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This PDF file contains the front matter associated with SPIE Proceedings Volume XXXX, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.
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We describe a new lidar system for CO2 that uses a Fabry-Perot based system as the detector portion of the
instrument and replaces the narrow band laser commonly used in lidars with the newly available
superluminescent light emitting diode (SLED) as the source. This approach reduces the number of
individual lasers used in the system from three or more to one-considerably reducing the risk of failure. It
also tremendously reduces the requirement for wavelength stability in the source putting this responsibility
on the Fabry-Perot.
&128;
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We report results on a single-end pumped waveguide laser for sensing applications Output power in excess of 20 mW
with 17% slope efficiency in robust single-frequency operation at 1533.5 nm is demonstrated. The overall laser cavity
laser was 60-mm long but the active medium, an Er:Yb-doped phosphate glass, was only 9-mm long. The waveguide
was fabricated by two-step Ag-Na ion-exchange technique. The overall cavity length including butt-coupled fiber-
Bragg-grating mirrors was <60 mm. We also reports on recent work to reach 100-mW single-frequency output power.
To extend the operation wavelength to 2-micron wavelength region we also developed new tellurite glasses. Preliminary
results on glass investigation are also reported.
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NASA Langley Research Center has been developing 2-micron lidar technologies over a decade for wind measurements,
utilizing coherent Doppler wind lidar technique and carbon dioxide measurements, utilizing Differential Absorption
Lidar (DIAL) technique. Significant advancements have been made towards developing state-of-the-art technologies
towards laser transmitters, detectors, and receiver systems. These efforts have led to the development of solid-state lasers
with high pulse energy, tunablility, wavelength-stability, and double-pulsed operation. This paper will present a review
of these technological developments along with examples of high resolution wind and high precision CO2 measurements
in the atmosphere. Plans for the development of compact high power lasers for applications in airborne and future space
platforms for wind and regional to global scale measurement of atmospheric CO2 will also be discussed.
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We present efficient CW lasing Tm3+/Ho3+/Yb3+-triply-doped tellurite fibre at ~2.1 μm. Two different pump schemes
have been demonstrated for this laser: a 1.088 μm
Yb3+-doped silica fibre laser simultaneously pumping the Tm3+: 3H5,
Ho3+: 5I6 and Yb3+: 2F5/2 levels, and a 1.6 μm
Er3+/Yb3+-doped silica fibre laser directly pumping the Tm3+: 3F4 level. For
the 1.6 μm pumping, a slope efficiency of 62% has been achieved in a 76 cm long fibre which is close to the Stokes
efficiency limit of ~75%. An output power of 160 mW has also been achieved, but with no signs of saturation or fibre
damage suggesting that higher output powers should be possible. For the 1.088 μm pumping there is very strong pump
ESA resulting in bright blue (480 nm) and near-IR (800 nm) fluorescence due to the 1G4 → 3H6 and 3H4 →
3H6
transitions of Tm3+, respectively, and this limits the achievable slope efficiency, which in this case was a maximum of
25% for a 17 cm long fibre. With this pump scheme, the highest observed output power was 60 mW, and further power
scaling was limited due to the intense ESA and thermal damage to the pump end of the fibre. We also present results on
the active Q-switching of the 1.6 μm pumped fibre laser using a mechanical chopper operating at 19.4 kHz. Average
powers of 26 mW and pulse energies of 0.65 μJ were measured with pulse widths in the range 100-160 ns.
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Lidar has in recent years matured into a reliable and versatile technology for remotely measuring wind speeds at all
heights across the rotor diameter. A laser beam is used to acquire the radial wind velocity in a number of directions at a
given height from the Doppler shift of the backscattered light. From this the wind velocity at that height can be derived.
Lidar allows wind flow model validation. Deployment of a Lidar to sites where different runs of modeling have
produced divergent results can help select which input parameter set is most useful for characterizing wind flow, by
taking measurements that allow differentiation between models. The cost of data acquisition for offshore wind resource
assessment can be reduced by adopting Lidar methods. Less stringent specifications are imposed for platform
installation, and approaches that dispense with the need for a platform are being developed. Operational turbine
performance monitoring can be helpfully augmented by using Lidar to obtain data describing the wind flow impinging
upon a turbine or in its wake. Lidar is also useful in obtaining details of wind shear, turbulence, vertical inflow and wind
veer at proposed and operational turbine locations. Some of the uses Lidar has been applied to, some of its limitations,
and the developing role Lidar will grow into in the future of wind resource assessment, are reviewed here.
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Active remote sensing using lidar appears to be very attractive for the measurement of atmospheric greenhouse gases
like carbon dioxide from spaceborne platforms. Feasibility studies are currently being performed to demonstrate the
required measurement performance. Due to the high precision required (less than 0.3 %) for climate studies, space-borne
IPDA (Integrating Path Differential Absorption) Lidar is preferred over the range resolving DIAL technique which uses
atmospheric backscatter. This is due to the larger Lidar echoes from hard target when using systems of comparable size.
Applying the IPDA Lidar method, magnitude and variability of the ground reflectance becomes an important issue in
terms of instrument sizing and pointing requirements of space-borne systems. Because of the stringent sensitivity
requirements, even small gradients of the ground reflectance could introduce noticeable retrieval errors in the CO2
column content, when the laser transmitter does not point on the same ground spot for the on- and off-line measurement.
However, the current knowledge on the variability of the ground reflectance both in the appropriate wavelength range
and on small spatial scales is insufficient for an accurate error assessment. In order to address these deficiencies, airborne
lidar measurements at 1.6 µm wavelength were performed. The wavelength range around 1.6 µm provides suitable
absorption lines for the measurement of carbon dioxide. A pulsed optical parametric oscillator (OPO) system (5 mJ at
1573 nm, 10 Hz pulse rate) was deployed on the DLR Cessna Caravan aircraft to measure the variations of the ground
return. In order to simulate a satellite system, statistical analyses on the data including upscaling to a larger ground spot
size of a space-borne system and different averaging ranges are being performed. The focus of this study is on the
investigation of the characteristics of typical surface types including the open sea.
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The Planetary Science Division (PSD) within NASA Headquarters' Science Mission Directorate (SMD) has several
Research & Analysis (R&A) programs that support the definition and development of instrumentation for science
investigations of all bodies in the solar system. These programs are part of the Research Opportunities in Space and
Earth Sciences (ROSES) - 2008 and can be found at http://nspires.nasaprs.com
com. Science instrumentation of interest to
the Planetary Science Division includes remote sensors as well as in situ sensors and laser-based instruments are well
suited for both scenarios. The programs that support hardware development include the Planetary Instrument Definition
& Development Program (PIDDP), the Astrobiology Science & Technology Instrument Development (ASTID) program,
the Astrobiology Science & Technology for exploring Planets (ASTEP) program, and the Mars Technology Project/Mars
Instrument Development Program (MIDP). PIDDP has been expanding over the last two years to cover advanced
instrument development with Technology Readiness Levels up to TRL 6. Beyond these R&A elements, a new
Announcement of Opportunity (AO) for Stand Alone Missions of Opportunity Notice (SALMON) will provide
resources to further develop science instrumentation for flights of opportunity aboard non-NASA missions.
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The CALIPSO Level II data are analyzed to assess the veracity of the CALIPSO aerosol type identification algorithm and generate distributions of aerosol types and their respective optical
characteristics. The distributions show that the classification algorithm has no surface type or diurnal dependencies. For this initial assessment of algorithm performance, we analyze global distributions of the CALIPSO aerosol types, along with distributions of integrated attenuated backscatter, backscatter color ratio, and volume depolarization ratio for each type. The aerosol type distributions are further partitioned according to various geophysical discriminators (e.g., geographic region, land
vs. ocean, and day vs. night). The algorithm generates the expected results in most scenes. The total color ratio distributions show significant overlap between the aerosol types. Since the aerosol typing algorithm uses a logical decision tree based on fixed thresholds, we test the sensitivity of the typing algorithm to perturbations in these threshold values. To test the CALIPSO extinction to backscatter ratio estimates, we compare
extinction-to-backscatter ratios derived using the transmittance method
to the values in the look up tables.
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The height of cloud and aerosol layers in the atmosphere is believed to affect climate change and air pollution because
both of them have important direct effects on the radiation balance of the earth. In this paper, we study the ability of
Cloud Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) data to detect, locate and distinguish
between cloud and aerosol layers in the atmosphere over Peninsula Malaysia. We also used image processing technique
to differentiate between cloud and aerosol layers from the CALIPSO images. The cloud and aerosol layers mostly are
seen at troposphere (>10 km) and lower stratosphere (>15km). The results shows that CALIPSO can be used to
determine cloud and aerosol layers and image processing technique has successfully distinguished them in the
atmosphere.
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CALIPSO is a satellite mission designed to measure the vertical structure and optical properties of aerosol and clouds
over the globe. The Science Team for the mission has organized an international program, named quid pro quo (QPQ), to
obtain correlative measurements to support validation of its retrieved products. EARLINET, a network of 25 European
lidar stations, joined the QPQ program and have been performing correlative measurements at all stations within 80 km
from the overpasses ("mandatory" measurements) and additionally at the lidar station which is closest to the actually
overpassed site ("suggested" measurements). In this work, we present the results obtained during the primary validation
phase for the #21 EARLINET station (CIEMAT-Madrid) correlative measurements. Two different data products have
been compared: The "Total Backscatter_Coefficient_532" from level 2 files (released on Jan/2008) and the version 2
(released on Dec/2007) Level 1 data product called "Total_Attenuated_Backscatter_532", that must be compared with a
simulated lidar profile calculated from the 532-nm extinction and backscattering coefficients profiles independently
measured by the unpolarized elastic channel and Raman channel of the ground system. Several cases with a reasonable
agreement in terms of backscattering coefficient magnitude have been found (7 cases, 26% of the total cases analyzed:
27 cases), while cases with bad agreement amounts to 38%. The rest correspond to cases with clouds (18%) and bad
assignment of aerosol layer as clouds (18%).
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LIDAR backscatter signal analysis can establish surface elevation at the LIDAR footprint, in kilometers above local
mean sea level. Since aberrations in the signal caused by a non-ideal transient response in the 532 nm detectors, the
geometric thickness associated with the LIDAR surface elevation can be utmost misleading. In this place, the provisional
LIDAR surface elevation should treated all signal beneath the reported LIDAR surface elevation top as being pure
instrument artifact introduced by the non-ideal transient response of the detectors. Apparently, no geophysical
significance should be ascribed to the subsurface portion of the LIDAR return. This study will present the comparison
between the LIDAR Surface Elevation and Digital Elevation Map (DEM) using CALIPSO LIDAR data over Peninsular
Malaysia.
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An algorithm using N-way analysis for the detection of multiple clouds in multi-wavelength lidar data is presented. Nway
analysis is a tool for algebraic manipulation of N-dimensional (ND) data arrays, and it allows for spatial (range),
temporal (time), and spectral (wavelength) information to be extracted simultaneously from 3D lidar data. The algorithm
tracks the spectral signal strength and location of each of the multiple clouds through time within the lidar measurements
via a method that is shown to be similar to multivariate anomaly detection. The method is data driven and can be applied
to arrays of any number of dimensions (e.g., polarization as the 4th dimension). Results of the algorithm for CO2 lidar
simulations of aerosol clouds are shown and discussed.
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Lidar investigation of temporal and vertical optical atmospheric properties will play a key role in the future for a
continuous monitoring over the whole planet through world ground based networks. The EZ LidarTM, manufactured by
LEOSPHERE, has been validated in several campaigns as that one in Southern Great Plains (ARM) or at Goddard Space
Flight Center (NASA). An EZ LIDARTM with
cross-polarization capabilities was deployed in Kanpur, India in the frame
of TIGER-Z campaign organized by NASA/AERONET in order to measure aerosol microphysical and optical properties
in the Gange basin. In addition, 12 sun-photometers were deployed during this campaign and CALIPSO (The
Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) data were also acquired. In this work we present the results
in retrieving aerosol extinction and backscattering from EZ
LidarTM measurements, and the validation of the space borne
instrument CALIPSO under the satellite track.
EZ LidarTM is also coupled with the photometers to provide the
measurements of the Aerosol Optical Depth over the selected region.
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In this paper, a scheme of a subpicosecond dispersion range-finder is proposed and an estimate of the precision of rangefinding
for large distances in open atmosphere using this device is performed. Using subpicosecond pulses allows us not
only to improve range-finding precision, but also to eliminate the effect of air refractive index indeterminacy on the path
of propagation quite effectively.
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A number of vector and volume averaging considerations arise in relation to remote sensing, and in particular, Lidar. 1)
Remote sensing devices obtain vector averages. These values are often compared to the scalar averages associated with
cup anemometry. The magnitude of a vector average is less than or equal to the scalar average obtained over the same
period. The use of Lidars in wind power applications has entailed the estimation of scalar averages by vector averages
and vice versa. The relationship between the two kinds of average must therefore be understood. It is found that the ratio
of the averages depends upon wind direction variability according to a Bessel function of the standard deviation of the
wind direction during the averaging interval. 2) The finite probe length of remote sensing devices also incurs a volume
averaging bias when wind shear is non-linear. The sensitivity of the devices to signals from a range of heights produces
volume averages which will be representative of wind speeds at heights within that range. One can distinguish between
the effective or apparent height the measured wind speeds represent as a result of volume averaging bias, and the
configuration height at which the device has been set to measure wind speeds. If the wind shear is described by a
logarithmic wind profile the apparent height is found to depend mainly on simple geometrical arguments concerning
configuration height and probe length and is largely independent of the degree of wind shear. 3) The restriction of the
locus of points at which radial velocity measurements are made to the circumference of a horizontally oriented disc at a
particular height is seen to introduce ambiguity into results when dealing with wind vector fields which are not
irrotational.
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During the Dry Season (July-September) of 2007 aerosol profiling campaign was carried with an aerosol backscattering
LIDAR system in Sao Paulo, Brazil. The main goal of this campaign was to observe the aerosol load in
the lower troposphere (up to 10 km) and its daily behavior in order to check for air dispersion conditions, planetary
boundary and mixed layer daily evolution, mid and long range transport. For the latter we used air mass
trajectory analysis and satellite data. With the LIDAR analysis we can provide the aerosol optical properties in
the visible range (532 nm) and quantities such as aerosol backscattering and extinction coefficients. Altogether
we could measure during 60 days, since when there was the presence of precipitation no measurement was conducted.
Collocated with the LIDAR was a AERONET Sunphotometer which help in characterizing the aerosol
optical properties. Our data was correlated with the Environmental Air using Optical Sensors in the Remote
Air Quality Assessment and cross-correlations were made with Aerosol Optical Thickness, Planetary Boundary
Layer evolution and Air Quality Index.
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In this paper, the properties of Low-level clouds are explored with a Raman-elastic lidar. In particular, we examine two
complementary methods to measure thin cloud optical depth (COD). The first is direct integration of Raman Derived
extinction while the second method utilizes a regression technique. We show that if we correct for aerosol influences the
regression method for low cloud optical depth can be dramatically improved. Furthermore, estimates of extinction to
backscatter ratio can be made within the cloud. We find that when the lidar ratio in cloud is averaged over the vertical
extent, an S ratio on the order of 20 sr is found which is consistent with conventional water phase cloud droplet models.
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Following article presents LIDAR for stand off detection of aerosols which was constructed in Institute of
Optoelectronics in Military University of Technology. LIDAR is a DISC type system (DIfferential SCattering) and is
based on analysis of backscattering signal for two wavelengths (λ1 = 1064 nm and λ2 = 532
nm) - the first and the
second harmonic of Nd:YAG laser. Optical receiving system is consisted of aspherical mirror lens, two additional
mirrors and a system of interference filters. In detection system of LIDAR a silicon avalanche photodiode and two
different amplifiers were used. Whole system is mounted on a specialized platform designed for possibility of LIDAR
scanning movements. LIDAR is computer controlled. The compiled software enables regulation of the scanning platform
work, gain control, and control of data processing and acquisition system. In the article main functional elements of
LIDAR are shown and typical parameters of system work and construction are presented. One presented also first results
of research with use of LIDAR. The aim of research was to detect and characterize scattering aerosol, both natural and
anthropogenic one. For analyses of natural aerosols, cumulus cloud was used. For analyses of anthropogenic aerosols one
used three various pyrotechnic mixtures (DM11, M2, M16) which generate smoke of different parameters. All scattering
centers were firstly well described and theoretical analyses were conducted. Results of LIDAR research were compared
with theoretical analyses and general conclusions concerning correctness of LIDAR work and its application were
drawn.
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Petrochemical and oil refining facilities play an increasingly important role in the industrial context. The corresponding
need for monitoring emissions from these facilities as well as in their neighborhood has raised in importance, leading to
the present tendency of creating real time data acquisition and analysis systems. The use of LIDAR-based techniques,
both for air quality and emissions monitoring purposes is currently being developed for the area of Cubatao, Sao Paulo,
one of the largest petrochemical and industrial sites in Brazil. In a partnership with the University of São Paulo (USP)
the Brazilian oil company PETROBRAS has implemented an Environmental Research Center - CEPEMA - located in
the industrial site, in which the development of fieldwork will be carried out. The current joint R&D project focuses on
the development of a real time acquisition system, together with automated multicomponent chemical analysis.
Additionally, fugitive emissions from oil processing and storage sites will be measured, together with the main
greenhouse gases (CO2, CH4), and aerosols. Our first effort is to assess the potential chemical species coming out of an
oil refinery site and to verify which LIDAR technique, DIAL, Raman, fluorescence would be most efficient in detecting
and quantifying the specific atmospheric emissions.
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