MM/DD 14:45--16:15 Name
Abstract
05/11 14:45--16:15 Sugiyama Haruki
In recent years, the damage caused by heavy rainfall brought by developed cumulonimbus clouds has become a problem. In the damage caused by the typhoon in 2021, floods occurred in Manila and 150,000 people were forced to evacuate. In Japan, too, a phenomenon called “guerrilla heavy rain”, where heavy rain falls in a short period of time, has been occurring frequently in recent years, causing road flooding, paralysis of transportation systems, power outages due to lightning strikes, and so on, affecting people’s lives. To cope with these problems, it is important to predict the development of cumulonimbus clouds that may attack cities as early as possible and take measures before damage occurs. The factors that cause cumulonimbus clouds are atmospheric convection and the presence of water vapor. Convection is the circulation of air caused by the temperature difference between the heated air near the ground and the cooled air at the top of the troposphere. When a mass of air containing water vapor rises due to convection, the water vapor condenses and forms clouds. As a method to predict their growth, observations using radar and satellites are currently being conducted. However, these observation methods have spatial resolution and temporal resolution challenges. Therefore, in this study, we aim to develop a method to observe the distribution of water vapor by multi-wavelength imaging and capture the movement of water vapor with unprecedented spatial resolution and temporal resolution, and improve the prediction of cumulonimbus cloud development. In a previous standard star observation in the Antarctic region, it was suggested that the amount of water vapor in the atmosphere could be estimated by spectral observation. The observation was carried out using a device that combined a visible light spectrometer with a 203 [mm] Schmidt-Cassegrain telescope and observed the spectrum of the target object in the wavelength range of 600-900 [nm] at Syowa Station’s observation building rooftop, Japan’s base for Antarctic observation. Then, we divided the obtained standard star spectrum by the known catalog value and calculated the absorption spectrum derived from the Earth’s atmosphere. We derived the ratio of equivalent widths of H2O absorption at 716-731 [nm] and O2 absorption at 759-770 [nm] as absorption ratio. As a result, in the observation with HR74 as the target, the correlation between precipitable water amount and absorption ratio was 0.89, indicating a strong correlation between them. Therefore, there is a possibility that we can elucidate the horizontal distribution of water vapor by performing imaging observations focusing on this wavelength range. As a method to observe water vapor focusing on this wavelength range, we are currently considering observations using satellites and all-sky cameras. In this presentation, I will introduce preliminary analysis results of test observations using satellites and observation concepts using all-sky cameras.
06/01 14:45--16:15 Ishida Yurino(Canceled)
06/08 14:45--16:15 Ye Min
Plastic pollution can be seen from Mount Everest to the deep ocean. Plastics of different sizes in the marine environment can be found due to mismanagement and natural disaster. Plastic debris can last from a few days to millennia, and they decompose to the micro level and affect the habitats and food ecosystem of phytoplankton, zooplankton, and fish. The plastics waste to rivers, lakes, and seas is estimated to be from 9 to 23 million metric tons per year. The mathematical model estimated that 99.8% of plastics are located below the surface. However, due to the knowledge gap for detection of the plastics on large scale, the actual impacts of plastics on the environment are not defined yet. The physiological process of plastics and its impacts along the track in seawater is also understood well. This study emphasized finding the method for the detection of plastics using remote sensing methods. The spatial resolution and signal-to-noise ratio of satellite sensor and their sensitivity is challenging to tackle this problem. Moreover, the dramatic changes in plastics due to the ocean wave and the high absorption nature of water vapor in the thermal band also limit to observe the monitoring of marine plastics. In this seminar, building the spectral library of different plastics which are commonly used in daily life as a basic tool for the detection of plastics using InGas camera with LCTF (liquid crystal tunable filter) to record the spectral data from the 700nm-1600nm. As a second step, classification of plastics using the common spectral bands for the extraction features are mentioned and effects of sunlight angle in the observation will be presented. Finally, the classification of plastics in the controlled environment which are over the water surface is also mentioned.
06/15 14:45--16:15 Ishida Yurino(Canceled)
06/22 14:45--16:15 Garid Zorigoo
Hyperspectral Imaging (HSI) devices are a bit hard to acquire compared to Multispectral devices. Consequently, both data analysis and usages of HSI aren't as mature and popular as multispectral technology, even though HSI might contain more delicate information about the target. With extensive HSI data, it may be possible to discover early-disease-detection or yield-estimation in a crop field. In this paper, we'll introduce our Spectral-Scanning-Device that is reasonably easy-to-reproduce and inexpensive; hoping to help other researchers acquiring HSI data. The price is approximately 1/50 or less compared to a typical HSI imager. In simple terms, our device is a spectroscope placed on top of 2-axes precisely controlled and monitored motors to log spectrum in a scanning motion. Due to initial data reconstruction of the device being shaped spherically, we named it Spectrosphere (combining 2 words Spectrum and Sphere). Currently, We're able to achieve scanning elevation angles from -50° to 10°, in all azimuth angles 0-360°, about 20-min. Our angular resolution is running average for 2x2 degree and plot at a step of <0.2 degrees; optical sensor’s wavelength range is about 400 to 800-nm. Currently, in our method, there are few pitfalls like change of sunlight during a scanning measurement (e.g. cloud movement hides the sun, etc.), and targets’ relative positions with the device (i.e. different reflection angle) may affect the uniformity of data. About the first one, we'll discuss our calibration method with a reflector, and the second one is hinting towards a larger issue about reflection-angle affecting measurement satellites that can change their viewing angle. Besides technicalities, subjects like these will be discussed further down.
06/29 14:45--16:15 Enkhbayar Badamgarav
The tree species classification is crucial for forest mapping, monitoring, and sustainable forest management. Recent studies used combinations of various remote sensing methods to improve the overall accuracy of the classification. Most of the recent studies are heavily focused on improving data processing techniques than on scientific principles. And, even though the same classification method and machine learning techniques are used, there are many cases where the results were different, in other words, the results are quite hard to reproduce. Therefore, based on my research and measurements, I intend to find what optimal strategies should be followed and scientific cause for affecting classification accuracy when measuring using a spectrometer placed on a drone/UAV. In this seminar, I will discuss previous studies, their problems and the purpose of my study. The presentation is divided into three parts, the first part presents current approaches for tree-species classification, the second part will present works I have done. We installed the inexpensive spectrometer developed at Hokkaido university on a drone and then generated a spectral mapping in the Tomakomai research forest of our university, in Oct 2022. Moreover, we chose the four wavelengths ( 480 nm, 500 nm, 600 nm, 660 nm) for tree-species classification depending on the gimbal spectrometer measurement that was made in the Hokuden research forest in previous years. After that, the classification analysis using the 4-band camera data with SVM algorithm is mentioned. Finally, we will discuss the future works.
07/06 14:45--16:15 Hamamoto Ko
Venus is covered by thick sulfuric acid clouds extending from 50 to 70 km in altitude, which reflect about 80 % of the incident sunlight, but in the ultraviolet (UV) wavelength range, various patterns are observed due to absorption by SO2 and an unknown absorber. The unknown absorber contributes to about half of the solar heating in the Venusian atmosphere. The distribution and temporal variability of the unknown absorber are important basic information for understanding the Venusian climate system. Spectral observation of Venus in the UV wavelength range has been conducted by ground-based telescopes and spacecraft including MASCS/MESSENGER, SPICAV and VIRTIS/Venus Express. Perez-Hoyos et al. (2018) reported that S2O and OSSO’s UV absorption spectra, which are the unknown UV absorber candidates, showed the best agreement with MASCS UV spectral data which has 5 nm wavelength resolution, and emphasized the importance of the mid-high resolution spectra data in the regions of higher and lower UV absorption for providing constrain to the physical state of the UV absorber. Toward the identification of the unknown UV absorber at cloud top altitude of Venus, we developed Ultra Violet Spectrometer, which provides 2 nm wavelength resolution in 250 – 450 nm range with 4.3 and 6.3 arcsec field of view (FOV), and is equipped Pirka telescope, 1.6 m ground-based telescope. The observation goal is to get UV spectra of Venus capturing unique spectral features, for example S2O absorption features centered around 339, 346, 353, 360, 368 nm, in higher and lower UV absorption regions over Venus disk to provide constrain to UV absorber. Based on the goal, we observed Venus disk on 16 May, 2022 with Venus diameter of 15 arcsecs, elongation angle of 39.8 degrees by 6.3 arcsec FOV which can separate Venus disk into the south and north hemisphere. We also target March – July in 2022 and 2023 as observation periods with over 15 arcsecs Venus diameter by 4.3 arcsecs FOV which can separate Venus disk into equatorial and mid-high latitude regions.
07/13 14:45--16:15 San Lin Phyo
The global climate changes are becoming worse as increasing of atmospheric concentration of greenhouse gases such as carbon dioxide (CO2), chlorofluorocarbons (CFCs), methane (CH4), and nitrous oxide (N2O). The contribution of each gas to the greenhouse effects is CO2 - 55%, CFCs - 24%, CH4 - 15%, and N2O - 6% [Demirbas, 2008]. [Demirbas, 2005] estimated that world carbon dioxide emission can be over 10000 million metric tons in 2025. In nature, forests, wetlands, grass, and croplands uptake carbon dioxide from atmosphere in photosynthesis and store it for a long time. Wetlands soil carbon storage percentage is about 20% higher than forests ,65% than grass/shrub-lands [Liu et al., 2021]. Paddy fields are temporary wetlands and contains substantial CH4 emissions, contributing about 10% of all anthropogenic CH4 emissions [Nazaries et al., 2013]. However, [Liu et al., 2021] mentioned that the carbon storage of paddy soil is over 20% greater than other staple crops and grassland. Greenhouse gases (GHG) contribution from paddy fields changes at various condition and time. Although several research regarding carbon in paddy fields have been published, there are still no research relates with the temporal variation of carbon fixation in paddy fields utilizing remote sensing. Therefore, the purpose of this research is to estimate temporal variation of Greenhouse gas (GHG) contribution from paddy fields. Furthermore, [Xuanlong Ma et al., 2020] mentioned that Sun-angle and sensor angle variations can alter reflectance and Vegetation Index (VIs). The complexity of the sun-angle affects in the remote sensing of vegetation. Therefore, one of the objectives of this research is to observe the characteristics of plant’s reflectance at sensor’s different elevation angle and azimuth angle. In this experiment, the reflectance of grass plants was measured using spectrometer at different angle. Before measurements, required calibration process for spectrometer were conducted. In this seminar, the methods regarding calibration process will be presented and about the measurement results will be discussed.
07/20 14:45--16:15 Yui Sho
Damage caused by heavy rainfall has become a problem worldwide in recent years. The damage is particularly severe in South-East Asian countries, and there is an urgent social need to improve the accuracy of forecasts for these. These heavy rains are mainly caused by cumulonimbus clouds. In contrast, observing and analysing lightning strikes, which are known to precede heavy rainfall by several tens of minutes, is expected to be a new method for predicting heavy rainfall. This study aimed to achieve this ultimate goal by using two different lightning observation methods. One is the observation of changes in the electric field using a plate-type sensor. The electric field changes during lightning strikes are observed using plate sensors installed at high-density, multi-point locations in Manila, Philippines, to estimate the three-dimensional location of lightning strikes and the amount of lost charge. In previous studies, the analysis programme of the estimation method was practically inadequate due to data errors in the observation equipment itself. In this respect, this study proposes a new method in interpolation analysis using kriging. This method reduced the analysis time from two minutes to about eight seconds, and also reduced the estimated position error within the observation range to around 500 m. Another is the observation of thunderstorms using infrasound sensors. Infrasound, which is a very low frequency sound, can propagate over long distances, making it possible to observe thunderstorms even when the observation point distance is set far away. If observations are made at three or more points, it is expected that the location of the lightning strike can be identified and the energy of the strike can be estimated by calculating the sound pressure and distance. In previous studies, there have been few studies in which multiple infrastructure sound sensors were installed outdoors to observe lightning strikes. In the present study, INF03 sensors were installed at four locations in Bergen, Norway, at 20 km intervals, and a total of four thunderstorms could be recorded during the winter observation period 2022-2023. Frequency analysis of these using the S-transform showed that the waveforms considered to be thunderstorms had a strong intensity around 2 Hz.
07/27 14:45--16:15 Miyajima Hideki
The Philippines is at risk from flooding. If a method could be established to predict the heavy rains that cause these floods, the damage could be controlled. It is known that there is a correlation between the frequency of thunderstorms and the amount of precipitation. If we can estimate the total energy of lightning, we may be able to find an even better correlation. Lightning is known to emit low-frequency sound waves, infrasound, and the use of special microphones that can measure infrasound will allow us to observe thunderstorms. In this presentation, we will introduce our efforts to establish a method to identify lightning by applying Fast Fourier Transform processing to data measured by infrasound sensors actually installed in Manila.
08/03 14:45--16:15 Tanuma Yuta
My research is to estimate the physical properties of space debris in Earth orbit using optical telescopes. In this observation, I succeeded in obtaining reflectance spectra of the geostationary orbiting meteorological satellite HIMAWARI 9 and the debris SL-12 Rocket Body. These spectra are in general agreement with those of previous studies, and the results are very useful as they guarantee the accuracy of my observations. Space debris is generally defined as derelict satellites, detached rocket bodies and debris from satellite collisions and destructive experiments. It is estimated that there are currently about 30,000 pieces of debris larger than 10 cm in diameter in Earth orbit, and more than 100 million pieces, including pieces a few millimetres in diameter. In Low Earth Orbit (LEO) they orbit at a speed of about 8 km/s, which is fast enough to puncture satellites. Space debris not only causes satellites to fail, but also contains the danger of falling to Earth. To avoid these dangers, it is very important to know the physical properties of the debris (reflectivity, color, rotation period, surface material) and I aim to estimate these using the Pirka telescope. During this observation, I was able to obtain reflectance spectra of the meteorological satellite Himawari 9 and the debris SL-12 Rocket Body. The HIMAWARI 9 has a flat spectral shape, while the SL-12 R/B has a large reflectance shift towards longer wavelengths, which clearly shows the characteristics of the surface composition. The Sunflower 9 consists of silver multi-layer insulation (MLI) and solar panels, and the obtained spectra are similar to the reflectance spectra of those materials [Vananti et al., 2016]. SL-12 R/B is highly reflective on the long wavelength side, suggesting that the surface may be covered with a white or gold color [Jorgensen et al., 2003].
08/17 14:45--16:15 Amada Kotaro
Uranus is the planet which spins around its orbit at an inclination of 98 degrees with respect to its orbital plane. As of August 2023, the only close observations conducted in the past were during the flyby mission of Voyager-2 in 1985-1986. Apart from this, various observations is conducted using telescopes. Notably, heightened atmospheric activity has been observed around the vernal equinox, 2007. In observations conducted in the H-band (1.6 μm) by Keck telescope in the 2014, bright localized cloud were found to be brighter and exhibiting variations in size compared to other areas [Pater et al. in 2015]. These bright cloud are consider to be distributed within the atmospheric region at depth of 0.3-0.7 bar [Sromovsky et al., 2005]. In addition, from 2014, polar caps resulting from CH4 downwelling around the 1 bar level have been observed in the northern polar region [Toledo et al., 2018]. These polar caps changes in brightness around the 80° latitude region, observed between 2015 - 2023, by VLT(Very Large Telescope). This phenomenon is thought to be caused by the transport of the atmosphere from regions deeper than 1 bar [Akins et al., 2023]. Both of these phenomena are deeply influenced by the vertical convection of Uranus’ atmosphere. Consequently, understanding the atmosphere of Uranus requires determining the vertical transport velocities of atmospheric components. In this study, I’m going to conduct observation with 1.6 m Pirka Telescope owned by Hokkaido University for Spectrophotometry and Spectroscopy of Uranus. Two different types of observations and analysis methods are conducted over a period of 1-4 weeks, which aimed at determining the temporal variations in absorption due to atmospheric constituents. Ultimately, these efforts aim to estimate the vertical transport velocities. In this seminar, I will explain about the purpose and goal, observations and analysis method of this study.
08/24 14:45--16:15 Ono Tatsuharu
The monitoring of planetary lightning is one of the procedures for understanding atmospheric dynamics. The spacecraft has detected lightning on Jupiter through night-side optical imaging and radio wave observation. Previous studies suggested that combining the many small-scale eddies driving the zonal jet receive their energy from moist convection that generates lightning (Gierash et al., 2000; Ingersoll et al., 2000). The moist convection would correlate with the jovian lightning, the same as Earth lightning. A possible signal originating from Venusian lightning was recorded by LAC onboard AKATSUKI on March 1, 2020 (Takahashi et al., 2020). If the signal is generated from lightning discharge, the occurrence rate equals 2.7x10-12 s-1km-2, estimated by the ground-based telescope observation (Hansell et al., 1995). It could be helpful to reveal the Venusian atmospheric dynamics if we can monitor global Venusian lightning activity and distribution compared with other atmospheric information. Two-band high-speed photometers simultaneously observe the lightning with the ground-based telescope. We increase our observation time using ground-based telescopes to reach a consensus between the previous studies. By using the two-band photometers and high-speed photon counting, it is possible to distinguish between the lightning and variation of the planet disk’s dayside brightness or sky brightness variation. We have developed the Planetary Lightning Detector (PLD) to observe the optical Jovian and Venusian lightning mounted on the 1.6-m Pirka Telescope. PLD has two photometers. The photomultiplier tube observes the wavelength of Jovian (777 nm, FWHM = 1nm)or Venusian lightning(656 nm, FWHM = 1nm). The second photomultiplier tube simultaneously observes the background variation with the broadband alter, 700 nm (FWHM = 10 nm). We compare the light curves obtained by two PMT. If the PMT’s signal has a larger count value above the trigger level estimated by the noise amplitude, unlike the second PMT, the candidate waveform has been detected. From the data of observing Venus and Jupiter since 2021, several possible signals are triggered. We cannot rule out the possibility that all recorded light curves originate from noise or Cosmic rays. It might be disputable to conclude that we have detected lightning, but we compare it with the model for completeness. I compare it with a simple model and discuss it.
08/31 14:45--16:15 Konno Atsushi
Volcanic lightning can occur when volcanic eruptions are large. It is suggested that the charge separation mechanism in the volcanic eruption is different depending on the altitude. At the higher altitude, the electrical charges are generated by the collision of ice particles, while at the lower altitude they are generated by the collision of pyroclastic materials and silicates. In this presentation, I review the paper investigating the effects of the Hunga Tonga-HungaHa'apai (HT-HH) volcanic lightning on the DC and AC global circuits. The DC global circuit was measured by the variation of the atmospheric electric field at six observationsites, while the AC global circuit was measured by the variation of Schumann Resonance (SR) magnetic field intensities. In the case of HT-HH volcanic eruption, it is found that the lightning stroke rates peaked above 5,000/min which corresponds to the 50-60% of global lightning rates. The time variation of the SR amplitudes is well correlated with that of the lightning stroke rates estimated by the GLD360 and WWLLN lightning data. The atmospheric electric field was found to increase during the period of the most prominent electrification in the volcanic cloud approach the interpretation of atmospheric lightning from a different perspective. Although the responses of the DC and AC global circuits to the HT-HH volcanic lightning are identified, the detailed electrical properties, such as charge moment change (CMC), of the HT-HH volcanic lightning are not clarified. Thus, I will estimate the CMC of the HT-HH volcanic lightning using WWLLN and GLD360 lightning data and ELF data obtained at Kuju station in Japan. Then, I will compare the results of the HT-HH and Sakurajima volcanic lightning and will discuss the difference of the possible charge separation mechanism in these volcanic eruptions.
08/31 14:45--16:15 Nakajima Mizuho
Titan is a satellite of Saturn with a dense atmosphere of 1.5 bar at the surface. Titan's atmosphere, which contains organic matter, is known to have seasonal variations. Titan's tilt angle is about 27°, and seasonal variations occur with a period of one Saturnian year (about 30 Earth years). The concentration of haze in the stratosphere fluctuates with the seasons [Horst, 2017]. The Cassini spacecraft observed seasonal variations in stratospheric composition. In the summer hemisphere, the concentration of haze decreases due to decomposition of organic matter by sunlight. In the winter hemisphere, decomposition is suppressed and the haze concentration increases [Hotst, 2017]. The asymmetry caused by the difference in haze concentration between the northern and southern hemispheres has also been measured from ground-based observations. Titan's magnitude is greatest when the northern or southern hemisphere is at the winter solstice. However, the seasonal variation is decreasing in magnitude, and the cause is unknown [Lockwood and Thompson, 2009]. In this study, first and second purposes are set to observe Titan's atmospheric variability. The first purpose is to measure the amplitude of seasonal variations and contribute to the understanding of their causes. The second purpose is to clarify the response of Titan's atmosphere to energetic particles, and to reveal the atmospheric variability over shorter time scales than in previous studies. These two purposes will help to to understand the chemical reactions and dynamics occurring in Titan's atmosphere, and will lead to a better understanding of the primitive Earth's atmosphere, which is assumed to be similar to Titan's atmosphere. To achieve these goals, I plan to conduct long-term observations of Titan using the 1.6-m Pirika telescope owned by Hokkaido University.
09/07 14:45--16:15 Maeda Sota
Since typhoons are one of the most devastating disasters, it is important to estimate typhoon intensity. However, it is difficult to directly measure the intensity of typhoons because ground-based observations can only observe a portion of the typhoon, and aircraft observations are costly. Now, Dvorak method is a widely used typhoon intensity estimation method. Dvorak method was established based on data from a 10-year period during which satellite images of typhoons and aircraft observations were conducted simultaneously. However, the accuracy of tropical cyclone intensity forecast using this method has declined over the years. In this study, to improve the accuracy of typhoon intensity estimation, the vertical profile of clouds will be examined, since the Dvorak method only considers the horizontal direction of clouds. If the vertical profile is known, we can expect to be able to calculate the velocity of updrafts, which will lead to a quantitative understanding of cloud convection and, ultimately, more accurate intensity estimation. In order to consider the vertical profile of clouds, I used 3D models. From August 11 to 17, 2023, microsatellite from the Philippines, called DIWATA2, and a ground-based synchronous observation were used to capture clouds over Tokyo and converted them into 3D images. The image of the typhoon on September 29, 2021, taken by DIWATA2, was also converted to 3D in the same way. In the future, the vertical profile of clouds will be quantitatively determined from 3D models obtained from this observation, leading to improved accuracy of intensity estimation.
09/07 14:45--16:15 Tanka Taisei
Plastic waste is a significant environmental pollutant that is difficult to monitor. Plastics are a major pollutant impacting our planet. They are integrated into nearly all aspects of our daily life and are leaking into the environment. Plastic waste has reached the world’s highest points, deepest parts of the ocean, seafloor sediment cores, populated areas, remote islands, and rivers. In this presentation, I review the paper investigating the use of satellite imagery for direct and indirect detection of floating plastics in rivers, ultimately calculating river surface plastic densities. The direct detection was done using Worldview-3 imagery and enables to detect large objects (∼ 1.2 m of size). The indirect approach uses plastic entrapped in water hyacinths as a proxy for plastic density at the river surface. Sentinel-1 imagery allowed to estimate water hyacinth coverage, which we combined with field data to estimate entrapment ratio and plastic density within hyacinths. Items as small as 2.7 cm could be detected with field data. The indirect approach detects a thousand more plastic items (2.1×104 items km−2) than the direct approach (5.8 × 101 items km−2), a likely result of the larger range of item size detectable with this method.
11/02 14:45--16:15 Sugiyama Haruki
Heavy precipitation caused by well-developed cumulonimbus clouds is causing damage all over the world. In 2021, typhoons caused flooding in Manila and forced the evacuation of 150,000 people. In recent years, ``torrential rains,'' in which heavy rain falls over a short period of time, have been occurring frequently in Japan during the summer months, causing flooding of roads, paralysis of transportation systems, and power outages, which have a major impact on people's lives. Furthermore, the snowstorms that occur in Hokkaido during the winter are a problem that cannot be ignored. In order to deal with these problems, it is important to predict the development of cumulonimbus clouds as early as possible and take countermeasures before damage occurs. Atmospheric convection and the presence of water vapor are factors that cause cumulonimbus clouds. When a mass of air containing water vapor rises due to convection, the water vapor condenses and forms a cloud. Inside the cloud, the heat of condensation of water vapor creates a temperature gradient, which further strengthens convection. It takes about an hour for a convective cell several kilometers in size to grow into a cumulonimbus cloud (Saito and Suzuki, 2016). Radar and satellite observations and numerical simulations are currently being used to predict the growth of cumulonimbus clouds. However, these observational methods focus on capturing the moment when water vapor begins to condense in the atmosphere, and the time it takes for clouds to grow into cumulonimbus clouds is short. In addition, (Bryan et al., 2003) shows that calculations with a spatial resolution of about 100 m are necessary to predict mesoscale phenomena such as torrential rain from numerical calculations, but at this resolution, calculations are necessary. has not been sufficiently observed, and no practical predictions can be made. In this research, we will develop a method to observe the distribution of water vapor, which is one of the factors that generate cumulonimbus clouds, and improve predictions of cumulonimbus cloud development by capturing the movement of water vapor with spatial and temporal resolution, which has rarely been done before. The purpose is to Previous analysis of spectroscopic observations of standard stars showed that there is a strong relationship between the strength of water vapor absorption in the near-infrared region and the amount of precipitable water (Sugiyama et al., 2023 master's thesis). These results suggest that it is possible to elucidate the horizontal distribution of water vapor by using imaging observations in the water vapor absorption band and non-absorption band. We will use a ground-based all-sky camera system to capture local phenomena on the order of tens of kilometers, and multi-wavelength imaging observations from a satellite to capture phenomena on the order of 200 km. The observation wavelengths were 722 [nm], which is the water vapor absorption band, 761 [nm], which is the oxygen absorption band, as a standard for evaluating the absorption strength, and three bands with no absorption. Through this, we aim to elucidate the horizontal distribution of vapor on a time scale of several tens of minutes, which has not been observed so far. In this presentation, I will introduce the development status of the all-sky camera system and the initial analysis results of test observations using a satellite.
11/09 14:45-16:15 Enkhbayar Badamgarav
Forests play an important role in the carbon cycle and fixation. Forest carbon fixation is estimated depending on the forest biomass on the global scale. Remote sensing techniques can save time and cost for such large-scale surveys and generate large amounts of useful data. Remote sensing is widely used in forest research to estimate forest biomass, study species distribution and classification, and also predict forest disease conditions. Optical remote sensing is used for the above applications based on the spectral properties of the target. It is mainly used to study diseases and create distribution maps of species. As for the spectrum of forest trees, its spectrum will differ depending on the type of tree, and the same species will have a different spectrum depending on the age, growth and health of the tree. The main objective of my research work is to study tree growth and further changes in forest biomass and carbon sequestration based on the spectral differences of same species trees. Our university has several research forests of its own and has a rich database of many years of this forest census. Based on this, the growth rate of trees and the growth of carbon absorption will be studied in relationship with the measurement data made in the field and the spectral data of remote sensing. To achieve this primary goal, we first aim to develop reliable and robust methods for tree species classification from spectral data. During the past 1 semester, a total of 4 measurements were made in the forest of Hokuden company using 4-band cameras. 7 different tree species were distinguished using machine learning methods on this measurement data. In order to improve the classification accuracy and to develop the most reliable method, several different methods have been examined. The four band camera filters are chosen depending on previous measurement results and the reference studies. In order to distinguish different species spectral characteristics, 532 nm, 570 nm, 720 nm, and 770 nm bands were used for the 4 band camera. In this presentation, I will discuss current research progress and results in tree species classification as well as future work.
11/16 14:45-16:15 San Lin Phyo
Global climate changes are becoming worse as increasing of atmospheric concentration of greenhouse gases such as carbon dioxide (CO2), chlorofluorocarbons (CFCs), methane (CH4), and nitrous oxide (N2O). The contribution of each gas to the greenhouse effects is CO2 - 55%, CFCs - 24%, CH4 - 15%, and N2O - 6% [Demirbas, 2008]. [Demirbas, 2005] estimated that world carbon dioxide emission can be over 10000 million metric tons in 2025. In nature, forests, wetlands, grass, and croplands uptake carbon dioxide from the atmosphere in photosynthesis and store it for a long time. Wetlands soil carbon storage percentage is about 20% higher than forests ,65% than grass/shrub-lands [Liu et al., 2021]. Paddy fields are temporary wetlands and contain substantial CH4 emissions, contributing about 10% of all anthropogenic CH4 emissions [Nazaries et al., 2013]. However, [Liu et al., 2021] mentioned that the carbon storage of paddy soil is over 20% greater than other staple crops and grassland. Greenhouse gases (GHG) contribution from paddy fields changes at various condition and time. Although several research regarding carbon in paddy fields have been published, there are still limitation regarding estimation of the temporal variation of carbon fixation in paddy fields utilizing remote sensing. Therefore, the purpose of this research is to estimate temporal variation of Greenhouse gas (GHG) contribution from paddy fields. Furthermore, [ Cen et al., 2019] conducted dynamic monitoring of biomass of rice under different nitrogen treatments using dual image-frame snapshot cameras. This paper has shown that the quantity of nitrogen can affect on the above ground biomass (AGB) of rice field. Therefore, one of the objectives of this research is to create vegetation index (VI) that relates parameters which are influenced on carbon fixation of rice fields. In this experiment, the reflectance of three types of rice fields with different amounts of nitrogen was measured using spectrometer from mid-June to early September. And then, NDSI was calculated and estimated the relationship between NDSI and the nitrogen amount of each type of rice field based on linear regression method. In this seminar, the methods that were used for that experiment will be presented and the analysis results will be discussed.
11/30 14:45-16:15 Garid Zorigoo
Hyperspectral Imaging (HSI) devices are a bit hard to acquire compared to Multispectral devices. Consequently, both data analysis and usages of HSI aren't as mature and popular as multispectral technology, even though HSI might contain more delicate information about the target. With extensive HSI data, it may be possible to discover early-disease-detection or yield-estimation in a crop field. In this paper, we'll introduce our Spectral-Scanning-Device that is reasonably easy-to-reproduce and inexpensive; hoping to help other researchers acquiring HSI data. The price is approximately 1/50 or less compared to a typical HSI imager. In simple terms, our device is a spectroscope placed on top of 2-axes precisely controlled and monitored motors to log spectrum in a scanning motion. Due to initial data reconstruction of the device being shaped spherically, we named it Spectrosphere (combining 2 words Spectrum and Sphere). Currently, We're able to achieve scanning elevation angles from -50° to 10°, in all azimuth angles 0-360°, about 20-min. Our angular resolution is running average for 2x2 degree and plot at a step of <0.2 degrees; optical sensor’s wavelength range is about 400 to 800-nm. Currently, in our method, there are few pitfalls like change of sunlight during a scanning measurement (e.g. cloud movement hides the sun, etc.), and targets relative positions with the device (i.e. different reflection angle) may affect the uniformity of data. About the first one, we will discuss our calibration method with a reflector, and the second one is hinting towards a larger issue about reflection-angle affecting measurement satellites that can change their viewing angle. Besides technicalities, subjects like these will be discussed further down.
12/07 14:45-16:15 Ye Min Htay
The mismanagement of plastics and natural disasters leads to marine debris, causing stress on ocean ecology. In situ monitoring methods, such as toweling, have limited temporal resolution and large area coverage. Therefore, the researcher aimed to achieve precise detection and distribution (tracking the paths of sources and sinks) using remote sensing techniques. However, the current spatial and spectral resolutions have limitations in detecting plastic, as the missions of most earth observation satellites are focused on forestry, agricultural lands, and land changes. A new promising solution for plastics is being required to investigate the pollution problem. This research started with the basic spectral library documentation of different plastics and natural debris commonly found on beaches and in water environments, presented in this seminar. Although, the spectral libraries consist of hyperspectral data, providing remarkable insights, band selections are considered one of the most important methods to reduce redundancy in band dimensions, offering an effective approach in terms of data processing and cost-effectiveness. Therefore, a band selection method to discriminate materials and their corresponding classification method is presented in this seminar.
12/14 14:45-16:15 Hamamoto Ko
Venus is covered by thick sulfuric acid clouds extending from 50 to 70 km in altitude, which reflect about 80 % of the incident sunlight, but in the ultraviolet (UV) wavelength range, various patterns are observed due to absorption by SO2 and an unknown absorber. The unknown absorber contributes to about half of the solar heating in the Venusian atmosphere. The distribution and temporal variability of the unknown absorber are important basic information for understanding the Venusian climate system. Spectral observation of Venus in the UV wavelength range has been conducted by ground-based telescopes and spacecraft including MASCS/MESSENGER, SPICAV and VIRTIS/Venus Express. Perez-Hoyos et al. (2018) reported that S2O and OSSO’s UV absorption spectra, which are the unknown UV absorber candidates, showed the best agreement with MASCS UV spectral data which has 5 nm wavelength resolution, and emphasized the importance of the mid-high resolution spectra data in the regions of higher and lower UV absorption for providing constrain to the physical state of the UV absorber. Toward the identification of the unknown UV absorber at cloud top altitude of Venus, we developed Ultra Violet Spectrometer, which provides 2 nm wavelength resolution in 250 – 450 nm range with 4.3 and 6.3 arcsec field of view (FOV), and is equipped Pirka telescope, 1.6 m ground-based telescope. The observation goal is to get UV spectra of Venus capturing unique spectral features, for example S2O absorption features centered around 339, 346, 353, 360, 368 nm, in higher and lower UV absorption regions over Venus disk to provide constrain to UV absorber. Based on the goal, we targeted the March – July in 2022 and 2023 as observation periods with Venus diameter over 15 arcsec which can be separated equatorial and mid-high latitude regions by the UV spectrometer’s FOV, and collected UV spectral observation data in May 2022, May 2023.
12/21 14:45-16:15 Ono Tatsuharu
Monitoring planetary lightning would lend itself well for use by understanding atmospheric dynamics. Lightning is the electrical discharge phenomenon. Its activity correlates with atmospheric activity like convection due to its generation mechanism. The spacecraft has detected lightning on Jupiter through night-side optical imaging and radio wave observation, the same as Earth lightning observations. Previous studies suggested combining the many small-scale eddies driving the zonal jet by receiving their energy from moist convection that generates lightning (Gierash et al., 2000; Ingersoll et al., 2000). The moist convection would correlate with the jovian lightning, the same as Earth lightning. A possible signal originating from Venusian lightning was recorded by LAC onboard AKATSUKI on March 1, 2020 (Takahashi et al., 2020). If the Venusian lightning discharge is the signal's origin, the occurrence rate equals 2.7x10-12 s-1km-2, estimated by the ground-based telescope observation (Hansell et al., 1995). It could be helpful to reveal the Venusian atmospheric dynamics if we can monitor global Venusian lightning activity and distribution compared with other atmospheric information. Two-band high-speed photometers simultaneously observe the lightning with the ground-based telescope. We increase our observation time using ground-based telescopes to reach a consensus between the previous studies. By using the two-band photometers and high-speed photon counting, it is possible to distinguish between the lightning and variation of the planet disk's dayside brightness or sky brightness variation. We have developed the Planetary Lightning Detector (PLD) to observe the optical Jovian and Venusian lightning mounted on the 1.6-m Pirka Telescope. PLD has two photometers. The photomultiplier tube observes the wavelength of Jovian (777 nm, FWHM = 1nm)or Venusian lightning(656 nm, FWHM = 1nm). The second photomultiplier tube simultaneously observes the background variation with the broadband alter, 700 nm (FWHM = 10 nm). We compare the light curves obtained by two PMTs. If the PMT's signal has a more considerable count value above the trigger level estimated by the noise amplitude, unlike the second PMT, the candidate waveform has been detected. From the data of observing Venus and Jupiter since 2021, the signals are scarcely distinguishable from noise. We cannot rule out the possibility that all recorded light curves originate from noise or Cosmic rays. We compare it with the model, although it might be disputable to conclude that we have detected lightning. We are developing the planetary lightning observations model using the Earth lightning model (Luque et al., 2020). They developed the code for Earth lightning observations using satellites or the instruments mounted on the ISS. We compare it with the observed results by PH onboard JEM-GLIMS to evaluate itself. We analyzed the data to obtain the lightning altitude. Bandholnopparat et al., 2019 suggested that the intensity ratio of PHs shows us the difference between IC and CG. Their typical lightning altitude is different. The FWHM of lightning's light curve differs depending on the lightning's altitude. We can evaluate the model accuracy by comparing the ratio and FWHM estimated by the model and observed data by PHs. In this seminar, I will talk about the model development progress.
12/28 14:45-16:15 Miyajima Hideaki
(1)In the Philippines, there is a risk of flooding arising from heavy rains caused by monsoons. If rainfall can be predicted, damage from heavy rainfall can be reduced. The correlation between lightning frequency and rainfall has been investigated. A better correlation might be found if lightning energy could be estimated. Lightning was observed in Tokyo using infrastructure sound sensors at three locations. TDOA analysis using grid search was performed on the observed lightning events to estimate lightning locations. As a result, the estimated lightning strike location was calculated, but did not match the lightning information from LIDEN.
(2)Otobe Town has suffered damage from sea cucumber poaching. Otobe needs a security system. Determine the angle of the ship from the sensor using the time difference between the signals received by the ship from multiple sensors. In this experiment, the ship moved in the frontal direction as seen from the sensor. Therefore, we focused on 14 Hz and concluded that a small phase difference between the two sensors was a signal by the ship. The windshield is also being improved to further increase sensitivity.
2024/01/11 14:45-16:15 Yui Sho
n recent years, the development of cumulonimbus clouds leading to heavy rainfall and the resulting substantial damages have become significant societal issues in various regions, including Japan and Southeast Asia. However, accurate forecasting of these heavy rainfall events remains challenging both temporally and spatially. This difficulty arises from the fact that the spatial scale of cumulonimbus clouds triggering heavy rainfall is around several tens of kilometers, which is narrower than the spatial resolution of existing meteorological observation networks. In this study, the ultimate goal is to attempt heavy rainfall prediction using lightning in response to these societal demands. Frequent lightning discharges have been found to precede heavy rainfall with a temporal correlation of several tens of minutes. The observation methods for lightning include: Radio wave observation: Observing electromagnetic waves generated by lightning discharges. Acoustic wave observation: Observing the vibrations of air rapidly expanding due to the heat of lightning discharges. Quasi-static electric field observation: Observing changes in the atmospheric electric field associated with charge neutralization. Optical observation: Observing light produced by lightning discharges. For this study, acoustic wave observation and quasi-static electric field observation were conducted. In the capital of the Philippines, Manila, a total of 42 static field observation devices were installed at approximately 5 km intervals. The devices used in this study are plate-type capacitive antennas, known for their relatively low cost and easy maintenance. Simultaneously recorded changes in electric field at multiple locations were fitted using a model equation, enabling the estimation of neutralized charge amounts and their three-dimensional positions. The analysis focused on 45 cumulonimbus clouds that occurred from May 2023 to September 2023. The average neutralized charge altitude for each cumulonimbus cloud was 5900 m, the average normalized neutralized charge amount was 0.52, the average normalized charge moment was 0.52, the average difference between the precipitation area and the lightning occurrence location was 13.5 km, and the average time difference between precipitation and lightning occurrence was 12.7 minutes. Additionally, the change in neutralized charge altitude during the entire lightning occurrence period showed a 60% increase and a 40% decrease, with an average ascent rate of -0.18 m/s. In Bergen, the second-largest city in Norway, four acoustic wave observation devices were installed at approximately 20 km intervals. The devices used in this study are infrasound sensors capable of observing low-frequency sounds below 20 Hz, facilitating long-distance propagation. Observations were conducted during the winter period from November 2022 to March 2023 and the summer period from May 2023 to July 2023. Thunderwave observation times were estimated based on radio wave observations by the Norwegian Meteorological Institute, and values above the set threshold were considered as waveforms due to lightning strikes. The analysis results showed the observation of 7 thunderstorms in winter and 30 thunderstorms in summer. The estimated energy from these waveforms averaged 70 kJ in winter and 33 kJ in summer. The dominant frequency was around 7 Hz, followed by 3 Hz, and the average duration in the region with the strongest amplitude was 0.4 seconds. Additionally, there was one instance where it appeared that the same sound source was observed at three or more locations, and position estimation was conducted. This result showed a discrepancy of approximately 10 km compared to the results of radio wave observations.
2024/01/18 14:45-16:15 Jean De DIEU BYIRINGIRO
This seminar presentation delves into a comprehensive satellite-based analysis in Rwandan agriculture, focusing on coffee leaf rust detection and land cover mapping. Our study employs decision tree algorithms and the Normalized Difference Spectral Index (NDSI) while incorporating Landsat 8 imagery, presenting a dual-purpose solution for enhancing agricultural monitoring and land use classification. The research starts with the collection of Landsat 8 high-resolution multispectral satellite data covering coffee-producing regions in Rwanda, Maraba region specifically. The study combines the NDSI and decision tree algorithm, leveraging Landsat 8 bands, to classify land cover into distinct categories, including coffee plantations, wetlands, buildings, and forests. Results showcase the efficacy of NDSI, and decision tree model applied on Landsat 8 imagery in accurately identifying different land cover classes, offering valuable insights into the spatial distribution of coffee plantations and diverse ecosystems. This holistic approach significantly contributes to advancing precision agriculture practices in Rwanda, providing a flexible tool for farmers, policymakers, and environmentalists. The presentation will discuss the potential applications of this methodology, such as facilitating sustainable land management, monitoring urban expansion, and supporting biodiversity conservation efforts in the region.
2024/01/25 14:45-16:15 Konno Atsudhi
The volcanic plume of the HT-HH volcanic eruption spread horizontally and lightning discharges were detected by WWLLN and GLD360 to have occurred more than 140 km away from the crater. The charging processes involved in the generation of lightning discharges are very important because volcanic lightning associated with eruptions of Palikutin and Rabaul volcanoes have caused fatalities in the past [McNutt. and Williams. 2010]. Peak current values, polarity, and CMC of volcanic lightning generated at Sakurajima have already been studied. On the other hand, the form of HT-HH eruptions differs from that of Sakurajima. However, previous studies have not clarified the relationship between the amount of charge in HT-HH and the charge separation promoted by water vapor and the magnitude of the charge moment of the lightning discharge. Therefore, the purpose of this study is to compare the CMC, which represents the magnitude of individual volcanic lightning of HT-HH, with the CMC of Sakurajima volcanic lightning. The analysis of the CMC of HT-HH in this study shows that its scale and polarity are larger than those of Sakurajima by one order of magnitude and have opposite polarity. This is analogous to the differences in peak currents and other physical characteristics that are one order of magnitude larger and different in polarity when comparing thunderstorm lightning and Sakurajima. As a result, it is possible that the HT-HH charge separation method is not the same as the charge separation method of the Sakurajima plume, but is charged similarly to the charge separation caused by cumulonimbus clouds.
2024/01/25 14::45-16:15 Nakajima Mizuho
Titan, Saturn's sixth satellite, is the largest Saturn satellite and the second largest satellite in the solar system. Titan's atmosphere, like that of the Earth, has a layered structure consisting of the thermosphere, mesosphere, stratosphere, and troposphere. The haze layer in the stratosphere is optically thick and blocks observation of the surface. In the mesosphere to thermosphere, methane is ionized by high-energy particles and photolysis by sunlight. The ionized and dissociated methane proceeds through a process that produces solin (high-molecular-weight organic matter), which is a component of the haze layer. Three types of time variations in Titan's atmosphere are known. 1. Long time scale time variations: seasonal variations caused by Saturn's orbital period (about 30 years) 2. Variations caused by solar cyclic activity (about 11-year cycle) 3. Short time scale time variations: variations caused by Titan's orbital period (about 16 days) and tropospheric activity Saturn's equatorial tilt angle causes seasonal variations on Titan with a cycle of about 30 years. For example, variation in stratospheric temperature and composition, variation in the north-south asymmetry of the Haze layer, variation in the height of a part of the Haze layer, and tropospheric cloud variation. Solar cycles (about 11-year cycles) have been observed to decrease methane concentrations in the thermosphere when solar activity is high. Titan's orbit moves in and out of the plasma sheet of Saturn's magnetosphere, where the plasma density is large. Westlake et al. (2011) and Snowden et al. (2013) found that the temperature of Titan's thermosphere varies in and out of the plasma sheet. Despite the non-periodic variability, ground-based telescope monitoring campaigns and Cassini have monitored the tropospheric clouds for several days and found that they are moving. While variations in methane concentrations due to solar flux variations are known from fluctuations caused by solar cycle activity, the effect of solar flux variations due to orbital motion on methane concentrations has not been clarified. Short time variations due to plasma density changes have been observed, but methane concentration variations due to flux variations of energetic particles are not known. The tropospheric cloud monitoring campaign was conducted in the wavelength band where there is no methane absorption effect, so it was impossible to observe methane variations on a short time scale. In this study, I observed Titan's methane absorption wavelengths (619, 727, and 889 nm) using the 1.6-m Pirka Telescope at the Hokkaido University Observatory for six nights from September to November 2023. The reflectance of Titan at the methane absorption wavelength was analyzed with the results of one night of observations in 2021 and two nights in 2022. The reflectance at multiple points on the orbit was compared to investigate the variation caused by the orbit. 3 months of monitoring observations were conducted to investigate whether the variation was repeated during multiple orbits. I will clarify the time variations on short time scales caused by Titan's orbital period (about 16 days). I defined two indices, RR (Reflectance Ratio) and RDI (Reflectance Delta Index), to evaluate the magnitude of reflectance at methane absorption wavelengths. The analysis showed that the RR and RDI varied with orbital position. The reflectance of the methane-absorbing wavelengths became relatively small as the motion moved from the near- to far-Saturn points, and the reflectance of the methane-absorbing wavelengths became relatively large as the motion moved from the far- to the near-Saturn point. This trend suggests that the reflectance of methane absorption wavelengths may exhibit periodic short time-scale variations due to the orbital motion of Titan's atmosphere. I have two hypotheses for the mechanism of such variations. 1. As the solar flux decreased, photolysis slowed down and the amount of methane increased relatively. 2. High energy particles in Saturn's magnetosphere dissociated polymers in the haze layer and increased methane 3. The reflectance of methane absorption wavelengths changed due to the change in the altitude of the detached haze layer. This study was not able to test the hypothesis, and only nine nights of observations were analyzed. Future research should include a comparison with the model and further observations.
2024/02/08 14:45-16:15 Maeda Sota
Cyclones and torrential rains cause serious damage and sometimes death in the surrounding areas. So, predicting the intensity of typhoons and torrential rains is an important issue. Currently, the Dvorak method is the commonly used for predicting typhoon intensity. The Dvorak method determines typhoon intensity by looking at cloud formations as seen from above by satellite. As for heavy rainfall, studies have shown that higher cloud top altitude results in more rainfall. Therefore, in both cases, if the vertical profile of clouds can be determined, it may lead to typhoon intensity predictions. Satellite stereoscopy is one of the methods for determining cloud top height. In this study, in order to determine the relationship between typhoon intensity and vertical profile of eyewalls, images of Typhoon No. 16 (Mindulle) in 2021 and Typhoon No. 11(Hinnamnor) in 2022 were taken on several days using the Philippine microsatellite Diwata-2. In addition, to investigate the process of cloud development, which is an indicator of rainfall, images were taken at Tokyo from August 11 to 17, 2023, through synchronous observations of clouds by Diwata-2 and ground-based cameras. These images were modeled using Agisoft Metashape, a 3D modeling software, to create Digital Elevation Map (DEM) and determine the vertical profile. A comparison of the temporal variation of the cloud top height of eyewalls with typhoon intensity revealed a positive correlation of 0.56-0.79 in the Mindulle case. However, the absolute altitude was negative. In synchronous observations of clouds, the cloud top height obtained by Diwata-2 was 45.63 m, while the cloud top height obtained by ground observation was 51.4 m. Since cloud top heights are generally a few kilometers high, it can be concluded that absolute cloud top heights could not be determined from either observation. It is considered that the observation method should be devised.
2024/02/15 14:45-16:15 Amada Kotaro
Uranus is the planet which spins around its orbit at an inclination of 98 degrees with respect to its orbital plane. As of August 2023, the only close observations conducted in the past were during the flyby mission of Voyager-2 in 1985-1986. Apart from this, various observations is conducted using telescopes. Notably, heightened atmospheric activity has been observed around the vernal equinox, 2007. In observations conducted in the H-band (1.6 μm) by Keck telescope in the 2014, bright localized cloud were found to be brighter and exhibiting variations in size compared to other areas [Pater et al. in 2015]. These bright cloud are consider to be distributed within the atmospheric region at depth of 0.3-0.7 bar [Sromovsky et al., 2005]. In addition, from 2014, polar caps resulting from CH4 downwelling around the 1 bar level have been observed in the northern polar region [Toledo et al., 2018]. These polar caps changes in brightness around the 80° latitude region, observed between 2015 - 2023, by VLT(Very Large Telescope). This phenomenon is thought to be caused by the transport of the atmosphere from regions deeper than 1 bar [Akins et al., 2023]. Out of polar caps, there are seasonal variation in aerozol density and reflectance, but variation in short term (in one year) has been not clear yet[James et al., 2023] Both of these phenomena are deeply influenced by the vertical convection of Uranus’ atmosphere. Consequently, understanding the atmosphere of Uranus requires determining the vertical transport velocities of atmospheric components. In this study, I conducted observation with 1.6 m Pirka Telescope owned by Hokkaido University for Spectrophotometry and Spectroscopy of Uranus. Two different types of observations and analysis methods are conducted over a period of 1-4 weeks, which aimed at determining the temporal variations in absorption due to atmospheric constituents and aerosol reflectance. Ultimately, these efforts aim to estimate the vertical transport velocities. In this seminar, I will explain about the purpose and goal, observations and analysis method, result, and disccussion for them.
2024/02/22 14:45-16:15 Tanuma Yuta
In recent years, the increase in space debris has had a significant impact not only on space development but also on human activities. In order to reduce space debris, there is an urgent need to develop debris monitoring satellites and debris recovery technologies, but unfortunately, these are still in their infancy. Space Situational Awareness (SSA) is a guideline to prevent further increase of space debris, and my major goal is to contribute to SSA. I conducted optical observations using the Pirka telescope to estimate the rotation period of debris. The rotation period of FALCON HEAVY R/B launched in 2022 was estimated to be about 300 seconds by frequency analysis, while the rotation period of SL-12 R/B(2) launched in 1993 was estimated to be about 100 seconds. The reason why multiple rotational periods of SL-12 R/B(2) were found is that it has been about 30 years since its launch, and the rotational motion may have become more complicated. In the future, I would like to observe not only large objects such as rockets but also small debris, and at the same time, I would like to conduct further observation and analysis of the surface materials of debris.
更新：田沼雄太 2024/03/08