This PDF file contains the front matter associated with SPIE Proceedings Volume 9262, including the Title Page, Copyright information, Table of Contents, Authors, Introduction (if any), and Conference Committee listing.

Spaceborne integrated path differential absorption (IPDA) lidar is an active-detection system which is able to perform global CO₂ measurement with high accuracy of 1ppmv at day and night over ground and clouds. To evaluate the detection performance of the system, simulation of the ground return signal and retrieval algorithm for CO₂ concentration are presented in this paper. Ground return signals of spaceborne IPDA lidar under various ground surface reflectivity and atmospheric aerosol optical depths are simulated using given system parameters, standard atmosphere profiles and HITRAN database, which can be used as reference for determining system parameters. The simulated signals are further applied to the research on retrieval algorithm for CO₂ concentration. The column-weighted dry air mixing ratio of CO₂ denoted by XCO₂ is obtained. As the deviations of XCO₂ between the initial values for simulation and the results from retrieval algorithm are within the expected error ranges, it is proved that the simulation and retrieval algorithm are reliable.

We are developing a 2-micron Ho:YLF laser end-pumped by Tm:fiber laser. The oscillator has ring resonator of 3m length. The laser is operated at high repetition rate of 200-5000 Hz in room temperature. The oscillator and amplifier system showed outputs of about 9W in CW and more than 6W in Q-switched operation. This laser will be used for wind and CO₂ concentration measurements.

In this paper, we propose a diode laser based differential absorption lidar (DIAL) for measuring lower-tropospheric water vapor profile using the modulated pulse technique. The transmitter is based on single-mode diode laser and tapered semiconductor optical amplifier with a peak power of 10W around 800nm absorption band, and the receiver telescope diameter is 35cm. The selected wavelengths are compared to referenced wavelengths in terms of random error and systematic errors. The key component of modulated pulse technique, a macropulse, is generated with a repetition rate of 10 kHz, and the modulation within the macropulse is coded according to a pseudorandom sequence with 100ns chip width. As a result, we evaluate both single pulse modulation and pseudorandom coded pulse modulation technique. The water vapor profiles conducted from these modulation techniques are compared to the real observation data in summer in Japan.

A new generation of flash LiDAR sensor called GLidar-I is presented in this paper. The GLidar-I has been being developed by Guilin University of Technology in cooperating with the Guilin Institute of Optical Communications. The GLidar-I consists of control and process system, transmitting system and receiving system. Each of components has been designed and implemented. The test, experiments and validation for each component have been conducted. The experimental results demonstrate that the researched and developed GLiDAR-I can effectively measure the distance about 13 m at the accuracy level about 11cm in lab.

A new advanced scanning multi-wavelength polarization Raman lidar system has been designed and implemented. It is three transmitted wavelengths and eight receiver channels. Nd:YAG laser emits simultaneously at 355, 532, and 1064 nm. The elastically backscattered signals, again with polarization discrimination at 355 and 532 nm, the nitrogen Raman signals at 387 and 607 nm, and the water-vapor Raman signal at 407 nm are detected. Vertical profiles of the three backscatter coefficients at 355, 532, and 1064 nm, of the two extinction coefficients at 355 and 532 nm, are determined both by Klett-Fernald and Raman method. The microphysical particle parameters are retrieved from backscatter coefficients at three wavelengths and extinction coefficients at two wavelengths by regularization. We selected experimental data of typical weather from the measurement areas both Bejing and Dunhuang in different weather, e.g. cloudy, clear, haze. The experiment results were derive by inversion, and they mainly include temporal evolution of the two extinction coefficients at 355 and 532 nm, the three backscatter coefficients at 355, 532, and 1064 nm, effective radius, PM2.5, and PM10. Our aim is to study the aerosol properties directly at source in order to analyze the transportation path for pollution and dust aerosol by the temporal evolution of PM2.5 and PM10.

The indispensable access to real turbulent wake behavior is provided by the pulsed coherent Doppler Light Detection and Ranging (LIDAR) which operates by transmitting a laser beam and detecting the radiation backscattered by atmospheric aerosol particles. The Doppler shift in the frequency of the backscattered signal is analyzed to obtain the line-of-sight (LOS) velocity component of the air motion. From the LOS velocities the characteristic of the turbulent wake can be deduced. The Coherent Doppler LIDAR (CDL) is based on all-fiber laser technology and fast digital-signal-processing technology. The 1.5 µm eye-safe Doppler LIDAR system has a pulse length of 200ns and a pulse repetition frequency of 10 kHz. The speed measurement range is ±50m/s and the speed measurement uncertainty is 0.3 m/s. The 2-axis beam scanner and detection range of 3000m enable the system to monitor the whole wind farming filed. Because of the all-fiber structure adoption, the system is stable, reliable and high-integrated. The wake vortices of wind turbine blades with different spatial and temporal scales have been observed by LIDAR. In this paper, the authors discuss the possibility of using LIDAR measurements to characterize the complicated wind field, specifically wind velocity deficit and terrain effects.

Vertical profiles of the linear particle depolarization ratio p δ of cloud and aerosol in the Tibet Plateau were measured during the Tibetan Plateau atmospheric expedition experiment campaign with water vapor, cloud and aerosol lidar system, which is capable of depolarization ratio measurement. The atmospheric comprehensive observations were performed during July of 2013 at Litang (30.03°N,100.28°E), which is 3949 meters above the mean sea level, Sichuan province, China. It was the first time to detect and obtain the Tibetan Plateau cloud and aerosol lidar depolarization profiles to our knowledge. After completing the plateau experiment campaign, the lidar system measured the atmosphere above coastal area in Qingdao (36.165°N,120.4956°E). In this year, we continued to participate in the plateau experiment campaign in Nagchu (31.5°N,92.05°E), which is 4600 meters above the mean sea level, The Tibet Autonomous Region from 1st, July to 1st, September. Since particle size, shape and refractive index have an impact on linear particle depolarization ratio, one can classify the aerosol types and cloud phase in turn in the Tibetan Plateau and Qingdao area using linear particle depolarization ratio data. Generally, two calibration methods were applied: comparison of the lidar measurement data and CALIPSO simultaneous data method and half-wave plate ±45°switch method. In this paper we applied the comparison calibration method. The correlation coefficient between lidar measurement data and CALIPSO data reaches up to 84.92%, which shows great linear relation. Finally, after the calculation and calibration of the linear particle depolarization ratio measured during the plateau experiment campaign and observation in coastal area, the ice-water mixed cloud (0.15< p δ <0.5), water cloud ( p δ <0.15) and dusty mix(0.2< p δ <0.35) in Tibetan Plateau were occurred and classified. Meanwhile, the cirrus clouds ( p δ <0.5), water cloud, smoke and urban pollution (0.05< p δ <0.2) and dusty mix in Qingdao area were also occurred and classified.

The data from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite was used to analyze the aerosol micro-physical properties over Beijing and surrounding area during haze periods from 2007 to 2008 in this paper. The results showed as follows. The values of TABC (total attenuated backscatter coefficient) for aerosols accounted for about 25% with varying altitudes. The aerosol scattering ability little changed from 0-4 km, showing that the aerosol layer evenly distribute. At different altitude ranges (0-1, 1-2, 2-3 and 3-4 km above ground level), values of TABC almost concentrate in the range of 2.5×10^-3 -4.5×10^-3 km^-1.sr^-1. In spring, summer and winter, aerosol scattering has the similar variation, with the maximum of TABC ranging from 3.5×10^-3 km^-1.sr^-1 to 4.5×10^-3 km^-1.sr^-1, while the maximum of TABC in autumn is from 1.5×10^-3 km^-1.sr^-1 to 2.5×10^-3 km^-1.sr^-1. Aerosol shape and size are characterized by VDR (volume depolarization ratio) and TACR (total attenuated color ratio). Aerosols with VDR greater than 10% were more than the ones with VDR less than 10% at the same altitude range. Notably, aerosols with smaller VDR (0-10%) appeared more frequently in autumn than those in the other three seasons. For each altitude range, aerosols with TACR ranging from 0-0.2 contributed much more than those with TACR ranging from 1.8-2.0. The size of aerosols in summer was the largest and that in autumn was the smallest in middle and lower troposphere.

Continuous observations of aerosols are being conducted with the Asian Dust and aerosol lidar observation Network (AD-Net). Currently, two-wavelength (1064 nm and 532 nm) polarization-sensitive (532 nm) lidars are operated at 20 stations in East Asia. At the primary stations (6 stations), nitrogen vibrational Raman scattering is also measured to obtain the extinction coefficient at 532 nm. Recently, continuous observations with a three-wavelength (1064 nm, 532 nm and 355 nm) lidar having a high-spectral-resolution receiver at 532 nm and a Raman receiver at 355 nm and polarization-sensitive receivers at 532 nm and 355 nm) was started in Tsukuba. Also, continuous observations with multi-wavelength Raman lidars are being prepared in Fukuoka, Okinawa Hedo, and Toyama. A data analysis method for deriving distributions of aerosol components (weak absorption fine (such as sulfate), weak absorption coarse (sea salt), strong absorption fine (black carbon), non-spherical (dust)) has been developed for these multi-parameter lidars. Major subjects of the current studies with AD-Net include data assimilation of multi-parameter lidars, mixing states of Asian dust with air pollution particulate matter, and validation of EarthCARE ATLID based on the aerosol component analysis method.

Ceilometer instruments are simple backscatter lidar systems and are usually set in airports for detecting the base of clouds. The instrument can also measure aerosol vertical distribution. Since ceilometers barely detect the molecular backscatter signals, retrieval of aerosol optical properties is an issue. This study investigates applicability of ceilometers to retrieval of optical properties. We make an idealized signal profile with the lidar ratio of 50 sr and calculate the retrieval errors caused by 30% errors of lidar ratio. In the forward inversion, useable (small error) optical properties are backscattering coefficients and the retrieval errors are less than 15% if the aerosol optical depth (AOD) is less than 0.2. The initial backscattering coefficients must be determined from other instruments (e.g., multi-wavelength lidar). Whereas in the backward inversion, if the AOD of idealized signals is larger than 1.5, extinction coefficients converge to the true value (within 5% errors), regardless of lidar ratios and initial conditions. Since there is no need for the system constant or molecular backscatter in this method, ceilometers can be an effective tool for retrieving extinction coefficients of dense aerosols in East Asia.

Airborne bathymetric lidar (Light Detection and Ranging) systems measure photoelectrons on the optical path (range and angle) at the photocathode of a returned laser pulse at high rates, such as every nanosecond. The collected measurement of a single pulse in a time series is called a waveform. Based on the calibration of the lidar system, the return signal is converted into units of received power. This converted value from the lidar waveform data is used to compute an estimate of the reflectance from the returned backscatter, which contains environmental information from along the optical path. This concept led us to develop a novel tool to visualize lidar data in terms of the returned backscatter, and to use this as a data analysis and editing tool. The full lidar waveforms along the optical path, from laser points collected in the region of interest (ROI), are voxelized into a 3D image cube. This allows lidar measurements to be analyzed in three orthogonal directions simultaneously. The laser pulse return (reflection) from the seafloor is visible in the waveform as a pronounced "bump" above the volume backscatter. Floating or submerged objects in the water may also be visible. Similarly, forest canopies and tree branches can be identified in the 3D voxelization. This paper discusses the possibility of using this unique three-orthogonal volume visualizing tool to extract environmental information for carrying out rapid environmental assessments over forests and water.

Ground-based LiDAR is one of the most effective city modeling tools at present, which has been widely used for three-dimensional reconstruction of outdoor objects. However, as for indoor objects, there are some technical bottlenecks due to lack of GPS signal. In this paper, based on the high-precision indoor point cloud data which was obtained by LiDAR, an international advanced indoor mobile measuring equipment, high -precision model was fulfilled for all indoor ancillary facilities. The point cloud data we employed also contain color feature, which is extracted by fusion with CCD images. Thus, it has both space geometric feature and spectral information which can be used for constructing objects’ surface and restoring color and texture of the geometric model. Based on Autodesk CAD platform and with help of PointSence plug, three-dimensional reconstruction of indoor whole elements was realized. Specifically, Pointools Edit Pro was adopted to edit the point cloud, then different types of indoor point cloud data was processed, including data format conversion, outline extracting and texture mapping of the point cloud model. Finally, three-dimensional visualization of the real-world indoor was completed. Experiment results showed that high-precision 3D point cloud data obtained by indoor mobile measuring equipment can be used for indoor whole elements’ 3-d reconstruction and that methods proposed in this paper can efficiently realize the 3 -d construction of indoor whole elements. Moreover, the modeling precision could be controlled within 5 cm, which was proved to be a satisfactory result.

The state-of-the-art remote sensing technologies, namely Unmanned Aerial Vehicle (UAV) based oblique imaging and Mobile Laser Scanning (MLS) show great potential for spatial information acquisition. This study investigated the combination of the two data sources for 4D modelling of roadside pole-like objects. The data for the analysis were collected by the Microdrone md4-200 UAV imaging system and the Sensei MLS system developed by the Finnish Geodetic Institute. Pole extraction, 3D structural parameter derivation and texture segmentation were deployed on the oblique images and point clouds, and their results were fused to yield the 4D models for one example of pole-like objects, namely lighting poles. The combination techniques proved promising.

Light Detection and Ranging (LiDAR) and Synthetic Aperture Radar (SAR) are two competitive active remote sensing techniques in forest above ground biomass estimation, which is important for forest management and global climate change study. This study aims to further explore their capabilities in temperate forest above ground biomass (AGB) estimation by emphasizing the spatial auto-correlation of variables obtained from these two remote sensing tools, which is a usually overlooked aspect in remote sensing applications to vegetation studies. Remote sensing variables including airborne LiDAR metrics, backscattering coefficient for different SAR polarizations and their ratio variables for Radarsat-2 imagery were calculated. First, simple linear regression models (SLR) was established between the field-estimated above ground biomass and the remote sensing variables. Pearson’s correlation coefficient (R²) was used to find which LiDAR metric showed the most significant correlation with the regression residuals and could be selected as co-variable in regression co-kriging (RCoKrig). Second, regression co-kriging was conducted by choosing the regression residuals as dependent variable and the LiDAR metric (Hmean) with highest R² as co-variable. Third, above ground biomass over the study area was estimated using SLR model and RCoKrig model, respectively. The results for these two models were validated using the same ground points. Results showed that both of these two methods achieved satisfactory prediction accuracy, while regression co-kriging showed the lower estimation error. It is proved that regression co-kriging model is feasible and effective in mapping the spatial pattern of AGB in the temperate forest using Radarsat-2 data calibrated by airborne LiDAR metrics.

This study was to attempt the cutting-edge 3D remote sensing technique of static terrestrial laser scanning (TLS) for parametric 3D reconstruction of juvenile understory trees. The data for test was collected with a Leica HDS6100 TLS system in a single-scan way. The geometrical structures of juvenile understory trees are extracted by model fitting. Cones are used to model trunks and branches. Principal component analysis (PCA) is adopted to calculate their major axes. Coordinate transformation and orthogonal projection are used to estimate the parameters of the cones. Then, AutoCAD is utilized to simulate the morphological characteristics of the understory trees, and to add secondary branches and leaves in a random way. Comparison of the reference values and the estimated values gives the regression equation and shows that the proposed algorithm of extracting parameters is credible. The results have basically verified the applicability of TLS for field phenotyping of juvenile understory trees.

Bathymetric lidar has been widely used for ocean floor mapping. By identifying two distinctive return peaks, one from the water surface and the other from the bottom, the water depth can be estimated. In addition to bathymetry, it is also possible to estimate the optical properties of the water by analyzing the lidar return waveform. Only the few systems (e.g. Optech’s SHOALS and CZMIL systems) that have good radiometric calibration demonstrate the capability to product the water’s inherent optical properties and bottom reflectance. As the laser pulse propagates through the water, it is scattered by the water constituents. The directional distribution of scattered radiant power is determined by the volume scattering function. Only the backscattering within a very narrow solid angle around the 180° scattering angle travels back to the detector. During the two-way travel it experiences the same optical interaction (absorption and scattering) with the water constituents. Thus, the lidar return waveform between the surface and bottom peak contains information about the vertical distribution of the water attenuation coefficient and the backscattering coefficient in the form of the rate of change of the return power. One challenge is how to estimate the inherent attenuation from the apparent attenuation. In this research we propose a technique to estimate the true water attenuation coefficient from the total system attenuation. We use a lidar waveform simulator that solves the irradiance distribution on the beam cross-section using an analytical Fourier transform of the radiance based on a single-scattering approximation.

The Asia-Pacific ocean region is one of the areas where airborne lidar is a promising tool for depth measurement. The anticipated efficiency of a laser bathymetry survey of a coastal zone in the region varies with the optical characteristics of the water. Near-shore waters in open areas of several countries (Philippines, Indonesia, Taiwan, and the east coast of South Korea) may be described as Class II in the Jerlov ¹ classification (turbid tropical-subtropical water), while water properties in internal seas are described as Classes 1 to 9 (coastal waters of increasing turbidity); the optical characteristics of the coastal waters of the East China Sea are beyond the Jerlov classification. In this paper, the applicability of the CZMIL (Coastal Zone Mapping and Imaging Lidar) ^{2, 3} system developed by Optech is considered for lidar bathymetry in the Asia-Pacific region. The Optech CZMIL has several attributes that enable it to significantly improve seafloor detectability in shallow and, in particular, turbid waters, namely a high-energy laser, a short system response function, increased receiver sensitivity, and high point density. The system capability was tested in a relatively turbid area of the Gulf Coast of Mississippi. The maximal depth for bathymetry with the CZMIL system is estimated theoretically in various countries, accounting for the spatial and seasonal variability of the internal optical properties of near-shore water

In this paper, we present examples of aerosol and Cirrus cloud altitude profiles over Hanoi, Vietnam, measured with the ground LIDAR setup of the Institute of Physics. Comparisons are made to LIDAR data collected by the Calipso satellite of the NASA A-Train during its orbits over the Hanoi area. The height distributions for both surface aerosols and Cirrus clouds derived from ground and satellite observations are generally consistent, with distributions between 2km-3km, and 8km-15km respectively for aerosols and Cirrus clouds. Cirrus cloud locations inferred from an analysis of limb spectral radiances obtained by the SCIAMACHY satellite are also consistent with the LIDAR data.

Accurate tree-level characteristic information is increasingly demanded for forest management and environment protection. The cutting-edge remote sensing technique of terrestrial laser scanning (TLS) shows the potential of filling this gap. This study focuses on exploring the methods for deriving various tree stem structural parameters, such as stem position, diameter at breast height (DBH), the degree of stem shrinkage, and the elevation angle and azimuth angle of stem inclination. The data for test was collected with a Leica HDS6100 TLS system in Seurasaari, Southern Finland in September 2010. In the field, the reference positions and DBHs of 100 trees were measured manually. The isolation of individual trees is based on interactive segmentation of point clouds. The estimation of stem position and DBH is based on the schematic of layering and then least-square-based circle fitting in each layer. The slope of robust fit line between the height of each layer and DBH is used to characterize the stem shrinkage. The elevation angle of stem inclination is described by the angle between the ground plane and the fitted stem axis. The angle between the north direction and the fitted stem axis gives the azimuth angle of stem inclination. The estimation of the DBHs performed with R square (R²) of 0.93 and root mean square error (RMSE) of 0.038m.The average angle corresponding to stem shrinkage is -1.86°. The elevation angles of stem inclinations are ranged from 31° to 88.3°. The results have basically validated TLS for deriving multiple structural parameters of stem, which help better grasp tree specialties.

Learning the shielding effect of tree crowns with various structures on ultraviolet-B (UV-B) transmission is of great significance, such as for reducing its damage on human. The cutting-edge remote sensing technique of mobile laser scanning (MLS) is a potential option for tree structure representation. This work was dedicated to investigating the correlation between the shielding efficiency of UV-B and tree crown structural parameters. Positive correlations were achieved between the shielding efficiency of UV-B and the canopy structural parameters, and this is of implications for selecting appropriate tree species for such as livable environment construction.

Airborne Light Detection and Ranging (LiDAR) is an active remote sensing technology which can acquire the topographic information efficiently. It can record the accurate 3D coordinates of the targets and also the signal intensity (the amplitude of backscattered echoes) which represents reflectance characteristics of targets. The intensity data has been used in land use classification, vegetation fractional cover and leaf area index (LAI) estimation. Apart from the reflectance characteristics of the targets, the intensity data can also be influenced by many other factors, such as flying height, incident angle, atmospheric attenuation, laser pulse power and laser beam width. It is therefore necessary to calibrate intensity values before further applications. In this study, we analyze the factors affecting LiDAR intensity based on radar range equation firstly, and then applying the intensity calibration method, which includes the sensor-to-target distance and incident angle, to the laser intensity data over the study area. Finally the raw LiDAR intensity and normalized intensity data are used for land use classification along with LiDAR elevation data respectively. The results show that the classification accuracy from the normalized intensity data is higher than that from raw LiDAR intensity data and also indicate that the calibration of LiDAR intensity data is necessary in the application of land use classification.

Aiming at spatial characteristics and echo information of the LiDAR point cloud data, design a regional segmentation and decision tree combined lidar point data classification method. First, based on the continuity of the LiDAR point cloud to finish the experiment area's region segmentation. Then, statistics each area boundaries and internal the number of dihedral angle cosine, to draw a line chart. Using the intersection's cosine of line chart , and region segmentation's minimum height as threshold to determine the ground point and the non-ground points. Finally, statistics separately all LiDAR point data set's dihedral angle, echo times, echo intensity, mean elevation, four constraint information to build a decision tree to determine which type of feature vesting each divided region. Using classification confusion matrix to assess the classification's accuracy, overall accuracy is higher than 94%. Experimental results show that this method can effectively separate roads, trees, buildings and terrain.

We report on a design strategy for a Tm,Ho:YLF laser transmitter capable of 125 mJ pulse energy at 30 Hz. Using the results of simulations and experiments, total efficiencies were compared for two different configurations. One is the oscillator operating at 193 K, and the other is the master oscillator and power amplifier operating at 233 K. In the latter case, an extensive cooling system is not required, while the laser efficiency becomes lower. Numerical simulations were performed by using a simple rate equation model. In order to validate the results of simulations, the laser experiments were made with a conductively cooled, side-pumped Tm,Ho:YLF laser in the temperature range of 195-228 K. Based on these results, an optimum configuration to achieve the 125-mJ pulse energy are discussed.

A scanning micro-pulse lidar (MPL) was developed by Institute of Oceanographic Instrumentation, Shandong Academy of Sciences, which can be used for routine observations of optical properties, temporal and spatial variation of atmospheric aerosol and cloud in the lower troposphere. In addition to the optical system design, the design of 3 dimensional (3-D) scanning system controlled by servo motors is analyzed, including servo motor selection and mechanical design. Through the measurements in Qingdao, it is proved that 3-D scanning system can control the lidar azimuth/elevation scanning with high precision. The lidar has good performance and can provide time-height indication (THI), range-height indication (RHI) and plane-position indication (PPI) of lidar signals which can well reflect the temporal and spatial variation of atmospheric aerosol.

Aerosol particles are important both because they affect atmospheric processes and, after deposition to the sea surface, because they affect processes in sea water. Aerosols have a strong impact on climate both due to scattering and absorption of incoming solar radiation (direct effect) and through their effects on cloud properties and associated cloud albedo (first indirect effect) and precipitation (second indirect effect). A shipborne multiwavelength Mie/Raman/Polarization aerosol lidar developed for marine aerosol is presented. The shipborne aerosol lidar (SAL) is able to measure aerosol backscatter and extinction coefficient as well as depolarization in the altitude range 0 to 20 km. The instrument is installed in a 2 m*2 m*2 m container. Preliminary results of investigation of marine aerosol properties on the basis of multiwavelength lidar onboard the Xiangyanghong Number 8 Research ship on the Yellow Sea and Jiaozhou Bay of China are presented.

There are nearly all kinds of typical earthquake types in Wenchuan earthquake relics. For the protection and efficient use of seismic data of relics, ground Lidar and UAV are used collected data about the ruined buildings, seismic scarps and other typical seismic information in Wenchuan, Beichuan, Bailu Middle School , Dujiangyan and Xiaoyudong earthquake relics. These data are processed and a high-precision surveying flow of typical earthquake relics is preliminarily formed.