Science.gov

Sample records for cloud radar lidar

  1. HIGH SPECTRAL RESOLUTION LIDAR EMULATION VIA DOPPLER CLOUD RADAR SPECTRUM PROCESSING AND ITS IMPLICATIONS FOR

    E-print Network

    HIGH SPECTRAL RESOLUTION LIDAR EMULATION VIA DOPPLER CLOUD RADAR SPECTRUM PROCESSING AND ITS measurements of high spectral resolution lidar (HSRL) through processing of Doppler cloud radar spectra are sustainable. In this arena, the synergistic relationship of radar and lidar is often exploited, with lidar

  2. The Retrieval of Ice-Cloud Properties from Cloud Radar and Lidar Synergy CLAIRE TINEL* AND JACQUES TESTUD

    E-print Network

    Protat, Alain

    properties of clouds. It combines the apparent backscatter reflectivity from the radar and the apparentThe Retrieval of Ice-Cloud Properties from Cloud Radar and Lidar Synergy CLAIRE TINEL* AND JACQUES method that combines cloud radar (94­95 GHz) and lidar data to derive the radiative and microphysical

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

    E-print Network

    Hogan, Robin

    A variational scheme for retrieving ice cloud properties from combined radar, lidar, and infrared retrieval is possible between regions of the cloud detected by both radar and lidar and regions detected such as strong attenuation), the retrieval tends toward an empirical relationship using radar reflectivity factor

  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.j.hogan@reading.ac.uk. 1http://www.met.rdg.ac.uk/radar/cloudnet/ 2http://www.arm.gov/ are regular 6-hourly radiosonde

  6. 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

  7. 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.

  8. An annual cycle of Arctic cloud characteristics observed by radar and lidar at SHEBA

    E-print Network

    Shupe, Matthew

    that the Arctic may also be a region where early warning indicators of climate change will be most apparent in simulations of Arctic climate [Randall et al., 1998]. [3] Our understanding of Arctic cloud propertiesAn annual cycle of Arctic cloud characteristics observed by radar and lidar at SHEBA J. M. Intrieri

  9. Validation of SCIAMACHY O2 A band cloud heights using Cloudnet radar/lidar measurements

    NASA Astrophysics Data System (ADS)

    Wang, P.; Stammes, P.

    2013-10-01

    For the first time two SCIAMACHY O2 A band cloud height products are validated using ground-based radar/lidar measurements between January 2003 and December 2011. The products are the ESA Level 2 (L2) version 5.02 cloud top height and the FRESCO (Fast Retrieval Scheme for Clouds from the Oxygen A band) version 6 cloud height. The radar/lidar profiles are obtained at the Cloudnet sites of Cabauw and Lindenberg, and are averaged for one hour centered at the SCIAMACHY overpass time to achieve an optimal temporal and spatial match. In total we have about 220 cases of single layer clouds and 200 cases of multi-layer clouds. The FRESCO cloud height and ESA L2 cloud top height are compared with the Cloudnet cloud top height and Cloudnet cloud middle height. We find that the ESA L2 cloud top height has a better agreement with the Cloudnet cloud top height than the Cloudnet cloud middle height. The ESA L2 cloud top height is on average 0.44 km higher than the Cloudnet cloud top height, with a standard deviation of 3.07 km. The FRESCO cloud height is closer to the Cloudnet cloud middle height than the Cloudnet cloud top height. The mean difference between the FRESCO cloud height and the Cloudnet cloud middle height is -0.14 km with a standard deviation of 1.88 km. The SCIAMACHY cloud height products are further compared to the Cloudnet cloud top height and the Cloudnet cloud middle height in 1 km bins. For single layer clouds, the difference between the ESA L2 cloud top height and the Cloudnet cloud top height is less than 1 km for each cloud bin at 3-7 km, which is 24 % percent of the data. The difference between the FRESCO cloud height and the Cloudnet cloud middle height is less than 1 km for each cloud bin at 0-6 km, which is 85 % percent of the data. The results are similar for multi-layer clouds, but the percentage of cases having a bias within 1 km is smaller than for single layer clouds. Since globally about 60 % of all clouds are low clouds and 42 % are single-layer low clouds, we expect that globally for a large percentage of cases the FRESCO cloud height would be close to the cloud middle height.

  10. Cloud Effects on Radiative Heating Rate Profiles over Darwin using ARM and A-train Radar/Lidar Observations

    SciTech Connect

    Thorsen, Tyler J.; Fu, Qiang; Comstock, Jennifer M.

    2013-06-11

    Observations of clouds from the ground-based U.S. Department of Energy Atmospheric Radiation Measurement program (ARM) and satellite-based A-train are used to compute cloud radiative forcing profiles over the ARM Darwin, Australia site. Cloud properties are obtained from both radar (the ARM Millimeter Cloud Radar (MMCR) and the CloudSat satellite in the A-train) and lidar (the ARM Micropulse lidar (MPL) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite in the A-train) observations. Cloud microphysical properties are taken from combined radar and lidar retrievals for ice clouds and radar only or lidar only retrievals for liquid clouds. Large, statistically significant differences of up to 1.43 K/day exist between the mean ARM and A-train net cloud radiative forcing profiles. The majority of the difference in cloud radiative forcing profiles is shown to be due to a large difference in the cloud fraction above 12 km. Above this altitude the A-train cloud fraction is significantly larger because more clouds are detected by CALIPSO than by the ground-based MPL. It is shown that the MPL is unable to observe as many high clouds as CALIPSO due to being more frequently attenuated and a poorer sensitivity even in otherwise clear-sky conditions. After accounting for cloud fraction differences and instrument sampling differences due to viewing platform we determined that differences in cloud radiative forcing due to the retrieved ice cloud properties is relatively small. This study demonstrates that A-train observations are better suited for the calculation cloud radiative forcing profiles. In addition, we find that it is necessary to supplement CloudSat with CALIPSO observations to obtain accurate cloud radiative forcing profiles since a large portion of clouds at Darwin are detected by CALIPSO only.

  11. 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.

  12. Combined vertical-velocity observations with Doppler lidar, cloud radar and wind profiler

    NASA Astrophysics Data System (ADS)

    Bühl, J.; Leinweber, R.; Görsdorf, U.; Radenz, M.; Ansmann, A.; Lehmann, V.

    2015-08-01

    Case studies of combined vertical-velocity measurements of Doppler lidar, cloud radar and wind profiler are presented. The measurements were taken at the Meteorological Observatory, Lindenberg, Germany. Synergistic products are presented that are derived from the vertical-velocity measurements of the three instruments: a comprehensive classification mask of vertically moving atmospheric targets and the terminal fall velocity of water droplets and ice crystals corrected for vertical air motion. It is shown that this combination of instruments can up-value the measurement values of each single instrument and may allow the simultaneous sensing of atmospheric targets and the motion of clear air.

  13. Joint retrievals of cloud and drizzle in marine boundary layer clouds using ground-based radar, lidar and zenith radiances

    NASA Astrophysics Data System (ADS)

    Fielding, M. D.; Chiu, J. C.; Hogan, R. J.; Feingold, G.; Eloranta, E.; O'Connor, E. J.; Cadeddu, M. P.

    2015-07-01

    Active remote sensing of marine boundary-layer clouds is challenging as drizzle drops often dominate the observed radar reflectivity. We present a new method to simultaneously retrieve cloud and drizzle vertical profiles in drizzling boundary-layer clouds using surface-based observations of radar reflectivity, lidar attenuated backscatter, and zenith radiances under conditions when precipitation does not reach the surface. Specifically, the vertical structure of droplet size and water content of both cloud and drizzle is characterised throughout the cloud. An ensemble optimal estimation approach provides full error statistics given the uncertainty in the observations. To evaluate the new method, we first perform retrievals using synthetic measurements from large-eddy simulation snapshots of cumulus under stratocumulus, where cloud water path is retrieved with an error of 31 g m-2. The method also performs well in non-drizzling clouds where no assumption of the cloud profile is required. We then apply the method to observations of marine stratocumulus obtained during the Atmospheric Radiation Measurement MAGIC deployment in the Northeast Pacific. Here, retrieved cloud water path agrees well with independent three-channel microwave radiometer retrievals, with a root mean square difference of 10-20 g m-2.

  14. Joint retrievals of cloud and drizzle in marine boundary layer clouds using ground-based radar, lidar and zenith radiances

    NASA Astrophysics Data System (ADS)

    Fielding, M. D.; Chiu, J. C.; Hogan, R. J.; Feingold, G.; Eloranta, E.; O'Connor, E. J.; Cadeddu, M. P.

    2015-02-01

    Active remote sensing of marine boundary-layer clouds is challenging as drizzle drops often dominate the observed radar reflectivity. We present a new method to simultaneously retrieve cloud and drizzle vertical profiles in drizzling boundary-layer cloud using surface-based observations of radar reflectivity, lidar attenuated backscatter, and zenith radiances. Specifically, the vertical structure of droplet size and water content of both cloud and drizzle is characterised throughout the cloud. An ensemble optimal estimation approach provides full error statistics given the uncertainty in the observations. To evaluate the new method, we first perform retrievals using synthetic measurements from large-eddy simulation snapshots of cumulus under stratocumulus, where cloud water path is retrieved with an error of 31 g m-2. The method also performs well in non-drizzling clouds where no assumption of the cloud profile is required. We then apply the method to observations of marine stratocumulus obtained during the Atmospheric Radiation Measurement MAGIC deployment in the northeast Pacific. Here, retrieved cloud water path agrees well with independent 3-channel microwave radiometer retrievals, with a root mean square difference of 10-20 g m-2.

  15. Joint retrievals of cloud and drizzle in marine boundary layer clouds using ground-based radar, lidar and zenith radiances

    DOE PAGESBeta

    Fielding, M. D.; Chiu, J. C.; Hogan, R. J.; Feingold, G.; Eloranta, E.; O'Connor, E. J.; Cadeddu, M. P.

    2015-07-02

    Active remote sensing of marine boundary-layer clouds is challenging as drizzle drops often dominate the observed radar reflectivity. We present a new method to simultaneously retrieve cloud and drizzle vertical profiles in drizzling boundary-layer clouds using surface-based observations of radar reflectivity, lidar attenuated backscatter, and zenith radiances under conditions when precipitation does not reach the surface. Specifically, the vertical structure of droplet size and water content of both cloud and drizzle is characterised throughout the cloud. An ensemble optimal estimation approach provides full error statistics given the uncertainty in the observations. To evaluate the new method, we first perform retrievalsmore »using synthetic measurements from large-eddy simulation snapshots of cumulus under stratocumulus, where cloud water path is retrieved with an error of 31 g m-2. The method also performs well in non-drizzling clouds where no assumption of the cloud profile is required. We then apply the method to observations of marine stratocumulus obtained during the Atmospheric Radiation Measurement MAGIC deployment in the Northeast Pacific. Here, retrieved cloud water path agrees well with independent three-channel microwave radiometer retrievals, with a root mean square difference of 10–20 g m-2.« less

  16. Joint retrievals of cloud and drizzle in marine boundary layer clouds using ground-based radar, lidar and zenith radiances

    DOE PAGESBeta

    Fielding, M. D.; Chiu, J. C.; Hogan, R. J.; Feingold, G.; Eloranta, E.; O'Connor, E. J.; Cadeddu, M. P.

    2015-02-16

    Active remote sensing of marine boundary-layer clouds is challenging as drizzle drops often dominate the observed radar reflectivity. We present a new method to simultaneously retrieve cloud and drizzle vertical profiles in drizzling boundary-layer cloud using surface-based observations of radar reflectivity, lidar attenuated backscatter, and zenith radiances. Specifically, the vertical structure of droplet size and water content of both cloud and drizzle is characterised throughout the cloud. An ensemble optimal estimation approach provides full error statistics given the uncertainty in the observations. To evaluate the new method, we first perform retrievals using synthetic measurements from large-eddy simulation snapshots of cumulusmore »under stratocumulus, where cloud water path is retrieved with an error of 31 g m?2. The method also performs well in non-drizzling clouds where no assumption of the cloud profile is required. We then apply the method to observations of marine stratocumulus obtained during the Atmospheric Radiation Measurement MAGIC deployment in the northeast Pacific. Here, retrieved cloud water path agrees well with independent 3-channel microwave radiometer retrievals, with a root mean square difference of 10–20 g m?2.« less

  17. 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.

  18. 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.

  19. Cloud fraction, liquid and ice water contents derived from long-term radar, lidar, and microwave radiometer data are systematically compared to models to quantify and

    E-print Network

    Hogan, Robin

    Cloud fraction, liquid and ice water contents derived from long-term radar, lidar, and microwave a systematic evaluation of clouds in forecast models. Clouds and their associated microphysical processes for end users of weather forecasts, who may be interested not only in cloud cover, but in other variables

  20. 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.

  1. Cloud fraction, liquid and ice water contents derived from long-term radar, lidar, and microwave radiometer data are systematically compared to models to quantify and

    E-print Network

    Reading, University of

    Cloud fraction, liquid and ice water contents derived from long-term radar, lidar, and microwave determined by cloud properties, such as surface precipitation, temperatures, or shortwave/ultraviolet microwave limb sounding instruments (Li et al. 2005). But, satellite remotely sensed products have had

  2. 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.

  3. Retrieving stratocumulus drizzle parameters using Doppler radar and lidar EWAN J. O'CONNOR

    E-print Network

    Reading, University of

    falling below the base of stratocumulus clouds. The ratio of the radar to lidar backscatter power (LWF) in g m ¡ 2 s ¡ 1 and radar reflectivity (Z) in mm6 m ¡ 3: LWF ¢ 0£ 0093 Z 0¤ 69. This is validRetrieving stratocumulus drizzle parameters using Doppler radar and lidar EWAN J. O

  4. Using Radar, Lidar and Radiometer Data from NSA and SHEBA to Quantify Cloud Property Effects on the Surface Heat Budget in the Arctic

    SciTech Connect

    Janet Intrieri; Mathhew Shupe

    2005-01-01

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

  5. Cloud and Precipitation Radar

    NASA Astrophysics Data System (ADS)

    Hagen, Martin; Höller, Hartmut; Schmidt, Kersten

    Precipitation or weather radar is an essential tool for research, diagnosis, and nowcasting of precipitation events like fronts or thunderstorms. Only with weather radar is it possible to gain insights into the three-dimensional structure of thunderstorms and to investigate processes like hail formation or tornado genesis. A number of different radar products are available to analyze the structure, dynamics and microphysics of precipitation systems. Cloud radars use short wavelengths to enable detection of small ice particles or cloud droplets. Their applications differ from weather radar as they are mostly orientated vertically, where different retrieval techniques can be applied.

  6. A climatology of supercooled layer clouds from lidar ceilometer data Robin J. Hogan

    E-print Network

    Hogan, Robin

    and 35 GHz radar reflectivity through a supercooledlayer, with a simultaneoussnap shot from the cloud It was demonstrated during the Cloud Lidar And Radar Exper- iment (CLARE'98) that supercooled water in the atmosphereA climatology of supercooled layer clouds from lidar ceilometer data Robin J. Hogan Anthony J

  7. A climatology of supercooled layer clouds from lidar ceilometer data Robin J. Hogan # Anthony J. Illingworth

    E-print Network

    Hogan, Robin

    and 35 GHz radar reflectivity through a supercooledlayer, with a simultaneous snap shot from the cloud.J.Hogan@reading.ac.uk INTRODUCTION It was demonstrated during the Cloud Lidar And Radar Exper­ iment (CLARE'98) that supercooledA climatology of supercooled layer clouds from lidar ceilometer data Robin J. Hogan # Anthony J

  8. Fast Lidar and Radar Multiple-Scattering Models. Part I: Small-Angle Scattering Using the Photon VarianceCovariance Method

    E-print Network

    Hogan, Robin

    Fast Lidar and Radar Multiple-Scattering Models. Part I: Small-Angle Scattering Using the Photon. Introduction Lidar and radar have been used extensively from the ground to study clouds (Ackerman and Stokes in combined radar­lidar retrievals of ice clouds from space, the retrieved optical depth

  9. Evaluating forecasts of the evolution of the cloudy boundary layer using diurnal composites of radar and lidar observations

    E-print Network

    Reading, University of

    composited to reveal the mean diurnal variation of cloud top and base heights, cloud thickness and liquid forecasts of the evolution of the cloudy boundary layer using diurnal composites of radar and lidar boundary-layer cloud observations, made by radar and lidar, are composited over the diurnal cycle. Seven

  10. Weather Radars and Lidar for Observing the Atmosphere

    NASA Astrophysics Data System (ADS)

    (Vivek) Vivekanandan, J.

    2010-05-01

    The Earth Observing Laboratory (EOL) at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado develops and deploys state-of-the-art ground-based radar, airborne radar and lidar instruments to advance scientific understanding of the earth system. The ground-based radar (S-Pol) is equipped with dual-wavelength capability (S-band and Ka-band). S-Pol is the only transportable radar in the world. In order to capture faster moving weather events such as tornadoes and record observations of clouds over rugged mountainous terrain and ocean, an airborne radar (ELDORA) is used. It is the only airborne Doppler meteorological radar that is able to detect motions in the clear air. The EOL is in the process of building the first phase of a three phase dual wavelength W/Ka-band airborne cloud radar to be called the HIAPER Cloud Radar (HCR). This phase is a pod based W-band radar system with scanning capability. The second phase will add pulse compression and polarimetric capability to the W-band system, while the third phase will add complementary Ka-band radar. The pod-based radar is primarily designed to fly on the Gulfstream V (GV) and C-130 aircraft. The envisioned capability of a millimeter wave radar system on GV is enhanced by coordination with microwave radiometer, in situ probes, and especially by the NCAR GV High-Spectral Resolution Lidar (HSRL) which is also under construction. The presentation will describe the capabilities of current instruments and also planned instrumentation development.

  11. 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.

  12. The lidar dark band: An oddity of the radar bright band analogy

    SciTech Connect

    Sassen, K.

    1996-04-01

    Although much has sbeen learned from independent radar and lidar studies of atmospheric precipitations, occasionally supported by aircraft profiling, what has been lacking is combined optical, microwave, and insitu observations of the melting layer. Fortunately, the rainshowers on April 21, 1994, during the Remote Cloud Sensing intensive obervations Period (RCSIOP) at the Southern Great Plains Cloud and radiation Testbed (CART) site provided an opportunity for coordinated dual-wavelength University of Utah Polarization Diversity Lidar, University of Massachusetts Cloud Profiling Radar System Doppler Radar, and the University of North Dakota Citation aircraft measurements.

  13. The Characterization of Ice Cloud Properties from Doppler Radar Measurements JULIEN DELANO

    E-print Network

    Protat, Alain

    The Characterization of Ice Cloud Properties from Doppler Radar Measurements JULIEN DELANOË Centre an original method that is complementary to the radar­lidar algorithm method to characterize ice cloud properties. The method makes use of two measurements from a Doppler cloud radar (35 or 95 GHz), namely

  14. P3.10 ACCOUNTING FOR MULTIPLE SCATTERING IN SPACEBORNE RADAR AND LIDAR OBSERVATIONS

    E-print Network

    Hogan, Robin

    P3.10 ACCOUNTING FOR MULTIPLE SCATTERING IN SPACEBORNE RADAR AND LIDAR OBSERVATIONS ROBIN J. HOGAN", where echoes appear to originate from beyond the end of the cloud and even below the ground. Spaceborne scat- tering. For example, the technique of "off-beam lidar" uti- lizes a single laser transmitter

  15. 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

  16. Lidar Bacscatter Cross-Section Radar Bacscatter Cross-Section Mixed Phase

    E-print Network

    Eloranta, Edwin W.

    Lidar Bacscatter Cross-Section Radar Bacscatter Cross-Section Mixed Phase Lidar-Radar Effective Size Mixed Phase Effective Size Number Density Lidar Water BSCS Lidar Ice BSCS Radar Water BSCS Radar Ice BSCS Water Content Ice Phase Lidar-Radar Effective Size Ice Phase Effective Size Ice Number

  17. Fast Lidar and Radar Multiple-Scattering Models. Part II: Wide-Angle Scattering Using the Time-Dependent Two-Stream Approximation

    E-print Network

    Hogan, Robin

    Fast Lidar and Radar Multiple-Scattering Models. Part II: Wide-Angle Scattering Using the Time of the cloud. A similar effect occurs for spaceborne millimeter-wave radar observations of deep convective well in comparison to Monte Carlo calculations (for both radar and lidar) but is much more efficient

  18. 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.

  19. Using Continuous Ground-Based Radar and Lidar Measurements for Evaluating the Representation of Clouds in Four Operational Models

    E-print Network

    Protat, Alain

    of Clouds in Four Operational Models DOMINIQUE BOUNIOL,a ALAIN PROTAT,b,c JULIEN DELANOE¨ ,d JACQUES PELON The ability of four operational weather forecast models [ECMWF, Action de Recherche Petite Echelle Grande but a correct ice water content. The dataset is then divided into seasons to evaluate the potential

  20. Raman LIDAR Detection of Cloud Base

    NASA Technical Reports Server (NTRS)

    Demoz, Belay; Starr, David; Whiteman, David; Evans, Keith; Hlavka, Dennis; Peravali, Ravindra

    1999-01-01

    Advantages introduced by Raman lidar systems for cloud base determination during precipitating periods are explored using two case studies of light rain and virga conditions. A combination of the Raman lidar derived profiles of water vapor mixing ratio and aerosol scattering ratio, together with the Raman scattered signals from liquid drops, can minimize or even eliminate some of the problems associated with cloud boundary detection using elastic backscatter lidars.

  1. Combined Lidar-Radar Remote Sensing: Initial Results from CRYSTAL-FACE and Implications for Future Spaceflight Missions

    NASA Technical Reports Server (NTRS)

    McGill, Matthew J.; Li, Li-Hua; Hart, William D.; Heymsfield, Gerald M.; Hlavka, Dennis L.; Vaughan, Mark A.; Winker, David M.

    2003-01-01

    In the near future NASA plans to fly satellites carrying a multi-wavelength backscatter lidar and a 94-GHz cloud profiling radar in formation to provide complete global profiling of cloud and aerosol properties. The CRYSTAL-FACE field campaign, conducted during July 2002, provided the first high-altitude colocated measurements from lidar and cloud profiling radar to simulate these spaceborne sensors. The lidar and radar provide complementary measurements with varying degrees of measurement overlap. This paper presents initial results of the combined airborne lidar-radar measurements during CRYSTAL-FACE. The overlap of instrument sensitivity is presented, within the context of particular CRYSTAL-FACE conditions. Results are presented to quantify the portion of atmospheric profiles sensed independently by each instrument and the portion sensed simultaneously by the two instruments.

  2. Fast lidar and radar multiple-scattering models Part 2: Wide-angle scattering using the time-dependent two-stream approximation

    E-print Network

    Reading, University of

    . Atmos. Sci., October 2007 ABSTRACT Spaceborne lidar returns from liquid water clouds contain significant for spaceborne millimeter-wave radar observations of deep convective clouds. An efficient method is described penetrated, an effect known as "pulse stretching". This is particularly ev- ident for spaceborne cloud lidar

  3. Arctic multilayered, mixed-phase cloud processes revealed in millimeter-wave cloud radar Doppler spectra

    NASA Astrophysics Data System (ADS)

    Verlinde, Johannes; Rambukkange, Mahlon P.; Clothiaux, Eugene E.; McFarquhar, Greg M.; Eloranta, Edwin W.

    2013-12-01

    radar Doppler velocity spectra, lidar backscattering coefficients and depolarization ratios, and aircraft in situ measurements are used to investigate microphysical processes occurring in a case of multilayered, mixed-phase clouds over the North Slope of Alaska. Some liquid-cloud layers were observed to exist in well-mixed atmospheric layers, but others were found in absolutely stable atmospheric layers. The observations suggest that strong cloud top cooling was necessary to produce the well-mixed cloud layers; clouds shielded from radiative cooling by overlaying clouds more frequently existed in absolutely stable layers. The in situ measurements revealed that most liquid layers contained drizzle, the production process of which was shown from the radar and lidar measurements to have been interrupted only during heavier ice-precipitation events. Different layers interacted with one another by changing the radiative heating profile and by precipitation which changed the growth paths available to cloud particles and even initiated new hydrometeor classes.

  4. CLOUD FRACTION STATISTICS DERIVED FROM 2YEARS OF HIGH SPECTRAL RESOLUTION LIDAR DATA ACQUIRED AT EUREKA, CANADA.

    E-print Network

    Eloranta, Edwin W.

    CLOUD FRACTION STATISTICS DERIVED FROM 2YEARS OF HIGH SPECTRAL RESOLUTION LIDAR DATA ACQUIRED(AHSRL) and the NOAA 8.6 mm wavelength cloud radar (MMCR). Both instruments have operated nearly continuously since Sept 2005. This paper presents a record of cloud cover, cloud altitude and cloud phase derived

  5. Drizzle Droplet Size Estimation Using High Spectral Resolution LIDAR and Millimeter Radar Data

    NASA Astrophysics Data System (ADS)

    Eloranta, E. W.; Bartholomew, M. J.; Bharadwaj, N.

    2013-12-01

    High spectral resolution lidar(HSRL) provides calibrated measurement of optical extinction that can be used with millimeter wavelength radar to provide a measure of drizzle droplet size. The strengths and limitations of the this approach are examined using a combination of HSRL, KAZR radar and disdrometer data acquired during the MAGIC deployment of the DOE AMF2 mobile facility. Data was collected on a ship during multiple trips between Long Beach, CA an Honolulu, HI. Lidar-radar particle size estimations are typically based on the assumption of a mono-modal size distribution. The multi-mode particle size distributions that exist in clouds where drizzle co-exists with cloud droplets yield lidar-radar size estimates that are not characteristic of either distribution. A similar problem is encountered in the sub-cloud layer where aerosol scattering co-exists with drizzle. This paper examines the possibility of using aerosol scattering measured outside the drizzle shafts to correct for aerosol contributions and compares the lidar-radar drizzle derived particle sizes with disdrometer measurements.

  6. Lidar and Radar Measurements of the melting layer in the frame of the Convective and Orographically-induced Precipitation Study

    NASA Astrophysics Data System (ADS)

    Di Girolamo, Paolo; Summa, Donato; Bhawar, Rohini; Di Iorio, Tatiana; Vaughan, Geraint; Norton, Emily; Peters, Gerhard

    2009-03-01

    During the Convective and Orographically-induced Precipitation Study (COPS), lidar dark bands were observed by the Univ. of BASILicata Raman lidar system (BASIL) on several IOPs and SOPs (among others, 23 July, 15 August, 17 August). Dark band signatures appear in the lidar measurements of particle backscattering at 355, 532 and 1064 nm and particle extinction at 355 and 532 nm, as well as in particle depolarization measurements. Lidar data are 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 Radio UHF clear air wind profiler (1.29 GHz). Results from BASIL and the radars are illustrated and discussed to support in the comprehension of the microphysical and scattering processes responsible for the appearance of the lidar dark band and radar bright band.

  7. THOR: Cloud Thickness from Off beam Lidar Returns

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; McGill, Matthew; Kolasinski, John; Varnai, Tamas; Yetzer, Ken

    2004-01-01

    Conventional wisdom is that lidar pulses do not significantly penetrate clouds having optical thickness exceeding about tau = 2, and that no returns are detectable from more than a shallow skin depth. Yet optically thicker clouds of tau much greater than 2 reflect a larger fraction of visible photons, and account for much of Earth s global average albedo. As cloud layer thickness grows, an increasing fraction of reflected photons are scattered multiple times within the cloud, and return from a diffuse concentric halo that grows around the incident pulse, increasing in horizontal area with layer physical thickness. The reflected halo is largely undetected by narrow field-of-view (FoV) receivers commonly used in lidar applications. THOR - Thickness from Off-beam Returns - is an airborne wide-angle detection system with multiple FoVs, capable of observing the diffuse halo, detecting wide-angle signal from which physical thickness of optically thick clouds can be retrieved. In this paper we describe the THOR system, demonstrate that the halo signal is stronger for thicker clouds, and validate physical thickness retrievals for clouds having z > 20, from NASA P-3B flights over the Department of Energy/Atmospheric Radiation Measurement/Southern Great Plains site, using the lidar, radar and other ancillary ground-based data.

  8. Lidar

    NASA Technical Reports Server (NTRS)

    Collis, R. T. H.

    1969-01-01

    Lidar is an optical radar technique employing laser energy. Variations in signal intensity as a function of range provide information on atmospheric constituents, even when these are too tenuous to be normally visible. The theoretical and technical basis of the technique is described and typical values of the atmospheric optical parameters given. The significance of these parameters to atmospheric and meteorological problems is discussed. While the basic technique can provide valuable information about clouds and other material in the atmosphere, it is not possible to determine particle size and number concentrations precisely. There are also inherent difficulties in evaluating lidar observations. Nevertheless, lidar can provide much useful information as is shown by illustrations. These include lidar observations of: cirrus cloud, showing mountain wave motions; stratification in clear air due to the thermal profile near the ground; determinations of low cloud and visibility along an air-field approach path; and finally the motion and internal structure of clouds of tracer materials (insecticide spray and explosion-caused dust) which demonstrate the use of lidar for studying transport and diffusion processes.

  9. 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.

  10. 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).

  11. 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.

  12. A Variational Method to Retrieve the Extinction Profile in Liquid Clouds Using Multiple Field-of-View Lidar

    NASA Technical Reports Server (NTRS)

    Pounder, Nicola L.; Hogan, Robin J.; Varnai, Tamas; Battaglia, Alessandro; Cahalan, Robert F.

    2011-01-01

    While liquid clouds playa very important role in the global radiation budget, it's been very difficult to remotely determine their internal cloud structure. Ordinary lidar instruments (similar to radars but using visible light pulses) receive strong signals from such clouds, but the information is limited to a thin layer near the cloud boundary. Multiple field-of-view (FOV) lidars offer some new hope as they are able to isolate photons that were scattered many times by cloud droplets and penetrated deep into a cloud before returning to the instrument. Their data contains new information on cloud structure, although the lack of fast simulation methods made it challenging to interpret the observations. This paper describes a fast new technique that can simulate multiple-FOV lidar signals and can even estimate the way the signals would change in response to changes in cloud properties-an ability that allows quick refinements in our initial guesses of cloud structure. Results for a hypothetical airborne three-FOV lidar suggest that this approach can help determine cloud structure for a deeper layer in clouds, and can reliably determine the optical thickness of even fairly thick liquid clouds. The algorithm is also applied to stratocumulus observations by the 8-FOV airborne "THOR" lidar. These tests demonstrate that the new method can determine the depth to which a lidar provides useful information on vertical cloud structure. This work opens the way to exploit data from spaceborne lidar and radar more rigorously than has been possible up to now.

  13. Lidar cloud studies for FIRE and ECLIPS

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    Optical remote sensing measurements of cirrus cloud properties were collected by one airborne and four ground-based lidar systems over a 32 h period during this case study from the First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment (FIRE) Intensive Field Observation (IFO) program. The lidar systems were variously equipped to collect 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. The cirrus cloud types include: dissipating subvisual and thin fibrous cirrus cloud bands, an isolated mesoscale uncinus complex (MUC), 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. Although the cirrus frequently developed in the vertical from particle fall-streaks emanating from generating regions at or near cloud tops, glaciating supercooled (-30 to -35 C) altocumulus clouds contributed to the production of ice mass at the base of the deep cirrus cloud, apparently even through riming, and other mechanisms involving evaporation, wave motions, and radiative effects are indicated. The generating regions ranged in scale from approximately 1.0 km cirrus uncinus cells, to organized MUC structures up to approximately 120 km across.

  14. 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.

  15. An improved model for snowfall measurement using lidar and radar Lidar Backscatter Cross Section ~ number density * Radar Backscatter Cross Section ~ number density * Radar Doppler Velocity ~ f( mass, projected area, air density)

    E-print Network

    Eloranta, Edwin W.

    An improved model for snowfall measurement using lidar and radar Lidar Backscatter Cross Section ~ number density * Radar Backscatter Cross Section ~ number density * Radar 4 24 4 Radar backscatter cross section De '= 3 k2 P(180) * Lidar backscatter cross section Ed

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

    E-print Network

    Cho, John Y. N.

    Upgraded Doppler Rayleigh Lidar and Comparisonswith Stratospheric Radar: 1: Observations Following and aerosol layers with complementary stratosphere/troposphere (ST) radar wind profiles. These observationsfollowedthe initial stage of a Doppler Rayleigh lidar system upgrade. These initial observations were made

  17. 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.

  18. Spaceborne lidar measurement accuracy - Simulation of aerosol, cloud, molecular density, and temperature retrievals

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Morley, B. M.; Browell, E. V.

    1982-01-01

    In connection with studies concerning the use of an orbiting optical radar (lidar) to conduct aerosol and cloud measurements, attention has been given to the accuracy with which lidar return signals could be measured. However, signal-measurement error is not the only source of error which can affect the accuracy of the derived information. Other error sources are the assumed molecular-density and atmospheric-transmission profiles, and the lidar calibration factor (which relates signal to backscatter coefficient). The present investigation has the objective to account for the effects of all these errors sources for several realistic combinations of lidar parameters, model atmospheres, and background lighting conditions. In addition, a procedure is tested and developed for measuring density and temperature profiles with the lidar, and for using the lidar-derived density profiles to improve aerosol retrievals.

  19. Impact of clouds on aerosol scattering as observed by lidar

    E-print Network

    Oxford, University of

    distribution. Lidars most commonly estimate the aerosol backscatter coefficient, , being the cross-section]. Observation with lidar Lidar is an active remote sensing technique, conceptually similar to radar, that monitors the light backscattered from a laser beam. The height of the scattering feature is calculated from

  20. 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.

  1. Forest Biomass Mapping From Lidar and Radar Synergies

    NASA Technical Reports Server (NTRS)

    Sun, Guoqing; Ranson, K. Jon; Guo, Z.; Zhang, Z.; Montesano, P.; Kimes, D.

    2011-01-01

    The use of lidar and radar instruments to measure forest structure attributes such as height and biomass at global scales is being considered for a future Earth Observation satellite mission, DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice). Large footprint lidar makes a direct measurement of the heights of scatterers in the illuminated footprint and can yield accurate information about the vertical profile of the canopy within lidar footprint samples. Synthetic Aperture Radar (SAR) is known to sense the canopy volume, especially at longer wavelengths and provides image data. Methods for biomass mapping by a combination of lidar sampling and radar mapping need to be developed. In this study, several issues in this respect were investigated using aircraft borne lidar and SAR data in Howland, Maine, USA. The stepwise regression selected the height indices rh50 and rh75 of the Laser Vegetation Imaging Sensor (LVIS) data for predicting field measured biomass with a R(exp 2) of 0.71 and RMSE of 31.33 Mg/ha. The above-ground biomass map generated from this regression model was considered to represent the true biomass of the area and used as a reference map since no better biomass map exists for the area. Random samples were taken from the biomass map and the correlation between the sampled biomass and co-located SAR signature was studied. The best models were used to extend the biomass from lidar samples into all forested areas in the study area, which mimics a procedure that could be used for the future DESDYnI Mission. It was found that depending on the data types used (quad-pol or dual-pol) the SAR data can predict the lidar biomass samples with R2 of 0.63-0.71, RMSE of 32.0-28.2 Mg/ha up to biomass levels of 200-250 Mg/ha. The mean biomass of the study area calculated from the biomass maps generated by lidar- SAR synergy 63 was within 10% of the reference biomass map derived from LVIS data. The results from this study are preliminary, but do show the potential of the combined use of lidar samples and radar imagery for forest biomass mapping. Various issues regarding lidar/radar data synergies for biomass mapping are discussed in the paper.

  2. 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, A. P.

    2015-01-01

    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 (MC) 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 (LES) 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.

  3. 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.

  4. Characterization of Cirrus Cloud Properties by Airborne Differential Absorption and High Spectral Resolution Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Ehret, G.; Gross, S.; Schäfler, A.; Wirth, M.; Fix, A.; Kiemle, C.

    2014-12-01

    Despite the large impact of cirrus clouds on the Earth's climate system, their effects are still only poorly understood. Our knowledge of the climate effect of cirrus clouds is mainly based on theoretical simulations using idealized cloud structure and microphysics, as well as radiative transfer approximations. To improve the representation of cirrus clouds in idealized simulations and circulation models, we need a better understanding of the micro- and macrophysical properties of cirrus clouds. Airborne lidar measurements provide two-dimensional information of the atmospheric structure, and are thus a suitable tool to study the fine-structure of cirrus clouds, as well as their macrophysical properties. Aerosol and water vapor was measured with the airborne high spectral resolution lidar (HSRL) and differential absorption lidar (DIAL) system WALES of the German Aerospace Center (DLR), Oberpfaffenhofen. The system was operated onboard the German high altitude and long range research aircraft HALO during the Next-generation remote sensing for validation studies campaign (NARVAL) in December 2013 over the tropical North-Atlantic and in January 2014 out of Iceland, and during the ML-Cirrus campaign in March/April 2014 over Central and Southern Europe. During NARVAL 18 flights with more than 110 flight hours were performed providing a large number of cirrus cloud overpasses with combined lidar and radar instrumentation. In the framework of the ML-Cirrus campaign 17 flights with more than 80 flight hours were performed to characterize cirrus cloud properties in different environmental conditions using a combination of remote sensing (e.g. lidar) and in-situ observations. In our presentation we will give a general overview of the campaigns and of the WALES measurements. We will show first results from the aerosol and water vapor lidar measurements with focus on the structure of cirrus clouds, the humidity distribution within and outside the cloud and on the impact of the stage of evolution on the cirrus cloud properties.

  5. Comparison of meteor radar and Na Doppler lidar measurements of winds in the mesopause region

    E-print Network

    Chu, Xinzhao

    Comparison of meteor radar and Na Doppler lidar measurements of winds in the mesopause region above 29 January 2005. [1] Simultaneous sodium (Na) Doppler lidar and meteor radar measurements/s at altitudes below 96 km. This is smaller than the RMS differences observed in a previous Na lidar and meteor

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

    SciTech Connect

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

    2011-02-16

    [1] 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 (Dupont et al., 2009). 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 20 cloud optical thickness larger than 3. In this study, 10-years of backscatter lidar signal data are analysed by a unique algorithm called STRucture of ATmosphere (STRAT, Morille et al., 2007). We apply the STRAT algorithm to data from both the collocated Micropulse lidar (MPL) and a Raman lidar (RL) at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site between 1998 and 2009. Raw backscatter lidar signal is processed and 25 corrections for detector deadtime, afterpulse, and overlap are applied. (Campbell et al.) 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 30 and (2) to estimate the discrepancies induced by the two remote sensing systems (pulse energy, sampling, resolution, etc.). Our first results tend to show that the MPLs, which are the primary ARM lidars, have a distinctly limited range where all of these cloud properties are detectable, especially cloud top and cloud thickness, but even actual cloud base especially 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 MPLderived 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 5 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 10 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 the Long et al. (2006) cloud fraction calculation derived from radiative flux analysis.

  7. Evaluation of airborne radar-lidar retrieval of ice water content using in-situ probes

    NASA Astrophysics Data System (ADS)

    Khanal, Sujan

    Cloud water content and how that water is distributed across hydrometeors are fundamental cloud microphysical properties that influence cloud dynamical and radiative properties. This study utilizes in-situ and remote sensing data collected by the University of Wyoming King Air research aircraft during the Colorado Airborne Multi-phase Cloud Study, 2010-2011 (CAMPS) field campaign to study the reliability of different cloud water content measuring instruments. It has been shown in several previous studies and again demonstrated here from the CAMPS dataset that Forward Scattering Spectrometer Probe (FSSP) measurements are subject to contamination by shattering artifacts in ice and mixed phase clouds. Contaminated measurements from CAMPS show a significant overestimation of large (D > 28 microm) particles and derived liquid water content (LWC). A new approach is developed to characterize, quantify and correct the shattering contribution in FSSP measurements using ice particle information measured by an OAP cloud probe (2D-C). Comparisons with cloud droplet probe (CDP) measurements show that this new approach adequately corrects for ice shattering effects. This new approach can also be applied to standard FSSP historical datasets. These studies may have erroneous conclusions that can be re-evaluated based on this new correction. University of Colorado closed-path tunable diode laser hygrometer (CLH) total water measurements are used to develop a mass-length relationship for CAMPS dataset to calculate ice water content (IWC) from 2D-C size distribution. Then, these well characterized in-situ instruments are used to evaluate IWC retrievals from combined radar and lidar measurements. Comparison of near flight level remote sensing IWC retrievals with in-situ measurements indicates statistically reasonable agreements (difference in mean values about 33%) providing confidence on the retrieved vertical IWC profile. The collocated airborne radar-lidar measurements combined with in-situ measurements provide detailed information about cloud microphysical and radiative properties. These properties can be used to develop and improve cloud parameterizations in numerical models.

  8. 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

    -funded 1998 Cloud Lidar And Radar Experiment. Radar-lidar and dual-wavelength radar tech- niques were used 2 ), these clouds caused a significant increase in the reflection of solar radiation to space, even the 1998 Cloud Lidar And Radar Experiment (CLARE'98) has been used to demonstrate that the combination

  9. LIDAR AND RADAR INVESTIGATION OF INERTIA GRAVITY WAVE INTRINSIC PROPERTIES AT MCMURDO, ANTARCTICA

    E-print Network

    Chu, Xinzhao

    LIDAR AND RADAR INVESTIGATION OF INERTIA GRAVITY WAVE INTRINSIC PROPERTIES AT MCMURDO, ANTARCTICA radar wind. The observed wave period is ~7.15 h and the vertical wavelength is ~20 km. With simultaneous, there have been observations of IGWs using lidars [2, 3] and incoherent scatter radar [4]. Similarly, large

  10. 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

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

    SciTech Connect

    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 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.

  12. First radar echoes from cumulus clouds

    NASA Technical Reports Server (NTRS)

    Knight, Charles A.; Miller, L. J.

    1993-01-01

    In attempting to use centimeter-wavelength radars to investigate the early stage of precipitation formation in clouds, 'mantle echoes' are rediscovered and shown to come mostly from scattering by small-scale variations in refractive index, a Bragg kind of scattering mechanism. This limits the usefulness of single-wavelength radar for studies of hydrometeor growth, according to data on summer cumulus clouds in North Dakota, Hawaii, and Florida, to values of reflectivity factor above about 10 dBZe with 10-cm radar, 0 dBZe with 5-cm radar, and -10 dBZe with 3-cm radar. These are limits at or above which the backscattered radar signal from the kinds of clouds observed can be assumed to be almost entirely from hydrometeors or (rarely) other particulate material such as insects. Dual-wavelength radar data can provide the desired information about hydrometeors at very low reflectivity levels if assumptions can be made about the inhomogeneities responsible for the Bragg scattering. The Bragg scattering signal itself probably will be a useful way to probe inhomogeneities one-half the radar wavelength in scale for studying cloud entrainment and mixing processes. However, this use is possible only before scattering from hydrometeors dominates the radar return.

  13. Particle Size Measurements Using Data from a High Spectral Resolution Lidar and a Millimeter Wavelength Radar

    E-print Network

    Eloranta, Edwin W.

    ). The lidar and radar backscatter cross sections are used to derive: 9 Deff prime provides measurements of the backscatter cross section, extinction cross section,and depolarization cross section D ~ (------------------------------------------ )1/4 eff prime Lidar scattering cross

  14. Amplification of radar and lidar signatures using quantum sensors

    NASA Astrophysics Data System (ADS)

    Lanzagorta, Marco

    2013-05-01

    One of the major scientific thrusts from recent years has been to try to harness quantum phenomena to dramat­ ically increase the performance of a wide variety of classical devices. These advances in quantum information science have had a considerable impact on the development of photonic-based quantum sensors. Even though quantum radar and quantum lidar remain theoretical proposals, preliminary results suggest that these sensors have the potential of becoming disruptive technologies able to revolutionize reconnaissance systems. In this paper we will discuss how quantum entanglement can be exploited to increase the radar and lidar signature of rectangular targets. In particular, we will show how the effective visibility of the target is increased if observed with an entangled multi-photon quantum sensor.

  15. Lidar ratio and depolarization ratio for cirrus clouds.

    PubMed

    Chen, Wei-Nai; Chiang, Chih-Wei; Nee, Jan-Bai

    2002-10-20

    We report on studies of the lidar and the depolarization ratios for cirrus clouds. The optical depth and effective lidar ratio are derived from the transmission of clouds, which is determined by comparing the backscattering signals at the cloud base and cloud top. The lidar signals were fitted to a background atmospheric density profile outside the cloud region to warrant the linear response of the return signals with the scattering media. An average lidar ratio, 29 +/- 12 sr, has been found for all clouds measured in 1999 and 2000. The height and temperature dependences ofthe lidar ratio, the optical depth, and the depolarization ratio were investigated and compared with results of LITE and PROBE. Cirrus clouds detected near the tropopause are usually optically thin and mostly subvisual. Clouds with the largest optical depths were found near 12 km with a temperature of approximately -55 degrees C. The multiple-scattering effect is considered for clouds with high optical depths, and this effect lowers the lidar ratios compared with a single-scattering condition. Lidar ratios are in the 20-40 range for clouds at heights of 12.5-15 km and are smaller than approximately 30 in height above 15 km. Clouds are usually optically thin for temperatures below approximately -65 degrees C, and in this region the optical depth tends to decrease with height. The depolarization ratio is found to increase with a height at 11-15 km and smaller than 0.3 above 16 km. The variation in the depolarization ratio with the lidar ratio was also reported. The lidar and depolarization ratios were discussed in terms of the types of hexagonal ice crystals. PMID:12396200

  16. 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.

  17. Lidar point cloud representation of canopy structure for biomass estimation

    NASA Astrophysics Data System (ADS)

    Neuenschwander, A. L.; Krofcheck, D. J.; Litvak, M. E.

    2014-12-01

    Laser mapping systems (lidar) have become an essential remote sensing tool for determining local and regional estimates of biomass. Lidar data (possibly in conjunction with optical imagery) can be used to segment the landscape into either individual trees or clusters of trees. Canopy characteristics (i.e. max, mean height) for a segmented tree are typically derived from a rasterized canopy height model (CHM) and subsequently used in a regression model to estimate biomass. The process of rasterizing the lidar point cloud into a CHM, however, reduces the amount information about the tree structure. Here, we compute statistics for each segmented tree from the raw lidar point cloud rather than a rasterized CHM. Working directly from the lidar point cloud enables a more accurate representation of the canopy structure. Biomass estimates from the point cloud method are compared against biomass estimates derived from a CHM for a Juniper savanna in New Mexico.

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

    E-print Network

    Chu, Xinzhao

    Inertia-gravity waves in Antarctica: A case study using simultaneous lidar and radar measurements in Antarctica: A case study using simultaneous lidar and radar measurements at McMurdo/Scott Base (77.8 S, 166

  19. 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.

  20. Rapidly tunable millimeter-wave Optical transmitter for Lidar-Radar Y. Li, A. J. C. Vieira+

    E-print Network

    Herczfeld, Peter

    laser, electro-optic modulation, frequency chirped lidar-radar, fiber radio. #12;2 I. INTRODUCTION rapidly tunable microchip laser for sophisticated frequency chirped lidar-radar technique. To obtain1 Rapidly tunable millimeter-wave Optical transmitter for Lidar-Radar Y. Li, A. J. C. Vieira+ , S

  1. 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.

  2. The DROPPS Program: A Rocket/Lidar/Radar Study of the Polar Summer Mesosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Holzworth, R. H.; Schmidlin, F. J.; Voss, H. D.; Tuzzolino, A. J.; Croskey, C. L.; Mitchell, J. D.; vonZhan, U.; Singer, W.

    1999-01-01

    During July of 1999, two sequences of rockets were launched from the Norwegian rocket range in Andoya, Norway. The purpose of these studies was to investigate the properties of the polar summer mesosphere, particularly relating to polar mesospheric summer echoes (PMSE) and their possible relationship to noctilucent clouds (NLC). Each of two sequences was anchored with a DROPPS Black Brant payload, consisting of 20 instruments to measure the electrodynamic and optical structure of the mesosphere and lower thermosphere. These were provided by participants from five American and two European scientific laboratories. The DROPPS (Distribution and Role of Particles in the Polar Summer) payloads were each accompanied by a sequence of meteorological rockets, and by several European payloads designed to study electrodynamics structure of the same region. ALOMAR (Arctic Lidar Observatory for Middle Atmosphere Research) Lidars, and MF (Medium Frequency) and MST (Mesosphere, Stratosphere, and Troposphere) Radars were used to continuously monitor the mesosphere for NLCs and PMSEs respectively. EISCAT VHF (European Incoherent Scatter Radar Very High Frequency) radar provided similar information about PMSEs downstream from the launch site. Sequence 1 was launched on the night of 5-6 July into a strong PMSE display coupled with a weak NLC at the low end of the PMSE. Sequence 2 was launched on the early morning of 14 July into a strong NLC with no PMSE evident. Here we describe the details of the program along with preliminary results.

  3. Quantification of Cloud Microphysical Parameterization Uncertainty Using Radar Reflectivity

    E-print Network

    Miami, University of

    Quantification of Cloud Microphysical Parameterization Uncertainty Using Radar Reflectivity MARCUS. An inversion is per- formed on 10 microphysical parameters using radar reflectivity observations. The results of this study show that radar reflectivity ob- servations, as expected, provide a much stronger

  4. Cloud radar Doppler spectra in drizzling stratiform clouds: 2. Observations and microphysical modeling of drizzle evolution

    E-print Network

    Cloud radar Doppler spectra in drizzling stratiform clouds: 2. Observations and microphysical I, the influence of cloud microphysics and dynamics on the shape of cloud radar Doppler spectra in warm stratiform clouds was discussed. The traditional analysis of radar Doppler moments was extended

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

    E-print Network

    Geerts, Bart

    Threshold radar reflectivity for drizzling clouds Yangang Liu,1 Bart Geerts,2 Mark Miller,2 Peter cloud to rain when the radar reflectivity exceeds some value (threshold reflectivity) but also reveals. Daum, and R. McGraw (2008), Threshold radar reflectivity for drizzling clouds, Geophys. Res. Lett., 35

  6. 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 to compare models with observations contains advantages and challenges. Radar Doppler spectra simulators model output with the Doppler spectra recorded from the vertically pointing cloud radars at the ARM

  7. Lidar-radar synergy for characterizing properties of ultragiant volcanic aerosol

    NASA Astrophysics Data System (ADS)

    Madonna, F.; Amodeo, A.; D'Amico, G.; Giunta, A.; Mona, L.; Pappalardo, G.

    2011-12-01

    The atmospheric aerosol has a relevant effect on our life influencing climate, aviation safety, air quality and natural hazards. The identification of aerosol layers through inspection of continuous measurements is strongly recommended for quantifying their contribution to natural hazards and air quality and to establish suitable alerting systems. In particular, the study of ultragiant aerosols may improve the knowledge of physical-chemical processes underlying the aerosol-cloud interactions and the effect of giant nuclei as a potential element to expedite the warm-rain process. Moreover, the identification and the characterization of ultragiant aerosols may strongly contribute to quantify their impact on human health and their role in airplane engine damages or in visibility problems, especially in case of extreme events as explosive volcanic eruptions. During spring 2010, volcanic aerosol layers coming from Eyjafjallajökull volcano were observed over most of the European countries, using lidar technique. From 19 April to 19 May 2010, they were also observed at CNR-IMAA Atmospheric Observatory (CIAO) with the multi-wavelength Raman lidar systems of the Potenza EARLINET station (40.60N, 15.72E, 760 m a.s.l), Southern Italy. During this period, ultragiant aerosol were also observed at CIAO using a co-located Ka-band MIRA-36 Doppler microwave radar operating at 8.45 mm (35.5 GHz). The Ka-band radar observed in four separate days (19 April, 7, 10, 13 May) signatures consistent with the observations of non-spherical ultragiant aerosol characterized by anomalous values of linear depolarization ratio higher than -4 dB, probably related to the occurrence of multiple effects as particle alignment and presence of an ice coating. 7-days backward trajectory analysis shows that the air masses corresponding to the ultragiant aerosol observed by the radar were coming from the Eyjafjallajökull volcano area. Only in one case the trajectories do not come directly from Iceland, but from Central Europe where many lidar observations confirm the presence of volcanic aerosol in the previous days. Therefore, both CIAO lidar observations and the backtrajectory analysis suggests a volcanic origin of the ultragiant aerosol observed by the radar, revealing that these particles might have travelled for more than 4000 km after their injection into the atmosphere. The reported observation fostered a study, reported in this work, about the performances of multi-wavelength Raman lidars in the identification and the characterization of ultragiant aerosols layers in the troposphere. Results from simulations using Mie, T-Matrix and ray-tracing codes will be presented and compared with the observations performed in April-May 2010 during the Eyjafjallajökull eruption. Sensitivity ranges in detection of aerosol layer are pointed out in terms of experimental limits of both lidar and radar techniques and of aerosol optical depth. Moreover, recommendations for use of a combined lidar-radar approach for the aerosol typing and for the retrieval of their microphysical properties are reported.

  8. Cloud Thickness from Diffusion of Lidar Pulses in Clouds

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Davis, A.; McGill, Matthew

    1999-01-01

    Measurements of the distribution of reflected light from a laser beam incident on an aqueous suspension of particles or "cloud" with known thickness and particle size distribution are reported. The distribution is referred to as the "cloud radiative Green's function", G. In the diffusion domain, G is sensitive to cloud thickness, allowing that important quantity to be retrieved. The goal of the laboratory simulation is to provide preliminary estimates of sensitivity of G to cloud thickness,for use in the optimal design of an offbeam Lidar instrument for remote sensing of cloud thickness (THOR, Thickness from Offbeam Returns). These clouds of polystyrene microspheres suspended in water are analogous to real clouds of water droplets suspended in air. The microsphere size distribution is roughly lognormal, from 0.5 microns to 25 microns, similar to real clouds. Density of suspended spheres is adjusted so mean-free-path of visible photons is about 10 cm, approximately 1000 times smaller than in real clouds. The light source is a ND:YAG laser at 530 nm. Detectors are flux and photon-counting Photomultiplier Tube (PMTS), with a glass probe for precise positioning. A Labview 5 VI controls positioning, and data acquisition, via an NI Motion Control board connected to a stepper motor driving an Edmund linear slider, and a 16-channel 16-bit NI-DAQ board. The stepper motor is accurate to 10 microns, and step size is selectable from the VI software. Far from the incident beam, the rate of exponential increase as the direction of the incident beam is approached scales as expected from diffusion theory, linearly with the cloud thickness, and inversely as the square root of the reduced optical thickness, and is independent of particle size. Near the beam the signal begins to increase faster than exponential, due to single and low-order scattering near the backward direction, and here the distribution depends on particle size. Results are being used to verify 3D Monte Carlo radiative transfer simulations, used to estimate signal-to-noise ratios for remotely sensed off beam returns, for both homogeneous and inhomogeneous clouds. Signal-to-noise estimates show that unfiltered observations are straight forward at night, while narrow band pass filters are being studied for day.

  9. CloudSat as a Global Radar Calibrator

    SciTech Connect

    Protat, Alain; Bouniol, Dominique; O'Connor, E. J.; Baltink, Henk K.; Verlinde, J.; Widener, Kevin B.

    2011-03-01

    The calibration of the CloudSat spaceborne cloud radar has been thoroughly assessed using very accurate internal link budgets before launch, comparisons with predicted ocean surface backscatter at 94 GHz, direct comparisons with airborne cloud radars, and statistical comparisons with ground-based cloud radars at different locations of the world. It is believed that the calibration of CloudSat is accurate to within 0.5 to 1 dB. In the present paper it is shown that an approach similar to that used for the statistical comparisons with ground-based radars can now be adopted the other way around to calibrate other ground-based or airborne radars against CloudSat and / or detect anomalies in long time series of ground-based radar measurements, provided that the calibration of CloudSat is followed up closely (which is the case). The power of using CloudSat as a Global Radar Calibrator is demonstrated using the Atmospheric Radiation Measurement cloud radar data taken at Barrow, Alaska, the cloud radar data from the Cabauw site, The Netherlands, and airborne Doppler cloud radar measurements taken along the CloudSat track in the Arctic by the RASTA (Radar SysTem Airborne) cloud radar installed in the French ATR-42 aircraft for the first time. It is found that the Barrow radar data in 2008 are calibrated too high by 9.8 dB, while the Cabauw radar data in 2008 are calibrated too low by 8.0 dB. The calibration of the RASTA airborne cloud radar using direct comparisons with CloudSat agrees well with the expected gains and losses due to the change in configuration which required verification of the RASTA calibration.

  10. A Wing Pod-based Millimeter Wave Cloud Radar on HIAPER

    NASA Astrophysics Data System (ADS)

    Vivekanandan, Jothiram; Tsai, Peisang; Ellis, Scott; Loew, Eric; Lee, Wen-Chau; Emmett, Joanthan

    2014-05-01

    One of the attractive features of a millimeter wave radar system is its ability to detect micron-sized particles that constitute clouds with lower than 0.1 g m-3 liquid or ice water content. Scanning or vertically-pointing ground-based millimeter wavelength radars are used to study stratocumulus (Vali et al. 1998; Kollias and Albrecht 2000) and fair-weather cumulus (Kollias et al. 2001). Airborne millimeter wavelength radars have been used for atmospheric remote sensing since the early 1990s (Pazmany et al. 1995). Airborne millimeter wavelength radar systems, such as the University of Wyoming King Air Cloud Radar (WCR) and the NASA ER-2 Cloud Radar System (CRS), have added mobility to observe clouds in remote regions and over oceans. Scientific requirements of millimeter wavelength radar are mainly driven by climate and cloud initiation studies. Survey results from the cloud radar user community indicated a common preference for a narrow beam W-band radar with polarimetric and Doppler capabilities for airborne remote sensing of clouds. For detecting small amounts of liquid and ice, it is desired to have -30 dBZ sensitivity at a 10 km range. Additional desired capabilities included a second wavelength and/or dual-Doppler winds. Modern radar technology offers various options (e.g., dual-polarization and dual-wavelength). Even though a basic fixed beam Doppler radar system with a sensitivity of -30 dBZ at 10 km is capable of satisfying cloud detection requirements, the above-mentioned additional options, namely dual-wavelength, and dual-polarization, significantly extend the measurement capabilities to further reduce any uncertainty in radar-based retrievals of cloud properties. This paper describes a novel, airborne pod-based millimeter wave radar, preliminary radar measurements and corresponding derived scientific products. Since some of the primary engineering requirements of this millimeter wave radar are that it should be deployable on an airborne platform, occupy minimum cabin space and maximize scan coverage, a pod-based configuration was adopted. Currently, the radar system is capable of collecting observations between zenith and nadir in a fixed scanning mode. Measurements are corrected for aircraft attitude changes. The near-nadir and zenith pointing observations minimize the cross-track Doppler contamination in the radial velocity measurements. An extensive engineering monitoring mechanism is built into the recording system status such as temperature, pressure, various electronic components' status and receiver characteristics. Status parameters are used for real-time system stability estimates and correcting radar system parameters. The pod based radar system is mounted on a modified Gulfstream V aircraft, which is operated and maintained by the National Center for Atmospheric Research (NCAR) on behalf of the National Science Foundation (NSF). The aircraft is called the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) (Laursen et al., 2006). It is also instrumented with high spectral resolution lidar (HSRL) and an array of in situ and remote sensors for atmospheric research. As part of the instrument suite for HIAPER, the NSF funded the development of the HIAPER Cloud Radar (HCR). The HCR is an airborne, millimeter-wavelength, dual-polarization, Doppler radar that serves the atmospheric science community by providing cloud remote sensing capabilities for the NSF/NCAR G-V (HIAPER) aircraft. An optimal radar configuration that is capable of maximizing the accuracy of both qualitative and quantitative estimated cloud microphysical and dynamical properties is the most attractive option to the research community. The Technical specifications of cloud radar are optimized for realizing the desired scientific performance for the pod-based configuration. The radar was both ground and flight tested and preliminary measurements of Doppler and polarization measurements were collected. HCR observed sensitivity as low as -37 dBZ at 1 km range and resolved linear depolarization ratio (LDR) si

  11. Polarization Lidar Liquid Cloud Detection Algorithm for Winter Mountain Storms

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Zhao, Hongjie

    1992-01-01

    We have collected an extensive polarization lidar dataset from elevated sites in the Tushar Mountains of Utah in support of winter storm cloud seeding research and experiments. Our truck-mounted ruby lidar collected zenith, dual-polarization lidar data through a roof window equipped with a wiper system to prevent snowfall accumulation. Lidar returns were collected at a rate of one shot every 1 to 5 min during declared storm periods over the 1985 and 1987 mid-Jan. to mid-Mar. Field seasons. The mid-barrier remote sensor field site was located at 2.57 km MSL. Of chief interest to weather modification efforts are the heights of supercooled liquid water (SLW) clouds, which must be known to assess their 'seedability' (i.e., temperature and height suitability for artificially increasing snowfall). We are currently re-examining out entire dataset to determine the climatological properties of SLW clouds in winter storms using an autonomous computer algorithm.

  12. 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

  13. Liquid Water Cloud Measurements Using the Raman Lidar Technique: Current Understanding and Future Research Needs

    NASA Technical Reports Server (NTRS)

    Tetsu, Sakai; Whiteman, David N.; Russo, Felicita; Turner, David D.; Veselovskii, Igor; Melfi, S. Harvey; Nagai, Tomohiro; Mano, Yuzo

    2013-01-01

    This paper describes recent work in the Raman lidar liquid water cloud measurement technique. The range-resolved spectral measurements at the National Aeronautics and Space Administration Goddard Space Flight Center indicate that the Raman backscattering spectra measured in and below low clouds agree well with theoretical spectra for vapor and liquid water. The calibration coefficients of the liquid water measurement for the Raman lidar at the Atmospheric Radiation Measurement Program Southern Great Plains site of the U.S. Department of Energy were determined by comparison with the liquid water path (LWP) obtained with Atmospheric Emitted Radiance Interferometer (AERI) and the liquid water content (LWC) obtained with the millimeter wavelength cloud radar and water vapor radiometer (MMCR-WVR) together. These comparisons were used to estimate the Raman liquid water cross-sectional value. The results indicate a bias consistent with an effective liquid water Raman cross-sectional value that is 28%-46% lower than published, which may be explained by the fact that the difference in the detectors' sensitivity has not been accounted for. The LWP of a thin altostratus cloud showed good qualitative agreement between lidar retrievals and AERI. However, the overall ensemble of comparisons of LWP showed considerable scatter, possibly because of the different fields of view of the instruments, the 350-m distance between the instruments, and the horizontal inhomogeneity of the clouds. The LWC profiles for a thick stratus cloud showed agreement between lidar retrievals andMMCR-WVR between the cloud base and 150m above that where the optical depth was less than 3. Areas requiring further research in this technique are discussed.

  14. 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

  15. Lidar observations of the eruptive cloud of El Chichon

    NASA Astrophysics Data System (ADS)

    Ovezgel'Dyev, O. G.; Mamadov, Kh.

    An aerosol cloud observed by lidar at an altitude of 30-35 km over Ashkhabad, USSR between August 9-19, 1982 is identified as an El Chichon eruptive cloud. The daily variation of the cloud maximum height is given and the structural height-time heterogeneities are investigated. The results are compared with data from other laser sounding stations in the 33-47 deg N latitude interval.

  16. 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

  17. Lidar-Radar Measurements of Snowfall Edwin W. Eloranta--Univ. Of Wisconsin

    E-print Network

    Eloranta, Edwin W.

    of the snowflakes. Donovan and Lammeren(2001) show that the ratio of radar to lidar cross sections can be used extinction cross section is equal to two times the number of snowflakes times the projected average area and lidar cross sections and the particle fall velocity, our model represents snowflakes with an equivalent

  18. Cloud Optical Depth Retrievals from Solar Background "signal" of Micropulse Lidars

    NASA Technical Reports Server (NTRS)

    Chiu, J. Christine; Marshak, A.; Wiscombe, W.; Valencia, S.; Welton, E. J.

    2007-01-01

    Pulsed lidars are commonly used to retrieve vertical distributions of cloud and aerosol layers. It is widely believed that lidar cloud retrievals (other than cloud base altitude) are limited to optically thin clouds. Here we demonstrate that lidars can retrieve optical depths of thick clouds using solar background light as a signal, rather than (as now) merely a noise to be subtracted. Validations against other instruments show that retrieved cloud optical depths agree within 10-15% for overcast stratus and broken clouds. In fact, for broken cloud situations one can retrieve not only the aerosol properties in clear-sky periods using lidar signals, but also the optical depth of thick clouds in cloudy periods using solar background signals. This indicates that, in general, it may be possible to retrieve both aerosol and cloud properties using a single lidar. Thus, lidar observations have great untapped potential to study interactions between clouds and aerosols.

  19. 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 were probed by a 0.523- m lidar and three (0.32-, 0.86-, and 10.6-cm wavelength) Doppler radars lidar and radar dark and bright bands. In contrast to the ubiquitous 10.6-cm (S band) radar bright band

  20. ESTIMATION OF TROPICAL FOREST STRUCTURE AND BIOMASS FROM FUSION OF RADAR AND LIDAR MEASUREMENTS (Invited)

    NASA Astrophysics Data System (ADS)

    Saatchi, S. S.; Dubayah, R.; Clark, D. B.; Chazdon, R.

    2009-12-01

    Radar and Lidar instruments are active remote sensing sensors with the potential of measuring forest vertical and horizontal structure and the aboveground biomass (AGB). In this paper, we present the analysis of radar and lidar data acquired over the La Selva Biological Station in Costa Rica. Radar polarimetry at L-band (25 cm wavelength), P-band (70 cm wavelength) and interferometry at C-band (6 cm wavelength) and VV polarization were acquired by the NASA/JPL airborne synthetic aperture radar (AIRSAR) system. Lidar images were provided by a large footprint airborne scanning Lidar known as the Laser Vegetation Imaging Sensor (LVIS). By including field measurements of structure and biomass over a variety of forest types, we examined: 1) sensitivity of radar and lidar measurements to forest structure and biomass, 2) accuracy of individual sensors for AGB estimation, and 3) synergism of radar imaging measurements with lidar imaging and sampling measurements for improving the estimation of 3-dimensional forest structure and AGB. The results showed that P-band radar combined with any interformteric measurement of forest height can capture approximately 85% of the variation of biomass in La Selva at spatial scales larger than 1 hectare. Similar analysis at L-band frequency captured only 70% of the variation. However, combination of lidar and radar measurements improved estimates of forest three-dimensional structure and biomass to above 90% for all forest types. We present a novel data fusion approach based on a Baysian estimation model with the capability of incorporating lidar samples and radar imagery. The model was used to simulate the potential of data fusion in future satellite mission scenarios as in BIOMASS (planned by ESA) at P-band and DESDynl (planned by NASA) at L-band. The estimation model was also able to quantify errors and uncertainties associated with the scale of measurements, spatial variability of forest structure, and differences in radar and lidar geometry and pixel locations. Keywords: Amazon, Biomass, Carbon, Forest Structure, Tropical forests, Radar, Polarimetry, Interferometry, Lidar This work is performed partially at the Jet Propulsion Laboratory, California Institute of Technology, under contract from National Aeronautic and Space Administration.

  1. First flight of the Cloud Detection Lidar Instrument Package

    SciTech Connect

    Henderson, J.R.; Ledebuhr, A.G.; Cameron, G.; Carter, P.; Hugenberger, R.E.; Kordas, J.F.; Nielsen, D.P.; Stratton, P.; Taylor, B.

    1996-03-01

    The Cloud Detection Lidar Instrument Package is composed of three instruments: the Cloud Detection Lidar (CDL) and two Wide Field of View (WFOV) cameras. The CDL can be rotated to operate in either a nadir-looking or zenith-looking mode. The WFOV cameras provide imagery to complement the CDL measurements. One camera is fixed at nadir looking and the other at zenith looking. Only one camera may be operational at a time. All instruments were successfully flown in September--November 1995.

  2. 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.

  3. 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.

  4. Cloud radar Doppler spectra in drizzling stratiform clouds: 1. Forward modeling and remote sensing applications

    E-print Network

    Cloud radar Doppler spectra in drizzling stratiform clouds: 1. Forward modeling and remote sensing broadening and drizzle growth in shallow liquid clouds remain not well understood. Detailed, cloudscale. Profiling, millimeterwavelength (cloud) radars can provide such observations. In particular, the first three

  5. Airborne lidar and radiometric observations of PBL- and low clouds

    NASA Technical Reports Server (NTRS)

    Flamant, P. H.; Valentin, R.; Pelon, J.

    1992-01-01

    Boundary layer- and low altitude clouds over open ocean and continent areas have been studied during several field campaigns since mid-1990 using the French airborne backscatter lidar LEANDRE in conjunction with on-board IR and visible radiometers. LEANDRE is an automatic system, and a modification of the instrumental parameters, when airborne, is computer controlled through an operator keyboard. The vertical range squared lidar signals and instrument status are displayed in real time on two dedicated monitors. The lidar is used either down- or up-looking while the aircraft is flying above or below clouds. A switching of the viewing configuration takes about a minute. The lidar measurements provide a high resolution description of cloud morphology and holes in cloud layers. The flights were conducted during various meteorological conditions on single or multilayer stratocumulus and cumulus decks. Analysis on a single shot basis of cloud top (or bottom) altitude and a plot of the corresponding histogram allows one to determine a probability density function (PDF). The preliminary results show the PDFs for cloud top are not Gaussian and symmetric about the mean value. The skewness varies with atmospheric conditions. An example of results recorded over the Atlantic ocean near Biarritz is displayed, showing: (1) the range squared lidar signals as a function of time (here 100 s corresponds to about 8 km, 60 shots are averaged on horizontal); the Planetary Boundary Layer (PBL) - up to 600 m - is observed at the beginning of the leg as well as on surface returns, giving an indication of the porosity; (2) the cloud top altitude variation between 2.4 to 2.8 km during the 150 to 320 s section; and (3) the corresponding PDF. Similar results are obtained on stratocumulus over land. Single shot measurements can be used also to determine an optical porosity at a small scale as well as a fractional cloudiness at a larger scale. A comparison of cloud top altitude retrieved from lidar and narrowbeam IR radiometer is conducted to study the scale integration problem. A good agreement within less than 100 m relies on spatial uniformity and an optically thick layer. In the presence of holes, a discrepancy is observed. This is illustrated in figure 2, displaying as a function of time (1) the lidar signals; (2) the target temperature (either clouds or sea surface) retreived from a narrowbeam IR radiometer, 17 C is the sea surface temperature on that day; and (3) the visible flux, linked to cloud albedo, measured by a pyranometer. In preparation of ASTEX, down- and up-looking measurements where conducted on stratocumulus clouds over the Atlantic Ocean near Quimper in Brittany. Depending on the flight pattern orientation with respect to the wind, the top and bottom cloud morphologies are different. Preliminary results are given on cloud morphology, cloud top PDFs, optical porosity, fractional cloudiness, and comparison of lidar and radiometric measurements.

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

    SciTech Connect

    Jayeshlal, G. S. Satyanarayana, Malladi Dhaman, Reji K. Motty, G. S.

    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.

  7. An investigation of cirrus cloud properties using airborne lidar

    NASA Astrophysics Data System (ADS)

    Yorks, John Edward

    The impact of cirrus clouds on the Earth's radiation budget remains a key uncertainty in assessing global radiative balance and climate change. Composed of ice, and located in the cold upper troposphere, cirrus clouds can cause large warming effects because they are relatively transmissive to short-wave solar radiation, but absorptive of long wave radiation. Our ability to model radiative effects of cirrus clouds is inhibited by uncertainties in cloud optical properties. Studies of mid-latitude cirrus properties have revealed notable differences compared to tropical anvil cirrus, likely a consequence of varying dynamic formation mechanisms. Cloud-aerosol lidars provide critical information about the vertical structure of cirrus for climate studies. For this dissertation, I helped develop the Airborne Cloud-Aerosol Transport System (ACATS), a Doppler wind lidar system at NASA Goddard Space Flight Center (GSFC). ACATS is also a high spectral resolution lidar (HSRL), uniquely capable of directly resolving backscatter and extinction properties of a particle from high-altitude aircraft. The first ACATS science flights were conducted out of Wallops Island, VA in September of 2012 and included coincident measurements with the Cloud Physics Lidar (CPL) instrument. In this dissertation, I provide an overview of the ACATS method and instrument design, describe the ACATS retrieval algorithms for cloud and aerosol properties, explain the ACATS HSRL retrieval errors due to the instrument calibration, and use the coincident CPL data to validate and evaluate ACATS cloud and aerosol retrievals. Both the ACATS HSRL and standard backscatter retrievals agree well with coincident CPL retrievals. Mean ACATS and CPL extinction profiles for three case studies demonstrate similar structure and agree to within 25 percent for cirrus clouds. The new HSRL retrieval algorithms developed for ACATS have direct application to future spaceborne missions. Furthermore, extinction and particle wind velocity retrieved from ACATS can be used for science applications such as dust transport and convective anvil outflow. The relationship between cirrus cloud properties and dynamic formation mechanism is examined through statistics of CPL cirrus observations from more than 100 aircraft flights. The CPL 532 nm lidar ratios (also referred to as the extinction to backscatter ratio) for cirrus clouds formed by synoptic-scale uplift over land are lower than convectively-generated cirrus over tropical oceans. Errors in assuming a constant lidar ratio can lead to errors of ˜50% in cloud optical extinction derived from space-borne lidar such as CALIOP. The 1064 nm depolarization ratios for synoptically-generated cirrus over land are lower than convectively-generated cirrus, formed due to rapid upward motions of tropical convection, as a consequence of differences in cloud temperatures and ice particle size and shape. Finally, the backscatter color ratio is directly proportional to depolarization ratio for synoptically-generated cirrus, but not for any other type of cirrus. The relationships between cirrus properties and formation mechanisms determined in this study can be used as part of a larger global climatology of cirrus clouds to improve parameterizations in global climate models and satellite retrievals to improve our understanding of the impact of clouds on weather and climate.

  8. 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.

  9. Lidar sensing of aerosols and clouds in the troposphere and stratosphere

    NASA Technical Reports Server (NTRS)

    Reagan, John A.; Mccormick, M. Patrick; Spinhirne, James D.

    1989-01-01

    Advances in the development and application of lidar as a tool for the remote sensing of atmospheric aerosols and clouds are reviewed. The lidar sensing technique is described, and various approaches for solving the lidar equation to retrieve aerosol properties are summarized. Examples are presented of lidar applications to aerosol and cloud sensing in both the troposphere and stratosphere. These include environmental monitoring, atmospheric-boundary-layer studies, retrieval of aerosol optical and physical properties, sensing of clouds, and investigation of volcanic effects in the stratosphere. Comments are offered regarding the future outlook for aerosol and cloud sensing by both ground-based and spaceborne lidars.

  10. 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.

  11. Lidar Studies on The Optical Characteristics of High Altitude Cirrus Clouds at A Low Latitiude Station, Gadanki (13.5°N , 79.2°E ) India

    NASA Astrophysics Data System (ADS)

    Jayeshlal, G. S.; Satyanarayana, M.; Motty, G. S.; Dhaman, R. K.; Krishnakumar, V.; Mahadevan Pillai, V. P.; Ramakrishnarao, D.; Sudhakar, P.; Kalavathi, P.

    2014-11-01

    Light Detection and Ranging (LIDAR) which is analogous to Radio Detection And Ranging (RADAR), has become an important and unique technology for atmospheric research and applications. The technology is widely used for the remote sensing of the Earth's atmosphere, oceans, vegetation and the characteristics of Earth's topography. Remote sensing of atmosphere, for its structure, composition and dynamics, is one of the proven applications of the lidar systems. More importantly the lidar technique is applied for the study of clouds, aerosols and minor constituents in the atmosphere. It provides the information on the above with good spatial and temporal resolutions and accuracy. The high altitude cirrus clouds which play an important role in the Earth's radiative budget and global climate can be studied by using the LIDAR system. These clouds absorb long-wave outgoing radiation from Earth's surface while reflecting part of the incoming short-wave solar radiation. Lidar measurements are useful in deriving the altitude, top height, bottom height and the optical properties of cirrus clouds, which are essential in understanding the cloud-radiation effects. The optical depth, the effective lidar ratio and the depolarization of the clouds are also derived by inverting the lidar signals from the cirrus clouds. In this paper we present the results on the lidar derived optical and microphysical properties of the cirrus clouds at a tropical station Gadanki (13.5°N, 79.2°E) India during two year period from 2009 to210. The seasonal variations of the cloud properties during the observation period are presented and discussed with reference to earlier period.

  12. 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

  13. 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.

  14. 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.

  15. 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).

  16. Use of equivalent spheres to model the relation between radar reflectivity and optical extinction of ice cloud particles.

    PubMed

    Donovan, David Patrick; Quante, Markus; Schlimme, Ingo; Macke, Andreas

    2004-09-01

    The effect of ice crystal size and shape on the relation between radar reflectivity and optical extinction is examined. Discrete-dipole approximation calculations of 95-GHz radar reflectivity and ray-tracing calculations are applied to ice crystals of various habits and sizes. Ray tracing was used primarily to calculate optical extinction and to provide approximate information on the lidar backscatter cross section. The results of the combined calculations are compared with Mie calculations applied to collections of different types of equivalent spheres. Various equivalent sphere formulations are considered, including equivalent radar-lidar spheres; equivalent maximum dimension spheres; equivalent area spheres, and equivalent volume and equivalent effective radius spheres. Marked differences are found with respect to the accuracy of different formulations, and certain types of equivalent spheres can be used for useful prediction of both the radar reflectivity at 95 GHz and the optical extinction (but not lidar backscatter cross section) over a wide range of particle sizes. The implications of these results on combined lidar-radar ice cloud remote sensing are discussed. PMID:15449480

  17. Objective Determination of Cloud Heights and Radar Reflectivities Using a Combination of Active Remote Sensors at the ARM CART Sites.

    NASA Astrophysics Data System (ADS)

    Clothiaux, Eugene E.; Ackerman, Thomas P.; Mace, Gerald G.; Moran, Kenneth P.; Marchand, Roger T.; Miller, Mark A.; Martner, Brooks E.

    2000-05-01

    The U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Program is deploying sensitive, millimeter-wave cloud radars at its Cloud and Radiation Test Bed (CART) sites in Oklahoma, Alaska, and the tropical western Pacific Ocean. The radars complement optical devices, including a Belfort or Vaisala laser ceilometer and a micropulse lidar, in providing a comprehensive source of information on the vertical distribution of hydrometeors overhead at the sites. An algorithm is described that combines data from these active remote sensors to produce an objective determination of hydrometeor height distributions and estimates of their radar reflectivities, vertical velocities, and Doppler spectral widths, which are optimized for accuracy. These data provide fundamental information for retrieving cloud microphysical properties and assessing the radiative effects of clouds on climate. The algorithm is applied to nine months of data from the CART site in Oklahoma for initial evaluation. Much of the algorithm's calculations deal with merging and optimizing data from the radar's four sequential operating modes, which have differing advantages and limitations, including problems resulting from range sidelobes, range aliasing, and coherent averaging. Two of the modes use advanced phase-coded pulse compression techniques to yield approximately 10 and 15 dB more sensitivity than is available from the two conventional pulse modes. Comparison of cloud-base heights from the Belfort ceilometer and the micropulse lidar confirms small biases found in earlier studies, but recent information about the ceilometer brings the agreement to within 20-30 m. Merged data of the radar's modes were found to miss approximately 5.9% of the clouds detected by the laser systems. Using data from only the radar's two less-sensitive conventional pulse modes would increase the missed detections to 22%-34%. A significant remaining problem is that the radar's lower-altitude data are often contaminated with echoes from nonhydrometeor targets, such as insects.

  18. Analysis of lidar, radar and satellite measurements on severe thunderstorms and their environments

    NASA Technical Reports Server (NTRS)

    Bluestein, H.; Doviak, R. J.; Zrnic, S.; Rabin, R.; Sundara-Rajan, A.

    1984-01-01

    Intercomparison of wind data from the airborne Doppler lidar, ground-based Doppler radars, the 444 m NSSL-KTVY tower, and rawinsonde were completed. The vertical profile of wind in the PBL measured by the radars compared favorably with the profiles measured by the tower and rawinsonde while the one obtained from lidar data differed from the other three by as much as 3m/sec in wind speed and 38 degrees in direction. The time dependence of differences in wind estimates from radar and lidar suggested that these discrepencies could be attributed to a Schuler resonance in the aircraft's inertial navigation system which caused an erroneous component of the aircraft's velocity vector to be subtracted from the lidar radial velocities, thus creating errors in the synthesized wind speed and direction. The vertical profile of turbulent fluctuations of the horizontal wind detected by the different systems compared well. Also, spectra from the different sensing systems compared well in both magnitude and shape, suggesting that the lidar and radar detected similar turbulent structure.

  19. An evaluation of ice formation in large-eddy simulations of supercooled Arctic stratocumulus using ground-based lidar

    E-print Network

    ground-based lidar and cloud radar B. van Diedenhoven,1,2 A. M. Fridlind,2 A. S. Ackerman,2 E. W stratocumulus, we compare measurements of radar reflectivity and Doppler velocity and lidar backscatter-eddy simulations (LES). The measurements are taken from the Millimeter Cloud Radar and the Arctic High Spectral

  20. 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.

  1. ARRA-funded Cloud Radar Development for the Department of Energy's ARM Climate Research Facility

    E-print Network

    ARRA-funded Cloud Radar Development for the Department of Energy's ARM Climate Research Facility six dual frequency cloud radar systems. These radars will be used by the Atmospheric Radiation on the effects of clouds and precipitation on the climate. Four cloud radar systems will be permanently installed

  2. Raster Vs. Point Cloud LiDAR Data Classification

    NASA Astrophysics Data System (ADS)

    El-Ashmawy, N.; Shaker, A.

    2014-09-01

    Airborne Laser Scanning systems with light detection and ranging (LiDAR) technology is one of the fast and accurate 3D point data acquisition techniques. Generating accurate digital terrain and/or surface models (DTM/DSM) is the main application of collecting LiDAR range data. Recently, LiDAR range and intensity data have been used for land cover classification applications. Data range and Intensity, (strength of the backscattered signals measured by the LiDAR systems), are affected by the flying height, the ground elevation, scanning angle and the physical characteristics of the objects surface. These effects may lead to uneven distribution of point cloud or some gaps that may affect the classification process. Researchers have investigated the conversion of LiDAR range point data to raster image for terrain modelling. Interpolation techniques have been used to achieve the best representation of surfaces, and to fill the gaps between the LiDAR footprints. Interpolation methods are also investigated to generate LiDAR range and intensity image data for land cover classification applications. In this paper, different approach has been followed to classifying the LiDAR data (range and intensity) for land cover mapping. The methodology relies on the classification of the point cloud data based on their range and intensity and then converted the classified points into raster image. The gaps in the data are filled based on the classes of the nearest neighbour. Land cover maps are produced using two approaches using: (a) the conventional raster image data based on point interpolation; and (b) the proposed point data classification. A study area covering an urban district in Burnaby, British Colombia, Canada, is selected to compare the results of the two approaches. Five different land cover classes can be distinguished in that area: buildings, roads and parking areas, trees, low vegetation (grass), and bare soil. The results show that an improvement of around 10 % in the classification results can be achieved by using the proposed approach.

  3. Interpretation of the optical and morphological properties of Cirrus clouds from lidar measurements

    NASA Technical Reports Server (NTRS)

    Grund, Christian John; Eloranta, Edwin W.

    1990-01-01

    Lidar measurements can provide a great deal of information about the structure, location, and scattering properties of cirrus clouds. However, caution must be used when interpreting raw lidar backscatter profiles in terms of relative or absolute extinction distribution, internal cloud structure, and, at times, cloud location. The problem arises because the signal measured from a range by any monostatic lidar system depends on the backscatter cross section at that range and the 2-way optical thickness to the scattering volume. Simple lidar systems, however, produce only one measurement of attenuated backscatter from each range. The general FIRE research community is given aid in interpretation of lidar measurements, and the special capabilities of the High Spectral Resolution Lidar (HSRL) is explained. Some examples are given of conditions under which direct interpretation of cirrus cloud morphology from simple lidar profiles could be misleading.

  4. Vertical Motion Long-Term Lidar and Radar Observations of Arctic Stratus at Two Locations

    E-print Network

    Eloranta, Edwin W.

    (km) Radar backscatter cross section (Masked values shown in black and white) 23:05 23:10 23:15 23:20 23:25 0(km) Radar backscatter cross section (Masked values shown in black and white) 12:05 12:10 12:15 12:20 12:25 0) Altitude(km) Lidar backscatter cross section (Masked values shown in black and white) 23:05 23:10 23:15 23

  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. Cloud radar Doppler spectra in drizzling stratiform clouds: 1. Forward modeling and remote sensing applications

    SciTech Connect

    Kollias, P.; Luke, E.; Rémillard, J.; Szyrmer, W.

    2011-07-02

    Several aspects of spectral broadening and drizzle growth in shallow liquid clouds remain not well understood. Detailed, cloud-scale observations of microphysics and dynamics are essential to guide and evaluate corresponding modeling efforts. Profiling, millimeter-wavelength (cloud) radars can provide such observations. In particular, the first three moments of the recorded cloud radar Doppler spectra, the radar reflectivity, mean Doppler velocity, and spectrum width, are often used to retrieve cloud microphysical and dynamical properties. Such retrievals are subject to errors introduced by the assumptions made in the inversion process. Here, we introduce two additional morphological parameters of the radar Doppler spectrum, the skewness and kurtosis, in an effort to reduce the retrieval uncertainties. A forward model that emulates observed radar Doppler spectra is constructed and used to investigate these relationships. General, analytical relationships that relate the five radar observables to cloud and drizzle microphysical parameters and cloud turbulence are presented. The relationships are valid for cloud-only, cloud mixed with drizzle, and drizzle-only particles in the radar sampling volume and provide a seamless link between observations and cloud microphysics and dynamics. The sensitivity of the five observed parameters to the radar operational parameters such as signal-to-noise ratio and Doppler spectra velocity resolution are presented. The predicted values of the five observed radar parameters agree well with the output of the forward model. The novel use of the skewness of the radar Doppler spectrum as an early qualitative predictor of drizzle onset in clouds is introduced. It is found that skewness is a parameter very sensitive to early drizzle generation. In addition, the significance of the five parameters of the cloud radar Doppler spectrum for constraining drizzle microphysical retrievals is discussed.

  7. Scanning ARM Cloud Radars Part I: Operational Sampling Strategies

    SciTech Connect

    Kollias, Pavlos; Bharadwaj, Nitin; Widener, Kevin B.; Jo, Ieng; Johnson, Karen

    2014-03-01

    Probing clouds in three-dimensions has never been done with scanning millimeter-wavelength (cloud) radars in a continuous operating environment. The acquisition of scanning cloud radars by the Atmospheric Radiation Measurement (ARM) program and research institutions around the world generate the need for developing operational scan strategies for cloud radars. Here, the first generation of sampling strategies for the Scanning ARM Cloud Radars (SACRs) is discussed. These scan strategies are designed to address the scientific objectives of the ARM program, however, they introduce an initial framework for operational scanning cloud radars. While the weather community uses scan strategies that are based on a sequence of scans at constant elevations, the SACRs scan strategies are based on a sequence of scans at constant azimuth. This is attributed to the cloud properties that are vastly different for rain and snow shafts that are the primary target of precipitation radars. A “cloud surveillance” scan strategy is introduced (HS-RHI) based on a sequence of horizon-to-horizon Range Height Indicator (RHI) scans that sample the hemispherical sky (HS). The HS-RHI scan strategy is repeated every 30 min to provide a static view of the cloud conditions around the SACR location. Between HS-RHI scan strategies other scan strategies are introduced depending on the cloud conditions. The SACRs are pointing vertically in the case of measurable precipitation at the ground. The radar reflectivities are corrected for water vapor attenuation and non-meteorological detection are removed. A hydrometeor detection mask is introduced based on the difference of cloud and noise statistics is discussed.

  8. 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.

  9. 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.

  10. Validation of Cloud Seeding using the Airborne Radar

    NASA Astrophysics Data System (ADS)

    Chang, K.; Jung, J.; Cha, J.; Lee, C.; Choi, Y.; Lee, H.

    2010-12-01

    In many cloud seeding programs, the effect of cloud seeding in natural situation has been statistically verified by analyzing the long-term variation of precipitation between experimental and control region. The case analysis for each cloud seeding experiment is needed for the advance of seeding technology, but is avoided because of the limitation of existing instruments. One of the preferable instruments for the validation of cloud seeding is the ground based radar(s) because of its good spatial and temporal resolution, but it also has the limitations of cloud observation such as the geometric darkness by earth curvature far from radar site. Using the airborne radar, we have obtained the results that the radar reflectivity is evidently enhanced along the wind direction from the seeding path about 15 minutes after seeding at 4 March 2008. This suggests that the advanced sensor system such as the airborne radar may facilitate the case-by-case validation of cloud seeding experiment, as mentioned in the Garbor Vali’s talk in the 2007 WMO conference, and the detailed understanding and rapid progress of weather modification research and operation (Most of cloud seeding project, based on the statistical verification, need the longer period than 5 years).

  11. Multidimensional Cloud Images Retrieval From Dual-Frequency Millimeter-Wave Radar

    E-print Network

    Cruz-Pol, Sandra L.

    use radar scans of cloud reflectivity at 33 GHz and 95 GHz to produce multi-dimensional cloud images such as the General Circulation Models (GCMs)[9]. The cloud reflectivity was measured with the Cloud Profiling RadarMultidimensional Cloud Images Retrieval From Dual- Frequency Millimeter-Wave Radar Sandra L. Cruz

  12. 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

  13. 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.

  14. 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 ); Knudsen, B.M. )

    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.

  15. Lidar studies of interannual, seasonal, and diurnal variations of polar mesospheric clouds at the South Pole

    E-print Network

    Chu, Xinzhao

    Lidar studies of interannual, seasonal, and diurnal variations of polar mesospheric clouds 2002; accepted 19 December 2002; published 8 March 2003. [1] Polar mesospheric clouds (PMC) were Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM), the hemispheric

  16. L625 Lidar Measurements of Pinatubo Volcanic Cloud at Hefei

    NASA Technical Reports Server (NTRS)

    Hu, Huanling; Zhou, Jun

    1992-01-01

    The Pinatubo volcano erupted violently between June 9-17, 1991. This eruption was much larger than the El Chichon volcanic eruption in April, 1982. Because of the effects on the global environment, much attention was focused on the measurements of the volcanic cloud. The 84 scattering-ratio profiles of the volcanic cloud have been obtained by our L625 lidar system. The conclusions from studies of the data are: (1) Pinatubo volcanic cloud was present over Hefei after 40 days from eruption; (2) the peak scattering ratio varied violently in July and August of 1991; (3) the height of the peak scattering ratio is between about 18 to 25 km; and (4) since August 28, 1991, the optical depth was about one order of magnitude larger than before the eruption.

  17. A NOVEL APPROACH TO PROFILE CLOUD MICROPHYSICS USING DUAL-FREQUENCY RADARS

    E-print Network

    A NOVEL APPROACH TO PROFILE CLOUD MICROPHYSICS USING DUAL- FREQUENCY RADARS Dong Huang, Karen cloud LWC can be obtained using operational ARM Ka- and W-band cloud radars operated by the Atmospheric to determine from radar reflectivity alone. We have applied the dual-frequency approach to the ARM radar

  18. A self-directing elastic backscatter lidar system for debris cloud tracking and characterization

    SciTech Connect

    Clark, D.A.; Dighe, K.A.; Tunnell, T.W.

    1996-06-01

    An elastic backscatter lidar that utilizes the lidar signal itself to direct the system towards fast moving isolated aerosol clouds has been developed. However, detecting and tracking invisible transient effluents from unknown locations, though conceptually straightforward, has still remained experimentally challenging. Accurate cloud volume, cloud density distribution, and track information have been obtained on small, fast moving, subvisible debris clouds resulting from above ground tests in which conventional explosives were detonated.

  19. Influence of Humidified Aerosol on Lidar Depolarization Measurements below Ice-Precipitating Arctic Stratus

    E-print Network

    - cients, radar reflectivity, and Doppler velocity, but lidar depolarization serves as a critical parameter distributions of lidar backscatter, radar reflectivity, and radar Doppler velocity, in addi- tion cloud that was lightly precipitating ice show a range of surprisingly low de- polarization ratios (4

  20. Lidar observations of cirrus clouds in Buenos Aires

    NASA Astrophysics Data System (ADS)

    Lakkis, S. Gabriela; Lavorato, Mario; Canziani, Pablo; Lacomi, Hector

    2015-08-01

    Characterization of cirrus clouds over Buenos Aires (34.6°S, 58.5°W) using a ground based lidar is presented. The study, carried out for the period 2010-2011, reveals that cirrus are usually found in the altitude region 8-11 km, with mid-cloud temperatures values varying between -75 °C and 55 °C. The clouds, whose bases altitudes display significant variability while their tops remains close to the tropopause, show geometrical thickness ranging from 1.2 to 5 km, with on average value 3.0±0.9 km. Most commonly observed cirri can be characterized as optically thin cirrus rather than dense ones, with a mean optical depth value of 0.26±0.11 and an applied multiple scattering factor ? of 0.85±0.07. In this region, the optical depth increases with increasing geometrical thickness with a partially linear correlation. Lidar ratios are also analyzed and on average the value is 32±17 sr.

  1. Analysis of cloud layer structure in Shouxian, China using RS92 radiosonde aided by 95 GHz cloud radar

    E-print Network

    Zeng, Ning

    radar Jinqiang Zhang,1,2 Hongbin Chen,1 Zhanqing Li,1,3 Xuehua Fan,1 Liang Peng,1,2 Yu Yu,1 and Maureen of cloud vertical layers from the 95 GHz radar. Singlelayer, twolayer, and threelayer clouds account for 28 in multiplelayer cloud systems, maximum cloud top height and cloud thickness occurred at 1930 LST. Diurnal

  2. 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.

  3. Estimation of canopy height using lidar and radar interferometry: an assessment of combination methods and sensitivity to instrument, terrain and canopy height profile

    NASA Astrophysics Data System (ADS)

    Simard, M.; Neumann, M.; Pinto, N.; Brolly, M.; Brigot, G.

    2014-12-01

    The combined use of Lidar and radar interferometry to estimate canopy height can be classified into 3 categories: cross-validation, simple combination and fusion methods. In this presentation, we investigate the potential of each category for local and regional scale applications, and assess their sensitivity to instrument configuration, terrain topography and variations in the vertical forest canopy profiles. In addition to field data, we use data from TanDEM-X, UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar), LVIS (Laser Vegetation Imaging Sensor) and a commercial discrete lidar. TanDEM-X is a pair of X-band spaceborne radars flying in formation to provide a global digital surface model and can also be used to perform polarimetric synthetic aperture radar (polinSAR) inversion of canopy height. The UAVSAR is an airborne fully polarimetric radar enabling repeat-pass interferometry and has been used for polinsar. While LVIS records the full waveform within a 20m footprint, the discrete lidar collects a cloud of points. The lidar data can be used to validate the polinSAR results (validation), to obtain ground elevation (simple combination with radar surface models) or within the polinSAR inversion model through a common model framework. The data was collected over the Laurentides Wildlife Reserve, a managed territory covering 7861km2 which is located between Québec city and Saguenay. The variety of management practices offers the possibility for long term and comparative studies of natural forest dynamics as well as the impact of human, fires and insect disturbances. The large elevational gradient of the region (~1000m) allows study of variations in structure and type of forests. Depending on the method used, several factors may degrade the accuracy of canopy height estimates from the combined use of lidar and radar interferometry. Here we will consider misregistration of datasets, differences in spatial resolution and viewing geometry, geometric decorrelation and the vertical wavenumber. Finally we investigate the sensitivity of estimate to forest vertical profile and terrain topography.

  4. 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.

  5. Improved retrievals of the optical properties of cirrus clouds by a combination of lidar methods.

    PubMed

    Cadet, Bertrand; Giraud, Vincent; Haeffelin, Martial; Keckhut, Philippe; Rechou, Anne; Baldy, Serge

    2005-03-20

    We focus on improvement of the retrieval of optical properties of cirrus clouds by combining two lidar methods. We retrieve the cloud's optical depth by using independently the molecular backscattering profile below and above the cloud [molecular integration (MI) method] and the backscattering profile inside the cloud with an a priori effective lidar ratio [particle integration (PI) method]. When the MI method is reliable, the combined MI-PI method allows us to retrieve the optimal effective lidar ratio. We compare these results with Raman lidar retrievals. We then use the derived optimal effective lidar ratio for retrieval with the PI method for situations in which the MI method cannot be applied. PMID:15818860

  6. 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.

  7. TURBULENCE INDUCED FLUCTUATIONS IN CLOUD SATURATION RATIO: DOPPLER RADAR MEASUREMENTS AND IMPLICATIONS FOR

    E-print Network

    TURBULENCE INDUCED FLUCTUATIONS IN CLOUD SATURATION RATIO: DOPPLER RADAR MEASUREMENTS and downdraft velocities using new ARM scanning Doppler radar and radiosonde measurements. The measurements potential theory of drizzle formation from remote sensing methods and in particular from the Doppler radar

  8. An assessment of cirrus heights from MISR oblique stereo using ground-based radar and lidar at the Tropical Western Pacific ARM sites

    NASA Astrophysics Data System (ADS)

    Prasad, Abhnil Amtesh; Davies, Roger

    2013-06-01

    We compare cirrus presence and heights (CTHs) using oblique stereo by the Multiangle Imaging SpectroRadiometer (MISR) with measurements from ground-based cloud radar and lidar sensors at the Tropical Western Pacific (TWP) sites operated by the U.S. Department of Energy Atmospheric Radiation Measurement Program. Precise point-wise comparisons, limited to only 195 coincident cases, showed that the total number of cirrus retrieved using oblique-stereo analysis improved to 70% from 39% using the standard-stereo technique. The stereo technique detects cloud with the highest contrast, which is often at lower altitude. The oblique-stereo technique's efficiency depends on the thickness and number of underlying cloud layers. A histogram approach allowed similar regions to be compared statistically with many more samples and showed three distinct peaks at ?13 km, 15 km, and 19 km related to deep convective clouds, tropical tropopause layer (TTL) cirrus, and overshooting convective clouds, respectively. Most differences between the satellite and ground-based measurements resulted from a number of cases of invalid cloud comparisons (14%), blunders from edges and broken clouds (7%), low contrast stereo mismatches (4%), and under-estimation of CTHs (3%). Overall, the oblique-stereo analysis detected a cirrus-top layer in 65% of all the valid coincident cases, mostly <1 km in thickness. The oblique-stereo derived cirrus CTHs differed from the heights of cirrus-top layers from ground-based cloud radar and lidar by -0.5 ± 1.0 km, validating the MISR retrievals. This suggests global thin cirrus retrievals are possible with the oblique-stereo technique after the screening of occasional blunders.

  9. 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.

  10. A wing pod-based millimeter wavelength airborne cloud radar

    NASA Astrophysics Data System (ADS)

    Vivekanandan, J.; Ellis, S.; Tsai, P.; Loew, E.; Lee, W. C.; Emmett, J.; Dixon, M.; Burghart, C.; Rauenbuehler, S.

    2015-04-01

    This paper describes a novel, airborne pod-based millimeter wavelength radar. Its frequency of operation is 94 GHz (3 mm wavelength). The radar has been designed to fly on the NCAR Gulfstream V HIAPER aircraft; however, it could be deployed on other similarly equipped aircraft. The pod-based configuration occupies minimum cabin space and maximizes scan coverage. The radar system is capable of collecting observations in a staring mode between zenith and nadir or in a scanning mode. Standard pulse-pair estimates of moments and raw time series of backscattered signals are recorded. The radar system design and characteristics, as well as techniques for calibrating reflectivity and correcting Doppler velocity for aircraft attitude and motion are described. The radar can alternatively be deployed in a ground-based configuration, housed in the 20 ft shipping container it shares with the High Spectral Resolution Lidar (HSRL). The radar was tested both on the ground and in flight. Preliminary measurements of Doppler and polarization measurements were collected and examples are presented.

  11. A wing pod-based millimeter wavelength airborne cloud radar

    NASA Astrophysics Data System (ADS)

    Vivekanandan, J.; Ellis, S.; Tsai, P.; Loew, E.; Lee, W.-C.; Emmett, J.; Dixon, M.; Burghart, C.; Rauenbuehler, S.

    2015-08-01

    This paper describes a novel, airborne pod-based millimeter (mm) wavelength radar. Its frequency of operation is 94 GHz (3 mm wavelength). The radar has been designed to fly on the NCAR Gulfstream V HIAPER aircraft; however, it could be deployed on other similarly equipped aircraft. The pod-based configuration occupies minimum cabin space and maximizes scan coverage. The radar system is capable of collecting observations in a staring mode between zenith and nadir or in a scanning mode. Standard pulse-pair estimates of moments and raw time series of backscattered signals are recorded. The radar system design and characteristics as well as techniques for calibrating reflectivity and correcting Doppler velocity for aircraft attitude and motion are described. The radar can alternatively be deployed in a ground-based configuration, housed in the 20 ft shipping container it shares with the High Spectral Resolution Lidar (HSRL). The radar was tested both on the ground and in flight. Preliminary measurements of Doppler and polarization measurements were collected and examples are presented.

  12. Ice Crystal Sice Retrievals using High Spectral Resolution Lidar and Millimeter Wave Radar Data Edwin W.Eloranta

    E-print Network

    Eloranta, Edwin W.

    an averages over the particle size distribution. Radar backscatter cross section D section,extinction cross section,and depolarization that are robustly calibrated by reference to molecular follows that of Donovan and Lammeren (JGR, V106, D21,p 27425). The lidar and radar backscatter cross

  13. Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar

    NASA Astrophysics Data System (ADS)

    Shupe, M. D.; Brooks, I. M.; Canut, G.

    2012-06-01

    Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4-6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tethered-balloon and meteorological tower-mounted sonic anemometer measurements made at spatial distances of a few hundred meters. Temporal lag analyses suggest that approximately half of the observed differences are due to spatial sampling considerations, such that the anticipated radar-based retrieval uncertainty is on the order of a factor of 2-3. Moreover, radar retrievals are clearly able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds.

  14. Investigation of the Turbulent Structure of a Cloud-Capped Mixed Layer Using Doppler Radar

    E-print Network

    Mark, Pinsky

    Investigation of the Turbulent Structure of a Cloud-Capped Mixed Layer Using Doppler Radar M. A vertically pointed Doppler radar is an efficient tool for investigating cloud microphysical parameters by a vertically pointed Doppler radar, namely, the radar reflectivity Z(h, t) and the mean ver- tical velocity V

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

    E-print Network

    Protat, Alain

    backscatter and ice cloud reflectivities measured by an airborne cloud radar and Cloudsat during two field reflectivities 1 dB higher than the airborne cloud radar. Five ground-based sites have also been usedAssessment of Cloudsat Reflectivity Measurements and Ice Cloud Properties Using Ground

  16. 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 approach, and 1.27 (1.12) 0.78 for the standard CloudSat radar­visible optical depth algorithm for Ze 28 d provided to the groups. Retrievals from future spaceborne radar using reflectivity­Doppler fall speeds show

  17. Distributed Dimensonality-Based Rendering of LIDAR Point Clouds

    NASA Astrophysics Data System (ADS)

    Brédif, M.; Vallet, B.; Ferrand, B.

    2015-08-01

    Mobile Mapping Systems (MMS) are now commonly acquiring lidar scans of urban environments for an increasing number of applications such as 3D reconstruction and mapping, urban planning, urban furniture monitoring, practicability assessment for persons with reduced mobility (PRM)... MMS acquisitions are usually huge enough to incur a usability bottleneck for the increasing number of non-expert user that are not trained to process and visualize these huge datasets through specific softwares. A vast majority of their current need is for a simple 2D visualization that is both legible on screen and printable on a static 2D medium, while still conveying the understanding of the 3D scene and minimizing the disturbance of the lidar acquisition geometry (such as lidar shadows). The users that motivated this research are, by law, bound to precisely georeference underground networks for which they currently have schematics with no or poor absolute georeferencing. A solution that may fit their needs is thus a 2D visualization of the MMS dataset that they could easily interpret and on which they could accurately match features with their user datasets they would like to georeference. Our main contribution is two-fold. First, we propose a 3D point cloud stylization for 2D static visualization that leverages a Principal Component Analysis (PCA)-like local geometry analysis. By skipping the usual and error-prone estimation of a ground elevation, this rendering is thus robust to non-flat areas and has no hard-to-tune parameters such as height thresholds. Second, we implemented the corresponding rendering pipeline so that it can scale up to arbitrary large datasets by leveraging the Spark framework and its Resilient Distributed Dataset (RDD) and Dataframe abstractions.

  18. Determining in-Cloud Ice Particle Canting Distributions Using Radar

    NASA Astrophysics Data System (ADS)

    Honeyager, R. E.; Liu, G.

    2014-12-01

    With the advent of satellite-borne and ground-based radar and radiometers, it is now possible to observe ice cloud processes with unprecedented global coverage, simultaneously and at multiple frequencies. Unlike with liquid water, ice is nonspherical. Because of this asymmetry, in-cloud ice can sometimes have a preferred orientation. Instead of the particles orienting randomly, these particles may align roughly parallel to the horizon due to dynamical forcings. As such, this means that radar and radiometer observation angle relative to vertical / nadir must also be considered when recovering information from these instruments. To gain a preliminary understanding of these effects, angle-dependent single scattering properties (i.e. scattering and backscatter cross-section) are first determined using the discrete dipole approximation (DDA). Several particle morphologies are considered, including bullet rosette aggregates [Nowell, Liu and Honeyager 2013], dendritic snowflakes, sector snowflakes and bullet rosettes [Liu 2008]. Early profiles are constructed, showing the change in backscatter and scattering cross-sections as a function of radar observation angle and degree of alignment in the ensemble. To make a more physical model, it is not assumed that all hydrometeors are either fully randomly oriented or fully aligned. It is expected that transition regions occur in clouds, with partial alignment. We use an ensemble von Mises-Fisher distribution to examine these alignment effects. Finally, the model is to be validated against dual-frequency radar retrievals (Ka and W-Band) using ARM scanning-mode radars. By examining clouds at multiple angles and multiple frequencies as they move over the radar site, it is possible to determine the hydrometeor canting distribution. Observations will be used to develop a model for where hydrometeor alignment effects are expected to occur, and to determine the impact hydrometeor alignment has on existing zenith and nadir-pointing radar.

  19. The Experimental Cloud Lidar Pilot Study (ECLIPS) for cloud-radiation research

    NASA Technical Reports Server (NTRS)

    Platt, C. M.; Young, S. A.; Carswell, A. I.; Pal, S. R.; Mccormick, M. P.; Winker, D. M.; Delguasta, M.; Stefanutti, L.; Eberhard, W. L.; Hardesty, M.

    1994-01-01

    The Experimental Cloud Lidar Pilot Study (ECLIPS) was initiated to obtain statistics on cloud-base height, extinction, optical depth, cloud brokenness, and surface fluxes. Two observational phases have taken place, in October-December 1989 and April-July 1991, with intensive 30-day periods being selected within the two time intervals. Data are being archived at NASA Langley Research Center and, once there, are readily available to the international scientific community. This article describes the scale of the study in terms of its international involvement and in the range of data being recorded. Lidar observations of cloud height and backscatter coefficient have been taken from a number of ground-based stations spread around the globe. Solar shortwave and infrared longwave fluxes and infrared beam radiance have been measured at the surface wherever possible. The observations have been tailored to occur around the overpass times of the NOAA weather satellites. This article describes in some detail the various retrieval methods used to obtain results on cloud-base height, extinction coefficient, and infrared emittance, paying particular attention to the uncertainties involved.

  20. Space-Based Lidar Systems

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli

    2012-01-01

    An overview of space-based lidar systems is presented. from the first laser altimeter on APOLLO 15 mission in 1971 to the Mercury Laser Altimeter on MESSENGER mission currently in orbit, and those currently under development. Lidar, which stands for Light Detection And Ranging, is a powerful tool in remote sensing from space. Compared to radars, lidars operate at a much shorter wavelength with a much narrower beam and much smaller transmitter and receiver. Compared to passive remote sensing instruments. lidars carry their own light sources and can continue measuring day and night. and over polar regions. There are mainly two types of lidars depending on the types of measurements. lidars that are designed to measure the distance and properties of hard targets are often called laser rangers or laser altimeters. They are used to obtain the surface elevation and global shape of a planet from the laser pulse time-of-night and the spacecraft orbit position. lidars that are designed to measure the backscattering and absorption of a volume scatter, such as clouds and aerosols, are often just called lidars and categorized by their measurements. such as cloud and aerosol lidar, wind lidar, CO2 lidar, and so on. The advantages of space-based lidar systems over ground based lidars are the abilities of global coverage and continuous measurements.

  1. 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.

  2. Coherent Doppler Lidar for Wind and Cloud Measurements on Venus from an Orbiting or Floating/Flying Platform

    NASA Astrophysics Data System (ADS)

    Singh, Upendra; Limaye, Sanjay; Emmitt, George; Kavaya, Michael; Yu, Jirong; Petros, Mulugeta

    Abstract 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. Assuming an orbit altitude of 250 km and cloud tops at 60km (within the “upper cloud layer”), an initial performance assessment of an orbiting DWL was made using a numerical instrument and atmospheres model developed for both Earth and Mars. The threshold aerosol backscatter for 2-micron was taken to be 1.0*10-6 msr-1. This backscatter value is between 1 and 2 orders of magnitude lower than that expected for clouds with optical depths greater than 2.0. Cloud composition was assumed to be mixture of dust, frozen CO2 and sulfuric acid. Based on the DWL assessment and simulation, it is reasonable to expect vertical profiles of the 3D wind speed with 1 km vertical resolution and horizontal spacing of 25 km to several 100 kms depending upon the desired integration times. These profiles would begin somewhere just below the tops of the highest clouds and extend into the overlying haze layer to some TBD height. Getting multiple layers of cloud returns is also possible with no negative impact on velocity measurement accuracy. With support from the NASA Laser Risk Reduction Program (LRRP) and Instrument Incubator Program (IIP), NASA Langley Research Center has developed a state-of-the-art compact lidar transceiver for a pulsed 2-micron coherent Doppler lidar system for wind measurement in the Earth’s atmosphere [1-3]. The knowledge and expertise for developing coherent Doppler wind lidar technologies and techniques for Earth related mission at NASA LaRC is being leveraged to develop an appropriate system suitable for wind measurement around Venus. We are considering a fiber laser based lidar system of high efficiency and smaller size and advancing the technology level to meet the requirements for DWL system for Venus from an orbiting or floating/flying platform. This presentation will describe the concept, simulation and technology development plan for wind and cloud measurements on Venus. References [1] M.J. Kavaya, U.N. Singh, G.J. Koch, B.C. Trieu, M. Petros, and P.J. Petzar, "Development of a Compact, Pulsed, 2-Micron, Coherent-Detection, Doppler Wind Lidar Transceiver and Plans for Flights on NASA's DC-8 and WB-57 Aircraft," Coherent Laser Radar Conference, Toulouse, France, June 2009. [2] G.J. Koch, J.Y. Beyon, B.W. Barnes, M. Petros, J. Yu, F. Amzajerdian, M.J. Kavaya, and U.N. Singh, "High-Energy 2-micron Doppler Lidar for Wind Measurements," Optical Engineering 46(11), 116201-14 (2007). [3] J.Y. Beyon and G.J. Koch, "Novel Nonlinear Adaptive Doppler Shift Estimation Technique for the Coherent Doppler Validation Lidar," Optical Engineering 46(1), 0160021-9 (2007).

  3. Arctic polar stratospheric cloud observations by airborne lidar

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.; Poole, L. R.; Kent, G. S.; Hunt, W. H.; Osborn, M. T.

    1990-01-01

    Lidar observations obtained from January 24 to February 2, 1989, during the Airborne Arctic Stratospheric expedition (AASE) mission further support the existence of two distinct classes (Types 1 and 2) of polar stratospheric clouds (PSCs). Most of the Type 1 PSCs observed were formed by rapid adiabatic cooling and exhibited very low depolarization ratios and low-to-intermediate scattering ratios. Type 2 PSCs were observed in regions of lowest temperature and showed much larger depolarization and scattering ratios, as would be expected from larger ice crystals. PSCs with low scattering ratios but moderate depolarization ratios were observed near the center of the vortex on one flight. These may have been either sparse Type 2 PSCs or Type 1 PSCs formed by less rapid cooling.

  4. Arctic polar stratospheric cloud observations by airborne lidar

    SciTech Connect

    McCormick, M.P.; Poole, L.R. ); Kent, G.S. ); Hunt, W.H. ); Osborn, M.T.; Pitts, M.C. )

    1990-03-01

    Lidar observations obtained from January 24 to February 2, 1989, during the Airborne Arctic Stratospheric Expedition (AASE) mission further support the existence of two distinct classes (Types 1 and 2) of polar stratospheric clouds (PSCs). Most of the Type 1 PSCs observed were formed by rapid adiabatic cooling and exhibited very low depolarization ratios and low-to-intermediate scattering ratios. Type 2 PSCs were observed in regions of lowest temperature and showed much larger depolarization and scattering ratios, as would be expected from larger ice crystals. PSCs with low scattering ratios but moderate depolarization ratios were observed near the center of the vortex on one flight. These may have been either sparse Type 2 PSCs or Type 1 PSCs formed by less rapid cooling.

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

    E-print Network

    Hogan, Robin

    the cloud fields from the Met Office forecast model to predict 94-GHz radar reflectivity factor, which. In this paper, the spaceborne CloudSat radar and CALIPSO lidar are used to evaluate the global distribution; for example, Delano¨e et al. [2011] used their ice water con- tent retrievals from the CloudSat radar

  6. Lidar multiple scattering models for use in cirrus clouds E. W. Eloranta

    E-print Network

    Eloranta, Edwin W.

    Lidar multiple scattering models for use in cirrus clouds E. W. Eloranta University of Wisconsin was motivated by ongoing efforts to remotely measure particle sizes in cirrus clouds which often contain a very that the diffraction peak can be represented as a Gaussian function of scattering angle (Eloranta, 1998). Cirrus clouds

  7. Evaluation of turbulent dissipation rate retrievals from Doppler cloud radar

    NASA Astrophysics Data System (ADS)

    Shupe, M. D.; Brooks, I. M.; Canut, G.

    2012-01-01

    Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4-6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tethered-balloon and 15-m tower sonic measurements made at spatial distances of a few hundred meters. Moreover, radar retrievals are able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds.

  8. Solid-State Cloud Radar System (CRS) Upgrade and Deployment

    NASA Technical Reports Server (NTRS)

    McLinden, Matt; Heymsfield, Gerald; Li, Lihua; Racette, Paul; Coon, Michael; Venkatesh, Vijay

    2015-01-01

    The recent decade has brought rapid development in solid-state power amplifier (SSPA) technology. This has enabled the use of solid-state precipitation radar in place of high-power and high-voltage systems such as those that use Klystron or Magnetron transmitters. The NASA Goddard Space Flight Center has recently completed a comprehensive redesign of the 94 gigahertz Cloud Radar System (CRS) to incorporate a solid-state transmitter. It is the first cloud radar to achieve sensitivity comparable to that of a high-voltage transmitter using solid-state. The NASA Goddard Space Flight Center's Cloud Radar System (CRS) is a 94 gigahertz Doppler radar that flies on the NASA ER-2 high-altitude aircraft. The upgraded CRS system utilizes a state-of-the-art solid-state 94 gigahertz power amplifier with a peak transmit power of 30 watts. The modernized CRS system is detailed here with data results from its deployment during the 2014 Integrated Precipitation and Hydrology Experiment (IPHEX).

  9. 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.

  10. 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.

  11. G band atmospheric radars: new frontiers in cloud physics

    NASA Astrophysics Data System (ADS)

    Battaglia, A.; Westbrook, C. D.; Kneifel, S.; Kollias, P.; Humpage, N.; Löhnert, U.; Tyynelä, J.; Petty, G. W.

    2014-06-01

    Clouds and associated precipitation are the largest source of uncertainty in current weather and future climate simulations. Observations of the microphysical, dynamical and radiative processes that act at cloud scales are needed to improve our understanding of clouds. The rapid expansion of ground-based super-sites and the availability of continuous profiling and scanning multi-frequency radar observations at 35 and 94 GHz have significantly improved our ability to probe the internal structure of clouds in high temporal-spatial resolution, and to retrieve quantitative cloud and precipitation properties. However, there are still gaps in our ability to probe clouds due to large uncertainties in the retrievals. The present work discusses the potential of G band (frequency between 110 and 300 GHz) Doppler radars in combination with lower frequencies to further improve the retrievals of microphysical properties. Our results show that, thanks to a larger dynamic range in dual-wavelength reflectivity, dual-wavelength attenuation and dual-wavelength Doppler velocity (with respect to a Rayleigh reference), the inclusion of frequencies in the G band can significantly improve current profiling capabilities in three key areas: boundary layer clouds, cirrus and mid-level ice clouds, and precipitating snow.

  12. G-band atmospheric radars: new frontiers in cloud physics

    NASA Astrophysics Data System (ADS)

    Battaglia, A.; Westbrook, C. D.; Kneifel, S.; Kollias, P.; Humpage, N.; Löhnert, U.; Tyynelä, J.; Petty, G. W.

    2014-01-01

    Clouds and associated precipitation are the largest source of uncertainty in current weather and future climate simulations. Observations of the microphysical, dynamical and radiative processes that act at cloud-scales are needed to improve our understanding of clouds. The rapid expansion of ground-based super-sites and the availability of continuous profiling and scanning multi-frequency radar observations at 35 and 94 GHz have significantly improved our ability to probe the internal structure of clouds in high temporal-spatial resolution, and to retrieve quantitative cloud and precipitation properties. However, there are still gaps in our ability to probe clouds due to large uncertainties in the retrievals. The present work discusses the potential of G-band (frequency between 110 and 300 GHz) Doppler radars in combination with lower frequencies to further improve the retrievals of microphysical properties. Our results show that, thanks to a larger dynamic range in dual-wavelength reflectivity, dual-wavelength attenuation and dual-wavelength Doppler velocity (with respect to a Rayleigh reference), the inclusion of frequencies in the G-band can significantly improve current profiling capabilities in three key areas: boundary layer clouds, cirrus and mid-level ice clouds, and precipitating snow.

  13. Dual Wavelength Lidar Observation of Tropical High-Altitude Cirrus Clouds During the ALBATROSS 1996 Campaign

    NASA Technical Reports Server (NTRS)

    Beyerle, G.; Schafer, J.; Neuber, R.; Schrems, O.; McDermid, I. S.

    1998-01-01

    Dual wavelength aerosol lidar observations of tropical high-altitude cirrus clouds were performed during the ALBATROSS 1996 campaign aboard the research vessel POLARSTERN on the Atlantic ocean in October-November 1996.

  14. [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

  15. The importance of ice clouds on the Earth's radiation budget is well recognized. However, due to uncertainties in their properties (e.g. vertically resolved

    E-print Network

    Zadelhoff, Gerd-Jan van

    of the treatment of clouds in models. The EarthCare simulator is used to test the lidar-radar microphysical (left figure for the ARM site). Lidar (top-left) and radar (top-right) measurements of an ice cloud. The top figures show slabs of the model input, extinction (left) and radar reflectivity (right

  16. Studies of ice clouds using 95 GHz airborne radar

    NASA Astrophysics Data System (ADS)

    Wolde, Mengistu Yirdaw

    2000-12-01

    This study presents results from analyses of 95 GHz airborne polarimetric radar measurements and other in situ data in a variety of ice clouds. Measurements were made in winter clouds over Wyoming and Colorado. Radar parameters analyzed were the differential reflectivity factor (ZDR) and the linear depolarization ratio (LDR). Examination of the specific signatures for different crystal forms, and the dependence of the signatures on beam angle, led to a diagnostic matrix in terms ZDR and LDR values. Planar crystals, columnar crystals, and melting particles can be differentiated based on combined ZDR and LDR measurements at various radar elevation angles. Unique LDR signatures were also observed in Cu con. clouds containing large graupel particles and high concentrations of small particles. It is also shown that among planar crystals P1a and P1d types can be differentiated from P1e types. Overall, the frequencies of occurrence of significant polarimetric signatures were only few percent in the cloud volumes examined, but can approach near 100% in certain clouds. Polarimetric signatures were found to be most frequent in the temperature interval -10 to -18°C due to plate-like crystals growing there. The presence of significant polarimetric signatures is associated with the absence of riming and provides a means of identifying cloud regions where diffusional crystal growth dominates. In the second part of the dissertation, cloud structure and crystal growth in Ns clouds sampled in Wyoming and Oregon are presented. In spite of differences in location and time, the two Ns data sets have shown similar features. In both cases, generating cells were present near cloud top and the melting layer was well defined in the radar images. Thin dry layers just above the melting layer were also observed in both cases. In accordance with earlier studies, particle spectra in these clouds are adequately described by exponential relationships. The slope and intercept parameters of the exponential fits have shown strong correlations and follow a power law relationship. The equivalent radar reflectivity, Ze near the nearest usable range gates shows that in general there is negative correlation between ? and Ze.

  17. Error analysis of Raman differential absorption lidar ozone measurements in ice clouds.

    PubMed

    Reichardt, J

    2000-11-20

    A formalism for the error treatment of lidar ozone measurements with the Raman differential absorption lidar technique is presented. In the presence of clouds wavelength-dependent multiple scattering and cloud-particle extinction are the main sources of systematic errors in ozone measurements and necessitate a correction of the measured ozone profiles. Model calculations are performed to describe the influence of cirrus and polar stratospheric clouds on the ozone. It is found that it is sufficient to account for cloud-particle scattering and Rayleigh scattering in and above the cloud; boundary-layer aerosols and the atmospheric column below the cloud can be neglected for the ozone correction. Furthermore, if the extinction coefficient of the cloud is ?0.1 km(-1), the effect in the cloud is proportional to the effective particle extinction and to a particle correction function determined in the limit of negligible molecular scattering. The particle correction function depends on the scattering behavior of the cloud particles, the cloud geometric structure, and the lidar system parameters. Because of the differential extinction of light that has undergone one or more small-angle scattering processes within the cloud, the cloud effect on ozone extends to altitudes above the cloud. The various influencing parameters imply that the particle-related ozone correction has to be calculated for each individual measurement. Examples of ozone measurements in cirrus clouds are discussed. PMID:18354611

  18. Cloud radar Doppler spectra in drizzling stratiform clouds: 2. Observations and microphysical modeling of drizzle evolution

    SciTech Connect

    Kollias, P.; Luke, E.; Szyrmer, W.; Rémillard, J.

    2011-07-02

    In part I, the influence of cloud microphysics and dynamics on the shape of cloud radar Doppler spectra in warm stratiform clouds was discussed. The traditional analysis of radar Doppler moments was extended to include skewness and kurtosis as additional descriptors of the Doppler spectrum. Here, a short climatology of observed Doppler spectra moments as a function of the radar reflectivity at continental and maritime ARM sites is presented. The evolution of the Doppler spectra moments is consistent with the onset and growth of drizzle particles and can be used to assist modeling studies of drizzle onset and growth. Time-height radar observations are used to exhibit the coherency of the Doppler spectra shape parameters and demonstrate their potential to improve the interpretation and use of radar observations. In addition, a simplified microphysical approach to modeling the vertical evolution of the drizzle particle size distribution in warm stratiform clouds is described and used to analyze the observations. The formation rate of embryonic drizzle droplets due to the autoconversion process is not calculated explicitly; however, accretion and evaporation processes are explicitly modeled. The microphysical model is used as input to a radar Doppler spectrum forward model, and synthetic radar Doppler spectra moments are generated. Three areas of interest are studied in detail: early drizzle growth near the cloud top, growth by accretion of the well-developed drizzle, and drizzle depletion below the cloud base due to evaporation. The modeling results are in good agreement with the continental and maritime observations. This demonstrates that steady state one-dimensional explicit microphysical models coupled with a forward model and comprehensive radar Doppler spectra observations offer a powerful method to explore the vertical evolution of the drizzle particle size distribution.

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

    E-print Network

    Baum, Bryan A.

    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

  20. Monostatic lidar/radar invisibility using coated spheres.

    PubMed

    Zhai, Peng-Wang; You, Yu; Kattawar, George W; Yang, Ping

    2008-02-01

    The Lorenz-Mie theory is revisited to explicitly include materials whose permeability is different from unity. The expansion coefficients of the scattered field are given for light scattering by both homogeneous and coated spheres. It is shown that the backscatter is exactly zero if the impedance of the spherical particles is equal to the intrinsic impedance of the surrounding medium. If spherical particles are sufficiently large, the zero backscatter can be explained as impedance matching using the asymptotic expression for the radar backscattering cross section. In the case of a coated sphere, the shell can be regarded as a cloak if the product of the thickness and the imaginary part of the refractive index of the outer shell is large. PMID:18542217

  1. 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.

  2. 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.

  3. Single Doppler radar and lidar studies of the dynamics of mixed layers and overlying stable regions

    NASA Technical Reports Server (NTRS)

    Xu, Mei; Gal-Chen, Tzvi

    1991-01-01

    Some examples of profiles of PBL quantities retrieved from Doppler radar and lidar observations are shown, and the extent to which the deduced quantities agree with the traditional eddy viscosity concept is examined. It is found in one case that the concept of 'top down bottom up' diffusion introduced by Wyngaard (1983) is more pertinent than that of the eddy viscosity. In another case it is found that, in stable layers with sufficiently large Richardson number, the momentum fluxes could be counter-gradient. In this latter case the use of a negative turbulence diffusion coefficient would result in an ill-posed differential equation, thus confusing the 'diffusion problem'.

  4. Analysis of airborne Doppler lidar, Doppler radar and tall tower measurements of atmospheric flows in quiescent and stormy weather

    NASA Technical Reports Server (NTRS)

    Bluestein, H. B.; Doviak, R. J.; Eilts, M. D.; Mccaul, E. W.; Rabin, R.; Sundara-Rajan, A.; Zrnic, D. S.

    1986-01-01

    The first experiment to combine airborne Doppler Lidar and ground-based dual Doppler Radar measurements of wind to detail the lower tropospheric flows in quiescent and stormy weather was conducted in central Oklahoma during four days in June-July 1981. Data from these unique remote sensing instruments, coupled with data from conventional in-situ facilities, i.e., 500-m meteorological tower, rawinsonde, and surface based sensors, were analyzed to enhance understanding of wind, waves and turbulence. The purposes of the study were to: (1) compare winds mapped by ground-based dual Doppler radars, airborne Doppler lidar, and anemometers on a tower; (2) compare measured atmospheric boundary layer flow with flows predicted by theoretical models; (3) investigate the kinematic structure of air mass boundaries that precede the development of severe storms; and (4) study the kinematic structure of thunderstorm phenomena (downdrafts, gust fronts, etc.) that produce wind shear and turbulence hazardous to aircraft operations. The report consists of three parts: Part 1, Intercomparison of Wind Data from Airborne Lidar, Ground-Based Radars and Instrumented 444 m Tower; Part 2, The Structure of the Convective Atmospheric Boundary Layer as Revealed by Lidar and Doppler Radars; and Part 3, Doppler Lidar Observations in Thunderstorm Environments.

  5. Detecting thermally driven cyclic deformation of an exfoliation sheet with lidar and radar

    USGS Publications Warehouse

    Collins, Brian D.; Stock, Greg M.

    2014-01-01

    Rock falls from steep, exfoliating cliffs are common in many landscapes. Of the many mechanisms known to trigger rock falls, thermally driven deformation is among the least quantified, despite potentially being a prevalent trigger due to its occurrence at all times of year. Here we present the results of a field-based monitoring program using instrumentation, ground-based lidar, and ground-based radar to investigate the process of thermally driven deformation of an exfoliation sheet, and the ability of remote sensing tools to capture cyclic expansion and contraction patterns. Our results indicate that thermally driven exfoliation occurs on diurnal cycles and can be measured at the submillimeter to centimeter scale using high-resolution strain gauges, short-range (2 km) radar interfer-ometry.

  6. Analysis of polarization radar returns from ice clouds

    NASA Astrophysics Data System (ADS)

    Battaglia, A.; Sturniolo, O.; Prodi, F.

    Using a modified T-matrix code, some polarimetric single-scattering radar parameters ( Zh,v, LDR h,v, ?hv, ZDR and ?hv) from populations of ice crystals in ice phase at 94 GHz, modeled with axisymmetric prolate and oblate spheroidal shapes for a ?-size distribution with different ? parameter ( ?=0, 1, 2) and characteristic dimension Lm varying from 0.1 to 1.8 mm, have been computed. Some of the results for different radar elevation angles and different orientation distribution for fixed water content are shown. Deeper analysis has been carried out for pure extensive radar polarimetric variables; all of them are strongly dependent on the shapes (characterised by the aspect ratio), the canting angle and the radar elevation angle. Quantities like ZDR or ?hv at side incidence or LDR h and ?hv at vertical incidence can be used to investigate the preferred orientation of the particles and, in some cases, their habits. We analyze scatterplots using couples of pure extensive variables. The scatterplots with the most evident clustering properties for the different habits seem to be those in the ( ZDR [ ?=0°], ?hv [ ?=0°]), in the ( ZDR [ ?=0°], LDR h [ ?=90°]) and in the ( ZDR [ ?=0°], ?hv [ ?=90°]) plane. Among these, the most appealing one seems to be that involving ZDR and ?hv variables. To avoid the problem of having simultaneous measurements with a side and a vertical-looking radar, we believe that measurements of these two extensive variables using a radar with an elevation angle around 45° can be an effective instrument to identify different habits. In particular, this general idea can be useful for future space-borne polarimetric radars involved in the studies of high ice clouds. It is also believed that these results can be used in next challenge of developing probabilistic and expert methods for identifying hydrometeor types by W-band radars.

  7. Cloud-Resolving Model Simulations of KWAJEX: Model Sensitivities and Comparisons with Satellite and Radar Observations

    E-print Network

    Bretherton, Chris

    and precipitation observations, including radar reflectivities from the Kwajalein ground validation radar) and insufficient albedo. The simu- lated radar reflectivities tend to be excessive, especially in the upper rainfall retrieval algorithms. However, its combination of radar and in situ sensing of cloud microphysics

  8. Stratospheric Clouds at South Pole During 1988 1. Results of Lidar Observations and Their Relationship to Temperature

    NASA Astrophysics Data System (ADS)

    Fiocco, Giorgio; Cacciani, Marco; Di Girolamo, Paolo; Fuà, Danielle; DeLuisi, John

    1992-04-01

    An optical radar-lidar-has been operational at the Amundsen-Scott South Pole Station since summer 1987-1988. The observations were specially directed to the detection of aerosol layers and polar stratospheric clouds (PSCs). The lidar utilized a Nd-YAG laser followed by a second harmonic generator, and a 0.5-m diameter Cassegrain receiving telescope. Results obtained during the period May-October 1988 are summarized. Some 10,000 profiles of the lidar echoes, each the result of 1-min averaging, were obtained. Data sets consisting of profiles of the scattering ratio and of the backscattering cross section Ba, based on half-hour averaging, are presented. The data can be related to profiles of the atmospheric temperature T, usually obtained on a daily basis at South Pole. Stratifications appear to have two distinct types of structures: one structure shows only a modest variation with height; the other is characterized by sharp features, with large changes of the cross section with height. The basic results, the relationship between Ba, and T, and their statistical relevance are considered in this paper. The microphysical interpretation, the attribution of these structures to PSC Type I and Type II, respectively involving the condensation of nitric acid trihydrate and of water ice, and the seasonal evolution of the phenomena are treated in a companion paper.

  9. 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.

  10. Three-dimensional lidar point-cloud visualization and analysis of coseismic deformation using LidarViewer

    NASA Astrophysics Data System (ADS)

    Oskin, M. E.; Kreylos, O.; Banesh, D.; Hamann, B.; Gold, P. O.; Elliott, A. J.; Hinojosa, A.; Kellogg, L. H.

    2012-12-01

    We summarize new point-cloud analysis techniques, and results obtained from lidar data collected from the 2010 El Mayor-Cucapah earthquake surface rupture, using LidarViewer, an open-source software platform developed at the UC Davis KeckCAVES. Imaging of earthquake deformation with multi-resolution and multi-temporal lidar presents several challenges for visualization and analysis. Instruments, data resolution, and even the geodetic reference frame may change significantly between surveys. Grid-based techniques fail to adequately represent fully 3-D features, such as scarps and vegetation, and introduce aliasing artifacts that are especially troublesome when the deformation signal sought is less than the point spacing. Once obtained, the resulting dense field of 3-D vectors derived from differential lidar are difficult to visualize together with the terrain, limiting interpretation of these results. Points are the native, resolution-independent format of lidar, but working with massive point data sets can overwhelm system memory. LidarViewer overcomes these challenges using hierarchal data storage, view-dependent rendering, and an efficient, recursive data analysis framework. Pre-earthquake airborne lidar, collected as part of a regional survey, are very sparse (0.013 pts/m2) compared to the post-earthquake survey (9 pts/m2). A simple, \\chi2 minimization approach to matching these data sets takes advantage of this dramatic resolution difference to extract 3-D ground motion. We visualize the resulting displacement field in a 3-D environment using streamline-based approaches, colored by elevation change, and superimposed on the post-earthquake topography. This fused data product encourages exploration and assessment of the deformation signal and its relationship to landscape features, such as fault scarps, vegetation, and topographic relief. Terrestrial lidar scans collected within two weeks of the earthquake reveal the surface rupture at centimeter resolution. Virtual field measurements of offset features were collected using the full point-cloud in an immersive 3-D cave environment. Repeat measurements, both at a point and along strike, reveal substantial epistemic (interpretive) uncertainty that is generally greater than that reported by geologists working in the field after an earthquake. Combining observations from differential airborne and post-earthquake terrestrial lidar from the strike-slip Borrego fault reveals smooth coseismic slip gradients of ˜ 10-3, similar to strains measured from ground-surface deformation across strike. Higher strains are found along the Paso Superior normal fault surface rupture, due largely to distributed faulting and sagging of the hangingwall.

  11. 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.

  12. Lidar Observations of Polar Stratospheric Clouds and Stratospheric Temperatures at the South Pole

    NASA Technical Reports Server (NTRS)

    Collins, Richard L.; Bowman, Kenneth P.; Gardner, Chester S.

    1992-01-01

    Polar stratospheric clouds (PSC's) play a crucial role in the ozone chemistry of the polar regions. Current chemical models rely on the presence of these clouds to explain the rapid destruction of ozone observed each spring in Antarctica. We present lidar observations of PCS's and stratospheric temperatures at the South Pole throughout the Antarctic winter and spring of 1990.

  13. Strong aerosol-cloud interaction in altocumulus during updraft periods: lidar observations over central Europe

    NASA Astrophysics Data System (ADS)

    Schmidt, J.; Ansmann, A.; Bühl, J.; Wandinger, U.

    2015-09-01

    For the first time, a liquid-water cloud study of the aerosol-cloud-dynamics relationship, solely based on lidar, was conducted. Twenty-nine cases of pure liquid-water altocumulus layers were observed with a novel dual-field-of-view Raman lidar over the polluted central European site of Leipzig, Germany, between September 2010 and September 2012. By means of the novel Raman lidar technique, cloud properties such as the droplet effective radius and cloud droplet number concentration (CDNC) in the lower part of altocumulus layers are obtained. The conventional aerosol Raman lidar technique provides the aerosol extinction coefficient (used as aerosol proxy) below cloud base. A collocated Doppler lidar measures the vertical velocity at cloud base and thus updraft and downdraft occurrence. Here, we present the key results of our statistical analysis of the 2010-2012 observations. Besides a clear aerosol effect on cloud droplet number concentration in the lower part of the altocumulus layers during updraft periods, turbulent mixing and entrainment of dry air is assumed to be the main reason for the found weak correlation between aerosol proxy and CDNC higher up in the cloud. The corresponding aerosol-cloud interaction parameter based on changes in cloud droplet number concentration with aerosol loading was found to be close to 0.8 at 30-70 m above cloud base during updraft periods and below 0.4 when ignoring vertical-wind information in the analysis. Our findings are extensively compared with literature values and agree well with airborne observations.

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

    SciTech Connect

    S, Motty G Satyanarayana, M. Krishnakumar, V. Dhaman, Reji k.

    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.

  15. UV Raman lidar measurements of relative humidity for the characterization of cirrus cloud microphysical properties

    NASA Astrophysics Data System (ADS)

    di Girolamo, P.; Summa, D.; Lin, R.-F.; Maestri, T.; Rizzi, R.; Masiello, G.

    2009-07-01

    Raman lidar measurements performed in Potenza by the Raman lidar system BASIL in the presence of cirrus clouds are discussed. Measurements were performed on 6 September 2004 in the frame of Italian phase of the EAQUATE Experiment. The major feature of BASIL is represented by its capability to perform high-resolution and accurate measurements of atmospheric temperature and water vapour, and consequently relative humidity, both in daytime and night-time, based on the application of the rotational and vibrational Raman lidar techniques in the UV. BASIL is also capable to provide measurements of the particle backscatter and extinction coefficient, and consequently lidar ratio (at the time of these measurements only at one wavelength), which are fundamental to infer geometrical and microphysical properties of clouds. A case study is discussed in order to assess the capability of Raman lidars to measure humidity in presence of cirrus clouds, both below and inside the cloud. While air inside the cloud layers is observed to be always under-saturated with respect to water, both ice super-saturation and under-saturation conditions are found inside these clouds. Upper tropospheric moistening is observed below the lower cloud layer. The synergic use of the data derived from the ground based Raman Lidar and of spectral radiances measured by the NAST-I Airborne Spectrometer allows to determine the temporal evolution of the atmospheric cooling/heating rates due to the presence of the cirrus cloud anvil. Lidar measurements beneath the cirrus cloud layer have been interpreted using a 1-D cirrus cloud model with explicit microphysics. The 1-D simulations indicates that sedimentation-moistening has contributed significantly to the moist anomaly, but other mechanisms are also contributing. This result supports the hypothesis that the observed mid-tropospheric humidification is a real feature which is strongly influenced by the sublimation of precipitating ice crystals. Results illustrated in this study demonstrate that Raman lidars, like the one used in this study, can resolve the spatial and temporal scales required for the study of cirrus cloud microphysical processes and appears sensitive enough to reveal and quantify upper tropospheric humidification associated with cirrus cloud sublimation.

  16. UV Raman lidar measurements of relative humidity for the characterization of cirrus cloud microphysical properties

    NASA Astrophysics Data System (ADS)

    di Girolamo, P.; Summa, D.; Lin, R.-F.; Maestri, T.; Rizzi, R.; Masiello, G.

    2009-11-01

    Raman lidar measurements performed in Potenza by the Raman lidar system BASIL in the presence of cirrus clouds are discussed. Measurements were performed on 6 September 2004 in the frame of the Italian phase of the EAQUATE Experiment. The major feature of BASIL is represented by its capability to perform high-resolution and accurate measurements of atmospheric temperature and water vapour, and consequently relative humidity, both in daytime and night-time, based on the application of the rotational and vibrational Raman lidar techniques in the UV. BASIL is also capable to provide measurements of the particle backscatter and extinction coefficient, and consequently lidar ratio (at the time of these measurements, only at one wavelength), which are fundamental to infer geometrical and microphysical properties of clouds. A case study is discussed in order to assess the capability of Raman lidars to measure humidity in presence of cirrus clouds, both below and inside the cloud. While air inside the cloud layers is observed to be always under-saturated with respect to water, both ice super-saturation and under-saturation conditions are found inside these clouds. Upper tropospheric moistening is observed below the lower cloud layer. The synergic use of the data derived from the ground based Raman Lidar and of spectral radiances measured by the NAST-I Airborne Spectrometer allows the determination of the temporal evolution of the atmospheric cooling/heating rates due to the presence of the cirrus cloud. Lidar measurements beneath the cirrus cloud layer have been interpreted using a 1-D cirrus cloud model with explicit microphysics. The 1-D simulations indicate that sedimentation-moistening has contributed significantly to the moist anomaly, but other mechanisms are also contributing. This result supports the hypothesis that the observed mid-tropospheric humidification is a real feature which is strongly influenced by the sublimation of precipitating ice crystals. Results illustrated in this study demonstrate that Raman lidars, like the one used in this study, can resolve the spatial and temporal scales required for the study of cirrus cloud microphysical processes and appear sensitive enough to reveal and quantify upper tropospheric humidification associated with cirrus cloud sublimation.

  17. First results of combined Fe-lidar/Radar measurements at Davis, 69° S.

    NASA Astrophysics Data System (ADS)

    Höffner, J.; Morris, R. J.; Kaifler, B.; Viehl, T.; Lübken, F.-J.

    2012-04-01

    The mobile scanning Fe-lidar of the IAP-Kühlungsborn was moved to Davis, Antarctica, 69° S, 78° E during November 2010. This location was chosen because PMSE/NLC observations by MST-radar/RMR-lidar have been performed since 2003/2001 by the Australian Antarctic Division. Davis is the only station in Antarctica where comparable long-term observations to Alomar, 69° N are available. A comparison of both locations allows a detailed comparison of differences or similarities between the northern (NH) / southern hemisphere (SH) at mesopause altitudes. The Fe-lidar is a two wavelength system which measures Doppler temperature/vertical wind and iron densities by resonance scattering at 386 nm. The fundamental wavelength at 772 nm is used for aerosol measurements from the stratosphere to the mesosphere including NLC in summer or PSC in winter. Measurements are almost background free which allows year round operation independent of sunlight. At Davis the lidar was in operation 24% of the first year (2150 hours) which has not been achieved elsewhere with a mesospheric lidar. This unusual and already largest lidar data base of Antarctica shows the thermal structure of the mesopause region and the iron layer in great detail. Strong tides throughout the year have been observed and a link of the early part of the PMSE season to the stratospheric vortex has been found. More than 700 hours of temperature observation during the PMSE-season are compared with common volume PMSE/NLC observations. For the first time temperature and vertical wind measurements through PMSE and NLC have been achieved by a lidar showing that the SH in particular in December/January differs significantly from the NH in June/July. The temperature measurements near 86 km altitude show that the summer mesopause is surprisingly similar to the NH at PMSE altitudes but differs significantly at higher altitudes. Unlike the NH the southern mesopause altitude changes throughout the season by several kilometres. Depending on altitude temperatures can be warmer but also much colder than at the NH causing a change in PMSE altitude over the season.

  18. Comparison of ground-based LiDAR and ground-based radar of southwestern Colorado snowpack

    NASA Astrophysics Data System (ADS)

    Deeb, E. J.; Marshall, H.; Finnegan, D. C.; Deems, J. S.; Landry, C.

    2011-12-01

    New technologies and instrumentation can provide high resolution sampling of the spatial distribution of snowpack parameters such as snow depth, stratigraphy, and SWE at speeds and resolutions that are orders of magnitude larger than traditional manual observations. Both LiDAR and radar techniques have emerged as efficient tools for the characterization of snow at the study plot to basin scale. In this work, ground-based LiDAR scanning of the snow surface at Swamp Angel Study Plot, Senator Beck Basin, Colorado was performed in April 2010. The full-waveform scanning LiDAR operates at 1550-nm collecting both range measurements and calibrated intensity. The vertical/horizontal resolution is 0.015 degrees resulting in 3.3 million points in 5.5 minutes. Five different scanning positions were collected, registered, and geo-located. In a coordinated effort, a mobile FMCW radar (4-18 GHz) was deployed though the same study plot to collect transects for estimating snow depth, stratigraphy, and SWE. Precision differential GPS provided cm-level positions for each radar trace, which were acquired at a rate of 50 traces per second. In September 2010, ground-based LiDAR scans of the underlying terrain without snow were collected/processed and, in combination with the April 2010 snow surface, are used to derive a continuous model of snow depth distribution. The September 2010 snow-off surface is also compared to available digital elevation models for this area. Direct comparisons of the depths estimated by ground-based radar and the depths from the ground-based LiDAR model are performed. Volume calculations from the ground-based LiDAR snow depth model are presented and compared to that estimated from the radar transects.

  19. Micropulse Lidar (MPL) Handbook

    SciTech Connect

    Mendoza, A; Flynn, C

    2006-05-01

    The micropulse lidar (MPL) is a ground-based optical remote sensing system designed primarily to determine the altitude of clouds overhead. The physical principle is the same as for radar. Pulses of energy are transmitted into the atmosphere; the energy scattered back to the transceiver is collected and measured as a time-resolved signal. From the time delay between each outgoing transmitted pulse and the backscattered signal, the distance to the scatterer is infered. Besides real-time detection of clouds, post-processing of the lidar return can also characterize the extent and properties of aerosol or other particle-laden regions.

  20. NOTES AND CORRESPONDENCE CloudSat as a Global Radar Calibrator

    E-print Network

    Protat, Alain

    - scattering cross section becomes nearly independent of surface wind speed (Durden et al. 2003) and takesNOTES AND CORRESPONDENCE CloudSat as a Global Radar Calibrator A. PROTAT,*,1 D. BOUNIOL,# E. J. O May 2010) ABSTRACT The calibration of the CloudSat spaceborne cloud radar has been thoroughly assessed

  1. OBJECTIVE DETERMINATION OF 3D CLOUD LOCATIONS USING SCANNING MILLIMETER-WAVELENGTH RADARS

    E-print Network

    OBJECTIVE DETERMINATION OF 3D CLOUD LOCATIONS USING SCANNING MILLIMETER-WAVELENGTH RADARS Pavlos-parametric radar measurements is the objective determination of 3D cloud locations (3D- ARSCL: Active Remote to develop an objective methodology for the determination of 3D cloud locations. __________ NOTICE

  2. 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.

    2015-11-01

    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 from the ALOS and lidar from the ICESat Earth-Observing satellites with 56 field 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 was 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 was 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), in conjunction with lidar data, it is possible to make reliable estimates of not just the area but also the carbon emissions resulting from land use change.

  3. Influence of daylight and noise current on cloud and aerosol observations by spaceborne elastic scattering lidar.

    PubMed

    Nakajima, T Y; Imai, T; Uchino, O; Nagai, T

    1999-08-20

    The influence of daylight and noise current on cloud and aerosol observations by realistic spaceborne lidar was examined by computer simulations. The reflected solar radiations, which contaminate the daytime return signals of lidar operations, were strictly and explicitly estimated by accurate radiative transfer calculations. It was found that the model multilayer cirrus clouds and the boundary layer aerosols could be observed during the daytime and the nighttime with only a few laser shots. However, high background noise and noise current make it difficult to observe volcanic aerosols in middle and upper atmospheric layers. Optimal combinations of the laser power and receiver field of view are proposed to compensate for the negative influence that is due to these noises. For the computer simulations, we used a realistic set of lidar parameters similar to the Experimental Lidar in-Space Equipment of the National Space Development Agency of Japan. PMID:18324021

  4. 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.

  5. 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.

  6. Radar/Lidar Sensor Fusion for Car-Following on Highways Daniel Gohring, Miao Wang, Michael Schnurmacher, Tinosch Ganjineh

    E-print Network

    Rojas, Raúl

    Car "MadeInGermany" about vehicles driving ahead. Here, this is accomplished by combining data fromRadar/Lidar Sensor Fusion for Car-Following on Highways Daniel G¨ohring, Miao Wang, Michael Schn-time algorithm which enables an autonomous car to comfortably follow other cars at various speeds while keeping

  7. Polar stratospheric cloud measurements by means of depolarization lidar in the Antarctic

    NASA Technical Reports Server (NTRS)

    Stefanutti, L.

    1991-01-01

    POLE (Polar Ozone Lidar Experiment) is a cooperative project between the French and Italian services. It was started with the implementation of a first depolarization backscattering lidar for measurements both of background stratospheric aerosols and Polar Stratospheric Clouds (PSCs). A complex Ozone lidar was also installed which will replace the backscattering system and extend its measurements to tropospheric and stratospheric Ozone and to stratospheric and mesospheric temperatures. This new system allows also the measurement of the backscattered and depolarized signal produced by PSCs and background aerosols. The depolarization technique seemed to be quite efficient in the detection of different types of PSCs.

  8. Autonomous, Full-Time Cloud Profiling at Arm Sites with Micro Pulse Lidar

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D.; Campbell, James R.; Hlavka, Dennis L.; Scott, V. Stanley; Flynn, Connor J.

    2000-01-01

    Since the early 1990's technology advances permit ground based lidar to operate full time and profile all significant aerosol and cloud structure of the atmosphere up to the limit of signal attenuation. These systems are known as Micro Pulse Lidars (MPL), as referenced by Spinhirne (1993), and were first in operation at DOE Atmospheric Radiation Measurement (ARM) sites. The objective of the ARM program is to improve the predictability of climate change, particularly as it relates to cloud-climate feedback. The fundamental application of the MPL systems is towards the detection of all significant hydrometeor layers, to the limit of signal attenuation. The heating and cooling of the atmosphere are effected by the distribution and characteristics of clouds and aerosol concentration. Aerosol and cloud retrievals in several important areas can only be adequately obtained with active remote sensing by lidar. For cloud cover, the height and related emissivity of thin clouds and the distribution of base height for all clouds are basic parameters for the surface radiation budget, and lidar is essetial for accurate measurements. The ARM MPL observing network represents the first long-term, global lidar study known within the community. MPL systems are now operational at four ARM sites. A six year data set has been obtained at the original Oklahoma site, and there are several years of observations at tropical and artic sites. Observational results include cloud base height distributions and aerosol profiles. These expanding data sets offer a significant new resource for cloud, aerosol and atmospheric radiation analysis. The nature of the data sets, data processing algorithms, derived parameters and application results are presented.

  9. Using MSG-SEVIRI Cloud Physical Properties and Weather Radar Observations for the Detection of Cb/TCu Clouds

    E-print Network

    Schmeits, Maurice

    Using MSG-SEVIRI Cloud Physical Properties and Weather Radar Observations for the Detection of Cb/towering cumulus (Cb/TCu) cloud detection method for the months of May­September is presented that combines. First, a pixel-based convective cloud mask (CCM) is con- structed on the basis of cloud physical

  10. P2A.4 On the vertical profile of stratus liquid water flux using a millimeter cloud radar Shelby Frisch

    E-print Network

    Zuidema, Paquita

    using cloud radars have been used to retrieve the effective radius from the reflectivity measurements water flux due to the cloud fall velocity can be evaluated using cloud radar reflectivity measurementsP2A.4 On the vertical profile of stratus liquid water flux using a millimeter cloud radar Shelby

  11. HIGH-RESOLUTION RETRIEVAL OF CLOUD LIQUID WATER PROFILES USING THE COLLOCATED ARM Ka-AND W-BAND RADARS

    E-print Network

    height of drizzling clouds -- something that is very difficult to determine from radar reflectivity alone of the existing radar algorithms for retrieving cloud liquid water content (LWC) make use of empirical Z resolved cloud LWC at high temporal and spatial resolution is achievable using operational cloud radars

  12. Reducing Surface Clutter in Cloud Profiling Radar Data

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Pak, Kyung; Durden, Stephen; Im, Eastwood

    2008-01-01

    An algorithm has been devised to reduce ground clutter in the data products of the CloudSat Cloud Profiling Radar (CPR), which is a nadir-looking radar instrument, in orbit around the Earth, that measures power backscattered by clouds as a function of distance from the instrument. Ground clutter contaminates the CPR data in the lowest 1 km of the atmospheric profile, heretofore making it impossible to use CPR data to satisfy the scientific interest in studying clouds and light rainfall at low altitude. The algorithm is based partly on the fact that the CloudSat orbit is such that the geodetic altitude of the CPR varies continuously over a range of approximately 25 km. As the geodetic altitude changes, the radar timing parameters are changed at intervals defined by flight software in order to keep the troposphere inside a data-collection time window. However, within each interval, the surface of the Earth continuously "scans through" (that is, it moves across) a few range bins of the data time window. For each radar profile, only few samples [one for every range-bin increment ((Delta)r = 240 m)] of the surface-clutter signature are available around the range bin in which the peak of surface return is observed, but samples in consecutive radar profiles are offset slightly (by amounts much less than (Delta)r) with respect to each other according to the relative change in geodetic altitude. As a consequence, in a case in which the surface area under examination is homogenous (e.g., an ocean surface), a sequence of consecutive radar profiles of the surface in that area contains samples of the surface response with range resolution (Delta)p much finer than the range-bin increment ((Delta)p << r). Once the high-resolution surface response has thus become available, the profile of surface clutter can be accurately estimated by use of a conventional maximum-correlation scheme: A translated and scaled version of the high-resolution surface response is fitted to the observed low-resolution profile. The translation and scaling factors that optimize the fit in a maximum-correlation sense represent (1) the true position of the surface relative to the sampled surface peak and (2) the magnitude of the surface backscatter. The performance of this algorithm has been tested on CloudSat data acquired over an ocean surface. A preliminary analysis of the test data showed a surface-clutter-rejection ratio over flat surfaces of >10 dB and a reduction of the contaminated altitude over ocean from about 1 km to about 0.5 km (over the ocean). The algorithm has been embedded in CloudSat L1B processing as of Release 04 (July 2007), and the estimated flat surface clutter is removed in L2B-GEOPROF product from the observed profile of reflectivity (see CloudSat product documentation for details and performance at http://www.cloudsat.cira.colostate.edu/ dataSpecs.php?prodid=1).

  13. Scanning Cloud Radar Observations at Azores: Preliminary 3D Cloud Products

    SciTech Connect

    Kollias, P.; Johnson, K.; Jo, I.; Tatarevic, A.; Giangrande, S.; Widener, K.; Bharadwaj, N.; Mead, J.

    2010-03-15

    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 a prelude for the type of 3D cloud observations that ARM will have the capability to provide at all the ARM Climate Research Facility sites by the end of 2010. The primary objective of the deployment of Scanning ARM Cloud Radars (SACRs) at the ARM Facility sites is to map continuously (operationally) the 3D structure of clouds and shallow precipitation and to provide 3D microphysical and dynamical retrievals for cloud life cycle and cloud-scale process studies. This is a challenging task, never attempted before, and requires significant research and development efforts in order to understand the radar's capabilities and limitations. At the same time, we need to look beyond the radar meteorology aspects of the challenge and ensure that the hardware and software capabilities of the new systems are utilized for the development of 3D data products that address the scientific needs of the new Atmospheric System Research (ASR) program. The SWACR observations at Azores provide a first look at such observations and the challenges associated with their analysis and interpretation. The set of scan strategies applied during the SWACR deployment and their merit is discussed. The scan strategies were adjusted for the detection of marine stratocumulus and shallow cumulus that were frequently observed at the Azores deployment. Quality control procedures for the radar reflectivity and Doppler products are presented. Finally, preliminary 3D-Active Remote Sensing of Cloud Locations (3D-ARSCL) products on a regular grid will be presented, and the challenges associated with their development discussed. In addition to data from the Azores deployment, limited data from the follow-up deployment of the SWACR at the ARM SGP site will be presented. This effort provides a blueprint for the effort required for the development of 3D cloud products from all new SACRs that the program will deploy at all fixed and mobile sites by the end of 2010.

  14. Coherent lidar imaging of dust clouds: waveform comparison with the poly-phase (P4) modulation waveform

    NASA Astrophysics Data System (ADS)

    Youmans, Douglas G.

    2008-04-01

    A dust or aerosol cloud represents a convenient target to examine the capabilities of range-resolved Doppler and intensity (RRDI) or inverse synthetic aperture ladar (ISAR) imaging coherent laser radar, known as coherent "lidar" for optically thin targets. The poly-phase P4 ladar waveform and its RRDI images are described and compared with previous pulse-burst, linear-FM chirp pulse-compression, pseudo-random phase modulation waveforms, and several other waveforms which have not been utilized to date. A "dust cloud" has very many independently moving point scatterers with velocities that are approximately Gaussian randomly distributed in x,y,z with standard deviations of about 10% of the mean wind + aerosol velocity. This is contrary to a hard-target where the point scatterers are rigidly attached and moving together. The dust cloud produced speckle effects for the various ladar waveforms are compared. In addition, a reference set of four corner-cube retro-reflectors within the dust cloud further illustrates the differences in the various waveform capabilities and resolution.

  15. GPGPU-based parallel processing of massive LiDAR point cloud

    NASA Astrophysics Data System (ADS)

    Zeng, Xun; He, Wei

    2009-10-01

    Processing the massive LiDAR point cloud is a time consuming process due to the magnitude of the data involved and the highly computational iterative nature of the algorithms. In particular, many current and future applications of LiDAR require real- or near-real-time processing capabilities. Relevant examples include environmental studies, military applications, tracking and monitoring of hazards. Recent advances in Graphics Processing Units (GPUs) open a new era of General-Purpose Processing on Graphics Processing Units (GPGPU). In this paper, we seek to harness the computing power available on contemporary Graphic Processing Units (GPUs), to accelerate the processing of massive LiDAR point cloud. We propose a CUDA-based method capable of accelerating processing of massive LiDAR point cloud on the CUDA-enabled GPU. Our experimental results showed that we are able to significantly reduce processing time of constructing TIN from LiDAR point cloud with GPGPU based parallel processing implementation, in comparison with the current state-of-the-art CPU-based algorithms.

  16. 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

    In this paper the results of an investigation are presented that are concerned with the feasibility of employing a weather radar to make precise measurements of the properties of a precipitating cloud. A schematic cloud is proposed as a model...

  17. Cloud and Aerosol Retrieval for the 2001 GLAS Satellite Lidar Mission

    NASA Technical Reports Server (NTRS)

    Hart, William D.; Palm, Stephen P.; Spinhirne, James D.

    2000-01-01

    The Geoscience Laser Altimeter System (GLAS) is scheduled for launch in July of 2001 aboard the Ice, Cloud and Land Elevation Satellite (ICESAT). In addition to being a precision altimeter for mapping the height of the Earth's icesheets, GLAS will be an atmospheric lidar, sensitive enough to detect gaseous, aerosol, and cloud backscatter signals, at horizontal and vertical resolutions of 175 and 75m, respectively. GLAS will be the first lidar to produce temporally continuous atmospheric backscatter profiles with nearly global coverage (94-degree orbital inclination). With a projected operational lifetime of five years, GLAS will collect approximately six billion lidar return profiles. The large volume of data dictates that operational analysis algorithms, which need to keep pace with the data yield of the instrument, must be efficient. So, we need to evaluate the ability of operational algorithms to detect atmospheric constituents that affect global climate. We have to quantify, in a statistical manner, the accuracy and precision of GLAS cloud and aerosol observations. Our poster presentation will show the results of modeling studies that are designed to reveal the effectiveness and sensitivity of GLAS in detecting various atmospheric cloud and aerosol features. The studies consist of analyzing simulated lidar returns. Simulation cases are constructed either from idealized renditions of atmospheric cloud and aerosol layers or from data obtained by the NASA ER-2 Cloud Lidar System (CLS). The fabricated renditions permit quantitative evaluations of operational algorithms to retrieve cloud and aerosol parameters. The use of observational data permits the evaluations of performance for actual atmospheric conditions. The intended outcome of the presentation is that climatology community will be able to use the results of these studies to evaluate and quantify the impact of GLAS data upon atmospheric modeling efforts.

  18. 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.

  19. Optical and morphological properties of Cirrus clouds determined by the high spectral resolution lidar during FIRE

    NASA Technical Reports Server (NTRS)

    Grund, Christian John; Eloranta, Edwin W.

    1990-01-01

    Cirrus clouds reflect incoming solar radiation and trap outgoing terrestrial radiation; therefore, accurate estimation of the global energy balance depends upon knowledge of the optical and physical properties of these clouds. Scattering and absorption by cirrus clouds affect measurements made by many satellite-borne and ground based remote sensors. Scattering of ambient light by the cloud, and thermal emissions from the cloud can increase measurement background noise. Multiple scattering processes can adversely affect the divergence of optical beams propagating through these clouds. Determination of the optical thickness and the vertical and horizontal extent of cirrus clouds is necessary to the evaluation of all of these effects. Lidar can be an effective tool for investigating these properties. During the FIRE cirrus IFO in Oct. to Nov. 1986, the High Spectral Resolution Lidar (HSRL) was operated from a rooftop site on the campus of the University of Wisconsin at Madison, Wisconsin. Approximately 124 hours of fall season data were acquired under a variety of cloud optical thickness conditions. Since the IFO, the HSRL data set was expanded by more than 63.5 hours of additional data acquired during all seasons. Measurements are presented for the range in optical thickness and backscattering phase function of the cirrus clouds, as well as contour maps of extinction corrected backscatter cross sections indicating cloud morphology. Color enhanced images of range-time indicator (RTI) displays a variety of cirrus clouds with approximately 30 sec time resolution are presented. The importance of extinction correction on the interpretation of cloud height and structure from lidar observations of optically thick cirrus are demonstrated.

  20. 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

    particles (i.e., hy- drometeors). If the scatterer’s locations are uncorrelated, the ensemble average of the second summation is zero (i.e., hpc 5 0), and there remains only the commonly observed incoherent hydrometeor backscatter. But if there is spatial... role in determining the global radiation balance. A large amount of cloud data has been obtained with millimeter-wavelength radars. The use of short wavelengths makes it possible to achieve a very high level of spatial resolution with relatively small...

  1. 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.

  2. Classification of particle effective shape ratios in cirrus clouds based on the lidar depolarization ratio.

    PubMed

    Noel, Vincent; Chepfer, Helene; Ledanois, Guy; Delaval, Arnaud; Flamant, Pierre H

    2002-07-20

    A shape classification technique for cirrus clouds that could be applied to future spaceborne lidars is presented. A ray-tracing code has been developed to simulate backscattered and depolarized lidar signals from cirrus clouds made of hexagonal-based crystals with various compositions and optical depth, taking into account multiple scattering. This code was used first to study the sensitivity of the linear depolarization rate to cloud optical and microphysical properties, then to classify particle shapes in cirrus clouds based on depolarization ratio measurements. As an example this technique has been applied to lidar measurements from 15 mid-latitude cirrus cloud cases taken in Palaiseau, France. Results show a majority of near-unity shape ratios as well as a strong correlation between shape ratios and temperature: The lowest temperatures lead to high shape ratios. The application of this technique to space-borne measurements would allow a large-scale classification of shape ratios in cirrus clouds, leading to better knowledge of the vertical variability of shapes, their dependence on temperature, and the formation processes of clouds. PMID:12148751

  3. 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.

  4. 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.

  5. Monitoring water levels by integrating optical and synthetic aperture radar water masks with lidar DEMs

    NASA Astrophysics Data System (ADS)

    Hopkinson, C.; Brisco, B.; Patterson, S.

    2014-12-01

    The ability to map and monitor wetland and lake open water extent and levels across the landscape allows improved estimates of watershed water balance, surface storage and flood inundation. The study presents open water classifications over the wetland dominated Sheppard Slough watershed east of Calgary in western Canada using parallel temporal imagery captured from the RapidEye and RadarSat satellites throughout 2013, a year of widespread and costly flood inundation in this region. The optical and SAR-based temporal image stacks were integrated with a high-resolution lidar DEM in order to delineate regions of inundation on the DEM surface. GIS techniques were developed to extract lidar-derived water surface elevations and track the spatio-temporal variation in pond and lake water level across the watershed. Water bodies were assigned unique identifiers so that levels could be tracked and linked to their associated watershed channel reach. The procedure of optical image classification through to merging of individual water bodies into watershed channel topology and extracting reach water levels has been automated within python scripts. The presentation will describe: i) the procedures used; ii) a comparison of the SAR and optical classification and water level extraction results; iii) a discussion of the spatio-temporal variations in water level across the Sheppard Slough watershed; and iv) a commentary on how the approach could be implemented for web-based operational monitoring and as simulation initialisation inputs for flood inundation model studies.

  6. Detection of fault structures with airborne LiDAR point-cloud data

    NASA Astrophysics Data System (ADS)

    Chen, Jie; Du, Lei

    2015-08-01

    The airborne LiDAR (Light Detection And Ranging) technology is a new type of aerial earth observation method which can be used to produce high-precision DEM (Digital Elevation Model) quickly and reflect ground surface information directly. Fault structure is one of the key forms of crustal movement, and its quantitative description is the key to the research of crustal movement. The airborne LiDAR point-cloud data is used to detect and extract fault structures automatically based on linear extension, elevation mutation and slope abnormal characteristics. Firstly, the LiDAR point-cloud data is processed to filter out buildings, vegetation and other non-surface information with the TIN (Triangulated Irregular Network) filtering method and Burman model calibration method. TIN and DEM are made from the processed data sequentially. Secondly, linear fault structures are extracted based on dual-threshold method. Finally, high-precision DOM (Digital Orthophoto Map) and other geological knowledge are used to check the accuracy of fault structure extraction. An experiment is carried out in Beiya Village of Yunnan Province, China. With LiDAR technology, results reveal that: the airborne LiDAR point-cloud data can be utilized to extract linear fault structures accurately and automatically, measure information such as height, width and slope of fault structures with high precision, and detect faults in areas with vegetation coverage effectively.

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

    E-print Network

    Bellan, Paul M.

    , Rayleigh scattering, which scales as (rd/l)4 times the grain's geomet- ric cross section, is much too smallIce iron/sodium film as cause for high noctilucent cloud radar reflectivity P. M. Bellan1 Received anomalously high radar reflectivity. It is shown that this observed high radar reflectivity can be explained

  8. STUDY OF CLOUD LIFETIME EFFECTS USING THE SGP HETEROGENEOUS DISTRIBUTED RADAR NETWORK: PRELIMINARY CONSIDERATIONS

    E-print Network

    STUDY OF CLOUD LIFETIME EFFECTS USING THE SGP HETEROGENEOUS DISTRIBUTED RADAR NETWORK: PRELIMINARY-dimensional morphology and life cycle of clouds. Detailing key cloud processes as they transit from the formation stage to precipitation onset and cloud dissipation is critical towards establishing uncertainties in climate models

  9. Feel free to contact the authors either here at the conference or at zadelhof@knmi.nl resp. donovan@knmi.nl Towards vertical cloud profile retrieval from

    E-print Network

    Zadelhoff, Gerd-Jan van

    of these clouds. Dealing with groundbased lidar-radar data. For groundbased data a method to determine R ¨ ¥§¦ , which has an exponential relationship with the radar reflectivity to lidar extinction in the Rayleigh parameters for use in NWP and GCMs. Radar Reflectivity (KNMI 35 GHz) Relative Backscatter (KNMI CT-75

  10. JUNE 2002 835F R I S C H E T A L . The Retrieval of Stratus Cloud Droplet Effective Radius with Cloud Radars

    E-print Network

    Shupe, Matthew

    . These high- sensitivity radars reveal detailed reflectivity structure of most clouds that are within several of the effective radius. One method uses both radar reflectivity and integrated liquid water through the clouds with Cloud Radars SHELBY FRISCH NOAA/Environmental Technology Laboratory, Boulder, Colorado, and Colorado

  11. Lidar System for Airborne Measurement of Clouds and Aerosols

    NASA Technical Reports Server (NTRS)

    McGill, Matthew; Scott, V. Stanley; Izquierdo, Luis Ramos; Marzouk, Joe

    2008-01-01

    A lidar system for measuring optical properties of clouds and aerosols at three wavelengths is depicted. The laser transmitter is based on a Nd:YVO4 laser crystal pumped by light coupled to the crystal via optical fibers from laser diodes that are located away from the crystal to aid in dissipating the heat generated in the diodes and their drive circuits. The output of the Nd:YVO4 crystal has a wavelength of 1064 nm, and is made to pass through frequency-doubling and frequency-tripling crystals. As a result, the net laser output is a collinear superposition of beams at wavelengths of 1064, 532, and 355 nm. The laser operates at a pulse-repetition rate of 5 kHz, emitting per-pulse energies of 50 microJ at 1064 nm, 25 microJ at 532 nm and 50 microJ at 355 nm. An important feature of this system is an integrating sphere located between the laser output and the laser beam expander lenses. The integrating sphere collects light scattered from the lenses. Three energy-monitor detectors are located at ports inside the integrating sphere. Each of these detectors is equipped with filters such that the laser output energy is measured independently for each wavelength. The laser output energy is measured on each pulse to enable the most accurate calibration possible. The 1064-nm and 532-nm photodetectors are, more specifically, single photon-counting modules (SPCMs). When used at 1064 nm, these detectors have approximately 3% quantum efficiency and low thermal noise (fewer than 200 counts per second). When used at 532 nm, the SPCMs have quantum efficiency of about 60%. The photodetector for the 355-nm channel is a photon-counting photomultiplier tube having a quantum efficiency of about 20%. The use of photon-counting detectors is made feasible by the low laser pulse energy. The main advantage of photon-counting is ease of inversion of data without need for complicated calibration schemes like those necessary for analog detectors. The disadvantage of photon-counting detectors is that they inherently have narrow dynamic ranges. However, by using photon-counting detectors along with a high-repetition rate laser, it is possible to obtain wide dynamic range through accumulation of counts over many pulses.

  12. Evidence of High Ice Supersaturation in Cirrus Clouds Using ARM Raman Lidar Measurements

    SciTech Connect

    Comstock, Jennifer M.; Ackerman, Thomas P.; Turner, David D.

    2004-06-05

    Water vapor amounts in the upper troposphere are crucial to understanding the radiative feedback of cirrus clouds on the Earth’s climate. We use a unique, year-long dataset of water vapor mixing ratio inferred from ground-based Raman lidar measurements to study the role of ice supersaturation in ice nucleation processes. We find that ice supersaturation occurs 31% of the time in over 300,000 data points. We also examine the distribution of ice supersaturation with height and find that in the uppermost portion of a cloud layer, the air is ice supersaturated 43% of the time. These measurements show that large ice supersaturation is common in cirrus clouds, which supports the theory of ice forming homogeneously. Given the continuous nature of these Raman lidar measurements, our results have important implications for studying ice nucleation processes using cloud microphysical models.

  13. ARM Raman Lidar Measurements of High Ice Supersaturation in Cirrus Clouds

    SciTech Connect

    Comstock, Jennifer M.; Ackerman, Thomas P.; Turner, David D.

    2004-09-01

    Water vapor amounts in the upper troposphere are crucial to understanding the radiative feedback of cirrus clouds on the Earth's climate. We use a unique, year-long dataset of water vapor mixing ratio inferred from ground-based Raman lidar measurements to study the role of ice supersaturation in ice nucleation processes. We find that ice supersaturation occurs 31% of the time in over 300,000 data points. We also examine the distribution of ice supersaturation with height and find that in the uppermost portion of a cloud layer, the air is ice supersaturated 43% of the time. These measurements show that large ice supersaturation is common in cirrus clouds, which supports the theory of ice forming homogeneously. Given the continuous nature of these Raman lidar measurements, our results have important implications for studying ice nucleation processes using cloud microphysical models.

  14. 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

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

    E-print Network

    Baum, Bryan A.

    Relationship 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 reflectivity for clouds consisting of nonspherical ice particles, J. Geophys. Res., 113, D20205, doi:10

  16. Second annual progress report of the Millimeter Wave Cloud Profiling Radar System (CPRS)

    SciTech Connect

    Pazmany, A.L.; Sekelsky, S.M.; McIntosh, R.E.

    1992-06-07

    The Cloud Profiling Radar System (CPRS) is a single antenna, two frequency (33 GHz and 95 GHz) polarimetric radar which is currently under the development at the University of Massachusetts (UMASS). This system will be capable of making four dimensional Doppler and polarimetric measurements of clouds. This report gives details about the status of the various subsystems under development and discusses current research activities.

  17. 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.

  18. Arctic polar stratospheric cloud measurements by means of a four wavelength depolarization lidar

    NASA Technical Reports Server (NTRS)

    Stefanutti, L.; Castagnoli, F.; Delguasta, M.; Flesia, C.; Godin, S.; Kolenda, J.; Kneipp, H.; Kyro, Esko; Matthey, R.; Morandi, M.

    1994-01-01

    A four wavelength depolarization backscattering lidar has been operated during the European Arctic Stratospheric Ozone Experiment (EASOE) in Sodankyl, in the Finnish Arctic. The lidar performed measurements during the months of December 1991, January, February and March 1992. The Finnish Meteorological Institute during the same period launched regularly three Radiosondes per day, and three Ozone sondes per week. Both Mt. Pinatubo aerosols and Polar Stratospheric Clouds were measured. The use of four wavelengths, respectively at 355 nm, 532 nm , 750 nm, and 850 nm permits an inversion of the lidar data to determine aerosol particle size. The depolarization technique permits the identification of Polar Stratospheric Clouds. Frequent correlation between Ozone minima and peaks in the Mt. Pinatubo aerosol maxima were detected. Measurements were carried out both within and outside the Polar Vortex.

  19. A Comparison of Simulated Cloud Radar Output from the Multiscale Modeling Framework Global Climate Model with CloudSat Cloud Radar Observations

    SciTech Connect

    Marchand, Roger T.; Haynes, J. M.; Mace, Gerald G.; Ackerman, Thomas P.; Stephens, Graeme L.

    2009-01-13

    Over the last few years a new type of global climate model (GCM) has emerged in which a cloud-resolving model is embedded into each grid cell of a GCM. This new approach is frequently called a multiscale modeling framework (MMF) or superparameterization. In this article we present a comparison of MMF output with radar observations from the NASA CloudSat mission, which uses a near-nadir-pointing millimeter-wavelength radar to probe the vertical structure of clouds and precipitation. We account for radar detection limits by simulating the 94 GHz radar reflectivity that CloudSat would observe from the high-resolution cloud-resolving model output produced by the MMF. Overall, the MMF does a good job of reproducing the broad pattern of tropical convergence zones, subtropical belts, and midlatitude storm tracks, as well as their changes in position with the annual solar cycle. Nonetheless, the comparison also reveals a number of model shortfalls including (1) excessive hydrometeor coverage at all altitudes over many convectively active regions, (2) a lack of low-level hydrometeors over all subtropical oceanic basins, (3) excessive low-level hydrometeor coverage (principally precipitating hydrometeors) in the midlatitude storm tracks of both hemispheres during the summer season (in each hemisphere), and (4) a thin band of low-level hydrometeors in the Southern Hemisphere of the central (and at times eastern and western) Pacific in the MMF, which is not observed by CloudSat. This band resembles a second much weaker ITCZ but is restricted to low levels.

  20. 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.

  1. Integrating Terrestrial LIDAR with Point Clouds Created from Unmanned Aerial Vehicle Imagery

    NASA Astrophysics Data System (ADS)

    Leslar, M.

    2015-08-01

    Using unmanned aerial vehicles (UAV) for the purposes of conducting high-accuracy aerial surveying has become a hot topic over the last year. One of the most promising means of conducting such a survey involves integrating a high-resolution non-metric digital camera with the UAV and using the principals of digital photogrammetry to produce high-density colorized point clouds. Through the use of stereo imagery, precise and accurate horizontal positioning information can be produced without the need for integration with any type of inertial navigation system (INS). Of course, some form of ground control is needed to achieve this result. Terrestrial LiDAR, either static or mobile, provides the solution. Points extracted from Terrestrial LiDAR can be used as control in the digital photogrammetry solution required by the UAV. In return, the UAV is an affordable solution for filling in the shadows and occlusions typically experienced by Terrestrial LiDAR. In this paper, the accuracies of points derived from a commercially available UAV solution will be examined and compared to the accuracies achievable by a commercially available LIDAR solution. It was found that the LiDAR system produced a point cloud that was twice as accurate as the point cloud produced by the UAV's photogrammetric solution. Both solutions gave results within a few centimetres of the control field. In addition the about of planar dispersion on the vertical wall surfaces in the UAV point cloud was found to be multiple times greater than that from the horizontal ground based UAV points or the LiDAR data.

  2. Analytical approximation for lidar signal from clouds under multiple light scattering

    NASA Astrophysics Data System (ADS)

    Barun, Vladimir V.

    1996-11-01

    The main purpose of this paper is to include analytically the angular backscattering dependence of phase function characteristic of rather large cloud droplets. We are doing so for two reasons, at least. First, the widely used approximation for the phase function, e.g. assuming it to be essentially constant near backscattering direction or using some its average value over the whole angular range of backscattering, can be shown to lead to overestimated or underestimated, respectively, light power recorded by a lidar. Second, the glory region bears the information on some microphysical parameters of clouds. So, the analytical description of backscattered light power would provide the simple prediction of lidar opportunities to measure, e.g., mean sizes or halfwidth of size distributions of cloud aerosols. To this purpose, the small-angle diffusion approximation of the radiative transfer theory (RTT) is used here to derive a lidar signal from intermediate optical thicknesses of clouds, where neither the asymptotic formulas of the RTT nor the single scattering approximation are working well. The analytical integration of radiative transfer with aerosol size distribution has enabled us to derive the explicit form of lidar signal power as a function of the microphysical parameters.

  3. Airborne lidar observation of mountain-wave-induced polar stratospheric clouds during EASOE

    SciTech Connect

    Godin, S.; Megie, G.; David, C.; Haner, D. ); Flesia, C.; Emery, Y. )

    1994-06-22

    This article presents the results of airborne lidar measurements of aerosol and polar stratospheric clouds (PSC) above Kiruna. Polarization measurements allow the distinction between volcanic aerosols, and PSC. They observed PSC formations near Kiruna on December 11, 1991, extending over 100's of km west and east.

  4. Calibration of the 1064 nm lidar channel using water phase and cirrus clouds.

    PubMed

    Wu, Yonghua; Gan, Chuen Meei; Cordero, Lina; Gross, Barry; Moshary, Fred; Ahmed, Sam

    2011-07-20

    Calibration is essential to derive aerosol backscatter coefficients from elastic scattering lidar. Unlike the visible UV wavelengths where calibration is based on a molecular reference, calibration of the 1064 nm lidar channel requires other approaches, which depend on various assumptions. In this paper, we analyze two independent calibration methods which use (i) low-altitude water phase clouds and (ii) high cirrus clouds. In particular, we show that to achieve optimal performance, aerosol attenuation below the cloud base and cloud multiple scattering must be accounted for. When all important processes are considered, we find that these two independent methods can provide a consistent calibration constant with relative differences less than 15%. We apply these calibration techniques to demonstrate the stability of our lidar on a monthly scale, along with a natural reduction of the lidar efficiency on an annual scale. Furthermore, our calibration procedure allows us to derive consistent aerosol backscatter coefficients and angstrom coefficient profiles (532-1064 nm) along with column extinction-to-backscatter ratios which are in good agreement with sky radiometer inversions. PMID:21772382

  5. Real-Time C-Band Radar Observations of 1992 Eruption Clouds from Crater Peak, Mount Spurr Volcano, Alaska

    E-print Network

    Rose, William I.

    . The radar system also mapped the extent of the most reflective parts of the ash cloud as it moved acrossReal-Time C-Band Radar Observations of 1992 Eruption Clouds from Crater Peak, Mount Spurr Volcano hazards in Alaska related to volcanic clouds have resulted in the use of a mobile C-band radar devoted

  6. On the vertical profile of stratus liquid water flux using a millimeter cloud radar Shelby Frisch Paquita Zuidema Chris Fairall

    E-print Network

    Zuidema, Paquita

    -normally distributed stratus cloud droplets relate to the radar reflectivity Z through where re is the effective radiusOn the vertical profile of stratus liquid water flux using a millimeter cloud radar Shelby Frisch Technology Laboratory,Boulder,CO 1.Introduction Millimeter cloud radars are routinely applied towards

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

    E-print Network

    , 2005]. In the Rayleigh approximation radar reflectivity is proportional to the sixth moment of cloud, cloud liquid water content (LWC), from radar reflectivity, certain assumptions have to be made of large drizzle drops can dominate the radar reflectivity yet contribute little to cloud LWC and optical

  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

    Evaluation 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 of the forthcoming CloudSat spaceborne radar, and of the European CloudNET and U.S. Atmospheric Radiation Measurement

  9. Lidar Observations of Tropical High-altitude Cirrus Clouds: Results form Dual Wavelength Raman Lidar Measurements During the ALBATROSS Campaign 1996

    NASA Technical Reports Server (NTRS)

    Neuber, R.; Wegener, Alfred; Schrems, O.; McDermid, I. S.

    1997-01-01

    Results from dual wavelength Raman Lidar Observations of tropical high-altitude cirrus clouds are reported. Based on 107 hours of night-time measurements cirrus cloud were present in more than 50% of the observations at latitudes between 23.5 degress S and 23.5 degrees N and altitudes between 11 and 16km.

  10. Fine-scale Horizontal Structure of Arctic Mixed-Phase Clouds M. Rambukkange1

    E-print Network

    measurement of radar Doppler velocity power spectra from the Millimeter Cloud Radar (MMCR). Shupe et al. (2004 in the radar reflectivity, it is impossible to identify much of the structure in the layer. The lidar Conference on Cloud Physics, Madison, WI, July 10-14, 2006. BNL-79883-2008-CP #12;Figure 2: Reflectivity (d

  11. Lidar-radar velocimetry using a pulse-to-pulse coherent rf-modulated Q-switched laser.

    PubMed

    Vallet, M; Barreaux, J; Romanelli, M; Pillet, G; Thévenin, J; Wang, L; Brunel, M

    2013-08-01

    An rf-modulated pulse train from a passively Q-switched Nd:YAG laser has been generated using an extra-cavity acousto-optic modulator. The rf modulation reproduces the spectral quality of the local oscillator. It leads to a high pulse-to-pulse phase coherence, i.e., phase memory, over thousands of pulses. The potentialities of this transmitter for lidar-radar are demonstrated by performing Doppler velocimetry on indoor moving targets. The experimental results are in good agreement with a model based on elementary signal processing theory. In particular, we show experimentally and theoretically that lidar-radar is a promising technique that allows discrimination between translation and rotation movements. Being independent of the laser internal dynamics, this scheme can be applied to any Q-switched laser. PMID:23913058

  12. A 35-GHz polarimetrie Doppler radar and its application for observing clouds associated with Typhoon Nuri

    NASA Astrophysics Data System (ADS)

    Zhong, Lingzhi; Liu, Lipingt; Feng, Sheng; Ge, Runsheng; Zhang, Zhe

    2011-07-01

    Millimeter-wavelength radar has proved to be an effective instrument for cloud observation and research. In this study, 8-mm-wavelength cloud radar (MMCR) with Doppler and polarization capabilities was used to investigate cloud dynamics in China for the first time. Its design, system specifications, calibration, and application in measuring clouds associated with typhoon are discussed in this article. The cloud radar measurements of radar reflectivity ( Z), Doppler velocity ( V r), velocity spectrum width ( S w) and the depolarization ratio ( L DR) at vertical incidence were used to analyze the microphysical and dynamic processes of the cloud system and precipitation associated with Typhoon Nuri, which occurred in southern China in August 2008. The results show the reflectivity observed using MMCR to be consistent with the echo height and the melting-layer location data obtained by the nearby China S-band new-generation weather radar (SA), but the Ka-band MMCR provided more detailed structural information about clouds and weak precipitation data than did the SA radar. The variation of radar reflectivity and L DR in vertical structure reveals the transformation of particle phase from ice to water. The vertical velocity and velocity spectrum width of MMCR observations indicate an updraft and strong turbulence in the stratiform cloud layer. MMCR provides a valuable new technology for meteorological research in China.

  13. CHAPTER 2: Analysis of cloud radar data 21 1000 1030 1100 1130 1200 1230 1300 1330

    E-print Network

    Hogan, Robin

    , and the corresponding noise­ equivalent reflectivity at 1 km measured by the 94 GHz radar (using the cloud­free gatesCHAPTER 2: Analysis of cloud radar data 21 0 0.5 1 1.5 2 2.5 Height (km) Z 35 -40 -30 -20 -10 dBZ) Figure 2.2: Time series of reflectivity factor through low cloud and insects at 35GHz

  14. ETO lidar studies of cirrostratus altocumulogenitus: Another role for supercooled liquid water in cirrus cloud formation

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth

    1990-01-01

    Cirrus clouds have traditionally been viewed as cold, wispy, or stratiform ice clouds, typically displaying optical phenomena such as haloes. A composition entirely of hexagonal ice crystals, of one habit or another could only have a transitory existence in cirrus, since the concentrations of ice nuclei (IN) measured by various techniques (at the surface or in the lower troposphere) indicate an enormous number of IN that should be active at cirrus cloud temperatures. In light of recent instrumental aircraft and polarization lidar studies of cirrus clouds, it is clear that highly supercooled cloud droplets can sometimes be a component of cirrus clouds. It remains to be determined if supercooled liquid water (SLW) is present abundantly enough in cirrus to play a significant role in earth's radiance balance, or is merely a curious, infrequent occurrence. To help evaluate this issue, the UH polarization lidar FIRE Extended Time Observation (ETO) of cirrus clouds are being utilized to compile, among other parameters, a climatological record of SLW clouds associated with and within cirrus.

  15. 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.

  16. 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.

  17. Automatic large-volume object region segmentation in LiDAR point clouds

    NASA Astrophysics Data System (ADS)

    Varney, Nina M.; Asari, Vijayan K.

    2014-10-01

    LiDAR is a remote sensing method which produces precise point clouds consisting of millions of geo-spatially located 3D data points. Because of the nature of LiDAR point clouds, it can often be difficult for analysts to accurately and efficiently recognize and categorize objects. The goal of this paper is automatic large-volume object region segmentation in LiDAR point clouds. This efficient segmentation technique is intended to be a pre- processing step for the eventual classification of objects within the point cloud. The data is initially segmented into local histogram bins. This local histogram bin representation allows for the efficient consolidation of the point cloud data into voxels without the loss of location information. Additionally, by binning the points, important feature information can be extracted, such as the distribution of points, the density of points and a local ground. From these local histograms, a 3D automatic seeded region growing technique is applied. This technique performs seed selection based on two criteria, similarity and Euclidean distance to nearest neighbors. The neighbors of selected seeds are then examined and assigned labels based on location and Euclidean distance to a region mean. After the initial segmentation step, region integration is performed to rejoin over-segmented regions. The large amount of points in LiDAR data can make other segmentation techniques extremely time consuming. In addition to producing accurate object segmentation results, the proposed local histogram binning process allows for efficient segmentation, covering a point cloud of over 9,000 points in 10 seconds.

  18. 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

  19. Cloud model-based simulation of spaceborne radar observations

    NASA Technical Reports Server (NTRS)

    Yeh, H.-Y. M.; Prasad, N.; Meneghini, R.; Tao, W.-K.; Jones, J. A.; Adler, R. F.

    1995-01-01

    Simulations of observations from potential spaceborne radars are made based on storm structure generated from the three-dimensional (3D) Goddard cumulus ensemble model simulation of an intense overland convective system. Five frequencies of 3, 10, 14, 35, and 95 GHz are discussed, but the Tropical Rainfall Measuring Mission precipitation radar sensor frequency (14 GHz) is the focus of this study. Radar reflectives and their attenuation in various atmospheric conditions are studied in this simulation. With the attenuation from cloud and precipitation in the estimation of reflectivity factor (dBZ), the reflectivities in the lower atmosphere in the convective cores are significantly reduced. With spatial resolution of 4 km X 4 km, attenuation at 14 GHz may cause as large as a 20-dBZ difference between the simulated measurements of the peak, Z(sub mp) and near-surface reflectivity, Z(sub ms) in the most intense convective region. The Z(sub mp) occurs at various altitudes depending on the hydrometeor concentrations and their vertical distribution. Despite the significant attenuation in the intense cores, the presence of the rain maximum is easily detected by using information of Z(sub mp). In the stratiform region, the attenuation is quite limited (usually less than 5 dBZ), and the reduction of reflectivity is mostly related to the actual vertical structure of cloud distribution. Since Z(sub ms) suffers severe attenuation and tends to underestimate surface rainfall intensity in convective regions. Z(sub mp) can be more representative for rainfall retrieval in the lower atmosphere in these regions. In the stratiform region where attenuation is negligible, however, Z(sub mp) tends to overestimate surface rainfall and Z(sub ms) is more appropriate for rainfall retrieval. A hybrid technique using a weight between the two rain intensities is tested and found potentially usefull for future applications. The estimated surface rain-rate map based on this hybrid approach captures many of the details of the cloud model rain field but still slightly underestimates the rain-rate maximum.

  20. Measurements of Backscatter Phase Function and Depolarization in Cirrus Clouds made with the University of Wisconsin High Spectral Resolution Lidar.

    E-print Network

    Eloranta, Edwin W.

    Measurements of Backscatter Phase Function and Depolarization in Cirrus Clouds made-262-5974, Email: eloranta@lidar.ssec.wisc.edu January 2, 2001 1 Introduction Cirrus clouds play an important role of backscat- ter phase function and depolarization in cirrus clouds. 2 Observations During 1994, the HSRL

  1. 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.

  2. Performance of mean-frequency estimators for Doppler radar and lidar

    NASA Technical Reports Server (NTRS)

    Frehlich, R. G.; Yadlowsky, M. J.

    1994-01-01

    The performance of mean-frequency estimators for Doppler radar and lidar measurements of winds is presented in terms of two basic parameters: Phi, the ratio of the average signal energy per estimate to the spectral noise level; and Omega, which is proportional to the number of independent samples per estimate. For fixed Phi and Omega, the Cramer-Rao bound (CRB) (theoretical best performance) for unbiased estimators of mean frequency (normalized by the spectral width of the signal), signal power, and spectral width are essentially independent of the number of data samples M. For large Phi, the estimators of mean frequency are unbiased and the performance is independent of M. The spectral domain estimators and covariance based estimators are bounded by the approximate period of M. The spectral domain estimators and covariance based estimators are bounded by the approximate periodogram CRB. The standard deviation of the maximum-likelihood estimator approaches the exact CRB, which can be more than a factor of 2 better than the performance of the spectral domain estimators or covariance-based estimators for typical Omega. For small Phi, the estimators are biased due to the effects of the uncorrelated noise (white noise), which results in uniformly distributed 'bad' estimates. The fraction of bad estimates is a function of Phi and M with weak dependence on the parameter Omega. Simple empirical models describe the standard deviation of the good estimates and the fraction of bad estimates. For Doppler lidar and for large Phi, better performance is obtained by using many low-energy pulses instead of one pulse with the same total energy. For small Phi, the converse is true.

  3. 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.

  4. 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.

  5. 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.

  6. Effects of Cloud on Goddard Lidar Observatory for Wind (GLOW) Performance and Analysis of Associated Errors

    NASA Astrophysics Data System (ADS)

    Bacha, Tulu

    The Goddard Lidar Observatory for Wind (GLOW), a mobile direct detection Doppler LIDAR based on molecular backscattering for measurement of wind in the troposphere and lower stratosphere region of atmosphere is operated and its errors characterized. It was operated at Howard University Beltsville Center for Climate Observation System (BCCOS) side by side with other operating instruments: the NASA/Langely Research Center Validation Lidar (VALIDAR), Leosphere WLS70, and other standard wind sensing instruments. The performance of Goddard Lidar Observatory for Wind (GLOW) is presented for various optical thicknesses of cloud conditions. It was also compared to VALIDAR under various conditions. These conditions include clear and cloudy sky regions. The performance degradation due to the presence of cirrus clouds is quantified by comparing the wind speed error to cloud thickness. The cloud thickness is quantified in terms of aerosol backscatter ratio (ASR) and cloud optical depth (COD). ASR and COD are determined from Howard University Raman Lidar (HURL) operating at the same station as GLOW. The wind speed error of GLOW was correlated with COD and aerosol backscatter ratio (ASR) which are determined from HURL data. The correlation related in a weak linear relationship. Finally, the wind speed measurements of GLOW were corrected using the quantitative relation from the correlation relations. Using ASR reduced the GLOW wind error from 19% to 8% in a thin cirrus cloud and from 58% to 28% in a relatively thick cloud. After correcting for cloud induced error, the remaining error is due to shot noise and atmospheric variability. Shot-noise error is the statistical random error of backscattered photons detected by photon multiplier tube (PMT) can only be minimized by averaging large number of data recorded. The atmospheric backscatter measured by GLOW along its line-of-sight direction is also used to analyze error due to atmospheric variability within the volume of measurement. GLOW scans in five different directions (vertical and at elevation angles of 45° in north, south, east, and west) to generate wind profiles. The non-uniformity of the atmosphere in all scanning directions is a factor contributing to the measurement error of GLOW. The atmospheric variability in the scanning region leads to difference in the intensity of backscattered signals for scanning directions. Taking the ratio of the north (east) to south (west) and comparing the statistical differences lead to a weak linear relation between atmospheric variability and line-of-sights wind speed differences. This relation was used to make correction which reduced by about 50%.

  7. 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.

  8. 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.

  9. Polar stratospheric clouds observed by lidar at McMurdo Station during the 1993 winter

    SciTech Connect

    Adriani, A.; Gobbi, G.P.; Donfrancesco, G.D.

    1994-12-31

    Since 1990, a lidar system has been operating at McMurdo Station (78{degrees}S 167{degrees}E) during the local spring. In 1993, it performed measurements between 1 March and 10 October. The lidar can monitor the presence of clouds by measuring the light backscattered from the atmosphere. After system calibration, the received signal is compared with the one expected from an atmosphere not containing particles. On such a basis, a parameter called backscattering ratio, R, is calculated. When particles are not present R is 1. Any value larger than 1 is related to the presence of particles. Lidar can be used to monitor clouds in the lower stratosphere (polar stratospheric clouds - PSCs- or volcanic clouds). PSCs have an important role in the heterogeneous chemistry of the polar stratosphere, and their presence is strictly linked with the `ozone hole`. During the 1993 winter and spring, the antarctic stratosphere still presented a measurable amount of volcanic aerosol from the Mount Pinatubo eruption. The volcanic aerosols facilitated the formation of PSCs observed during the 1993 winter because they need condensation nuclei to form. 3 refs., 2 figs.

  10. AIRBORNE RADAR OBSERVATIONS OF NON-DRIZZLING MARINE STRATOCUMULUS Department of Atmospheric Science, University of Wyoming.

    E-print Network

    Vali, Gabor

    3, DMS) instrumentation, the SABL lidar and the Wyoming Cloud Radar (WCR). This paper focuses, some new material is presented. 3. REFLECTIVITY PATTERNS AND ECHO TOP VARIATIONS Radar data from. The dominant pattern in radar reflectivity is an upward gradient, from values near -30 dBZ at the base

  11. 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.

  12. Retrieval of Polar Stratospheric Cloud Microphysical Properties from Lidar Measurements: Dependence on Particle Shape Assumptions

    NASA Technical Reports Server (NTRS)

    Reichardt, J.; Reichardt, S.; Yang, P.; McGee, T. J.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    A retrieval algorithm has been developed for the microphysical analysis of polar stratospheric cloud (PSC) optical data obtained using lidar instrumentation. The parameterization scheme of the PSC microphysical properties allows for coexistence of up to three different particle types with size-dependent shapes. The finite difference time domain (FDTD) method has been used to calculate optical properties of particles with maximum dimensions equal to or less than 2 mu m and with shapes that can be considered more representative of PSCs on the scale of individual crystals than the commonly assumed spheroids. Specifically. these are irregular and hexagonal crystals. Selection of the optical parameters that are input to the inversion algorithm is based on a potential data set such as that gathered by two of the lidars on board the NASA DC-8 during the Stratospheric Aerosol and Gas Experiment 0 p (SAGE) Ozone Loss Validation experiment (SOLVE) campaign in winter 1999/2000: the Airborne Raman Ozone and Temperature Lidar (AROTEL) and the NASA Langley Differential Absorption Lidar (DIAL). The 0 microphysical retrieval algorithm has been applied to study how particle shape assumptions affect the inversion of lidar data measured in leewave PSCs. The model simulations show that under the assumption of spheroidal particle shapes, PSC surface and volume density are systematically smaller than the FDTD-based values by, respectively, approximately 10-30% and approximately 5-23%.

  13. 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.

  14. Lidar Investigation of Tropical Nocturnal Boundary Layer Aerosols and Cloud Macrophysics

    SciTech Connect

    Manoj, M. G.; Devara, PC S.; Taraphdar, Sourav

    2013-10-01

    Observational evidence of two-way association between nocturnal boundary layer aerosols and cloud macrophysical properties under different meteorological conditions is reported in this paper. The study has been conducted during 2008-09 employing a high space-time resolution polarimetric micro-pulse lidar over a tropical urban station in India. Firstly, the study highlights the crucial role of boundary layer aerosols and background meteorology on the formation and structure of low-level stratiform clouds in the backdrop of different atmospheric stability conditions. Turbulent mixing induced by the wind shear at the station, which is associated with a complex terrain, is found to play a pivotal role in the formation and structural evolution of nocturnal boundary layer clouds. Secondly, it is shown that the trapping of energy in the form of outgoing terrestrial radiation by the overlying low-level clouds can enhance the aerosol mixing height associated with the nocturnal boundary layer. To substantiate this, the long-wave heating associated with cloud capping has been quantitatively estimated in an indirect way by employing an Advanced Research Weather Research and Forecasting (WRF-ARW) model version 2.2 developed by National Center for Atmospheric Research (NCAR), Colorado, USA, and supplementary data sets; and differentiated against other heating mechanisms. The present investigation as well establishes the potential of lidar remote-sensing technique in exploring some of the intriguing aspects of the cloud-environment relationship.

  15. Arctic Mixed-Phase Cloud Properties from AERI Lidar Observations: Algorithm and Results from SHEBA

    SciTech Connect

    Turner, David D.

    2005-04-01

    A new approach to retrieve microphysical properties from mixed-phase Arctic clouds is presented. This mixed-phase cloud property retrieval algorithm (MIXCRA) retrieves cloud optical depth, ice fraction, and the effective radius of the water and ice particles from ground-based, high-resolution infrared radiance and lidar cloud boundary observations. The theoretical basis for this technique is that the absorption coefficient of ice is greater than that of liquid water from 10 to 13 ?m, whereas liquid water is more absorbing than ice from 16 to 25 ?m. MIXCRA retrievals are only valid for optically thin (?visible < 6) single-layer clouds when the precipitable water vapor is less than 1 cm. MIXCRA was applied to the Atmospheric Emitted Radiance Interferometer (AERI) data that were collected during the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment from November 1997 to May 1998, where 63% of all of the cloudy scenes above the SHEBA site met this specification. The retrieval determined that approximately 48% of these clouds were mixed phase and that a significant number of clouds (during all 7 months) contained liquid water, even for cloud temperatures as low as 240 K. The retrieved distributions of effective radii for water and ice particles in single-phase clouds are shown to be different than the effective radii in mixed-phase clouds.

  16. Comparison of ECMWF Cloud Cover with Radar Derived Values Robin J. Hogan # , Christian Jakob + and Anthony J. Illingworth

    E-print Network

    Hogan, Robin

    Comparison of ECMWF Cloud Cover with Radar Derived Values Robin J. Hogan # , Christian Jakob to whether a 35 GHz radar observed any cloud in it during the model timestep, and this was compared is quite straightforward; daily time­height sections of radar reflectivity are divided into boxes centred

  17. Determination of cloud effective particle size from the multiple-scattering effect on lidar integration-method temperature measurements.

    PubMed

    Reichardt, Jens; Reichardt, Susanne

    2006-04-20

    A method is presented that permits the determination of the cloud effective particle size from Raman- or Rayleigh-integration temperature measurements that exploits the dependence of the multiple-scattering contributions to the lidar signals from heights above the cloud on the particle size of the cloud. Independent temperature information is needed for the determination of size. By use of Raman-integration temperatures, the technique is applied to cirrus measurements. The magnitude of the multiple-scattering effect and the above-cloud lidar signal strength limit the method's range of applicability to cirrus optical depths from 0.1 to 0.5. Our work implies that records of stratosphere temperature obtained with lidar may be affected by multiple scattering in clouds up to heights of 30 km and beyond. PMID:16633433

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

    SciTech Connect

    Stadler, John H.; Hostetler, Chris A.; Williams-Byrd, Julie; Hovis, Floyd; Bradford, Charles M.; Schwiesow, Ron

    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.

  19. 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.

  20. 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...

  1. An Unattended Cloud-Profiling Radar for Use in Climate Research.

    NASA Astrophysics Data System (ADS)

    Moran, Kenneth P.; Martner, Brooks E.; Post, M. J.; Kropfli, Robert A.; Welsh, David C.; Widener, Kevin B.

    1998-03-01

    A new millimeter-wave cloud radar (MMCR) has been designed to provide detailed, long-term observations of nonprecipitating and weakly precipitating clouds at Cloud and Radiation Testbed (CART) sites of the Department of Energy's Atmospheric Radiation Measurement (ARM) program. Scientific requirements included excellent sensitivity and vertical resolution to detect weak and thin multiple layers of ice and liquid water clouds over the sites and long-term, unattended operations in remote locales. In response to these requirements, the innovative radar design features a vertically pointing, single-polarization, Doppler system operating at 35 GHz (Ka band). It uses a low-peak-power transmitter for long-term reliability and high-gain antenna and pulse-compressed waveforms to maximize sensitivity and resolution. The radar uses the same kind of signal processor as that used in commercial wind profilers. The first MMCR began operations at the CART in northern Oklahoma in late 1996 and has operated continuously there for thousands of hours. It routinely provides remarkably detailed images of the ever-changing cloud structure and kinematics over this densely instrumented site. Examples of the data are presented. The radar measurements will greatly improve quantitative documentation of cloud conditions over the CART sites and will bolster ARM research to understand how clouds impact climate through their effects on radiative transfer. Millimeter-wave radars such as the MMCR also have potential applications in the fields of aviation weather, weather modification, and basic cloud physics research.

  2. A new cloud and aerosol layer detection method based on micropulse lidar measurements

    E-print Network

    Zeng, Ning

    cycle. They can change the Earth's energy balance by reflecting solar radiation and by trapping longwave to land. The representation of clouds remains one of the largest uncertainties in current climate characterize the extent and properties of aerosols or other particle-laden regions. Compared to weather radars

  3. Macrophysical Properties of Tropical Cirrus Clouds from the CALIPSO Satellite and from Ground-based Micropulse and Raman Lidars

    SciTech Connect

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

    2013-08-27

    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 In- frared 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 cy- cle is significantly different than zero only below about 11 km; where it is the opposite sign (i.e. more clouds during the daytime). For cirrus geomet- rical thickness, the MPL and CALIPSO observations agree well and both datasets have signficantly 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 vast im- provement the RL provides (compared to the MPL) in the ARM program's ability to observe tropical cirrus clouds as well as a valuable ground-based lidar dataset for the validation of CALIPSO observations and to help im- prove our understanding of tropical cirrus clouds.

  4. Fingerprints of a riming event on cloud radar Doppler spectra: observations and modeling

    NASA Astrophysics Data System (ADS)

    Kalesse, H.; Szyrmer, W.; Kneifel, S.; Kollias, P.; Luke, E.

    2015-10-01

    Radar Doppler spectra measurements are exploited to study a riming event when precipitating ice from a seeder cloud sediments through a supercooled liquid water (SLW) layer. The observations were collected during the deployment of the Atmospheric Radiation Measurement Program's (ARM) mobile facility AMF2 at Hyytiälä, Finland during the BAECC (Biogenic Aerosols - Effects on Clouds and Climate Snowfall Experiment) field campaign. The presented analysis of the height evolution of the radar Doppler spectra is a state-of-the-art retrieval with profiling cloud radars in SLW layers beyond the traditional use of spectral moments. Dynamical effects are taken into account by following the particle population evolution along slanted tracks that are caused by horizontal advection of the cloud under wind shear conditions. In the SLW layer, the identified liquid peak is used as an air motion tracer to correct the Doppler spectra for vertical air motion and the ice peak is used to study the radar profiles of rimed particles. A 1-D steady-state bin microphysical model is constrained using the SLW and air motion profiles and cloud top radar observations. The observed radar moment profiles of the rimed snow can be simulated reasonably well by the model, but not without making several assumptions about the ice particle concentration and the relative role of deposition and aggregation. This suggests that in-situ observations of key ice properties are needed to complement the profiling radar observations before process-oriented studies can effectively evaluate ice microphysical parameterizations.

  5. 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.

  6. Retrieval of Atmospheric CO2 Concentration above Clouds and Cloud Top Pressure from Airborne Lidar Measurements during ASCENDS Science Campaigns

    NASA Astrophysics Data System (ADS)

    Mao, J.; Ramanathan, A. K.; Rodriguez, M.; Allan, G. R.; Hasselbrack, W. E.; Abshire, J. B.; Riris, H.; Kawa, S. R.

    2014-12-01

    NASA Goddard is developing an integrated-path, differential absorption (IPDA) lidar approach to measure atmospheric CO2 concentrations from space as a candidate for NASA's ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons) mission. The approach uses pulsed lasers to measure both CO2 and O2 absorption simultaneously in the vertical path to the surface at a number of wavelengths across a CO2 line at 1572.335 nm and an O2 line doublet near 764.7 nm. Measurements of time-resolved laser backscatter profiles from the atmosphere allow the technique to estimate column CO2 and O2 number density and range to cloud tops in addition to those to the ground. This allows retrievals of CO2 column above clouds and cloud top pressure, and all-sky measurement capability from space. This additional information can be used to evaluate atmospheric transport processes and other remote sensing carbon data in the free atmosphere, improve carbon data assimilation in models and help global and regional carbon flux estimates. We show some preliminary results of this capability using airborne lidar measurements from the summers of 2011 and 2014 ASCENDS science campaigns. These show simultaneous retrievals of CO2 and O2 column densities for laser returns from low-level marine stratus clouds in the west coast of California. This demonstrates the supplemental capability of the future space carbon mission to measure CO2 above clouds, which is valuable particularly for the areas with persistent cloud covers, e.g, tropical ITCZ, west coasts of continents with marine layered clouds and southern ocean with highest occurrence of low-level clouds, where underneath carbon cycles are active but passive remote sensing techniques using the reflected short wave sunlight are unable to measure accurately due to cloud scattering effect. We exercise cloud top pressure retrieval from O2 absorption measurements during the flights over the low-level marine stratus cloud decks, which is one of fundamental parameters related to cloud radiative forcing and their feedback to global warming. These retrievals are evaluated with those from in-situ measured during the campaigns.

  7. 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.

  8. Fully Automated Detection of Cloud and Aerosol Layers in the CALIPSO Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Vaughan, Mark A.; Powell, Kathleen A.; Kuehn, Ralph E.; Young, Stuart A.; Winker, David M.; Hostetler, Chris A.; Hunt, William H.; Liu, Zhaoyan; McGill, Matthew J.; Getzewich, Brian J.

    2009-01-01

    Accurate knowledge of the vertical and horizontal extent of clouds and aerosols in the earth s atmosphere is critical in assessing the planet s radiation budget and for advancing human understanding of climate change issues. To retrieve this fundamental information from the elastic backscatter lidar data acquired during the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission, a selective, iterated boundary location (SIBYL) algorithm has been developed and deployed. SIBYL accomplishes its goals by integrating an adaptive context-sensitive profile scanner into an iterated multiresolution spatial averaging scheme. This paper provides an in-depth overview of the architecture and performance of the SIBYL algorithm. It begins with a brief review of the theory of target detection in noise-contaminated signals, and an enumeration of the practical constraints levied on the retrieval scheme by the design of the lidar hardware, the geometry of a space-based remote sensing platform, and the spatial variability of the measurement targets. Detailed descriptions are then provided for both the adaptive threshold algorithm used to detect features of interest within individual lidar profiles and the fully automated multiresolution averaging engine within which this profile scanner functions. The resulting fusion of profile scanner and averaging engine is specifically designed to optimize the trade-offs between the widely varying signal-to-noise ratio of the measurements and the disparate spatial resolutions of the detection targets. Throughout the paper, specific algorithm performance details are illustrated using examples drawn from the existing CALIPSO dataset. Overall performance is established by comparisons to existing layer height distributions obtained by other airborne and space-based lidars.

  9. 9.7 Studies of Arctic Mixed-Phase Clouds from SHEBA/FIRE/ACE: May 1-10 Case Study , J. Intrieri

    E-print Network

    Zuidema, Paquita

    . 1: a) Radar reflectivity in dBZ, with black dots in- dicating the lidar-determined water cloud bases, CO 80305 e- mail:paquita.zuidema@noaa.gov May 1-May 7, radar reflectivity 1 2 3 4 5 6 7 8 day (gmt) 0. Primary Application Reference 35 GHz cloud radar 45 m retrieval of ice component Moran et al. (1998) 23

  10. Performance assessment of a triple-frequency spaceborne cloud-precipitation radar concept using a global cloud-resolving model

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    Multi-frequency radars offer enhanced detection of clouds and precipitation compared to single-frequency systems, and are able to make more accurate retrievals when several frequencies are available simultaneously. An evaluation of a spaceborne three-frequency Ku-/Ka-/W-band radar system is presented in this study, based on modeling radar reflectivities from the results of a global cloud-resolving model with a 875 m grid spacing. To produce the reflectivities, a scattering model has been developed for each of the hydrometeor types produced by the model, as well as for melting snow. The effects of attenuation and multiple scattering on the radar signal are modeled using a radiative transfer model, while nonuniform beam filling is reproduced with spatial averaging. The combined effects of these are then quantified both globally and in six localized case studies. Two different orbital scenarios using the same radar are compared. Overall, based on the results, it is expected that the proposed radar would detect a high-quality signal in most clouds and precipitation. The main exceptions are the thinnest clouds that are below the detection threshold of the W-band channel, and at the opposite end of the scale, heavy convective rainfall where a combination of attenuation, multiple scattering and nonuniform beam filling commonly cause significant deterioration of the signal; thus, while the latter can be generally detected, the quality of the retrievals is likely to be degraded.

  11. Performance assessment of a triple-frequency spaceborne cloud-precipitation radar concept using a global cloud-resolving model

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Multi-frequency radars offer enhanced detection of clouds and precipitation compared to single-frequency systems, and are able to make more accurate retrievals when several frequencies are available simultaneously. An evaluation of a spaceborne three-frequency Ku/Ka/W-band radar system is presented in this study, based on modeling radar reflectivities from the results of a global cloud-resolving model with a 875 m grid spacing. To produce the reflectivities, a scattering model has been developed for each of the hydrometeor types produced by the model, as well as for melting snow. The effects of attenuation and multiple scattering on the radar signal are modeled using a radiative transfer model, while nonuniform beam filling is reproduced with spatial averaging. The combined effects of these are then quantified both globally and in five localized case studies. Two different orbital scenarios using the same radar are compared. Overall, based on the results, it is expected that the proposed radar would detect a high-quality signal in most clouds and precipitation. The main exceptions are the thinnest clouds that are below the detection threshold of the W-band channel, and at the opposite end of the scale, heavy convective rainfall where a combination of attenuation, multiple scattering and nonuniform beam filling commonly cause significant deterioration of the signal; thus, while the latter can be generally detected, the quality of the retrievals is likely to be degraded.

  12. 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.

  13. On the combined use of satellite multispectral and radar polarimetric measurements to infer cloud microphysics

    NASA Astrophysics Data System (ADS)

    Celano, M.; Porcù, F.; Alberoni, P. P.; Prodi, F.

    2008-10-01

    The extensive availability of multispectral satellite observations and polarimetric ground radar measurements enhances the remote sensing capabilities in studying structure and dynamics of cloud systems at all relevant scales. We present here a combined approach to perform a detailed cloud vertical structure analysis, by means of MODIS VIS-NIR products and C-band polarimetric radar data. Satellite products include estimates of cloud optical thickness, cloud particles effective radius and cloud top phase, to be matched with the polarimetric hydrometeor 3D classification as obtained by a fuzzy logic algorithm. The problem of matching of the two datasets is discussed and the procedure is applied to three case studies that occurred in Northern Italy. Results are presented in terms of vertical hydrometeor profile and satellite derived microphysical cloud properties, showing the capability of the combined approach in the 3D rendering of cloud structures, with envisaged applications for precipitation studies and data assimilation in meteorological models.

  14. 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.

  15. [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

  16. Investigation of multiple scattering processes resolved in clouds using a flash lidar

    NASA Astrophysics Data System (ADS)

    Weimer, C. S.; Hu, Y.; Saiki, E.; Delker, T.; Applegate, J.; Ramond, T.

    2010-12-01

    The Topographic Mapping Flash Lidar (TMFL) instrument developed at Ball Aerospace has been used to investigate the phenomenon of multiple scattering of the lidar signal inside a medium such as a water cloud. This behavior has been observed during a recent flight of the instrument aboard a Twin Otter aircraft flying over a steam plume. TMFL illuminates a line that extends across-track, and signal was observed off-axis over multiple pixels of the flash focal plane array. Thus the multiple scattering intensities are spatially sub-sampled, in addition to obtaining range resolutions. Variation of scattering strengths with off-axis distance is compared to those predicted by atmospheric models. It has been hypothesized that multiple scattering effects could account for a major source of error for space-based lidars such as CALIPSO, which samples atmospheric backscatter over a column. However, the physics behind multiple scattering is not well -understood and thus the effect cannot be sufficiently characterized to improve the error bars. The spatial resolution TMFL therefore provides a tool to quantify the effects of the processes of multiple scattering in lidar instrument signal. In addition, TMFL has recorded returns from the surface of a lake, and the strength of water surface returns can be correlated to the roughness of the water. That in turn can be tied to aerosol concentrations near the water surface.

  17. 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.

  18. Polar stratospheric clouds at the South Pole in 1990: Lidar observations and analysis

    SciTech Connect

    Collins, R.L.; Bowman, K.P.; Gardner, C.S. )

    1993-01-20

    In December 1989 a Rayleigh/sodium lidar (589 nm) was installed at the Amundsen-Scott South Pole station, and was used to measure stratospheric aerosol, temperature, and mesospheric sodium profiles through October 1990. Observations of stratospheric aerosol and temperature are presented in this paper. Polar stratospheric clouds (PSCs) were first observed in late May at about 20 km. As the lower stratosphere cooled further, PSCs were observed throughout the 12-27 km altitude region, and remained there from mid-June until late August. Observations in early September detected no PSCs above 21 km. An isolated cloud was observed in mid-October. Throughout the winter the clouds had small backscatter ratios (< 10). Observations made at two wavelengths in July show that the clouds are predominately composed of nitric acid trihydrate with associated Angstrom coefficients between 0.2 and 3.7. Comparison of the lidar data and balloon borne frost point measurements in late August indicate that the nitric acid mixing ratio was less than 1.5 ppbv. Observations over periods of several hours show downward motions in the cloud layers similar to the phase progressions of upwardly-propagating gravity waves. The vertical phase velocities of these features ([approx] 4 cm/s) are significantly faster than the expected settling velocities of the cloud particles. Both the backscatter ratio profiles and the radiosonde horizontal wind profiles show 1-4 km vertical structures. This suggests that the kilometer-scale vertical structure of the PSCs is maintained by low frequency gravity waves propagating through the cloud layers. 24 refs., 9 figs., 4 tabs.

  19. Automatic Detection of Building Points from LIDAR and Dense Image Matching Point Clouds

    NASA Astrophysics Data System (ADS)

    Maltezos, E.; Ioannidis, C.

    2015-08-01

    This study aims to detect automatically building points: (a) from LIDAR point cloud using simple techniques of filtering that enhance the geometric properties of each point, and (b) from a point cloud which is extracted applying dense image matching at high resolution colour-infrared (CIR) digital aerial imagery using the stereo method semi-global matching (SGM). At first step, the removal of the vegetation is carried out. At the LIDAR point cloud, two different methods are implemented and evaluated using initially the normals and the roughness values afterwards: (1) the proposed scan line smooth filtering and a thresholding process, and (2) a bilateral filtering and a thresholding process. For the case of the CIR point cloud, a variation of the normalized differential vegetation index (NDVI) is computed for the same purpose. Afterwards, the bare-earth is extracted using a morphological operator and removed from the rest scene so as to maintain the buildings points. The results of the extracted buildings applying each approach at an urban area in northern Greece are evaluated using an existing orthoimage as reference; also, the results are compared with the corresponding classified buildings extracted from two commercial software. Finally, in order to verify the utility and functionality of the extracted buildings points that achieved the best accuracy, the 3D models in terms of Level of Detail 1 (LoD 1) and a 3D building change detection process are indicatively performed on a sub-region of the overall scene.

  20. 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, O C.; Tobin, D.; Feltz, W.; Jedlovec, G. J.; Gutman, S. I.; Schwemmer, G. K.; Cadirola, M.; Melfi, S. H.; Schmidlin, F.

    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 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/lR 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.

  1. An investigation of mountain waves with lidar observations.

    NASA Technical Reports Server (NTRS)

    Viezee, W.; Collis, R. T. H.; Lawrence, J. D., Jr.

    1973-01-01

    In March and April of 1969 and 1970, lidar (laser radar) observations of the atmospheric structure were made in the lee of the Sierra Nevada during the occurrence of mountain lee waves. Rawinsonde ascents and, on some occasions, research aircraft flights supported the lidar observations. The objective of the program was to explore the applicability of the lidar technique to atmospheric turbulence detection. The observations demonstrate that a ground-based lidar can delineate significant features of the atmospheric flow pattern by monitoring echoes from concentrations of particulate matter that characterize the airflow structure in the form of either visible or subvisible clouds and dust.

  2. 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.

  3. A STUDY OF CLOUD AND DRIZZLE PROPERTIES IN THE AZORES USING DOPPLER RADAR SPECTRA

    E-print Network

    A STUDY OF CLOUD AND DRIZZLE PROPERTIES IN THE AZORES USING DOPPLER RADAR SPECTRA Edward Luke 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

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

    E-print Network

    Hogan, Robin

    Altimeter System (GLAS) lidar on the ICESat satellite. In order to account for lidar attenuation represented in general circu- lation models (Arking, 1991), which is one of the ma- jor factors limiting

  5. Performance of the Lidar Design and Data Algorithms for the GLAS Global Cloud and Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D.; Palm, Stephen P.; Hlavka, Dennis L.; Hart, William D.

    2007-01-01

    The Geoscience Laser Altimeter System (GLAS) launched in early 2003 is the first polar orbiting satellite lidar. The instrument design includes high performance observations of the distribution and optical scattering cross sections of atmospheric clouds and aerosol. The backscatter lidar operates at two wavelengths, 532 and 1064 nm. For the atmospheric cloud and aerosol measurements, the 532 nm channel was designed for ultra high efficiency with solid state photon counting detectors and etalon filtering. Data processing algorithms were developed to calibrate and normalize the signals and produce global scale data products of the height distribution of cloud and aerosol layers and their optical depths and particulate scattering cross sections up to the limit of optical attenuation. The paper will concentrate on the effectiveness and limitations of the lidar channel design and data product algorithms. Both atmospheric receiver channels meet and exceed their design goals. Geiger Mode Avalanche Photodiode modules are used for the 532 nm signal. The operational experience is that some signal artifacts and non-linearity require correction in data processing. As with all photon counting detectors, a pulse-pile-up calibration is an important aspect of the measurement. Additional signal corrections were found to be necessary relating to correction of a saturation signal-run-on effect and also for daytime data, a small range dependent variation in the responsivity. It was possible to correct for these signal errors in data processing and achieve the requirement to accurately profile aerosol and cloud cross section down to 10-7 llm-sr. The analysis procedure employs a precise calibration against molecular scattering in the mid-stratosphere. The 1064 nm channel detection employs a high-speed analog APD for surface and atmospheric measurements where the detection sensitivity is limited by detector noise and is over an order of magnitude less than at 532 nm. A unique feature of the GLAS is a full acquisition of the surface return pulse, which has important application to the atmospheric transmission retrieval.

  6. 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

  7. 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

    on radar reflectivity measurements made by the vertically-pointing, 35-GHz, millimeter cloud radar (MMCR by a cloud radar and two different radiometers that are useful for retrieving various cloud microphysical the distribution of liquid throughout the cloud, which is done according to the reflectivity profile

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

    SciTech Connect

    Febvre, G.

    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. Measurements of cirrus cloud backscatter color ratio with a two-wavelength lidar.

    PubMed

    Tao, Zongming; McCormick, M Patrick; Wu, Dong; Liu, Zhaoyan; Vaughan, Mark A

    2008-04-01

    We present observations of cirrus clouds from June 2006 to July 2007 performed by using a two-wavelength lidar located at Hampton University. For this time period, cirrus clouds were observed mostly in 7-13.5 km altitudes. Data analyses have been performed focusing on a color-ratio retrieval. In total, 86,369 samples from 1,689 profiles (1 min average and 15 m range resolution) containing cirrus clouds with attenuated backscatter ratio (ratio of attenuated total backscatter to the molecular backscatter) larger than 10 have been selected. The cirrus color ratio distribution shows a peak value at about 0.88 and a full width at half-maximum of 0.12. PMID:18382576

  10. CO2 lidar technique for observing characteristic drop size in water clouds

    NASA Astrophysics Data System (ADS)

    Eberhard, Wynn L.

    1993-01-01

    An analytical evaluation demonstrates that a calibrated 10.6 micron wavelength lidar can measure the mean radius and the effective radius of the drop size distribution in a water cloud. The radius parameter observed is a weighted average over the penetration depth of the pulse, with weighting factor decreasing with optical depth. In this method, the lidar signal is integrated and boundary conditions on optical depth are applied to obtain the average extinction-to-backscatter ratio. The radius parameter is determined by comparing the measured ratio with that found from Mie scatter calculations for a variety of typical drop size distributions. This extinction-to-backscatter method was originally proposed in the literature for measuring mode radius, but at 10.6-micron wavelength the current results show better accuracy for mean or effective radius. Other CO2 laser wavelengths can be used, but slightly more stable results are expected at longer wavelengths.

  11. 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.

  12. Lidar observations of tropical high-altitude cirrus clouds: results from dual-wavelength Raman lidar measurements during the ALBATROSS campaign 1996

    NASA Astrophysics Data System (ADS)

    Beyerle, Georg; Schaefer, H. J.; Schrems, Otto; Neuber, R.; Rairoux, P.; McDermid, I. S.

    1997-05-01

    Results from dual wavelength Raman lidar observations of tropical high-altitude cirrus clouds are reported. Based on 107 hours of night-time measurements cirrus clouds were present in more than 50% of the observations at latitudes between 23.5 degrees south and 23.5 degrees north and altitudes between 11 and 16 km. Volume depolarization is found to be a sensitive parameter for the detection of subvisible cloud layers. Using Mie scattering calculations estimates of the ice water content are derived.

  13. 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.

  14. Arctic Mixed-Phase Cloud Properties Derived from Surface-Based Sensors at SHEBA MATTHEW D. SHUPE AND SERGEY Y. MATROSOV

    E-print Network

    Shupe, Matthew

    from these clouds using radar reflectivity measurements. The annual average ice particle mean diameter Arctic mixed-phase cloud macro- and microphysical properties are derived from a year of radar, lidarArctic Mixed-Phase Cloud Properties Derived from Surface-Based Sensors at SHEBA MATTHEW D. SHUPE

  15. Retrieval of Polar Stratospheric Cloud Microphysical Properties From Lidar Measurements: Dependence on Particle Shape Assumptions

    NASA Technical Reports Server (NTRS)

    Reichardt, Susanne; Reichardt, Jens; Yang, Ping; McGee, Thomas J.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Knowledge of particle sizes and number densities of polar stratospheric clouds (PSCs) is highly important, because they are critical parameters for the modeling of the ozone chemistry of the stratosphere. In situ measurements of PSC particles are rare. the main instrument for the accumulation of PSC data are lidar systems. Therefore the derivation of some microphysical properties of PSCS from the optical parameters measured by lidars would be highly beneficial for ozone research. Inversion of lidar data obtained in the presence of PSCs formed from crystalline particles type 11 and the various nitric acid tri Ydrrate (NAT) types cannot be easily accomplished, because a suitable scattering theory for small faceted crystals has not been readily available tip to now. As a consequence, the T-matrix method is commonly used for the interpretation of these PSC lidar data. Here the assumption is made that the optical properties of an ensemble of spheroids resemble those of crystalline PSCs, and microphysical properties of the PSC are inferred from the optical signatures of the PSC at two or more wavelengths. The problem with the T-matrix approach is that the assumption of spheroidal instead of faceted particles can lead to dramatically wrong results: Usually cloud particle properties are deduced from analysis of lidar profiles of backscatter ratio and depolarization ratio. The particle contribution to the backscatter ratio is given by the product of the particle number density and the backscattering cross section. The latter is proportional to the value of the particle's scattering phase function at 180 degrees scattering angle. At 180 degrees however, the phase functions of rough, faceted crystals and of spheroids with same maximum dimension differ by a factor of 6. From this it follows that for a PSC consisting of faceted crystals, the particle number density is underestimated by roughly the same factor if spheroidal particles are unrealistically assumed. We are currently developing a retrieval technique for determining the microphysical parameters of crystalline PSCs that takes into account the faceted shape of the PSC particles. This approach utilizes finite-difference time-domain (FDTD) calculations of particle optical properties. The accuracy and the free choice of the shape of the scattering particle make the FDTD technique a promising tool for the inversion of PSC lidar data. A first comparison of FDTD and T-matrix calculations will be presented.

  16. 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.

  17. 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.

  18. Numerical study on influence of turbulent droplet clustering on radar reflectivity factor under cumulus cloud conditions

    NASA Astrophysics Data System (ADS)

    Matsuda, K.; Onishi, R.; Takahashi, K.; Kurose, R.; Komori, S.

    2014-12-01

    Spatial correlations of cloud droplets cause particulate Bragg scattering, which increases the reflected microwave intensity in radar observations. Most studies assume that particulate Bragg scattering is insignificant in clouds. However, cloud turbulence generates microscale clusters of cloud droplets due to centrifugal effects. This indicates that the influence of turbulent clustering can be a cause of observational errors. Thus, this study aims to investigate the influence of turbulent clustering of cloud droplets on the radar reflectivity factor. Droplet clustering data are obtained by performing a three-dimensional direct numerical simulation (DNS), in which an isotropic turbulence is generated by solving the Navier-Stokes equation without any turbulence model and a large number of droplet motions are tracked by the Lagrangian method. The clustering data are used to calculate the power spectrum of number density fluctuation. The results show that the turbulent Reynolds number dependency of the power spectrum is sufficiently small for enough high turbulent Reynolds number. On the other hand, the spectrum is strongly dependent on the Stokes number, which is defined as the ratio of droplet relaxation time to the Kolmogorov time. Thus, the influence of turbulent clustering on the radar reflectivity factor is estimated by using the power spectrum considering the Stokes number dependency. We will show the estimate results under ideal cumulus cloud conditions, where the droplet size distributions and the number densities are set based on the dataset of Hess et al. (1998), and discuss the influence on radar cloud observations.

  19. 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.

  20. 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).

  1. Lidar Investigations of Atmospheric Boundary Layer Clouds over Coastal Environment and its Diurnal Evolution

    NASA Astrophysics Data System (ADS)

    Mishra, Manoj; Rajeev, Kunjukrishnapillai; Nair, Anish Kumar M.

    Over the high pressure region, diurnal evolution of atmospheric boundary layer (ABL) leads to the development of fair weather clouds, which in turn play an important role in modulating the thermodynamic structure of ABL, radiation balance at surface, and further development of ABL. As they usually cap the ABL, aerosol-cloud interaction in these clouds are expected to be quite large. Notwithstanding their importance, characteristics of the ABL clouds, their diurnal evolution and the resulting feedback are least explored. Major objectives of this study are to: (i) quantify the diurnal evolution of fair-weather ABL clouds and their characteristics (in terms of their altitude of occurrence, physical thickness and optical depth) based on multi-year (2008-2011) Micropulse Lidar observations at the coastal station, Thumba (8.5(°) N, 77(°) E), and (ii) explore the potential impact of these clouds in modulating the downwelling shortwave radiative flux at surface and further development of ABL. Altitude of occurrence of ABL clouds is found to undergo significant diurnal variation during the development of convective ABL (CABL). Typically, the ABL cloud base increases from <500 m at ˜09 LT to >1500 m at ˜12 LT. Base altitude of the ABL clouds is rather steady during the afternoon, associated with the stabilization of CABL development. Clouds in the nocturnal ABL (NABL) generally occur at the altitude of the preceding afternoon CABL height. Simultaneous occurrence of clouds in the thermal internal boundary layer (TIBL) and developed CABL/residual layer (RL) are also observed, through they are less frequent. The TIBL clouds are distinctly separated from those formed at the top of CABL/RL. Base heights of clouds are distinctly lower in TIBL and evolving CABL compared to those in developed CABL and RL, though their mean physical thickness are comparable (typically ˜250m). Optically thin clouds dominate the TIBL, compared to the other three regimes. Reduction in the instantaneous incoming shortwave flux by ABL clouds can be as large as 550 Wm(-2) and the associated surface cooling would inhibit the growth of thermals, causing a reduction in the rate of CABL growth.

  2. 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.

  3. CART Raman Lidar Aerosol and Water Vapor Measurements in the Vicinity of Clouds

    NASA Technical Reports Server (NTRS)

    Clayton, Marian B.; Ferrare, Richard A.; Turner, David; Newsom, Rob; Sivaraman, Chitra

    2008-01-01

    Aerosol and water vapor profiles acquired by the Raman lidar instrument located at the Climate Research Facility (CRF) at Southern Great Plains (SGP) provide data necessary to investigate the atmospheric variability in the vicinity of clouds near the top of the planetary boundary layer (PBL). Recent CARL upgrades and modifications to the routine processing algorithms afforded the necessarily high temporal and vertical data resolutions for these investigations. CARL measurements are used to investigate the behavior of aerosol backscattering and extinction and their correlation with water vapor and relative humidity.

  4. Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) Spacecraft: Independent Technical Assessment

    NASA Technical Reports Server (NTRS)

    Gilbrech, Richard J.; McManamen, John P.; Wilson, Timmy R.; Robinson, Frank; Schoren, William R.

    2005-01-01

    CALIPSO is a joint science mission between the CNES, LaRC and GSFC. It was selected as an Earth System Science Pathfinder satellite mission in December 1998 to address the role of clouds and aerosols in the Earth's radiation budget. The spacecraft includes a NASA light detecting and ranging (LIDAR) instrument, a NASA wide-field camera and a CNES imaging infrared radiometer. The scope of this effort was a review of the Proteus propulsion bus design and an assessment of the potential for personnel exposure to hydrazine propellant.

  5. Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) Spacecraft: Independent Technical Assessment

    NASA Technical Reports Server (NTRS)

    Gilbrech, Richard J.; McManamen, John P.; Wilson, Timmy R.; Robinson, Frank; Schoren, William R.

    2004-01-01

    CALIPSO is a joint science mission between the CNES, LaRC and GSFC. It was selected as an Earth System Science Pathfinder satellite mission in December 1998 to address the role of clouds and aerosols in the Earth's radiation budget. The spacecraft includes a NASA light detecting and ranging (LIDAR) instrument, a NASA wide-field camera and a CNES imaging infrared radiometer. The scope of this effort was a review of the Proteus propulsion bus design and an assessment of the potential for personnel exposure to hydrazine propellant.

  6. Combined Observational and Model Investigations of the ZLWC Relationship in Stratocumulus Clouds

    E-print Network

    Mark, Pinsky

    the complexity and nonunique character of radar reflectivity­liquid water content (Z­LWC) relationships as their moments (e.g., aerosol and drop concentration, mass content, radar reflectivity) in each parcel (ISCCP) Regional Experiment (FIRE; Austin et al. 1995), the Cloud Lidar and Radar Experiment (CLARE'98

  7. Stratocumulus Liquid Water Content from Dual Wavelength Radar Robin J. Hogan # , Anthony J. Illingworth, John W. F. Goddard + , Suzanne C. H. M. Jongen # and Henri Sauvageot ++

    E-print Network

    Hogan, Robin

    contrib­ ute negligibly to LWC but dominate radar reflectivity such that the absolute value) and LWC taken during the 1998 Cloud Radar and Lidar Experiment (CLARE'98) at Chilbolton, EnglandStratocumulus Liquid Water Content from Dual Wavelength Radar Robin J. Hogan # , Anthony J

  8. 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.

  9. 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.

    2013-11-01

    The Scanning ARM Cloud Radars (SACR's) 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 common scan strategy is to repetitively slice the atmosphere from horizon to horizon as clouds advect over the radar (Cross-Wind Range Height Indicator - CWRHI). Here, the processing and gridding of the SACR CW-RHI scans are presented. First, the SACR sample observations from the ARM Oklahoma (SGP) and Cape-Cod (PVC) sites are post-processed (detection mask, velocity de-aliasing and gaseous attenuation correction). The resulting radial Doppler moment fields are then mapped to Cartesian coordinates with time as one of the dimension. The Cartesian-gridded Doppler velocity fields are next 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 clouds dynamical representations up to 25-30° off zenith. The proposed gridded products are expected to advance our understanding of 3-D cloud morphology, dynamics, anisotropy and lead to more realistic 3-D radiative transfer calculations.

  10. 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.

  11. 4A.5 DERIVING TURBULENT KINETIC ENERGY DISSIPATION RATE WITHIN CLOUDS USING GROUND BASED 94 GHZ RADAR

    E-print Network

    Hogan, Robin

    RADAR Dominique Bouniol # , Anthony J. Illingworth, Robin J. Hogan Centre d' â?? etude des Environnemant radar data (Brewster and Zrniâ?? c 1986). Another technique is to derive e from ground based spectral based 94 GHz radar in order to derive e within non­ precipitating clouds which can be composed of wa

  12. Observations of atmospheric water vapor, aerosol, and cloud with a Raman lidar

    NASA Astrophysics Data System (ADS)

    Yufeng, Wang; Fei, Gao; Chengxuan, Zhu; Qing, Yan; Dengxin, Hua

    2014-11-01

    To realize the improvement of signal-to-noise ratio and rejection rate for elastic Mie-Rayleigh signals, a set of dichroic mirrors and narrow-band interference filters with high efficiency was proposed to constitute a new spectroscopy for atmospheric water vapor, aerosol, and cloud studies. Based on the curves of signal-to-noise ratio at three different channels, the actual rejection rates of elastic Mie-Rayleigh signals at the Raman channels were found to be higher than eight orders of magnitude with the cloudy conditions. Continuous nighttime observations showed that the statistical error of the water vapor mixing ratio was <10% at a height of 2.3 km with an aerosol backscatter ratio of 17. Temporal variations of water vapor and aerosols were obtained under the conditions of cloud and cloud-free, the change relevance between aerosol and water vapor was analyzed, and the growth characteristics of water vapor and aerosols showed a good agreement within the cloud layers. Obtained results indicate achievement of the continuous detection of water vapor, aerosol, and cloud with a high efficiency and stability by Raman lidar.

  13. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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 dependent snow crystal size distribution.

  15. Orbiting lidar simulations. 2: Density, temperature, aerosol, and cloud measurements by a wavelength-combining technique.

    PubMed

    Russell, P B; Morley, B M

    1982-05-01

    A technique is described for combining several wavelength backscatter measurements to yield profiles of molecular density and temperature plus aerosol and cloud backscatter with associated error-bar profiles. Error sources include signal, transmission, calibration, conventional density, lidar density normalization, temperature or pressure estimation at a reference height, and backscatter wavelength-dependence estimation. Strong particulate contamination limits the technique to the cloud-free upper troposphere and above. Error bars automatically returned as part of the measurement show when such contamination occurs. Relative density (temperature) profiles have rms errors of 0.5-2% (1.2-2.5 K) in the nonvolcanic stratosphere and upper troposphere. The density profiles significantly improve aerosol retrievals. The fine vertical resolution of the temperature profiles would permit defining the tropopause to approximately 0.5 km and higher wave structures to 1 or 2 km. PMID:20389896

  16. The El Chichon volcanic cloud in the stratosphere - Lidar observation at Fukuoka and numerical simulation

    NASA Astrophysics Data System (ADS)

    Shibata, T.; Fujiwara, M.; Hirono, M.

    1984-12-01

    The El Chichon April 1982 eruption's stratospheric cloud was routinely observed by a Nd:YAG lidar system. These observations, together with numerical calculations, indicate that the stratospheric vertical eddy diffusion coefficient in the summer easterly region is of the order of 100 sq cm/sec or less. It is also predicted on these bases that the stratospheric materials of tropospheric origin should be found in smaller concentrations in the summer easterly wind region. It is suggested that the observed reincrease of the integrated backscattering coefficient in September-December 1982 was not caused only by the delayed oxidation of injected SO2, but also by seasonal variation of the meridional advective and diffusive transport from lower to higher latitudes. Nucleation within the cloud renders the simulated results more plausible, in view of observed results.

  17. 20 Years Lidar Observations of Clouds at the Edge of Space

    NASA Astrophysics Data System (ADS)

    Fiedler, J.; Baumgarten, G.; Luebken, F.

    2013-12-01

    The highest clouds in the Earth atmosphere are located around 83 km altitude. They were first documented in 1885 and are called noctilucent clouds (NLC) because of the impressive bluish-white displays they form against the dark night sky. NLC occur during the summer months from mid to high latitudes and are a visible sign of the extreme conditions in the mesopause region. They consist of nano-sized ice particles (mean value 48×1 nm) which are subject to the variability of the ambient atmosphere. Ice formation and growth at these high altitudes is very sensitive to temperature and water vapor content which are hardly to measure directly with high accuracy. Thus NLC can act as tracers for short-term variations and are thought to document long-term atmospheric changes as well. We will report about our NLC time series obtained by laser optical remote sensing at the research station ALOMAR in Northern Norway (69°N, 16°E). The data archive obtained with the Rayleigh/Mie/Raman-lidar covers now 20 summer seasons and is the largest NLC data set acquired by lidar. It shows variabilities of basic cloud parameters like occurrence, altitude and brightness on time scales ranging from minutes to years. Using the capability of all three emitted laser wavelengths we are able to determine ice particle properties like mean and width of the size distribution and number density. This allows investigation of the cloud water content and its variability. Comparing our ground-based measurements on a fixed location to data sets obtained from sun-synchronous satellites shows certain differences. They could at least partly be attributed to the observation conditions like measurement volume, local time, scattering angles etc. We found atmospheric tides to have a significant influence on the NLC properties. Additionally microphysical processes limit the duration within the ice particles can be considered as passive tracers. Long-term data sets are subject to varying instrument sensitivities, caused by atmospheric transmission as well as system performance. We have investigated the temporal development of the lower lidar detection limit and its impact on the retrieved cloud properties. It is important to take these effects into account as they can change the tendency of long time series.

  18. Optical depths of semi-transparent cirrus clouds over oceans from CALIPSO infrared radiometer and lidar measurements, and an evaluation of the lidar multiple scattering factor

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    This paper provides a detailed evaluation of cloud absorption optical depths retrieved at 12.05 ?m and comparisons to extinction optical depths retrieved at 0.532 ?m from perfectly co-located observations of single-layered semi-transparent cirrus over ocean 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. The blackbody radiance taken in the IIR Version 3 algorithm is evaluated, and IIR retrievals are corrected accordingly. IIR infrared absorption optical depths are then compared to CALIOP visible extinction optical depths when the latter can be directly derived from the measured apparent 2-way transmittance through the cloud. Numerical simulations and IIR retrievals of ice crystal sizes suggest that the ratios of CALIOP extinction and IIR absorption optical depths should remain roughly constant with respect to temperature. Instead, these ratios are found to increase quasi-linearly by about 40% as the temperature at the layer centroid altitude decreases from 240 to 200 K. This behavior is explained by variations of the multiple scattering factor ?T to be applied to correct the measured transmittance, which is taken equal to 0.6 in the CALIOP Version 3 algorithm, and which is found here to vary with temperature (and hence cloud particle size) from ?T = 0.8 at 200 K to ?T = 0.5 at 240 K for clouds with optical depth larger than 0.3. The revised parameterization of ?T introduces a concomitant temperature dependence in the simultaneously derived CALIOP lidar ratios that is consistent with observed changes in CALIOP depolarization ratios and particle habits derived from IIR measurements.

  19. Lidar multiple scattering factors inferred from CALIPSO lidar and IIR retrievals of semi-transparent cirrus cloud optical depths over oceans

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    Cirrus cloud absorption optical depths retrieved at 12.05 ?m are compared to extinction optical depths retrieved at 0.532 ?m from perfectly co-located observations of single-layered semi-transparent cirrus over ocean 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. IIR infrared absorption optical depths are compared to CALIOP visible extinction optical depths when the latter can be directly derived from the measured apparent two-way transmittance through the cloud. An evaluation of the CALIOP multiple scattering factor is inferred from these comparisons after assessing and correcting biases in IIR and CALIOP optical depths reported in version 3 data products. In particular, the blackbody radiance taken in the IIR version 3 algorithm is evaluated, and IIR retrievals are corrected accordingly. Numerical simulations and IIR retrievals of ice crystal sizes suggest that the ratios of CALIOP extinction and IIR absorption optical depths should remain roughly constant with respect to temperature. Instead, these ratios are found to increase quasi-linearly by about 40 % as the temperature at the layer centroid altitude decreases from 240 to 200 K. It is discussed that this behavior can be explained by variations of the multiple scattering factor ?T applied to correct the measured apparent two-way transmittance for contribution of forward-scattering. While the CALIOP version 3 retrievals hold ?T fixed at 0.6, this study shows that ?T varies with temperature (and hence cloud particle size) from ?T = 0.8 at 200 K to ?T = 0.5 at 240 K for single-layered semi-transparent cirrus clouds with optical depth larger than 0.3. The revised parameterization of ?T introduces a concomitant temperature dependence in the simultaneously derived CALIOP lidar ratios that is consistent with observed changes in CALIOP depolarization ratios and particle habits derived from IIR measurements.

  20. Optical and microphysical parameters of dense stratocumulus clouds during mission 206 of EUCREX '94 as retrieved from measurements made with the airborne lidar LEANDRE 1

    NASA Astrophysics Data System (ADS)

    Pelon, J.; Flamant, C.; Trouillet, V.; Flamant, P. H.

    Cloud parameters derived from measurements performed with the airborne backscatter lidar LEANDRE 1 during mission 206 of the EUCREX '94 campaign are reported. A new method has been developed to retrieve the extinction coefficient at the top of the dense stratocumulus deck under scrutiny during this mission. The largest extinction values are found to be related to the highest cloud top altitude revealing the small-scale structure of vertical motions within the stratocumulus field. Cloud optical depth (COD) is estimated from extinction retrievals, as well as cloud top and cloud base altitude using nadir and zenith lidar observations, respectively. Lidar-derived CODs are compared with CODs deduced from radiometric measurements made onboard the French research aircraft Avion de Recherche Atmosphérique et de Télédétection (ARAT/F27). A fair agreement is obtained (within 20%) for COD's larger than 10. Our results show the potential of lidar measurements to analyze cloud properties at optical depths larger than 5.

  1. Estimation of cirrus cloud particle fallspeeds from vertically pointing Doppler radar

    NASA Technical Reports Server (NTRS)

    Orr, Brad W.; Kropfli, Robert A.

    1993-01-01

    The First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment 2 (FIRE 2) was conducted in Coffeyville, Kansas in late 1991 to study the microphysical and radiative properties of cirrus clouds. A variety of active and passive remote sensors were employed, including an 8-mm-wavelength cloud-sensing Doppler radar developed at the Wave Propagation Laboratory (WPL). The radar, having excellent sensitivity to cloud particles (-30 dBZ at 10 km), good spatial resolution (37 m), and velocity precision (.05 ms -1), is an excellent tool for observing cirrus clouds. Having this radar directed toward the zenith for long periods of time during FIRE 2 permitted the reflectivity-weighted particle fallspeed to be related to reflectivity which allowed a separation of ice particle fallspeeds from vertical air motions. Additionally, such relationships proved useful in other multi-sensor techniques for determining vertical profiles of ice particle characteristic size and ice water content in cirrus clouds. The analysis method and the results of applying it to cirrus cloud reflectivity and velocity data collected during FIRE 2 are discussed.

  2. TRMM Radar Observations of Cloud Tops in the Tropical Tropopause Layer

    NASA Technical Reports Server (NTRS)

    Alcala, C. M.; Dessler, A. E.; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    Air dehydrates to stratospheric abundances in the tropical tropopause layer (TTL). The role of overshooting convection in the dehydration process is not well understood. To study this effect, we use the TRMM (Tropical Rainfall Measuring Mission) precipitation radar (PR) to measure the altitudes of cloud tops forming in the TTL. Because the radar signal is dominated by scatter from large particles, these cloud observations imply the presence of strong convective systems with large updraft. Both winter and summer data from two different years are examined to study both interseasonal and interannual variability. The global distribution of these clouds is in good agreement with those of the surface precipitation rates. In addition, the altitude distributions of these clouds follow an exponential dependence. However, clouds over continental regions typically extend to higher altitudes in the tropics. Almost no cloud tops were observed above 20 km. Comparison between the radar cloud tops and colocated IR brightness temperature measurements reveal a large difference in both the diurnal cycle and intensity between continental and oceanic convection.

  3. 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-31, the ship remained located at roughly 10N,95 W. A cloud radar (Ka-band,8.66 mm wavelength) was present on the RHB during this time. Although cloud radars are not normally applied within heavily-raining regions

  4. Intercomparison of snowfall estimates derived from the CloudSat Cloud Profiling Radar and the ground based weather radar network over Sweden

    NASA Astrophysics Data System (ADS)

    Norin, L.; Devasthale, A.; L'Ecuyer, T. S.; Wood, N. B.; Smalley, M.

    2015-08-01

    To be able to estimate snowfall accurately is important for both weather and climate applications. Ground-based weather radars and space-based satellite sensors are often used as viable alternatives to rain-gauges to estimate precipitation in this context. The Cloud Profiling Radar (CPR) onboard CloudSat is especially proving to be a useful tool to map snowfall globally, in part due to its high sensitivity to light precipitation and ability to provide near-global vertical structure. The importance of having snowfall estimates from CloudSat/CPR further increases in the high latitude regions as other ground-based observations become sparse and passive satellite sensors suffer from inherent limitations. Here we intercompared snowfall estimates from two observing systems, CloudSat and Swerad, the Swedish national weather radar network. Swerad offers one of the best calibrated data sets of precipitation amount at very high latitudes that are anchored to rain-gauges and that can be exploited to evaluate usefulness of CloudSat/CPR snowfall estimates in the polar regions. In total 7.2×105 matchups of CloudSat and Swerad over Sweden were inter-compared covering all but summer months (October to May) from 2008 to 2010. The intercomparison shows encouraging agreement between these two observing systems despite their different sensitivities and user applications. The best agreement is observed when CloudSat passes close to a Swerad station (46-82 km), when the observational conditions for both systems are comparable. Larger disagreements outside this range suggest that both platforms have difficulty with shallow snow but for different reasons. The correlation between Swerad and CloudSat degrades with increasing distance from the nearest Swerad station as Swerad's sensitivity decreases as a function of distance and Swerad also tends to overshoots low level precipitating systems further away from the station, leading to underestimation of snowfall rate and occasionally missing the precipitation altogether. Further investigations of various statistical metrics, such as the probability of detection, false alarm rate, hit rate, and the Hanssen-Kuipers skill scores, and the sensitivity of these metrics to snowfall rate and the distance from the radar station, were carried out. The results of these investigations highlight the strengths and the limitations of both observing systems at the lower and upper ends of snowfall distributions and the range of uncertainties that could be expected from these systems in the high latitude regions.

  5. Off-beam (multiply-scattered) lidar returns from stratus. 1; Cloud-information content and sensitivity to noise

    NASA Technical Reports Server (NTRS)

    Davis, Anthony B.; Cahalan, Robert F.

    1998-01-01

    We review the basic multiple scattering theory of off-beam lidar returns from optically thick clouds using the diffusion approximation. The shape of the temporal signal - the stretched pulse - depends primarily on the physical thickness of the cloud whereas its spatial counterpart - the diffuse spot - conveys specific information on the cloud's optical thickness, as do the absolute returns. This makes observation of the weak off-beam lidar returns an attractive prospect in remote sensing of cloud properties. By estimating the signal-to-noise ratio, we show that night-time measurements can be performed with existing technology. By the same criterion, day-time operation is a challenge that can only be met with a combination of cutting-edge techniques in filtering and in laser sources.

  6. Dual wavelength lidar observation of tropical high-altitude cirrus clouds during the ALBATROSS 1996 Campaign

    NASA Astrophysics Data System (ADS)

    Beyerle, G.; Schäfer, H.-J.; Neuber, R.; Schrems, O.; McDermid, I. S.

    Dual wavelength aerosol lidar observations of tropical high-altitude cirrus clouds were performed during the ALBATROSS 1996 campaign aboard the research vessel “POLARSTERN” on the Atlantic ocean in October-November 1996. On the basis of 57 hours of night-time observations between 23.5°N and 23.5°S we find in 72% of the altitude profiles indications of the presence of cirrus cloud layers. This percentage drops to 32% at subtropical latitudes (23.5°-30°) based on 15 hours of data. About one-half of the subtropical and tropical cirrus layers are subvisual with an optical depth of less than 0.03 at a wavelength of 532 nm. In general the clouds exhibit high spatial and temporal variability on scales of a few tens of meters vertically and a few hundred meters horizontally. No clouds are observed above the tropopause. An abrupt change in the relation between the color ratios of the parallel and perpendicular backscatter coefficients at about 240 K is interpreted in terms of changes of particle shape and/or size distribution. At temperatures between 195 and 255 K only a small fraction of the observations are consistent with the presence of small particles with dimensions of less than 0.1 µm.

  7. 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.

  8. The 27-28 October 1986 FIRE IFO Cirrus Case Study: Cloud Optical Properties Determined by High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Grund, C. J.; Eloranta, E. W.

    1996-01-01

    During the First ISCCP Region Experiment (FIRE) cirrus intensive field observation (IFO) the High Spectral Resolution Lidar was operated from a roof top site on the University of Wisconsin-Madison campus. Because the HSRL technique separately measures the molecular and cloud particle backscatter components of the lidar return, the optical thickness is determined independent of particle backscatter. This is accomplished by comparing the known molecular density distribution to the observed decrease in molecular backscatter signal with altitude. The particle to molecular backscatter ratio yields calibrated measurements of backscatter cross sections that can be plotted ro reveal cloud morphology without distortion due to attenuation. Changes in cloud particle size, shape, and phase affect the backscatter to extinction ratio (backscatter-phase function). The HSRL independently measures cloud particle backscatter phase function. This paper presents a quantitative analysis of the HSRL cirrus cloud data acquired over an approximate 33 hour period of continuous near zenith observations. Correlations between small scale wind structure and cirrus cloud morphology have been observed. These correlations can bias the range averaging inherent in wind profiling lidars of modest vertical resolution, leading to increased measurement errors at cirrus altitudes. Extended periods of low intensity backscatter were noted between more strongly organized cirrus cloud activity. Optical thicknesses ranging from 0.01-1.4, backscatter phase functions between 0.02-0.065 sr (exp -1) and backscatter cross sections spanning 4 orders of magnitude were observed. the altitude relationship between cloud top and bottom boundaries and the cloud optical center altitude was dependent on the type of formation observed Cirrus features were observed with characteristic wind drift estimated horizontal sizes of 5-400 km. The clouds frequently exhibited cellular structure with vertical to horizontal dimension ratios of 1:5-1:1.

  9. 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.

  10. Measurements of the Vertical Structure of Aerosols and Clouds Over the Ocean Using Micro-Pulse LIDAR Systems

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Spinhirne, James D.; Campbell, James R.; Berkoff, Timothy A.; Bates, David; Starr, David OC. (Technical Monitor)

    2001-01-01

    The determination of the vertical distribution of aerosols and clouds over the ocean is needed for accurate retrievals of ocean color from satellites observations. The presence of absorbing aerosol layers, especially at altitudes above the boundary layer, has been shown to influence the calculation of ocean color. Also, satellite data must be correctly screened for the presence of clouds, particularly cirrus, in order to measure ocean color. One instrument capable of providing this information is a lidar, which uses pulses of laser light to profile the vertical distribution of aerosol and cloud layers in the atmosphere. However, lidar systems prior to the 1990s were large, expensive, and not eye-safe which made them unsuitable for cruise deployments. During the 1990s the first small, autonomous, and eye-safe lidar system became available: the micro-pulse lidar, or MPL. The MPL is a compact and eye-safe lidar system capable of determining the range of aerosols and clouds by firing a short pulse of laser light (523 nm) and measuring the time-of-flight from pulse transmission to reception of a returned signal. The returned signal is a function of time, converted into range using the speed of light, and is proportional to the amount of light backscattered by atmospheric molecules (Rayleigh scattering), aerosols, and clouds. The MPL achieves ANSI eye-safe standards by sending laser pulses at low energy (micro-J) and expanding the beam to 20.32 cm in diameter. A fast pulse-repetition-frequency (2500 Hz) is used to achieve a good signal-to-noise, despite the low output energy. The MPL has a small field-of-view (< 100 micro-rad) and signals received with the instrument do not contain multiple scattering effects. The MPL has been used successfully at a number of long-term sites and also in several field experiments around the world.

  11. Noctilucent cloud observations at mid-latitudes by lidar: mean state and relation to MSE and temperature during day and night

    NASA Astrophysics Data System (ADS)

    Gerding, Michael; Höffner, Josef; Kopp, Maren; Zecha, Marius; Lübken, Franz-Josef

    Since more than 120 years Noctilucent clouds (NLC) are observed every summer poleward of about 50° latitude. Even if NLC are much more frequent at polar latitudes, NLC observations at mid-latitudes are of particular importance since the average temperature is near the saturation temperature. Hence, NLC occurrence is expected to change strongly with only minor variations in water vapour concentration and temperature, e.g. due to planetary, tidal and gravity waves, and solar cycle. At Leibniz Institute of Atmospheric Physics at Kühlungsborn, Germany (54° N, ° 12 E) NLC are observed since 1997 at 532 nm wavelength. Until 2008 the NLC occurrence rate was up to 12%, while 2009 showed record-high 19%. The altitude distribution centres at 82.9 km, i.e. similar to the polar NLC distribution even if the temperature structures are quite different at these heights. We will compare these mean NLC parameters from nighttime observations with data from the 2009 season, showing comparatively frequent and strong NLC. We will discuss the relation to simultaneously observed temperatures and wave activity for 2009 and previous years. We have set up a daylight capable lidar in summer 2009, measuring NLC independent of solar elevation. By this the retrieval of diurnal variation of NLC occurrence and strength will be possible at our mid-latitude site as one of very few stations in the world. Simultaneous observations of NLC and Mesospheric Summer Echoes (MSE) are limited to daytime since electron densities have to be sufficiently high. The new capabilities of the RMR lidar at Kühlungsborn together with the OSWIN VHF radar and the K lidar allow first case studies from simultaneous NLC and MSE observations at mid-latitudes.

  12. 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.

  13. 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.

  14. Extinction coefficients from lidar observations in ice clouds compared to in-situ measurements from the Cloud Integrating Nephelometer during CRYSTAL-FACE

    NASA Technical Reports Server (NTRS)

    Noel, Vincent; Winker, D. M.; Garrett, T. J.; McGill, M.

    2005-01-01

    This paper presents a comparison of volume extinction coefficients in tropical ice clouds retrieved from two instruments : the 532-nm Cloud Physics Lidar (CPL), and the in-situ probe Cloud Integrating Nephelometer (CIN). Both instruments were mounted on airborne platforms during the CRYSTAL-FACE campaign and took measurements in ice clouds up to 17km. Coincident observations from three cloud cases are compared : one synoptically-generated cirrus cloud of low optical depth, and two ice clouds located on top of convective systems. Emphasis is put on the vertical variability of the extinction coefficient. Results show small differences on small spatial scales (approx. 100m) in retrievals from both instruments. Lidar retrievals also show higher extinction coefficients in the synoptic cirrus case, while the opposite tendency is observed in convective cloud systems. These differences are generally variations around the average profile given by the CPL though, and general trends on larger spatial scales are usually well reproduced. A good agreement exists between the two instruments, with an average difference of less than 16% on optical depth retrievals.

  15. 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.

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

    SciTech Connect

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

    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.

  17. 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.

  18. Change detection of trees in urban areas using multi-temporal airborne lidar point clouds

    NASA Astrophysics Data System (ADS)

    Xiao, Wen; Xu, Sudan; Oude Elberink, Sander; Vosselman, George

    2012-09-01

    Light detection and ranging (lidar) provides a promising way of detecting changes of vegetation in three dimensions (3D) because the beam of laser may penetrate through the foliage of vegetation. This study aims at the detection of changes in trees in urban areas with a high level of automation using mutil-temporal airborne lidar point clouds. Three datasets covering a part of Rotterdam, the Netherlands, have been classified into several classes including trees. A connected components algorithm was applied first to group the points of trees together. The attributes of components were utilized to differentiate tree components from misclassified non-tree components. A point based local maxima algorithm was implemented to distinguish single tree from multiple tree components. After that, the parameters of trees were derived through two independent ways: a point based method using 3D alpha shapes and convex hulls; and a model based method which fits a Pollock tree model to the points. Then the changes were detected by comparing the parameters of corresponding tree components which were matched by a tree to tree matching algorithm using the overlapping of bounding boxes and point to point distances. The results were visualized and statistically analyzed. The difference of parameters and the difference of changes derived from point based and model based methods were both lower than 10%. The comparison of these two methods illustrates the consistency and stability of the parameters. The detected changes show the potential to monitor the growth and pruning of trees.

  19. Mother-of-pearl cloud particle size and composition from aircraft-based photography of coloration and lidar measurements.

    PubMed

    Reichardt, Jens; Reichardt, Susanne; Hostetler, Chris A; Lucker, Patricia L; McGee, Thomas J; Twigg, Laurence W; Dörnbrack, Andreas; Schoeberl, Mark R; Yang, Ping

    2015-02-01

    During a Stratospheric Aerosol and Gas (SAGE)-III Ozone Loss and Validation Experiment (SOLVE)-II science flight on 4 February 2003, a mother-of-pearl cloud over Iceland was underflown by the NASA DC-8 and measured with the lidars onboard. In addition, color photos were taken during the approach. Aided by extensive modeling of cloud coloration, the main results of the analysis of this unique data set are: (1) the polar stratospheric cloud was mountain wave-induced and of type II; (2) the spectacular color display was caused by ice particles with sizes around 2 ?m. PMID:25967820

  20. 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.

  1. Airborne lidar observations in the wintertime Arctic stratosphere - Polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Browell, E. V.; Ismail, S.; Carter, A. F.; Higdon, N. S.; Butler, C. F.; Robinette, P. A.; Toon, O. B.; Schoeberl, M. R.

    1990-01-01

    Polar stratospheric cloud (PSC) distributions in the wintertime Arctic stratosphere and their optical characteristics were measured with a multiwavelength airborne lidar system as part of the 1989 Airborne Arctic Stratospheric Expedition. PSCs were observed on 10 flights between January 6 and February 2, 1989, into the polar vortex. The PSCs were found in the 14-27 km altitude range in regions where the temperatures were less than 195 K. Two types of aerosols with different optical characteristics (Types 1a and 1b) were observed in PSCs thought to be composed of nitric acid trihydrate. Water ice PSCs (Type 2) were observed to have high scattering ratios (greater than 10) and high aerosol depolarizations (greater than 10 percent) at temperatures less than 190 K.

  2. Dual-polarization airborne lidar observations of polar stratospheric cloud evolution

    SciTech Connect

    Poole, L.R.; McCormick, M.P. ); Kent, G.S.; Schaffner, S. ); Hunt, W.H. ); Osborn, M.T.; Pitts, M.C. )

    1990-03-01

    Dual-polarization {lambda}=0.532 {mu}m lidar data show systematic polar stratospheric cloud (PSC) evolution along a portion of the Airborne Arctic Stratospheric Expedition DC-8 flight of January 31, 1989. This flight leg was roughly aligned with air parcel motion on isentropic surfaces from 400-500K, where the local adiabatic cooling rate was {approximately}20 K/day. Type 1 PSCs show low depolarization ratios and scattering ratios which approach intermediate limiting values as ambient temperature decreases. These data suggest that Type 1 particles formed by rapid cooling may be nearly spherical and are restricted in size by partitioning of a limited HNO{sub 3} vapor supply among many competing growth sites. Type 2 PSCs appear at temperatures below estimated local frost points with increases in depolarization and scattering typical of larger ice crystals.

  3. Effects of the Hawaiian Islands on the vertical structure of low-level clouds from CALIPSO lidar

    NASA Astrophysics Data System (ADS)

    Liu, Jing-Wu; Xie, Shang-Ping; Zhang, Su-Ping

    2015-01-01

    steady northeast trade winds impinge on the Hawaiian Islands, producing prominent island wakes of multispatial scales from tens to thousands of kilometers. Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) reveal rich three-dimensional structures of low-level clouds that are induced by the islands, distinct from the background environment. The cloud frequency peaks between 1.5 and 2.0 km in cloud top elevation over the windward slopes of the islands of Kauai and Oahu due to orographic lifting and daytime island heating. In the nighttime near-island wake of Kauai, CALIPSO captures a striking cloud hole below 1.6 km as the cold advection from the island suppresses low-level clouds. The cyclonic eddy of the mechanical wake behind the island of Hawaii favors the formation of low-level clouds (below 2.5 km), and the anticyclonic eddy suppresses the low-level cloud formation, indicative of the dynamical effect on the vertical structure of low-level clouds. In the long Hawaiian wake due to air-sea interaction, low-level clouds form over both the warmer and colder waters, but the cloud tops are 400-600 m higher over the warm than the cold waters. In addition, the day-night differences and the sensitivity of low-level clouds to the background trade wind inversion height are also studied.

  4. Development of Spaceborne Radar Simulator by NICT and JAXA using JMA Cloud-resolving Model

    NASA Astrophysics Data System (ADS)

    Kubota, T.; Eito, H.; Aonashi, K.; Hashimoto, A.; Iguchi, T.; Hanado, H.; Shimizu, S.; Yoshida, N.; Oki, R.

    2009-12-01

    We are developing synthetic spaceborne radar data toward a simulation of the Dual-frequency Precipitation Radar (DPR) aboard the Global Precipitation Measurement (GPM) core-satellite. Our purposes are a production of test-bed data for higher level DPR algorithm developers, in addition to a diagnosis of a cloud resolving model (CRM). To make the synthetic data, we utilize the CRM by the Japan Meteorological Agency (JMA-NHM) (Ikawa and Saito 1991, Saito et al. 2006, 2007), and the spaceborne radar simulation algorithm by the National Institute of Information and Communications Technology (NICT) and the Japan Aerospace Exploration Agency (JAXA) named as the Integrated Satellite Observation Simulator for Radar (ISOSIM-Radar). The ISOSIM-Radar simulates received power data in a field of view of the spaceborne radar with consideration to a scan angle of the radar (Oouchi et al. 2002, Kubota et al. 2009). The received power data are computed with gaseous and hydrometeor attenuations taken into account. The backscattering and extinction coefficients are calculated assuming the Mie approximation for all species. The dielectric constants for solid particles are computed by the Maxwell-Garnett model (Bohren and Battan 1982). Drop size distributions are treated in accordance with those of the JMA-NHM. We assume a spherical sea surface, a Gaussian antenna pattern, and 49 antenna beam directions for scan angles from -17 to 17 deg. in the PR. In this study, we report the diagnosis of the JMA-NHM with reference to the TRMM Precipitation Radar (PR) and CloudSat Cloud Profiling Radar (CPR) using the ISOSIM-Radar from the view of comparisons in cloud microphysics schemes of the JMA-NHM. We tested three kinds of explicit bulk microphysics schemes based on Lin et al. (1983), that is, three-ice 1-moment scheme, three-ice 2-moment scheme (Eito and Aonashi 2009), and newly developed four-ice full 2-moment scheme (Hashimoto 2008). The hydrometeor species considered here are rain, graupel, snow, cloud water, cloud ice and hail (4-ice scheme only). We examined a case of an intersection with the TRMM PR and the CloudSat CPR on 6th April 2008 over sea surface in the south of Kyushu Island of Japan. In this work, observed rainfall systems are simulated with one-way double nested domains having horizontal grid sizes of 5 km (outer) and 2 km (inner). Data used here are from the inner domain only. Results of the PR indicated better performances of 2-moment bulk schemes. It suggests that prognostic number concentrations of frozen hydrometeors are more effective in high altitudes and constant number concentrations can lead to the overestimation of the snow there. For three-ice schemes, simulated received power data overestimated above freezing levels with reference to the observed data. In contrast, the overestimation of frozen particles was heavily reduced for the four-ice scheme.

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

    SciTech Connect

    Turner, D.D. Whiteman, D.N. Russo, F.

    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

  6. 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.

  7. 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.

  8. Turbulence as observed by concurrent measurements made at NSSL using weather radar, Doppler radar, Doppler lidar and aircraft

    NASA Technical Reports Server (NTRS)

    Lee, Jean T.

    1987-01-01

    As air traffic increases and aircraft capability increases in range and operating altitude, the exposure to weather hazards increases. Turbulence and wind shears are two of the most important of these hazards that must be taken into account if safe flight operations are to be accomplished. Beginning in the early 1960's, Project Rough Rider began thunderstorm investigations. Past and present efforts at the National Severe Storm Laboratory (NSSL) to measure these flight safety hazards and to describe the use of Doppler radar to detect and qualify these hazards are summarized. In particular, the evolution of the Doppler-measured radial velocity spectrum width and its applicability to the problem of safe flight is presented.

  9. 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.

  10. Macrophysical and optical properties of midlatitude cirrus clouds from four ground-based lidars and collocated CALIOP observations

    SciTech Connect

    Dupont, Jean-Charles; Haeffelin, M.; Morille, Y.; Noel, V.; Keckhut, P.; Winker, D.; Comstock, Jennifer M.; Chervet, P.; Roblin, A.

    2010-05-27

    Ground-based lidar and CALIOP datasets gathered over four mid-latitude sites, two US and two French sites, are used to evaluate the consistency of cloud macrophysical and optical property climatologies that can be derived by such datasets. The consistency in average cloud height (both base and top height) between the CALIOP and ground datasets ranges from -0.4km to +0.5km. The cloud geometrical thickness distributions vary significantly between the different datasets, due in part to the original vertical resolutions of the lidar profiles. Average cloud geometrical thicknesses vary from 1.2 to 1.9km, i.e. by more than 50%. Cloud optical thickness distributions in subvisible, semi-transparent and moderate intervals differ by more than 50% between ground and space-based datasets. The cirrus clouds with 2 optical thickness below 0.1 (not included in historical cloud climatologies) represent 30-50% of the non-opaque cirrus class. The differences in average cloud base altitude between ground and CALIOP datasets of 0.0-0.1 km, 0.0-0.2 km and 0.0-0.2 km can be attributed to irregular sampling of seasonal variations in the ground-based data, to day-night differences in detection capabilities by CALIOP, and to the restriction to situations without low-level clouds in ground-based data, respectively. The cloud geometrical thicknesses are not affected by irregular sampling of seasonal variations in the ground-based data, while up to 0.0-0.2 km and 0.1-0.3 km differences can be attributed to day-night differences in detection capabilities by CALIOP, and to the restriction to situations without lowlevel clouds in ground-based data, respectively.

  11. Radar-Derived Forecasts of Cloud-to-Ground Lightning Over Houston, Texas 

    E-print Network

    Mosier, Richard Matthew

    2011-02-22

    stream_source_info MOSIER-THESIS.pdf.txt stream_content_type text/plain stream_size 229403 Content-Encoding ISO-8859-1 stream_name MOSIER-THESIS.pdf.txt Content-Type text/plain; charset=ISO-8859-1 RADAR... for the degree of MASTER OF SCIENCE December 2009 Major Subject: Atmospheric Sciences RADAR-DERIVED FORECASTS OF CLOUD-TO-GROUglyph1197D LIGHTglyph1197Iglyph1197G OVER HOUSTOglyph1197, TEXAS A Thesis by RICHARD MATTHEW MOSIER Submitted...

  12. Continuous Lidar Monitoring of Polar Stratospheric Clouds at the South Pole

    NASA Technical Reports Server (NTRS)

    Campbell, James R.; Welton, Ellsworth J.; Spinhirne, James D

    2009-01-01

    Polar stratospheric clouds (PSC) play a primary role in the formation of annual ozone holes over Antarctica during the austral sunrise. Meridional temperature gradients in the lower stratosphere and upper troposphere, caused by strong radiative cooling, induce a broad dynamic vortex centered near the South Pole that decouples and insulates the winter polar airmass. PSC nucleate and grow as vortex temperatures gradually fall below equilibrium saturation and frost points for ambient sulfate, nitrate, and water vapor concentrations (generally below 197 K). Cloud surfaces promote heterogeneous reactions that convert stable chlorine and bromine-based molecules into photochemically active ones. As spring nears, and the sun reappears and rises, photolysis decomposes these partitioned compounds into individual halogen atoms that react with and catalytically destroy thousands of ozone molecules before they are stochastically neutralized. Despite a generic understanding of the ozone hole paradigm, many key components of the system, such as cloud occurrence, phase, and composition; particle growth mechanisms; and denitrification of the lower stratosphere have yet to be fully resolved. Satellite-based observations have dramatically improved the ability to detect PSC and quantify seasonal polar chemical partitioning. However, coverage directly over the Antarctic plateau is limited by polar-orbiting tracks that rarely exceed 80 degrees S. In December 1999, a NASA Micropulse Lidar Network instrument (MPLNET) was first deployed to the NOAA Earth Systems Research Laboratory (ESRL) Atmospheric Research Observatory at the Amundsen-Scott South Pole Station for continuous cloud and aerosol profiling. MPLNET instruments are eye-safe, capable of full-time autonomous operation, and suitably rugged and compact to withstand long-term remote deployment. With only brief interruptions during the winters of 2001 and 2002, a nearly continuous data archive exists to the present.

  13. Dual-wavelength millimeter-wave radar measurements of cirrus clouds

    SciTech Connect

    Sekelsky, S.M.; Firda, J.M.; McIntosh, R.E.

    1996-04-01

    In April 1994, the University of Massachusetts` 33-GHz/95-GHz Cloud Profiling Radar System (CPRS) participated in the multi-sensor Remote Cloud Sensing (RCS) Intensive Operation Period (IOP), which was conducted at the Southern Great Plains Cloud and Radiation Testbed (CART). During the 3-week experiment, CPRS measured a variety of cloud types and severe weather. In the context of global warming, the most significant measurements are dual-frequency observations of cirrus clouds, which may eventually be used to estimate ice crystal size and shape. Much of the cirrus data collected with CPRS show differences between 33-GHz and 95-GHz reflectivity measurements that are correlated with Doppler estimates of fall velocity. Because of the small range of reflectivity differences, a precise calibration of the radar is required and differential attenuation must also be removed from the data. Depolarization, which is an indicator of crystal shape, was also observed in several clouds. In this abstract we present examples of Mie scattering from cirrus and estimates of differential attenuation due to water vapor and oxygen that were derived from CART radiosonde measurements.

  14. Automatic registration of optical aerial imagery to a LiDAR point cloud for generation of city models

    NASA Astrophysics Data System (ADS)

    Abayowa, Bernard O.; Yilmaz, Alper; Hardie, Russell C.

    2015-08-01

    This paper presents a framework for automatic registration of both the optical and 3D structural information extracted from oblique aerial imagery to a Light Detection and Ranging (LiDAR) point cloud without prior knowledge of an initial alignment. The framework employs a coarse to fine strategy in the estimation of the registration parameters. First, a dense 3D point cloud and the associated relative camera parameters are extracted from the optical aerial imagery using a state-of-the-art 3D reconstruction algorithm. Next, a digital surface model (DSM) is generated from both the LiDAR and the optical imagery-derived point clouds. Coarse registration parameters are then computed from salient features extracted from the LiDAR and optical imagery-derived DSMs. The registration parameters are further refined using the iterative closest point (ICP) algorithm to minimize global error between the registered point clouds. The novelty of the proposed approach is in the computation of salient features from the DSMs, and the selection of matching salient features using geometric invariants coupled with Normalized Cross Correlation (NCC) match validation. The feature extraction and matching process enables the automatic estimation of the coarse registration parameters required for initializing the fine registration process. The registration framework is tested on a simulated scene and aerial datasets acquired in real urban environments. Results demonstrates the robustness of the framework for registering optical and 3D structural information extracted from aerial imagery to a LiDAR point cloud, when co-existing initial registration parameters are unavailable.

  15. SSM/I and the Montagnana radar data fusion to analyze clouds over Tuscany

    NASA Astrophysics Data System (ADS)

    Nativi, Stefano; Mazzetti, Paolo; Giuli, Dino

    2001-01-01

    The present work empirically deals with the challenging problem of the integration of data obtained from passive and active microwave sources, in order to develop procedures to suitably calibrate and validate satellite-based passive microwave rainfall algorithms by means of multi parameter radar information over midlatitude areas. Furthermore, this research tires to analyze the well-known beam-filling problem and the different microwave channel penetration top9ic. SSM/I passive microwave radiometer precipitation related parameters were analyzed against multi parameter radar Zh and Zdr 3D maps, obtained from the POLAR-55C multi parameter radar set near Florence, Italy. SSM/I-derived parameters, related to rainfall over land were analyzed by means of information derived form radar volume data. We faced several statistical analyses of the obtained data sets. Results report the effectiveness of Montagnana radar and SSM/I data fusion. In particular, it is assessed the utility of utilizing both active and passive microwave hydrometeor-related information in order to improve the inferences about monitored phenomena. Results are valuable in order to better calibrate and validate passive microwave algorithms for rainfall rate estimation and for cloud detection over land. Correlation values may be improved by filtering radar data according to several parameters thresholds, in order to tackle beam-filling problem and statistical issues.

  16. Evaluating cloud microphysics from NICAM against CloudSat and CALIPSO

    NASA Astrophysics Data System (ADS)

    Hashino, Tempei; Satoh, Masaki; Hagihara, Yuichiro; Kubota, Takuji; Matsui, Toshihisa; Nasuno, Tomoe; Okamoto, Hajime

    2013-07-01

    We describe a method to evaluate cloud microphysics simulated with a global cloud-resolving model against CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite data. Output from the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) is run through a satellite-sensor simulator (Joint Simulator for Satellite Sensors), then directly compared to the radar and lidar signals from CloudSat and CALIPSO. The forward approach allows for consistency in cloud microphysical assumption involved in the evaluation. To investigate the dependence of the signals on the temperature, we use temperature extensively as the vertical coordinate. The global statistical analysis of the radar reflectivity shows that the simulation overestimates all the percentiles above -50°C and that snow category contributes significantly to low reflectivity values between -80 and -40°C. The simulated lidar signals have two modes associated with cloud ice and snow categories, though the observations have only one mode. The synergetic use of radar reflectivity and lidar backscatter enables us to determine the relative magnitudes of ice/liquid water contents and effective radii without use of retrievals. The radar-and-lidar diagnosis for cloud tops shows that, due to snow category, NICAM overestimates the mass-equivalent effective radius and underestimates ice water content. Also, the diagnosis was shown to be useful to investigate sensitivities of the parameters of bulk microphysical schemes on the water contents and sizes. The nonspherical scattering of ice particles was shown to affect the above radar-and-lidar diagnosis for large reflectivity ranges but not to alter most of the other diagnoses for this simulation.

  17. 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.

  18. Combined satellite and radar retrievals of drop concentration and CCN at convective cloud base

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Daniel; Fischman, Baruch; Zheng, Youtong; Goren, Tom; Giguzin, David

    2014-05-01

    The number of activated cloud condensation nuclei (CCN) into cloud drops at the base of convective clouds (Na) is retrieved based on the high-resolution (375 m) satellite retrievals of vertical profiles of convective cloud drop effective radius (re). The maximum cloud base supersaturation (S) is calculated when Na is combined with radar-measured updraft and yields CCN(S), which was validated well against ground-based CCN measurements during the conditions of well-mixed boundary layer over the U.S. Department of Energy's Atmospheric System Research Southern Great Plains site. Satellite retrieving Na is a new capability, which is one essential component of simultaneous measurements of cloud microstructure and CCN from space by using clouds as natural CCN chambers. This has to be complemented by a methodology for satellite estimates of cloud base updraft, which is yet to be developed and demonstrated. In the mean time, the retrieved Na can be used for the assimilation of the combined CCN and updraft effects on clouds in models.

  19. Assimilation of coastal Doppler radar data with the ARPS 3DVAR and cloud analysis for the prediction of Hurricane Ike (2008)

    E-print Network

    Xue, Ming

    2008-01-01

    Assimilation of coastal Doppler radar data with the ARPS 3DVAR and cloud analysis, is examined. Radial velocity (Vr) and reflectivity (Z) data from coastal radars are assimilated over a 6-h (2009), Assimilation of coastal Doppler radar data with the ARPS 3DVAR and cloud analysis

  20. 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

  1. NASA/GSFC Scanning Raman Lidar Measurements of Water Vapor and Cirrus Clouds during WVIOP2000 and AFWEX

    NASA Technical Reports Server (NTRS)

    Whiteman, D. N.; Evans, K. D.; DiGirolamo, P.; Demoz, B. B.; Turner, D.; Comstock, J.; Ismail, S.; Ferrare, R. A.; Browell, E. V.; Goldsmith, J. E. M.; Abshire, James B. (Technical Monitor)

    2002-01-01

    The NASA/GSFC Scanning Raman Lidar (SRL) was deployed to the Southern Great Plains CART site from September - December, 2000 and participated in two field campaigns devoted to comparisons of various water vapor measurement technologies and calibrations. These campaigns were the Water Vapor Intensive Operations Period 2000 (WVIOP2000) and the ARM FIRE Water Vapor Experiment (AFWEX). WVIOP2000 was devoted to validating water vapor measurements in the lower atmosphere while AFWEX had similar goals but for measurements in the upper troposphere. The SRL was significantly upgraded both optically and electronically prior to these field campaigns. These upgrades enabled the SRL to demonstrate the highest resolution lidar measurements of water vapor ever acquired during the nighttime and the highest S/N Raman lidar measurements of water vapor in the daytime; more than a factor of 2 increase in S/N versus the DOE CARL Raman Lidar. Examples of these new measurement capabilities along with comparisons of SRL and CARL, LASE, MPI-DIAL, in-situ sensors, radiosonde, and others will be presented. The profile comparisons of the SRL and CARL have revealed what appears to be an overlap correction or countrate correction problem in CARL. This may be involved in an overall dry bias in the precipitable water calibration of CARL with respect to the MWR of approx. 4%. Preliminary analysis indicates that the application of a temperature dependent correction to the narrowband Raman lidar measurements of water vapor improves the lidar/Vaisala radiosonde comparisons of upper tropospheric water vapor. Other results including the comparison of the first-ever simultaneous measurements from four water vapor lidar systems, a bore-wave event captured at high resolution by the SRL and cirrus cloud optical depth studies using the SRL and CARL will be presented at the meeting.

  2. 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.

  3. Investigating particle orientation in cirrus clouds by measuring backscattering phase matrices with lidar.

    PubMed

    Kaul, Bruno V; Samokhvalov, Ignatii V; Volkov, Sergei N

    2004-12-20

    The relation between the orientation of particles in ice-crystal clouds and backscattering phase matrices (BSPMs) is considered. Parameters characterizing the predominant orientation of particles in the azimuthal direction and in the horizontal position are presented. The parameters are expressed through BSPM elements. A technique for measuring BSPM elements with lidar is described. Examples of some measurements are presented along with a statistical generalization of the results from more than 400 BSPM measurements. It is found that the orientation of coarse particles with large diameters in an azimuthal direction and in a horizontal position is more probable than in a random direction. However, the orientation of large particles is often masked by small particles that are not subject to the effect of orienting factors. Thus the mean parameters characterizing the state of orientation of particles in clouds as a whole correspond to weak orientation. It is supposed that the orientation of particles in the azimuthal direction is caused by wind-velocity pulsations. PMID:15646781

  4. Height Distribution Between Cloud and Aerosol Layers from the GLAS Spaceborne Lidar in the Indian Ocean Region

    NASA Technical Reports Server (NTRS)

    Hart, William D.; Spinhirne, James D.; Palm, Steven P.; Hlavka, Dennis L.

    2005-01-01

    The Geoscience Laser Altimeter System (GLAS), a nadir pointing lidar on the Ice Cloud and land Elevation Satellite (ICESat) launched in 2003, now provides important new global measurements of the relationship between the height distribution of cloud and aerosol layers. GLAS data have the capability to detect, locate, and distinguish between cloud and aerosol layers in the atmosphere up to 40 km altitude. The data product algorithm tests the product of the maximum attenuated backscatter coefficient b'(r) and the vertical gradient of b'(r) within a layer against a predetermined threshold. An initial case result for the critical Indian Ocean region is presented. From the results the relative height distribution between collocated aerosol and cloud shows extensive regions where cloud formation is well within dense aerosol scattering layers at the surface. Citation: Hart, W. D., J. D. Spinhime, S. P. Palm, and D. L. Hlavka (2005), Height distribution between cloud and aerosol layers from the GLAS spaceborne lidar in the Indian Ocean region,

  5. 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 MMCR reflectivities were then merged with the WSR- 88D data to fill in the gaps during the heavy precipitation periods. This merged dataset provides a more complete radar reflectivity profile for studying

  6. 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.

  7. Toward Aboveground Biomass Estimation with RADAR, Lidar and Optical Remote Sensing Data in Southern Mexico

    NASA Astrophysics Data System (ADS)

    Urbazaev, M.; Thiel, C. J.; Schmullius, C.

    2014-12-01

    Information on the spatial distribution of aboveground biomass (AGB) over large areas is needed (1) for understanding and managing the processes involved in the carbon cycle, and (2) supporting international policies for climate change mitigation and adaption. Using remote sensing techniques it is possible to provide spatially explicit information of AGB from local to global scales. In this work we present the first results on the use of multi-sensor remote sensing data to estimate AGB over three test sites in southern Mexico. In order to develop a set of AGB retrieval algorithms, we firstly compared different SAR parameters (e.g. multi-polarized backscatter intensities and interferometric coherence) obtained from ALOS PALSAR sensor and Landsat imagery with field-based AGB estimates using empirical regressions and analyzed the relationships between them. The next steps of the work will be development of a two-stage up-scaling approach: firstly, to enlarge the cal/val data, we propose to estimate AGB along airborne LiDAR (from G-LiHT sensor) transects using field-based AGB and LiDAR height metrics. With LiDAR-based AGB we will then calibrate SAR parameters in a non-parametric model (e.g., randomForest) to create AGB maps over the study areas. An overall aim of the study is the analysis of capabilities and limitations of SAR data for AGB mapping and the investigation of the potential synergistic use of SAR, LiDAR and optical systems.The proposed monitoring tool will facilitate quantitative estimations in loss of carbon storage and support the selection of terrestrial (e.g. tropical dry forests, shrublands) sites for conservation priorities with high value for the national carbon budget.

  8. Application of Cloude's target decomposition theorem to polarimetric imaging radar data

    NASA Technical Reports Server (NTRS)

    Vanzyl, Jakob J.

    1993-01-01

    In this paper we applied Cloude's decomposition to imaging radar polarimetry. We show in detail how the decomposition results can guide the interpretation of scattering from vegetated areas. For multifrequency polarimetric radar measurements of a clear-cut area, the decomposition leads us to conclude that the vegetation is probably thin compared to even the C-band radar wavelength of 6 cm. For a frosted area, we notice an increased amount of even number of reflection scattering at P-band and L-band, probably the result of penetration through the coniferous canopy resulting in trunk-ground double reflection scattering. However, the scattering for the forested area is still dominated by scattering from randomly oriented cylinders. It is found that these cylinders are thicker than in the case of clear-cut areas, leading us to conclude that scattering from the branches probably dominates in this case.

  9. Additional development of remote sensing techniques for observing morphology, microphysics, and radiative properties of clouds and tests using a new, robust CO{sub 2} lidar. Final report

    SciTech Connect

    Eberhard, W.L.; Brewer, W.A.; Intrieri, J.M.

    1998-09-28

    A three-year project with a goal of advancing CO{sub 2} lidar technology and measurement techniques for cloud studies was successfully completed. An eyesafe, infrared lidar with good sensitivity and improved Doppler accuracy was designed, constructed, and demonstrated. Dual-wavelength operation was achieved. A major leap forward in robustness was demonstrated. CO{sub 2} lidars were operated as part of two Intensive Operations Periods at the Southern Great Plains CART site. The first used an older lidar and was intended primarily for measurement technique development. The second used the new lidar and was primarily a demonstration and evaluation of its performance. Progress was demonstrated in the development, evaluation, and application of measurement techniques using CO{sub 2} lidar.

  10. 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).

  11. Layers of quasi-horizontally oriented ice crystals in cirrus clouds observed by a two-wavelength polarization lidar.

    PubMed

    Borovoi, Anatoli; Balin, Yurii; Kokhanenko, Grigorii; Penner, Iogannes; Konoshonkin, Alexander; Kustova, Natalia

    2014-10-01

    Layers of quasi-horizontally oriented ice crystals in cirrus clouds are observed by a two-wavelength polarization lidar. These layers of thickness of several hundred meters are identified by three attributes: the backscatter reveals a sharp ridge while the depolarization ratio and color ratio become deep minima. These attributes have been justified by theoretical calculations of these quantities within the framework of the physical-optics approximation. PMID:25322032

  12. Polarimetric Radar Observations of Arctic Clouds: Signal Processing and First Results from the may 2013 Iop

    NASA Astrophysics Data System (ADS)

    Galletti, M.; Oue, M.; Verlinde, J.

    2013-12-01

    The ARM Climate Research Facility site at the North Slope of Alaska in Barrow provides polarimetric radar observations of Arctic clouds at X, Ka and W bands. During the May 2013 Scanning radar Intensive Observation Period, raw I and Q data were acquired with the X-SAPR and the Ka-W SACR for the purpose of validating existing, and testing new signal processing procedures specifically tailored for Arctic observations. The raw I and Q datasets were collected on May 3rd 2013 for the case of low-level boundary layer mixed-phase arctic clouds and on May 6th 2013 for the case of a synoptic low moving in from the west. http://www.arm.gov/campaigns/nsa2013nsasr The present paper describes the impact of signal processing procedures on the data, and establishes dual-polarization radar as a valuable tool for the microphysical characterization of ice clouds. In particular, the X-SAPR operates at STSR mode, making available differential reflectivity ZDR, copolar correlation coefficient ?hv, specific differential phase KDP and Degree of Polarization at Simultaneous Transmit DOPS. Low-level boundary layer mixed-phase Arctic clouds are characterized by layers of supercooled liquid water aloft, which present a stark polarimetric contrast with respect to the associated ice precipitation fallout. The ice particles falling from boundary layer Arctic clouds on May 2nd, 3rd and 4th 2013 (winds were very weak or absent) showed the remarkable property of being composed exclusively by large dendrites - fern-like, stellars, twelve-branched - indicating deposition as the main accretion mechanism. http://www.flickr.com/photos/michele_galletti/sets/72157633422079814/ Boundary Layer mixed-phase Arctic clouds provide an exceptional natural laboratory for the exploration of polarimetric signatures in presence of dendritic ice particles. The first-ever X-band analysis of differential reflectivity ZDR of mixed-phase Arctic clouds is presented in [1]. For the May 6th case, ice particle populations associated with frontal systems underwent more significant vertical mixing, and therefore more significant break-up and aggregation, with the overall result that ice particles possessed less geometrical symmetry, and consequently less prominent polarimetric contrast was detected by the radars. [1] Oue, Galletti, Verlinde "Observations of X-band differential reflectivity in Arctic mixed-phase clouds", submitted.

  13. Trajectory-Based Registration of 3d LIDAR Point Clouds Acquired with a Mobile Mapping System

    NASA Astrophysics Data System (ADS)

    Gressin, A.; Cannelle, B.; Mallet, C.; Papelard, J.-P.

    2012-07-01

    Thanks to a hybrid georeferencing unit coupling GNSS and IMU sensors, mobile mapping systems (MMS) with lidar sensors provide accurate 3D point clouds of the acquired areas, mainly urban cities. When dealing with several acquisitions of the same area with the same device, differences in the range of several tens of centimeters can be observed. Such degradation of the georeferencing accuracies are due to two main reasons: inertial drift and losses of GNSS signals in urban corridors. The purpose of this paper is therefore to correct these differences with an accurate ICP-based registration algorithm, and then to correct the MMS trajectory using these retrieved local transformation parameters.The trajectory loop information plays a key role for that purpose. We propose a four-step method starting from a 3D point cloud with overlapping parts, and the trajectory of the mobile mapping system. First, a polygonal approximation of the trajectory is computed in order to first divide the whole registration problem in local sub-issues. Secondly, we aim to find all the potential overlapping acquired areas between these segments using simple bounding box intersections. Thirdly, for each pair of overlapping areas, an efficient variant of the ICP algorithm is proposed to (1) prune cases where segments do not share point clouds of the same areas and (2) retrieve the transformation parameters, for real overlapping cases. Finally, all these transformations are linked together, and fed into a global distance compensation problem, allowing to adjust the MMS trajectories for several passages. As a conclusion, this method is successfully applied to data acquired over Paris (France) with the Stereopolis mobile mapping system.

  14. Different Applications of FORTRACC: From Convective Clouds to thunderstorms and radar fields

    NASA Astrophysics Data System (ADS)

    Morales, C.; Machado, L. A.

    2009-09-01

    The algorithm Forecasting and Tracking the Evolution of Cloud Clusters (ForTraCC), Vila et al. (2008), has been employed operationally in Brazil since 2005 to track and forecast the development of convective clouds. This technique depicts the main morphological features of the cloud systems and most importantly it reconstructs its entire life cycle. Based on this information, several relationships that use the area expansion and convective and stratiform fraction are employed to predict the life time duration and cloud area. Because of these features, the civil defense and power companies are using this information to mitigate the damages in the population. Further developments in FORTRACC included the integration of satellite rainfall retrievals, radar fields and thunderstorm initiation. These improvements try to address the following problems: a) most of the satellite rainfall retrievals do not take into account the life cycle stage that it is a key element on defining the rain area and rain intensity; b) by using the life cycle information it is possible to better predict the precipitation pattern observed in the radar fields; c) cloud signatures are associated to the development of systems that have lightning and no lightning activity. During the presentation, an overview of the different applications of FORTRACC will be presented including case studies and evaluation of the technique. Finally, the presentation will address how the users can have access to the algorithm to implement in their institute.

  15. Radar derived storm dynamics for cloud-resolving model evaluation and climate model parameterization development

    NASA Astrophysics Data System (ADS)

    Collis, S. M.; May, P. T.; Protat, A.; Fridlind, A. M.; Ackerman, A. S.; Williams, C. R.; Varble, A.; Zipser, E. J.

    2010-12-01

    The Tropical Warm Pool-International Cloud Experiment (TWP-ICE) was conducted in and around the US Department of Energy’s Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Darwin site during January and February 2006. The field program gathered observations that have been used for initializing and driving cloud-resolving models (CRMs, with periodic boundary conditions) and limited-area models (LAMs, with open boundary conditions) for submission to the model intercomparison study, which is organized by the ARM and GEWEX Cloud System Study (GCSS) programs. Measurements also included an extensive set of remotely sensed and in-situ quantities to evaluate model performance, assisting climate model parameterization development. For example, using a combination of operational Doppler radar and CPOL polartimetric research radar data vector winds have been retrieved in storms for part of the model intercomparison period. This presentation will outline the retrieval technique, show preliminary verification of the retrieved updraft intensities and showcase model-measurement comparison with output from the DHARMA cloud-resolving model focusing on vertical winds, a crucial aspect of simulated storm dynamics which exhibit a high degree of model to model variability. Initial comparison has most model updraft speeds substantially higher those retrieved from radar measurements. Investigations into the impact of sampling, scale differences and the cause for this discrepancy are ongoing as is the extension of comparisons to all CRM and LAM submissions. Details on the roll out of the American Recovery and Reinvestment Act funded precipitation radar infrastructure for ACRF and plans for geophysical retrievals from this new instrumentation will also be presented.

  16. Uncertainties in Ice-Sheet Altimetry from a Spaceborne 1064-nm Single-Channel Lidar Due to Undetected Thin Clouds

    NASA Technical Reports Server (NTRS)

    Yang, Yuekui; Marshak, Alexander; Varnai, Tamas; Wiscombe, Warren; Yang, Ping

    2010-01-01

    In support of the Ice, Cloud, and land Elevation Satellite (ICESat)-II mission, this paper studies the bias in surface-elevation measurements caused by undetected thin clouds. The ICESat-II satellite may only have a 1064-nm single-channel lidar onboard. Less sensitive to clouds than the 532-nm channel, the 1064-nm channel tends to miss thin clouds. Previous studies have demonstrated that scattering by cloud particles increases the photon-path length, thus resulting in biases in ice-sheet-elevation measurements from spaceborne lidars. This effect is referred to as atmospheric path delay. This paper complements previous studies in the following ways: First, atmospheric path delay is estimated over the ice sheets based on cloud statistics from the Geoscience Laser Altimeter System onboard ICESat and the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua. Second, the effect of cloud particle size and shape is studied with the state-of-the-art phase functions developed for MODIS cirrus- cloud microphysical model. Third, the contribution of various orders of scattering events to the path delay is studied, and an analytical model of the first-order scattering contribution is developed. This paper focuses on the path delay as a function of telescope field of view (FOV). The results show that reducing telescope FOV can significantly reduce the expected path delay. As an example, the average path delays for FOV = 167 microrad (a 100-m-diameter circle on the surface) caused by thin undetected clouds by the 1064-nm channel over Greenland and East Antarctica are illustrated.

  17. Augmented reality system using lidar point cloud data for displaying dimensional information of objects on mobile phones

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Lohani, B.

    2014-05-01

    Mobile augmented reality system is the next generation technology to visualise 3D real world intelligently. The technology is expanding at a fast pace to upgrade the status of a smart phone to an intelligent device. The research problem identified and presented in the current work is to view actual dimensions of various objects that are captured by a smart phone in real time. The methodology proposed first establishes correspondence between LiDAR point cloud, that are stored in a server, and the image t hat is captured by a mobile. This correspondence is established using the exterior and interior orientation parameters of the mobile camera and the coordinates of LiDAR data points which lie in the viewshed of the mobile camera. A pseudo intensity image is generated using LiDAR points and their intensity. Mobile image and pseudo intensity image are then registered using image registration method SIFT thereby generating a pipeline to locate a point in point cloud corresponding to a point (pixel) on the mobile image. The second part of the method uses point cloud data for computing dimensional information corresponding to the pairs of points selected on mobile image and fetch the dimensions on top of the image. This paper describes all steps of the proposed method. The paper uses an experimental setup to mimic the mobile phone and server system and presents some initial but encouraging results

  18. Active laser radar (lidar) for measurement of corresponding height and reflectance images

    NASA Astrophysics Data System (ADS)

    Froehlich, Christoph; Mettenleiter, M.; Haertl, F.

    1997-08-01

    For the survey and inspection of environmental objects, a non-tactile, robust and precise imaging of height and depth is the basis sensor technology. For visual inspection,surface classification, and documentation purposes, however, additional information concerning reflectance of measured objects is necessary. High-speed acquisition of both geometric and visual information is achieved by means of an active laser radar, supporting consistent 3D height and 2D reflectance images. The laser radar is an optical-wavelength system, and is comparable to devices built by ERIM, Odetics, and Perceptron, measuring the range between sensor and target surfaces as well as the reflectance of the target surface, which corresponds to the magnitude of the back scattered laser energy. In contrast to these range sensing devices, the laser radar under consideration is designed for high speed and precise operation in both indoor and outdoor environments, emitting a minimum of near-IR laser energy. It integrates a laser range measurement system and a mechanical deflection system for 3D environmental measurements. This paper reports on design details of the laser radar for surface inspection tasks. It outlines the performance requirements and introduces the measurement principle. The hardware design, including the main modules, such as the laser head, the high frequency unit, the laser beam deflection system, and the digital signal processing unit are discussed.the signal processing unit consists of dedicated signal processors for real-time sensor data preprocessing as well as a sensor computer for high-level image analysis and feature extraction. The paper focuses on performance data of the system, including noise, drift over time, precision, and accuracy with measurements. It discuses the influences of ambient light, surface material of the target, and ambient temperature for range accuracy and range precision. Furthermore, experimental results from inspection of buildings, monuments and industrial environments are presented. The paper concludes by summarizing results achieved in industrial environments and gives a short outlook to future work.

  19. A Climatology of Midlatitude Continental Clouds from the ARM SGP Central Facility. Part II: Cloud Fraction and Surface Radiative Forcing

    E-print Network

    Dong, Xiquan

    (SCF) are analyzed to determine the monthly and hourly variations of cloud fraction and radiative lidar­radar measurements. Shortwave (SW) and longwave (LW) fluxes are derived from up- and down diurnal cycle, clouds deplete the amount of surface insolation more than they add to the downwelling LW

  20. Automated Detection of Geomorphic Features in LiDAR Point Clouds of Various Spatial Density

    NASA Astrophysics Data System (ADS)

    Dorninger, Peter; Székely, Balázs; Zámolyi, András.; Nothegger, Clemens

    2010-05-01

    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 resolution (some ten points per square meter) compared to terrestrial laser scanning. Hence, terrestrial laser scanning is preferably used for precise data acquisition of limited areas such as landslides or steep structures, while airborne laser scanning is well suited for the acquisition of topographic data of huge areas or even country wide. Laser scanners acquire more or less homogeneously distributed point clouds. These points represent natural objects like terrain and vegetation and artificial objects like buildings, streets or power lines. Typical products derived from such data are geometric models such as digital surface models representing all natural and artificial objects and digital terrain models representing the geomorphic topography only. As the LiDAR technology evolves, the amount of data produced increases almost exponentially even in smaller projects. This means a considerable challenge for the end user of the data: the experimenter has to have enough knowledge, experience and computer capacity in order to manage the acquired dataset and to derive geomorphologically relevant information from the raw or intermediate data products. Additionally, all this information might need to be integrated with other data like orthophotos. In all theses cases, in general, interactive interpretation is necessary to determine geomorphic structures from such models to achieve effective data reduction. There is little support for the automatic determination of characteristic features and their statistical evaluation. From the lessons learnt from automated extraction and modeling of buildings (Dorninger & Pfeifer, 2008) we expected that similar generalizations for geomorphic features can be achieved. Our aim is to recognize as many features as possible from the point cloud in the same processing loop, if they can be geometrically described with appropriate accuracy (e.g., as a plane). For this, we propose to apply a segmentation process allowing determining connected, planar structures within a surface represented by a point cloud. It is based on a robust determination of local tangential planes for all points acquired (Nothegger & Dorninger, 2009). It assumes that for points, belonging to a distinct planar structure, similar tangential planes can be determined. In passing, points acquired at continuous such as vegetation can be identified and eliminated. The plane parameters are used to define a four-dimensional feature space which is used to determine seed-clusters globally for the whole are of interest. Starting from these seeds, all points defining a connected, planar region are assigned to a segment. Due to the design of the algorithm, millions of input points can be processed with acceptable processing time on standard computer systems. This allows for processing geomorphically representative areas at once. For each segment, numerous parameter are derived which can be used for further exploitation. These are, for example, location, area, aspect, slope, and roughness. To prove the applicability of our method for automated geomorphic terrain analysis, we used terrestrial and airborne laser scanning data, acquired at two locations. The data of the Doren landslide located in Vorarlberg, Austria, was acquired by a terrestrial Riegl LS-321 laser scanner in 2008, by a terrestrial Riegl LMS-Z420i laser scanner in 2009, and additionally by three airborne LiDAR measurement campaigns, organized by the Landesvermessungsamt Vorarlberg, Feldkirch, in 2003, 2006, and 2007. The measurement distance of the terrestrial measurements was considerably varying considerably because of the various base points that were neede

  1. Continuous Profiles of Cloud Microphysical Properties for the Fixed Atmospheric Radiation Measurement Sites

    SciTech Connect

    Jensen, M; Jensen, K

    2006-06-01

    The Atmospheric Radiation Measurement (ARM) Program defined a specific metric for the third quarter of Fiscal Year 2006 to produce and refine a one-year continuous time series of cloud microphysical properties based on cloud radar measurements for each of the fixed ARM sites. To accomplish this metric, we used a combination of recently developed algorithms that interpret radar reflectivity profiles, lidar backscatter profiles, and microwave brightness temperatures into the context of the underlying cloud microphysical structure.

  2. 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.

  3. 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.

  4. Application technology of micro pulse lidar

    NASA Astrophysics Data System (ADS)

    Xu, Yan-ming; Tong, Shou-feng; Jia, Yu-guang

    2013-09-01

    With the constant exploration to the atmosphere and the attention to the air quality of the living environment, the applications of micro-pulse lidar are more and more important. Micro Pulse Lidar can be used to observe the distribution of atmospheric aerosol and analyse structure, spatial and temporal evolution of the aerosol. The paper gives the introduction about the reference of micro-pulse lidar which is researched in the laboratory. Through the precision optical design, the blind area of Micro Pulse Lidar can be less than 45m. The portable requirement in the structure is implemented. The software function of micro-pulse lidar includes: extinction coefficiency monitoring, tracking the pollution source, distinguish spherical particular (fog) from no-sphercial particular(ice or dust)? simulating the Mass concentration, scanning date integrating with GIS, and so on. The average height of the boundary layer measured by micro-pulse lidar. The relationship between the cloud height and aerosol echo signal can be seen from the data received from micro-pulse lidar and the peak is at 6KM. By acquiring corresponding visibility values from probing different heights, a conclusion can be drawn that visibility and extinction coeffcient is inversely proportionate. Take a 24 hour day as a circle and divide it into several time periods. An atmosphere evolution diagram of the backscattering of the height of atmospheric boundary layer and the atmospheric aerosol particles can be derived according to the difference in sun radiation. Information like structure and the evolution characteristics of atmospheric boundary layer, cloud height, cloud cover structure, atmospheric visibility and space particles obtained by the laser radar detection provides a basis for the establishment of the correct atmospheric model. At the same time because lidar can monitor the emissions of industrial soot and detect the law of diffusion of environmental pollutants of the sky over cities, it is of great significance to the environmental monitoring of the atmosphere and atmospheric science research.

  5. Microphysical properties of the November 26 cirrus cloud retrieved by Doppler radar/IR radiometer technique

    NASA Technical Reports Server (NTRS)

    Matrosov, Sergey Y.; Kropfli, Robert A.; Orr, Brad W.; Snider, Jack B.

    1993-01-01

    Gaining information about cirrus cloud microphysics requires development of remote sensing techniques. In an earlier paper. Matrosov et al. (1992) proposed a method to estimate ice water path (IWP) (i.e., vertically integrated ice mass content IMC) and characteristic particle size averaged through the cloud from combined groundbased measurements of radar reflectivities and IR brightness temperatures of the downwelling thermal radiation in the transparency region of 10-12 mu m. For some applications, the vertically averaged characteristic particle sizes and IWP could be the appropriate information to use. However, vertical profiles of cloud microphysical parameters can provide a better understanding of cloud structure and development. Here we describe a further development of the previous method by Matrosov et al. (1992) for retrieving vertical profiles of cirrus particle sizes and IMC rather than their vertically averaged values. In addition to measurements of radar reflectivities, the measurements of Doppler velocities are used in the new method. This provides us with two vertical profiles of measurements to infer two vertical profiles of unknowns, i.e., particle characteristic sizes and IMC. Simultaneous measurements of the IR brightness temperatures are still needed to resolve an ambiguity in particle size-fall velocity relationships.

  6. 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; 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 Hemispherical Sky – Range Height Indicator 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.

  7. 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.

  8. Extraction of Features from High-resolution 3D LiDaR Point-cloud Data

    NASA Astrophysics Data System (ADS)

    Keller, P.; Kreylos, O.; Hamann, B.; Kellogg, L. H.; Cowgill, E. S.; Yikilmaz, M. B.; Hering-Bertram, M.; Hagen, H.

    2008-12-01

    Airborne and tripod-based LiDaR scans are capable of producing new insight into geologic features by providing high-quality 3D measurements of the landscape. High-resolution LiDaR is a promising method for studying slip on faults, erosion, and other landscape-altering processes. LiDaR scans can produce up to several billion individual point returns associated with the reflection of a laser from natural and engineered surfaces; these point clouds are typically used to derive a high-resolution digital elevation model (DEM). Currently, there exist only few methods that can support the analysis of the data at full resolution and in the natural 3D perspective in which it was collected by working directly with the points. We are developing new algorithms for extracting features from LiDaR scans, and present method for determining the local curvature of a LiDaR data set, working directly with the individual point returns of a scan. Computing the curvature enables us to rapidly and automatically identify key features such as ridge-lines, stream beds, and edges of terraces. We fit polynomial surface patches via a moving least squares (MLS) approach to local point neighborhoods, determining curvature values for each point. The size of the local point neighborhood is defined by a user. Since both terrestrial and airborne LiDaR scans suffer from high noise, we apply additional pre- and post-processing smoothing steps to eliminate unwanted features. LiDaR data also captures objects like buildings and trees complicating greatly the task of extracting reliable curvature values. Hence, we use a stochastic approach to determine whether a point can be reliably used to estimate curvature or not. Additionally, we have developed a graph-based approach to establish connectivities among points that correspond to regions of high curvature. The result is an explicit description of ridge-lines, for example. We have applied our method to the raw point cloud data collected as part of the GeoEarthScope B-4 project on a section of the San Andreas Fault (Segment SA09). This section provides an excellent test site for our method as it exposes the fault clearly, contains few extraneous structures, and exhibits multiple dry stream-beds that have been off-set by motion on the fault.

  9. Cloud radar with hybrid mode towards estimation of shape and orientation of ice crystals

    NASA Astrophysics Data System (ADS)

    Myagkov, A.; Seifert, P.; Bauer-Pfundstein, M.; Wandinger, U.

    2015-09-01

    This paper is devoted to the experimental quantitative characterization of the shape and orientation distribution of ice particles in clouds. The characterization is based on measured and modeled elevation dependencies of the polarimetric parameters differential reflectivity and correlation coefficient. The polarimetric data is obtained using a newly developed 35 GHz cloud radar MIRA-35 with hybrid polarimetric configuration and scanning capabilities. The full procedure chain of the technical implementation and the realization of the setup of the hybrid-mode cloud radar for the shape determination are presented. This includes the description of phase adjustments in the transmitting paths, the introduction of the general data processing scheme, correction of the data for the differences of amplifications and electrical path lengths in the transmitting and receiving channels, the rotation of the polarization basis by 45°, the correction of antenna effects on polarimetric measurements, the determination of spectral polarimetric variables, and the formulation of a scheme to increase the signal-to-noise ratio. Modeling of the polarimetric variables is based on existing back-scattering models assuming the spheroidal representation of cloud scatterers. The parameters retrieved from the model are polarizability ratio and degree of orientation, which can be assigned to certain particle orientations and shapes. The developed algorithm is applied to a measurement of the hybrid-mode cloud radar taken on 20 October 2014 in Cabauw, the Netherlands, in the frame of the ACCEPT (Analysis of the Composition of Clouds with Extended Polarization Techniques) campaign. The case study shows the retrieved polarizability ratio and degree of orientation of ice particles for a cloud system of three cloud layers at different heights. Retrieved polarizability ratios are 0.43, 0.85, and 1.5 which correspond to oblate, quasi-spherical, and columnar ice particles, respectively. It is shown that the polarizability ratio is useful for the detection of aggregation/riming processes. The orientation of oblate and prolate particles is estimated to be close to horizontal while quasi-spherical particles were found to be more randomly oriented.

  10. Airborne lidar observations in the wintertime Arctic stratosphere: Polar stratospheric clouds

    SciTech Connect

    Browell, E.V.; Ismail, S.; Carter, A.F.; Higdon, N.S. ); Butler, C.F.; Robinette, P.A. ); Toon, O.B. ); Schoeberl, M.R. ); Tuck, A.F. )

    1990-03-01

    Polar stratospheric cloud (PSC) distributions in the wintertime Arctic stratosphere and their optical characteristics were measured with a multi-wavelength airborne lidar system as part of the 1989 Airborne Arctic Stratospheric Expedition. PSCs were observed on 10 flights between January 6 and February 2, 1989, into the polar vortex. The PSCs were found in the 14-27 km altitude range in regions where the temperatures were {le}195 K. Two types of aerosols with different optical characteristics (Types 1a and 1b) were observed in PSCs thought to be composed of nitric acid trihydrate. Type 1a PSCs typically exhibited low scattering ratios (1.2-1.5) and high aerosol depolarizations (30-50%) at 603 nm, while Type 1b PSCs had higher scattering ratios (3-8) and lower aerosol depolarizations (0.5-2.5%). Water ice PSCs (Type 2) were observed to have high scattering ratios (>10) and high aerosol depolarizations (>10%) at temperatures {le}190 K.

  11. Lidar observations of polar stratospheric clouds (PSCs): Implications for the formation of type Ia PSCs

    SciTech Connect

    Tabazadeh, A.; Toon, O.B.

    1996-10-01

    DC-8 lidar observations of Type I PSCs obtained during AASE I on January 11, 1989 are presented. On this day, Type I PSCs were observed over a vast area in the altitude range of about 16 to 23 km between 73{degrees}N and the north pole. Three types of particles were seen by the DC-8 on January 11. The main body of the cloud was composed of large nonspherical particles classed as Type Ia PSCs (nitric acid trihydrate, NAT). The other two types, which occurred with about equal frequency, were composed of either small spherical particles classed as Type Ib PSCs (ternary solutions of H{sub 2}SO{sub 4}/HNO{sub 3}/H{sub 2}O) or small nonspherical particles classed as Type Ic PSCs (probably composed of a dilute solid solution of HNO{sub 3}/H{sub 2}O). The relationship between the temperature histories of air parcels for the locations indicated above and the physical characteristics of the observed Type I PSCs are used to infer a plausible mechanism for the nucleation of NAT particles in the stratosphere. The significance of NAT particle formation to the denitrification process in the Arctic is also discussed.

  12. Fast Occlusion and Shadow Detection for High Resolution Remote Sensing Image Combined with LIDAR Point Cloud

    NASA Astrophysics Data System (ADS)

    Hu, X.; Li, X.

    2012-08-01

    The orthophoto is an important component of GIS database and has been applied in many fields. But occlusion and shadow causes the loss of feature information which has a great effect on the quality of images. One of the critical steps in true orthophoto generation is the detection of occlusion and shadow. Nowadays LiDAR can obtain the digital surface model (DSM) directly. Combined with this technology, image occlusion and shadow can be detected automatically. In this paper, the Z-Buffer is applied for occlusion detection. The shadow detection can be regarded as a same problem with occlusion detection considering the angle between the sun and the camera. However, the Z-Buffer algorithm is computationally expensive. And the volume of scanned data and remote sensing images is very large. Efficient algorithm is another challenge. Modern graphics processing unit (GPU) is much more powerful than central processing unit (CPU). We introduce this technology to speed up the Z-Buffer algorithm and get 7 times increase in speed compared with CPU. The results of experiments demonstrate that Z-Buffer algorithm plays well in occlusion and shadow detection combined with high density of point cloud and GPU can speed up the computation significantly.

  13. Time correlations and 1/f behavior in backscattering radar reflectivity measurements from cirrus cloud ice fluctuations

    E-print Network

    K. Ivanova; T. P. Ackerman; E. E. Clothiaux; P. Ch. Ivanov; H. E. Stanley; M. Ausloos

    2003-01-14

    The state of the atmosphere is governed by the classical laws of fluid motion and exhibits correlations in various spatial and temporal scales. These correlations are crucial to understand the short and long term trends in climate. Cirrus clouds are important ingredients of the atmospheric boundary layer. To improve future parameterization of cirrus clouds in climate models, it is important to understand the cloud properties and how they change within the cloud. We study correlations in the fluctuations of radar signals obtained at isodepths of winter and fall cirrus clouds. In particular we focus on three quantities: (i) the backscattering cross-section, (ii) the Doppler velocity and (iii) the Doppler spectral width. They correspond to the physical coefficients used in Navier Stokes equations to describe flows, i.e. bulk modulus, viscosity, and thermal conductivity. In all cases we find that power-law time correlations exist with a crossover between regimes at about 3 to 5 min. We also find that different type of correlations, including 1/f behavior, characterize the top and the bottom layers and the bulk of the clouds. The underlying mechanisms for such correlations are suggested to originate in ice nucleation and crystal growth processes.

  14. 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.

  15. Classification of Particle Shapes from Lidar Depolarization Ratios in Convective Ice Clouds Compared to in situ Observations During CRYSTAL-FACE

    NASA Technical Reports Server (NTRS)

    Noel, Vincent; Winker, David; McGill, Matthew; Lawson, Paul

    2004-01-01

    This manuscript describes a method to class@ cirrus cloud ice particle shape using lidar depolarization measurements as a basis for segregating different particle shape regimes. Measurements from the ER-2 Cloud Physics Lidar (CPL) system during CRYSTAL-FACE provide the basis for this work. While the CPL onboard the ER-2 aircraft was providing remote sensing measurements of cirrus clouds, the Cloud Particle Imager (CPI) onboard the WB-57 aircraft was flying inside those same clouds to sample particle sizes. The results of classifying particle shapes using the CPL data are compared to the in situ measurements made using the CPI , and there is found to be good agreement between the particle shape inferred from the CPL data and that actually measured by the CPI. If proven practical, application of this technique to spaceborne observations could lead to large-scale classification of cirrus cloud particle shapes.

  16. Breaking Kelvin-Helmholtz waves and cloud-top entrainment as revealed by K-band Doppler radar

    NASA Technical Reports Server (NTRS)

    Martner, Brooks E.; Ralph, F. Martin

    1993-01-01

    Radars have occasionally detected breaking Kelvin-Helmholtz (KH) waves under clear-air conditions in the atmospheric boundary layer and in the free troposphere. However, very few direct measurements of such waves within clouds have previously been reported and those have not clearly documented wave breaking. In this article, we present some of the most detailed and striking radar observations to date of breaking KH waves within clouds and at cloud top and discuss their relevance to the issue of cloud-top entrainment, which is believed to be important in convective and stratiform clouds. Aircraft observations reported by Stith suggest that vortex-like circulations near cloud top are an entrainment mechanism in cumuliform clouds. Laboratory and modeling studies have examined possibility that KH instability may be responsible for mixing at cloud top, but direct observations have not yet been presented. Preliminary analyses shown here may help fill this gap. The data presented in this paper were obtained during two field projects in 1991 that included observations from the NOAA Wave Propagation Laboratory's K-band Doppler radar (wavelength = 8.7 mm) and special rawinsonde ascents. The sensitivity (-30 dBZ at 10 km range), fine spatial resolution (375-m pulse length and 0.5 degrees beamwidth), velocity measurement precision (5-10 cm s-1), scanning capability, and relative immunity to ground clutter make it sensitive to non-precipitating and weakly precipitating clouds, and make it an excellent instrument to study gravity waves in clouds. In particular, the narrow beam width and short pulse length create scattering volumes that are cylinders 37.5 m long and 45 m (90 m) in diameter at 5 km (10 km) range. These characteristics allow the radar to resolve the detailed structure in breaking KH waves such as have been seen in photographic cloud images.

  17. Detection of potentially hazardous convective clouds with a dual-polarized C-band radar

    NASA Astrophysics Data System (ADS)

    Adachi, A.; Kobayashi, T.; Yamauchi, H.; Onogi, S.

    2013-04-01

    A method for forecasting very short-term rainfall to detect potentially hazardous convective cloud that produces heavy local rainfall was developed using actual volumetric C-band polarimetric radar data. Because the rainfall estimation algorithm used in this method removed the effect of ice particles based on polarimetric measurements, it was immune to the high reflectivity associated with hail. The reliability of the algorithm was confirmed by comparing the rainfall rate estimated from the polarimetric radar measurements at the lowest elevation angle with that obtained from an optical disdrometer on the ground. The rainfall rate estimated from polarimetric data agreed well with the results obtained from the disdrometer, and was much more reliable than results derived from reflectivity alone. Two small cumulus cells were analyzed, one of which developed and later produced heavy rainfall, whereas the other did not. Observations made by polarimetric radar with a volumetric scan revealed that a high vertical maximum intensity of rainfall rate and a vertical area of enhanced differential reflectivity extending above the freezing level, often termed a high ZDR column, were clearly formed about 10 min prior to the onset of heavy rainfall on the ground. The onset time of the heavy rainfall could be estimated in advance from the polarimetric data, which agreed fairly well with observations. These polarimetric characteristics were not observed for the cumulus cell that did not produce heavy rainfall. The results suggest that both the vertical maximum intensity of the rainfall rate and a high ZDR column, estimated from polarimetric measurements, can be used to identify potentially hazardous clouds. Furthermore, this study shows that polarimetric radar measurements with high spatial and temporal resolutions are invaluable for disaster reduction.

  18. Detection of potentially hazardous convective clouds with a dual-polarized C-band radar

    NASA Astrophysics Data System (ADS)

    Adachi, A.; Kobayashi, T.; Yamauchi, H.; Onogi, S.

    2013-10-01

    A method for forecasting very short-term rainfall to detect potentially hazardous convective cloud that produces heavy local rainfall was developed using actual volumetric C-band polarimetric radar data. Because the rainfall estimation algorithm used in this method removed the effect of ice particles based on polarimetric measurements, it was immune to the high reflectivity associated with hail. The reliability of the algorithm was confirmed by comparing the rainfall rate estimated from the polarimetric radar measurements at the lowest elevation angle with that obtained from optical disdrometers on the ground. The rainfall rate estimated from polarimetric data agreed well with the results obtained from the disdrometers, and was much more reliable than results derived from reflectivity alone. Two small cumulus cells were analyzed, one of which developed and later produced heavy rainfall, whereas the other did not. Observations made by polarimetric radar with a volumetric scan revealed that a high vertical maximum intensity of rainfall rate and a vertical area of enhanced differential reflectivity extending above the freezing level, often termed a high ZDR column, were clearly formed about 10 min prior to the onset of heavy rainfall on the ground. The onset time of the heavy rainfall could be estimated in advance from the polarimetric data, which agreed fairly well with observations. These polarimetric characteristics were not observed for the cumulus cell that did not produce heavy rainfall. The results suggest that both the vertical maximum intensity of the rainfall rate and a high ZDR column, estimated from polarimetric measurements, can be used to identify potentially hazardous clouds. Furthermore, this study shows that polarimetric radar measurements with high spatial and temporal resolutions are invaluable for disaster reduction.

  19. 3D Observations of Marine Stratocumulus Structure and Dynamics at the Azores Using a Scanning Cloud Radar

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    The US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility recently upgraded its infrastructure at the fixed and mobile sites by adding scanning cloud and precipitation radars of frequencies ranging from 5 to 94 GHz. The first scanning ARM 94-GHz radar was deployed for a short period of 2 months (October-November 2009) on Graciosa Island, Azores as part of the ARM Mobile Facility (AMF) deployment to support the Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) field campaign (www.arm.gov/sites/amf/grw). Several scan strategies were tested during the scanning cloud radar deployment. One of these strategies is the Cross Wind Range Height Indicator (CW-RHI) scan that consist of keeping a constant azimuth oriented perpendicular to the mean wind direction at the cloud level and operating scans with changing elevations from horizon to horizon passing over the radar location for a duration of one continuous hour. This unique scan strategy allows to slice clouds entirely as they move over time above the radar. Then using the wind magnitude and direction, it is possible to convert time to along-wind length and thus reconstruct the complete 3D cloud structure. Cross wind measurements of all Doppler moments are reported in radar spherical coordinates that can be transform to Cartesian coordinate system to simplify result analysis using an adaptive gridding algorithms. The raw observed Doppler velocities are quality controlled and corrected for folding. Then, the Doppler velocities are corrected for the horizontal wind contribution and the effect of the viewing angle. The resulting information provide 3D observations of the vertical component of the Doppler velocity in 3D and can be used to describe for the first time the 3D structure of large eddies in marine stratocumulus clouds at scales ranging from 50 m to 5km across.

  20. Temporal and structural evolution of a tropical monsoon cloud system: A case study using X-band radar observations

    NASA Astrophysics Data System (ADS)

    Kumar Das, Subrata; Deshpande, Sachin M.; Shankar Das, Siddarth; Konwar, Mahen; Chakravarty, Kaustav; Kalapureddy, Madhu Chandra Reddy

    2015-10-01

    A mobile X-band (~9.535 GHz) dual-polarization Doppler weather radar system was operated at a tropical site Pune (18.5386°N, 73.8089°E, 582 m AMSL) by the Indian Institute of Tropical Meteorology, Pune, India for observing monsoon clouds. The measurement site was on the leeward (eastern) side of the Western Ghats (WG). This study focuses on the horizontal and vertical structure of monsoon precipitating clouds and its temporal evolution as observed by the X-band radar on August 27, 2011. The radar reflectivity factor (Z, dBZ) is used as a proxy for measure of intensity of cloud system. Result shows that the radar reflectivity has a strong temporal variation in the vertical, with a local peak occurring in the afternoon hours. Relatively shallow structure during the late night and early morning hours is noticed. The observed cloud tops were reached up to 8 km heights with reflectivity maxima of about 35 dBZ at ?5 km. The spatial and vertical evolution of radar reflectivity is consistent with the large-scale monsoon circulation. The variations in the outgoing longwave radiation (OLR) from the Kalpana-1 satellite and vertical velocity and cloud-mixing ratio from the Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis data are also analyzed. As direct observations of clouds using radars are sparse over the Indian region, the results presented here would be useful to understand the processes related to cloud and precipitation formation in the tropical environment.

  1. A 19-Month Record of Marine AerosolCloudRadiation Properties Derived from DOE ARM Mobile Facility Deployment at the Azores. Part I: Cloud Fraction

    E-print Network

    Dong, Xiquan

    . The annual means of total CF and single-layered low, middle, and high CFs derived from ARM radar and lidar. Diurnal cycles for both total and low CFs were stronger during summer than during winter. The CFs clouds associated with midlatitude cyclones. The seasonal variations of cloud heights and thickness

  2. Building Change Detection from LIDAR Point Cloud Data Based on Connected Component Analysis

    NASA Astrophysics Data System (ADS)

    Awrangjeb, M.; Fraser, C. S.; Lu, G.

    2015-08-01

    Building data are one of the important data types in a topographic database. Building change detection after a period of time is necessary for many applications, such as identification of informal settlements. Based on the detected changes, the database has to be updated to ensure its usefulness. This paper proposes an improved building detection technique, which is a prerequisite for many building change detection techniques. The improved technique examines the gap between neighbouring buildings in the building mask in order to avoid under segmentation errors. Then, a new building change detection technique from LIDAR point cloud data is proposed. Buildings which are totally new or demolished are directly added to the change detection output. However, for demolished or extended building parts, a connected component analysis algorithm is applied and for each connected component its area, width and height are estimated in order to ascertain if it can be considered as a demolished or new building part. Finally, a graphical user interface (GUI) has been developed to update detected changes to the existing building map. Experimental results show that the improved building detection technique can offer not only higher performance in terms of completeness and correctness, but also a lower number of undersegmentation errors as compared to its original counterpart. The proposed change detection technique produces no omission errors and thus it can be exploited for enhanced automated building information updating within a topographic database. Using the developed GUI, the user can quickly examine each suggested change and indicate his/her decision with a minimum number of mouse clicks.

  3. Balloon-borne and Raman lidar observations of Asian dust and cirrus cloud properties over Tsukuba, Japan

    NASA Astrophysics Data System (ADS)

    Sakai, Tetsu; Orikasa, Narihiro; Nagai, Tomohiro; Murakami, Masataka; Tajiri, Takuya; Saito, Atsushi; Yamashita, Katsuya; Hashimoto, Akihiro

    2014-03-01

    The vertical distributions of the microphysical and optical properties of tropospheric aerosols and cirrus cloud were measured using an instrumented balloon and a ground-based Raman lidar over Tsukuba, Japan (36°N, 140°E), during the Asian dust events on 9 and 21 May 2007 to investigate the influence of Asian mineral dust on ice cloud formation in the upper troposphere. The instrumented balloon measured the particle size distribution, ice crystal images, dew/frost point, relative humidity, and temperature. The Raman lidar measured the particle backscattering and extinction coefficients and the depolarization ratio at a wavelength of 532 nm. The results of the balloon measurements showed that supermicrometer (0.7 to 2.8 µm in optical-equivalent radius) dust particles and ice crystals (10 to 400 µm in maximum dimension) were present in the upper troposphere (8 to 12 km in altitude), with number concentrations varying from 5 × 10-3 to 0.6 cm-3 for dust and from 5 × 10-3 to 0.15 cm-3 for ice crystals. The Raman lidar measurement indicated that the particle depolarization ratios were 15 to 35% in the altitude range of 6 to 12 km, indicating the predominance of nonspherical particles in the region. The temperature ranged from -33 to -63°C, and the relative humidity with respect to ice (RHi), estimated from the total (vapor plus condensate) water content obtained with the Snow White hygrometer in the cloud, was 130% at maximum on 9 May, which was close to the activation point of Asian mineral dust as ice nuclei to form ice crystals.

  4. Using Doppler spectra to separate hydrometeor populations and analyze ice precipitation in multilayered mixed-phase clouds

    SciTech Connect

    Rambukkange, Mahlon P.; Verlinde, J.; Eloranta, E. W.; Flynn, Connor J.; Clothiaux, Eugene E.

    2011-01-31

    Multimodality of cloud radar Doppler spectra is used to partition cloud particle phases and to separate distinct ice populations in the radar sample volume, thereby facilitating analysis of individual ice showers in multilayered mixed-phase clouds. A 35-GHz cloud radar located at Barrow, Alaska, during the Mixed-Phase Arctic Cloud Experiment collected the Doppler spectra. Data from a pair of collocated depolarization lidars confirmed the presence of two liquid cloud layers reported in this study. Surprisingly, both of these cloud layers were embedded in ice precipitation yet maintained their liquid. Our spectral separation of the ice precipitation yielded two distinct ice populations: ice initiated within the two liquid cloud layers and ice precipitation formed in higher cloud layers. Comparisons of ice fall velocity versus radar reflectivity relationships derived for distinct showers reveal that a single relationship might not properly represent the ice showers during this period.

  5. Observations of tornadoes and wall clouds with a portable FM-CW Doppler radar: 1989--1990 results

    SciTech Connect

    Bluestein, H.B. . School of Meteorology); Unruh, W.P. )

    1990-01-01

    The purpose of this paper is to report on our progress using a portable, 1 W,FM (frequency modulated)-CW (continuous wave) Doppler radar developed at the Los Alamos National Laboratory (LANL), to make measurements of the wind field in tornadoes and wall clouds along with simultaneous visual documentation. Results using a CW version of the radar in 1987--1988 are given in Bluestein and Unruh (1989). 18 refs., 2 figs., 1 tab.

  6. Comparison of in-situ Electric Field and Radar Derived Parameters for Stratiform Clouds in Central Florida

    NASA Astrophysics Data System (ADS)

    Bateman, M.; Mach, D.; Lewis, S.; Dye, J.; Defer, E.; Grainger, C.; Willis, P.; Christian, H.; Merceret, F.

    2003-12-01

    Airborne measurements of electric fields and particle microphysics were made during a field program at NASA's Kennedy Space Center. The aircraft, a Cessna Citation II jet operated by the University of North Dakota, carried six rotating-vane style electric field mills, several microphysics instruments, and thermodynamic instruments. In addition to the aircraft measurements, we also have data from both the Eastern Test Range WSR-74C (Patrick AFB) and the U.S. National Weather Service WSR-88D radars (primarily Melbourne, FL). One specific goal of this program was to try to develop a radar-based rule for estimating the hazard that an in-cloud electric field would present to a vehicle launched into the cloud. Based on past experience, and our desire to quantify the mixed-phase region of the cloud in question, we have assessed several algorithms for integrating radar reflectivity data in and above the mixed-phase region as a proxy for electric field. A successful radar proxy is one that can accurately predict the presence or absence of significant electric fields. We have compared various proxies with the measured in-cloud electric field strength in an attempt to develop a radar rule for assessing launch hazard. Assessment of the best proxy is presented.

  7. A Framework for Applying Point Clouds Grabbed by Multi-Beam LIDAR in Perceiving the Driving Environment.

    PubMed

    Liu, Jian; Liang, Huawei; Wang, Zhiling; Chen, Xiangcheng

    2015-01-01

    The quick and accurate understanding of the ambient environment, which is composed of road curbs, vehicles, pedestrians, etc., is critical for developing intelligent vehicles. The road elements included in this work are road curbs and dynamic road obstacles that directly affect the drivable area. A framework for the online modeling of the driving environment using a multi-beam LIDAR, i.e., a Velodyne HDL-64E LIDAR, which describes the 3D environment in the form of a point cloud, is reported in this article. First, ground segmentation is performed via multi-feature extraction of the raw data grabbed by the Velodyne LIDAR to satisfy the requirement of online environment modeling. Curbs and dynamic road obstacles are detected and tracked in different manners. Curves are fitted for curb points, and points are clustered into bundles whose form and kinematics parameters are calculated. The Kalman filter is used to track dynamic obstacles, whereas the snake model is employed for curbs. Results indicate that the proposed framework is robust under various environments and satisfies the requirements for online processing. PMID:26404290

  8. A Framework for Applying Point Clouds Grabbed by Multi-Beam LIDAR in Perceiving the Driving Environment

    PubMed Central

    Liu, Jian; Liang, Huawei; Wang, Zhiling; Chen, Xiangcheng

    2015-01-01

    The quick and accurate understanding of the ambient environment, which is composed of road curbs, vehicles, pedestrians, etc., is critical for developing intelligent vehicles. The road elements included in this work are road curbs and dynamic road obstacles that directly affect the drivable area. A framework for the online modeling of the driving environment using a multi-beam LIDAR, i.e., a Velodyne HDL-64E LIDAR, which describes the 3D environment in the form of a point cloud, is reported in this article. First, ground segmentation is performed via multi-feature extraction of the raw data grabbed by the Velodyne LIDAR to satisfy the requirement of online environment modeling. Curbs and dynamic road obstacles are detected and tracked in different manners. Curves are fitted for curb points, and points are clustered into bundles whose form and kinematics parameters are calculated. The Kalman filter is used to track dynamic obstacles, whereas the snake model is employed for curbs. Results indicate that the proposed framework is robust under various environments and satisfies the requirements for online processing. PMID:26404290

  9. CRYSTAL-FACE Polarization Lidar Research

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth

    2005-01-01

    The University of Alaska Fairbanks (UAF) Polarization Diversity Lidar (PDL, Sassen 1994) participated in the July 2002 CRYSTAL-FACE field campaign, shortly after the PI moved from the University of Utah to UAF. The truck-mounted PDL is an advanced dual wavelength (1.06 and 0.532 micron), high resolution (0.1-s by 1.5-m), scanning lidar system designed as a testbed for evaluating laser backscatter depolarization techniques for the study of clouds and aerosols in the atmosphere. The main goals identified in our proposal for the CRYSTAL-FACE experiment were, i) the characterization of Florida thunderstorm anvil macrophysical and microphysical properties from lidar backscattering and depolarization, ii) the study of thin to subvisual tropopause-topped subtropical cirrus, iii) the search for indirect cloud effects of trans- Atlantic advected Saharan dust storm aerosols on clouds, and iv) the investigation of melting layer effects on lidar and multi-wavelength Doppler radar measurements in precipitation. Although we experienced adversity in the field during the campaign, sufficient data was collected to begin addressing these topics, and several conference presentations, three journal articles, and one book chapter have resulted from the data analysis effort supported by this grant. (PDL operations were delayed by FAA concerns over the initial sighting at the Kendall-Tamiami Airport, and a brief but major laser breakdown was experienced during the re- setup at the remote Ochopee Everglades site that also supported the N-POL radar.) All lidar data collected by the PDL system were processed and quality checked, and submitted to the CRYSTAL-FACE data archive in a timely manner.

  10. 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

  11. 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

  12. Use of a lidar forward model for global comparisons of cloud fraction

    E-print Network

    Hogan, Robin

    observations by the Geoscience Laser Altimeter System (GLAS) lidar on the ICESat satellite. In order to account), which is one of the major factors limiting the accuracy of future climate predictions. In numerical

  13. Vertical structure of radar reflectivity in deep intense convective clouds over the tropics

    NASA Astrophysics Data System (ADS)

    Kumar, Shailendra; Bhat, G. S.

    2015-04-01

    This study is based on 10 years of radar reflectivity factor (Z) data derived from the TRMM Precipitation Radar (PR) measurements. We define two types of convective cells, namely, cumulonimbus towers (CbTs) and intense convective clouds (ICCs), essentially following the methodology used in deriving the vertical profiles of radar reflectivity (VPRR). CbT contains Z? 20 dBZ at 12 km height with its base height below 3 km. ICCs belong to the top 5% reflectivity population at 3 km and 8 km altitude. Regional differences in the vertical structure of convective cells have been explored for two periods, namely, JJAS (June, July, August and September) and JFM (January, February and March) months. Frequency of occurrences of CbTs and ICCs depend on the region. Africa and Latin America are the most productive regions for the CbTs while the foothills of Western Himalaya contain the most intense profiles. Among the oceanic areas, the Bay of Bengal has the strongest vertical profile, whereas Atlantic Ocean has the weakest profile during JJAS. During JFM months, maritime continent has the strongest vertical profile whereas western equatorial Indian Ocean has the weakest. Monsoon clouds lie between the continental and oceanic cases. The maximum heights of 30 and 40 dBZ reflectivities (denoted by MH30 and MH40, respectively) are also studied. MH40 shows a single mode and peaks around 5.5 km during both JJAS and JFM months. MH30 shows two modes, around 5 km and between 8 km and 10 km, respectively. It is also shown that certain conclusions such as the area/region with the most intense convective cells, depend of the reference height used in defining a convective cell.

  14. 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.

  15. 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.

  16. Using multi-frequency radar and discrete-return LiDAR measurements to estimate above-ground biomass and biomass components in a coastal temperate forest

    NASA Astrophysics Data System (ADS)

    Tsui, Olivier W.; Coops, Nicholas C.; Wulder, Michael A.; Marshall, Peter L.; McCardle, Adrian

    2012-04-01

    Height measurements from small-footprint discrete-return LiDAR and backscatter coefficients from C- and L-band radar were used independently and in combination to estimate above-ground component and total biomass for a coniferous temperate forest, located on Vancouver Island, British Columbia, Canada. Reference biomass data were obtained from plot-level data and used for comparison against the LiDAR and radar-based biomass models. For the LiDAR-only model, height metrics such as mean first return height and percentiles (e.g., 10th and 90th) of first returns correlated best to total above-ground and stem biomass. While percent of first returns above 2 m and percentiles (75th and 90th) of first returns height metrics correlated best to crown biomass. A comparison between above-ground components and total biomass indicate that stem biomass displayed the highest relationship with the LiDAR measurements while crown biomass showed the lowest relationship with relative root mean squared error ranging from 16% to 22%, respectively. Alternatively, the radar-only models indicated that for C-band radar, a combination of HH and VV backscatter demonstrated the most significant correlation with forest biomass compared to coherence based models with a relative root mean squared error of 53%. For L-band radar, a combination of HH and HV backscatter showed the most significant correlation compared to coherence based models with a relative root mean squared error of 44%. Exploring a mixture of C- and L-band backscatter and coherence based models revealed that a combination of C-HV and L-HV coherence magnitudes provided the best radar relationship with forest biomass with a relative root mean squared error of 35%. Also for all radar-based models, L- and C-band backscatter and coherence magnitudes were poorly correlated with individual biomass components when compared to total above-ground biomass. The addition of C- and L-band backscatter and coherence variables to the LiDAR-only biomass model was also investigated. The results showed that the integration of C-band HH backscatter to the LiDAR-only model significantly improved the relationship with forest biomass by explaining an additional 8.9% and 6.5% of the variability in total aboveground and stem biomass respectively, while C-band polarimetric entropy explained an additional 17.9% of the variability in crown biomass. Improvements in the relative root mean squared errors were also observed ranging from 7.1% to 11.7%. The study suggests that for a temperate forest dominated by coniferous stands, the addition of C-band radar variables to a best LiDAR-only linear model provides improved estimates of above-ground component and total biomass.

  17. 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.

  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. Gravity Waves and Mesospheric Clouds in the Summer Middle Atmosphere: A Comparison of Lidar Measurements and Ray Modeling of Gravity Waves Over Sondrestrom, Greenland

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    We conducted gravity wave ray-tracing experiments within an atmospheric region centered near the ARCLITE lidar system at Sondrestrom, Greenland (67N, 310 deg 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 daily-varying background atmospheres in the region, based on forecasts and analyses in the troposphere and stratosphere and climatologies higher up. Reverse ray tracing based on upper stratospheric lidar observations at Sondrestrom was also used to try to objectively identify wave source regions in the troposphere. A source spectrum specified by reverse ray tracing experiments in early August 1996 (when atmospheric flow patterns produced enhanced transmission of waves into the upper stratosphere) yielded model results throughout the remainder of August 1996 that agreed best with the lidar observations. The model also simulated increased vertical group propagation of waves between 40 km and 80 km due to intensifying mean easterlies, which allowed many of the gravity waves observed at 40 km over Sondrestrom to propagate quasi-vertically from 40-80 km and then interact with any mesospheric clouds at 80 km near Sondrestrom, supporting earlier experimentally-inferred correlations between upper stratospheric gravity wave activity and mesospheric cloud backscatter from Sondrestrom lidar observations. A pilot experiment of real-time runs with the model in 2001 using weather forecast data as a low-level background produced less agreement with lidar observations. We believe this is due to limitations in our specified tropospheric source spectrum, the use of climatological winds and temperatures in the upper stratosphere and mesosphere, and missing lidar data from important time periods.

  20. 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.

  1. Automatic reconstruction of 3D urban landscape by computing connected regions and assigning them an average altitude from LiDAR point cloud image

    NASA Astrophysics Data System (ADS)

    Kawata, Yoshiyuki; Koizumi, Kohei

    2014-10-01

    The demand of 3D city modeling has been increasing in many applications such as urban planing, computer gaming with realistic city environment, car navigation system with showing 3D city map, virtual city tourism inviting future visitors to a virtual city walkthrough and others. We proposed a simple method for reconstructing a 3D urban landscape from airborne LiDAR point cloud data. The automatic reconstruction method of a 3D urban landscape was implemented by the integration of all connected regions, which were extracted and extruded from the altitude mask images. These mask images were generated from the gray scale LiDAR image by the altitude threshold ranges. In this study we demonstrated successfully in the case of Kanazawa city center scene by applying the proposed method to the airborne LiDAR point cloud data.

  2. 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.

  3. Cloud screening and quality control algorithm for star photometer data: assessment with lidar measurements and with all-sky-images

    NASA Astrophysics Data System (ADS)

    Pérez-Ramírez, D.; Lyamani, H.; Olmo, F. J.; Whiteman, D. N.; Navas-Guzman, F.; Alados-Arboledas, L.

    2012-02-01

    This paper present the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. This kind of algorithms is necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, ?Ae(?), and precipitable water vapor content, W, at night-time. This cloud screening procedure consists of calculating moving averages of ?Ae(?) and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable ?Ae(?) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16° N, 3.60° W, 680 m a.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

  4. Cloud screening and quality control algorithm for star photometer data: assessment with lidar measurements and with all-sky images

    NASA Astrophysics Data System (ADS)

    Pérez-Ramírez, D.; Lyamani, H.; Olmo, F. J.; Whiteman, D. N.; Navas-Guzmán, F.; Alados-Arboledas, L.

    2012-07-01

    This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, ?Ae(?), and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of ?Ae(?) and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable ?Ae(?) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16° N, 3.60° W, 680 m a.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

  5. Cloud Screening and Quality Control Algorithm for Star Photometer Data: Assessment with Lidar Measurements and with All-sky Images

    NASA Technical Reports Server (NTRS)

    Ramirez, Daniel Perez; Lyamani, H.; Olmo, F. J.; Whiteman, D. N.; Navas-Guzman, F.; Alados-Arboledas, L.

    2012-01-01

    This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, delta Ae(lambda), and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of delta Ae() and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable Ae(lambda) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16 N, 3.60 W, 680 ma.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

  6. Doppler radar signatures of developing thunderstorms and their potential to indicate the onset of cloud-to-ground lightning

    NASA Technical Reports Server (NTRS)

    Hondl, Kurt D.; Eilts, Michael D.

    1994-01-01

    The capability of Doppler weather radars to short-term forecast the initiation of thunderstorms and the onset of cloud-to-ground (CG) lightning is examined. Doppler weather radar data from 28 thunderstorms were analyzed from August 1990 in the central Florida environment. These radar echoes were associated with CG lightning strike locations from the National Lightning Detection Network and two lightning detection systems operated by the U.S. Air Force in the vicinity of Kennedy Space Center. From a time history of these radar echoes it was found that a 10-dBZ echo, first detected near the freezing level, may be the first definitive echo of a future thunderstorm. This thunderstorm initiation signature is often accompanied by low-altitude convergence and divergence at the top of the radar echo. The observed lead times between this thunderstorm initiation signature and the first detected CG lightning strike ranged from 5 to 45 min with a median lead time of 15 min. All lightning-producing radar echoes were detected using the thunderstorm initiation signature; however, some echoes exceeded the 10-dBZ threshold and did not produce andy CG lightning. The charecteristics of the WSR-88D and Terminal Doppler Weather Radar systems are evaluated for their capability to detect the thunderstorm initiation signature in central Florida with sufficient temporal and spatial resolution.

  7. Doppler radar signatures of developing thunderstorms and their potential to indicate the onset of cloud-to-ground lightning

    SciTech Connect

    Hondl, K.D.; Eilts, M.D.

    1994-08-01

    The capability of Doppler weather radars to short-term forecast the initiation of thunderstorms and the onset of cloud-to-ground (CG) lightning is examined. Doppler weather radar data from 28 thunderstorms were analyzed from August 1990 in the central Florida environment. These radar echoes were associated with CG lightning strike locations from the National Lightning Detection Network and two lightning detection systems operated by the U.S. Air Force in the vicinity of Kennedy Space Center. From a time history of these radar echoes it was found that a 10-dBZ echo, first detected near the freezing level, may be the first definitive echo of a future thunderstorm. This thunderstorm initiation signature is often accompanied by low-altitude convergence and divergence at the top of the radar echo. The observed lead times between this thunderstorm initiation signature and the first detected CG lightning strike ranged from 5 to 45 min with a median lead time of 15 min. All lightning-producing radar echoes were detected using the thunderstorm initiation signature; however, some echoes exceeded the 10-dBZ threshold and did not produce andy CG lightning. The charecteristics of the WSR-88D and Terminal Doppler Weather Radar systems are evaluated for their capability to detect the thunderstorm initiation signature in central Florida with sufficient temporal and spatial resolution.

  8. Multi-wavelength Raman lidar observations of the Eyjafjallajökull volcanic cloud over Potenza, Southern Italy

    NASA Astrophysics Data System (ADS)

    Mona, L.; Amodeo, A.; D'Amico, G.; Giunta, A.; Madonna, F.; Pappalardo, G.

    2011-04-01

    Multi-wavelength Raman lidar measurements were performed at CNR-IMAA Atmospheric Observatory (CIAO) during the entire Eyjafjallajökull explosive eruptive period in April-May 2010, whenever weather conditions permitted. A methodology for volcanic layer identification and accurate aerosol typing has been developed on the basis both of the multi-wavelength Raman lidar measurements and EARLINET measurements performed at CIAO since 2000. The aerosol mask for lidar measurements performed at CIAO during the 2010 Eyjafjallajökull eruption has been obtained. Volcanic aerosol layers have been observed in different periods: 19-22 April, 27-29 April, 8-9 May, 13-14 May and 18-19 May. A maximum aerosol optical depth of about 0.12-0.13 was observed on 20 April, 22:00 UTC and 13 May, 20:30 UTC. Volcanic particles have been detected both at low altitudes, in the free troposphere and in the upper troposphere. Intrusions into the PBL have been revealed on 21-22 April and 13 May. In the April-May period Saharan dust intrusions typically occur in Southern Italy. For the period under investigations, a Saharan dust intrusion was observed on 13-14 May: dust and volcanic particles have been simultaneously observed at CIAO both at separated different levels and mixed within the same layer. Lidar ratios at 355 and 532 nm, Ångström exponent at 355/532 nm, backscatter related Ångström exponent at 532/1064 nm and particle linear depolarization ratio at 532 nm measured inside the detected volcanic layers have been discussed. The dependence of these quantities on relative humidity (RH) has been investigated by using co-located microwave profiler measurements. The particle linear depolarization ratio increasing with RH, lidar ratio values at 355 nm around 80 sr, and values of the ratio of lidar ratios greater than 1 suggest the presence of sulfates mixed with continental aerosol. Lower lidar ratio values (around 40 sr) increasing with RH and values of the ratio of lidar ratios lower than 1 indicate the presence of some aged ash inside these sulfate layers.

  9. The Status of the ACRF Millimeter Wave Cloud Radars (MMCRs), the Path Forward for Future MMCR Upgrades, the Concept of 3D Volume Imaging Radar and the UAV Radar

    SciTech Connect

    P Kollias; MA Miller; KB Widener; RT Marchand; TP Ackerman

    2005-12-30

    The United States (U.S.) Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) operates millimeter wavelength cloud radars (MMCRs) in several climatological regimes. The MMCRs, are the primary observing tool for quantifying the properties of nearly all radiatively important clouds over the ACRF sites. The first MMCR was installed at the ACRF Southern Great Plains (SGP) site nine years ago and its original design can be traced to the early 90s. Since then, several MMCRs have been deployed at the ACRF sites, while no significant hardware upgrades have been performed. Recently, a two-stage upgrade (first C-40 Digital Signal Processors [DSP]-based, and later the PC-Integrated Radar AcQuisition System [PIRAQ-III] digital receiver) of the MMCR signal-processing units was completed. Our future MMCR related goals are: 1) to have a cloud radar system that continues to have high reliability and uptime and 2) to suggest potential improvements that will address increased sensitivity needs, superior sampling and low cost maintenance of the MMCRs. The Traveling Wave Tube (TWT) technology, the frequency (35-GHz), the radio frequency (RF) layout, antenna, the calibration and radar control procedure and the environmental enclosure of the MMCR remain assets for our ability to detect the profile of hydrometeors at all heights in the troposphere at the ACRF sites.

  10. Antarctica Cloud Cover for October 2003 from GLAS Satellite Lidar Profiling

    NASA Technical Reports Server (NTRS)

    Spinhirne, J. D.; Palm, S. P.; Hart, W. D.

    2005-01-01

    Seeing clouds in polar regions has been a problem for the imagers used on satellites. Both clouds and snow and ice are white, which makes clouds over snow hard to see. And for thermal infrared imaging both the surface and the clouds cold. The Geoscience Laser Altimeter System (GLAS) launched in 2003 gives an entirely new way to see clouds from space. Pulses of laser light scatter from clouds giving a signal that is separated in time from the signal from the surface. The scattering from clouds is thus a sensitive and direct measure of the presence and height of clouds. The GLAS instrument orbits over Antarctica 16 times a day. All of the cloud observations for October 2003 were summarized and compared to the results from the MODIS imager for the same month. There are two basic cloud types that are observed, low stratus with tops below 3 km and high cirrus form clouds with cloud top altitude and thickness tending at 12 km and 1.3 km respectively. The average cloud cover varies from over 93 % for ocean and coastal regions to an average of 40% over the East Antarctic plateau and 60-90% over West Antarctica. When the GLAS monthly average cloud fractions are compared to the MODIS cloud fraction data product, differences in the amount of cloud cover are as much as 40% over the continent. The results will be used to improve the way clouds are detected from the imager observations. These measurements give a much improved understanding of distribution of clouds over Antarctica and may show how they are changing as a result of global warming.

  11. 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.

  12. DYNAMICS OF DUST PARTICLES RELEASED FROM OORT CLOUD COMETS AND THEIR CONTRIBUTION TO RADAR METEORS

    SciTech Connect

    Nesvorny, David; Vokrouhlicky, David; Pokorny, Petr; Janches, Diego

    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.

  13. 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.

  14. 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.

  15. 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...

  16. Measurements of the backscattering phase matrices of crystal clouds with a polarization lidar

    NASA Technical Reports Server (NTRS)

    Kaul, B. V.; Kuznetsov, A. L.; Polovtseva, E. R.

    1992-01-01

    A polarization technique based on measurements of intensities of the polarized I(parallel) and crosspolarized I(perpendicular) components of scattered radiation is often used in lidar studies of aerosols. The ratio I(perp)/I(para) is related to nonsphericity of scattering particles and it is often called, though unjustified, depolarization. Correct definition of the term has previously been shown to be the value d = 1 - P, where P is the degree of polarization defined in terms of the Stokes parameters. In fact, measurements of I(para) and I(perp) enable one to determine the Stokes parameter Q = I(para) - I(perp), and under the condition U = V = 0 the depolarization is determined by the relationship d = 2 x I(perp)/(I(para) + I(perp)). In 1988 a new cycle of measuring the Stokes parameters of lidar returns from scattering media irradiated with a linearly polarized light was started. Based on the lidar data obtained during the 1988-1990 period, a classification of scattering ensembles was made which reveals five types of the scattering particle ensembles differing by a combination of the Stokes parameters. In the 1990-1991 period, a cycle of measurements of the lidar returns' Stokes parameters was carried out using sounding radiation.

  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. 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.

  19. Monitoring of the Polar Stratospheric Clouds formation and evolution in Antarctica in August 2007 during IPY with the MATCH method applied to lidar data

    NASA Astrophysics Data System (ADS)

    Montoux, Nadege; David, Christine; Klekociuk, Andrew; Pitts, Michael; di Liberto, Luca; Snels, Marcel; Jumelet, Julien; Bekki, Slimane; Larsen, Niels

    2010-05-01

    The project ORACLE-O3 ("Ozone layer and UV RAdiation in a changing CLimate Evaluated during IPY") is one of the coordinated international proposals selected for the International Polar Year (IPY). As part of this global project, LOLITA-PSC ("Lagrangian Observations with Lidar Investigations and Trajectories in Antarctica and Arctic, of PSC") is devoted to Polar Stratospheric Clouds (PSC) studies. Indeed, understanding the formation and evolution of PSC is an important issue to quantify the impact of climate changes on their frequency of formation and, further, on chlorine activation and subsequent ozone depletion. In this framework, three lidar stations performed PSC observations in Antarctica during the 2006, 2007, and 2008 winters: Davis (68.58°S, 77.97°E), McMurdo (77.86°S, 166.48°E) and Dumont D'Urville (66.67°S, 140.01°E). The data are completed with the lidar data from CALIOP ("Cloud-Aerosol Lidar with Orthogonal Polarization") onboard the CALIPSO ("Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation") satellite. Lagrangian trajectory calculations are used to identify air masses with PSCs sounded by several ground-based lidar stations with the same method, called MATCH, applied for the first time in Arctic to study the ozone depletion with radiosoundings. The evolution of the optical properties of the PSCs and thus the type of PSCs formed (supercooled ternary solution, nitric acid trihydrate particles or ice particles) could thus be linked to the thermodynamical evolution of the air mass deduced from the trajectories. A modeling with the microphysical model of the Danish Meteorological Institute allows assessing our ability to predict PSCs for various environmental conditions. Indeed, from pressure and temperature evolution, the model allows retrieving the types of particles formed as well as their mean radii, their concentrations and could also simulate the lidar signals. In a first step, a case in August 2007 around 17-18 km, involving the three ground-based lidar stations and CALIOP has been selected. Trajectories with different models (gscf and ecmwf), grids and initializations have been computed to test the robustness of the MATCH. Then the DMI model has been used with these different trajectories to test its ability to reproduce the observations. For a same case, the temperature differences (~2-3 K) between the trajectories have a strong impact on the number density of the particles formed (factor 1000). This case is presented here in detail and a statistical comparison is planned with the numerous MATCH cases identified during the three winters and which involve most of the time two ground-based lidar stations with CALIOP.

  20. 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.

  1. Development of Cloud Microphysical Property Retrievals Using the University of Wisconsin Arctic High Spectral Resolution Lidar

    E-print Network

    Eloranta, Edwin W.

    contribution to the radar backscatter cross-section by water in mixed phase situations. Method Time (UT.8 1/(m str) 1e-8 1e-7 1e-6 1e-5 1e-4 1e-3 Time (UT) Altitude(km) Radar Backscatter Cross-Section 21 cross-sections from both the AHSRL and MMCR to estimate an effective particle size. From there, number

  2. 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.

  3. 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.

  4. A comparison of Ground-Based LiDAR, contact spectroscopy, FMCW radar, and manual snow pit profiles of a mountain snowpack

    NASA Astrophysics Data System (ADS)

    Deems, J. S.; Finnegan, D. C.; Deeb, E. J.; Marshall, H.; Bryant, A. C.; Skiles, S.; Landry, C.; Painter, T. H.

    2010-12-01

    Manual field measurement of seasonal snow properties is time-consuming and often subjective, leading to difficulties with repeatability and obtaining adequate spatial coverage. Remote sensing observations provide non-destructive sampling and large spatial extents, but signal interpretation is frequently complicated by high spatial variability. Use of remote sensing technology via ground-based deployment offers the potential to bridge manual and remote observations, and aid interpretation and repeatability of both. We examine co-located profiles of snow properties in a single snow pit using a variety of observation techniques. Ground-based LiDAR scans of the vertical pit face using a 1550 nm wavelength full-waveform scanning LiDAR system provides 2 to 5 mm horizontal and vertical resolution that allows for quantifiable characterization of reflectivity, absorption and grain size. A contact spectroscopy profile at 2 cm vertical intervals provides spectral signatures, from which optical-equivalent grain size and specific surface area are inferred. A portable FMCW radar system returns a profile of backscatter energy with 1 cm vertical resolution, detailing layering and a vertical SWE distribution. A conventional manual profile of stratigraphy, grain size and type, and hardness allows comparison of profiles from the different technologies to standard field observation practices. This comparison at the point scale supports interpretation of data obtained using these different techniques, and analysis of field and remotely-sensed measurements of seasonal snowpack properties at multiple scales in mountain environments.

  5. Active optical remote sensing of dense clouds with diffusing light : Early results, present implementations, and the challenges ahead

    SciTech Connect

    Davis, A. B.; Cahalan, R. F.; Winker, D. 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.

  6. 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.

  7. 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.

  8. The relation of radar to cloud area-time integrals and implications for rain measurements from space

    NASA Technical Reports Server (NTRS)

    Atlas, David; Bell, Thomas L.

    1992-01-01

    The relationships between satellite-based and radar-measured area-time integrals (ATI) for convective storms are determined, and both are shown to depend on the climatological conditional mean rain rate and the ratio of the measured cloud area to the actual rain area of the storms. The GOES precipitation index of Arkin (1986) for convective storms, an area-time integral for satellite cloud areas, is shown to be related to the ATI for radar-observed rain areas. The quality of GPI-based rainfall estimates depends on how well the cloud area is related to the rain area and the size of the sampling domain. It is also noted that the use of a GOES cloud ATI in conjunction with the radar area-time integral will improve the accuracy of rainfall estimates and allow such estimates to be made in much smaller space-time domains than the 1-month and 5-deg boxes anticipated for the Tropical Rainfall Measuring Mission.

  9. 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.

  10. Millimeter-Wave Radar Field Measurements and Inversion of Cloud Parameters for the 1999 Mt. Washington Icing Sensors Project

    NASA Technical Reports Server (NTRS)

    Pazmany, Andrew L.; Reehorst, Andrew (Technical Monitor)

    2001-01-01

    The Mount Washington Icing Sensors Project (MWISP) was a multi-investigator experiment with participants from Quadrant Engineering, NOAA Environmental Technology Laboratory (NOAA/ETL), the Microwave Remote Sensing Laboratory (MIRSL) of the University of Massachusetts (UMass), and others. Radar systems from UMass and NOAA/ETL were used to measure X-, Ka-, and W-band backscatter data from the base of Mt. Washington, while simultaneous in-situ particle measurements were made from aircraft and from the observatory at the summit. This report presents range and time profiles of liquid water content and particle size parameters derived from range profiles of radar reflectivity as measured at X-, Ka-, and W-band (9.3, 33.1, and 94.9 GHz) using an artificial neural network inversion algorithm. In this report, we provide a brief description of the experiment configuration, radar systems, and a review of the artificial neural network used to extract cloud parameters from the radar data. Time histories of liquid water content (LWC), mean volume diameter (MVD) and mean Z diameter (MZD) are plotted at 300 m range intervals for slant ranges between 1.1 and 4 km. Appendix A provides details on the extraction of radar reflectivity from measured radar power, and Appendix B provides summary logs of the weather conditions for each day in which we processed data.

  11. PhD title: Assimilation of airborne cloud radar data during the HyMeX special observing period PhD supervisors: Dr. Olivier Caumont, Dr. Vronique Ducrocq

    E-print Network

    PhD title: Assimilation of airborne cloud radar data during the HyMeX special observing period Ph their thermodynamic, microphysical, and dynamical properties. In particular, the cloud radar Rasta (http://rali.projet.latmos.ipsl.fr/) was aboard this aircraft. This radar measures vertical profiles of reflectivity and Doppler velocity above

  12. EnKF Assimilation of High-Resolution, Mobile Doppler Radar Data of the 4 May 2007 Greensburg, Kansas, Supercell into a Numerical Cloud Model

    E-print Network

    Xue, Ming

    velocity Vr and radar reflectivity factor Z. NWP models require and calculate additional state variables (eEnKF Assimilation of High-Resolution, Mobile Doppler Radar Data of the 4 May 2007 Greensburg, Kansas, Supercell into a Numerical Cloud Model ROBIN L. TANAMACHI,*,1,# LOUIS J. WICKER,@ DAVID C. DOWELL

  13. 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.

  14. Climatology of polar stratospheric clouds based on lidar observations from 1993 to 2001 over McMurdo Station, Antarctica

    NASA Astrophysics Data System (ADS)

    Adriani, Alberto; Massoli, Paola; di Donfrancesco, Guido; Cairo, Francesco; Moriconi, Maria Luisa; Snels, Marcel

    2004-12-01

    A climatology of polar stratospheric clouds (PSCs) based on lidar measurements performed at McMurdo Station, Antarctica (78°S, 167°E) from 1993 to 2001 is presented here. The observations are discussed in terms of occurrence and temporal and spatial variability of PSC types. The climatological analysis reveals that in McMurdo PSCs mainly occur between July and mid-August. During this time their altitude changes from 22 to 14 km, following the stratospheric temperature minimum trend. At the beginning of the accounted period (1993-1994), volcanic aerosols from the Mt. Pinatubo eruption in 1991 were still present in the southern polar vortex. Therefore these 2 years have been corrected for the direct contribution of the volcanic aerosol to the backscatter signal. A close examination of the data set evidences that most PSCs appear either as rather thin layers (<1 km) or as layers with a considerably higher thickness. Therefore all observed PSCs have been divided into two classes, depending on the variation of the backscattering ratio with respect to the altitude (e.g., small-scale variations, or SSV, and large-scale variations, or LSV). The seasonal behavior and the occurrence of PSC types under each class have been studied, keeping 1993 and 1994 separated to better highlighting the effect of the volcanic aerosol load on cloud properties. Finally, in order to shed some light on PSC formation, back-trajectory analysis has been performed for retrieving thermal histories of opportunely selected PSCs.

  15. 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.

  16. Installation of a Permanent Doppler Radar Monitoring System at Colima Volcano, Mexico, and its use for Eruption Cloud Modelling

    NASA Astrophysics Data System (ADS)

    Scharff, L.; Hort, M. K.; Varley, N. R.; Herzog, M.

    2011-12-01

    In February 2007 we installed a standalone Doppler radar monitoring station at Colima volcano, Mexico. During that time, a new episode of dome growth was underway with daily Vulcanian eruptive events occurring. These were continuously recorded with the Doppler radar. In December 2008 we upgraded the monitoring station with a second Doppler radar, a network video camera, and a direct WLAN connection to the 28.5km distant Colima University, which allows us to remotely reconfigure the whole system in times of volcanic crises. A custom made data logger collects and stores all data at the station before transmitting data in packages to the office. The entire system is powered by solar panels. The camera is triggered by the Doppler radar that is aimed at the vent. In case an eruption is detected, the camera switches from taking pictures at arbitrary intervals to continuous video recording until the end of the eruption. Similarly the Doppler radar switches to a high sampling rate (15Hz). In 2007 we recorded 92 events during six months with durations of 20 to 200 seconds. The velocity spectra clearly show two regimes: (a) buoyant updraft with 20 to 60 seconds of constant velocities and a maximum of 20 m/s (vertical) and (b) series of pulses of intense jetting where every pulse lasts about 20s and starts with vertical velocities up to 85 m/s (measured ~75m above vent). Our deployment at Colima volcano is the first investigation of Vulcanian eruption column dynamics using Doppler radar. The data provide particle velocities and a proxy of the particles mass ~75m above the vent, which allows us to define the activity status in near real time during an eruption. Here we focus on the dynamic processes during the early stages of eruption cloud formation. Using (1) a simple ballistic model for particle transport and (2) the active tracer high-resolution atmospheric model (ATHAM) we model the first 100 m of