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- Front Matter: Volume 8526
- Lasers for Lidar Remote Sensing
- Lidar Methods and Technologies
- Laser Ranging
- Meteorological Measurements (Wind and Water Vapor)
- Space Lidars and Applications
- Aerosol and Cloud Measurements
- Poster Session
Front Matter: Volume 8526
Front Matter: Volume 8526
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This PDF file contains the front matter associated with SPIE Proceedings Volume 8526, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.
Lasers for Lidar Remote Sensing
Conductive-cooled 2-micron laser development for wind and CO2 measurements
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We have developing two types of 2micron conductive-cooled lasers for wind and CO2 measurements. One type of lasers is side pumped Tm,Ho:YLF laser operated at 20-40Hz. The laser rod is cooled down to -80C and laser diodes are
operated at normal temperature in a vacuum container. With this type of laser, we have built up a coherent lidar system
which is used to measure wind and CO2 concentration. Ho:YLF laser end-pumped by Tm:fiber laser is another type
oscillator which will be operated at high repetition rate of 200-300 Hz in normal temperature. The laser will have an
amplifier. These lasers are conductive-cooled, solid-state, eye-safe and suitable for space applications.
1.5-μm high average power laser amplifier using an Er,Yb:glass planar waveguide for coherent Doppler LIDAR
Show abstract
We have developed a 1.5-μm eye-safe wavelength high average power laser amplifier using an Er,Yb:glass planar
waveguide for coherent Doppler LIDAR. Large cooling surface of the planar waveguide enabled high average power
pumping for Er,Yb:glass which has low thermal fracture limit. Nonlinear effects are suppressed by the large beam size
which is designed by the waveguide thickness and the beam width of the planar direction. Multi-bounce optical path
configuration and high-intensity pumping provide high-gain and high-efficient operation using three-level laser material.
With pulsed operation, the maximum pulse energy of 1.9 mJ was achieved at the repetition rate of 4 kHz. Output average
power of the amplified signal was 7.6W with the amplified gain of more than 20dB. This amplifier is suitable for
coherent Doppler LIDAR to enhance the measurable range.
All-solid-state rapidly tunable coherent 6-10 μm light source for lidar environmental sensing
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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.
Development of a simultaneous dual-wavelength Q-switched Nd:YAG laser at 1064 and 1319 nm
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A dual-wavelength Q-switched Nd:YAG laser operating at 1064 and 1319 nm is useful as a light source for simultaneous
lidar observations of a canopy height and a normalized difference vegetation index. In this study, simultaneous dualwavelength
lasing was achieved in a Q-switched Nd:YAG laser by optimizing the resonator designs for both
wavelengths and by adjusting a time interval between two Q-switch trigger pulses. Q-switched pulse energies of 6.9 and
6.2 mJ were obtained at 1064 and 1319 nm, respectively. A pulse-to-pulse amplitude fluctuation at each wavelength was
then measured to be less than ±9%.
Lidar Methods and Technologies
Study of fluorescence of atmospheric aerosols using a lidar spectrometer
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A lidar for measuring fluorescence from atmospheric aerosols was constructed with a third harmonic Nd:YAG laser, a 1-
m diameter telescope, and a 32-channel time-resolved photon counting spectrometer system. Fluorescence of aerosols in
the spectral range from 420 nm to 510 nm was studied with the excitation at 355 nm. The distribution of fluorescent
aerosols was studied in the time-height indications of the broad fluorescence. Type of the aerosols was identified from
simultaneous observation with a polarization lidar in the Asian dust and aerosol observation lidar network (AD-Net). It
was found that Asian dust and air-pollution aerosols transported from urban or industrial areas emit fluorescence.
Fluorescence efficiency was roughly estimated for these aerosols. The results suggest fluorescence measurements
combined with the measurement of microphysical parameters of aerosols using a multiple-wavelength Raman lidar or
high-spectral-resolution lidar will provide useful information for characterizing chemical properties of aerosols.
Application of lidar and optical data for oil palm plantation management in Malaysia
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Proper oil palm plantation management is crucial for Malaysia as the country depends heavily on palm oil as a major
source of national income. Precision agriculture is considered as one of the approaches that can be adopted to improve
plantation practices for plantation managers such as the government-owned FELDA. However, currently the
implementation of precision agriculture based on remote sensing and GIS is still lacking. This study explores the
potential of the use of LiDAR and optical remote sensing data for plantation road and terrain planning for planting
purposes. Traditional approaches use land surveying techniques that are time consuming and costly for vast plantation
areas. The first ever airborne LiDAR and multispectral survey for oil palm plantation was carried out in early 2012 to
test its feasibility. Preliminary results show the efficiency of such technology in demanding engineering and agricultural
requirements of oil palm plantation. The most significant advantage of the approach is that it allows plantation managers
to accurately plan the plantation road and determine the planting positions of new oil palm seedlings. Furthermore, this
creates for the first time, digital database of oil palm estate and the airborne imagery can also be used for related
activities such as oil palm tree inventory and detection of palm diseases. This work serves as the pioneer towards a more
frequent application of LiDAR and multispectral data for oil palm plantation in Malaysia.
Development of polarization optical particle counter to detect particle shape information
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Polarization optical particle counter (POPC) capable of measuring particle shape or sphericity was developed, which uses detection of polarization of light scattered by particles. Sensors that detected P and S polarization components are incorporated at scattering angle of 120˚ in addition to ordinary sensor located at the angle of 60˚. The particle size is derived from the pulse height detected with the ordinary sensor. The size thresholds were determined by measurements of PSL standard particles. Polarization of particle is calculated as the ratio of S polarization component to the sum of all components. The POPC field observations were started in Fukuoka, Japan on 15 March 2012 and in Matsue, Japan on 28 February 2012. Air pollution with high particle number concentration was observed in Fukuoka on 11 April. In that time, the particles with polarization lower than 0.3 constituted 90% of particles in the size range from 0.5 µm to 3 µm and 70-90% of those from 3 µm to 5 µm. Most of the atmospheric aerosol particles were consisted of spherical particles. Significant Asian dust transport was observed in Fukuoka on from 31 March to 1 April. The particles with polarization lower than 0.3 constituted 80% of those from 0.5 µm to 1 µm, 55-65% of those from 1 µm to 5µm. The increase of the ratio of non-spherical particles to all particles in Asian dust event was confirmed. The POPC thus is capable of measuring particle shape as well as size for each individual particle.
Laser Ranging
Lie-EM-ICP algorithm: a novel frame for 2D shape registration
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In this paper, a 2D shape registration algorithm for noisy data is established by combining the Iterative Closest
Point (ICP) method, Expectation Maximization (EM) method, and Lie Group representation. First, the problem
is formulated by a minimization problem with two sets of variables: the point-to-point correspondence, and the
transformation (i.e., rotation, scaling and translation) between two data sets. The conventional way for solving
this model is by iterating alternatively the following two steps: 1) having the transformation fixed, solve the
correspondence, and 2) having the correspondence fixed, solve the transformation. In our approach, to enhance
the robustness, the EM algorithm is introduced to find the correspondence by a probability which covers the
relationship of all points, instead of one-to-one closest correspondence in ICP. Meanwhile, Lie group is used to
parameterize transformation, i.e., in the iteration, the rotation, scaling and translation are all elements within
respective Lie groups, and we use the element of Lie algebra to represent that of Lie group near the identity via
exponential map. This forms a unified framework for registration algorithms. Then, transformation is estimated
by solving a quadratic programming. The experimental result in 2D shape registration demonstrates that,
compared with Lie-ICP, our algorithm is robuster and more accurate.
A study of lidar-based sense making and topographic mapping
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The paper presents a study of topographic mapping and sense making with LIDAR data and ground color map. The
objective is for possible alternative navigation in case the GPS service is not available. To achieve the objective, a few
LIDAR data filtering and image processing techniques are applied. From LIDAR data, an accurate digital elevation
model is first generated, then a progressive morphological filtering to remove such interference objects as trees for more
reliable matching afterwards. For topographic mapping, the processed LIDAR image and a ground map image are
segmented based on the Mean-Shift principle, segmenting the image into different color blocks, then extracting the
building color blocks and converting into binary image. Lastly based on the least sum of absolute value, we are able to
matching a LIDAR image with a real map image. By performing the effective image filtering and matching process, we
have successfully achieved accurate topographic matching based on real LIDAR measurement taken in Singapore. This
automatic processing is able to indicate exactly where the LIDAR image was taken.
Meteorological Measurements (Wind and Water Vapor)
Profiling tropospheric water vapour with a coherent infrared differential absorption lidar: a sensitivity analysis
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In the last decade the precision of coherent Doppler differential absorption lidar (DIAL) has been greatly improved in near and middle infra-red domains for measuring greenhouse gases such as CO2, CH4 and winds. The National Institute of Information and Communications Technology (NICT, Japan) has developed and is operating a CO2 and wind measuring ground-based coherent DIAL at 2.05 μm (4878 cm-1). The application of this technology from space is now considered. In this analysis we study the use of the NICT DIAL for profiling tropospheric water vapour from space. We present the methodology to select the spectral lines and summarized the results of the selected lines between 4000 and 7000 cm-1. The choice of the frequency offset, the pulse energy and repetition frequency are discussed. Retrieval simulations from the line at 4580 cm-1 (2.18 μm) suitable for the boundary layer and the stronger one at 5621 cm-1 (1.78 μm) for sounding the boundary layer and the middle troposphere, are shown.
Wind sensing demonstration of more than 30km measurable range with a 1.5 μm coherent Doppler lidar which has the laser amplifier using Er,Yb:glass planar waveguide
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Recently, we have developed the high output power laser amplifier using Er,Yb:glass planar waveguide in order to
increase the measurable range of our 1.5 μm coherent Doppler LIDAR (CDL). In this paper, we introduce this
development and demonstration of a long range wind sensing using the developed system. The transmitted pulse has a
peak power of 2.4 kW and a width of 580 ns (i.e. pulse energy of 1.4 mJ) with a pulse repetition frequency of 4 kHz, in
addition to a nearly diffraction limited beam quality. With this laser amplifier, we demonstrate the measurable range of
more than 30 km. According to our own research, this is the longest measurable range demonstration for wind sensing
CDLs.
Space Lidars and Applications
Remote sensing for physical geography from ISS by JEM-EUSO
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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
earth's atmosphere from orbit. JEM-EUSO telescope observations have been using a Fresnel lens of the world's
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 EUSO's
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 EUSO's 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.
i-LOVE: ISS-JEM lidar for observation of vegetation environment
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It is very important to watch the spatial distribution of vegetation biomass and changes in biomass over time,
representing invaluable information to improve present assessments and future projections of the terrestrial carbon cycle.
A space lidar is well known as a powerful remote sensing technology for measuring the canopy height accurately. This
paper describes the ISS(International Space Station)-JEM(Japanese Experimental Module)-EF(Exposed Facility) borne
vegetation lidar using a two dimensional array detector in order to reduce the root mean square error (RMSE) of tree
height due to sloped surface.
Simulation and visualization of echo signals from forest for iLOVE
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This paper describes the method and process of developing a forest echo signal simulator to be applied in “iLOVE” : Issjem
LiDAR Observation of Vegetation Environment. The goal of this study was to develop an echo signal simulation
model and to visualize the generation process of echo signals.
The simulator consists of four components: 1) terrain and features, 2) sensor configuration, 3) echo signal generation and
4) visualization. Terrain and feature data were defined to be full polygon object in 3D space. A laser beam refers to
numerous sub laser beams, with each sub laser beam featuring specific intensity based on TEM00. The time-series
intensity change of sub laser beams was based on Gaussian distribution.
At the start of the echo signal generating process, intersections between sub laser beams and target objects were
calculated. Then, echo signal of sub laser beams was calculated from the position of intersections, pulse width and
specific reflectance of target objects. Finally, an echo signal suitable for footprint size was calculated by synthesizing
echo signals of sub laser beams. Meanwhile, intersections were drawn in 3D on the surface of target objects.
The results indicated that the simulator was highly useful for understanding the relationship between the echo signal and
the structure of target objects, and also for developing algorism for forest applications.
Measuring forest canopy height using ICESat/GLAS data for applying to Japanese spaceborne lidar mission
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We developed a methodology to estimate the canopy height from the ICESat/GLAS waveform for the purpose of
contributing to the design of the Japanese spaceborne LiDAR mission; iss-jem LiDAR for Observation of Vegetation
Environment (i-LOVE). We adopted an estimation method using a terrain index, which indicates the steepness of ground
surface, to accurately estimate the canopy height in sloped areas. The study area is Hokkaido Island. We conducted a
ground survey and collected airborne LiDAR data to use as the ground truth for the canopy height. We then developed
some models to estimate the canopy height from a GLAS waveform. As a result, the estimation accuracy decreased in
steep sloped areas where the terrain index exceeded 15 m. To reduce the influence of this effect, the estimation equation
was separated for a gentle slope (terrain index ≤ 15 m) and a steep slope (terrain index < 15 m). In this case, RMSE was
3 to 5 m. These findings indicated that an accurate estimation method would be ensured by using a footprint of less than
15 m of terrain index for the i-LOVE mission. On the assumption of a forested area located primarily at less than a 30°
surface slope on a global scale, it is recommended that the diameter of the i-LOVE footprint should be less than 25 m. i-
LOVE is planned to transmit four laser pulses arranged at 2×2 simultaneously. This characteristic of i-LOVE, which
does not require DEM, makes it possible to calculate the terrain index accurately and has a large advantage for accurately
estimating the canopy height on a global scale.
Aerosol and Cloud Measurements
Lidar remote sensing of atmospheric aerosol and cloudiness: Monte Carlo modeling
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The light haze of a ground-based impulse LIDAR in an altitude-wise optically inhomogeneous cloud-free atmosphere was computed in dependence of various optical-geometrical parameters of the experiment using the Monte Carlo method. Modeling of the LIDAR echo-signal reflected off the lower boundary of a liquid droplet cloud for a ground-based LIDAR and off the upper boundary of the cloud for an aircraft- and space-based LIDAR was also completed. A feature of these calculations is the choice of the model with altitude-wise statistically inhomogeneous structure of aerosol scattering parameters as the optical model of a cloudless atmosphere. The echo-signals from clouds were computed in the assumption of statistical variation of the altitudes of the lower and upper cloudiness boundaries. In the calculations new effective discrete-stochastic modifications of local estimates were employed.
Interaction between the low altitude atmosphere and clouds by high-precision polarization lidar
Show abstract
Lidar is a powerful remote sensing tool to monitor the weather changes and the environmental issues. This technique
should not been restricted in those fields. In this study, the authors aim to be apply it to the prediction of weather
disaster. The heavy rain and the lightning strike are our targets. The inline typed MPL (micro pulse lidar) has been
accomplished to grasp the interaction between the low altitude cloud and the atmosphere and to predict the heavy rain,
while it was hard to catch the sign of lightning strike. The authors introduced a new algorism to catch the direct sign of
the lightning strike. Faraday effect is caused by lightning discharge in the ionized atmosphere. This effect interacts with
the polarization of the propagating beam, that is, the polarization plane is rotated by the effect. In this study, high
precision polarization lidar was developed to grasp the small rotation angle of the polarization of the propagating beam.
In this report, the interaction between the low altitude cloud and the atmosphere was monitored by the high precision
polarization lidar. And the observation result of the lightning discharge were analyzed.
Low altitude fog-haze measurements by Raman-Rayleigh-Mie lidar in Nanjing
Show abstract
This paper presents the Fog-Haze measurements by Raman-Rayleigh-Mie Lidar in North suburb of Nanjing,
the measurement results are analyzed and compared with the weather forecast. Continuous measurements are
carried out on 2009/12/2, it is clear day from 01:00 to 08:00 in the morning, and Fog-Haze is measured from
at 10:00 in the morning to 19:00 in the evening. The Fog-Haze measurement results coincide with the weather
forecast that very day. The Fog-Haze Lidar measurement results on 2009/12/2 are analyzed and compared
with the boundary aerosol measurement results on 2010/01/10, the differential characters of
range-corrected-signals between Fog-Haze and boundary aerosol are discussed. It is shown that Fog-Haze
usually occurs at about 300-400m height and boundary aerosol usually occurs at about 1000m height in
Nanjing.
Keywords:
Improvement of NIES lidar network observations by adding Raman scatter measurement function
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We have conducted ground-based lidar network observations in wide areas of East Asia using two-wavelength (532 and
1064nm) backscatter and one-wavelength (532nm) depolarization Mie-scatter lidars for more than ten years. To realize
more advanced aerosol classification and retrieval, we improved the Mie-scatter lidars at several main sites by adding a
N2 Raman scatter measurement channel (607nm). This Mie-Raman lidar system provides 1α+2β+1δ data at nighttime: extinction coefficient (α) at 532nm, backscatter coefficients (β) at 532 and 1064nm, and depolarization ratio (δ) at 532nm. We also developed an algorithm to estimate vertical profiles of 532nm extinction coefficients of black carbon,
dust, sea-salt, and air-pollution aerosols consisting of a mixture of sulfate, nitrate, and organic carbon substances
(SF-NT-OC) using the 1α+2β+1δ data. With this method, we assume an external mixture of aerosol components and prescribe their size distributions, refractive indexes, and particle shapes. The measured lidar data are automatically
transferred to the NIES data server. We developed an algorithm to estimate particle optical properties (1α+2β+1δ data),
planetary boundary layer (PBL) height, and scene classification identifiers representing molecule-rich, aerosol-rich, or
cloud-rich layer automatically and provide their quick-looks in semi-realtime on the website
(http://www-lidar.nies.go.jp/shingakujutsu/Raman/).
Observation and analysis of urban boundary layer characteristics with Raman-Mie lidar
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Long-term observations of atmosphere aerosol optical properties over Xi’an area have been carried out by a Raman-Mie
lidar and a Micro-pulsed 3D Scanning Mie lidar, which were built at Xi’an University of technology with the laser
wavelength of 355nm and 532nm, respectively. The Raman-Mie lidar is used for observation of the atmospheric
temperature, water vapor and aerosol profiles simultaneously. In order to deeply discuss the temporal-spatial evolution of
the mixed-layer within the urban boundary layer (UBL), the method of combining the absolute minimum of first
derivative and second derivative of the range-squared-corrected signal (RSCS) of lidar was used to retrieve the
mixed-layer depth (MLD). By using continuous observations of 24-hour (THI display), the MLD in temporal and spatial
variation are clearly revealed. Also, the results of continuous observations from July 2006 to October 2011 have been
analyzed for revealing the seasonal cycle and the annual cycle of the MLD. By analyzing the average MLD, it is
obviously shown that the MLD of seasonal cycle is higher in summer than in winter over Xi’an area. Otherwise, by
investigating the relationship of atmospheric boundary layer height, relative humidity and temperature, and the
dependence characteristics and a general disciplinarian between them are then obtained. The achievement is of great
importance for studying the proliferation of urban pollution and obtaining a complete meteorological status of the urban
atmosphere.
Typical patterns of PBL structure and dynamics in transitional ocean-continent zone in summer and winter in Far East region
Show abstract
The paper is connected with planetary boundary layer (PBL) the lowermost part of the atmosphere its structure and
dynamics investigations in the Far Eastern coastal zone in winter and summer. The data have been analyzed were
obtained by means of aerosol polarization lidar. Mean values of PBL height, top of the convective layer and mean height
of the nocturnal layer were presented. Well-developed nocturnal convection in the PBL was analyzed and explained. On
the example of several summer days specific features of the PBL structure and dynamics are identified, presented and
analyzed. Maximal values of breeze circulation heights are also presented.
Poster Session
Three-year program to improve critical 1-micron Qsw laser technology for Earth observation
Show abstract
Laser remote sensing technologies are valuable for a variety of scientific requirements. These measurement techniques
are involved in several earth science areas, including atmospheric chemistry, aerosols and clouds, wind speed and
directions, prediction of pollution, oceanic mixed layer depth, vegetation canopy height (biomass), ice sheet, surface
topography, and others. Much of these measurements have been performed from the ground to aircraft over the past
decades. To improve knowledge of these science areas with transport models (e.g. AGCM), further advances of vertical
profile are required.
JAXA collaborated with NICT and RIKEN started a new cross-sectional 3-year program to improve a technology
readiness of the critical 1-micron wavelengths from 2011. The efficient frequency conversions such as second and third
harmonic generation and optical parametric oscillation/generation are applied. A variety of elements are common issues
to lidar instruments, which includes heat rejection using high thermal conductivity materials, laser diode life time and
reliability, wavelength control, and suppression of contamination control. And the program has invested in several
critical areas including advanced laser transmitter technologies to enable science measurements and improvement of
knowledge for space-based laser diode arrays, Pockels cells, advanced nonlinear wavelength conversion technology for
space-based LIDIRs. Final goal is aim to realize 15 watt class Q-switched pulse laser over 3-year lifetime.
Remote sensing of hydrogen gas concentration distribution by Raman lidar
Show abstract
Hydrogen is expected to become an energy source in the next generation. Although hydrogen gas is a combustible gas
with a large explosion concentration range, leakage is presently monitored by contact type gas sensors. The technology
for locating a leak and remote sensing of gas concentration distribution is required in case of hydrogen gas leaks. In this
study, remote sensing technology of hydrogen gas concentration distribution using a Raman lidar was developed. The
lidar system consisted of a pulsed Nd:YAG laser of wavelength 354.7 nm and a Galilean telescope of aperture 170 mm.
The system could detect hydrogen gas by vibrational Raman scattering. In this method, hydrogen gas concentration
could be measured based on the ratio of the Raman scattering signals from hydrogen gas and from atmospheric nitrogen,
which were simultaneously measured. In this manner, the geometrical form factor of the biaxial lidar and the
instrumental function were canceled. Hydrogen gas concentration of 0.6-100% could be measured at a distance 13m
using this system.
The characteristics of solid etalon Doppler discriminator and transmitter in designing Doppler lidar
Show abstract
In this paper, we propose a new type of Doppler discrimination system using an unseeded pulsed Q-switched laser and
solid etalon. To substantiate our system, we calculate the transmitting spectral power distribution and discriminator
characteristics. In our calculation, we use a 25 mm thick solid etalon with a finesse of 30, as well as a normal pulsed
laser with a bandwidth of 1 cm-1. The results reveal that the change in the receiving scattered signal through the
discriminator with a given LOS(Line of Sight) wind velocity is more sensitive than a normal iodine metal vapor-based
Doppler lidar receiving system. We experimentally verify our suggestion using our Doppler discriminator and
transmitter, and confirm that this combination is more sensitive than a metal vapor filter. Moreover, we suggest a more
efficient transmitter and a more sensitive double-edge receiving system based on our calculations and experimental
results.
Performance evaluation of coherent 2-µm differential absorption and wind lidar for wind measurement
Show abstract
A coherent 2-μm differential absorption and wind lidar (Co2DiaWiL) has been built with a high power Q-switched
Tm,Hm:YLF laser to measure CO2 concentration and radial wind velocity. Our experiment was conducted to test the
ability of the Co2DiaWiL to make wind measurement in the atmospheric boundary layer and lower free troposphere. The bias in the velocity measurement was estimated as –0.0069 m/s using measurements from a stationary hard target. The magnitude of the random error of radial velocity measurements was determined from data in the vertical pointing mode and the Co2DiaWiL achieved a velocity precision of 0.12 m/s. The radial velocity measurements to ranges up to 20-25 km by the horizontally fixed beam mode for average times of 1 min have been demonstrated with the high laser output power. The Co2DiaWiL-measured radial velocities were directly compared with the wind speeds measured by a closelylocated sonic anemometer. The correlation coefficient was as large as 0.99 for comparison of radial velocities averaged for 1 min from the Co2DiaWiL and sonic anemometer.
Evaluation of water vapor Raman lidar signals from clouds
Show abstract
Raman lidar is commonly used for measurement of water vapor profiles in the lower atmosphere. However, the
treatment of the Raman lidar signals from clouds is not well established. A simplified model taking multiple scattering
into account is proposed. The model results in a difference of two exponential functions, one which represents the
extinction of laser light inside the cloud, and another which represents the effect of multiple scattering. The model was
applied to measurement results using a Raman lidar system consisting of a laser wavelength of 280 nm and detection
channels for Raman scattering from water vapor and atmospheric nitrogen. When a cloud was present in the field of view
of the lidar, the water vapor Raman scattering signal increased from almost zero at the cloud base to a maximum at a
penetration distance of about 50 m, whereas the nitrogen Raman scattering signal decreased monotonously beyond the
cloud base. This behavior could be explained by the model, and the measured signals could be adequately reproduced by
setting the decay constant of one exponential function equal to the attenuation coefficient of the nitrogen Raman
scattering signal, and optimizing the decay constant of the other exponential function. Comparison of measurement
results and calculation results based on the model showed that the model is mainly applicable to optically thick clouds,
for which the attenuation coefficient is larger than 0.02 m-1.
Meteorological observation with Doppler and Raman lidars and comparison with numerical weather simulations
Show abstract
Meteorological observation data such as temperature, humidity, wind speed and wind direction are important for
validating and improving numerical weather simulation models. Lidar is an effective method for acquiring such data
with high range resolution and short time intervals. In this study, we carried out a field observation with coherent
Doppler Lidar and Raman Lidar systems at the coastal area of Yokosuka, Japan, and compared the observed data with
the results of numerical weather simulations. We obtained the vertical profiles of horizontal wind speeds and wind
directions by Doppler Lidar with 65 m vertical range resolution, and the vertical profiles of the water vapor mixing ratio
by Raman Lidar with 20 m vertical range resolution at the lower atmospheric boundary layer (200-600 m height from
ground level). These data were acquired at time intervals of 10 minutes. We found an interesting phenomenon from
observed data indicating that, under weak wind conditions, water vapor in the atmosphere significantly increased just
after a definite change in wind direction from land breeze to sea breeze. A similar phenomenon was also predicted by the
numerical weather simulation with the same meteorological and terrestrial conditions. We analyzed the numerical results
and found that the change in water vapor mentioned above is mainly caused by the difference between the evaporation
from land and sea surfaces, which were located upwind of the land and sea breezes, respectively.
Observation of aerosol parameters at Saga using GOSAT product validation lidar
Show abstract
Greenhouse gases Observation SATellite (GOSAT) was launched to enable the precise monitoring of the density
of carbon dioxide by combining global observation data sent from space with data obtained on land, and with
simulation models. In addition, observation of methane, another greenhouse gas, has been considered. For
validation of GOSAT data products, ground-base observation with Fourier Transform Spectrometer (FTS),
aerosol lidar and ozone-DIAL (DIfferencial Absorption Lidar) at Saga University, JAPAN has been continued
since March, 2011. In this article, observation results obtained from aerosol lidar are reported.