Current uncertainties in the effects of aerosols and clouds on the Earth radiation budget limit our understanding of the climate system and the potential for global climate change. The CALIPSO satellite will use an active lidar together with passive instruments to provide vertical profiles of aerosols and clouds and their properties which will help address these uncertainties. CALIPSO will fly in formation with the EOS Aqua and CloudSat satellites and the other satellites of the Aqua constellation. The acquisition of simultaneous and coincident observations will allow numerous synergies to be realized by combining CALIPSO observations with complementary observations from other platforms. In particu-lar, cloud observations from the CALIPSO lidar and the CloudSat radar will be complementary, together encompassing the variety of clouds found in the atmosphere, from thin cirrus to deep convective clouds. CALIPSO is being developed within the framework of a collaboration between NASA and CNES and is scheduled for launch in 2004.

The extinction-to-backscatter ratio, S1, is a crucial parameter for quantitative interpretation of lidar data. A new method will be presented for obtaining aerosol extinction-backscatter-ratio S in the aerosol layer near the ground by using OPC, visibility-meter and particle-monitors. According to the measured data in Beijing during two periods of August of 2001 and January of 2002, the variation of S will be discussed.

An eye-safe, mobile micro-pulse Mie Lidar system has recently been integrated. The system is capable of taking slant angle 360 degree horizontal scans of aerosol distributions, as well as vertical boundary-layer profiles in a zenith pointing position. The Lidar is co-axial, and the transmitter is a high repetition rate, diode-pumped micro-joule pulse energy, Nd:YAG 532 nm laser. The receiver is a compact Schmidt-Cassegrain f/6.3 telescope. The whole system can be fitted into a small van for field observations. The main objective in building this Lidar in Hong Kong is for monitoring spatially varying aerosols and vertical distributions within the lower few km of the troposphere. In this paper, the near range corrections from geometric ray tracing are presented together with field data. Representative spatial scans over urban Hong Kong are also given. The new system will be deployed in the very near future to study the correlation between the spatial distribution of aerosols and local traffic conditions. The Lidar design may represent a typical commercial product of the current technology.

The indirect effect of aerosols in the atmospheric radiation process, which is the effect of aerosols through the formation of clouds, is one of the most uncertain factors in the current climate models for predicting global warming. To study the effect of aerosols on cloud formation quantitatively, a method for measuring cloud particle size is indispensable. A bistatic lidar method was developed for measuring water cloud particle size at the cloud base. The method is based on single scattering Mie theory. A simple measurement system that consists of a single-wavelength laser and dual-polarization bistatic receivers was developed. Experiments were conducted using the 532 nm beam of the Mie scattering lidar on board the research vessel Mirai. An additional bistatic receiver having polarization analyzers was located at a suitable scattering angle. Cloud particle size (mode radius of the assumed size distribution) was derived from the ratio of the polarization components of the scattered light based on the single scattering Mie theory. Particle size of maritime cumulus and stratus near the cloud base was measured. The particle size profiles in the clouds up to a penetration depth of about 50 m were observed with the method. At a larger penetration depth, effect of multiple scattering dominated the return signals.

Asian-dust and Cirrus cloud have been measured by Multi-Wavelength aerosol lidar since 2000 and Automatic Controlled Aerosol lidar since 2002 at Suwon (127°E 37°N),Korea. These Lidars are Mie scattering scheme that use 355/532/1064 nm and 532 nm respectively. The vertical profiles of range corrected backscatter intensity and depolarization ratio on 16 days of Asian dust in springtime of 2002 are analyzed for this report. In Suwon, the Asiandust mainly showed at lower troposphere below 3 km but several cases showed in free troposphere of over 4 km. The peak depolarization ratios are in the range of 20-40%. The thickness of dust layer is about 2-2.5 km in case of lower tropospheric measurements. After event ofAsian dust the cirrus clouds are often measured in resemblance to Asian dust at upper troposphere. The maximum upper altitudes are about 8 to 12 km. The clouds falling down to about 3 km were measured which is a higher depolarization ratio of 10-30 %.

In this paper, two inversion algorithms considering multiple scattering are proposed to retrieve aerosol/cloud extinction coefficient profiles from LITE data, which are called as the Iterative Forward Integration Algorithm (IFIA) and the Iterative Forward-Backward Integration Algorithm (IFBIA). In IFIA, at first assuming no multiple scattering, retrieve the extinction coefficient profile by the forward integration algorithm. Then, using the profile and assuming an aerosol/ cloud phase scattering function, calculate the multiple scattering component by a parameterized multiple scatter lidar equation (or Monte Carlo calculation) and then yield new extinction coefficient profile solution. By using IRA and IFBIA, some typical LITE data are selected to derive aerosol/cloud extinction coefficient profiles. As shown in the inversion results, if the multiple scattering is neglected, there may be a very large uncertainty in the retrieved aerosol/cloud extinction coefficient profile, especially for the shorter-wavelength 355nm channel and the case of cloud layer. The present algorithms considering multiple scattering can produce more reasonable aerosol/cloud extinction coefficient retrievals.

Three lidar systems are developed in Institute of Atmospheric Physics. A four-wavelength lidar is used to detect ozone, aerosol and clouds, which contains a XeCl excimer laser with output energy of about 120mJ at 308nm, a Nd:YAG laser with three operating wavelengths of 355nm, 532nm and 1064nm, and a 1m-receiver telescope. A two-wavelength mobile lidar system is used to detect aerosol in troposphere and Asian dust storm, which has a Nd:YAG laser with wavelengths of 532 and 1064nm. A 1064nm Nd:YAG lidar is used to monitor city aerosol pollution. Since January 2000 the lidar systems have been used in measuring dust storm, high cloud and ground-35km aerosol extinction coefficient profiles. Measurement results show that the aerosol optical depth between 6km and 11km has a mean value of 0.0192; the cloud optical depth between 6km and 11km ranges from 0.014 to 0.23. The aerosol extinction near above the ground changes very greatly. From measurements, the change characteristics of aerosol extinction through snow and rain course, and dust storm are analyzed. Routine city aerosol pollution monitoring result is presented. The results of measurements of ozone shows that during September-October, the maximum ozone concentration is usually in the height range from 25km to 29km, and there is usually second concentration peak in the range between 10km and 17km. The compares of lidar-detected ozone profile made during 20:40-21:35 of October 16, 2001 with balloon measurement during 15:00-16:00 of same day is given.

We present the results of our multi-wavelength scanning lidar investigations of time dependent 3-D marine aerosol fields as a function of meteorological parameters at a coastal site in Hawaii. We describe our measurements of salt-aerosol plumes generated at a reef >1.3 km from the lidar and their effect on the aerosol extinction coefficient. At typical trade wind speeds of ~7 m/s, plumes of salt spray have been observed to rise to heights of about 50 m above the reef. A time sequence of vertical scans at three wavelengths (355, 532, 1064 nm) was taken under light (1.9 m/s) wind conditions over the same reef. Large salt plumes more than 600 m high were found to develop under these conditions. The much greater height of light-wind plumes suggests that they are being dispersed less rapidly, allowing them to rise to greater heights because of the presence of thermals. Earlier data collected at Bellows showed reef plumes rising to 120 m in winds of 5 m/s, indicating a consistent trend of increasing plume height with decreasing wind speed.

Raman lidar techniques provide vertical profiles of the key parameters needed for better understanding of meteorological and air pollution processes. The time sequence of atmospheric profiles is most valuable for understanding meteorological processes and describing the evolution of episodes and exposure associated with air pollution. The vibrational and rotational Raman lidar signals provide simultaneous profiles of ozone and airborne particulate matter, as well as several meteorological properties. The first operational prototype Raman lidar, Lidar Atmospheric Profile Sensor (LAPS), makes use of 2nd and 4th harmonic generated beams of a Nd:YAG laser to provide both daytime and nighttime measurements. The Raman scatter signals from vibrational states of water vapor and nitrogen provide robust profiles of the specific humidity in the lower atmosphere. The temperature profiles are measured using the ratio of rotational Raman signals at 530 and 528 nm from the 532 nm beam of the Nd:YAG laser. Optical extinction profiles can be determined from the measured gradients in each of several molecular species profiles by comparing with the molecular scale height. Wavelengths at 284 nm, 530 nm and 607 nm have been used routinely to determine profiles of optical extinction. The ozone profiles in the lower troposphere are measured using a DIAL analysis of the ratio of the vibrational Raman signals for nitrogen (284 nm) and oxygen (278 nm), which are on the steep side of the Hartley band of ozone. Examples from several measurement campaigns are used to demonstrate the utility of Raman lidar for describing the evolution of air pollution events. The examples presented have been selected to show the new level of understanding of air pollution events and meteorological processes that is gained from applications of lidar techniques.

A lidar system capable of simultaneous measurement of Raman and Mie-Rayleigh scattering was constructed, and used for measurement of 03, water vapor, and aerosols in the lower troposphere. 03 concentration measurement was performed by differential absorption of N2 and 02 Raman scattering signals with the lidar transmitter operating at 280.0 nm, and also by differential absorption of Mie-Rayleigh scattering and of N2 Raman scattering with the transmitter operating at 279.5 nm and 280.5 nm on alternate pWses. Water vapor profiles were obtained as the mix ing ratio relative to N2 using the N2 and H20 Raman scattering signals with the lidar transmitter operating at 280.0 nm. Simultaneous measurement of H20 Raman scattering and Mie scattering over a continuous period of about 13 hours showed that the lidar system can identify uncondensed water vapor and condensed water vapor by comparison of temporal and spatial variations of the water vapor mixing ratio and of the Mie backscattering coefficient.

The optical fiber Raman temperature (OFRT) Lidar is a real time, on line and multi-point temperature measurement system. 30k spot temperature information on space field can be measured and located the position by 30km OFRT Lidar It is a new technology integration of optical-mechanic-electric and computer. The system can take real time, on line measurement of spatial temperature field. In the system, optical fibers are both transmission media and sensing media. The intensity of anti-stokes Raman backscattering of optical fiber is modulated by the spatial temperature field where the optical fiber is laid. After signal processing and demodulation, the information of temperature can be extracted from the noise and can be displayed in real time. In time domain, using the velocity of light wave in optical fiber, the time interval ofback-direction light wave and optical fiber OTDR technology The amplification of anti-stokes Rairan spontaneous scattering (ARS) and the temperature effect have been first observed and applied to OFRT Lidar. The performance of OFRT Lidar is following: fiber length : 25.2km; temperature measuring range: O-lOOC(can be expand) temperature uncertainty: 2 C : temperature resolution: 0. 1 ; spatial resolution: Sm: measurement time: 5mm; Main unit operation temperature range: O—40t .The optical fiber sensor probes and the software for signal processing are also discussed. Keywords: Optical Fiber Raman Temperature (OFRT) Lidar, Optic Time Domain Reflection (OTDR),distributed optical fiber Raman photons temperature sensors, the temperature effect of Raman backscattering, Rayleigh backscattering, ZX band backscattering spectrum, optical fiber sensor probe.

Measurement parameters of the RASC Raman lidar are temperature (in the troposphere and stratosphere measured with rotational Raman (RR) technique, in the stratosphere and mesosphere with integration technique), particle extinction coefficient, particle backscatter coefficient, and water vapor mixing ratio (all measured with Raman lidar technique). Recently, we implemented new interference filters, new data acquisition electronics and - for simultaneous temperature measurements with integration technique - a chopper. With the first two upgrades, the measurement resolution for tropospheric measurements could be improved significantly. Now the 1-sigma statistical uncertainty of the rotational Raman temperature measurements is below 1 K up to about 16 km altitude for, e.g., 7 minutes integration time and a gliding average of 360 m of the data. In this contribution, we discuss the recent technical upgrades and illustrate the performance of the new system with measurement examples.

Raman lidar techniques have been used in remote sensing to measure the aerosol optical extinction in the lower atmosphere, as well as water vapor, temperature and ozone profiles. Knowledge of aerosol optical properties assumes special importance in the wake of studies strongly correlating airborne particulate matter with adverse health effects. Optical extinction depends upon the concentration, composition, and size distribution of the particulate matter. Optical extinction from lidar returns provide information on particle size and density. The influence of relative humidity upon the growth and size of aerosols, particularly the sulfate aerosols along the northeast US region, has been investigated using a Raman lidar during several field measurement campaigns. A particle size distribution model is being developed and verified based on the experimental results. Optical extinction measurements from lidar in the NARSTO-NE-OPS program in Philadelphia PA, during summer of 1999 and 2001, have been analyzed and compared with other measurements such as PM sampling and particle size measurements.

Design and laboratory characterization of a highly efficient all solid state 200 mJ UV light source for ozone dial measurements We are carrying out initial laboratory tests of an all solid state UV source designed to generate 200 mJ pulses of 320 nm light based on sum-frequency mixing of the 532 nm second harmonic of an Nd:YAG pump laser with 803 nm light derived from a nanosecond optical parametric oscillator. The sum-frequency stage was designed to obtain mixing efficiency approaching 60% by carefully matching the spatial and temporal properties of the 532 nm and 803 nm pulses. The nearly equal balance of 532 nm to 803 nm photons required an injection-seeded Nd:YAG pump laser and an OPO exhibiting exceptional signal beam quality and unusually high conversion efficiency. The OPO was designed to meet these requirements by employing a high Fresnel-number image-rotating nonplanar ring cavity producing signal beams with M-squared of approximately 3 that was pulsed self-injection seeded with the goal of obtaining greater than 75% conversion of pump energy into the signal and idler. This design can easily be modified to produce other UV wavelengths in the range of 300 nm to 320 nm.

The earth's environment is constantly changing. Scientific evidence indicates that these changes are result of a complex interplay among a number of natural and human related systems. Therefore in recent times, concern has grown about global change studies - which is related to natural and anthropogenic alteration of the Earth's environment. The atmospheric trace gases play an important role in many processes such as biosphere-troposphere interaction, the chemistry of troposphere and the troposphere - stratosphere exchange. Therefore measurement of various minor constituents in the atmosphere is of great significance to understand physics, Chemistry and dynamics of the atmosphere. A Differential Absorption Lidar (DIAL) system using a tunable CO2 laser has been designed and developed at National Physical Laboratory, New Delhi, to monitor various minor constituents in the atmosphere. The system is being used to monitor water vapour, surface ozone, ammonia and ethylene concentration. Some times these trace species were found to be quite high which is a health hazard. Some measurements have also been made to estimate the liquid water contents of the fog by the measurement of CO2 laser transmission at 9.5 μm. The liquid water content was found to be in the range 0.008 - 0.2 gm/m3 depending on the density of fog. In the present communication salient features of experimental set up and results obtained will be presented in detail.

We performed SO2, NO2, and 03 measurements in the lower troposphere using a multiwavelength differential absorption lidar (MDIAL) system. Measurement results are compared with results of airborne and ground-based in-situ measurements performed simultaneously with lidar measurement. Vertical concentration variation of SO2 with 0-7 ppb for 1000-1700 m altitude was measured by dual-DIAL, and those ofNO2 and 03 with 0-50 ppb for 700-2000 m altitude were measured by 2-wavelength DIAL quasi-simultaneously. Measurement results suggest that NO2 was trapped below the inversion layer, which induced the reduction of 03 concentration by the reaction with NOR. Comparison of results obtained by DIAL and by in-situ methods showed that the MDIAL system had sufficient accuracy for verification of long-range transport models of sulfur compounds and for observation of chemical reactions of oxidants and nitrogen oxides. We also performed simultaneous profiling of NO2 and 03 in the lower troposphere using a stable, high power transmitter for NO2 measurement. Concentration variations ofNO2 and 03 for 900-1350 m altitude were measured for a continuous time interval of 24 hours without maintenance.

Development of a mid-infrared differential absorption LIDAR system around 2.0 and 2.3 tm wavelength is proposed for remote sensing of greenhouse-effect gases, such as CO2 and CH. A model calculation shows that the 1.6 to 2 ptm wavelength region is also suitable for the CO2 measurements. A widely tunable self—injection seeded Ti3: sapphire laser in combination with a Raman shifter is used for a tunable mid-infrared laser source. This combination could allow a wide tuning range between 1.6 and 2.3 .tm. The spectral width of the Ti3: sapphire laser was measured around 0.04 cnf 1 and stability of the laser source was also studied by a Fabry-Perot interferometer in order to determine theaccuracy of the DIAL measurement. Currently, output energy is limited to only a few mJ limiting the detection sensitivity. Nevertheless improved output characteristics should meet the requirements satisfactorily to monitor CO2 and CH gases in the atmosphere.

A differential absorption mobile lidar system for pollution monitoring for daytime and nighttime operation is described. It allows 3Dmeasurements by using a steering unit, and can measure four kinds of pollutants in atmosphere, Aerosol, so2, NO2, and 03. The lower detection limit ofthe SO2, NO2, 03, is a few ppb. The max. measurement range is about 3 —5 km. This system was developed at the Anhui Institute of Optics and Fine Mechanics, the Academy of Sciences of China. A few examples ofmeasured 03, SO2 , NO2, and aerosols distributions are presented. Keywords: Mobile lidar, differential absorption lidar, aerosols, 502, NO2, 03.

The findings of an independent panel commissioned by NASA’s Earth Science Enterprise (ESE) to assess the current missions utilizing advanced solid-state lasers and the programmatic actions by the Enterprise to define how NASA Centers will cooperate on future lidar competitive opportunities together formulate a strategy for technology development of advanced solid-state laser systems. In this paper we will describe a program created to address risks in the development of laser transmitter technologies. This program grew out of concern that there are no lasers as active sources for space-based remote sensing that have been space qualified for long-term science measurements. Presently, the risks inherent in developing these technologies have been born by programs funded to produce scientific results. The intention of this program is to mitigate risks in certain technical areas so that other technology programs can further the maturation of the instruments prior to infusion into a science program. The program will invest in several critical areas: • Advancing transmitter technologies to enable science measurements (tropospheric ozone, water vapor, winds, altimetry) • Development and qualification of space-based laser diode arrays • Advancing nonlinear wavelength conversion technology for space-based lidars

Lasers operating around 2.0 jm have several remote sensing applications including wind velocity, water vapor and green house gasses. An attractive approach to 2.0 m lasers has a Tm:glass fiber laser pumping a Ho:YAG laser, thereby avoiding problems that are associated with the Ho:Tm up conversion process. Toward this end, both Tm:silica and Tm:ZBLAN fiber lasers are evaluated as well as a Tm laser pumped Ho:YAG. Performance of these devices is reported.

We are developing a high energy, narrow linewidth, and tunable mid-IR laser source that can be used to measure the green house gases and toxic gases with sufficient sensitivity and accuracy. This system consists of three major components; a high energy seeded 2.05-micron pump laser, a parametric oscillator and amplifier tunable between 3 to 9 microns and a continuous wave Periodically Poled Lithium Niobate (PPLN) seed source for parametric oscillator. A high-energy 2.05-micron pump laser with 600-mJ output has been demonstrated. This laser is comprised of one oscillator and two amplifiers. It is operated in a double pulse format to increase the system efficiency. The high beam quality combined with the narrow linewidth feature makes it a superior pump source for the parametric oscillator and amplifier. A seed source for the parametric oscillator can be implemented by using a PPLN continuous wave Optical Parametric Oscillator (OPO). The efficiency of this PPLN OPO can be greatly increased because of the huge nonlinearly associated with the d33 element of the nonlinear tensor of this material and the non-critical phase matching. Recent significant material growth improvement of ZnGeP2 makes it possible to produce the crystal with sufficient low absorption at the 2.05 pump wavelength (<0.1cm-1). This crystal also has the characteristics of wide transparency range and large second-order nonlinearities. Such a crystal is one of the most promising nonlinear optical materials for efficient frequency conversion into the mid-IR spectral region. In this paper, the design and preliminary results of this laser system will be presented.

We report on several developments in solid state lasers and nonlinear optics specifically for applications in remote sensing. In the area of UV sources for ozone monitoring, we have developed an efficient, third-harmonic, tunable Ti:sapphire-laser-based source. For long-range, eyesafe detection of aerosols, we report a high-energy optical parametric oscillator (OPO) driven by a flashlamp-pumped, Q-switched Nd:YLF laser. Finally, for mid-infrared DIAL, we have developed a Tandem-OPO that converts a common Nd-doped laser into a tunable source capable of providing wavelengths in the range 1500-5500 nm and 8000-12000 nm.

Two-micron lasers can be used in a variety of remote sensing and medical applications. In recent years, such lasers have been used for remote sensing of wind and CO2 to expand our understanding of the global weather system. The detection of clear air turbulence and wake vortex from aircraft has been proven to enhance air travel safety. In this paper, we present the design and performance of a high-energy diode pumped solid-state 2-micron laser transmitter. There has been a large body of work on 2 μm laser crystals using Tm and Ho ions doped in YLF and YAG hosts, but the use of LuLiF4 as a host is relatively recent. Studies comparing Ho:LuLiF4 and Ho:YLF show that both crystals have similar emission cross-sections for both 2.05 μm and 2.06 μm transitions. Tm:Ho:LuLiF4 has proven to produce 15%-20% more energy than Tm:Ho:YLF. This is primarily attributed to the variation of the thermal population distribution in the Ho: 5I7 and 5I8 energy levels. The laser crystal used for this experiment is grown in the crystalline a-axis. The resonator is a bow tie ring configuration with 3-m length. One of the mirrors in the resonator has a 3.5m curvature, which sets up a 1.8 mm TEMoo mode radius. The output mirror reflectivity is 72% and it is the dominant source of the resonator loss. An acousto-optic Q-Switch with Brewster angle switches the Q of the oscillator and defines the polarization of the laser output. This laser has a potential to produce a multi joule energy and replace the traditionally used Ho: Tm: YLF crystal.

With the goal of obtaining high energy at 946 nm, we have built and characterized a power amplifier that will be used in conjunction with our Three Module Oscillator and PreAmplifier to further increase the available laser energy. Previously we obtained >75 mJ Q-switched energy in TEM00 mode at 946 nm in an all solid state diode pumped system using Nd:YAG.1 This transition is extremely useful to the remote sensing community, considering the presence of strong atmospheric water vapor absorption lines in this region. In order to obtain the higher energies that are necessary for such measurements, we have built a power amplifier. Gain was measured for varying input probe energies and the experimental results compared well with model predictions.

Accurate global atmospheric remote sensing such as wind and carbon-oxide concentration profiling requires a coherent Doppler lidar and a Differential Absorption Lidar (DIAL) in an eye-safe spectrum range, respectively. Both Doppler lidar and DIAL should have laser transmitters with high pulse energy and high efficiency. There is no doubt that a Tm:Ho:YLF or Tm:Ho:LuLF laser oscillator with multistage amplifiers are appropriate candidates for these transmitters, especially for space-borne lidar systems. To achieve a high efficient laser transmitter, a collinear double-pass Tm:Ho:YLF laser amplifier has been designed and experimentally tested with a Tm:Ho:YLF laser oscillator. When laser pulses at a reasonably high energy, said 50 mJ here, from a Q-switched Tm:Ho:YLF laser oscillator were directly sent into a single-pass Tm:Ho:YLF amplifier, a gain of 1.86 was obtained at a pump pulse energy of 5.82 J. With a collinear double-pass configuration, a gain of 2.24 was achieved at same pump pulse energy level including all losses of the necessary optical elements, such as a thin film polarizer, a half-wave plate, and a Faraday rotator. More than 95% pulse energy was extracted from the double-pass amplifier, compared to a single-pass amplifier.

Global climate change resulting from greenhouse gas increase has extended into the middle and upper atmosphere. Modelling studies show that the effects are more significant at high latitudes. Thus, the observations at the poles may provide some of the first conclusive evidence of global changes in the middle and upper atmosphere, and also provide a convenient mean of calibrating general circulation models. However, the middle and upper atmosphere region is difficult to study. To help address the measurement needs, we developed a new robust lidar system using an Fe Boltzmann technique. The new lidar utilizes mesospheric iron as a fluorescence tracer and relies on the temperature dependence of the population difference of two closely spaced Fe transitions. We deployed this new lidar to the North and South Poles from 1999 through 2001 to measure the temperatures and polar mesospheric clouds in the middle and upper atmosphere for both day and nighttime. Important scientific results and issues have emerged from our observations at the poles, especially on the polar mesospheric clouds (PMC) and temperatures. Significant hemispheric differences in PMC altitudes were found during our pole-to-pole measurements. Interpretation of these results has led to a new insight into the solar radiative forcing on the Earth atmosphere and a baseline for calibrating the atmospheric general circulation models. We review the pole-to-pole observations and results in this paper.

The University of Illinois Na wind/temperature lidar data collected at the Starfire Optical Range (SOR: 35N, 106.5W), NM, can be used to extract the dominant monochromatic inertial gravity waves and to characterize their features. By using simultaneously measured horizontal wind and temperature profiles the vertical wavelengths, intrinsic periods, and propagation directions can be determined using the hodograph method. A total of 700 waves were analyzed from about 300 h of observations. Waves with vertical wavelengths between 2 and 20 km and intrinsic periods between 1 and 20 h were fully characterized. 84.4% of the waves were propagating upwards. There was a prevailing direction towards the northeast in upward waves horizontal propagations over the year. This prevailing direction existed also in spring, summer and autumn. In winter, most waves propagated to the south and west. The filter theory of gravity waves propagating through the middle atmosphere can be used to give an explanation on the observations. Propagation directions of downward waves showed no prevailing directions over the year. A discussion was given on their different features for different seasons.

The University of Illinois Na wind/temperature lidar data collected at the Starfire Optical Range, New Mexico, can be used to present annual variations of the mesospheric mid-night horizontal winds. For each night, the winds profiles from the 11:00pm to 1:00am were smoothed in 1km altitude and then averaged in time to give mid-night winds profiles. All mid-night winds profiles within one month were averaged again to give mid night winds profiles of that month. The annual variations of the mid-night winds in the altitude ranges from 84km to 100km were obtained using a total of 46 nights lidar data distributed over the months except July. Zonal mid-night winds showed strong annual oscillations. Prevailing westerly winds blew over low altitudes in the winter months and over high altitudes in summer months. Meridional mid-night winds also showed annual or semi-annual oscillations. Southward winds dominated below 90km from April to October, and at about 96km during winter months and summer months except January. Correlations were found between the meridional mid-night winds and the mid-night temperatures. When the meridional winds blow from south, temperatures become warm. Results were compared with calculations of the HWM93 and the mid night winds observed with a MF radar at Urbana. Similar wind structures can be found in their results. The major differences are that strong westerly winds above 94km in March and April and strong northward winds at 96km in January were observed with the lidar. The winds values of the lidar and the MF radar data are larger than those of HWM93. Activities of inertial gravity waves and tidals might contaminated estimations of annual winds with the lidar data and contribute partially to their differences.

DIAL lidars are widely used for the monitoring of stratospheric ozone in the framework of the NDSC (Network for the Detection of Stratospheric changes). Long term DIAL ozone measurements have been performed in the South of France at Observatoire de Haute-Provence (OHP - 43.91°N, 5.71°E) since 1986 and in Antarctica in Dumont d'Urville (66.4°S, 140°E) from 1991 to 2000. At OHP, the measurements allow the study of the short-term and long-term variability of stratospheric ozone in the northern mid-latitude regions. They have been used recently to evaluate the influence of Arctic ozone depletion on mid-latitude ozone amounts. In Antarctica, the lidar measurements allowed the evaluation of the air subsidence in autumn and the ozone loss linked to anthropogenic halogen compounds in spring. Due to the location of the Dumont d'Urville station close to the edge of the polar vortex, a detailed study of the permeability of the polar vortex as a function of altitude could be performed. In addition to long term measurements, an airborne ozone lidar was deployed to sample polar air filaments mixing into mid-latitude regions. These measurements validated high resolution transport models used to evaluate at global scale the influence of polar ozone depleted air on mid-latitude ozone trends.

The upper troposphere should play an important role on the climate. Several greenhouse gazes as well as cirrus clouds present in this region a large variability in both temporal and spatial scales. This variability is strongly connected with processes and air mass exchanges with the lower altitude as well as the stratosphere. The upper troposphere is not easy to probe nor from space nor from the ground. Lidar appears to be a good candidate for probing the upper troposphere. Ozone, water vapor, cirrus clouds, and temperature can be measure with lidar. All those measurements have been deployed in two sites. One is located in south of France at mid-latitude of the Northern Hemisphere and the other at the tropical site of the Southern Hemisphere: La Reunion. The technology has been improved to make such reliable measurements on a routine basis and to implement those measurements on a single lidar. Due to the episodic nature of the variability (in comparison with wave type variability), some questions about lidar signal integration need to be addressed. First climatologies of each parameter independently have been already obtained. Future strategy will be discussed.

Sum frequency generation of sodium D2 resonance radiation (589 nm) based on injection seeded Nd:YAG lasers was applied to a sodium lidar transmitter for temperature measurements of the mesopause region (80-105km). The output energy was 40 mJ / pulse at a repetition rate of 10 Hz and a temporal width of 28 nsec. The laser wavelength at 589 nm (~0.04 pm FWHM) was finely tuned with an accuracy of 0.1pm by seeders. The lidar installed at Syowa station (69°S, 39°E), Antarctica, measured temperature profiles between March and September during 2000 and 2001. Monthly averaged temperature profiles in the mesopause region in wintertime (June, July and August) are nearly 20 K lower than those in the northern hemisphere sites. The measured winter mesopause altitudes (~99 km) are in good agreement with those measured in the northern winter hemisphere. The mesopause temperatures (~175 K) in winter months however are about 20 K lower than those observed from a northern hemisphere conjugate site, Andoya (69°N). The lower winter mesopause temperatures measured at Syowa station, which are consistent with southern hemisphere mesopause temperatures measured by a shipborne lidar, suggest the existence of a hemispheric difference. Possible causes for this difference are discussed.

A multipurpose Lidar was built at Wuhan Institute of Physics & Mathematics, Chinese Academy of Science. The Lidar consists of an YAG laser pumped dye laser system, two receiving telescopes and several detection channels. During the past few years, we conducted some lidar observation in various altitudes of the atmosphere at our location. In this paper, we describe the technical aspects of this multipurpose lidar, and summarize some of the atmosphere observation results obtained by the lidar over Wuhan, China (31 deg N,114 deg E) with the emphasis on the sodium layer detections.

In this paper we present a detailed analysis of the performance of the Goddard Lidar Observatory for Winds (GLOW) Doppler lidar. GLOW is a mobile direct detection Doppler lidar system which uses the double edge technique to measure the Doppler shift of the molecular backscattered laser signal at a wavelength of 355 nm. The lidar has been used in several recent field experiments to measure wind profiles from the surface into the lower stratosphere. Simulations of detected signal levels predicted using a realistic instrument model and representative atmospheric model will be presented and compared with range resolved signals detected with the photon counting data acquisition system. A detailed analysis of wind errors observed with the system will also be reported. The analysis begins by propagating ideal shot noise limited errors through the analysis algorithms used to calculate winds. The resulting shot noise limited errors are compared with statistical standard deviations obtained by averaging multiple independent wind profiles taken at various temporal and spatial sampling scales. An assessment of other instrumental and atmospheric effects contributing to the wind error will also be given.

The Goddard Lidar Observatory for Wind (GLOW) has participated three field campaigns since Sept. 2000. Near 300 hours of wind measurement under a wide variety of conditions including day and night operation, high and low altitude, line of sight and horizontal winds, have been obtained from the GroundWinds intercomparison, Harlie-GLOW intercomparison ( HARGLO) and the International H2O Project (IHOP) field campaigns. The GLOW system has demonstrated the capability to atmospheric wind from ground up to 30 km with an accuracy of 0.4-6m/s.

We have developed a direct-detection scanning Doppler lidar system for wind field measurements in the troposphere. The lidar employs an injection seeded tripled Nd:YAG laser at eye-safe ultraviolet 355nm wavelength, a 25cm aperture telescope and a laser beam scanner. Two high-spectral resolution etalons are used to detect Doppler shift of the aerosol Mie backscattering and the molecular Rayleigh backscattering. Wind measurement accuracy of O.33m/s was obtained at 3km range with 4OmJ laser energy and 5s integration time.

Global wind profiling with a space-borne Doppler lidar is expected to bring big progress in the studies on global climate change and Numerical Weather Prediction. A feasibility study has been done for an eye-safe 2micron coherent Doppler lidar aiming at demonstration of the technology onboard the Japanese Experiment module of the International Space Station. We are now developing an airborne coherent Doppler lidar system to measure wind profile under a jet plane for simulation of the Doppler lidar measurement in space. This system is also operated in the ground to develop algorithm of the wind measurements and the results of the wind profiles are compared with those derived from other instruments.

Space-based global wind observations are a potential application of Doppler lidars. While the use of Doppler lidars to measure winds has existed for several decades, the availability of airborne systems is relatively recent. Ground based Doppler wind lidars (DWL) have provided much experience in interpreting return signals and validating performance models. However, spacebased operations present a very different perspective on the atmosphere. For that reason, airborne lidars are critical in the development of signal processing algorithms and performance model validation for both future space-based as well as sub-orbital instruments. As a component of a program to develop a calibration/validation strategy for all space-based wind observing systems, an airborne coherent 2 micron DWL was flown early in 2002. The primary purpose of those flights was to investigate the surface returns from water. This paper summarizes those missions and offers several examples of the findings.

A field campaign featuring three collocated Doppler wind lidars was conducted over ten days during September 2000 at the GroundWinds Observatory in New Hampshire. The lidars were dissimilar in wavelength and Doppler detection method. The GroundWinds lidar operated at 532 nm and used fringe-imaging direct detection, while the Goddard Lidar Observatory for Winds (GLOW) ran at 355 nm and employed double-edge filter direct detection, and the NOAA mini-MOPA operated at 10 microns and used heterodyne detection. The objectives of the campaign were (1) to demonstrate the capability of the GroundWinds lidar to measure winds while employing several novel components, and (2) to compare directly the radial wind velocities measured by the three lidars for as wide a variety of conditions as possible. Baseline wind profiles and ancillary meteorological data (temperature and humidity profiles) were obtained by launching GPS radiosondes from the observatory as frequently as every 90 minutes. During the final week of the campaign the lidars collected data along common lines-of-sight for several extended periods. The wind speed varied from light to jet stream values, and sky conditions ranged from clear to thick clouds. Intercomparisons of overlapping lidar and radiosonde observations show that all three lidars were able to measure wind given sufficient backscatter. At ranged volumes containing thicker clouds, and those beyond, the wind sensing capability of the direct detection lidars was adversely affected.

GroundWinds 2nd Generation (2nd Gen.) New Hampshire (NH) and GroundWinds Hawaii (HI) are direct detection Doppler LIDAR instruments that operate at 532nm and 355nm, respectively. These ground based incoherent LIDARs utilize backscatter from Rayleigh and Mie scattering to measure Doppler shifts in the atmosphere. The NH and HI instruments routinely make wind measurements from 0.5 to 15 kilometers and achieve sub-meter per second accuracies in the lower troposphere. This paper will provide a brief review of each instrument, and detail the instruments performance and achievements in wind measurement.

In our new compact DDWL (direct-detect wind lidar), we use a CrystaLaser model IRCL-100-1064S laser as a seeder, which has a thermal frequency actuator inside. Given that the external frequency actuator can only achieve green radiation stability and are technically complicated and difficult of application, here we describe a simpler method-applying improved digital PID algorithm to a servo in the compact commercial CrystaLaser laser. A PID algorithm simplifies regulation of even the most difficult cryogenic systems. The PID controller can anticipate the load action to provide closer temperature stability for the laser frequency stabilization. After setting the desired locking point to the process, the controller calculates the output with improved digital PID algorithm, and the output is fed back into the thermal actuator of the laser, which keep the laser locked to the iodine line at a central laser frequency stability level of better than 1 MHz for arbitrarily long periods.

The return Raman Lidar signal contains a strong elastically scattered component (at X) that is useful for profiling clouds and aerosols and also weaker inelastically scattered components that provide chemical-specific information. For profiling water vapor, we use components produced by vibrational Raman effect that produces energy shifts characteristic of the molecules in the atmosphere (3652 cm' for water vapor, 233 1 cm1 for nitrogen). The aim of this paper is to process lidar backscattered signal that contains water vapor and aerosol information in order to improve their recovery. Since they are affected by different kinds of noise, an appropriate filtering, with an improved recovery, represents a way to get good estimates of the above components. Water vapor and aerosols are two significant atmospheric components that are generally detected for a better knowledge of weather and climate. In spite of optical filters included in the experimental apparatus used for this paper, there is a need of further filtering, by using signal digital filtering. To discriminate noises from the main signal that is backscattered from sky, we are investigating on the use of appropriate digital filtering to be utilized in order to retrieval a noiseless signal. This approach is different from the current one that uses a poissonian averaging of collected data. In our investigation, we prefer to employ filters that preserve either amplitude information or phase one. Different kinds of filtering procedures have been used in order to isolate the main signal from noise.

Effect ofatmospheric turbulence on the performance oflaserradar is investigated in this paper. The characteristic of the Gaussian laser beam propagating parallel to the ground in weak turbu'ence is primarily considered. The light intensity fluctuation, beam shifting and spread caused by the turbulence are calculated. The effect of turbulence on laser pulse width is also researched. And then the effect ofthe atmospheric turbulence on laser radar is concluded.

ABSTRACT This paper describes one Raman lidar system for measurements of optical parameters for tropospheric aerosol and cirrus at Hefei (31.9 N/117.17 E) station. Typical extinction and backscatter coefficients profiles of tropospheric aerosol and cloud are presented. Many observation cases show the positive relationship between aerosol optical parameters and water vapor distribution. Some aerosol distributions were captured for dust storm by this Raman lidar in the spring of year 2001~2002. Angstrom coefficient profiles of aerosol are derived in the free troposphere by combining two-wavelength Raman-elastic scattering channels, those values indicate smaller for dust aerosols. Optical thickness and scattering ratio profile of cirrus are obtained by this Raman lidar. The values of extinction to backscatter ratios are frequently found between 20 sr and 70 sr for free tropospheric aerosol, but less than 20 sr for cirrus clouds.

In the present work, directed toward using differential absorption lidar (DIAL) for measuring concentrations of pollutant gases, a monolithic microprocessor-controlled tuning and triggering system for rapidly tuning a TEA C02 laser is reported. It is shown that it is possible to utilize a high frequency stepping motor and a diffraction grating to rapidly select wavelength over rotational transitions in the 9.2-10.8 jtm region of the laser spectrum. The tuning is performed by applying appropriate signals to the stepping motor, which is coupled to the grating via a precision gear box. The microprocessor controls motion of the motor which rotates the correct angle for a given wavelength together with the grating. Many of pollutants have strong absorption lines in the 9-11 im region, therefore the wavelength tunable transversely excited atmospheric-pressure (TEA) CO2 laser becomes an ideal optical source for DIAL.

Optical scanning plays a very important role in LADAR system for large field of view (FOV). But it introduces a Optical scanning lag angle which depends on the detecting range and the angular rate of scanner. Optical scanning lag angle makes a part of received optical energy fall out of the optical sensitive area of detector which will greatly degrade the detecting performance of LADAR in many cases. Optical scanning lag effect and optical scanning lag angle are computational analyzed in detail in this paper. And two conceptual solutions, sub-area receiving way on unit optical sensitive area and electrical scan receiving way on detector array, are proposed.

In order to detect and identify oil-spilled on the sea by Airborne Laser-Induced Fluorescence, a fuzzy model and algorithm are put forward in this paper. The target to be detected on the sea may be one of the following: seawater, crude oil, diesel, lubricating oil, dirty water, sand, etc. The primary requirement for airborne sensors is to identify, in real-time, the substances targeted by the laser beam. There have been several algorithms developed for the detection of oil spilled on the sea by Airborne Laser-Induced Fluorescence, for example, the Pearson Correlation Coefficient method. The reason that we have decided to research the fuzzy model for the identification of oils spilled on the sea, is that there are some uncertainties and unknown differences between the “live” spectrum, and the substances targeted by the laser beam. The fuzzy algorithm presented in this paper is based on a fuzzy closeness matrix. All values in the matrix are calculated from the spectrum of a target and the spectra of the above mentioned “pure” substances. This paper outlines the fuzzy model for the identification of the spilled oils, and makes a comparison with the Pearson Correlation Coefficient method in an effort to increase the level of confidence in the identification results and reduce the computational time. The results of ground tests using known targets show an increased confidence with the identification results using the Fuzzy Model when compared to the results of the Pearson Correlation Coefficient Algorithm.

An optimization model of laser diode (LD) pumped, passively Q-switched, intracavity frequency doubled solid state laser was proposed. The output energy is maximized by optimizing the length of doubling crystal and the initial transmission of saturable absorber. It provides a design criteria of a compact laser source for micro pulse lidar (MPL). The pulse repetition frequency (PRF) is controlled to meet the requirement of MPL. Numerical simulation examples are present to shows the relationship between the output energy and optimized parameters.

A laser airborne depth mapping (LADM) for the topography of coastal water was developed in China. System was implemented in South China Sea between 2001 and 2002. Data processing subsystem is introduced in this paper. Three automated waveform processing algorithms have been developed around several sets of heuristic rules to extract reliably accurate depths with a low false alarm rate. The position, pulse width and ratio of signal to noise are obtained by the low-pass differentiator algorithm (LD). The floor reflecting is determined by the signal above some thresholds in LD method. According to the characteristics of water attenuation, the received signal is revised by the inverse of the water attenuation coefficient (here after, RA method). The bottom is easier to distinguished from the enhanced contrast between the floor reflecting and water scattering. The LD and RA algorithms show a consist results in the post-flight data processing. A more simple and fast algorithms of delayed signal subtracter (DS) is used on flight as a real time data processing, in which the signal is delayed some time abd subtracted by the original signal. The three methods are analyzed in details. The result of data processing isalso presented.

With the requirement of safe navigation in South China Sea, airborne laser bathymetry technique becomes attractive in China recently. A prototype of laser airborne depth mapping (LADM-I) system was developed. System included a diode laser pumped solid-state laser with a repetition rate of 200 Hz and the peak power of 2 Mw, a 15°nadir quasi-elliptical scanner, a combination unit of DGPS and an electronics compass, and a post-flight data processor. System has been demonstrated in South China Sea during last two years. In order to improve sounding density, survey productivity, maximum penetrable depth and accuracy of depth, a new generation of LADM-II is under developed. System will be constituted of a 1 kHz diode pumped laser, INS and KGPS. The performance will also upgrade to meet the higher requirement. In this paper, the detail parameters and specifications of LADM-I, and the experimental result will be reported. The protocol of LADM-II system will be also present.

Rod-shaped thulium-doped gadolinium ortho-vanadate (Tm:GdVO4) crystals have been successfully grown by using the floating zone (FZ) method. The crystals grown showed good transparency and with no cracks and bubbles. Tm:GdVO4 exhibited a strong and wide absorption band around 800 nm. For p polarization of the 5 at.% sample, the absorption coefficient at 799 nm and the linewidth were 21.9 cm-1 and 6.3 nm, respectively. The strong and broad absorption remits the requirements for the LD specification.

By using aerosols as tracers, lidar or laser radar can be applied to study aerosols in the atmosphere that directly or indirectly effect the air quality. The pulsed Nd:YAG lidar system operating at the Ocean Remote Sensing Institute (ORSI), Qingdao, China has been used to get aerosol profiles. The results of the experiments performed on the days with different sky conditions at Qingdao during March-May 2002 indicated significant day-to-day variation in the aerosol profiles. These results are found to be consistent with the aerosol index, which is measured with TOMS (Total Ozone Mapping Spectrometer) and is an index of air quality over a place.

This letter briefly discusses the influence of I2 filter temperature on accuracy of incoherent Doppler lidar measuring wind speed. Using the 1109 line of iodine filter as edge detection, we simulated the relationship between measuring error of wind speed and I2 filter temperature. The simulation result was found that the I2 filter temperature under which the measuring error of wind speed was minimum changed with measured wind speed. We chose the I2 filter temperature as 333K and measured real wind speed with the mobile ground-based incoherent Doppler wind lidar (MIDWiL) system developed by the Ocean Remote Sensing Laboratory of the Ministry of Education of China, Ocean University of Qingdao (OUQ) in November 2000. Results showed the standard deviation of wind speed and wind direction were 0.985 m/s and 17.9 deg. respectively comparing with simultaneous data of pilot balloons.

Automated Mie-scattering lidars have been operated since March 2001 at Beijing, Nagasaki and Tsukuba to reveal the time and height distribution of Asian dust and its optical properties. The lidars detect backscattering light from clouds and aerosols at 532nm in both parallel and perpendicular polarization channels. They continuously measure profiles every 15 minutes regardless of weather conditions. At first we eliminated clouds using vertical profiles of intensity, then Asian dust was identified by the depolarization ratio. In Beijing, close to the source region of the dust, Asian dust events occurred 15 times in March April, and May 2001. Each event continued for several days. The aerosol depolarization ratio (ADR) frequently reached up to 40 %. In Nagasaki, located western part of the Japan, Asian dust was confirmed near the surface with a delay of a few days from events in Beijing. However, in Tsukuba, there were few surface dust events and passing dust in the free troposphere was confirmed. The ADR in Tsukuba were lower than those in other two observatories. Internal mixing of mineral dust and anthropogenic aeorols, and changing size distribution may contribute the differences of ADR among observatories. In Beijing, ground sampling of mineral dust was simultaneously carried out. Mass concentration by the sampler at the surface and extinction coefficient near the surface derived from lidar observation were compared to estimate the conversion factor from extinction coefficient to mass concentration. Utilizing this factor we estimated the vertical distribution of the mass of Asian dust in Beijing.

The paper overviews capabilities of a multi-wavelength laser remote sensing technique in real-time analytical monitoring of aquatic and terrestrial targets. The conceptual design of the Fluorescent Lidar Spectrometer (FLS) - a compact, multipurpose analytical lidar - is described. Its modular architecture allows efficient research and routine monitoring applications from small boats or aircraft. Depending on the application requirements, the FLS analytical performance can be optimized with features such as variable excitation wavelengths and high-speed, gated hyper-spectral detection. The Spectral Fluorescent Signature (SFS) concept, which forms the background for the FLS functioning, has been successful in the detection and identification of trace organics in various environmental, industrial and other mixtures. FLS-lidars have been used in a variety of applications ranging from detecting chemical pollution in water and on soil to classifying marine dissolved organic matter (DOM) and mapping spatial distributions of phytoplankton in the Baltic, North and Norwegian seas. The presented field data obtained with shipborne and airborne FLS illustrate the approachs potential for real-time monitoring of marine, coastal and inland-water environments. Future developments are discussed.

AML-1 Mobile Lidar system is the first mobile lidar system developed in China for measuring the polluted particles in atmosphere. This paper gives the basic principle to measure aerosol, and the way to compute the original data. Finally, As an example, it gives some results ofthe aerosol measured in January, 2002 in Beijing.

In this paper L625 UV-DIAL system was described, and ozone measurement method was briefly introduced. Some observation results were presented and discussed. Ozone data were obtained by L625 UV-DIAL system at Hefei for more than two hundred days. The characteristics of ozone vertical profiles are analyzed, its seasonal variation and stratosphere-troposphere exchange process. Two yearly averaged profiles and their standard deviations were presented.

An eyes-safe, airborne, coherent Doppler lidar (CDL) system has been developed at the Communications Research Laboratory (CRL). It consists of a 2-mm laser transmitter, a receiver, a heterodyne detector, a scanning device, and signal processing equipments. The main objective of the development of this CDL system is to demonstrate the feasibility of CDL from a moving platform. The second objective is to develop a computational algorithm for calculating wind velocity and wind direction. The performance of the CDL was evaluated by a ground-based experiment on wind profiling. That is, zonal, meridional, and vertical wind profiles were obtained by the CDL and by the velocity-azimuth display (VAD) technique with a height resolution of 150 m for every 20 minutes. These profiles were compared with the wind profiles measured by the WindProfiler (WP) installed at CRL. Although the temporal and vertical resolution measured by the CDL differed slightly from that by the WP, the calculated horizontal wind velocity measured by the CDL corresponded well with the WP calculations. It is thus concluded that the developed computational algorithm provides valid calculations of wind velocity.

A new Rayleigh scattering lidar system at eye-safe 355nm ultraviolet wavelength has been developed for measuring vertical profiles of atmospheric temperature in the lower troposphere, based on the high-spectral resolution lidar (HSRL) technique using two narrow-band Fabry-Perot filters. The Doppler broadened width of the Rayleigh backscatter signal was measured for the temperature analysis. The central frequency and the width of the two filters are carefully selected to optimize the detection sensitivity of the filter. In order to reject the intense Mie backscattering component introduced in the Rayleigh signal, which affects the temperature accuracy, the third narrow-band filter has been installed to measure the Mie scattering intensity. A signal processing method has been developed to derive the temperature profile. In a preliminary experiment, it was shown that the temperature sensitivity of the filter is 0.4%/K and the measurement error is about 1K at 2km height.

Tropospheric and stratospheric aerosols were measured with a lidar and a balloon-borne optical particle counter at Lhasa (30 N, 91 E), Tibet, China in August, September, and October, 1999. Also, the vertical profile of ozone by ozone sonde measurements were gained in same period. Ozone concentrations of this area were smaller than those of other region of same latitude especially near tropopause. The number concentration of particles (diameter larger than 0.3 tm) showed noticeable enhancement near the local tropopause, and temporal changes in the particle concentration of the enhanced layer, especially in tropospheric part of the layer, seemed to correlate well to the changes in water vapor content in the mid, and possibly upper, troposphere. Those observations suggest the possibility that the tropopause aerosol particle enhancement associates with water vapor transportation from the lower troposphere to near the tropopause which is caused by active upwelling motion of air over the Tibetan plateau during Asian summer monsoon period. In other words form of aerosols near the tropopause possibly affected by monsoon activities in summer over the Tibetan plateau. The temperature of the local tropopause observed at Lhasa, Tibet was very cold and became frequently lower than frost point of nitric acid trihydrates (NAT) during observational period, and that atmospheric condition contributed to activation of gas to particle conversion process near the tropopause in summer over the Tibetan plateau. The lidar measurements suggested that the enhanced particle (scattering ratio=1.25) had low depolarization ratio, c =0.5%, and showed possibility that particulate near the tropopause was composed of liquid phase particles and not solid state such as cirrus cloud particles. Those lidar measurements, however, were not in the same range of polar stratospheric particles (PSCs) type Ia and/or lb given by previous lidar measurements at polar regions suggesting necessary of new particle formation scenario, which is different from PSCs formation processes in the poiar winter stratosphere, near the cold summer tropopause over the Tibetan plateau.

We made the first lidar observations of polar mesospheric clouds (PMC) at the South Pole and in the southern hemisphere with an Fe Boltzmann temperature lidar in the 1999-2000 and 2000-2001 austral summer seasons. Strong PMC activities were observed at the South Pole and extensive data were collected. Here we summarize the lidar observation results including the interannual, seasonal and diurnal variations of PMC altitude, brightness and occurrence probability. In particular, our data show that PMC at the South Pole are a few kilometers higher than in the northern hemisphere and PMC at the South Pole exhibit seasonal trends in both altitude and brightness. We explore the possible causes through the study of atmospheric thermal structure and upwelling wind by using NCAR TIME-GCM model and then presenting a PMC altitude model. Our initial conclusion is that these hemispheric differences and seasonal trends in PMC altitudes are the combination results of the hemispheric differences in thermal structure and upwelling wind, which are caused by the Earth orbital eccentricity and inter-hemisphere difference in gravity wave forcing.

Shipborne laser bathymetric system

This paper presents the test results of a clock distributor, which was applied to Changchun and Beijing Satellite Laser Ranging (SLR) system. It gives out the ground target calibration results and ranging satellite results. After applying the clock distributor, the precision of calibrating ground targets and ranging satellites has several mm improvements. It also shows the comparison results of standard frequency source provided only by HP58503A GPS receiver and by HP58503A GPS receiver through the clock distributor.

The incoherent Doppler lidar technique using the frequency doubled Nd:YAG laser which was alternately tuned to the both slopes of one absorption line of the molecular iodine was developed and wind measurements were observed from 8 to 25km with 500m range resolution. Owing to the evaluation of measurement accuracy of this Doppler lidar, the truth of the zero wind is confirmed by using the direct reflection light from the hard target and the standard deviation is 0.35m/s. The comparison observations between the lidar wind velocities and the wind profiles of a wind profiler are performed experimentally.

The rationale and justification for aerosol and cirrus cloud observations in the equatorial region of the central Pacific are presented. The development of a small, fully automatic lidar system, powered by wind and solar energy, is discussed.