by a remote observer free of such rotation. We accentuate the importance of taking into account this effect in the Tokyo Skytree experiment. This is especially relevant in the light of the results gathered from recent measurements of the Mössbauer effect in a rotating system.

Lightning occurrence characteristics around tokyo skytree

The lightning occurrence characteristics around Tokyo Skytree are investigated with Japan Lightning Detection Network, and the results are evaluated with observation data by the Rogowski coils installed at a height of 497 m and by cameras set around Tokyo Skytree. After the construction of Tokyo Skytree, the apparent density of detected strokes near Tokyo Skytree increases, but without lightning strokes to Tokyo Skytree, the density of detected strokes around Tokyo Skytree seems to be roughly constant. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Test of general relativity by a pair of transportable optical lattice clocks

A clock at a higher altitude ticks faster than one at a lower altitude, in accordance with Einstein’s theory of general relativity. The outstanding stability and accuracy of optical clocks, at 10−18 levels1–5, allows height differences6 of a centimetre to be measured. However, such state-of-the-art clocks have been demonstrated only in well-conditioned laboratories. Here, we demonstrate an 18-digit-precision frequency comparison in a broadcasting tower, Tokyo Skytree, by developing transportable optical lattice clocks. The tower provides the clocks with adverse conditions to test the robustness and a 450 m height difference to test the gravitational redshift at (1.4 ± 9.1) × 10−5. The result improves ground-based clock comparisons7–9 by an order of magnitude and is comparable with space experiments10,11. Our demonstration shows that optical clocks resolving centimetres are technically ready for field applications, such as monitoring spatiotemporal changes of geopotentials caused by active volcanoes or crustal deformation12 and for defining the geoid13,14, which will have an immense impact on future society. A pair of transportable optical lattice clocks with 10−18 uncertainty is developed. The relativistic redshift predicted by the theory of general relativity has been tested at the 10–5 level by the two optical clocks with a height difference of 450 m on the ground.

Characteristics of Lightning Observed at Tokyo Skytree

Characteristics of Lightning Observed at Tokyo Skytree

Spatial Analysis of Tourist Spots in Central Tokyo Using Online Geotagged Photographs from Flickr

Abstract. Advancements in information and communication technologies enable us to trace human activities through digital media; networks of fixed or mobile sensors, such as smartphones, global positioning systems, and travel cards, can monitor the timing and locations of human behavior throughout the day. These new sources of geospatial data provide the possibility of analyzing high-resolution big data to capture patterns of human spatial behavior across space and time. Online photo-sharing services are comprised of such sources. This study analyzes the geocoded photos from a photo-sharing service to make a comparison of the varying spatial patterns of tourist attractions in Tokyo as differentiated between those taken by Japanese and foreign visitors. We selected three places (Shinjuku, Asakusa, and Ginza) as study districts from the five top places frequently visited by foreigners based on the 2014 Survey Report of Foreigner Behavior. The data were downloaded from Flickr, one of the most popular online platforms for people to share their travel experiences by uploading photos. We used the data of geocoded photos from 2014, taken within 1 km from Shinjuku, Ginza, and Asakusa stations. Information on the nationality of contributors recorded in the Flickr data was used to compare the tourist spots of Japanese and foreign visitors. To identify the tourist spot, we employed a hotspot analysis using geographic information systems. The obtained results showed some tourist spots common to Japanese and foreign visitors in three study areas, namely, places close to railroad stations. However, the distribution of foreigners’ photographs showed a higher spatial concentration than those taken by Japanese tourists. This tendency is consistent with the findings obtained by Suzuki and Wakabayashi (2008), wherein they compared photos of tourist attractions in guide books of Tokyo. This comparative difference can be explained by the accessibility of railroad stations; in other words, foreigners rely more on public transportation during their comparatively short stays. Spatial patterns of tourist spots varied with the study district in question. In Shinjuku and Ginza, there are differences in tourist spots between Asians and Europeans. Particularly, European tourists’ hot spots tend to be more scattered than Asians. However, such differences are not observed in Asakusa, where tourists’ hot spots are concentrated around Sensoji Temple and Tokyo Sky Tree. The reason for this is that tourist attractions are concentrated in and around specific facilities in the Asakusa district. Hence, the variations of tourist spots obtained by analyzing the geotagged photographs on Flickr can be explained by the difference in behavior and interest of foreign tourists between countries, as well as the spatial distribution of tourist attractions.

Current Observation Results of Downward Negative Flashes at Tokyo Skytree From 2012 to 2018

Direct observation of lightning current is a fundamental approach to evaluating lightning parameters, which are among the most basic factors for the lightning protection design of various grounded objects. However, for a tall grounded structure, upward lightning flashes initiated from the top of the structure have usually been observed, and the direct observation results of downward flashes have been limited. We developed and installed a pair of Rogowski coils at Tokyo Skytree, which is a 634-m-high freestanding broadcasting tower in Japan (35.71°N, 139.81°E), and have conducted direct observation of lightning flashes striking the tower. As of November 2018, 70 lightning flashes striking the tower, 26 downward and 44 upward, have been observed since the end of February 2012. In this paper, we focus on the downward negative flashes that occurred at the tower for seven years from 2012 to 2018 and report on the observed results of typical waveform parameters of lightning stroke currents in comparison with other observed results on downward negative flashes.

Lightning Strike to a Tall Grounded Object: Part 1. Circuit Modeling With Direction Dependence

This paper proposes a circuit model of a lightning strike to a tall grounded object. The model can consider the direction-dependent attenuation characteristic of current propagating along with a tall grounded object as well as frequency-dependent characteristics of lightning channel and tower impedances, in contrast to the conventional lossless transmission line representations. Hence, the model removes the use of an unrealistic high grounding impedance for approximately expressing the significant current attenuation propagating upward along with the tall object. Measured lightning currents at a height of about 500 m of the 634-m-high Tokyo Skytree are accurately reproduced with the proposed model, which assumes a constant lightning channel impedance with a current source that generates a current waveform decaying with time, or a frequency (time) dependent lightning channel impedance with a step-like voltage source. The proposed model can also be used for lightning electromagnetic pulse calculations.

Reproduction of Electromagnetic Field Waveforms of Downward Lightning Strokes Hitting Tokyo Skytree

Reproduction of Electromagnetic Field Waveforms of Downward Lightning Strokes Hitting Tokyo Skytree

Lightning Strike to a Tall-Grounded Object: Part 2—LEMP Calculation With a Channel Approximation

Lightning electromagnetic pulse (LEMP) waveforms associated with lightning strikes to the 634-m high Tokyo Skytree are calculated by the finite-difference time-domain (FDTD) method in the two-dimensional (2-D) cylindrical coordinate. The three-dimensional (3-D) tortuous lightning channel and the tall strike object are represented by an “equivalent vertical” phased-current-source array. The current propagation speed along the equivalent vertical lighting channel is determined in two steps: first, the channel is projected on a plane including the strike object and a field observation point, and then it is converted into the straight vertical channel right above the strike object. Thus, the height-dependent lightning-current propagation speed along the equivalent channel depends on the direction of the observation point. The proposed method greatly reduces computational resources required for calculating LEMPs without deteriorating accuracy since it allows the use of the 2-D FDTD method. LEMP waveforms measured at a horizontal distance of 27, 57, and 101 km (in different directions) from the strike object are accurately reproduced by the proposed method. The results clarified that the lower region of the tortuous lightning has a large influence on the wavefront of the LEMPs at a horizontal distance ranging from 20 to 100 km from the strike point.

3‐D Finite Difference Time Domain Simulation of Lightning Strikes to the 634‐m Tokyo Skytree

AbstractWaveforms of vertical electric field observed at distances of 27, 57, and 101 km from the 634‐m tall Tokyo Skytree (Japan) struck by lightning have been reproduced using the 3‐D finite difference time domain method. Optically observed 3‐D lightning channels and currents directly measured in the tower were used. Distribution of current along the lightning channel was represented using the transmission line model, assuming a constant propagation speed v = 0.5c. Simulations with commonly assumed vertical channel did not allow us to reproduce the observed early (within 5 μs or so) field zero crossing when the 1‐D speed was set to be constant and equal to the 3‐D speed (v = 0.5c) used for the actual‐channel‐geometry case. It was, however, possible to achieve a good match for a vertical channel when the vertical component of 3‐D speed was evaluated for each nonvertical channel segment and used in the corresponding range of heights.

Current Observation Results of Upward Negative Flashes Initiated from Tokyo Skytree during 2012 to 2016

Current Observation Results of Upward Negative Flashes Initiated from Tokyo Skytree during 2012 to 2016

The advisability of high-rise construction in the city

In this article there discusses the question of advisability high-rise construction, the reasons for its use, both positive and negative sides of it. On the one hand, a number of authors believe that it is difficult to avoid high-rise construction due to the limited areas in very large cities. On the other hand, a number of other authors draw attention to the problems associated with high-rise construction. The author of the article analyses examples of high-rise construction in several countries (UAE, Dubai "Burj Khalifa"; Japan "Tokyo Sky Tree"; United States of America, "Willis Tower"; Russia "Federation Tower") and proves the advisability of high-rise construction in the city.

Characteristics of Droplet Size Distributions in Low-Level Stratiform Clouds Observed from Tokyo Skytree

Characteristics of Droplet Size Distributions in Low-Level Stratiform Clouds Observed from Tokyo Skytree

スカイツリー周辺地域における飲食店の集客要因分析

スカイツリー周辺地域における飲食店の集客要因分析

Tokyo Tower and Tokyo Skytree: History and Symbolism in Contemporary Japan

The Tokyo Tower and the Tokyo Skytree are the two most recognizable landmarks on the skyline of Japan’s capital. By means of a documental revision, a textual interpretative analysis of media contents, participant observation and unstructured interviews, the objective of this article is to identify the development of these towers as symbols of Tokyo and Japan. It is found that, with more than half a century of existence, the Tokyo Tower represents the successful postwar Japanese society, while in just five years the Tokyo Skytree has become a symbol of Japanese national spirit and resilience in an era of multiple crises. Both broadcasting towers are regularly portrayed in Japanese media linked to narratives of romance, dreams, family and community. Also, enhanced by their special lightening at night, they stand as attractive poles for locals and visitors to choose them as background in relevant events in their lives.

Observation of lightning strikes at Tokyo skytree [News From Japan

More than 260 years have passed since the famous experiment on lightning carried out by Benjamin Franklin in 1752. Everybody knows that lightning is an electromagnetic phenomenon. However, scientific observation of lightning strikes and lightning currents is still of prime importance to achieve more complete lightning protection. Researchers in the Central Research Institute of Electric Power Industry (CRIEPI) and the University of Tokyo are observing lightning strikes and measuring lightning currents at Tokyo Skytree, one of the tallest freestanding towers in the world.