L625差分吸收激光雷达探测对流层臭氧

介绍了用于探测对流层大气臭氧的L6 2 5差分吸收激光雷达系统 ,叙述了该激光雷达的结构、探测大气臭氧的原理和数据处理方法。利用波长对 2 89～ 2 99nm和 2 89～ 30 8nm对合肥上空中、上部对流层的臭氧进行了对比测量。测量结果表明 ,这两对波长的测量结果差别约在 10 %左右。分析了 2 89～ 30 8nm波长对测量臭氧的结果和误差。 10km以下 ,2 89～ 30 8nm波长对测量的对流层臭氧统计误差绝对值一般小于 2× 10 11molecules/cm3 ,忽略气溶胶影响引起的相对系统误差一般小于 4 %。给出和分析了合肥地区对流层 5～ 15km臭氧柱含量的季节变化特征 ,柱含量最大的月份一般出现在第二季度 ,柱含量最小的月份一般出现在第三季度。     

Intercomparison of ozone profiles measurements by a differential absorption lidar system and satellite instruments at Buenos Aires, Argentina

A ground-based DIfferential Absorption Lidar (DIAL) system has been implemented at CEILAP (CITEFA-CONICET) laboratory (34°33′S, 58°30′W), located in the Buenos Aires industrial suburbs. The goal is to perform measurements of the stratospheric ozone layer. Systematic measurements of ozone concentration profiles from 18 to 35 km altitude are performed since early 1999. Our measurements are carried out in 5 h in average during the night and in cloudless conditions. The DIAL system allows us to calculate directly the ozone profile from the lidar backscattering radiation since it is a self-calibrating technique. The signal processing takes into account the influence of the temperature profile on the ozone cross section. The temperature data are obtained from the radiosondes measurements performed at Ezeiza International Airport (34°30′S, 58°18′W), 27 km from DIAL station. The evolution of the stratospheric ozone profile is studied for different months. Results are compared with the data obtained by different satellites SAGE II, HALOE and GOME. The comparisons between our DIAL system and the satellite measurements show an agreement better than 20% for 20–35 km altitude range.     

LIDAR mapping of ozone-episode dynamics in Paris and intercomparison with spot analyzers Supplementary material available at http://link.springer.de/journals/apb

Continuous mapping of an ozone episode in Paris in June 1999 has been performed using a differential absorption lidar system. The 2D ozone concentration vertical maps recorded over 33 h at the Champ de Mars are compiled in a video clip that gives access to local photochemical dynamics with unprecedented precision. The lidar data are compared over the whole period with point monitors located at 0-, 50-, and 300-m altitudes on the Eiffel Tower. Very good agreement is found when spatial resolution, acquisition time, and required concentration accuracy are optimized. Sensitivity to these parameters for successful intercomparison in urban areas is discussed. Received: 11 February 2002 / Published online: 14 March 2002     

A comparison method for spaceborne and ground-based lidar and its application to the CALIPSO lidar

A method is proposed to aid in the comparison of spaceborne lidar measurements with ground-based lidar measurements. The downward attenuated backscatter is constructed from ground-based lidar data, and then compared to the attenuated backscatter measured by spaceborne lidar. To test the accuracy of the method, sensitivity analysis is performed. This method is applied to compare the measurements between the CALIPSO lidar and ground-based lidar at Hampton University. The comparison results show this method is a feasible and reasonable approach for spaceborne lidar validation. Moreover, it can help to retrieve aerosol optical properties.     

Ground-based monitoring of pinatubo aerosols and ozone at L''Aquila, Italy I.—Evidences for ozone depletion during 1991/92 winter months

Summary Possible evidence for stratospheric ozone depletion at northern midlatitudes as a consequence of the Pinatubo aerosol cloud is presented in this work. A ten-month record of aerosol and ozone measurements taken at the lidar station of L'Aquila, Italy, is compared to the 1985–1986 SBUV and SAGE II ozone data. Ozonesonde data collected in the station of Hohenpeissenberg, Germany, and S. Pietro Capofiume, Italy, are used to validate the DIAL measurements corrected for the aerosol presence.     

Monitoring of the stratospheric ozone layer by laser radar

Monitoring of the height distribution of atmospheric ozone up to 50 km is being performed with a ground-based lidar system, which has been in operation since October 1982 on the summit of Zugspitze in the German Alps. Daily and monthly averages of the ozone profile are being obtained with high precision. Furthermore, stratospheric aerosol layers, originating from the eruption of El Chichon volcano in Mexico in sping 1982 are being recorded.     

Neural networks for the dimensionality reduction of GOME measurement vector in the estimation of ozone profiles

Dimensionality reduction can be of crucial importance in the application of inversion schemes to atmospheric remote sensing data. In this study the problem of dimensionality reduction in the retrieval of ozone concentration profiles from the radiance measurements provided by the instrument Global Ozone Monitoring Experiment (GOME) on board of ESA satellite ERS-2 is considered. By means of radiative transfer modelling, neural networks and pruning algorithms, a complete procedure has been designed to extract the GOME spectral ranges most crucial for the inversion. The quality of the resulting retrieval algorithm has been evaluated by comparing its performance to that yielded by other schemes and co-located profiles obtained with lidar measurements.     

A comprehensive optical investigation of processes of transformation of the ozonosphere above Tomsk

The results are given on experimental optical research into variations and peculiarities of the time dependence of the total ozone content (TOC) and the influence of an eruption of the Pinatubo Volcano on the stratospheric ozone layer, as well as observations of local negative ozone anomalies and polar stratospheric clouds (PSCs), obtained during lidar and spectrophotometric measurements at the Siberian Lidar Station (56°.5 N, 85°.0 E). It is shown that normal and anomalous deviations in TOC are due to atmospheric dynamics and depend on the amount of anomaly in the atmospheric processes themselves. Under the conditions of considerable loading of the stratosphere with volcanogenic aerosol, a substantial inverse relationship between aerosol and ozone contents is observed. The formation of PSCs and a local TOC decrease correspond to an anomalous thermodynamic state of the troposphere and lower stratosphere. Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 75–82, September, 1998.     

基于差分吸收激光雷达的一种新的对流层臭氧浓度反演算法

差分吸收激光雷达探测对流层臭氧浓度时,气溶胶的干扰会造成较大的误差。提出了一种算法,该算法能够同时反演得到对流层臭氧浓度和气溶胶消光系数,减少气溶胶对反演结果的影响。使用实验数据,分析计算了气溶胶雷达比,气溶胶波长指数、标定点气溶胶后向散射比各种变化参数对反演结果的误差。结果表明,1 km以下,各种变化参数造成的反演误差小于8%,1 km以上臭氧浓度误差主要来源于信号和背景噪声,各种参数反演误差小于3%。最后给出了利用该算法得到对流层臭氧浓度和气溶胶的消光系数垂直廓线,并和传统的双波长差分算法反演结果作了比较分析。实验结果表明该算法是可行的,该算法可以减少气溶胶对差分吸收激光雷达测量结果引起的误差。     

Gome ozone profiles retrieved by neural network techniques: A global validation with lidar measurements

Ozone profiles retrieved from Global Ozone Monitoring Experiment (GOME, flying on ERS-2 satellite) spectra from July 1995 to June 2003 by means of 2 independent neural network (NN) schemes have been validated with ozone lidar measurements performed at different stations belonging to the network for the detection of atmospheric composition changes (NDACC). The retrieval and the whole validation have been carried out by using the performances and resources of the European project Enabling Grid for E-sciencE (EGEE) and of a local Grid at the European Space Research Institute of the European Space Agency (ESRIN/ESA). Roughly 1800 collocated profiles have been found, in tropical, mid-latitude and high-latitude regions; for each lidar station the differences between GOME and lidar profiles have been evaluated and the global performance of the proposed NN approaches has been critically discussed. The results indicate the potentialities for obtaining reliable ozone field analysis on global scale, including detailed altitude resolved trend analysis.     

Two-wavelength lidar inversion algorithm for determination of aerosol extinction-to-backscatter ratio and its application to CALIPSO lidar measurements

A modified two-wavelength lidar inversion algorithm is proposed to aid in the retrieval of aerosol extinction-to-backscatter ratios (lidar ratio) as well as backscatter coefficients and extinction color ratios from simultaneous two-wavelength elastic backscatter lidar measurements. To demonstrate the feasibility of the algorithm, both the Raman method and the two-wavelength method have been applied to the ground-based measurements at 355 and 532 nm; moreover, it has been applied to the data acquired by the Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar, and to the simultaneous ground-based lidar measurements carried out at Napoli (southern Italy, 40.838 °N, 14.183 °E, 118 m above sea level). Three cases of Saharan dust transport towards Europe have been considered. From the comparison, it can be found that the values of lidar ratio and backscatter coefficient retrieved by the modified two-wavelength algorithm are in good agreement with those obtained by the Raman method. Moreover the retrieved mean values of the lidar ratios and color ratios are in agreement with those reported by other authors.     

Retrieving aerosol backscattering coefficient for short range lidar using parameter selection at reference point

<正>A new method is proposed based on the analysis of lidar equation which selects aerosol backscatter ratio at a reference point for short range lidar in data processing.Simulation computation and experimental comparison results show that this method is reasonable and feasible.The method is applied to short range lidars,such as atmospheric monitoring lidar-2(AML-2) and micro-pulse lidar(MPL).     

Comparison of CALIPSO and ground-based lidar profiles over Chung-Li, Taiwan

We report the first inter-comparison of vertical profiles of aerosols and clouds derived from space (CALIPSO) and ground based lidar over Chung-Li, Taiwan. Results show that inter-comparison is closer in case of aerosols than clouds. The strength/shortcoming of the comparison has been also discussed. An iterative calculation to retrieve extinction-to-backscatter ratio (lidar ratio) by using sun-photometer and CALIPSO data is also documented. By using the mentioned method, a mean lidar ratio of 23.5±8.2 sr was found. The derived lidar ratios are lower than former studies. The possible reasons for the difference have been discussed in this paper. The discussed methodology will be helpful to reduce the uncertainty of optical parameters derived from lidar data especially near the surface where the atmosphere is inhomogeneous.     

噪音信号对夜间对流层臭氧探测准确度的影响

本文探讨在背景噪音影响下,差分吸收激光雷达测量臭氧的不确定性:背景噪音对臭氧浓度廓线的影响正比于背景噪音强度、强吸收波长和弱吸收波长的回波信号强度比.理论计算结果表明:合适的回波信号强度比可以使激光雷达背景信号对夜间臭氧探测浓度的影响变得非常小,可以忽略不计.实验结果表明:用波长对(280 nm,285 nm)对大气臭氧进行观测时,适当调节两波长回波信号强度比为0.96时,背景信号对臭氧浓度探测的影响小到可以忽略的程度.模拟分析和实验观测结果相接近,证实了理论推算的合理性.在背景噪音强度未知的情况下,通过调整强吸收和弱吸收两波长的激光脉冲的能量,在示波器上得到适合的回波信号强度比值,可以抑制背景噪音信号对臭氧探测结果的影响,确保夜间臭氧测量的准确性.     

Precursor experiment for an active true airspeed sensor

The feasibility of an active optical true airspeed sensor was demonstrated with a coherent short-range Doppler lidar. Even at the long wavelength of 10.6 mum , aerosol events at the high altitude of 12, 000 m were measured. A comparison of the line-of-sight velocity obtained by lidar measurements with a conventional five-hole probe on an aircraft showed an excellent coincidence in the average value, although the lidar detected turbulence effects much more sensitively.     

基于星载激光雷达数据的海面风速探测

使用新版(Version 3.01)星载激光雷达CALIPSO Level 1剖面数据和Level 2的大气气溶胶光学厚度(AOD)数据反演全球海面风速。将AOD数据用于大气双程透射率的校正。对CALIPSO所采集的2007年1月、4月、7月和10月532nm波长无云激光测量数据进行应用计算,采用532nm退偏比经验修正海面白帽及水下次表层水体散射的影响,同时选用准同步的AMSR-E海面风速测量值为真值进行对比。对应2007年的4个月,由CALIPSO星载激光雷达532nm单脉冲测量数据反演海面风速的标准偏差分别为1.24、1.24、1.24、1.20m/s,由5km滚动平均数据反演海面风速的标准偏差分别为0.98、1.02、0.98、0.94m/s。结果表明,采用的数据反演方法可行且数据利用率得到提高。     

Particle Size Distributions Based on a Multipopulation Genetic Algorithm Used in Multiwavelength Lidar

Aerosols influence the radiation budget of the Earth’s atmospheric system. Aerosol particle size distribution is one of the major parameters used for characterizing aerosol influence on radiative forcing. The optical and microphysical properties of aerosol particles over Yinchuan, China, were measured with a multiwavelength lidar developed at Beifang University of Nationalities using backscatter and extinction coefficients at wavelengths of 1064, 532, and 355 nm. These data were used to retrieve particle size distributions. Given the disadvantages of the traditional regularization method, the innovative multipopulation genetic algorithm (MPGA) was used to retrieve the particle size distribution from the lidar data. To verify the feasibility of using the MPGA on multiwavelength lidar data, experiments were carried out under different atmospheric conditions, including a background sunny day, a cloudy day, and a foggy day. The particle size distributions obtained from the multiwavelength lidar data were compared with results retrieved from direct irradiance data from a sun photometer. Results showed that the MPGA is suitable for retrieving particle size distributions from multiwavelength lidar data.     

Tunable ultraviolet optical parametric oscillator for differential absorption lidar measurements of tropospheric ozone

A pulsed optical parametric oscillator (OPO) with intracavity sum frequency mixing was developed generating energies of up to 16 mJ in the 281–293 nm wavelength range. Both OPO process and sum frequency mixing are pumped by the harmonics of a single, medium-sized Nd:YAG laser. The system is characterized by a high overall efficiency (∼4% conversion from 1064 nm to the UV), a very compact set-up and stable and reliable operation. This system was successfully employed to measure tropospheric ozone using the differential absorption lidar (DIAL) technique and shows much promise as a lidar transmitter in airborne case studies as well as in unattended lidar systems for long-term monitoring. An unattended ozone profiling system could already be successfully realized. Received: 1 April 2002 / Revised version: 30 May 2002 / Published online: 2 September 2002 RID="*" ID="*"Corresponding author. Fax: +49-8153/28-1271, E-mail: Andreas.Fix@dlr.de     

Lidar Network System for Monitoring the Atmospheric Environment in Jakarta City

A lidar network system consisting of two Mie scattering lidars and one differential absorption lidar was developed to measure the atmospheric environment in Jakarta. The three lidars were installed at three locations in Jakarta to study atmospheric boundary layer structure and transportation of atmospheric pollutants. The Mie scattering lidars employ compact flashlamp pumped Nd:YAG lasers operated at 1064 nm fundamental. They are installed in shelters and directed vertically. One of the Mie lidar has a rotating wedged window for scanning conically to measure wind velocity using a correlation method. The DIAL system employs two Nd:YAG laser-pumped optical parametric oscillators. The DIAL is designed to measure distribution of ozone and SO₂ in the near UV region, and NO₂ in the 450-nm region. The system is installed in a shelter and has a full scanning capability.