T. Tomida

The atmospheric transparency measured with a LIDAR system at the Telescope Array experiment

An atmospheric transparency was measured using a LIDAR with a pulsed UV laser (355 nm) at the observation site of Telescope Array in Utah, USA. The measurement at night for two years in 2007–2009 revealed that the extinction coefficient by aerosol at the ground level is 0.033−0.012+0.016km−1 and the vertical aerosol optical depth at 5 km above the ground is 0.035−0.013+0.019. A model of the altitudinal aerosol distribution was built based on these measurements for the analysis of atmospheric attenuation of the fluorescence light generated by ultra high energy cosmic rays.

An Event Reconstruction Method for the Telescope Array Fluorescence Detectors

We measure arrival directions, energies and mass composition of ultra‐high energy cosmic rays with air fluorescence detector telescopes. The longitudinal profile of the cosmic ray induced extensive air shower cascade is imaged on focal plane of the telescope camera. Here, we show an event reconstruction method to obtain the primary information from data collected by the Telescope Array Fluorescence Detectors. In particular, we report on an “Inverse Monte Carlo (IMC)” method in which the reconstruction process searches for an optimum solution via repeated Monte Carlo simulations including characteristics of all detectors, atmospheric conditions, photon emission and scattering processes.

Central Laser Facility Analysis at The Telescope Array Experiment

The Central Laser Facility (CLF) is the laser device which shoots the vertical laser. CLF is located at the Center of the Telescope Array (TA) experiment site. The TA has three fluorescence detectors. CLF is equidistant from three FD stations. We made the CLF simulation using the same program as the cosmic‐ray simulation. Using the CLF simulation, we reconstruct the energy shot by the CLF. In this paper, we describe some results of CLF reconstruction comparing the difference of reconstructed energy between two fluorescence telescopes.

All-solid-state rapidly tunable coherent 6-10 μm light source for lidar environmental sensing

We report on an all-solid-state rapidly tunable pulsed coherent 6-10 μm light source achieved in an optical parametric oscillator (OPO) pumped with an electronically tuned Cr:ZnSe laser and its application to lidar remote sensing for environmental detection. We designed a lidar system using the 6-10 μm light source and a telescope with a primary mirror of 50 cm and a high-efficient HgCdTe detector. The lidar system would be a valuable system in the measurement of chemical agents in the 100-300 m.

Remote sensing for physical geography from ISS by JEM-EUSO

Always, in the atmosphere of the earth we live in is a luminous phenomenona (Fluorescence by cosmic rays, lightning and aurora etc..) has been occurring. JEM-EUSO (Extreme Universe Space Observatory onboard Japanese Experiment Module) experiment is the observation that aims to capture the luminous phenomenon in earths atmosphere from orbit. JEM-EUSO telescope observations have been using a Fresnel lens of the worlds largest. The observation area (250km radius at the sea level) is extremely larger than the telescope installed on the ground to captures the luminous phenomenon. The main target of EUSO is to capture the fluorescence emission caused by UHECR (Ultra-High-Energy Cosmic Ray). This way that is extremely large observation area for UHECR will be frontier for astronomical observation of charged particles for relatively near space (50Mpc). Because JEM-EUSO observe fluorescence in the atmosphere of the earth from space, it is necessary to measure the state of the atmosphere (cloud cover and transparency in particular) for the calibration. The infrared camera mounted on the JEM-EUSO is used to measurement of cloud coverage and cloud top height. For the atmospheric transparency measurement and calibration of the cloud top height, we use the LIDAR system using EUSOs telescope and the laser. It is also possible that in addition to this, to know the state of the atmosphere based on the background light captured by EUSOs telescope. These measurements of atmospheric conditions for the observation of UHECRs is not only calibration data. The atmospheric observation that covers the entire ground is the vital information in the geophysical. Furthermore, it is possible to measure light emission by lightning or meteor that occur in the field of view during observation of darkness in the JEM-EUSO. Expected by combining a lot of measurement, to understand of the earth and proceed further.

Design and daytime performance of laser-induced fluorescence spectrum lidar for simultaneous detection of multiple components, dissolved organic matter, phycocyanin, and chlorophyll in river water.

In this work, we developed mobile laser-induced fluorescence spectrum (LIFS) lidar based on preliminary experiments on the excitation emission matrix of a water sample and a method for reducing solar background light using the synchronous detection technique. The combination of a UV short-pulse laser (355 nm, 6 ns) for fluorescence excitation with a 10-100 ns short-time synchronous detection using a gated image-intensified multi-channel CCD of the fluorescence made the LIFS lidar operation possible even in daytime. The LIFS lidar with this construction demonstrated the potential of natural river/lake water quality monitoring at the Tenryu River/Lake Suwa. Three main components in the fluorescence data of the water, dissolved organic matter, phycocyanin, and chlorophyll, were extracted by spectral analysis using the standard spectral functions of these components. Their concentrations were estimated by adapting experimentally calibrated data. Results of long-term field observations using our LIFS lidar from 2010 to 2012 show the necessity of simultaneous multi-component detection to understand the natural water environment.

Development of atmospheric transparency measurement system

The atmospheric transparency measurement for the telescope array (TA) experiment is made by using a back-scatter LIDAR system and the central laser facility (CLF) that is a bistatic LIDAR. Both systems use a pulsed energy tripled YAG laser (355 nm). However, these systems have complementary advantages and disadvantages. A new backscatter measurement has been added to the CLF making it possible to measure, atmospheric transparency at short distances close to the surface. This new system is called LIDAR@CLF. The system and its use are discussed.

Remote Detection of the Fluorescence Spectrum of Natural Pollens Floating in the Atmosphere Using a Laser-Induced-Fluorescence Spectrum (LIFS) Lidar

A mobile laser-induced fluorescence spectrum (LIFS) lidar was developed for monitoring pollens floating in the atmosphere. The fluorescence spectrum of pollens excited at 355 nm was measured with a fluorescence spectrometer and the results suggested that in general they had peaks at around 460 nm and the ranges were 400–600 nm. A fluorescence spectrum database of 25 different pollens was made with the 355 nm excitation. Based on these results, we developed a LIFS lidar that had features in pollen species identification and daytime operation. The former was achieved by the database and the latter was possible by introducing a synchronous-delay detection to a gated CCD spectrometer in an operation time of 200 ns. Fluorescence detection of pollens floating in the atmosphere was performed using the LIFS lidar in a field where cedars grow in the spring and ragweed in the autumn. The LIFS lidar system successfully detected fluorescence spectrums of the pollens at a distance of approximately 20 m away. We discussed the performance of the LIFS lidar by estimating the number of cedar pollens using a lidar equation, introducing a fluorescence cross section of cedar pollens and a sensitivity of the CCD spectrometer that was measured by ourselves.

A fluorescence lidar for seamlessly connecting individual observations of the global environmental systems

It is commonly said that the global environment structure is formed from the atmosphere, hydrosphere, geosphere, and biosphere, which are natural environment systems. In addition to this, we add another system “livingsphere” which is an artificial system, but holds strong relations between the daily lives of humans and the natural systems. It would then be appropriate to consider the global environment structure with the idea that natural systems and the artificial one are interconnected. We propose using fluorescence as a common parameter to understand the interconnection. Since a large variety of substances exhibit their own unique auto-fluorescence spectrum more or less if they are irradiated by light, they are good targets for fluorescence lidars. Lidar observation results about substances moving freely among the systems might offer information about the interconnection of each type of environment system. In this presentation, we show several experiments done using the fluorescence lidar we have developed for observing aerosol in the atmosphere, lake/river water quality in the hydrosphere, vegetation growth status in the biosphere, and pre-observing ground surface substances in the geosphere and waste substances of daily necessities in the livingsphere. We also describe a fluorescence database which is an EEM (Excitation-Emission-Matrix) of substances found elsewhere in the systems, and discuss an adaptation of the database to the atmospheric aerosols observation done by the fluorescence lidar.

TA fluorescence detector calibration by UV LED with an unmanned aerial vehicle

We are developing a fluorescence detector (FD) calibration device called as Opt-copter which consists of an UV LED, a high accuracy GPS and an unmanned aerial vehicle (UAV). Opt-copter is a standard light source to be used to calibrate the Telescope Array (TA) FDs. The primary characteristic of Opt-copter is its high portability which enables us to put the light source on any position we want in the F.O.V. of FDs. Our upgraded UAV, has improved flight reliability and payload capacity. The calibration procedure is established by a test observation at the TA FD site. We evaluated the flight accuracy and developed a method to measure the FD geometry. We will report the current status of Opt-copter.