06/22 14:45--16:15 Masataka Imai
A planetary-scale bright and dark UV feature, known as the "Y- feature," rotates around Venus with a period of 4-5 days and has been long-time interpreted as planetary waves. When assuming this, its rotation period and spatial structure might help to understand the propagation of the planetary-scale waves and find out their role in the acceleration-deceleration of the zonal wind speed, which is essential for understanding the super-rotation of the planet. The rotation period of the UV feature varied over the course of observation by the Pioneer Venus orbiter. However, in previous explorations of Venus such as Pioneer Venus and Venus Express, the spacecraft were operated in nearly fixed inertial space. As a result, the periodicity variations on sub-yearly timescales (one Venusian year is ~224 Earth days) were obscured by the limitations of continuous dayside observations. We conducted six periods of ground-based Venus imaging observations at 365 nm from mid-August 2013 to the end of June 2014, over three months observation from mid-April to the end of July 2015, and two times monthly observations in September and December in 2015. Distributions of the cloud top relative brightness were obtained from the equatorial (EQ) to mid-latitudinal regions in both hemispheres, and from the cyclical variations of these distributions we deduced the rotation periods of the UV features of the cloud tops brightness. The relative brightness exhibited periods of 5.2 and 3.5 days above 90% of significance. The relative intensities of these two significant components also seemed subject to temporal variations. Although the 3.5- day component considered persists throughout the observation periods, its dominance over the longer period varied in a cyclic fashion. The prevailing first significant mode seems to change from 5.2-day waves to 3.5-day waves in about nine months, which is clearly inconsistent with the Venusian year. Clear periodic perturbations, indicating stability of the planetary-scale UV-feature, were observed only in the presence of single longer or shorter periodic waves. During the transition periods of dominant-wave changing, the amplitude of the relative brightness was largely changed. This can be explained by the deformation of the Y-shaped UV feature as observed by Pioneer Venus in 1979. Additionally, by summarizing the results of the relative intensities of two significant waves, we success to obtain some cyclical change in two waves dominance. In this seminar, I will present those variability in Venus dynamics and further observation plans using data from Japanese Venus exploration “AKATSUKI” (Venus Climate Orbiter).
06/29 14:45--16:15 Yukihiro Takahashi
The prediction of typhoon location has been successfully improved for these 20 years. However, its intensity, that is, maximum wind velocity near eye is difficult to make forecast. This is because the energy input from ocean to the atmosphere is not easy to observe. It was found in the last decade that the lightning activity is an excellent proxy of the energy input. Though its exact reason has not been confirmed, the most probable scenario is that the energy input occurring near the edge of typhoon area induces thunderstorm and lightning discharge. A part of the energy input to the atmosphere as latent heat approaches the center due to the low pressure. Since it takes one or two day(s) from the edge to the center, we could predict the maximum wind velocity caused by the release of the latent heat near the eye one or two day(s) before. Based on this assumption we plan to establish the way of prediction for the intensity of typhoon, using the ground based lightning detection networks which will be constructed or improved during our SATREPS project as well as the 3D imaging with micro-satellite.
07/06 14:45--16:15 Ngo Duc Minh
Climate change related to emission of greenhouse gas from human activities is the most important environmental problem of twenty-first century. Such climate change maybe influence to marine ecosystems through extreme weather events like El Nino Southern Oscillation (ENSO), or monsoon causing damage on both fishery and aquaculture. Therefore, the relationship between climate events such as Monsoon, ENSO) and the variation of marine environment can be used as a proxy to access the damage of climate change on marine ecosystems. However, the mechanisms linking climate events and ecosystem change depend on geographical features, and are difficult to identify due to the synergistic effects of multiple climates and stressors. To understand the response of marine ecosystem to variation of climate events, satellite remote-sensing data, in-situ observations, and climate indices data in Southwest Sea Vietnam and South-central Sea of Vietnam are combined to examine the patio-temporal distribution of environment factors for a long period (2002-2012). Beside that, statistical analysis was also implemented to test whether the relationship between paired factors. These analyses proved that the dynamic of marine environmental factors were strongly correlated with monsoon activities.
07/13 14:45--16:15 Vi Duc Huan
Due to the fact that aerosols play an important role in radiative forcing, numerous satellite aerosol products have generated as the results of increasing attention paid to aerosols in climate studies. As for aerosol over Vietnam ocean, aerosols of this region are very complex due to it results from both anthropogenic and natural sources. Therefore, the aerosol retrieval over such region is difficult because of complex aerosol composition and aerosol properties. In this study, new aerosol models based on local aerosol properties derived from the inversion products of AERONET sites in Vietnam. The aerosol retrieval method uses Look-up table approach. The table is build by using the new aerosol models and polarized reflectance (670nm and 865nm) to improve the accuracy of retrieved aerosol optical depth (AOD) and classify aerosol type. The retrieval will be applied into the future Vietnam satellite named MicroDragon that will be launched in 2018.
07/20 14:45--16:15 Junji Miyazawa
The Martian atmosphere was warm and high pressure several billions of years ago[Carr, 1999]. The Martian atmosphere is dry and low pressure (636 Pa)[McKay and Stoker, 1989; Kerr, 2000; Baker, 2001]. Although about 95% of Martian atmosphere is CO2, about 90% of escaping atmosphere is oxygen (O, O+) from the observation by Mars Express[Lundin et al., 2009]. Oxygen escape may be important for the evolution of the water of Mars. Mars does not have a significant internal magnetic field. The solar wind can penetrate to the Martian ionosphere altitude and interact with the Martian ionosphere [Acunã et al., 1998; Lundin et al., 2004]. Then, ionopause and bow shock are formed, and oxygen ion escape is strongly affected by the solar wind. The structures of ionopause and bow shock are important for oxygen ion escape. The important escape mechanisms of Martian atmosphere are Dissociative Recombination, Solar Wind pick up and Sputtering. The previous models do not include the effect of the collision of the escaping particles with the atmospheric particles and the escape of the collided secondary particles. Then, I constructed a model including dissociative recombination, solar wind pick up and spattering processes, and investigated the amount of the atmospheric escape from Mars. I calculated the solar wind interaction with the Mars ionosphere with Magnetohydrodynamics equations and particle model of Oxygen, and I found that the solar wind conditions around Mars control the escape flux of Oxygen in Mars.
07/27 14:45--16:15 Kaye Kristine Vergel
Remote sensing has been widely used in assessing damages from disasters. Compared with field surveys, it is a cost-effective tool. In a year, around 18 to 19 tropical storms enter the Philippine area of responsibility, 7 to 9 of which make landfall in the country. Given the large frequency of storm passing in the country, analysis of storm damage to agriculture is of great demand. There are two types of factors that contribute to the damages brought by a storm’s passing, [1] intensity of the typhoon and [2] characteristic of the areas hit. The typhoon’s intensity can be described by rainfall and wind velocity. On the other hand, elevation and land cover characterizes the area to be hit. In this seminar, the damages brought by two typhoons will be discussed. The storms Haiyan and Koppu have hit the provinces of Leyte and Nueva Ecija, respectively. Using the Normalized Difference Vegetation Index and Normalized Difference Infrared Index, we found a decrease in value after the storm’s passing which can be attributed to the damage caused by the typhoon. The damages are also correlated with the land cover of the provinces and as well as to elevation. Rainfall data with resolution of 10 km is also correlated with the measured damages.
08/03 14:45--16:15 Chiharu Shimizu
Lightning discharges usually occur within active thunderclouds, and previous studies suggested that there are close relations between lightning activities and severe meteorological phenomena. However, in these studies, only the occurrence frequencies of lightning discharges are considered to estimate such relation. As lightning is a discharge phenomenon, it is more important to investigate the relation between electrical properties of lightning discharges, such as polarities, peak currents, and charge amounts, and the meteorological parameters of the severe weather. In order to measure the lightning currents and to estimate charge amounts, induction magnetic coils named as Rogowski coils installed at tall towers are generally used. However, such Rogowski coils can measure only the lightning discharges directly hitting the towers. Recently, it is shown that the ELF magnetic field waveforms measured at the 300 km distance from the lightning is comparable to the lightning current waveforms. Therefore, the charge amounts of any lightning discharges occurring within the area where the induction magnetic fields are measured can be easily estimated from ELF waveforms by quantitatively evaluating the relation between ELF waveforms and the current waveforms. In this study, the lightning current waveforms measured by a Rogowski coil installed at Mt. Ogami and ELF waveforms measured at Onagawa observatory are analyzed. From these quantitative analyses, empirical equations that enable us to directly convert from the magnetic field intensities into the charge amounts were obtained. Using ELF waveform data obtained at Kuju station in Kyushu and lightning data of the Japan Lightning Detection Network (JLDN), charge amounts for the lightning discharges occurring when downbursts were confirmed in Japan are estimated by applying the empirical equations. Furthermore, echo-top heights observed by the JMA c-radar at that time were analyzed. At the presentation, we will show the results and discussed.
08/10 14:45--16:15 Benjamin Jonah Perez Magallon
Banana Industry in the Philippines plays a big role in the country's economy. Currently, the country is third in the world's top producers of banana. Davao del Norte, located in Mindanao, is the source of almost 50% of the country's production. Recently, the province has experienced a rapid decrease of banana plantation area and it is attributed to the presence of infestation called 'Panama Disease'. Because of the infestation, the region has loss a huge part of the plantation area and million dollars of profit. With these events, the need for finding a way in monitoring the plantation and the spread of the disease arises and one of the method that could be used is Remote Sensing. In this study, Landsat 7 and 8 Images of Davao del Norte are processed for creating detailed classified vegetation map of the region and in calculating the general trends of the Banana Plantation in the region by looking at three vegetation indices: NDVI, NDWI and GRVI.
08/31 14:45--16:15 Ade Purwanto
Although polarization and spectral information utilization has been received great attention with the sensor and detection technology advance, few results are showed to jointly utilize both of this information in targets classification. Polarization and spectral information reveals two different aspects of one single target, and therefore, if both of information is properly used, good performance would be achieved in the classification. (Chao et al, 2007) In this presentation, initial experiment to discover visually how polarization of light happens on leaf surfaces will be explained. The experiments were unique yet simple, however, the finding should be very useful to understand the phenomena of polarized light. Object of the experiment is coffee plants with the age around 1 to 1.5 years. Instruments are the polarimeter camera from Photonic Lattice, an LCTF camera developed by Hokkaido University, and a polarizer wheel. Several findings can be discussed as a possible probe to acquire a “true spectra”, from mean leaf angle until the average degree of polarization derived either from the single leaf, or a tree.
09/07 14:45--16:15 Tatsuharu Ohno
The Great Red Spot’s color has varied. The Great Red Spot is one of the feature of Jovian atmosphere. In January 2015, Hubble Space Telescope observed the Jupiter for Outer Planet Atmosphere Legacy program. This program is generating new yearly global maps for each of the outer planet. The data from this program show the Great Red Spot’s color has varied compare to the data in 2014. This variation will be caused by the wind velocity field variation. The Vertical convection with cumulonimbus will cause the window velocity variation, too. So that, there may be a correlation between the GRS internal wind velocity field and cumulonimbus. This relation may reveal the effect the vertical convection for the large-scale structure on Jupiter. In this presentation, I’m going to introduce my study and future work.
09/21 14:45--16:15 Tsuyoshi Sato
Transient Luminous Events (TLEs) are transient discharge emission phenomena that are accompanied by cloud-to-ground (CG) discharge in the stratosphere and the mesosphere. In recent previous studies, global distribution and occurrence rate of lightning and TLEs were estimated, however they don’t reflect local time (LT) dependency. We use the Global Lightning and sprIte MeasurementS on JEM-EF (JEM-GLIMS) onboard the International Space Station (ISS). JEM-GLIMS can observe lightning and TLEs at the range of 19-4 LT. We estimate the global distribution and occurrence rate of lightning and TLEs (sprite and elves) and the dependency on season, month and LT. From December 2012 and November 2014, JEM-GLIMS recorded 4946 lightning, 549 TLEs, 35 sprite, 409 elves. The occurrence rate of lightning, TLEs, sprite and elves are estimated 93.3, 10.4, 0.66 and 7.71 events/min, respectively. Lightning and TLEs concentrate over the African Continent, Southeast Asia, and Central America. The seasonal maximum of occurrence rate of lightning is summer, and that of TLEs is winter. The occurrence of TLEs on July is less than other months. Both lightning and TLEs occur frequently around 20LT and 3LT.
09/14 14:45--16:15 Quach Trung Dong
Coral reefs are considered to be among the most biologically diverse ecosystems on Earth. They have much higher gross primary productivity than the surrounding ocean. Thus, the information on the status of coral reefs is crucial for marine habitats' conservation and sustainable utilization. However, coral reefs ecosystems are particularly sensitive to climate-induced changes in the physical environment. Since the 1980s, coral reef bleaching has had devastating and widespread effects worldwide. In this seminar, I will introduce some information about the coral bleaching event as well as some previous studies on the detection of coral bleaching. Based on that, I would like to show my study's purposes and plan.
09/14 16:30--18:00 Nguyen Thi Thu Hanh
Space-borne remote sensing have been very effective and successful tools for monitoring water bodies, particularly the open ocean waters. However, monitoring coastal waters has been more difficult and challenging than monitoring open ocean waters because of the optical complexity of the coastal region. The accuracy of the extracted information of obtained satellite images was reduced and not robust due to the coarse spatial resolution and the limited range of the spectrum. Using the data from the Hyperspectral Imager for coastal Ocean (HICO) and apply the new algorithm six-band algorithm- the first time for space-born sensor- could be possible to increase the accuracy of deriving Chlorophyll-a concentration. In my research I also want consider the effect of the bottom surface to retrieve the Chl-a concentration.
09/28 14:45--16:15 Begzsuren Tumendemberel
Modern multispectral satellites are able to take an image observation in arbitrary directions using an altitude determination control system (ADCS). Parameters of remote sensing are calculated based on the spectral reflectance that strongly depends on the combination of the sunlight incidence and observation view angle of the satellite camera. In this study, Parameters of normalized difference vegetation index (NDVI), green red vegetation index (GRVI), and MERIS total chlorophyll index (MTCI) are estimated for bidirectional distribution reflectance function (BRDF) on healthy leafs of pothos lima and coffee plant. Spectral radiances in six different view directions are measured by liquid crystal tunable filter (LCTF) camera and grating based spectrometer in a laboratory using a half automatic goniometer. This measurement equipment has a rotating linear polarizer and quarter circle light source axis. in this measurement, axises are normally adjusted that polarizer is rotated from 0 to 180 degrees, with a step of 7.2 degrees and the light source incidence zenith is moved from 90 to 15 degrees, with a step of 5 degrees. An example result is that relationships between incidents angle and the vegetation indexes (NDVI and GRVI) are not constant. The values of NDVI and GRVI at incidence angle 15 degrees is almost 20% higher than a value of the 90 degrees in the case of nadir view.
09/28 16:30--18:00 Kittanapat Bandholnopparat
The intra-cloud (IC) to cloud-to-ground (CG) ratio (Z=IC/CG) is important and has huge impact for the future studies on the severe weather prediction (hurricane, tornado, heavy rain, etc.). It is also very important for the study on the global circuit model. However, there is no clear answer of the Z ratio and its latitudinal dependence in global scale. Therefore in this study, the researcher would like to find the relation of Z ratio and geographic latitude. The analysis of the Z ratio over the global has been performed using Global Lightning and Sprite Measurements on Japanese Experiment Module (JEM – GLIMS) and The U.S. National Lightning Detection Network (NLDN) from November 2012 to August 2015. In this presentation, JEM-GLIMS mission, JEM-GLIMS’s spectrophotometer, the identification of IC and CG lightning using Blue to Red ratio will be discussed.
11/17 14:45--16:15 Junichi Kurihara
Ground reflectance anisotropy is a major source of uncertainty in hyper/multi-spectral remote sensing. The Bidirectional Reflectance Distribution Function (BRDF) measurement can contribute to improve the model and reduce the uncertainty. Conventional laboratory and field measurements have many disadvantages in their limited samples and flexibilities. Recently, some UAV gonimeter systems with a spectrometer are used for the BRDF measurement to overcome the disadvantages. However, the attitude stability and accuracy of UAVs cause view angle errors. We developed a new UAV goniometer system with a Liquid Crystal Tunable Filter (LCTF) camera, which allows snapshot hyperspectral imaging. This system provides more accurate and efficient BRDF measurements and will promote a better understanding of ground reflectance anisotropy for the future remote sensing.
12/01 14:45--16:15 Masataka Imai
Lightning can be considered as one of the fundamental atmospheric phenomena, and they are produced by strong convective clouds on the Earth. We know that lightning also exists on the giant planets such as Jupiter and Saturn, and these planets are well known having intense atmospheric convection. Besides with their impacts on the chemical reactions, lightning can be an important implication for the atmospheric dynamics. Venusian lightning explorations were started in the 1970s from several spacecraft such as Venera series and Pioneer Venus Orbiter [e.g. Ksanfomaliti et al., 1979; Taylor et al., 1979], and also previous ground-based observations challenged to detect the lightning flashes [e.g. Hansell et al., 1995]. It has been known that this planet has a severe environment with 90 bars high pressure and 720 K temperature at the surface, and fast zonal atmospheric winds named Superrotation exist at ~50-70 km cloud layer. Recently, Japanese Venus exploration AKATSUKI and one of its camera IR2 firstly success to reveal the convective cloud formation in the middle layer of Venus. However, Venusian lightning activity has been a mystery over a half century, and we still do not get over the ambiguity of evidential measurements of previous studies.
12/08 14:45--16:15 Kaye Kristine Vergel
Remote sensing has been widely used in assessing damages from disasters. Compared with field surveys, it is a cost-effective tool. In a year, around 18 to 19 tropical storms enter the Philippine area of responsibility, 7 to 9 of which make landfall in the country. Given the large frequency of storm passing in the country, analysis of storm damage to agriculture is of great demand. There are two types of factors that contribute to the damages brought by a storm’s passing, [1] intensity of the typhoon and [2] characteristic of the areas hit. The typhoon’s intensity can be described by rainfall and wind velocity. On the other hand, elevation and land cover characterize the area to be hit. In this seminar, the damages brought by two typhoons will be discussed. The storms Haiyan and Koppu have hit the provinces of Leyte and Nueva Ecija, respectively. These two typhoons were chosen because of their different characteristics. Haiyan, a typhoon which carried wind of great intensity with maximum speed of 315 km/h; and Koppu, a typhoon that brought a large amount of rainfall. Using the Normalized Difference Vegetation Index and Normalized Difference Infrared Index, we found a decrease in value after the storm’s passing which can be attributed to the damage caused by the typhoon. A disturbance map was then created using these indices. Correlation of the disturbance with different variables: land cover, elevation, rainfall and aspect were carried out. Considering the interactive effects of these factors to the measured damaged, machine learning using neural networks was utilized. It was found that the strongest influence to damage comes from elevation, followed by aspect, rainfall and lastly land cover.
12/15 14:45--16:15 Benjamin Jonah Perez Magallon
Banana Industry in the Philippines plays a big role in the country's economy. Currently, the country is third in the world's top producers of banana. Davao del Norte, located in Mindanao, is the source of almost 50% of the country's production. Recently, the province has experienced a rapid decrease of banana plantation area and it is attributed to the presence of infestation called 'Panama Disease'. Because of the infestation, the region has loss a huge part of the plantation area and million dollars of profit. With these events, the need for finding a way in monitoring the plantation and the spread of the disease arises and one of the method that could be used is Remote Sensing. In this study, Landsat 7 and 8 Images of Davao del Norte are processed for creating detailed classified vegetation map of the region. Spectral information and LCTF images were also acquired and will be discussed.
12/22 14:45--16:15 Chiharu Shimizu
Lightning discharges usually occur within active thunderclouds, and previous studies suggested that there are close relations between lightning activities and severe meteorological phenomena. Therefore, lightning discharges can be potentially used as a good proxy to predict the occurrence of the severe weather. Especially, as lightning is a discharge phenomenon, it is more important to investigate the relation between electrical properties of lightning discharges, such as the polarity, the peak current, and the charge amount and the meteorological parameters of the severe weather. Since it is reported that there are comparable relation between lightning current waveforms and ELF magnetic field waveforms measured at the 300 km distance from the lightning, we evaluated the similarity of the lightning current waveforms measured by a Rogowski coil installed at Mt. Ogami and ELF waveforms measured at Onagawa observatory. Then, the average correlation coefficient and standard deviation between these two waveforms are estimated to be r=-0.84 and sigma=0.14, respectively. This result indicates that there are high similarities between these two waveforms. From these quantitative analyses, empirical equations that enable us to directly convert from the magnetic field intensities into the charge amounts were obtained. Furthermore, to investigate the relation between severe weather and lightning activities, we picked up 8 downburst events in 2015 according to Japan Meteorological Agency (JMA). Using ELF waveform data obtained at Kuju station in Kyushu and lightning data of the Japan Lightning Detection Network (JLDN), charge amounts of the lightning discharges that occurred around the downburst onset were estimated by applying the empirical equations. In addition, precipitation amounts observed by the JMA C-band radar and temperature and wind velocity obtain by AMeDAS data were also analyzed. At the presentation, we will show the results and discuss the relation between the time variation of the lightning frequency and charge amount and the onset of the downburst.
01/12 14:45--16:15 Tsuyoshi Sato
Transient Luminous Events (TLEs) are transient discharge emission phenomena that are accompanied by cloud-to-ground (CG) discharge in the stratosphere and the mesosphere. Global distribution and occurrence rate of lightning and TLEs are necessary to estimate the contribution to the global chemical component of the atmosphere. In previous studies, there were some estimations of global occurrence rate of TLEs such as 0.5 sprites/min based on 216 days of ELF data [Sato and Fukunishi, 2003], 1.33 sprites/min based on 3.5 hours of observation from ISS [Blanc et al., 2004], 2.8 sprites/min using a new formula [Ignaccolo et al., 2006] and 0.5 sprites/min based on three-year optical survey from satellite [Chen et al., 2008]. They don’t reflect local time (LT) dependency. We use the Global Lightning and sprIte MeasurementS on JEM-EF (JEM-GLIMS) onboard the International Space Station (ISS). JEM-GLIMS can observe lightning and TLEs at the range of 19-4 LT. We estimate the global distribution and occurrence rate of lightning and TLEs and the seasonal and LT variations. From December 2012 and August 2015, JEM-GLIMS recorded 6404 lightning, 709 TLEs, 42 sprite, 504 elves. The occurrence rate of lightning, TLEs, sprite and elves are estimated 89.5, 9.91, 0.587 and 7.05 events/min, respectively. Lightning and TLEs concentrate over the African Continent, Southeast Asia, and Central America. The activity of lightning and TLEs tend to decrease in the middle of the night.
01/19 14:45--16:15 Tatsuharu Ohno
One of the Jupiter's atmosphere characteristic is Band structure. The band structure consists of east-west zonal jet. There are many theory to explain how to maintain the zonal jet. However, the debate is continuing. There is one theory that the jovian cumulonimbus maintain the zonal jet (Gierasch et al., 2000. Ingersoll et al., 2000). This suggest that the cumulonimbus provide the energy to zonal jet and maintain by combining continuously the small-scale eddies made by cumulonimbus. The distribution of jovian cumulonimbus has been observed by many spacecraft, Voyager, Galileo etc. However, their observation time for cumulonimbus is very short time. The distribution of Jupiter's zonal jet is similar between north-pole and south-pole. But, the distribution of cumulonimbus isn’t similar. Sugiyama et al., (2014) suggest that the cumulonimbus has intermittency. So, the distribution is not enough to explain the relationship between zonal jet and cumulonimbus because the spacecraft’s observation period might have been the quiet period of cumulonimbus activity. My purpose is understanding the formation mechanism of jovian zonal jet maintained by cumulonimbus. So, at first, I’m going to obtain the average distribution of cumulonimbus. The cumulonimbus is very small from the Earth. The observation is bit difficult with Ground-based telescope. Lightning occur at the cumulonimbus. So, lightning detection may be useful for obtaining the cumulonimbus’s position. In this seminar, I’m going to introduce my work, review the ‘Ground-based search for lightning in Jupiter with GTC_OSIRIS fast photometry and tunable filters’ (Luque et al., 2015) to know how to observe the lightning ,and make a study my observation.
01/26 14:45--16:15 Junji Miyazawa
The Martian atmosphere was warm and high pressure several billions of years ago[Carr, 1999]. The Martian atmosphere is dry and low pressure (636 Pa)[McKay and Stoker, 1989; Kerr, 2000; Baker, 2001]. Although about 95% of Martian atmosphere is CO2, about 90% of escaping atmosphere is oxygen (O, O+) from the observation by Mars Express[Lundin et al., 2009]. Oxygen escape may be important for the evolution of the water of Mars. Mars does not have a significant internal magnetic field. The solar wind can penetrate to the Martian ionosphere altitude and interact with the Martian ionosphere [Acunã et al., 1998; Lundin et al., 2004]. Then, ionopause and bow shock are formed, and oxygen ion escape is strongly affected by the solar wind. The structures of ionopause and bow shock are important for oxygen ion escape. The important escape mechanisms of Martian atmosphere are Dissociative Recombination, Solar Wind pick up and Solar wind sputtering. The previous models do not include the effect of the collision of the escaping particles with the atmospheric particles and the escape of the collided secondary particles. Then, I constructed a model including dissociative recombination, solar wind pick up and spattering processes, and investigated the amount of the atmospheric escape from Mars. I calculated the solar wind interaction with the Mars ionosphere with Magnetohydrodynamics equations and particle model of Oxygen. In this seminar, I will talk about Solar wind sputtering escape.
02/02 14:45--16:15 Tetsuro Ishida
The spectral signature of vegetation provides us a lot of valuable information such as tree species, growth stage and health condition. Therefore, the relationship between the plant properties and the spectral information has been studied by using direct and indirect measurements [e.g., Mahlein 2016]. Recently, the Unmanned Aerial Vehicles (UAVs) technology steady progress, and it has resulted in one of the survey systems in the agricultural sector. Since it can survey large-scale agricultural land efficiently, the UAVs equipped with multispectral sensors have recently come to be utilized by many researchers [e.g., Peña et al., 2013; 2015; Garcia-Ruiz et al., 2015]. The spectral property is usually different for each observation target. Thus, in the case of multispectral imaging, it is necessary to select optimal band combination, i.e. optical filters, in order to acquire desired information. Regarding the UAV-based multispectral imaging, the selection of optimal band combination is rather important since the maximum payload size and weight are limited. Thus, we utilized the Liquid Crystal Tunable Filters (LCTFs) for the UAV-based spectral imaging. The LCTFs are compact, electronically tunable, spectral notch filters whose spectral transmittance can be controlled by adjusting the voltage. Hence, the spectral transmittance can be changed afterwards in accordance with the spectral property of observation target. For the calibration and validation of the LCTF sensor, the field campaign was conducted under the PHL Microsat Program in Gerona and Ramos, Tarlac, the Philippines on March 28 – April 3, 2016. In this campaign, the LCTF-based spectral aerial imaging was carried out in 9 vegetation areas, and spectral signatures of 14 different ground objects were collected. In this paper, the vegetation classification by the LCTF’s aerial imagery is firstly performed by using Support Vector Machine (SVM). The result showed that a change in spectral signatures in shaded areas was a major cause of misclassification. By training the SVM model with both sunlit and shaded spectral signatures, we achieved 93.3 % accuracy on a vegetation classification.
02/09 14:45--16:15 Ade Purwanto
Although polarization and spectral information utilization has been received great attention with the sensor and detection technology advance, few results are showed to jointly utilize both of this information in targets classification. Polarization and spectral information reveals two different aspects of one single target, and therefore, if both of information is properly used, good performance would be achieved in the classification. (Chao et al, 2007) In this presentation, initial experiment to discover the effect of a specular reflection on the surface of a leaf will be presented. The experiments were unique yet simple, however, the finding should be very useful to understand the phenomena of polarized light. Object of the experiment is coffee plants with the age around 1 to 1.5 years. Instruments are the polarimeter camera from Photonic Lattice, an LCTF camera developed by Hokkaido University, and a polarizer wheel. Several findings can be discussed as a possible probe to acquire a “true spectra”, from mean leaf angle until the average degree of polarization derived either from the single leaf, or a tree.
02/16 14:45--16:15 Nguyen Thi Thu Hanh
The expansion of various types of Floating algae have been reported in coastal regions and open oceans recently. The Floating Algae Index (FAI) was developed by Hu (2009) is a robust algorithm to detect floating algae. Due to the lack of spatial resolution, it is difficult to detect some small patchy algae, therefore leading to uncertainties in the spatial distribution. The Landsat 8 OLI has the suitable bands for detecting floating algae, furthermore the panchromatic sharpening could improve the spatial resolution of the images. (Johnson, 2014). However, no studies have focused on the effects of pan-sharpening on Vegetation Index (VI) images particularly FAI images. Pan-sharpening could improve the ability to detect and quantify the surface features of floating algae.
02/23 14:45--16:15 Kittanapat Bandholnopparat
The ratio between intracloud discharge (IC) and cloud-to-ground discharge (CG), denoted by Z, is 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 are not resolved yet. In order to solve these problems, the Global Lightning and Sprite Measurements on Japanese Experiment Module (JEM-GLIMS) mission was launched in 2012, and it conducted nadir observations of lightning discharges using both optical instruments (Lightning and Sprite Imager: LSI and six-channel spectrophotometers: PH) and electromagnetic wave receivers. Thus, the final goal of this study is to estimate Z-value and to clarify its latitudinal and regional dependences and to evaluate the contribution of lightning to the global circuit as a generator. For this purpose, we have developed new methods to distinguish IC and CG using JEM-GLIMS optical data and ground-based lightning data. As a first step, we selected 707 lightning events detected by LSI and PH on board JEM-GLIMS in the period from Nov. 2012 to Aug. 2015. These lightning events were detected over both land and oceanic regions. Then, we compared the JEM-GLIMS data to the ground-based lightning data obtained by the Japanese Lightning Detection Network (JLDN), the National Lightning Detection Network (NLDN), and the World Wide Lightning Location Network (WWLLN) and identified the type of the lightning discharge detected by JEM-GLIMS, As a next step, we have calculated intensity ratios between blue and red PH channels, such as 337nm/762nm, 316nm/762nm, 392nm/762nm, 337nm/(599-900nm), 316nm/(599-900nm), and 392nm/(599-900nm) for each lightning event. It is found that 400 of 707 lightning events (56.6%) were identified to be CG discharges while 307 of 707 (43.4%) were IC discharges. It is also found that the PH intensity ratio of IC discharges is clearly higher than that of CG discharges. In the case of IC discharge, the ratio of 337nm/762nm, 316nm/762nm, 392nm/762nm, 337nm/(599-900nm), 316nm/(599-900nm), and 392nm/(599-900nm) are estimated to be 1.06, 0.21, 1.04, 0.16, 0.04, and 0.17, respectively, while those of CG discharges are 0.46, 0.16, 0.74, 0.03, 0.03, and 0.13, respectively. As the difference of the 337nm/762nm and 337nm/(599-900nm) ratio in IC case and in CG case is relatively large, these two ratios are the useful proxy to classify the discharge types for other 7650 lightning events detected by JEM-GLIMS. At the presentation, we will also show detailed results derived from the analyses of LSI data and ground-based ELF observation data.
03/02 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 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 develop a new and feasible process to detect coral bleaching in the coastal area of Vietnam by using some cheap and available image sources such as Landsat, Sentinel-2, AVNIR-2, and as well as our own data such as VNREDSAT and MDG in the near future. In this EOU seminar, I would like to show my image pre-processing steps and some initial results.
03/09 14:45--16:15 Begzsuren Tumendemberel
Spectral reflectance of a plant is one of the major methods of the modern remote sensing, which strongly depends on the combination of the sunlight incidence and observation view angle of the satellite camera. In this study, single leaf’s 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 hundreds of different angles for Bidirectional Reflectance Distribution proposals in a laboratory. The advantage of using an image of the multispectral camera is able to crop surface area of a leaf that means it is possible to select arbitrary size of the field of view. This kind of measurement setup produces an error less than a spectroradiometer. We separated polarized and unpolarized reflectance of a leaf and the product of those two parts is the total reflectance which is equal to reflectance measurement result without a linear polarizer. The result showed that polarized reflectance strongly depends on relative azimuth angle and zenith light source angle relative to the camera and unpolarized part almost does not depend on angles. Results indicated that polarized part is caused by waxy cuticle which is a transparent outer layer, there is no relationship between polarization degree and chemical compounds inside a healthy leaf, and it became a problem of multilayered structure scattering. These indicators leads to reflectance model of a leaf which consists of two layers which are transparent layer and structure layer. This simple model shows an almost same spectral signature as that produced without linear polarizer. The model explains bidirectional reflected light on the plants, allowing to take an image along slope downward angle.
03/09 16:30--18:00 Ellison Caparas Castro
Thunderstorms have been a concern to the public due to their destructive capabilities. Even though the basic dynamics of a thunderstorm have been understood, the amount and type of precipitation brought by these storms have been a forecasting problem. The relationship between the thunderstorm and its accompanying precipitation has been monitored extensively, such as the number of lightning flashes, the height of cloud or the depth and duration of the storm cells measured using radar systems present a linear relationship to the amount of rainfall the storm may release. In this study, cloud images from satellites will be used to create a three-dimensional model of the storm, because these models may provide numerous information such as the speed of the storm's development that will be helpful in predicting the intensity of the storm. For this presentation, I shall discuss several related pieces of literature discussing a cloud's properties and its relationship to the intensity of the storm, three-dimensional modeling techniques, and future works.
03/16 14:45--16:15 Mitsuteru Sato
Lightning Recent studies suggest that the lightning occurrence frequency and charge amount neutralized by lightning discharges are closely related to severe weather events, such as typhoon, hailstorm, tornado, downburst, etc. In order to monitor lightning activities in the regional and global scale, we continuously developed the lightning observation system, i.e., ELF observation network (GEON), VLF observation network (AVON), slow-antenna system, and field mill sensor. Using these systems, we succeed in detecting a precursor of the downburst occurrence in Japan [Shimizu, M-thesis, 2017]. On the other hand, many Asian countries do not own any operational lightning detection network so far. Unfortunately, the Philippines is one of such countries, but it always suffers from severe weather evens (especially, attacks of typhoons). For example, in case of the typhoon Haiyan, ~6000 people died and ~29000 people were injured. In order to monitor lightning and thundercloud activities in (near) the Philippines, to develop the technique to predict the intensity of the severe weather events, and to develop the system informing the related agencies (PAGASA, OCD, MMDA, etc.) of such observational results, we will start the SATREPS project from this April in the Philippines. At the seminar, the main objective of this project and the observation plan of lightning discharges and thunderclouds using ground-based network and micro-satellites will be introduced in detail.