06/05 10:30--12:00 Chiharu Shimizu
Previous studies suggested that there are close relations between lightning activities and meteorological phenomena. But in these studies, only the occurrence frequencies of lightning discharges are considered. 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. As the magnitude of the electrification in thunderclouds is considered to be proportional to the intensity of the vertical convection, charge amounts of lightning discharges can be a good proxy to represent the developing process of thunderclouds. 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, in this method, only the lightning discharges directly hitting the towers can be measured. Recently, it is shown that the shape of the lightning-generated induction magnetic field waveforms in the ELF frequency range is well comparable to that of the lightning current waveforms [Sato et al., 2013]. 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 peak current intensities and charge amounts were obtained. Furthermore, using ELF waveform data obtained at Kuju station in Kyushu and lightning data of the Japan Lightning Detection Network (JLDN), peak current values and charge amounts for the lightning discharges occurring when severe down bursts were confirmed in the Kanto Plain are estimated by applying the empirical equations. Then, we newly found a clear feature showing that the time variation of charge amounts was changed just before the downburst onset. At the presentation, results of my analysis are discussed.
06/12 10:30--12:00 Yuya Goda
A Rossby wave plays an important role in atmospheric phenomena on planets. The south polar wave at about 67°S in Jupiter is considered as one of signatures of Rossby wave. Previous observations, such as by Cassini ISS in 2000 or the Hubble Space Telescope (HST) from 1994 to 1999 [Barrado-Izagirre at al., 2008], show that the polar region is covered by bright diffuse haze and its edge has a wave structure spreading in longitudinal direction with wavenumber of 12 – 14 at 67° S, which travels westward with a phase velocity of 0 - 10 m/s in SystemⅢ. These observations suggested that this wave structure is caused by a planetary Rossby wave. However, these observations had been carried out only every other year and the variance of short time scale (about month) is clear. We determine whether or not the wave observed at the edge of the stratospheric haze in south polar region is caused by Rossby wave. Using a methane absorption band filter at 889 nm installed at Multi-Spectral Imager (MSI) of the 1.6 m Pirka telescope, we investigated the meridional and vertical wavenumbers and phase velocity of the observed wave structure and zonal wind speed. In this presentation, I discuss two points. First, we introduce the improvement of Jupiter images quality using FWHM (full width at half maximum) of Galileo satellites PSF. When we observe Jupiter, we get few thousands continuous images and compose 10% images for reducing effect of Earth atmosphere. So it is important to evaluate image quality of Jupiter. Second, we show the observational results of time variation of the wave structure in Jupiter’s south polar region in 2011 to 2015 by the ground-based telescope. In the period of availability of observed Jupiter, each result is separated by few weeks or few months. Our results show the wave structure spreading in longitudinal direction at 67° S. In particular, observation data in April 2015, we found that wave structure at longitude of 190 to 260 degrees at 67°S in SystemⅢ was very similar. So those didn’t change in this period. It is possible that the wave doesn’t large change about 5 days. Using analysis of this method, we will make wave structure of different latitude and wavelength.
06/19 10:30--12:00 Tsuyoshi Sato
Transient Luminous Events (TLEs) are transient discharge emission phenomena that accompany cloud-to-ground (CG) discharge in the stratosphere and the mesosphere. In recent previous studies, global distribution of TLEs was estimated without reflecting local time dependency, and global occurrence rate was calculated directly from the observed data. This may pose some problem because the true global occurrence rate could be ten times larger than the observed data. In order to resolve these, the global distribution and occurrence rate of lightning and TLEs are estimated using the Global Lightning and sprIte MeasurementS on JEM-EF (JEM-GLIMS) onboard the International Space Station (ISS). Two sensors equipped on JEM-GLIMS, which are the Lightning and Sprite Imager (LSI) and Photometer (PH) are used. From December 2012 to November 2014, JEM-GLIMS recorded 4823 events at night in local time. From the data obtained from the JEM-GLIMS, lightning and TLEs concentrate over the African Continent, Southeast Asia, and Central America. The global distribution of lightning varies seasonally; lightning occur chiefly in the Northern Hemisphere on northern summer and in the Southern Hemisphere on northern winter. The global occurrence rates of lightning and TLEs are 111 events per minute and 12 events per minute respectively.
06/26 10:30--12:00 Katia Nagamine Urata
Within the Global Monitoring for Environment and Security (GMES) framework, sustainable management of forests is recognised as an important challenge to be addressed throughout remote sensing and future generation of satellites. For instance, optical Earth Observation data is able to deliver biochemical and structure canopy information. However, the spectral and directional reflection properties of forests and vegetation are considerably affected by the sun-sensor geometry, which may lead to faulty interpretation of the derived albedo products. Directional effects in space- and airborne imaging spectroscopy data are mainly caused by anisotropic reflectance behaviour of the surface. Such anisotropic behaviour is typical for all natural surfaces and can be expressed by the quantity of the Bidirectional Reflectance Distribution Function (BRDF). Anisotropy is especially pronounced in sensor systems provided with wide field-of-view optics as well as those capable of multi-angular observations. Hokkaido University developed the first space-qualified Liquid Crystal Tuneable Filter (LCTF), which allows multispectral imagery at customized bands selection. It is currently on board the RISING-2 platform, featured with multi-angular observations from space. An additional LTCF-platform has been adapted for airborne or Unmanned Aerial Vehicles (UAV) payloads, featuring large field-of-view of nearly 90°. Hence, for an accurate quantitative data analysis from either LCTF-platforms, it is crucial a normalization of the existing reflectance anisotropy, especially for the derivation of albedo products. This seminar reports on the considerations and analysis for the BRDF modelling, suitable for the characterization and quantification of anisotropy, as well as its correction. The findings of the current work are intended as a step toward the standardization of the LCTF data pre-processing, in order to make directional effects correction a standard step before generating further higher level product.
07/03 10:30--12:00 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 ion (O+,O2+) 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.[Acun ̃a et al., 1998; Lundin et al., 2004] Then Ionopause and Shock are formed, and oxygen ion escape is strongly affected by the solar wind. The structures of ionopause and the 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 investigate the amount of the atmospheric escape in Mars. In this presentation, I will show the results of the solar wind condition calculation around Mars.
07/10 10:30--12:00 To Anh Duc
• Polarized light, which plays an important role in the history of physics, is believed to be utilized hundred years ago by the Viking as a navigation tool for their sea voyages. In the animals kingdom, species such as: bees, octopus, shrimp… have the capability to sense polarized light, which is also used for navigation. In the field of remote sensing, Hansen and Hovenier (1979) interpreted Venus Polarization to study about Venus cloud characteristics. In 1986, for the first time polarized light was used for Earth observation from US Shuttle. Although the system is simple and manual, it still showed some promising results. • In 1996, CNES installed POLDER, a powerful and automatic polarized imaging system onboard Japanese ADEOS-1 satellite for Earth observation. POLDER then proved its prominent capabilities compared to conventional unpolarized channels. • However, since POLDER was manufactured about 20 years ago, there exist some problems: numbers of observation angles per orbit are limited, risk of false polarization, too low spatial resolution. Scientists nowadays are requiring for a new polarized imaging system with higher measurement accuracy which can support them in building more complex and precise models. • With the help of Japanese expert engineers and scientists, we are now developing a new generation of polarized imaging system that may satisfy scientist’s requirements. While still keeping the best capabilities of POLDER, we are trying to improve its drawbacks: the numbers of observation angles per orbit are increased, spatial resolution is increased, risk of polarization is decreased, Signal-to-Noise ratio is increased. By doing that, the measurement accuracy will absolutely be enhanced. • My scientific target throughout this seminar is to improve the accuracy of aerosols retrieval by using the new polarized imaging system. In my presentation, I will firstly analyze about the limitations of POLDER, importance of observation target, the sources of POLDER’s errors, and the necessity of improvement. Then, the system’s configuration and method used to improve the accuracy are presented. The results for Signal-to-Noise-ratio and required exposure time are derived in the next part. Finally, in the discussion, the accuracies improved from different viewing angles are compared with POLDER to show the level of enhancement. Some other system evaluations are also introduced in this presentation.
07/17 10:30--12:00 Nguyen Thi Thao
Remote sensing of ocean color from space began in 1978 with the successful launch of NASA’s Coastal Zone Color Scanner. Over two decades, a series of the ocean color sensors have been launched. The new generation of the ocean color sensors significantly improves our ability to monitor the coastal environment. However, the coastal environment still presents several obstacles for the use of satellite ocean color data because of its complexity. For applications in the coastal zone, high spatial resolution, high spectral resolution, and many spectral bands are required. Image data of the current sensors can provide each of them but not all. With advantages of a new technique of Liquid Crystal Tunable Filter (LCTF), all three parameters can be included by a sensor. Moreover, the LCTF sensor that is small, light and low power consumption is suitable to install in a micro-satellite. The micro-satellite with low cost and quick fabrication is playing an increasingly important role for Earth observation. The purpose of my thesis is to study feasibility of a new sensor called the Space-borne Multispectral Imager (SMI) on-board the MicroDragon micro-satellite to observe coastal water. This study focuses on three objects including outline of mission requirements, sun glint avoiding solution, and evaluation of noise, then estimation of Signal to Noise Ratio (SNR).
07/24 10:30--12:00 Vi Duc HUAN
Micro-Dragon Satellite is the Vietnamese sun-synchronous cubic satellite developed under agreement between Vietnam National Satellite Center and 5 Japanese Universities ( Tokyo University, Keio University, Hokkaido University, Tohoku University and Kyushu Institute of Technology). Micro-Dragon is planned to be finished by the end of 2017 and launched in 2018 with the main mission is Ocean Observation in Vietnam region using two instruments called Space-borne Multispectral Imager (SMI) and Triple Polarization Imager (TPI). Due to TPI potential application is to use for retrieving aerosol optical parameters, I plan to develop the aerosol optical parameter retrieval algorithm for Micro-Dragon based on recent algorithm for the similar operating space-borne instrument to TPI such as POLDER on board ADOES1,2 and PARASOLS satellites. Throughout this seminar, I am going to introduce the recent aerosol retrieval algorithm over ocean applied to PARASOL data called SRON. The SRON’s author fit a radiative transfer model for a coupled atmosphere-ocean system to the PARASOL measurements and retrieve the oceanic chlorophyll a concentration, wind speed in two directions,and fractional foam coverage in addition to all parameters related to a bimodal aerosol model. The retrieved values for aerosol optical thickness (AOT) and Angstrom exponent agree well with Sun photometer measurements of the Aerosol Robotic Network (AERONET), and the Single Scattering Albedo (SSA) agrees well with the AERONET diffuse sky inversion product.
07/31 10:30--12:00 Yukihiro Takahashi
It has been pointed out that atmospheric activity has ~27-day periodicity, which implies the connections between solar activity and the earth’s climate since the rotation period of the sun near its equator is 27 days. However, this hypothesis is still controversial since the spatial extent of such variation and the relationship between the different areas in global scale was unclear. Here we show a close relationship between globally synchronized thunderstorm/cloud activities in the tropical latitudinal range and solar parameter with ~one-month periodicity for a certain half year, using lightning data, a proxy of thunderstorm activity, obtained by the global radio wave network and a proxy of cloud amount, Outgoing Longwave Radiation. Amplitudes of those variations are sometimes up to few 10s of percent and don’t show apparent longitudinal propagation. It was found that the thunderstorm activity in Asia Maritime Continent (AMC) shows a seesaw correlation with the cloud in Western Pacific Warm Pool (WPWP), which corresponds to typhoon activity, while in-phase correlation with could in most part of other tropical regions. This implies typhoon generation in WPWP and lightning in AMC has a strong dynamical connection. Such relationship cannot be explained by simple existing theories or phenomena, such as Madden Julian Oscillation.
08/07 10:30--12:00 Ngo Duc Minh
The Southwest sea of Vietnam, from Ca Mau cape to the Cambodian border, including Phu Quoc and Tho Chu islands, has been especially interested and played an important role in the socio-economic development and national security of Vietnam. Southwest coastal region also is one of Vietnamese Coastal regions most affected by climate change due to its geography resulted in great variation of coastal aquaculture productivity in period of 5 years from 2003 to 2008, threatening food security and economic growth. Therefore, understanding impacts of climate events on Southwest coastal environments in Vietnam is urgently required. Worldwide, climate change-driven changes coastal environment are expected but the exact magnitude and extent of effects are largely unknown due to the immaturity of scientific analytical approaches. However, results of study on The regional impacts of climate events on coastal environments and the aquaculture of Japanese scallops in Dalian,China and Funka Bay, Japan published in 2014 by Yang Liu et al.,2014 has significant implications for Vietnam. In this seminar, I want to use new scientific analytical approach done by Yang Liu et al.,2014 to clarify the relationship between different climate events and Southwest coastal environment in Vietnam.
08/20 10:30--12:00 Shuhei Goda
The size distribution of small-bodies orbiting Jupiter calculated from cratering records of moons is very uncertain, especially the diameter of small-body < 1km. It is very difficult to observe directly small-bodies orbiting Jupiter by telescope on the ground, but it is possible to observe impact flashes on Jupiter due to collisions of small-bodies with Jupiter.So I expect to restrict the size distribution of small-bodies with observing impact flashes on Jupiter long term. To do this, I have to observe the condition of Strehl ratio > 0.02 at observed wavelength 0.9micron entirely jupiter(>50"). So we are developing AO (Adaptive Optics) system for planets. For the condition of high spatial resolution with long-term stability using AO, I consider that using extended sources of planets to measure wavefont computing cross-correlation like solar AO is best method. My purpose is to derive analytical expressions of wavefront measurement error with correlation algorithms to extended sources in order to understand this essence. I used derivasion of Thomas et al,2006 as a reference, that is analytical expressions with the correlation algorithms to a gaussian spot to derive analytical expressions with the correlation algorithms to a extended sources expressed by cosine waves. As a result, it suggests that wavefront measurement error with correlation algorthms depends on the shape of the auto-correlation of sources, and its coefficient is determined by figure pattern, e.g. gaussian, cosine.
08/27 10:30--12:00 Masataka IMAI
On Venus, a planetary scale bright and dark UV feature, sometimes called as the “Y-feature”, rotates around the planet every ~4–5 days. The rotation of the Y-feature implies the propagation of planetary scale waves and provides information about the dynamical state of the Venusian atmosphere. Previous Venus exploration spacecraft, such as Pioneer Venus and Venus Express, have monitored UV features for many years and revealed a long-term variation (i.e., 5–10 Earth years) of the rotation period of the Y-feature. However, short-term variations (i.e. <1 Venus year; ~224 Earth days) were difficult to observe since orbital planes of the past spacecrafts were nearly fixed in the internal frame of reference. To resolve this issue, we conducted ground-based Venus imaging observations using Pirka telescope at the wavelength of 365 nm for six times from mid-August 2013 to the end of June 2014. Each observational period has a half or one month. The latitudinal profile of relative brightness was obtained from the equatorial to mid-latitudinal regions in both hemispheres, and its periodical variation was interpreted as the rotation of the Y-feature. Our frequent observations revealed a short-term variation of Venusian atmosphere; the most significant rotation period was changed from ~5.2 days to ~3.5 days within several months. In middle observational periods, two periodical components are retrieved, and the Y-feature was not clearly observed during these periods. We also found that the ∼3.5-day periodical component, which is apparently shorter than ever reported, was significant for all observational periods, suggesting that a ~3.5-day planetary scale wave contributes to dynamics of Venusian atmosphere. In this seminar, the pre-nominal results of the latest observations, which conducted continuously from April 21 to July 29 in 2015, will be added, and we will discuss about them by comparing our previous results.
09/11 10:30--12:00 Kaye Kristine Vergel
The use of remotely sensed images in assessing damages from disasters has been widely used. 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. Nine to 10 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 many variables that contribute to the damage brought by a storm’s passing. Some of which are wind intensity, rainfall volume and topography. Few studies have analyzed the relation of all these variables to the observed typhoon damages. In this seminar, a simple analysis of the damage brought by Typhoon Haiyan to Leyte, a province in the Philippines will be discussed. We used satellite images from Landsat 8 to calculate the normalized vegetation index before and after the storm and found a decrease in value which can be attributed to the damage caused by the storm. Spectral changes to crops, in particular to rice and coconut trees were also analyzed. The data presented is a preliminary step towards the goal of relating wind intensity, rainfall volume and topography to the detected damage in the crops through spectral analysis.
09/18 10:30--12:00 Benjamin Jonah Perez Magallon
Acquisition of bidirectional reflectance distribution function (BRDF) to model multi-directional reflectance effects has been widely done for different applications such as deriving albedo, land cover classification, atmospheric correction and others. BRDF is the ratio of the reflected radiance exiting the surface and its corresponding irradiance. They are acquired using multi-angular observation by the use of goniometer, uav, planes and satellite with the combination of multispectral sensor. Philippines’ and Japan’s Forests are vulnerable to different environmental phenomena like insect infestation and seasonal variation that can affect their canopy conditions. BRDF measurements can be a tool to monitor and understand better these effects to the forest condition. In this seminar, different methods on BRDF acquisition and its application on determining vegetation condition will be discussed and a methodology to determine the effects of different environmental conditions to the BRDF measurements is proposed.
09/25 10:30--12:00 Junichi Kurihara
To study the horizontal structure of midlatitude sporadic E (Es) layers, the vacuum ultraviolet resonant scattering by magnesium ions (Mg+) in an Es layer was observed with the Magnesium Ion Imager (MII) on the sounding rocket S-520-29. Since the Es layers is formed by the convergence of metallic ions that have slow ion-electron recombination rates, the distribution of Mg+, which is one of the dominant species among the metallic ions, is thought to reflect the spatial structure of the Es layer. The spatial structure of the Es layer is closely related to various ionospheric phenomena such as the field aligned irregularity and the E-F coupling. It is expected that imaging observations of the Mg+ distribution will provide a new observational evidence for the generation mechanism of the horizontal structure in the Es layers.
11/12 14:45--16:15 Tetsuro Isida
The airborne campaign using the Liquid Crystal Tunable Filter (LCTF) multi-spectral camera has been conducted in Catarman, Northern Samar last August 1- 5, 2015. In this campaign, a simultaneous ground validation using Ocean Optics spectrometer as well as an on-site discerning of vegetation types were carried out. The main purpose of this campaign is to collect data for the derivation of algorithms that will be used in product development for the Philippine Scientific Earth Observation Microsatellite (PHL-MICROSAT). The Department of Science and Technology (DOST) and University of the Philippines-Diliman (UPD) have started an international joint program for the development of microsatellites with two Japanese universities, Hokkaido and Tohoku University. The LCTF is a light weight (80 g) and small size (30mm cube) component for spectroscopy, developed by Hokkaido University, was applied for the Spaceborne Multi-spectral Imager (SMI) mounted on the Philippines’ first microsatellite, Diwata. As the spectrum of vegetation includes several kinds of information such as vegetation types and growth stages, forests and agricultural crops have been studied using spectral instruments in past publications [e.g., Schmidt and Skidmore, 2003; Shibayama and Watanabe, 2007]. However, it is difficult to obtain the same information from the spectra taken at different altitudes because of the variability of the spectral shape. This is due to several observational factors, such as the influence of specular reflection, difference of spatial resolution and also varying weather condition at the time of acquisition. It remains unclear how we can link the spectral information taken at different altitudes. Thus, we conducted a simultaneous observation, using the LCTF camera on-board an aircraft and ground measurement in Catarman, Northern Samar. In this paper, we report the initial results of the LCTF data analysis and discuss its relationship with the spectrum taken on the ground.
11/19 14:45--16:15 Tsuyoshi Sato
Transient Luminous Events (TLEs) are transient discharge emission phenomena that accompany cloud-to-ground (CG) discharge in the stratosphere and the mesosphere. In recent previous studies, global distribution of TLEs was estimated without reflecting local time dependency. In my study, I estimated the global distribution and occurrence rate of lightning and TLEs per local time using the Global Lightning and sprIte MeasurementS on JEM-EF (JEM-GLIMS) onboard the International Space Station (ISS). Two sensors on JEM-GLIMS, the Lightning and Sprite Imager (LSI) and Photometer (PH) are used. From the data observed between December 2012 and November 2014 at the range of 20-4 local time, lightning and TLEs concentrate over the African Continent, Southeast Asia, and Central America. It was found that the global occurrence rate of lightning and TLEs depend on a local time. The occurrence rate of lightning ranges from 25.5 to 34.9 [events/min] and that of TLEs ranges from 2.49 to 5.10 [events/min]. The local time the occurrence rate of lightning and TLEs reaches minimum is different from each other.
11/26 14:45--16:15 Chiharu Simizu
Previous studies suggested that there are close relations between lightning activities and meteorological phenomena [for example; Price et al.,2009, Williams et al., 1999]. But in these studies, only the occurrence frequencies of lightning discharges are considered. As the magnitude of the electrification in thunderclouds is considered to be proportional to the intensity of the vertical convection, charge amounts of lightning discharges can be a good proxy to represent the developing process of thunderclouds. 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, in this method, only the lightning discharges directly hitting the towers can be measured. Recently, it is shown that the shape of the lightning-generated induction magnetic field waveforms in the ELF frequency range is well comparable to that of the lightning current waveforms [Sato et al., 2013]. 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 peak current intensities and charge amounts were obtained. Furthermore, using ELF waveform data obtained at Kuju station in Kyushu and lightning data of the Japan Lightning Detection Network (JLDN), peak current values and charge amounts for the lightning discharges occurring when severe down bursts were confirmed in the Kanto Plain are estimated by applying the empirical equations. Then, we newly found a clear feature showing that the time variation of charge amounts was changed just before the downburst onset. There are two tasks for next step of my research. First, we should increase the data of analysis to improve the accuracy of empirical equation. The second task is more case studies to demonstrate the relation between downburst and charge amounts of lightning discharges. At the seminar, results of my analysis and future works will be discussed.
12/03 14:45--16:15 Katia M. Urata
Recent technology making use of optical remote sensing datasets collected from different viewing angles has demonstrated to have advantages over usual nadir view observations, as multi-angle imagery has the potential to provide additional structural information of vegetation canopy. Leaf Area Index (LAI) is a key parameter of vegetation structure; it quantifies information of canopy interception, evapotranspiration, photosynthesis and gas-vegetation exchange processes. In addition, combining multiple sensors information can be a resourceful approach for vegetation parameter retrieval. Since single-sensor data may be constrained by the revisit time of the satellite or cloud coverage, if higher temporal resolution of vegetation characteristics are envisaged. However, differences in sensor characteristics - spatial, spectral, radiometric - and acquisition geometry still pose a number of challenges for the implementation of the optical data fusion. The main objective of the current study is to quantitatively estimate vegetation LAI when merging retrieved parameters from several sensors under different observations angles, based on machine learning methods. In particular, neural networks, Gaussian regression and Kernel ridge regression algorithms are focused. The results achieved so far from the agricultural site in Barrax, Spain, with the remote sensing optical data used (Landsat, MERIS, PROBA, Hymap) will be presented and further discussed in this seminar.
12/10 15:15--16:45 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 ion (O+,O2+) 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.[Acun ̃a 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. >From the model calculation result, it was found that the solar wind conditions around Mars is important. However, the solar wind conditions that I showed in the last presentation included a problem. In this presentation, I will discuss the method to solve the problem.
12/17 14:45--16:15 Yuya Goda
A Rossby wave plays an important role in atmospheric phenomena on planets. The south polar wave at 67°S in Jupiter is considered as a planetary Rossby wave. Previous observations by the Cassini ISS in 2000 or the Hubble Space Telescope (HST) from 1994 to 1999[Barrado-Izagirre at al., 2008] showed that the polar region was covered by bright haze and its edge was a wave structure spreading in longitudinal direction with wavenumber of 12 – 14 at 67° S, which travels westward with a phase velocity of 0 - 10 m/s in SystemⅢ. These observations suggested that this wave structure was caused by a planetary Rossby wave. However, these observations had been carried out only every other year and the variance of short time scale (about month) is not clear. We determine whether or not the wave observed at the edge of the stratospheric haze in south polar region is caused by Rossby wave. We investigated the meridional and vertical wavenumbers and phase velocity of the observed wave structure and zonal wind speed using a methane absorption band at 889 nm installed at Multi-Spectral Imager (MSI) of the 1.6 m Pirka telescope. In this presentation, I show that the result of the vertical variation of the wave structure. The result of observation at some wavelengths that difference absorption by methan suggests the wave structure at different altitude. The cross-correlation coefficients of different observational wavelength each days are used to estimate similarity different two longitudinal profile. In our observational results, it is found a high correlation between 889 nm and 727 nm and low correlation between 889 nm and other observational wavelength. So the sensitivity altitude of 889 nm is closer that of 727 nm than other observational wavelength, it shows that the wave structure in the stratosphere doesn't fall short of the deep troposphere. In addition, I investigate whether there is longitudinal shift of the wave structure by the altitude using displacement correlation moving along the longitudinal direction. I don't find longitudinal shift of the wave structure by the altitude.
12/24 14:45-16:15 Shota Onisi
Previous studies suggested that there exists a good relationship between frequency of lightning and atmospheric convection or precipitation [e.g. Deierling and Petersen, 2008]. Therefore, lightning data can be used as a proxy for the presence of deep atmospheric convection and precipitation. To monitor time series behavior of lightning activity, it is possible to understand more detailed relationship between the lightning activity and atmospheric convection and it is possible to predict the distributional area of precipitation. Our purpose of research is to calculate a time variation of the frequency of lightning of cloud to ground lightning (CG) and that of spatial distribution of lightning. We analyzed 3909 events of CG observed by Japan Lightning Detection Network (JLDN) from 17:30, August 12th 2013 to 19:14, August 12th 2010 (JST) in Kanto region to estimate the frequency and spatial distribution of CG for every minute and with 1km square grid. We calculated the cross correlation function between the CG distribution at a certain time and that of the one minute later in order to estimate the motion vector of CG area and we required the luminance centroid to track CG lightning area, which might be useful to predict the distribution few minutes later. It is possible that we can estimate the motion vector of the one minute later with an accuracy of a few hundred meters and using the luminance centroid and we compare the time variation of CG lightning area with the variation of the precipitation area. Our result shows The rain area which has more than 50 mm/h corresponds with CG lightning area well. In this presentation, we will discuss the adequacy of analysis method and our initial result. Also we will consider the relationship between the distribution of torrential rain area and the area of CG.
01/07 14:45-16:15 Masataka Imai
A planetary-scaleY-feature,” rotates around Venus with a periodicity of 4–5 days. The rotation period of the UV feature varied over the course of observation by the Pioneer Venus orbiter. However, in previous satellite observations of Venus, since the spacecraft were operated in nearly fixed inertial space, the periodicity variations on sub-yearly timescales (one Venusian year is ~224 Earth days) were obscured by the limitation of continuous dayside observations. We conducted ground-based Venus imaging observations, which consist of six times observation periods, at 365 nm from mid-August 2013 to the end of June 2014. Each observation period was conducted over half or one month, enabling long-term monitoring of Venus’ atmosphere above the equator region. The latitudinal distributions of the relative brightness exhibited the longer (~5.2 days) and the shorter (~3.5 days) prominent periods (>90% significance level). The relative intensities of these two significant components also showed temporal variations. Although the shorter component persisted throughout the observation periods, its dominance over the longer period varied in a cyclic fashion, and the relative intensity of two significant components had a temporal variation. The period changed from 5.2 days to 3.5 days at approximately nine-month intervals, suggesting that the timescales of the periodic variation of the planetary scale waves, and the Venusian year (224 days) do not co incide. 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 perturbation patterns were dynamic. In this seminar, I will show additional results from more continuous data obtained from April to July, 2015, and discuss the variability of the cyclic nature.
01/14 14:45-16:15 Shuhei Goda
The size distribution of small-bodies orbiting Jupiter calculated from cratering records of moons is very uncertain, especially the diameter of small-body < 1km. It is very difficult to observe directly small-bodies orbiting Jupiter by telescope on the ground, but it is possible to observe impact flashes on Jupiter due to collisions of small-bodies with Jupiter.So I expect to restrict the size distribution of small-bodies with observing impact flashes on Jupiter long term. To do this, I have to observe the condition of Strehl ratio>0.02 at observed wavelength 0.9micron entirely jupiter(>50"). So we are developing AO (Adaptive Optics) system for planets. For the condition of high spatial resolution with long-term stability using AO, I consider that using extended sources of planets to measure wavefont computing cross-correlation like solar AO is best method. The analtycal expression of wavefront measurement error using extended sources was derived by Thomas et al.,2006. I made Jupiter image that can be seen in Nayoro site using Hubble Space Telescope Jupiter image and calculated wavefront measurement error using analytical expression. As a result, the condition of strehl ratio>0.02 is achived when extended objects of Jupiter are used as wavefront measurement source. But now analytical expression has not been confirmed by observational experiments. I made Wavefront Sensor and measured wawvefront error using moon and Jupiter sources. analytical expression suggests that wavefront measurement error with extended objects depends on the FWHM of the auto-correlation, photon, and background of sources. So, I performed parameter studies using experiment results, and made clear that wavefront measurement error depends on parameters of observed sources in the same way as analytical expression.
01/21 14:45-16:15 Ngo Duc Minh
Climate change has been recognized as the most important environmental problem of 21st century. It is believe that climate change is the main reason leading to the increase frequency, and intensity of extreme weather events like El Nino,.. (Wenju Cai et al. 2014), climatic processes including monsoon (Yen Yi Loo et al.2014). As consequence, climate change will affect to aquaculture and fishery indirectly through the changes in environmental parameters (Chlorophyll a, Sea Surface Temperature..) which are sensitive to climate variability. Therefore it is important to understand the relationship between climate events and the variation of environmental factors to access climate change's impacts on aquaculture and fishery. However, the impacts of climate change on fishery and aquaculture are difficult to predict, as marine ecosystems are affected by the synergistic effects of multiple climates and stressors (Mohanty et al.2010). The Southwest sea of Vietnam, from Ca Mau cape to the Cambodian border, including Phu Quoc and Tho Chu islands, has been especially interested and played an important role in the socio-economic development and national security of Vietnam. Southwest coastal region also is one of Vietnamese Coastal regions most affected by climate change due to its geography. However, the mechanism and the impacts of climate events on this regions are not well-understood. In my study, I combined 10 years satellite remote-sensing data, and in situ observations, and used statistical analysis to exam the correlations among climate events, and environmental and climatic factors to explore which factors were the main influences on the Southwest Sea of Vietnam when the climate events (Monsoon, ENSO) occurred. In this seminar, I want to show my current results and discuss about it.
01/28 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, 9 to 10 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 many variables that contribute to the damage brought by a storm’s passing, such as wind intensity, rainfall volume and topography. Few studies have analyzed the relation of all these variables to the observed typhoon damages. In this seminar, the damages brought by two typhoons will be discussed. The storms, Haiyan and Tson-tinh have different intensities but both hit the province of Leyte, Philippines. 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. To assess if the measured change is indeed brought by the typhoons, free-storm satellite images obtained from a different year but from the same season are analyzed and compared. The end-goal of this research is to discover how wind intensity, rainfall volume and topography play a role in the damages brought by typhoons detected by spectral analysis. Preliminary results of the relation of rainfall volume to spectral data will also be presented.
02/04 14:45-16:15 Vi Duc Huan
Micro-Dragon Satellite is the Vietnamese sun-synchronous cubic satellite developed under agreement between Vietnam National Satellite Center and 5 Japanese Universities (Tokyo University, Keio University, Hokkaido University, Tohoku University and Kyushu Institute of Technology). Micro-Dragon expected to be finished by the end of 2017 and launched in 2018 with the main mission is Coastal Ocean Observation in Vietnam region using two instruments called Space-borne Multispectral Imager (SMI) and Triple Polarization Imager (TPI). Due to TPI potentials, TPI is used for retrieving the atmospheric optical thickness at the top of atmosphere for atmospheric correction. The retrieval bases on the previous algorithms for POLDER instrument or polarization measurements. However, the algorithms with old aerosol models showed limitations for a specific region such as Vietnam coastal ocean region. So new coastal ocean aerosol models are developed by integrating the inversion data from Aerosol Robotic Network (AERONET) sun/sky radiometers with a database for the optical properties over Vietnam coastal ocean region. The aerosol models are categorized by using the fine-mode fraction (FMF) at 550nm and the single scattering albedo (SSA) at 440nm from the AERONET inversion data to include a variety of aerosol types found at 3 locations in Vietnam coast. The use of the aerosol models is to build up the look-up-tables (LUT) of the polarized radiance at the top of atmosphere to retrieve the aerosol optical parameters from TPI products. The radiative transfer equation solver in plane-parallel atmosphere named successive of scattering code is chosen (SOS).
02/25 14:45-16:15 Benjamin Jonah Perez Magallon
Spectral Information can be used to determine the state of the vegetation cover, detect diseases and other stress-related conditions. Also, it can be used to classify vegetation to different species. However, removing the bidirectional effects to the observations have been an issue. Bidirectional reflectance distribution function (BRDF) is the ratio of the reflected radiance exiting the surface and its corresponding irradiance. Acquisition of the BRDF has been widely studied. They are acquired using multi-angular observation by the use of goniometer, uav, planes and satellite with the combination of multispectral sensor. Even though there have been a lot of studies regarding BRDF, the instruments used have been the bottleneck for the results' reliability and accuracy. In this seminar, different methods on BRDF acquisition, its application on determining vegetation condition will be discussed and a new methodology to determine the vegetation conditions using Liquid Crystal Tunable Filter (LCTF) measurements is proposed. Also, preliminary results on fundamental experiments regarding the methodology and spectral analysis on Rising 2 images will also be discussed.
03/03 14:45-16:15 Quach Trung Dong
Clouds and aerosols are ubiquitous in planetary atmospheres, where they impact climate, atmospheric chemistry, remote sensing, and weather. Clouds are a vital link in the global and regional weather climate and hydrological cycle. Aerosols can cool down or warm up the atmosphere by reflecting or absorbing the sun light. They can even change the lifetimes of clouds, how much rainfall can occur and enable chemical reactions to occur on their surfaces and influence the composition of the atmosphere. Spaceborne LIDAR (Light Detection And Ranging) is one of effective ways to study clouds and aerosols. It can provide an unprecedented view of cloud structure, particularly in showing how clouds are layered vertically, which was not possible with visible, infrared, or microwave passive instruments. Level-1 backscatter and Level-2 aerosol product obtained by CALIOP (Cloud-Aerosol LIDAR with Orthogonal Polarization) onboard CALIPSO (Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observations) satellite were evaluated with a combined ground-based LIDAR and AERONET-sunphotometer measurements. The consistence between those data has demonstrated the great potential of spaceborne LIDAR.
03/03 16:20-17:50 Nguyen Thi Thu Hanh
The need for more effective environmental monitoring of the open and coastal ocean has recently led to notable advances in satellite ocean color technology and algorithm research. Satellite ocean color sensors’ data are widely used for the detection, mapping and monitoring of phytoplankton blooms because earth observation provides a synoptic view of the ocean, both spatially and temporally. Algal blooms are indicators of marine ecosystem health; thus, their monitoring is a key component of effective management of coastal and oceanic resources. Since the late 1970s, a wide variety of operational ocean color satellite sensors and algorithms have been developed. The comprehensive review presented in this article captures the details of the progress and discusses the advantages and limitations of the algorithms used with the multi-spectral ocean color sensors CZCS, SeaWiFS, MODIS and MERIS. Present challenges include overcoming the severe limitation of these algorithms in coastal waters and refining detection limits in various oceanic and coastal environments. To understand the spatio-temporal patterns of algal blooms and their triggering factors, it is essential to consider the possible effects of environmental parameters, such as water temperature, turbidity, solar radiation and bathymetry. Hence, this review will also discuss the use of statistical techniques and additional datasets derived from ecosystem models or other satellite sensors to characterize further the factors triggering or limiting the development of algal blooms in coastal and open ocean waters.
03/10 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 several surfaces will be explained. The experiment were unique yet simple, however, the finding should be very useful to understand the phenomena of polarized light. Data were taken in February 5th and February 10th, logging the phenomena on wood, glossy rubber, dope rubber, glossy paper, ordinary paper and the surface of a coffee plant’s leaf. We will discuss the finding of this experiment and also the methodology to be used to investigate the influence of polarized light to a spectral signature of a surface.
03/17 14:45-16:15 Mitsuteru Sato
The Global Lightning and Sprite Measurements on JEM-EF (JEM-GLIMS) mission started the nadir observations of lightning and transient luminous events (TLEs) from the ISS since November 20, 2012. On August 24, 2015, JEM-GLIMS successfully finished the continuous observations without any serious troubles. In this observation period, JEM-GLIMS detected a total of 8357 lightning events. In 699 of 8357 lightning events, impulsive far ultraviolet (FUV) emissions were simultaneously detected with the lightning emissions, which strongly support the occurrence of TLEs. In order to distinguish the weak sprite emissions from the incomparably intense lightning emissions, we adopted three analytical procedures, that is, (1) a subtraction of the wideband camera image from the narrowband camera image, (2) a calculation of the peak intensity ratio between different PH channels, and (3) an estimation of the polarization and charge moment changes (CMCs) of the suspected sprite-producing lightning discharges. Using these techniques, we have identified 42 sprite events, which correspond to 0.5% of the total lightning event number. We have statistically estimated the horizontal shift of the sprite locations from the peak intensity locations of the sprite-producing lightning emissions. The median and average values are estimated to be 13.6 km and 13.3 km, respectively. At the 42 sprite events, the delay time of the sprite FUV emissions from the parent lightning emissions is found to be less than 2 ms, which suggests that the sprites were short-delayed sprites. This fact is consistent with the previous reports by Lu et al. [2013]. Thus, the first quantitative spatial distributions of sprites and sprite-producing lightning discharges are revealed from the JEM-GLIMS nadir observations.