06/07 14:45 -- 16:15 Kubota Hisayuki
What is climate? It is a basic state of daily weather and seasonal march. In this talk I will introduce climate studies focusing on Philippines. Three keywords of “low latitude”, “monsoon” and “typhoon” are chosen to explain the climate in the Philippines. In low latitude region, climate is strongly influenced by the elevation angle of solar insolation. The excess of solar insolation generates global circulation. One of the major circulation is “monsoon”. Land-sea contrast triggers seasonal change of wind direction and rainfall. Typhoon is also a key player which transports heat from low latitude to high latitude. About 20 typhoons influence Philippines in a year which counts highest number in the world. Some studies using these three keywords are introduced in the talk.
06/14 14:45 -- 16:15 Kittanapat Bandholnopparat
The ratio between intracloud discharge (IC) and cloud-to-ground discharge (CG), denoted by Z, is an important parameter for the studies on the severe weather prediction, the production of NOX by lightning discharges, and the quantitative contribution of lightning to the global circuit. However, the difficulties of Z-value estimation in previous studies are originated in (1) the ground-based lightning data obtained at limited and specific areas, (2) difficulties in detecting IC discharges, and (3) difficulties in distinguishing the discharge types (IC or CG) in the previous space observation data. So, the latitudinal and regional dependence of Z-value is not resolved yet. Consequently, we have developed new methods to distinguish the discharge types (IC and CG) using both optical data from the Global Lightning and Sprite Measurements on Japanese Experiment Module (JEM-GLIMS) and ground-based lightning data obtained by the Japanese Lightning Detection Network (JLDN), the National Lightning Detection Network (NLDN), the World Wide Lightning Location Network (WWLLN), and the ELF data from Syowa and Kuju station, in the period from November 2012 to August 2015, to estimate Z-value. These lightning events were detected over both land and oceanic regions from latitude 51 degrees south to 51 degrees north. The Z-value over this region is 0.11 ? 1.28 with the average value 0.70. A correlation was found between Z-value and latitude(; coefficient of determination 0.628).
06/21 14:45 -- 16:15 Kurihara Junichi
Planet disease detection by using hyperspectral imaging sensors is studied for a wide variety of agricultural plants from leaf to field scales. However, it is still challenging for hyperspectral imaging to detect diseases in early stages, when their symptoms are small or invisible. We started a collaborative research on disease detection by hyperspectral imaging for adzuki bean, with Prof. Kondo, Plant Pathology Laboratory, Research Faculty of Agriculture, Hokkaido University. Recently, a bacterial disease of adzuki bean has been spread in Hokkaido. It is important for prevention of the spread to detect the disease in the early stage. The purpose of this study is to develop an early detection method based on a machine learning for the adzuki disease in leaf and plant scales by hyperspectral imaging with the LCTF camera, for future UAV and satellite remote-sensing of the adzuki disease.
06/28 14:45 -- 16:15 Begzsuren Tumendemberel
Total reflectance of a leaf is a product of reflectance of the waxy cuticle, reflectance of inside structure, and pigment scattering. Although a structure of most leaves has several layers, light reflectance strongly depends on the optical property of top waxy cuticle at shallow view angles. We are focusing on angle dependence of the reflectance of the leaf in this study. Spectral images of Coffea canephora Pierre, Epipremnum aureum, and Fragaria ananassa are taken by Liquid Crystal Tunable Filter (LCTF) camera with rotating linear polarizing film at mirror angles on automatic goniometer system. The advantage of using an image of the multispectral camera is able to crop surface area of a leaf and that means it is possible to select an arbitrary size of the field of view. This kind of measurement setup produces an error less than a spectroradiometer. We measured pigment concentration by SPAD-502plus chlorophyll meter which is calibrated with chemical analysis so that correlation coefficient is higher than 90%. Parallel and perpendicular reflectance of a leaf are separated by spectra-polarimetric measurement. The result showed that new leaf has lower chlorophyll concentration and higher refractive index than the old one. These indicators lead to reflectance model of a leaf which consists of two optical layers-transparent layer and structure layer. This simple model shows an almost same spectral signature and explains bidirectional reflected light on the plants.
07/05 14:45 -- 16:15 Ade Purwanto
One of the challenge of the space imaging technology is to obtain an accurate spectral signature of an object from off-nadir angle. The greater the angle from the normal angle, the higher the challenge, especially with the mirror angle between the light source and the sensor. In this case, polarization becomes an important variable to be considered. This presentation will presents an empirical study of the polarized-light phenomena under laboratory condition, using a Liquid Crystal Tuneable Filter (LCTF) camera with a linear polarizer filter attached on front of its lens and were rotated to obtain the degree of polarization (DoP) of the target. The instrument was capable to capture the spectrum from 460nm to 780nm with the step of 1nm. This camera was chosen so that the detail of the spectral signature of the target can be captured and a more accurate indexes analyses and other spectra-related calculations can be acquired. Moreover, because LCTF camera is an imager, any pixel can be chosen to be analysed. A type of Coffea Arabica was observed in a dark-room laboratory. The experiment was focused to capture the DoP and the specular reflectance from the surface of a leaf, thus the angle between the light source and the sensor was set to be always in a mirror angle. Results show that a drought-stress plant could be distinguished through the characteristic of the polarization on its leaves. The specular noise on the reflectance of the leaves was having the characteristic of the light source, with the scale linear to the incident angle. Optical characteristic of the polarized-light is one of the key component understand a vegetation cuticular condition, and in a broader range, the terrestrial canopy.
07/12 14:45 -- 16:15 Quach Trung Dong
Living corals have many different colors, such as brown, purple and green, but this color is actually the color of microscopic single-celled algae called zooxanthellae living symbiotically inside the body of the coral.When the environmental conditions are altered and the stress placed upon the coral, it will expel either its symbiotic zooxanthallae or experience a decrease in photosynthetic pigment concentration within the zooxanthallae. This event is called coral bleaching cause a loss of color since the coral tissue become translucent without its pigment. Coral bleaching is now considered as a global problem but it's not fully monitored and estimated because most remote sensing studies are based on in situ data, kite photography and aerial photography at a relatively small partial scale while satellite remote sensing can cover a larger area but it also has a lot of limitations such as optical similarity of reef features, limitation in the spatial and spectral resolution of the sensors or some current detection methods can not be used for all data and region. In Vietnam, due to suitable conditions in the humid tropical region, coral reefs develop very well with their distribution stretch along from North to South areas. The increase of coral bleaching in both frequency and extent worldwide in the past 20 years requires Vietnam has to monitor and assess the bleached coral regularly. The aim of my research is to d detect coral bleaching in the coastal area of Vietnam by using some cheap and available image sources such as Landsat 8 and Sentinel-2. In this EOU seminar, I would like to show my whole process and some results from analysing Landsat 8's images.
07/19 15:00 -- 16:30 Nguyen Thi Thu Hanh
The number of beaching seaweed events are recognized worldwide as a response to increased levels of nutrients in coastal areas. The seaweed blooms have led to the negative impacts on aquatic resources, fisheries, waterway, and tourism. After the world’s largest macroalgal bloom (green tide) in 2008 in China, the approaches to monitoring, control, and management of macroalgal blooms were heeded the public opinions. The origin of Ulva prolifera which formed the green tide was indicated to the Subei Shoal from remote sensing, ocean circular models, and field survey. After harvesting the P. yezoensis, the U. prolifera would have been removed from the aquaculture rafts. The detached algae were driven by wind and current under the favorable oceanographic conditions can add huge biomass and move large distances then causing significant damage far away from their original sources. The green tide has become an annual nuisance in Yellow Sea (YS). But there are smaller floating algal blooms were recurrent in East China Sea (ECS) not only in YS. Because green tide of the same macroalgae may occur in both YS and ECS in the future. It is desirable to study in both regions for the insight of relationship between environmental factors and interannual variability in Ulva blooms. The Floating Algae Index (FAI) is a robust algorithm to detect floating algae due to their less sensitivity to change in environmental and observing conditions. It was used for detecting and quantifying the algal bloom. Most of the studies focused on the detection of Floating algae and area coverage. The effect of environmental factors such as temperature, salinity, and irradiance on growth and biomass of floating algae is still not clear. In this study, I investigated the algae coverage, start time, and time duration response to the sea surface temperature (SST), salinity, and photosynthetically active radiation (PAR).
08/03 14:45 -- 16:15 Imai Masataka
Venus has a global cloud layer whose thickness exceeds 30 km, and the atmosphere rotates with the speed over 100 m/s from east to west. The scattering of solar radiance and absorption in clouds cause the strong dark and bright contrast in UV range. Since the orbit insertion in December 2015, the Japanese Venus orbiter AKATSUKI continues to monitor cloud features having various spatial scale size in 283 nm SO2 and 365 nm unknown absorption bands. Depending on the AKATSUKI's highly elliptical orbit with 10.8-day period, the spatial resolution ranges from ~50 km to ~5 km in the equatorial region, and UVI can capture ~100 km mesoscale cloud features over the entire visible dayside area. In contrast, the planetary-scale feature, which is often represented as Y-feature, is simultaneously observed when the orbiter is at the moderate distance from Venus and when the Sun-Venus-orbiter phase angle is smaller than 45 degree. At the previous exploration of Venus Express, cloud top wind velocity was measured with the cloud tracking technique using the mesoscale cloud motion. This approach is widely used, and the long-term trend of wind velocity is being revealed. However, at the same time, observations of the propagation velocity and its variation of the planetary-scale feature are not well conducted because of the limitation of the observable area in the dayside. In this study, we use the ground-based telescope named Pirka and revealed the periodicity change of planetary-scale waves with a time scale of a couple of months. It is considered that the motion of the planetary-scale clouds is related to the atmospheric planetary-scale waves, and the contribution of the waves to the wind acceleration would be a key parameter to solve the generation mechanism of the mysterious super-rotation. The purpose of this study is to clarify the motion of mesoscale and planetary-scale cloud features simultaneously using AKATSUKI UVI images. Each cloud feature can be represented as the wind and phase velocity of the planetary-scale waves, respectively. For the initial study, we used the time-consecutive and well spatially resolved UVI images taken in the orbit #32. During this orbit (from Nov. 13 to 20, 2016), 7 consecutive images were obtained in a dayside with ~2 hr time-interval between the images and with the spatial resolution ranged from 35 km to 10 km. To investigate the typical spatial scale dividing the mesoscale and planetary-scale motion, the Gaussian-filters with sigma = 1-, 3-, 5- and 8-deg. were used to smooth geometrically mapped images, which were produced by projecting the original UVI images with 0.25 deg. resolution using the Akima interpolation. Then the mapped images were divided into 15 x 5 deg. (lon x lat) sub-images covering N50--S50. The amount of longitudinal shift between each pair of two time-consecutive bands was estimated by searching the 2D cross-correlation maximum. The final wind and phase velocity (or rotation period) for mesoscale features were determined with a small error about ± 0.2-day period. In the case of planetary-scale features, they still were not well determined because of the unnatural correlation peak, and it was necessary to exclude the low contrast sub-images manually especially when the larger sigma at the Gaussian-filter and sub-images of higher latitudes were used. However, the visual inspection of the figures, which arrange sub-latitudinal images smoothed by the 3-deg. filter in the vertical direction (as shown in Figure 1), clearly showed the velocity deviation between the mesoscale and planetary-scale motion. At the EOU seminar, the detail methodology of our new analyses using UVI images and the initial results of the velocity deviation will be presentated. The time variation of the velocity deviation with the time scale of a couple of months will be investigated soon. The phase velocity of the planetary-scale features can be compared with the results derived from our ground-based simultaneous observations using the Pirka telescope. Based on the previous results, the prospects in the near future will also be shown.
08/09 14:45 -- 16:15 Ellison Caparas Castro
Strong Hurricanes have been damaging livestock and communities. Projecting the path of hurricanes for better forecasting has been successful, however, the strength of the hurricanes are less likely predicted. Hurricane strength had been correlated with lightning activity; with the lightning activity peaking a day before the peak of hurricane strength. Lightning, on the other hand, is related to the electrical activity of a cloud, or storm. This electrical activity has been related to a cloud's behavior; the cloud needs to grow rapidly and reach a height of at least 9 kilometers to produce lightning. In which case, it is possible to forecast hurricane strength by the cloud's growth activity. In this presentation, three-dimensional reconstruction of clouds, using DIWATA-1 data, is proposed as a methodology for estimating the vertical growth of clouds.
MM/DD 14:45 -- 16:15 Ono Tatsuharu
Jupiter is gas giant planet. One of the jovian feature is stripe. The stripe is called band structure. The band structure consist of east-west zonal jet. There are many theory to explain how to form the zonal jet. However, the debate is continuing. There is one theory that the zonal jet is formed by coupling small-scale eddies [Gierasch et al., 2000; Ingersoll et al., 2000]. The small-scale eddies exists with cumulonimbus. From the observation the cumulonimbus, the information of small-scale eddies can be provided indirectly. The intermittency of cumulonimbus would be similar to of small-scale eddies. My purpose is understanding the formation mechanism of Jupiter's zonal wind maintained by small-scale eddies. To know the distribution and intermittency of small-scale eddies, I observe the cumulonimbus and obtain the intermittency and distribution of them. I observed the Jupiter from January 8 to June 30. In this presentation, I will show the results of observation and introduce the analysis procedure and their results.
08/30 14:45 --16:15 Futamura Yuki
The cloud has a great influence on the energy balance of atmosphere. And in the Earth, there are the cloud of droplet, of ice crystal and of mixture. They have each effect, e.g., sublimation and evaporation.That means it's important to know the state of cloud. Moreover, If we know the presence of ice crystal, we could estimate the temperature. Or in addition if we know the temperature with another method, like IR camera, we could estimate which subject is it or its concentration and the thermal cycle from different temperature of each place. To analyze the presence of ice crystal in the Venus, I do the polarimetry observation using the Pirka telescope of Hokkaido University. I use this method because there are the different feature between ice crystal and droplet in polarization, particularly at 158° and 134° of phase angle, which caused by halo phenomena of 22° and 46° of scattering angle. And utilizing the advantage of Pirika telescope that we can use the wavelength which we need, I detect the dependence of wavelength which is found by previous research but not solved(Können et al., 1993).
09/07 14:45 -- 16:15 Niwa Shunsuke
This paper present a new method for quantifying the main tropical thunderstorm regions based on extremely low frequency (ELF) electromagnetic waves observation from a single station -the Hylaty ELF station in Central Europe. The approach is based on Schumann resonance (SR) measurements, which is applied as an example to thunderstorms in Africa. Distances to the most powerful thunderstorm centers are calculated and simplified 1-D thunderstorm activity maps with spatial resolution of 1°and temporal resolution of 10 min for January and August 2011. This allows us to study the varying location and intensities of the African storm centers in different seasons of the year. A cross check of the obtained lightning activity maps with Tropical Rainfall Measuring Mission satellite data recorded by the Lightning Imaging Sensor and the derived correlation coefficients between SR and optical data were used to validate the proposed method.
09/2 14:45 -- 16:15 Sato Yuuki
Neptune is the eighth planet of the solar system. Its atmosphere is mainly composed of hydrogen and helium. A small amount of methane is also present. Prominent absorption bands of methane exist at wavelengths above 600 nm, in the red and infrared range of the spectrum. On June 26 and July 2 2017, a large-scale storm was observed by the Keck Observatory on Mauna Kea, Hawaii. Such a huge storm has never seen near Neptune’ equator. The diameter of the storm is 9,000 km (1/3 of Neptune’s radius), and the diameter of Neptune is 49,529 km. So the area of the storm accounts for 3.3% of a disk of Neptune. It is expected that a spectrum of Neptune is changed by the effect of the storm. My purpose is to find out the spectrum variation of Neptune by the storm. I observe Neptune by using Pirka Telescope in Hokkaido University.