Download or read book Using Radar Lidar and Radiometer Measurements to Classify Cloud Type and Study Middle Level Cloud Properties written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The project is concerned with the characterization of cloud macrophysical and microphysical properties by combining radar, lidar, and radiometer measurements available from the U.S. Department of Energy's ARM Climate Research Facility (ACRF). To facilitate the production of integrated cloud product by applying different algorithms to the ARM data streams, an advanced cloud classification algorithm was developed to classified clouds into eight types at the SGP site based on ground-based active and passive measurements. Cloud type then can be used as a guidance to select an optimal retrieval algorithm for cloud microphysical property retrieval. The ultimate goal of the effort is to develop an operational cloud classification algorithm for ARM data streams. The vision 1 IDL code of the cloud classification algorithm based on the SGP ACRF site observations was delivered to the ARM cloud translator during 2004 ARM science team meeting. Another goal of the project is to study midlevel clouds, especially mixed-phase clouds, by developing new retrieval algorithms using integrated observations at the ACRF sites. Mixed-phase clouds play a particular role in the Arctic climate system. A multiple remote sensor based algorithm, which can provide ice water content and effective size profiles, liquid water path, and layer-mean effective radius of water droplet, was developed to study arctic mixed-phase clouds. The algorithm is applied to long-term ARM observations at the NSA ACRF site. Based on these retrieval results, we are studying seasonal and interannual variations of arctic mixed-phase cloud macro- and micro-physical properties.

Download or read book Studies of Aerosol and Cloud Properties Using Synergy of Lidar and Radar Measurements written by Dongxiang Wang and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dotyczy: optical properties, cloud, aerosol, atmospheric boundary layer, microwave radiometer, Lidar, właściwości optycznych, chmurowego, aerozolu, Atmosferyczna warstwa graniczna, radiometru mikrofalowego, chmurowego radar, Lidaru.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Basic Comparison of Lidar and Radar for Remote Sensing of Clouds written by Vernon Ellsworth Derr and published by . This book was released on 1978 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Both radar and lidar have proved valuable in studying cloud microphysics and dynamics. Because of the large difference in wavelength, the two techniques have differing penetration capabilities and detection sensitivities. A "system-free" comparison of radar and lidar for several missions and many cloud types is presented to permit the optimum choice of technique for field studies of cloud formation, development, and precipitation.

Download or read book Investigation on Cirrus Clouds by the Cloud aerosol Lidar and Infrared Pathfinder Satellite Observation Data written by Jiang Zhu and published by . This book was released on 2011 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding and describing the role of clouds in the climate system need intensive and extensive research on cloud properties. The albedo and greenhouse effects of clouds and their relations with the physical properties of clouds are analyzed. Cloud-top height and ice water content are key factors in impacting the longwave and shortwave radiation, respectively. Lidar and infrared radiometer measurement technologies are introduced. Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) level I Lidar profile, level 2 cloud layer, and level 2 Lidar/IIR track products are briefly reviewed. The algorithms for identification of cirrus clouds, Linear Depolarization Ratio (LDR), and effective diameter are presented. An average LDR profile is calculated by using the sum of total attenuated backscattering profiles and the sum of perpendicular attenuated backscattering profiles. A weight-average method is applied to calculate the average LDR. A split-window method is applied to estimate the effective diameters of clouds. A set of bulk ice crystal models and a radiative transfer model are applied to produce a look-up table that includes the radiative transfer simulation results. The macro-physical properties of cirrus clouds are analyzed. The frequency of occurrence of cirrus clouds varies with latitude, and strongly relates to the atmospheric circulation. Cirrus clouds are few in high-pressure zones and abundant where seasonal monsoonal circulation occurs. Cloud-top height decreases with increasing latitude. Cloud-top temperature is lower in the tropical regions than in the midlatutude and the polar regions. The measured cloud thickness shows a great diurnal variation. CALIPSO lidar detects more cirrus clouds than satellite-based passive measurement. LDR values of cirrus clouds vary with latitude and location, and are higher during nighttime than during daytime. The 0.32 and 0.37 annual average LDRs derived by nadir and off-nadir measurements, respectively, indicate that substantial amounts of horizontal orientated ice crystals exist in cirrus clouds. The global distribution of effective diameter of cirrus clouds varies with latitude and season, and the effective diameter has relationship with the LDR.

Download or read book Earth Resources written by and published by . This book was released on 1983 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of Cloud Height written by Eugene Y. Moroz and published by . This book was released on 1975 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new evaluation of a ruby lidar ceilometer was performed at AFCRL as part of a program to evaluate the applicability of lasers to determine cloud height for airfield use. Comparitive measurements of cloud height were made with a standard Air Force rotating beam ceilometer (RBC). Examination of the test results shows the lidar indicates an accurate presentation of cloud structure. The RBC cloud return is affected by its geometry and by multiple scatter in the cloud. As a result, the measurement is not a true representation of cloud structure. These effects also bias the RBC to indicate higher cloud heights. However, the difference in cloud heights as measured by the two systems is not significant. Therefore, it is concluded that the lidar is a superior cloud height measuring device and both techniques provide operationally useful indications of cloud height. (Author).

Download or read book A Comparison Study Using the Goes Sounder Cloud Top Pressure Product and Cloud Lidar and Radar written by James A. Hawkinson and published by . This book was released on 2003 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Using Radar Lidar and Radiometer Data from NSA and SHEBA to Quantify Cloud Property Effects on the Surface Heat Budget in the Arctic written by Janet Intrieri and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cloud and radiation data from two distinctly different Arctic areas are analyzed to study the differences between coastal Alaskan and open Arctic Ocean region clouds and their respective influence on the surface radiation budget. The cloud and radiation datasets were obtained from (1) the DOE North Slope of Alaska (NSA) facility in the coastal town of Barrow, Alaska, and (2) the SHEBA field program, which was conducted from an icebreaker frozen in, and drifting with, the sea-ice for one year in the Western Arctic Ocean. Radar, lidar, radiometer, and sounding measurements from both locations were used to produce annual cycles of cloud occurrence and height, atmospheric temperature and humidity, surface longwave and shortwave broadband fluxes, surface albedo, and cloud radiative forcing. In general, both regions revealed a similar annual trend of cloud occurrence fraction with minimum values in winter (60-75%) and maximum values during spring, summer and fall (80-90%). However, the annual average cloud occurrence fraction for SHEBA (76%) was lower than the 6-year average cloud occurrence at NSA (92%). Both Arctic areas also showed similar annual cycle trends of cloud forcing with clouds warming the surface through most of the year and a period of surface cooling during the summer, when cloud shading effects overwhelm cloud greenhouse effects. The greatest difference between the two regions was observed in the magnitude of the cloud cooling effect (i.e., shortwave cloud forcing), which was significantly stronger at NSA and lasted for a longer period of time than at SHEBA. This is predominantly due to the longer and stronger melt season at NSA (i.e., albedo values that are much lower coupled with Sun angles that are somewhat higher) than the melt season observed over the ice pack at SHEBA. Longwave cloud forcing values were comparable between the two sites indicating a general similarity in cloudiness and atmospheric temperature and humidity structure between the two regions.

Download or read book Cirrus Cloud Microphysical Property Retrieval Using Lidar and Radar Measurements written by Zhien Wang and published by . This book was released on 2002 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cloud Effective Particle Size and Water Content Profile Retrievals Using Combined Lidar and Radar Observations written by and published by . This book was released on 2000 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbulence and Life Time Studies of Shallow Cumuli Clouds Using Scanning Cloud Radar Observations written by Paloma Borque and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Les nuages jouent un rôle critique dans le système climatique terrestre. L'étude des éléments de nuage lors de leur transition à travers diverses étapes de leur cycle de vie est donc d'une importance vitale. Le suivi des nuages à l'aide des radars de nuage à balayage peut aider à documenter l'évolution temporelle des propriétés de nuages bien avant la formation des grosses gouttes (le premier écho radar). Un nouvel algorithme d'identification et de suivi (CITA) est développé pour faire le suivi des éléments de nuages à partir d'observations verticales dans le sens des vents d'une population the cumulus peu profonds (avec et sans précipitation). Basé sur le CITA, l'évolution temporelle des propriétés des éléments de nuage (nombre, taille, réflectivité maximale) et leur connexion avec l'environnement peuvent être analysées. La turbulence affecte fortement le cycle de vie des nuages, surtout leurs stages de formation et de dissipation. Des observations coïncidentes de profilage d'un lidar Doppler et de radars sont utilisées pour estimer la vitesse de dissipation de l'énergie turbulente ([epsilon]) à partir de différentes sources de données: vitesse Doppler radar, vitesse Doppler lidar et les mesures de largeur spectrale de radar Doppler. Les évaluations de vitesse de dissipation de turbulence basées sur les mesures de vitesse Doppler sont consistantes lors des conditions de bruine mais aussi en leur absence, suggérant que la vitesse de dissipation de tourbillon peut être estimée à travers la couche de nuage sans contrainte quant à la présence de précipitation. Par contre, l'utilisation des séries temporelles de vélocité Doppler radar et lidar pour mesurer [epsilon] requierent de longues périodes (~20 minutes) d'observations continues. Étant donné la courte durée de vie des nuages cumulus (3-10 minutes selon les radars nuages à profilage) ces techniques sont surtout limitées au nuages stratiformes. Cela motive le travail exploratoire sur une nouvelle technique basée sur les observations à double longueur d'onde pour estimer la vitesse de dissipation des tourbillons de nuages de courte durée." --

Download or read book An Analysis of Cloud Property Retrieval Using Infrared Sounder Data written by Bruce Anthony Wielicki and published by . This book was released on 1980 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book DC 8 Scanning Lidar Characterization of Aircraft Contrails and Cirrus Clouds written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-16 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Subsonic Assessment (SASS) element of the overall Atmospheric Effects of Aviation Project (AEAP) was initiated by NASA to assess the atmospheric impact of subsonic aircraft. SRI was awarded a project to develop and test a scanning backscatter lidar for installation on the NASA DC-8 (year 1), participate in the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) field program (year 2), and conduct a comprehensive analysis of field data (year 3). A scanning mirror pod attached to the DC-8 aircraft provides for scanning lidar observations ahead of the DC-8 and fixed-angle upward or downward observations. The lidar system installed within the DC-8 transmits 275 MJ at 1.06 gm wavelength or about 130 mJ at 1.06 and 0.53 gm simultaneously. Range-resolved aerosol backscatter is displayed in real time in terms of cloud/contrail spatial distributions. The objectives of the project are to map contrail/cloud vertical distributions ahead of DC-8; provide DC-8 guidance into enhanced scattering layers; document DC-8 flight path intersection of contrail and cloud geometries (in-situ measurement positions relative to cloud/contrail shape and an extension of in-situ measurements into the vertical -- integrated contrail/cloud properties); analyze contrail/cloud radiative properties with LIRAD (combined lidar and radiometry) technique; evaluate mean particle sizes of aircraft emissions from two-wavelength observations; study contrail/cloud interactions, diffusion, and mass decay/growth; and make observations in the near-field of aircraft engine emissions. The scanning mirror pod may also provide a scanning capability for other remote sensing instruments. Nielsen, Norman B. and Uthe, Edward E. (Principal Investigator) Ames Research Center NASA-CR-201902, NAS 1.26:201902, SRI Project 6555 NCC2-885...

Download or read book Assessing the Performance of Several Modis Level 2 Cloud and Aerosol Products Against a Surface Based Polarization Cloud Lidar at Fairbanks AK written by Patrick Cobb and published by . This book was released on 2008 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Global Circulation Models (GCMs) currently suffer from inadequate cloud and aerosol parameterizations due to a shortage of information regarding how clouds and aerosols are globally distributed in space and time. Although surface and airborne instruments can offer reliable cloud and aerosol measurements, such methods are expensive, and their scope is rather limited. Satellite instruments, such as the MODerate resolution Imaging Spectroradiometer (MODIS), may provide an alternative. MODIS measures spectral radiance in thirty-six discreet spectral bands. A variety of cloud and aerosol properties are derived at the pixel scale from these measurements using algorithms developed from radiative transfer theory. A comprehensive validation campaign is underway to assess the quality of these data in hopes that it can be assimilated into the GCMs. This thesis provides one such study comparing the MODIS cloud mask, cloud top properties, cloud thermodynamic phase and aerosol type with overlapping surface data from a polarization cloud lidar at Fairbanks, AK. Most of the sample is comprised of cirrus clouds, which are difficult to detect with satellites. Results are mixed, but are generally consistent with past studies. The MODIS products are fairly dependable, but the algorithms could be improved, especially over the polar regions"--Leaf iii.

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Cirrus Clouds from Ground based Remote Sensing Using the Synergy of Lidar and Multi spectral Infrared Radiometry written by Friederike Hemmer and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a broad consensus that cirrus clouds strongly influence the climate of the Earth. However, their net radiative effect is still poorly quantified nowadays due to an insufficient knowledge of their microphysical properties. This thesis aims to improve our understanding of the complex microphysics of this cloud type mainly composed of irregularly shaped ice crystals and thereby improve estimates of the ice water content (IWC). For this purpose, we developed an algorithm to retrieve vertical profiles of the IWC of cirrus clouds. The methodology combines the measurements of a ground-based lidar and a thermal infrared (TIR) radiometer in a common optimal estimation framework. It follows three steps: (1) An algorithm to retrieve the vertically integrated amount of ice (ice water path, IWP) from the passive TIR measurements is established. (2) The information about the vertical distribution of the IWC inside the cloud is obtained from the active lidar measurements. These retrievals strongly depend on the backscatter-to-extinction ratio of the ice crystals which is obtained from a bulk ice microphysical model. The scattering phase function of this model used to define the backscatter-to-extinction ratio assumes a flat ending without backscattering peak. We show that this assumption is unrealistic since it results in the retrieval of IWC profiles which are inconsistent with the TIR measurements. (3) Consequently, both types of measurements are combined in a synergistic algorithm allowing to estimate together with the IWC profiles a correction factor for the phase function in backscattering direction. Finally, the retrieval results and associated hypotheses are discussed.