Download or read book Raman lidar measurement of the atmospheric aerosol extinction profile written by Maren Riebesell and published by . This book was released on 1991 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of atmospheric aerosol extinction profiles with a Raman lidar written by Albert Ansmann and published by . This book was released on 1990 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Final Technical Report Cloud and Radiation Testbed CART Raman Lidar Measurement of Atmospheric Aerosols for the Atmospheric Radiation Measurement ARM Program written by and published by . This book was released on 2002 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vertical profiles of aerosol extinction are required for determination of the effects of aerosols on the clear-sky radiative flux. Since recent studies have demonstrated the inability to compute these profiles on surface aerosol measurements alone, vertical profiles of aerosol optical properties must be acquired to compute aerosol radiative effects throughout the entire atmospheric column. Following the recommendation of the ARM Aerosol Working Group, the investigator developed, evaluated, and implemented algorithms for the CART Raman Lidar to provide profiles of aerosol extinction and backscattering. By virtue of its ability to measure vertical profiles of both aerosol extinction and water vapor simultaneously in the same scattering volume, we used the resulting profiles from the CART Raman Lidar to investigate the impact of water vapor and relative humidity on aerosol extinction throughout the column on a continuous and routine basis. The investigator used these the CART Raman Lidar aerosol extinction and backscattering profiles to evaluate the vertical variability of aerosol extinction and the extinction/backscatter ratio over the ARM SGP site.

Download or read book Arr t s et remontrances du parlement de Bordeaux au roi sur ce qui a suivi la r clamation de cette compagnie contre les lettres patentes accord es en 1752 au bureau des finances 21 juillet 1756 written by and published by . This book was released on 1756 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Colloque europ en d conomie de l nergie written by and published by . This book was released on 1965 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Examination of the Raman Lidar Technique for Water Vapor and Aerosols written by David N. Whiteman and published by BiblioGov. This book was released on 2013-08 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: The intent of this paper and its companion is to compile together the essential information required for the analysis of Raman lidar water vapor and aerosol data acquired using a single laser wavelength. In this first paper several details concerning the evaluation of the lidar equation when measuring Raman scattering are considered. These details include the influence of the temperature dependence of both pure rotational and vibrational-rotational Raman scattering on the lidar profile. These are evaluated for the first time using a new form of the lidar equation. The results indicate that, for the range of temperatures encountered in the troposphere, the magnitude of the temperature dependent effect can reach 10% or more for narrowband Raman water vapor measurements. Also the calculation of atmospheric transmission is examined carefully including the effects of depolarization. Different formulations of Rayleigh cross section determination commonly used in the lidar field are compared revealing differences up to 5% among the formulations. The influence of multiple scattering on the measurement of aerosol extinction using the Raman lidar technique is considered as are several photon pulse-pileup correction techniques.

Download or read book Solutions in LIDAR Profiling of the Atmosphere written by Vladimir A. Kovalev and published by John Wiley & Sons. This book was released on 2015-02-17 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides tools and techniques to identify and address distortions and to interpret data coming from Lidar sensing technology This book covers the issues encountered in separating the backscatter and transmission terms in the LIDAR equation when profiling the atmosphere with zenith-directed and vertically-scanning Lidars. Solutions in Lidar Profiling of the Atmosphere explains how to manage and interpret the Llidar signals when the uncertainties of the involved atmospheric parameters are not treatable statistically. The author discusses specific scenarios for using specific scenarios for profiling vertical aerosol loading. Solutions in Lidar Profiling of the Atmosphere emphasizes the use of common sense when interacting with potentially large distortions inherent in most inversion techniques. Addresses the systematic errors in LIDAR measurements Proposes specific methods to estimate systematic distortions Explains how to apply these methods to both simulated and real data Solutions in Lidar Profiling of the Atmosphere is written for scientists, researchers, and graduate students in Meteorology and Geophysics.

Download or read book Analysis and Calibration of CRF Raman Lidar Cloud Liquid Water Measurements written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Atmospheric Radiation Measurement (ARM) Raman lidar (RL), located at the Southern Great Plains (SGP) Climate Research Facility (CRF), is a unique state-of-the-art active remote sensor that is able to measure profiles of water vapor, aerosol, and cloud properties at high temporal and vertical resolution throughout the diurnal cycle. In October 2005, the capability of the RL was extended by the addition of a new detection channel that is sensitive to the Raman scattering of liquid water. This new channel permits the system, in theory, to measure profiles of liquid water content (LWC) by the RL. To our knowledge, the ARM RL is the only operation lidar with this capability. The liquid water Raman backscattering cross-section is a relatively weak and spectrally broad feature, relative to the water vapor Raman backscatter signal. The wide bandpass required to achieve reasonable signal-to-noise in the liquid water channel essentially eliminates the ability to measure LWC profiles during the daytime in the presence of large solar background, and thus all LWC observations are nighttime only. Additionally, the wide bandpass increases the probability that other undesirable signals, such as fluorescence from aerosols, may contaminate the observation. The liquid water Raman cross-section has a small amount of overlap with the water vapor Raman cross-section, and thus there will be a small amount of 'cross-talk' between the two signals, with water vapor contributing a small amount of signal to the LWC observation. And finally, there is significant uncertainty in the actual strength of the liquid water Raman cross-section in the literature. The calibrated LWC profiles, together with the coincident cloud backscatter observations also made by the RL, can be used to derive profiles of cloud droplet effective radius. By combining these profiles of effective radius in the lower portion of the cloud with the aerosol extinction measurements made below the cloud by the RL, the first aerosol indirect effect can be investigated using a single instrument, thereby reducing the uncertainty associated with aligning the different sampling periods and fields of view of multiple instruments. We have applied a "first principles" calibration to the LWC profiles. This approach requires that the relative differences in optical efficiency between the water vapor and liquid water channels be known; this relative difference is easily computed using the efficiency values of the beam splitters and interference filters in the lidar that were provided by the vendors of these components. The first principles approach then transfers the calibration from the water vapor mixing ratio to the LWC using the difference in the optical efficiency and an interpolated value of the liquid water Raman cross section from the literature, and the better established water vapor Raman cross section. After accounting for all known error sources, the vertical integral of LWC was compared against a similar value retrieved from a co-located ground-based infrared radiometer. The RL and infrared radiometer have significantly different fields of view; thus to compare the two sensors the data were averaged to 5 min intervals where only cloudy samples were included in the average of each. While there is fair scatter in the data (r=0.47), there is also a clear indication of a positive correlation between the infrared and the RL values. The value of the slope of the regression is 0.49, which indicates a tendency of the RL measurements to underestimate the total liquid amount with respect to the infrared retrieval. Research continues to investigate the source of the bias, but the most likely candidate is the large uncertainty in the liquid water Raman cross-section as there have been no direct measurements made of this parameter at the lidar's laser wavelength of 355 nm. The calibrated LWC profile was then used together with the cloud backscatter coefficient profile from the RL to derive profiles of cloud droplet effective radius and cloud droplet number density. These profiles of cloud droplet size together with the aerosol extinction observed by the same lidar are used to investigate the aerosol indirect effect in several case studies in August 2006. Russo F. "An investigation of Raman lidar measurements and their application to the study of the aerosol indirect effect", PhD Thesis (2007). Russo F., D.N. Whiteman, D.D. Turner, B.B. Demoz, R.M. Hoff, I. Veselovskii, "Measurements of the Aerosol Indirect Effect using a Raman lidar. Part 1: cloud liquid water measurements", manuscript in preparation. Russo F., D.N. Whiteman, D.D. Turner, B.B. Demoz, R.M. Hoff, I. Veselovskii, "Measurements of the Aerosol Indirect Effect using a Raman lidar. Part 2: the calculation of IE", manuscript in preparation.

Download or read book Raman Lidar Profiling of Water Vapor and Aerosols Over the ARM SGP Site written by and published by . This book was released on 2000 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have developed and implemented automated algorithms to retrieve profiles of water vapor mixing ratio, aerosol backscattering, and aerosol extinction from Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) Raman Lidar data acquired during both daytime and nighttime operations. This Raman lidar system is unique in that it is turnkey, automated system designed for unattended, around-the-clock profiling of water vapor and aerosols (Goldsmith et al., 1998). These Raman lidar profiles are important for determining the clear-sky radiative flux, as well as for validating the retrieval algorithms associated with satellite sensors. Accurate, high spatial and temporal resolution profiles of water vapor are also required for assimilation into mesoscale models to improve weather forecasts. We have also developed and implemented routines to simultaneously retrieve profiles of relative humidity. These routines utilize the water vapor mixing ratio profiles derived from the Raman lidar measurements together with temperature profiles derived from a physical retrieval algorithm that uses data from a collocated Atmospheric Emitted Radiance Interferometer (AERI) and the Geostationary Operational Environmental Satellite (GOES) (Feltz et al., 1998; Turner et al., 1999). These aerosol and water vapor profiles (Raman lidar) and temperature profiles (AERI+GOES) have been combined into a single product that takes advantage of both active and passive remote sensors to characterize the clear sky atmospheric state above the CART site.

Download or read book The Refurbishment and Upgrade of the Atmospheric Radiation Measurement Raman Lidar written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) Raman lidar (CARL) is an autonomous, turn-key system that profiles water vapor, aerosols, and clouds throughout the diurnal cycle for days without attention (Goldsmith et al. 1998). CARL was first deployed to the Southern Great Plains CRF during the summer of 1996 and participated in the 1996 and 1997 water vapor intensive operational periods (IOPs). Since February 1998, the system has collected over 38,000 hrs of data (equivalent of almost 4.4 years), with an average monthly uptime of 62% during this time period. This unprecedented performance by CARL makes it the premier operational Raman lidar in the world. Unfortunately, CARL began degrading in early 2002. This loss of sensitivity, which affected all observed variables, was very gradual and thus was not identified until the autumn of 2003. Analysis of the data suggested the problem was not associated with the laser or transmit portion of the system, but rather in the detection subsystem, as both the background values and the peak signals showed a marked decreases over this time period. The loss of sensitivity of a factor of 2-4, depending on the channel, resulted in higher random error in the retrieved products, such as the aerosol backscatter coefficient and water vapor mixing ratio. Figure 1 shows the random error at 2 km for aerosol backscatter coefficient (top) and water vapor mixing ratio (middle), in terms of percent of the signal for both average daytime (red) and nighttime (blue) data from 1998 to 2005. The seasonal variation of water vapor is easily seen in the random error in the water vapor mixing ratio data. The loss of sensitivity also affected the maximum range of the usable data, as illustrated by the dramatic decrease in the maximum height seen in the water vapor mixing ratio data (bottom). This degradation, which results in much larger random errors, greatly hinders the analysis of data sets such as the Aerosol IOP (March 2003) and the AIRS Water Vapor Experiment (December 2003). The degradation and its impact on the Aerosol IOP analysis are reported in Ferrare et al. 2005.

Download or read book Lidar Technologies Techniques and Measurements for Atmospheric Remote Sensing written by Upendra N. Singh and published by SPIE-International Society for Optical Engineering. This book was released on 2005 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of SPIE present the original research papers presented at SPIE conferences and other high-quality conferences in the broad-ranging fields of optics and photonics. These books provide prompt access to the latest innovations in research and technology in their respective fields. Proceedings of SPIE are among the most cited references in patent literature.

Download or read book New Examination of the Traditional Raman Lidar Technique written by David N. Whiteman and published by BiblioGov. This book was released on 2013-08 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: The intent of this paper and its companion paper is to pull together the essential information required for the traditional Raman lidar data analysis to be performed. As a part of this, complications such as the temperature dependence of the water vapor signal is evaluated through numerical simulation. A new form of the lidar equation is presented that accounts for the temperature dependence of Raman scattering. Also the calculation of atmospheric transmission is examined carefully. Several photon correction techniques are considered as is the influence of multiple scattering on the measurement of aerosol extinction using the Raman lidar technique.

Download or read book Lidar written by Claus Weitkamp and published by Springer Science & Business. This book was released on 2006-06-03 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by leading experts in optical radar, or lidar, this book brings all the recent practices up-to-date. With a Foreword by one of the founding fathers in the area. Its broad cross-disciplinary scope should appeal to scientists ranging from the view of optical sciences to environmental engineers. Optical remote sensing has matured to become a lead method for cross-disciplinary research. This new multi-authored book reviews the state-of-the-art in a readable monograph.

Download or read book Turn key Raman Lidar for Profiling Atmospheric Water Vapor Clouds and Aerosols at the US Southern Great Plains Climate Study Site written by and published by . This book was released on 1997 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are clearly identified scientific requirements for continuous profiling of atmospheric water vapor at the Department of Energy, Atmospheric Radiation Measurement program, Southern Great Plains CART (Cloud and Radiation Testbed) site in northern Oklahoma. Research conducted at several laboratories has demonstrated the suitability of Raman lidar for providing measurements that are an excellent match to those requirements. We have developed and installed a ruggedized Raman lidar system that resides permanently at the CART site, and that is computer automated to eliminate the requirements for operator interaction. In addition to the design goal of profiling water vapor through most of the troposphere during nighttime and through the boundary layer during daytime, the lidar provides quantitative characterizations of aerosols and clouds, including depolarization measurements for particle phase studies.

Download or read book The Atmospheric Radiation Measurement ARM Program written by D. D. Turner and published by . This book was released on 2018-03-09 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Comparative Aerosol Studies Based on Multi wavelength Raman LIDAR at Ny lesund Spitsbergen written by Anne Hoffmann and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Arctic is a particularly sensitive area with respect to climate change due to the high surface albedo of snow and ice and the extreme radiative conditions. Clouds and aerosols as parts of the Arctic atmosphere play an important role in the radiation budget, which is, as yet, poorly quantified and understood. The LIDAR (Light Detection And Ranging) measurements presented in this PhD thesis contribute with continuous altitude resolved aerosol profiles to the understanding of occurrence and characteristics of aerosol layers above Ny-Ålesund, Spitsbergen. The attention was turned to the analysis of periods with high aerosol load. As the Arctic spring troposphere exhibits maximum aerosol optical depths (AODs) each year, March and April of both the years 2007 and 2009 were analyzed. Furthermore, stratospheric aerosol layers of volcanic origin were analyzed for several months, subsequently to the eruptions of the Kasatochi and Sarychev volcanoes in summer 2008 and 2009, respectively. The Koldewey Aerosol Raman LIDAR (KARL) is an instrument for the active remote sensing of atmospheric parameters using pulsed laser radiation. It is operated at the AWIPEV research base and was fundamentally upgraded within the framework of this PhD project. It is now equipped with a new telescope mirror and new detection optics, which facilitate atmospheric profiling from 450m above sea level up to the mid-stratosphere. KARL provides highly resolved profiles of the scattering characteristics of aerosol and cloud particles (backscattering, extinction and depolarization) as well as water vapor profiles within the lower troposphere. Combination of KARL data with data from other instruments on site, namely radiosondes, sun photometer, Micro Pulse LIDAR, and tethersonde system, resulted in a comprehensive data set of scattering phenomena in the Arctic atmosphere. The two spring periods March and April 2007 and 2009 were at first analyzed based on meteorological parameters, like local temperature and relative humidity profiles as well as large scale pressure patterns and air mass origin regions. Here, it was not possible to find a clear correlation between enhanced AOD and air mass origin. However, in a comparison of two cloud free periods in March 2007 and April 2009, large AOD values in 2009 coincided with air mass transport through the central Arctic. This suggests the occurrence of aerosol transformation processes during the aerosol transport to Ny-Ålesund. Measurements on 4 April 2009 revealed maximum AOD values of up to 0.12 and aerosol size distributions changing with altitude. This and other performed case studies suggest the differentiation between three aerosol event types and their origin: Vertically limited aerosol layers in dry air, highly variable hygroscopic boundary layer aerosols and enhanced aerosol load across wide portions of the troposphere. For the spring period 2007, the available KARL data were statistically analyzed using a characterization scheme, which is based on optical characteristics of the scattering particles. The scheme was validated using several case studies. Volcanic eruptions in the northern hemisphere in August 2008 and June 2009 arose the opportunity to analyze volcanic aerosol layers within the stratosphere. The rate of stratospheric AOD change was similar within both years with maximum values above 0.1 about three to five weeks after the respective eruption. In both years, the stratospheric AOD persisted at higher rates than usual until the measurements were stopped in late September due to technical reasons. In 2008, up to three aerosol layers were detected, the layer structure in 2009 was characterized by up to six distinct and thin layers which smeared out to one broad layer after about two months. The lowermost aerosol layer was continuously detected at the tropopause altitude. Three case studies were performed, all revealed rather large indices of refraction of m = (1.531.55) - 0.02i, suggesting the presence of an absorbing carbonaceous component. The particle radius, derived with inversion calculations, was also similar in both years with values ranging from 0.16 to 0.19 æm. However, in 2009, a second mode in the size distribution was detected at about 0.5 æm. The long term measurements with the Koldewey Aerosol Raman LIDAR in Ny-Ålesund provide the opportunity to study Arctic aerosols in the troposphere and the stratosphere not only in case studies but on longer time scales. In this PhD thesis, both, tropospheric aerosols in the Arctic spring and stratospheric aerosols following volcanic eruptions have been described qualitatively and quantitatively. Case studies and comparative studies with data of other instruments on site allowed for the analysis of microphysical aerosol characteristics and their temporal evolution.

Download or read book ARM written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 1-minute Raman Lidar: aerosol extinction profiles and aerosol optical thickness, from first Ferrare algorithm.