Sample records for cloud radar lidar

  1. Cloud parameters from IR lidar and other instruments - CLARET design and preliminary results. [Cloud Lidar And Radar Exploratory Test

    NASA Technical Reports Server (NTRS)

    Eberhard, Wynn L.; Uttal, Taneil; Intrieri, Janet M.; Willis, Ron J.

    1990-01-01

    The paper describes the objectives and experimental design of the Cloud Lidar and Radar Exploratory Test (CLARET) project. Early results for some of the objectives are presented. Particular attention is given to polarization of IR lidar backscatter, cirrus size distribution, and cirrus emissivity. CLARET has produced a good data set for cloud/radiation research and evaluation of remote sensing methods and technologies.

  2. A variational scheme for retrieving ice cloud properties from combined radar, lidar and infrared radiometer

    E-print Network

    Reading, University of

    of ground-based or spaceborne radar, lidar and infrared radiometer. The forward model includes effectsA variational scheme for retrieving ice cloud properties from combined radar, lidar and infrared such as non-Rayleigh scattering by the radar and molecular and multiple scattering by the lidar. By rigorous

  3. A variational scheme for retrieving ice cloud properties from combined radar, lidar, and infrared

    E-print Network

    Delanoë, Julien

    of ground-based or spaceborne radar, lidar and infrared radiometer. The forward model includes effectsA variational scheme for retrieving ice cloud properties from combined radar, lidar, and infrared such as non-Rayleigh scattering by the radar and molecular and multiple scattering by the lidar. By rigorous

  4. Analysis of radar and lidar returns from clouds: Implications for the proposed Earth Radiation Mission

    E-print Network

    Hogan, Robin

    Analysis of radar and lidar returns from clouds: Implications for the proposed Earth Radiation 1999, a near­continuous dataset of observations by cloud radar, lidar ceilometer and drop to the proposed ESA Earth Radiation Mission, and in this study we examine the frequency distribution of radar

  5. Facilitating cloud radar and lidar algorithms: the Cloudnet Instrument Synergy/Target Categorization product

    E-print Network

    Hogan, Robin

    Facilitating cloud radar and lidar algorithms: the Cloudnet Instrument Synergy recognition of the usefulness of cloud radar for evaluating numerous aspects of the representation of clouds, UK. E­mail: r.j.hogan@reading.ac.uk. 1 http://www.met.rdg.ac.uk/radar/cloudnet/ 2 http

  6. Ground-Based Lidar and Radar Remote Sensing of Tropical Cirrus Clouds at Nauru Island: Cloud Statistics and Radiative Impacts

    SciTech Connect

    Comstock, Jennifer M.; Ackerman, Thomas P.; Mace, Gerald G.

    2002-12-12

    Ground based active and passive remote sensing instrumentation are combined to derive radiative and macrophysical properties of tropical cirrus clouds. Eight months of cirrus observations at the Department of Energy Atmospheric Radiation Measurement site located on Nauru Island provide independent retrieval of cloud height and visible optical depth using lidar and radar techniques. Comparisons reveal the millimeter cloud radar does not detect 13% of cirrus clouds with a cloud base higher than 15 km that are detected by the lidar. Lidar and radar cloud heights demonstrate good agreement when the cloud lies below 15 km. Radar and lidar retrievals of visible optical depth also compare well for all but the optically thinnest clouds. Cloud occurrence at Nauru as measured by lidar, reveal clear sky conditions occur on average 40%, low clouds 16%, and high clouds 44% of the time. Analysis of observed cirrus macrophysical and radiative properties suggests that two different types of cirrus exist in the tropical western Pacific: high, thin, laminar cirrus with cloud base higher than 15 km, and lower, physically thicker, more structured cirrus clouds. Differences in cirrus types are likely linked to their formation mechanisms. Radiosonde profiles of temperature and equivalent potential temperature near the tropical tropopause show a clear transition between neutrally stable and stable air at ~15 km, which may also explain the presence of two distinct cirrus types. Radiative heating rate and cloud forcing calculations for specific cirrus cases reveal the impact of tropical cirrus clouds on the earth?s radiation budget.

  7. A method for determining cirrus cloud particle sizes using lidar and radar backscatter technique

    Microsoft Academic Search

    Janet M. Intrieri; Graeme L. Stephens; Wynn L. Eberhard; Taneil Uttal

    1993-01-01

    A method to determine cirrus cloud effective radii remotely using lidar and radar backscatter data is presented. The difference in backscattered returns from instruments widely separated in wavelength holds information on the characteristic sizes of the scatters. The method compares theoretically expected backscatter coefficients to observed backscatter returns from NOAA's 3.2-cm and 8.6-mm radars and the 10.6-[mu]m lidar. Measurements were

  8. On the use of IR lidar and K(sub a)-band radar for observing cirrus clouds

    NASA Technical Reports Server (NTRS)

    Eberhard, Wynn L.; Hardesty, R. Michael; Kropfli, Robert A.

    1990-01-01

    Advances in lidar and radar technology have potential for providing new and better information on climate significant parameters of cirrus. Consequently, the NOAA Wave Propagation Lab. is commencing CLARET (Cloud Lidar And Radar Exploratory Test) to evaluate the promise of these new capabilities. Parameters under study include cloud particle size distribution, height of cloud bases, tops, and multiple layers, and cloud dynamics revealed through measurement of vertical motions. The first phase of CLARET is planned for Sept. 1989. The CO2 coherent Doppler lidar and the sensitive K sub a band radar hold promise for providing valuable information on cirrus that is beyond the grasp of current visible lidars.

  9. Comparison of Airborne In Situ, Airborne RadarLidar, and Spaceborne RadarLidar Retrievals of Polar Ice Cloud Properties Sampled during the POLARCAT Campaign

    E-print Network

    Protat, Alain

    Comparison of Airborne In Situ, Airborne Radar­Lidar, and Spaceborne Radar­Lidar Retrievals-Aerosol-Water-Radiation Interactions (ICARE) center's radar­lidar project (DARDAR). 1. Introduction Spaceborne radar and lidar on board; Delanoe¨ et al. 2011). The combination of spaceborne radar and lidar remains the most accurate technique

  10. Synergetic radar and lidar algorithm for the retrieval of radiative and microphysical properties in ice clouds

    NASA Astrophysics Data System (ADS)

    Tinel, Claire; Testud, Jacques; Protat, Alain; Pelon, Jacques R.

    2003-04-01

    To appreciate the radiative impact of clouds in the dynamics of the global atmosphere, it is important to deploy from space, from aircraft, or from ground, instruments able to describe the cloud layering and to document the cloud characteristics (namely liquid and/or ice water content, and the effective particle radius). In the framework of EarthCARE (ESA), that plans to associate a cloud radar and a lidar on the same spatial platform, RALI (RAdar-LIdar) airborne system is an interesting demonstrator. RALI combines the 95 GHz radar of the CETP and the 0.5 ?m wavelength backscattering lidar of the SA. In order to derive the radiative and microphysical properties of clouds, a synergetic algorithm has been developed. It combines the apparent backscatter coefficient, ?a, from the lidar and the apparent reflectivity, Za, from the radar to infer properties of the particle size distribution. The principle of this algorithm is to apply in parallel the Hitschfeld-Bordan algorithm to the radar and the Klett algorithm to the lidar. Taken separately, these two algorithms are unstable, but by considering a mutual constraint, it is shown that a stable solution can be established. This solution formulates the retrieval of the true reflectivity and backscattering coefficient, to access microphysical and radiative parameters of clouds. This algorithm allows also to retrieve the variable N0* parameter, which is a normalization parameter of the particle size distribution. This synergetic algorithm has been tested with simulated cases, and results of the algorithm applied on real data are validated by microphysical in-situ measurements.

  11. Toward a quantitative characterization of heterogeneous ice formation with lidar/radar: Comparison of CALIPSO/CloudSat with ground-based observations

    NASA Astrophysics Data System (ADS)

    Bühl, J.; Ansmann, A.; Seifert, P.; Baars, H.; Engelmann, R.

    2013-08-01

    We analyze and compare the different sensitivities of aerosol/cloud lidar and 35-GHz cloud radar to detect ice formation in midlevel clouds in order to harmonize mixed phase cloud observations performed with lidar and radar. We found good agreement between spaceborne Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO)/CloudSat and ground-based lidar/radar observations at Leipzig, Germany. However, large differences were found to a previous study with an 11-year cloud statistics solely based on lidar observations which is caused by significantly higher sensitivity of the cloud radar to detect ice crystals. By introducing a lidar detection threshold for the ice water content of 10-6kgm-3, we find that lidar and radar cloud statistics become increasingly similar.

  12. First simultaneous and common volume observations of noctilucent clouds and polar mesosphere summer echoes by lidar and radar

    Microsoft Academic Search

    V. Nussbaumer; K. H. Fricke; M. Langer; W. Singer; U. von Zahn

    1996-01-01

    We present the results of first simultaneous and common volume observations of noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE) by two ground-based lidars and one VHF radar. The measurements were performed at the ALOMAR facility (69°N, 16°E) during the time period July 23 through August 18, 1994. Throughout this period, NLC layers were observed by the lidars on

  13. Comparison of cloud boundaries measured with 8.6 mm radar and 10.6 micrometer lidar

    NASA Technical Reports Server (NTRS)

    Uttal, Taneil; Intrieri, Janet M.

    1993-01-01

    One of the most basic cloud properties is location; the height of cloud base and the height of cloud top. The glossary of meteorology defines cloud base (top) as follows: 'For a given cloud or cloud layer, that lowest (highest) level in the atmosphere at which the air contains a perceptible quantity of cloud particles.' Our studies show that for a 8.66 mm radar, and a 10.6 micrometer lidar, the level at which cloud hydrometers become 'perceptible' can vary significantly as a function of the different wavelengths, powers, beamwidths and sampling rates of the two remote sensors.

  14. Using Radar, Lidar, and Radiometer measurements to Classify Cloud Type and Study Middle-Level Cloud Properties

    SciTech Connect

    Wang, Zhien

    2010-06-29

    The project is mainly focused on the characterization of cloud macrophysical and microphysical properties, especially for mixed-phased clouds and middle level ice clouds by combining radar, lidar, and radiometer measurements available from the ACRF sites. First, an advanced mixed-phase cloud retrieval algorithm will be developed to cover all mixed-phase clouds observed at the ACRF NSA site. The algorithm will be applied to the ACRF NSA observations to generate a long-term arctic mixed-phase cloud product for model validations and arctic mixed-phase cloud processes studies. To improve the representation of arctic mixed-phase clouds in GCMs, an advanced understanding of mixed-phase cloud processes is needed. By combining retrieved mixed-phase cloud microphysical properties with in situ data and large-scale meteorological data, the project aim to better understand the generations of ice crystals in supercooled water clouds, the maintenance mechanisms of the arctic mixed-phase clouds, and their connections with large-scale dynamics. The project will try to develop a new retrieval algorithm to study more complex mixed-phase clouds observed at the ACRF SGP site. Compared with optically thin ice clouds, optically thick middle level ice clouds are less studied because of limited available tools. The project will develop a new two wavelength radar technique for optically thick ice cloud study at SGP site by combining the MMCR with the W-band radar measurements. With this new algorithm, the SGP site will have a better capability to study all ice clouds. Another area of the proposal is to generate long-term cloud type classification product for the multiple ACRF sites. The cloud type classification product will not only facilitates the generation of the integrated cloud product by applying different retrieval algorithms to different types of clouds operationally, but will also support other research to better understand cloud properties and to validate model simulations. The ultimate goal is to improve our cloud classification algorithm into a VAP.

  15. Cirrus Clouds Optical, Microphysical and Radiative Properties Observed During Crystal-Face Experiment: I. A Radar-Lidar Retrieval System

    NASA Technical Reports Server (NTRS)

    Mitrescu, C.; Haynes, J. M.; Stephens, G. L.; Heymsfield, G. M.; McGill, M. J.

    2004-01-01

    A method of retrieving cloud microphysical properties using combined observations from both cloud radar and lidar is introduced. This retrieval makes use of an improvement to the traditional optimal estimation retrieval method, whereby a series of corrections are applied to the state vector during the search for an iterative solution. This allows faster convergence to a solution and is less processor intensive. The method is first applied to a synthetic cloud t o demonstrate its validity, and it is shown that the retrieval reliably reproduces vertical profiles of ice water content. The retrieval method is then applied to radar and lidar observations from the CRYSTAL-FACE experiment, and vertical profiles of ice crystal diameter, number concentration, and ice water content are retrieved for a cirrus cloud layers observed one day of that experiment. The validity of the relationship between visible extinction coefficient and radar reflectivity was examined. While synthetic tests showed such a functional relationship, the measured data only partially supported such a conclusion. This is due to errors in the forward model (as explained above) as well as errors in the data sets, including possible mismatch between lidar and radar profiles or errors in the optical depth. Empirical relationships between number concentrations and mean particle diameter were also examined. The results indicate that a distinct and robust relationship exists between these retrieved quantities and it is argued that such a relationship is more than an artifact of the retrieval process offering insight into the nature of the microphysical processes taking place in cirrus.

  16. Relationship between Ice Cloud Microphysics and Supersaturation from Spaceborne Cloud Radar, Lidar and Infrared Sounder

    NASA Astrophysics Data System (ADS)

    Tanaka, K.; Okamoto, H.; Sato, K.; Ishimoto, H.

    2014-12-01

    We examined the relationship between ice cloud microphysics retrieved from cloud radar on CloudSat and CALIOP on CALIPSO and super saturation inferred from AIRS on AQUA. Ice microphysics such as ice water content (IWC) and effective radius was estimated by CloudSat and CALIPSO data. Unique features of the algorithm is that it has been designed to use depolarization ratio from CALIOP addition to radar reflectivity factor from CloudSat and attenuated backscattering coefficient from CALIOP in order to take into account the variation of ice particle shapes and their orientations [Okamoto et al., 2010]. Water vapor density and temperature were retrieved with much finer resolution by the application of Ishimoto's algorithm [2009] compared with standard AIRS products where horizontal resolution is 45km. The algorithm allows retrievals of water vapor density and temperature every 13.5km in horizontal direction with 1km in vertical. The retrievals are carried out when there is no cloud with its cloud top pressure <200hPa. That is, it is possible to report water vapor information above low-level clouds. Then we sampled the amount of water vapor and temperature estimated from AIRS data to match the CloudSat and CALIPSO foot-print and the data were interpolated to have the same space and time resolution of the merged data sets of CloudSat and CALIPSO, i.e., 1.1km and 240m for horizontal and vertical resolutions. In the new AIRS products, ice super saturation often reached 150% while standard AIRS products showed less frequent super saturation. The ECMWF results generally showed smaller fraction of ice super saturation compared with the new AIRS products. In order to quantitatively compare the water vapor amount and retrieved IWC, we estimated the excess of water amount respect to ice saturation by using ice super saturation. The occurrences of ice clouds inferred from CloudSat and CALIOP agreed with the occurrences of ice-supersaturation reported in the new AIRS products. The retrieved IWC were smaller compared with the estimated IWC from the new AIRS products. Similar analyses with ECMWF showed smaller estimated IWC compared with the values in the new products.

  17. Vertical Cloud Climatology During TC4 Derived from High-Altitude Aircraft Merged Lidar and Radar Profiles

    NASA Technical Reports Server (NTRS)

    Hlavka, Dennis; Tian, Lin; Hart, William; Li, Lihua; McGill, Matthew; Heymsfield, Gerald

    2009-01-01

    Aircraft lidar works by shooting laser pulses toward the earth and recording the return time and intensity of any of the light returning to the aircraft after scattering off atmospheric particles and/or the Earth s surface. The scattered light signatures can be analyzed to tell the exact location of cloud and aerosol layers and, with the aid of a few optical assumptions, can be analyzed to retrieve estimates of optical properties such as atmospheric transparency. Radar works in a similar fashion except it sends pulses toward earth at a much larger wavelength than lidar. Radar records the return time and intensity of cloud or rain reflection returning to the aircraft. Lidar can measure scatter from optically thin cirrus and aerosol layers whose particles are too small for the radar to detect. Radar can provide reflection profiles through thick cloud layers of larger particles that lidar cannot penetrate. Only after merging the two instrument products can accurate measurements of the locations of all layers in the full atmospheric column be achieved. Accurate knowledge of the vertical distribution of clouds is important information for understanding the Earth/atmosphere radiative balance and for improving weather/climate forecast models. This paper describes one such merged data set developed from the Tropical Composition, Cloud and Climate Coupling (TC4) experiment based in Costa Rica in July-August 2007 using the nadir viewing Cloud Physics Lidar (CPL) and the Cloud Radar System (CRS) on board the NASA ER-2 aircraft. Statistics were developed concerning cloud probability through the atmospheric column and frequency of the number of cloud layers. These statistics were calculated for the full study area, four sub-regions, and over land compared to over ocean across all available flights. The results are valid for the TC4 experiment only, as preferred cloud patterns took priority during mission planning. The TC4 Study Area was a very cloudy region, with cloudy profiles occurring 94 percent of the time during the ER-2 flights. One to three cloud layers were common, with the average calculated at 2.03 layers per profile. The upper troposphere had a cloud frequency generally over 30%, reaching 42 percent near 13 km during the study. There were regional differences. The Caribbean was much clearer than the Pacific regions. Land had a much higher frequency of high clouds than ocean areas. One region just south and west of Panama had a high probability of clouds below 15 km altitude with the frequency never dropping below 25% and reaching a maximum of 60% at 11-13 km altitude. These cloud statistics will help characterize the cloud volume for TC4 scientists as they try to understand the complexities of the tropical atmosphere.

  18. Facilitating cloud radar and lidar algorithms: the Cloudnet Instrument Synergy/Target Categorization product

    E-print Network

    Hogan, Robin

    estimates of their associated error. Instrument sensitivity: Knowledge of the minimum de- tectable signal of the radar allows one to take account of clouds that may not be detected in comparisons with a model. Data quality flags: These inform the user when signals are contaminated by ground clutter, unknown radar atten

  19. Independent Evaluation of the Ability of Spaceborne Radar and Lidar to Retrieve the Microphysical and Radiative Properties of Ice Clouds

    E-print Network

    Reading, University of

    Independent Evaluation of the Ability of Spaceborne Radar and Lidar to Retrieve the Microphysical) estimated that spaceborne 94-GHz radar should be able to retrieve ice water content (IWC) to within a factor 16 March 2005) ABSTRACT The combination of radar and lidar in space offers the unique potential

  20. Mapping tropical forest biomass with radar and spaceborne LiDAR: overcoming problems of high biomass and persistent cloud

    NASA Astrophysics Data System (ADS)

    Mitchard, E. T. A.; Saatchi, S. S.; White, L. J. T.; Abernethy, K. A.; Jeffery, K. J.; Lewis, S. L.; Collins, M.; Lefsky, M. A.; Leal, M. E.; Woodhouse, I. H.; Meir, P.

    2011-08-01

    Spatially-explicit maps of aboveground biomass are essential for calculating the losses and gains in forest carbon at a regional to national level. The production of such maps across wide areas will become increasingly necessary as international efforts to protect primary forests, such as the REDD+ (Reducing Emissions from Deforestation and forest Degradation) mechanism, come into effect, alongside their use for management and research more generally. However, mapping biomass over high-biomass tropical forest is challenging as (1) direct regressions with optical and radar data saturate, (2) much of the tropics is persistently cloud-covered, reducing the availability of optical data, (3) many regions include steep topography, making the use of radar data complex, (4) while LiDAR data does not suffer from saturation, expensive aircraft-derived data are necessary for complete coverage. We present a solution to the problems, using a combination of terrain-corrected L-band radar data (ALOS PALSAR), spaceborne LiDAR data (ICESat GLAS) and ground-based data. We map Gabon's Lopé National Park (5000 km2) because it includes a range of vegetation types from savanna to closed-canopy tropical forest, is topographically complex, has no recent cloud-free high-resolution optical data, and the dense forest is above the saturation point for radar. Our 100 m resolution biomass map is derived from fusing spaceborne LiDAR (7142 ICESat GLAS footprints), 96 ground-based plots (average size 0.8 ha) and an unsupervised classification of terrain-corrected ALOS PALSAR radar data, from which we derive the aboveground biomass stocks of the park to be 78 Tg C (173 Mg C ha-1). This value is consistent with our field data average of 181 Mg C ha-1, from the field plots measured in 2009 covering a total of 78 ha, and which are independent as they were not used for the GLAS-biomass estimation. We estimate an uncertainty of ± 25 % on our carbon stock value for the park. This error term includes uncertainties resulting from the use of a generic tropical allometric equation, the use of GLAS data to estimate Lorey's height, and the necessity of separating the landscape into distinct classes. As there is currently no spaceborne LiDAR satellite in operation (GLAS data is available for 2003-2007 only), this methodology is not suitable for change-detection. This research underlines the need for new satellite LiDAR data to provide the potential for biomass-change estimates, although this need will not be met before 2015.

  1. Vertical cloud properties in the tropical western Pacific Ocean: Validation of the CCSR/NIES/FRCGC GCM by shipborne radar and lidar

    NASA Astrophysics Data System (ADS)

    Okamoto, Hajime; Nishizawa, Tomoaki; Takemura, Toshihiko; Sato, Kaori; Kumagai, Hiroshi; Ohno, Yuichi; Sugimoto, Nobuo; Shimizu, Atsushi; Matsui, Ichiro; Nakajima, Teruyuki

    2008-12-01

    This study examined the vertical cloud structure over the tropical western Pacific Ocean using 95-GHz radar and lidar data observed from September to December 2001 during the MR01-K05 cruise of the research vessel Mirai. The cloud vertical structure was homogeneous between 6 and 10 km, and the maximum cloud occurrence was 20% and located at 12 km. The mean precipitation occurrence was 11.5% at 1 km. The cloud fraction, radar reflectivity factor, and lidar backscattering coefficient were simulated along the Mirai cruise track using the output from the Center for Climate System Research, University of Tokyo; National Institute for Environmental Studies; and Frontier Research Center for Global Change (CCSR/NIES/FRCGC) general circulation model (GCM). The original output showed the maximum cloud fraction at 15 km; however, after considering attenuation and the minimum sensitivity of the radar, the maximum shifted to 12 km. The model overestimated the cloud fraction above 8 km, with the simulated fraction more than twice as large as the observed fraction. The model overpredicted the frequency of deep convection reaching the upper atmosphere above 12 km. Further, it overestimated precipitation frequency. Simulated radar reflectivity was underestimated throughout the entire altitude range, whereas simulated and observed lidar backscattering were in good agreement above 12 km with subgrid-scale treatment. The ice effective radius of 40 ?m and ice water content were reasonable in thin clouds, but the radius was underestimated in other regions. The simulated liquid water content was overestimated.

  2. Characterization of ice cloud properties obtained by shipborne radar/lidar over the tropical western Pacific Ocean for evaluation of an atmospheric general circulation model

    NASA Astrophysics Data System (ADS)

    Sato, Kaori; Okamoto, Hajime; Takemura, Toshihiko; Kumagai, Hiroshi; Sugimoto, Nobuo

    2010-08-01

    This study analyzed 95-GHz radar/lidar data collected from the R/V Mirai over the tropical western Pacific to characterize the vertical distribution of ice cloud effective radius reff, ice water content IWC, and in-cloud vertical velocity of the region in conjunction with weather regimes classified by International Satellite Cloud Climatology Project (ISCCP) cluster analysis. Ice clouds observed from the Mirai were roughly consistent with the ISCCP weather regimes; more convectively active regimes had larger amounts of high cloud consisting of deeper cloud with larger ice water path (IWP) and precipitating ice fraction. Ice cloud microphysics of the Center for Climate System Research, National Institute for Environmental Studies, Frontier Research Center for Global Change atmospheric general circulation model (AGCM) was then evaluated using the radar-lidar simulator and ISCCP weather regimes for comparison of the statistics at different scales. The model tended to produce a high cloud fraction that was two times larger in the cirrus regimes but 50% lower in the deepest convective regime. The simulated IWP could only weakly reproduce the observed variety and generally underestimated the observed values despite the weather regimes. Cutoff in the simulated grid mean IWC around 0.1 g-3 was too small, especially above 11 km. The AGCM successfully predicted the observed frequency distribution for reff above 11 km, but produced large overestimation in the peak value below 11 km due to the excessively large fraction of reff ˜100 ?m. Establishing a cutoff for cloud ice at reff > 120 ?m was found to be quite reasonable, although it would miss some of the larger particles that were observed.

  3. The Ability of MM5 to Simulate Ice Clouds: Systematic Comparison between Simulated and Measured Fluxes and Lidar/Radar Profiles at SIRTA Atmospheric Observatory

    SciTech Connect

    Chiriaco, M.; Vautard, R.; Chepfer, H.; Haeffelin, M.; Wanherdrick, Y.; Morille, Y.; Protat, A.; Dudhia, J.

    2005-03-18

    Ice clouds play a major role in the radiative energy budget of the Earth-atmosphere system (Liou 1986). Their radiative effect is governed primarily by the equilibrium between their albedo and greenhouse effects. Both macrophysical and microphysical properties of ice clouds regulate this equilibrium. For quantifying the effect of these clouds onto climate and weather systems, they must be properly characterized in atmospheric models. In this paper we use remote-sensing measurements from the SIRTA ground based atmospheric observatory (Site Instrumental de Recherche par Teledetection Atmospherique, http://sirta.lmd.polytechnique.fr). Lidar and radar observations taken over 18 months are used, in order to gain statistical confidence in the model evaluation. Along this period of time, 62 days are selected for study because they contain parts of ice clouds. We use the ''model to observations'' approach by simulating lidar and radar signals from MM5 outputs. Other more classical variables such as shortwave and longwave radiative fluxes are also used. Four microphysical schemes, among which that proposed by Reisner et al. (1998) with original or modified parameterizations of particle terminal fall velocities (Zurovac-Jevtic and Zhang 2003, Heymsfield and Donner 1990), and the simplified Dudhia (1989) scheme are evaluated in this study.

  4. Mapping tropical forest biomass with radar and spaceborne LiDAR in Lopé National Park, Gabon: overcoming problems of high biomass and persistent cloud

    NASA Astrophysics Data System (ADS)

    Mitchard, E. T. A.; Saatchi, S. S.; White, L. J. T.; Abernethy, K. A.; Jeffery, K. J.; Lewis, S. L.; Collins, M.; Lefsky, M. A.; Leal, M. E.; Woodhouse, I. H.; Meir, P.

    2012-01-01

    Spatially-explicit maps of aboveground biomass are essential for calculating the losses and gains in forest carbon at a regional to national level. The production of such maps across wide areas will become increasingly necessary as international efforts to protect primary forests, such as the REDD+ (Reducing Emissions from Deforestation and forest Degradation) mechanism, come into effect, alongside their use for management and research more generally. However, mapping biomass over high-biomass tropical forest is challenging as (1) direct regressions with optical and radar data saturate, (2) much of the tropics is persistently cloud-covered, reducing the availability of optical data, (3) many regions include steep topography, making the use of radar data complex, (5) while LiDAR data does not suffer from saturation, expensive aircraft-derived data are necessary for complete coverage. We present a solution to the problems, using a combination of terrain-corrected L-band radar data (ALOS PALSAR), spaceborne LiDAR data (ICESat GLAS) and ground-based data. We map Gabon's Lopé National Park (5000 km2) because it includes a range of vegetation types from savanna to closed-canopy tropical forest, is topographically complex, has no recent contiguous cloud-free high-resolution optical data, and the dense forest is above the saturation point for radar. Our 100 m resolution biomass map is derived from fusing spaceborne LiDAR (7142 ICESat GLAS footprints), 96 ground-based plots (average size 0.8 ha) and an unsupervised classification of terrain-corrected ALOS PALSAR radar data, from which we derive the aboveground biomass stocks of the park to be 78 Tg C (173 Mg C ha-1). This value is consistent with our field data average of 181 Mg C ha-1, from the field plots measured in 2009 covering a total of 78 ha, and which are independent as they were not used for the GLAS-biomass estimation. We estimate an uncertainty of ±25% on our carbon stock value for the park. This error term includes uncertainties resulting from the use of a generic tropical allometric equation, the use of GLAS data to estimate Lorey's height, and the necessity of separating the landscape into distinct classes. As there is currently no spaceborne LiDAR satellite in operation (GLAS data is available for 2003-2009 only), this methodology is not suitable for change-detection. This research underlines the need for new satellite LiDAR data to provide the potential for biomass-change estimates, although this need will not be met before 2015.

  5. Wyoming Cloud Lidar: instrument description and applications.

    PubMed

    Wang, Zhien; Wechsler, Perry; Kuestner, William; French, Jeffrey; Rodi, Alfred; Glover, Brent; Burkhart, Matthew; Lukens, Donal

    2009-08-01

    The Wyoming Cloud Lidar (WCL), a compact two-channel elastic lidar, was designed to obtain cloud measurements together with the Wyoming Cloud Radar (WCR) on the University of Wyoming King Air and the National Science Foundation/National Center of Atmospheric Research C-130 aircraft. The WCL has been deployed in four field projects under a variety of atmospheric and cloud conditions during the last two years. Throughout these campaigns, it has exhibited the needed reliability for turn-key operation from aircraft. We provide here an overview of the instrument and examples to illustrate the measurements capability of the WCL. Although the WCL as a standalone instrument can provide unique measurements for cloud and boundary layer aerosol studies, the synergy of WCL and WCR measurements coupled with in situ sampling from an aircraft provide a significant step forward in our ability to observe and understand cloud microphysical property evolution. PMID:19654765

  6. A Radar Safety Device for Lidars Probing the Atmosphere

    NASA Technical Reports Server (NTRS)

    Alvarez, J. M.; Fuller, W. H., Jr.; Lawrence, R. M.

    1998-01-01

    Lasers have been used for important atmospheric research almost since their inception. Present day lidar systems continue this serious work and lasers are currently being used in increasingly sophisticated ways to expand our knowledge of atmospheric processes. Langley Research Center, for example, has been performing airborne and ground-based stratospheric volcanic-aerosol lidar measurements for the past 27 years and the University of Utah has been measuring cirrus cloud radiative properties with lidar for the past 20 years. Although the widespread use of lasers probing the atmosphere is too voluminous to cite in an extended abstract, one critical fact must be noted: atmospheric lidar measurements must increasingly be performed wherever they are needed and thus the problems associated with the operation of lidars and aircraft in the same airspace are becoming increasingly vexatious. The lidar community is quite sensitive to this issue and procedures such as the issuance of Notices to Airmen (NOTAMS), informing the FAA of lidar operations, and use of ground-based aircraft observers are already being widely utilized. Current measures, however, depend largely on pilots receiving the NOTAM and acting on it or approach control vectoring the aircraft away from the lidar site. Perhaps a better approach is to provide the lidar site with an autonomous capability to automatically interrupt laser operations while any aircraft is close-by. This abstract describes our efforts to develop and test an inexpensive radar system for use as an aircraft proximity warning and laser shut-down device during atmospheric lidar operations.

  7. Combined High Spectral Resolution Lidar and Radar Measurement of Drizzle

    NASA Astrophysics Data System (ADS)

    Eloranta, Edwin

    2015-04-01

    Marine stratus clouds are an important feature of the global climate system. Cloud lifetime is sensitive to drizzle rates. Drizzle not only removes water from the cloud but it's evaporation cools the sub-cloud layer acting to suppress convection. Accurate measurements of drizzle rates will improve our understanding of cloud maintenance. Simultaneous lidar measurements of extinction and radar backscatter allow determination of drizzle droplet particle size, liquid water content, fall velocity and water flux. However, drizzle measurements with conventional lidar are hampered by: 1)changes in the transmission of the output window caused by water accumulation on the lidar output window, 2)the difficulty of correcting the backscatter signal for atmospheric extinction and, 3)the effects of multiple scattering. High spectral resolution lidar avoids problems with window transmission and atmospheric attenuation because the backscatter is referenced to the known molecular scattering cross section at each point in the profile. Although multiple scattering degrades the direct measurement of extinction with the HSRL, it has little effect the HSRL measurement of backscatter cross section. We have developed an iterative solution that begins by estimating the extinction cross in drizzle using an assumed lidar ratio and the backscatter measurement. This is combined with the radar backscatter to make a first estimate of the particle size distribution. Mie scattering theory is then used to compute an improved lidar ratio for this particle size distribution and the new lidar ratio provides an improved extinction cross section. The calculation assumes a modified gamma distribution of sizes. The mode diameter of the distribution is fixed by the lidar-radar cross section ratio, while the width of the distribution is determined by matching the computed fall velocity of the drizzle with the observed radar Doppler velocity. The strengths and limitations of the this approach are examined using HSRL and millimeter radar acquired during the MAGIC deployment of the DOE ARM mobile facility on the 'Spirit Horizon' container ship. Marine stratus observations were acquired as the ship made repeated weekly trips between Long Beach CA and Honolulu, HI. This paper will compared derived precipitation rates with conventional rain gauge and distressed data. The sensitivity of the retrieval precipitation rates to assumptions will also be presented.

  8. CloudSat spaceborne 94 GHz radar bright bands in the melting layer: An attenuation-driven upside-down lidar analog

    Microsoft Academic Search

    Kenneth Sassen; Sergey Matrosov; James Campbell

    2007-01-01

    The CloudSat satellite supports a W-band (94 GHz) cloud profiling radar. At this 3.2 mm wavelength, ground-based measurements of rainfall associated with melting snowflakes do not show the radar reflectivity peak that is characteristic of bright band measurements at longer (Rayleigh scattering-dominated) wavelengths. Nonetheless, examination of downward-looking CloudSat returns in precipitation often indicate an obvious signal peak in the melting

  9. Use of cloud radar observations for model evaluation: A probabilistic approach

    E-print Network

    Jakob, Christian

    Diagnostics Center, National Oceanic and Atmospheric Administration Cooperative Institute for Research] The use of narrow-beam, ground-based active remote sensors (such as cloud radars and lidars) for long and active remote sensors, including millimeter wavelength cloud radars and lidars, that can be combined

  10. Arctic-Winter Climatology and Radiative Effects of Clouds and Aerosols Based on Lidar and Radar Measurements at PEARL

    E-print Network

    Eloranta, Edwin W.

    Measurements at PEARL T. Ayash, J.-P. Blanchet and E. W. Eloranta During the cold and dark Polar winter months Laboratory (PEARL) at Eureka, Nunavut by an Automated High Spectral Resolution Lidar (AHSRL

  11. Cloud detection by lidar extinction calculations

    NASA Technical Reports Server (NTRS)

    Lentz, W. J.

    1986-01-01

    A new lidar method of measuring cloud ceiling height using the Klett solution to the lidar equation was developed. This simple technique will find cloud ceiling height for clouds that rangefinder-like lidars cannot theoretically detect. In addition, the noise signals that do not correspond to clouds removed by using the convergence of the Klett solution to discriminate between signal changes and broader signal changes due to clouds. Clouds above rain or light fog can be detected without error, and it is possible to discriminate against haze layers by the magnitude of their maximum extinction.

  12. Millimeter Wave Cloud Radar (MMCR) Handbook

    SciTech Connect

    KB Widener; K Johnson

    2005-01-30

    The millimeter cloud radar (MMCR) systems probe the extent and composition of clouds at millimeter wavelengths. The MMCR is a zenith-pointing radar that operates at a frequency of 35 GHz. The main purpose of this radar is to determine cloud boundaries (e.g., cloud bottoms and tops). This radar will also report radar reflectivity (dBZ) of the atmosphere up to 20 km. The radar possesses a doppler capability that will allow the measurement of cloud constituent vertical velocities.

  13. An Initial Application of Polarization Lidar for Orographic Cloud Seeding Operations

    Microsoft Academic Search

    Kenneth Sassen

    1980-01-01

    Ground-based polarization lidar measurements have been obtained in conjunction with a commercial cloud seeding program to evaluate the potential of pulsed laser remote sensing techniques for increasing the effectiveness of orographic cloud seeding operations. The lidar measurements, supplemented by microwave radar cloud top and rawinsonde data, are shown to aid in the determination of seeding criteria. Our real-time seed, no-seed

  14. An Atmospheric Radiation Measurement Value-Added Product to Retrieve Optically Thin Cloud Visible Optical Depth using Micropulse Lidar

    SciTech Connect

    Lo, C; Comstock, JM; Flynn, C

    2006-10-01

    The purpose of the Micropulse Lidar (MPL) Cloud Optical Depth (MPLCOD) Value-Added Product (VAP) is to retrieve the visible (short-wave) cloud optical depth for optically thin clouds using MPL. The advantage of using the MPL to derive optical depth is that lidar is able to detect optically thin cloud layers that may not be detected by millimeter cloud radar or radiometric techniques. The disadvantage of using lidar to derive optical depth is that the lidar signal becomes attenuation limited when ? approaches 3 (this value can vary depending on instrument specifications). As a result, the lidar will not detect optically thin clouds if an optically thick cloud obstructs the lidar beam.

  15. Initial assessment of space-based lidar CALIOP aerosol and cloud layer structures through inter-comparison with a ground-based back-scattering lidar and CloudSat

    Microsoft Academic Search

    S.-W. Kim; S.-C. Yoon; E.-S. Chung; B.-J. Sohn; S. Berthier; J.-C. Raut; P. Chazette; F. Dulac

    2009-01-01

    This study presents results of the intercomparison of aerosol\\/cloud top and bottom heights obtained from a space-borne active sensor Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard CALIPSO, and the Cloud Profiling Radar (CPR) onboard CloudSat, and the space-borne passive sensor Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua, and ground-based 2-wavelenght polarization lidar system (532 and 1064 nm) at Seoul National

  16. Lidar and radar measurements of the melting layer: observations of dark and bright band phenomena

    NASA Astrophysics Data System (ADS)

    Di Girolamo, P.; Summa, D.; Cacciani, M.; Norton, E. G.; Peters, G.; Dufournet, Y.

    2012-05-01

    Multi-wavelength lidar measurements in the melting layer revealing the presence of dark and bright bands have been performed by the University of BASILicata Raman lidar system (BASIL) during a stratiform rain event. Simultaneously radar measurements have been also performed from the same site by the University of Hamburg cloud radar MIRA 36 (35.5 GHz), the University of Hamburg dual-polarization micro rain radar (24.15 GHz) and the University of Manchester UHF wind profiler (1.29 GHz). Measurements from BASIL and the radars are illustrated and discussed in this paper for a specific case study on 23 July 2007 during the Convective and Orographically-induced Precipitation Study (COPS). Simulations of the lidar dark and bright band based on the application of concentric/eccentric sphere Lorentz-Mie codes and a melting layer model are also provided. Lidar and radar measurements and model results are also compared with measurements from a disdrometer on ground and a two-dimensional cloud (2DC) probe on-board the ATR42 SAFIRE. Measurements and model results are found to confirm and support the conceptual microphysical/scattering model elaborated by Sassen et al. (2005).

  17. Cloud top remote sensing by airborne lidar

    NASA Technical Reports Server (NTRS)

    Spinhirne, J. D.; Hansen, M. Z.; Caudill, L. O.

    1982-01-01

    Observations of cloud top height, backscattering, and signal depolarization have been obtained by a lidar system operating onboard a high-altitude research aircraft. The transmitter for the cloud lidar system is a doubled Nd:YAG laser operating at 5 Hz. The system functions as a fully automated sensor under microprocessor control and operates from a nominal 19-km altitude. Measurements have been acquired over a wide variety of cloud cover in conjunction with passive visible and infrared measurements. Initial observation results are reported

  18. Cloud top remote sensing by airborne lidar.

    PubMed

    Spinhirne, J D; Hansen, M Z; Caudill, L O

    1982-05-01

    Observations of cloud top height, backscattering, and signal depolarization have been obtained by a lidar system operating onboard a high-altitude research aircraft. The transmitter for the cloud lidar system is a doubled Nd:YAG laser operating at 5 Hz. The system functions as a fully automated sensor under microprocessor control and operates from a nominal 19-km altitude. Measurements have been acquired over a wide variety of cloud cover in conjunction with passive visible and infrared measurements. Initial observation results are reported. PMID:20389897

  19. A Depolarisation Lidar Based Method for the Determination of Liquid-Cloud Microphysical Properties.

    NASA Astrophysics Data System (ADS)

    Donovan, D. P.; Klein Baltink, H.; Henzing, J. S.; De Roode, S. R.; Siebesma, P.

    2014-12-01

    The fact that polarisation lidars measure a multiple-scattering induced depolarisation signal in liquid clouds is well-known. The depolarisation signal depends on the lidar characteristics (e.g. wavelength and field-of-view) as well as the cloud properties (e.g. liquid water content (LWC) and cloud droplet number concentration (CDNC)). Previous efforts seeking to use depolarisation information in a quantitative manner to retrieve cloud properties have been undertaken with, arguably, limited practical success. In this work we present a retrieval procedure applicable to clouds with (quasi-)linear LWC profiles and (quasi-)constant CDNC in the cloud base region. Limiting the applicability of the procedure in this manner allows us to reduce the cloud variables to two parameters (namely liquid water content lapse-rate and the CDNC). This simplification, in turn, allows us to employ a robust optimal-estimation inversion using pre-computed look-up-tables produced using lidar Monte-Carlo multiple-scattering simulations. Here, we describe the theory behind the inversion procedure and apply it to simulated observations based on large-eddy simulation model output. The inversion procedure is then applied to actual depolarisation lidar data covering to a range of cases taken from the Cabauw measurement site in the central Netherlands. The lidar results were then used to predict the corresponding cloud-base region radar reflectivities. In non-drizzling condition, it was found that the lidar inversion results can be used to predict the observed radar reflectivities with an accuracy within the radar calibration uncertainty (2-3 dBZ). This result strongly supports the accuracy of the lidar inversion results. Results of a comparison between ground-based aerosol number concentration and lidar-derived CDNC are also presented. The results are seen to be consistent with previous studies based on aircraft-based in situ measurements.

  20. Beyond Radar Backscatter: Estimating Forest Structure and Biomass with Radar Interferometry and Lidar Remote Sensing

    NASA Astrophysics Data System (ADS)

    Lavalle, M.; Ahmed, R.

    2014-12-01

    Mapping forest structure and aboveground biomass globally is a major challenge that the remote sensing community has been facing for decades. Radar backscatter is sensitive to biomass only up to a certain amount (about 150 tons/ha at L-band and 300 tons/ha at P-band), whereas lidar remote sensing is strongly limited by poor spatial coverage. In recent years radar interferometry, including its extension to polarimetric radar interferometry (PolInSAR), has emerged as a new technique to overcome the limitations of radar backscatter. The idea of PolInSAR is to use jointly interferometric and polarimetric radar techniques to separate different scattering mechanisms and retrieve the vertical structure of forests. The advantage is to map ecosystem structure continuously over large areas and independently of cloud coverage. Experiments have shown that forest height - an important proxy for biomass - can be estimated using PolInSAR with accuracy between 15% and 20% at plot level. At AGU we will review the state-of-art of repeat-pass PolInSAR for biomass mapping, including its potential and limitations, and discuss how merging lidar data with PolInSAR data can be beneficial not only for product cross-validation but also for achieving better estimation of ecosystem properties over large areas. In particular, lidar data are expected to aid the inversion of PolInSAR models by providing (1) better identification of ground under the canopy, (2) approximate information of canopy structure in limited areas, and (3) maximum tree height useful for mapping PolInSAR temporal decorrelation. We will show our tree height and biomass maps using PolInSAR L-band JPL/UAVSAR data collected in tropical and temperate forests, and P-band ONERA/TROPISAR data acquired in French Guiana. LVIS lidar data will be used, as well as SRTM data, field measurements and inventory data to support our study. The use of two different radar frequencies and repeat-pass JPL UAVSAR data will offer also the opportunity to compare our results with the new airborne P-band ECOSAR and L-band DBSAR instruments developed at the NASA Goddard Space Flight Center.

  1. Micropulse Lidar Cloud Mask Value-Added Product Technical Report

    SciTech Connect

    Sivaraman, C; Comstock, J

    2011-07-25

    Lidar backscattered signal is a useful tool for identifying vertical cloud structure in the atmosphere in optically thin clouds. Cloud boundaries derived from lidar signals are a necessary input for popular ARM data products, such as the Active Remote Sensing of Clouds (ARSCL) product. An operational cloud boundary algorithm (Wang and Sassen 2001) has been implemented for use with the ARM Micropulse Lidar (MPL) systems. In addition to retrieving cloud boundaries above 500 m, the value-added product (VAP) named Micropulse Lidar Cloud Mask (MPLCMASK) applies lidar-specific corrections (i.e., range-square, background, deadtime, and overlap) as described in Campbell et al. (2002) to the measured backscattered lidar. Depolarization ratio is computed using the methodology developed by Flynn et al. (2007) for polarization-capable MPL systems. The cloud boundaries output from MPLCMASK will be the primary lidar cloud mask for input to the ARSCL product and will be applied to all MPL systems, including historical data sets.

  2. Radiative effects of supercooled water Summary. Supercooled liquid water layers are visible in lidar imagery as a strongly enhanced return followed by

    E-print Network

    Hogan, Robin

    by the resolutions of current forecast and climate models. These results suggest that a spaceborne lidar and radar-funded 1998 Cloud Lidar And Radar Experiment. Radar-lidar and dual-wavelength radar tech- niques were used the 1998 Cloud Lidar And Radar Experiment (CLARE'98) has been used to demonstrate that the combination

  3. Cloud temperature measurement using rotational Raman lidar

    NASA Astrophysics Data System (ADS)

    Su, Jia; Patrick McCormick, M.; Wu, Yonghua; Lee, Robert B.; Lei, Liqiao; Liu, Zhaoyan; Leavor, Kevin R.

    2013-08-01

    Insufficient suppression of the elastic-scattering signal in the rotational Raman (RR) detection channels can result in a retrieval error particularly when the temperature of a thick cloud is measured using an RR lidar. To solve this problem, a technique is presented to obtain relative transmission factors for the two RR channels' thereby correcting for the influence of residual elastic-signal on the temperature retrieval. The feasibility of this technique is demonstrated by applying the algorithm to the Hampton University (HU) lidar measurements. Intercomparisons of these temperature retrievals from both water-phase and cirrus clouds show good agreement with radiosonde measurements.

  4. LIDAR, Point Clouds, and their Archaeological Applications

    SciTech Connect

    White, Devin A [ORNL

    2013-01-01

    It is common in contemporary archaeological literature, in papers at archaeological conferences, and in grant proposals to see heritage professionals use the term LIDAR to refer to high spatial resolution digital elevation models and the technology used to produce them. The goal of this chapter is to break that association and introduce archaeologists to the world of point clouds, in which LIDAR is only one member of a larger family of techniques to obtain, visualize, and analyze three-dimensional measurements of archaeological features. After describing how point clouds are constructed, there is a brief discussion on the currently available software and analytical techniques designed to make sense of them.

  5. Cloud properties derived from two lidars over the ARM SGP site

    NASA Astrophysics Data System (ADS)

    Dupont, Jean-Charles; Haeffelin, Martial; Morille, Yohann; Comstock, Jennifer M.; Flynn, Connor; Long, Charles N.; Sivaraman, Chitra; Newson, Rob K.

    2011-04-01

    Active remote sensors such as lidars or radars can be used with other data to quantify the cloud properties at regional scale and at global scale. Relative to radar, lidar remote sensing is sensitive to very thin and high clouds but has a significant limitation due to signal attenuation in the ability to precisely quantify the properties of clouds with a cloud optical thickness larger than 3. The cloud properties for all levels of clouds are derived and distributions of cloud base height (CBH), top height (CTH), physical cloud thickness (CT), and optical thickness (COT) from local statistics are compared. The goal of this study is (1) to establish a climatology of macrophysical and optical properties for all levels of clouds observed over the ARM SGP site and (2) to estimate the discrepancies between the two remote sensing systems (pulse energy, sampling, resolution, etc.). Our first results tend to show that the MPL, which are the primary ARM lidars, have a distinctly limited range within which all of these cloud properties are detectable, especially cloud top and cloud thickness, but this can include cloud base particularly during summer daytime period. According to the comparisons between RL and MPL, almost 50% of situations show a signal to noise ratio too low (smaller than 3) for the MPL in order to detect clouds higher than 7km during daytime period in summer. Consequently, the MPL-derived annual cycle of cirrus cloud base (top) altitude is biased low, especially for daylight periods, compared with those derived from the RL data, which detects cloud base ranging from 7.5 km in winter to 9.5 km in summer (and tops ranging from 8.6 to 10.5 km). The optically thickest cirrus clouds (COT > 0.3) reach 50% of the total population for the Raman lidar and only 20% for the Micropulse lidar due to the difference of pulse energy and the effect of solar irradiance contamination. A complementary study using the cloud fraction derived from the Micropulse lidar for clouds below 5 km and from the Raman lidar for cloud above 5 km allows for better estimation of the total cloud fraction between the ground and the top of the atmosphere. This study presents the diurnal cycle of cloud fraction for each season in comparisons with Long et al.'s (2006) cloud fraction calculation derived from radiative flux analysis.

  6. Coherent CO2 lidar: A superior system for observing clouds?

    NASA Technical Reports Server (NTRS)

    Eberhard, Wynn L.; Hardesty, R. Michael

    1992-01-01

    Lidars have long been used to study various parameters of clouds. NOAA's Wave Propagation Laboratory has operated a coherent CO2 lidar for over a decade, using Doppler to study wind fields and turbulence, atmospheric absorption for Differential Absorption Lidar (DIAL) applications, backscatter to investigate aerosol distributions, and backscatter and extinction measurements on clouds. A system under development for our laboratory promises to overcome the older system's problems of large size, frequency instability, and need for continual operator attention. We are also thoroughly evaluating the capabilities of CO2 lidar for observing clouds, including development of some new techniques. CO2 lidar provides a view of clouds different in many ways from that of lidars at other extinction measurements from clouds. This discussion argues in support of the proposition: coherent CO2 lidar can be a superior lidar system for measuring most cloud properties.

  7. Investigation of cloud properties using a Raman lidar

    Microsoft Academic Search

    David Neil Whiteman

    2000-01-01

    Raman lidar is well known to be a useful tool for charting the evolution of water vapor and aerosols in the atmosphere. The goal of this dissertation is to use the Raman lidar technique to study cloud properties that are important in understanding atmospheric radiation and dynamics. The lidar system used here is the NASA\\/GSFC Scanning Raman Lidar. A detailed

  8. Scanning ARM Cloud Radar Handbook

    SciTech Connect

    Widener, K; Bharadwaj, N; Johnson, K

    2012-06-18

    The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.

  9. The Earth Clouds and Radiation Explorer (EarthCARE) Mission: Cloud and Aerosol Lidar and Imager algorithms.

    NASA Astrophysics Data System (ADS)

    Donovan, David; van Zadelhoff, Gerd-Jan; Wandinger, Ulla; Hünerbein, Anjah; Fischer, Jurgen; von Bismarck, Jonas; Eisinger, Michael; Lajas, Dulce; Wehr, Tobias

    2015-04-01

    The value of multi-sensor remote sensing applied to clouds and aerosol has become clear in recent years. For example, combinations of instruments including passive radiometers, lidars and cloud radars have proved invaluable for their ability to retrieve profiles of cloud macrophysical and microphysical properties. This is amply illustrated by various results from the US-DoE ARM (and similar) surface sites as well as results from data collected by sensors aboard the A-train satellites CloudSat, CALIPSO, and Terra. The Earth Clouds Aerosol and Radiation Explorer (EarthCARE) mission is a combined ESA/JAXA mission to be launched in 2018 which has been designed with sensor-synergy playing a key role. The mission consists of a cloud-profiling radar (CPR), a high-spectral resolution cloud/aerosol lidar (ATLID), a cloud/aerosol multi-spectral imager (MSI), and a three-view broad-band radiometer (BBR). The mission will deliver cloud, aerosol and radiation products focusing on horizontal scales ranging from 1 km to 10 km. EarthCARE data will be used in multiple ways ranging from model evaluation studies, to GCM-orientated cloud microphysical property parameterization development, to data assimilation activities. Recently a number of activities, funded by ESA, have kicked-off which will ultimately deliver operational algorithms for EarthCARE. One of these activities is the "Atmospheric Products from Imager and Lidar" (APRIL) project which focuses on the development of lidar, imager and combined lidar-imager cloud and aerosol algorithms. In this presentation an overview of the APRIL algorithms within the wider context of the planned EarthCARE processing chain will be given.

  10. Infrared Lidar Sensitivity to Cloud Optical and Geometrical Properties: Implications for Earth-Orbiting Doppler Lidar

    Microsoft Academic Search

    Robert T. Menzies; David M. Tratt

    Flights of calibrated backscatter lidars during the GLOBE (Global Backscatter Experiment) Pacific missions have provided the opportunity to study cloud optical properties at lidar wavelengths in the visible and near-IR (.530, 1.06, and 1.54 pm from the NASA GSFC Nd:YAG lidar) and the thermal IR (9.25 Pm from the JPL C02 lidar), for a wide range of cloud types. These

  11. LIDAR multiple scattering from clouds

    NASA Astrophysics Data System (ADS)

    Bissonnette, L. R.; Bruscaglioni, P.; Ismaelli, A.; Zaccanti, G.; Cohen, A.; Benayahu, Y.; Kleiman, M.; Egert, S.; Flesia, C.; Schwendimann, P.; Starkov, A. V.; Noormohammadian, M.; Oppel, U. G.; Winker, D. M.; Zege, E. P.; Katsev, I. L.; Polonsky, I. N.

    1995-04-01

    Multiple-scattering LIDAR return calculations obtained by seven different models for the same specified numerical experiment are compared. This work results from an international joint effort stimulated by the workshop group called MUSCLE for MUltiple SCattering Lidar Experiments. The models include approximations to the radiative-transfer theory, Monte-Carlo calculations, a stochastic model of the process of multiple scattering, and an extension of Mie theory for particles illuminated by direct and scattered light. The model solutions are similar in form but differ by up to a factor of 5 in the strength of the multiple-scattering contributions. Various reasons for the observed differences are explored and their practical significance is discussed.

  12. A Depolarisation lidar based method for the determination of liquid-cloud microphysical properties

    NASA Astrophysics Data System (ADS)

    Donovan, David; Klein Baltink, Henk; Henzing, Bas; de Roode, Stephen; Siebesma, Pier

    2015-04-01

    The fact that polarisation lidars measure a~depolarisation signal in liquid clouds due to the occurrence of multiple-scattering is well-known. The degree of measured depolarisation depends on the lidar characteristics (e.g. wavelength and receiver field-of-view) as well as the cloud macrophysical (e.g. cloud base altitude) and microphysical (e.g. effective radius, liquid water content) properties. Efforts seeking to use depolarisation information in a~quantitative manner to retrieve cloud properties have been undertaken with, arguably, limited practical success. In this work we present a~retrieval procedure applicable to clouds with (quasi-)linear liquid water content (LWC) profiles and (quasi-)constant cloud droplet number density in the cloud base region. Thus limiting the applicability of the procedure allows us to reduce the cloud variables to two parameters (namely the derivative of the liquid water content with height and the extinction at a~fixed distance above cloud-base). This simplification, in turn, allows us to employ a~fast and robust optimal-estimation inversion using pre-computed look-up-tables produced using extensive lidar Monte-Carlo multiple-scattering simulations. In this paper, we describe the theory behind the inversion procedure and successfully apply it to simulated observations based on large-eddy simulation model output. The inversion procedure is then applied to actual depolarisation lidar data corresponding to a~range of cases taken from the Cabauw measurement site in the central Netherlands. The lidar results were then used to predict the corresponding cloud-base region radar reflectivities. In non-drizzling condition, it was found that the lidar inversion results can be used to predict the observed radar reflectivities with an accuracy within the radar calibration uncertainty (2--3 dBZ). This result strongly supports the accuracy of the lidar inversion results. Results of a~comparison between ground-based aerosol number concentration and lidar-derived cloud droplet number densities are also presented and discussed. The observed relationship between the two quantities is seen to be consistent with the results of previous studies based on aircraft-based in situ measurements.

  13. Next-Generation Spaceborne Cloud Profiling Radars

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Durden, Stephen L.; Im, Eastwood; Heymsfield, Gerald M.; Racette, Paul; Starr, Dave O.

    2009-01-01

    One of the instruments recommended for deployment on the Aerosol/Cloud/Echosystems (ACE) mission is a new advanced Cloud Profiling Radar (ACE-CPR). The atmospheric sciences community has initiated the effort to define the scientific requirements for this instrument. Initial studies focusing on system configuration, performance and feasibility start from the successful experience of the Cloud Profiling Radar on CloudSat Mission (CS-CPR), the first 94-GHz nadir-looking spaceborne radar which has been acquiring global time series of vertical cloud structure since June 2, 2006. In this paper we address the significance of CloudSat's accomplishments in regards to the design and development of radars for future cloud profiling missions such as EarthCARE and ACE.

  14. A cloud masking algorithm for EARLINET lidar systems

    NASA Astrophysics Data System (ADS)

    Binietoglou, Ioannis; Baars, Holger; D'Amico, Giuseppe; Nicolae, Doina

    2015-04-01

    Cloud masking is an important first step in any aerosol lidar processing chain as most data processing algorithms can only be applied on cloud free observations. Up to now, the selection of a cloud-free time interval for data processing is typically performed manually, and this is one of the outstanding problems for automatic processing of lidar data in networks such as EARLINET. In this contribution we present initial developments of a cloud masking algorithm that permits the selection of the appropriate time intervals for lidar data processing based on uncalibrated lidar signals. The algorithm is based on a signal normalization procedure using the range of observed values of lidar returns, designed to work with different lidar systems with minimal user input. This normalization procedure can be applied to measurement periods of only few hours, even if no suitable cloud-free interval exists, and thus can be used even when only a short period of lidar measurements is available. Clouds are detected based on a combination of criteria including the magnitude of the normalized lidar signal and time-space edge detection performed using the Sobel operator. In this way the algorithm avoids misclassification of strong aerosol layers as clouds. Cloud detection is performed using the highest available time and vertical resolution of the lidar signals, allowing the effective detection of low-level clouds (e.g. cumulus humilis). Special attention is given to suppress false cloud detection due to signal noise that can affect the algorithm's performance, especially during day-time. In this contribution we present the details of algorithm, the effect of lidar characteristics (space-time resolution, available wavelengths, signal-to-noise ratio) to detection performance, and highlight the current strengths and limitations of the algorithm using lidar scenes from different lidar systems in different locations across Europe.

  15. Airborne and spaceborne cloud radar designs

    Microsoft Academic Search

    Fuk Li; Eastwood Im; Stephen Durden; William Wilson

    1994-01-01

    Presents some crucial design parameters and a strawman system design for a nadir-looking, 94-GHz spaceborne cloud profiling radar. This sensor is expected to provide cloud measurements at vertical resolution of 500 m and with a minimum detectable cloud reflectivity of slightly better than -30 dBZ. The radar design is intended to be accommodated by a spacecraft with limited resources. It

  16. Spaceborne Radar Would Measure Rain And Clouds

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Kellogg, Kent H.

    1992-01-01

    Report describes conceptual design of spaceborne radar system mapping precipitation and clouds at mid-latitudes to provide data for research on global weather and climate. Radar operates at two frequencies. Lower (35 GHz) provides vertical profiles of rainfall at rates up to 20 mm/h and enables probing of cirrus clouds. Higher (94 GHz) enables detection and quantitative measurements of clouds of all types and provides rain profiles at rates up to 10 mm/h.

  17. Building a 15-Year Cloud Climatology using Lidar in Space Observations: CALIOP and CloudSat now, EarthCARE next.

    NASA Astrophysics Data System (ADS)

    Reverdy, M.; Chepfer, H.; Donovan, D. P.; Noel, V.; Marchand, R.; Cesana, G.; Hoareau, C.; Chiriaco, M.; Bastin, S.

    2014-12-01

    Today, the CALIOP lidar and CloudSat radar have collected more than seven years of observations, and willhopefully still operate in 2016, after the EarthCARE-ATLID/CPR launch. Lidars and Radars in space providecutting edge information on the detailed vertical structure of clouds: a key element for both the evaluation ofthe description of clouds in climate models, and the survey of the clouds inter-annual evolution in variousclimatic conditions (El Nino, variation of North Atlantic Oscillations, polar regions, etc). For this purpose,the observations collected by CALIOP and by ATLID as well as CloudSat and EarthCARE CPR need to bemerged into a long-term (15 years) cloud climatology. Here, we examine the possibility of building such a climatology, with the aim of defining its accuracy andrelevance for cloud inter-annual studies. We examine the differences between the instruments (wavelengths,satellite's altitudes, telescope fields of view, multiple scattering processes, spatial resolutions) and theirability to detect the same clouds consistently. Then, we define a set of cloud detection thresholds for ATLID,CALIOP, CloudSat and EarthCARE-CPR and test against synthetic cloud scenes (cirrus and shallowcumulus) over small areas (about 200km) produced by a lidar and radar instrument simulator (ECSIM)running on Large Eddy Simulations. Doing so, we verify that the fourth instruments will be able to detect thesame clouds despite their differences (e.g. their sensitivities to noise). Finally, we use the COSP lidar andradar simulator to predict the global scale cloud cover that ATLID, CALIOP, CloudSat and EarthCARE CPRwould observe if they were overflying the same atmosphere predicted by a GCM. Our results suggest that amerged CALIOP/ATLID and CloudSat/CPR cloud climatology could be to be useful for clouds inter-annualstudies, if the post-launch sensitivity of EarthCARE instruments is in line with what is predicted today.

  18. Polar stratospheric clouds over Antarctica from the CALIPSO spaceborne lidar

    Microsoft Academic Search

    Vincent Noel; Albert Hertzog; Hélène Chepfer; David M. Winker

    2008-01-01

    This paper presents statistics of polar stratospheric clouds (PSCs) above Antarctica from June to October 2006 using observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) spaceborne lidar, part of the CALIPSO mission. Synoptic-scale changes in geographic and temporal distribution are documented weekly and correlated with temperature fields. A high spatial and temporal variability tends to contradict the hypothesis that

  19. Depolarization ratio–effective lidar ratio relation: Theoretical basis for space lidar cloud phase discrimination

    Microsoft Academic Search

    Yongxiang Hu

    2007-01-01

    This paper introduces a technique for cloud phase discrimination based on linear polarization measurements made by space-based lidar. Using CALIPSO Level 2 data products, a 3-dimensional histogram of the depolarization ratio, ?, and the effective lidar ratio, Sc,eff, is derived for all optically thick clouds measured during July 2006. A second histogram is derived using data from early November, 2006.

  20. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. ???, XXXX, DOI:10.1029/, Combined CloudSat-CALIPSO-MODIS retrievals of1

    E-print Network

    Delanoë, Julien

    from spaceborne radar, lidar and infrared radiometers5 on the A-Train of satellites are combined regions where both radar and lidar are sensitive to the regions where one de-8 tect the cloud. We first more, the radar-only and lidar-only retrieval than the radar-16 lidar retrieval, although the lidar

  1. CloudSat: the Cloud Profiling Radar Mission

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Durden, Stephen L.; Tanelli, Simone

    2006-01-01

    The Cloud Profiling Radar (CPR), the primary science instrument of the CloudSat Mission, is a 94-GHz nadir-looking radar that measures the power backscattered by clouds as a function of distance from the radar. This instrument will acquire a global time series of vertical cloud structure at 500-m vertical resolution and 1.4-km horizontal resolution. CPR will operate in a short-pulse mode and will yield measurements at a minimum detectable sensitivity of -28 dBZ.

  2. First observations of tracking clouds using scanning ARM cloud radars

    DOE PAGESBeta

    Borque, Paloma; Giangrande, Scott; Kollias, Pavlos

    2014-12-01

    Tracking clouds using scanning cloud radars can help to document the temporal evolution of cloud properties well before large drop formation (‘‘first echo’’). These measurements complement cloud and precipitation tracking using geostationary satellites and weather radars. Here, two-dimensional (2-D) Along-Wind Range Height Indicator (AW-RHI) observations of a population of shallow cumuli (with and without precipitation) from the 35-GHz scanning ARM cloud radar (SACR) at the DOE Atmospheric Radiation Measurements (ARM) program Southern Great Plains (SGP) site are presented. Observations from the ARM SGP network of scanning precipitation radars are used to provide the larger scale context of the cloud fieldmore »and to highlight the advantages of the SACR to detect the numerous, small, non-precipitating cloud elements. A new Cloud Identification and Tracking Algorithm (CITA) is developed to track cloud elements. In CITA, a cloud element is identified as a region having a contiguous set of pixels exceeding a preset reflectivity and size threshold. The high temporal resolution of the SACR 2-D observations (30 sec) allows for an area superposition criteria algorithm to match cloud elements at consecutive times. Following CITA, the temporal evolution of cloud element properties (number, size, and maximum reflectivity) is presented. The vast majority of the designated elements during this cumulus event were short-lived non-precipitating clouds having an apparent life cycle shorter than 15 minutes. The advantages and disadvantages of cloud tracking using an SACR are discussed.« less

  3. First observations of tracking clouds using scanning ARM cloud radars

    DOE PAGESBeta

    Borque, Paloma [McGill Univ., Montreal, QC (Canada); Giangrande, Scott [Brookhaven National Lab. (BNL), Upton, NY (United States); Kollias, Pavlos [McGill Univ., Montreal, QC (Canada)

    2014-12-01

    Tracking clouds using scanning cloud radars can help to document the temporal evolution of cloud properties well before large drop formation (‘‘first echo’’). These measurements complement cloud and precipitation tracking using geostationary satellites and weather radars. Here, two-dimensional (2-D) Along-Wind Range Height Indicator (AW-RHI) observations of a population of shallow cumuli (with and without precipitation) from the 35-GHz scanning ARM cloud radar (SACR) at the DOE Atmospheric Radiation Measurements (ARM) program Southern Great Plains (SGP) site are presented. Observations from the ARM SGP network of scanning precipitation radars are used to provide the larger scale context of the cloud field and to highlight the advantages of the SACR to detect the numerous, small, non-precipitating cloud elements. A new Cloud Identification and Tracking Algorithm (CITA) is developed to track cloud elements. In CITA, a cloud element is identified as a region having a contiguous set of pixels exceeding a preset reflectivity and size threshold. The high temporal resolution of the SACR 2-D observations (30 sec) allows for an area superposition criteria algorithm to match cloud elements at consecutive times. Following CITA, the temporal evolution of cloud element properties (number, size, and maximum reflectivity) is presented. The vast majority of the designated elements during this cumulus event were short-lived non-precipitating clouds having an apparent life cycle shorter than 15 minutes. The advantages and disadvantages of cloud tracking using an SACR are discussed.

  4. The Ability of MM5 to Simulate Ice Clouds: Systematic Comparison between Simulated and Measured Fluxes and Lidar/Radar Profiles at the

    E-print Network

    Protat, Alain

    effect is governed primarily by the equi- librium between their albedo effect and their green- house effect. Both macrophysical and microphysical properties of ice clouds regulate this equilibrium. To quantify the effect of these clouds onto climate and weather systems, their global coverage, altitude, tem

  5. Reconstruction of cloud geometry using a scanning cloud radar

    NASA Astrophysics Data System (ADS)

    Ewald, F.; Winkler, C.; Zinner, T.

    2015-06-01

    Clouds are one of the main reasons of uncertainties in the forecasts of weather and climate. In part, this is due to limitations of remote sensing of cloud microphysics. Present approaches often use passive spectral measurements for the remote sensing of cloud microphysical parameters. Large uncertainties are introduced by three-dimensional (3-D) radiative transfer effects and cloud inhomogeneities. Such effects are largely caused by unknown orientation of cloud sides or by shadowed areas on the cloud. Passive ground-based remote sensing of cloud properties at high spatial resolution could be crucially improved with this kind of additional knowledge of cloud geometry. To this end, a method for the accurate reconstruction of 3-D cloud geometry from cloud radar measurements is developed in this work. Using a radar simulator and simulated passive measurements of model clouds based on a large eddy simulation (LES), the effects of different radar scan resolutions and varying interpolation methods are evaluated. In reality, a trade-off between scan resolution and scan duration has to be found as clouds change quickly. A reasonable choice is a scan resolution of 1 to 2°. The most suitable interpolation procedure identified is the barycentric interpolation method. The 3-D reconstruction method is demonstrated using radar scans of convective cloud cases with the Munich miraMACS, a 35 GHz scanning cloud radar. As a successful proof of concept, camera imagery collected at the radar location is reproduced for the observed cloud cases via 3-D volume reconstruction and 3-D radiative transfer simulation. Data sets provided by the presented reconstruction method will aid passive spectral ground-based measurements of cloud sides to retrieve microphysical parameters.

  6. Lidar and radar derived cirrus microphysical properties for the 26 November 1991 case study

    NASA Technical Reports Server (NTRS)

    Intrieri, Janet M.; Feingold, Graham

    1993-01-01

    The Wave Propagation Laboratory's CO2 lidar (lambda = 10.6 microns) and Ka-band radar (lambda = 8.66 mm) operate at widely separated wavelengths; the differences in how the transmitted waves interact with cloud targets can be exploited to provide information that neither sensor could provide alone. This can be as simple as overlapping the data sets to provide additional coverage on cloud geometry (see Uttal and Intrieri, 1993) or combining the measurements in a theoretical framework to provide cirrus cloud parameters of the size spectrum, i.e., characteristic particle size and number concentration. In this paper, the latter option is described and an example case study presented to illustrate the types of information available for cloud and radiation transfer models.

  7. Lidar and radar measurements of the melting layer in the frame of the Convective and Orographically-induced Precipitation Study: observations of dark and bright band phenomena

    NASA Astrophysics Data System (ADS)

    di Girolamo, P.; Summa, D.; Bhawar, R.; di Iorio, T.; Norton, E. G.; Peters, G.; Dufournet, Y.

    2011-11-01

    During the Convective and Orographically-induced Precipitation Study (COPS), lidar dark and bright bands were observed by the University of BASILicata Raman lidar system (BASIL) during several intensive (IOPs) and special (SOPs) observation periods (among others, 23 July, 15 August, and 17 August 2007). Lidar data were supported by measurements from the University of Hamburg cloud radar MIRA 36 (36 GHz), the University of Hamburg dual-polarization micro rain radars (24.1 GHz) and the University of Manchester UHF wind profiler (1.29 GHz). Results from BASIL and the radars for 23 July 2007 are illustrated and discussed to support the comprehension of the microphysical and scattering processes responsible for the appearance of the lidar and radar dark and bright bands. Simulations of the lidar dark and bright band based on the application of concentric/eccentric sphere Lorentz-Mie codes and a melting layer model are also provided. Lidar and radar measurements and model results are also compared with measurements from a disdrometer on ground and a two-dimensional cloud (2DC) probe on-board the ATR42 SAFIRE.

  8. Ground-based microwave radar and optical lidar signatures of volcanic ash plumes: models, observations and retrievals

    NASA Astrophysics Data System (ADS)

    Mereu, Luigi; Marzano, Frank; Mori, Saverio; Montopoli, Mario; Cimini, Domenico; Martucci, Giovanni

    2013-04-01

    The detection and quantitative retrieval of volcanic ash clouds is of significant interest due to its environmental, climatic and socio-economic effects. Real-time monitoring of such phenomena is crucial, also for the initialization of dispersion models. Satellite visible-infrared radiometric observations from geostationary platforms are usually exploited for long-range trajectory tracking and for measuring low level eruptions. Their imagery is available every 15-30 minutes and suffers from a relatively poor spatial resolution. Moreover, the field-of-view of geostationary radiometric measurements may be blocked by water and ice clouds at higher levels and their overall utility is reduced at night. Ground-based microwave radars may represent an important tool to detect and, to a certain extent, mitigate the hazard from the ash clouds. Ground-based weather radar systems can provide data for determining the ash volume, total mass and height of eruption clouds. Methodological studies have recently investigated the possibility of using ground-based single-polarization and dual-polarization radar system for the remote sensing of volcanic ash cloud. A microphysical characterization of volcanic ash was carried out in terms of dielectric properties, size distribution and terminal fall speed, assuming spherically-shaped particles. A prototype of volcanic ash radar retrieval (VARR) algorithm for single-polarization systems was proposed and applied to S-band and C-band weather radar data. The sensitivity of the ground-based radar measurements decreases as the ash cloud is farther so that for distances greater than about 50 kilometers fine ash might be not detected anymore by microwave radars. In this respect, radar observations can be complementary to satellite, lidar and aircraft observations. Active remote sensing retrieval from ground, in terms of detection, estimation and sensitivity, of volcanic ash plumes is not only dependent on the sensor specifications, but also on the range and ash cloud distribution. The minimum detectable signal can be increased, for a given system and ash plume scenario, by decreasing the observation range and increasing the operational frequency using a multi-sensor approach, but also exploiting possible polarimetric capabilities. In particular, multi-wavelengths lidars can be complementary systems useful to integrate radar-based ash particle measurement. This work, starting from the results of a previous study and from above mentioned issues, is aimed at quantitatively assessing the optimal choices for microwave and millimeter-wave radar systems with a dual-polarization capability for real-time ash cloud remote sensing to be used in combination with an optical lidar. The physical-electromagnetic model of ash particle distributions is systematically reviewed and extended to include non-spherical particle shapes, vesicular composition, silicate content and orientation phenomena. The radar and lidar scattering and absorption response is simulated and analyzed in terms of self-consistent polarimetric signatures for ash classification purposes and correlation with ash concentration and mean diameter for quantitative retrieval aims. A sensitivity analysis to ash concentration, as a function of sensor specifications, range and ash category, is carried out trying to assess the expected multi-sensor multi-spectral system performances and limitations. The multi-sensor multi-wavelength polarimetric model-based approach can be used within a particle classification and estimation scheme, based on the VARR Bayesian metrics. As an application, the ground-based observation of the Eyjafjallajökull volcanic ash plume on 15-16 May 2010, carried out at the Atmospheric Research Station at Mace Head, Carna (Ireland) with MIRA36 35-GHz Ka-Band Doppler cloud radar and CHM15K lidar/ceilometer at 1064-nm wavelength, has been considered. Results are discussed in terms of retrievals and intercomparison with other ground-based and satellite-based sensors.

  9. MU radar and lidar observations of clear-air turbulence and mammatus underneath cirrus

    NASA Astrophysics Data System (ADS)

    Luce, H.; Nakamura, T.; Yamamoto, M.; Fukao, S.

    2009-04-01

    Mammatus are smooth hanging protuberances on the undersurface of a cloud (Glossary of Meteorology). Their mechanisms for formation and their role in the atmosphere are still not well-known. We obtained Rayleigh/Mie/Raman (RMR) lidar measurements of cirrus mammatus in the night of 07-08 June 2006 at Shigaraki Observatory (34.85°N, 136.10°E, Japan). Coincident observations from the VHF (46.5 MHz) MU radar in range imaging (FII) mode revealed the presence of downward developing turbulent layers and oscillatory vertical wind perturbations (+/-0.7 m/s) near the cirrus cloud base and in the mammatus environment. Moreover, simultaneous radiosonde data showed the presence of a dry and weakly stable layer underneath the cirrus. Our analysis suggests that turbulence and mammatus were generated by convective overturns due to evaporative cooling in the subcloud region. The cooling was likely the consequence of sublimation of ice crystals below the cloud base due to either precipitation or, more likely, spontaneous mixing of the saturated air and the dry air through the cloud-base detrainment instability (CDI) mechanism at the cloud base. Clear air downdrafts measured by the MU radar were associated with the descending mammatus lobes and clear air updrafts were observed between the lobes. Consequently, in addition to a possible negative buoyancy of the cloudy air, the cloudy air might have been pushed down by the downdrafts of the "upside-down" convective instability and pushed up by the updrafts to form mammatus lobes.

  10. Retrieve Optically Thick Ice Cloud Microphysical Properties by Using Airborne Dual-Wavelength Radar Measurements

    NASA Technical Reports Server (NTRS)

    Wang, Zhien; Heymsfield, Gerald M.; Li, Lihua; Heymsfield, Andrew J.

    2005-01-01

    An algorithm to retrieve optically thick ice cloud microphysical property profiles is developed by using the GSFC 9.6 GHz ER-2 Doppler Radar (EDOP) and the 94 GHz Cloud Radar System (CRS) measurements aboard the high-altitude ER-2 aircraft. In situ size distribution and total water content data from the CRYSTAL-FACE field campaign are used for the algorithm development. To reduce uncertainty in calculated radar reflectivity factors (Ze) at these wavelengths, coincident radar measurements and size distribution data are used to guide the selection of mass-length relationships and to deal with the density and non-spherical effects of ice crystals on the Ze calculations. The algorithm is able to retrieve microphysical property profiles of optically thick ice clouds, such as, deep convective and anvil clouds, which are very challenging for single frequency radar and lidar. Examples of retrieved microphysical properties for a deep convective clouds are presented, which show that EDOP and CRS measurements provide rich information to study cloud structure and evolution. Good agreement between IWPs derived from an independent submillimeter-wave radiometer, CoSSIR, and dual-wavelength radar measurements indicates accuracy of the IWC retrieved from the two-frequency radar algorithm.

  11. Depolarization ratio-effective lidar ratio relation: Theoretical basis for space lidar cloud phase discrimination

    Microsoft Academic Search

    Yongxiang Hu

    2007-01-01

    This paper introduces a technique for cloud phase discrimination based on linear polarization measurements made by space-based lidar. Using CALIPSO Level 2 data products, a 3-dimensional histogram of the depolarization ratio, delta, and the effective lidar ratio, Sc,eff, is derived for all optically thick clouds measured during July 2006. A second histogram is derived using data from early November, 2006.

  12. 24th International Laser Radar Conference BACKSCATTER NEPHELOM.ETER TO CALIBRATE SCANNING LIDAR

    E-print Network

    24th International Laser Radar Conference BACKSCATTER NEPHELOM.ETER TO CALIBRATE SCANNING LIDAR-grade instrument, which operates at the wavelength 355 nm, will be co-located with a scanning-lidar at measurement the vertical particulate extinction-coefficient profile from the signals of elastic scanning lidar without

  13. Use of a Lidar Forward Model for Global Comparisons of Cloud Fraction between the ICESat Lidar and the ECMWF Model

    Microsoft Academic Search

    Jonathan M. Wilkinson; Robin J. Hogan; Anthony J. Illingworth; Angela Benedetti

    2008-01-01

    The performance of the European Centre for Medium-Range Weather Forecasts (ECMWF) model in simulating clouds is evaluated using observations by the Geoscience Laser Altimeter System lidar on the Ice, Cloud, and Land Elevation Satellite (ICESat). To account for lidar attenuation in the comparison, model variables are used to simulate the attenuated backscatter using a lidar forward model. This generates a

  14. Inversion of 2 wavelength Lidar data for cloud properties

    NASA Technical Reports Server (NTRS)

    Pal, S. R.; Carswell, A. I.

    1986-01-01

    The inversion of the lidar equation to derive quantitative properties of the atmosphere has continued to present considerable difficulty. The results of a study in which Klett's procedure was utilized for the analysis of cloud backscatter measurements made simulataneously at two ruby lidar wavelengths (694nm,347nmm) are presented. With one lidar system a cloud is probed at the two wavelength and the backscatter measured simulataneously by separate receivers. As a result two sigma profiles which should differ only because the wavlength dependence of the scattering. Experimental data presented to demonstrate the effects and the implications of the applications of the inversion method will be discussed.

  15. Hybrid lidar radar receiver for underwater imaging applications

    NASA Astrophysics Data System (ADS)

    Seetamraju, Madhavi; Gurjar, Rajan; Squillante, Michael; Derderian, Jeffrey P.

    2009-05-01

    In this work, we present research performed to improve the receiver characteristics for underwater imaging applications using the hybrid lidar-radar detection technique. We report the development of the next-generation coherent heterodyne receiver using modulation of the optical receiver's amplifier gain. Significant advantages in the receiver specifications are achieved using a large-area, high gain, low-noise silicon avalanche photodiode (APD) as the photodetector cum frequency mixer-demodulator. We demonstrate that heterodyne detection by gain modulation of APD can be used to increase the signal-to-noise ratio, detection sensitivity and bandwidth for the hybrid receiver system.

  16. Lidar observations of aerosols near clouds during CHAPS/CLASIC

    NASA Astrophysics Data System (ADS)

    Ferrare, R.; Clayton, M.; Turner, D.; Newsom, R.; Sivaraman, C.; Hostetler, C.; Hair, J.; Obland, M.; Rogers, R.; Cook, A.; Harper, D.; Su, W.; Jonsson, H.; Ogren, J.; Andrews, B.; Berg, L.

    2008-12-01

    Data collected by two lidar systems during the CHAPS/CLASIC missions are used to examine the behavior of aerosols in "transition zones" of a few kilometers to several tens of kilometers away from clouds. The lidar measurements are unaffected by cloud adjacency effects, are less susceptible to cloud contamination than passive satellite measurements, and possess high vertical and temporal resolution to capture variations in aerosol optical properties near clouds. The ground-based U.S. Department of Energy Atmospheric Radiation Measurement Climate Research Facility Raman lidar provides a detailed view of the variability of aerosols and water vapor near clouds at or near the top of the Planetary Boundary Layer. Aerosol and water vapor properties in the vicinity of clouds at the top of the daytime boundary layer are examined using 10 second profiles of aerosol backscattering, water vapor mixing ratio, and relative humidity, and 1 minute profiles of aerosol extinction in conjunction with continuous Total Sky Imager images of cloud cover. Data from the NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) collected during CHAPS/CLASIC are also used to examine the variability of aerosol optical properties near clouds. The LaRC airborne HSRL measures aerosol backscatter and depolarization at 532 and 1064 nm and aerosol extinction at 532 nm. Preliminary results using these Raman lidar and HSRL data show that aerosol backscatter and extinction 1-2 km from clouds were approximately 25-40% smaller than immediately adjacent to clouds. The variations in aerosol optical thickness are smaller, typically around 10-15%, since the changes in aerosol backscatter and extinction were generally confined to the top of the boundary layer. Variations in the Raman lidar aerosol backscatter and extinction measurements were typically confined to the altitude range between 200-400 m below cloud base and 200 m above cloud base. Raman lidar observations show relative humidity decreased by 5-15% within this same region suggesting that variations in backscatter and extinction near clouds were caused in part by hygroscopic aerosol growth. The HSRL aerosol depolarization measurements also suggest that aerosol nonsphericity changed in response to variations in relative humidity. This presentation will discuss the use of these lidar measurements as well as airborne in situ measurements to study the behavior of aerosols near clouds.

  17. CloudSat radar instrument design and development status

    Microsoft Academic Search

    Eastwood Im; Stephen L. Durden; Fuk K. Li; Chialin Wu; Ziad S. Haddad

    2001-01-01

    The Cloud Profiling Radar is the key science instrument for the CloudSat Mission to acquire a global data set of vertical atmospheric cloud structure and its variability. CPR is a 94-GHz nadir-looking radar that measures the power backscattered by clouds as a function of distance from the radar. This sensor is expected to provide cloud measurements at a 500-m vertical

  18. Assessment of scan-only operations of lidar for the detection and discrimination of biological clouds

    Microsoft Academic Search

    Kang H. Kwon

    2006-01-01

    The Joint Biological Standoff Detection System (JBSDS) Program has developed a lidar system for detecting and discriminating biological clouds at a standoff range. The lidar typically scans near the horizon to detect a cloud and then \\

  19. Radar For Measuring Vertical Cloud Structure

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Li, Fuk K.; Durden, Stephen L.; Wilson, William J.

    1995-01-01

    Proposed radar system views clouds from above and measures their vertical structures with resolution of 500 m. Two versions of system; initial developmental version to be flown aboard aircraft and final version flown aboard spacecraft in circular orbit around Earth at altitude of 400 km.

  20. SCANNING CLOUD RADAR OBSERVATIONS AT AZORES: PRELIMINARY 3D CLOUD PRODUCTS

    E-print Network

    SCANNING CLOUD RADAR OBSERVATIONS AT AZORES: PRELIMINARY 3D CLOUD PRODUCTS P. Kollias, I. Jo, A, NY www.bnl.gov ABSTRACT The deployment of the Scanning W-Band ARM Cloud Radar (SWACR) during the AMF campaign at Azores signals the first deployment of an ARM Facility-owned scanning cloud radar and offers

  1. Mie Lidar for Aerosols and Clouds Monitoring at Otlica Observatory

    NASA Astrophysics Data System (ADS)

    Gao, F.; Stani?, S.; Bergant, K.; Filip?i?, A.; Veberi?, D.; Forte, B.

    2009-04-01

    Aerosol and cloud densities are the most important atmospheric parameters, which significantly influence the atmospheric conditions. The study of their spatial and temporal properties can provide detailed information about the transport processes of the air masses. In recent years, lidar techniques for remote sensing of the atmospheric parameters have been greatly improved. Like the lidar systems of the Pierre Auger Observatory in Argentina (35.2S, 69.1W, 1400 m a.s.l.), the Mie lidar built at Otlica Observatory (45.93N, 13.91E, 945 m a.s.l.) in Slovenia employs the same hardware, including the transmitter, the receiver, and the DAQ system. Due to its high-power laser, large-diameter telescope, and photon-counting data-acquisition technique, the Mie lidar has the potential ability to measure the tropospheric and stratospheric atmospheric conditions, and is suitable for monitoring the changes of the cirrus clouds and atmospheric boundary layer. We have been performing routine atmospheric monitoring experiments with the Otlica Mie lidar since September 2008. Using the techniques of event-averaging, noise-elimination, and data-gluing, the far end of lidar probing range is extended from 30 km up to 40 km. The extinction profiles are calculated using the Klett method and the time-height-intensity plots were made. They clearly show the evolution of atmospheric conditions, especially the motion of the cirrus clouds above Otlica.

  2. Radar and radiation properties of ice clouds

    SciTech Connect

    Atlas, D. [NASA/Goddard Space Flight Center, Greenbelt, MD (United States)] [NASA/Goddard Space Flight Center, Greenbelt, MD (United States); Matrosov, S.Y. [Univ. of Colorado, Boulder CO (United States)] [Univ. of Colorado, Boulder CO (United States); Heymsfield, A.J. [National Center for Atmospheric Research, Boulder, CO (United States)] [and others] [National Center for Atmospheric Research, Boulder, CO (United States); and others

    1995-11-01

    The authors derive relations of the equivalent radar reflectivity Z{sub e} and extinction coefficient a of ice clouds and confirm the theory by in situ aircraft observations during the First International Satellite Cloud Climatology Project Regional Experiment. Equivalent radar reflectivity Z{sub e} is a function of ice water content Wand a moment of the size distribution such as the median volume diameter D{sub 0}. Stratification of the data by D{sub 0} provides a set of W-Z{sub e} relations from which one may deduce the dependence of particle density on size. This relation is close to that of Brown and Francis and provides confidence in the methodology of estimating particle size and mass. The authors find that there is no universal W-Z{sub e} relation, due both to large scatter and systematic shifts in particle size from day to day and cloud to cloud. These variations manifest the normal changes in ice crystal growth. The result is that, with the exception of temperatures less than -40{degrees}C, temperature cannot be used to reliably parameterize the particle size as has been previously suggested. To do so is to risk large possible systematic errors in retrievals. Even if one could measure monthly averages of ice water content, this is inadequate to estimate the monthly radiative effect because of the nonlinearity between the two. The authors show that a sizable fraction of radiatively significant clouds would be missed at a radar threshold of -30 dBZ, the value proposed for a spaceborne cloud-profiling radar. 29 refs., 13 figs., 3 tabs.

  3. Frequency-agile dual-frequency lidar for integrated coherent radar-lidar architectures.

    PubMed

    Vercesi, Valeria; Onori, Daniel; Laghezza, Francesco; Scotti, Filippo; Bogoni, Antonella; Scaffardi, Mirco

    2015-04-01

    We propose a novel architecture for implementing a dual-frequency lidar (DFL) exploiting differential Doppler shift measurement. The two frequency tones, needed for target velocity measurements, are selected from the spectrum of a mode-locked laser operating in the C-band. The tones' separation is easily controlled by using a programmable wavelength selective switch, thus allowing for a dynamic trade-off among robustness to atmospheric turbulence and sensitivity. Speed measurements for different tone separations equal to 10, 40, 80, and 160 GHz are demonstrated, proving the system's capability of working in different configurations. Thanks to the acquisition system based on an analog-to-digital converter and digital-signal processing, real-time velocity measurements are demonstrated. The MLL-based proposed architecture enables the integration of the DFL with a photonic-based radar that exploits the same laser for generating and receiving radio-frequency signal with high performance, thus allowing for simultaneous or complementary target observations by exploiting the advantages of both radar and lidar. PMID:25831332

  4. Comparison of millimeter-wave cloud radar measurements for the Fall 1997 Cloud IOP

    SciTech Connect

    Sekelsky, S.M.; Li, L.; Galloway, J.; McIntosh, R.E. [Univ. of Massachusetts, Amherst, MA (United States); Miller, M.A. [Brookhaven National Lab., Upton, NY (United States); Clothiaux, E.E. [Pennsylvania State Univ., University Park, PA (United States); Haimov, S. [Univ. of Wyoming, Laramie, WY (United States); Mace, G.; Sassen, K. [Univ. of Utah, Salt Lake City, UT (United States)

    1998-05-01

    One of the primary objectives of the Fall 1997 IOP was to intercompare Ka-band (350Hz) and W-band (95GHz) cloud radar observations and verify system calibrations. During September 1997, several cloud radars were deployed at the Southern Great Plains (SOP) Cloud and Radiation Testbed (CART) site, including the full time operation 35 GHz CART Millimeter-wave Cloud Radar (MMCR), the University of Massachusetts (UMass) single antenna 33GHz/95 GHz Cloud Profiling Radar System (CPRS), the 95 GHz Wyoming Cloud Radar (WCR) flown on the University of Wyoming King Air, the University of Utah 95 GHz radar and the dual-antenna Pennsylvania State University 94 GHz radar. In this paper the authors discuss several issues relevant to comparison of ground-based radars, including the detection and filtering of insect returns. Preliminary comparisons of ground-based Ka-band radar reflectivity data and comparisons with airborne radar reflectivity measurements are also presented.

  5. Distinguishing cirrus cloud presence in autonomous lidar measurements

    NASA Astrophysics Data System (ADS)

    Campbell, J. R.; Vaughan, M. A.; Oo, M.; Holz, R. E.; Lewis, J. R.; Welton, E. J.

    2014-07-01

    Level 2 Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite-based cloud datasets from 2012 are investigated for metrics that help distinguish the cirrus cloud presence of in autonomous lidar measurements, using temperatures, heights, optical depth and phase. A thermal threshold, proposed by Sassen and Campbell (2001; SC2001) for cloud top temperature Ttop ? -37 °C, is evaluated vs. CALIOP algorithms that identify ice-phase cloud layers alone using depolarized backscatter. Global mean cloud top heights (11.15 vs. 10.07 km a.m.s.l.), base heights (8.76 vs. 7.95 km a.m.s.l.), temperatures (-58.48 °C vs. -52.18 °C and -42.40 °C vs. -38.13 °C, respectively for tops and bases) and optical depths (1.18 vs. 1.23) reflect the sensitivity to these competing constraints. Over 99% of all Ttop ? -37 °C clouds are classified as ice by CALIOP Level 2 algorithms. Over 81% of all ice clouds correspond with Ttop ? -37 °C. For instruments lacking polarized measurements, and thus practical phase estimates, Ttop ? -37 °C proves stable for distinguishing cirrus, as opposed to the risks of glaciated liquid water cloud contamination occurring in a given sample from clouds identified at warmer temperatures. Uncertainties in temperature profiles use to collocate with lidar data (i.e., model reanalyses/sondes) may justifiably relax the Ttop ? -37 °C threshold to include warmer cases. The ambiguity of "warm" (Ttop > -37 °C) ice cloud genus cannot be reconciled completely with available measurements, however, conspicuously including phase. Cloud top heights and optical depths are evaluated as potential constraints, as functions of CALIOP-retrieved phase. However, these data provide, at best, additional constraint in regional samples, compared with temperature alone, and may exacerbate classification uncertainties overall globally.

  6. Distinguishing cirrus cloud presence in autonomous lidar measurements

    NASA Astrophysics Data System (ADS)

    Campbell, J. R.; Vaughan, M. A.; Oo, M.; Holz, R. E.; Lewis, J. R.; Welton, E. J.

    2015-01-01

    2012 Level-2 Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite-based cloud data sets are investigated for thresholds that distinguish the presence of cirrus clouds in autonomous lidar measurements, based on temperatures, heights, optical depth and phase. A thermal threshold, proposed by Sassen and Campbell (2001) for cloud top temperature Ttop ? -37 °C, is evaluated versus CALIOP algorithms that identify ice-phase cloud layers using polarized backscatter measurements. Derived global mean cloud top heights (11.15 vs. 10.07 km above mean sea level; a.m.s.l.), base heights (8.76 km a.m.s.l. vs. 7.95 km a.m.s.l.), temperatures (-58.48 °C vs. -52.18 °C and -42.40 °C vs. -38.13 °C, respectively, for tops and bases) and optical depths (1.18 vs. 1.23) reflect the sensitivity to this constraint. Over 99 % of all Ttop ? -37 °C clouds are classified as ice by CALIOP Level-2 algorithms. Over 81 % of all ice clouds correspond with Ttop ? -37 °C. For instruments lacking polarized measurements, and thus practical estimates of phase, Ttop ? -37 °C provides sufficient justification for distinguishing cirrus, as opposed to the risks of glaciated liquid-water cloud contamination occurring in a given sample from clouds identified at relatively "warm" (Ttop > -37 °C) temperatures. Although accounting for uncertainties in temperatures collocated with lidar data (i.e., model reanalyses/sondes) may justifiably relax the threshold to include warmer cases, the ambiguity of "warm" ice clouds cannot be fully reconciled with available measurements, conspicuously including phase. Cloud top heights and optical depths are investigated, and global distributions and frequencies derived, as functions of CALIOP-retrieved phase. These data provide little additional information, compared with temperature alone, and may exacerbate classification uncertainties overall.

  7. Aircraft-protection radar for use with atmospheric lidars Thomas J. Duck, Bernard Firanski, Frank D. Lind, and Dwight Sipler

    E-print Network

    Duck, Thomas J.

    Aircraft-protection radar for use with atmospheric lidars Thomas J. Duck, Bernard Firanski, Frank D. Lind, and Dwight Sipler A modified X-band radar system designed to detect aircraft during atmospheric lidar operations is described and characterized. The capability of the radar to identify aircraft

  8. Upgraded Doppler Rayleigh Lidar and Comparisonswith Stratospheric Radar: 1: Observations Following Initial System Modifications

    E-print Network

    Cho, John Y. N.

    run. METHODOLOGY Changes to the Doppler Rayleigh lidar include a refitted laser transmitter and hysteresis present with the pressure scanning instrument. The two color seed laser will give an absoluteUpgraded Doppler Rayleigh Lidar and Comparisonswith Stratospheric Radar: 1: Observations Following

  9. Threshold radar reflectivity for drizzling clouds Yangang Liu,1

    E-print Network

    Threshold radar reflectivity for drizzling clouds Yangang Liu,1 Bart Geerts,2 Mark Miller,2 Peter reflectivity between nonprecipitating and precipitating clouds; however, there has been neither a rigorous cloud to rain when the radar reflectivity exceeds some value (threshold reflectivity) but also reveals

  10. VALIDATION OF A RADAR DOPPLER SPECTRA SIMULATOR USING MEASUREMENTS FROM THE ARM CLOUD RADARS

    E-print Network

    VALIDATION OF A RADAR DOPPLER SPECTRA SIMULATOR USING MEASUREMENTS FROM THE ARM CLOUD RADARS model output with the Doppler spectra recorded from the vertically pointing cloud radars at the ARM are then used to compute the backscattering cross-section and fall velocities, while the turbulence

  11. Seasonal and optical characterisation of cirrus clouds over Indian sub-continent using LIDAR

    SciTech Connect

    Jayeshlal, G. S., E-mail: drssatyanarayana.malladi@gmail.com; Satyanarayana, Malladi, E-mail: drssatyanarayana.malladi@gmail.com; Dhaman, Reji K., E-mail: drssatyanarayana.malladi@gmail.com; Motty, G. S., E-mail: drssatyanarayana.malladi@gmail.com [Department of Optoelectronics, University of Kerala, Karyavattom, Trivandrum-695 581, Kerala (India)

    2014-10-15

    Light Detection and Ranging (LIDAR) is an important remote sensing technique to study about the cirrus clouds. The subject of cirrus clouds and related climate is challenging one. The received scattered signal from Lidar contains information on the physical and optical properties of cirrus clouds. The Lidar profile of the cirrus cloud provides information on the optical characteristics like depolarisation ratio, lidar ratio and optical depth, which give knowledge about possible phase, structure and orientation of cloud particle that affect the radiative budgeting of cirrus clouds. The findings from the study are subjected to generate inputs for better climatic modelling.

  12. Active Cloud Probing with Los Alamos National Laboratory's Wide Angle Imaging Lidar: Status and Outlook

    Microsoft Academic Search

    I. N. Polonsky; A. B. Davis; S. P. Brumby

    Summary We survey recent developments in off-beam cloud lidar and especially the Wide Angle Imaging Lidar (WAIL) developed at Los Alamos National Laboratory (LANL). By abandoning the single back- scattering assumption of standard (on-beam) lidar in favor of a multiple scattering model and with the appropriate modifications of the instrument, we enable detection robust detection of the cloud boundary opposite

  13. Airborne Lidar Point Cloud Density Indices

    Microsoft Academic Search

    P. T. Shih; C.-M. Huang

    2006-01-01

    Airborne lidar is useful for collecting a large volume and high density of points with three dimensional coordinates. Among these points are terrain points, as well as those points located aboveground. For DEM production, the density of the terrain points is an important quality index. While the penetration rate of laser points is dependent on the surface type characteristics, there

  14. Surface Roughness Impact on the Sea Ice Thickness Measurements Based on LIDAR/Radar Altimetry

    NASA Astrophysics Data System (ADS)

    Li, L.; Truesdale, D.; Posey, P.; Allard, R.; Gardner, J. M.; Brozena, J. M.; Richter-Menge, J.

    2013-12-01

    The Radar and/or LIDAR measurements of sea ice freeboard provide an indirect approach to infer sea ice thickness via isostasy. The underlying assumption is that the LIDAR signal returns at the air/snow interface and radar signal at the snow/ice interface. Thus the surface roughness at the air, snow and ice interface has a significant impact on the LIDAR/Radar returns, which can lead to very significant errors in the ice thickness retrievals. Recent Cryosat-2 validation results suggest that its altimetry-based technique is very effective in mapping hemispheric sea ice thickness. However, in some cases significant bias exists in the Cryosat-2 data product. To understand the performance of those data depends on our skills in quantifying the impacts of the secondary parameters, such as surface roughness of snow and ice surfaces and the penetration depth of the snow/ice by the radar. To this end, we analyze airborne radar and lidar altimeter data collected during a Cryosat-2 under-flight by the NRL and the NASA IceBridge missions, as well as the in-situ data from the coordinated CRREL/NRL field campaign. In this presentation we will show some surface roughness data from airborne LIDAR for leveled and deformed first year ice, and ice pressure ridges. Their impacts on radar returns and sea ice thickness retrieval will be presented.

  15. Bistatic lidar measurements of clouds in the Nordic Arctic region.

    PubMed

    Olofson, K Frans G; Witt, Georg; Pettersson, Jan B C

    2008-09-10

    Cloud studies were carried out with a polarimetric bistatic lidar setup at the Arctic Lidar Observatory for Middle Atmosphere Research in Andenes (69 degrees N, 16 degrees E), Norway. Measurements were performed at altitudes between 1.5 and 10.5 km, corresponding to scattering angles between 130 degrees and 170 degrees. The geometry, not restricted to the parallel or perpendicular laser polarization directions, gave a well-defined scattering angle, which together with polarization characterization, was used to investigate the scattering particles. The principles of the technique and the first results are presented together with an evaluation of the capabilities. PMID:18784783

  16. Study of Droplet Activation in Thin Clouds Using Ground-based Raman Lidar and Ancillary Remote Sensors

    NASA Astrophysics Data System (ADS)

    Rosoldi, Marco; Madonna, Fabio; Gumà Claramunt, Pilar; Pappalardo, Gelsomina

    2015-04-01

    Studies on global climate change show that the effects of aerosol-cloud interactions (ACI) on the Earth's radiation balance and climate, also known as indirect aerosol effects, are the most uncertain among all the effects involving the atmospheric constituents and processes (Stocker et al., IPCC, 2013). Droplet activation is the most important and challenging process in the understanding of ACI. It represents the direct microphysical link between aerosols and clouds and it is probably the largest source of uncertainty in estimating indirect aerosol effects. An accurate estimation of aerosol-clouds microphysical and optical properties in proximity and within the cloud boundaries represents a good frame for the study of droplet activation. This can be obtained by using ground-based profiling remote sensing techniques. In this work, a methodology for the experimental investigation of droplet activation, based on ground-based multi-wavelength Raman lidar and Doppler radar technique, is presented. The study is focused on the observation of thin liquid water clouds, which are low or midlevel super-cooled clouds characterized by a liquid water path (LWP) lower than about 100 gm-2(Turner et al., 2007). These clouds are often optically thin, which means that ground-based Raman lidar allows the detection of the cloud top and of the cloud structure above. Broken clouds are primarily inspected to take advantage of their discontinuous structure using ground based remote sensing. Observations are performed simultaneously with multi-wavelength Raman lidars, a cloud Doppler radar and a microwave radiometer at CIAO (CNR-IMAA Atmospheric Observatory: www.ciao.imaa.cnr.it), in Potenza, Southern Italy (40.60N, 15.72E, 760 m a.s.l.). A statistical study of the variability of optical properties and humidity in the transition from cloudy regions to cloud-free regions surrounding the clouds leads to the identification of threshold values for the optical properties, enabling the discrimination between clouds and cloudless regions. Furthermore, a statistical study of the Doppler radar moments allows to retrieve droplet size and vertical velocities close to the cloud base. First evidences of a correlation between updrafts and downdrafts and aerosol effective radius have been found.

  17. Cloud Coverage and Height Distribution from the GLAS Polar Orbiting Lidar: Comparison to Passive Cloud Retrievals

    NASA Technical Reports Server (NTRS)

    Spinhime, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.

    2004-01-01

    The Geoscience Laser Altimeter System (GLAS) began full on orbit operations in September 2003. A main application of the two-wavelength GLAS lidar is highly accurate detection and profiling of global cloud cover. Initial analysis indicates that cloud and aerosol layers are consistently detected on a global basis to cross-sections down to 10(exp -6) per meter. Images of the lidar data dramatically and accurately show the vertical structure of cloud and aerosol to the limit of signal attenuation. The GLAS lidar has made the most accurate measurement of global cloud coverage and height to date. In addition to the calibrated lidar signal, GLAS data products include multi level boundaries and optical depth of all transmissive layers. Processing includes a multi-variable separation of cloud and aerosol layers. An initial application of the data results is to compare monthly cloud means from several months of GLAS observations in 2003 to existing cloud climatologies from other satellite measurement. In some cases direct comparison to passive cloud retrievals is possible. A limitation of the lidar measurements is nadir only sampling. However monthly means exhibit reasonably good global statistics and coverage results, at other than polar regions, compare well with other measurements but show significant differences in height distribution. For polar regions where passive cloud retrievals are problematic and where orbit track density is greatest, the GLAS results are particularly an advance in cloud cover information. Direct comparison to MODIS retrievals show a better than 90% agreement in cloud detection for daytime, but less than 60% at night. Height retrievals are in much less agreement. GLAS is a part of the NASA EOS project and data products are thus openly available to the science community (see http://glo.gsfc.nasa.gov).

  18. Observations of High-Level Cirrus Clouds by the NOAA Depolarization Lidar During Nauru99

    Microsoft Academic Search

    J. M. Intrieri; S. Sandberg

    During the Nauru99 field campaign, the National Oceanic and Atmospheric Administration's (NOAA's) depolarization and backscatter lidar (DABUL) obtained cloud data from aboard the research vessel Ron Brown. This lidar system, which obtains information on cloud occurrence and phase, documented a variety of cloud scenarios: boundary layer water clouds; mid-level, mixed-phase cloud systems with precipitation; and high-altitude ice phase cirrus clouds.

  19. Report on the Radar/PIREP Cloud Top Discrepancy Study

    NASA Technical Reports Server (NTRS)

    Wheeler, Mark M.

    1997-01-01

    This report documents the results of the Applied Meteorology Unit's (AMU) investigation of inconsistencies between pilot reported cloud top heights and weather radar indicated echo top heights (assumed to be cloud tops) as identified by the 45 Weather Squadron (45WS). The objective for this study is to document and understand the differences in echo top characteristics as displayed on both the WSR-88D and WSR-74C radars and cloud top heights reported by the contract weather aircraft in support of space launch operations at Cape Canaveral Air Station (CCAS), Florida. These inconsistencies are of operational concern since various Launch Commit Criteria (LCC) and Flight Rules (FR) in part describe safe and unsafe conditions as a function of cloud thickness. Some background radar information was presented. Scan strategies for the WSR-74C and WSR-88D were reviewed along with a description of normal radar beam propagation influenced by the Effective Earth Radius Model. Atmospheric conditions prior to and leading up to both launch operations were detailed. Through the analysis of rawinsonde and radar data, atmospheric refraction or bending of the radar beam was identified as the cause of the discrepancies between reported cloud top heights by the contract weather aircraft and those as identified by both radars. The atmospheric refraction caused the radar beam to be further bent toward the Earth than normal. This radar beam bending causes the radar target to be displayed erroneously, with higher cloud top heights and a very blocky or skewed appearance.

  20. A High Resolution Hydrometer Phase Classifier Based on Analysis of Cloud Radar Doppler Spectra.

    SciTech Connect

    Luke,E.; Kollias, P.

    2007-08-06

    The lifecycle and radiative properties of clouds are highly sensitive to the phase of their hydrometeors (i.e., liquid or ice). Knowledge of cloud phase is essential for specifying the optical properties of clouds, or else, large errors can be introduced in the calculation of the cloud radiative fluxes. Current parameterizations of cloud water partition in liquid and ice based on temperature are characterized by large uncertainty (Curry et al., 1996; Hobbs and Rangno, 1998; Intriery et al., 2002). This is particularly important in high geographical latitudes and temperature ranges where both liquid droplets and ice crystal phases can exist (mixed-phase cloud). The mixture of phases has a large effect on cloud radiative properties, and the parameterization of mixed-phase clouds has a large impact on climate simulations (e.g., Gregory and Morris, 1996). Furthermore, the presence of both ice and liquid affects the macroscopic properties of clouds, including their propensity to precipitate. Despite their importance, mixed-phase clouds are severely understudied compared to the arguably simpler single-phase clouds. In-situ measurements in mixed-phase clouds are hindered due to aircraft icing, difficulties distinguishing hydrometeor phase, and discrepancies in methods for deriving physical quantities (Wendisch et al. 1996, Lawson et al. 2001). Satellite-based retrievals of cloud phase in high latitudes are often hindered by the highly reflecting ice-covered ground and persistent temperature inversions. From the ground, the retrieval of mixed-phase cloud properties has been the subject of extensive research over the past 20 years using polarization lidars (e.g., Sassen et al. 1990), dual radar wavelengths (e.g., Gosset and Sauvageot 1992; Sekelsky and McIntosh, 1996), and recently radar Doppler spectra (Shupe et al. 2004). Millimeter-wavelength radars have substantially improved our ability to observe non-precipitating clouds (Kollias et al., 2007) due to their excellent sensitivity that enables the detection of thin cloud layers and their ability to penetrate several non-precipitating cloud layers. However, in mixed-phase clouds conditions, the observed Doppler moments are dominated by the highly reflecting ice crystals and thus can not be used to identify the cloud phase. This limits our ability to identify the spatial distribution of cloud phase and our ability to identify the conditions under which mixed-phase clouds form.

  1. Validating Lidar Depolorization Calibration using Solar Radiation Scattered by Ice Clouds

    NASA Technical Reports Server (NTRS)

    Liu, Zhao-Yang; McGill, Matthew; Hu, Yong-Xiang; Hostetter, Chris; Winker, David; Vaughan, Mark

    2004-01-01

    This letter proposes the use of solar background radiation scattered by ice clouds for validating space lidar depolarization calibration. The method takes advantage of the fact that the background light scattered by ice clouds is almost entirely unpolarized. The theory is examined with Cloud Physics Lidar (CPL) background light measurements.

  2. W-band ARM Cloud Radar (WACR) Handbook

    SciTech Connect

    Widener, KB; Johnson, K

    2005-01-05

    The W-band Atmospheric Radiation Measurement (ARM) Program Cloud Radar (WACR) systems are zenith pointing Doppler radars that probe the extent and composition of clouds at 95.04 GHz. The main purpose of this radar is to determine cloud boundaries (e.g., cloud bottoms and tops). This radar reports estimates for the first three spectra moments for each range gate up to 15 km. The 0th moment is reflectivity, the 1st moment is radial velocity, and the 2nd moment is spectral width. Also available are the raw spectra files. Unlike the millimeter wavelength cloud radar (MMCR), the WACR does not use pulse coding and operates in only copolarization and cross-polarization modes.

  3. Global estimation of above-cloud aerosols using spaceborne LIDAR

    NASA Astrophysics Data System (ADS)

    Chand, D.; Wood, R.; Anderson, T. L.; Satheesh, S. K.; Leahy, L.

    2008-12-01

    Estimates of global mean direct climate forcing by absorbing aerosols located above boundary layer clouds are large, uncertain, and almost entirely unconstrained by observations. Spaceborne lidar offers a new opportunity of estimating the aerosols at global scale. Here we use two recently available techniques quantifying the above-cloud aerosols using liquid water clouds as lidar targets from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) [Chand et al., 2008]. Both methods can quantify aerosols above clouds and are based on their self-calibrating techniques. We used one year of global data between 70N-70S to show that day time calibration constants are different than night time calibrations constants. A clear latitudinal dependence is observed in the calibrations constants in CALIPSO observations. Using these 'self-calibration' constants, aerosol optical depth (AOD) and angstrom exponent (AE) of 'above- cloud' aerosols are quantified. Biomass burning is a major source of fine mode aerosols in different regions of world. For example, it is observed that June is the onset of the biomass burning fires in Southern Africa, peaking in August and September and then slowly decreasing until November, with a corresponding signature in aerosol optical depth. Layers with aerosol optical depth greater than 0.3 are commonly observed up to several thousand kilometers away from Africa over the Atlantic Ocean. The 'above-cloud' AOD as high as 1.5 is observed in the peak months. Despite of large variations is AOD, mean AE of these aerosols is about 1.6, without any systematic variability away from the source region. The results estimating the aerosols above clouds, including other regions at global scale, will be presented in the AGU meeting. Chand, D., T. L. Anderson, R. Wood, R. J. Charlson, Y. Hu, Z. Liu, and M. Vaughan (2008), Quantifying above-cloud aerosol using spaceborne lidar for improved understanding of cloudy-sky direct climate forcing, J. Geophys. Res., 113, D13206, doi:10.1029/2007JD009433.

  4. UNCERTAINTIES OF RADAR-DERIVED VERTICAL VELOCITIES IN DEEP CONVECTIVE CLOUDS USING ARM PRECIPITATION RADARS

    E-print Network

    UNCERTAINTIES OF RADAR-DERIVED VERTICAL VELOCITIES IN DEEP CONVECTIVE CLOUDS USING ARM PRECIPITATION RADARS Kirk North, McGill University Scott Collis, Argonne National Laboratory Scott Giangrande of the new ARRA enhanced radar networks is to provide such measurements routinely. The retrieval approach

  5. Lidar Observations of the Optical Properties and 3-Dimensional Structure of Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Eloranta, E. W.

    1996-01-01

    The scientific research conducted under this grant have been reported in a series of journal articles, dissertations, and conference proceedings. This report consists of a compilation of these publications in the following areas: development and operation of a High Spectral Resolution Lidar, cloud physics and cloud formation, mesoscale observations of cloud phenomena, ground-based and satellite cloud cover observations, impact of volcanic aerosols on cloud formation, visible and infrared radiative relationships as measured by satellites and lidar, and scattering cross sections.

  6. Enhanced Simulation of Radar Backscatter From Forests Using LiDAR and Optical Data

    Microsoft Academic Search

    Richard M. Lucas; Alex C. Lee; Mark L. Williams

    2006-01-01

    Focusing on a forest dominated by Poplar Box (Eucalyptus populnea) near Injune in Queensland, Australia, light detection and ranging (LiDAR) and optical remote sensing data are integrated with tree- and stand-level information to parameterize a coherent L-band synthetic aperture radar (SAR) imaging simulation that models microwave penetration and interaction with the canopy, understory, and ground. The approach used LiDAR data

  7. Observations of mesospheric sporadic sodium layers with the MU radar and sodium lidars

    Microsoft Academic Search

    Hirohisa Miyagawa; Takuji Nakamura; Toshitaka Tsuda; Makoto Abo; Chikao Nagasawa; T. D. Kawahara; Keiji Kobayashi; Tsukasa Kitahara; Akio Nomura

    1999-01-01

    The dynamical structure of the atmosphere around the sporadic sodium layer at mid-latitude (~35°N) below 100 km was studied by simultaneous observation with the MU radar at Shigaraki (34.9°N, 136.1°E), and two Na lidars at Shigaraki and in Hachioji (35.6°N, 139.4°E). In the lidar data, fifteen NAS (sporadic sodium layer) events were detected. Wind shear, temperature, and stability indices, at

  8. Comparison of CloudSat and TRMM radar reflectivities

    NASA Astrophysics Data System (ADS)

    Sindhu, K. D.; Bhat, G. S.

    2013-08-01

    Comparison of reflectivity data of radars onboard CloudSat and TRMM is performed using coincident overpasses. The contoured frequency by altitude diagrams (CFADs) are constructed for two cases: (a) only include collocated vertical profiles that are most likely to be raining and (b) include all collocated profiles along with cloudy pixels falling within a distance of about 50 km from the centre point of coincidence. Our analysis shows that for both cases, CloudSat underestimates the radar reflectivity by about 10 dBZ compared to that of TRMM radar below 15 km altitude. The difference is well outside the uncertainty value of ~2 dBZ of each radar. Further, CloudSat reflectivity shows a decreasing trend while that of TRMM radar an increasing trend below 4 km height. Basically W-band radar that CloudSat flies suffers strong attenuation in precipitating clouds and its reflectivity value rarely exceeds 20 dBZ though its technical specification indicates the upper measurement limit to be 40 dBZ. TRMM radar, on the other hand, cannot measure values below 17 dBZ. In fact combining data from these two radars seems to give a better overall spatial structure of convective clouds.

  9. Balloonborne lidar for cloud physics studies

    NASA Astrophysics Data System (ADS)

    di Donfrancesco, Guido; Cairo, Francesco; Buontempo, Carlo; Adriani, Alberto; Viterbini, Maurizio; Snels, Marcel; Morbidini, Roberto; Piccolo, Francesco; Cardillo, Francesco; Pommereau, Jean-Pierre; Garnier, Anne

    2006-08-01

    An innovative balloonborne microjoule lidar (MULID) has been developed within the framework of the HIBISCUS project to provide nighttime measurements of visible and subvisible cirrus and aerosols. MULID has been designed to be a low-cost and an ultralow consumption instrument, due to the remote possibilities of payload recovery and the necessity of a low-weight battery power supply. Ground tests have been performed at the Observatory of Haute Provence (France), and the first technical flight has been made from Trapani, Italy, on a stratospheric balloon; finally, the instrument has been scientifically deployed during the pre-HIBISCUS and HIBISCUS tropical campaigns in Bauru, Brazil, in February 2003 and February 2004, respectively. A description of the instrument is provided together with the results of the ground-based and flight tests as well as an overview and discussion of the first results.

  10. High resolution retrieval of liquid water vertical distributions using collocated Ka-band and W-band cloud radars

    NASA Astrophysics Data System (ADS)

    Huang, Dong; Johnson, Karen; Liu, Yangang; Wiscombe, Warren

    2009-12-01

    The retrieval of cloud water content using dual-frequency radar attenuation is very sensitive to error in radar reflectivity. Either a long radar dwell time or an average over many range gates is needed to reduce random noise in radar data and thus to obtain accurate retrievals - but at the cost of poorer temporal and spatial resolution. In this letter we have shown that, by using advanced mathematical inversion techniques like total variation regularization, vertically resolved liquid water content can be retrieved at an accuracy of about 0.15 gm-3 at 40 m resolution. This is demonstrated using the co-located Ka-band and W-band cloud radars operated by the Atmospheric Radiation Measurement program. The liquid water path calculated from the radars agrees closely with that from a microwave radiometer, with a mean difference of 70 gm-2. Comparison with lidar observations reveals that the dual-frequency retrieval also reasonably captures the cloud base height of drizzling clouds - something that is very difficult to determine from radar reflectivity alone.

  11. Lidar observations of polar stratospheric clouds at Andoya, Norway, in January 1992

    SciTech Connect

    Schaefer, H.J.; Scheuch, P.; Langer, M.; Fricke, K.H.; Zahn, U. von (Physikalisches Institut der Universitaet, Bonn (Germany)); Knudsen, B.M. (DMI Copenhagen (Denmark))

    1994-06-22

    This paper reports on lidar measurements of polar stratospheric clouds above Andoya, Norway (69[degrees]N) during January 1992. On one day the cloud seemed to be just forming. One two days the clouds showed characteristics of type 1a clouds. The fourth observation showed the cloud formed within the altitude band where significant aerosol products from the Pinatubo volcanic eruption were present.

  12. Retrieving Optical Depths and Lidar Ratios for Transparent Layers Above Opaque Water Clouds From CALIPSO Lidar Measurements

    Microsoft Academic Search

    Yongxiang Hu; Mark Vaughan; Zhaoyan Liu; Kathleen Powell; Sharon Rodier

    2007-01-01

    For measurements that are made by the CALIPSO lidar, the layer-integrated attenuated backscatter of opaque water clouds gamma'water,O can be accurately estimated for those cases for which there is no overlying aerosol or cloud layer. When transparent overlying layers of clouds or aerosols are present, the layer-integrated attenuated backscatter that is measured for the water cloud is reduced by a

  13. GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/, Global verification of cloud fraction in models using CloudSat

    E-print Network

    Hogan, Robin

    . In this paper, the spaceborne CloudSat radar and CALIPSO lidar are used to evaluate the global distribution of the cloud radiative feedback varying significantly between models [Randall et al., 2007]. Spaceborne cloud radar and lidar [Stephens et al., 2002] are revolutionizing our ability to test the representation

  14. On Integrating Cloud-Radar-Derived Arctic Ice Cloud Properties into the Radiative Transfer Model "Streamer" 1.Introduction

    E-print Network

    Zuidema, Paquita

    On Integrating Cloud-Radar-Derived Arctic Ice Cloud Properties into the Radiative Transfer Model "Streamer" 1.Introduction Millimeter-wavelength cloud radars can potentially provide a vast dataset on ice cloud optical properties.The problem arises, however,of how best to integrate the radar-retrieved ice

  15. Radar Evaluation of Optical Cloud Constraints to Space Launch Operations

    NASA Technical Reports Server (NTRS)

    Merceret, Francis J.; Short, David A.; Ward, Jennifer G.

    2005-01-01

    Weather constraints to launching space vehicles are designed to prevent loss of the vehicle or mission due to weather hazards (See, e.g., Ref 1). Constraints include Lightning Launch Commit Criteria (LLCC) designed to avoid natural and triggered lightning. The LLCC currently in use at most American launch sites including the Eastern Range and Kennedy Space Center require the Launch Weather Officer to determine the height of cloud bases and tops, the location of cloud edges, and cloud transparency. The preferred method of making these determinations is visual observation, but when that isn't possible due to darkness or obscured vision, it is permissible to use radar. This note examines the relationship between visual and radar observations in three ways: A theoretical consideration of the relationship between radar reflectivity and optical transparency. An observational study relating radar reflectivity to cloud edge determined from in-situ measurements of cloud particle concentrations that determine the visible cloud edge. An observational study relating standard radar products to anvil cloud transparency. It is shown that these three approaches yield results consistent with each other and with the radar threshold specified in Reference 2 for LLCC evaluation.

  16. BUILDING ROOF SEGMENTATION AND RECONSTRUCTION FROM LIDAR POINT CLOUDS USING CLUSTERING TECHNIQUES

    E-print Network

    Shan, Jie

    . INTRODUCTION Extracting interest features from an airborne Laser (or LiDAR) point cloud is not a trivial task building types using the raw laser scanning data. Data-driven methods do not assume any underlying buildingBUILDING ROOF SEGMENTATION AND RECONSTRUCTION FROM LIDAR POINT CLOUDS USING CLUSTERING TECHNIQUES

  17. Mie lidar observations of lower tropospheric aerosols and clouds.

    PubMed

    Veerabuthiran, S; Razdan, A K; Jindal, M K; Dubey, D K; Sharma, R C

    2011-12-15

    Mie lidar system is developed at Laser Science and Technology Centre, Delhi (28.38°N, 77.12°E) by using minimal number of commercially available off-the-shelf components. Neodymium Yttrium Aluminum Garnet (Nd:YAG) laser operating at 1064nm with variable pulse energies between 25 and 400 mJ with 10 Hz repetition rate and 7ns pulse duration is used as a transmitter and off-axis CASSEGRAIN telescope with 100mm diameter as a receiver. Silicon avalanche photodiode (Si-APD) module with built-in preamplifier and front-end optics is used as detector. This system has been developed for the studies of lower tropospheric aerosols and clouds. Some experiments have been conducted using this set up and preliminary results are discussed. The characteristics of backscattered signals for various transmitter pulse energies are also studied. Atmospheric aerosol extinction coefficient values are calculated using Klett lidar inversion algorithm. The extinction coefficient, in general, falls with range in the lower troposphere and the values lie typically in the range 7.5×10(-5) m(-1) to 1.12×10(-4) m(-1) in the absence of any cloud whereas this value shoots maximum up to 1.267×10(-3) m(-1) (peak extinction) in the presence of clouds. PMID:21975046

  18. Mie lidar observations of lower tropospheric aerosols and clouds

    NASA Astrophysics Data System (ADS)

    Veerabuthiran, S.; Razdan, A. K.; Jindal, M. K.; Dubey, D. K.; Sharma, R. C.

    2011-12-01

    Mie lidar system is developed at Laser Science and Technology Centre, Delhi (28.38°N, 77.12°E) by using minimal number of commercially available off-the-shelf components. Neodymium Yttrium Aluminum Garnet (Nd:YAG) laser operating at 1064 nm with variable pulse energies between 25 and 400 mJ with 10 Hz repetition rate and 7 ns pulse duration is used as a transmitter and off-axis CASSEGRAIN telescope with 100 mm diameter as a receiver. Silicon avalanche photodiode (Si-APD) module with built-in preamplifier and front-end optics is used as detector. This system has been developed for the studies of lower tropospheric aerosols and clouds. Some experiments have been conducted using this set up and preliminary results are discussed. The characteristics of backscattered signals for various transmitter pulse energies are also studied. Atmospheric aerosol extinction coefficient values are calculated using Klett lidar inversion algorithm. The extinction coefficient, in general, falls with range in the lower troposphere and the values lie typically in the range 7.5 × 10 -5 m -1 to 1.12 × 10 -4 m -1 in the absence of any cloud whereas this value shoots maximum up to 1.267 × 10 -3 m -1 (peak extinction) in the presence of clouds.

  19. COMPARISON OF MILLIMETER-WAVE CLOUD RADAR MEASUREMENTS FOR THE FALL 1997 CLOUD IOP

    SciTech Connect

    SEKELSKY,S.M.; LI,L.; GALLOWAY,J.; MCINTOSH,R.E.; MILLER,M.A.; CLOTHIAUX,E.E.; HAIMOV,S.; MACE,G.; SASSEN,K.

    1998-03-23

    One of the primary objectives of the Fall 1997 IOP was to intercompare Ka-band (35GHz) and W-band (95GHz) cloud radar observations and verify system calibrations. During September 1997, several cloud radars were deployed at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site, including the full time operation 35 GHz CART Millimeter-wave Cloud Radar (MMCR), (Moran, 1997), the University of Massachusetts (UMass) single antenna 33GHz/95 GHz Cloud Profiling Radar System (CPRS), (Sekelsky, 1996), the 95 GHz Wyoming Cloud Radar (WCR) flown on the University of Wyoming King Air (Galloway, 1996), the University of Utah 95 GHz radar and the dual-antenna Pennsylvania State University 94 GHz radar (Clothiaux, 1995). In this paper the authors discuss several issues relevant to comparison of ground-based radars, including the detection and filtering of insect returns. Preliminary comparisons of ground-based Ka-band radar reflectivity data and comparisons with airborne radar reflectivity measurements are also presented.

  20. First detection of a noctilucent cloud by lidar

    SciTech Connect

    Hansen, G.; Serwazi, M.; von Zahn, U. (Universitaet Bonn (West Germany))

    1989-12-01

    During the night of August 5/6, 1989 for the first time a noctilucent cloud (NLC) was detected and measured by a lidar instrument. The observations were made with ground-based narrow-band Na lidar located at Andenes, Norway (69{degree}N, 16{degree}E geographic coordinates). In wavelength the lidar was operated both at the Na D{sub 2} resonance line of 589 nm as well as 5 Doppler widths shifted away. The altitude resolution was 200 m. The NLC developed at about 22:20 UT, reached its maximum backscatter cross section at 23:05 UT and became unobservable at around 00:10 UT. During this period the NLC exhibited the following properties: (a) its altitude ranged between 83.4 and 82.2 km; (b) its full width at half maximum ranged between 1.4 and 0.3 km; (c) the ratio of measured backscatter intensity from the NLC to the calculated Rayleigh signal from 82.6 km reached 450; (d) its volume backscatter cross section maximized at 6.5 {times} 10{sup {minus}9} m{sup {minus}1} sr{sup {minus}1}.

  1. Spaceborne precipitation radar simulation from a global cloud resolving model

    NASA Astrophysics Data System (ADS)

    Leinonen, J. S.; Lebsock, M. D.; Suzuki, K.; Yashiro, H.; Miyamoto, Y.

    2014-12-01

    The ability of spaceborne radars to detect and measure clouds and precipitation globally is affected by their inherent sensitivity limits, by attenuation of the microwave radiation in the atmosphere, and by variability of the precipitation over scales smaller than the radar footprint. Effective design of radars and the interpretation of their measurements require that the influence of these phenomena on their performance be quantified. Such quantification is hindered by the incompleteness of the existing reference measurements. Simulation of radar observations from atmospheric models can be used as an alternative to direct measurements, but most models either operate on a local scale and are thus not globally representative, or else are too coarse in their resolution to simulate sub-footprint scale phenomena. This gap is currently being bridged by global cloud resolving models, which simulate the entire atmosphere at scales approaching that of individual clouds. We have simulated spaceborne radar measurements globally from a run of the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) at a resolution of 800 m. A radar single scattering model was developed for each of the five NICAM cloud and precipitation particle classes: cloud ice, cloud water, rain, snow and graupel, retaining consistency with the model microphysics assumptions. Additionally, regions with melting snowflakes were considered separately, as they have a pronounced effect on radar observations. The results of the single scattering calculations were then used in a time-dependent radiative transfer model in order to simulate attenuation and multiple scattering effects. Finally, the simulated observations were spatially averaged to reproduce the effect of a radar footprint larger than a single grid point. Using this approach, we can estimate the performance of various radar configurations in current and future Earth observing satellite missions.

  2. New Cloud Science from the New ARM Cloud Radar Systems (Invited)

    NASA Astrophysics Data System (ADS)

    Wiscombe, W. J.

    2010-12-01

    The DOE ARM Program is deploying over $30M worth of scanning polarimetric Doppler radars at its four fixed and two mobile sites, with the object of advancing cloud lifecycle science, and cloud-aerosol-precipitation interaction science, by a quantum leap. As of 2011, there will be 13 scanning radar systems to complement its existing array of profiling cloud radars: C-band for precipitation, X-band for drizzle and precipitation, and two-frequency radars for cloud droplets and drizzle. This will make ARM the world’s largest science user of, and largest provider of data from, ground-based cloud radars. The philosophy behind this leap is actually quite simple, to wit: dimensionality really does matter. Just as 2D turbulence is fundamentally different from 3D turbulence, so observing clouds only at zenith provides a dimensionally starved, and sometimes misleading, picture of real clouds. In particular, the zenith view can say little or nothing about cloud lifecycle and the second indirect effect, nor about aerosol-precipitation interactions. It is not even particularly good at retrieving the cloud fraction (no matter how that slippery quantity is defined). This talk will review the history that led to this development and then discuss the aspirations for how this will propel cloud-aerosol-precipitation science forward. The step by step plan for translating raw radar data into information that is useful to cloud and aerosol scientists and climate modelers will be laid out, with examples from ARM’s recent scanning cloud radar deployments in the Azores and Oklahoma . In the end, the new systems should allow cloud systems to be understood as 4D coherent entities rather than dimensionally crippled 2D or 3D entities such as observed by satellites and zenith-pointing radars.

  3. Research of Cloud Temperature and Optical Depth Using Rotational-Vibrational Raman Lidar

    NASA Astrophysics Data System (ADS)

    Su, J.; McCormick, M. P.; Lei, L.

    2014-12-01

    The study of clouds plays a key role in the understanding of climate change. Reliable measurements of cloud temperature and optical depth are important for improving our understanding of cloud physics, cloud dynamics, and for validating cloud-resolving models. Raman Lidars have been proven to be a very useful remote sensing tool to measure cloud properties. In the paper, cloud temperature and optical depth are respectively obtained using rotational Raman technique and vibrational Raman technique. Results of cloud temperature and optical depth observed by the Hampton University (HU) Rotational-Vibrational Raman Lidar are presented. The paper emphatically discusses the influence of cloud optical depth on temperature of cloud base and top. From these measurements, the relation of low-altitude cloud optical depth and temperature is summarized. These analyses are unique in that they combine simultaneous measurements of these quantities that can lead to an improvement in the understanding of cloud radiation transfer and prediction of local weather.

  4. A numerical technique for the calculation of cloud optical extinction from lidar

    NASA Technical Reports Server (NTRS)

    Alvarez, J. M.; Vaughan, M. A.

    1993-01-01

    A simple numerical algorithm which calculates optical extinction from cloud lidar data is presented. The method assumes a two-component atmosphere consisting of 'clear air' and cloud particulates. 'Clear air' may consist of either molecules only or a mix of molecules and atmospheric aerosols. For certain clouds, the method may be utilized to provide an estimate of the cloud-atmospheric parameter defined as the ratio of the cloud volume backscatter coefficient to the cloud extinction coefficient divided by the atmospheric volume backscatter coefficient at a given altitude. The cloud-atmospheric parameter may be estimated only from cloud data from which the optical thickness may reliably be used as a constraint on the numerical solution. This constraint provides the additional information necessary to obtain the cloud-atmospheric parameter. Conversely, the method may be applied to obtain cloud extinction and optical thickness from lidar cloud soundings if an estimate of the cloud-atmospheric parameter is available.

  5. Lidar measurements of boundary layers, aerosol scattering and clouds during project FIFE

    NASA Technical Reports Server (NTRS)

    Eloranta, Edwin W. (Principal Investigator)

    1995-01-01

    A detailed account of progress achieved under this grant funding is contained in five journal papers. The titles of these papers are: The calculation of area-averaged vertical profiles of the horizontal wind velocity using volume imaging lidar data; Volume imaging lidar observation of the convective structure surrounding the flight path of an instrumented aircraft; Convective boundary layer mean depths, cloud base altitudes, cloud top altitudes, cloud coverages, and cloud shadows obtained from Volume Imaging Lidar data; An accuracy analysis of the wind profiles calculated from Volume Imaging Lidar data; and Calculation of divergence and vertical motion from volume-imaging lidar data. Copies of these papers form the body of this report.

  6. Reconstruction of 3-D cloud geometry using a scanning cloud radar

    NASA Astrophysics Data System (ADS)

    Ewald, F.; Winkler, C.; Zinner, T.

    2014-11-01

    Clouds are one of the main reasons of uncertainties in the forecasts of weather and climate. In part, this is due to limitations of remote sensing of cloud microphysics. Present approaches often use passive spectral measurements for the remote sensing of cloud microphysical parameters. Large uncertainties are introduced by three dimensional (3-D) radiative transfer effects and cloud inhomogeneities. Such effects are largely caused by unknown orientation of cloud sides or by shadowed areas on the cloud. Passive ground based remote sensing of cloud properties at high spatial resolution could be improved crucially with this kind of additional knowledge of cloud geometry. To this end, a method for the accurate reconstruction of 3-D cloud geometry from cloud radar measurements is developed in this work. Using a radar simulator and simulated passive measurements of static LES model clouds, the effects of different radar scan resolutions and varying interpolation methods are evaluated. In reality a trade-off between scan resolution and scan duration has to be found as clouds are changing quickly. A reasonable choice is a scan resolution of 1 to 2°. The most suitable interpolation procedure identified is the barycentric interpolation method. The 3-D reconstruction method is demonstrated using radar scans of convective cloud cases with the Munich miraMACS, a 35 GHz scanning cloud radar. As a successful proof of concept, camera imagery collected at the radar location is reproduced for the observed cloud cases via 3-D volume reconstruction and 3-D radiative transfer simulation. Data sets provided by the presented reconstruction method will aid passive spectral ground-based measurements of cloud sides to retrieve microphysical parameters.

  7. Interpretation of cirrus cloud properties using coincident satellite and lidar data during the FIRE cirrus IFO

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Alvarez, Joseph M.; Young, David F.; Sassen, Kenneth; Grund, Christian J.

    1990-01-01

    The First ISCCP Regional Experiment (FIRE) Cirrus Intensive Field Observations (IFO) provide an opportunity to examine the relationships between the satellite observed radiances and various parameters which describe the bulk properties of clouds, such as cloud amount and cloud top height. Lidar derived cloud altitude data, radiosonde data, and satellite observed radiances are used to examine the relationships between visible reflectance, infrared emittance, and cloud top temperatures for cirrus clouds.

  8. A 94 GHz spaceborne cloud profiling radar antenna system

    Microsoft Academic Search

    S. Spitz; J. Harrell; R. Perez; W. Veruttipong

    2001-01-01

    The CloudSat spacecraft, scheduled to launch in 2003, will carry a 94 GHz cloud profiling radar. The electrical design of its antenna system has been completed and is presented here. It consists of a quasi-optical transmission line that performs signal relaying and duplexing (using a Faraday rotator), and a collimating antenna that provides the required gain and spatial resolution. A

  9. NOTES AND CORRESPONDENCE CloudSat as a Global Radar Calibrator

    E-print Network

    Protat, Alain

    May 2010) ABSTRACT The calibration of the CloudSat spaceborne cloud radar has been thoroughly assessedNOTES AND CORRESPONDENCE CloudSat as a Global Radar Calibrator A. PROTAT,*,1 D. BOUNIOL,# E. J. O backscatter at 94 GHz, direct comparisons with airborne cloud radars, and statistical comparisons with ground

  10. Radar based remote sensing of cloud liquid water—application of various techniques—a case study

    NASA Astrophysics Data System (ADS)

    Meywerk, J.; Quante, M.; Sievers, O.

    2005-05-01

    During the BALTEX BRIDGE Campaign (BBC) of CLIWA-NET, conducted at Cabauw, The Netherlands, from 1 August through 31 September 2001, cloud radar parameters like reflectivity, linear depolarization ratio and Doppler velocities have been observed using a 95 GHz cloud radar. These observations along with other remotely sensed parameters from the ground, have been used to derive the liquid water content of clouds which is one of the most important parameters to be known when the radiative transfer of clouds needs to be calculated. Simultaneously a multi-channel passive microwave radiometer and a lidar ceilometer have been operated close to the radar. While drizzle could be ruled out to have a significant impact on the return signal, corrections due to atmospheric absorption (gaseous) and attenuation due to clouds (mainly loss of signal due to absorption) had to be applied to the radar data. The corrections will be discussed in detail and have been applied to the radar reflectivity profiles before estimating cloud liquid water profiles. After the liquid water content profile has been calculated (for a fixed integrated liquid water path) the maximum in liquid water content of the cloud increased by about 14% and shifted upward within the cloud. The applied corrections bring the liquid water profile closer to adiabatic in the middle and upper part of the cloud. Examples of time series of corrected vertical profiles and average profiles are shown and are discussed. The ground based remotely sensed liquid water profiles show, on average, excellent agreement with simultaneously in situ measured liquid water content from aircraft measurements.

  11. Assessment of Cloudsat Reflectivity Measurements and Ice Cloud Properties Using Ground-Based and Airborne Cloud Radar Observations

    E-print Network

    Protat, Alain

    -based radar calibration accuracy is about 1 dB, it is concluded that the reflectivities of the spaceborne-Based and Airborne Cloud Radar Observations A. PROTAT,* D. BOUNIOL,1 J. DELANOE¨ ,# P. T. MAY,@ A. PLANA-FATTORI,& A backscatter and ice cloud reflectivities measured by an airborne cloud radar and Cloudsat during two field

  12. Time Shifted PN Codes for CW Lidar, Radar, and Sonar

    NASA Technical Reports Server (NTRS)

    Campbell, Joel F. (Inventor); Prasad, Narasimha S. (Inventor); Harrison, Fenton W. (Inventor); Flood, Michael A. (Inventor)

    2013-01-01

    A continuous wave Light Detection and Ranging (CW LiDAR) system utilizes two or more laser frequencies and time or range shifted pseudorandom noise (PN) codes to discriminate between the laser frequencies. The performance of these codes can be improved by subtracting out the bias before processing. The CW LiDAR system may be mounted to an artificial satellite orbiting the earth, and the relative strength of the return signal for each frequency can be utilized to determine the concentration of selected gases or other substances in the atmosphere.

  13. Adaptive algorithms for the fully-automated retrieval of cloud and aerosol extinction profiles from CALIPSO lidar data

    Microsoft Academic Search

    Stuart A. Young; Mark A. Vaughan; David M. Winker

    2003-01-01

    The difficulties associated with the analysis of lidar data acquired from space are discussed. Novel methods to overcome these problems will be used in the analysis of lidar data from the Cloud Aerosol Lidar Pathfinder Satellite Observations (CALIPSO) (1) mission and are described here. The analysis of lidar data measured from space-based platforms is associated with difficulties not encountered to

  14. Lidar measurements of cloud extinction coefficient distribution and its forward scattering phase function according to multiply scattered lidar returns

    NASA Technical Reports Server (NTRS)

    Qiu, Jinhuan; Huang, Qirong

    1992-01-01

    The study of the inversion algorithm for the single scatter lidar equation, for quantitative determination of cloud (or aerosol) optical properties, has received much attention over the last thirty years. Some of the difficulties associated with the solution of this equation are not yet solved. One problem is that a single scatter lidar equation has two unknowns. Because of this, the determination of the far-end boundary value, in the case of Klett's algorithm, is a problem if the atmosphere is optically inhomogeneous. Another difficulty concerns multiple scattering. There is a large error in the extinction distribution solution, in many cases, if only the single scattering component is considered, while neglecting the multiple scattering component. However, the use of multiple scattering in the remote sensing of aerosol or cloud optical properties is promising. In our early study, an inversion method for simultaneous determination of the cloud (or aerosol) Extinction Coefficient Distribution (ECD) and its Forward Scattering Phase Function (FSPF) was proposed according to multiply scattered lidar returns with two fields of view for the receiver. The method is based on a parameterized multiple scatter lidar equation. This paper is devoted to further numerical tests and an experimental study of lidar measurements of cloud ECD and FSPF using this method.

  15. Validation of aerosol and cloud layer structures from the space-borne lidar CALIOP using Seoul National University ground-based lidar

    Microsoft Academic Search

    S.-W. Kim; S. Berthier; P. Chazette; J.-C. Raut; F. Dulac; S.-C. Yoon

    2007-01-01

    We present first observationally based validations of the space-borne lidar CALIOP onboard CALIPSO satellite using coincidental observations from a ground-based SNU lidar for 3 different types of atmospheric scenes. Both lidar measurements were taken in nearly same airmass in space and time. Total attenuated backscatters at 532 nm from the two instruments show similar aerosol and cloud layer structures (the

  16. Monte-Carlo calculations of cloud returns for ground-based and space-based LIDARS

    NASA Astrophysics Data System (ADS)

    Winker, D. M.; Poole, L. R.

    1995-04-01

    A Monte-Carlo model is described which has been developed for calculation of multiply scattered LIDAR returns. Results are shown for the common problem selected by the MUSCLE (MUltiple SCattering LIDAR Experiments) group for intercomparison, which represents a typical ground-based cloud-sensing scenario. This is contrasted with returns from the same cloud sensed by a space-based LIDAR, where multiple-scattering effects are much greater. The magnitude of multiple-scattering effects is seen to be largely determined by the optical depth across the receiver field of view at the cloud.

  17. Registration of vehicle based panoramic image and LiDAR point cloud

    NASA Astrophysics Data System (ADS)

    Chen, Changjun; Cao, Liang; Xie, Hong; Zhuo, Xiangyu

    2013-10-01

    Higher quality surface information would be got when data from optical images and LiDAR were integrated, owing to the fact that optical images and LiDAR point cloud have unique characteristics that make them preferable in many applications. While most previous works focus on registration of pinhole perspective cameras to 2D or 3D LiDAR data. In this paper, a method for the registration of vehicle based panoramic image and LiDAR point cloud is proposed. Using the translation among panoramic image, single CCD image, laser scanner and Position and Orientation System (POS) along with the GPS/IMU data, precise co-registration between the panoramic image and the LiDAR point cloud in the world system is achieved. Results are presented under a real world data set collected by a new developed Mobile Mapping System (MMS) integrated with a high resolution panoramic camera, two laser scanners and a POS.

  18. Lidar observations of sodium density depletions in the presence of polar mesospheric clouds

    Microsoft Academic Search

    Jeffrey P. Thayer; Weilin Pan

    2006-01-01

    Since 1997, sodium resonance lidar and Rayleigh lidar measurements have been conducted simultaneously at the Sondrestrom upper atmosphere research facility near Kangerlussuaq, Greenland (67.0°N, 309.1°E) for studying the arctic mesosphere. The summertime lidar observations during the typical polar mesospheric cloud (PMC) season from June through August are used to investigate changes in the mesospheric sodium layer related to the presence

  19. Lidar measurements of cirrus clouds, aerosols and dust at Chung-Li (25N,121E)

    Microsoft Academic Search

    J. B. Nee; C. W. Jian; A. Liang; W. N. Chen

    2003-01-01

    Dust, clouds, and aerosols in the 0-30 km have been measured by using a Mie scattering lidar at the National Central University in Chung-Li (25 N,121 E). The lidar system consists of a 532\\/1064 nm transmitter, two telescopes with diameters of 45 cm and 20 cm, and detector and signal analyses systems. NCU lidar system has been used to measure

  20. Scanning Cloud Radar Observations at the ARM sites

    NASA Astrophysics Data System (ADS)

    Kollias, P.; Clothiaux, E. E.; Shupe, M.; Widener, K.; Bharadwaj, N.; Miller, M. A.; Verlinde, H.; Luke, E. P.; Johnson, K. L.; Jo, I.; Tatarevic, A.; Lamer, K.

    2012-12-01

    Recently, the DOE Atmospheric Radiation Measurement (ARM) program upgraded its fixed and mobile facilities with the acquisition of state-of-the-art scanning, dual-wavelength, polarimetric, Doppler cloud radars. The scanning ARM cloud radars (SACR's) are the most expensive and significant radar systems at all ARM sites and eight SACR systems will be operational at ARM sites by the end of 2013. The SACR's are the primary instruments for the detection of 3D cloud properties (boundaries, volume cloud fractional coverage, liquid water content, dynamics, etc.) beyond the soda-straw (profiling) limited view. Having scanning capabilities with two frequencies and polarization allows more accurate probing of a variety of cloud systems (e.g., drizzle and shallow, warm rain), better correction for attenuation, use of attenuation for liquid water content retrievals, and polarimetric and dual-wavelength ratio characterization of non-spherical particles for improved ice crystal habit identification. Examples of SACR observations from four ARM sites are presented here: the fixed sites at Southern Great Plains (SGP) and North Slope of Alaska (NSA), and the mobile facility deployments at Graciosa Island, Azores and Cape Cod, Massachusetts. The 3D cloud structure is investigated both at the macro-scale (20-50 km) and cloud-scale (100-500 m). Doppler velocity measurements are corrected for velocity folding and are used either to describe the in-cloud horizontal wind profile or the 3D vertical air motions.

  1. Accuracy of biomass estimates from radar and lidar over temperate forests

    NASA Astrophysics Data System (ADS)

    Ahmed, R.; Siqueira, P. R.; Hensley, S.

    2011-12-01

    A better understanding of ecosystem processes requires accurate estimates of forest biomass and structure on global scales. Recently, there have been demonstrations of the ability of remote sensing instruments, such as radar and lidar, for the estimation of forest parameters from spaceborne platforms in a consistent manner. These advances can be exploited for global forest biomass accounting and structure characterization, leading to a better understanding of the global carbon cycle. The popular techniques for estimation of forest parameters from radar instruments in particular, use backscatter intensity, interferometry and polarimetric interferometry. In this paper we analyze the accuracy of biomass estimates over temperate forests of the North-Eastern United States from lidar and radar backscatter. We adopt an empirical approach, relying on ground truth data collected during DESDynI field campaigns over the Harvard and Howland Forests in 2009 and remote sensing data from LVIS, the GSFC full-waveform lidar and NASA JPL's L-band UAVSAR. UAVSAR collected data over the Harvard and Howland Forests during a deployment in 2009 where it was flown in a repeat-pass configuration collecting several fully polarimetric scenes. In a concurrent deployment of the GSFC LVIS instrument, full waveform lidar data was collected over the same region. Diameter and species information from fifteen hectares at the Harvard Forest and twenty three hectares at the Howland forest was collected during the July 2009 DESDynI field campaigns as well. We assess the accuracy of biomass estimates based on diameter measurements by using a classic statistical approach to characterize the impact of the diameter-biomass allometry at both field sites. Using a lidar error model and estimates of error in field biomass, we attempt to characterize the error in biomass estimates from common full waveform lidar metrics from LVIS data over the Harvard and Howland forests. Similarly, using a radar backscatter error model and data from UAVSAR, we analyze the accuracy of the backscatter-biomass relationship and characterize the uncertainty in biomass estimates from radar in a non-linear regression setting with measurement error. A discussion will be provided on the implications of this analysis on the design and science outcomes of the proposed DESDynI mission.

  2. Lidar remote sensing of aerosols and clouds from space

    Microsoft Academic Search

    D. Winker; J. Pelon

    2004-01-01

    Until recently, optical remote sensing from space has been performed using passive instruments. Active sensing by satellite lidars will soon add significant new capabilities for atmospheric sensing. The lidar technique is characterized by high vertical resolution and independence of lighting conditions. The Lidar In-space Technology Experiment (LITE) flew on the Space Shuttle in 1994 and demonstrated active sensing by lidar

  3. A 2year climatology of clouds at Eureka, Canada prepared from High Spectral Resolution lidar data.

    E-print Network

    Eloranta, Edwin W.

    A 2year climatology of clouds at Eureka, Canada prepared from High Spectral Resolution lidar data then at lower latitudes. Differences in cloud parametrization are the likely to be the main source because of a lack of reliable cloud observations. The Canadian Network for the Detection of Atmospheric

  4. Tropical and Midlatitude Cirrus Cloud Extinction and Backscatter From Multiyear Raman Lidar Measurements.

    NASA Astrophysics Data System (ADS)

    Thorsen, T. J.; Fu, Q.

    2014-12-01

    Lidars have the capability to provide unparalleled range-resolved observations of particulate extinction. However, lidars fundamentally measure backscattered energy, not extinction, and for widely prevalent single-channel elastic backscatter lidars extinction must be obtained by assuming a backscatter-extinction relationship. Our knowledge of this relationship, known as the lidar ratio, mainly consists values determined via the transmission-loss method: which can only provide layer-averaged values and is only applicable to a subset of all cloud layers. Directly-retrieved, vertically resolved extinction coefficients and lidar ratios are obtainable through the use of more advance high spectral resolution lidars (HSRL) or Raman lidars (RL). However, the complexity of operating a HSRL or RL has limited their use for cloud observations to very limited time periods: typical only a few months or less. In this work, we present a newly developed retrieval for the Atmospheric Radiation Measurement (ARM) program's Raman lidars for Feature detection and EXtinction retrieval (FEX). FEX improves upon existing ARM products by using multiple, complimentary quantities to identify both clouds and aerosols and retrieve their extinction and backscatter profiles. Multiple years of data are examined at both the Lamont, Oklahoma and Darwin, Australia ARM sites; providing the most comprehensive climatology to date of cirrus extinction and lidar ratios. Variations in these optical properties with classification of the synoptic state and their relationship with microphysical parameters (temperature, relative humidity and depolarization) are examined.

  5. Visually-Complete Aerial LiDAR Point Cloud Rendering Zhenzhen Gao

    E-print Network

    Shahabi, Cyrus

    and classification labels. Aerial LiDAR is gathered by mounting a downward-scanning laser on a low-flying aircraft Detection and Ranging) point clouds are gathered by a downward scanning laser on a low-flying aircraft. Due) is a terrain and urban information acquisition technique based on laser tech- nology. LiDAR data sets consist

  6. Vegetation profiles in tropical forests from multibaseline interferometric synthetic aperture radar, field, and lidar measurements

    Microsoft Academic Search

    R. N. Treuhaft; B. D. Chapman; J. R. dos Santos; F. G. Gonçalves; L. V. Dutra; P. M. L. A. Graça; J. B. Drake

    2009-01-01

    This paper addresses the estimation of vertical vegetation density profiles from multibaseline interferometric synthetic aperture radar (InSAR) data from the AirSAR aircraft at C band over primary, secondary, and abandoned-pasture stands at La Selva Biological Station, Costa Rica in 2004. Profiles were also estimated from field data taken in 2006 and lidar data taken with the LVIS, 25 m spot

  7. Metal and ion layers observed by resonance lidars and incoherent scatter radar at Arecibo

    Microsoft Academic Search

    J. S. Friedman; S. Raizada; C. A. Tepley; Q. Zhou; Y. Morton; M. P. Sulzer; S. A. Gonzalez

    2003-01-01

    Observations of the mesopause-region potassium and sodium layers using the resonance lidar technique have been carried out at the Arecibo Observatory (18.35oN, 66.75oW) for a number of years. These observations have often coincided with E-region observations by the incoherent scatter radar. In this presentation, we examine the seasonal and diurnal variability of K\\/Na\\/ion layer content and height. In particular, we

  8. A 3D Cloud-Construction Algorithm for the EarthCARE Satellite Mission

    NASA Technical Reports Server (NTRS)

    Barker, H. W.; Jerg, M. P.; Wehr, T.; Kato, S.; Donovan, D. P.; Hogan, R. J.

    2011-01-01

    This article presents and assesses an algorithm that constructs 3D distributions of cloud from passive satellite imagery and collocated 2D nadir profiles of cloud properties inferred synergistically from lidar, cloud radar and imager data.

  9. Polar Cirrus Cloud Properties Through Long-Term Lidar and Radiometer Observations

    NASA Technical Reports Server (NTRS)

    Spinhirne, James; Campbell, James; Mahesh, Ashwin; Welton, Judd; Starr, David OC. (Technical Monitor)

    2001-01-01

    In comparison to mid latitude cloud cover, knowledge of polar cirrus and other cloud cover is limited. The interpretations of satellite-based cloud imaging and retrievals in polar regions have major problems due to factors such as darkness and extreme low temperatures. Beginning in 2002 a NASA orbiting lidar instrument, GLAS, (Geoscience Laser Altimeter System) will unambiguously define cloud type and fraction with good coverage of polar regions. Active laser sensing gives the spatial and temporal distribution of clouds and diamond dust. In preparation for, and supplementing the GLAS measurements are ground based MP (micro pulse) lidar experiments providing continuous profiling. MP lidar installations have been operating at the South Pole since December 1999 and at the Atmospheric Radiation Measurement (ARM) program arctic site since 1996. Both at the ARM Barrow, Alaska site and at the South Pole station, Fourier-transform interferometers also observe clouds in the wavelength intervals between approximately 5 and 18 microns. Spectral instruments can yield cloud microphysical properties with additional information from lidar about the vertical extent of clouds being modeled. We examine the simultaneous lidar and spectral data from both Barrow and South Pole, to obtain cloud properties (optical depth, particle size) by the use of both instruments. The results have applications to interpretation of current satellite data, and GLAS measurements when available.

  10. A Qualitative Comparison between MISR and Cloud Radar Cloud Heights at the North Slope of Alaska ARM Site paquita.zuidema@noaa.gov

    E-print Network

    Zuidema, Paquita

    A Qualitative Comparison between MISR and Cloud Radar Cloud Heights at the North Slope of Alaska between cloud heights as perceived by a surface-based cloud radar located at Pt.Barrow,Alaska (71.2N,156 heights and winds are codetermined using a stereo-matching process.The cloud radar cloud heights

  11. Mixed-phase cloud phase partitioning using millimeter wavelength cloud radar Doppler velocity spectra

    NASA Astrophysics Data System (ADS)

    Yu, G.; Verlinde, J.; Clothiaux, E. E.; Chen, Y.-S.

    2014-06-01

    Retrieving and quantifying cloud liquid drop contributions to radar returns from mixed-phase clouds remains a challenge because the radar signal is frequently dominated by the returns from the ice particles within the radar sample volume. We present a technique that extracts the weak cloud liquid drop contributions from the total radar returns in profiling cloud radar Doppler velocity spectra. Individual spectra are first decomposed using a continuous wavelet transform, the resulting coefficients of which are used to identify the region in the spectra where cloud liquid drops contribute. By assuming that the liquid contribution to each Doppler spectrum is Gaussian shaped and centered on an appropriate peak in the wavelet coefficients, the cloud liquid drop contribution may be estimated by fitting a Gaussian distribution centered on the velocity of this peak to the original Doppler spectrum. The cloud liquid drop contribution to reflectivity, the volume mean vertical air motion, subvolume vertical velocity variance, and ice particle mean fall speed can be estimated based on the separation of the liquid contribution to the radar Doppler spectrum. The algorithm is evaluated using synthetic spectra produced from output of a state-of-the-art large eddy simulation model study of an Arctic mixed-phase cloud. The retrievals of cloud liquid drop mode reflectivities were generally consistent with the original model values with errors less than a factor of 2. The retrieved volume mean vertical air velocities reproduced the updraft and downdraft structures, but with an overall bias of approximately -0.06 m s-1. Retrievals based on Ka-band Atmospheric Radiation Measurement Program Zenith Radar observations from Barrow, Alaska, during October 2011 are also presented.

  12. Cloud Distribution Statistics from LITE

    NASA Technical Reports Server (NTRS)

    Winker, David M.

    1998-01-01

    The Lidar In-Space Technology Experiment (LITE) mission has demonstrated the utility of spaceborne lidar in observing multilayer clouds and has provided a dataset showing the distribution of tropospheric clouds and aerosols. These unambiguous observations of the vertical distribution of clouds will allow improved verification of current cloud climatologies and GCM cloud parameterizations. Although there is now great interest in cloud profiling radar, operating in the mm-wave region, for the spacebased observation of cloud heights the results of the LITE mission have shown that satellite lidars can also make significant contributions in this area.

  13. An Automated Cloud-edge Detection Algorithm Using Cloud Physics and Radar Data

    NASA Technical Reports Server (NTRS)

    Ward, Jennifer G.; Merceret, Francis J.; Grainger, Cedric A.

    2003-01-01

    An automated cloud edge detection algorithm was developed and extensively tested. The algorithm uses in-situ cloud physics data measured by a research aircraft coupled with ground-based weather radar measurements to determine whether the aircraft is in or out of cloud. Cloud edges are determined when the in/out state changes, subject to a hysteresis constraint. The hysteresis constraint prevents isolated transient cloud puffs or data dropouts from being identified as cloud boundaries. The algorithm was verified by detailed manual examination of the data set in comparison to the results from application of the automated algorithm.

  14. A comparison of cloud top heights computed from airborne lidar and MAS radiance data using CO2 slicing

    E-print Network

    Sheridan, Jennifer

    A comparison of cloud top heights computed from airborne lidar and MAS radiance data using CO2]. Other studies have compared CO2- slicing cloud heights with those computed from lidar data [Smith in assessing the accuracy of the CO2-slicing cloud height algorithm. Infrared measurements of upwelling

  15. [Analysis of cloud spectral structure characteristics based on cloud profile radar data].

    PubMed

    Han, Yong; Lü, Da-Ren

    2013-04-01

    Cloud plays a very important role in the earth-atmosphere system. However, the current climate models are still lacking data about internal fine structure of cloud. And when the traditional passive satellite radiometer is used for remote sense, a plentiful information of the vertical distribution of cloud layer will be lost. For these reasons, NASA proposed the launch project of CloudSat, Whose purpose is to provide the necessary observation, and then allow us to understand better the internal structure of the cloud. CloudSat was successfully launched on April 28, 2006. It carried the first cloud profile radar (CPR) with W band (94 GHz), which can provide continuous and global time sequence vertical structure and characteristics of cloud. In the present paper, using CloudSat satellite data, we analyzed the 8th "Morakot" and 15th " Koppu" typhoon cloud systems. According to the "typhoon" cloud detection results, the radar reflectivity, cloud types and optical thickness successive variation of cloud layer were gotten, which will provide a reference for studying optical properties of typhoon cloud system. PMID:23841397

  16. The Three-Dimensional Spatial Structure of Cirrus Clouds Determined from Lidar Satellite Observations

    NASA Technical Reports Server (NTRS)

    Eloranta, E. W.; Wylie, D.; Wolf, W.

    1996-01-01

    Simultaneous imagery from the University of Wisconsin Volume Imaging Lidar (VIL) and meteorological satellites were used to quantify the spatial structure of cirrus clouds with 60 m resolution. This data was used to determine the spatial distributions of cloud base altitude, cloud top altitude, and mid-cloud altitude. Two dimensional auto-correlation functions describing the mean shape of cirrus clouds were computed. Because cirrus clouds seldom have distinct edges, these correlation functions are derived as a function of a threshold value which defines the cloud edge.

  17. The structure and phase of cloud tops as observed by polarization lidar

    NASA Technical Reports Server (NTRS)

    Spinhirne, J. D.; Hansen, M. Z.; Simpson, J.

    1983-01-01

    High-resolution observations of the structure of cloud tops have been obtained with polarization lidar operated from a high altitude aircraft. Case studies of measurements acquired from cumuliform cloud systems are presented, two from September 1979 observations in the area of Florida and adjacent waters and a third during the May 1981 CCOPE experiment in southeast Montana. Accurate cloud top height structure and relative density of hydrometers are obtained from the lidar return signal intensity. Correlation between the signal return intensity and active updrafts was noted. Thin cirrus overlying developing turrets was observed in some cases. Typical values of the observed backscatter cross section were 0.1-5 (km/sr) for cumulonimbus tops. The depolarization ratio of the lidar signals was a function of the thermodynamic phase of cloud top areas. An increase of the cloud top depolarization with decreasing temperature was found for temperatures above and below -40 C.

  18. The Cloud-Aerosol Transport System (CATS): a new lidar for aerosol and cloud profiling from the International Space Station

    NASA Astrophysics Data System (ADS)

    Welton, E. J.; McGill, M. J.; Yorks, J. E.; Hlavka, D. L.; Hart, W. D.; Palm, S. P.; Colarco, P. R.

    2011-12-01

    Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064, 532, 355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time data capability of the ISS will enable CATS to support operational applications such as air quality and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a summary of the science objectives and simulated data.

  19. The Cloud-Aerosol Transport System (CATS): a New Lidar for Aerosol and Cloud Profiling from the International Space Station

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; McGill, Matthew J.; Yorks, John E.; Hlavka, Dennis L.; Hart, William D.; Palm, Stephen P.; Colarco, Peter R.

    2011-01-01

    Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064, 532, 355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time data capability of the ISS will enable CATS to support operational applications such as air quality and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a summary of the science objectives and simulated data.

  20. Cloud profiling radar for the CloudSat Mission

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Wu, Chialin; Durden, Stephen L.

    2005-01-01

    The CloudSat Mission is a new satellite mission jointly developed by NASA, JPL, the Canadian Agency, Colorado State University, and the US AirForce to acquire a global data set of vertical cloud structure and its variability.

  1. Airborne lidar point cloud-based below-canopy line-of-sight visibility estimator

    NASA Astrophysics Data System (ADS)

    Lee, Heezin; Bruce Blundell, S.; Starek, Michael J.; Harris, John G.

    2013-01-01

    Point cloud data collected by small-footprint lidar scanning systems have proven effective in modeling the forest canopy for extraction of tree parameters. Although line-of-sight visibility (LOSV) in complex forests may be important for military planning and search-and-rescue operations, the ability to estimate LOSV from lidar scanners is not well developed. A new estimator of below-canopy LOSV (BC-LOSV) by addressing the problem of estimation of lidar under-sampling of the forest understory is created. Airborne and terrestrial lidar scanning data were acquired for two forested sites in order to test a probabilistic model for BC-LOSV estimation solely from airborne lidar data. Individual crowns were segmented, and allometric projections of the probability model into the lower canopy and stem regions allowed the estimation of the likelihood of the presence of vision-blocking elements for any given LOSV vector. Using terrestrial lidar scans as ground truth, we found an approximate average absolute difference of 20% between BC-LOSV estimates from the airborne and terrestrial point clouds, with minimal bias for either over- or underestimates. The model shows the usefulness of a data-driven approach to BC-LOSV estimation that depends only on small-footprint airborne lidar point cloud and physical knowledge of tree phenology.

  2. Aerosol and Cloud Interaction Observed From High Spectral Resolution Lidar Data

    NASA Technical Reports Server (NTRS)

    Su, Wenying; Schuster, Gregory L.; Loeb, Norman G.; Rogers, Raymond R.; Ferrare, Richard A.; Hostetler, Chris A.; Hair, Johnathan W.; Obland, Michael D.

    2008-01-01

    Recent studies utilizing satellite retrievals have shown a strong correlation between aerosol optical depth (AOD) and cloud cover. However, these retrievals from passive sensors are subject to many limitations, including cloud adjacency (or 3D) effects, possible cloud contamination, uncertainty in the AOD retrieval. Some of these limitations do not exist in High Spectral Resolution Lidar (HSRL) observations; for instance, HSRL observations are not a ected by cloud adjacency effects, are less prone to cloud contamination, and offer accurate aerosol property measurements (backscatter coefficient, extinction coefficient, lidar ratio, backscatter Angstrom exponent,and aerosol optical depth) at a neospatial resolution (less than 100 m) in the vicinity of clouds. Hence, the HSRL provides an important dataset for studying aerosol and cloud interaction. In this study, we statistically analyze aircraft-based HSRL profiles according to their distance from the nearest cloud, assuring that all profile comparisons are subject to the same large-scale meteorological conditions. Our results indicate that AODs from HSRL are about 17% higher in the proximity of clouds (approximately 100 m) than far away from clouds (4.5 km), which is much smaller than the reported cloud 3D effect on AOD retrievals. The backscatter and extinction coefficients also systematically increase in the vicinity of clouds, which can be explained by aerosol swelling in the high relative humidity (RH) environment and/or aerosol growth through in cloud processing (albeit not conclusively). On the other hand, we do not observe a systematic trend in lidar ratio; we hypothesize that this is caused by the opposite effects of aerosol swelling and aerosol in-cloud processing on the lidar ratio. Finally, the observed backscatter Angstrom exponent (BAE) does not show a consistent trend because of the complicated relationship between BAE and RH. We demonstrate that BAE should not be used as a surrogate for Angstrom exponent, especially at high RH.

  3. Lidar Measurements of Wind and Cloud Around Venus from an Orbiting or Floating/Flying Platform

    NASA Astrophysics Data System (ADS)

    Singh, U. N.; Limaye, S.; Emmitt, G.; Refaat, T. F.; Kavaya, M. J.; Yu, J.; Petros, M.

    2015-04-01

    Given the presence of clouds and haze in the upper portion of the Venus atmosphere, it is reasonable to consider a Doppler Wind Lidar (DWL) for making remote measurements of the 3D winds within the tops of clouds and the overlying haze layer.

  4. Analysis of lidar observations of Arctic polar stratospheric clouds during January 1989

    Microsoft Academic Search

    Owen B. Toon; Azadeh Tabazadeh; Edward V. Browell; Joseph Jordan

    2000-01-01

    We present analyses of lidar backscatter and depolarization ratios for polar stratospheric clouds (PSCs) observed during the 1989 Airborne Arctic Stratospheric Experiment. The backscatter and depolarization ratios are available at one visible and one infrared wavelength. Water ice PSCs were identified at low ambient temperatures based upon their relatively large backscattering and depolarization ratios. The remaining clouds fall into four

  5. Airborne lidar/radiometric measurements of cirrus cloud parameters and their application to LOWTRAN radiance evaluations

    NASA Technical Reports Server (NTRS)

    Uthe, Edward E.

    1990-01-01

    SRI has assembled an airborne lidar/radiometric instrumentation suite for mapping cirrus cloud distribution and analyzing cirrus cloud optical properties. Operation of upward viewing infrared radiometers from an airborne platform provides the optimum method of measuring high altitude cold cloud radiative properties with minimum interference from the thermal emission by the earth's surface and lower atmospheric components. Airborne installed sensors can also operate over large regional areas including water, urban, and mountain surfaces and above lower atmospheric convective clouds and haze layers. Currently available sensors installed on the SRI Queen Air aircraft are illustrated. Lidar and radiometric data records are processed for real time viewing on a color video screen. A cirrus cloud data example is presented as a black and white reproduction of a color display of data at the aircraft altitude of 12,000 ft, the 8 to 14 micron atmospheric radiation background was equivalent to a blackbody temperature of about -60 C and, therefore, the radiometer did not respond strongly to low density cirrus cloud concentrations detected by the lidar. Cloud blackbody temperatures (observed by radiometer) are shown plotted against midcloud temperatures (derived from lidar observed cloud heights and supporting temperature profiles) for data collected on 30 June and 28 July.

  6. Cirrus cloud-temperature interactions over a tropical station, Gadanki from lidar and satellite observations

    SciTech Connect

    S, Motty G, E-mail: mottygs@gmail.com; Satyanarayana, M., E-mail: mottygs@gmail.com; Krishnakumar, V., E-mail: mottygs@gmail.com; Dhaman, Reji k., E-mail: mottygs@gmail.com [Department of Optoelectronics, University of Kerala, Kariavattom, Trivandrum-695 581, Kerala (India)

    2014-10-15

    The cirrus clouds play an important role in the radiation budget of the earth's atmospheric system and are important to characterize their vertical structure and optical properties. LIDAR measurements are obtained from the tropical station Gadanki (13.5{sup 0} N, 79.2{sup 0} E), India, and meteorological indicators derived from Radiosonde data. Most of the cirrus clouds are observed near to the tropopause, which substantiates the strength of the tropical convective processes. The height and temperature dependencies of cloud height, optical depth, and depolarization ratio were investigated. Cirrus observations made using CALIPSO satellite are compared with lidar data for systematic statistical study of cirrus climatology.

  7. NASA Spaceborne Radar Missions: CloudSat and QuickScat: To Observe Clouds and Sea Surface Winds

    NASA Technical Reports Server (NTRS)

    Wu, Chialin

    2006-01-01

    CloudSat is a joint US/Canadian spaceborne science mission for global measurements of atmospheric cloud structures. Cloud Profiling Radar (CPR) has already captured many stunning profiles of cloud/precipitation structures, some have not been seen before. Observation of storms' cloud formation, in conjunction with data from other remote sensors, will hopefully improve quality of natural hazards' forecasts.

  8. Assessment of scan-only operations of lidar for the detection and discrimination of biological clouds

    NASA Astrophysics Data System (ADS)

    Kwon, Kang H.

    2006-05-01

    The Joint Biological Standoff Detection System (JBSDS) Program has developed a lidar system for detecting and discriminating biological clouds at a standoff range. The lidar typically scans near the horizon to detect a cloud and then "stares" at the cloud for a time period to ensure adequate signal-to-noise ratio (SNR) to discriminate if the cloud is biological. This paper proposes an alternative to the scan-and-stare approach; i.e., to scan only. The analysis results of lidar data obtained from field tests conducted in 2004 at Dugway Proving Ground (DPG) in Utah suggest that scan-only operations without staring would improve SNR for detection and discrimination and provide operational advantages.

  9. Retrieving optical properties of dusty clouds from MFRSR and Lidar measurements

    NASA Astrophysics Data System (ADS)

    Wang, T.; Huang, J.

    2009-12-01

    Based on the scattering properties of nonspherical dust aerosol, a new method is developed for retrieving dust aerosol optical depths of dusty clouds. The dusty clouds are defined as the hybrid system of dust plume and cloud. The new method is based on transmittance measurements from surface-based instruments Multi-filter Rotating Shadowband Radiometer (MFRSR) and cloud parameters from Lidar measurements. It uses the difference of absorption between dust aerosols and water droplets for distinguishing and estimating the optical properties of dusts and clouds, respectively. This new retrieval method is not sensitive to the retrieval error of cloud properties and the maximum absolute deviations of dust aerosol and total optical depths for thin dusty cloud retrieval algorithm are only 0.056 and 0.1, respectively, for given possible uncertainties. The retrieval error for thick dusty cloud mainly depends on Lidar-based total dusty cloud properties. This algorithm was applied to retrieve the dusty cloud properties by using MFRSR and Lidar Measurements, during 2008 China-US joined dust field campaign (March-June 2008). This presentation will provide the preliminary results.

  10. Relationship between ice water content and equivalent radar reflectivity for clouds consisting of nonspherical ice particles

    E-print Network

    Baum, Bryan A.

    ). In particular, the focus is on measurements offered by Cloud- Sat, a spaceborne radar launched on 28 April 2006Relationship between ice water content and equivalent radar reflectivity for clouds consisting investigates the relationship between ice water content (IWC) and equivalent radar reflectivity (Ze) at 94 GHz

  11. Active probing of cloud thickness and optical depth using wide-angle imaging LIDAR.

    SciTech Connect

    Love, Steven P.; Davis, A. B. (Anthony B.); Rohde, C. A. (Charles A.); Tellier, L. L. (Larry L.); Ho, Cheng,

    2002-01-01

    At most optical wavelengths, laser light in a cloud lidar experiment is not absorbed but merely scattered out of the beam, eventually escaping the cloud via multiple scattering. There is much information available in this light scattered far from the input beam, information ignored by traditional 'on-beam' lidar. Monitoring these off-beam returns in a fully space- and time-resolved manner is the essence of our unique instrument, Wide Angle Imaging Lidar (WAIL). In effect, WAIL produces wide-field (60{sup o} full-angle) 'movies' of the scattering process and records the cloud's radiative Green functions. A direct data product of WAIL is the distribution of photon path lengths resulting from multiple scattering in the cloud. Following insights from diffusion theory, we can use the measured Green functions to infer the physical thickness and optical depth of the cloud layer. WAIL is notable in that it is applicable to optically thick clouds, a regime in which traditional lidar is reduced to ceilometry. Section 2 covers the up-to-date evolution of the nighttime WAIL instrument at LANL. Section 3 reports our progress towards daytime capability for WAIL, an important extension to full diurnal cycle monitoring by means of an ultra-narrow magneto-optic atomic line filter. Section 4 describes briefly how the important cloud properties can be inferred from WAIL signals.

  12. Testing IWC Retrieval Methods Using Radar and Ancillary Measurements with In Situ Data ANDREW J. HEYMSFIELD,* ALAIN PROTAT, RICHARD T. AUSTIN,# DOMINIQUE BOUNIOL,

    E-print Network

    Protat, Alain

    from spaceborne cloud satellite radar (CloudSat) data. Integrating these data with Cloud-Aerosol Lidar provided to the groups. Retrievals from future spaceborne radar using reflectivity­Doppler fall speeds showTesting IWC Retrieval Methods Using Radar and Ancillary Measurements with In Situ Data ANDREW J

  13. Dual-FOV Raman and Doppler lidar studies of aerosol-cloud interactions: Simultaneous profiling of aerosols, warm-cloud properties, and vertical wind

    NASA Astrophysics Data System (ADS)

    Schmidt, Jörg; Ansmann, Albert; Bühl, Johannes; Baars, Holger; Wandinger, Ulla; Müller, Detlef; Malinka, Aleksey V.

    2014-05-01

    For the first time, colocated dual-field of view (dual-FOV) Raman lidar and Doppler lidar observations (case studies) of aerosol and cloud optical and microphysical properties below and within thin layered liquid water clouds are presented together with an updraft and downdraft characterization at cloud base. The goal of this work is to investigate the relationship between aerosol load close to cloud base and cloud characteristics of warm (purely liquid) clouds and the study of the influence of vertical motions and turbulent mixing on this relationship. We further use this opportunity to illustrate the applicability of the novel dual-FOV Raman lidar in this field of research. The dual-FOV lidar combines the well-established multiwavelength Raman lidar technique for aerosol retrievals and the multiple-scattering Raman lidar technique for profiling of the single-scattering extinction coefficient, effective radius, number concentration of the cloud droplets, and liquid water content. Key findings of our 3 year observations are presented in several case studies of optically thin altocumulus layers occurring in the lower free troposphere between 2.5 and 4 km height over Leipzig, Germany, during clean and polluted situations. For the clouds that we observed, the most direct link between aerosol proxy (particle extinction coefficient) and cloud proxy (cloud droplet number concentration) was found at cloud base during updraft periods. Above cloud base, additional processes resulting from turbulent mixing and entrainment of dry air make it difficult to determine the direct impact of aerosols on cloud processes.

  14. Ice-cloud depolarization of backscatter for CO2 and other infrared lidars

    NASA Technical Reports Server (NTRS)

    Eberhard, Wynn L.

    1992-01-01

    The depolarization of backscatter from ice particles at the CO2 lidar wavelength of 10.59 microns was investigated through field measurements, with simultanous depolarization measurements taken at 0.6943 micron for comparison. The depolarization ratio at the infrared wavelength was usually at or below the lidar's sensitivity limit of 0.01, which is dramatically smaller than the typical 0.5 linear depolarization ratio for short-wave lidars. This behavior is explained by the strong absorption of ice at the infrared wavelength. Depolarization measurements at a 10.59-micron wavelength cannot discriminate between ice and water clouds in the manner of short-wave lidars. A possibility exists for more prominent depolarization at shorter CO2 lidar wavelengths, but additional research is required. Depolarization at the 2.09-micron wavelength is predicted to be substantial and useful for hydrometeor observations.

  15. Assessing spaceborne lidar detection and characterization of aerosols near clouds using coincident airborne lidar and other measurements

    NASA Astrophysics Data System (ADS)

    Kacenelenbogen, M. S.; Redemann, J.; Russell, P. B.; Vaughan, M.; Omar, A. H.; Burton, S. P.; Rogers, R.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.

    2011-12-01

    The objectives are to 1) evaluate potential shortcomings in the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aerosol height detection concerning specific biomass burning smoke events informed by airborne High Spectral Resolution Lidar (HSRL) in different cloud environments and 2) study the lidar-derived atmospheric parameters in the vicinity of clouds for the cases where smoke is within or above clouds. In the case of light absorbing aerosols like biomass burning smoke, studies show that the greater the cloud cover below the aerosols, the more likely the aerosols are to heat the planet. An accurate aerosol height assumption is also crucial to a correct retrieval of aerosol chemical composition from passive space-based measurements (through the Single Scattering Albedo (SSA) and aerosol absorption coefficient, as exemplified by aerosol retrievals using the passive Ozone Monitoring Instrument (OMI)). Strong smoke events are recognized as very difficult to quantify from space using passive (MODIS, OMI etc...) or active (CALIOP) satellite sensors for different reasons. This study is performed through (i) the selection of smoke events with coincident CALIOP and airborne HSRL aerosol observations, with smoke presence determined according to the HSRL aerosol classification data, (ii) the order of such events by range of HSRL aerosol optical depth, total color ratio and depolarization ratio (the latter two informing on the size and shape of the particles) and the evaluation of CALIOP's detection, classification and retrieval performance for each event, (iii) the study of the HSRL (or CALIOP when available) atmospheric parameters (total color ratio, volume depolarization ratio, mean attenuated backscatter) in the vicinity of clouds for each smoke event.

  16. Tracking nucleation, growth, and sublimation in cirrus clouds using ARM millimeter-wavelength radar observations

    NASA Astrophysics Data System (ADS)

    Ivanova, K.; Ackerman, T. P.

    2009-03-01

    On the basis of a case study we outline a stochastic approach to investigate the internal structure of radiative properties of cirrus clouds and place it into the context of the state of the large-scale atmosphere. We analyze radar reflectivity ?(t) measurements obtained with the ground-based millimeter-wavelength radar of the Atmospheric Radiation Measurements (ARM) Program of the Department of Energy at its Southern Great Plains facility. We demonstrate that the evolution of observed non-Gaussian, time-dependent probability distribution functions of ?(t) at each of various depths into cloud relative to cloud top is governed by the Fokker-Planck equation with linear drift D1(x) and stochastic multiplicative noise D2(x). The former is tentatively identified with larger-scale forcing, and the latter is identified with in-cloud circulations and turbulence. Obtained quadratic dependence of D2(x) leads to a noise-induced drift that presents the influence of the small-scale noise on the slow, large-scale deterministic processes. Obtained larger values of the noise-induced drift for the middle 50% of cirrus versus both the upper and lower 25% is anticipated from an ice crystal growth and deposition region. We find that the probability distribution functions of the cirrus that developed above a low-pressure system exhibit behavior at larger scales, e.g., delay times of 2 h, that is consistent with the structure of cirrus based on aircraft in situ measurements and with results from ground-based Raman lidar studies of cirrus. In contrast, the tails of the probability distribution functions of the cirrus over high-pressure system do not show the structure of properties that is distinctive for the cirrus above low-pressure synoptics.

  17. Volcanic Ash Cloud Retrieval by Ground-Based Microwave Weather Radar

    Microsoft Academic Search

    Frank Silvio Marzano; Stefano Barbieri; Gianfranco Vulpiani; William I. Rose

    2006-01-01

    The potential of ground-based microwave weather radar systems for volcanic ash cloud detection and quantitative retrieval is evaluated. The relationship between radar reflectivity factor, ash concentration, and fall rate is statistically derived for various eruption regimes and ash sizes by applying a radar-reflectivity microphysical model. To quantitatively evaluate the ash detectability by weather radars, a sensitivity analysis is carried out

  18. Independent measurement of extinction and backscatter profiles in cirrus clouds by using a combined Raman elastic-backscatter lidar

    NASA Astrophysics Data System (ADS)

    Ansmann, Albert; Wandinger, Ulla; Riebesell, Maren; Weitkamp, Claus; Michaelis, Walfried

    1992-11-01

    Height profiles of the extinction and the backscatter coefficients in cirrus clouds are determined independently from elastic- and inelastic- (Raman) backscatter signals. An extended error analysis is given. Examples covering the measured range of extinction-to-backscatter ratios (lidar ratios) in ice clouds are presented. Lidar ratios between 5 and 15 sr are usually found. A strong variation between 2 and 20 sr can be observed within one cloud profile. Particle extinction coefficients determined from inelastic-backscatter signals and from elastic-backscatter signals by using the Klett method are compared. The Klett solution of the extinction profile can be highly erroneous if the lidar ratio varies along the measuring range. On the other hand, simple backscatter lidars can provide reliable information about the cloud optical depth and the mean cloud lidar ratio.

  19. Possibilities of warm cloud microstructure profiling with multiple-field-of-view Raman lidar.

    PubMed

    Malinka, Aleksey V; Zege, Eleonora P

    2007-12-10

    The possibilities of cloud characteristics retrieval with multiple-field-of-view Raman lidar are considered. It has been shown that the Raman lidar return is sensitive to two cloud characteristics; the scattering coefficient and the effective droplet size. This sensitivity is studied and the optimal receiver fields-of-view (FOVs) for cloud sounding are recommended. The optimal FOV values are estimated to be approximately R/H (R, the collecting optics radius, H, the cloud altitude) to measure the scattering coefficient profiles, and approximately 0.01z/H for the droplet size measurements (z, the cloud thickness). The algorithm based on the iterative scheme and singular value decomposition as a regularization procedure is presented and verified using computer simulation. The recommendations for profile retrieval with variable altitude resolution are given. PMID:18071372

  20. The Structure and Phase of Cloud Tops as Observed by Polarization Lidar.

    NASA Astrophysics Data System (ADS)

    Spinhirne, J. D.; Hansen, M. Z.; Simpson, J.

    1983-08-01

    High-resolution observations of the structure of cloud tops have been obtained with polarization lidar operated from a high altitude aircraft. Case studies of measurements acquired from cumuliform cloud systems are presented, two from September 1979 observations in the area of Florida and adjacent waters and a third during the May 1981 CCOPE experiment in southeast Montana. Accurate cloud top height structure and relative density of hydrometers are obtained from the lidar return signal intensity. Correlation between the signal return intensity and active updrafts was noted. Thin cirrus overlying developing turrets was observed in some cases. Typical values of the observed backscatter cross section were 0.1-0.5 (km sr1) for cumulonimbus tops.The depolarization ratio of the lidar signals was a function of the thermodynamic phase of cloud top areas. An increase of the cloud top depolarization with decreasing temperature was found for temperatures above and below 40°C. The observed values of depolarization from water clouds were greater than reported by previous studies. Increased multiple scattering due to a larger range from the receiver to scattering medium is thought to have given rise to the greater water cloud depolarization for the cloud top measurements.

  1. Electric Field Magnitude and Radar Reflectivity as a Function of Distance from Cloud Edge

    NASA Technical Reports Server (NTRS)

    Ward, Jennifer G.; Merceret, Francis J.

    2004-01-01

    The results of analyses of data collected during a field investigation of thunderstorm anvil and debris clouds are reported. Statistics of the magnitude of the electric field are determined as a function of distance from cloud edge. Statistics of radar reflectivity near cloud edge are also determined. Both analyses use in-situ airborne field mill and cloud physics data coupled with ground-based radar measurements obtained in east-central Florida during the summer convective season. Electric fields outside of anvil and debris clouds averaged less than 3 kV/m. The average radar reflectivity at the cloud edge ranged between 0 and 5 dBZ.

  2. Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station

    NASA Astrophysics Data System (ADS)

    Giannakaki, E.; Balis, D. S.; Amiridis, V.; Kazadzis, S.

    2007-11-01

    Optical and geometrical characteristics of cirrus clouds over Thessaloniki, Greece (40.6° N, 22.9° E) have been determined from the analysis of lidar and radiosonde measurements performed during the period from 2000 to 2006. Cirrus clouds are generally observed in a mid-altitude region ranging from 8.6 to 13 km, with mid-cloud temperatures in the range from -65° to -38°C. The cloud thickness generally ranges from 1 to 5 km and 38{%} of the cases studied have thickness between 2 and 3 km. The retrieval of optical depth and lidar ratio of cirrus clouds is performed using three different methods, taking into account multiple scattering effect. The mean optical depth is found to be 0.31±0.24 and the corresponding mean lidar ratio is 30±17 sr following the scheme of Klett-Fernald method. Sub-visual, thin and opaque cirrus clouds are observed at 3%, 57% and 40% of the measured cases, respectively. A comparison of the results obtained between the three methods shows good agreement. The multiple scattering errors of the measured effective extinction coefficients range from 20 to 60%, depending on cloud optical depth. The temperature and thickness dependencies on optical properties have also been studied in detail. A maximum mid-cloud depth of 3.5 km is found at temperatures around -47.5°C, while there is an indication that optical depth and mean extinction coefficient increases with increasing mid-cloud temperature. A correlation between optical depth and thickness was also found. However, no clear dependence of the lidar ratio values on the cloud temperature and thickness was found.

  3. A SYNERGY OF MICROWAVE CLOUD TOMOGRAPHY AND SCANNING RADAR: MOVING TOWARD A 3D VIEW OF CLOUDS

    E-print Network

    A SYNERGY OF MICROWAVE CLOUD TOMOGRAPHY AND SCANNING RADAR: MOVING TOWARD A 3D VIEW OF CLOUDS D.O. Box, Upton, NY www.bnl.gov ABSTRACT Clouds are a central focus of the DOE Atmospheric Radiation Measurement (ARM) and many other programs. A 3D view of clouds would allow not only a better understanding

  4. Offshore wind farm flow measured by complementary remote sensing techniques: radar satellite TerraSAR-X and lidar windscanners

    NASA Astrophysics Data System (ADS)

    Schneemann, J.; Hieronimus, J.; Jacobsen, S.; Lehner, S.; Kühn, M.

    2015-06-01

    Scanning Doppler lidar systems offer continuous wind measurements with some kilometres of range and a spatial distribution of concurrent measurements down to some metres. The synthetic aperture radar (SAR) satellite TerraSAR-X is capable to cover offshore areas of hundreds of square kilometres and to obtain wind data spatially distributed with some tens of metres. Images can be taken up to twice a day when the satellite passes the measurement site. Simultaneous wind speed measurements with ground based scanning Doppler lidar and TerraSAR-X in the region of the offshore wind farm ”alpha ventus” in the German North Sea were collected. A comparison of both systems in free stream conditions is performed by extrapolating the lidardata to the measurement height of the radar satellite assuming a logarithmic wind profile. In wake conditions the wake tracks obtained by lidar and TerraSAR-X are compared. In free stream conditions the comparison reveals a mean absolute wind velocity difference ? 0.4 m/s in two of the four considered cases and 1.1 m/s in one case. The fourth case shows a bad agreement due to a unusually low radar backscatter in the satellite's measurement. In wake conditions the wind turbine wakes could be tracked in the lidar and the satellite data. The comparison for the considered case reveals similar wake tracks in principle, but no matching due to the time difference of the measurements and the lower spatial resolution of the radar measurements.

  5. Inertia-gravity waves in Antarctica: A case study using simultaneous lidar and radar measurements at McMurdo/Scott

    E-print Network

    Vadas, Sharon

    Inertia-gravity waves in Antarctica: A case study using simultaneous lidar and radar measurements: Chen, C., X. Chu, A. J. McDonald, S. L. Vadas, Z. Yu, W. Fong and X. Lu (2013), Inertia-gravity waves [Fritts and Alexander, 2003]. Unfortunately, the gravity wave parameterizations used in global models

  6. Laser radar characterization of atmospheric aerosols in the troposphere and stratosphere using range dependent lidar ratio

    NASA Astrophysics Data System (ADS)

    Malladi, Satyanarayana; Soman Radha, Radhakrishnan; Mahadevan Pillai, V. P.; Sangipillai, Veerabuthiran; Bhargavan, Presennakumar; Vinjanampaty, Murty; Karnam, Reghunath

    2010-01-01

    Laser radar (lidar) provides an excellent tool for characterizing the physical properties of atmospheric aerosols which play a very important role in modifying the radiative budget of the Earth's atmosphere. One of the important issues in lidar research is to derive accurate backscattering or extinction coefficient profiles required for understanding the basic mechanisms in the formation of aerosols and identifying their sources and sinks. Most of the inversion methods used for deriving the aerosol coefficients assume a range independent value for the extinction-to- backscattering ratio [lidar ratio, (LR)]. However, it is known that in a realistic atmosphere the value of LR is range dependent and varies with the physical and chemical properties of the aerosols. In this paper, we use a variant of widely applied Klett's method to obtain the range dependent LR values and derive the aerosol extinction profiles with good accuracy. We present the lidar derived aerosol extinction profiles in the upper troposphere and lower stratosphere corresponding to different seasons of the year of two distinctly different stations in the Indian subcontinent namely Trivandrum (8.33° N, 77° E), Kerala, India, a coastal station and Gadanki (13.5° N, 79.2° E), Tirupati, India an inland station. The range dependent LR is derived corresponding to different seasons of the year at the two stations. The lidar ratio, aerosol extinction coefficient (AEC), aerosol scattering ratio and aerosol optical depth show strong to medium seasonal variation at both the stations. The lidar ratio values at Trivandum vary in the range of 11-38 sr whereas the values range from 20-34 sr at Gadanki. AEC values at the Trivandum station vary from 7.9x10-6 to 6.9x10-5 m-1 and at Gadanki station the variation is from 1.27x10-5 to 6.9x10-5 m-1. It is proposed to use back-trajectory analysis to understand the sources of aerosol at the two stations.

  7. Aerosol and Cloud Observations and Data Products by the GLAS Polar Orbiting Lidar Instrument

    NASA Technical Reports Server (NTRS)

    Spinhirne, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.; Welton, E. J.

    2005-01-01

    The Geoscience Laser Altimeter System (GLAS) launched in 2003 is the first polar orbiting satellite lidar. The instrument was designed for high performance observations of the distribution and optical scattering cross sections of clouds and aerosol. The backscatter lidar operates at two wavelengths, 532 and 1064 nm. Both receiver channels meet and exceed their design goals, and beginning with a two month period through October and November 2003, an excellent global lidar data set now exists. The data products for atmospheric observations include the calibrated, attenuated backscatter cross section for cloud and aerosol; height detection for multiple cloud layers; planetary boundary layer height; cirrus and aerosol optical depth and the height distribution of aerosol and cloud scattering cross section profiles. The data sets are now in open release through the NASA data distribution system. The initial results on global statistics for cloud and aerosol distribution has been produced and in some cases compared to other satellite observations. The sensitivity of the cloud measurements is such that the 70% global cloud coverage result should be the most accurate to date. Results on the global distribution of aerosol are the first that produce the true height distribution for model inter-comparison.

  8. Precipitation Structures and Associated Cloud Microphysics in an MJO event during DYNAMO: Cloud-Resolving Modeling and Radar Observations

    NASA Astrophysics Data System (ADS)

    Li, X.; Tao, W. K.; Janiga, M. A.; Wang, S.; Hagos, S.; Matsui, T.; Liu, C.; Rowe, A.; Xu, W.; Zhang, C.

    2014-12-01

    The Dynamics of the Madden-Julian Oscillation field campaign (Oct. 2011 ~Mar. 2012) over the Tropical Indian Ocean produced a rich dataset of cloud and precipitation structures with ground-based radars. This study uses 3 different cloud-resolving models (GCE, SAM and WRF running in doubly cyclic condition), 2 ground-based radar (S-POL and C-Band radar onboard R/V Revelle), TRMM satellite, as well as limited CloudSat overpasses during the November MJO event in an attempt to piece together how precipitation structures, and the associated cloud microphysics, evolve with the developing MJO over central Indian Ocean. The cloud-resolving models are forced by observed large-scale forcing data. The model simulations fill in observational gaps for limited area ground-based radars and sporadic satellite observations. In the mean time, radar observations provide excellent validations for CRMs' inter-comparisons.

  9. The Cloud-Aerosol Transport System (CATS): a new lidar for aerosol and cloud profiling from the International Space Station

    NASA Astrophysics Data System (ADS)

    Welton, E. J.; McGill, M. J.; Yorks, J. E.; Hlavka, D. L.; Hart, W. D.; Palm, S. P.; Colarco, P. R.

    2012-12-01

    Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064, 532, 355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time (NRT) data capability of the ISS will enable CATS to support operational applications such as aerosol and air quality forecasting and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a summary of the science objectives and simulated data. Results from the NASA Goddard Earth Observing System general circulation model and data assimilation system (GEOS-5) have been used to generate the simulated data, and will be used to help process CATS data after launch.

  10. The Cloud-Aerosol Transport System (CATS): A New Lidar for Aerosol and Cloud Profiling from the International Space Station

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; McGill, Mathew J.; Yorks. John E.; Hlavka, Dennis L.; Hart, William D.; Palm, Stephen P.; Colarco, Peter R.

    2012-01-01

    Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064,532,355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time (NRT) data capability ofthe ISS will enable CATS to support operational applications such as aerosol and air quality forecasting and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a summary of the science objectives and simulated data. Input from the ICAP community is desired to help plan our NRT mission goals and interactions with ICAP forecasters.

  11. High altitude Balloon Borne Lidar experiment for the study of aerosols and clouds

    NASA Astrophysics Data System (ADS)

    Manchanda, R. K.; Ramaratnam, S.; Krishnan, A. R.; Presenna Kumar, Bharghavan; Jeswin Vetha Jeyasingh, J.; Sreekumar, S.; Joy, Sherly; Thirupathirajan, S.; Bhavanikumar, Y.; Devarajan, Anand

    Ground based light detection and ranging (LIDAR) instruments are routinely used for the study of aerosols and clouds using remote sensing technique. Such measurements can only give local/regional scale data. Space based system can provide data on global scale and the same can be used for climate modeling and weather forecasting applications. Development of a Balloon Borne Lidar (BBL) system was taken up as a precursor to the development of Space Borne Lidar system by Indian Space Research Organization (ISRO). A downward looking low power, high PRF laser based lidar system (Micro Pulse Lidar) operating at 532nm having 150mm Cassegrain type small telescope and a photomultiplier tube based photon counting data acquisition system was developed for the measurement of backscattered signal from aerosols and clouds. The BBL instrument was flown successfully in a high altitude balloon platform from National Balloon Facility in Hyderabad. The balloon reached a ceiling altitude of 35 km and scientific data on aerosol and clouds were collected for duration of 5 hours. This paper describes the design challenges and the technical complexity associated with the laser based active payload in a balloon platform. Preliminary results of the experiment will also be presented.

  12. Influence of characteristics of micro-bubble clouds on backscatter lidar signal.

    PubMed

    Li, Wei; Yang, Kecheng; Xia, Min; Rao, Jionghui; Zhang, Wei

    2009-09-28

    Marine micro-bubbles are one of those important constituents that influence scattering characteristics of water column. Monte Carlo Based simulations show that a water entrained bubble cloud generate a characteristic backscatter of incident laser light [M. Xia, J. Opt. A: Pure Appl. Opt. 8, 350 (2006)]. This characteristic can be used to detect and localize bubble clouds, leading to wide ranging applications, especially in optical remote sensing. This paper describes tests of an underwater lidar system applied to detecting cloud of micro-bubbles. Laboratory experiments demonstrate that the system is capable of detecting bubbles ranging from diameter 10 microm approximately 200 microm, over a distance of 7-12 m from the detector. The dependence of the lidar return signal on size distribution of bubbles, concentration, thickness and location of bubble clouds is studied and compared with simulation results. PMID:19907564

  13. DC-8 Scanning Lidar Characterization of Aircraft Contrails and Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Uthe, Edward E.; Nielsen, Norman B.; Oseberg, Terje E.

    1998-01-01

    An angular-scanning large-aperture (36 cm) backscatter lidar was developed and deployed on the NASA DC-8 research aircraft as part of the SUCCESS (Subsonic Aircraft: Contrail and Cloud Effects Special Study) program. The lidar viewing direction could be scanned continuously during aircraft flight from vertically upward to forward to vertically downward, or the viewing could be at fixed angles. Real-time pictorial displays generated from the lidar signatures were broadcast on the DC-8 video network and used to locate clouds and contrails above, ahead of, and below the DC-8 to depict their spatial structure and to help select DC-8 altitudes for achieving optimum sampling by onboard in situ sensors. Several lidar receiver systems and real-time data displays were evaluated to help extend in situ data into vertical dimensions and to help establish possible lidar configurations and applications on future missions. Digital lidar signatures were recorded on 8 mm Exabyte tape and generated real-time displays were recorded on 8mm video tape. The digital records were transcribed in a common format to compact disks to facilitate data analysis and delivery to SUCCESS participants. Data selected from the real-time display video recordings were processed for publication-quality displays incorporating several standard lidar data corrections. Data examples are presented that illustrate: (1) correlation with particulate, gas, and radiometric measurements made by onboard sensors, (2) discrimination and identification between contrails observed by onboard sensors, (3) high-altitude (13 km) scattering layer that exhibits greatly enhanced vertical backscatter relative to off-vertical backscatter, and (4) mapping of vertical distributions of individual precipitating ice crystals and their capture by cloud layers. An angular scan plotting program was developed that accounts for DC-8 pitch and velocity.

  14. DC-8 scanning lidar characterization of aircraft contrails and cirrus clouds

    NASA Technical Reports Server (NTRS)

    Nielsen, Norman B.; Uthe, Edward E. (Principal Investigator)

    1996-01-01

    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.

  15. Landslide detection by indices of LiDAR point-cloud density

    Microsoft Academic Search

    Jin-King Liu; Wei-Chen Hsu; Mon-Shieh Yang; Yu-Chung Shieh; Tian-Yuan Shih

    2010-01-01

    The deliverables of an airborne LiDAR survey usually include all points, ground points, digital surface models (DSM) and digital elevation models (DEM). Indices of point clouds tested in this study include density of all points, density of ground points, density of only returns, and density of multiple returns. Shallow landslides are the most common landslides triggered by torrential rainfalls and

  16. A HIGH SPECTRAL RESOLUTION LIDAR DESIGNED FOR LONG-TERM ARCTIC CLOUD AND HAZE OBSERVATIONS.

    E-print Network

    Eloranta, Edwin W.

    allow robust discrimination between ice and water clouds. Rigorous error estimates can be computed and particle phase. References: Grund, C.J. and E. W. Eloranta, 1991: The University of Wisconsin High Spectral of a High Spectral Resolution Lidar based on an iodine absorption filter, Optics Letters, 19, 234-236. #12;

  17. Enhanced lidar backscattering by quasi-horizontally oriented ice crystal plates in cirrus clouds

    Microsoft Academic Search

    Ping Yang; Yong X. Hu; David M. Winker; Jun Zhao; Chris A. Hostetler; Lamont Poole; Bryan A. Baum; Michael I. Mishchenko; Jens Reichardt

    2003-01-01

    The backscattering of light by quasi-horizontally oriented hexagonal ice plates is investigated because of its pertinence to lidar measurements of cirrus clouds. For oriented ice crystals, the commonly used geometric optics ray-tracing method is not applicable to the computation of the scattered field in certain scattering directions, in particular, the backscattering direction, because of the singularity problem inherent to the

  18. Use of Probability Distribution Functions for Discriminating Between Cloud and Aerosol in Lidar Backscatter Data

    NASA Technical Reports Server (NTRS)

    Liu, Zhaoyan; Vaughan, Mark A.; Winker, Davd M.; Hostetler, Chris A.; Poole, Lamont R.; Hlavka, Dennis; Hart, William; McGill, Mathew

    2004-01-01

    In this paper we describe the algorithm hat will be used during the upcoming Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission for discriminating between clouds and aerosols detected in two wavelength backscatter lidar profiles. We first analyze single-test and multiple-test classification approaches based on one-dimensional and multiple-dimensional probability density functions (PDFs) in the context of a two-class feature identification scheme. From these studies we derive an operational algorithm based on a set of 3-dimensional probability distribution functions characteristic of clouds and aerosols. A dataset acquired by the Cloud Physics Lidar (CPL) is used to test the algorithm. Comparisons are conducted between the CALIPSO algorithm results and the CPL data product. The results obtained show generally good agreement between the two methods. However, of a total of 228,264 layers analyzed, approximately 5.7% are classified as different types by the CALIPSO and CPL algorithm. This disparity is shown to be due largely to the misclassification of clouds as aerosols by the CPL algorithm. The use of 3-dimensional PDFs in the CALIPSO algorithm is found to significantly reduce this type of error. Dust presents a special case. Because the intrinsic scattering properties of dust layers can be very similar to those of clouds, additional algorithm testing was performed using an optically dense layer of Saharan dust measured during the Lidar In-space Technology Experiment (LITE). In general, the method is shown to distinguish reliably between dust layers and clouds. The relatively few erroneous classifications occurred most often in the LITE data, in those regions of the Saharan dust layer where the optical thickness was the highest.

  19. Using LiDAR, RADAR, and Optical data to improve a NFMS in Kalimantan, Indonesia

    NASA Astrophysics Data System (ADS)

    Hagen, S. C.; Saatchi, S. S.; Braswell, B. H., Jr.; Palace, M. W.; Salas, W.; Walker, S.; Hoekman, D.; Ipsan, C.; Brown, S.; Sullivan, F.

    2014-12-01

    Around the world, governments are establishing national forest monitoring systems (NFMS) that use a combination of remote sensing and ground-based forest carbon inventory approaches to estimate anthropogenic forest-related greenhouse gas emissions and removals. The NFMS forms the link between historical assessments and current/future assessments of forests, enabling consistency in the data and information to support the implementation of REDD+ activities. The creation of a reliable, transparent, and comprehensive NFMS is currently limited by a dearth of relevant data that are accurate, low-cost, and spatially resolved at subnational scales. With funding from a 3-year NASA Carbon Monitoring System project beginning in September 2013, we are developing, evaluating, and validating several critical components of an NFMS in Kalimantan, Indonesia, focusing on the use of LiDAR and radar imagery for improved carbon stock and forest degradation information. Here, we present results from an initial analysis of a spatially extensive set of LiDAR data collected across the Indonesian provinces on the island of Borneo together with RADAR and optical data. Our objectives are to evaluate sensor and platform tradeoffs systematically against in situ investments, as well as provide detailed tracking and characterization of uncertainty in a cost-benefit framework. Kalimantan is an ideal area to evaluate the use of remote sensing methods because measuring forest carbon stocks and their human caused changes with a high degree of certainty on the ground can be difficult. While our work focuses at the subnational scale for Kalimantan, we are targeting these methods for applicability across broader geographies and for implementation at various scales.

  20. Validation of a radar doppler spectra simulator using measurements from the ARM cloud radars

    SciTech Connect

    Remillard, J.; Luke, E.; Kollias, P.

    2010-03-15

    The use of forward models as an alternative approach to compare models with observations contains advantages and challenges. Radar Doppler spectra simulators are not new; their application in high- resolution models with bin microphysics schemes could help to compare model output with the Doppler spectra recorded from the vertically pointing cloud radars at the ARM Climate Research Facility sites. The input parameters to a Doppler spectra simulator are both microphysical (e.g., particle size, shape, phase, and number concentration) and dynamical (e.g., resolved wind components and sub-grid turbulent kinetic energy). Libraries for spherical and non-spherical particles are then used to compute the backscattering cross-section and fall velocities, while the turbulence is parameterized as a Gaussian function with a prescribed width. The Signal-to-Noise Ratio (SNR) is used to determine the amount of noise added throughout the spectrum, and the spectral smoothing due to spectral averages is included to reproduce the averaging realized by cloud radars on successive returns. Thus, realistic Doppler spectra are obtained, and several parameters that relate to the morphological characteristics of the synthetically generated spectra are computed. Here, the results are compared to the new ARM microARSCL data products in an attempt to validate the simulator. Drizzling data obtained at the SGP site by the MMCR and the AMF site at Azores using the WACR are used to ensure the liquid part and the turbulence representation part of the simulator are properly accounted in the forward model.

  1. Synthetic Signatures of Volcanic Ash Cloud Particles From X-Band Dual-Polarization Radar

    Microsoft Academic Search

    Frank Silvio Marzano; Errico Picciotti; Gianfranco Vulpiani; Mario Montopoli

    2012-01-01

    Weather radar retrieval, in terms of detection, estimation, and sensitivity, of volcanic ash plumes is dependent not only on the radar system specifications but also on the range and ash cloud distribution. The minimum detectable signal can be increased, for a given radar and ash plume scenario, by decreasing the observation range and increasing the operational frequency and also by

  2. Aircraft Microphysical and Surface-Based Radar Observations of Summertime Arctic Clouds

    E-print Network

    Zuidema, Paquita

    Aircraft Microphysical and Surface-Based Radar Observations of Summertime Arctic Clouds R. PAUL Updated analyses of in situ microphysical properties of three Arctic cloud systems sampled by aircraft to the North Pole. Radar­aircraft agreement in reflectivity and derived microphysical parameters was reasonably

  3. NEXRAD Weather Radar Observations of the 2006 Augustine Volcanic Eruption Clouds

    Microsoft Academic Search

    D. J. Schneider; C. Scott; J. Wood; T. Hall

    2006-01-01

    The 2006 eruption of Augustine Volcano, Alaska provided an exceptional opportunity to detect and measure explosive volcanic events and to track drifting volcanic clouds using WRS-88D (NEXRAD) weather radar data. Radar data complemented the real-time seismic monitoring by providing rapid confirmation of ash generation and cloud height. The explosive phase of the eruption consisted of thirteen discrete Vulcanian explosions from

  4. Lidar and Triple-Wavelength Doppler Radar Measurements of the Melting Layer: A Revised Model for Dark-and Brightband Phenomena

    E-print Network

    Shupe, Matthew

    Lidar and Triple-Wavelength Doppler Radar Measurements of the Melting Layer: A Revised Model water-coated snowflakes that are high in the melting layer. The lidar dark band exclusively involves mixed-phase particles and is centered where the shrinking snowflakes collapse into raindrops--the point

  5. Object-Based Classification of Urban Airborne LIDAR Point Clouds with Multiple Echoes Using Svm

    NASA Astrophysics Data System (ADS)

    Zhang, J. X.; Lin, X. G.

    2012-07-01

    Airborne LiDAR point clouds classification is meaningful for various applications. In this paper, an object-based analysis method is proposed to classify the point clouds in urban areas. In the process of classification, outliers in the point clouds are first removed. Second, surface growing algorithm is employed to segment the point clouds into different clusters. The above point cloud segmentation is helpful to derive useful features such as average height, size/area, proportion of multiple echoes, slope/orientation, elevation difference, rectangularity, ratio of length to width, and compactness. At last, SVM-based classification is performed on the segmented point clouds with radial basis function as kernel. Two datasets with high point densities are employed to test the proposed method, and three classes are predefined. The results suggest that our method will produce the overall classification accuracy larger than 97% and the Kappa coefficient larger than 0.95.

  6. Simulating Martian boundary layer water ice clouds and the lidar measurements for the Phoenix mission

    NASA Astrophysics Data System (ADS)

    Pathak, Jagruti; Michelangeli, Diane V.; Komguem, Leonce; Whiteway, James; Tamppari, Leslie K.

    2008-06-01

    Diurnal variation of ground fog and water ice cloud formation at the NASA Phoenix lander site is investigated using a one-dimensional Mars Microphysical Model (MMM) coupled with the results from the one-dimensional University of Helsinki atmospheric boundary layer (ABL) model. Phoenix is scheduled to reach Mars in May 2008 and land in the northern plains (65°-72°N). Observations from Mars Global Surveyor Thermal Emission Spectrometer for the proposed landing site and season L s = 76°-125° have been used for the model initialization, both in the ABL and MMM. The diurnal variations of temperature and eddy diffusion coefficients produced by the uncoupled ABL are then applied to the MMM. Extinction and backscattering coefficients and lidar ratios are presented for the simulated dust and water ice clouds at the Phoenix location. Results of the dust and ice clouds are then used to simulate the Phoenix lidar measurements at two wavelengths, 532 and 1064 nm.

  7. Depolarization ratio and attenuated backscatter for nine cloud types: analyses based on collocated CALIPSO lidar and MODIS measurements.

    PubMed

    Cho, Hyoun-Myoung; Yang, Ping; Kattawar, George W; Nasiri, Shaima L; Hu, Yongxiang; Minnis, Patrick; Trepte, Charles; Winker, David

    2008-03-17

    This paper reports on the relationship between lidar backscatter and the corresponding depolarization ratio for nine types of cloud systems. The data used in this study are the lidar returns measured by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite and the collocated cloud products derived from the observations made by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua satellite. Specifically, the operational MODIS cloud optical thickness and cloud-top pressure products are used to classify cloud types on the basis of the International Satellite Cloud Climatology Project (ISCCP) cloud classification scheme. While the CALIPSO observations provide information for up to 10 cloud layers, in the present study only the uppermost clouds are considered. The layer-averaged attenuated backscatter (gamma') and layer-averaged depolarization ratio (delta) from the CALIPSO measurements show both water- and ice-phase features for global cirrus, cirrostratus, and deep convective cloud classes. Furthermore, we screen both the MODIS and CALIPSO data to eliminate cases in which CALIPSO detected two- or multi-layered clouds. It is shown that low gamma' values corresponding to uppermost thin clouds are largely eliminated in the CALIPSO delta-gamma' relationship for single-layered clouds. For mid-latitude and polar regions corresponding, respectively, to latitude belts 30 degrees -60 degrees and 60 degrees -90 degrees in both the hemispheres, a mixture of water and ice is also observed in the case of the altostratus class. MODIS cloud phase flags are also used to screen ice clouds. The resultant water clouds flagged by the MODIS algorithm show only water phase feature in the delta-gamma' relation observed by CALIOP; however, in the case of the ice clouds flagged by the MODIS algorithm, the co-existence of ice- and water-phase clouds is still observed in the CALIPSO delta-gamma' relationship. PMID:18542490

  8. Evaluation of Ice Water Content Retrievals from Cloud Radar Reflectivity and Temperature Using a Large Airborne In Situ Microphysical Database

    E-print Network

    Protat, Alain

    of the forthcoming CloudSat spaceborne radar, and of the European CloudNET and U.S. Atmospheric Radiation MeasurementEvaluation of Ice Water Content Retrievals from Cloud Radar Reflectivity and Temperature Using the performances of the proposed ice water content (IWC)­radar reflectivity Z and IWC­Z­temperature T relationships

  9. Improved Boundary Layer and Cloud Heights from the NASA Micro Pulse Lidar Network (MPLNET)

    NASA Astrophysics Data System (ADS)

    Lewis, J.; Welton, E. J.; Belcher, L. R.; Mplnet Team

    2011-12-01

    The NASA Micro Pulse Lidar Network (MPLNET) Level 1.5b data product provides identification of aerosol and cloud layers. New algorithms have been developed for determining planetary boundary layer (PBL) heights and cloud heights from MPLNET data. An overview of the new methods will be discussed, along with their advantages and limitations. Seasonal and diurnal trends observed at the Goddard Space Flight Center site in Greenbelt, MD will also be evaluated. Results from the improved algorithms are compared to the current operational MPLNET cloud and PBL height products as well as the corresponding products from the GEOS-5 model.

  10. Advances in Raman Lidar Measurements of Water Vapor, Cirrus Clouds and Carbon Dioxide

    NASA Technical Reports Server (NTRS)

    Whiteman, David N.; Potter, John R.; Tola, Rebecca; Rush, Kurt; Veselovskii, Igor; Cadirola, Martin; Comer, Joseph

    2006-01-01

    Narrow-band interference filters with improved transmission in the ultraviolet have been developed under NASA-funded research and used in the Raman Airborne Spectroscopic Lidar (RASL) in ground- based, upward-looking tests. RASL is an airborne Raman Lidar system designed to measure water vapor mixing ratio, and aerosol backscatter/extinction/depolarization. It also possesses the capability to make experimental measurements of cloud liquid water and carbon dioxide. It is being prepared for first flight tests during the summer of 2006. With the newly developed filters installed in RASL, measurements were made of atmospheric water vapor, cirrus cloud optical properties and carbon dioxide that improve upon any previously demonstrated using Raman lidar. Daytime boundary layer profiling of water vapor mixing ratio is performed with less than 5% random error using temporal and spatial resolution of 2-minutes and 60 - 210, respectively. Daytime cirrus cloud optical depth and extinction- to-backscatter ratio measurements are made using 1-minute average. Sufficient signal strength is demonstrated to permit the simultaneous profiling of carbon dioxide and water vapor mixing ratio into the free troposphere during the nighttime. Downward-looking from an airborne RASL should possess the same measurement statistics with approximately a factor of 5 - 10 decrease in averaging time. A description of the technology improvements are provided followed by examples of the improved Raman lidar measurements.

  11. Multiple scattering in space-borne lidar sounding of multilayered clouds

    NASA Astrophysics Data System (ADS)

    Flesia, Cristina; Starkov, Andrei V.; Schwendimann, Paolo

    1994-12-01

    Due to the big distance between a spaceborne lidar and the sounding targets a great volume of the atmospheric domain is caught within the lidar receiver field of view and the multiple scattering highly affects the lidar returns. Variance reduction Monte Carlo method and analytical extension of the Mie theory are used for the calculation of spaceborne lidar returns from multilayered cloud systems. A main advantage of Monte Carlo techniques is that they allow the calculation of the solution with the desired accuracy. The analytical scattering extension of the Mie theory leads to analytical expressions of the n-fold scattered electromagnetic field and then to a generalisation of the optical parameters. The performance capabilities of identification of cloud layers from space has been evaluated. The retrieval of the extinction and optical depth in clear and cloudy atmosphere has been carried out by single scattering inversion methods. For clear inhomogeneous atmosphere in visible spectral region the use of Klett's inversion method leads to a reduction of about 10% of the retrieval values in lower 30 km atmospheric slab as compared with the initial data. Influence of transparent multilayered cirrus clouds results in a reduction of the retrieval extinction coefficient varying between 30-50%.

  12. Aerosol and cloud typing with an automated 24/7 aerosol lidar

    NASA Astrophysics Data System (ADS)

    Baars, Holger; Seifert, Patric; Wandinger, Ulla

    2015-04-01

    Modern sophisticated multi-wavelength Raman polarization lidars have the ability to measure autonomous and unattended in 24/7 mode. These aerosol lidars can deliver backscatter, extinction, and depolarization profiles of the atmosphere which can be used for a target categorization, i.e. the determination of different aerosol and cloud types. However, to derive the optical particle properties a calibration of the lidar signals in the free atmosphere, where only Rayleigh scattering occurs, is needed. This calibration is usually done manually case by case and thus prohibits automatic data analysis and particle typing. To overcome this limitation, the mobile EARLINET lidar PollyXT of TROPOS was deployed continuously without changes in the instrumental setup during two field campaigns in the framework of the German HD(CP)2 project to obtain temporally stable lidar signals. The temporal stability together with the high performance and good characterization of the lidar lead to the possibility of an absolute lidar calibration. The corresponding calibration constant was derived in two ways: first by using manually Raman and Klett retrievals for selected periods and second by using the aerosol optical depth (AOD) from co-located AERONET sun photometer measurements. The derived calibration constants show a high temporal stability and a good agreement between both methods and thus allowed the continuous calibration of the lidar and the retrieval of the attenuated backscatter coefficient at three wavelengths. In addition, the calibrated volume depolarization ratio, obtained following EARLINET recommendations, is continuously available. After correction for the molecular contribution, these four quantities were used for an aerosol and cloud typing in terms of particle size and shape. The final categorization leads to 11 categories, e.g. clean atmosphere, small spherical particles, large non-spherical particles, water droplets, ice crystals and corresponding mixtures. In this contribution, the application of this methodology for several case studies and the statistical analysis from the two field campaigns will be shown. For future applications it is planned to implement this approach in the CLOUDNET retrieval at sites for which an appropriate lidar is available to make use of the full instrument synergy which is required for advanced aerosol-cloud-interaction studies.

  13. The Polarization Lidar Technique for Cloud Research: A Review and Current Assessment.

    NASA Astrophysics Data System (ADS)

    Sassen, Kenneth

    1991-12-01

    The development of the polarization lidar field over the past two decades is reviewed, and the current cloud-research capabilities and limitations are evaluated. Relying on fundamental scattering principles governing the interaction of polarized laser light with distinctly shaped hydrometers, this remote-sensing technique has contributed to our knowledge of the composition and structure of a variety of cloud types. For example, polarization lidar is a key component of current climate-research programs to characterize the properties of cirrus clouds, and is an integral part of multiple remote-sensor studies of mixed-phase cloud systems, such as winter mountain storms. Although unambiguous cloud-phase discrimination and the identification of some ice particle types and orientations are demonstrated capabilities, recent theoretical approaches involving ice crystal ray-tracing and cloud microphysical model simulations are, promising to increase the utility of the technique. New results simulating the single and multiple scattering properties of precipitating mixed-phase clouds are given for illustration of such methods.

  14. The 27-28 October 1986 FIRE IFO cirrus case study - A five lidar overview of cloud structure and evolution

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Grund, Christian J.; Spinhirne, James D.; Hardesty, Michael M.; Alvarez, Jose M.

    1990-01-01

    During the case study from the First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment (FIRE) Intensive Field Observation (IFO), one airborne lidar system and four ground-based systems collected linear depolarization, intrinsically calibrated backscatter, and Doppler velocity information. Data presented describe the temporal evolution and spatial distribution of cirrus clouds over an area encompassing southern and central Wisconsin. Cirrus cloud types include dissipating subvisual and thin fibrous cirrus cloud bands, an isolated mesoscale uncinus complex, a large-scale, deep cloud that developed into an organized cirrus structure within the lidar array, and a series of intensifying mesoscale cirrus cloud masses. It is noted that the cirrus frequently developed in the vertical from particle fallstreaks emanating from generating regions at or near cloud tops; however, glaciating supercooled altocumulus clouds contributed to the production of ice mass at the base of the deep cirrus cloud.

  15. The eyesafe visioceilometer - A tactical visibility and cloud height lidar

    NASA Astrophysics Data System (ADS)

    Barnes, E. S.; Lentz, W. J.

    A recent breakthrough in the mathematical solution to the lidar equation combined with state-of-the-art microelectronics has made it possible to produce the first portable ceiling, visibility, and rangefinding device suitable for tactical use by the U.S. Army. The signal processor of the former XE-2 (Nd:YAG) can be adapted to an eyesafe unit by making use of an erbium glass laser and a GaInAs PIN photodiode detector. It is pointed out that the XE-3 (Eyesafe Visioceilometer) provides tactical real-time data when and where the user needs it, with an accuracy superior to existing nonportable runway equipment. Attention is given to system evolution, lidar theory, the relationship of backscattering and extinction coefficients, a system description, the transient recorder, the analysis of data, and details regarding tactical applications.

  16. Raman Lidar Measurements of Water Vapor and Cirrus Clouds During the Passage of Hurricane Bonnie

    NASA Technical Reports Server (NTRS)

    Whiteman, D. N.; Evans, K. D.; Demoz, B.; Starr, D. OC; Tobin, D.; Feltz, W.; Jedlovec, G. J.; Gutman, S. I.; Schwemmer, G. K.; Cardirola, M.; Melfi, S. H.; Schmidlin, F. J.

    2000-01-01

    The NASA/GSFC Scanning Raman Lidar (SRL) was stationed on Andros Island in the Bahamas during August - September, 1998 as a part of the third Convection and Moisture Experiment (CAMEX-3) which focussed on hurricane development and tracking. During the period August 21 - 24, hurricane Bonnie passed near Andros Island and influenced the water vapor and cirrus cloud measurements acquired by the SRL. Two drying signatures related to the hurricane were recorded by the SRL (Scanning Raman Lidar) and other sensors. Cirrus cloud optical depths (at 351 nm) were also measured during this period. Optical depth values ranged from approximately 0.01 to 1.4. The influence of multiple scattering on these optical depth measurements was studied with the conclusion that the measured values of optical depth are less than the actual value by up to 20% . The UV/IR cirrus cloud optical depth ratio was estimated based on a comparison of lidar and GOES measurements. Simple radiative transfer model calculations compared with GOES satellite brightness temperatures indicate that satellite radiances are significantly affected by the presence of cirrus clouds if IR optical depths are approximately 0.02 or greater. This has implications for satellite cirrus detection requirements.

  17. Remote sensing measurements of the CO2 mixing ratio in the planetary boundary layer using cloud slicing with airborne lidar

    NASA Astrophysics Data System (ADS)

    Ramanathan, Anand K.; Mao, Jianping; Abshire, James B.; Allan, Graham R.

    2015-03-01

    We have measured the CO2 volume mixing ratio (VMR) within the planetary boundary layer (PBL) using cloud slicing with an airborne pulsed integrated path differential absorption (IPDA) lidar from flight altitudes of up to 13 km. During a flight over Iowa in summer 2011, simultaneous measurement of the optical range and CO2 absorption to clouds and the ground were made using time-resolved detection of pulse echoes from each scattering surface. We determined the CO2 absorption in the PBL by differencing the two lidar-measured absorption line shapes, one to a broken shallow cumulus cloud layer located at the top of the PBL and the other to the ground. Solving for the CO2 VMR in the PBL and that of the free troposphere, we measured a ?15 ppm (4%) drawdown in the PBL. Both CO2 VMRs were within ?3 ppm of in situ CO2 profile measurements. We have also demonstrated cloud slicing using scatter from thin, diffuse cirrus clouds and cumulus clouds, which allowed solving for the CO2 VMR for three vertical layers. The technique and retrieval algorithm are applicable to a space-based lidar instrument as well as to lidar IPDA measurements of other trace gases. Thus, lidar cloud slicing also offers promise toward space-based remote sensing of vertical trace gas profiles in the atmosphere using a variety of clouds.

  18. Analyses of Semi-transparent Cirrus Clouds Using Combined Retrievals of CALIPSO Radiometer and Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Garnier, A.; Vaughan, M.; Pelon, J. R.; Winker, D. M.; Trepte, C. R.; Dubuisson, P.

    2014-12-01

    We present a detailed evaluation of cloud optical depths retrieved from perfectly co-located observations of semi-transparent cirrus made by the Imaging Infrared Radiometer (IIR) and the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP) flying on-board the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite. Analyses use Version 3 CALIOP Level 2 5-km cloud layer products and the corresponding Version 3 IIR Level 2 track products. Uncertainties are assessed by comparing IIR absorption optical depths retrieved at 12.05 microns to CALIOP visible optical depths for single-layered clouds over ocean when the latter can be derived using the so-called constrained retrieval technique. A bias in the optical depths used in CALIOP constrained retrievals is evidenced for optical depths smaller than about 0.6. This bias can be largely eliminated by relaxing the criteria applied in the current version 3 of the CALIOP algorithm to select the qualifying clouds. Ratios of CALIOP visible to IIR absorption optical depths are found to increase quasi-linearly by about 50% as the temperature at the layer centroid altitude decreases from 250 K to 200 K, whereas they are expected between 1.9 and 2 according to simulations and ice crystal effective diameters retrieved from the IIR. The analysis of simultaneously derived CALIOP lidar ratios of moderately deep clouds (1-4 km) strongly suggests that these observations can be explained by variations of the multiple scattering correction factor, which is taken to be constant and equal to 0.6 in the CALIOP algorithm. Multiple scattering factors derived by reconciling observed and expected ratios of visible to infrared absorption optical extend from 0.68 +/- 0.05 at 200 K to 0.46 +/- 0.03 at 250 K.

  19. Nineteenth International Laser Radar Conference. Part 2

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N. (Editor); Ismail, Syed (Editor); Schwemmer, Geary K. (Editor)

    1998-01-01

    This publication contains extended abstracts of papers presented at the Nineteenth International Laser Radar Conference, held at Annapolis, Maryland, July 6-10, 1998; 260 papers were presented in both oral and poster sessions. The topics of the conference sessions were Aerosol Clouds, Multiple Scattering; Tropospheric Profiling, Stratospheric/Mesospheric Profiling; Wind Profiling; New Lidar Technology and Techniques; Lidar Applications, Including Altimetry and Marine; Space and Future Lidar; and Lidar Commercialization/Eye Safety. This conference reflects the breadth of research activities being conducted in the lidar field. These abstracts address subjects from lidar-based atmospheric investigations, development of new lasers and lidar system technology, and current and future space-based lidar systems.

  20. Integrated radar and lidar analysis reveals extensive loss of remaining intact forest on Sumatra 2007-2010

    NASA Astrophysics Data System (ADS)

    Collins, M. B.; Mitchard, E. T. A.

    2015-06-01

    Forests with high above ground biomass (AGB), including those growing on peat swamps, have historically not been thought suitable for biomass mapping and change detection using Synthetic Aperture Radar (SAR). However, by integrating L-band (? = 0.23 m) SAR with lidar data from the ALOS and ICESat earth-observing satellites respectively, and 56 forest plots, we were able to create a forest biomass and change map for a 10.7 Mha section of eastern Sumatra that still contains high AGB peat swamp forest. Using a time series of SAR data we estimated changes in both forest area and AGB. We estimate that there were 274 ± 68 Tg AGB remaining in natural forest (≥ 20 m height) in the study area in 2007, with this stock reducing by approximately 11.4% over the subsequent 3 years. A total of 137.4 kha of the study area were deforested between 2007 and 2010; an average rate of 3.8% yr-1. The ability to attribute forest loss to different initial biomass values allows for far more effective monitoring and baseline modelling for avoided deforestation projects than traditional, optical-based remote sensing. Furthermore, given SAR's ability to penetrate the smoke and cloud which normally obscure land cover change in this region, SAR-based forest monitoring can be relied on to provide frequent imagery. This study demonstrates that even at L-band, which typically saturates at medium biomass levels (ca. 150 Mg ha-1), it is possible to make reliable estimates of not just the area but the carbon emissions resulting from land use change.

  1. Raman Lidar Measurements of Water Vapor and Cirrus Clouds During The Passage of Hurricane Bonnie

    NASA Technical Reports Server (NTRS)

    Whiteman, D. N.; Evans, K. D.; Demoz, B.; Starr, D OC.; Eloranta, E. W.; Tobin, D.; Feltz, W.; Jedlovec, G. J.; Gutman, S. I.; Schwemmer, G. K.; Smith, David E. (Technical Monitor)

    2000-01-01

    The NASA/GSFC Scanning Raman Lidar (SRL) was stationed on Andros Island in the Bahamas during August - September, 1998 as a part of the third Convection and Moisture Experiment (CAMEX-3) which focussed on hurricane development and tracking. During the period August 21 - 24, hurricane Bonnie passed near Andros Island and influenced the water vapor and cirrus cloud measurements acquired by the SRL. Two drying signatures related to the hurricane were recorded by the SRL and other sensors. Cirrus cloud optical depths (at 351 nm) were also measured during this period. Optical depth values ranged from less than 0.01 to 1.5. The influence of multiple scattering on these optical depth measurements was studied. A correction technique is presented which minimizes the influences of multiple scattering and derives information about cirrus cloud optical and physical properties. The UV/IR cirrus cloud optical depth ratio was estimated based on a comparison of lidar and GOES measurements. Simple radiative transfer model calculations compared with GOES satellite brightness temperatures indicate that satellite radiances are significantly affected by the presence of cirrus clouds if IR optical depths are approximately 0.005 or greater. Using the ISCCP detection threshold for cirrus clouds on the GOES data presented here, a high bias of up to 40% in the GOES precipitable water retrieval was found.

  2. Quality assessment of satellite retrieved cloud top temperature data with ground based 36 GHz radar measurements

    Microsoft Academic Search

    A. I. Weiss; C. Rathke

    2003-01-01

    Measurements of accurate cloud parameters are required for improvements and validations of climate and weather forecast models. Ground based microwave radars are a powerful tool to obtain various cloud parameters with a high spacial and temporal resolution. Likewise satellite observations of clouds are of high data assimilation interest, due to their large area coverage. A new algorithm was developed for

  3. Space-based laser for a cloud and aerosol backscatter lidar

    SciTech Connect

    Stadler, John H.; Hostetler, Chris A.; Williams-Byrd, Julie [National Aeronautics and Space Administration Langley Research Center, Hampton, Virginia 23681-2199 (United States); Hovis, Floyd [Fibertek, Inc., 510 Herndon Parkway, Herndon, Virginia 20170 (United States); Bradford, Charles M.; Schwiesow, Ron [Ball Aerospace and Technologies Corporation, 1600 Commerce Street, Boulder, Colorado 80306 (United States)

    1999-01-22

    NASA Langley Research Center in conjunction with Ball Aerospace and Technologies Corp., are developing a small, lightweight, diode-pumped Nd:YAG laser to enable a spaceborne backscatter lidar to measure clouds and aerosols. The frequency-doubled laser has total output energy of 220 mJ at 27 Hz. The laser has been specifically designed for space applications and features conductive cooling and a minimum three-year design life.

  4. Cloud and Aerosol Measurements from the GLAS Polar Orbiting Lidar: First Year Results

    NASA Technical Reports Server (NTRS)

    Spinhirne, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.; Welton, E. J.

    2004-01-01

    The Geoscience Laser Altimeter System (GLAS) launched in 2003 is the first polar orbiting satellite lidar. The instrument was designed for high performance observations of the distribution and optical scattering cross sections of clouds and aerosol. GLAS is approaching six months of on orbit data operation. These data from thousands of orbits illustrate the ability of space lidar to accurately and dramatically measure the height distribution of global cloud and aerosol to an unprecedented degree. There were many intended science applications of the GLAS data and significant results have already been realized. One application is the accurate height distribution and coverage of global cloud cover with one goal of defining the limitation and inaccuracies of passive retrievals. Comparison to MODIS cloud retrievals shows notable discrepancies. Initial comparisons to NOAA 14&15 satellite cloud retrievals show basic similarity in overall cloud coverage, but important differences in height distribution. Because of the especially poor performance of passive cloud retrievals in polar regions, and partly because of high orbit track densities, the GLAS measurements are by far the most accurate measurement of Arctic and Antarctica cloud cover from space to date. Global aerosol height profiling is a fundamentally new measurement from space with multiple applications. A most important aerosol application is providing input to global aerosol generation and transport models. Another is improved measurement of aerosol optical depth. Oceanic surface energy flux derivation from PBL and LCL height measurements is another application of GLAS data that is being pursued. A special area of work for GLAS data is the correction and application of multiple scattering effects. Stretching of surface return pulses in excess of 40 m from cloud propagation effects and other interesting multiple scattering phenomena have been observed. As an EOS project instrument, GLAS data products are openly available to the science community. First year results from GLAS are summarized.

  5. ASSESSMENT OF EZ LIDAR AND ARM\\/SGP MPL LIDAR PERFORMANCES FOR QUALITATIVE AND QUANTITATIVE MEASUREMENTS OF AEROSOL AND CLOUDS

    Microsoft Academic Search

    Simone Lolli; Laurent Sauvage; Iwona Stachlewska; Richard Coulter; Rob Newsom

    The objective of this work is to assess the performances of EZ LIDAR™ (EZ) instrument with regard to those of a Micro Pulse Lidar (MPL) type 4, deployed at the ARM site in South Great Plains, Oklahoma, in October 2006. Results show that EZ lidar measurements performances are equivalent to those of ARM site MPL Lidar. A quantitative assessment of

  6. Estimation of Microphysical and Radiative Parameters of Precipitating Cloud Systems Using mm-Wavelength Radars

    NASA Astrophysics Data System (ADS)

    Matrosov, Sergey Y.

    2009-03-01

    A remote sensing approach is described to retrieve cloud and rainfall parameters within the same precipitating system. This approach is based on mm-wavelength radar signal attenuation effects which are observed in a layer of liquid precipitation containing clouds and rainfall. The parameters of ice clouds in the upper part of startiform precipitating systems are then retrieved using the absolute measurements of radar reflectivity. In case of the ground-based radar location, these measurements are corrected for attenuation in the intervening layer of liquid hydrometers.

  7. Macrophysical properties of tropical cirrus clouds from the CALIPSO satellite and from ground-based micropulse and Raman lidars

    NASA Astrophysics Data System (ADS)

    Thorsen, Tyler J.; Fu, Qiang; Comstock, Jennifer M.; Sivaraman, Chitra; Vaughan, Mark A.; Winker, David M.; Turner, David D.

    2013-08-01

    Lidar observations of cirrus cloud macrophysical properties over the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program Darwin, Australia, site are compared from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, the ground-based ARM micropulse lidar (MPL), and the ARM Raman lidar (RL). Comparisons are made using the subset of profiles where the lidar beam is not fully attenuated. Daytime measurements using the RL are shown to be relatively unaffected by the solar background and are therefore suited for checking the validity of diurnal cycles. RL and CALIPSO cloud fraction profiles show good agreement while the MPL detects significantly less cirrus, particularly during the daytime. Both MPL and CALIPSO observations show that cirrus clouds occur less frequently during the day than at night at all altitudes. In contrast, the RL diurnal cycle is significantly different from zero only below about 11 km; where it is of opposite sign (i.e., more clouds during the daytime). For cirrus geometrical thickness, the MPL and CALIPSO observations agree well and both data sets have significantly thinner clouds during the daytime than the RL. From the examination of hourly MPL and RL cirrus cloud thickness and through the application of daytime detection limits to all CALIPSO data, we find that the decreased MPL and CALIPSO cloud thickness during the daytime is very likely a result of increased daytime noise. This study highlights the significant improvement the RL provides (compared to the MPL) in the ARM program's ability to observe tropical cirrus clouds and will help improve our understanding of these clouds. The RL also provides a valuable ground-based lidar data set for the evaluation of CALIPSO observations.

  8. Simulation of Lidar Return Signals Associated with Water Clouds

    E-print Network

    Lu, Jianxu

    2010-01-14

    wa- ter clouds. The relationship is found to be sensitive to the extinction coefficient and to the particle size. The layer integrated attenuated backscatter is also obtained. Comparisons made between the simulations and statistics derived...

  9. A Compact Airborne High Spectral Resolution Lidar for Observations of Aerosol and Cloud Optical Properties

    NASA Technical Reports Server (NTRS)

    Hostetler, Chris A.; Hair, John W.; Cook, Anthony L.

    2002-01-01

    We are in the process of developing a nadir-viewing, aircraft-based high spectral resolution lidar (HSRL) at NASA Langley Research Center. The system is designed to measure backscatter and extinction of aerosols and tenuous clouds. The primary uses of the instrument will be to validate spaceborne aerosol and cloud observations, carry out regional process studies, and assess the predictions of chemical transport models. In this paper, we provide an overview of the instrument design and present the results of simulations showing the instrument's capability to accurately measure extinction and extinction-to-backscatter ratio.

  10. Improved simulation of aerosol, cloud, and density measurements by shuttle lidar

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Morley, B. M.; Livingston, J. M.; Grams, G. W.; Patterson, E. W.

    1981-01-01

    Data retrievals are simulated for a Nd:YAG lidar suitable for early flight on the space shuttle. Maximum assumed vertical and horizontal resolutions are 0.1 and 100 km, respectively, in the boundary layer, increasing to 2 and 2000 km in the mesosphere. Aerosol and cloud retrievals are simulated using 1.06 and 0.53 microns wavelengths independently. Error sources include signal measurement, conventional density information, atmospheric transmission, and lidar calibration. By day, tenuous clouds and Saharan and boundary layer aerosols are retrieved at both wavelengths. By night, these constituents are retrieved, plus upper tropospheric, stratospheric, and mesospheric aerosols and noctilucent clouds. Density, temperature, and improved aerosol and cloud retrievals are simulated by combining signals at 0.35, 1.06, and 0.53 microns. Particlate contamination limits the technique to the cloud free upper troposphere and above. Error bars automatically show effect of this contamination, as well as errors in absolute density nonmalization, reference temperature or pressure, and the sources listed above. For nonvolcanic conditions, relative density profiles have rms errors of 0.54 to 2% in the upper troposphere and stratosphere. Temperature profiles have rms errors of 1.2 to 2.5 K and can define the tropopause to 0.5 km and higher wave structures to 1 or 2 km.

  11. Combined microwave and optical remote sensing of clouds: a review

    Microsoft Academic Search

    Kenneth Sassen

    1995-01-01

    Joint cloud remote sensing research using radar, lidar, and passive optical and microwave techniques began over 25 years ago, not long after the development of field-worthy laser systems. Concurrent field measurements of thunderstorm clouds and anvils were made in 1970 by a polarization ruby (0.69 ?m) lidar transported from New York University and a scanning 10-cm radar system from the

  12. Polarization properties of lidar scattering from clouds at 347 nm and 694 nm.

    PubMed

    Pal, S R; Carswell, A I

    1978-08-01

    The polarization characteristics of lidar scattering from cumulus and low-lying shower clouds have been measured with a system operating at 694 nm (red) and 347 nm (blue). The backscatter profiles of the polarization components as well as of the total intensity of the return are presented and discussed for the two wavelengths. The linear depolarization ratio delta, which can be used as a measure of the unpolarized multiple scattering, has been obtained at both wavelengths. This quantity has a very low value at cloud base for both wavelengths and increases with pulse penetration. The blue registers generally higher values of a within the cloud. The measured total intensity backscatter functions for both wavelengths are presented and discussed in relation to theoretical calculations of cloud models. PMID:20203781

  13. Operational processing and cloud boundary detection from micro pulse lidar data

    NASA Technical Reports Server (NTRS)

    Campbell, James R.; Hlavka, Dennis L.; Spinhirne, James D.; Scott, V. Stanley., III; Turner, David D.

    1998-01-01

    Micro Pulse Lidar (MPL) was developed at NASA Goddard Space Flight Center (GSFC) as the result of research on space-borne lidar techniques. It was designed to provide continuous, unattended observations of all significant atmospheric cloud and aerosol structure with a rugged, compact system design and the benefit of eye safety (Spinhirne 1993). The significant eye safety feature is achieved by using low pulse energies and high pulse repetition rates compared to standard lidar systems. MPL systems use a diode pumped 10 microj, 2500 Hz doubled Nd:YLF laser. In addition, a solid state Geiger mode avalanche photo diode (GAPD) photon counting detector is used allowing for quantum efficiencies approaching 70%. Other design features have previously been noted by Spinhirne (1995). Though a commercially available instrument, with nearly 20 systems operating around the world, the most extensive MPL work has come from those operated by the Atmospheric Radiation Measurement (ARM) (Stokes and Schwartz 1994) program. The diverse ability of the instrument relating to the measurement of basic cloud macrophysical structure and both cloud and aerosol radiative properties well suits the ARM research philosophy. MPL data can be used to yield many parameters including cloud boundary heights to the limit of signal attenuation, cloud scattering cross sections and optical thicknesses, planetary boundary layer heights and aerosol scattering profiles, including those into the stratosphere in nighttime cases (Hlavka et al 1996). System vertical resolution ranges from 30 m to 300 m (i.e. high and low resolution respectively) depending on system design. The lidar research group at GSFC plays an advisory role in the operation, calibration and maintenance of NASA and ARM owned MPL systems. Over the past three years, processing software and system correction techniques have been developed in anticipation of the increasing population of systems amongst the community. Datasets produced by three ARM-owned systems have served as the basis for this development. With two operating at the southern Great Plains Cloud and Radiation Testbed Site (SGP CART) since December 1993 and another at the Manus Island Atmospheric Radiation and Cloud Station (TWP ARCS) location in the tropical western Pacific since February 1997, the ARM archive contains over 4 years of observations. In addition, high resolution systems planning to come on-line at the North Slope, AK CART shortly with another scheduled to follow at the TWP ARCS-II will diversify this archive with more extensive observations.

  14. A Method to Merge WSR-88D Data with ARM SGP Millimeter Cloud Radar Data by Studying Deep Convective Systems

    E-print Network

    Dong, Xiquan

    A Method to Merge WSR-88D Data with ARM SGP Millimeter Cloud Radar Data by Studying Deep Convective A decade of collocated Atmospheric Radiation Measurement Program (ARM) 35-GHz Millimeter Cloud Radar (MMCR) and Weather Surveillance Radar-1988 Doppler (WSR-88D) data over the ARM Southern Great Plains (SGP) site have

  15. Polar stratospheric clouds over McMurdo, Antarctica, during the 1991 spring: Lidar and particle counter measurements

    Microsoft Academic Search

    A. Adriani; T. Deshler; G. P. Gobbi; B. J. Johnson; G. Di. Donfrancesco

    1992-01-01

    Lidar and balloonborne particle counter measurements were performed simultaneously on two days when polar stratospheric clouds were observed in late August 1991 at McMurdo, Antarctica. Both nitric acid trihydrate and ice clouds were observed in the lower stratosphere between 10 and 23 km in different formation stages and with different cooling rate; however in all cases the size distributions were

  16. [The estimation of cirrus cloud particulate shape using combined simulation and a three-wavelength lidar measurement].

    PubMed

    Tao, Zong-Ming; Liu, Dong; Wei, He-Li; Ma, Xiao-Min; Shi, Bo; Nie, Miao; Zhou, Jun; Wang, Ying-Jian

    2013-07-01

    The global occurrence of cirrus clouds can reach as high as 30%, whose scattering properties are essential impact on the climatic model, radiative transfer, and remote sensing. Their scattering properties are determined by the ice crystal shape, size distribution, refractive index and so on. Retrieval of the backscattering color ratios of cirrus cloud using a 355, 532 and 1 064 nm three-wavelength lidar, combined with the simulation of the three backscattering color ratios of different ice crystal shape, the shape of the lidar-measured ice crystal can be estimated. The results indicate that the shape of cirrus cloud over Hefei city is mostly composed by aggregates. PMID:24059165

  17. ARSCL POST-ARRA: UPCOMING CLOUD RADAR VALUE-ADDED PRODUCTS Karen Johnson, Brookhaven National Laboratory

    E-print Network

    ARSCL POST-ARRA: UPCOMING CLOUD RADAR VALUE-ADDED PRODUCTS Karen Johnson, Brookhaven National Laboratory Pavlos Kollias, McGill University Scott Giangrande, Brookhaven National Laboratory David Troyan, Brookhaven National Laboratory Michael Jensen, Brookhaven National Laboratory Eugene Clothiaux

  18. Long-term lidar observations of polar stratospheric clouds at Esrange in northern Sweden

    NASA Astrophysics Data System (ADS)

    Blum, U.; Fricke, K. H.; Müller, K. P.; Siebert, J.; Baumgarten, G.

    2005-11-01

    Polar stratospheric clouds (PSCs) play a key role in the depletion of polar ozone. The type of cloud and the length of time for which it exists are crucial for the amount of chlorine activation during the polar night. The Bonn University backscatter lidar at Esrange in northern Sweden (68°N, 21°E) is well equipped for long-term observation and classification of these clouds. Nearly continuous measurements through several winters are rare, in particular in wave-active regions like Esrange. Lidar measurements have been performed each winter since 1997—a total of more than 2000 h of observation time has been accumulated, including more than 300 h with PSCs. Analysis of this unique data set leads to a classification scheme with four different scattering characteristics which can be associated with four different cloud types: (1) supercooled ternary solution (STS), (2) nitric acid trihydrate (NAT), (3) ice and (4) mixtures of solid and liquid particles. The analysis of observations over seven winters gives an overview of the frequency of appearance of the individual PSC types. Most of the clouds contain layers of different PSC types. The analysis of these layers shows STS and mixed clouds to occur most frequently, with more than 39% and 37% of all PSC observations, respectively, whereas NAT (15%) and ice clouds (9%) are seen only rarely. The lidar is located close to the Scandinavian mountain ridge, which is a major source of orographically induced gravity waves that can rapidly cool the atmosphere below cloud formation temperatures. Comparing the individual existence temperature of the observed cloud type with the synoptic-scale temperature provided by the European Centre for Medium-range Weather Forecasts (ECMWF) gives information on the frequency of synoptically and wave-induced PSCs. Further, the analysis of ECMWF temperature and wind data gives an estimate of the transparency of the atmosphere to stationary gravity waves. During more than 80% of all PSC observations in synoptic-scale temperatures which were too warm the atmosphere was transparent for stationary gravity waves. Our measurements show that dynamically induced cooling is crucial for the existence of PSCs above Esrange. In particular ice PSCs are observed only in situations where there are gravity waves.

  19. First temperature measurements within Polar Stratospheric Clouds with the Esrange lidar

    NASA Astrophysics Data System (ADS)

    Achtert, Peggy; Khaplanov, Mikhail; Khosrawi, Farahnaz; Gumbel, Jörg

    2013-04-01

    In the winter stratosphere polar stratospheric clouds (PSCs) provide the surface for heterogeneous reactions which transform stable chlorine and bromine species into their highly reactive ozone-destroying states. PSCs are classified into three types (PSC Ia: nitric acid di- or trihydrate crystals, NAD or NAT; PSC Ib: supercooled liquid ternary solutions, STS; PSC II: ice) according to their particle composition and to their physical phase. The formation of PSCs depends strongly on temperature. For a comprehensive understanding of such temperature-dependent processes in the lower stratosphere, lidar measurements using the rotational-Raman technique are most suitable. The rotational-Raman technique allows for temperature measurements without a priori assumptions of the state of the atmosphere. The technique is feasible in aerosol layers and clouds, such as PSCs. A rotational-Raman channel for temperature measurements in the upper troposphere and lower stratosphere was added to the Esrange lidar in late 2010. The Esrange lidar operates at Esrange (68°N, 21°E) near the Swedish city of Kiruna. By combining rotational-Raman measurements (4-35 km height) and the integration technique (30-80 km height), the Esrange lidar is now capable of measuring atmospheric temperature profiles from the upper troposphere up to the mesosphere. Such measurements could be used to validate current lidar-based PSC classification schemes and the current understanding of PSC formation. The new capability of the instrument furthermore enables the studies of other clouds layers, temperature variations and exchange processes in the upper troposphere/lower stratosphere. These studies will take advantage of the geographical location of Esrange where mountain wave activity in the lee of the Scandinavian mountain range gives rise to a wide range of PSC growth conditions. Although several lidars are operated at polar latitudes, there are few instruments that are capable of measuring temperature profiles in the troposphere, stratosphere, and mesosphere, as well as aerosols extinction in the troposphere and lower stratosphere. In this study, we utilize measurements of PSCs and temperature during the winters 2010/11, 2011/12, and 2012/13 to gain insight into the temperature dependence of different PSC types.

  20. a Data Driven Method for Building Reconstruction from LiDAR Point Clouds

    NASA Astrophysics Data System (ADS)

    Sajadian, M.; Arefi, H.

    2014-10-01

    Airborne laser scanning, commonly referred to as LiDAR, is a superior technology for three-dimensional data acquisition from Earth's surface with high speed and density. Building reconstruction is one of the main applications of LiDAR system which is considered in this study. For a 3D reconstruction of the buildings, the buildings points should be first separated from the other points such as; ground and vegetation. In this paper, a multi-agent strategy has been proposed for simultaneous extraction and segmentation of buildings from LiDAR point clouds. Height values, number of returned pulse, length of triangles, direction of normal vectors, and area are five criteria which have been utilized in this step. Next, the building edge points are detected using a new method named "Grid Erosion". A RANSAC based technique has been employed for edge line extraction. Regularization constraints are performed to achieve the final lines. Finally, by modelling of the roofs and walls, 3D building model is reconstructed. The results indicate that the proposed method could successfully extract the building from LiDAR data and generate the building models automatically. A qualitative and quantitative assessment of the proposed method is then provided.

  1. Aerosol and cloud sensing with the Lidar In-space Technology Experiment (LITE)

    NASA Technical Reports Server (NTRS)

    Winker, D. M.; McCormick, M. P.

    1994-01-01

    The Lidar In-space Technology Experiment (LITE) is a multi-wavelength backscatter lidar developed by NASA Langley Research Center to fly on the Space Shuttle. The LITE instrument is built around a three-wavelength ND:YAG laser and a 1-meter diameter telescope. The laser operates at 10 Hz and produces about 500 mJ per pulse at 1064 nm and 532 nm, and 150 mJ per pulse at 355 nm. The objective of the LITE program is to develop the engineering processes required for space lidar and to demonstrate applications of space-based lidar to remote sensing of the atmosphere. The LITE instrument was designed to study a wide range of cloud and aerosol phenomena. To this end, a comprehensive program of scientific investigations has been planned for the upcoming mission. Simulations of on-orbit performance show the instrument has sufficient sensitivity to detect even thin cirrus on a single-shot basis. Signal averaging provides the capability of measuring the height and structure of the planetary boundary layer, aerosols in the free troposphere, the stratospheric aerosol layer, and density profiles to an altitude of 40 km. The instrument has successfully completed a ground-test phase and is scheduled to fly on the Space Shuttle Discovery for a 9-day mission in September 1994.

  2. Model interpretation of cloud observations by the LIDAR on the Phoenix Mars lander

    NASA Astrophysics Data System (ADS)

    Daerden, Frank; Whiteway, J. A.; Davy, R.; Komguem, L.; Dickinson, C.; Taylor, P. A.

    2010-05-01

    Phoenix LIDAR observations [Whiteway et al. 2009] of clouds and precipitation in the planetary boundary layer (PBL) on Mars have been interpreted by a microphysical model for Mars ice clouds in combination with a coupled PBL-Aeolian dust model [Davy et al. 2009, Daerden et al. 2010]. The model simulates nighttime clouds and fall streaks within the PBL that are similar in structure to the LIDAR observations. Sizes of precipitating crystals grow to sizes of 30-50 µm effective radius, comparable to ice crystals observed in precipitation from terrestrial cirrus clouds which are formed under similar meteorological conditions. The observed regular daily pattern of water ice cloud formation and precipitation in the PBL is indicative of a diurnal process in the local water cycle in which the combination of strong daytime vertical mixing and nighttime precipitation of large ice crystals acts to confine water to the PBL [Whiteway et al. 2009]. The simulations support this interpretation. This process may contribute to the seasonal variation of atmospheric humidity. References Daerden, F., J.A. Whiteway, R. Davy, C. Verhoeven, L. Komguem, C. Dickinson, P. A. Taylor, N. Larsen (2010), Simulating Observed Boundary Layer Clouds on Mars, Geophys. Res. Lett., in press Davy, R., P. A. Taylor, W. Weng, and P.-Y. Li (2009), A model of dust in the Martian lower atmosphere, J. Geophys. Res., 114, D04108, doi:10.1029/2008JD010481 Whiteway, J.A., L. Komguem, C. Dickinson, C. Cook, M. Illnicki, J. Seabrook, V. Popovici, T.J. Duck, R. Davy, P.A. Taylor, J. Pathak, D. Fisher, A.I. Carswell, M. Daly, V. Hipkin, L. Tamppari, N. Renno, J. Moores, M. Lemmon, F. Daerden, H. Smith (2009), Mars Water Ice Clouds and Precipitation, Science 325, 68

  3. Simulation of Space-borne Radar Observation from High Resolution Cloud Model - for GPM Dual frequency Precipitation Radar -

    NASA Astrophysics Data System (ADS)

    Kim, H.; Meneghini, R.; Jones, J.; Liao, L.

    2011-12-01

    A comprehensive space-borne radar simulator has been developed to support active microwave sensor satellite missions. The two major objectives of this study are: 1) to develop a radar simulator optimized for the Dual-frequency Precipitation Radar (KuPR and KaPR) on the Global Precipitation Measurement Mission satellite (GPM-DPR) and 2) to generate the synthetic test datasets for DPR algorithm development. This simulator consists of two modules: a DPR scanning configuration module and a forward module that generates atmospheric and surface radar observations. To generate realistic DPR test data, the scanning configuration module specifies the technical characteristics of DPR sensor and emulates the scanning geometry of the DPR with a inner swath of about 120 km, which contains matched-beam data from both frequencies, and an outer swath from 120 to 245 km over which only Ku-band data will be acquired. The second module is a forward model used to compute radar observables (reflectivity, attenuation and polarimetric variables) from input model variables including temperature, pressure and water content (rain water, cloud water, cloud ice, snow, graupel and water vapor) over the radar resolution volume. Presently, the input data to the simulator come from the Goddard Cumulus Ensemble (GCE) and Weather Research and Forecast (WRF) models where a constant mass density is assumed for each species with a particle size distribution given by an exponential distribution with fixed intercept parameter (N0) and a slope parameter (?) determined from the equivalent water content. Although the model data do not presently contain mixed phase hydrometeors, the Yokoyama-Tanaka melting model is used along with the Bruggeman effective dielectric constant to replace rain and snow particles, where both are present, with mixed phase particles while preserving the snow/water fraction. For testing one of the DPR retrieval algorithms, the Surface Reference Technique (SRT), the simulator uses the normalized radar cross sections of the surface,?0, at each frequency and incidence angle to generate the radar return power from the surface. The simulated ?0 data are modeled as realizations from jointly Gaussian random variables with means, variances and correlations obtained from measurements of ?0 from the JPL APR2 (2nd generation Airborne Precipitation Radar) data, which operates at approximately the same frequencies as the DPR. We will discuss the general capabilities of the radar simulator, present some sample results and show how they can be used to assess the performance of the radar retrieval algorithms proposed for the Dual-Frequency GPM radar. In addition, we will report on updates to the simulator using inputs from cloud models with spectral bin microphysics.

  4. Estimating forest structure at five tropical forested sites using lidar point cloud data

    NASA Astrophysics Data System (ADS)

    Palace, M. W.; Sullivan, F.; Treuhaft, R. N.; Keller, M. M.

    2014-12-01

    Tropical forests are fundamental components in the global carbon cycle and are threatened by deforestation and climate change. Because of their importance in carbon dynamics, understanding the structural architecture of these forests is vital. Airborne lidar data provides a unique opportunity to examine not only the height of these forests, which is often used to estimate biomass, but also the crown geometry and vertical profile of the canopy. These structural attributes inform temporal and spatial apsects of carbon dynamics providing insight into the past disturbances and growth of forests. We examined airborne lidar point cloud data from five sites in the Brazilian Amazon collected during the years 2012 to 2014. We generated both digital elevation maps, canopy height models (CHM), and vertical vegetation profiles (VVP) in our analysis. We analyzed the CHM using crown delineation with an iterative maximum finding routine to find the tops of canopies, local maxima to determine edges of crowns, and two parameters that control termination of crown edges. We also ran textural analysis methods on the CHM and VVP. Using multiple linear regression models and boosted regression trees we estimated forest structural parameters including biomass, stem density, basal area, width and depth of crowns and stem size distribution. Structural attributes estimated from lidar point cloud data can improve our understanding of the carbon dynamics of tropical forests on a landscape level and regional level.

  5. Corona-producing cirrus cloud properties derived from polarization lidar and photographic analyses.

    PubMed

    Sassen, K

    1991-08-20

    Polarization lidar data are used to demonstrate that clouds composed of hexagonal ice crystals can generate multiple-ringed colored coronas. Although relatively uncommon in our mid-latitude cirrus sample (derived from Project FIRE extended time observations), the coronas are associated with unusual cloud conditions that appear to be effective in generating the displays. Invariably, the cirrus cloud tops are located at or slightly above elevated tropopauses (12.7-km MSL average height) at temperatures between -60 degrees and -70 degrees C. The cloud top region also generates relatively strong laser backscattering and unusually high 0.5-0.7 linear depolarization ratios. Color photograph analysis of corona ring angles indicates crystals with mean diameters of from 12 to 30 microm. The cirrus cloud types were mainly subvisual to thin (i.e., bluish-colored) cirrostratus, but also included fibrous cirrus. Estimated cloud optical thicknesses at the 0.694-microm laser wavelength ranged from 0.001 to 0.2, where the upper limit reflects the effects of multiple scattering and/or unfavorable changes in particle characteristics in deep cirrus clouds. PMID:20706407

  6. Active probing of cloud multiple scattering, optical depth, vertical thickness, and liquid water content using wide-angle imaging LIDAR.

    SciTech Connect

    Love, Steven P.; Davis, A. B. (Anthony B.); Rohde, C. A. (Charles A.); Tellier, L. L. (Larry L.); Ho, Cheng,

    2002-01-01

    At most optical wavelengths, laser light in a cloud lidar experiment is not absorbed but merely scattered out of the beam, eventually escaping the cloud via multiple scattering. There is much information available in this light scattered far from the input beam, information ignored by traditional 'on-beam' lidar. Monitoring these off-beam returns in a fully space- and time-resolved manner is the essence of our unique instrument, Wide Angle Imaging Lidar (WAIL). In effect, WAIL produces wide-field (60-degree full-angle) 'movies' of the scattering process and records the cloud's radiative Green functions. A direct data product of WAIL is the distribution of photon path lengths resulting from multiple scattering in the cloud. Following insights from diffusion theory, we can use the measured Green functions to infer the physical thickness and optical depth of the cloud layer, and, from there, estimate the volume-averaged liquid water content. WAIL is notable in that it is applicable to optically thick clouds, a regime in which traditional lidar is reduced to ceilometry. Here we present recent WAIL data oti various clouds and discuss the extension of WAIL to full diurnal monitoring by means of an ultra-narrow magneto-optic atomic line filter for daytime measurements.

  7. The Study of Verification and Correction of Cloud Base and Top Height Retrievals from Ka-band Cloud Radar in Boseong, Korea during Fall 2013

    NASA Astrophysics Data System (ADS)

    Kim, Y. H.; Oh, S. B.; Kim, K. H.; Cho, C. H.

    2014-12-01

    In this study, the cloud base and top heights observed by Ka-band (33.44 GHz) cloud radar at the Boseong National Center for Intensive Observation of severe weather (NCIO) in Korea during the fall of 2013 (September to November) were verified and corrected. For comparative verification, the base and top heights data obtained from ceilometer (CL51) and Communication, Ocean and Meteorological Satellite (COMS), respectively were used. During rainfall, the cloud base and top heights observed by the cloud radar were lower than that observed by ceilometer-COMS due to signal attenuation and reflectivity caused by raindrops. The stronger rainfall intensity gets, the more the difference grows. In the case of rainfall, the base and top heights data from cloud radar could be replaced with these obtained data from ceilometer-COMS. In the case of no rainfall, the cloud base and top heights observed by the cloud radar and ceilometer-COMS were relatively similar. The clouds with thin thickness or low density were more effectively observed in cloud radar compared to ceilometer-COMS. Based on these results, in case of rainfall or missing cloud radar data, the ceilometer and COMS data were effectively used to correct the cloud radar data. These corrected cloud data were used to classify the cloud types of low (Cloud base height (CBH) < 2 km), middle (2 km ? CBH < 6 km), and high (CBH ? 6 km) clouds, and it was shown that the frequency of occurrence for low clouds were highest. When the low clouds were further subdivided, the most common type was shown to be deep precipitable clouds (CBH < 200 m and Cloud top height (CTH) ? 2 km), followed by non-precipitable clouds (200 m ? CBH < 2 km) and shallow precipitable clouds (CBH < 200 m and CTH < 2 km) in this order.

  8. Lidar data inversion for Cirrus clouds: An approach based on a statistical analysis of in situ microphysical measurements

    SciTech Connect

    Febvre, G. [Univ. Blaise Pascal, Clermont-Ferrand (France)] [Univ. Blaise Pascal, Clermont-Ferrand (France)

    1994-10-01

    The problem of the lidar equation inversion lies in the fact that it requires a lidar calibration or else a reference value from the studied medium. This paper presents an approach to calibrate the lidar by calculating the constant Ak (lidar constant A multiplied by the ratio of backscatter coefficient to extinction coefficient k). This approach is based on statistical analysis of in situ measurements. This analysis demonstrates that the extinction coefficient has a typical probablility distribution in cirrus clouds. The property of this distribution, as far as the attenuation of laser beam in the cloud, is used as a constraint to calculate the value of Ak. The validity of this method is discussed and results compared with two other inversion methods.

  9. Characterization of sub-cloud vertical velocity distributions and precipitation-driven outflow dynamics using a ship-based, scanning Doppler lidar during VOCALS-Rex

    NASA Astrophysics Data System (ADS)

    Brewer, A.; Feingold, G.; Tucker, S. C.; Covert, D. S.; Hardesty, R.

    2010-12-01

    During the VOCALS Regional Experiment NOAA's High Resolution Doppler Lidar (HRDL) operated from the RV Ronald H. Brown and made continuous measurements of sub-cloud horizontal and vertical wind speed and aerosol backscatter signal strength. We will present averaged profiles of vertical velocity distributions and turbulence parameters, stratified by a range of conditions including diurnal variation, precipitation, and distance from shore. The results point to a strong diurnal dependence in the strength of turbulence with nighttime conditions exhibiting stronger subcloud variance. Skewness shows less diurnal sensitivity with a trend towards more negative skewness near cloud base. Combining HRDL’s scanning horizontal wind speed measurements with other ship based in-situ and remote sensing measurements, we investigate the dynamics of precipitation-driven outflows and their impact on surface thermodynamic and aerosol properties. Using a sample of over 150 airmass transitions over the course of the 5 week deployment, we observed that warmer outflow air is typically drier, has less aerosol scattering and tends to have higher ozone concentrations (indicating the transport of air from above the boundary layer top). Transitions to cooler air are generally moister, have more aerosol scattering and show no significant change in ozone concentration. We will present animations of combined lidar/radar/GOES imagery that were used to facilitate visualization and interpretation of the dynamics of the outflows.

  10. Global distribution of instantaneous daytime radiative effects of high thin clouds observed by the cloud profiling radar

    NASA Astrophysics Data System (ADS)

    Lee, Yong-Keun; Greenwald, Thomas J.; Yang, Ping; Ackerman, Steve; Huang, Hung-Lung

    2010-09-01

    The instantaneous daytime geographical distribution and radiative effects of high thin clouds (optical thickness < 5) are investigated on the basis of the CloudSat Cloud Profiling Radar (CPR) radiative flux and cloud classification products. The regional features of the fraction and radiative effects of high thin clouds are associated with ITCZ, SPCZ and mid-latitude storm track regions. High thin clouds have positive net cloud-induced radiative effect (CRE) at the top of the atmosphere (TOA) and negative net CRE at the bottom of the atmosphere (BOA). The magnitudes of TOA and BOA CREs depend on cloud optical thickness, cloud fraction and geographical location. The magnitude of the net CRE of high thin clouds increases at both TOA and BOA as cloud optical thickness increases. Net CRE at both TOA and BOA contributes to a positive net CRE in-atmosphere and warms the atmosphere regardless of cloud fraction. The global annual mean of the net CRE multiplied by cloud fraction is 0.49 W/m2 at TOA, -0.54 W/m2 at BOA and 1.03 W/m2 in-atmosphere. The most radiatively effective cloud optical thickness of a high thin cloud is between 1-2 for the TOA and in-atmosphere CREs or 3-4 for the BOA CRE.

  11. Lidar observations of polar mesospheric clouds at Rothera, Antarctica (67.5S, 68.0W)

    E-print Network

    Chu, Xinzhao

    Lidar observations of polar mesospheric clouds at Rothera, Antarctica (67.5°°S, 68.0°°W) Xinzhao lidar at Rothera (67.5°S, 68.0°W), Antarctica in the austral summer of 2002­2003. The Rothera PMC at Rothera, Antarctica (67.5°S, 68.0°W), Geophys. Res. Lett., 31, L02114, doi:10.1029/ 2003GL018638. 1

  12. Southern Hemisphere Lidar Measurements of the Aerosol Clouds from Mt. Pinatubo and Mt. Hudson

    NASA Technical Reports Server (NTRS)

    Young, Stuart A.; Manson, Peter J.; Patterson, Graeme R.

    1992-01-01

    On 19 Jul., 1991, during tests to determine the ability of the newly-modified CSIRO Ns:YAG lidar to measure signals from the stratosphere before the arrival of dust from the eruption of Mt. Pinatubo, a strongly scattering layer was detected at an altitude of 2 km. That evening, the spectacular sunset and twilight were typical of volcanically disturbed conditions. Lidar measurements at 532 nm were made between 1400 and 1500 EST (0400-0500 UT) on 19 Jul. through broken cloud. Approximately 3800 laser firings were averaged in 256 shot blocks. These and subsequent data have been analyzed to produce profiles of aerosol volume backscatter function and scattering ratio. Clouds again prevented a clear view of the twilights on the next two nights, although there was some evidence for an enhanced glow. The evidence suggested that the aerosol layer had disappeared. An explanation for this disappearance and the earlier than expected arrival of the layer over Melbourne was required. Nimbus 7 TOMS data for 23 Jun. showed that the SO2 from the eruption had extended at least 11000 km to the west and that the southern boundary of the cloud had reached 15 degrees S just 8 days after the climactic eruption. It can be assumed that this cloud also contained dust and sulphuric acid aerosol. It was proposed that a section had then been broken away from the main cloud and carried south by a large scale eddy between the low latitude easterlies and the strong mid-latitude westerlies which finally carried the aerosol cloud over southern Australia. Accompanying 30 mb wind data showed a counter clockwise circulation, responsible for the transport, located in the South Atlantic Ocean.

  13. Characterization of mid-latitude cirrus cloud with airborne and ground-based lidar measurements during ML_CIRRUS

    NASA Astrophysics Data System (ADS)

    Gross, Silke; Forster, Linda; Wirth, Martin; Schäfler, Andreas; Freudenthaler, Volker; Fix, Andreas; Mayer, Bernhard

    2015-04-01

    Cirrus clouds have a large impact on the Earth's climate and radiation budget, but their microphysical and radiative properties are still insufficiently understood. As these parameters are difficult to measure, our knowledge of the radiative effect of cirrus clouds is mainly based on theoretical simulations. But these simulations use idealized cloud structure and microphysics, as well as radiative transfer approximations. To improve our knowledge of mid-latitude cirrus clouds, measurements onboard the German research aircraft HALO were performed during the ML_CIRRUS campaign over Europe in March and April 2014. During ML_CIRRUS an extensive combination of in-situ and remote sensing instrumentation was used to study the microphysical, optical and radiative properties of cirrus clouds with respect to cirrus cloud formation and life time. During ML_CIRRUS the airborne water vapor differential absorption and high spectral resolution lidar WALES of DLR-Institute of Atmospheric Physics was operational onboard HALO to measure the 2-dimensional humidity distribution inside and outside of cirrus clouds as well as the cirrus clouds optical properties along the flight track. We will present first results of correlated analyses of the optical cirrus cloud properties and the relative humidity in- and outside the cloud, as well as on the distribution of relative humidity and optical properties within the cloud. In particular we investigate differences of the cirrus cloud properties with respect to cirrus cloud formation and life-time. Additionally, we will show first results of ground-based depolarization lidar measurements with the lidar system POLIS of Meteorological Institute of the LMU to study the optical properties of clouds considering different optical phenomena of the cirrus clouds.

  14. Breakthrough in multichannel laser-radar technology providing thousands of high-sensitive lidar receivers on a chip

    NASA Astrophysics Data System (ADS)

    Schwarte, Rudolf M.

    2004-11-01

    The purpose of this paper is to describe a new proved multi-channel laser-radar technology which enables several thousands of high-sensitive laser-radar or lidar receivers to be integrated on a fingernail-sized CMOS-chip for fast 3D-perception and, furthermore, to explain the huge number of resulting applications and to estimate the desirable scientific, economic and society impacts. These extraordinary capabilities rely on the revolutionary improvements introduced by a smart inherently-mixing photodiode with two controllable photo-current outputs [1]. We call it PMD (Photonic Mixer Device) because the opto-electronic mixing process is accomplished directly in the photonic state, followed by an integration process to get OE-correlation and the delay of the optical echo and the modulation signal. The PMD-principle provides an unbelievable simplification, size-reduction and improvement in Multi-Channel Light Detecting and Ranging as a MC-PMD-Lidar or 3D-PMD-camera without scanner. Thanks to the competence and merit of the PMDTechnologies GmbH in cooperation with the INV of the University of Siegen finally brought the PMD in big steps to reliability and to large pixel numbers and to products with today about 20.000 lidar receivers in a 120x160 PMD-matrix, which exhibits homogenous and exquisite specifications like very constant mean value and low standard deviation compared with conventional radar receivers. This innovation may be seen as a breakthrough in the history of camera development. The "3D-camera" of today comprises more 3D-pixels in a PMD-array than, about 1970, the first CCD-cameras contained 2D-pixel in a CCD-array. Both are of similar size aside from the modulated sender with integrated LED's or laser diodes required for a homogenous illumination of the field-of-view.

  15. Global Lidar Measurements of Clouds and Aerosols from Space Using the Geoscience Laser Altimeter System (GLAS)

    NASA Technical Reports Server (NTRS)

    Hlavka, Dennis L.; Palm, S. P.; Welton, E. J.; Hart, W. D.; Spinhirne, J. D.; McGill, M.; Mahesh, A.; Starr, David OC. (Technical Monitor)

    2001-01-01

    The Geoscience Laser Altimeter System (GLAS) is scheduled for launch on the ICESat satellite as part of the NASA EOS mission in 2002. GLAS will be used to perform high resolution surface altimetry and will also provide a continuously operating atmospheric lidar to profile clouds, aerosols, and the planetary boundary layer with horizontal and vertical resolution of 175 and 76.8 m, respectively. GLAS is the first active satellite atmospheric profiler to provide global coverage. Data products include direct measurements of the heights of aerosol and cloud layers, and the optical depth of transmissive layers. In this poster we provide an overview of the GLAS atmospheric data products, present a simulated GLAS data set, and show results from the simulated data set using the GLAS data processing algorithm. Optical results from the ER-2 Cloud Physics Lidar (CPL), which uses many of the same processing algorithms as GLAS, show algorithm performance with real atmospheric conditions during the Southern African Regional Science Initiative (SAFARI 2000).

  16. Droplet-size distribution measurements in water clouds from double scattering with a 532-nm lidar

    NASA Astrophysics Data System (ADS)

    Maby, Celine; Lado-Bordowski, Olga

    1999-12-01

    The aim of this poster is to determine the droplet size distribution in low water clouds from measured optical parameters. Those measurements are obtained by a Lidar system. It consists of two reception telescopes: the first is near the beam send to the atmosphere, the second is at 7.7 m-distance from the first. The backscattering signal collected by the first telescope gives after an Klett's inversion, the volume extinction coefficient profile in the cloud. The double- scattering signal collected by the second telescope associated with the volumique extinction coefficient profile, gives by an inversion method, the double-scattering phase function which is correlated to a log-normal size distribution. The collected signals are detected simultaneously. A verification of the water phase is made by the depolarization ratio. Because of the situation of Lannion city, near the sea, swept by predominant winds from West, frequent fronts are present. So, a large diversity of clouds exists, which is a good experimental ground for testing and validating the theory presented here. Results from ENSSAT Lidar measurements will be presented.

  17. Cirrus cloud properties derived from coincident GOES and lidar data during the 1986 FIRE Cirrus Intensive Field Observations (IFO)

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Alvarez, Jose M.; Young, David F.; Heck, Patrick W.; Sassen, Kenneth

    1990-01-01

    One of the main difficulties in detecting cirrus clouds and determining their correct altitude using satellite measurements is their nonblackness. In the present algorithm (Rossow et al., 1985) used by the International Satellite Cloud Climatology Project (ISCCP), the cirrus cloud emissivity is estimated from the derived cloud reflectance using a theoretical model relating visible (VIS, 0.65 micron) optical depth to infrared (IR, 10.5 micron) emissivity. At this time, it is unknown how accurate this approach is or how the derived cloud altitude relates to the physical properties of the cloud. The First ISCCP Regional Experiment (FIRE) presents opportunities for determining how the observed radiances depend on the cloud properties. During the FIRE Cirrus Intensive Field Observations (IFO, see Starr, 1987), time series of cloud thickness, height, and relative optical densities were measured from several surface-based lidars. Cloud microphysics and radiances at various wavelengths were also measured simultaneously over these sites from aircraft at specific times during the IFO (October 19 to November 2, 1986). Satellite-observed radiances taken simultaneously can be matched with these data to determine their relationships to the cirrus characteristics. The first step is taken toward relating all of these variables to the satellite observations. Lidar-derived cloud heights are used to determine cloud temperatures which are used to estimate cloud emissivities from the satellite IR radiances. These results are then correlated to the observed VIS reflectances for various solar zenith angles.

  18. Ice iron/sodium film as cause for high noctilucent cloud radar reflectivity

    E-print Network

    Bellan, Paul M.

    Ice iron/sodium film as cause for high noctilucent cloud radar reflectivity P. M. Bellan1 Received that such a film exists and is caused by the deposition of iron and sodium atoms on the ice grain from iron and sodium layers located immediately above the noctilucent cloud layer. The number of conduction electrons

  19. Validation of Satellite-Based Objective Overshooting Cloud-Top Detection Methods Using CloudSat Cloud Profiling Radar Observations

    NASA Technical Reports Server (NTRS)

    Bedka, Kristopher M.; Dworak, Richard; Brunner, Jason; Feltz, Wayne

    2012-01-01

    Two satellite infrared-based overshooting convective cloud-top (OT) detection methods have recently been described in the literature: 1) the 11-mm infrared window channel texture (IRW texture) method, which uses IRW channel brightness temperature (BT) spatial gradients and thresholds, and 2) the water vapor minus IRW BT difference (WV-IRW BTD). While both methods show good performance in published case study examples, it is important to quantitatively validate these methods relative to overshooting top events across the globe. Unfortunately, no overshooting top database currently exists that could be used in such study. This study examines National Aeronautics and Space Administration CloudSat Cloud Profiling Radar data to develop an OT detection validation database that is used to evaluate the IRW-texture and WV-IRW BTD OT detection methods. CloudSat data were manually examined over a 1.5-yr period to identify cases in which the cloud top penetrates above the tropopause height defined by a numerical weather prediction model and the surrounding cirrus anvil cloud top, producing 111 confirmed overshooting top events. When applied to Moderate Resolution Imaging Spectroradiometer (MODIS)-based Geostationary Operational Environmental Satellite-R Series (GOES-R) Advanced Baseline Imager proxy data, the IRW-texture (WV-IRW BTD) method offered a 76% (96%) probability of OT detection (POD) and 16% (81%) false-alarm ratio. Case study examples show that WV-IRW BTD.0 K identifies much of the deep convective cloud top, while the IRW-texture method focuses only on regions with a spatial scale near that of commonly observed OTs. The POD decreases by 20% when IRW-texture is applied to current geostationary imager data, highlighting the importance of imager spatial resolution for observing and detecting OT regions.

  20. New Lidar Capabilities in Space: An Overview of the Cloud-Aerosol Transport System (CATS)

    NASA Astrophysics Data System (ADS)

    McGill, M. J.; Yorks, J. E.; Hlavka, D. L.; Selmer, P. A.; Hart, W. D.; Palm, S. P.; Nowottnick, E. P.; Vaughan, M.; Rodier, S. D.; Colarco, P. R.; da Silva, A.; Buchard, V.

    2014-12-01

    The Cloud-Aerosol Transport System (CATS), built at NASA Goddard Space Flight Center as a payload for the International Space Station (ISS), is set to launch in the late 2014. CATS is an elastic backscatter lidar operating in one of three science modes with three wavelengths (1064, 532, 355 nm) and HSRL capability at 532 nm. Depolarization measurements will be made at the 532 and 1064 nm wavelengths. The CATS science modes are described in Figure 1. The ISS orbit is a 51 degree inclination orbit at an altitude of about 405 km. This orbit provides more comprehensive coverage of the tropics and mid-latitudes than sun-synchronous orbiting sensors, with nearly a three day repeat cycle. Thus, science applications of CATS include cloud and aerosol climate studies, air quality monitoring, and smoke/volcanic plume tracking. Current uncertainties in cloud and aerosol properties limit our ability to accurately model the Earth's climate system and predict climate change. These limitations are due primarily to difficulties in adequately measuring aerosols and clouds on a global scale. A primary science objectives of CATS is to provide global aerosol and cloud vertical profile data in near real time to for assimilation in aerosol transport models such as the NASA GEOS-5 model. Furthermore, the vertical profiles of cloud and aerosol properties provided by CATS will complement current and future passive satellite sensors. Another important science objective of CATS is to advance technology in support of future mission development. CATS will employ 355 nm and HSRL capabilities, as well as depolarization at multiple wavelengths. These expanded measurement capabilities will provide the science community with new and improved global data products that have yet to be retrieved from space-based lidar. In preparation for launch, simulations of the CATS lidar signal are produced using GEOS5 model data to develop and test future data products. An example of the simulated CATS attenuated total backscatter for the 532 nm parallel channel is shown in Figure 2 using the GEOS-5 model forecast from 15 July 2009. This work provides an overview of the CATS mission, science objectives and simulated data.

  1. The Atmospheric Radiation Measurement Program Cloud Profiling Radars: Second-Generation Sampling Strategies, Processing, and Cloud Data Products

    SciTech Connect

    Kollias, Pavlos; Clothiaux, Eugene E.; Miller, Mark A.; Luke, Edward; Johnson, Karen L.; Moran, Kenneth P.; Widener, Kevin B.; Albrecht, Bruce A.

    2007-07-01

    The United States Department of Energy Atmospheric Radiation Measurement program operates millimeter-wavelength cloud radars in several climatologically distinct regions. The digital signal processors for these radars were recently upgraded and allow for enhancements in the operational parameters running on them. Recent evaluations of millimeter-wavelength cloud radar signal processing performance relative to the range of cloud dynamical and microphysical conditions encountered at the Atmospheric Radiation Measurement program sites have indicated that improvements are necessary, including significant improvement in temporal resolution (i.e., less than 1 s for dwell and 2 s for dwell and processing), wider Nyquist velocities, operational dealiasing of the recorded spectra, removal of pulse compression while sampling the boundary layer, and continuous recording of Doppler spectra. The new set of millimeter-wavelength cloud radar operational modes that incorporate these enhancements is presented. A significant change in radar sampling is the introduction of an uneven mode sequence with 50% of the sampling time dedicated to the lower atmosphere, allowing for detailed characterization of boundary layer clouds. The changes in the operational modes have a substantial impact on the post-processing algorithms that are used to extract cloud information from the radar data. New methods for post-processing of recorded Doppler spectra are presented that result in more accurate identification of radar clutter (e.g., insects) and extraction of turbulence and microphysical information. Results of recent studies on the error characteristics of derived Doppler moments are included so that uncertainty estimates are now included with the moments. A micro-scale data product based on the new temporal resolution of the millimeter-wavelength cloud radars is proposed that contains the number of local maxima in each Doppler spectrum, the Doppler moments of the primary peak, uncertainty estimates for the Doppler moments of the primary peak, Doppler moment shape parameters (e.g., skewness and kurtosis), and clear-air clutter flags. A macro-scale, or coarse temporal resolution, product is also proposed that includes summary statistics derived from the micro-scale product. These statistics characterize the microphysical and dynamical properties of clouds over time periods of 5 min and 60 min.

  2. An Aircraft And Radar Based Analysis Of Cloud And Precipitation Microphysics In Mid-Latitude Continental Clouds

    NASA Astrophysics Data System (ADS)

    Mishra, S.; Kumjian, M.; Bansemer, A.; Giangrande, S. E.; Ryzhkov, A.; Toto, T.

    2014-12-01

    An observational analysis of precipitation microphysics was conducted using data obtained during the Midlatitude Continental Convective Clouds Experiment (MC3E) that took place around the Atmospheric Radiation Measurement (ARM) site in Lamont, Oklahoma from April 22- June 6, 2011. MC3E was a collaborative campaign led by the National Aeronautic and Space Administration's (NASA's) Global Precipitation Measurement (GPM) mission and the U.S. Department of Energy ARM program. MC3E provided a unique opportunity to compare in-situ data from aircraft based microphysical probes with data from polarimetric radars in the radar bright band region or melting layer. One of the primary objectives of this study was to understand how riming and aggregation affect polarimetric signatures. In depth case study analysis of cloud and precipitation microphysics was performed for two specific cases, April 27th, 2011 (A27) and May 20th, 2011 (M20). Both these cases provided coincident aircraft and radar data in extensive stratiform cloud regions. Measurements from the University of North Dakota (UND) Citation aircraft and polarimetric data from the ARM CSAPR data reveal interesting details of cloud scale processes. Observations based on data from cloud probes (2DC, CIP and HVPS) along with in-situ observations of environmental variables provide remarkable details of particle growth and cloud dynamics for both case studies. For the A27 case study, UND aircraft measurements from two successive spiral profiles through the stratiform cloud region showed a transition from a riming dominated region to an aggregation dominated region. This is supported by polarimetric data from the C-Band ARM Precipitation Radar (CSAPR ). An extensive region of trailing stratiform precipitation was sampled in the M20 case study, where the aggregation, melting, and evaporation processes were measured in detail with the in-situ microphysical instruments. Latest findings from MC3E based on this combined aircraft and polarimetric radar study will be presented at the conference.

  3. Polar stratospheric clouds over Finland in the 2012/2013 Arctic winter measured by two Raman lidars

    NASA Astrophysics Data System (ADS)

    Hoffmann, Anne; Giannakaki, Eleni; Kivi, Rigel; Schrems, Otto; Immler, Franz; Komppula, Mika

    2013-04-01

    Already in December 2012, the Arctic stratospheric vortex reached temperatures sufficiently low for polar stratospheric cloud (PSC) formation over wide areas of Northern Europe and whole Finland. Within Finland, stratospheric aerosol lidar measurements have been and are performed with two Raman lidar systems, the PollyXT, owned by the Finnish Meteorological Institute (FMI) and situated well below the Arctic circle close to Kuopio (63 N, 27 E) and the MARL lidar owned by the Alfred-Wegener-Institute for Polar and Marine Research (AWI), and situated at the FMI Arctic Research Centre in Sodankylä (67 N, 26 E). The PollyXT has been designed as an autonomous tropospheric lidar system, but it has proven to be able to detect aerosol backscatter and depolarization at least as high up as 25 km. Measurements are ongoing as far as low clouds allow for stratospheric analysis with both lidars until the end of PSC season in February. For the winter 2012/2013, PSC occurrence frequency, types and characteristics will be determined. Comparative analysis with Calipso lidar profiles covering Finland will be performed. Preliminary results from December 17-24 show PSCs detected in Kuopio during seven days with the PollyXT lidar. The altitude of the clouds varied in the range of 17-25 km. In Sodankylä the measurements were running on one day during the period and PSCs were observed between altitudes 17-25 km. For the same time period (December 17-24, 2012) CALIPSO has observed stratospheric layers at all overpasses over Finland (9 tracks on five days). The clouds were observed between 18.5 and 26 km, with varying geometric and optical thickness.

  4. Multilayer cloud monitoring by micro-Joule lidar based on photon counting receiver and diode laser

    NASA Astrophysics Data System (ADS)

    Pershin, S. M.; Lyash, A. N.; Makarov, V. S.; Hamal, K.; Prochazka, I.; Sopko, B.

    2009-05-01

    Multilayers clouds layer's horizons have been detected in strong snowing condition by using the micro-Joule eye-safe lidar. Lidar is based on the 1 ?J (30 ns length) pulsed diode laser, which operates with high repetition rate (up to 10 kHz) and silica (Si) photon counting receiver (Single Photon Avalanche Diode, SPAD) from Czech Technical University. Note that the unique low avalanche voltage of Czech SPAD (~ 26-28 Volts), low power consumption (~ 0.2 Watts), the wide (-100 to 20 °C) temperature operation and low weight (~ 0.94 kg) were the main arguments to involve this lidar version into the NASA Mars Polar Lander mission a decade ago in 1999. The Geiger (photon counting) mode of SPAD operation and laser high repetition rate allow us to apply the specifically statistical approach to the development of the remote sensing return, which is scattered by aerosol and other inhomogeneous along the sounding trace. To get of reliable signal-to-noise ratio (SNR) we have to use a few hundred or thousand laser pulses because the probability of the photon scattered by sounding object is smaller than unit. As a role a Poison statistics is used to development of the remote sensing return.

  5. Introduction Mixed-phase clouds, such as those found in the Arctic

    E-print Network

    Eloranta, Edwin W.

    ) and NSA Millimeter Cloud Radar (MMCR) (left,top and bottom) show a cloud layer extending from ~600 m-1600 Amount: Total Sky Imager (Long) - Precipitation Rate: NSA 40m Tower Barrow Radiosonde Mea- surements from made using a combination of the AHSRL and NSA MMCR (see Lidar/Radar section, top). For these re

  6. Visual Cloud Histories Related to First Radar Echo Formation in Northeast Colorado Cumulus.

    NASA Astrophysics Data System (ADS)

    Knight, Charles A.; Hall, William D.; Roskowski, Philip M.

    1983-06-01

    Using quantitative analysis of time-lapse motion pictures from aircraft and a sensitive meteorological radar, the cloud top history is related to the early radar echo development in 12 vigorous, summer, convective cloud turrets in northeastern Colorado. At a threshold of about 5 dB(Z), the first echoes appear typically 5-10 min after the cloud top passes the -20°C level. The first echo either appears at cloud top or reaches the top very quickly. It sometimes appears at a well-defined height, but sometimes nearly simultaneously over an altitude range of 3 km or more. Radar echo at 5 dB(Z) typically fills the visual cloud 5-10 min after first echo. In terms of overall cloud lifetime there is plenty of time for the particles responsible for the first echo to form by the ice process. A detailed model of the rates of ice particle formation by vapor growth followed by riming gives a 5 dB(Z) radar echo within 7-10 min at concentrations as low as 1 m3, at most temperatures between 10 and 20°C and in cloud conditions realistic for northeast Colorado. The natural echo development may often result from the transport of embryonic ice particles into regions with vigorous updraft and high liquid water content where growth by accretion is rapid, rather than from growth entirely within the vigorous updrafts, for which the time may often be insufficient.

  7. The 94 GHz Cloud Radar System on a NASA ER-2 Aircraft

    NASA Technical Reports Server (NTRS)

    Li, Lihua; Heymsfield, Gerald M.; Racette, Paul E.; Tian, Lin; Zenker, Ed

    2003-01-01

    The 94-GHz (W-band) Cloud Radar System (CRS) has been developed and flown on a NASA ER-2 high-altitude (20 km) aircraft. The CRS is a fully coherent, polarimeteric Doppler radar that is capable of detecting clouds and precipitation from the surface up to the aircraft altitude in the lower stratosphere. The radar is especially well suited for cirrus cloud studies because of its high sensitivity and fine spatial resolution. This paper describes the CRS motivation, instrument design, specifications, calibration, and preliminary data &om NASA s Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE) field campaign. The unique combination of CRS with other sensors on the ER-2 provides an unprecedented opportunity to study cloud radiative effects on the global energy budget. CRS observations are being used to improve our knowledge of atmospheric scattering and attenuation characteristics at 94 GHz, and to provide datasets for algorithm implementation and validation for the upcoming NASA CloudSat mission that will use a 94-GHz spaceborne cloud radar to provide the first direct global survey of the vertical structure of cloud systems.

  8. Detecting and Updating Changes in Lidar Point Clouds for Automatic 3D Urban Cartography

    NASA Astrophysics Data System (ADS)

    Aijazi, A. K.; Checchin, P.; Trassoudaine, L.

    2013-10-01

    This work presents a method that automatically detects, analyses and then updates changes in LiDAR point clouds for accurate 3D urban cartography. In the proposed method, the 3D point cloud obtained in each passage is first classified into 2 main object classes: Permanent and Temporary. The Temporary objects are then removed from the 3D point cloud to leave behind a perforated 3D point cloud of the urban scene. These perforated 3D point clouds obtained from different passages (in the same place) at different days and times are then matched together to complete the 3D urban landscape by incremental updating. Different natural or man-made changes occurring in the urban landscape over this period of time are detected and analyzed using cognitive functions of similarity and the resulting 3D cartography is progressively modified and updated accordingly. The results, evaluated on real data using different standard evaluation metrics, not only demonstrate the efficacy of the proposed method but also shows that this method is easily applicable and well scalable, making it suitable for handling large urban scenes.

  9. Lidar Observations of the Pinatubo Stratospheric Aerosol Cloud over Frascati, Italy

    NASA Technical Reports Server (NTRS)

    Congeduti, Fernando; Adriani, Alberto; Gobbi, Gian Paolo; Centurioni, Sante

    1992-01-01

    The Pinatubo eruption of June 1991 introduced large plumes into the local stratosphere. On several occasions, volcanic gases and particles reached altitudes of about 30 km, and spread towards the west. A lidar system has been operating to monitor the evolution of the stratospheric aerosol cloud. The backscattering ratio profiles of eight different measurements were chosen to summarize the most significant occurrences of the event. Since the beginning of the winter planetary wave activity, the Pinatubo cloud integrated backscatter exceeded El Chichon's. In this context, the perturbation generated by El Chichon can only be assumed as a lower limit of the one which will follow the Pinatubo eruption. Observations of the event are still in progress.

  10. A new high spectral resolution lidar technique for direct retrievals of cloud and aerosol extinction

    NASA Astrophysics Data System (ADS)

    Yorks, J. E.; McGill, M. J.; Hlavka, D. L.

    2014-12-01

    The Airborne Cloud-Aerosol Transport System (ACATS) is a Doppler lidar system and high spectral resolution lidar (HSRL) recently developed at NASA Goddard Space Flight Center (GSFC). ACATS passes the returned atmospheric backscatter through a single etalon and divides the transmitted signal into several channels (wavelength intervals), which are measured simultaneously and independently (Figure 1). Both the particulate and molecular scattered signal can be directly and unambiguously measured, allowing for direct retrievals of particle extinction. The broad Rayleigh-scattered spectrum is imaged as a nearly flat background, illustrated in Figure 1c. The integral of the particulate backscattered spectrum is analogous to the aerosol measurement from the typical absorption filter HSRL technique in that the molecular and particulate backscatter components can be separated (Figure 1c and 1d). The main difference between HSRL systems that use the iodine filter technique and the multichannel etalon technique used in the ACATS instrument is that the latter directly measures the spectral broadening of the particulate backscatter using the etalon to filter out all backscattered light with the exception of a narrow wavelength interval (1.5 picometers for ACATS) that contains the particulate spectrum (grey, Figure 1a). This study outlines the method and retrieval algorithms for ACATS data products, focusing on the HSRL derived cloud and aerosol properties. While previous ground-based multi-channel etalon systems have been built and operated for wind retrievals, there has been no airborne demonstration of the technique and the method has not been used to derive HSRL cloud and aerosol properties. ACATS has flown on the NASA ER-2 during flights over Alaska in July 2014 and as part of the Wallops Airborne Vegetation Experiment (WAVE) in September 2012. This study will focus on the HSRL aspect of the ACATS instrument, since the method and retrieval algorithms have direct application to the Cloud-Aerosol Transport System (CATS) to be installed on the International Space Station (ISS) in late 2014. Initial ACATS HSRL results and data products, as well as comparisons to coincident Cloud Physics Lidar data will be presented.

  11. Cloud and aerosol observation planned with the space-borne lidar “ELISE” and the ATMOS-B1\\/ERM lidar

    Microsoft Academic Search

    NOBUO SUGIMOTO; Zhaoyan Liu; PETER VOELGER; YASUHIRO SASANO

    2000-01-01

    Simulation studies have been carried out for the Experimental Lidar in Space Equipment (ELISE) for the Mission Demonstration Test Satellite-2 (MDS-2), which unfortunately was canceled, and for the new spaceborne lidar for the ATMOS-B1\\/ERM program. The new lidar, which is currently studied by National Space Development Agency of Japan (NASDA) for the NASDA-ESA joint Earth radiation mission (ATMOS-B1\\/ERM), is a

  12. Monitoring cirrus clouds with lidar in the Southern Hemisphere: A local study over Buenos Aires. 1. Tropopause heights

    NASA Astrophysics Data System (ADS)

    Lakkis, Susan Gabriela; Lavorato, Mario; Canziani, Pablo Osvaldo

    2009-03-01

    Cirrus clouds in the upper troposphere and the lower stratosphere have recently drawn much attention due to their important role and impact on the atmospheric radiative balance. Because they are located in the upper troposphere their study requires a high resolution technique not only to detect them but also to characterize their behaviour and evolution. A good dynamic range in lidar backscattering signals is necessary to observe and improve our knowledge of cirrus clouds, and thereof, atmospheric parameters in the troposphere and UT/LS due to their vicinity to the tropopause layer. The lidar system measures, in real time, the evolution of the atmospheric boundary layer, stratospheric aerosols, tropopause height and cirrus clouds evolution. The aim of the work is to present the main properties of cirrus clouds over central Argentina and to monitor tropopause height together with their temporal evolution using a backscatter lidar system located in Buenos Aires (34.6 °S, 58.5 °W). A cirrus clouds detection method was used to analyze a set of 60 diurnal events, during 2001-2005, in order to estimate tropopause height and its temporal evolution, using the top of cirrus clouds present on the upper troposphere as a tropopause tracer. The results derived from lidar show a remarkable good agreement when compared with rawinsonde data, considering values of tropopause height with differences less than or equal to 500 m, depending on the signal to noise ratio of the measurements. Clouds properties analysis reveals the presence of thick cirrus clouds with thickness between 0.5 and 4.2 km, with the top cloud located at the tropopause height.

  13. Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles: II. A Study of Three Radars with Different Sensitivity

    NASA Astrophysics Data System (ADS)

    Janches, D.; Swarnalingam, N.; Plane, J. M. C.; Nesvorný, D.; Feng, W.; Vokrouhlický, D.; Nicolls, M. J.

    2015-07-01

    The sensitivity of radar systems to detect different velocity populations of the incoming micrometeoroid flux is often the first argument considered to explain disagreements between models of the Near-Earth dust environment and observations. Recently, this was argued by Nesvorný et al. to support the main conclusions of a Zodiacal Dust Cloud (ZDC) model which predicts a flux of meteoric material into the Earth’s upper atmosphere mostly composed of small and very slow particles. In this paper, we expand on a new methodology developed by Janches et al. to test the ability of powerful radars to detect the meteoroid populations in question. In our previous work, we focused on Arecibo 430 MHz observations since it is the most sensitive radar that has been used for this type of observation to date. In this paper, we apply our methodology to two other systems, the 440 MHz Poker Flat Incoherent Scatter Radar and the 46.5 Middle and Upper Atmosphere radar. We show that even with the less sensitive radars, the current ZDC model over-predicts radar observations. We discuss our results in light of new measurements by the Planck satellite which suggest that the ZDC particle population may be characterized by smaller sizes than previously believed. We conclude that the solution to finding agreement between the ZDC model and sensitive high power and large aperture meteor observations must be a combination of a re-examination not only of our knowledge of radar detection biases, but also the physical assumptions of the ZDC model itself.

  14. A comparison of observations in the tropical western Pacific from ground-based and satellite millimeter-wavelength cloud radars

    Microsoft Academic Search

    Zheng Liu; Roger Marchand; Thomas Ackerman

    2010-01-01

    Millimeter-wavelength cloud radar (MMCR) can provide information on the vertical structure of cloud fields and thereby improve our understanding of the spatial distribution of clouds and their role in the climate system. Here we consider the representativeness of ground-based vertically pointing MMCR observations, which have been used in numerous climate studies. MMCR cloud statistics collected at Darwin, Australia, are compared

  15. Evaluation of gridded scanning ARM cloud radar reflectivity observations and vertical doppler velocity retrievals

    NASA Astrophysics Data System (ADS)

    Lamer, K.; Tatarevic, A.; Jo, I.; Kollias, P.

    2014-04-01

    The scanning Atmospheric Radiation Measurement (ARM) cloud radars (SACRs) provide continuous atmospheric observations aspiring to capture the 3-D cloud-scale structure. Sampling clouds in 3-D is challenging due to their temporal-spatial scales, the need to sample the sky at high elevations and cloud radar limitations. Thus, a suggested scan strategy is to repetitively slice the atmosphere from horizon to horizon as clouds advect over the radar (Cross-Wind Range-Height Indicator - CW-RHI). Here, the processing and gridding of the SACR CW-RHI scans are presented. First, the SACR sample observations from the ARM Southern Great Plains and Cape Cod sites are post-processed (detection mask, gaseous attenuation correction, insect filtering and velocity de-aliasing). The resulting radial Doppler moment fields are then mapped to Cartesian coordinates with time as one of the dimensions. Next the Cartesian-gridded Doppler velocity fields are decomposed into the horizontal wind velocity contribution and the vertical Doppler velocity component. For validation purposes, all gridded and retrieved fields are compared to collocated zenith-pointing ARM cloud radar measurements. We consider that the SACR sensitivity loss with range, the cloud type observed and the research purpose should be considered in determining the gridded domain size. Our results also demonstrate that the gridded SACR observations resolve the main features of low and high stratiform clouds. It is established that the CW-RHI observations complemented with processing techniques could lead to robust 3-D cloud dynamical representations up to 25-30 degrees off zenith. The proposed gridded products are expected to advance our understanding of 3-D cloud morphology, dynamics and anisotropy and lead to more realistic 3-D radiative transfer calculations.

  16. Radiative effects of African dust and smoke observed from Clouds and the Earth's Radiant Energy System (CERES) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data

    NASA Astrophysics Data System (ADS)

    Yorks, John E.; McGill, Matt; Rodier, Sharon; Vaughan, Mark; Hu, Yongxiang; Hlavka, Dennis

    2009-09-01

    Cloud and aerosol effects have a significant impact on the atmospheric radiation budget in the tropical Atlantic because of the spatial and temporal extent of desert dust and smoke from biomass burning in the atmosphere. The influences of African dust and smoke aerosols on cloud radiative properties over the tropical Atlantic Ocean were analyzed for the month of July for 3 years (2006-2008) using colocated data collected by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Aqua satellites. Aerosol layer height and type can be accurately determined using CALIOP data through directly measured parameters such as optical depth, volume depolarization ratio, attenuated backscatter, and color ratio. On average, clouds below 5 km had a daytime instantaneous shortwave (SW) radiative flux of 270.2 ± 16.9 W/m2 and thin cirrus clouds had a SW radiative flux of 208.0 ± 12.7 W/m2. When dust aerosols interacted with clouds below 5 km, as determined from CALIPSO, the SW radiative flux decreased to 205.4 ± 13.0 W/m2. Similarly, smoke aerosols decreased the SW radiative flux of low clouds to a value of 240.0 ± 16.6 W/m2. These decreases in SW radiative flux were likely attributed to the aerosol layer height and changes in cloud microphysics. CALIOP lidar observations, which more accurately identify aerosol layer height than passive instruments, appear essential for better understanding of cloud-aerosol interactions, a major uncertainty in predicting the climate system.

  17. Polar stratospheric clouds and volcanic aerosol during spring 1992 over McMurdo Station, Antarctica: Lidar and particle counter comparisons

    Microsoft Academic Search

    A. Adriani; T. Deshler; G. Di Donfrancesco; G. P. Gobbi

    1995-01-01

    Coordinated observations with lidar and balloon-borne particle counters were used to characterize polar stratospheric clouds and to estimate a particle index of refraction. The index of refraction was estimated from comparisons of calculated and measured scattering ratios at a wavelength of 532 nm. The clouds, measured from McMurdo Station, Antarctica (78°S), were observed above 11 km at temperatures below 198

  18. A 94 GHz RF Electronics Subsystem for the CloudSat Cloud Profiling Radar

    NASA Technical Reports Server (NTRS)

    LaBelle, Remi C.; Girard, Ralph; Arbery, Graham

    2003-01-01

    The CloudSat spacecraft, scheduled for launch in 2004, will carry the 94 GHz Cloud Profiling Radar (CPR) instrument. The design, assembly and test of the flight Radio Frequency Electronics Subsystem (RFES) for this instrument has been completed and is presented here. The RFES consists of an Upconverter (which includes an Exciter and two Drive Amplifiers (DA's)), a Receiver, and a Transmitter Calibrator assembly. Some key performance parameters of the RFES are as follows: dual 100 mW pulse-modulated drive outputs at 94 GHz, overall Receiver noise figure < 5.0 dB, a highly stable W-band noise source to provide knowledge accuracy of Receiver gain of < 0.4 dB over the 2 year mission life, and a W-band peak power detector to monitor the transmitter output power to within 0.5 dB over life. Some recent monolithic microwave integrated circuit (MMIC) designs were utilized which implement the DA's in 0.1 micron GaAs high electron-mobility transistor (HEMT) technology and the Receiver low-noise amplifier (LNA) in 0.1 micron InP HEMT technology.

  19. Comparison of lightning location data and polarisation radar observations of clouds

    NASA Technical Reports Server (NTRS)

    Illingworth, A. J.; Lees, M. I.

    1991-01-01

    Simultaneous observations of both the precipitation and the lightning associated with thunderstorms show that the lightning is within 3 km of the maximum precipitation echo. The intensity and type of the precipitation is observed with 500 m spatial accuracy using an S-band polarization radar and the position of the lightning is inferred from a low frequency magnetic direction finding location system. Empirical adjustment to the angles using the redundancy of the lightning data reduce this error. Radar echoes above 45dBZ may be caused by soft hail or hailstones, but similarly intense echoes may result from melting snow. The data show that a new polarization radar parameter, the linear depolarization ratio, can distinguish between soft hail and melting snow, and that the intense radar echoes associated with melting snow pose no threat of lightning. A lightning risk only exists when the radar indicates that the clouds contain soft hail or hailstones.

  20. An algorithm for generating stochastic cloud fields from radar profile statistics

    NASA Astrophysics Data System (ADS)

    Franklin Evans, K.; Wiscombe, Warren J.

    2004-11-01

    An algorithm is described for generating stochastic three-dimensional (3D) cloud fields from time-height fields derived from vertically pointing radar. This model is designed to generate cloud fields that match the statistics of the input fields as closely as possible. The major assumptions of the algorithm are that the statistics of the fields are translationally invariant in the horizontal and independent of horizontal direction; however, the statistics do depend on height. The algorithm outputs 2D or 3D stochastic fields of liquid water content (LWC) and (optionally) effective radius. The algorithm is a generalization of the Fourier filtering methods often used for stochastic cloud models. The Fourier filtering procedure generates Gaussian stochastic fields from a "Gaussian" cross-correlation matrix, which is a function of a pair of heights and the horizontal distance (or "lag"). The Gaussian fields are nonlinearly transformed to give the correct LWC histogram for each height. The "Gaussian" cross-correlation matrix is specially chosen so that, after the nonlinear transformation, the cross-correlation matrix of the cloud mask fields approximately matches that derived from the input LWC fields. The cloud mask correlation function is chosen because the clear/cloud boundaries are thought to be important for 3D radiative transfer effects in cumulus. The stochastic cloud generation algorithm is tested with 3 months of boundary layer cumulus cloud data from an 8.6-mm wavelength radar on the island of Nauru. Winds from a 915-MHz wind profiler are used to convert the radar fields from time to horizontal distance. Tests are performed comparing the statistics of 744 radar-derived input fields to the statistics of 100 2D and 3D stochastic output fields. The single-point statistics as a function of height agree nearly perfectly. The input and stochastic cloud mask cross-correlation matrices agree fairly well. The cloud fractions agree to within 0.005 (the total cloud fraction is 18%). The cumulative distributions of optical depth, cloud thickness, cloud width, and intercloud gap length agree reasonably well. In the future, this stochastic cloud field generation algorithm will be used to study domain-averaged 3D radiative transfer effects in cumulus clouds.

  1. Retrieval of vertical profiles of stratus cloud properties from combined oxygen a-band and radar observations

    NASA Astrophysics Data System (ADS)

    Li, S.; Min, Q.

    2011-12-01

    Detailed knowledge of the radiative properties of clouds is crucial to properly characterize climate forcing mechanisms and quantify the response of the climate system. To derive properties of clouds from the cloud radar reflectivity, which is a function of the 6th moment of the particle size distribution, requires making assumptions about the cloud microphysics. The passive oxygen A-band measurements, however, are sensitive to the 2nd moment of the particle size distribution and can be used to constrain radar retrievals. Combination of active cloud radar and passive oxygen A-band measurements is able to accurately derive cloud vertical properties. We have developed such a retrieval algorithm, in which a set of consistent cloud vertical properties, i.e., cloud effective radius and cloud water content profiles, is obtained by closures in both radar reflectivity and oxygen A-band spectrum. The synergetic retrieval algorithm has applied to the measurements of Millimeter Cloud Radar (MMCR) and Rotating Shadowband Spectrometer (RSS) at the ARM SGP site. Our case study demonstrates that both retrieved cloud effective radius and cloud water content agree well with other independent measurements.

  2. The evolution of radar echo in a seeded cloud

    Microsoft Academic Search

    Marianne English; John D. Marwitz

    1982-01-01

    A convective cloud extending above a stratocumulus deck was seeded with droppable AgI flares at about the — 7°C level. Ten minutes after seeding, an echo was observed front the cloud at about the seeding level and downwind from the seeding location. The echo was very elongated and oriented parallel to the seeding track. Since the cloud was located only

  3. Constructing a Merged Cloud-Precipitation Radar Dataset for Tropical Convective Clouds during the DYNAMO/AMIE Experiment at Addu Atoll

    SciTech Connect

    Feng, Zhe; McFarlane, Sally A.; Schumacher, Courtney; Ellis, Scott; Comstock, Jennifer M.; Bharadwaj, Nitin

    2014-05-16

    To improve understanding of the convective processes key to the Madden-Julian-Oscillation (MJO) initiation, the Dynamics of the MJO (DYNAMO) and Atmospheric Radiation Measurement MJO Investigation Experiment (AMIE) collected four months of observations from three radars, the S-band Polarization Radar (S-Pol), the C-band Shared Mobile Atmospheric Research & Teaching Radar (SMART-R), and Ka-band Zenith Radar (KAZR) on Addu Atoll in the tropical Indian Ocean. This study compares the measurements from the S-Pol and SMART-R to those from the more sensitive KAZR in order to characterize the hydrometeor detection capabilities of the two scanning precipitation radars. Frequency comparisons for precipitating convective clouds and non-precipitating high clouds agree much better than non-precipitating low clouds for both scanning radars due to issues in ground clutter. On average, SMART-R underestimates convective and high cloud tops by 0.3 to 1.1 km, while S-Pol underestimates cloud tops by less than 0.4 km for these cloud types. S-Pol shows excellent dynamic range in detecting various types of clouds and therefore its data are well suited for characterizing the evolution of the 3D cloud structures, complementing the profiling KAZR measurements. For detecting non-precipitating low clouds and thin cirrus clouds, KAZR remains the most reliable instrument. However, KAZR is attenuated in heavy precipitation and underestimates cloud top height due to rainfall attenuation 4.3% of the time during DYNAMO/AMIE. An empirical method to correct the KAZR cloud top heights is described, and a merged radar dataset is produced to provide improved cloud boundary estimates, microphysics and radiative heating retrievals.

  4. Polar stratospheric clouds over McMurdo, Antarctica, during the 1991 spring: Lidar and particle counter measurements

    SciTech Connect

    Adriani, A.; Gobbi, G.P. (Instituto di Fisica dell'Atmosfera, Frascati (Italy)); Deshler, T.; Johnson, B.J. (Univ. of Wyoming, Laramie, WY (United States)); Donfrancesco, G.Di. (ENEA, Rome (Italy))

    1992-09-04

    Lidar and balloonborne particle counter measurements were performed simultaneously on two days when polar stratospheric clouds were observed in late August 1991 at McMurdo, Antarctica. Both nitric acid trihydrate and ice clouds were observed in the lower stratosphere between 10 and 23 km in different formation stages and with different cooling rate; however in all cases the size distributions were bimodal. Comparison of scattering ratios measured by lidar and calculated from particle size distributions are in good agreement; however, discrepancies were observed when the lower stratosphere was highly perturbed by wave activity. Lee waves generated by air flowing over the Trans Antarctic Mountains induced ice cloud formation at altitudes as high as 20 km. No PSCs were observed after the end of August in 1991.

  5. Buildings classification from airborne LiDAR point clouds through OBIA and ontology driven approach

    NASA Astrophysics Data System (ADS)

    Tomljenovic, Ivan; Belgiu, Mariana; Lampoltshammer, Thomas J.

    2013-04-01

    In the last years, airborne Light Detection and Ranging (LiDAR) data proved to be a valuable information resource for a vast number of applications ranging from land cover mapping to individual surface feature extraction from complex urban environments. To extract information from LiDAR data, users apply prior knowledge. Unfortunately, there is no consistent initiative for structuring this knowledge into data models that can be shared and reused across different applications and domains. The absence of such models poses great challenges to data interpretation, data fusion and integration as well as information transferability. The intention of this work is to describe the design, development and deployment of an ontology-based system to classify buildings from airborne LiDAR data. The novelty of this approach consists of the development of a domain ontology that specifies explicitly the knowledge used to extract features from airborne LiDAR data. The overall goal of this approach is to investigate the possibility for classification of features of interest from LiDAR data by means of domain ontology. The proposed workflow is applied to the building extraction process for the region of "Biberach an der Riss" in South Germany. Strip-adjusted and georeferenced airborne LiDAR data is processed based on geometrical and radiometric signatures stored within the point cloud. Region-growing segmentation algorithms are applied and segmented regions are exported to the GeoJSON format. Subsequently, the data is imported into the ontology-based reasoning process used to automatically classify exported features of interest. Based on the ontology it becomes possible to define domain concepts, associated properties and relations. As a consequence, the resulting specific body of knowledge restricts possible interpretation variants. Moreover, ontologies are machinable and thus it is possible to run reasoning on top of them. Available reasoners (FACT++, JESS, Pellet) are used to check the consistency of the developed ontologies, and logical reasoning is performed to infer implicit relations between defined concepts. The ontology for the definition of building is specified using the Ontology Web Language (OWL). It is the most widely used ontology language that is based on Description Logics (DL). DL allows the description of internal properties of modelled concepts (roof typology, shape, area, height etc.) and relationships between objects (IS_A, MEMBER_OF/INSTANCE_OF). It captures terminological knowledge (TBox) as well as assertional knowledge (ABox) - that represents facts about concept instances, i.e. the buildings in airborne LiDAR data. To assess the classification accuracy, ground truth data generated by visual interpretation and calculated classification results in terms of precision and recall are used. The advantages of this approach are: (i) flexibility, (ii) transferability, and (iii) extendibility - i.e. ontology can be extended with further concepts, data properties and object properties.

  6. An algorithm for generating stochastic cloud fields from radar profile statistics

    Microsoft Academic Search

    K. Franklin Evans; Warren J. Wiscombe

    An algorithm is described for generating stochastic three-dimensional (3D) cloud fields from time-height fields derived from vertically pointing radar. This model is designed to generate cloud fields that match the statistics of the input fields as closely as possible. The major assumptions of the algorithm are that the statistics of the fields are translationally invariant in the horizontal and independent

  7. Characterization of Polar Stratospheric Clouds With Spaceborne Lidar: CALIPSO and the 2006 Antarctic Season

    NASA Technical Reports Server (NTRS)

    Pitts, Michael C.; Thomason, L. W.; Poole, Lamont R.; Winker, David M.

    2007-01-01

    The role of polar stratospheric clouds in polar ozone loss has been well documented. The CALIPSO satellite mission offers a new opportunity to characterize PSCs on spatial and temporal scales previously unavailable. A PSC detection algorithm based on a single wavelength threshold approach has been developed for CALIPSO. The method appears to accurately detect PSCs of all opacities, including tenuous clouds, with a very low rate of false positives and few missed clouds. We applied the algorithm to CALIPSO data acquired during the 2006 Antarctic winter season from 13 June through 31 October. The spatial and temporal distribution of CALIPSO PSC observations is illustrated with weekly maps of PSC occurrence. The evolution of the 2006 PSC season is depicted by time series of daily PSC frequency as a function of altitude. Comparisons with virtual solar occultation data indicate that CALIPSO provides a different view of the PSC season than attained with previous solar occultation satellites. Measurement-based time series of PSC areal coverage and vertically-integrated PSC volume are computed from the CALIPSO data. The observed area covered with PSCs is significantly smaller than would be inferred from a temperature-based proxy such as TNAT but is similar in magnitude to that inferred from TSTS. The potential of CALIPSO measurements for investigating PSC microphysics is illustrated using combinations of lidar backscatter coefficient and volume depolarization to infer composition for two CALIPSO PSC scenes.

  8. Filtering of LIDAR Point Cloud Using a Strip Based Algorithm in Residential Mountainous Areas

    NASA Astrophysics Data System (ADS)

    Hosseini, S. A.; Arefi, H.; Gharib, Z.

    2014-10-01

    Several algorithms have been developed to automatically detect the bare earth in LIDAR point clouds referred to as filtering. Previous experimental study on filtering algorithms determined that in flat and uncomplicated landscapes, algorithms tend to do well. Significant differences in accuracies of filtering appear in landscapes containing steep slopes and discontinuities. A solution for this problem is the segmentation of ALS point clouds. In this paper a new segmentation has been developed. The algorithm starts with first slicing a point cloud into contiguous and parallel profiles in different directions. Then the points in each profile are segmented into polylines based on distance and elevation proximity. The segmentation in each profile yields polylines. The polylines are then linked together through their common points to obtain surface segments. At the final stage, the data is partitioned into some windows in which the strips are exploited to analysis the points with regard to the height differences through them. In this case the whole data could be fully segmented into ground and non-ground measurements, sequentially via the strips which make the algorithm fast to implement.

  9. Gravity waves and mesospheric clouds in the summer middle atmosphere: A comparison of lidar measurements and ray modeling of gravity waves over Sondrestrom, Greenland

    Microsoft Academic Search

    Andrew J. Gerrard; Timothy J. Kane; Stephen D. Eckermann; Jeffrey P. Thayer

    2004-01-01

    (1) We conducted gravity wave ray-tracing experiments within an atmospheric region centered near the ARCLITE lidar system at Sondrestrom, Greenland (67? N, 310? E), in efforts to understand lidar observations of both upper stratospheric gravity wave activity and mesospheric clouds during August 1996 and the summer of 2001. The ray model was used to trace gravity waves through realistic three-dimensional

  10. Lidar observations of polar stratospheric clouds at McMurdo, Antarctica, during NOZE-2

    NASA Technical Reports Server (NTRS)

    Morley, Bruce M.

    1988-01-01

    SRI International operated a dual wavelength (1.064 micrometer and .532 micrometer) aerosol lidar at McMurdo Station, Antarctica, as part of the National Ozone Expedition-2 (NOZE-2). The objective of the project was to map the vertical distributions of polar stratospheric clouds (PSCs), which are believed to play an important role in the destruction of ozone in the Antarctic spring. Altitude, thickness, homogeneity, and duration of PSC events as well as information on particle shape, size or number density will be very useful in determining the exact role of PSCs in ozone destructions, and when combined with measurements of other investigators, additional properties of PSCs can be estimated. The results are currently being analyzed in terms of PSC properties which are useful for modeling the stratospheric ozone depletion mechanism.

  11. Scale Dependence of Variability in Stratiform Clouds Based on Millimeter Wave Could Radar

    SciTech Connect

    Kogan, Z.N.; Kogan, Y.L.; Mechem, D.B.

    2005-03-18

    Internal variability of stratiform clouds is manifested on grid scales ranging from cloud resolving models to general circulation models, and its accurate formulation is one of the most important tasks in improvement of model predictions. Understanding cloud variability on different scales will help to develop and improve subgrid-scale cloud parameterizations. Information about variability is also crucial when dealing with retrieval of microphysical information from observations of volume averaged reflectivity parameters, since neglecting variability can lead to substantial biases in estimation of retrieved microphysical variables. The Atmospheric Radiation Measurement Program (ARM) operates millimeter wave cloud radar (MMCR) at the ARM Climate Research Facility over the Southern Great Plains (ACRF SGP) that provides a unique opportunity to obtain continuous observations in order to address issues of cloud variability. These data contain information on spatial and/or temporal short- and long-range correlations in cloudiness, enabling scale-by-scale (scaling) analyses over a range of hundreds of meters to hundreds of kilometers. The objective of this study is to conduct an analysis based on radar reflectivity observations of clouds over the ACRF SGP site with special emphasis on boundary layer clouds, and the effect of drizzle.

  12. Cloud-base distribution and cirrus properties based on micropulse lidar measurements at a site in southeastern China

    NASA Astrophysics Data System (ADS)

    Liu, Jianjun; Li, Zhanqing; Zheng, Youfei; Cribb, Maureen

    2015-07-01

    The cloud fraction (CF) and cloud-base heights (CBHs), and cirrus properties, over a site in southeastern China from June 2008 to May 2009, are examined by a ground-based lidar. Results show that clouds occupied the sky 41% of the time. Significant seasonal variations in CF were found with a maximum/minimum during winter/summer and similar magnitudes of CF in spring and autumn. A distinct diurnal cycle in the overall mean CF was seen. Total, daytime, and nighttime annual mean CBHs were 3.05±2.73 km, 2.46±2.08 km, and 3.51±3.07 km, respectively. The lowest/highest CBH occurred around noon/midnight. Cirrus clouds were present ˜36.2% of the time at night with the percentage increased in summer and decreased in spring. Annual mean values for cirrus geometrical properties were 8.89±1.65 km, 9.80±1.70 km, 10.73±1.86 km and 1.83±0.91 km for the base, mid-cloud, top height, and the thickness, respectively. Seasonal variations in cirrus geometrical properties show a maximum/minimum in summer/winter for all cirrus geometrical parameters. The mean cirrus lidar ratio for all cirrus cases in our study was ˜ 25±17 sr, with a smooth seasonal trend. The cirrus optical depth ranged from 0.001 to 2.475, with a mean of 0.34±0.33. Sub-visual, thin, and dense cirrus were observed in ˜12%, 43%, and 45% of the cases, respectively. More frequent, thicker cirrus clouds occurred in summer than in any other season. The properties of cirrus cloud over the site are compared with other lidar-based retrievals of midlatitude cirrus cloud properties.

  13. Analysis and Calibration of CRF Raman Lidar Cloud Liquid Water Measurements

    SciTech Connect

    Turner, D.D.

    2007-10-31

    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 o

  14. Optimal form and frequency of presentation of radar data on clouds and phenomena connected with them

    NASA Technical Reports Server (NTRS)

    Salman, Y. M.; Divinskaya, B. S.

    1975-01-01

    The available data on the space and time structure of the radio echoes from different clouds is examined. On the basis of their analysis, a basis is given for the optimal form of presentation and the operational quality of renewal of radar information used for operational purposes in ZGMO and the TGMTs.

  15. Using multiparameter radars to estimate the attenuation and water content of clouds

    SciTech Connect

    Jameson, A.R. [Applied Research Corporation, Landover, MD (United States)] [Applied Research Corporation, Landover, MD (United States)

    1995-09-01

    The attenuation of microwaves is caused not only by precipitation but also by clouds. Consequently, the presence of liquid cloud can affect estimates of rainfall rate computed from attenuation and reflectivity factors measured at higher frequencies typically used for spaceborne and airborne radars. Cloud attenuation also affects ground-based radar measurements of rainfall at frequencies as low as 5 GHz. This paper suggests an approach for determining the attenuation due to cloud (A{sub c}) and for estimating the cloud water content (W{sub c}) even in moderate rain by using radars operating at two frequencies with one of them capable of dual-linear (horizontal-vertical) polarization measurements. This analysis suggests that useful {open_quotes}instantaneous{close_quotes} estimates of A{sub c} and W{sub c} should be possible when an upper frequency of 13.8 GHz is used in conjunction with a lower frequency. These measurements could also be used to derive cloud attenuation statistics, potentially useful for developing techniques to help compensate for the effect of cloud attenuation on spaceborne, airborne, and ground-based radar estimates of rainfall. While this algorithm appears promising, it is particularly challenging to devise approaches to test this technique, not only because the necessary instruments do not yet exist but also because of a lack of a standard for comparison. Although a complete test appears out of reach at this time, it should be possible at least to explore the validity of certain aspects of the technology. One possible approach using measurements over extended volumes is discussed at the end of this paper. 19 refs., 11 figs., 2 tabs.

  16. Coupling high resolution 3D point clouds from terrestrial LiDAR with high precision displacement time series from GB-InSAR to understand landslide kinematic: example of the La Perraire instability, Swiss Alps.

    NASA Astrophysics Data System (ADS)

    Michoud, Clément; Baillifard, François; Harald Blikra, Lars; Derron, Marc-Henri; Jaboyedoff, Michel; Kristensen, Lene; Leva, Davide; Metzger, Richard; Rivolta, Carlo

    2014-05-01

    Terrestrial Laser Scanning and Ground-Based Radar Interferometry have changed our perception and interpretation of slope activities for the last 20 years and are now routinely used for monitoring and even early warning purposes. Terrestrial LiDAR allows indeed to model topography with very high point density, even in steep slopes, and to extract 3D displacements of rock masses by comparing successive datasets. GB-InSAR techniques are able to detect mm displacements over large areas. Nevertheless, both techniques suffer of some limitations. The precision of LiDAR devices actually limits its ability to monitor very slow-moving landslides, as well as by the dam resolution and the particular geometry (in azimuth/range) of GB-InSAR data may complicate their interpretations. To overcome those limitations, tools were produced to truly combine strong advantages of both techniques, by coupling high resolution geometrical data from terrestrial LiDAR or photogrammetry with high precision displacement time series from GB-InSAR. We thus developed a new exportation module into the processing chain of LiSAmobile (GB-InSAR) devices in order to wrap radar results from their particular geometry on high resolution 3D point clouds with cm mean point spacing. Furthermore, we also added new importation and visualization functionalities into Coltop3D (software for geological interpretations of laser scanning data) to display those results in 3D and even analyzing displacement time series. This new method has also been optimized to create as few and small files as possible and for time processing. Advantages of coupling terrestrial LiDAR and GB-InSAR data will be illustrated on the La Perraire instability, an active large rockslide involving frequent rockfalls and threatening inhabitant within the Val de Bagnes in the Swiss Alps. This rock mass, monitored by LiDAR and GPS since 2006, is huge enough and long-term movements are big (up to 1.6 m in 6 years) and complex enough to make difficult point cloud comparisons and LiDAR interpretations. Two monitoring campaigns with GB-InSAR devices were later performed and caught mm daily displacements (up to 8 mm in 15 days in September 2011). By coupling both datasets, we were able to clearly identify back scarps, as well as the most active masses within the whole instability, and thus to map limits of the instability and stable parts of the slope. Here the integration and the coupling of ground-based monitoring techniques were necessary to understand the whole landslide kinematic.

  17. Comparison between active sensor and radiosonde cloud boundaries over the ARM Southern Great Plains site

    E-print Network

    accurate observations of both global cloud amount and the vertical distributions of clouds. Satellite from satellite has yet to be demonstrated. To validate satellite-derived cloud bounda- ries, ground, such as radars, laser ceilometers, and lidars, for this purpose has been extensively demonstrated [e.g., Mace et

  18. High Resolution Radar Detection of Individual Raindrops in Natural Cloud Systems

    NASA Astrophysics Data System (ADS)

    Schmidt, J.; Flatau, P. J.; Harasti, P. R.; Yates, R. D.

    2014-12-01

    A high resolution C-band Doppler radar previously used to detect debris shed during space shuttle missions is shown to have the capability to determine the properties of individual raindrops in the free atmosphere. This is accomplished through a combination of the radar's narrow (0.22 degree) beamwidth, a range resolution as fine as 0.5m, and extremely high 3MW power. These attributes lead to exceptionally small radar pulse volumes (as low as 14m3 at the radar's minimum 2km range) and allow the radar to detect individual drops that exceed 0.5mm in diameter. As the radar transmits both a higher (0.5m) and lower (37m) range resolution waveform every other pulse, a unique opportunity arise to examine both the bulk radar reflectivity and individual particle properties at the same time. The larger individual drops detected by the radar appear in the radar data as bright, nearly linear, reflectivity "streaks" against the more uniform background reflectivity field generated by the population of smaller drops. These streaks can then be examined to infer the properties of the particles directly such as their size, fall velocity, concentration, and potentially other properties such as naturally occurring drop oscillations. Examples of the bulk and individual particle properties for several "streaks" associated with a deep convective system are examined. Additional high-resolution studies of the circulation fields associated with a shallow altocumulus layer and a long-lived radar reflectivity bright band associated with the melting layer within a meso-convective cloud system reveal new details of the internal circulation features associated with these phenomena.

  19. Quantifying monthly to decadal subsidence and assessing collapse potential near the Wink sinkholes, west Texas, using airborne lidar, radar interferometry, and microgravity

    NASA Astrophysics Data System (ADS)

    Paine, J. G.; Collins, E.; Yang, D.; Andrews, J. R.; Averett, A.; Caudle, T.; Saylam, K.

    2014-12-01

    We are using airborne lidar and satellite-based radar interferometry (InSAR) to quantify short-term (months to years) and longer-term (decades) subsidence in the area surrounding two large (100- to 200-m diameter) sinkholes that formed above Permian bedded salt in 1980 and 2002 in the Wink area, west Texas. Radar interferograms constructed from synthetic aperture radar data acquired between 2008 and 2011 with the ALOS PALSAR L-band satellite-borne instrument reveal local areas that are subsiding at rates that reach a few cm per month. Subsiding areas identified on radar interferograms enable labor-intensive ground investigations (such as microgravity surveys) to focus on areas where subsidence is occurring and shallow-source mass deficits might exist that could be sites of future subsidence or collapse. Longer-term elevation changes are being quantified by comparing digital elevation models (DEMs) constructed from high-resolution airborne lidar data acquired over a 32-km2 area in 2013 with older, lower-resolution DEMs constructed from data acquired during the NASA- and NGA-sponsored Shuttle Radar Topographic Mission in February 2000 and from USGS aerial photogrammetry-derived topographic data from the 1960s. Total subsidence reaches more than 10 m over 45 years in some areas. Maximum rates of subsidence measured on annual (from InSAR) and decadal (from lidar) time scales are about 0.25 m/yr. In addition to showing the extent and magnitude of subsidence at the 1980 and 2002 sinkholes, comparison of the 2013 lidar-derived DEM with the 1960s photogrammetry-derived DEM revealed other locations that have undergone significant (more than 1 m) elevation change since the 1960s, but show no evidence of recent (2008 to 2011) ground motion from satellite radar interferograms. Regional coverage obtained by radar interferometry and local coverage obtained with airborne lidar show that areas of measurable subsidence are all within a few km of the 1980 and 2002 sinkholes.

  20. On the air motion in continental shallow cumulus clouds: large-eddy simulation versus radar observation

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Chandra, A.; Klein, S. A.

    2013-12-01

    Summertime observations for 13 years at Atmospheric Radiation Measurement Southern Great Plains (SGP) site are used to study air motion in non-precipitating fair-weather shallow cumulus clouds. A composite shallow cumulus case is constructed based on an ensemble of days with observed active shallow cumulus clouds. Large-scale forcing for this composite case is derived accordingly based on observation-constrained variational analysis and is used to drive the large-eddy simulation (LES), whose set-up is most suitable to make an apple-to-apple comparison with radar observation at the site. At the same time, a novel retrieval algorithm, which can remove the insects' contamination on radar reflectivity, is applied to millimeter cloud radar 10s observations to get vertical velocity of air motion in the shallow cumulus cloud ensembles. We then focus on the behavior of cloudy profiles with liquid water path greater than 80 g/m^2. This is done because we believe this portion of cloud makes a major contribution to the total mass flux and by so doing, the uncertainty is minimized in the comparison between observation and LES results. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-641597

  1. An Improved Method for Detectingand Separating Cloud from Drizzle Radar Signatures Using a Time Domain Parametric Technique

    NASA Astrophysics Data System (ADS)

    Nguyen, C.; Chandra, C. V.

    2014-12-01

    The separation of radar signatures depicting cloud and drizzle within a pulse radar volume is a fundamental problem whose solution is required to decouple the microphysical and dynamical processes introduced by turbulence. Such a solution would lead to the development of new meteorological products.In this presentation, a method to detect, separate and estimate multiple radar echoes from cloud and drizzle obtained from vertically pointing cloud Doppler spectra is described. In the case when only clouds are present, the Doppler spectrum is symmetrical and is well approximated by a Gaussian. To extract cloud echoes, a parametric maximum likelihood estimator in the time domain is employed using the recorded radar Doppler spectra data. To detect skewness in the radar spectrum, goodness of fit parameters are defined. It is shown that these new detection parameters exhibit a low level sensitivity to poor signal-to-noise ratios and large signal spectrum widths. The proposed method can consequently be applied to signals with shorter integration time; this significantly reduces the impact of small-scale dynamics present in the Doppler spectrum. Additionally, signals near the cloud top and cloud base are used as constraints to optimize the detection and estimation algorithm's performance.The applications of the technique include inference of the vertical air motion and the particle size distribution of the drizzle. The method will be tested on datasets that have been collected by the ARM cloud radars.

  2. Feeder-Cell Ingestion of Seeding Aerosol from Cloud Base Determined by Tracking Radar Chaff.

    NASA Astrophysics Data System (ADS)

    Reinking, Roger F.; Martner, Brooks E.

    1996-09-01

    Questions of delivery, transport, and dispersion of cloud seeding aerosol in a convective feeder cloud are addressed by using radar chaff as a surrogate for aerosol and tracking it with circular-polarization radar. In a case study, a line source of chaff was released by an aircraft at the roots of a growing cloud flanking and feeding into a thunderstorm line. The chaff was tracked as it dispersed in the boundary layer and rose more than 3 km from the cloud base at +14°C to levels cold enough to nucleate ice-forming seeding aerosols. Quantitative measures of the rates of loft and dispersion, and the volume filling and dilution were obtained. The measurements permit examination of the hypotheses and potential efficacy of cloud-base seeding to increase rain and suppress hail. Notably, the problem of delivery, transport, and dispersion of cloud seeding aerosol is much the same as the air quality question of the nature and effect of cloud venting of the boundary layer, and the findings here apply in that context as well.

  3. The role of spaceborne millimeter-wave radar in the global monitoring of ice cloud

    SciTech Connect

    Brown, P.R.A.; Illingworth, A.J. [Univ. of Reading, Reading (United Kingdom)] [Univ. of Reading, Reading (United Kingdom); Heymsfield, A.J. [National Center for Atmospheric Research, Boulder, CO (United States)] [National Center for Atmospheric Research, Boulder, CO (United States)

    1995-11-01

    The potential of spaceborne 94-GHz radar for measuring global vertical distribution and water content of ice clouds is assessed. Longwave (LW) fluxes for model ice clouds are calculated and used to determine minimum cloud optical depths that will change outgoing longwave radiation or flux divergence within a cloud layer greater than 10 W m{sup -2}, and in surface downward LW flux greater than 5 W m{sup -2}, compared to clear-sky value. Optical depth values are used to define radiatively significant clouds. Thresholds of radiative significance are calculated for radiation parameters and for tropical and midlatitude cirrus clouds. Observational data of ice crystal size spectra from midlatitude and tropical cirrus are used to assess radar capability to meet measurement requirements. A radar threshold of -30 dBZ should detect 99% (92%) of radiatively significant clouds in the midlatitudes. Detection efficiency may be reduced significantly for tropical clouds at very low temperatures (-80 C). LW flux calculations also establish the optical depth accuracy required to estimate LW fluxes or flux divergence. Accuracy requirements are also given in terms of ice water content (IWC) for validating cloud parameterization in general circulation models (GCMs). IWC estimates are derived using radar and additional information to define mean crystal size. IWC for samples with a horizontal scale of 1-2 km has a bias of less than 8%. For IWC larger than 0.01 g m{sup -3}, random error is from +50 to -35%; for 0.001 g m{sup -3}, random error is between +80 and -45%. This is also the best achievable accuracy for cloud optical depth estimates and meets requirements derived from LW flux calculations. Without independent particle size information, random error is from +85 to -55% for IWC greater than 0.01 g m{sup -3} and estimated bias is less than {plus_minus}15%. This accuracy is sufficient to provide useful constraints on GCM cloud parameterization schemes. 34 refs., 15 figs., 6 tabs.

  4. Climatology Of Thin Cirrus Clouds at Gadanki (13.5°N, 79.2°E) Using Ground Based Lidar And Satellite Based Measurements

    NASA Astrophysics Data System (ADS)

    Motty, G. S.; Jayeshlal, G. S.; Satyanarayana, M.

    2014-11-01

    High altitude cirrus clouds play a significant role in the radiative balance of Earth atmosphere system. Information on cirrus occurrences and their optical properties is essential for climate modeling studies. The influence of high altitude thin cirrus clouds on the climate is important due to their optical and thermodynamic properties. In order to quantify their effect on atmosphere, the vertical structure and optical properties of these thin cirrus clouds are to be characterized. The Lidar technique has become a unique tool for detecting and characterizing cirrus clouds for their optical properties. Ground based LIDAR system offers an excellent way to obtain characteristic values on the cirrus formations, although the microphysical and optical properties of thin cirrus clouds can also obtained on global scale by the observations from Earth-orbiting Satellites .The ground-based lidar observations could provide more intensive measurements on continuous basis, compared to satellite observations. Utilising observations from both, the statistical characteristics, physical and optical properties of thin cirrus clouds can be retrieved more precisely. The present study is based on the ground based lidar measurements using the pulsed monostatic LIDAR system at the National Atmospheric Research Laboratory [NARL], Gadanki (13.5° N, 79.2° E), Andhra Pradesh, India. The data obtained in the altitude range of 8-20 km are used for this study. Cirrus observations made using CALIPSO and MODIS satellites are compared with the ground based lidar data for systematic statistical study of cirrus climatology. Optically thin cirrus clouds (? < 0.3) observed during 2009 are selected and their microphysical and geometrical properties are studied. The microphysical properties such as optical depth, lidar ratio and depolarisation ratio for cirrus clouds were obtained. It is observed that the variability in optical depth depends on the composition and thickness of the clouds. The relationships between various quantities were also processed. The study shows that the thin cirrus generally was present in higher altitudes and the optical properties show correlation with the height and the temperature.

  5. 16 year climatology of cirrus clouds over a tropical station in southern India using ground and space-based lidar observations

    NASA Astrophysics Data System (ADS)

    Pandit, A. K.; Gadhavi, H. S.; Venkat Ratnam, M.; Raghunath, K.; Rao, S. V. B.; Jayaraman, A.

    2015-06-01

    16 year (1998-2013) climatology of cirrus clouds and their macrophysical (base height, top height and geometrical thickness) and optical properties (cloud optical thickness) observed using a ground-based lidar over Gadanki (13.5° N, 79.2° E), India, is presented. The climatology obtained from the ground-based lidar is compared with the climatology obtained from seven and half years (June 2006-December 2013) of Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) observations. A very good agreement is found between the two climatologies in spite of their opposite viewing geometries and difference in sampling frequencies. Nearly 50-55% of cirrus clouds were found to possess geometrical thickness less than 2 km. Ground-based lidar is found to detect more number of sub-visible clouds than CALIOP which has implications for global warming studies as sub-visible cirrus clouds have significant positive radiative forcing. Cirrus clouds with mid-cloud temperatures between -50 to -70 °C have a mean geometrical thickness greater than 2 km in contrast to the earlier reported value of 1.7 km. Trend analyses reveal a statistically significant increase in the altitude of sub-visible cirrus clouds which is consistent with the recent climate model simulations. Also, the fraction of sub-visible cirrus cloud is found to be increasing during the last sixteen years (1998 to 2013) which has implications to the temperature and water vapour budget in the tropical tropopause layer.

  6. Prospects of the WSR-88D Radar for Cloud Studies

    E-print Network

    Melnikov, Valery M.; Zrni?, Dusan S.; Doviak, Richard J.; Chilson, Phillip B.; Mechem, David B.; Kogan, Yefim L.

    2011-04-01

    cu- mulus: Bragg and hydrometeor scattering. J. Atmos. Sci., 55, 2974–2992. Kollias, P., B. A. Albrecht, R. Lhermitte, and A. Savtchenko, 2001: Radar observations of updrafts, downdrafts, and turbulence in fair-weather cumuli. J. Atmos. Sci., 58, 1750...

  7. The Use of Coincident Synthetic Aperture Radar and Visible Imagery to Aid in the Analysis of Photon-Counting Lidar Data Sets Over Complex Ice/Snow Surfaces

    NASA Astrophysics Data System (ADS)

    Horan, Kimberly H.

    Qualitative and quantitative analysis of multi-sensor data is becoming increasingly useful as a method of improving our understanding of complex environments, and can be an effective tool in the arsenal to help climate scientists to predict sea level rise due to change in the mass balance of large glaciers in the Arctic and Antarctic. A novel approach to remote sensing of the continuously changing polar environment involves the use of coincident RADARSAT-2 synthetic aperture radar (SAR) imagery and Landsat 7 visible/near-infrared imagery, combined with digital elevation models (DEM) developed from Multiple Altimeter Beam Experimental Lidar (MABEL) data sets. MABEL is a scaled down model of the lidar altimeter that will eventually be flown on ICESat-2, and provides dense along-track and moderate slope (cross-track) elevation data over narrow (~198 m) aircraft transects. Because glacial terrain consists of steep slopes, crevices, glacial lakes, and outflow into the sea, accurate slope information is critical to our understanding of any changes that may be happening in the ice sheets. RADARSAT-2 operates in the C-band, at a wavelength of 5.55 cm, and was chosen partly for its ability to image the Earth under all atmospheric conditions, including clouds. The SAR images not only provide spatial context for the elevation data found using the lidar, but also offer key insights into the consistency of the snow and ice making up the glacier, giving us some idea of mean temperature and surface conditions on the ice sheet. Finally, Landsat 7 images provide us with information on the extent of the glacier, and additional understanding of the state of the glacial surface. To aid in the analysis of the three data sets, proper preparation of each data set must first be performed. For the lidar data, this required the development of a new data reduction technique, based on statistical analysis, to reduce the number of received photons to those representing only the surface return. Accordingly, the raw SAR images require calibration, speckle reduction, and geocorrection, before they can be used. Landsat 7 bands are selected to provide the most contrast between rock, snow, and other surface features, and compiled into a three-band red, green, blue (RGB) image. By qualitatively analyzing images and data taken only a short time apart using multiple imaging modalities, we are able to accurately compare glacial surface features to elevation provided by MABEL, with the goal of increasing our understanding of how the glacier is changing over time. Quantitative analysis performed throughout this thesis has indicated that there is a strong correlation between top-of-the-atmosphere reflectance (Landsat 7), sigma,0-calibrated HH and HV polarized backscatter coefficients (RADARSAT-2), elevation (MABEL), and various surface features and glacial zones on the ice sheet. By comparing data from unknown or mixed surfaces to known quantities scientists can effectively estimate the type of glacial zone the area of interest occurs in. Climate scientists can then use this data, along with long-term digital elevations models, as a measure of predicting climate change.

  8. Application of the CloudSat and NEXRAD Radars Toward Improvements in High Resolution Operational Forecasts

    NASA Astrophysics Data System (ADS)

    Molthan, A. L.; Haynes, J. M.; Jedlovec, G. J.; Lapenta, W. M.

    2008-12-01

    As computational power increases, operational forecast models are performing simulations with higher spatial resolution allowing for the transition from sub-grid scale cloud parameterizations to an explicit forecast of cloud characteristics and precipitation through the use of single- or multi-moment bulk water microphysics schemes. Investments in space-borne and terrestrial remote sensing have developed the NASA CloudSat Cloud Profiling Radar and the NOAA National Weather Service NEXRAD system, each providing observations related to the bulk properties of clouds and precipitation through measurements of reflectivity. CloudSat and NEXRAD system radars observed light to moderate snowfall in association with a cold-season, midlatitude cyclone traversing the Central United States in February 2007. These systems are responsible for widespread cloud cover and various types of precipitation, are of economic consequence, and pose a challenge to operational forecasters. This event is simulated with the Weather Research and Forecast (WRF) Model, utilizing the NASA Goddard Cumulus Ensemble microphysics scheme. Comparisons are made between WRF-simulated and observed reflectivity available from the CloudSat and NEXRAD systems. The application of CloudSat reflectivity is made possible through the QuickBeam radiative transfer model, with cautious application applied in light of single scattering characteristics and spherical target assumptions. Significant differences are noted within modeled and observed cloud profiles, based upon simulated reflectivity, and modifications to the single-moment scheme are tested through a supplemental WRF forecast that incorporates a temperature dependence within the slope parameter of the snow crystal size distribution.

  9. Scanning ARM Cloud Radars. Part II: Data Quality Control and Processing

    SciTech Connect

    Kollias, Pavlos; Jo, Ieng; Borque, Paloma; Tatarevic, Aleksandra; Lamer, Katia; Bharadwaj, Nitin; Widener, Kevin B.; Johnson, Karen L.; Clothiaux, Eugene E.

    2014-03-01

    The Scanning ARM Cloud Radars (SACR’s) are the primary instruments for documenting the four-dimensional structure and evolution of clouds within a 20-30 km radius from the ARM fixed and mobile sites. Here, the post-processing of the calibrated SACR measurements is discussed. First, a feature mask algorithm that objectively determines the presence of significant radar returns is described. The feature mask algorithm is based on the statistical properties of radar receiver noise. It accounts for atmospheric emission and is applicable even for SACR profiles with few or no signal-free range gates. Using the nearest-in-time atmospheric sounding, the SACR radar reflectivities are corrected for gaseous attenuation (water vapor and oxygen) using a line-by-line absorption model. Despite having a high pulse repetition frequency, the SACR has a narrow Nyquist velocity limit and thus Doppler velocity folding is commonly observed. An unfolding algorithm that makes use of a first guess for the true Doppler velocity using horizontal wind measurements from the nearest sounding is described. The retrieval of the horizontal wind profile from the HS-RHI SACR scan observations and/or nearest sounding is described. The retrieved horizontal wind profile can be used to adaptively configure SACR scan strategies that depend on wind direction. Several remaining challenges are discussed, including the removal of insect and second-trip echoes. The described algorithms significantly enhance SACR data quality and constitute an important step towards the utilization of SACR measurements for cloud research.

  10. From Clouds to Life Detection: The Past, Present, and Future of LIDAR

    NASA Astrophysics Data System (ADS)

    DeMarines, J.; Abedin, M. N.; Moore, W.; Bradley, A. T.

    2015-04-01

    LIDAR holds promise for Venus exploration with its application to remote sensing of mineralogy, atmospheric chemistry, and biosignatures. We present new developments in LIDAR instrumentation, and discuss potential applications to Venus science.

  11. Long-term measurements of Polar Stratospheric Clouds with the Esrange lidar

    NASA Astrophysics Data System (ADS)

    Achtert, Peggy; Tesche, Matthias; Blum, Ulrich

    2014-05-01

    Polar Stratospheric Clouds (PSCs) play a key role for ozone depletion in the polar stratosphere whose magnitude depends on the type of PSC and its lifetime and extent. PSCs are classified into three types (PSC Ia: nitric acid di- or trihydrate crystals, NAD or NAT; PSC Ib: supercooled liquid ternary solutions, STS; PSC II: ice) according to their particle composition and to their physical phase. This study presents long-term statistics of PSC occurrence from measurements with the lidar system at the Esrange Space Centre (68°N, 21°E), northern Sweden. The study gives an overview of the occurrence frequency of different PSC types in connection to the prevailing meteorological conditions for the northern hemispheric winters from 1996/97 to 2013/14. During these 18 years, most of the measurements were conducted in January. The geographical location of Esrange in the lee of the Scandinavian mountain range allows for the observation of a wide range of PSC growth conditions due to mountain-wave activity. The Esrange lidar data set contains hourly mean values of the parallel and perpendicularly polarized backscatter ratio and the linear particle depolarization ratio - all measured at 532 nm. These parameters are used for PSC classification. The lowest occurrence frequency is found for PSCs of type II (6% for the entire period). This low occurrence rate is reasonable since PSCs of type II are formed at temperatures below the ice-frost point. Such temperatures are rarely reached in the Arctic polar vortex. Most of the observations between 1997 and 2014 showed low particle depolarization ratios and low backscatter ratios according to which observed PSCs were classified as type Ib (47%) or mixtures (33%). The remaining 13% of the observation were classified as type Ia PSCs (NAT particles).

  12. 1498 JOURNAL OF ,\\TMOSPHERIC AND OCEANIC TECHNOLOGY VULIIME 25 A Techniqne for the Automatic Detection of Insect Clutter in Cloud Radar Returns

    E-print Network

    Detection of Insect Clutter in Cloud Radar Returns EDWARD P. LUKE, PAVLOS KOLLlAS, AND KAREN L. JOHNSON Aml Radiation Measurement (ARM) Program operales 35- GHz millimclcr·w:lvclenglh cloud radars (MMCRs) in several (clullcr) mask. The technique exhibits significam skill in the identification of insect radar returns (morc

  13. Towards Realtime Assimilation of Doppler Radar Observations for Cloud-Resolving Hurricane Prediction

    NASA Astrophysics Data System (ADS)

    Weng, Y.; Zhang, F.; Gamache, J. F.; Marks, F. D.

    2008-12-01

    This study explores the feasibility and impacts of on-demand, real-time assimilation of Doppler radar observations straight from the planes with an ensemble Kalman filter (EnKF) to initialize a cloud-resolving hurricane prediction model. The NOAA P3 aircrafts have being flying into tropical cyclones to gather radar observations since 1994. These observations are significant in investigating and anglicizing hurricane's intensity, eye-wall structure and intensity changes, but the radar data has never been ingested into hurricane prediction models in real-time. Likely reasons are (1) insufficient model resolution due to inadequate computing resources for ingesting convective-scale details observed by the radar, (2) inadequacy of existing data assimilation method for operational models, and (3) lack of sufficient bandwidth in transmitting huge volume radar data to the ground in realtime. This work is built on our recent case studies of predicting the rapid formation and intensification of past hurricanes in assimilating both ground-base and/or airborne radial velocity into a cloud-resolving mesoscale model with EnKF. Under the auspices of NOAA Hurricane Forecasting Improvement Project (HFIP), we have access to the NSF-sponsored high-performance computing facility TACC at University of Texas at Austin that makes realtime cloud-resolving hurricane data assimilation and forecasting possible. We alleviate the requirement of large volume data transfer from the aircraft through developing a radar radial velocity data quality and thinning procedure (namely to produce superobervations or SOs) to significantly reduce the data size before being transferred. We have first conducted near realtime testing of the cloud-resolving data assimilation and forecasting with Weather Research and Forecast (WRF) model using 40.5, 13.5, 4.5 and 1.5 km grid spacings and movable nested grids for Hurricanes Dolly and Fay (2008). As of today, we have successfully demonstrated the feasibility, data follow and effectiveness of on-demand, realtime data assimilation of airborne Doppler observations and subsequent cloud-resolving deterministic and ensemble hurricane forecasting for Hurricanes Gustav and Ike. We plan to conduct more assimilation experiments both in realtime and retrospectively to improve the efficiency and effectiveness of our data assimilation system for future on- demand cloud-resolving hurricane predictions.

  14. The 94GHz cloud profiling radar for the CloudSat mission

    Microsoft Academic Search

    Eastwood Im; Stephen L. Durden; Chialin Wu; Thomas R. Livermore

    2001-01-01

    The CloudSat Mission is a new international satellite mission to acquire a global data set of vertical atmospheric cloud structure and its variability. Such data set is expected to provide crucial input to the studies of cloud physics, radiation budget, water distribution in the atmosphere, and to the numerical weather prediction models. The key science instrument aboard the CloudSat satellite

  15. A Motion-Stabilized W-Band Radar for Shipboard Observations of Marine Boundary-Layer Clouds

    NASA Astrophysics Data System (ADS)

    Moran, Ken; Pezoa, Sergio; Fairall, Chris; Williams, Chris; Ayers, Tom; Brewer, Alan; de Szoeke, Simon P.; Ghate, Virendra

    2012-04-01

    Cloud radars at X, Ka and W-bands have been used in the past for ocean studies of clouds, but the lack of suitable stabilization has limited their usefulness in obtaining accurate measurements of the velocity structure of cloud particles and the heights of cloud features. A 94 GHz (W-band) radar suitable for use on shipboard studies of clouds has been developed that is small and lightweight and can maintain the radar's beam pointing in the vertical to reduce the affects of the pitch and roll of the ship. A vertical velocity sensor on the platform allows the effects of the ship's heave to be removed from the measured cloud particle motions. Results from the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-Rex) field program on the NOAA vessel Ronald H. Brown demonstrate the improvements to the cloud measurements after the ship's motion effects are removed. The compact design of the radar also makes it suitable for use in aircraft studies. The radar is being repackaged to fit in an aft bay of a NOAA P3 aircraft to observe sea-spray profiles during ocean storms.

  16. Double Bright Band Observations with High-Resolution Vertically Pointing Radar, Lidar, and Profiles

    NASA Technical Reports Server (NTRS)

    Emory, Amber E.; Demoz, Belay; Vermeesch, Kevin; Hicks, Michael

    2014-01-01

    On 11 May 2010, an elevated temperature inversion associated with an approaching warm front produced two melting layers simultaneously, which resulted in two distinct bright bands as viewed from the ER-2 Doppler radar system, a vertically pointing, coherent X band radar located in Greenbelt, MD. Due to the high temporal resolution of this radar system, an increase in altitude of the melting layer of approximately 1.2 km in the time span of 4 min was captured. The double bright band feature remained evident for approximately 17 min, until the lower atmosphere warmed enough to dissipate the lower melting layer. This case shows the relatively rapid evolution of freezing levels in response to an advancing warm front over a 2 h time period and the descent of an elevated warm air mass with time. Although observations of double bright bands are somewhat rare, the ability to identify this phenomenon is important for rainfall estimation from spaceborne sensors because algorithms employing the restriction of a radar bright band to a constant height, especially when sampling across frontal systems, will limit the ability to accurately estimate rainfall.

  17. DEVELOPMENT OF A PROCEDURE FOR VERTICAL STRUCTURE ANALYSIS AND 3D-SINGLE TREE EXTRACTION WITHIN FORESTS BASED ON LIDAR POINT CLOUD

    Microsoft Academic Search

    Yunsheng Wang; Holger Weinacker; Barbara Koch

    2007-01-01

    A procedure for both vertical canopy structure analysis and 3D single tree extraction based on Lidar raw point cloud is presented in this paper. The whole study area is segmented into small study cells by a raster net. For each cell, a normalized point cloud whose point heights represent the absolute heights of the ground objects is generated from the

  18. BOREAS AFM-6 NOAA/ETL 35 GHz Cloud/Turbulence Radar GIF Images

    NASA Technical Reports Server (NTRS)

    Martner, Brooks E.; Newcomer, Jeffrey A. (Editor); Hall, Forrest G.; Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from the National Oceanic and Atmospheric Administration/Environment Technology Laboratory (NOAA/ETL) operated a 35-GHz cloud-sensing radar in the Northern Study Area (NSA) near the Old Jack Pine (OJP) tower from 16 Jul 1994 to 08 Aug 1994. This data set contains a time series of GIF images that show the structure of the lower atmosphere. The NOAA/ETL 35-GHz cloud/turbulence radar GIF images are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  19. Airborne LIDAR Measurements of Water Vapor, Ozone, Clouds, and Aerosols in the Tropics Near Central America During the TC4 Experiment

    NASA Technical Reports Server (NTRS)

    Kooi, Susan; Fenn, Marta; Ismail, Syed; Ferrare, Richard; Hair, John; Browell, Edward; Notari, Anthony; Butler, Carolyn; Burton, Sharon; Simpson, Steven

    2008-01-01

    Large scale distributions of ozone, water vapor, aerosols, and clouds were measured throughout the troposphere by two NASA Langley lidar systems on board the NASA DC-8 aircraft as part of the Tropical Composition, Cloud, and Climate Coupling Experiment (TC4) over Central and South America and adjacent oceans in the summer of 2007. Special emphasis was placed on the sampling of convective outflow and transport, sub-visible cirrus clouds, boundary layer aerosols, Saharan dust, volcanic emissions, and urban and biomass burning plumes. This paper presents preliminary results from this campaign, and demonstrates the value of coordinated measurements by the two lidar systems.

  20. Scanning Backscatter Lidar Observations for Characterizing 4-D Cloud and Aerosol Fields to Improve Radiative Transfer Parameterizations

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.; Miller, David O.

    2005-01-01

    Clouds have a powerful influence on atmospheric radiative transfer and hence are crucial to understanding and interpreting the exchange of radiation between the Earth's surface, the atmosphere, and space. Because clouds are highly variable in space, time and physical makeup, it is important to be able to observe them in three dimensions (3-D) with sufficient resolution that the data can be used to generate and validate parameterizations of cloud fields at the resolution scale of global climate models (GCMs). Simulation of photon transport in three dimensionally inhomogeneous cloud fields show that spatial inhomogeneities tend to decrease cloud reflection and absorption and increase direct and diffuse transmission, Therefore it is an important task to characterize cloud spatial structures in three dimensions on the scale of GCM grid elements. In order to validate cloud parameterizations that represent the ensemble, or mean and variance of cloud properties within a GCM grid element, measurements of the parameters must be obtained on a much finer scale so that the statistics on those measurements are truly representative. High spatial sampling resolution is required, on the order of 1 km or less. Since the radiation fields respond almost instantaneously to changes in the cloud field, and clouds changes occur on scales of seconds and less when viewed on scales of approximately 100m, the temporal resolution of cloud properties should be measured and characterized on second time scales. GCM time steps are typically on the order of an hour, but in order to obtain sufficient statistical representations of cloud properties in the parameterizations that are used as model inputs, averaged values of cloud properties should be calculated on time scales on the order of 10-100 s. The Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE) provides exceptional temporal (100 ms) and spatial (30 m) resolution measurements of aerosol and cloud backscatter in three dimensions. HARLIE was used in a ground-based configuration in several recent field campaigns. Principal data products include aerosol backscatter profiles, boundary layer heights, entrainment zone thickness, cloud fraction as a function of altitude and horizontal wind vector profiles based on correlating the motions of clouds and aerosol structures across portions of the scan. Comparisons will be made between various cloud detecting instruments to develop a baseline performance metric.

  1. Identification of a Debris Cloud from the Nuclear Powered SNAPSHOT Satellite with Haystack Radar Measurements

    NASA Technical Reports Server (NTRS)

    Stokely, C.; Stansbery, E.

    2006-01-01

    Data from the MIT Lincoln Laboratory (MIT/LL) Long Range Imaging Radar (known as the Haystack radar) have been used in the past to examine families of objects from individual satellite breakups or families of orbiting objects that can be isolated in altitude and inclination. This is possible because for some time after a breakup, the debris cloud of particles can remain grouped together in similar orbit planes. This cloud will be visible to the radar, in fixed staring mode, for a short time twice each day, as the orbit plane moves through the field of view. There should be a unique three-dimensional pattern in observation time, range, and range rate which can identify the cloud. Eventually, through slightly differing precession rates of the right ascension of ascending node of the debris cloud, the observation time becomes distributed so that event identification becomes much more difficult. Analyses of the patterns in observation time, range, and range rate have identified good debris candidates released from the polar orbiting SNAPSHOT satellite (International Identifier: 1965-027A). For orbits near 90o inclination, there is essentially no precession of the orbit plane. The SNAPSHOT satellite is a well known nuclear powered satellite launched in 1965 to a near circular 1300 km orbit with an inclination of 90.3o. This satellite began releasing debris in 1979 with new pieces being discovered and cataloged over the years. 51 objects are still being tracked by the United States Space Surveillance Network. An analysis of the Haystack data has identified at least 60 pieces of debris separate from the 51 known tracked debris pieces, where all but 2 of the 60 pieces have a size less than 10cm. The altitude and inclination (derived from range-rate with a circular orbit assumption) are consistent with the SNAPSHOT satellite and its tracked debris cloud.

  2. Measurements of Ocean Surface Scattering Using an Airborne 94-GHz Cloud Radar: Implication for Calibration of Airborne and Spaceborne W-band Radars

    NASA Technical Reports Server (NTRS)

    Li, Li-Hua; Heymsfield, Gerald M.; Tian, Lin; Racette, Paul E.

    2004-01-01

    Scattering properties of the Ocean surface have been widely used as a calibration reference for airborne and spaceborne microwave sensors. However, at millimeter-wave frequencies, the ocean surface backscattering mechanism is still not well understood, in part, due to the lack of experimental measurements. During the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE), measurements of ocean surface backscattering were made using a 94-GHz (W-band) cloud radar onboard a NASA ER-2 high-altitude aircraft. The measurement set includes the normalized Ocean surface cross section over a range of the incidence angles under a variety of wind conditions. Analysis of the radar measurements shows good agreement with a quasi-specular scattering model. This unprecedented dataset enhances our knowledge about the Ocean surface scattering mechanism at 94 GHz. The results of this work support the proposition of using the Ocean surface as a calibration reference for airborne millimeter-wave cloud radars and for the ongoing NASA CloudSat mission, which will use a 94-GHz spaceborne cloud radar for global cloud measurements.

  3. Microphysical parameters of cirrus clouds using lidar at a tropical station, Gadanki, Tirupati (13.5° N, 79.2°E), India

    NASA Astrophysics Data System (ADS)

    Satyanarayana, M.; Radhakrishnan, S.-R.; Krishnakumar, V.; Mahadevan Pillai, V. P.; Raghunath, K.

    2008-12-01

    Cirrus clouds have been identified as one of the most uncertain component in the atmospheric research. It is known that cirrus clouds modulate the earth's climate through direct and indirect modification of radiation. The role of cirrus clouds depends mainly on their microphysical properties. To understand cirrus clouds better, we must observe and characterize their properties. In-situ observation of such clouds is a challenging experiment, as the clouds are located at high altitudes. Active remote sensing method based on lidar can detect high and thin cirrus clouds with good spatial and temporal resolution. We present the result obtained on the microphysical properties of the cirrus clouds at two Tropical stations namely Gadhanki, Tirupati (13.50 N, 79.20 E), India and Trivandrum (13.50 N, 770 E) Kerala, India from the ground based pulsed Nd: YAG lidar systems installed at the stations. A variant of the widely used Klett's lidar inversion method with range dependent scattering ratio is used for the present study for the retrieval of aerosol extinction and microphysical parameters of cirrus cloud.

  4. Observations of a glaciating hole-punch cloud

    E-print Network

    Westbrook, C D

    2009-01-01

    Remote-sensing measurements of a hole-punch cloud or fall-streak hole are presented. The cloud was observed with a vertically pointing infrared ceilometer, Doppler lidar, sky camera and a polarimetric radar inclined at 45 degrees. The Doppler lidar and polarimetric radar observations show that the aircraft-induced fall streak was composed primarily of oriented thick plate crystals, and the vertical Doppler velocities suggest that vertical mixing may have been triggered by the large flux of ice into the dry air at the base of the virga.

  5. Science Goals for the ARM Recovery Act Radars

    SciTech Connect

    JH Mather

    2012-05-29

    Science Goals for the ARM Recovery Act Radars. In October 2008, an ARM workshop brought together approximately 30 climate research scientists to discuss the Atmospheric Radiation Measurement (ARM) Climate Research Facility's role in solving outstanding climate science issues. Through this discussion it was noted that one of ARM's primary contributions is to provide detailed information about cloud profiles and their impact on radiative fluxes. This work supports cloud parameterization development and improved understanding of cloud processes necessary for that development. A critical part of this work is measuring microphysical properties (cloud ice and liquid water content, cloud particle sizes, shapes, and distribution). ARM measurements and research have long included an emphasis on obtaining the best possible microphysical parameters with the available instrumentation. At the time of the workshop, this research was reaching the point where additional reduction in uncertainties in these critical parameters required new instrumentation for applications such as specifying radiative heating profiles, measuring vertical velocities, and studying the convective triggering and evolution of three-dimensional (3D) cloud fields. ARM was already operating a subset of the necessary instrumentation to make some progress on these problems; each of the ARM sites included (and still includes) a cloud radar (operating at 35 or 94 GHz), a cloud lidar, and balloon-borne temperature and humidity sensors. However, these measurements were inadequate for determining detailed microphysical properties in most cases. Additional instrumentation needed to improve retrievals of microphysical processes includes radars at two additional frequencies for a total of three at a single site (35 GHz, 94 GHz, and a precipitation radar) and a Doppler lidar. Evolving to a multi-frequency scanning radar is a medium-term goal to bridge our understanding of two-dimensional (2D) retrievals to the 3D cloud field. These additional microphysical measurements would allow detailed cloud properties to be derived even in the presence of light precipitation. It is important to couple these detailed measurements of cloud microphysics to vertical motion on the cloud scale to couple microphysics with meteorological processes. Vertically pointing Doppler radars provide the vertical motion of cloud particles but, to separate particle motion from air motion, a wind profiler is required. The American Recovery and Reinvestment Act provided the means to address these needs and implement a multi-frequency suite of radars, including scanning radars, at each of the ARM sites. In addition, Doppler lidars have been deployed at several sites. With these new measurement capabilities, ARM has the measurement capabilities to tackle the problems of improving microphysical profile descriptions and evaluating the relationship between our current narrow-field-of view, zenith perspective on clouds to a description of the full 3D cloud field and its temporal evolution.

  6. MM-Wave Radar Structure and Microphysical Characteristics of a Mixed Phase Altocumulus Cloud on 2 November 2001

    Microsoft Academic Search

    L. D. Carey; L. R. Belcher; A. Kankiewicz; T. H. Vonder Haar

    2005-01-01

    The ninth Cloud Layer Experiment (CLEX-9), conducted over western Nebraska from 8 October to 4 November 2001 provided in-situ microphysical and radar measurements of mid-level clouds from the University of Wyoming King Air research aircraft (UWKA). Microphysical measurements include cloud liquid water (LWC) and ice water contents (IWC) from a suite of microphysical probes (e.g., PMS 2D-C, 2D-P, and DMT-100

  7. The influence of rain and clouds on a satellite dual frequency radar altimeter system operating at 13 and 35 GHz

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Monaldo, F. M.; Goldhirsh, J.

    1983-01-01

    The effects of inhomogeneous spatial attenuation resulting from clouds and rain on the altimeter estimate of the range to mean sea level are modelled. It is demonstrated that typical cloud and rain attenuation variability at commonly expected spatial scales can significantly degrade altimeter range precision. Rain cell and cloud scale sizes and attenuations are considered as factors. The model simulation of altimeter signature distortion is described, and the distortion of individual radar pulse waveforms by different spatial scales of attenuation is considered. Examples of range errors found for models of a single cloud, a rain cell, and cloud streets are discussed.

  8. Modeling Residential Urban Areas from Dense Aerial LiDAR Point Clouds

    E-print Network

    Shahabi, Cyrus

    models for residential areas from aerial LiDAR scans. The key differ- ence between downtown area modeling of building structures invisible to laser scans; in contrast, trees do not possess such characteristic as a reference(b) Our modeling result Fig. 1. Given (a) a dense aerial LiDAR scan of a residential area (point

  9. Complete Residential Urban Area Reconstruction from Dense Aerial LiDAR Point Clouds

    E-print Network

    Shahabi, Cyrus

    D urban models for residen- tial areas from aerial LiDAR scans. The key difference between downtown, making the interior of building structures invisible to laser scans; in contrast, trees do not possess aerial LiDAR scans has been an important topic in both computer graphics and computer vision

  10. Multiwavelength observations of a devleoping cloud system: The FIRE II 26 November 1991 case study

    SciTech Connect

    Intrieri, J.M.; Eberhard, W.L.; Uttal, T. [NOAA/ERL/Environmental Technology Lab., Boulder, CO (United States)] [and others] [NOAA/ERL/Environmental Technology Lab., Boulder, CO (United States); and others

    1995-12-01

    Simultaneous multiwavelength measurements of a developing cloud system were obtained by NOAA Doppler lidar, Doppler radar, Fourier transform infrared interferometer, and microwave and infrared radiometers on 26 November 1991. The evolution of the cloud system is described in terms of lidar backscatter, radar reflectivity and velocity, interferometer atmospheric spectra, and radiometer brightness temperature, integrated liquid water, and water vapor paths. Utilizing the difference in wavelength between the radar and lidar, and therefore their independent sensitivity to different regions of the same cloud, the cloud top, base, depth, and multiple layer heights can be determined with better accuracy than with either instrument alone. Combining the radar, lidar, and radiometer measurements using two different techniques allows an estimation of the vertical profile of cloud microphysical properties such as particle sizes. Enhancement of lidar backscatter near zenith revealed when highly oriented ice crystals were present. The authors demonstrate that no single instrument is sufficient to accurately describe cirrus clouds and that measurements in combination can provide important details on their geometric, radiative, and microphysical properties.

  11. Measurement of Mean or Effective Radius of Cloud Drop Size Distributions with a 10.6-micron Wavelength Lidar

    NASA Technical Reports Server (NTRS)

    Eberhard, Wynn L.

    1992-01-01

    Platt and Takashima (1987) proposed and analytically evaluated a technique to observe the mode radius R sub p of drop size distributions in clouds using the backscatter detected by a CO2 lidar. The scheme depends on fortuitous relationships between the backscatter and extinction properties of common drop size distributions when probed with wavelengths between about 9 and 11 microns, which is the range of CO2 laser transitions. This study extends their work to measurement of mean and effective radius and presents experimental results that demonstrate that the technique is practical.

  12. Detection of Tropical Thin Cirrus Clouds Over Dark Water From MISR With Comparisons to Ground-based Lidar

    NASA Astrophysics Data System (ADS)

    Garay, M. J.; Kahn, R.; Comstock, J.; Welton, E. J.

    2006-12-01

    A detailed tropical cirrus cloud climatology having good temporal and spatial resolution is important because cirrus clouds are known to play important roles in the tropical radiation budget and the global climate system. In addition, undetected, optically thin cirrus can lead to biases in satellite aerosol and surface property retrievals. Inventories of tropical cirrus occurrence have been compiled from limb-sounding instruments, but these instruments are limited in their ability to characterize the horizontal extent and distribution of the clouds. Due to their tenuous nature, thin cirrus can be difficult to detect using higher horizontal resolution, nadir- viewing techniques, particular those that rely on infrared channels. Ground-based lidar observations of tropical thin cirrus clouds at the Atmospheric Radiation Measurement (ARM) sites at Manus and Nauru have provided detailed information about the frequency and properties of the cirrus clouds that occur over these sites. However, these studies only provide sparse spatial sampling. Here we present a unique approach to the problem of tropical thin cirrus detection and characterization that exploits the capabilities of the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's polar- orbiting Terra satellite. Although the lower optical depth limit of typical satellite cloud detection algorithms is no better than 0.1, it has been demonstrated that MISR is sensitive to aerosol optical depths approximately 0.05 and larger. The geometry of MISR's nine cameras increases instrument sensitivity to optically thin layers, since air mass factors as high as three are sampled at the most oblique camera angles. In the tropics, MISR observes scattering angles ranging from about 100 to 160 degrees, which provides sensitivity to particle shape for all but the smallest particles. To test MISR's ability to detect and characterize optically thin tropical cirrus, we compare MISR retrievals with coincident observations from ground-based lidar located at a number of Atmospheric Radiation Measurement (ARM) and Micro-pulse Lidar Network (MPLNET) sites. Preliminary results suggest that MISR is capable of distinguishing cirrus in the presence of other aerosols if the total column aerosol optical depth is greater than 0.2 and cirrus contributes more than approximately 20 percent to this total. This work is the first step toward the larger goal of retrieving cirrus optical depth and ice particle properties using this technique on a global basis over the world's oceans. The work of MJG and RAK is performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  13. Studying Clouds and Aerosols with Lidar Depolarization Ratio and Backscatter Relationships 

    E-print Network

    Cho, Hyoun-Myoung

    2012-02-14

    comparison of mineral dust aerosol retrievals from two instruments, MODIS and CALIPSO lidar. And, we implement and evaluate a new mineral dust detection algorithm based on the analysis of thin dust radiative signature. In comparison, three commonly used...

  14. Smoke detection using a compact and eye-safe lidar

    NASA Astrophysics Data System (ADS)

    Streicher, Juergen; Werner, Christian

    1999-05-01

    Cloud ceiling determination using laser radar (lidar) is a well known application of this remote sensing technique. It is no problem to measure large distances up to some kilometers, since the particles of interest (water droplets) reflect the laser radiation pretty well, even when using very tiny light sources (eye safety criterion). This detection of white scatterers (clouds) points of course to the question whether it will be possible to measure dark particles for example smoke as well. The possible measurement range of the remote sensing smoke detectors cover medium scale observations, like corridor sensors, as well as large scale systems, like replacing fire alarm sensors in a tunnel by one single lidar system. It will be reported on the double impact using the laser radar technique: the range resolved measurement of black smoke as well as using the transmission path of the laser light as a control device.

  15. Dependence of the lidar signal depolarization on the receiver's field of view in the sounding of fog and clouds

    NASA Astrophysics Data System (ADS)

    Tatarov, B.; Trifonov, T.; Kaprielov, B.; Kolev, I.

    We report an experimental study of the lidar signal depolarization as a function of the relative contribution of the multiple scattering in case of optically dense objects in the atmospheric planetary boundary layer. Results of the observation of fog and stratus clouds are presented, as well as those obtained by sounding of stratocumulus clouds during a snowfall. The lidar data point to a rise of the depolarization coefficient as the influence of the multiple scattering increases in consequence of both viewing angle enlargement and penetration into the object sounded. The variations of the depolarization coefficient are studied as a function of the field of view. In the case of fog, this dependence is approximated by a three-parameter exponential law; it is found that the depolarization increases steeply when the viewing angle is increased from 9 mrad to 12.5 mrad. The relationships between the approximation parameters and the microphysical characteristics of the scattering medium are considered. The experimentally determined size of the area where multiple scattering occurs is in good agreement with that calculated according to the diffusion model. The results obtained on the multiple scattering effect on the depolarization can also be employed in determining the extinction coefficient profiles in optically dense objects, as well as in evaluating the characteristic size of the scattering particles.

  16. Evaporation of rain falling from convective clouds as derived from radar measurements

    NASA Technical Reports Server (NTRS)

    Rosenfeld, Daniel; Mintz, Yale

    1988-01-01

    A computerized method developed by Rosenfeld (1987) is used to track the three-dimensional structure of the rainshafts of about 3000 summer afternoon convective rain cells in the semiarid region of central South Africa. By assuming a fixed relationship between the radar reflectivity factor and the rain intensity, time- and area-integrated rain volumes of each individual rainshaft are obtained at the cloudbase level and at a lower level. These results are used to obtain the cumulative fractional evaporation of the falling rain. This permits the cumulative evaporation of the falling rain to be obtained in a quantitative way as a function of the fall distance from the cloud base level and the rain intensity at the cloud base.

  17. Radar

    Microsoft Academic Search

    James R. Zimbelman; Kenneth S. Edgett

    1994-01-01

    Over 1,000,000 km2 of the equatorial surface of Mars west of the Arsia Mons volcano displays no 3.5-cm radar echo to the very low level of the radar system noise for the Very Large Array; the area displaying this unique property has been terms \\

  18. Spatial distribution of lacunarity of voxelized airborne LiDAR point clouds in various forest assemblages

    NASA Astrophysics Data System (ADS)

    Székely, Balázs; Kania, Adam; Standovár, Tibor; Heilmeier, Hermann

    2015-04-01

    Forest ecosystems have characteristic structure of features defined by various structural elements of different scales and vertical positions: shrub layers, understory vegetation, tree trunks, and branches. Furthermore in most of the cases there are superimposed structures in distributions (mosaic or island patterns) due to topography, soil variability, or even anthropogenic factors like past/present forest management activity. This multifaceted spatial context of the forests is relevant for many ecological issues, especially for maintaining forest biodiversity. Our aim in this study is twofold: (1) to quantify this structural variability laterally and vertically using lacunarity, and (2) to relate these results to relevant ecological features, i.e quantitatively described forest properties. Airborne LiDAR data of various quality and point density have been used for our study including a number of forested sites in Central and East Europe (partly Natura 2000 sites). The point clouds have been converted to voxel format and then converted to horizontal layers as images. These images were processed further for the lacunarity calculation. Areas of interest (AOIs) have been selected based on evaluation of the forested areas and auxiliary field information. The calculation has been performed for the AOIs for all available vertical data slices. The lacunarity function referring to a certain point and given vicinity varies horizontally and vertically, depending on the vegetation structure. Furthermore, the topography may also influence this property as the growth of plants, especially spacing and size of trees are influenced by the local topography and relief (e.g., slope, aspect). The comparisons of the flatland and hilly settings show interesting differences and the spatial patterns also vary differently. Because of the large amount of data resulting from these calculations, sophisticated methods are required to analyse the results. The large data amount then has been structured according to AOIs and relevant AOI pairs or small groups have been formed for comparative purposes. Change detection techniques have been applied to reveal fine differences. The spatial variation can be related to ecologically relevant forest characteristics. Data used in this study have been acquired in the framework of ChangeHabitat2 project (an IAPP Marie Curie Actions project of the European Union), in Hungarian-Slovakian Transnational Cooperation Programme 2007-2013, "Management of World Heritage Aggtelek Karst/Slovakian Karst Caves" (HUSK/1101/221/0180, Aggtelek NP). These studies were partly carried out in the project 'Multipurpose assessment serving forest biodiversity conservation in the Carpathian region of Hungary', Swiss-Hungarian Cooperation Programme (SH/4/13 Project). BS contributed as an Alexander von Humboldt Research Fellow.

  19. Turn-key Raman lidar for profiling atmospheric water vapor, clouds, and aerosols at the US Southern Great Plains Climate Study Site

    SciTech Connect

    Goldsmith, J.E.M.; Blair, F.H.; Bisson, S.E.

    1997-12-31

    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.

  20. NASA/GSFC Scanning Raman Lidar Measurements of Water Vapor and Clouds during the International H2O Project (IHOP) Field Campaign

    NASA Technical Reports Server (NTRS)

    Whiteman, David; Demoz, Belay; DiGirolamo, Paolo; Wang, Zhi-En; Evans, Keith; Lin, Ruei-Fong

    2003-01-01

    The NASA/GSFC Scanning Raman Lidar (SFL) acquired approximately 200 hours of water vapor, aerosol and cloud measurements during the IHOP field campaign. The detailed water vapor structure of events such as a dryline passage and internal bores were revealed. We discuss the error characteristics of the instrument as well as the water vapor and cirrus cloud structure during the 19-20 June bore event.

  1. Ice Concentration Retrieval in Stratiform Mixed-phase Clouds Using Cloud Radar Reflectivity Measurements and 1D Ice Growth Model Simulations

    SciTech Connect

    Zhang, Damao; Wang, Zhien; Heymsfield, Andrew J.; Fan, Jiwen; Luo, Tao

    2014-10-01

    Measurement of ice number concentration in clouds is important but still challenging. Stratiform mixed-phase clouds (SMCs) provide a simple scenario for retrieving ice number concentration from remote sensing measurements. The simple ice generation and growth pattern in SMCs offers opportunities to use cloud radar reflectivity (Ze) measurements and other cloud properties to infer ice number concentration quantitatively. To understand the strong temperature dependency of ice habit and growth rate quantitatively, we develop a 1-D ice growth model to calculate the ice diffusional growth along its falling trajectory in SMCs. The radar reflectivity and fall velocity profiles of ice crystals calculated from the 1-D ice growth model are evaluated with the Atmospheric Radiation Measurements (ARM) Climate Research Facility (ACRF) ground-based high vertical resolution radar measurements. Combining Ze measurements and 1-D ice growth model simulations, we develop a method to retrieve the ice number concentrations in SMCs at given cloud top temperature (CTT) and liquid water path (LWP). The retrieved ice concentrations in SMCs are evaluated with in situ measurements and with a three-dimensional cloud-resolving model simulation with a bin microphysical scheme. These comparisons show that the retrieved ice number concentrations are within an uncertainty of a factor of 2, statistically.

  2. Intercomparison of Vertical Structure of Storms Revealed by Ground-Based (NMQ) and Spaceborne Radars (CloudSat-CPR and TRMM-PR)

    PubMed Central

    Fall, Veronica M.; Hong, Yang

    2013-01-01

    Spaceborne radars provide great opportunities to investigate the vertical structure of clouds and precipitation. Two typical spaceborne radars for such a study are the W-band Cloud Profiling Radar (CPR) and Ku-band Precipitation Radar (PR), which are onboard NASA's CloudSat and TRMM satellites, respectively. Compared to S-band ground-based radars, they have distinct scattering characteristics for different hydrometeors in clouds and precipitation. The combination of spaceborne and ground-based radar observations can help in the identification of hydrometeors and improve the radar-based quantitative precipitation estimation (QPE). This study analyzes the vertical structure of the 18 January, 2009 storm using data from the CloudSat CPR, TRMM PR, and a NEXRAD-based National Mosaic and Multisensor QPE (NMQ) system. Microphysics above, within, and below the melting layer are studied through an intercomparison of multifrequency measurements. Hydrometeors' type and their radar scattering characteristics are analyzed. Additionally, the study of the vertical profile of reflectivity (VPR) reveals the brightband properties in the cold-season precipitation and its effect on the radar-based QPE. In all, the joint analysis of spaceborne and ground-based radar data increases the understanding of the vertical structure of storm systems and provides a good insight into the microphysical modeling for weather forecasts. PMID:24459424

  3. Intercomparison of vertical structure of storms revealed by ground-based (NMQ) and spaceborne radars (CloudSat-CPR and TRMM-PR).

    PubMed

    Fall, Veronica M; Cao, Qing; Hong, Yang

    2013-01-01

    Spaceborne radars provide great opportunities to investigate the vertical structure of clouds and precipitation. Two typical spaceborne radars for such a study are the W-band Cloud Profiling Radar (CPR) and Ku-band Precipitation Radar (PR), which are onboard NASA's CloudSat and TRMM satellites, respectively. Compared to S-band ground-based radars, they have distinct scattering characteristics for different hydrometeors in clouds and precipitation. The combination of spaceborne and ground-based radar observations can help in the identification of hydrometeors and improve the radar-based quantitative precipitation estimation (QPE). This study analyzes the vertical structure of the 18 January, 2009 storm using data from the CloudSat CPR, TRMM PR, and a NEXRAD-based National Mosaic and Multisensor QPE (NMQ) system. Microphysics above, within, and below the melting layer are studied through an intercomparison of multifrequency measurements. Hydrometeors' type and their radar scattering characteristics are analyzed. Additionally, the study of the vertical profile of reflectivity (VPR) reveals the brightband properties in the cold-season precipitation and its effect on the radar-based QPE. In all, the joint analysis of spaceborne and ground-based radar data increases the understanding of the vertical structure of storm systems and provides a good insight into the microphysical modeling for weather forecasts. PMID:24459424

  4. Finding Planes in LiDAR Point Clouds for Real-Time Registration W. Shane Grant*, Randolph C. Voorhies*, and Laurent Itti

    E-print Network

    Itti, Laurent

    comprising 827 successive 3D laser scans (over 57 million points), using no additional information (eFinding Planes in LiDAR Point Clouds for Real-Time Registration W. Shane Grant*, Randolph C is capable of handling large and sparse datasets such as those generated from spinning multi-laser sensors

  5. Radar Reflectivity Simulated by a 2-D Spectra Bin Model: Sensitivity of Cloud-aerosol Interaction

    NASA Technical Reports Server (NTRS)

    Li, Kiaowen; Tao, Wei-Kuo; Khain, Alexander; Simpson, Joanne; Johnson, Daniel

    2003-01-01

    The Goddard Cumulus Ensemble (GCE) model with bin spectra microphysics is used to simulate mesoscale convective systems.The model uses explicit bins to represent size spectra of cloud nuclei, water drops, ice crystals, snow and graupel. Each hydrometeorite category is described by 33 mass bins. The simulations provide a unique data set of simulated raindrop size distribution in a realistic dynamic frame. Calculations of radar parameters using simulated drop size distribution serve as an evaluation of numerical model performance. In addition, the GCE bin spectra modes is a very useful tool to study uncertainties related to radar observations; all the environmental parameters are precisely known. In this presentation, we concentrate on the discussion of Z-R (ZDR-R) relation in the simulated systems. Due to computational limitations, the spectra bin model has been run in two dimensions with 31 stretched vertical layers and 1026 horizontal grid points (1 km resolution). Two different cases, one in midlatitude continent, the other in tropical ocean, have been simulated. The continental case is a strong convection which lasted for two hours. The oceanic case is a persistent system with more than 10 hours' life span. It is shown that the simulated Z-R (ZDR-R) relations generally agree with observations using radar and rain gauge data. The spatial and temporal variations of Z-R relation in different locations are also analyzed. Impact of aerosols on cloud formation and raindrop size distribution was studied. Both clean (low CCN) and dirty (high CCN) cases are simulated. The Z-R relation is shown to vary considerable in the initial CCN concentrations.

  6. An Offset Linear-Array-Fed Ku\\/Ka Dual-Band Reflectarray for Planet Cloud\\/Precipitation Radar

    Microsoft Academic Search

    Shih-Hsun Hsu; Chulmin Han; John Huang; Kai Chang

    2007-01-01

    A Ku\\/Ka band dual-frequency offset array-fed microstrip reflectarray antenna using thin membranes has been developed. This antenna is a demonstration model for the next generation titan cloud precipitation radar and altimeter (TCPRA) and is intended to enhance the capability of the future cloud and precipitation remote sensing system for Earth and other planets. The reflectarray has a dimension of 0.5-m

  7. Evaluating Microphysics in Cloud-Resolving Models using TRMM and Ground-based Precipitation Radar Observations

    NASA Astrophysics Data System (ADS)

    Krueger, S. K.; Zulauf, M. A.; Li, Y.; Zipser, E. J.

    2005-05-01

    Global satellite datasets such as those produced by ISCCP, ERBE, and CERES provide strong observational constraints on cloud radiative properties. Such observations have been widely used for model evaluation, tuning, and improvement. Cloud radiative properties depend primarily on small, non-precipitating cloud droplets and ice crystals, yet the dynamical, microphysical and radiative processes which produce these small particles often involve large, precipitating hydrometeors. There now exists a global dataset of tropical cloud system precipitation feature (PF) properties, collected by TRMM and produced by Steve Nesbitt, that provides additional observational constraints on cloud system properties. We are using the TRMM PF dataset to evaluate the precipitation microphysics of two simulations of deep, precipitating, convective cloud systems: one is a 29-day summertime, continental case (ARM Summer 1997 SCM IOP, at the Southern Great Plains site); the second is a tropical maritime case: the Kwajalein MCS of 11-12 August 1999 (part of a 52-day simulation). Both simulations employed the same bulk, three-ice category microphysical parameterization (Krueger et al. 1995). The ARM simulation was executed using the UCLA/Utah 2D CRM, while the KWAJEX simulation was produced using the 3D CSU CRM (SAM). The KWAJEX simulation described above is compared with both the actual radar data and the TRMM statistics. For the Kwajalein MCS of 11 to 12 August 1999, there are research radar data available for the lifetime of the system. This particular MCS was large in size and rained heavily, but it was weak to average in measures of convective intensity, against the 5-year TRMM sample of 108. For the Kwajalein MCS simulation, the 20 dBZ contour is at 15.7 km and the 40 dBZ contour at 14.5 km! Of all 108 MCSs observed by TRMM, the highest value for the 40 dBZ contour is 8 km. Clearly, the high reflectivity cores are off scale compared with observed cloud systems in this area. A similar conclusion can be reached by comparing the simulated microwave brightness temperatures with observed brightness temperatures at 85 GHz and 37 GHz. In each case, the simulations are more extreme than all observed MCSs in the region over the 5 year period. The situation is similar but less egregious for the southern Great Plains simulation. Inspection of the cloud microphysics output files reveals the source of the discrepancy between simulation and observations in the upper troposphere. The simulations have very large graupel concentrations between about 5-10 km, as high as 10 g/kg graupel mixing ratio. This guarantees that there are very high radar reflectivities extending into the upper troposphere, and unrealistically low microwave brightness temperatures. We also performed a set of short (6-h) numerical simulations of the life cycle of a single convection cell to examine the sensitivity of the simulated graupel fields to the intercept parameter and the density of the graupel. The control case used the same values as the ARM and KWAJEX simulations. Reducing the intercept parameter by a factor of 100 reduced the maximum graupel mixing ratios but increased the maximum dBZ values. This suggests that the discrepencies between the simulations and the observations must involve the graupel growth rates.

  8. Orographic precipitation enhancement by boundary-layer turbulence: evidence from vertically pointing airborne cloud radar data

    NASA Astrophysics Data System (ADS)

    Geerts, B.; Miao, Q.

    2010-09-01

    The University of Wyoming King Air, with multi-antenna 3 mm Doppler radar (the Wyoming Cloud Radar, or WCR), is used to examine shallow orographic precipitation growth. The key question regards how boundary-layer turbulence affects orographic precipitation growth in cold clouds. Houze and Medina and (2005) speculate that BL turbulence is important in snow growth, mainly though riming in turbulent eddies whose updraft speed far exceeds the average ascent rate over the terrain. Flight-level cloud microphysics data and WCR data were collected in flights across the Snowy range in Wyoming. The WCR Doppler velocity transects across the mountain clearly indicate intense turbulence, not in a stable shear layer intersecting the terrain (the mechanism proposed by Houze and Medina (2005)), but rather in the boundary-layer, roughly in the lowest 1 km above the undulating ground, especially on the windier days. This turbulence enhances the hydrometeor growth rate by riming, and thus more precipitation reaching the ground before the crest. Also, ice nucleation may occur along rimed surfaces on the ground, such as trees, or by snow on the ground lofted by turbulent wind gusts. The resulting ice crystals are readily mixed by BL turbuelnce, and thus the Bergeron process too may enhance the growth rate of snow. Specifically, BL turbulence co-locates supercooled liquid water and near-surface ice crystals in updrafts, where rapid growth is likely. This work addresses both the significance of BL turbulence, surface-induced nucleation, and possible interaction between the turbulence and upper level processes. This work is based on evidence from a single mountain range. It remains unclear how common the observed conditions are

  9. Inversion of water cloud lidar signals based on accumulated depolarization ratio.

    PubMed

    Roy, Gilles; Cao, Xiaoying

    2010-03-20

    The relation between the accumulated single scattering factor and the layer accumulated depolarization ratio appears to be independent of the geometry of the measurements and contains information on the optical depth and thus on the extinction coefficient. A simple equation is developed to retrieve the extinction coefficient from the total integrated signal and the integrated depolarization ratio measurements. The results compare well with Klett and Weinman lidar inversion techniques. The results from the measurements of the integrated depolarization ratio can be used to set the far end initial extinction coefficient value required for Klett and Weinman lidar inversion or can be used directly. PMID:20300160

  10. Characterization of rockslide dynamics by the joint analysis of airborne LiDAR and stereo-photogrammetric point clouds.

    NASA Astrophysics Data System (ADS)

    Mathieu, Alexandre; Malet, Jean-Philippe; Stumpf, André

    2014-05-01

    The catchment of Sanières is located on the South-facing slope of the Barcelonnette basin (South French Alps). This region is known to be highly prone to gravitational processes including large landslides and debris-flows. In early August 2013, a large rockslide event occurred in the lower part of the catchment. During several days, a large amount of debris have been mobilised along a 300m length cliff. Deposits have reached and filled the torrential channel downslope. Several field observations carried out in the following weeks have shown the progressive opening of fissures along the main scarp. Today, large volumes of unstable debris are still available on the slope. Local stakeholders are now expecting the formation of a debris-dam in the channel which could lead to a debris flow in case of failure. Since the rockslide cannot be stabilized, it is necessary to monitor the site in order to track the evolution of the sliding processes for hazard assessment purposes. This work is focused on the use of remote sensing techniques (terrestrial photogrammetry, LiDAR) to detect and quantify spatial and temporal distribution of materials on the slope. Dataset includes ground-based and aerial optical images acquired through several field surveys together with an airborne LiDAR points clouds. The Structure From Motion (SFM) technique is used to generate multi-date high-resolution digital elevation models (HRDEMs) in order to quantify volumes changes. Images correlation technique is used to estimate displacements at the surface from images acquired continuously by a fixed camera mounted on the opposite slope and facing the rockslide. The analysis of the terrestrial point clouds indicates two types of dynamics: (i) surficial transport of debris (boulders, tree trunks) which can be identified on daily observations, and (ii) a global deformation of the rockslope along several slip surfaces. The progressive development of the main scarp with velocity of a few cm.month-1 is also monitored. The analysis of an airborne LiDAR point cloud allows to characterize the main discontinuities and the possibility of movement of the global deformation. Finally, an indicator of activity of the slope is proposed from the time serie analysis. The possibility of extension of the rockslide is discussed.

  11. Real-Time C-Band Radar Observations of 1992 Eruption Clouds from Crater Peak, Mount Spurr Volcano, Alaska

    E-print Network

    Rose, William I.

    volcanoes was demonstrated at Mount St. Helens (Harris and others 1981; Harris and Rose, 1983). The heightsReal-Time C-Band Radar Observations of 1992 Eruption Clouds from Crater Peak, Mount Spurr Volcano area. Three significant erup- tions from the Crater Peak vent of Mount Spurr vol- cano (about 80 km

  12. On an 8 km-altitude cloud and precipitation radar echo peak observed during EPIC Paquita Zuidema

    E-print Network

    Zuidema, Paquita

    On an 8 km- altitude cloud and precipitation radar echo peak observed during EPIC Paquita Zuidema is mitigated by the large (80%) percentage of data from EPIC not affected by precipitation below the melting vertical structure observed during EPIC as a function of time of day, easterly wave phase, and "disturbed

  13. Studying Clouds and Aerosols with Lidar Depolarization Ratio and Backscatter Relationships

    E-print Network

    Cho, Hyoun-Myoung

    2012-02-14

    properties of clouds and aerosols. The relationships between depolarization ratio and backscatter allow us to retrieve particle thermodynamic phase and shape and/or orientation of aerosols and clouds. The first part is devoted to the investigation...

  14. Retrieval of vertical profiles of stratus cloud properties from combined oxygen a-band and radar observations

    NASA Astrophysics Data System (ADS)

    Li, S.; Min, Q.

    2012-12-01

    The vertical distribution of cloud properties is important to heating rate profile which is a key part in GCMs. The hydrological circle is also intimately associated with the distribution of clouds. The accurate knowledge of cloud vertical structure is necessary for us to understand the energy balance, dynamic process, hydrological circulation and even the whole climate system. Two independent pieces of information (mean and variance of photon pathlength distribution) are retrievable from a modest resolution Rotating Shadowband Spectrometer (RSS). Millimeter Cloud Radar (MMCR) can provide reflectivity at 45m or 90m vertical resolution. By combining observations of RSS at oxygen a-band and MMCR reflectivity, a new retrieval algorithm is developed to retrieve vertical distribution of cloud properties including cloud droplet effective radius, optical depth and liquid water content. The measurements of RSS at oxygen a-band are used to constrain the co-located radar retrieval by getting the consistency between observation and simulation. The uncertainties of the retrieval algorithm have been evaluated in a sunny day case in which the error induced by the difference between the real atmospheric conditions and that set in the model is relatively small compared to be evaluated in a cloudy day. The combined oxygen a-band and radar retrieval algorithm is applied on two cloudy day cases in ARM SGP site. One case is stratus water cloud and the other one is stratus cloud of which the upper part is mixed phase. The retrieval results have been compared and get a good consistency with other retrieval results which are based on different measurements and algorithm. It's also presented that this algorithm has the potential to investigate the liquid properties in mixed phase cloud.

  15. Internet-Based Software Tools for Analysis and Processing of LIDAR Point Cloud Data via the OpenTopography Portal

    NASA Astrophysics Data System (ADS)

    Nandigam, V.; Crosby, C. J.; Baru, C.; Arrowsmith, R.

    2009-12-01

    LIDAR is an excellent example of the new generation of powerful remote sensing data now available to Earth science researchers. Capable of producing digital elevation models (DEMs) more than an order of magnitude higher resolution than those currently available, LIDAR data allows earth scientists to study the processes that contribute to landscape evolution at resolutions not previously possible, yet essential for their appropriate representation. Along with these high-resolution datasets comes an increase in the volume and complexity of data that the user must efficiently manage and process in order for it to be scientifically useful. Although there are expensive commercial LIDAR software applications available, processing and analysis of these datasets are typically computationally inefficient on the conventional hardware and software that is currently available to most of the Earth science community. We have designed and implemented an Internet-based system, the OpenTopography Portal, that provides integrated access to high-resolution LIDAR data as well as web-based tools for processing of these datasets. By using remote data storage and high performance compute resources, the OpenTopography Portal attempts to simplify data access and standard LIDAR processing tasks for the Earth Science community. The OpenTopography Portal allows users to access massive amounts of raw point cloud LIDAR data as well as a suite of DEM generation tools to enable users to generate custom digital elevation models to best fit their science applications. The Cyberinfrastructure software tools for processing the data are freely available via the portal and conveniently integrated with the data selection in a single user-friendly interface. The ability to run these tools on powerful Cyberinfrastructure resources instead of their own labs provides a huge advantage in terms of performance and compute power. The system also encourages users to explore data processing methods and the variations in algorithm parameters since all of the processing is done remotely and numerous jobs can be submitted in sequence. The web-based software also eliminates the need for users to deal with the hassles and costs associated with software installation and licensing while providing adequate disk space for storage and personal job archival capability. Although currently limited to data access and DEM generation tasks, the OpenTopography system is modular in design and can be modified to accommodate new processing tools as they become available. We are currently exploring implementation of higher-level DEM analysis tasks in OpenTopography, since such processing is often computationally intensive and thus lends itself to utilization of cyberinfrastructure. Products derived from OpenTopography processing are available in a variety of formats ranging from simple Google Earth visualizations of LIDAR-derived hillshades to various GIS-compatible grid formats. To serve community users less interested in data processing, OpenTopography also hosts 1 km^2 digital elevation model tiles as well as Google Earth image overlays for a synoptic view of the data.

  16. Automated Detection of Geomorphic Features in LiDAR Point Clouds of Various Spatial Density

    Microsoft Academic Search

    Peter Dorninger; Balázs Székely; András. Zámolyi; Clemens Nothegger

    2010-01-01

    LiDAR, also referred to as laser scanning, has proved to be an important tool for topographic data acquisition. Terrestrial laser scanning allows for accurate (several millimeter) and high resolution (several centimeter) data acquisition at distances of up to some hundred meters. By contrast, airborne laser scanning allows for acquiring homogeneous data for large areas, albeit with lower accuracy (decimeter) and

  17. Lidar measurements of polar stratospheric clouds during the 1989 airborne Arctic stratospheric expedition

    NASA Technical Reports Server (NTRS)

    Ismail, Syed; Browell, Edward V.

    1991-01-01

    The Airborne Arctic Stratospheric Expedition (AASE) was conducted during January to February 1989 from the Sola Air Station, Norway. As part of this expedition, the NASA Langley Research Center's multiwavelength airborne lidar system was flown on the NASA Ames Research Center's DC-8 aircraft to measure ozone (O3) and aerosol profiles in the region of the polar vortex. The lidar system simultaneously transmitted laser beams at 1064, 603, 311, and 301.5 nm to measure atmospheric scattering, polarization and O3 profiles. Long range flights were made between Stavanger, Norway, and the North Pole, and between 40 deg W and 20 deg E meridians. Eleven flights were made, each flight lasting an average of 10 hours covering about 8000 km. Atmospheric scattering ratios, aerosol polarizations, and aerosol scattering ratio wavelength dependences were derived from the lidar measurements to altitudes above 27 km. The details of the aerosol scattering properties of lidar observations in the IR, VIS, and UV regions are presented along with correlations with the national meteorological Center's temperature profiles.

  18. Validation of POLDER/ADEOS data using a ground-based lidar network: Preliminary results for semi-transparent and cirrus clouds

    NASA Technical Reports Server (NTRS)

    Chepfer, H.; Sauvage, L.; Flamant, P. H.; Pelon, J.; Goloub, P.; Brogniez, G.; spinhirne, J.; Lavorato, M.; Sugimoto, N.

    1998-01-01

    At mid and tropical latitudes, cirrus clouds are present more than 50% of the time in satellites observations. Due to their large spatial and temporal coverage, and associated low temperatures, cirrus clouds have a major influence on the Earth-Ocean-Atmosphere energy balance through their effects on the incoming solar radiation and outgoing infrared radiation. At present the impact of cirrus clouds on climate is well recognized but remains to be asserted more precisely, for their optical and radiative properties are not very well known. In order to understand the effects of cirrus clouds on climate, their optical and radiative characteristics of these clouds need to be determined accurately at different scales in different locations i.e. latitude. Lidars are well suited to observe cirrus clouds, they can detect very thin and semi-transparent layers, and retrieve the clouds geometrical properties i.e. altitude and multilayers, as well as radiative properties i.e. optical depth, backscattering phase functions of ice crystals. Moreover the linear depolarization ratio can give information on the ice crystal shape. In addition, the data collected with an airborne version of POLDER (POLarization and Directionality of Earth Reflectances) instrument have shown that bidirectional polarized measurements can provide information on cirrus cloud microphysical properties (crystal shapes, preferred orientation in space). The spaceborne version of POLDER-1 has been flown on ADEOS-1 platform during 8 months (October 96 - June 97), and the next POLDER-2 instrument will be launched in 2000 on ADEOS-2. The POLDER-1 cloud inversion algorithms are currently under validation. For cirrus clouds, a validation based on comparisons between cloud properties retrieved from POLDER-1 data and cloud properties inferred from a ground-based lidar network is currently under consideration. We present the first results of the validation.

  19. Active optical remote sensing of dense clouds with diffusing light : Early results, present implementations, and the challenges ahead

    SciTech Connect

    Davis, A. B. (Anthony B.); Cahalan, R. F. (Robert F.); Winker, D. M. (David M.)

    2002-01-01

    We survey the rapid progress of 'off-beam' cloud lidar, from inception to validation via laboratory-scale simulations. Cloud observations from ground, aircraft and even space are covered. Finally, we describe future work in this instrument development effort born out of pure theory in the mid-1990s. We foresee a bright future for off-beam lidar which is, in essence, an atmospheric application of the general principles of optical diffuse-light tomography. The physical cloud-boundary information it delivers is, in principle, the same as given from ground or space (upcoming CloudSat mission) obtained by mm-radar. And mm-radar gives some information about internal variability. However, radar reflectivities quite often disagree with optical estimates of cloud base and optical thickness for well-understood reasons. So optical and microwave cloud probes are now considered as complimentary rather then competitive in our efforts to better understand cloud radiative properties in the context of climate research. We are confident that off-beam lidar will be a valuable and, ultimately, cost-effective source of information about cloud processes. In this, we include direct insight into the present issues in large-scale short-wave absorption based on unambiguous geometrical pathlength statistics, a unique capability of off-beam cloud lidar.

  20. Radar Analysis of Precipitation Initiation in Maritime versus Continental Clouds near the Florida Coast: Inferences Concerning the Role of CCN and Giant Nuclei

    E-print Network

    Rutledge, Steven

    Radar Analysis of Precipitation Initiation in Maritime versus Continental Clouds near the Florida with the clouds' maritime or continental characteristics. For this study, the entire National Center, it was assumed that clouds forming over the ocean during onshore flow had maritime characteristics (group 1: low

  1. Features of Point Clouds Synthesized from Multi-View ALOS/PRISM Data and Comparisons with LiDAR Data in Forested Areas

    NASA Technical Reports Server (NTRS)

    Ni, Wenjian; Ranson, Kenneth Jon; Zhang, Zhiyu; Sun, Guoqing

    2014-01-01

    LiDAR waveform data from airborne LiDAR scanners (ALS) e.g. the Land Vegetation and Ice Sensor (LVIS) havebeen successfully used for estimation of forest height and biomass at local scales and have become the preferredremote sensing dataset. However, regional and global applications are limited by the cost of the airborne LiDARdata acquisition and there are no available spaceborne LiDAR systems. Some researchers have demonstrated thepotential for mapping forest height using aerial or spaceborne stereo imagery with very high spatial resolutions.For stereo imageswith global coverage but coarse resolution newanalysis methods need to be used. Unlike mostresearch based on digital surface models, this study concentrated on analyzing the features of point cloud datagenerated from stereo imagery. The synthesizing of point cloud data from multi-view stereo imagery increasedthe point density of the data. The point cloud data over forested areas were analyzed and compared to small footprintLiDAR data and large-footprint LiDAR waveform data. The results showed that the synthesized point clouddata from ALOSPRISM triplets produce vertical distributions similar to LiDAR data and detected the verticalstructure of sparse and non-closed forests at 30mresolution. For dense forest canopies, the canopy could be capturedbut the ground surface could not be seen, so surface elevations from other sourceswould be needed to calculatethe height of the canopy. A canopy height map with 30 m pixels was produced by subtracting nationalelevation dataset (NED) fromthe averaged elevation of synthesized point clouds,which exhibited spatial featuresof roads, forest edges and patches. The linear regression showed that the canopy height map had a good correlationwith RH50 of LVIS data with a slope of 1.04 and R2 of 0.74 indicating that the canopy height derived fromPRISM triplets can be used to estimate forest biomass at 30 m resolution.

  2. New ARM measurements of clouds, aerosols, and the atmospheric state

    NASA Astrophysics Data System (ADS)

    Mather, J. H.; Voyles, J.

    2011-12-01

    The DOE Atmospheric Radiation Measurement (ARM) program has recently enhanced its observational capabilities at its fixed and mobile sites as well as its aerial facility. New capabilities include scanning radars, several types of lidars, an array of aerosol instruments, and in situ cloud probes. All ARM sites have been equipped with dual frequency scanning cloud radars that will provide three-dimensional observations of cloud fields for analysis of cloud field evolution. Sites in Oklahoma, Alaska, and Papua New Guinea have also received scanning centimeter wavelength radars for observing precipitation fields. This combination of radars will provide the means to study the interaction of clouds and precipitation. New lidars include a Raman lidar in Darwin, Australia and High Spectral Resolution Lidars in Barrow and with the second ARM Mobile Facility. Each of these lidars will provide profiles of aerosol extinction while the Raman will also measure profiles of water vapor. ARM has also expanded its capabilities in the realm of aerosol observations. ARM is adding Aerosol Observing Systems to its sites in Darwin and the second mobile facility. These aerosol systems principally provided measurements of aerosol optical properties. Additionally, a new Mobile Aerosol Observing System has been developed that includes a variety of instruments to provide information about aerosol chemistry and size distributions. Many of these aerosol instruments are also available for the ARM Aerial Facility. The Aerial Facility also now includes a variety of cloud probes for measuring size distribution and water content. The new array of ARM instruments is intended to build upon the existing ARM capabilities to better study the interactions among aerosol, clouds, and precipitation. Data from these instruments are now available and development of advanced data products is underway.

  3. New ARM Measurements of Clouds, Aerosols, and the Atmospheric State

    NASA Astrophysics Data System (ADS)

    Mather, J.

    2012-04-01

    The DOE Atmospheric Radiation Measurement (ARM) program has recently enhanced its observational capabilities at its fixed and mobile sites as well as its aerial facility. New capabilities include scanning radars, several types of lidars, an array of aerosol instruments, and in situ cloud probes. All ARM sites have been equipped with dual frequency scanning cloud radars that will provide three-dimensional observations of cloud fields for analysis of cloud field evolution. Sites in Oklahoma, Alaska, and Papua New Guinea have also received scanning centimeter wavelength radars for observing precipitation fields. This combination of radars will provide the means to study the interaction of clouds and precipitation. New lidars include a Raman lidar in Darwin, Australia and High Spectral Resolution Lidars in Barrow and with the second ARM Mobile Facility. Each of these lidars will provide profiles of aerosol extinction while the Raman will also measure profiles of water vapor. ARM has also expanded its capabilities in the realm of aerosol observations. ARM is adding Aerosol Observing Systems to its sites in Darwin and the second mobile facility. These aerosol systems principally provided measurements of aerosol optical properties. In addition, a new Mobile Aerosol Observing System has been developed that includes a variety of instruments to provide information about aerosol chemistry and size distributions. Many of these aerosol instruments are also available for the ARM Aerial Facility. The Aerial Facility also now includes a variety of cloud probes for measuring size distribution and water content. The new array of ARM instruments is intended to build upon the existing ARM capabilities to better study the interactions among aerosol, clouds, and precipitation. Data from these instruments are now available and development of advanced data products is underway.

  4. Fast, Space Qualified 3000 V Modulator for a Cloud Profiling Radar

    NASA Technical Reports Server (NTRS)

    Haque, Inam U.; Harvey, Wayne; Duong, Johnny; Packard, Roy; Ispirian, Julie

    2005-01-01

    Cloudsat's Cloud Profiling Radar (CPR) delivers a 2 kW of RF pulse using an extended Interaction Klystron (EIK). 'To drive such an EIK, it was necessary to develop a -16.3 kV High Voltage Power Supply (HVPS) and a Focus Electrode Modulator (FEM), floating at Cathode potential to turn the EIK's Beam on and off -45V to -3kV with respect to the Cathode. This paper describes the design approach for the FEM and its performance at EM and Flight Configuration. In author's opinion it a simple but universal approach which allow designer to achieve greater flexibility and freedom in designing high swinging space qualifiable FEM.

  5. Doppler-radar observation of the evolution of downdrafts in convective clouds

    NASA Technical Reports Server (NTRS)

    Motallebi, N.

    1982-01-01

    A detailed analysis of the 20 July 1977 thunderstorm complex which formed and evolve over the South Park region in Central Colorado is presented. The storm was extensively analyzed using multiple Doppler radar and surface mesonet data, developed within an environment having very weak wind shear. The storm owed its intensification to the strength of the downdraft, which was nearly coincident with the region where the cloud had grown. The noteworthy features of this storm were its motion to the right of the cloud-level winds, its multicellular nature and discrete propagation, its north-south orientation, and its relatively large storm size and high reflectivity factor (55 dBZ). This scenario accounts for the observed mesoscale and cloud-scale event. A line of convergence was generated at the interface between the easterly upslope winds and westerly winds. During stage II, the convergence line subsequently propagated down the slopes of the Mosquito Range, and was the main forcing mechanism for the development of updraft on the west flank of the storm. The formation of downdraft on the eastern side of updraft blacked surface inflow, and created a detectable gust front. As the original downdraft intensified, the accumulation of evaporatively-chilled air caused the intensification of the mesohigh, which likely destroyed the earlier convergence line and created a stronger convergence line to the east, which forced up-lifting of the moist, westerly inflow and caused the formation of updraft to the east. An organized downdraft circulation, apparently maintained by precipitation drag and evaporational cooling, was responsible in sustaining a well-defined gust front. The storm attained its highest intensity as a consequence of merging with a neighboring cloud. The interaction of downdrafts or gust fronts from two intense cells appeared to be the primary mechanism of this merging process as suggested by Simpson et al. (1980). The merging process coincided with more rain than occurred in unmerged echoes.

  6. Dynamics of Dust Particles Released from Oort Cloud Comets and Their Contribution to Radar Meteors

    NASA Technical Reports Server (NTRS)

    Nesvorny, David; Vokrouhlicky, David; Pokorny, Petr; Janches, Diego

    2012-01-01

    The Oort Cloud Comets (OCCs), exemplified by the Great Comet of 1997 (Hale-Bopp), are occasional visitors from the heatless periphery of the solar system. Previous works hypothesized that a great majority of OCCs must physically disrupt after one or two passages through the inner solar system, where strong thermal gradients can cause phase transitions or volatile pressure buildup. Here we study the fate of small debris particles produced by OCC disruptions to determine whether the imprints of a hypothetical population of OCC meteoroids can be found in the existing meteor radar data. We find that OCC particles with diameters D < or approx. 10 microns are blown out from the solar system by radiation pressure, while those with D > or approx. 1 mm have a very low Earth-impact probability. The intermediate particle sizes, D approx. 100 microns represent a sweet spot. About 1% of these particles orbitally evolve by Poynting-Robertson drag to reach orbits with semimajor axis a approx. 1 AU. They are expected to produce meteors with radiants near the apex of the Earth s orbital motion. We find that the model distributions of their impact speeds and orbits provide a good match to radar observations of apex meteors, except for the eccentricity distribution, which is more skewed toward e approx. 1 in our model. Finally, we propose an explanation for the long-standing problem in meteor science related to the relative strength of apex and helion/antihelion sources. As we show in detail, the observed trend, with the apex meteors being more prominent in observations of highly sensitive radars, can be related to orbital dynamics of particles released on the long-period orbits.

  7. DYNAMICS OF DUST PARTICLES RELEASED FROM OORT CLOUD COMETS AND THEIR CONTRIBUTION TO RADAR METEORS

    SciTech Connect

    Nesvorny, David; Vokrouhlicky, David; Pokorny, Petr [Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Janches, Diego [Space Weather Laboratory, Code 674, GSFC/NASA, Greenbelt, MD 20771 (United States)

    2011-12-10

    The Oort Cloud Comets (OCCs), exemplified by the Great Comet of 1997 (Hale-Bopp), are occasional visitors from the heatless periphery of the solar system. Previous works hypothesized that a great majority of OCCs must physically disrupt after one or two passages through the inner solar system, where strong thermal gradients can cause phase transitions or volatile pressure buildup. Here we study the fate of small debris particles produced by OCC disruptions to determine whether the imprints of a hypothetical population of OCC meteoroids can be found in the existing meteor radar data. We find that OCC particles with diameters D {approx}< 10 {mu}m are blown out from the solar system by radiation pressure, while those with D {approx}> 1 mm have a very low Earth-impact probability. The intermediate particle sizes, D {approx} 100 {mu}m, represent a sweet spot. About 1% of these particles orbitally evolve by Poynting-Robertson drag to reach orbits with semimajor axis a {approx} 1 AU. They are expected to produce meteors with radiants near the apex of Earth's orbital motion. We find that the model distributions of their impact speeds and orbits provide a good match to radar observations of apex meteors, except for the eccentricity distribution, which is more skewed toward e {approx} 1 in our model. Finally, we propose an explanation for the long-standing problem in meteor science related to the relative strength of apex and helion/antihelion sources. As we show in detail, the observed trend, with the apex meteors being more prominent in observations of highly sensitive radars, can be related to orbital dynamics of particles released on the long-period orbits.

  8. Evaluation of cloud microphysics schemes in simulations of a winter storm using radar and radiometer measurements

    NASA Astrophysics Data System (ADS)

    Han, Mei; Braun, Scott A.; Matsui, Toshihisa; Williams, Christopher R.

    2013-02-01

    observations from a space-borne radiometer and a ground-based precipitation profiling radar, the impact of cloud microphysics schemes in the WRF model on the simulation of microwave brightness temperature (Tb), radar reflectivity, and Doppler velocity (Vdop) is studied for a winter storm in California. The unique assumptions of particles size distributions, number concentrations, shapes, and fall speeds in different microphysics schemes are implemented into a satellite simulator and customized calculations for the radar are performed to ensure consistent representation of precipitation properties between the microphysics schemes and the radiative transfer models.Simulations with four different schemes in the WRF model, including the Goddard scheme (GSFC), the WRF single-moment 6-class scheme (WSM6), the Thompson scheme (THOM), and the Morrison double-moment scheme (MORR), are compared directly with measurements from the sensors. Results show large variations in the simulated radiative properties. General biases of ~20 K or larger are found in (polarization-corrected) Tb, which is linked to an overestimate of the precipitating ice aloft. The simulated reflectivity with THOM appears to agree well with the observations, while high biases of ~5-10 dBZ are found in GSFC, WSM6 and MORR. Peak reflectivity in MORR exceeds other schemes. These biases are attributable to the snow intercept parameters or the snow number concentrations. Simulated Vdop values based on GSFC agree with the observations well, while other schemes appear to have a ~1 m s-1 high bias in the ice layer. In the rain layer, the model representations of Doppler velocity vary at different sites.

  9. Evaluation of Cloud Microphysics in JMA-NHM Simulations Using Bin or Bulk Microphysical Schemes through Comparison with Cloud Radar Observations

    NASA Technical Reports Server (NTRS)

    Iguchi, Takamichi; Nakajima, Teruyuki; Khain, Alexander P.; Saito, Kazuo; Takemura, Toshihiko; Okamoto, Hajime; Nishizawa, Tomoaki; Tao, Wei-Kuo

    2012-01-01

    Numerical weather prediction (NWP) simulations using the Japan Meteorological Agency NonhydrostaticModel (JMA-NHM) are conducted for three precipitation events observed by shipborne or spaceborneW-band cloud radars. Spectral bin and single-moment bulk cloud microphysics schemes are employed separatelyfor an intercomparative study. A radar product simulator that is compatible with both microphysicsschemes is developed to enable a direct comparison between simulation and observation with respect to theequivalent radar reflectivity factor Ze, Doppler velocity (DV), and path-integrated attenuation (PIA). Ingeneral, the bin model simulation shows better agreement with the observed data than the bulk modelsimulation. The correction of the terminal fall velocities of snowflakes using those of hail further improves theresult of the bin model simulation. The results indicate that there are substantial uncertainties in the masssizeand sizeterminal fall velocity relations of snowflakes or in the calculation of terminal fall velocity of snowaloft. For the bulk microphysics, the overestimation of Ze is observed as a result of a significant predominanceof snow over cloud ice due to substantial deposition growth directly to snow. The DV comparison shows thata correction for the fall velocity of hydrometeors considering a change of particle size should be introducedeven in single-moment bulk cloud microphysics.

  10. Doppler Radar and Cloud-to-Ground Lightning Observations of a Severe Outbreak of Tropical Cyclone Tornadoes

    NASA Technical Reports Server (NTRS)

    McCaul, Eugene W., Jr.; Buechler, Dennis; Cammarata, Michael; Arnold, James E. (Technical Monitor)

    2002-01-01

    Data from a single WSR-88D Doppler radar and the National Lightning Detection Network are used to examine the characteristics of the convective storms that produced a severe tornado outbreak within Tropical Storm Beryl's remnants on 16 August 1994. Comparison of the radar data with reports of tornadoes suggests that only 12 cells produced the 29 tornadoes that were documented in Georgia and the Carolinas on that date. Six of these cells spawned multiple tornadoes, and the radar data confirm the presence of miniature supercells. One of the cells was identifiable on radar for 11 hours, spawning tornadoes over a time period spanning approximately 6.5 hours. Time-height analyses of the three strongest supercells are presented in order to document storm kinematic structure and evolution. These Beryl mini-supercells were comparable in radar-observed intensity but much more persistent than other tropical cyclone-spawned tornadic cells documented thus far with Doppler radars. Cloud-to-ground lightning data are also examined for all the tornadic cells in this severe swarm-type tornado outbreak. These data show many of the characteristics of previously reported heavy-precipitation supercells. Lightning rates were weak to moderate, even in the more intense supercells, and in all the storms the lightning flashes were almost entirely negative in polarity. No lightning at all was detected in some of the single-tornado storms. In the stronger cells, there is some evidence that lightning rates can decrease during tornadogenesis, as has been documented before in some midlatitude tornadic storms. A number of the storms spawned tornadoes just after producing their final cloud-to-ground lightning flashes. These findings suggest possible benefits from implementation of observing systems capable of monitoring intracloud as well as cloud-to-ground lightning activity.

  11. Mystery of Polar Inertia-gravity Waves: An Observational Study Combining Lidar, Radar and Airglow Imager at McMurdo/Scott Base (77.8°S, 166.7°E)

    NASA Astrophysics Data System (ADS)

    Chen, C.; Chu, X.; Fong, W.; McDonald, A.; Pautet, P. D.; Taylor, M. J.

    2014-12-01

    Since the start of the McMurdo Fe lidar campaign, large-amplitude (~±30 K), long-period (4 to 9 h) perturbations with upward propagating Inertia Gravity Wave (IGW) signatures are frequently observed in the MLT temperature data. Despite its frequent appearance, such type of wave was neither widely observed, nor well understood in the past, primarily due to a paucity of measurements in Polar Regions. At McMurdo, the simultaneous observations of such waves using lidar, radar and airglow imager can provide their unique 3-D intrinsic wave-propagation properties, which are greatly needed for understanding their sources and potential impacts. This study presents the first coincident observation of IGWs by lidar, radar and airglow imager in the Antarctic mesopause region. On 11 June 2013, coherent wave structures with observed period of ~ 5 h and vertical wavelength of ~20 km were observed in both the Fe lidar temperature and MF radar winds. Derived from hodograph analysis, the wave has a horizontal wavelength of ~1200 km and propagates southward at ~60 m/s. The phase relationship between the temperature and winds is in good agreement with the gravity wave polarization relationship. Similar wave structures were also observed in the airglow keograms. The results of the horizontal propagation information obtained from appropriate filtering and applying a non-linear least-square fit of the keograms are similar to those estimated from the combined lidar-radar hodograph analysis. A Monte Carlo sampling method is used to perform all the non-linear fits of the observations to the linear gravity wave models.

  12. Lidar Remote Sensing

    NASA Technical Reports Server (NTRS)

    McGill, Matthew J.; Starr, David OC. (Technical Monitor)

    2002-01-01

    The laser radar, or lidar (for light detection and ranging) is an important tool for atmospheric studies. Lidar provides a unique and powerful method for unobtrusively profiling aerosols, wind, water vapor, temperature, and other atmospheric parameters. This brief overview of lidar remote sensing is focused on atmospheric applications involving pulsed lasers. The level of technical detail is aimed at the educated non-lidar expert and references are provided for further investigation of specific topics. The article is divided into three main sections. The first describes atmospheric scattering processes and the physics behind laser-atmosphere interactions. The second section highlights some of the primary lidar applications, with brief descriptions of each measurement capability. The third section describes the practical aspects of lidar operation, including the governing equation and operational considerations.

  13. Observations of ice motion changes at the terminus of Hubbard Glacier using co-located ground-based radar interferometer and LiDAR scanning systems (Invited)

    NASA Astrophysics Data System (ADS)

    Wolken, G. J.; Finnegan, D. C.; Sharp, M. J.; LeWinter, A.; Fahnestock, M. A.; Stevens, R.

    2013-12-01

    The tidewater terminus of Hubbard Glacier extends into Disenchantment Bay and currently blocks most of the mouth of Russell Fjord. Recent advances of Hubbard Glacier (1986 and 2002) caused the damming of Russell Fjord, creating one of the largest glacier-dammed lakes on the continent and exposing the community of Yakutat to a host of potential hazards. Detailed observations of the terminus of Hubbard Glacier were conducted during a field campaign in May 2013. Ground-based radar interferometer (GBRI) and ground-based light detection and ranging (LiDAR) scanning systems were deployed to observe changes in ice motion in response to calving events and tidal cycles. GBRI and LiDAR units were co-located and data acquisition was synchronized to maximize data recovery and to aid inter-system comparisons. Observations from ground-based scanners were also compared to meteorological and tidal measurements and to time-lapse photography and satellite data. Both ground-based scanning systems capture ice motion at very high resolution, but each offer specific technical and logistical advantages. The combination of these ground-based remote sensing techniques allows us to quantify high-frequency changes in the velocity and surface deformation at the terminus of Hubbard Glacier and to develop a better understanding of the mechanisms associated with advancing tidewater termini.

  14. Comparison of Cloud Properties from CALIPSO-CloudSat and Geostationary Satellite Data

    NASA Technical Reports Server (NTRS)

    Nguyen, L.; Minnis, P.; Chang, F.; Winker, D.; Sun-Mack, S.; Spangenberg, D.; Austin, R.

    2007-01-01

    Cloud properties are being derived in near-real time from geostationary satellite imager data for a variety of weather and climate applications and research. Assessment of the uncertainties in each of the derived cloud parameters is essential for confident use of the products. Determination of cloud amount, cloud top height, and cloud layering is especially important for using these real -time products for applications such as aircraft icing condition diagnosis and numerical weather prediction model assimilation. Furthermore, the distribution of clouds as a function of altitude has become a central component of efforts to evaluate climate model cloud simulations. Validation of those parameters has been difficult except over limited areas where ground-based active sensors, such as cloud radars or lidars, have been available on a regular basis. Retrievals of cloud properties are sensitive to the surface background, time of day, and the clouds themselves. Thus, it is essential to assess the geostationary satellite retrievals over a variety of locations. The availability of cloud radar data from CloudSat and lidar data from CALIPSO make it possible to perform those assessments over each geostationary domain at 0130 and 1330 LT. In this paper, CloudSat and CALIPSO data are matched with contemporaneous Geostationary Operational Environmental Satellite (GOES), Multi-functional Transport Satellite (MTSAT), and Meteosat-8 data. Unlike comparisons with cloud products derived from A-Train imagers, this study considers comparisons of nadir active sensor data with off-nadir retrievals. These matched data are used to determine the uncertainties in cloud-top heights and cloud amounts derived from the geostationary satellite data using the Clouds and the Earth s Radiant Energy System (CERES) cloud retrieval algorithms. The CERES multi-layer cloud detection method is also evaluated to determine its accuracy and limitations in the off-nadir mode. The results will be useful for constraining the use of the passive retrieval data in models and for improving the accuracy of the retrievals.

  15. Research of the cirrus structure with the polarization lidar: parameters of particle orientation in crystal clouds

    Microsoft Academic Search

    Gennadii G. Matvienko; Ignaty V. Samokhvalov; Bruno V. Kaul

    2004-01-01

    The particles of upper clouds are ice crystals with various sizes and shapes. Under certain conditions they can be oriented in space. This circumstance leads to the significant anisotropy of light in cirrus clouds that should be taken into account when solving problems of radiation propagation through the atmosphere. Acquiring the information on parameters of particle orientation in ensembles of

  16. Integrated framework for retrievals in a networked radar environment: Application to the Mid-latitude Continental Convective Clouds Experiment

    NASA Astrophysics Data System (ADS)

    Hardin, J. C.; Chandrasekar, C. V.; Yoshikawa, E.; Ushio, T.

    2012-12-01

    The Mid-Latitude Continental Convective Clouds Experiment (MC3E), was a joint DOE Atmospheric Radiation Measurement (ARM) and NASA Global Precipitation Measurements (GPM) field campaign that took place from April - June 2011 in Central Oklahoma centered at the ARM Southern Great Plains site. The experiment was a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administration (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign involved a large suite of observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors, and new ARM instrumentation. The overarching goal was to provide the most complete characterization of convective cloud systems, precipitation, and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall retrieval algorithms over land that had never before been available. The experiment consisted of a large number of ground radars, including NASA scanning dual-polarization radar systems (NPOL) at S-band, wind profilers, and a dense network of surface disdrometers. In addition to these special MC3E instruments, there were three networked scanning X-band radar systems, four wind profilers, a C-band scanning radar, a dual-wavelength (Ka/W) scanning cloud radar. There is extensive literature on the retrieval algorithms for precipitation and cloud parameters from single frequency, dual-polarization radar systems. With the cost of instruments such as radars becoming more affordable, multiple radar deployments are becoming more common in special programs, and the MC3E is a text book example of such a deployment. Networked deployments are becoming more common popularized by the CASA program, resulting in networked retrievals which was initially used for attenuation mitigation. Since then Networked retrievals have expanded reach to include retrieval of DSDs from networked X-band or Ku-band radars. All the above retrieval methodologies were for homogeneous, single frequency systems; however the multi frequency nature of the deployment during the MC3E program is the motivation for the integrated formulation presented in this paper. This paper presents a comprehensive integrated retrieval methodology to obtain microphysical retrieval such as the drop size distribution for the complete MC3E network, for the multi frequency radar systems. References Chandrasekar, V., et al. (2010), "The CASA IP Test-bed after 5 Years Operation: Accomplishments, Breakthroughs, Challenges and Lessons Learned.", (2010) Proceedings of the Sixth European Conference on Radar Meteorology and Hydrology. Sibiu, 2012 Jensen, MP, et al.(2011), Midlatitude Continental Convective Clouds Experiment (MC3E). ARM Climate Facility: U.S. Department of Energy. Yoshikawa, Ei-ichi, V Chandrasekar, Tamoo Ushio, and Zen Kawasaki.(2012), "Bayesian Formulation of DSD Retrieval Algorithm for Dual-Polarized X-Band Weather Radar Network." Proceedings of IGARSS 2012. Munich: Proceedings of the IGARSS 2012.

  17. Lidar Ratios for Dust Aerosols Derived From Retrievals of CALIPSO Visible Extinction Profiles Constrained by Optical Depths from MODIS-Aqua and CALIPSO/CloudSat Ocean Surface Reflectance Measurements

    NASA Technical Reports Server (NTRS)

    Young, Stuart A.; Josset, Damien B.; Vaughan, Mark A.

    2010-01-01

    CALIPSO's (Cloud Aerosol Lidar Infrared Pathfinder Satellite Observations) analysis algorithms generally require the use of tabulated values of the lidar ratio in order to retrieve aerosol extinction and optical depth from measured profiles of attenuated backscatter. However, for any given time or location, the lidar ratio for a given aerosol type can differ from the tabulated value. To gain some insight as to the extent of the variability, we here calculate the lidar ratio for dust aerosols using aerosol optical depth constraints from two sources. Daytime measurements are constrained using Level 2, Collection 5, 550-nm aerosol optical depth measurements made over the ocean by the MODIS (Moderate Resolution Imaging Spectroradiometer) on board the Aqua satellite, which flies in formation with CALIPSO. We also retrieve lidar ratios from night-time profiles constrained by aerosol column optical depths obtained by analysis of CALIPSO and CloudSat backscatter signals from the ocean surface.

  18. Evaluation of Passive Multilayer Cloud Detection Using Preliminary CloudSat and CALIPSO Cloud Profiles

    NASA Astrophysics Data System (ADS)

    Minnis, P.; Sun-Mack, S.; Chang, F.; Huang, J.; Nguyen, L.; Ayers, J. K.; Spangenberg, D. A.; Yi, Y.; Trepte, C. R.

    2005-05-01

    During the last few years, several algorithms have been developed to detect and retrieve multilayered clouds using passive satellite data. Assessing these techniques has been difficult due to the need for active sensors such as cloud radars and lidars that can "see" through different layers of clouds. Such sensors have been available only at a few surface sites and on aircraft during field programs. With the launch of the CALIPSO and CloudSat satellites on April 28, 2006, it is now possible to observe multilayered systems all over the globe using collocated cloud radar and lidar data. As part of the A- Train, these new active sensors are also matched in time ad space with passive measurements from the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer - EOS (AMSR-E). The Clouds and the Earth's Radiant Energy System (CERES) has been developing and testing algorithms to detect ice-over-water overlapping cloud systems and to retrieve the cloud liquid path (LWP) and ice water path (IWP) for those systems. One technique uses a combination of the CERES cloud retrieval algorithm applied to MODIS data and a microwave retrieval method applied to AMSR-E data. The combination of a CO2-slicing cloud retireval technique with the CERES algorithms applied to MODIS data (Chang et al., 2005) is used to detect and analyze such overlapped systems that contain thin ice clouds. A third technique uses brightness temperature differences and the CERES algorithms to detect similar overlapped methods. This paper uses preliminary CloudSat and CALIPSO data to begin a global scale assessment of these different methods. The long-term goals are to assess and refine the algorithms to aid the development of an optimal combination of the techniques to better monitor ice 9and liquid water clouds in overlapped conditions.

  19. Evaluation of Passive Multilayer Cloud Detection Using Preliminary CloudSat and CALIPSO Cloud Profiles

    NASA Astrophysics Data System (ADS)

    Minnis, P.; Sun-Mack, S.; Chang, F.; Huang, J.; Nguyen, L.; Ayers, J. K.; Spangenberg, D. A.; Yi, Y.; Trepte, C. R.

    2006-12-01

    During the last few years, several algorithms have been developed to detect and retrieve multilayered clouds using passive satellite data. Assessing these techniques has been difficult due to the need for active sensors such as cloud radars and lidars that can "see" through different layers of clouds. Such sensors have been available only at a few surface sites and on aircraft during field programs. With the launch of the CALIPSO and CloudSat satellites on April 28, 2006, it is now possible to observe multilayered systems all over the globe using collocated cloud radar and lidar data. As part of the A- Train, these new active sensors are also matched in time ad space with passive measurements from the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer - EOS (AMSR-E). The Clouds and the Earth's Radiant Energy System (CERES) has been developing and testing algorithms to detect ice-over-water overlapping cloud systems and to retrieve the cloud liquid path (LWP) and ice water path (IWP) for those systems. One technique uses a combination of the CERES cloud retrieval algorithm applied to MODIS data and a microwave retrieval method applied to AMSR-E data. The combination of a CO2-slicing cloud retireval technique with the CERES algorithms applied to MODIS data (Chang et al., 2005) is used to detect and analyze such overlapped systems that contain thin ice clouds. A third technique uses brightness temperature differences and the CERES algorithms to detect similar overlapped methods. This paper uses preliminary CloudSat and CALIPSO data to begin a global scale assessment of these different methods. The long-term goals are to assess and refine the algorithms to aid the development of an optimal combination of the techniques to better monitor ice 9and liquid water clouds in overlapped conditions.

  20. Validation of aerosol and cloud layer structures from the space-borne lidar CALIOP using a ground-based lidar in Seoul, Korea

    Microsoft Academic Search

    S.-W. Kim; S. Berthier; J.-C. Raut; P. Chazette; F. Dulac; S.-C. Yoon

    2008-01-01

    We present initial validation results of the space-borne lidar CALIOP onboard CALIPSO satellite using coincidental observations from a ground-based lidar in Seoul National University (SNU), Seoul, Korea (37.46° N, 126.95° E). We analyze six selected cases between September 2006 and February 2007, including 3 daytime and 3 night-time observations and covering different types of clear and cloudy atmospheric conditions. Apparent

  1. Cloud Physics Lidar Optical Measurements During the SAFARI-2000 Field Campaign

    NASA Technical Reports Server (NTRS)

    Hlavka, Dennis L.; McGill, Matt; Hart, William D.; Spinhirne, James D.; Starr, David OC. (Technical Monitor)

    2002-01-01

    In this presentation, we will show new optical data processing results from the Cloud Physics War during SAFARI-2000. Retrieved products include aerosol and cloud layer location and identification, layer optical depths, vertical extinction profiles, and extinction-to-backscatter (S) ratios for 532 and 1064 nm. The retrievals will focus on the persistent and smoky planetary boundary layer and occasional elevated aerosol layers found in southern Africa during August and September 2000.

  2. The structure and organization of clouds under suppressed conditions observed by S-band radar during DYNAMO

    NASA Astrophysics Data System (ADS)

    Rowe, A.; Houze, R.

    2013-12-01

    The NCAR S-PolKa dual-polarized Doppler S- and Ka-band radar captured three active periods of the Madden-Julian Oscillation (MJO) during the Dynamics of the MJO (DYNAMO) field project. These three multi-week periods were separated by periods of convectively suppressed conditions. While deep convection and widespread stratiform echo during the active periods were responsible for the majority of the precipitation, a goal of DYNAMO was to investigate the entire cloud population as it evolves from shallow, isolated convection to deep mesoscale systems since this evolution needs to be represented in models predicting the MJO. The S-PolKa radar is sensitive enough to detect non-precipitating clouds at both its wavelengths, and its data therefore can be used to describe the organization and structure of boundary layer clouds during the buildup phase of the MJO. The non-precipitating clouds are seen via Bragg scattering in which the boundaries of small cumulus clouds have signatures referred to as mantle echoes. The Bragg scattering also shows layers of strong water vapor gradient. The small non-precipitating clouds are often organized into lines parallel to the boundary layer wind or wind shear before they begin to precipitate. As soon as S-PolKa indicates the onset of precipitation from a small cloud, Bragg and Rayleigh echoes outline quasi-circular cold pools in the boundary layer surrounding the showers. At times, the cold pools intersect with each other and new convection tends to initiate at the intersection points. This study will document the non-precipitating cloud structures as seen by S-PolKa and describe the steps in the evolution of the boundary layer echoes from lines to cold pools, and hence to the development of the deeper MJO convective population.

  3. Cloud Properties and Radiative Heating Rates for TWP

    DOE Data Explorer

    Comstock, Jennifer

    A cloud properties and radiative heating rates dataset is presented where cloud properties retrieved using lidar and radar observations are input into a radiative transfer model to compute radiative fluxes and heating rates at three ARM sites located in the Tropical Western Pacific (TWP) region. The cloud properties retrieval is a conditional retrieval that applies various retrieval techniques depending on the available data, that is if lidar, radar or both instruments detect cloud. This Combined Remote Sensor Retrieval Algorithm (CombRet) produces vertical profiles of liquid or ice water content (LWC or IWC), droplet effective radius (re), ice crystal generalized effective size (Dge), cloud phase, and cloud boundaries. The algorithm was compared with 3 other independent algorithms to help estimate the uncertainty in the cloud properties, fluxes, and heating rates (Comstock et al. 2013). The dataset is provided at 2 min temporal and 90 m vertical resolution. The current dataset is applied to time periods when the MMCR (Millimeter Cloud Radar) version of the ARSCL (Active Remotely-Sensed Cloud Locations) Value Added Product (VAP) is available. The MERGESONDE VAP is utilized where temperature and humidity profiles are required. Future additions to this dataset will utilize the new KAZR instrument and its associated VAPs.

  4. Cloud Properties and Radiative Heating Rates for TWP

    SciTech Connect

    Comstock, Jennifer

    2013-11-07

    A cloud properties and radiative heating rates dataset is presented where cloud properties retrieved using lidar and radar observations are input into a radiative transfer model to compute radiative fluxes and heating rates at three ARM sites located in the Tropical Western Pacific (TWP) region. The cloud properties retrieval is a conditional retrieval that applies various retrieval techniques depending on the available data, that is if lidar, radar or both instruments detect cloud. This Combined Remote Sensor Retrieval Algorithm (CombRet) produces vertical profiles of liquid or ice water content (LWC or IWC), droplet effective radius (re), ice crystal generalized effective size (Dge), cloud phase, and cloud boundaries. The algorithm was compared with 3 other independent algorithms to help estimate the uncertainty in the cloud properties, fluxes, and heating rates (Comstock et al. 2013). The dataset is provided at 2 min temporal and 90 m vertical resolution. The current dataset is applied to time periods when the MMCR (Millimeter Cloud Radar) version of the ARSCL (Active Remotely-Sensed Cloud Locations) Value Added Product (VAP) is available. The MERGESONDE VAP is utilized where temperature and humidity profiles are required. Future additions to this dataset will utilize the new KAZR instrument and its associated VAPs.

  5. A Ku\\/Ka-dual band reflectarray to emulate a cylindrical reflector for titan cloud precipitation radar and altimeter

    Microsoft Academic Search

    C. Han; S. Hsu; K. Chang; J. Huang

    2007-01-01

    A Ku\\/Ka dual-band reflectarray has been developed as a demonstration model for the next generation of Titan cloud precipitation radar and altimeter (TCPRA). The reflectarray developed is a substitute of a parabolic cylindrical reflector and it is offset-fed by two linear arrays. The antenna has a 50-cm-square aperture and uses two 2-mil thick membranes for both bands enabling transformation into

  6. Simulated KWAJEX Convective Systems Using a 2D and 3D Cloud Resolving Model and Their Comparisons with Radar Observations

    NASA Technical Reports Server (NTRS)

    Shie, Chung-Lin; Tao, Wei-Kuo; Simpson, Joanne

    2003-01-01

    The 1999 Kwajalein Atoll field experiment (KWAJEX), one of several major TRMM (Tropical Rainfall Measuring Mission) field experiments, has successfully obtained a wealth of information and observation data on tropical convective systems over the western Central Pacific region. In this paper, clouds and convective systems that developed during three active periods (Aug 7-12, Aug 17-21, and Aug 29-Sep 13) around Kwajalein Atoll site are simulated using both 2D and 3D Goddard Cumulus Ensemble (GCE) models. Based on numerical results, the clouds and cloud systems are generally unorganized and short lived. These features are validated by radar observations that support the model results. Both the 2D and 3D simulated rainfall amounts and their stratiform contribution as well as the heat, water vapor, and moist static energy budgets are examined for the three convective episodes. Rainfall amounts are quantitatively similar between the two simulations, but the stratiform contribution is considerably larger in the 2D simulation. Regardless of dimension, fo all three cases, the large-scale forcing and net condensation are the two major physical processes that account for the evolution of the budgets with surface latent heat flux and net radiation solar and long-wave radiation)being secondary processes. Quantitative budget differences between 2D and 3D as well as between various episodes will be detailed.Morover, simulated radar signatures and Q1/Q2 fields from the three simulations are compared to each other and with radar and sounding observations.

  7. A Method for the Automatic Detection of Insect Clutter in Doppler-Radar Returns.

    SciTech Connect

    Luke,E.; Kollias, P.; Johnson, K.

    2006-06-12

    The accurate detection and removal of insect clutter from millimeter wavelength cloud radar (MMCR) returns is of high importance to boundary layer cloud research (e.g., Geerts et al., 2005). When only radar Doppler moments are available, it is difficult to produce a reliable screening of insect clutter from cloud returns because their distributions overlap. Hence, screening of MMCR insect clutter has historically involved a laborious manual process of cross-referencing radar moments against measurements from other collocated instruments, such as lidar. Our study looks beyond traditional radar moments to ask whether analysis of recorded Doppler spectra can serve as the basis for reliable, automatic insect clutter screening. We focus on the MMCR operated by the Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program at its Southern Great Plains (SGP) facility in Oklahoma. Here, archiving of full Doppler spectra began in September 2003, and during the warmer months, a pronounced insect presence regularly introduces clutter into boundary layer returns.

  8. Integrated Cloud-Aerosol-Radiation Product using CERES, MODIS, CALIPSO and CloudSat Data

    NASA Technical Reports Server (NTRS)

    Sun-Mack, Sunny; Minnis, Patrick; Chen, Yan; Gibson, Sharon; Yi, Yuhong; Trepte, Qing; Wielicki, Bruce; Kato, Seiji; Winker, Dave

    2007-01-01

    This paper documents the development of the first integrated data set of global vertical profiles of clouds, aerosols, and radiation using the combined NASA A-Train data from the Aqua Clouds and Earth's Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS), Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and CloudSat. As part of this effort, cloud data from the CALIPSO lidar and the CloudSat radar are merged with the integrated column cloud properties from the CERES-MODIS analyses. The active and passive datasets are compared to determine commonalities and differences in order to facilitate the development of a 3- dimensional cloud and aerosol dataset that will then be integrated into the CERES broadband radiance footprint. Preliminary results from the comparisons for April 2007 reveal that the CERES-MODIS global cloud amounts are, on average, 0.14 less and 0.15 greater than those from CALIPSO and CloudSat, respectively. These new data will provide unprecedented ability to test and improve global cloud and aerosol models, to investigate aerosol direct and indirect radiative forcing, and to validate the accuracy of global aerosol, cloud, and radiation data sets especially in polar regions and for multi-layered cloud conditions.

  9. Analysis of Aircraft, Radiosonde and Radar Observations in Cirrus Clouds Observed During FIRE II: The Interactions Between Environmental Structure, Turbulence and Cloud Microphysical Properties

    NASA Technical Reports Server (NTRS)

    Smith, Samantha A.; DelGenio, Anthony D.

    1999-01-01

    Ways to determine the turbulence intensity and the horizontal variability in cirrus clouds have been investigated using FIRE-II aircraft, radiosonde and radar data. Higher turbulence intensities were found within some, but not all, of the neutrally stratified layers. It was also demonstrated that the stability of cirrus layers with high extinction values decrease in time, possibly as a result of radiative destabilization. However, these features could not be directly related to each other in any simple manner. A simple linear relationship was observed between the amount of horizontal variability in the ice water content and its average value. This was also true for the extinction and ice crystal number concentrations. A relationship was also suggested between the variability in cloud depth and the environmental stability across the depth of the cloud layer, which requires further investigation.

  10. Airborne Multiparameter Precipitation Radar (CAMPR) Observation of Wind Fields in Snow Clouds

    NASA Astrophysics Data System (ADS)

    Satoh, Shinsuke; Hanado, Hiroshi; Nakagawa, Katsuhiro; Iguchi, Toshio; Nakamura, Kenji; Yoshizaki, Masanori

    2002-06-01

    The CRL airborne multiparameter precipitation radar (CAMPR-D) is equipped with a dual-beam antenna to measure three-dimensional wind fields in precipitation. This paper describes the methods and related problems of wind-vector calculation, and shows the results of dual-Doppler analysis. The observation data was obtained through the WMO-01 (Winter MCSs Observations over the Japan Sea 2001), the objective of which was to reveal the structure of snow clouds over the Japan Sea. First, the trajectories of the front- and rear-antenna beam were investigated. The results showed that there were some gaps between the two beam footprints due to the speed and direction of the wind relative to the aircraft, and that the front beam did not overlap the rear beam in some regions on the leeward side. The investigation also demonstrated that the data from a flight-information system (POS) consisting of an optical-fiber gyroscope and a differential GPS is effective in removing the aircraft velocity component from the measured Doppler velocity. Finally, some distributions of the wind vectors in the along-track vertical sections are shown. The wind vectors were analyzed using the observation data for linear clouds in the JPCZ (Japan Sea Polar-airmass Convergence Zone). The distributions showed that updrafts were dominant over the sea because of developing convective cells, and that the repetition of updrafts and downdrafts seemed to indicate roll convections. The distributions also showed a common structure of anvil echoes that extended northward or northeastward.

  11. The Australian Antarctic lidar facility

    SciTech Connect

    Klekociuk, A.R.; Morris, R.J.; Yates, P.; Fleming, A.; Murphy, D.J. [Auroral and Space Physics, Kingston, Tasmania (Australia). Antarctic Division; Greet, P.A. [Auroral and Space Physics, Kingston, Tasmania (Australia). Antarctic Division; [Univ. of Tasmania, Hobart, Tasmania (Australia). Inst. for Antarctic and Southern Ocean Studies; Argall, P.S. [Univ. of Adelaide, South Australia (Australia). Dept. of Physics and Mathematical Physics; [Univ. of Western Ontario, London, Ontario (Canada). Dept. of Physics; Vincent, R.A.; Reid, I.M. [Univ. of Adelaide, South Australia (Australia). Dept. of Physics and Mathematical Physics

    1994-12-31

    A high spectral resolution lidar, under development by the Australian Antarctic Division and the University of Adelaide, is described. This instrument will be stationed at Davis, Antarctica (68.6{degree}S, 78.0{degree}E) from early 1996 for the long-term measurement of atmospheric parameters as a function of altitude from the lower stratosphere to the mesopause. The siting of the lidar will allow for data comparison with existing optical, radar and balloon-borne atmospheric studies. Research utilizing the multi-instrument database will be aimed at assessing climatic variability and coupling processes throughout the atmosphere. The lidar transmitter consists of a commercial injection-seeded pulsed ND:YAG laser coupled to a altazimuth mounted Cassegrain telescope with a 1 meter diameter primary mirror. The laser emits at a wavelength of 532 nm with an average power of 30 W. The telescope also serves as the collecting optics for the receiving system. The lidar is switched between transmit and receive modes by a high speed rotating shutter system. The detection system consists of a dual scanning Fabry Perot Spectrometer (FPS) followed by a cooled photomultiplier operated in `photon counting` mode. The received signal is integrated as a function of equivalent range over a bandpass that may be either fixed or scanned in the wavelength domain. Performance simulations for the fixed bandpass operating mode are discussed. These indicate that useful measurements of density and inferred temperature should be achievable for the mesopause region, particularly at night and during twilight. In addition, detection of clouds in the mesosphere during the day appears feasible.

  12. Cloud Radar Observations made during the Rains of EPIC-2001 P.Zuidema,C.Fairall,T.Uttal,I.Djalalova,S.Matrosov

    E-print Network

    Zuidema, Paquita

    Cloud Radar Observations made during the Rains of EPIC-2001 P,as part of the East Pacific Investigation of Climate Processes (EPIC-2001).From September 10 other data on the same clouds,such as optical thicknesses derived from an infrared radiometer. For EPIC

  13. Study of atmospheric parameters measurements using MM-wave radar in synergy with LITE-2

    NASA Technical Reports Server (NTRS)

    Andrawis, Madeleine Y.

    1994-01-01

    The Lidar In-Space Technology Experiment, (LITE), has been developed, designed, and built by NASA Langley Research Center, to be flown on the space shuttle 'Discovery' on September 9, 1994. Lidar, which stands for light detecting and ranging, is a radar system that uses short pulses of laser light instead of radio waves in the case of the common radar. This space-based lidar offers atmospheric measurements of stratospheric and tropospheric aerosols, the planetary boundary layer, cloud top heights, and atmospheric temperature and density in the 10-40 km altitude range. A study is being done on the use, advantages, and limitations of a millimeterwave radar to be utilized in synergy with the Lidar system, for the LITE-2 experiment to be flown on a future space shuttle mission. The lower atmospheric attenuation, compared to infrared and optical frequencies, permits the millimeter-wave signals to penetrate through the clouds and measure multi-layered clouds, cloud thickness, and cloud-base height. These measurements would provide a useful input to radiation computations used in the operational numerical weather prediction models, and for forecasting. High power levels, optimum modulation, data processing, and high antenna gain are used to increase the operating range, while space environment, radar tradeoffs, and power availability are considered. Preliminary, numerical calculations are made, using the specifications of an experimental system constructed at Georgia Tech. The noncoherent 94 GHz millimeter-wave radar system has a pulsed output with peak value of 1 kW. The backscatter cross section of the particles to be measured, that are present in the volume covered by the beam footprint, is also studied.

  14. Comparative classification analysis of post-harvest growth detection from terrestrial LiDAR point clouds in precision agriculture

    NASA Astrophysics Data System (ADS)

    Koenig, Kristina; Höfle, Bernhard; Hämmerle, Martin; Jarmer, Thomas; Siegmann, Bastian; Lilienthal, Holger

    2015-06-01

    In precision agriculture, detailed geoinformation on plant and soil properties plays an important role, e.g., in crop protection or the application of fertilizers. This paper presents a comparative classification analysis for post-harvest growth detection using geometric and radiometric point cloud features of terrestrial laser scanning (TLS) data, considering the local neighborhood of each point. Radiometric correction of the TLS data was performed via an empirical range-correction function derived from a field experiment. Thereafter, the corrected amplitude and local elevation features were explored regarding their importance for classification. For the comparison, tree induction, Na?ve Bayes, and k-Means-derived classifiers were tested for different point densities to distinguish between ground and post-harvest growth. The classification performance was validated against highly detailed RGB reference images and the red edge normalized difference vegetation index (NDVI705), derived from a hyperspectral sensor. Using both geometric and radiometric features, we achieved a precision of 99% with the tree induction. Compared to the reference image classification, the calculated post-harvest growth coverage map reached an accuracy of 80%. RGB and LiDAR-derived coverage showed a polynomial correlation to NDVI705 of degree two with R2 of 0.8 and 0.7, respectively. Larger post-harvest growth patches (>10 × 10 cm) could already be detected by a point density of 2 pts./0.01 m2. The results indicate a high potential of radiometric and geometric LiDAR point cloud features for the identification of post-harvest growth using tree induction classification. The proposed technique can potentially be applied over larger areas using vehicle-mounted scanners.

  15. The Role of Cloud and Precipitation Radars in Convoys and Constellations

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Durden, Stephen L.; Im, Eastwood; Sadowy, Gregory A.

    2013-01-01

    We provide an overview of which benefits a radar, and only a radar, can provide to any constellation of satellites monitoring Earth's atmosphere; which aspects instead are most useful to complement a radar instrument to provide accurate and complete description of the state of the troposphere; and finally which goals can be given a lower priority assuming that other types of sensors will be flying in formation with a radar.

  16. A High Resolution Hydrometer Phase Classifier Based on Analysis of Cloud Radar Doppler Spectra

    Microsoft Academic Search

    Edward Luke; Pavlos Kollias

    2007-01-01

    The lifecycle and radiative properties of clouds are highly sensitive to the phase of their hydrometeors (i.e., liquid or ice). Knowledge of cloud phase is essential for specifying the optical properties of clouds, or else, large errors can be introduced in the calculation of the cloud radiative fluxes. Current parameterizations of cloud water partition in liquid and ice based on

  17. Frequency of tropical precipitating clouds as observed by the Tropical Rainfall Measuring Mission Precipitation Radar and

    E-print Network

    Frequency of tropical precipitating clouds as observed by the Tropical Rainfall Measuring Mission July 2007. [1] Convective clouds in the tropics can be grouped into three categories: shallow clouds with cloud top heights near 2 km above the surface, midlevel congestus clouds with tops near the 0°C level

  18. Validation of CALIPSO Lidar Observations Using Data From the NASA Langley Airborne High Spectral Resolution Lidar

    Microsoft Academic Search

    C. A. Hostetler; J. W. Hair; Z. Liu; R. A. Ferrare; D. B. Harper; A. L. Cook; M. A. Vaughan; C. R. Trepte; D. M. Winker

    2006-01-01

    This paper focuses on comparisons of data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft with data acquired with the NASA Langley Airborne High Spectral Resolution Lidar (HSRL). A series of aircraft validation flights was initiated on 14 June 2006, soon after the completion of the CALIPSO satellite

  19. Optical Properties of Aerosols - Clouds - Contrails and Water Vapor Mixing Ratio By Lidar From The Jungfraujoch Research Station (3580 M Asl)

    NASA Astrophysics Data System (ADS)

    Larchevêque, G.; Balin, I.; Quaglia, P.; Nessler, R.; Simeonov, V.; van den Bergh, H.; Calpini, B.

    The direct (as suspended particles) and indirect (by induced clouds/contrails) effects of the aerosols on the Sun - Earth system radiation budget is still remaining an important climate topic [IPCC, Report 2001]. The indirect effect is very complex (difficult to be quantified) is influencing also the hydrological cycle (evaporation/precipitation rates) [Ramamathan et al.,Science, Dec 2001]. Thus more space-time resolved measure- ments in order to retrieve optical, chemical and microphysical properties of aerosols are still needed. In this context the implementation of a new multi-wavelength (Ra- man) lidar system at the Jungfraujoch station (3580m ASL, January 2000) allows the retrieval of aerosols backscatter and extinction coefficients at 355nm, 532nm and 1064nm with a vertical resolution around 100 to 200m in the upper troposphere and lower stratosphere (UTLS). Depolarization studies (e.g. clouds) are also performed detecting parallel and cross polarization signals at 532nm. The water vapor mixing ratio retrieval is based on the spontaneous Raman shifts (387nm for N2 and 408nm for H2O) of the 355nm. This work will focus mainly on the results obtained using a 20cm diameter Newtonian configuration telescope. The Jungfraujoch lidar is part of the EARLINET European lidar network for aerosols measurements and is operating since May 2000. Furthermore these range resolved lidar measurements are bringing new insights in some of the column density measurements performed by FTIR or Sun photometry, or the passive microwave measurements, and are also linked to the direct "in situ" aerosols measurements.

  20. Extracting Mobile Objects in Images Using a Velodyne LIDAR Point Cloud

    NASA Astrophysics Data System (ADS)

    Vallet, B.; Xiao, W.; Brédif, M.

    2015-03-01

    This paper presents a full pipeline to extract mobile objects in images based on a simultaneous laser acquisition with a Velodyne scanner. The point cloud is first analysed to extract mobile objects in 3D. This is done using Dempster-Shafer theory and it results in weights telling for each points if it corresponds to a mobile object, a fixed object or if no decision can be made based on the data (unknown). These weights are projected in an image acquired simultaneously and used to segment the image between the mobile and the static part of the scene.

  1. Inter-seasonal surface deformations of an active rock glacier imaged with radar and lidar remote sensing; Turtmann valley, Switzerland

    NASA Astrophysics Data System (ADS)

    Kos, Andrew; Buchli, Thomas; Strozzi, Tazio; Springman, Sarah

    2013-04-01

    Inter-seasonal changes in surface deformation were imaged using a portable radar interferometer and terrestrial laser scanner during a series of three campaigns that took place in autumn 2011, summer 2012 and autumn 2012 on a rock glacier located in the Turtmann valley, Switzerland. Satellite radar interferometry (ERS 1 & 2, CosmoSkymed) indicate that accelerated downslope movement of the rock glacier commenced during the 1990s. Due to signal decorrelation associated with the satellite repeat pass time interval, continuous ground-based radar interferometry measurements were undertaken. Results show that the rock glacier accelerated significantly in Summer (Vmax = 6.0cm/25hrs), probably in response to the condition of the subsurface hydrology (e.g. post-peak spring snow melt and/or infiltration of rainfall). In autumn, the displacement velocity was reduced (Vmax = 2.0cm/25hrs). A one year surface difference of the glacier topography, derived from terrestrial laser scanning, provided insight into the rock glacier kinematics. Ongoing research is aimed at integrating surface displacement results with an extensive borehole monitoring system consisting of inclinometers and temperature sensors.

  2. Assessing global microphysics of warm cloud and light precipitation from active sensors

    NASA Astrophysics Data System (ADS)

    Sato, K.; Okamoto, H.; Ishimoto, H.

    2014-12-01

    Synergetic uses of radar and lidar are potentially useful for deriving vertically resolved microphysical properties of aerosols, clouds and precipitation. The Earth Cloud, Aerosol and Radiation Explorer (EarthCARE) mission, carrying Doppler Cloud Profiling Radar (CPR) and a high spectral resolution lidar (ATLID) is expected to bring qualitative estimate of these quantities together with cloud vertical velocity information. The standard algorithm for warm cloud microphysics developed under the first Jaxa EarthCARE Research announcement enables us to tackle bimodal problems on retrieving size and number concentration of cloud particles and drizzles coexisting within a vertical grid, by practically incorporating backward Monte-Carlo calculations of the polarized lidar returns in the inversion scheme with sufficient processing speed adapted to global data. In the present study, the developed algorithm has been applied to similar set of measurements from A-train, especially from CloudSat and CALIPSO, to derive global views of cloud and drizzle vertical distributions to be further used to examine the performance of their parameterizations in climate and cloud resolving models.

  3. History of remote-sensing methods in meteorology, cloud physics and nowcasting in Slovakia over the period 1965-1990

    NASA Astrophysics Data System (ADS)

    Podhorský, Dušan; Guba, Peter

    2014-03-01

    A brief overview of building the radar and satellite meteorology in Slovakia over the period 1965-1990 and application of dispatching locators of PAR, SRE and RSR types for studying the evolution of convective cells is given. Further, the conception and implementation of a meteorological radar network in Slovakia, the algorithms for recognition of clouds and phenomena related to the parameters of radioecho are reviewed. The development of a new laser radar (LIDAR) and the application of a prototype meteorological radar with the TESLA RM-3 controlled polarizer are described.

  4. Study of wind retrieval from space-borne infrared coherent lidar in cloudy atmosphere.

    NASA Astrophysics Data System (ADS)

    Baron, Philippe; Ishii, Shoken; Mizutani, Kohei; Okamoto, Kozo; Ochiai, Satoshi

    2015-04-01

    Future spaceborne tropospheric wind missions using infrared coherent lidar are currently being studied in Japan and in the United States [1,2]. The line-of-sight wind velocity is retrieved from the Doppler shift frequency of the signal returned by aerosol particles. However a large percentage (70-80%) of the measured single-shot intensity profiles are expected to be contaminated by clouds [3]. A large number of cloud contaminated profiles (>40%) will be characterized by a cloud-top signal intensity stronger than the aerosol signal by a factor of one order of magnitude, and by a strong attenuation of the signal backscattered from below the clouds. Profiles including more than one cloud layer are also expected. This work is a simulation study dealing with the impacts of clouds on wind retrieval. We focus on the three following points: 1) definition of an algorithm for optimizing the wind retrieval from the cloud-top signal, 2) assessment of the clouds impact on the measurement performance and, 3) definition of a method for averaging the measurements before the retrieval. The retrieval simulations are conducted considering the instrumental characteristics selected for the Japanese study: wavelength at 2 µm, PRF of 30 Hz, pulse power of 0.125 mJ and platform altitude between 200-400 km. Liquid and ice clouds are considered. The analysis uses data from atmospheric models and statistics of cloud effects derived from CALIPSO measurements such as in [3]. A special focus is put on the average method of the measurements before retrieval. Good retrievals in the mid-upper troposphere implie the average of measured single-range power spectra over large horizontal (100 km) and vertical (1 km) ranges. Large differences of signal intensities due to the presence of clouds and the clouds non-uniform distribution have to be taken into account when averaging the data to optimize the measurement performances. References: [1] S. Ishii, T. Iwasaki, M. Sato, R. Oki, K. Okamoto, T. Ishibashi, P. Baron, and T. Nishizawa: Future Doppler lidar wind measurement from space in Japan, Proc. of SPIE Vol. 8529, 2012 [2] D. Wu, J. Tang, Z. Liu, and Y. Hu: Simulation of coherent doppler wind lidar measurement from space based on CALIPSO lidar global aerosol observations. Journal of Quantitative Spectroscopy and Radiative Transfer, 122(0), 79-86, 2013 [3] G.D Emmitt: CFLOS and cloud statistics from satellite and their impact on future space-based Doppler Wind Lidar development. Symposium on Recent Developments in Atmospheric Applications of Radar and Lidar, 2008

  5. On the camparability of cloud fractions derived from whole sky imager and ceilometer data

    SciTech Connect

    Rodriguez, D.

    1998-01-30

    The Atmospheric Radiation Measurement (ARM) Program`s most heavily instrumented site is its central facility in Lamont, OK. With respect to cloud observations, the instrumentation included a whole sky imager, ceilometers, lidar, millimeter cloud radar, microwave profilers, and radiosondes. Data from three of these instrument--the Whole Sky Imager (WSI), Belfort Laser Ceilometer (BLC) and Micropulse Lidar (MPL)-- are used in this study primarily to investigate the utility of using ceilometers, now strategically emplaced at four additional locations along the perimeter of the site.

  6. Correction to ``Remote sensing of three-dimensional inhomogeneous cirrus clouds using satellite and mm-wave cloud radar data''

    E-print Network

    Takano, Yoshihide

    Correction to ``Remote sensing of three-dimensional inhomogeneous cirrus clouds using satellite Meteorology and Atmospheric Dynamics: Remote sensing; 9900 Corrections [1] In the paper ``Remote sensing and Structure: Cloud physics and chemistry; 3359 Meteorology and Atmospheric Dynamics: Radiative processes; 3360

  7. Thin and thick cloud top height retrieval algorithm with the Infrared Camera and LIDAR of the JEM-EUSO Space Mission

    NASA Astrophysics Data System (ADS)

    Sáez-Cano, G.; Morales de los Ríos, J. A.; del Peral, L.; Neronov, A.; Wada, S.; Rodríguez Frías, M. D.

    2015-03-01

    The origin of cosmic rays have remained a mistery for more than a century. JEM-EUSO is a pioneer space-based telescope that will be located at the International Space Station (ISS) and its aim is to detect Ultra High Energy Cosmic Rays (UHECR) and Extremely High Energy Cosmic Rays (EHECR) by observing the atmosphere. Unlike ground-based telescopes, JEM-EUSO will observe from upwards, and therefore, for a properly UHECR reconstruction under cloudy conditions, a key element of JEM-EUSO is an Atmospheric Monitoring System (AMS). This AMS consists of a space qualified bi-spectral Infrared Camera, that will provide the cloud coverage and cloud top height in the JEM-EUSO Field of View (FoV) and a LIDAR, that will measure the atmospheric optical depth in the direction it has been shot. In this paper we will explain the effects of clouds for the determination of the UHECR arrival direction. Moreover, since the cloud top height retrieval is crucial to analyze the UHECR and EHECR events under cloudy conditions, the retrieval algorithm that fulfills the technical requierements of the Infrared Camera of JEM-EUSO to reconstruct the cloud top height is presently reported.

  8. Using Voxelized Point-Cloud Forest Reconstructions from Ground-Based Full-Waveform Lidar to Retrieve Leaf Area Index and Foliage Profiles

    NASA Astrophysics Data System (ADS)

    Yang, X.; Strahler, A. H.; Schaaf, C.; Li, Z.; Yao, T.; Zhao, F.; Wang, Z.; Woodcock, C. E.; Jupp, D.; Culvenor, D.; Newnham, G.; Lovell, J.

    2012-12-01

    This study presents a new methodology to directly retrieve two important biophysical parameters, Leaf Area Index (LAI; m^2) and Foliage Area Volume Density (FAVD; m^2 LAI/m^3 volume) profiles through the voxelization of point-cloud forest reconstructions from multiple ground-based full-waveform Echidna® lidar scans. Previous studies have verified that estimates of LAI and FAVD made from single EVI scans, using azimuth-averaged gap probability with zenith angle (Jupp et al. 2009; Zhao et al. 2011), agree well with those of traditional hemispherical photos and LAI-2000 measurements. Strahler et al. (2008) and Yang et al. (2012) established a paradigm for the 3-D reconstruction of forest stands using a full-waveform, ground-based, scanning lidar by merging point clouds constructed from overlapping EVI scans, thereby allowing virtual direct representation of forest biomass. Classification procedures (Yang et al. 2012), based on the shape of the laser pulse returned to the instrument, can separate trunk from foliage scattering events. Volumetric datasets are produced by properly assigning attributes, such as gap probability, apparent reflectance, and volume associated with the laser pulse footprint at the observed range, to the foliage scattering events in the reconstructed point cloud. Leaf angle distribution is accommodated with a simple model based on gap probability with zenith angle as observed in individual scans of the stand. Clumping occurring at scales coarser than elemental volumes associated with scattering events is observed directly and therefore does not require parametric correction. For validation, comparisons are made between LAI and FAVD profiles retrieved directly from the voxelized 3-D forest reconstructions and those observed from airborne and field measurements. The voxelized 3-D forest reconstructions derived from EVI point clouds provide a pathway to estimate "ground truth" FAVD, LAI, and above-ground biomass without destructive sampling. These virtual measurements will be very helpful in validating retrieval algorithms for LAI and above-ground biomass using large-footprint spaceborne or airborne lidar systems, thus facilitating large-area inventories. Due to nature of the ground-based instrument, the measurements are highly repeatable and easy to obtain. The enhanced characterization of leaf area spatial distribution within the forest stand possible from EVI is of interest to both land biogeoscientists who require bulk vegetation biomass measures and to atmospheric biogeoscientists, who require information on surface roughness, photosynthesis, and respiration processes. Moreover, the EVI can be deployed to monitor disturbance and deforestation detected by optical sensors, such as MODIS or Landsat, to provide better calibration of the type and nature of change. This research was supported by the National Science Foundation under grant DBI-0923389.

  9. Full-Time, Eye-Safe Cloud and Aerosol Lidar Observation at Atmospheric Radiation Measurement Program Sites: Instruments and Data Analysis

    NASA Technical Reports Server (NTRS)

    Campbell, James R.; Hlavka, Dennis L.; Welton, Ellsworth J.; Flynn, Connor J.; Turner, David D.; Spinhirne, James D.; Scott, V. Stanley, III; Hwang, I. H.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Atmospheric radiative forcing, surface radiation budget, and top of the atmosphere radiance interpretation involves a knowledge of the vertical height structure of overlying cloud and aerosol layers. During the last decade, the U.S. Department of Energy through I the Atmospheric Radiation Measurement (ARM) program has constructed four long- term atmospheric observing sites in strategic climate regimes (north central Oklahoma, In Barrow. Alaska, and Nauru and Manus Islands in the tropical western Pacific). Micro Pulse Lidar (MPL) systems provide continuous, autonomous observation of all significant atmospheric cloud and aerosol at each of the central ARM facilities. Systems are compact and transmitted pulses are eye-safe. Eye-safety is achieved by expanding relatively low-powered outgoing Pulse energy through a shared, coaxial transmit/receive telescope. ARM NIPL system specifications, and specific unit optical designs are discussed. Data normalization and calibration techniques are presented. A multiple cloud boundary detection algorithm is also described. These techniques in tandem represent an operational value added processing package used to produce normalized data products for Cloud and aerosol research and the historical ARM data archive.

  10. SAR and LIDAR fusion: experiments and applications

    NASA Astrophysics Data System (ADS)

    Edwards, Matthew C.; Zaugg, Evan C.; Bradley, Joshua P.; Bowden, Ryan D.

    2013-05-01

    In recent years ARTEMIS, Inc. has developed a series of compact, versatile Synthetic Aperture Radar (SAR) systems which have been operated on a variety of small manned and unmanned aircraft. The multi-frequency-band SlimSAR has demonstrated a variety of capabilities including maritime and littoral target detection, ground moving target indication, polarimetry, interferometry, change detection, and foliage penetration. ARTEMIS also continues to build upon the radar's capabilities through fusion with other sensors, such as electro-optical and infrared camera gimbals and light detection and ranging (LIDAR) devices. In this paper we focus on experiments and applications employing SAR and LIDAR fusion. LIDAR is similar to radar in that it transmits a signal which, after being reflected or scattered by a target area, is recorded by the sensor. The differences are that a LIDAR uses a laser as a transmitter and optical sensors as a receiver, and the wavelengths used exhibit a very different scattering phenomenology than the microwaves used in radar, making SAR and LIDAR good complementary technologies. LIDAR is used in many applications including agriculture, archeology, geo-science, and surveying. Some typical data products include digital elevation maps of a target area and features and shapes extracted from the data. A set of experiments conducted to demonstrate the fusion of SAR and LIDAR data include a LIDAR DEM used in accurately processing the SAR data of a high relief area (mountainous, urban). Also, feature extraction is used in improving geolocation accuracy of the SAR and LIDAR data.

  11. Regional cloud characteristics over the tropical northwestern Pacific as revealed by Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar and TRMM Microwave Imager

    Microsoft Academic Search

    Myung-Sook Park; Yong-Sang Choi; Chang-Hoi Ho; Chung-Hsiung Sui; Seon Ki Park; Myoung-Hwan Ahn

    2007-01-01

    The present study investigates regional cloud characteristics over the tropical northwestern Pacific using Tropical Rainfall Measuring Mission (TRMM) data sets such as rain rate, radar reflectivity, and passive microwave radiometer polarization corrected temperature (PCT). In particular, the tropical northwestern Pacific is divided into two surface rain maxima regions: the South China Sea (SCS) and the Philippine Sea (PS). The TRMM

  12. Eleventh ARM Science Team Meeting Proceedings, Atlanta, Georgia, March 19-23, 2001 Radar-based Retrievals of Cloud Properties in the Arctic

    E-print Network

    Shupe, Matthew

    Eleventh ARM Science Team Meeting Proceedings, Atlanta, Georgia, March 19-23, 2001 1 Radar Radiation Measurement (ARM) program Cloud and Radiation Testbed (CART) sites, all techniques discussed here can be applied to measurements taken at the different ARM sites. Briefly summarized here

  13. New Visualization Techniques to Analyze Ultra-High Resolution Three- and Four-Dimensional Airborne and Tripod LiDAR Point-Cloud Data

    NASA Astrophysics Data System (ADS)

    Kreylos, O.; Bawden, G. W.; Kellogg, L. H.

    2007-12-01

    In the context of the UC~Davis W. M. Keck Center for Active Visualization in the Earth Sciences (KeckCAVES, http://www.keckcaves.org), we are developing an immersive visualization application to display and interact with very large (billions of points) three- and four-dimensional point-position datasets, such that point groups from repeated airborne and ground based Light Detection And Ranging (LiDAR) surveys can be selected, measured, and analyzed for quality control and land surface change detection. One of the difficulties of analyzing dense 3D and 4D point-cloud data is that there are few software packages that can display and analyze the data at full resolution and in the natural 3D perspective in which it was collected. We developed an octree-based, multiresolution, point-set data representation that allows very large point cloud datasets to be displayed at the frame rates required to create immersion (between 60 Hz and 120 Hz). Data inside an observer's region of interest is shown in full detail, whereas data outside the field of view or far away from the observer is shown at reduced resolution to provide context. Users can navigate LiDAR data sets and accurately select related point groups in two or more point sets by sweeping space using 3D input devices provided by immersive display environments such as CAVEs. Users can then guide the software in deriving positional information from point groups to compute displacements between surveys, or to extract survey measurements. This software runs on UNIX-like operating systems and can be used on laptop or desktop computers, 3D display systems such as Geowalls, and in fully immersive environments such as CAVEs. It is available for download from http://www.keckcaves.org. Examples of the wide range of applications of the software for airborne and Tripod LiDAR (T-LiDAR) include: 1)~visualization of airborne LiDAR data from the southern San Andreas Fault; 2)~quality control assessment of ground based T-LiDAR from the March 2006 Ka~Loko Dam breach on Kauai; and 3)~4D T-LiDAR time-series analysis from the June 2005 Blue Bird Canyon landslide in Laguna Beach, southern California.

  14. A data assimilation experiment of RASTA airborne cloud radar data during HyMeX IOP16

    NASA Astrophysics Data System (ADS)

    Saussereau, Gaël; Caumont, Olivier; Delanoë, Julien

    2015-04-01

    The main goal of HyMeX first special observing period (SOP1), which took place from 5 September to 5 November 2012, was to document the heavy precipitation events and flash floods that regularly affect the north-western Mediterranean coastal areas. In the two-month campaign, around twenty rainfall events were documented in France, Italy, and Spain. Among the instrumental platforms that were deployed during SOP1, the Falcon 20 of the Safire unit (http://www.safire.fr/) made numerous flights in storm systems so as to document their thermodynamic, microphysical, and dynamical properties. In particular, the RASTA cloud radar (http://rali.projet.latmos.ipsl.fr/) was aboard this aircraft. This radar measures vertical profiles of reflectivity and Doppler velocity above and below the aircraft. This unique instrument thus allows us to document the microphysical properties and the speed of wind and hydrometeors in the clouds, quasi-continuously in time and at a 60-m vertical resolution. For this field campaign, a special version of the numerical weather prediction (NWP) Arome system was developed to cover the whole north-western Mediterranean basin. This version, called Arome-WMed, ran in real time during the SOP in order to, notably, schedule the airborne operations, especially in storm systems. Like the operational version, Arome-WMed delivers forecasts at a horizontal resolution of 2.5 km with a one-moment microphysical scheme that predicts the evolution of six water species: water vapour, cloud liquid water, rainwater, pristine ice, snow, and graupel. Its three-dimensional variational (3DVar) data assimilation (DA) system ingests every three hours (at 00 UTC, 03 UTC, etc.) numerous observations (radiosoundings, ground automatic weather stations, radar, satellite, GPS, etc.). In order to provide improved initial conditions to Arome-WMed, especially for heavy precipitation events, RASTA data were assimilated in Arome-WMed 3DVar DA system for IOP16 (26 October 2012), to begin with. There were two flights on 26 October and thus RASTA data were assimilated at 2+2 consecutive analysis times (06, 09, 12, and 15 UTC). This task involved a preliminary step to convert the original data into vertical profiles that are suitable for assimilation: the data were averaged to remove noise and match the model's resolution, they were converted to appropriate physical quantities and in a format that is readable by the DA system, etc.). The presentation will show the impact of RASTA data on Arome-WMed analyses and forecasts, both with respect to RASTA data and to independent data (either also assimilated or not).

  15. A comparison between CloudSat and aircraft data for a multilayer, mixed phase cloud system during the Canadian CloudSat-CALIPSO Validation Project

    NASA Astrophysics Data System (ADS)

    Barker, H. W.; Korolev, A. V.; Hudak, D. R.; Strapp, J. W.; Strawbridge, K. B.; Wolde, M.

    2008-04-01

    Reflectivities recorded by the W-band Cloud Profiling Radar (CPR) aboard NASA's CloudSat satellite and some of CloudSat's retrieval products are compared to Ka-band radar reflectivities and in situ cloud properties gathered by instrumentation on the NRC's Convair-580 aircraft. On 20 February 2007, the Convair flew several transects along a 60 nautical mile stretch of CloudSat's afternoon ground track over southern Quebec. On one of the transects it was well within CloudSat's radar's footprint while in situ sampling a mixed phase boundary layer cloud. A cirrus cloud was also sampled before and after overpass. Air temperature and humidity profiles from ECMWF reanalyses, as employed in CloudSat's retrieval stream, agree very well with those measured by the Convair. The boundary layer cloud was clearly visible, to the eye and lidar, and dominated the region's solar radiation budget. It was, however, often below or near the Ka-band's distance-dependent minimum detectable signal. In situ samples at overpass revealed it to be composed primarily of small, supercooled droplets at the south end and increasingly intermixed with ice northward. Convair and CloudSat CPR reflectivities for the low cloud agree well, but while CloudSat properly ascribed it as overcast, mixed phase, and mostly liquid near the south end, its estimates of liquid water content LWC (and visible extinction coefficient ?) and droplet effective radii are too small and large, respectively. The cirrus consisted largely of irregular crystals with typical effective radii ˜150 ?m. While both CPR reflectivities agree nicely, CloudSat's estimates of crystal number concentrations are too large by a factor of 5. Nevertheless, distributions of ice water content and ? deduced from in situ data agree quite well with values retrieved from CloudSat algorithms.

  16. Lidar Remote Sensing for Industry and Environment Monitoring

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N. (Editor); Itabe, Toshikazu (Editor); Sugimoto, Nobuo (Editor)

    2000-01-01

    Contents include the following: 1. Keynote paper: Overview of lidar technology for industrial and environmental monitoring in Japan. 2. lidar technology I: NASA's future active remote sensing mission for earth science. Geometrical detector consideration s in laser sensing application (invited paper). 3. Lidar technology II: High-power femtosecond light strings as novel atmospheric probes (invited paper). Design of a compact high-sensitivity aerosol profiling lidar. 4. Lasers for lidars: High-energy 2 microns laser for multiple lidar applications. New submount requirement of conductively cooled laser diodes for lidar applications. 5. Tropospheric aerosols and clouds I: Lidar monitoring of clouds and aerosols at the facility for atmospheric remote sensing (invited paper). Measurement of asian dust by using multiwavelength lidar. Global monitoring of clouds and aerosols using a network of micropulse lidar systems. 6. Troposphere aerosols and clouds II: Scanning lidar measurements of marine aerosol fields at a coastal site in Hawaii. 7. Tropospheric aerosols and clouds III: Formation of ice cloud from asian dust particles in the upper troposphere. Atmospheric boundary layer observation by ground-based lidar at KMITL, Thailand (13 deg N, 100 deg. E). 8. Boundary layer, urban pollution: Studies of the spatial correlation between urban aerosols and local traffic congestion using a slant angle scanning on the research vessel Mirai. 9. Middle atmosphere: Lidar-observed arctic PSC's over Svalbard (invited paper). Sodium temperature lidar measurements of the mesopause region over Syowa Station. 10. Differential absorption lidar (dIAL) and DOAS: Airborne UV DIAL measurements of ozone and aerosols (invited paper). Measurement of water vapor, surface ozone, and ethylene using differential absorption lidar. 12. Space lidar I: Lightweight lidar telescopes for space applications (invited paper). Coherent lidar development for Doppler wind measurement from the International Space Station. 13. Space lidar II: Using coherent Doppler lidar to estimate river discharge. 14. Poster session: Lidar technology, optics for lidar. Laser for lidar. Middle atmosphere observations. Tropospheric observations (aerosols, clouds). Boundary layer, urban pollution. Differential absorption lidar. Doppler lidar. and Space lidar.

  17. A study of cloud and drizzle properties in the Azores using Doppler Radar spectra

    SciTech Connect

    Luke, E.; Remillard, J.; Kollias, P.

    2010-03-15

    Understanding the onset of coalescence in warm clouds is key in our effort to improve cloud representation in numerical models. Coalescence acts at small scales, and its study requires detailed high-resolution dynamical and microphysical measurements from a comprehensive suite of instruments over a wide range of environmental conditions (e.g., aerosol loading). The first AMF is currently in its second year of a two-year deployment at Graciosa Island in the Azores, offering the opportunity to collect a long data set from a stable land-based platform in a marine stratocumulus regime. In this study, recorded WACR Doppler spectra are used to characterize the properties of Doppler spectra from warm clouds with and without drizzle, and from drizzle only, in an effort to observe the transition (onset) to precipitation in clouds. A retrieval technique that decomposes observed Doppler spectra into their cloud and/or drizzle components is applied in order to quantify drizzle growth.

  18. Particle aggregation in volcanic clouds from the 2009 eruption of Redoubt Volcano, Alaska: Observations of Doppler weather radar, satellite images and tephra-fall deposits

    NASA Astrophysics Data System (ADS)

    Schneider, D. J.; Wallace, K. L.; Mastin, L. G.

    2012-12-01

    The combined use of weather radar and thermal infrared satellite images provides complementary evidence that can be used to observe and interpret tephra-fall processes. Radar is ideal for characterizing coarse-grained tephra in the eruption column and proximal cloud, while thermal infrared satellite data are better able to characterize the fine-grained distal volcanic cloud. We present observations of radar, satellite images, and character of the tephra-fall deposits from the 2009 eruption of Redoubt Volcano, Alaska. Accretionary tephra-ice pellets (up to 9 mm in diameter) comprised of fine-grained ash (less than 63 micron diameter) were abundant in the many of the proximal tephra-fall deposits. The eruption column and proximal cloud from seventeen explosive events were observed using the MiniMax-250C (MM-250C) volcano-monitoring Doppler weather radar located 80 km from the vent. Radar reflectivity and radial Doppler velocity measurements were made of the column, every 70-90 seconds at a vertical resolution of about 2 km. Radar reflectivity is highly dependent upon particle size and to a lesser extent, concentration. At 80 km distance, the minimum detectable particle diameter for the MM-250C was about 0.2 mm for a mass concentration of 100 g/m3. Thus, the radar was able to observe the aggregate pellets, and not the fine-grained ash. Most of the explosive events were characterized by high radar reflectivity values of 50-60 dBZ in the central core of the eruption column and proximal cloud, which we interpret to be related to the rapid growth of accretionary tephra-ice pellets. Tephra-fall deposits extended for distances of several hundred kilometers and mapped to a minimum mass density of 10 g/m2. However, the MM-250C radar data were only able to observe the dispersed cloud for tens of kilometers from the source, which was well within the 1000 g/m2 isomass contour. Fine-grained ash was prematurely removed from the eruption cloud in proximal locations due to aggregate formation. The relative lack of fine-grained ash may account for the poor thermal infrared brightness temperature signals observed in satellite images for many of the distal volcanic clouds from the 2009 eruption, and possibly from the 1989-90 eruption as well. Time-series of radial Doppler velocity images documented the transition from turbulent mixing in the column to larger scale entrainment within the proximal cloud. Large scale entrainment begins to develop within minutes of eruption onset. Most of the eruption clouds from the explosive events reached the stratosphere, but the large scale entrainment appears to be better developed in the tropospheric portion of the cloud.

  19. Time-Integrated Radar Echo Tops as a Measure of Cloud Seeding Effects

    Microsoft Academic Search

    Guy G. Goyer

    1975-01-01

    Radar echo tops of individual cells, integrated over their duration above 7.6 km, are used to define an overall storm magnitude, a growth factor after seeding, and an average seeding rate. The growth factor is then plotted as a function of the average seeding rate for 23 seeded cells and 23 randomly selected non-seeded cells. The results show an appreciable

  20. On the Feasibility of Precisely Measuring the Properties of a Precipitating Cloud with a Weather Radar 

    E-print Network

    Runnels, R.C.

    1967-01-01

    of the liquid-water content by means of this equation. The version of the continuity equation developed in this study represents an improvement over forms used previously. The new version accounts for the downward development of a radar echo at speeds faster...

  1. Large-scale variations in ozone and polar stratospheric clouds measured with airborne lidar during formation of the 1987 ozone hole over Antarctica

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Poole, Lamont R.; Mccormick, M. Patrick; Ismail, Syed; Butler, Carolyn F.; Kooi, Susan A.; Szedlmayer, Margaret M.; Jones, Rod; Krueger, Arlin J.; Tuck, Adrian

    1988-01-01

    A joint field experiment between NASA and NOAA was conducted during August to September 1987 to obtain in situ and remote measurements of key gases and aerosols from aircraft platforms during the formation of the ozone (O3) hole over Antarctica. The ER-2 (advanced U-2) and DC-8 aircraft from the NASA Ames Research Center were used in this field experiment. The NASA Langley Research Center's airborne differential absorption lidar (DIAL) system was operated from the DC-8 to obtain profiles of O3 and polar stratospheric clouds in the lower stratosphere during long-range flights over Antarctica from August 28 to September 29, 1987. The airborne DIAL system was configured to transmit simultaneously four laser wavelengths (301, 311, 622, and 1064 nm) above the DC-8 for DIAL measurements of O3 profiles between 11 to 20 km ASL (geometric altitude above sea level) and multiple wavelength aerosol backscatter measurements between 11 to 24 km ASL. A total of 13 DC-8 flights were made over Antarctica with 2 flights reaching the South Pole. Polar stratospheric clouds (PSC's) were detected in multiple thin layers in the 11 to 21 km ASL altitude range with each layer having a typical thickness of less than 1 km. Two types of PSC's were found based on aerosol backscattering ratios: predominantly water ice clouds (type 2) and clouds with scattering characteristics consistent with binary solid nitric acid/water clouds (type 1). Large-scale cross sections of O3 distributions were obtained. The data provides additional information about a potentially important transport mechanism that may influence the O3 budget inside the vortex. There is also some evidence that strong low pressure systems in the troposphere are associated with regions of lower stratospheric O3. This paper discusses the spatial and temporal variations of O3 inside and outside the polar vortex region during the development of the O3 hole and relates these data to other measurements obtained during this field experiment.

  2. Cloud Thickness from Offbeam Returns (THOR) Validation Campaign on NASA's P3B Over the ARM/SGP

    NASA Technical Reports Server (NTRS)

    Cahalan, R. F.; Kolasinski, J.; McGill, M.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Physical thickness of a cloud layer, sometimes multiple cloud layers, is a crucial controller of solar heating of the Earth- atmosphere system, which drives the convective processes that produce storm systems. Yet clouds of average optical thickness are opaque to conventional lidar, so their thickness is well estimated only by combining a lidar above and another below cloud, or a radar and lidar on the same side, dual facilities not widely available. Here we report initial observations of a new airborne multiple field of view lidar, capable of determining physical thickness of cloud layers from time signatures of off-beam returns from a I kHz micropulse lidar at 540 rim. For a single layer, the time delay of light returning from the outer diffuse halo of light surrounding the beam entry point, relative to the time delay at beam center, determines the cloud physical thickness. The delay combined with the pulse stretch gives the optical thickness. This halo method requires cloud optical thickness exceeding 2, and improves with cloud thickness, thus complimenting conventional lidar, which cannot penetrate thick clouds. Results are presented from March 25, 2002, when THOR flew a butterfly pattern over the ARM site at 8.3 km, above a thin ice cloud at 5 km, and a thick boundary-layer stratus deck with top at 1.3 km, as shown by THOR channel 1, and a base at about 0.3 km as shown by the ground-based MPL. Additional information is included in the original extended abstract.

  3. Constraining mass-diameter relations from hydrometeor images and cloud radar reflectivities in tropical continental and oceanic convective anvils

    NASA Astrophysics Data System (ADS)

    Fontaine, E.; Schwarzenboeck, A.; Delanoë, J.; Wobrock, W.; Leroy, D.; Dupuy, R.; Gourbeyre, C.; Protat, A.

    2014-10-01

    In this study the density of ice hydrometeors in tropical clouds is derived from a combined analysis of particle images from 2-D-array probes and associated reflectivities measured with a Doppler cloud radar on the same research aircraft. Usually, the mass-diameter m(D) relationship is formulated as a power law with two unknown coefficients (pre-factor, exponent) that need to be constrained from complementary information on hydrometeors, where absolute ice density measurement methods do not apply. Here, at first an extended theoretical study of numerous hydrometeor shapes simulated in 3-D and arbitrarily projected on a 2-D plan allowed to constrain the exponent ?of the m(D) relationship from the exponent ? of the surface-diameterS(D)relationship, which is likewise written as a power law. Since S(D) always can be determined for real data from 2-D optical array probes or other particle imagers, the evolution of the m(D) exponent can be calculated. After that, the pre-factor ? of m(D) is constrained from theoretical simulations of the radar reflectivities matching the measured reflectivities along the aircraft trajectory. The study was performed as part of the Megha-Tropiques satellite project, where two types of mesoscale convective systems (MCS) were investigated: (i) above the African continent and (ii) above the Indian Ocean. For the two data sets, two parameterizations are derived to calculate the vertical variability of m(D) coefficients ? and ? as a function of the temperature. Originally calculated (with T-matrix) and also subsequently parameterized m(D) relationships from this study are compared to other methods (from literature) of calculating m(D) in tropical convection. The significant benefit of using variable m(D) relations instead of a single m(D) relationship is demonstrated from the impact of all these m(D) relations on Z-CWC (Condensed Water Content) and Z-CWC-T-fitted parameterizations.

  4. Constraining mass-diameter relations from hydrometeor images and cloud radar reflectivities in tropical continental and oceanic convective anvils

    NASA Astrophysics Data System (ADS)

    Fontaine, E.; Schwarzenboeck, A.; Delanoë, J.; Wobrock, W.; Leroy, D.; Dupuy, R.; Protat, A.

    2014-01-01

    In this study the density of hydrometeors in tropical clouds is derived from a combined analysis of particle images from 2-D-array probes and associated reflectivities measured with a Doppler cloud radar on the same research aircraft. The mass-diameter m(D) relationship is expressed as a power law with two unknown coefficients (pre-factor, exponent) that need to be constrained from complementary information on hydrometeors, where absolute ice density measurement methods do not apply. Here, at first an extended theoretical study of numerous hydrometeor shapes simulated in 3-D and arbitrarily projected on a 2-D plane allowed to constrain the temporal evolution of the exponent of the mass-diameter relationship with that of the exponent of the surface-diameter relationship that is measured by the 2-D-array probes. The pre-factor is then constrained from theoretical simulations of the radar reflectivities matching the measured reflectivities along the aircraft trajectory. The study has been performed as part of the Megha-Tropiques satellite project, where two types of mesoscale convective systems (MCS) have been investigated: (i) above the African Continent and (ii) above the Indian Ocean. In general, both mass-diameter coefficients (pre-factor and exponent) decrease with decreasing temperature, the decrease is more pronounced for oceanic MCS. The condensed water contents (CWC) calculated from particle size distributions (PSD) and m(D) also decrease with altitude while the concentrations of the hydrometeors increase with altitude. The calculated values of CWC are largest for continental MCS.

  5. An Intercomparison Between Radar Reflectivity and the IR Cloud Classification Technique for the TOGA-COARE Area

    NASA Technical Reports Server (NTRS)

    Carvalho, L. M. V.; Rickenbach, T.

    1999-01-01

    Satellite infrared (IR) and visible (VIS) images from the Tropical Ocean Global Atmosphere - Coupled Ocean Atmosphere Response Experiment (TOGA-COARE) experiment are investigated through the use of Clustering Analysis. The clusters are obtained from the values of IR and VIS counts and the local variance for both channels. The clustering procedure is based on the standardized histogram of each variable obtained from 179 pairs of images. A new approach to classify high clouds using only IR and the clustering technique is proposed. This method allows the separation of the enhanced convection in two main classes: convective tops, more closely related to the most active core of the storm, and convective systems, which produce regions of merged, thick anvil clouds. The resulting classification of different portions of cloudiness is compared to the radar reflectivity field for intensive events. Convective Systems and Convective Tops are followed during their life cycle using the IR clustering method. The areal coverage of precipitation and features related to convective and stratiform rain is obtained from the radar for each stage of the evolving Mesoscale Convective Systems (MCS). In order to compare the IR clustering method with a simple threshold technique, two IR thresholds (Tir) were used to identify different portions of cloudiness, Tir=240K which roughly defines the extent of all cloudiness associated with the MCS, and Tir=220K which indicates the presence of deep convection. It is shown that the IR clustering technique can be used as a simple alternative to identify the actual portion of convective and stratiform rainfall.

  6. Coherent Doppler lidar for automated space vehicle rendezvous, stationkeeping and capture

    Microsoft Academic Search

    James A. Bilbro

    1991-01-01

    The inherent spatial resolution of laser radar makes ladar or lidar an attractive candidate for Automated Rendezvous and Capture application. Previous applications were based on incoherent lidar techniques, requiring retro-reflectors on the target vehicle. Technology improvements (reduced size, no cryogenic cooling requirement) have greatly enhanced the construction of coherent lidar systems. Coherent lidar permits the acquisition of non-cooperative targets at

  7. Using Continuous Ground-Based Radar and Lidar Measurements for Evaluating the Representation of Clouds in Four Operational Models

    E-print Network

    Protat, Alain

    and Climate Research, Melbourne, Australia c LATMOS-IPSL, CNRS/INSU, Ve´lizy, France d Meteorology Department, University of Reading, Reading, United Kingdom e LATMOS-IPSL, CNRS/INSU, Paris, France f European Centre

  8. Global Ice Cloud Climatological Properties and Radiative Effects Based on Cloudsat and Calipso Measurements and Radiative Transfer Modelling

    NASA Astrophysics Data System (ADS)

    Hong, Y.; Liu, G.

    2014-12-01

    Ice clouds play an important role in Earth radiation balance by reflecting solar and absorbing thermal radiation, which is expressed as albedo and greenhouse effects, which cause significant differential atmospheric heating and cooling in both horizontal and vertical directions. Two co-orbital sensors, the CloudSat radar and the CALIPSO lidar, provide global profiles for the first time of atmospheric ice clouds. A combination of radar and lidar is useful for examining clouds of varying optical depth, as the radar excels in probing optically thick clouds while the lidar is better suited to the thin clouds. With these joint measurements from the CloudSat radar and the CALIPSO lidar, ice cloud climotological properties are studied and radiative effects are calculated for with a wide range of optical depth using libRadtran, a model package for radiative transfer. Ice cloud climatological studies show that the global mean optical depth and effective radius are around 4 and 48 ?m, respectively. Mean ice water path is approximately 110 g m-2for all measurements. Their occurrence frequencies and ice mass amount distributions do not just depend on seasons, but also rely on the optical depth values. Meanwhile, ice water content and effective radius show different temperature dependent relationships among the tropics, mid- and high-latitudes. Geographical variations of ice cloud forcing are investigated to discover where warming/cooling by ice cloud occurs, and how these effects are modulated by seasonal and regional variations. Vertical heating rate profiles are also studied to reveal heating/cooling structures for cases such as mid-latitude summer. Meanwhile, ice cloud forcing is calculated as a function of optical depth. Past studies have established in general that thin and high cirrus warm the earth system due to the greenhouse effect, whereas thicker ice clouds are cooling because of stronger solar albedo effect. However, the whole spectrum of ice cloud forcing have yet to be studied quantitatively. This study attempts to find thresholds where ice clouds change from a net warming to a net cooling effect.

  9. Multifractal Analyses and Simulations of the Anisotropic 2D Structure of Cloud Fields from ARM's mm-Radars using Semi-Discrete Wavelet Transforms

    NASA Astrophysics Data System (ADS)

    Davis, A. B.; Clothiaux, E. E.; Marshak, A.

    2001-05-01

    To support research on climate using GCMs, it is important to quantify -and eventually predict- the effects of 3D radiative transfer caused by clouds in the Earth's atmosphere. It is therefore essential to have robust statistical information on the spatial correlations in cloud systems at all scales at least up to the GCM grid-size. The mm-wavelength cloud radars operated by the DOE's Atmospheric Radiation Measurement (ARM) Program are a prime source of quasi-continuous data on cloud structure in the vertical and horizontal directions for three vastly different climatic regimes: Southern Great Plains, Northern Slopes of Alaska, and Tropical Western Pacific. We have developed a custom 2D wavelet transform to analyze ARM's mm-radar fields allowing for their strong anisotropy. It is actually a Multi-Resolution Analysis (MRA) based on one scaling function and a family of five orthogonal wavelets. This functional basis is generated by tensor products of the well-known binary Haar MRA (vertically) with another one using a ternary generalization of the Haar basis (horizontally). MRAs are very fast order N algorithms but their sparse tree structure in scale-position space is detrimental to statistical analyses. So we have kept the sparse sampling only in the scale parameter and use a continuous sampling in position; the computational cost makes the algorithms order NlogN. A few test cases are analyzed in depth as a preliminary to the systematic processing of ARM's mm-radar archive. We highlight the scale-invariant (fractal) structure of cloud cover where the 2-point correlations tend to be over long ranges in the horizontal (inside cloud layers) and correspondingly short in the vertical (between cloud layers). Higher-order moments are used to characterize the multifractality (intermittency) of clouds. The low-order statistics carry the information needed to validate and/or improve cloud diagnostics in GCM columns while higher-order properties should, in principle, be reproducible by cloud-resolving models. Stochastically simulated clouds obtained by inverse wavelet transformation illustrate these distinctive structural features.

  10. Atmospheric observations during the Arctic Clouds in Summer Experiment (ACSE)

    NASA Astrophysics Data System (ADS)

    Tjernström, Michael; Brooks, Barbara; Brooks, Ian; Johnston, Paul; Persson, Ola; Prytherch, John; Salisbury, Dominic; Sedlar, Joseph; Shupe, Matthew; Sotiropoulou, Georgia; Wolfe, Dan

    2015-04-01

    During the SWERUS-C3 expedition, twice across the Barents, Laptev, Kara and East Siberian Seas, on the icebreaker Oden, the Arctic Clouds in Summer Experiment (ACSE) took extensive atmospheric observations during a three month period. This poster presents the observations and some preliminar results. The first leg, starting in Tromsö, Norway, on 5 July and ending at Barrow, Alaska, on 19 August, moved mostly on the outer shelf, in open water or sea ice at about 50/50; the sea iuce was sometimes quite thick and solid although melting was intense. The second leg, starting out from Barrow on 21 August and ending in Tromsö on 5 October, was mostly in either open water or in the marginal ice zone, and saw the onset of the autumn freeze. During the the entire 3-month period we deployed an extensive set of instruments, including both in-situ observations and surface based remote sensing. The in-situ observations included standard meteorology, clouds and visibility as well as surface fluxes observed by eddy-correlation measurements on a bow mast 20-meter above the surface and incoming radiation; 6-hourly soundings were also launched through the whole expedition. The remote sensing instruments include a W-band Doppler cloud radar, scanning microwave radiometers, a 3D scanning Doppler lidar and a 449MHz wind profiling radar. The cloud radar, one radiometer and the lidar were mounted on stabilized platforms.

  11. Lidar performance analysis

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.

    1994-01-01

    Section 1 details the theory used to build the lidar model, provides results of using the model to evaluate AEOLUS design instrument designs, and provides snapshots of the visual appearance of the coded model. Appendix A contains a Fortran program to calculate various forms of the refractive index structure function. This program was used to determine the refractive index structure function used in the main lidar simulation code. Appendix B contains a memo on the optimization of the lidar telescope geometry for a line-scan geometry. Appendix C contains the code for the main lidar simulation and brief instruction on running the code. Appendix D contains a Fortran code to calculate the maximum permissible exposure for the eye from the ANSI Z136.1-1992 eye safety standards. Appendix E contains a paper on the eye safety analysis of a space-based coherent lidar presented at the 7th Coherent Laser Radar Applications and Technology Conference, Paris, France, 19-23 July 1993.

  12. A Global View of Ice Generation in Supercooled Stratiform Altocumulus Clouds Based on CALIPSO and CloudSat Measurements

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Wang, Z.; Liu, D.

    2008-12-01

    Ice generation in atmospheric clouds is still poorly understood. Supercooled stratiform altocumulus (Ac) clouds represent a simple scenario to study ice generation in clouds. Because radar is more sensitive to large ice crystals than small water droplets in mixed-phase clouds, radar measurements provide a good indication of ice generation in supercooled stratiform Ac clouds. The first year CALIPSO (lidar) and CloudSat (radar) satellite data are analyzed to provide a global view of ice generation in supercooled stratiform Ac clouds. Two distinct ice formation zones, cloud top temperature (CTT) colder or warmer than -18 C, can be identified from the distributions of Ac occurrence in terms of CTT and layer maximum radar reflectivity factor (Zmax). For all latitude ranges, ice crystals are detectable in some of the stratiform Ac clouds when cloud top temperature colder than -10 C, and the Zmax of ice crystals increase with CTT decrease in an similar slope and reach the maximum value ~ -16 C. Ice generation in stratiform Ac with CTT colder than -18 C show significant latitude differences. The contrast of ice generation in these two zones indicate different dominate ice generation mechanisms among them. The ice occurrence and mean ice water path are proved as a function of CTT. Aerosol size and chemical compositions have great impacts on ice formation characteristics, and mineral dust is effective ice nuclei (IN). By separating stratiform Ac in the "dust bel" regions into dusty Ac (affected by dust) and non-dusty Ac, we found strong dust impacts on ice generation in stratiform Ac. For dusty Ac, ice are detected in all clouds when CTT reaches ~ -20 C.

  13. The use of Doppler radar to predict cloud-to-ground lightning

    E-print Network

    Aclin, Keith Andrew

    1995-01-01

    If the National Weather Service could forecast the occurrences of cloud-toground lightning strikes, it would benefit the authorities that are served by the WSR-88Ds. In this thesis I will examine the WSR-88D level 11 archive data from Houston, Texas...

  14. On the Formation and Seasonal Properties of Topical Cirrus Clouds over Amazon Basin (2.89ºS, 59.97ºW): Observations from Lidar, Radiosonde and Satellite instruments.

    NASA Astrophysics Data System (ADS)

    Barbosa, H. M.; Gouveia, D. A.; Barja Gonzalez, B.

    2014-12-01

    Formed mainly by anvil outflow and the remaining part of deep convective clouds after rainfall or in situ in the upper troposphere by synoptic events, high clouds are constantly found in the tropical region. The global cirrus cover has been estimated to be about 20-25% and their occurrence can be more than 70% over the tropics. These clouds have lifetime that can go from hours to a few days, large coverage area and have been recognized as important agents of the climate system as they can signi?cantly alter the radiation balance of the atmosphere. Despite being relatively transparent to solar radiation (optical depth < 3.0), they trap the infrared radiation that would be lost to space, and thus may have a positive radiative forcing. In this paper, we report on tropical cirrus clouds characteristics as measured by a Lidar station operational in the central Amazon (2.89° S 59.97° W) since 2011. An automated algorithm for the detection of cirrus clouds was developed to determine the clouds geometrical properties. The transmittance of the lidar signal was used to derive the cirrus optical depth. The Klett method was used to derive the backscattering coe?cient and to estimate the lidar ratio of the cirrus clouds. Precipitation information by TRMM satellite and wind field by ERA Interim reanalysis from ECMWF were used. As the results from the ?rst two years of measurements (2011-2012), we found that the occurrence of high clouds with base altitude higher than 8 km (temperatures below -20°C) was approximately 71.0% of the total time of observation, varying between about 50% in the dry season (JJA) and about 80% in the wet season (DJF). These all cirrus clouds were classifies as subvisual (?<0.03) approximately 24.2% of times, 40.7% were thin cirrus (0.030.3). The average values of the cirrus base and top altitudes were 12.4±2.4km and 14.3±2.2km, respectively. They were found at temperatures down to ?90°C they reside most frequently near the tropopause. The mean diurnal cycle of the frequency and altitude, during both summer and winter, indicate anvil outflow to be the most important generation mechanism. The mean lidar ratio was 20.0±6.8sr, indicating a mixed composition of thick plate and long column ice crystals. The behavior of these quantities with respect to temperature was analyzed.

  15. Scientific aspects of the Earth clouds, Aerosols, and Radiation Explorer (EarthCARE) mission

    NASA Astrophysics Data System (ADS)

    Donovan, D. P.; Barker, H. W.; Hogan, R. J.; Wehr, T.; Eisinger, M.; Lajas, D.; Lefebvre, A.

    2013-05-01

    In recent years remote sensing of cloud, aerosol, precipitation, and radiation has benefited greatly from simultaneous application of multiple sensors. For example, combinations of passive radiometers with active sensors such as lidar or radar have proved to be invaluable for their ability to retrieve profiles of cloud macrophysical and microphysical properties. This is amply illustrated by results from both surface sites, such as the US-DoE's ARM installations, and sensors aboard A-train satellites; namely CloudSat, CALIPSO, and Terra. The Earth Clouds, Aerosols, and Radiation Explorer (EarthCARE) mission, a combined ESA/JAXA endeavor set for launch in 2015, has been designed to host active and passive sensors on a single low-Earth orbit satellite and thus retrieve, through synergistic use of data, the most comprehensive global survey of the vertical structure cloud, aerosol precipitation, and radiation. The mission consists of a cloud-profiling radar, a high-spectral resolution cloud/aerosol lidar, a passive imager, and a threeview broadband radiometer (BBR) covering both longwave and shortwave bands. The mission will deliver cloud, aerosol and radiation products focusing on horizontal scales ranging from 1 km to 10 km at a vertical grid-spacing of 0.1 km.

  16. Towards quantifying mesoscale flows in the troposphere using Raman lidar and Sondes

    NASA Technical Reports Server (NTRS)

    Demoz, B.; Starr, D.; Evans, K.; Whiteman, D.; Melfi, S.; Turner, D.; Ferrare, R.; Goldsmith, J.; Schwemmer, G.; Cadirola, M.

    1998-01-01

    Water vapor plays an important role in the energetics of the boundary layer processes which in turn play a key role in regulating regional and global climate. It plays a primary role in Earth's hydrological cycle, in radiation balance as a direct absorber of infrared radiation, and in atmospheric circulation as a latent heat energy source, as well as in determining cloud development and atmospheric stability. Water vapor concentration, expressed as a mass mixing ratio (g kg(exp -l)), is conserved in all meteorological processes except condensation and evaporation. This property makes it an ideal choice for studying many of the atmosphere's dynamic features. Raman scattering measurements from lidar also allow retrieval of water vapor mixing ratio profiles at high temporal and vertical resolution. Raman lidars sense water vapor to altitudes not achievable with towers and surface systems, sample the atmosphere at much higher temporal resolution than radiosondes or satellites, and do not require strong vertical gradients or turbulent fluctuations in temperature that is required by acoustic sounders and radars. Analysis of highly-resolved water vapor profiles are used here to characterize two important mesoscale flows: thunderstorm outflows and a cold front passage. The data were obtained at the Atmospheric Radiation Measurement Site (CART) by the groundbased Department of Energy/Sandia National Laboratories lidar (CART Raman lidar or CARL) and Goddard Space Flight Center Scanning Raman Lidar (SRL). A detailed discussion of the SRL and CARL performance during the IOPs is given by others in this meeting.

  17. Oceanic Lidar

    NASA Technical Reports Server (NTRS)

    Carder, K. L. (editor)

    1981-01-01

    Instrument concepts which measure ocean temperature, chlorophyll, sediment and Gelbstoffe concentrations in three dimensions on a quantitative, quasi-synoptic basis were considered. Coastal zone color scanner chlorophyll imagery, laser stimulated Raman temperaure and fluorescence spectroscopy, existing airborne Lidar and laser fluorosensing instruments, and their accuracies in quantifying concentrations of chlorophyll, suspended sediments and Gelbstoffe are presented. Lidar applications to phytoplankton dynamics and photochemistry, Lidar radiative transfer and signal interpretation, and Lidar technology are discussed.

  18. Effects of Clouds on Cross-Atmospheric Radiative Flux Divergence: Case Studies in Different Cloud Conditions

    NASA Astrophysics Data System (ADS)

    Ghate, V. P.; Miller, M. A.

    2013-12-01

    Clouds have a profound effect on the amount of radiation absorbed across the atmospheric column. The amount of absorption mainly depends on the location and type of the clouds, the albedo of the surface and profile of water vapor mixing ratio in the atmospheric column. In this study we have used the data collected during the deployment of Atmospheric Radiation Measurement (ARM)'s first Mobile Facility (AMF#1) at the island of Graciosa in the North Atlantic and at the Niamey, Niger to assess the impact of different cloud types on the cross-atmospheric radiative flux divergence. The cloud structure was retrieved using the data collected by a vertically pointing w-band cloud radar, a micro-pulse lidar, laser ceilometer among other instruments. The profiles of temperature, moisture and winds were measured by balloon borne radiosondes. The radiation at the surface were measured by broadband radiometers, while the radiation at the top of the atmosphere were measured by the Geostationary Earth Radiation Budget (GERB) radiometers onboard the Meteosat Second Generation (MSG) satellite. Simulations of a 1-dimensional radiative transfer model called as Rapid Radiative Transfer Model (RRTM) having representation of cloud and aerosol properties are made to assess the relative impact of different cloud types and water vapor on spectral bands both in the shortwave and longwave radiation spectrum. Results from four case-studies which had cloud free conditions, single layered stratocumulus clouds, broken shallow cumulus clouds and high level cirrus clouds respectively will be presented.

  19. Using A-Train satellite data to investigate the relationship between cloud ice water path and cloud radiative effects

    NASA Astrophysics Data System (ADS)

    Berry, E. J.; Mace, G. G.

    2013-12-01

    The active remote sensors in the NASA A-Train offer vertically resolved observations of hydrometeors. We obtain ice microphysical properties from the CloudSat 2C-ICE dataset, which combines information from the CloudSat radar and CALIPSO lidar to retrieve the ice water content. We find that the distribution of ice water path (IWP) is highly non-Gaussian. Because of this highly skewed distribution, the cirrus that contribute most to the mean radiative forcing have little to do with the mean of the IWP distribution. Therefore using the mean IWP as a value for comparison with and among global climate models is not a useful evaluation with respect to the radiative effects of cirrus. We also investigate the influence of each instrument (radar and lidar) to the total (combined radar and lidar) IWP distribution, highlighting the IWP sensitivity thresholds for each instrument. In this study we explore the physical relationship of cloud radiative effect (CRE) as a function of the cloud IWP. We find that the net CRE at the top of the atmosphere (TOA) increases with increasing cloud IWP up to 40 g/m^2, then begins to decrease and eventually becomes negative at 200 g/m^2. It remains to be determined whether global climate models show a similar physical relationship between the microphysical quantity of cloud IWP and the net CRE at the TOA. We also find that the solar and infrared CREs are highly dependent on the IWP, changing at different rates with increasing IWP. To evaluate which high clouds are most important in terms of warming the atmosphere, we consider their frequency of occurrence and net CRE at the TOA. We find that cirrus with an IWP around 20 g/m^2 contribute most to the heating of the upper troposphere. This IWP that is most significant to the cloud radiative effects is to be contrasted with the mean of the IWP distribution near 300 g/m^2. While cirrus clouds with IWP near 20 g/m^2 have a small CRE, their frequency of occurrence results in a significant radiative impact. This result highlights the importance of the lidar measurements for observing the full spectrum of ice clouds that are important to the radiation balance.

  20. Inversion of radar backscatter from millimeter wave smoke

    NASA Astrophysics Data System (ADS)

    Perry, Benjamin; Hale, D. J.

    1994-08-01

    This paper describes the results of an analysis of radar backscatter and attenuation data collected during field trials of the MMW Module of the XM56 Large Area Screening Generator. The trials were conducted by Edgewood Research Development and Engineering Center personnel at Dugway Proving Ground in 1989 and 1990, and at Eglin AFB in 1992. The purpose of this analysis was to use inversion techniques, similar to those developed for lidar systems, to translate the radar backscatter data from the XM56 smoke clouds into estimates of cloud concentration, and to compare the resulting concentration estimates with those produces by independent, point sampling nephelometers. Three dimensional cloud concentration profiles have been produced and were found to be consistent with the Pasquill stability category. In addition, the overall correlation between the radar-generated concentration data and those collected using the nephelometers was quite good. Examples of these results are presented for the 1989, long range trials, which allowed characterization of a large volume cloud, and the 1990 and 1992 trials, which were performed over a much shorter range, but provided more useful nephelometer data.

  1. Remote Measurements of Snowfalls in Wakasa Bay, Japan with Airborne Millimeter- wave Imaging Radiometer and Cloud Radar

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Austin, R.; Liu, G. S.; Racette, P. E.

    2004-01-01

    In this paper we explore the application of combined millimeter-wave radar and radiometry to remotely measure snowfall. During January-February of 2003, a field campaign was conducted with the NASA P-3 aircraft in Wakasa Bay, Japan for the validation of the AMSRE microwave radiometer on board the Aqua satellite. Among the suite of instruments-on board the P-3 aircraft were the Millimeter-wave Imaging Radiometer (MIR) from the NASA Goddard Space Flight Center and the 94 GHz Airborne Cloud Radar (ACR) which is co-owned and operated by NASA Jet Propulsion Laboratory/University of Massachusetts. MIR is a total power, across-track scanning radiometer that measures radiation at the frequencies of 89, 150, 183.3 +/- 1, 183.3 +/- 3, 183.3 +/-7, 220, and 340 GHz. The MIR has flown many successful missions since its completion in May 1992. ACR is a newer instrument and flew only a few times prior to the Wakasa Bay deployment. These two instruments which are particularly well suited for the detection of snowfall functioned normally during flights over snowfall and excellent data sets were acquired. On January 14, 28, and 29 flights were conducted over snowfall events. The MIR and ACR detected strong signals during periods of snowfall over ocean and land. Results from the analysis of these concurrent data sets show that (1) the scattering of millimeter-wave radiation as detected by the MIR is strongly correlated with ACR radar reflectivity profiles, and (2) the scattering is highly frequency-dependent, the higher the frequency the stronger the scattering. Additionally, the more transparent channels of the MIR (e.g., 89, 150, and 220 GHz) are found to display ambiguous signatures of snowfall because of their exposure to surface features. Thus, the snowfall detection and retrievals of snowfall parameters, such as the ice water path (IWP) and median mass diameter (D(me)) are best conducted at the more opaque channels near 183.3 GHz and 340 GHz. Retrievals of IWP and D(me) using the MIR measurements at 183.3 and 340 GHZ are currently in progress, and the results will be compared with those derived from the ACR reflectivity profiles. Implication from this comparison will be discussed.

  2. Diagnosis of multilayer clouds using photon path length distributions

    NASA Astrophysics Data System (ADS)

    Li, Siwei; Min, Qilong

    2010-10-01

    Photon path length distribution is sensitive to 3-D cloud structures. A detection method for multilayer clouds has been developed, by utilizing the information of photon path length distribution. The photon path length method estimates photon path length information from the low level, single-layer cloud structure that can be accurately observed by a millimeter-wave cloud radar (MMCR) combined with a micropulse lidar (MPL). As multiple scattering within the cloud layers and between layers would substantially enhance the photon path length, the multilayer clouds can be diagnosed by evaluating the estimated photon path information against observed photon path length information from a co-located rotating shadowband spectrometer (RSS). The measurements of MMCR-MPL and RSS at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site have been processed for the year 2000. Cases studies illustrate the consistency between MMCR-MPL detection and the photon path length method under most conditions. However, the photon path length method detected some multilayer clouds that were classified by the MMCR-MPL as single-layer clouds. From 1 year statistics at the ARM SGP site, about 27.7% of single-layer clouds detected by the MMCR-MPL with solar zenith angle less than 70° and optical depth greater than 10 could be multilayer clouds. It suggests that a substantial portion of single-layer clouds detected by the MMCR-MPL could also be influenced by some "missed" clouds or by the 3-D effects of clouds.

  3. Practical depolarization-ratio-based inversion procedure: lidar measurements of the Eyjafjallajökull ash cloud over the Netherlands.

    PubMed

    Donovan, David Patrick; Apituley, Arnoud

    2013-04-10

    In this paper we present a technique for estimating optical backscatter and extinction profiles using lidar, which exploits the difference between the observed linear volume depolarization ratio at 355 nm and the corresponding expected aerosol-only depolarization ratio. The technique is specific to situations where a single strongly depolarizing species is present and the associated linear particulate depolarization ratio may be presumed to be known to within a reasonable degree of accuracy (on the order of 10%). The basic principle of the technique is extended to deal with situations where a depolarizing fraction is mixed with nondepolarizing aerosol. In general, since the relative depolarization interchannel calibration is much more stable than the absolute system calibration, the depolarization-based technique is easier to implement than conventional techniques that require a profile-by-profile calibration or, equivalently, an identification of aerosol-free altitude intervals. This in particular allows for unattended data analysis and makes the technique well-suited to be part of a broader (volcanic ash) surveillance system. The technique is demonstrated by applying it to the analysis of aerosol layers resulting from the 2010 eruptions of the Eyjafjallajökull volcano in Iceland. The measurements were made at the Cabauw remote-sensing site in the central Netherlands. By comparing the results of the depolarization-based inversion with a more conventional manual inversion procedure as well as Raman lidar results, it is demonstrated that the technique can be successfully applied to the particular case of 355 nm depolarization lidar volcanic ash soundings, including cases in which the ash is mixed with nondepolarizing aerosol. PMID:23670771

  4. A 10-Year Climatology of Cloud Cover and Vertical Distribution Derived from Both Surface and GOES Observations Over the DOE ARM SGP Site

    NASA Technical Reports Server (NTRS)

    Xi, Baike; Dong, Xiquan; Minnis, P.; Khaiyer, M.

    2010-01-01

    Analysis of a decade of ARM radar-lidar and GOES observations at the SGP site reveal that 0.5 and 4-hr averages of the surface cloud fraction correspond closely to 0.5deg and 2.5deg averages of GOES cloudiness, respectively. The long-term averaged surface and GOES cloud fractions agree to within 0.5%. Cloud frequency increases and cloud amount decreases as the temporal and spatial averaging scales increase. Clouds occurred most often during winter and spring. Single-layered clouds account for 61.5% of the total cloud frequency. There are distinct bimodal vertical distributions of clouds with a lower peak around 1 km and an upper one that varies from 7.5 to 10.8 km between winter and summer, respectively. The frequency of occurrence for nighttime GOES high-cloud tops agree well with the surface observations, but are underestimated during the day.

  5. The vertical distribution of cloud regimes and their radiative impact under active phases of the Arctic Oscillation

    NASA Astrophysics Data System (ADS)

    Johansson, Erik; Devasthale, Abhay; Ekman, Annica; L'Ecuyer, Tristan; Tjernström, Michael

    2015-04-01

    The Arctic Oscillation (AO) is the leading natural mode of variability in the Northern Hemisphere (NH) and strongly influences weather and climate over mid- and high-latitudes. Although our understanding of the AO is improving, the insufficient description of clouds remains a major stumbling block in achieving the desired accuracy and confidence in forecasting and climate models over NH regions due to tight coupling of clouds with radiation and thermodynamics during the AO. Previous studies argue that anomalies of the vertical distribution of clouds show a dipole structure that is centred around Greenland during the positive and negative phases of the AO, with different signs of dipole anomalies in the low and medium/high level clouds (Devasthale et al. 2012, and references therein). The net radiative impact of such dipole structure and its implications for local dynamics remains to be evaluated. In that context, we investigate the following aspects. 1) How does the vertical distribution of various cloud regimes changes during the enhanced AO positive and negative phases and under which meteorological conditions? 2) What is the TOA, in-atmosphere and surface radiative impact of these cloud regimes during AO? 3) How sensitive the cloud radiative impact is to cloud microphysical properties during enhanced positive and negative phases of the AO? We use the combined lidar and radar (CloudSat+CALIPSO) data from the A-Train constellation of satellites from 2006 through 2011 for analysis. Specifically, we use the 2B-CLDCLASS-LIDAR data for obtaining information on cloud regimes, 2B-GEOPROF-LIDAR for cloud boundaries, and 2B-FLXHR-LIDAR for the estimates of cloud radiative heating/cooling. References: Devasthale, A., Tjernström, M., Caian, M., Thomas, M. A., Kahn, B. H., and Fetzer, E. J.: Influence of the Arctic Oscillation on the vertical distribution of clouds as observed by the A-Train constellation of satellites, Atmos. Chem. Phys., 12, 10535-10544, doi:10.5194/acp-12-10535-2012, 2012.

  6. Development of High Altitude UAV Weather Radars for Hurricane Research

    NASA Technical Reports Server (NTRS)

    Heymsfield, Gerald; Li, Li-Hua

    2005-01-01

    A proposed effort within NASA called (ASHE) over the past few years was aimed at studying the genesis of tropical disturbances off the east coast of Africa. This effort was focused on using an instrumented Global Hawk UAV with high altitude (%Ok ft) and long duration (30 h) capability. While the Global Hawk availability remains uncertain, development of two relevant instruments, a Doppler radar (URAD - UAV Radar) and a backscatter lidar (CPL-UAV - Cloud Physics Lidar), are in progress. The radar to be discussed here is based on two previous high-altitude, autonomously operating radars on the NASA ER-2 aircraft, the ER-2 Doppler Radar (EDOP) at X-band (9.6 GHz), and the Cloud Radar System (CRS) at W- band (94 GHz). The nadir-pointing EDOP and CRS radars profile vertical reflectivity structure and vertical Doppler winds in precipitation and clouds, respectively. EDOP has flown in all of the CAMEX flight series to study hurricanes over storms such as Hurricanes Bonnie, Humberto, Georges, Erin, and TS Chantal. These radars were developed at Goddard over the last decade and have been used for satellite algorithm development and validation (TRMM and Cloudsat), and for hurricane and convective storm research. We describe here the development of URAD that will measure wind and reflectivity in hurricanes and other weather systems from a top down, high-altitude view. URAD for the Global Hawk consists of two subsystems both of which are at X-band (9.3-9.6 GHz) and Doppler: a nadir fixed-beam Doppler radar for vertical motion and precipitation measurement, and a Conical scanning radar for horizontal winds in cloud and at the surface, and precipitation structure. These radars are being designed with size, weight, and power consumption suitable for the Global Hawk and other UAV's. The nadir radar uses a magnetron transmitter and the scanning radar uses a TWT transmitter. With conical scanning of the radar at a 35" incidence angle over an ocean surface in the absence of precipitation, the surface return over a single 360 degree sweep over -25 h-diameter region provides information on the surface wind speed and direction within the scan circle. In precipitation regions, the conical scan with appropriate mapping and analysis provides the 3D structure of reflectivity beneath the plane and the horizontal winds. The use of conical scanning in hurricanes has recently been demonstrated for measuring inner core winds with the IWRAP system flying on the NOAA P3's. In this presentation, we provide a description of the URAD system hardware, status, and future plans. In addition to URAD, NASA SBIR activity is supporting a Phase I study by Remote Sensing Solutions and the University of Massachusetts for a dual-frequency IWRAP for a high altitude UAV that utilizes solid state transmitters at 14 and 35 GHz, the same frequencies that are planned for the radar on the Global Precipitation System satellite. This will be discussed elsewhere at the meeting.

  7. Vertical velocities and turbulence in midlatitude anvil cirrus: A comparison between in situ aircraft measurements and ground-based Doppler cloud radar retrievals

    NASA Astrophysics Data System (ADS)

    Muhlbauer, Andreas; Kalesse, Heike; Kollias, Pavlos

    2014-11-01

    This study introduces a statistical comparison of vertical velocity observations within cirrus from aircraft and ground-based Doppler cloud radar. Two cases of midlatitude anvil cirrus forming under very similar environmental conditions are examined. The case studies benefit from simultaneous observations of vertical velocities in cirrus collected at and around the Atmospheric Radiation Measurement Southern Great Plains site during the U.S. Department of Energy Small Particles in Cirrus field campaign. Observations from both platforms suggest that the majority of vertical velocities in the examined midlatitude anvil cirrus cases are roughly within ±1 m s-1 although higher vertical velocities are occasionally observed. The quality of the vertical velocity comparison between in situ aircraft measurements and ground-based Doppler radar retrievals depends on the case. For the first case on 23 April 2010, the comparison suggests that the radar retrieval may underestimate vertical velocities in the range between roughly 50 cm s-1 and 1 m s-1. For the second case on 14 June 2010, the agreement between radar and aircraft is excellent, and the differences are largely within the observed variability of vertical velocities within cirrus. Differences in the spatial scales of vertical velocities and turbulence sampled by the aircraft and Doppler radar, which arise due to differences in the temporal resolution of the observational platforms are not found to explain the observed discrepancies. Estimates for the dissipation rate of turbulent kinetic energy agree to within 1 order of magnitude between the two observational platforms.

  8. Evaluation of single field-of-view cloud top height retrievals from hyperspectral infrared sounder radiances with CloudSat and CALIPSO measurements

    NASA Astrophysics Data System (ADS)

    Yao, Zhigang; Li, Jun; Weisz, Elisabeth; Heidinger, Andrew; Liu, Chian-Yi

    2013-08-01

    Accurate cloud top height retrievals from hyperspectral infrared (IR) sounder radiances are needed for weather and climate prediction. To account for the nonlinearity of the cloud parameters with respect to the IR radiances, a one-dimensional variational retrieval algorithm is used to derive the cloud top heights (CTHs) from the Atmospheric Infrared Sounder (AIRS) radiances on a single field-of-view basis. The CTHs are evaluated by comparison with the measurements from radar and lidar instruments onboard the Earth Observing System (EOS) CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellites. Using the retrievals from a global 3 day dataset, it is found that the variational algorithm compared with the regression algorithm could reduce the variability of the difference between the AIRS and active measurements by 1 km. And the biases of AIRS CTHs range from +1.5 to -1.4 km and from +1.6 to -3.8 km, depending on the Cloud Profiling Radar (CPR) and CALIPSO CTHs between 3 and 18 km, respectively. Globally, the AIRS CTH is overestimated (underestimated) when the CTH from active measurements is below (above) 5 km. The bias decreases from -1.9 to -0.8 km, and the variability decreases from 2.8 to about 1.6 km with the increase of the CALIPSO cloud optical thickness from 0.1 to 2.5. It also reveals that the AIRS CTHs agree better with the CPR than the CALIPSO.

  9. A comparison of cloud top heights computed from airborne lidar and MAS radiance data using CO 2 slicing

    Microsoft Academic Search

    Richard A. Frey; Bryan A. Baum; W. Paul Menzel; Steven A. Ackerman; Christopher C. Moeller; James D. Spinhirne

    1999-01-01

    Data from two instruments onboard the National Aeronautics and Space Administration (NASA) ER-2 high-altitude aircraft have been utilized in the largest validation study to date in assessing the accuracy of the CO2-slicing cloud height algorithm. Infrared measurements of upwelling radiance from the MODIS (Moderate- Resolution Imaging Spectroradiometer) airborne simulator (MAS) were used to generate cloud top heights and then compared

  10. Validation of CERES-MODIS Arctic cloud properties using CloudSat/CALIPSO and ARM NSA observations

    NASA Astrophysics Data System (ADS)

    Giannecchini, K.; Dong, X.; Xi, B.; Minnis, P.; Kato, S.

    2011-12-01

    The traditional passive satellite studies of cloud properties in the Arctic are often affected by the complex surface features present across the region. Nominal visual and thermal contrast exists between Arctic clouds and the snow- and ice-covered surfaces beneath them, which can lead to difficulties in satellite retrievals of cloud properties. However, the addition of active sensors to the A-Train constellation of satellites has increased the availability of validation sources for cloud properties derived from passive sensors in the data-sparse high-latitude regions. In this study, Arctic cloud fraction and cloud heights derived from the NASA CERES team (CERES-MODIS) have been compared with CloudSat/CALIPSO and DOE ARM NSA radar-lidar observations over Barrow, AK, for the two-year period from 2007 to 2008. An Arctic-wide comparison of cloud fraction and height between CERES-MODIS and CloudSat/CALIPSO was then conducted for the same time period. The CERES-MODIS cloud properties, which include cloud fraction and cloud effective heights, were retrieved using the 4-channel VISST (Visible Infrared Solar-Infrared Split-window Technique) [Minnis et al.,1995]. CloudSat/CALIPSO cloud fraction and cloud-base and -top heights were from version RelB1 data products determined by both the 94 GHz radar onboard CloudSat and the lidar on CALIPSO with a vertical resolution of 30 m below 8.2 km and 60 m above. To match the surface and satellite observations/retrievals, the ARM surface observations were averaged into 3-hour intervals centered at the time of the satellite overpass, while satellite observations were averaged within a 3°x3° grid box centered on the Barrow site. The preliminary results have shown that all observed CFs have peaks during April-May and September-October, and dips during winter months (January-February) and summer months (June-July) during the study period of 2007-2008. ARM radar-lidar and CloudSat/CALIPSO show generally good agreement in CF (0.79 vs. 0.74), while CERES-MODIS derived values are much lower (0.60). CERES-MODIS derived cloud effective height (2.7 km) falls between the CloudSat/CALIPSO derived cloud base (0.6 km) and top (6.4 km) and the ARM ceilometers and MMCR derived cloud base (0.9 km) and radar derived cloud top (5.8 km). When extended to the entire Arctic, although the CERES-MODIS and Cloudsat/CALIPSO derived annual mean CFs agree within a few percents, there are significant differences over several regions, and the maximum cloud heights derived from CloudSat/CALIPSO (13.4 km) and CERES-MODIS (10.7 km) show the largest disagreement during early spring.

  11. Automatic Weather Station (AWS) Lidar

    NASA Technical Reports Server (NTRS)

    Rall, Jonathan A.R.; Abshire, James B.; Spinhirne, James D.; Smith, David E. (Technical Monitor)

    2000-01-01

    An autonomous, low-power atmospheric lidar instrument is being developed at NASA Goddard Space Flight Center. This compact, portable lidar will operate continuously in a temperature controlled enclosure, charge its own batteries through a combination of a small rugged wind generator and solar panels, and transmit its data from remote locations to ground stations via satellite. A network of these instruments will be established by co-locating them at remote Automatic Weather Station (AWS) sites in Antarctica under the auspices of the National Science Foundation (NSF). The NSF Office of Polar Programs provides support to place the weather stations in remote areas of Antarctica in support of meteorological research and operations. The AWS meteorological data will directly benefit the analysis of the lidar data while a network of ground based atmospheric lidar will provide knowledge regarding the temporal evolution and spatial extent of Type la polar stratospheric clouds (PSC). These clouds play a crucial role in the annual austral springtime destruction of stratospheric ozone over Antarctica, i.e. the ozone hole. In addition, the lidar will monitor and record the general atmospheric conditions (transmission and backscatter) of the overlying atmosphere which will benefit the Geoscience Laser Altimeter System (GLAS). Prototype lidar instruments have been deployed to the Amundsen-Scott South Pole Station (1995-96, 2000) and to an Automated Geophysical Observatory site (AGO 1) in January 1999. We report on data acquired with these instruments, instrument performance, and anticipated performance of the AWS Lidar.

  12. Cloud and Radiation Mission with Active and Passive Sensing from the Space Station

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D.

    1998-01-01

    A cloud and aerosol radiative forcing and physical process study involving active laser and radar profiling with a combination of passive radiometric sounders and imagers would use the space station as an observation platform. The objectives are to observe the full three dimensional cloud and aerosol structure and the associated physical parameters leading to a complete measurement of radiation forcing processes. The instruments would include specialized radar and lidar for cloud and aerosol profiling, visible, infrared and microwave imaging radiometers with comprehensive channels for cloud and aerosol observation and specialized sounders. The low altitude,. available power and servicing capability of the space station are significant advantages for the active sensors and multiple passive instruments.

  13. On the properties of cirrus clouds over the tropical West Pacific

    NASA Astrophysics Data System (ADS)

    Mitrescu, Cristian

    Understanding Earth's climate is a complex undertaking, and requires the development of accurate simulations that combine all the natural elements that can affect climate. The data that goes into these models needs to be as precise as possible, and collecting reliable data is an important and sometimes difficult step in this research. Clouds, in particular tropical thin cirrus clouds, exert a major influence on climate through cloud radiative forcing (CRF). These clouds, with their variable height, optical depth and particle distribution, make collecting accurate data difficult. Investigation by remote sensing techniques, in particular by LIDARs alone or in combination with other instruments, has become a popular way of retrieving cirrus cloud physical and microphysical properties such as particle concentration (N), characteristic diameter (D), ice water content (IWC) and ice water path (IWP). The aim of this study is to document the properties of tropical thin cirrus using combinations of data collected from various remote sensing systems. A new method for determining cloud optical depths and a new parameterization that treats multiple scattering effects in the lidar equation are introduced. A novel "inverse" model applied to LIDAR measurements produces profiles for IWC and N. A simple analytical method developed for the combination of RADAR and LIDAR system is also presented. This combination of data provides vertical profiles for D, N, and IWC. One key finding derived from the measured data is the observational relationship between optical depth and IWP. Also, the active-passive combinations of LIDAR and IR radiometer, and LIDAR and MODIS Airborne Sensor are explored. The results obtained with these new analysis tools are used to study the radiative budget of tropical thin cirrus. It is shown how the thin cirrus radiatively heat the atmosphere both within the layer of cloudiness as well as within the atmosphere below. A convenient parameterization of the LW and SW CRF as function of the IWP is tested against measured data.

  14. Evaluating Snowfall Detectability of NASA CloudSat with NOAA/NSSL Ground Radar-Based National Multi-sensor Mosaic QPE (NMQ)

    NASA Astrophysics Data System (ADS)

    Chen, S.; Cao, Q.; Hong, Y.; Gourley, J. J.; Hu, J.

    2013-12-01

    NASA CloudSat, carrying the first space-borne Cloud Profiling Radar (CPR), is the first satellite that provides scientific communities with global snowfall observations. The accuracy of snowfall observation and quantification at middle and high latitude area is directly correlated with the liability of satellite-based precipitation estimates. However, up-to-date there is not systematic evaluation of its snowfall detectability at regional and global scale. Validation and evaluation of CPR's capability of snowfall detection is still needed in satellite precipitation communities. The NOAA/NSSL ground radar-based National Mosaic and multi-sensor Quantitative Precipitation Estimates (QPE) (NMQ or Q2) provides the high spatiotemporal resolution (1km/5min) 2-dimensional (2D) multi-suites precipitation products as well as 3-dimensional (3D) products. Such high-resolution QPE products offer an ideal alternate to evaluate satellite-based observations and products. In this paper, the CloudSat-CPR's detectability of falling snow is systematically evaluated using NMQ-Q2 snowfall products (i.e., solid snowfall precipitation identification) over the CONUS from January 2009 to December 2012. Spatial and temporal matching is applied to obtain the most matched dataset from both observations considering their differences in spatiotemporal resolution. The evaluation results offer the insights into the performance of CPR in detecting falling snow and also demonstrate its great potential in improving the solid precipitation (snowfall) in the mid-high latitude area and high-altitude area (e.g. the Tibetan plateau). A synthetic approach of incorporating the ground-radar-based NMQ products for evaluating and integrating into spaceborne radar observations will be highly expected with the launch of Global Precipitation Measurement in 2014.

  15. Clouds

    NSDL National Science Digital Library

    Carl Wozniak

    Clouds comprise a wonderful focus for classroom study. They're ubiquitous, ever-changing, scientifically interesting and, most importantly for teachers, they're cheap. The material presented here includes sections on cloud formation, cloud types, cloud pictures, other cloud-related phenomena, and a glossary.

  16. The Atmospheric Channels of GLAS: Near Real-Time Global Lidar Remote Sensing of Clouds and Aerosols from Space

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Hlavka, Dennis; Hart, Bill; Welton, E. Judd; Spinhirne, James

    2000-01-01

    The Geoscience Laser Altimeter System (GLAS) will be placed into orbit in 2001 aboard the Ice, Cloud and Land Elevation Satellite (ICESat). From its nearly polar orbit (94 degree inclination), GLAS will provide continuous global measurements of the vertical distribution of clouds and aerosols while simultaneously providing high accuracy topographic profiling of surface features. During the mission, which is slated to last 3 to 5 years, the data collected by GLAS will be in near-real time to produce level 1 and 2 data products at the NASA GLAS Science Computing Facility (SCF) at Goddard Space Flight Center in Greenbelt, Maryland. The atmospheric products include cloud and aerosol layer heights, planetary boundary layer depth, polar stratospheric clouds and thin cloud and aerosol optical depth. These products will be made available to the science community within days of their creation. The processing algorithms must be robust, adaptive, efficient, and clever enough to run autonomously for the widely varying atmospheric conditions that will be encountered. This paper presents an overview of the GLAS atmospheric data products and briefly discusses the design of the processing algorithms.

  17. Spaceborne Lidar, Validation, and the REALM Network

    Microsoft Academic Search

    M. Patrick McCormick

    A long-duration spaceborne lidar called CALIPSO, now scheduled to be launched in Spring 2005, is the first such multi-wavelength and polarization-sensitive lidar specifically designed for the purpose of providing global aerosol and cloud data for reducing uncertainties in climate forcing. It will fly on the French-built Proteus Spacecraft. Further, it is the first lidar to be flown in formation with

  18. Cloud-top Height Esimation Method by Geostationary Satellite Split-Window Measurements Trained with CALIPSO and CloudSat data

    NASA Astrophysics Data System (ADS)

    Nishi, Noriyuki; Hamada, Atsushi; Hirose, Hitoshi

    2015-04-01

    We released a database of cloud top height and visible optical thickness (CTOP) with one-hour resolution over the tropical western Pacific and Maritime Continent, by using infrared split-window data of the geostationary satellites (MTSAT) (http://database.rish.kyoto-u.ac.jp/arch/ctop/). We made lookup tables for estimating cloud top height only with geostationary infrared observations by comparing them with the direct cloud observation by CloudSat (Hamada and Nishi, 2010, JAMC). We picked out the same-time observations by MTSAT and CloudSat and regressed the cloud top height observation of CloudSat back onto 11 micro m brightness temperature (Tb) and the difference between the 11 micro m Tb and 12 micro m Tb of MTSAT. The database contains digital data and quick look images from Jul 2005 to real time and the area in 85E-155W (MTSAT2) and 20S-20N. Though the CTOP dataset is particularly useful for the upper tropospheric clouds, it has one serious problem. The cloud radar onboard CloudSat cannot well detect the optically thin cirrus clouds composed of small ice crystals and misses a certain part of cirriform clouds in the upper troposphere. In order to overcome this weakness, we are now making next version of the CTOP by using the lidar data (CALIOP) onboard CALIPSO satellite. One problem on the use of lidar observation is that they observe very thin cirrus formed around the tropopause. The main purpose of CTOP dataset is to provide the top height of clouds that originate from cloud clusters including cumulonimbus and nimbostratus, not of in-situ cirrus clouds formed near the tropopause. To exclude the very thin tropopause cirrus, we define cloud-top height of CALIOP observation as the height at which the optical depth accumulated from the cloud top is 0.2, instead of the CALIOP cloud top itself. With this criterion we can succeed in estimating the top height of cirruiform clouds, but it has another problem for thick clouds like cumulonimbus. For such clouds, the height of accumulated optical depth 0.2 is considerably lower than the real cloud top, possibly due to rather small number of large cloud particles near the top. Therefore, the estimation using CloudSat data is closer to the real top for the thick clouds, while that using CALIOP data is closer for cirriform clouds. So we are now making a lookup table with using both CloudSat and CALIPSO data to estimate cloud-top heights both for thick and thin clouds seamlessly.

  19. Detection of artificially created negative ion clouds with incoherent scatter radar

    NASA Technical Reports Server (NTRS)

    Sultan, Peter J.; Mendillo, Michael; Oliver, William L.; Holt, John M.

    1992-01-01

    The physical mechanisms by which negative ions change the shape of the incoherent scatter spectrum, and the way in which shape changes may be used to detect the presence of heavy positive and negative ions in an ambient ionosphere are investigated. In order to detect heavy negative ions, the temperature structure of the ionosphere is fixed to a prevent average measurement, and any changes in spectral shape during the experiment are interpreted as being caused by changes in composition, and not by changes in the temperature ratio Te/Ti. The spatial and temporal development of heavy negative ion plasma clouds created during four active chemical release experiments was observed. Concentrations of 10-40-percent SF6(-) were detected in SPINEX 1, SPINEX 2, and IMS data sets. An average uncertainty of +/-10-percent SF6(-) is present in all three experiments. Concentrations of 30-percent Br(-) were detected in the NICARE 1 release, with uncertainties of +/-4 percent.

  20. Lidar observations of the Mount St. Helens eruption clouds over mid-Europe, May to July 1980

    Microsoft Academic Search

    R. Reiter; H. Jaeger; W. Carnuth; W. Funk

    1980-01-01

    Three violent eruptions of the Mount St. Helens volcano on 18 and 24 May and 13 June terminated the period of background aerosol prevailing in the stratosphere since the end of 1976, after the decay of the volcanic aerosols injected by the Fuego eruption in 1974. The Mt. St. Helens eruption cloud arrived over mid-Europe on 26 May. The subsequent

  1. Evaluation of Ice cloud retrievals using CloudSat/CALIPSO/MODIS/AIRS and EarthCARE

    NASA Astrophysics Data System (ADS)

    Okamoto, H.; Sato, K.; Hagihara, Y.; Tanaka, K.; Ishimoto, H.; Makino, T.; Nishizawa, T.; Sugimoto, N.

    2014-12-01

    We analyzed characterization of ice water content and ice water path and discussed the uncertainties of these quantities. We developed the retrieval algorithms that use CloudSat and CALIOP on CALIPSO and also the one for CloudSat, CALIOP and MODIS on Aqua. There are several possible sources of uncertainties in the retrieved values. The backscattering properties of ice particles have not been yet fully understood in lidar wavelengths. There are also uncertainties in the retrieval results in radar- or lidar-only detected cloud regions where only one of the two sensors detected clouds. Multiple scattering contribution in space-borne lidar observations has not been fully evaluated too. In order to assess and reduce these uncertainties, we introduced two approaches. Analyses of independent physical quantities based on the same physical ice particle models used in the retrievals of microphysics might be useful in order to test consistency in the ice particle model and its scattering properties. Second approach is to develop a new type of ground-based active sensor system. Concerning the first approach, backscattering color ratio of ice particles was derived from the backscattering coefficient at 532nm and 1064nm for periods before and after the change of the laser tilt angle from 0.3 degrees off nadir to 3 degrees off nadir. Then we examined relationships between the retrieved color ratio and the retrieved microphysics and found the relations agreed with the theoretically estimated ones.For the second approach, Multi-Field of view Multiple Scattering Polarization Lidar has been developed to resolve the angular dependence of backscattering and depolarization ratio and has been employed to evaluate the uncertainties in the retrievals. We performed global evaluation of ice microphysical properties and examined relationships between ice microphysics and ice super saturation information from AIRS on Aqua. Finally we introduced the JAXA-ESA satellite mission EarthCARE that will be launched in 2016. There are four sensors on the EarthCARE, i.e., Doppler cloud profiling radar (CPR), high spectral resolution lidar at 355nm (ATLID), multi-spectral imager (MSI) and broad band radiometer (BBR). We discussed the possible improvements in the ice cloud retrievals.

  2. Theory of CW lidar aerosol backscatter measurements and development of a 2.1 microns solid-state pulsed laser radar for aerosol backscatter profiling

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Henderson, Sammy W.; Frehlich, R. G.

    1991-01-01

    The performance and calibration of a focused, continuous wave, coherent detection CO2 lidar operated for the measurement of atmospheric backscatter coefficient, B(m), was examined. This instrument functions by transmitting infrared (10 micron) light into the atmosphere and collecting the light which is scattered in the rearward direction. Two distinct modes of operation were considered. In volume mode, the scattered light energy from many aerosols is detected simultaneously, whereas in the single particle mode (SPM), the scattered light energy from a single aerosol is detected. The analysis considered possible sources of error for each of these two cases, and also considered the conditions where each technique would have superior performance. The analysis showed that, within reasonable assumptions, the value of B(m) could be accurately measured by either the VM or the SPM method. The understanding of the theory developed during the analysis was also applied to a pulsed CO2 lidar. Preliminary results of field testing of a solid state 2 micron lidar using a CW oscillator is included.

  3. Clouds

    NSDL National Science Digital Library

    First, the Project Atmosphere Canada offers a module to educate primary and secondary students about cloud formation and characteristics (1). The website outlines key points and offers a more in-depth discussion of water vapor, cloud formation, convection, air motion, severe weather, and more. The second website, by Scholastic, supplies many pdf documents of activities and lesson plans for all types of weather phenomena including clouds (2). Students can learn about condensation, discover what makes up a cloud, and find a key identifying the cloud types. Next, USA Today offers an online tutorial of the differing characteristics of clouds (3). Users can learn about Mammatus clouds, contrails, cloud seeding, and other cloud-related topics. At the fourth website, visitors can view meteorologist Dan Satterfield's amazing cloud photographs (4). Educators may find useful materials to supplement their lectures. Next, NASA's Climate and Radiation Branch furnishes "information on the fantastic variety of cloud forms and structures, and their implications for climate" (5). While the website is still being constructed, users can find useful information about the Bounded Cascades Fractal Cloud model, animations, and definitions of inhomogeneous cloud terminology. The sixth website, created by the National Center for Atmospheric Research and the University Corporation for Atmospheric Research, addresses how clouds impact our lives, how they cause chaos, and how they form (6). The enlightening descriptions are packed with colorful images and short quizzes. Next, The Australian Government's Bureau of Meteorology describes the useful of clouds as an indicator of weather conditions (7). After learning how moist air can form clouds, individuals can view images of the ten most common cloud types. Lastly, Enchanted Learning offers a table of the cloud types with their abbreviation, appearance, composition, and altitude along with explanations of cloud formation and the atmosphere (8). Educators can find simple activities dealing with cloud types and the water cycle.

  4. Numerical Simulations of a Snow Storm Using the Goddard Cloud Microphysics Scheme with the WRF Model and the Comparison with Ground and Satellite Radars

    NASA Astrophysics Data System (ADS)

    Shi, J.; Matsui, T.; Tao, W.; Hou, A.; Lang, S. E.; Cifelli, R.; Peters-Lidard, C.

    2008-12-01

    One of the grand challenges of the Global Precipitation Measurement (GPM) mission is to improve precipitation measurements in mid- and high-latitudes during cold seasons through the use of high-frequency passive microwave radiometry. For this, the Weather Research Forecast (WRF) model with the Goddard microphysics scheme is coupled with the Satellite Data Simulation Unit (WRF-SDSU) that has been developed to facilitate the over- snowfall retrieval algorithm by providing virtual cloud library and microwave brightness temperature (Tb) measurements consistent to the GPM Microwave Imager (GMI). This study tested the Goddard cloud microphysics scheme in WRF in snowstorm events (January 20-22, 2007) over the Canadian CloudSat/CALIPSO Validation Project (C3VP) site in Ontario, Canada. In this meeting, we will present the performance of the Goddard cloud microphysics scheme both with 2ice (ice and snow) and 3ice (ice, snow and graupel) as well as other WRF microphysics schemes. Results will be compared with the King Radar data. We will also use the WRF model outputs to drive the Goddard SDSU to calculate radiances and backscattering signals consistent to satellite direct observations. These simulated radiance are evaluated against the measurement from A-Train satellites. Note that the Goddard cloud microphysics scheme is now officially included in the WRF V3.

  5. Geometric calibration and radiometric correction of LiDAR data and their impact on the quality of derived products.

    PubMed

    Habib, Ayman F; Kersting, Ana P; Shaker, Ahmed; Yan, Wai-Yeung

    2011-01-01

    LiDAR (Light Detection And Ranging) systems are capable of providing 3D positional and spectral information (in the utilized spectrum range) of the mapped surface. Due to systematic errors in the system parameters and measurements, LiDAR systems require geometric calibration and radiometric correction of the intensity data in order to maximize the benefit from the collected positional and spectral information. This paper presents a practical approach for the geometric calibration of LiDAR systems and radiometric correction of collected intensity data while investigating their impact on the quality of the derived products. The proposed approach includes the use of a quasi-rigorous geometric calibration and the radar equation for the radiometric correction of intensity data. The proposed quasi-rigorous calibration procedure requires time-tagged point cloud and trajectory position data, which are available to most of the data users. The paper presents a methodology for evaluating the impact of the geometric calibration on the relative and absolute accuracy of the LiDAR point cloud. Furthermore, the impact of the geometric calibration and radiometric correction on land cover classification accuracy is investigated. The feasibility of the proposed methods and their impact on the derived products are demonstrated through experimental results using real data. PMID:22164121

  6. Comparing ice cloud microphysical properties using CloudNET and Atmospheric Radiation Measurement Program data

    NASA Astrophysics Data System (ADS)

    van Zadelhoff, G.-J.; Donovan, D. P.; Klein Baltink, H.; Boers, R.

    2004-12-01

    A comparison of the microphysical properties of ice clouds, using lidar and radar data, is made for three sites: Cabauw (Netherlands), Atmospheric Radiation Measurement Program Southern Great Plains (ARM-SGP) site (United States), and Chilbolton (United Kingdom). The effective particle size (Reff), extinction, and ice water content (IWC) are derived and correlated to each other, temperature, radar reflectivity, and depth into the cloud from cloud top (?Zt). There is no indication for large seasonal differences of the ice microphysical properties; however, the Reff differences observed at the ARM-SGP site are of the same magnitude as the error. The Chilbolton and Cabauw sites exhibit similar behavior in all cases while the ARM site shows large differences for some relationships, e.g., Reff(T, IWC). Within the sensitivity studies performed, it is not possible to construct a single Reff(T, IWC) parameterization valid at all three sites, and therefore it is not applicable in global models. It is possible to construct a single parameterization of ice water content related to temperature or to radar reflectivity. In all cases, an ice habit and particle size distribution assumption has to be made, resulting in different fits for different habits. When Reff is correlated to ?Zt for different classes of total cloud thicknesses (H), one can define a single parameterization, using parabolic descriptions, valid at the three sites and possibly on a global scale.

  7. Eye-Safe Lidar

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1989-01-01

    Laser infrared radar (lidar) undergoing development harmless to human eyes, consists almost entirely of solid-state components, and offers high range resolution. Operates at wavelength of about 2 micrometers. If radiation from such device strikes eye, almost completely absorbed by cornea without causing damage, even if aimed directly at eye. Continuous-wave light from laser oscillator amplified and modulated for transmission from telescope. Small portion of output of oscillator fed to single-mode fiber coupler, where mixed with return pulses. Intended for remote Doppler measurements of winds and differential-absorption measurements of concentrations of gases in atmosphere.

  8. Algorithm for retrieving lidar ratios at 1064 nm from space-based lidar backscatter data

    Microsoft Academic Search

    Mark Vaughan

    2004-01-01

    Accurate estimation of cloud and aerosol optical depths using backscatter lidar data requires knowledge of the particulate lidar ratio (i.e., the extinction-to-backscatter ratio). In those cases for which a measurement of molecular backscatter can be made on the far side of a layer, knowledge of the lidar ratio can be derived directly from the data. However, obtaining a reliable clear

  9. An X-Band Radar Terrain Feature Detection Method for Low-Altitude SVS Operations and Calibration Using LiDAR

    NASA Technical Reports Server (NTRS)

    Young, Steve; UijtdeHaag, Maarten; Campbell, Jacob

    2004-01-01

    To enable safe use of Synthetic Vision Systems at low altitudes, real-time range-to-terrain measurements may be required to ensure the integrity of terrain models stored in the system. This paper reviews and extends previous work describing the application of x-band radar to terrain model integrity monitoring. A method of terrain feature extraction and a transformation of the features to a common reference domain are proposed. Expected error distributions for the extracted features are required to establish appropriate thresholds whereby a consistency-checking function can trigger an alert. A calibration-based approach is presented that can be used to obtain these distributions. To verify the approach, NASA's DC-8 airborne science platform was used to collect data from two mapping sensors. An Airborne Laser Terrain Mapping (ALTM) sensor was installed in the cargo bay of the DC-8. After processing, the ALTM produced a reference terrain model with a vertical accuracy of less than one meter. Also installed was a commercial-off-the-shelf x-band radar in the nose radome of the DC-8. Although primarily designed to measure precipitation, the radar also provides estimates of terrain reflectivity at low altitudes. Using the ALTM data as the reference, errors in features extracted from the radar are estimated. A method to estimate errors in features extracted from the terrain model is also presented.

  10. Raman lidar measurements of water vapor and aerosol/clouds during the FIRE/SPECTRE field campaign

    NASA Technical Reports Server (NTRS)

    Melfi, S. H.; Whiteman, D.; Ferrare, R.; Evans, K.; Goldsmith, J. E. M.; Lapp, M.; Bisson, S. E.

    1992-01-01

    Water vapor is one of the most important constituents of the earth's atmosphere. It has a major impact on both atmospheric dynamics and radiative transfer. From a dynamic standpoint, the distribution of water vapor with height determines convective stability which is the major indicator of destructive storm development. Also, water vapor stored in the planetary boundary layer acts as the fuel to intensify severe weather. In regards to radiative t