Science.gov

Sample records for base height cloud

  1. Development of methods for inferring cloud thickness and cloud-base height from satellite radiance data

    NASA Technical Reports Server (NTRS)

    Smith, William L., Jr.; Minnis, Patrick; Alvarez, Joseph M.; Uttal, Taneil; Intrieri, Janet M.; Ackerman, Thomas P.; Clothiaux, Eugene

    1993-01-01

    Cloud-top height is a major factor determining the outgoing longwave flux at the top of the atmosphere. The downwelling radiation from the cloud strongly affects the cooling rate within the atmosphere and the longwave radiation incident at the surface. Thus, determination of cloud-base temperature is important for proper calculation of fluxes below the cloud. Cloud-base altitude is also an important factor in aircraft operations. Cloud-top height or temperature can be derived in a straightforward manner using satellite-based infrared data. Cloud-base temperature, however, is not observable from the satellite, but is related to the height, phase, and optical depth of the cloud in addition to other variables. This study uses surface and satellite data taken during the First ISCCP Regional Experiment (FIRE) Phase-2 Intensive Field Observation (IFO) period (13 Nov. - 7 Dec. 1991, to improve techniques for deriving cloud-base height from conventional satellite data.

  2. Ground-Based Infrared Remote Sensing of Cloud Properties over the Antarctic Plateau. Part I: Cloud-Base Heights.

    NASA Astrophysics Data System (ADS)

    Mahesh, Ashwin; Walden, Von P.; Warren, Stephen G.

    2001-07-01

    A Fourier-transform interferometer, operated throughout 1992 at South Pole Station, measured downward spectral longwave radiance from 550 to 1500 cm1 (7-18 m) at a resolution of 1 cm1. Radiance measurements were usually made twice daily, coincident with routine launches of radiosondes made by the South Pole Weather Office; 223 radiance measurements (40% of the observations) were of cloudy-sky conditions. Cloud-base heights are retrieved from these data using a ground-based version of the radiance-ratioing method, which was originally developed to retrieve cloud-top heights from satellite data. Frequencies in the R branch of the 15-m carbon dioxide band are used, exploiting the variation of atmospheric opacity with wavenumber. The annual cycle of cloud-base heights shows a bimodal distribution in all seasons except during the brief summer (December-January). Cloud-base heights are typically higher in the summer than in winter. Although retrieved cloud-base heights are uncorrelated with heights estimated by visual observers, both the retrieved and observed data indicate that base heights are bimodal. Most clouds have bases in the lowest few hundred meters, within the surface-based temperature inversion. The other mode is of higher clouds with base heights 1.5-3 km above the surface. Even the highest tropospheric clouds are within 6 km of the surface. Radiance ratioing can be used to detect polar stratospheric clouds, but their base heights are not reliably determined by the method.

  3. Cumulus cloud base height estimation from high spatial resolution Landsat data - A Hough transform approach

    NASA Technical Reports Server (NTRS)

    Berendes, Todd; Sengupta, Sailes K.; Welch, Ron M.; Wielicki, Bruce A.; Navar, Murgesh

    1992-01-01

    A semiautomated methodology is developed for estimating cumulus cloud base heights on the basis of high spatial resolution Landsat MSS data, using various image-processing techniques to match cloud edges with their corresponding shadow edges. The cloud base height is then estimated by computing the separation distance between the corresponding generalized Hough transform reference points. The differences between the cloud base heights computed by these means and a manual verification technique are of the order of 100 m or less; accuracies of 50-70 m may soon be possible via EOS instruments.

  4. Method of estimation of cloud base height using ground-based digital stereophotography

    NASA Astrophysics Data System (ADS)

    Chulichkov, Alexey I.; Andreev, Maksim S.; Emilenko, Aleksandr S.; Ivanov, Victor A.; Medvedev, Andrey P.; Postylyakov, Oleg V.

    2015-11-01

    Errors of the retrieval of the atmospheric composition using optical methods (DOAS et al.) are under the determining influence of the cloudiness during the measurements. Information on cloud characteristics helps to adjust the optical model of the atmosphere used to interpret the measurements and to reduce the retrieval errors are. For the reconstruction of some geometrical characteristics of clouds a method was developed based on taking pictures of the sky by a pair of digital photo cameras and subsequent processing of the obtained sequence of stereo frames to obtain the height of the cloud base. Since the directions of the optical axes of the stereo cameras are not exactly known, a procedure of adjusting of obtained frames was developed which use photographs of the night starry sky. In the second step, the method of the morphological analysis of images is used to determine the relative shift of the coordinates of some fragment of cloud. The shift is used to estimate the searched cloud base height. The proposed method can be used for automatic processing of stereo data and getting the cloud base height. The report describes a mathematical model of stereophotography measurement, poses and solves the problem of adjusting of optical axes of the cameras, describes method of searching of cloud fragments at another frame by the morphological image analysis; the problem of estimating the cloud base height is formulated and solved. Theoretical investigation shows that for the stereo base of 60 m and shooting with a resolution of 1600x1200 pixels in field of view of 60° the errors do not exceed 10% for the cloud base height up to 4 km. Optimization of camera settings can farther improve the accuracy. Available for authors experimental setup with the stereo base of 17 m and a resolution of 640x480 pixels preliminary confirmed theoretical estimations of the accuracy in comparison with laser rangefinder.

  5. [Retrieval of the Optical Thickness and Cloud Top Height of Cirrus Clouds Based on AIRS IR High Spectral Resolution Data].

    PubMed

    Cao, Ya-nan; Wei, He-li; Dai, Cong-ming; Zhang, Xue-hai

    2015-05-01

    A study was carried out to retrieve optical thickness and cloud top height of cirrus clouds from the Atmospheric Infrared Sounder (AIRS) high spectral resolution data in 1070~1135 cm-1 IR band using a Combined Atmospheric Radiative Transfer model (CART) by brightness temperature difference between model simulation and AIRS observation. The research is based on AIRS LIB high spectral infrared observation data combined with Moderate Resolution Imaging Spectroradiometer (MODIS) cloud product data. Brightness temperature spectra based, on the retrieved cirrus optical thickness and cloud top height were simulated and compared with brightness temperature spectra of AIRS observation in the 650~1150 cm-1 band. The cirrus optical thickness and cloud top height retrieved were compared with brightness temperature of AIRS for channel 760 (900.56 cm-1, 11. 1 m) and cirrus reflectance of MODIS cloud product. And cloud top height retrieved was compared with cloud top height from MODIS. Results show that the brightness temperature spectra simulated were basically consistent with AIRS observation under the condition of retrieval in the 650~1150 cm-1 band. It means that CART can be used to simulate AIRS brightness temperature spectra. The retrieved cirrus parameters are consistent with brightness temperature of AIRS for channel 11. 1 m with low brightness temperature corresponding to large cirrus optical thickness and high cloud top height. And the retrieved cirrus parameters are consistent with cirrus reflectance of MODIS cloud product with high cirrus reflectance corresponding to large cirrus optical thickness and high cloud top height. Correlation coefficient of brightness temperature between retrieved cloud top height and MODIS cloud top height was relatively high. They are mostly located in the range of 8. 5~11.5 km, and their probability distribution trend is approximately identical. CART model is feasible to retrieve cirrus properties, and the retrieval is reliable. PMID:26415429

  6. Cloud Base Height Measurements at Manila Observatory: Initial Results from Constructed Paired Sky Imaging Cameras

    NASA Astrophysics Data System (ADS)

    Lagrosas, N.; Tan, F.; Antioquia, C. T.

    2014-12-01

    Fabricated all sky imagers are efficient and cost effective instruments for cloud detection and classification. Continuous operation of this instrument can result in the determination of cloud occurrence and cloud base heights for the paired system. In this study, a fabricated paired sky imaging system - consisting two commercial digital cameras (Canon Powershot A2300) enclosed in weatherproof containers - is developed in Manila Observatory for the purpose of determining cloud base heights at the Manila Observatory area. One of the cameras is placed on the rooftop of Manila Observatory and the other is placed on the rooftop of the university dormitory, 489m from the first camera. The cameras are programmed to simultaneously gather pictures every 5 min. Continuous operation of these cameras were implemented since the end of May of 2014 but data collection started end of October 2013. The data were processed following the algorithm proposed by Kassianov et al (2005). The processing involves the calculation of the merit function that determines the area of overlap of the two pictures. When two pictures are overlapped, the minimum of the merit function corresponds to the pixel column positions where the pictures have the best overlap. In this study, pictures of overcast sky prove to be difficult to process for cloud base height and were excluded from processing. The figure below shows the initial results of the hourly average of cloud base heights from data collected from November 2013 to July 2014. Measured cloud base heights ranged from 250m to 1.5km. These are the heights of cumulus and nimbus clouds that are dominant in this part of the world. Cloud base heights are low in the early hours of the day indicating low convection process during these times. However, the increase in the convection process in the atmosphere can be deduced from higher cloud base heights in the afternoon. The decrease of cloud base heights after 15:00 follows the trend of decreasing solar energy in the atmosphere after this time. The results show the potential of these instruments to determine cloud base heights on prolonged time intervals. The continuous operation of these instruments is implemented to gather seasonal variation of cloud base heights in this part of the world and to add to the much-needed dataset for future climate studies in Manila Observatory.

  7. Cloud Base Height and Wind Speed Retrieval through Digital Camera Based Stereo Vision

    NASA Astrophysics Data System (ADS)

    Janeiro, F. M.; Wagner, F.; Ramos, P. M.

    2010-12-01

    Clouds are an important factor in Earth’s climate system. In general, the height of the cloud determines if the cloud consists of water droplets or ice crystals which have large consequences on the radiative properties of the clouds. Also, the height plays a role on the interaction between aerosols and clouds. Furthermore, the height of low clouds is very important for air safety, especially if an instrument landing system (ILS) is not available, as is the case in small aerodromes. Cloud height can be assessed from stereo photography using triangulation methods. However, in the past, the matching of the pictures had to be done manually, in a time consuming and error prone procedure. Recently, the developments on digital consumer electronics have made digital cameras widely available and at relatively low cost. The use of digital cameras in stereo vision presents the major advantage of allowing for the automation of the picture matching in a process called image registration. In fact, this process can now be performed by a computer in a fully automated way. Another advantage of the stereo digital photography is that cloud height can be estimated in various horizontal positions in contrast to LIDAR or ceilometer measurements where the cloud height can only be determined in the direction of laser beam. In a previous work we have analyzed the main sources of uncertainty in the cloud base height and wind speed estimation using a digital camera based system. Here, we present the new developments that attempt to reduce the final system uncertainty. Two digital cameras are placed 40 m away from each other with a vertical alignment uncertainty estimated to be better than 0.1°. A computer based triggering system is employed to remotely trigger the two cameras within 1 ms of each other. The pictures are automatically downloaded to a single computer for near real time processing. An overview of the whole system will be presented as well as field measurements. A comparison with available LIDAR measurements will also be included.

  8. Latitudinal variations of cloud base height and lightning parameters in the tropics

    NASA Technical Reports Server (NTRS)

    Mushtak, V. C.; Williams, E. R.; Boccippio, D. J.

    2006-01-01

    The observed reduction in cloud-to-ground lightning in the new-equational zone is examined from the perspective of the width of the main negative charge region. Thermodynamic observations of cloud base height also show a climatological minimum value in the near-equatorial region. The association of low cloud base with both narrow updrafts and narrow changing zones may impede the bridging of the large air gap to ground, and thereby suppress cloud-to-ground lightning activity. This width dependence may be more important than the approx. 10% variation in height of the freezing level in the encouraging flashes to ground.

  9. Urbanization Causes Increased Cloud Base Height and Decreased Fog in Coastal Southern California

    NASA Technical Reports Server (NTRS)

    Williams, A. Park; Schwartz, Rachel E.; Iacobellis, Sam; Seager, Richard; Cook, Benjamin I.; Still, Christopher J.; Husak, Gregory; Michaelsen, Joel

    2015-01-01

    Subtropical marine stratus clouds regulate coastal and global climate, but future trends in these clouds are uncertain. In coastal Southern California (CSCA), interannual variations in summer stratus cloud occurrence are spatially coherent across 24 airfields and dictated by positive relationships with stability above the marine boundary layer (MBL) and MBL height. Trends, however, have been spatially variable since records began in the mid-1900s due to differences in nighttime warming. Among CSCA airfields, differences in nighttime warming, but not daytime warming, are strongly and positively related to fraction of nearby urban cover, consistent with an urban heat island effect. Nighttime warming raises the near-surface dew point depression, which lifts the altitude of condensation and cloud base height, thereby reducing fog frequency. Continued urban warming, rising cloud base heights, and associated effects on energy and water balance would profoundly impact ecological and human systems in highly populated and ecologically diverse CSCA.

  10. Urbanization causes increased cloud base height and decreased fog in coastal Southern California

    NASA Astrophysics Data System (ADS)

    Williams, A. Park; Schwartz, Rachel E.; Iacobellis, Sam; Seager, Richard; Cook, Benjamin I.; Still, Christopher J.; Husak, Gregory; Michaelsen, Joel

    2015-03-01

    Subtropical marine stratus clouds regulate coastal and global climate, but future trends in these clouds are uncertain. In coastal Southern California (CSCA), interannual variations in summer stratus cloud occurrence are spatially coherent across 24 airfields and dictated by positive relationships with stability above the marine boundary layer (MBL) and MBL height. Trends, however, have been spatially variable since records began in the mid-1900s due to differences in nighttime warming. Among CSCA airfields, differences in nighttime warming, but not daytime warming, are strongly and positively related to fraction of nearby urban cover, consistent with an urban heat island effect. Nighttime warming raises the near-surface dew point depression, which lifts the altitude of condensation and cloud base height, thereby reducing fog frequency. Continued urban warming, rising cloud base heights, and associated effects on energy and water balance would profoundly impact ecological and human systems in highly populated and ecologically diverse CSCA.

  11. Verification and correction of cloud base and top height retrievals from Ka-band cloud radar in Boseong, Korea

    NASA Astrophysics Data System (ADS)

    Oh, Su-Bin; Kim, Yeon-Hee; Kim, Ki-Hoon; Cho, Chun-Ho; Lim, Eunha

    2016-01-01

    In this study, cloud base height (CBH) and cloud top height (CTH) observed by the Ka-band (33.44 GHz) cloud radar at the Boseong National Center for Intensive Observation of Severe Weather during fall 2013 (September-November) were verified and corrected. For comparative verification, CBH and CTH were obtained using a ceilometer (CL51) and the Communication, Ocean and Meteorological Satellite (COMS). During rainfall, the CBH and CTH observed by the cloud radar were lower than observed by the ceilometer and COMS because of signal attenuation due to raindrops, and this difference increased with rainfall intensity. During dry periods, however, the CBH and CTH observed by the cloud radar, ceilometer, and COMS were similar. Thin and low-density clouds were observed more effectively by the cloud radar compared with the ceilometer and COMS. In cases of rainfall or missing cloud radar data, the ceilometer and COMS data were proven effective in correcting or compensating the cloud radar data. These corrected cloud data were used to classify cloud types, which revealed that low clouds occurred most frequently.

  12. The computation of cloud base height from paired whole-sky imaging cameras

    SciTech Connect

    Allmen, M.C.; Kegelmeyer, W.P. Jr.

    1994-03-01

    A major goal for global change studies is to improve the accuracy of general circulation models (GCMs) capable of predicting the timing and magnitude of greenhouse gas-induced global warming. Research has shown that cloud radiative feedback is the single most important effect determining the magnitude of possible climate responses to human activity. Of particular value to reducing the uncertainties associated with cloud-radiation interactions is the measurement of cloud base height (CBH), both because it is a dominant factor in determining the infrared radiative properties of clouds with respect to the earth`s surface and lower atmosphere and because CBHs are essential to measuring cloud cover fraction. We have developed a novel approach to the extraction of cloud base height from pairs of whole sky imaging (WSI) cameras. The core problem is to spatially register cloud fields from widely separated WSI cameras; this complete, triangulation provides the CBH measurements. The wide camera separation (necessary to cover the desired observation area) and the self-similarity of clouds defeats all standard matching algorithms when applied to static views of the sky. To address this, our approach is based on optical flow methods that exploit the fact that modern WSIs provide sequences of images. We will describe the algorithm and present its performance as evaluated both on real data validated by ceilometer measurements and on a variety of simulated cases.

  13. Linear relation between convective cloud base height and updrafts and application to satellite retrievals

    NASA Astrophysics Data System (ADS)

    Zheng, Youtong; Rosenfeld, Daniel

    2015-08-01

    Measurements done by the Department of Energy/Atmospheric Radiation Measurement program, at the Southern Great Plains, the central Amazon, and on board an oceangoing ship between Honolulu and Los Angeles, show that updraft speeds measured by Doppler lidar and 95 GHz cloud radar are tightly linearly correlated with cloud base height (Hb). Based on these relationships, a method of satellite retrieval of maximum (Wmax) and cloud base (Wb) updraft speeds in cloud topped planetary boundary layer is proposed. Hb, as an input for updraft estimation, is obtained from satellite-retrieved cloud base temperature in combination with 2 m air temperature derived from European Centre for Medium-Range Weather Forecasts reanalysis. Validation by the lidar and radar measurements shows good agreements for the satellite retrieval of Wmax with RMSE (root-mean-square error) = 0.38 m/s and MAPE (mean absolute percentage error) = 19% and Wb with RMSE = 0.34 m/s and MAPE = 21%.

  14. The Role of Cloud Base Height in the Convective Vigor and Flash Rate of Thunderstorms

    NASA Astrophysics Data System (ADS)

    Williams, E. R.; Mushtak, V. C.; Boccippio, D. J.

    2002-12-01

    Earlier studies of atmospheric convection have established the following results: (1) Convective Available Potential Energy (CAPE) over tropical land areas is of the same order as over warm ocean regions, (2) updraft strengths in continental clouds are more than twice those in oceanic clouds, (3) cumulonimbus updraft widths are larger over land than over ocean, (4) thermal widths in the planetary boundary layer over land increase with the depth of the boundary layer. The present study is concerned with tests of the hypothesis that cumulonimbus updraft width scales with cloud base height, and the greater the width, the more efficient is the conversion of CAPE to updraft kinetic energy. The greater the kinetic energy, the greater is the lightning flash rate. Comparisons are made between cloud base height inferred from routine thermodynamic measurements throughout the tropics and thunderstorm flash rates (in proximity to the surface stations) observed by the Lightning Imaging Sensor on the NASA TRMM (Tropical Rainfall Measuring Mission) satellite. These comparisons indicate that, on average, thunderstorm flash rates increase exponentially with cloud base height, with an order of magnitude change in flash rate for a change in height from 500 m values typical for tropical oceans, to 2500 m values typical of extreme tropical continental conditions. These correlations, found to be statistically significant, support the foregoing hypothesis.

  15. Evaluation of cloud base height measurements from ceilometer CL31 and MODIS satellite over Ahmedabad, India

    NASA Astrophysics Data System (ADS)

    Sharma, S.; Vaishnav, R.; Shukla, M. V.; Kumar, P.; Kumar, P.; Thapliyal, P. K.; Lal, S.; Acharya, Y. B.

    2015-11-01

    Clouds play a tangible role in the Earth's atmosphere and in particular, the cloud base height (CBH) which is linked to cloud type is one of the important characteristic to describe the influence of clouds on the environment. In present study, CBH observations from ceilometer CL31 have been extensively studied during May 2013 to January 2015 over Ahmedabad (23.03° N, 72.54° E), India. A detail comparison has been performed with the use of ground-based CBH measurements from ceilometer CL31 and CBH retrieved from MODIS (Moderate Resolution Imaging Spectroradiometer) onboard Aqua and Terra satellite. Some interesting features of cloud dynamics viz. strong downdraft and updraft have been observed over Ahmedabad which revealed different cloud characteristics during monsoon and post-monsoon periods. CBH shows seasonal variation during Indian summer monsoon and post-monsoon period. Results indicate that ceilometer is one of the excellent instruments to precisely detect low and mid-level clouds and MODIS satellite provides accurate retrieval of high-level clouds over this region. The CBH algorithm used for MODIS satellite is also able to capture the low-level clouds.

  16. Evaluation of cloud base height measurements from Ceilometer CL31 and MODIS satellite over Ahmedabad, India

    NASA Astrophysics Data System (ADS)

    Sharma, Som; Vaishnav, Rajesh; Shukla, Munn V.; Kumar, Prashant; Kumar, Prateek; Thapliyal, Pradeep K.; Lal, Shyam; Acharya, Yashwant B.

    2016-02-01

    Clouds play a tangible role in the Earth's atmosphere and in particular, the cloud base height (CBH), which is linked to cloud type, is one of the most important characteristics to describe the influence of clouds on the environment. In the present study, CBH observations from Ceilometer CL31 were extensively studied during May 2013 to January 2015 over Ahmedabad (23.03° N, 72.54° E), India. A detailed comparison has been performed with the use of ground-based CBH measurements from Ceilometer CL31 and CBH retrieved from MODIS (Moderate Resolution Imaging Spectroradiometer) onboard Aqua and Terra satellite. CBH retrieved from MODIS is ˜ 1.955 and ˜ 1.093 km on 25 July 2014 and 1 January 2015 respectively, which matches well with ceilometer-measured CBH ( ˜ 1.92 and ˜ 1.097 km). Some interesting features of cloud dynamics viz. strong downdraft and updraft have been observed over Ahmedabad which revealed different cloud characteristics during monsoon and post-monsoon periods. CBH shows seasonal variation during the Indian summer monsoon and post-monsoon period. Results indicate that the ceilometer is an excellent instrument to precisely detect low- and mid-level clouds, and the MODIS satellite provides accurate retrieval of high-level clouds over this region. The CBH algorithm used for the MODIS satellite is also able to capture the low-level clouds.

  17. New Stereo Vision Digital Camera System for Simultaneous Measurement of Cloud Base Height and Atmospheric Visibility

    NASA Astrophysics Data System (ADS)

    Janeiro, F. M.; Carretas, F.; Palma, N.; Ramos, P. M.; Wagner, F.

    2013-12-01

    Clouds play an important role in many aspects of everyday life. They affect both the local weather as well as the global climate and are an important parameter on climate change studies. Cloud parameters are also important for weather prediction models which make use of actual measurements. It is thus important to have low-cost instrumentation that can be deployed in the field to measure those parameters. This kind of instruments should also be automated and robust since they may be deployed in remote places and be subject to adverse weather conditions. Although clouds are very important in environmental systems, they are also an essential component of airplane safety when visual flight rules (VFR) are enforced, such as in most small aerodromes where it is not economically viable to install instruments for assisted flying. Under VFR there are strict limits on the height of the cloud base, cloud cover and atmospheric visibility that ensure the safety of the pilots and planes. Although there are instruments, available in the market, to measure those parameters, their relatively high cost makes them unavailable in many local aerodromes. In this work we present a new prototype which has been recently developed and deployed in a local aerodrome as proof of concept. It is composed by two digital cameras that capture photographs of the sky and allow the measurement of the cloud height from the parallax effect. The new developments consist on having a new geometry which allows the simultaneous measurement of cloud base height, wind speed at cloud base height and atmospheric visibility, which was not previously possible with only two cameras. The new orientation of the cameras comes at the cost of a more complex geometry to measure the cloud base height. The atmospheric visibility is calculated from the Lambert-Beer law after the measurement of the contrast between a set of dark objects and the background sky. The prototype includes the latest hardware developments that allow its cost to remain low even with its increased functionality. Also, a new control software was also developed to ensure that the two cameras are triggered simultaneously. This is a major requirement that affects the final uncertainty of the measurements due to the constant movement of the clouds in the sky. Since accurate orientation of the cameras can be a very demanding task in field deployments, an automated calibration procedure has been developed, that removes the need for an accurate alignment. It consists on photographing the stars, which do not exhibit parallax due to the long distances involved, and deducing the inherent misalignments of the two cameras. The known misalignments are then used to correct the cloud photos. These developments will be described in the detail, along with an uncertainty analysis of the measurement setup. Measurements of cloud base height and atmospheric visibility will be presented and compared with measurements from other in-situ instruments. This work was supported by FCT project PTDC/CTE-ATM/115833/2009 and Program COMPETE FCOMP-01-0124-FEDER-014508

  18. Estimation of cloud height using ground-based stereophotography: methods, error analysis, and validation

    NASA Astrophysics Data System (ADS)

    Andreev, Maksim S.; Chulichkov, Alexey I.; Emilenko, Aleksander S.; Medvedev, Andrey P.; Postylyakov, Oleg V.

    2014-11-01

    Retrieval errors of the atmospheric composition using optical methods (DOAS et al.) are under the determining influence of the cloudiness during the measurements. If there is information about the clouds, the optical model of the atmosphere used to interpret the measurements can be adjusted, and the retrieval errors are reduced. For the reconstruction of the parameters of clouds a method was developed based on taking pictures of the sky by a pair of digital photocameras and subsequent processing of the obtained sequence of stereo frames by a method of morphological analysis of images. Since the directions of the optical axes of the cameras are not exactly known, the calibration of the direction of sight of the cameras was conducted at the first stage using the photographs of the stars in the night sky. At the second stage, the relative shift of the image of the cloud fragment on the second frame of the pair was calculated. Stereo pairs obtained by simultaneous photography, allowed us to estimate the height of cloud. The report describes a mathematical model of measurement, pose and solve the problem of calibration of direction of sight of the cameras, describes methods of combining of image fragments by morphological method, the problem of estimating cloud height and speed of their movement is formulated and solved. The examples of evaluations in a real photo are analyzed and validated by the way of comparing with the results of measurement by laser rangefinder.

  19. Evaluation of Satellite-Based Upper Troposphere Cloud Top Height Retrievals in Multilayer Cloud Conditions During TC4

    NASA Technical Reports Server (NTRS)

    Chang, Fu-Lung; Minnis, Patrick; Ayers, J. Kirk; McGill, Matthew J.; Palikonda, Rabindra; Spangenberg, Douglas A.; Smith, William L., Jr.; Yost, Christopher R.

    2010-01-01

    Upper troposphere cloud top heights (CTHs), restricted to cloud top pressures (CTPs) less than 500 hPa, inferred using four satellite retrieval methods applied to Twelfth Geostationary Operational Environmental Satellite (GOES-12) data are evaluated using measurements during the July August 2007 Tropical Composition, Cloud and Climate Coupling Experiment (TC4). The four methods are the single-layer CO2-absorption technique (SCO2AT), a modified CO2-absorption technique (MCO2AT) developed for improving both single-layered and multilayered cloud retrievals, a standard version of the Visible Infrared Solar-infrared Split-window Technique (old VISST), and a new version of VISST (new VISST) recently developed to improve cloud property retrievals. They are evaluated by comparing with ER-2 aircraft-based Cloud Physics Lidar (CPL) data taken during 9 days having extensive upper troposphere cirrus, anvil, and convective clouds. Compared to the 89% coverage by upper tropospheric clouds detected by the CPL, the SCO2AT, MCO2AT, old VISST, and new VISST retrieved CTPs less than 500 hPa in 76, 76, 69, and 74% of the matched pixels, respectively. Most of the differences are due to subvisible and optically thin cirrus clouds occurring near the tropopause that were detected only by the CPL. The mean upper tropospheric CTHs for the 9 days are 14.2 (+/- 2.1) km from the CPL and 10.7 (+/- 2.1), 12.1 (+/- 1.6), 9.7 (+/- 2.9), and 11.4 (+/- 2.8) km from the SCO2AT, MCO2AT, old VISST, and new VISST, respectively. Compared to the CPL, the MCO2AT CTHs had the smallest mean biases for semitransparent high clouds in both single-layered and multilayered situations whereas the new VISST CTHs had the smallest mean biases when upper clouds were opaque and optically thick. The biases for all techniques increased with increasing numbers of cloud layers. The transparency of the upper layer clouds tends to increase with the numbers of cloud layers.

  20. Evaluation of satellite-based upper troposphere cloud top height retrievals in multilayer cloud conditions during TC4

    NASA Astrophysics Data System (ADS)

    Chang, Fu-Lung; Minnis, Patrick; Ayers, J. Kirk; McGill, Matthew J.; Palikonda, Rabindra; Spangenberg, Douglas A.; Smith, William L.; Yost, Christopher R.

    2010-05-01

    Upper troposphere cloud top heights (CTHs), restricted to cloud top pressures (CTPs) < 500 hPa, inferred using four satellite retrieval methods applied to Twelfth Geostationary Operational Environmental Satellite (GOES-12) data are evaluated using measurements during the July-August 2007 Tropical Composition, Cloud and Climate Coupling Experiment (TC4). The four methods are the single-layer CO2-absorption technique (SCO2AT), a modified CO2-absorption technique (MCO2AT) developed for improving both single-layered and multilayered cloud retrievals, a standard version of the Visible Infrared Solar-infrared Split-window Technique (old VISST), and a new version of VISST (new VISST) recently developed to improve cloud property retrievals. They are evaluated by comparing with ER-2 aircraft-based Cloud Physics Lidar (CPL) data taken during 9 days having extensive upper troposphere cirrus, anvil, and convective clouds. Compared to the 89% coverage by upper tropospheric clouds detected by the CPL, the SCO2AT, MCO2AT, old VISST, and new VISST retrieved CTPs < 500 hPa in 76, 76, 69, and 74% of the matched pixels, respectively. Most of the differences are due to subvisible and optically thin cirrus clouds occurring near the tropopause that were detected only by the CPL. The mean upper tropospheric CTHs for the 9 days are 14.2 (2.1) km from the CPL and 10.7 (2.1), 12.1 (1.6), 9.7 (2.9), and 11.4 (2.8) km from the SCO2AT, MCO2AT, old VISST, and new VISST, respectively. Compared to the CPL, the MCO2AT CTHs had the smallest mean biases for semitransparent high clouds in both single-layered and multilayered situations whereas the new VISST CTHs had the smallest mean biases when upper clouds were opaque and optically thick. The biases for all techniques increased with increasing numbers of cloud layers. The transparency of the upper layer clouds tends to increase with the numbers of cloud layers.

  1. Development of an analysis tool for cloud base height and visibility

    NASA Astrophysics Data System (ADS)

    Umdasch, Sarah; Reinhold, Steinacker; Manfred, Dorninger; Markus, Kerschbaum; Wolfgang, Pttschacher

    2014-05-01

    The meteorological variables cloud base height (CBH) and horizontal atmospheric visibility (VIS) at surface level are of vital importance for safety and effectiveness in aviation. Around 20% of all civil aviation accidents in the USA from 2003 to 2007 were due to weather related causes, around 18% of which were owing to decreased visibility or ceiling (main CBH). The aim of this study is to develop a system generating quality-controlled gridded analyses of the two parameters based on the integration of various kinds of observational data. Upon completion, the tool is planned to provide guidance for nowcasting during take-off and landing as well as for flights operated under visual flight rules. Primary input data consists of manual as well as instrumental observation of CBH and VIS. In Austria, restructuring of part of the standard meteorological stations from human observation to automatic measurement of VIS and CBH is currently in progress. As ancillary data, satellite derived products can add 2-dimensional information, e.g. Cloud Type by NWC SAF (Nowcasting Satellite Application Facilities) MSG (Meteosat Second Generation). Other useful available data are meteorological surface measurements (in particular of temperature, humidity, wind and precipitation), radiosonde, radar and high resolution topography data. A one-year data set is used to study the spatial and weather-dependent representativeness of the CBH and VIS measurements. The VERA (Vienna Enhanced Resolution Analysis) system of the Institute of Meteorology and Geophysics of the University of Vienna provides the framework for the analysis development. Its integrated "Fingerprint" technique allows the insertion of empirical prior knowledge and ancillary information in the form of spatial patterns. Prior to the analysis, a quality control of input data is performed. For CBH and VIS, quality control can consist of internal consistency checks between different data sources. The possibility of two-dimensional consistency checks has to be explored. First results in the development of quality control features and fingerprints will be shown.

  2. Estimation of Cirrus and Stratus Cloud Heights Using Landsat Imagery

    NASA Technical Reports Server (NTRS)

    Inomata, Yasushi; Feind, R. E.; Welch, R. M.

    1996-01-01

    A new method based upon high-spatial-resolution imagery is presented that matches cloud and shadow regions to estimate cirrus and stratus cloud heights. The distance between the cloud and the matching shadow pattern is accomplished using the 2D cross-correlation function from which the cloud height is derived. The distance between the matching cloud-shadow patterns is verified manually. The derived heights also are validated through comparison with a temperature-based retrieval of cloud height. It is also demonstrated that an estimate of cloud thickness can be retrieved if both the sunside and anti-sunside of the cloud-shadow pair are apparent. The technique requires some intepretation to determine the cloud height level retrieved (i.e., the top, base, or mid-level). It is concluded that the method is accurate to within several pixels, equivalent to cloud height variations of about +/- 250 m. The results show that precise placement of the templates is unnecessary, so that the development of a semi-automated procedure is possible. Cloud templates of about 64 pixels on a side or larger produce consistent results. The procedure was repeated for imagery degraded to simulate lower spatial resolutions. The results suggest that spatial resolution of 150-200 m or better is necessary in order to obtain stable cloud height retrievals.

  3. An Assessment of MultiAngle Imaging SpectroRadiometer (MISR) Stereo-Derived Cloud Top Heights and cloud top winds using ground-based radar, lidar, and microwave radiometers

    SciTech Connect

    Marchand, Roger T.; Ackerman, Thomas P.; Moroney, C.

    2007-03-17

    Clouds are of tremendous importance to climate because of their direct radiative effects and because of their role in atmospheric dynamics and the hydrological cycle. The value of satellite imagery in monitoring cloud properties on a global basis can hardly be understated. One cloud property that satellites are in an advantageous position to monitor is cloud top height. Cloud top height retrievals are especially important for MISR because the derived height field is used to co-register the measured radiances. In this presentation we show the results of an ongoing comparison between ground-based millimeter-wave cloud radar and lidar measurements of cloud top and MISR stereo-derived cloud top height. This comparison is based on data from three radar systems located in the U.S Southern Great Plains (Lamont, Oklahoma), the Tropical Western Pacific (Nauru Island) and the North Slope of Alaska (Barrow, Alaska). These radars are operated as part of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program. The MISR stereo height algorithm is performing largely as expected for most optically thick clouds. As with many satellite retrievals, the stereo-height retrieval has difficulty with optically thin clouds or ice clouds with little optical contrast near cloud top.

  4. Evaluation of SCIAMACHY Oxygen A band cloud heights using Cloudnet measurements

    NASA Astrophysics Data System (ADS)

    Wang, P.; Stammes, P.

    2014-05-01

    Two SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) O2 A band cloud height products are evaluated using ground-based radar/lidar measurements between January 2003 and December 2011. The products are the ESA (European Space Agency) 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 1 h centered at the SCIAMACHY overpass time. In total we have 217 cases of single-layer clouds and 204 cases of multilayer clouds. 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 0.4 km higher than the Cloudnet cloud top height, with a standard deviation of 3.1 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 -0.1 km with a standard deviation of 1.9 km. The ESA L2 cloud top height is higher than the FRESCO cloud height. The differences between the SCIAMACHY cloud (top) height and the Cloudnet cloud top height are linked to cloud optical thickness. 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. 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. The results are similar for multilayer clouds, but the percentage of cases having a bias within 1 km is smaller than for single-layer clouds. We may conclude that the FRESCO cloud height is accurate for low and middle level clouds, whereas the ESA L2 cloud top height is more accurate for middle level clouds. Both products are less accurate for high clouds.

  5. 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.

  6. Crop height determination with UAS point clouds

    NASA Astrophysics Data System (ADS)

    Grenzdörffer, G. J.

    2014-11-01

    The accurate determination of the height of agricultural crops helps to predict yield, biomass etc. These relationships are of great importance not only for crop production but also in grassland management, because the available biomass and food quality are valuable information. However there is no cost efficient and automatic system for the determination of the crop height available. 3D-point clouds generated from high resolution UAS imagery offer a new alternative. Two different approaches for crop height determination are presented. The "difference method" were the canopy height is determined by taking the difference between a current UAS-surface model and an existing digital terrain model (DTM) is the most suited and most accurate method. In situ measurements, vegetation indices and yield observations correlate well with the determined UAS crop heights.

  7. Exploiting the sensitivity of two satellite cloud height retrievals to cloud vertical distribution

    NASA Astrophysics Data System (ADS)

    Carbajal Henken, C. K.; Doppler, L.; Lindstrot, R.; Preusker, R.; Fischer, J.

    2015-08-01

    This work presents a study on the sensitivity of two satellite cloud height retrievals to cloud vertical distribution. The difference in sensitivity is exploited by relating the difference in the retrieved cloud heights to cloud vertical extent. The two cloud height retrievals, performed within the Freie Universitt Berlin AATSR MERIS Cloud (FAME-C) algorithm, are based on independent measurements and different retrieval techniques. First, cloud-top temperature (CTT) is retrieved from Advanced Along Track Scanning Radiometer (AATSR) measurements in the thermal infrared. Second, cloud-top pressure (CTP) is retrieved from Medium Resolution Imaging Spectrometer (MERIS) measurements in the oxygen-A absorption band and a nearby window channel. Both CTT and CTP are converted to cloud-top height (CTH) using atmospheric profiles from a numerical weather prediction model. First, a sensitivity study using radiative transfer simulations in the near-infrared and thermal infrared was performed to demonstrate, in a quantitative manner, the larger impact of the assumed cloud vertical extinction profile, described in terms of shape and vertical extent, on MERIS than on AATSR top-of-atmosphere measurements. Consequently, cloud vertical extinction profiles will have a larger influence on the MERIS than on the AATSR cloud height retrievals for most cloud types. Second, the difference in retrieved CTH (?CTH) from AATSR and MERIS are related to cloud vertical extent (CVE), as observed by ground-based lidar and radar at three ARM sites. To increase the impact of the cloud vertical extinction profile on the MERIS-CTP retrievals, single-layer and geometrically thin clouds are assumed in the forward model. Similarly to previous findings, the MERIS-CTP retrievals appear to be close to pressure levels in the middle of the cloud. Assuming a linear relationship, the ?CTH multiplied by 2.5 gives an estimate on the CVE for single-layer clouds. The relationship is stronger for single-layer clouds than for multi-layer clouds. Due to large variations of cloud vertical extinction profiles occurring in nature, a quantitative estimate of the cloud vertical extent is accompanied with large uncertainties. Yet, estimates of the CVE provide an additional parameter, next to CTH, that can be obtained from passive imager measurements and can be used to further describe cloud vertical distribution, thus contributing to the characterization of a cloudy scene. To further demonstrate the plausibility of the approach, an estimate of the CVE was applied to a case study. In light of the follow-up mission Sentinel-3 with AATSR and MERIS like instruments, Sea and Land Surface Temperature Radiometer (SLSTR) and (Ocean and Land Colour Instrument) OLCI, respectively, for which the FAME-C algorithm can be easily adapted, a more accurate estimate of the CVE can be expected. OLCI will have three channels in the oxygen-A absorption band, possibly providing enhanced information on cloud vertical distributions.

  8. Predicting Daily Insolation with Hourly Cloud Height and Coverage.

    NASA Astrophysics Data System (ADS)

    Meyers, T. P.; Dale, R. F.

    1983-04-01

    Solar radiation information is used in crop growth, boundary layer, entomological and plant pathological models, and in determining the potential use of active and passive solar energy systems. Yet solar radiation is among the least measured meteorological variables.A semi-physical model based on standard meteorological data was developed to estimate solar radiation received at the earth's surface. The radiation model includes the effects of Rayleigh scattering, absorption by water vapor and permanent gases, and absorption and scattering by aerosols and clouds. Cloud attenuation is accounted for by assigning transmission coefficients based on cloud height and amount. The cloud transmission coefficients for various heights and coverages were derived empirically from hourly observations of solar radiation in conjunction with corresponding cloud observations at West Lafayette, Indiana. The model was tested with independent data from West Lafayette and Indianapolis, Madison, WI, Omaha, NE, Columbia, MO, Nashville, TN, Seattle, WA, Los Angeles, CA, Phoenix, AZ, Lake Charles, LA, Miami, FL, and Sterling, VA. For each of these locations a 16% random sample of days was drawn within each of the 12 months in a year for testing the model. Excellent agreement between predicted and observed radiation values was obtained for all stations tested. Mean absolute errors ranged from 1.05 to 1.80 MJ m2 day1 and root-mean-square errors ranged from 1.31 to 2.32 MJ m2 day1. The model's performance judged by relative error was found to be independent of season and cloud amount for all locations tested.

  9. Analysis of cloud top height and cloud coverage from satellites using the O2 A and B bands

    NASA Technical Reports Server (NTRS)

    Kuze, Akihiko; Chance, Kelly V.

    1994-01-01

    Cloud height and cloud coverage detection are important for total ozone retrieval using ultraviolet and visible scattered light. Use of the O2 A and B bands, around 761 and 687 nm, by a satellite-borne instrument of moderately high spectral resolution viewing in the nadir makes it possible to detect cloud top height and related parameters, including fractional coverage. The measured values of a satellite-borne spectrometer are convolutions of the instrument slit function and the atmospheric transmittance between cloud top and satellite. Studies here determine the optical depth between a satellite orbit and the Earth or cloud top height to high accuracy using FASCODE 3. Cloud top height and a cloud coverage parameter are determined by least squares fitting to calculated radiance ratios in the oxygen bands. A grid search method is used to search the parameter space of cloud top height and the coverage parameter to minimize an appropriate sum of squares of deviations. For this search, nonlinearity of the atmospheric transmittance (i.e., leverage based on varying amounts of saturation in the absorption spectrum) is important for distinguishing between cloud top height and fractional coverage. Using the above-mentioned method, an operational cloud detection algorithm which uses minimal computation time can be implemented.

  10. Retrieval of cloud height from SCIAMACHY using oxygen absorption around 630nm

    NASA Astrophysics Data System (ADS)

    Grzegorski, Michael; Deutschmann, Tim; Platt, Ulrich; Wang, Ping; Wagner, Thomas

    2010-05-01

    The SCanning Imaging Absorption spectrometer for Atmospheric ChartographY (SCIAMACHY) on ENVISAT allows measurements of different atmospheric trace gases (e.g. O3, NO2, SO2, CH4, HCHO, CO, BrO, H2O, O2, O4) using the DOAS technique. The HICRU algorithm retrieves cloud height using the spectral analysis of the oxygen absorption around 630nm combined with results of the Monte-Carlo model TRACY-II and a new SCIAMACHY surface albedo database. The results are compared to: 1.) cloud height retrievals of other satellite instruments (MERIS, MODIS) 2.) ISCCP climatology 3.) SCIAMACHY cloud algorithms (SACURA, FRESCO+) 4.) LIDAR/RADAR measurements. For low clouds, the HICRU algorithm retrieves cloud heights more close to the the top, because of the assumption of an appropriate cloud model with a realistic estimation of the scattering inside the cloud. It is also demonstrated, that none the three SCIAMACHY cloud algorithms HICRU, SACURA and FRESCO+ is able to retrieve the top of high clouds because of principal characteristics of the retrieval methods based on oxygen absorption. But oxygen absorptions can provide important additional information on the vertical cloud structure and multiple cloud layers if the method is combined with cloud-top-retrieval using windows in the thermal infrared. An application of these concepts to the GOSAT instrument will be discussed.

  11. A method of retrieving cloud top height and cloud geometrical thickness with oxygen A and B bands for the Deep Space Climate Observatory (DSCOVR) mission: Radiative transfer simulations

    NASA Astrophysics Data System (ADS)

    Yang, Yuekui; Marshak, Alexander; Mao, Jianping; Lyapustin, Alexei; Herman, Jay

    2013-06-01

    The Earth Polychromatic Imaging Camera (EPIC) onboard the Deep Space Climate Observatory (DSCOVR) was designed to measure the atmosphere and surface properties over the whole sunlit half of the Earth from the L1 Lagrangian point. It has 10 spectral channels ranging from the UV to the near-IR, including two pairs of oxygen (O2) A-band (779.5 and 764nm) and B-band (680 and 687.75nm) reference and absorption channels selected for the cloud height measurements. This paper presents the radiative transfer analysis pertinent to retrieving cloud top height and cloud geometrical thickness with EPIC A- and B-band observations. Due to photon cloud penetration, retrievals from either O2 A- or B-band channels alone gives the corresponding cloud centroid height, which is lower than the cloud top. However, we show both the sum and the difference between the retrieved cloud centroid heights in the A and B bands are functions of cloud top height and cloud geometrical thickness. Based on this fact, the paper develops a new method to retrieve cloud top height and cloud geometrical thickness simultaneously for fully cloudy scenes over ocean surface. First, cloud centroid heights are calculated for both A and B bands using the ratios between the reflectances of the absorbing and reference channels; then the cloud top height and the cloud geometrical thickness are retrieved from the two dimensional look up tables that relate the sum and the difference between the retrieved centroid heights for A and B bands to the cloud top height and the cloud geometrical thickness. This method is applicable for clouds thicker than an optical depth of 5.

  12. A Polar Specific 20-year Data Set of Cloud Fraction and Height Derived from Satellite Radiances

    NASA Technical Reports Server (NTRS)

    Francis, Jennifer; Schweiger, Axel

    2004-01-01

    This is a final report to fulfill reporting requirements on NASA grant NASA NAG5-11800. Jennifer Francis, PI at Rutgers University is currently continuing work on this project under a no-cost extension. Work at the University of Washington portion of the project is completed and reported here. Major accomplishments and results from this portion of the project include: 1) Extension and reprocessing of TOVS Polar Pathfinder (Path-P) data set; 2) Analysis of Arctic cloud variability; 3) Validation of Southern Hemisphere ocean cloud retrievals; 4) Intercompared cloud height information from AVHRR retrievals and surface-based cloud radar information.

  13. Cloud Height Maps for Hurricanes Frances and Ivan

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA's Multi-angle Imaging SpectroRadiometer (MISR) captured these images and cloud-top height retrievals of Hurricane Frances on September 4, 2004, when the eye sat just off the coast of eastern Florida, and Hurricane Ivan on September 5th, after this cyclone had devastated Grenada and was heading toward the central and western Caribbean. Hurricane Frances made landfall in the early hours of September 5, and was downgraded to Tropical Storm status as it swept inland through the Florida panhandle and continued northward. On the heels of Frances is Hurricane Ivan, which is on record as the strongest tropical cyclone to form at such a low latitude in the Atlantic, and was the most powerful hurricane to have hit the Caribbean in nearly a decade.

    The ability of forecasters to predict the intensity and amount of rainfall associated with hurricanes still requires improvement, especially on the 24 to 48 hour timescale vital for disaster planning. To improve the operational models used to make hurricane forecasts, scientists need to better understand the multi-scale interactions at the cloud, mesoscale and synoptic scales that lead to hurricane intensification and dissipation, and the various physical processes that affect hurricane intensity and rainfall distributions. Because these uncertainties with regard to how to represent cloud processes still exist, it is vital that the model findings be evaluated against hurricane observations whenever possible. Two-dimensional maps of cloud height such as those shown here offer an unprecedented opportunity for comparing simulated cloud fields against actual hurricane observations.

    The left-hand panel in each image pair is a natural color view from MISR's nadir camera. The right-hand panels are cloud-top height retrievals produced by automated computer recognition of the distinctive spatial features between images acquired at different view angles. These results indicate that at the time that these images were acquired, clouds within Frances and Ivan had attained altitudes of 15 kilometers and 16 kilometers above sea level, respectively. The height fields pictured here are uncorrected for the effects of cloud motion. Wind-corrected heights (which have higher accuracy but sparser spatial coverage) are within about 1 kilometer of the heights shown here.

    The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82o north and 82o south latitude. These data products were generated from a portion of the imagery acquired during Terra orbits 25081 and 25094. The panels cover an area of 380 kilometers x 924 kilometers, and utilize data from within blocks 65 to 87 within World Reference System-2 paths 14 and 222, respectively.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California In

  14. 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).

  15. Global cloud top height retrieval using SCIAMACHY limb spectra: model studies and first results

    NASA Astrophysics Data System (ADS)

    Eichmann, Kai-Uwe; Lelli, Luca; von Savigny, Christian; Sembhi, Harjinder; Burrows, John P.

    2016-03-01

    Cloud top heights (CTHs) are retrieved for the period 1 January 2003 to 7 April 2012 using height-resolved limb spectra measured with the SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) on board ENVISAT (ENVIronmental SATellite). In this study, we present the retrieval code SCODA (SCIAMACHY cloud detection algorithm) based on a colour index method and test the accuracy of the retrieved CTHs in comparison to other methods. Sensitivity studies using the radiative transfer model SCIATRAN show that the method is capable of detecting cloud tops down to about 5 km and very thin cirrus clouds up to the tropopause. Volcanic particles can be detected that occasionally reach the lower stratosphere. Upper tropospheric ice clouds are observable for a nadir cloud optical thickness (COT) ≥ 0.01, which is in the subvisual range. This detection sensitivity decreases towards the lowermost troposphere. The COT detection limit for a water cloud top height of 5 km is roughly 0.1. This value is much lower than thresholds reported for passive cloud detection methods in nadir-viewing direction. Low clouds at 2 to 3 km can only be retrieved under very clean atmospheric conditions, as light scattering of aerosol particles interferes with the cloud particle scattering. We compare co-located SCIAMACHY limb and nadir cloud parameters that are retrieved with the Semi-Analytical CloUd Retrieval Algorithm (SACURA). Only opaque clouds (τN,c > 5) are detected with the nadir passive retrieval technique in the UV-visible and infrared wavelength ranges. Thus, due to the frequent occurrence of thin clouds and subvisual cirrus clouds in the tropics, larger CTH deviations are detected between both viewing geometries. Zonal mean CTH differences can be as high as 4 km in the tropics. The agreement in global cloud fields is sufficiently good. However, the land-sea contrast, as seen in nadir cloud occurrence frequency distributions, is not observed in limb geometry. Co-located cloud top height measurements of the limb-viewing Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on ENVISAT are compared for the period from January 2008 to March 2012. The global CTH agreement of about 1 km is observed, which is smaller than the vertical field of view of both instruments. Lower stratospheric aerosols from volcanic eruptions occasionally interfere with the cloud retrieval and inhibit the detection of tropospheric clouds. The aerosol impact on cloud retrievals was studied for the volcanoes Kasatochi (August 2008), Sarychev Peak (June 2009), and Nabro (June 2011). Long-lasting aerosol scattering is detected after these events in the Northern Hemisphere for heights above 12.5 km in tropical and polar latitudes. Aerosol top heights up to about 22 km are found in 2009 and the enhanced lower stratospheric aerosol layer persisted for about 7 months. In August 2009 about 82 % of the lower stratosphere between 30 and 70° N was filled with scattering particles and nearly 50 % in October 2008.

  16. Cloud Height Estimation with a Single Digital Camera and Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Carretas, Filipe; Janeiro, Fernando M.

    2014-05-01

    Clouds influence the local weather, the global climate and are an important parameter in the weather prediction models. Clouds are also an essential component of airplane safety when visual flight rules (VFR) are enforced, such as in most small aerodromes where it is not economically viable to install instruments for assisted flying. Therefore it is important to develop low cost and robust systems that can be easily deployed in the field, enabling large scale acquisition of cloud parameters. Recently, the authors developed a low-cost system for the measurement of cloud base height using stereo-vision and digital photography. However, due to the stereo nature of the system, some challenges were presented. In particular, the relative camera orientation requires calibration and the two cameras need to be synchronized so that the photos from both cameras are acquired simultaneously. In this work we present a new system that estimates the cloud height between 1000 and 5000 meters. This prototype is composed by one digital camera controlled by a Raspberry Pi and is installed at Centro de Geofísica de Évora (CGE) in Évora, Portugal. The camera is periodically triggered to acquire images of the overhead sky and the photos are downloaded to the Raspberry Pi which forwards them to a central computer that processes the images and estimates the cloud height in real time. To estimate the cloud height using just one image requires a computer model that is able to learn from previous experiences and execute pattern recognition. The model proposed in this work is an Artificial Neural Network (ANN) that was previously trained with cloud features at different heights. The chosen Artificial Neural Network is a three-layer network, with six parameters in the input layer, 12 neurons in the hidden intermediate layer, and an output layer with only one output. The six input parameters are the average intensity values and the intensity standard deviation of each RGB channel. The output parameter in the output layer is the cloud height estimated by the ANN. The training procedure was performed, using the back-propagation method, in a set of 260 different clouds with heights in the range [1000, 5000] m. The training of the ANN has resulted in a correlation ratio of 0.74. This trained ANN can therefore be used to estimate the cloud height. The previously described system can also measure the wind speed and direction at cloud height by measuring the displacement, in pixels, of a cloud feature between consecutively acquired photos. Also, the geographical north direction can be estimated using this setup through sequential night images with high exposure times. A further advantage of this single camera system is that no camera calibration or synchronization is needed. This significantly reduces the cost and complexity of field deployment of cloud height measurement systems based on digital photography.

  17. Retrieving cloud top height in the JEM-EUSO cosmic-ray observation system

    NASA Astrophysics Data System (ADS)

    Briz, Susana; Anzalone, Anna; Isgrò, Francesco; Cremonini, Roberto; Tabone, Ilaria; Bertainav, Mario; Rodríguez, Irene; Fernández-Gómez, Isabel; de Castro, Antonio J.

    2015-03-01

    The main telescope of JEM-EUSO will determine Ultra High Energy Cosmic Ray properties by measuring the UV fluorescence light generated in the interaction between the cosmic rays and the atmosphere. Therefore, cloud information is crucial for a proper interpretation of the data. JEM-EUSO will observe the clouds in the field of view of the telescope making use of an atmospheric monitoring system, which consists of a LIDAR and an IR Camera. To retrieve the cloud top height from IR images two different methodologies will be used. The first one is based on stereo vision algorithms and requires two different views of the same scene. The second one is based on the relationship between the cloud top temperature and the cloud top height. From the IR camera the brightness temperature can be retrieved, thus the developed Split Window Algorithm retrieves the real cloud temperature from the brightness temperature in two spectral bands. This article presents a preliminary work, in which both methodologies are compared with the height given by MODIS. The stereo system is provided by the two geostationary satellites MSG-2 and MSG-3. The Split Window Algorithm has been tested in MODIS images of bands 31 and 32. This initial work is a first step to compare a very simplified version of both methodologies.

  18. Deep Convective Cloud Top Heights and Their Thermodynamic Control During CRYSTAL-FACE

    NASA Technical Reports Server (NTRS)

    Sherwood, Steven C.; Minnis, Patrick; McGill, Matthew

    2004-01-01

    Infrared (11 micron) radiances from GOES-8 and local radiosonde profiles, collected during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) in July 2002, are used to assess the vertical distribution of Florida-area deep convective cloud top height and test predictions as to its variation based on parcel theory. The highest infrared tops (Z(sub 11)) reached approximately to the cold point, though there is at least a 1-km uncertainty due to unknown cloud-environment temperature differences. Since lidar shows that visible 'tops' are 1 km or more above Z(sub 11), visible cloud tops frequently penetrated the lapse-rate tropopause (approx. 15 km). Further, since lofted ice content may be present up to approx. 1 km above the visible tops, lofting of moisture through the mean cold point (15.4 km) was probably common. Morning clouds, and those near Key West, rarely penetrated the tropopause. Non-entraining parcel theory (i.e., CAPE) does not successfully explain either of these results, but can explain some of the day-to-day variations in cloud top height over the peninsula. Further, moisture variations above the boundary layer account for most of the day-today variability not explained by CAPE, especially over the oceans. In all locations, a 20% increase in mean mixing ratio between 750 and 500 hPa was associated with about 1 km deeper maximum cloud penetration relative to the neutral level. These results suggest that parcel theory may be useful for predicting changes in cumulus cloud height over time, but that parcel entrainment must be taken into account even for the tallest clouds. Accordingly, relative humidity above the boundary layer may exert some control on the height of the tropical troposphere.

  19. Comparing different methods to retrieve cloud top height from Meteosat satellite data

    NASA Astrophysics Data System (ADS)

    Tabone, I.; Briz, S.; Anzalone, A.; De Castro, A. J.; Lopez, F.; Ferrarese, S.; Isgrò, F.; Cassardo, C.; Cremonini, R.; Bertaina, M.

    2015-10-01

    Cloud parameters such as the Cloud Top Height (CTH), Cloud Top Temperature (CTT), emissivity, particle size and optical depth have always been matter of interest for the atmospheric community. Particularly the CTH provides information leading to better understand the cloud radiative effects. Although there are many meteorological satellites providing the CTH, there are other sensors, not devoted to this purpose, that give some information from which this crucial parameter can be estimated. In this contribution we will describe three different methodologies to retrieve the CTH. The first technique is based on stereo-vision algorithms and requires two different views of the same scene and does not need of extra atmospheric information. In the second one, brightness temperatures in two IR spectral bands are converted to real cloud temperature by means of the proposed algorithms. From the CTT, the CTH is estimated using temperature vertical profiles (measured or modeled). The third technique retrieves the CTH from the output parameters of post event simulations performed by a Numerical Weather Prediction (NWP) model that in this work will be the mesoscale model WRF (Weather Research Forecast). This article presents a preliminary work, in which the heights retrieved by the three methodologies applied to the geostationary satellite Meteosat 10 are compared with the heights given by MODIS sensor installed on the polar satellite AQUA. This promising results show that valuable information about CTH can be retrieved from Meteosat which provide high frequency and large scale data useful for weather and climate research.

  20. A Simple Stochastic Model for Generating Broken Cloud Optical Depth and Top Height Fields

    NASA Technical Reports Server (NTRS)

    Prigarin, Sergei M.; Marshak, Alexander

    2007-01-01

    A simple and fast algorithm for generating two correlated stochastic twodimensional (2D) cloud fields is described. The algorithm is illustrated with two broken cumulus cloud fields: cloud optical depth and cloud top height retrieved from Moderate Resolution Imaging Spectrometer (MODIS). Only two 2D fields are required as an input. The algorithm output is statistical realizations of these two fields with approximately the same correlation and joint distribution functions as the original ones. The major assumption of the algorithm is statistical isotropy of the fields. In contrast to fractals and the Fourier filtering methods frequently used for stochastic cloud modeling, the proposed method is based on spectral models of homogeneous random fields. For keeping the same probability density function as the (first) original field, the method of inverse distribution function is used. When the spatial distribution of the first field has been generated, a realization of the correlated second field is simulated using a conditional distribution matrix. This paper is served as a theoretical justification to the publicly available software that has been recently released by the authors and can be freely downloaded from http://i3rc.gsfc.nasa.gov/Public codes clouds.htm. Though 2D rather than full 3D, stochastic realizations of two correlated cloud fields that mimic statistics of given fields have proved to be very useful to study 3D radiative transfer features of broken cumulus clouds for better understanding of shortwave radiation and interpretation of the remote sensing retrievals.

  1. Cloud Height Retrieval with Oxygen A and B bands for the Deep Space Climate Observatory (DSCOVR) Mission

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Marshak, A.; Lyapustin, A.; Wang, Y.; Mao, J.; Meyer, K.; Herman, J. R.

    2011-12-01

    At the Earth's L1 Lagrangian point, the Deep Space Climate Observatory (DSCOVR) would see the whole sunlit half of the Earth and would provide simultaneous data on cloud and aerosol properties from its Earth Polychromatic Imaging Camera (EPIC). EPIC images the Earth on a 2Kx2K CCD array, which gives a horizontal resolution of about 10 km at nadir. A filter-wheel provides consecutive images in 10 spectral channels ranging from the UV to the near-IR, including the oxygen A and B bands, which are designed for cloud height retrievals. In this talk, we will present the progress on EPIC cloud height retrieval using Oxygen A and B band. As the first step, a study on the effect of cloud phase, particle size, optical depth, extinction coefficient, cloud fraction, sun-view geometry, and surface type on the cloud height determination is conducted. Second, based on the simple Lambertian cloud reflectance model, two cloud pressure retrieval algorithms are developed: one utilizes the absolute radiances at the Oxygen A and B bands and the other uses the radiance ratios between the absorption and reference channels of the two bands. Third, a cloud height retrieval model that is suitable for operational use is implemented. Test results with the data from the EPIC simulator will be presented.

  2. Tornado occurrences related to overshooting cloud-top heights as determined from ATS pictures

    NASA Technical Reports Server (NTRS)

    Fujita, T. T.

    1972-01-01

    A sequence of ATS 3 pictures including the development history of large anvil clouds near Salina, Kansas was enlarged by NASA into 8X negatives which were used to obtain the best quality prints by mixing scan lines in 8 steps to minimize checker-board patterns. These images resulted in the best possible resolution, permitting use to compute the heights of overshooting tops above environmental anvil levels based on cloud shadow relationships along with the techniques of lunar topographic mapping. Of 39 heights computed, 6 were within 15 miles of reported positions of 3 tornadoes. It was found that the tornado proximity tops were mostly less than 5000 ft, with one exception of 7000 ft, suggesting that tornadoes are most likely to occur when overshooting height decreases. In order to simulate surface vortices induced by cloud-scale rotation and updraft fields, a laboratory model was constructed. The model experiment has shown that the rotation or updraft field induces a surface vortex but their combination does prevent the formation of the surface vortex. This research leads to a conclusion that the determination of the cloud-top topography and its time variation is of extreme importance in predicting severe local storms for a period of 0 to 6 hours.

  3. A new algorithm for detecting cloud height using OMPS/LP measurements

    NASA Astrophysics Data System (ADS)

    Chen, Zhong; DeLand, Matthew; Bhartia, Pawan K.

    2016-03-01

    The Ozone Mapping and Profiler Suite Limb Profiler (OMPS/LP) ozone product requires the determination of cloud height for each event to establish the lower boundary of the profile for the retrieval algorithm. We have created a revised cloud detection algorithm for LP measurements that uses the spectral dependence of the vertical gradient in radiance between two wavelengths in the visible and near-IR spectral regions. This approach provides better discrimination between clouds and aerosols than results obtained using a single wavelength. Observed LP cloud height values show good agreement with coincident Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) measurements.

  4. A Comparison of Several Techniques to Assign Heights to Cloud Tracers.

    NASA Astrophysics Data System (ADS)

    Nieman, Steven J.; Schmetz, Johannes; Menzel, W. Paul

    1993-09-01

    Satellite-derived cloud-motion vector (CMV) production has been troubled by inaccurate height assignment of cloud tracers, especially in thin semitransparent clouds. This paper presents the results of an intercomparison of current operational height assignment techniques. Currently, heights are assigned by one of three techniques when the appropriate spectral radiance measurements are available. The infrared window (IRW) technique compares measured brightness temperatures to forecast temperature profiles and thus infers opaque cloud levels. In semitransparent or small subpixel clouds, the carbon dioxide (CO2) technique uses the ratio of radiances from different layers of the atmosphere to infer the correct cloud height. In the water vapor (H2O) technique, radiances influenced by upper-tropospheric moisture and IRW radiances are measured for several pixels viewing different cloud amounts, and their linear relationship is used to extrapolate the correct cloud height. The results presented in this paper suggest that the H2O technique is a viable alternative to the CO2 technique for inferring the heights of semitransparent cloud elements. This is important since future National Environmental Satellite, Data, and Information Service (NESDIS) operations will have to rely on H20-derived cloud-height assignments in the wind field determinations with the next operational geostationary satellite. On a given day, the heights from the two approaches compare to within 60 110 hPa rms; drier atmospheric conditions tend to reduce the effectiveness of the H2O technique. By inference one can conclude that the present height algorithms used operationally at NESDIS (with the C02 technique) and at the European Satellite Operations Center (ESOC) (with their version of the H20 technique) are providing similar results. Sample wind fields produced with the ESOC and NESDIS algorithms using Meteosat-4 data show good agreement.

  5. Arctic PBL Cloud Height and Motion Retrievals from MISR and MINX

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.

    2012-01-01

    How Arctic clouds respond and feedback to sea ice loss is key to understanding of the rapid climate change seen in the polar region. As more open water becomes available in the Arctic Ocean, cold air outbreaks (aka. off-ice flow from polar lows) produce a vast sheet of roll clouds in the planetary boundary layer (PBl). The cold air temperature and wind velocity are the critical parameters to determine and understand the PBl structure formed under these roll clouds. It has been challenging for nadir visible/IR sensors to detect Arctic clouds due to lack of contrast between clouds and snowy/icy surfaces. In addition) PBl temperature inversion creates a further problem for IR sensors to relate cloud top temperature to cloud top height. Here we explore a new method with the Multiangle Imaging Spectro-Radiometer (MISR) instrument to measure cloud height and motion over the Arctic Ocean. Employing a stereoscopic-technique, MISR is able to measure cloud top height accurately and distinguish between clouds and snowy/icy surfaces with the measured height. We will use the MISR INteractive eXplorer (MINX) to quantify roll cloud dynamics during cold-air outbreak events and characterize PBl structures over water and over sea ice.

  6. Remote Sensing of Cloud Top Heights Using the Research Scanning Polarimeter

    NASA Technical Reports Server (NTRS)

    Sinclair, Kenneth; van Diedenhoven, Bastiaan; Cairns, Brian; Yorks, John; Wasilewski, Andrzej

    2015-01-01

    Clouds cover roughly two thirds of the globe and act as an important regulator of Earth's radiation budget. Of these, multilayered clouds occur about half of the time and are predominantly two-layered. Changes in cloud top height (CTH) have been predicted by models to have a globally averaged positive feedback, however observational changes in CTH have shown uncertain results. Additional CTH observations are necessary to better and quantify the effect. Improved CTH observations will also allow for improved sub-grid parameterizations in large-scale models and accurate CTH information is important when studying variations in freezing point and cloud microphysics. NASA's airborne Research Scanning Polarimeter (RSP) is able to measure cloud top height using a novel multi-angular contrast approach. RSP scans along the aircraft track and obtains measurements at 152 viewing angles at any aircraft location. The approach presented here aggregates measurements from multiple scans to a single location at cloud altitude using a correlation function designed to identify the location-distinct features in each scan. During NASAs SEAC4RS air campaign, the RSP was mounted on the ER-2 aircraft along with the Cloud Physics Lidar (CPL), which made simultaneous measurements of CTH. The RSPs unique method of determining CTH is presented. The capabilities of using single and combinations of channels within the approach are investigated. A detailed comparison of RSP retrieved CTHs with those of CPL reveal the accuracy of the approach. Results indicate a strong ability for the RSP to accurately identify cloud heights. Interestingly, the analysis reveals an ability for the approach to identify multiple cloud layers in a single scene and estimate the CTH of each layer. Capabilities and limitations of identifying single and multiple cloud layers heights are explored. Special focus is given to sources of error in the method including optically thin clouds, physically thick clouds, multi-layered clouds as well as cloud phase. When determining multi-layered CTHs, limits on the upper clouds opacity are assessed.

  7. Height correction based on multiple subimage correlation

    NASA Astrophysics Data System (ADS)

    Fan, Rong; Wang, Yuehuan

    2015-12-01

    In this paper, a height correction approach is proposed based on multiple sub-image correlation in remote sensing and navigation systems. First, multiple subareas are selected in the reference image, combination of two of which consists of the two for height correction. Then the measured distance and real distance between two areas can be computed by correlation matching and perspective transformation model. With the distances, height deviation can be estimated for further processing. Considering the accuracy-loss caused by image blurring, noise, changes of scales and so on, the approach utilizes clustering method to improve accuracy. Experiments show that the proposed method can estimate the height deviation automatically and the accuracy of the proposed method is equivalent to that based on manually labeled.

  8. A development of cloud top height retrieval using thermal infrared spectra observed with GOSAT and comparison with CALIPSO data

    NASA Astrophysics Data System (ADS)

    Someya, Yu; Imasu, Ryoichi; Saitoh, Naoko; Ota, Yoshifumi; Shiomi, Kei

    2016-05-01

    An algorithm based on CO2 slicing, which has been used for cirrus cloud detection using thermal infrared data, was developed for high-resolution radiance spectra from satellites. The channels were reconstructed based on sensitivity height information of the original spectral channels to reduce the effects of measurement errors. Selection of the reconstructed channel pairs was optimized for several atmospheric profile patterns using simultaneous studies assuming a cloudy sky. That algorithm was applied to data by the Greenhouse gases Observing SATellite (GOSAT). Results were compared with those obtained from the space-borne lidar instrument on-board Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Monthly mean cloud amounts from the slicing generally agreed with those from CALIPSO observations despite some differences caused by surface temperature biases, optically very thin cirrus, multilayer structures of clouds, extremely low cloud tops, and specific atmospheric conditions. Comparison of coincident data showed good agreement, except for some cases, and revealed that the improved slicing method is more accurate than the traditional slicing method. Results also imply that improved slicing can detect low-level clouds with cloud top heights as low as approximately 1.5 km.

  9. Are Satellite-Retrieved Correlations Between Cloud-Top-Height and Aerosol Optical Depth Evidence of Aerosol Invigoration of Convection?

    NASA Astrophysics Data System (ADS)

    Stier, P.; Gryspeerdt, E.; Grandey, B. S.; Wagner, T. M.; Kipling, Z.

    2013-12-01

    A robust negative correlation between cloud top pressure (CTP) and aerosol optical depth (AOD) has been documented in a number of studies and triggered hypotheses on aerosol invigoration of convective clouds. However, correlation based analysis is limited in its explanatory power as it does not directly establish physical causality between the correlated properties which may be cross-correlated with other meteorological factors. In this study we combine the global aerosol-climate model ECHAM-HAM with mechanistic coupling of the aerosol microphysics (HAM) to the two-moment cloud microphysics in the Convective Cloud Field Model (CCFM) and satellite data from SEVIRI, MODIS, ISCCP, CALIOP and CloudSat. CCFM explicitly simulates a spectrum of convective cloud top heights within each grid box, providing enhanced realism over traditional mass flux schemes. Consistency is established through sampling of the models at satellite overpass times and the use of ISCCP and COSP satellite simulators in the model. We employ this setup to investigate the contributions of aerosol-cloud interactions and meteorological cross-correlations to AOD--CTP correlations. Our analysis shows that a significant fraction of the observed AOD-CTP relationship is driven by the meteorological link between CTP and cloud fraction (CF), which itself is strongly linked to AOD via the humidification of aerosol in humid (hence preferentially cloudy) environments. Our results shed light on this controversial issue with potentially significant climate implications and emphasise the difficulty to constrain for meteorological variability in observational studies of aerosol-cloud interactions.

  10. Cloud-top Height Esimation Method by Geostationary Satellite Split-Window Measurements Trained with CALIPSO and CloudSat data

    NASA Astrophysics Data System (ADS)

    Nishi, Noriyuki; Hamada, Atsushi; Hirose, Hitoshi

    2015-04-01

    We released a database of cloud top height and visible optical thickness (CTOP) with one-hour resolution over the tropical western Pacific and Maritime Continent, by using infrared split-window data of the geostationary satellites (MTSAT) (http://database.rish.kyoto-u.ac.jp/arch/ctop/). We made lookup tables for estimating cloud top height only with geostationary infrared observations by comparing them with the direct cloud observation by CloudSat (Hamada and Nishi, 2010, JAMC). We picked out the same-time observations by MTSAT and CloudSat and regressed the cloud top height observation of CloudSat back onto 11 micro m brightness temperature (Tb) and the difference between the 11 micro m Tb and 12 micro m Tb of MTSAT. The database contains digital data and quick look images from Jul 2005 to real time and the area in 85E-155W (MTSAT2) and 20S-20N. Though the CTOP dataset is particularly useful for the upper tropospheric clouds, it has one serious problem. The cloud radar onboard CloudSat cannot well detect the optically thin cirrus clouds composed of small ice crystals and misses a certain part of cirriform clouds in the upper troposphere. In order to overcome this weakness, we are now making next version of the CTOP by using the lidar data (CALIOP) onboard CALIPSO satellite. One problem on the use of lidar observation is that they observe very thin cirrus formed around the tropopause. The main purpose of CTOP dataset is to provide the top height of clouds that originate from cloud clusters including cumulonimbus and nimbostratus, not of in-situ cirrus clouds formed near the tropopause. To exclude the very thin tropopause cirrus, we define cloud-top height of CALIOP observation as the height at which the optical depth accumulated from the cloud top is 0.2, instead of the CALIOP cloud top itself. With this criterion we can succeed in estimating the top height of cirruiform clouds, but it has another problem for thick clouds like cumulonimbus. For such clouds, the height of accumulated optical depth 0.2 is considerably lower than the real cloud top, possibly due to rather small number of large cloud particles near the top. Therefore, the estimation using CloudSat data is closer to the real top for the thick clouds, while that using CALIOP data is closer for cirriform clouds. So we are now making a lookup table with using both CloudSat and CALIPSO data to estimate cloud-top heights both for thick and thin clouds seamlessly.

  11. Synergy of stereo cloud top height and ORAC optimal estimation cloud retrieval: evaluation and application to AATSR

    NASA Astrophysics Data System (ADS)

    Fisher, Daniel; Poulsen, Caroline A.; Thomas, Gareth E.; Muller, Jan-Peter

    2016-03-01

    In this paper we evaluate the impact on the cloud parameter retrievals of the ORAC (Optimal Retrieval of Aerosol and Cloud) algorithm following the inclusion of stereo-derived cloud top heights as a priori information. This is performed in a mathematically rigorous way using the ORAC optimal estimation retrieval framework, which includes the facility to use such independent a priori information. Key to the use of a priori information is a characterisation of their associated uncertainty. This paper demonstrates the improvements that are possible using this approach and also considers their impact on the microphysical cloud parameters retrieved. The Along-Track Scanning Radiometer (AATSR) instrument has two views and three thermal channels, so it is well placed to demonstrate the synergy of the two techniques. The stereo retrieval is able to improve the accuracy of the retrieved cloud top height when compared to collocated Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), particularly in the presence of boundary layer inversions and high clouds. The impact of the stereo a priori information on the microphysical cloud properties of cloud optical thickness (COT) and effective radius (RE) was evaluated and generally found to be very small for single-layer clouds conditions over open water (mean RE differences of 2.2 (±5.9) microns and mean COD differences of 0.5 (±1.8) for single-layer ice clouds over open water at elevations of above 9 km, which are most strongly affected by the inclusion of the a priori).

  12. Retrieval of cloud fraction and height anomalies and their trend from temporally and spatially averaged infrared spectra observed from space

    NASA Astrophysics Data System (ADS)

    Kato, S.; Rose, F. G.; Liu, X.; Wielicki, B. A.; Mlynczak, M. G.

    2013-12-01

    Understanding how clouds and atmospheric properties change with time under radiative forcing is necessary to understand feedback. Generally, global clouds and atmospheric Understanding how clouds and atmospheric properties change with time under radiative forcing is necessary to understand feedback. Generally, global clouds and atmospheric properties are retrieved from satellite-based instruments. Subsequently, retrieved values from an instrument's field-of-view are averaged and the time rate of change of cloud or atmospheric properties can be inferred from averaged properties. This is simple in concept but identifying artifacts of the retrieval is difficult in practice. An alternative way to derive a trend of cloud and atmospheric properties is tying their property change directly to the observed radiance change. This average-then-retrieve approach directly utilizes instrument stability but requires separating cloud and atmospheric property changes contributing to the highly spatially and temporally averaged observed radiance change. In this presentation, we demonstrate the average-then-retrieve approach by simulating the retrieval of cloud fraction and height anomalies from highly averaged longwave spectra. We use 28 years of reanalysis (Modern Era Retrospective-Analysis for Research MERRA) for the simulation and retrieve annual 10° zonal cloud fraction and height anomalies, as well as temperature and water vapor amount anomalies. The error in retrieved anomalies is estimated based on the method discussed in Kato et al. (2011). The uncertainty in the trend estimated from retrieved anomalies is also discussed. Reference Kato, S., B. A. Wielicki, F. G. Rose, X. Liu, P. C. Taylor, D. P. Kratz, M. G. Mlynczak, D. F. Young, N. Phojanamongkolkij, S. Sun-Mack, W. F. Miller, Y. Chen, 2011b, Detection of atmospheric changes in spatially and temporally averaged infrared spectra observed from space, J Climate, 24, 6392-6407, Doi: 10.1175/JCLI-D-10-05005.1.

  13. AATSR Based Volcanic Ash Plume Top Height Estimation

    NASA Astrophysics Data System (ADS)

    Virtanen, Timo H.; Kolmonen, Pekka; Sogacheva, Larisa; Sundstrom, Anu-Maija; Rodriguez, Edith; de Leeuw, Gerrit

    2015-06-01

    The AATSR Correlation Method (ACM) height estimation algorithm is presented. The algorithm uses Advanced Along Track Scanning Radiometer (AATSR) satellite data to detect volcanic ash plumes and to estimate the plume top height. The height estimate is based on the stereo-viewing capability of the AATSR instrument, which allows to determine the parallax between the satellite's nadir and 55° forward views, and thus the corresponding height. AATSR provides an advantage compared to other stereo-view satellite instruments: with AATSR it is possible to detect ash plumes using brightness temperature difference between thermal infrared (TIR) channels centered at 11 and 12 μm. The automatic ash detection makes the algorithm efficient in processing large quantities of data: the height estimate is calculated only for the ash-flagged pixels. Besides ash plumes, the algorithm can be applied to any elevated feature with sufficient contrast to the background, such as smoke and dust plumes and clouds. The ACM algorithm can be applied to the Sea and Land Surface Temperature Radiometer (SLSTR), scheduled for launch at the end of 2015.

  14. Global cloud top height retrieval using SCIAMACHY limb spectra: model studies and first results

    NASA Astrophysics Data System (ADS)

    Eichmann, K.-U.; Lelli, L.; von Savigny, C.; Sembhi, H.; Burrows, J. P.

    2015-08-01

    Cloud top heights (CTH) were retrieved for the period 1 January 2003 to 7 April 2012 using height-resolved limb spectra measured with the Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on board ENVISAT (ENVIronmental SATellite). In this study, we tested the sensitivity of the colour index method used in the retrieval code SCODA (SCIAMACHY Cloud Detection Algorithm) and the accuracy of the retrieved CTHs in comparison to other methods. Sensitivity studies using the radiative transfer model SCIATRAN showed that the method is capable of generally detecting cloud tops down to about 5 km and very thin cirrus clouds even up to the tropopause. Volcanic particles can also be detected that occasionally reach the lower stratosphere. Low clouds at 2-3 km can only be retrieved under very clean atmospheric conditions, as light scattering of aerosols interferes with the cloud retrieval. Upper tropospheric ice clouds are detectable for cloud optical depths down to about τN = 0.005, which is in the subvisual range. The detection sensitivity decreases towards the surface. An optical thickness of roughly 0.1 was the lower detection limit for water cloud top heights at 5 km. This value is much lower than thresholds reported for the passive cloud detection in nadir viewing direction. Comparisons with SCIAMACHY nadir cloud top heights, calculated with the Semi-Analytical CloUd Retrieval Algorithm (SACURA), showed a good agreement in the global cloud field distribution. But only opaque clouds (τN > 5) are detectable with the nadir passive retrieval technique in the UV-visible and infrared wavelength range. So due to the frequent occurrence of thin and sub-visual cirrus clouds in the tropics, large cloud top height deviations were detected between both viewing geometries. Also the land/sea contrast seen in nadir retrievals was not detected in limb mode. Co-located cloud top height measurements of the limb viewing Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on ENVISAT for the period from January 2008 to March 2012 were compared, showing good agreement to within 1 km, which is smaller than the vertical field of view of both instruments. Lower stratospheric aerosols from volcanic eruptions occasionally interfered with the cloud retrieval and inhibited detection of tropospheric clouds. Examples of the impact of these events are shown for the volcanoes Kasatochi in August 2008, Sarychev Peak in June 2009, and Nabro in June 2010. Long-lasting aerosol layers were detected after these events in the Northern Hemisphere down to the tropics. Particle top heights up to about 22 km were retrieved in 2009, when the enhanced lower stratospheric aerosol layer persisted for about 7 months. Up to about 82 % of the Northern hemispheric lower stratosphere between 30° and 70° was covered by scattering particles in August 2009 and nearly half in October 2008.

  15. Automatic analysis of stereoscopic satellite image pairs for determination of cloud-top height and structure

    NASA Technical Reports Server (NTRS)

    Hasler, A. F.; Strong, J.; Woodward, R. H.; Pierce, H.

    1991-01-01

    Results are presented on an automatic stereo analysis of cloud-top heights from nearly simultaneous satellite image pairs from the GOES and NOAA satellites, using a massively parallel processor computer. Comparisons of computer-derived height fields and manually analyzed fields show that the automatic analysis technique shows promise for performing routine stereo analysis in a real-time environment, providing a useful forecasting tool by augmenting observational data sets of severe thunderstorms and hurricanes. Simulations using synthetic stereo data show that it is possible to automatically resolve small-scale features such as 4000-m-diam clouds to about 1500 m in the vertical.

  16. Effects of explosively venting aerosol-sized particles through earth-containment systems on the cloud-stabilization height

    SciTech Connect

    Dyckes, G.W.

    1980-07-01

    A method of approximating the cloud stabilization height for aerosol-sized particles vented explosively through earth containment systems is presented. The calculated values for stabilization heights are in fair agreement with those obtained experimentally.

  17. A geometric photography model for determining cloud top heights using MISR images

    NASA Astrophysics Data System (ADS)

    He, Yongjian; Qiu, Xinfa; Sun, Zhian; Li, Qiang

    2015-10-01

    Cloud top height (CTH) is an important factor in weather forecasting and monitoring. An accurate CTH has scientific significance for improving the quality of both weather analyses and numerical weather prediction. The three-dimensional geometric method has been widely recognized as a CTH calculation method that provides relatively high accuracy. In this paper, we used the theory of digital photogrammetry and remote sensing technology to establish a geometric photography model (GPM) that can simultaneously determine CTHs and cloud movement speed (CMS) by introducing the CMS into the collinearity equation of photogrammetry. The CTH is derived by constructing three-dimensional image pairs of multitemporal Multiangle Imaging Spectroradiometer (MISR) red spectral band images from three angles. Compared with CTHs observed by ground-based lidar at the United States Southern Great Plains, the difference of CTHs using the GPM relative to the reference value was less than 300 m. By analyzing the ground control points, the GPM error is estimated to be approximately 300 m. Compared with MISR CTH data, the CTHs calculated in this study were similar to that of MISR without wind.

  18. Cloud Height Retrieval with Oxygen A and B Bands for the Deep Space Climate Observatory (DSCOVR) Mission

    NASA Technical Reports Server (NTRS)

    Yang, Yuekui; Marshak, Alexander; Mao, Jianping; Lyapustin, Alexei; Herman, Jay

    2012-01-01

    Planned to fly in 2014, the Deep Space Climate Observatory (DSCOVR) would see the whole sunlit half of the Earth from the L 1 Lagrangian point and would provide simultaneous data on cloud and aerosol properties with its Earth Polychromatic Imaging Camera (EPIC). EPIC images the Earth on a 2Kx2K CCD array, which gives a horizontal resolution of about 10 km at nadir. A filter-wheel provides consecutive images in 10 spectral channels ranging from the UV to the near-IR, including the oxygen A and B bands. This paper presents a study of retrieving cloud height with EPIC's oxygen A and B bands. As the first step, we analyzed the effect of cloud optical and geometrical properties, sun-view geometry, and surface type on the cloud height determination. Second, we developed two cloud height retrieval algorithms that are based on the Mixed Lambertian-Equivalent Reflectivity (MLER) concept: one utilizes the absolute radiances at the Oxygen A and B bands and the other uses the radiance ratios between the absorption and reference channels of the two bands. Third, we applied the algorithms to the simulated EPIC data and to the data from SCanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY) observations. Results show that oxygen A and B bands complement each other: A band is better suited for retrievals over ocean, while B band is better over vegetated land due to a much darker surface. Improvements to the MLER model, including corrections to surface contribution and photon path inside clouds, will also be discussed.

  19. Satellite and Surface Data Synergy for Developing a 3D Cloud Structure and Properties Characterization Over the ARM SGP. Stage 1: Cloud Amounts, Optical Depths, and Cloud Heights Reconciliation

    NASA Technical Reports Server (NTRS)

    Genkova, I.; Long, C. N.; Heck, P. W.; Minnis, P.

    2003-01-01

    One of the primary Atmospheric Radiation Measurement (ARM) Program objectives is to obtain measurements applicable to the development of models for better understanding of radiative processes in the atmosphere. We address this goal by building a three-dimensional (3D) characterization of the cloud structure and properties over the ARM Southern Great Plains (SGP). We take the approach of juxtaposing the cloud properties as retrieved from independent satellite and ground-based retrievals, and looking at the statistics of the cloud field properties. Once these retrievals are well understood, they will be used to populate the 3D characterization database. As a first step we determine the relationship between surface fractional sky cover and satellite viewing angle dependent cloud fraction (CF). We elaborate on the agreement intercomparing optical depth (OD) datasets from satellite and ground using available retrieval algorithms with relation to the CF, cloud height, multi-layer cloud presence, and solar zenith angle (SZA). For the SGP Central Facility, where output from the active remote sensing cloud layer (ARSCL) valueadded product (VAP) is available, we study the uncertainty of satellite estimated cloud heights and evaluate the impact of this uncertainty for radiative studies.

  20. Multi-Sensor Analysis of Cloud-Top Height in Sc - Cu Transition Regions

    NASA Astrophysics Data System (ADS)

    Ludewig, E.; Horvath, A.

    2010-12-01

    In the eastern basins of the subtropical oceans unbroken sheets of stratocumulus transition to fields of scattered cumulus as boundary-layer air masses advect equatorward in the trades. This shift in cloud regimes is the subject of intense modeling efforts, because it has profound effects on the local and the planetary albedo. To provide observational constraints for such modeling studies, we analyzed satellite measurements of boundary-layer cloud-top heights (CTHs) in the northeast and southeast Atlantic and Pacific. Our sensor suite comprised CALIPSO-CALIOP, MODIS, MISR, and Meteosat-9. The study covered the summer months June-August and September-November for the northern and southern hemisphere, respectively, spanning the period 2006-2009. We considered CALIOP lidar measurements the most accurate and, hence, used them as reference. The operational Collection 5 MODIS CTHs were based on fitting measured cloud-top temperatures (CTTs) to forecast temperature profiles and were known to have large biases in case of low-level inversions. Therefore, we also evaluated CTHs derived from CTT-SST differences and various lapse rate formulations, which is the method suggested for the upcoming Collection 6 dataset. The MISR stereo CTHs were computed from a purely geometric method, which, however, is rather sensitive to errors in along-track wind speed. Because our previous work indicated a MISR cross-swath speed bias, we created a modified CTH dataset by replacing MISR winds with Meteosat-9 winds to correct the raw MISR stereo heights. The various satellite retrievals were then compared over whole regions as well as along characteristic Sc-Cu transition trajectories computed with the HYSPLIT model. For context, results from LES transition simulations were also analyzed. Some highlights of our study are summarized below. The CALIOP, MISR, and lapse-rate-based MODIS CTHs all showed a systematic increase of 500-700 m in the southeast Atlantic and northeast Pacific as Sc transitioned to Cu. In the northeast Atlantic and southeast Pacific, however, these CTHs had no obvious trends and remained fairly constant. Operational MODIS CTHs indicated an erroneously decreasing trend along transition trajectories in all four regions due to large (500-1500 m) overestimations in the Sc regime (although they were fairly reasonable in the Cu regime). The best MODIS dataset was a hybrid one combining current operational retrievals and lapse-rate-based heights depending on the presence or lack of low-level inversions. Overall, MISR CTHs compared most favorably to CALIOP with typical correlations and biases of 0.7 and 150 m, respectively. In the southeast Atlantic, MISR CTH errors could be further reduced by 15-30% when using Meteosat-9 winds for height correction, thereby removing apparent cross-swath biases.

  1. Automatic determination of trunk diameter, crown base and height of scots pine (Pinus Sylvestris L.) Based on analysis of 3D point clouds gathered from multi-station terrestrial laser scanning. (Polish Title: Automatyczne okreslanie srednicy pnia, podstawy korony oraz wysokosci sosny zwyczajnej (Pinus Silvestris L.) Na podstawie analiz chmur punktow 3D pochodzacych z wielostanowiskowego naziemnego skanowania laserowego)

    NASA Astrophysics Data System (ADS)

    Ratajczak, M.; Wężyk, P.

    2015-12-01

    Rapid development of terrestrial laser scanning (TLS) in recent years resulted in its recognition and implementation in many industries, including forestry and nature conservation. The use of the 3D TLS point clouds in the process of inventory of trees and stands, as well as in the determination of their biometric features (trunk diameter, tree height, crown base, number of trunk shapes), trees and lumber size (volume of trees) is slowly becoming a practice. In addition to the measurement precision, the primary added value of TLS is the ability to automate the processing of the clouds of points 3D in the direction of the extraction of selected features of trees and stands. The paper presents the original software (GNOM) for the automatic measurement of selected features of trees, based on the cloud of points obtained by the ground laser scanner FARO. With the developed algorithms (GNOM), the location of tree trunks on the circular research surface was specified and the measurement was performed; the measurement covered the DBH (l: 1.3m), further diameters of tree trunks at different heights of the tree trunk, base of the tree crown and volume of the tree trunk (the selection measurement method), as well as the tree crown. Research works were performed in the territory of the Niepolomice Forest in an unmixed pine stand (Pinussylvestris L.) on the circular surface with a radius of 18 m, within which there were 16 pine trees (14 of them were cut down). It was characterized by a two-storey and even-aged construction (147 years old) and was devoid of undergrowth. Ground scanning was performed just before harvesting. The DBH of 16 pine trees was specified in a fully automatic way, using the algorithm GNOM with an accuracy of +2.1%, as compared to the reference measurement by the DBH measurement device. The medium, absolute measurement error in the cloud of points - using semi-automatic methods "PIXEL" (between points) and PIPE (fitting the cylinder) in the FARO Scene 5.x., showed the error, 3.5% and 5.0%,.respectively The reference height was assumed as the measurement performed by the tape on the cut tree. The average error of automatic determination of the tree height by the algorithm GNOM based on the TLS point clouds amounted to 6.3% and was slightly higher than when using the manual method of measurements on profiles in the TerraScan (Terrasolid; the error of 5.6%). The relatively high value of the error may be mainly related to the small number of points TLS in the upper parts of crowns. The crown height measurement showed the error of +9.5%. The reference in this case was the tape measurement performed already on the trunks of cut pine trees. Processing the clouds of points by the algorithms GNOM for 16 analyzed trees took no longer than 10 min. (37 sec. /tree). The paper mainly showed the TLS measurement innovation and its high precision in acquiring biometric data in forestry, and at the same time also the further need to increase the degree of automation of processing the clouds of points 3D from terrestrial laser scanning.

  2. Comparing Icesat/glas Based Elevation Heights with Photogrammetric Terrain Heights from Uav-Imagery on the East Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Enßle, F.; Fritz, A.; Koch, B.

    2015-08-01

    Digital elevation models (DEMs) and height measurements are broadly used in environmental studies. Two common elevation sources are the Ice Cloud and land elevation Satellite (ICESat), which acquired laser range measurements with the Geoscience Laser Altimeter System (GLAS) across the globe and elevation data from the Shuttle Radar Topography Mission (SRTM). Current developments of small unmanned aerial vehicles (UAV) provide the opportunity to collect aerial images of remote areas at a high spatial resolution. These can be further processed to digital surface models by stereophotogrammetry and provide a reliable data source to evaluate coarse scale Digital Elevation Models (DEMs). This study compares ICESat/GLAS and SRTM90 elevation data against photogrammetric terrain heights within GLAS footprints on high altitudes on the East Tibetan Plateau. Without vegetation-bias, we were able to examine height differences under different topographic conditions and of different acquisition dates. Several resampling techniques were applied to SRTM90 data and averaged height within each footprint was calculated. ICESat/GLAS heights (n = 148) are most similar to UAV data based elevations with an averaged difference of -0.8m ±3.1m. Results furthermore indicate the validity of ICESat/GLAS heights, which are usually removed from analyses by applying different quality flags. Smallest difference of SRTM90 to UAV based heights could be observed by a natural neighbour resampling technique (averaged 3.6m ±14m), whereat other techniques achieved quite similar results. It can be confirmed that within a range of 3,800-4,200m above mean sea level the ICESat/GLAS heights are a precise source to determine elevation at footprint geolocation.

  3. CloudSat-Constrained Cloud Ice Water Path and Cloud Top Height Retrievals from MHS 157 and 183.3 GHz Radiances

    NASA Technical Reports Server (NTRS)

    Gong, J.; Wu, D. L.

    2014-01-01

    Ice water path (IWP) and cloud top height (ht) are two of the key variables in determining cloud radiative and thermodynamical properties in climate models. Large uncertainty remains among IWP measurements from satellite sensors, in large part due to the assumptions made for cloud microphysics in these retrievals. In this study, we develop a fast algorithm to retrieve IWP from the 157, 183.3+/-3 and 190.3 GHz radiances of the Microwave Humidity Sounder (MHS) such that the MHS cloud ice retrieval is consistent with CloudSat IWP measurements. This retrieval is obtained by constraining the empirical forward models between collocated and coincident measurements of CloudSat IWP and MHS cloud-induced radiance depression (Tcir) at these channels. The empirical forward model is represented by a lookup table (LUT) of Tcir-IWP relationships as a function of ht and the frequency channel.With ht simultaneously retrieved, the IWP is found to be more accurate. The useful range of the MHS IWP retrieval is between 0.5 and 10 kg/sq m, and agrees well with CloudSat in terms of the normalized probability density function (PDF). Compared to the empirical model, current operational radiative transfer models (RTMs) still have significant uncertainties in characterizing the observed Tcir-IWP relationships. Therefore, the empirical LUT method developed here remains an effective approach to retrieving ice cloud properties from the MHS-like microwave channels.

  4. A neural network approach for monitoring of volcanic SO2 and cloud height using hyperspectral measurements

    NASA Astrophysics Data System (ADS)

    Piscini, Alessandro; Carboni, Elisa; Del Frate, Fabio; Grainger, Roy Gordon

    2014-10-01

    In this study two neural networks were implemented in order to emulate a retrieval model and to estimate the sulphur dioxide (SO2) columnar content and cloud height from volcanic eruption. ANNs were trained using all Infrared Atmospheric Sounding Interferometer (IASI) channels in Thermal Infrared (TIR) as inputs, and the corresponding values of SO2 content and height of volcanic cloud obtained using the Oxford SO2 retrievals as target outputs. The retrieval is demonstrated for the eruption of the Eyjafjallajökull volcano (Iceland) occurred in 2010 and to three IASI images of the Grímsvötn volcanic eruption that occurred in May 2011, in order to evaluate the networks for an unknown eruption. The results of validation, both for Eyjafjallajökull independent data-sets, provided root mean square error (RMSE) values between neural network outputs and targets lower than 20 DU for SO2 total column and 200 mb for cloud height, therefore demonstrating the feasibility to estimate SO2 values using a neural network approach, and its importance in near real time monitoring activities, owing to its fast application. Concerning the validation carried out with neural networks on images from the Grímsvötn eruption, the RMSE of the outputs remained lower than the Standard Deviation (STD) of targets, and the neural network underestimated retrieval only where target outputs showed different statistics than those used during the training phase.

  5. Accuracy analysis of height difference models derived from terrestrial laser scanning point clouds

    NASA Astrophysics Data System (ADS)

    Glira, Philipp; Briese, Christian; Pfeifer, Norbert; Dusik, Jana; Hilger, Ludwig; Neugirg, Fabian; Baewert, Henning

    2014-05-01

    In many research areas the temporal development of the earth surface topography is investigated for geomorphological analysis (e.g. landslide monitoring). Terrestrial laser scanning (TLS) often is used for this purpose, as it allows a fast and detailed 3d reconstruction of the sampled object. The temporal development of the earth surface usually is investigated on the basis of rasterized data, i.e. digital terrain models (DTM). The difference between two DTMs - the difference model - should preferably correspond to the terrain height changes occurred between the measurement campaigns. Actually, these height differences can be influenced by numerous potential error sources. The height accuracy of each raster cell is affected primarily by (a) the measurement accuracy of the deployed TLS, (b) the terrain topography (e.g. roughness), (c) the registration accuracy, (d) the georeferencing accuracy and (e) the raster interpolation method. Thus, in this contribution, height differences are treated as stochastic variables in order to estimate their precision. For an accurate estimation of the height difference precision a detailed knowledge about the whole processing pipeline (from the raw point clouds to the final difference model) is essential. In this study, first the height difference precision is estimated by a rigorous error propagation. As main result, for each raster cell of the difference model, a corresponding height error is estimated, forming an error map. A statistical hypothesis test is presented in order to judge the significance of a height difference. Furthermore, in order to asses the effect of single factors on the final height difference precision, multivariate statistic methods are applied. This analysis allows the deduction of a simple error propagation model, neglecting error sources with small impact on the final precision. The proposed method is demonstrated by means of TLS data acquired at the Gepatschferner (Tyrol, Austria). This study was carried out within the research project PROSA (high-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps).

  6. The upper clouds of Venus: Determination of the scale height from NIMS-Galileo infrared data

    NASA Technical Reports Server (NTRS)

    Roos, M.; Drossart, P.; Encrenaz, TH.; Lellouch, E.; Bezard, B.; Carlson, R. W.; Baines, K. H.; Kamp, L. W.; Taylor, F. W.; Collard, A. D.

    1993-01-01

    The 3-5 micrometer thermal emission of the nightside of Venus, recorded by the Near-Infrared Mapping Spectrometer (NIMS) instrument at the time of the Galileo flyby of Venus, is analysed to infer the properties of the upper cloud boundary. From the global maps of Venus at fixed wavelengths, the limb darkening of the flux is measured at several latitudes, within each infrared channel. By using the nominal Pioneer Venus thermal profile, these data give access to two parameters: the cloud deck temperature and the cloud scale height. It is verified independently, from the NIMS spectra, that this thermal profile is consistent with all the NIMS observations, and that the thermal structure does not vary significantly in the latitude range (25 deg S, 30 deg N). Within this range, the cloud scale height is found to be constant with latitude, and is H = 5.2 km, with an accuracy of about 15%, taking into account the various sources of theoretical and observational uncertainties. At higher latitudes, the temperature profile becomes more isothermal and the presented method to retrieve H is no longer valid.

  7. Cloud Based Applications and Platforms (Presentation)

    SciTech Connect

    Brodt-Giles, D.

    2014-05-15

    Presentation to the Cloud Computing East 2014 Conference, where we are highlighting our cloud computing strategy, describing the platforms on the cloud (including Smartgrid.gov), and defining our process for implementing cloud based applications.

  8. Remote sensing of cloud top pressure/height from SEVIRI: analysis of ten current retrieval algorithms

    NASA Astrophysics Data System (ADS)

    Hamann, U.; Walther, A.; Baum, B.; Bennartz, R.; Bugliaro, L.; Derrien, M.; Francis, P.; Heidinger, A.; Joro, S.; Kniffka, A.; Le Gléau, H.; Lockhoff, M.; Lutz, H.-J.; Meirink, J. F.; Minnis, P.; Palikonda, R.; Roebeling, R.; Thoss, A.; Platnick, S.; Watts, P.; Wind, G.

    2014-01-01

    The role of clouds remains the largest uncertainty in climate projections. They influence solar and thermal radiative transfer and the earth's water cycle. Therefore, there is an urgent need for accurate cloud observations to validate climate models and to monitor climate change. Passive satellite imagers measuring radiation at visible to thermal infrared wavelengths provide a wealth of information on cloud properties. Among others, the cloud top height (CTH) - a crucial parameter to estimate the thermal cloud radiative forcing - can be retrieved. In this paper we investigate the skill of ten current retrieval algorithms to estimate the CTH using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard Meteosat Second Generation (MSG). In the first part we compare the ten SEVIRI cloud top pressure (CTP) datasets with each other. The SEVIRI algorithms catch the latitudinal variation of the CTP in a similar way. The agreement is better in the extratropics than in the tropics. In the tropics multi-layer clouds and thin cirrus layers complicate the CTP retrieval, whereas good agreement is found for the cores of the deep convective system having a high optical depth. Furthermore, a good agreement between the algorithms is observed for trade wind cumulus and marine stratocumulus clouds. In the second part of the paper the SEVIRI retrievals are compared to CTH observations from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR) instruments. It is important to note that the different measurement techniques cause differences in the retrieved CHT data. SEVIRI measures a radiatively effective CTH, while the CTH of the active instruments is derived from the return time of the emitted signal. Therefore some systematic diffrences are expected. On average the CTHs detected by the SEVIRI algorithms are 1.0 to 2.5 km lower than CALIOP observations, and the correlation coefficients between the SEVIRI and the CALIOP datasets range between 0.77 and 0.90. The mean CTH differences between the SEVIRI algorithms and CPR observations are smaller than for CALIOP ranging from -0.8 km to 0.6 km. The correlation coefficients of CPR and SEVIRI observations range between 0.82 and 0.89. To discuss the origin of the CTH deviation we elaborate the comparison for three cloud categories: optically thin and thick single layer as well as multi-layer clouds. For optically thick clouds the correlation coefficients between the SEVIRI and the reference datasets are usually above 0.95. For optically thin single layer clouds the correlation coefficients are still above 0.92. For this cloud category the SEVIRI algorithms yield CTHs that are lower than CALIOP but similar to CPR observations. Most challenging are the multi-layer clouds, where the correlation coefficients are for most algorithms between 0.6 and 0.8. Finally, we evaluate the performance of the SEVIRI retrievals for boundary layer clouds. While the CTH retrieval for this cloud type is relatively accurate, there are still considerable differences between the algorithms. These are related to uncertainties in and limited vertical resolution of the assumed temperature profiles in combination with the presence of temperature inversions, which lead to ambiguities in the CTH retrieval. Alternative approaches for the CTH retrieval of low clouds are discussed.

  9. Remote Sensing of Cloud Top Height from SEVIRI: Analysis of Eleven Current Retrieval Algorithms

    NASA Technical Reports Server (NTRS)

    Hamann, U.; Walther, A.; Baum, B.; Bennartz, R.; Bugliaro, L.; Derrien, M.; Francis, P. N.; Heidinger, A.; Joro, S.; Kniffka, A.; Le Gleau, H.; Lockhoff, M.; Lutz, H.-J.; Meirink, J. F.; Minnis, P.; Palikonda, R.; Roebeling, R.; Thoss, A.; Platnick, S.; Watts, P.; Wind, G.

    2014-01-01

    The role of clouds remains the largest uncertainty in climate projections. They influence solar and thermal radiative transfer and the earth's water cycle. Therefore, there is an urgent need for accurate cloud observations to validate climate models and to monitor climate change. Passive satellite imagers measuring radiation at visible to thermal infrared (IR) wavelengths provide a wealth of information on cloud properties. Among others, the cloud top height (CTH) - a crucial parameter to estimate the thermal cloud radiative forcing - can be retrieved. In this paper we investigate the skill of ten current retrieval algorithms to estimate the CTH using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard Meteosat Second Generation (MSG). In the first part we compare ten SEVIRI cloud top pressure (CTP) data sets with each other. The SEVIRI algorithms catch the latitudinal variation of the CTP in a similar way. The agreement is better in the extratropics than in the tropics. In the tropics multi-layer clouds and thin cirrus layers complicate the CTP retrieval, whereas a good agreement among the algorithms is found for trade wind cumulus, marine stratocumulus and the optically thick cores of the deep convective system. In the second part of the paper the SEVIRI retrievals are compared to CTH observations from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR) instruments. It is important to note that the different measurement techniques cause differences in the retrieved CTH data. SEVIRI measures a radiatively effective CTH, while the CTH of the active instruments is derived from the return time of the emitted radar or lidar signal. Therefore, some systematic differences are expected. On average the CTHs detected by the SEVIRI algorithms are 1.0 to 2.5 kilometers lower than CALIOP observations, and the correlation coefficients between the SEVIRI and the CALIOP data sets range between 0.77 and 0.90. The average CTHs derived by the SEVIRI algorithms are closer to the CPR measurements than to CALIOP measurements. The biases between SEVIRI and CPR retrievals range from -0.8 kilometers to 0.6 kilometers. The correlation coefficients of CPR and SEVIRI observations vary between 0.82 and 0.89. To discuss the origin of the CTH deviation, we investigate three cloud categories: optically thin and thick single layer as well as multi-layer clouds. For optically thick clouds the correlation coefficients between the SEVIRI and the reference data sets are usually above 0.95. For optically thin single layer clouds the correlation coefficients are still above 0.92. For this cloud category the SEVIRI algorithms yield CTHs that are lower than CALIOP and similar to CPR observations. Most challenging are the multi-layer clouds, where the correlation coefficients are for most algorithms between 0.6 and 0.8. Finally, we evaluate the performance of the SEVIRI retrievals for boundary layer clouds. While the CTH retrieval for this cloud type is relatively accurate, there are still considerable differences between the algorithms. These are related to the uncertainties and limited vertical resolution of the assumed temperature profiles in combination with the presence of temperature inversions, which lead to ambiguities in the CTH retrieval. Alternative approaches for the CTH retrieval of low clouds are discussed.

  10. Remote sensing of cloud top pressure/height from SEVIRI: analysis of ten current retrieval algorithms

    NASA Astrophysics Data System (ADS)

    Hamann, U.; Walther, A.; Baum, B.; Bennartz, R.; Bugliaro, L.; Derrien, M.; Francis, P. N.; Heidinger, A.; Joro, S.; Kniffka, A.; Le Gléau, H.; Lockhoff, M.; Lutz, H.-J.; Meirink, J. F.; Minnis, P.; Palikonda, R.; Roebeling, R.; Thoss, A.; Platnick, S.; Watts, P.; Wind, G.

    2014-09-01

    The role of clouds remains the largest uncertainty in climate projections. They influence solar and thermal radiative transfer and the earth's water cycle. Therefore, there is an urgent need for accurate cloud observations to validate climate models and to monitor climate change. Passive satellite imagers measuring radiation at visible to thermal infrared (IR) wavelengths provide a wealth of information on cloud properties. Among others, the cloud top height (CTH) - a crucial parameter to estimate the thermal cloud radiative forcing - can be retrieved. In this paper we investigate the skill of ten current retrieval algorithms to estimate the CTH using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard Meteosat Second Generation (MSG). In the first part we compare ten SEVIRI cloud top pressure (CTP) data sets with each other. The SEVIRI algorithms catch the latitudinal variation of the CTP in a similar way. The agreement is better in the extratropics than in the tropics. In the tropics multi-layer clouds and thin cirrus layers complicate the CTP retrieval, whereas a good agreement among the algorithms is found for trade wind cumulus, marine stratocumulus and the optically thick cores of the deep convective system. In the second part of the paper the SEVIRI retrievals are compared to CTH observations from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR) instruments. It is important to note that the different measurement techniques cause differences in the retrieved CTH data. SEVIRI measures a radiatively effective CTH, while the CTH of the active instruments is derived from the return time of the emitted radar or lidar signal. Therefore, some systematic differences are expected. On average the CTHs detected by the SEVIRI algorithms are 1.0 to 2.5 km lower than CALIOP observations, and the correlation coefficients between the SEVIRI and the CALIOP data sets range between 0.77 and 0.90. The average CTHs derived by the SEVIRI algorithms are closer to the CPR measurements than to CALIOP measurements. The biases between SEVIRI and CPR retrievals range from -0.8 km to 0.6 km. The correlation coefficients of CPR and SEVIRI observations vary between 0.82 and 0.89. To discuss the origin of the CTH deviation, we investigate three cloud categories: optically thin and thick single layer as well as multi-layer clouds. For optically thick clouds the correlation coefficients between the SEVIRI and the reference data sets are usually above 0.95. For optically thin single layer clouds the correlation coefficients are still above 0.92. For this cloud category the SEVIRI algorithms yield CTHs that are lower than CALIOP and similar to CPR observations. Most challenging are the multi-layer clouds, where the correlation coefficients are for most algorithms between 0.6 and 0.8. Finally, we evaluate the performance of the SEVIRI retrievals for boundary layer clouds. While the CTH retrieval for this cloud type is relatively accurate, there are still considerable differences between the algorithms. These are related to the uncertainties and limited vertical resolution of the assumed temperature profiles in combination with the presence of temperature inversions, which lead to ambiguities in the CTH retrieval. Alternative approaches for the CTH retrieval of low clouds are discussed.

  11. 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.

  12. A new 500-m resolution map of canopy height for Amazon forest using spaceborne LiDAR and cloud-free MODIS imagery

    NASA Astrophysics Data System (ADS)

    Sawada, Yoshito; Suwa, Rempei; Jindo, Keiji; Endo, Takahiro; Oki, Kazuo; Sawada, Haruo; Arai, Egidio; Shimabukuro, Yosio Edemir; Celes, Carlos Henrique Souza; Campos, Moacir Alberto Assis; Higuchi, Francisco Gasparetto; Lima, Adriano José Nogueira; Higuchi, Niro; Kajimoto, Takuya; Ishizuka, Moriyoshi

    2015-12-01

    In the present study, we aimed to map canopy heights in the Brazilian Amazon mainly on the basis of spaceborne LiDAR and cloud-free MODIS imagery with a new method (the Self-Organizing Relationships method) for spatial modeling of the LiDAR footprint. To evaluate the general versatility, we compared the created canopy height map with two different canopy height estimates on the basis of our original field study plots (799 plots located in eight study sites) and a previously developed canopy height map. The compared canopy height estimates were obtained by: (1) a stem diameter at breast height (D) - tree height (H) relationship specific to each site on the basis of our original field study, (2) a previously developed D-H model involving environmental and structural factors as explanatory variables (Feldpausch et al., 2011), and (3) a previously developed canopy height map derived from the spaceborne LiDAR data with different spatial modeling method and explanatory variables (Simard et al., 2011). As a result, our canopy height map successfully detected a spatial distribution pattern in canopy height estimates based on our original field study data (r = 0.845, p = 8.31 × 10-3) though our canopy height map showed a poor correlation (r = 0.563, p = 0.146) with the canopy height estimate based on a previously developed model by Feldpausch et al. (2011). We also confirmed that the created canopy height map showed a similar pattern with the previously developed canopy height map by Simard et al. (2011). It was concluded that the use of the spaceborne LiDAR data provides a sufficient accuracy in estimating the canopy height at regional scale.

  13. A physically based algorithm for non-blackbody correction of the cloud top temperature for the convective clouds

    NASA Astrophysics Data System (ADS)

    Wang, C.; Luo, Z. J.; Chen, X.; Zeng, X.; Tao, W.; Huang, X.

    2012-12-01

    Cloud top temperature is a key parameter to retrieval in the remote sensing of convective clouds. Passive remote sensing cannot directly measure the temperature at the cloud tops. Here we explore a synergistic way of estimating cloud top temperature by making use of the simultaneous passive and active remote sensing of clouds (in this case, CloudSat and MODIS). Weighting function of the MODIS 11μm band is explicitly calculated by feeding cloud hydrometer profiles from CloudSat retrievals and temperature and humidity profiles based on ECMWF ERA-interim reanalysis into a radiation transfer model. Among 19,699 tropical deep convective clouds observed by the CloudSat in 2008, the averaged effective emission level (EEL, where the weighting function attains its maximum) is at optical depth 0.91 with a standard deviation of 0.33. Furthermore, the vertical gradient of CloudSat radar reflectivity, an indicator of the fuzziness of convective cloud top, is linearly proportional to, d_{CTH-EEL}, the distance between the EEL of 11μm channel and cloud top height (CTH) determined by the CloudSat when d_{CTH-EEL}<0.6km. Beyond 0.6km, the distance has little sensitivity to the vertical gradient of CloudSat radar reflectivity. Based on these findings, we derive a formula between the fuzziness in the cloud top region, which is measurable by CloudSat, and the MODIS 11μm brightness temperature assuming that the difference between effective emission temperature and the 11μm brightness temperature is proportional to the cloud top fuzziness. This formula is verified using the simulated deep convective cloud profiles by the Goddard Cumulus Ensemble model. We further discuss the application of this formula in estimating cloud top buoyancy as well as the error characteristics of the radiative calculation within such deep-convective clouds.

  14. Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

    SciTech Connect

    Liu, Y.; Wu, W.; Jensen, M. P.; Toto, T.

    2011-07-21

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surface-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fraction, and cloud albedo. The analytical expression is then used to deduce a new approach for inferring cloud albedo from concurrent surface-based measurements of downwelling surface shortwave radiation and cloud fraction. High-resolution decade-long data on cloud albedos are obtained by use of this surface-based approach over the US Department of Energy's Atmospheric Radiaton Measurement (ARM) Program at the Great Southern Plains (SGP) site. The surface-based cloud albedos are further compared against those derived from the coincident GOES satellite measurements. The three long-term (1997-2009) sets of hourly data on shortwave cloud radiative forcing, cloud fraction and cloud albedo collected over the SGP site are analyzed to explore the multiscale (diurnal, annual and inter-annual) variations and covariations. The analytical formulation is useful for diagnosing deficiencies of cloud-radiation parameterizations in climate models.

  15. Novel Spectrograph/Radiometer for Cloud Top Height Measurement Using Three Complementary Techniques

    NASA Technical Reports Server (NTRS)

    Park, Hongwoo; Soulen, Peter F.; Prasad, Coorg R.

    1997-01-01

    A proof-of-concept (POC) instrument system to measure cloud top height from space using three complementary techniques is presented. These techniques use measurements of: (1) thermal infrared (IR); (2) molecular oxygen 'A' band absorption; and (3) filling-in of Fraunhofer lines (the Ring effect), respectively. Combining three techniques is achieved with a single grating spectrograph with bandpass and order sorting filters by measuring I I jim radiation from the zeroth order of the grating for the IR, 750-780 nm radiation from the first order for the 'A' band absorption, and 390-400 mn radiation from the second order for the Ca K and H Fraunhofer line filling-in effect. The POC system and its measurement results with the POC system are described.

  16. Cloud-Based Data Storage

    ERIC Educational Resources Information Center

    Waters, John K.

    2011-01-01

    The vulnerability and inefficiency of backing up data on-site is prompting school districts to switch to more secure, less troublesome cloud-based options. District auditors are pushing for a better way to back up their data than the on-site, tape-based system that had been used for years. About three years ago, Hendrick School District in

  17. Cloud-Based Data Storage

    ERIC Educational Resources Information Center

    Waters, John K.

    2011-01-01

    The vulnerability and inefficiency of backing up data on-site is prompting school districts to switch to more secure, less troublesome cloud-based options. District auditors are pushing for a better way to back up their data than the on-site, tape-based system that had been used for years. About three years ago, Hendrick School District in…

  18. Registration of point cloud data for HDD stamped base inspection

    NASA Astrophysics Data System (ADS)

    Suh, Sungho; Cho, Hansang

    2015-09-01

    As a part of the HDD manufacturing process, HDD stamped base, an exterior container, is one of the most essential components in which various parts become assembled to compose a hard disk drive (HDD). Height errors that are caused by pressing, breaking or cracking can occur on the base, because it is designed by a stamping method. In order to detect the height errors, the inspection process is essential in the production fields. In the current industry, CMM (Coordinate Measurement Machine) is one of the representative machines that inspect certain regions on the product. The machine probes a designated point by an operator and judges the defect by comparing the height of the point to the originally designed height. However, the method takes much time to inspect each designated point resulting in a total of 17 minutes. In order to reduce the total inspection time, we propose an inspection method using 3D point cloud data acquired from a holographic sensor. To compare the height from acquired 3D point cloud data with the one from the originally designed CAD data, the exact point cloud registration is important. There are differences between 2D image registration and 3D point cloud registration, such as translation on each plane, rotation, tilt, and nonlinear transformations. The relationship between the acquired 3D point cloud data and the originally designed CAD data can be obtained by projective transformation. If the projective transformation matrix between the two is obtained, 3D point cloud data registration can be performed. In order to calculate 3D projective transformation matrix, corresponding points between 3D point cloud data and CAD data are required. To find the corresponding points, we use the height map which is projected from 3D point cloud data onto XY plane. The height map has pixel intensity from the height value of each point. If the height maps from 3D point cloud data and CAD data are matched, corresponding points can be estimated. As one of the features of the HDD stamped base, there are multiple circles on the base. In this paper, we find the corresponding points between 3D point cloud data and CAD data using circle fitting, and obtain 2D Affine transformation matrix from the corresponding points. By applying 2D Affine transformation matrix to height map, the corresponding points on the 3D coordinate can be obtained. Using such points, we propose the method designed to achieve 3D projective transformation matrix. To find the proper 3D projective transformation matrix, we formulate a cost function which uses the relationship of the corresponding points. Also the proper 3D projective transformation matrix can be calculated by minimizing the cost function. Then the 3D point cloud data can be matched to CAD data and the height values of each point of 3D point cloud can be compared to the CAD data.

  19. 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,

  20. Research on ionospheric tomography based on variable pixel height

    NASA Astrophysics Data System (ADS)

    Zheng, Dunyong; Li, Peiqing; He, Jie; Hu, Wusheng; Li, Chaokui

    2016-05-01

    A novel ionospheric tomography technique based on variable pixel height was developed for the tomographic reconstruction of the ionospheric electron density distribution. The method considers the height of each pixel as an unknown variable, which is retrieved during the inversion process together with the electron density values. In contrast to conventional computerized ionospheric tomography (CIT), which parameterizes the model with a fixed pixel height, the variable-pixel-height computerized ionospheric tomography (VHCIT) model applies a disturbance to the height of each pixel. In comparison with conventional CIT models, the VHCIT technique achieved superior results in a numerical simulation. A careful validation of the reliability and superiority of VHCIT was performed. According to the results of the statistical analysis of the average root mean square errors, the proposed model offers an improvement by 15% compared with conventional CIT models.

  1. The conditional risk probability-based seawall height design method

    NASA Astrophysics Data System (ADS)

    Yang, Xing; Hu, Xiaodong; Li, Zhiqing

    2015-11-01

    The determination of the required seawall height is usually based on the combination of wind speed (or wave height) and still water level according to a specified return period, e.g., 50-year return period wind speed and 50-year return period still water level. In reality, the two variables are be partially correlated. This may be lead to over-design (costs) of seawall structures. The above-mentioned return period for the design of a seawall depends on economy, society and natural environment in the region. This means a specified risk level of overtopping or damage of a seawall structure is usually allowed. The aim of this paper is to present a conditional risk probability-based seawall height design method which incorporates the correlation of the two variables. For purposes of demonstration, the wind speeds and water levels collected from Jiangsu of China are analyzed. The results show this method can improve seawall height design accuracy.

  2. Integration of Satellite-Derived Cloud Phase, Cloud Top Height, and Liquid Water Path into an Operational Aircraft Icing Nowcasting System

    NASA Technical Reports Server (NTRS)

    Haggerty, Julie; McDonough, Frank; Black, Jennifer; Landott, Scott; Wolff, Cory; Mueller, Steven; Minnis, Patrick; Smith, William, Jr.

    2008-01-01

    Operational products used by the U.S. Federal Aviation Administration to alert pilots of hazardous icing provide nowcast and short-term forecast estimates of the potential for the presence of supercooled liquid water and supercooled large droplets. The Current Icing Product (CIP) system employs basic satellite-derived information, including a cloud mask and cloud top temperature estimates, together with multiple other data sources to produce a gridded, three-dimensional, hourly depiction of icing probability and severity. Advanced satellite-derived cloud products developed at the NASA Langley Research Center (LaRC) provide a more detailed description of cloud properties (primarily at cloud top) compared to the basic satellite-derived information used currently in CIP. Cloud hydrometeor phase, liquid water path, cloud effective temperature, and cloud top height as estimated by the LaRC algorithms are into the CIP fuzzy logic scheme and a confidence value is determined. Examples of CIP products before and after the integration of the LaRC satellite-derived products will be presented at the conference.

  3. Height estimations based on eye measurements throughout a gait cycle.

    PubMed

    Yang, Sylvia X M; Larsen, Peter K; Alkjær, Tine; Juul-Kristensen, Birgit; Simonsen, Erik B; Lynnerup, Niels

    2014-03-01

    Anthropometric measurements (e.g. the height to the head, nose tip, eyes or shoulders) of a perpetrator based on video material may be used in criminal cases. However, several height measurements may be difficult to assess as the perpetrators may be disguised by clothes or headwear. The eye height (EH) measurement, on the other hand, is less prone to concealment. The purpose of the present study was to investigate: (1) how the eye height varies during the gait cycle, and (2) how the eye height changes with head position. The eyes were plotted manually in APAS for 16 test subjects during a complete gait cycle. The influence of head tilt on the EH was investigated in 20 healthy men. Markers were attached to the face and the subjects were instructed to stand relaxed, tilt their head to the right, to the left, forward and backward. The marker data for the right eye were used to calculate the EH. The respective deviation and SD from the relaxed standing EH and the EH in the Frankfurt plane, left tilted, right tilted, forward tilted and backward tilted, in addition to the corresponding head tilt angles were calculated. There was no correlation between the height of the subject and the maximum vertical displacement of the EH throughout the gait cycle nor between height of the subjects and the variation of the EH throughout the gait cycle. The average maximum vertical displacement for the test subject group was 4.76 cm (± 1.56 cm). The average EH was lower when the subjects were standing in the relaxed position than in the Frankfurt plane. The average EH was higher in the relaxed position than when the subjects tilted their heads, except when they tilted their heads backwards. The subjects had a slightly larger range of motion to the right than to the left, which was not significant. The results of this study provide a range for eye height estimates and may be readily implemented in forensic case work. It can be used as a reference in height estimates in cases with height measurements based on time of the gait cycle and based on the degree of head tilt from video material. Our data also provide descriptive statistics which may be helpful when comparing eye height measurements of a perpetrator with one or more suspects. PMID:24503163

  4. Detection method for height limit based on compression encoding imaging

    NASA Astrophysics Data System (ADS)

    Hu, Jianchuan; Wei, Ping; Ke, Jun

    2015-12-01

    We put forward a new method based on compressed encoding imaging faced with detection for height limit. In the beginning of this paper, we focus on hadamard encoding, and analysis the SNR of hadamard encoding. Then, a new encoding matrix M based on hadamard matrix been put forward. Matrix M is suitable for the sparse image obtained from the detection for height limit, and implement easily on the DMD. Compressed encoding imaging simulation based on measurement matrix M have been done in our work, and demonstrates the feasibility of the design method.

  5. Subseasonal Vertical Correlations with MBL Cloud Top Heights over the Southeastern Pacific and Cloud Top Height/Vertical Velocity Relationships in a Baroclinic Atmosphere Using Satellite and Re-Analysis Data

    NASA Astrophysics Data System (ADS)

    Kubar, T. L.; Larson, V. E.; Stephens, G. L.; Wood, R.; Lebsock, M. D.

    2014-12-01

    MBL cloud top height (Ztop) is a reflection of the balance between several large-scale terms, including subsidence, which in isolation tends to suppress Ztop, and entrainment, which deepens Ztop, and is inversely proportional to stability. With the use of gridded daily MODIS L3 cloud data and state-of-the-art reanalysis data from ERA-Interim, we extend beyond the traditional constraints of defining stability/dynamic variables with one or two fixed levels by instead computing vertical correlations relative to Ztop. Along a southeast (SE) Pacific cross section centered at 20˚S from the coast to 140˚W, ϴ negatively correlates with Ztop not only just above cloud top, but throughout the lower free troposphere. Below cloud top, ϴ correlations with Ztopare fairly weak. More confounding relationships are found between profiles of pressure vertical velocity (ω) and both Ztop and MBL cloud fraction (CF); especially over the stratocumulus (Sc) and transitional regions, stronger ω (either near Ztop or aloft) is associated with deeper MBL clouds, anomalously low ϴ near and above Ztop, and slightly reduced CF. Over the trade cumulus region, enhanced subsidence is associated with an anomalously cold MBL, increased stability, and suppressed Ztop. For further elucidation, we visit the concept of a baroclinic atmosphere, in which the trough/ridge axes and ϴ anomalies tilt with height, albeit in opposite ways. Along our cross section, in the case of an anomalous surface high to the east of an upper-level high, an eastward tilt with height of ϴ is documented, especially over the transitional and Sc cloud regimes. Anomalous ridging aloft is strongly correlated with suppressed Ztop. Over the transitional and Sc regimes (east of ~105˚W), maximum ω anomalies are located directly between the upper-level anomalous ridge and trough axes. The coldest ϴ anomalies near and above Ztop are located just east of the maximum subsidence, corresponding to reduced stability, deeper Ztop, and a slight reduction of CF. Thus, the baroclinic structure between 100˚W and 70˚W can help explain the unexpected positive correlations between ω and Ztop. The relationships described between ω and Ztop may have implications for diagnosing low cloud feedbacks in other subtropical Sc areas as well, especially where baroclinicity is important.

  6. Satellite Inference of Thermals and Cloud Base Updraft Speeds Based on Retrieved Surface and Cloud Base Temperatures

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Rosenfeld, D.; Li, Z.

    2014-12-01

    Updraft speeds of thermals have always been difficult to measure, despite the significant role they play in transporting pollutants and in cloud formation and precipitation. In this study, updraft speeds measured by Doppler lidar are found to be correlated with the observed planetary boundary layer (PBL) and surface properties in the buoyancy-driven PBL over the Southern Great Plains (SGP) site operated by the U.S. Department of Energy's Atmospheric Radiation Program (ARM). Based on the found relationships, two approaches are proposed to estimate both maximum (Wmax ) and cloud base (Wb ) updraft speeds. The required input data are PBL height, 10-m horizontal wind speed, wind shear, surface skin temperature and 2-m air temperature. The application for remote sensing of updraft speeds in cloud-topped PBL from space was tested by using satellite-retrieved surface and cloud base temperature in combination with European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis data. Validation against lidar-measured updraft speeds indicates the feasibility of retrieving Wmax (root-mean-square error, RMSE, is 0.32 m/s) and Wb (RMSE is 0.42 m/s) for global coverage. This information is essential to advance the understanding of aerosol-cloud interactions. This method does not work for stable or mechanically-driven PBL.

  7. Height-based Indices of Pubertal Timing in Male Adolescents

    PubMed Central

    Khairullah, Ammar; May, Margaret T.; Tilling, Kate; Howe, Laura D.; Leonard, Gabriel; Perron, Michel; Richer, Louis; Veillette, Suzanne; Pausova, Zdenka; Paus, Tomáš

    2014-01-01

    It is important to account for timing of puberty when studying the adolescent brain and cognition. The use of classical methods for assessing pubertal status may not be feasible in some studies, especially in male adolescents. Using data from a sample of 478 males from a longitudinal birth cohort, we describe the calculations of three independent height-based markers of pubertal timing: Age at Peak Height Velocity (APHV), Height Difference in Standard Deviations (HDSDS), and Percent Achieved of Adult Stature (PAAS). These markers correlate well with each other. In a separate cross-sectional study, we show that the PAAS marker correlates well with testosterone levels and self-reported pubertal-stage scores. We conclude by discussing key considerations for investigators when drawing upon these methods of assessing pubertal timing. PMID:26052478

  8. Height gauge based on dual polarization competition laser

    NASA Astrophysics Data System (ADS)

    Zhao, Zhengqi; Zhang, Shulian; Li, Yan

    2011-03-01

    Based on dual polarization competition laser, we develop a new height gauge. By inserting a quartz crystal plate into the laser cavity, one laser beam splits into two orthogonally linear polarized laser beams, which appear one after another with the change in cavity length. After detecting their intensities, we obtain two power-turning curves. The longitudinal mode spacing is divided into 4 equal zones and each one has different intensity phenomena, which provides a new method of height measurement. According to experiments, the direct measuring range of this new method is 12 mm with resolution of 79.1 nm, and the indirect measuring range can be increased using first grade gauge blocks and a liftable platform. Compared to other height gauges such as vernier gauge, inductance sensor and gauge block interferometer, this new instrument has the advantage of self-calibration and simple structure without frequency stabilization system.

  9. 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.

  10. Aerosol cloud interaction: a multiplatform-scenario-based methodology

    NASA Astrophysics Data System (ADS)

    Landulfo, Eduardo; Lopes, Fabío. J. S.; Guerrero-Rascado, Juan Luis; Alados-Arboledas, Lucas

    2015-10-01

    Suspended atmospheric particles i.e. aerosol particles go through many chemical and physical processes and those interactions and transformations may cause particle change in size, structure and composition regulated by mechanisms, which are also present in clouds. These interactions play a great role in the radiation transfer in the atmosphere and are not completely understood as competing effects might occur which are known as indirect aerosol effects. Performing measurements and experiments in remote sensing to improve the knowledge of these processes are also a challenge. In face of that we propose a multi-platform approach based lidar, sun photometry and satellite observations which should be characterized under a scenario perspective in which given the cloud height, geometric and optical geometries in a diurnal/nocturnal basis will make possible to apply different analytical tools in each a set of product that specify the aerosol present in the vicinity of clouds, their optical and physical properties. These scenarios are meant to aid in tagging the expected products and help in creating a robust database to systematically study the aerosol-cloud interaction.In total we will present 6 scenarios: 3 under daylight conditions, 3 under at nighttime. Each scenario and their counterpart should be able to provide the cloud base/top height, aerosol backscattering profile and cloud optical/geometric thickness. In each instance we should count on a 5 wavelength Raman lidar system measurement, a collocated sun photometer and CALIPSO/MODIS observation from AQUA/TERRA platforms. To further improve the aerosol cloud interaction the Raman lidar system should have a water vapor channel or moreover a liquid water channel. In our study we will present a two-day case study to show the methodology feasibility and its potential application.

  11. The effects of cloud inhomogeneities upon radiative fluxes, and the supply of a cloud truth validation dataset

    NASA Technical Reports Server (NTRS)

    Welch, Ronald M.

    1993-01-01

    A series of cloud and sea ice retrieval algorithms are being developed in support of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Science Team objectives. These retrievals include the following: cloud fractional area, cloud optical thickness, cloud phase (water or ice), cloud particle effective radius, cloud top heights, cloud base height, cloud top temperature, cloud emissivity, cloud 3-D structure, cloud field scales of organization, sea ice fractional area, sea ice temperature, sea ice albedo, and sea surface temperature. Due to the problems of accurately retrieving cloud properties over bright surfaces, an advanced cloud classification method was developed which is based upon spectral and textural features and artificial intelligence classifiers.

  12. Satellite-observed cloud-top height changes in tornadic thunderstorms

    NASA Technical Reports Server (NTRS)

    Adler, R. F.; Fenn, D. D.

    1981-01-01

    Eleven tornadic storms are evaluated with respect to cloud top temperature changes relative to tornado touchdown. Digital IR data from the SMS/GOES geosynchronous satellites were employed for 10 F2 and one F1 tornadoes. A rapid ascent of the cloud tops 30-45 min before tornado touchdown, a temperature decrease of 0.4 K/min, and an ascent rate of about 3 m/sec were observed. The presence of an operating Doppler radar for three of the sample storms allowed detection of a mesocyclone coincident with the rapid cloud top ascent. The intensification and descent of the vortex to form a tornado is concluded to be due to a weakening of the updraft, the formation of a downdraft, and a shift of the vortex to the updraft-downdraft boundary, leading to dominance of the tilting term in the generation of vorticity.

  13. Stratocumulus cloud properties derived from simultaneous satellite and island-based instrumentation during FIRE

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Heck, Patrick W.; Young, David F.; Fairall, C. W.; Snider, J. B.

    1992-01-01

    Cloud parameters derived from visible and infrared window data from the Geostationary Operational Environmental Satellite (GOES) are compared to corresponding properties determined from instrumentation on San Nicolas Island off the coast of California during the First ISCCP Regional Experiment marine stratocumulus intensive field observations period in July 1987. Examination of the satellite imagery revealed that the apparent bias can be explained by the persistence of the clouds over the northwest part of the island during periods of clearing around the island. Diurnal variations in the cloud cover were very significant; minimum cloudiness occurred during the late afternoon and maximum cloudiness early in the morning. Relationships were established between the satellite-derived cloud optical depth and two surface-observed quantities: cloud liquid water path and cloud thickness. Simultaneous observations of liquid water path and satellite-derived cloud optical depth were used to infer effective cloud-droplet radius, resulting in good agreement with correlative data. The diurnal variations in cloud amount are accompanied by changes in cloud thickness, cloud-top height, cloud liquid water path, and effective droplet size. These observations provide the most complete picture, to date, of the diurnal cycle of marine stratocumulus clouds, confirming previous satellite-based inferences of the diurnal behavior of marine stratocumulus at larger scales.

  14. Comparison of spinal anesthesia dosage based on height and weight versus height alone in patients undergoing elective cesarean section

    PubMed Central

    Siddiqui, Khalid Maudood; Ullah, Hameed

    2016-01-01

    Background Spinal anesthesia with bupivacaine, typically used for elective and emergency cesarean section, is associated with a significant incidence of hypotension resulting from sympathetic blockade. A variety of dosing regimens have been used to administer spinal anesthesia for cesarean section. The objective of this study was to compare the incidence of hypotension following two different fixed dosing regimens. Methods This was a randomized double-blind clinical trial with a two-sided design, 5% significance level and 80% power. After approval of the hospital ethics review committee, 60 patients were divided randomly into two groups. In one group, the local anesthetic dose was adjusted according to height and weight, and in the other, the dose was adjusted according to height only. Results Sixty women with a singleton pregnancy were included. Of the factors that could affect dose and blood pressure, including age, weight, height, and dose, only height differed between the groups. Mean heart rate was similar between the groups. Hypotension was significantly more frequent with dosage based on height alone than with two-factor dose calculation (56.7% vs. 26.7%; P = 0.018). Conclusions Adjusting the dose of isobaric bupivacaine to a patient's height and weight provides adequate anesthesia for elective cesarean section and is associated with a decreased incidence and severity of maternal hypotension and less use of ephedrine. PMID:27066205

  15. A multi-spectral method for estimating cirrus cloud top heights

    NASA Technical Reports Server (NTRS)

    Shenk, W. E.; Curran, R. J.

    1973-01-01

    A two-channel method has been developed to estimate the altitude of cirrus clouds over ocean areas with an expected altitude error less than or equal to plus or minus 50 mb. Reflected radiation is used to estimate cirrus emissivity in the 10- to 11-micron spectral interval. The cirrus altitude is determined from the emissivity estimate, a registered 10- to 11-micron measurement, and a vertical temperature profile. Nimbus 3 medium-resolution infrared radiometer measurements were used to establish the relationship between reflectance and 11-micron cirrus emissivity.

  16. 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.

  17. The effects of cloud inhomogeneities upon radiative fluxes, and the supply of a cloud truth validation dataset. Semiannual progress report, 1 July-31 December 1992

    SciTech Connect

    Welch, R.M.

    1993-01-01

    A series of cloud and sea ice retrieval algorithms are being developed in support of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Science Team objectives. These retrievals include the following: cloud fractional area, cloud optical thickness, cloud phase (water or ice), cloud particle effective radius, cloud top heights, cloud base height, cloud top temperature, cloud emissivity, cloud 3-D structure, cloud field scales of organization, sea ice fractional area, sea ice temperature, sea ice albedo, and sea surface temperature. Due to the problems of accurately retrieving cloud properties over bright surfaces, an advanced cloud classification method was developed which is based upon spectral and textural features and artificial intelligence classifiers.

  18. Ground-based infrared remote sensing of cloud properties over the Antarctic plateau

    NASA Astrophysics Data System (ADS)

    Mahesh, Ashwin

    A Fourier-transform interferometer, operated throughout the year 1992 at South Pole Station, measured downward spectral longwave radiance from 550 to 1500 cm-1 (7-18 ?m) at a resolution of 1 cm-1. Radiance measurements were usually made twice daily, coincident with routine launches of radiosondes made by the South Pole Weather Office; 252 radiance measurements were of cloudy-sky conditions. Cloud-base heights are retrieved from these data using a ground-based version of the radiance-ratioing method, originally developed to retrieve cloud-top heights from satellite data. Frequencies in the R branch of the 15-?m CO 2 band are used, exploiting the variation of atmospheric opacity with wavenumber. A one-year climatology of cloud-base heights shows a bimodal distribution. Most clouds have bases in the lowest few hundred meters, within the surface-based temperature inversion. The other mode is of higher clouds with base heights 1.5-3 km above the surface. The retrieved cloud-base heights are in general uncorrelated with visual estimates made by observers at the South Pole Weather Office. The longwave atmospheric emission spectra are also used to infer optical thicknesses and ice crystal sizes. This method makes use of the cloud's emissivity at 10 ?m and 11 ?m wavelength and the cloud's transmittance of stratospheric ozone emission in the 9.6 ?m band. The difference in emissivity between 10 and 11 ?m is sensitive to ice particle size because the absorption coefficient of ice varies greatly between these two wavelengths. The retrieval of optical depth (expressed as its value in the geometric-optics limit, ?g) is limited to ?g < 5, and the effective particle radii r eff are distinguished only for reff < 25 ?m, but most (80%) of the clouds observed did have ?g and reff in the retrievable range. These clouds over the Antarctic interior are found to be optically thin, usually with ?g < 1, in contrast to coastal clouds which usually have ?g > 20. Most have reff in the range 5-25 ?m, with a mode at 15 ?m. The retrieved reff is larger in summer than in winter, in agreement with in-situ measurements.

  19. Cloud-based Architecture Capabilities Summary Report

    SciTech Connect

    Vang, Leng; Prescott, Steven R; Smith, Curtis

    2014-09-01

    In collaborating scientific research arena it is important to have an environment where analysts have access to a shared of information documents, software tools and be able to accurately maintain and track historical changes in models. A new cloud-based environment would be accessible remotely from anywhere regardless of computing platforms given that the platform has available of Internet access and proper browser capabilities. Information stored at this environment would be restricted based on user assigned credentials. This report reviews development of a Cloud-based Architecture Capabilities (CAC) as a web portal for PRA tools.

  20. The ESA Cloud CCI project: Generation of Multi Sensor consistent Cloud Properties with an Optimal Estimation Based Retrieval Algorithm

    NASA Astrophysics Data System (ADS)

    Jerg, M.; Stengel, M.; Hollmann, R.; Poulsen, C.

    2012-04-01

    The ultimate objective of the ESA Climate Change Initiative (CCI) Cloud project is to provide long-term coherent cloud property data sets exploiting and improving on the synergetic capabilities of past, existing, and upcoming European and American satellite missions. The synergetic approach allows not only for improved accuracy and extended temporal and spatial sampling of retrieved cloud properties better than those provided by single instruments alone but potentially also for improved (inter-)calibration and enhanced homogeneity and stability of the derived time series. Such advances are required by the scientific community to facilitate further progress in satellite-based climate monitoring, which leads to a better understanding of climate. Some of the primary objectives of ESA Cloud CCI Cloud are (1) the development of inter-calibrated radiance data sets, so called Fundamental Climate Data Records - for ESA and non ESA instruments through an international collaboration, (2) the development of an optimal estimation based retrieval framework for cloud related essential climate variables like cloud cover, cloud top height and temperature, liquid and ice water path, and (3) the development of two multi-annual global data sets for the mentioned cloud properties including uncertainty estimates. These two data sets are characterized by different combinations of satellite systems: the AVHRR heritage product comprising (A)ATSR, AVHRR and MODIS and the novel (A)ATSR - MERIS product which is based on a synergetic retrieval using both instruments. Both datasets cover the years 2007-2009 in the first project phase. ESA Cloud CCI will also carry out a comprehensive validation of the cloud property products and provide a common data base as in the framework of the Global Energy and Water Cycle Experiment (GEWEX). The presentation will give an overview of the ESA Cloud CCI project and its goals and approaches and then continue with results from the Round Robin algorithm comparison exercise carried out at the beginning of the project which included three algorithms. The purpose of the exercise was to assess and compare existing cloud retrieval algorithms in order to chose one of them as backbone of the retrieval system and also identify areas of potential improvement and general strengths and weaknesses of the algorithm. Furthermore the presentation will elaborate on the optimal estimation algorithm subsequently chosen to derive the heritage product and which is presently further developed and will be employed for the AVHRR heritage product. The algorithm's capabilities to coherently and simultaneously process all radiative input and yield retrieval parameters together with associated uncertainty estimates will be presented together with first results for the heritage product. In the course of the project the algorithm is being developed into a freely and publicly available community retrieval system for interested scientists.

  1. Biological ice nuclei at tropospheric cloud heights: potential conditioning of precipitation

    NASA Astrophysics Data System (ADS)

    Stopelli, Emiliano; Conen, Franz; Alewell, Christine; Morris, Cindy

    2014-05-01

    Different substances present in the atmosphere enhance the aggregation of water molecules into ice structures, but particularly effective seem to be aerosols of biological origin, active at temperatures up to -2°C. Yet, the relevance of biological ice nucleation for cloud processes, such as initiating precipitation, remains ambiguous. We try to understand the meteorological conditions and the environmental factors controlling the abundance of biological ice nuclei (IN) in precipitation. One full year of observations has been carried out at the High Altitude Research station of Jungfraujoch, in the Swiss Alps, 3580 m a.s.l. Fresh snow was collected each month and analysed immediately on site for the concentration of IN active at temperatures warmer than -12°C. For this purpose we had developed an innovative system automatically recording freezing events of samples in closed tubes. Additional information was gained through the recording of meteorological parameters associated with the precipitation events, and the determination of stable isotopes (2H and 18O) and of bacterial concentrations (direct epifluorescence microscope counting, live/dead staining) in precipitation. Our analysis of the data suggests that the abundance of ice nuclei in snowfall is characterized not only by seasonality, but also by the geographical origin of precipitating air masses. Further, it seems that the more water an air mass has lost through previous precipitation, the smaller is the biological IN abundance in the remaining precipitation. Moreover, the loss of biological IN with precipitation seems to be much faster than that of other suspended particles in the same air mass, pointing towards a role of biological IN in conditioning the development of precipitation at its early stages.

  2. Quantification of volcanic cloud top heights and thicknesses using A-train observations for the 2008 Chaitén eruption

    NASA Astrophysics Data System (ADS)

    Prata, A. T.; Siems, S. T.; Manton, M. J.

    2015-04-01

    New evidence of vertically thin (< 400 m), low-level (< 10 km) volcanic ash clouds, as well as confirmation of previously reported high-level (>10 km) ash clouds, from the May 2008 Chaitén eruption in southern Chile is presented. A-train remote sensors were used to measure high-resolution volcanic cloud top heights (VCTHs) during the explosive phase (2-10 May 2008) of the eruption. Ash clouds were identified using a reverse absorption technique applied to hyperspectral measurements taken by the Atmospheric Infrared Sounder. Once identified, heights and thicknesses were derived from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument. As these two instruments are part of the same constellation of satellites, coincident retrievals are routinely possible. Collocation of the data allowed for detection of volcanic ash within CALIOP profiles. Using a simple thresholding algorithm, VCTH and thickness were derived from the CALIOP profiles. A total of 12 VCTH measurements, ranging from 3.7 to 16.6 km, have been derived. Back trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory dispersion model were used as a check on volcanic origin of the detected ash clouds. Ensemble forward trajectories were generated to demonstrate how the new data could be used to improve Volcanic Ash Advisory Center operations. The findings reported here demonstrate several cases where low-level ash was not recorded previously and include observations of thin ash clouds at large distances (˜4000 km) from the volcano.

  3. Macrophysical and optical properties of midlatitude high-altitude clouds from 4 ground-based lidars and collocated CALIOP observations

    NASA Astrophysics Data System (ADS)

    Dupont, J. C.; Haeffelin, M.; Morille, Y.; Noel, V.; Keckhut, P.; Comstock, J.; Winker, D.; Chervet, P.; Roblin, A.

    2009-04-01

    Cirrus clouds not only play a major role in the energy budget of the Earth-Atmosphere system, but are also important in the hydrological cycle [Stephens et al., 1990; Webster, 1994]. According to satellite passive remote sensing, high-altitude clouds cover as much as 40% of the earth's surface on average (Liou 1986; Stubenrauch et al., 2006) and can reach 70% of cloud cover over the Tropics (Wang et al., 1996; Nazaryan et al., 2008). Hence, given their very large cloud cover, they have a major role in the climate system (Lynch et al. 2001). Cirrus clouds can be classified into three distinct families according to their optical thickness, namely subvisible clouds (OD<0.03), semi-transparent clouds (0.03clouds (0.3clouds represent 50% or more of cirrus cloud population. The radiative effects of cirrus clouds are found to be significant by many studies both at the top of the atmosphere and surface. The contribution of the subvisible and semi-transparent classes is strongly affected by levels of other scatterers in the atmosphere (gases, aerosols). This makes them quite an important topic of study at the global scale. In the present work, we applied the cloud structure analysis algorithm STRAT to long time series of lidar backscatter profiles from multiple locations around the world. Our goal was to establish a Mid-Latitude climatology of cirrus clouds macrophysical properties based on active remote sensing: ground-based lidars at four mid-latitude observatories and the spaceborne instrument CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization). Lidar sampling, macrophysical (cloud base height, cloud top height, cloud thickness) and optical (cloud optical thickness) properties statistics are then evaluated and compared between the four observatories ground-based lidar measurements and quasi-simultaneously CALIOP overpasses. We note an overall good consistency in the macrophysical properties statistics derived from ground- based Lidar and CALIOP. For high altitude clouds, using consistent transmission-based retrieval methods, discrepancies are found in COT retrievals between ground Lidars and CALIOP. Ground-based Lidar retrievals contain less thick cirrus clouds than CALIOP. Overall, the results show that cirrus clouds with COD<0.1 (not included in historical cloud climatologies) represent 30-50% of the non-opaque cirrus class (COD<3, Pressure<440mb from ISCCP). Finally, we analyze the statistic consistencies between each dataset and investigate the possible bias due to lidar sampling and instrument/algorithm differences between ground-based lidar and CALIOP.

  4. Couch height-based patient setup for abdominal radiation therapy.

    PubMed

    Ohira, Shingo; Ueda, Yoshihiro; Nishiyama, Kinji; Miyazaki, Masayoshi; Isono, Masaru; Tsujii, Katsutomo; Takashina, Masaaki; Koizumi, Masahiko; Kawanabe, Kiyoto; Teshima, Teruki

    2016-01-01

    There are 2 methods commonly used for patient positioning in the anterior-posterior (A-P) direction: one is the skin mark patient setup method (SMPS) and the other is the couch height-based patient setup method (CHPS). This study compared the setup accuracy of these 2 methods for abdominal radiation therapy. The enrollment for this study comprised 23 patients with pancreatic cancer. For treatments (539 sessions), patients were set up by using isocenter skin marks and thereafter treatment couch was shifted so that the distance between the isocenter and the upper side of the treatment couch was equal to that indicated on the computed tomographic (CT) image. Setup deviation in the A-P direction for CHPS was measured by matching the spine of the digitally reconstructed radiograph (DRR) of a lateral beam at simulation with that of the corresponding time-integrated electronic portal image. For SMPS with no correction (SMPS/NC), setup deviation was calculated based on the couch-level difference between SMPS and CHPS. SMPS/NC was corrected using 2 off-line correction protocols: no action level (SMPS/NAL) and extended NAL (SMPS/eNAL) protocols. Margins to compensate for deviations were calculated using the Stroom formula. A-P deviation > 5mm was observed in 17% of SMPS/NC, 4% of SMPS/NAL, and 4% of SMPS/eNAL sessions but only in one CHPS session. For SMPS/NC, 7 patients (30%) showed deviations at an increasing rate of > 0.1mm/fraction, but for CHPS, no such trend was observed. The standard deviations (SDs) of systematic error (Σ) were 2.6, 1.4, 0.6, and 0.8mm and the root mean squares of random error (σ) were 2.1, 2.6, 2.7, and 0.9mm for SMPS/NC, SMPS/NAL, SMPS/eNAL, and CHPS, respectively. Margins to compensate for the deviations were wide for SMPS/NC (6.7mm), smaller for SMPS/NAL (4.6mm) and SMPS/eNAL (3.1mm), and smallest for CHPS (2.2mm). Achieving better setup with smaller margins, CHPS appears to be a reproducible method for abdominal patient setup. PMID:26553471

  5. A Physically Based Algorithm for Non-Blackbody Correction of Cloud-Top Temperature and Application to Convection Study

    NASA Technical Reports Server (NTRS)

    Wang, Chunpeng; Lou, Zhengzhao Johnny; Chen, Xiuhong; Zeng, Xiping; Tao, Wei-Kuo; Huang, Xianglei

    2014-01-01

    Cloud-top temperature (CTT) is an important parameter for convective clouds and is usually different from the 11-micrometers brightness temperature due to non-blackbody effects. This paper presents an algorithm for estimating convective CTT by using simultaneous passive [Moderate Resolution Imaging Spectroradiometer (MODIS)] and active [CloudSat 1 Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)] measurements of clouds to correct for the non-blackbody effect. To do this, a weighting function of the MODIS 11-micrometers band is explicitly calculated by feeding cloud hydrometer profiles from CloudSat and CALIPSO retrievals and temperature and humidity profiles based on ECMWF analyses into a radiation transfer model.Among 16 837 tropical deep convective clouds observed by CloudSat in 2008, the averaged effective emission level (EEL) of the 11-mm channel is located at optical depth; approximately 0.72, with a standard deviation of 0.3. The distance between the EEL and cloud-top height determined by CloudSat is shown to be related to a parameter called cloud-top fuzziness (CTF), defined as the vertical separation between 230 and 10 dBZ of CloudSat radar reflectivity. On the basis of these findings a relationship is then developed between the CTF and the difference between MODIS 11-micrometers brightness temperature and physical CTT, the latter being the non-blackbody correction of CTT. Correction of the non-blackbody effect of CTT is applied to analyze convective cloud-top buoyancy. With this correction, about 70% of the convective cores observed by CloudSat in the height range of 6-10 km have positive buoyancy near cloud top, meaning clouds are still growing vertically, although their final fate cannot be determined by snapshot observations.

  6. A study of the morphology of winter sprites in the Hokuriku area of Japan in relation to cloud charge height

    NASA Astrophysics Data System (ADS)

    Myokei, K.; Matsudo, Y.; Asano, T.; Suzuki, T.; Hobara, Y.; Michimoto, K.; Hayakawa, M.

    2009-04-01

    Continuous observations of sprites in the Hokuriku area of Japan were performed from two optical sites during the three winter periods. The purpose of this observation is to study the major effect in the appearance of sprites and in determining the morphology of sprites (columns or carrots). Detailed analysis is performed based on the estimation of the height of -10 °C at the time of sprite occurrence. When the height of -10 °C is lower than 1800 m, the occurrence of sprites is infrequent, and the dominant shape is column. Then when it is increased (1800-3000 m), a new situation takes place, namely the occurrence of sprites is very enhanced and more spectacular shapes like carrots tend to be frequently observed in addition to column sprites. These sprite characteristics are first compared with those of parent lightning in the Hokuriku area and with our latest computer simulations on sprite initiation.

  7. Interoperating Cloud-based Virtual Farms

    NASA Astrophysics Data System (ADS)

    Bagnasco, S.; Colamaria, F.; Colella, D.; Casula, E.; Elia, D.; Franco, A.; Lusso, S.; Luparello, G.; Masera, M.; Miniello, G.; Mura, D.; Piano, S.; Vallero, S.; Venaruzzo, M.; Vino, G.

    2015-12-01

    The present work aims at optimizing the use of computing resources available at the grid Italian Tier-2 sites of the ALICE experiment at CERN LHC by making them accessible to interactive distributed analysis, thanks to modern solutions based on cloud computing. The scalability and elasticity of the computing resources via dynamic (“on-demand”) provisioning is essentially limited by the size of the computing site, reaching the theoretical optimum only in the asymptotic case of infinite resources. The main challenge of the project is to overcome this limitation by federating different sites through a distributed cloud facility. Storage capacities of the participating sites are seen as a single federated storage area, preventing the need of mirroring data across them: high data access efficiency is guaranteed by location-aware analysis software and storage interfaces, in a transparent way from an end-user perspective. Moreover, the interactive analysis on the federated cloud reduces the execution time with respect to grid batch jobs. The tests of the investigated solutions for both cloud computing and distributed storage on wide area network will be presented.

  8. Zonal superrotation above Venus' cloud base induced by the semidiurnal tide and the mean meridional circulation

    NASA Technical Reports Server (NTRS)

    Hou, Arthur Y.; Goody, Richard M.; Fels, Stephen B.

    1990-01-01

    The equilibrium zonal wind structure resulting from the interaction of the semidiurnal tide and the mean meridional circulation driven by the zonally averaged solar heating above the Venus cloud base were calculated. The results show that the tidal mechanism proposed by Fels and Lindzen (1974) can account for a substantial fraction (and possibly all) of the increase of the equatorial wind speed above the cloud base. Above the cloud tops, tidal deceleration may be too small to produce the zonal wind decrease with height inferred from thermal data. Tidal forcing does not explain the superrotation below the clouds, and additional eddy sources are needed to account for the zonal wind structure at mid and high latitudes.

  9. Statistical analysis of an LES shallow cumulus cloud ensemble using a cloud tracking algorithm

    NASA Astrophysics Data System (ADS)

    Dawe, J. T.; Austin, P. H.

    2012-01-01

    A technique for the tracking of individual clouds in a Large Eddy Simulation (LES) is presented. We use this technique on an LES of a shallow cumulus cloud field based upon the Barbados Oceanographic and Meteorological Experiment (BOMEX) to calculate statistics of cloud height, lifetime, and other physical properties for individual clouds in the model. We also examine the question of nature versus nurture in shallow cumulus clouds: do properties at cloud base determine the upper-level properties of the clouds (nature), or are cloud properties determined by the environmental conditions they encounter (nurture). We find that clouds which ascend through an environment that has been pre-moistened by previous cloud activity are no more likely to reach the inversion than clouds that ascend through a drier environment. Cloud base thermodynamic properties are uncorrelated with upper-level cloud properties, while mean fractional entrainment and detrainment rates display moderate correlations with cloud properties up to the inversion. Conversely, cloud base area correlates well with upper-level cloud area and maximum cloud height. We conclude that cloud thermodynamic properties are primarily influenced by entrainment and detrainment processes, cloud area and height are primarily influenced by cloud base area, and thus nature and nurture both play roles in the dynamics of BOMEX shallow cumulus clouds.

  10. Statistical analysis of a LES shallow cumulus cloud ensemble using a cloud tracking algorithm

    NASA Astrophysics Data System (ADS)

    Dawe, J. T.; Austin, P. H.

    2011-08-01

    A technique for the tracking of individual clouds in a Large Eddy Simulation (LES) is presented. We use this technique on a LES of a shallow cumulus cloud field based upon the Barbados Oceanographic and Meteorological Experiment (BOMEX) to calculate statistics of cloud height, lifetime, and other physical properties for individual clouds in the model. We also examine the question of nature versus nurture in shallow cumulus clouds: do properties at cloud base determine the upper-level properties of the clouds (nature), or are cloud properties determined by the environmental conditions they encounter (nurture). We find that clouds which ascend through an environment that has been pre-moistened by previous cloud activity are no more likely to reach the inversion than clouds that ascend through a drier environment. Cloud base thermodynamic properties are uncorrelated with upper-level cloud properties, while mean fractional entrainment and detrainment rate displays moderate correlations with cloud properties up to the inversion. Conversely, cloud base area correlates well with upper-level cloud area and maximum cloud height. We conclude that cloud thermodynamic properties are primarily influenced by entrainment and detrainment processes, cloud area and height are primarily influenced by cloud base area, and thus nature and nurture both play roles in the dynamics of BOMEX shallow cumulus clouds.

  11. NASA Cloud-Based Climate Data Services

    NASA Astrophysics Data System (ADS)

    McInerney, M. A.; Schnase, J. L.; Duffy, D. Q.; Tamkin, G. S.; Strong, S.; Ripley, W. D., III; Thompson, J. H.; Gill, R.; Jasen, J. E.; Samowich, B.; Pobre, Z.; Salmon, E. M.; Rumney, G.; Schardt, T. D.

    2012-12-01

    Cloud-based scientific data services are becoming an important part of NASA's mission. Our technological response is built around the concept of specialized virtual climate data servers, repetitive cloud provisioning, image-based deployment and distribution, and virtualization-as-a-service (VaaS). A virtual climate data server (vCDS) is an Open Archive Information System (OAIS) compliant, iRODS-based data server designed to support a particular type of scientific data collection. iRODS is data grid middleware that provides policy-based control over collection-building, managing, querying, accessing, and preserving large scientific data sets. We have deployed vCDS Version 1.0 in the Amazon EC2 cloud using S3 object storage and are using the system to deliver a subset of NASA's Intergovernmental Panel on Climate Change (IPCC) data products to the latest CentOS federated version of Earth System Grid Federation (ESGF), which is also running in the Amazon cloud. vCDS-managed objects are exposed to ESGF through FUSE (Filesystem in User Space), which presents a POSIX-compliant filesystem abstraction to applications such as the ESGF server that require such an interface. A vCDS manages data as a distinguished collection for a person, project, lab, or other logical unit. A vCDS can manage a collection across multiple storage resources using rules and microservices to enforce collection policies. And a vCDS can federate with other vCDSs to manage multiple collections over multiple resources, thereby creating what can be thought of as an ecosystem of managed collections. With the vCDS approach, we are trying to enable the full information lifecycle management of scientific data collections and make tractable the task of providing diverse climate data services. In this presentation, we describe our approach, experiences, lessons learned, and plans for the future.; (A) vCDS/ESG system stack. (B) Conceptual architecture for NASA cloud-based data services.

  12. Comparing the Cloud Vertical Structure Derived from Several Methods Based on Radiosonde Profiles and Ground-based Remote Sensing Measurements

    SciTech Connect

    Costa-Suros, M.; Calbo, J.; Gonzalez, J. A.; Long, Charles N.

    2014-08-27

    The cloud vertical distribution and especially the cloud base height, which is linked to cloud type, is an important characteristic in order to describe the impact of clouds in a changing climate. In this work several methods to estimate the cloud vertical structure (CVS) based on atmospheric sounding profiles are compared, considering number and position of cloud layers, with a ground based system which is taken as a reference: the Active Remote Sensing of Clouds (ARSCL). All methods establish some conditions on the relative humidity, and differ on the use of other variables, the thresholds applied, or the vertical resolution of the profile. In this study these methods are applied to 125 radiosonde profiles acquired at the ARM Southern Great Plains site during all seasons of year 2009 and endorsed by GOES images, to confirm that the cloudiness conditions are homogeneous enough across their trajectory. The overall agreement for the methods ranges between 44-88%; four methods produce total agreements around 85%. Further tests and improvements are applied on one of these methods. In addition, we attempt to make this method suitable for low resolution vertical profiles, which could be useful in atmospheric modeling. The total agreement, even when using low resolution profiles, can be improved up to 91% if the thresholds for a moist layer to become a cloud layer are modified to minimize false negatives with the current data set, thus improving overall agreement.

  13. Cloud field classification based on textural features

    NASA Technical Reports Server (NTRS)

    Sengupta, Sailes Kumar

    1989-01-01

    An essential component in global climate research is accurate cloud cover and type determination. Of the two approaches to texture-based classification (statistical and textural), only the former is effective in the classification of natural scenes such as land, ocean, and atmosphere. In the statistical approach that was adopted, parameters characterizing the stochastic properties of the spatial distribution of grey levels in an image are estimated and then used as features for cloud classification. Two types of textural measures were used. One is based on the distribution of the grey level difference vector (GLDV), and the other on a set of textural features derived from the MaxMin cooccurrence matrix (MMCM). The GLDV method looks at the difference D of grey levels at pixels separated by a horizontal distance d and computes several statistics based on this distribution. These are then used as features in subsequent classification. The MaxMin tectural features on the other hand are based on the MMCM, a matrix whose (I,J)th entry give the relative frequency of occurrences of the grey level pair (I,J) that are consecutive and thresholded local extremes separated by a given pixel distance d. Textural measures are then computed based on this matrix in much the same manner as is done in texture computation using the grey level cooccurrence matrix. The database consists of 37 cloud field scenes from LANDSAT imagery using a near IR visible channel. The classification algorithm used is the well known Stepwise Discriminant Analysis. The overall accuracy was estimated by the percentage or correct classifications in each case. It turns out that both types of classifiers, at their best combination of features, and at any given spatial resolution give approximately the same classification accuracy. A neural network based classifier with a feed forward architecture and a back propagation training algorithm is used to increase the classification accuracy, using these two classes of features. Preliminary results based on the GLDV textural features alone look promising.

  14. Estimation of Biomass Potential Based on Classification and Height Information

    NASA Astrophysics Data System (ADS)

    Müller, S.; Büscher, O.; Jandewerth, M.

    2013-05-01

    On the way to make energy supply independent from fossil resources more and more renewable energy sources have to be explored. Biomass has become an important energy resource during the last years and the consumption is rising steadily. Common sources of biomass are agricultural production and forestry but the production of these sources is stagnating due to limited space. To explore new sources of biomass like in the field of landscape conservation the location and available amount of biomass is unknown. Normally, there are no reliable data sources to give information about the objects of interest such as hedges, vegetation along streets, railways and rivers, field margins and ruderal sites. There is a great demand for an inventory of these biomass sources which could be answered by applying remote sensing technology. As biomass objects considered here are sometimes only a few meters wide, spectral unmixing is applied to separate different material mixtures reflected in one image pixel. The spectral images are assumed to have a spatial resolution of 5-20 m with multispectral or hyperspectral band configurations. Combining the identified material part fractions with height information and GIS data afterwards will give estimates about the location of biomass objects. The method is applied to test data of a Sentinel-2 simulation and the results are evaluated visually.

  15. Cloudy Sounding and Cloud-Top Height Retrieval From AIRS Alone Single Field-of-View Radiance Measurements

    NASA Technical Reports Server (NTRS)

    Weisz, Elisabeth; Li, Jun; Li, Jinlong; Zhou, Daniel K.; Huang, Hung-Lung; Goldberg, Mitchell D.; Yang, Ping

    2007-01-01

    High-spectral resolution measurements from the Atmospheric Infrared Sounder (AIRS) onboard the EOS (Earth Observing System) Aqua satellite provide unique information about atmospheric state, surface and cloud properties. This paper presents an AIRS alone single field-of-view (SFOV) retrieval algorithm to simultaneously retrieve temperature, humidity and ozone profiles under all weather conditions, as well as cloud top pressure (CTP) and cloud optical thickness (COT) under cloudy skies. For optically thick cloud conditions the above-cloud soundings are derived, whereas for clear skies and optically thin cloud conditions the profiles are retrieved from 0.005 hPa down to the earth's surface. Initial validation has been conducted by using the operational MODIS (Moderate Resolution Imaging Spectroradiometer) product, ECMWF (European Center of Medium range Weather Forecasts) analysis fields and radiosonde observations (RAOBs). These inter-comparisons clearly demonstrate the potential of this algorithm to process data from 38 high-spectral infrared (IR) sounder instruments.

  16. A global survey of cloud overlap based on CALIPSO and CloudSat measurements

    NASA Astrophysics Data System (ADS)

    Li, J.; Huang, J.; Stamnes, K.; Wang, T.; Lv, Q.; Jin, H.

    2015-01-01

    Using 2B-CLDCLASS-LIDAR (radar-lidar) cloud classification and 2B-FLXHR-LIDAR radiation products from CloudSat over 4 years, this study evaluates the co-occurrence frequencies of different cloud types, analyzes their along-track horizontal scales and cloud radiative effects (CREs), and utilizes the vertical distributions of cloud types to evaluate cloud-overlap assumptions. The statistical results show that high clouds, altostratus (As), altocumulus (Ac) and cumulus (Cu) tend to coexist with other cloud types. However, stratus (St) (or stratocumulus, Sc), nimbostratus (Ns) and convective clouds are much more likely to exhibit individual features than other cloud types. On average, altostratus-over-stratus/stratocumulus cloud systems have a maximum horizontal scale of 17.4 km, with a standard deviation of 23.5 km. Altocumulus-over-cumulus cloud types have a minimum scale of 2.8 km, with a standard deviation of 3.1 km. By considering the weight of each multilayered cloud type, we find that the global mean instantaneous net CREs of multilayered cloud systems during the daytime are approximately -41.3 and -50.2 W m-2, which account for 40.1 and 42.3% of the global mean total net CREs at the top of the atmosphere (TOA) and at the surface, respectively. The radiative contributions of high-over-altocumulus and high-over-stratus/stratocumulus (or cumulus) in the all multilayered cloud systems are dominant due to their frequency. Considering the overlap of cloud types, the cloud fraction based on the random overlap assumption is underestimated over vast oceans, except in the west-central Pacific Ocean warm pool. Obvious overestimations mainly occur over tropical and subtropical land masses. In view of a lower degree of overlap than that predicted by the random overlap assumption to occur over the vast ocean, particularly poleward of 40° S, the study therefore suggests that a linear combination of minimum and random overlap assumptions may further improve the predictions of actual cloud fractions for multilayered cloud types (e.g., As + St/Sc and Ac + St/Sc) over the Southern Ocean. The establishment of a statistical relationship between multilayered cloud types and the environmental conditions (e.g., atmospheric vertical motion, convective stability and wind shear) would be useful for parameterization design of cloud overlap in numerical models.

  17. Evaluation of Radar Reflectivity Based Estimates of Water Content in Stratiform Marine Clouds.

    NASA Astrophysics Data System (ADS)

    Matrosov, Sergey Y.; Uttal, Taneil; Hazen, Duane A.

    2004-04-01

    The performance of radar reflectivity (Ze) based relations for retrievals of marine stratiform cloud liquid water content (LWC) is evaluated by comparing liquid water path (LWP) estimates from microwave radiometers with vertically integrated LWC values retrieved from radar measurements. Based on a measurement dataset from a research vessel in the tropical eastern Pacific Ocean, it is shown that reflectivity thresholding allows minimizing of the influence of drizzle drops present in marine stratiform clouds to the extent that LWP estimates from a ground-/shipborne radar can have uncertainties that might be acceptable for different applications. The accuracies of Ze-based retrievals depend on the thresholding level Zet, and they are generally better than a factor of 2 for Zet -15 dBZ. These accuracies typically improve when Zet is lowered; however, the amount of cloud profiles that pass thresholding diminishes as Zet is decreased from about 50% for a -15-dbZ threshold to only about 10% for a -25-dBZ threshold. Different thresholding strategies are considered. Ancillary information on cloud-base heights can improve LWP estimates from reflectivities. The ship-based dataset was used to simulate measurements from prospective 94-GHz spaceborne cloud radar (CloudSat). CloudSat measurements would, on average, detect about 75% of warm marine stratiform clouds, though many clouds with negligible presence of drizzle will be missed. Because of sensitivity and resolution issues for the spaceborne radar, reflectivity-based estimates of LWP are generally biased toward high values and have higher uncertainties when compared with the ground-based radar, for the same Zet.

  18. Is School-Based Height and Weight Screening of Elementary Students Private and Reliable?

    ERIC Educational Resources Information Center

    Stoddard, Sarah A.; Kubik, Martha Y.; Skay, Carol

    2008-01-01

    The Institute of Medicine recommends school-based body mass index (BMI) screening as an obesity prevention strategy. While school nurses have provided height/weight screening for years, little has been published describing measurement reliability or process. This study evaluated the reliability of height/weight measures collected by school nurses…

  19. 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.

  20. Determination of the normal height of the Everest based on EGM 2008

    NASA Astrophysics Data System (ADS)

    Shen, W. B.; Li, Jin; Han, J.

    2009-04-01

    The orthometric height H is the height above the geoid, which is the equi-geopotential surface nearest to the mean sea level. The normal height H*, however, is the height above the quasi-geoid, which fast coincides with the geoid in the ocean but deviates from the geoid a little in the land areas. In China, the height datum system is based on the quasi-geoid, i.e., in most cases we use the normal height. GPS technique provides the coordinates of an arbitrary point P on ground with the accuracy better than 1 cm, in the geocentric Earth-fixed system. Hence, with the same accuracy, GPS technique provides the geodetic coordinates of the point P . Then, if the quasi-geoid is determined, the normal height can be subsequently determined. In the present paper, we focus on the determination of the normal height of the Everest based on the international gravity field model, EGM 2008. The geodetic coordinates of the Everest could be obtained by different sources. We use the coordinates provided by Chinese Surveying Bureau. In the frame of Molodensky theory, based on EGM 2008 (with degree 2190), we determine the normal height of the Everest by two approaches: point-wise approach and area-average approach. By point-wise and area-average approaches, our results show that the normal heights of the Everest are HEGM2008* = 8847.32 m and HEGM2008* = 8847.37 m, respectively. Concerning the normal height determination of the Everest, we find that the difference between our result and the result provided recently by Chinese Surveying Bureau is less than 0.1 m. Using EGM 96 however, we find that the difference is around 1 m. This study is supported by National 863 Project of China (Grant No.: 2006AA12Z211) and National Natural Science Foundation of China (Grant No.: 40637034; 40574004).

  1. Satellite-Based Insights into Precipitation Formation Processes in Continental and Maritime Convective Clouds.

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Daniel; Lensky, Itamar M.

    1998-11-01

    Multispectral analyses of satellite images are used to calculate the evolution of the effective radius of convective cloud particles with temperature, and to infer from that information about precipitation forming processes in theclouds. Different microphysical processes are identified at different heights. From cloud base to top, the microphysical classification includes zones of diffusional droplet growth, coalescence droplet growth, rainout, mixed-phase precipitation, and glaciation. Not all zones need appear in a given cloud system. Application to maritime clouds shows, from base to top, zones of coalescence, rainout, a shallow mixed-phase region, and glaciation starting at -10C or even warmer. In contrast, continental clouds have a deep diffusional growth zone above their bases, followed by coalescence and mixed-phase zones, and glaciation at -15 to -20C. Highly continental clouds have a narrow or no coalescence zone, a deep mixed-phase zone, and glaciation occurring between -20 and -30C. Limited aircraft validation for the satellite inferences over Israel, Thailand, and Indonesia is available.Substantial transformation in the microphysical and precipitation forming processes is observed by this method in convective clouds developing in air masses moving from the sea inland. These changes appear to be related to the modification of the maritime air mass as it moves inland and becomes more continental. Further transformations are observed in air masses moving into areas affected by biomass burning smoke or urban air pollution, such that coalescence, and thus precipitation, is suppressed even in deep tropical clouds. It follows that natural and anthropogenic aerosols can substantially modify clouds not only in pristine environments, as was already demonstrated by the ship tracks, but they can also incur profound impact on cloud microstructure and precipitation in more continental environments, leading to substantial weather modification in densely populated areas.

  2. 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.

  3. Height Accuracy Based on Different Rtk GPS Method for Ultralight Aircraft Images

    NASA Astrophysics Data System (ADS)

    Tahar, K. N.

    2015-08-01

    Height accuracy is one of the important elements in surveying work especially for control point's establishment which requires an accurate measurement. There are many methods can be used to acquire height value such as tacheometry, leveling and Global Positioning System (GPS). This study has investigated the effect on height accuracy based on different observations which are single based and network based GPS methods. The GPS network is acquired from the local network namely Iskandar network. This network has been setup to provide real-time correction data to rover GPS station while the single network is based on the known GPS station. Nine ground control points were established evenly at the study area. Each ground control points were observed about two and ten minutes. It was found that, the height accuracy give the different result for each observation.

  4. STUDY OF GRIDDED MIXING HEIGHTS AD CLOUD FIELDS DERIVED FROM THE MESOSCALE METEOROLOGICAL MODEL WITH FOUR DIMENSIONAL DATA ASSIMILATION

    EPA Science Inventory

    Meteorological data including wind, temperature and moisture variables, as well as boundary layer parameters including surface fluxes, depth of the mixed layer and cloud and precipitation information are integral components of air quality simulations models (AQSMS). QSMs require ...

  5. Characteristics of Borneo and Sumatra fire plume heights and smoke clouds and their impact on regional El Nio-induced drought

    NASA Astrophysics Data System (ADS)

    Tosca, Michael; Randerson, James; Zender, Cs; Flanner, Mg; Nelson, Dl; Diner, Dj; Rasch, Pj; Logan, Ja

    2010-05-01

    During the dry season, anthropogenic fires in tropical forests and peatlands in equatorial Asia produce regionally expansive smoke clouds. We estimated the altitude of smoke clouds from these fires, characterized the sensitivity of these clouds to regional drought and El Nio variability, and investigated their effect on climate. We used the MISR satellite product and MISR INteractive eXplorer (MINX) software to estimate the heights of 382 smoke plumes (smoke with a visible surface source and transport direction) on Borneo and 143 plumes on Sumatra for 20012009. In addition, we estimated the altitudes of 10 smoke clouds (opaque regions of smoke with no detectable surface source or transport direction) on Borneo during 2006. Most smoke plumes (84%) were observed during El Nio events (2002, 2004, 2006, and 2009); this is consistent with higher numbers of active fire detections and larger aerosol optical depths observed during El Nio years. Annually averaged plume heights on Borneo were positively correlated to the Oceanic Nio Index (ONI), an indicator of El Nio (r2 = 0.53), and the mean plume height for all El Nio years was 772.5 15.9m, compared to 711.4 28.7m for non-El Nio years. The median altitude of the 10 smoke clouds observed on Borneo during 2006 was 1313m, considerably higher than the median of nearby smoke plumes (787m). The difference in height between individual plumes and regional smoke clouds may be related to deeper planetary boundary layers and injection heights later in the afternoon (after the 10:30am MISR overpass) or other atmospheric mixing processes that occur on synoptic timescales. We investigated the climate response to these expansive smoke clouds using the Community Atmosphere Model (CAM). Climate responses to smoke from two 30 year simulations were compared: one simulation was forced with fire emissions typical of a dry (El Nio) burning year, while the other was forced with emissions typical of a low (La Nia) burning year. Fire aerosols reduced net shortwave radiation at the surface during August-October by an average of 10% in the region encompassing most of Sumatra and Borneo (90E-120E, 5 S-5N). The reductions in net radiation cooled both sea surface temperature (0.5 0.3C) and land air temperature (0.4 0.2C) during these months. Tropospheric heating from black carbon (BC) absorption increased substantially (20.5 9.3 W m-2) and was balanced by an overall reduction in latent heating in the mid-troposphere. The combination of decreased SSTs and increased atmospheric heating reduced regional precipitation by 0.9 0.6 mm d-1 (10%). The vulnerability of ecosystems to fire was enhanced because the decreases in precipitation exceeded those for evapotranspiration. Together, the satellite and modeling results imply a possible positive feedback loop in which anthropogenic burning in the region intensifies drought stress during El Nio.

  6. Efficient modeling of height datum based on GIS

    NASA Astrophysics Data System (ADS)

    Qiao, Q.

    2014-04-01

    Since the proposal of Digital Earth, its research and applications are continuing to be deepened, and now Smart City is more indepth implementation of the Digital Earth. The unification of global or regional vertical datums has always been one of the main geodesy studies to achieve Smart City, as Smart City must first realize the seamless integration of multi-source geo-dataset. This paper introduces spatio-temporal data management and interactive visualization into the entire process of vertical datum modelling. We demonstrate that the efficiency of modelling is greatly improved. In this paper GIS database is used to manage all dataset such as tidal station data, gravity field model data, GPS leveling data, and vertical datum data for evaluation and analysis. We use geographic information visualization technique to graphically display the results, together with the interactive browsing, to convert tedious digital information to easy-to-understand images. Consequently, researchers can quickly and comprehensively grasp the macro and micro information. Finally, an efficient and interactive prototype operating platforms for vertical datum modeling is constructed based on GIS.

  7. Ground-Based Cloud and Atmospheric Boundary Layer Observations for the Project: High Definition Clouds and Precipitation for Advancing Climate Prediction, HD(CP)2

    NASA Astrophysics Data System (ADS)

    Hirsikko, A.; Ebell, K.; Ulrich, U.; Schween, J. H.; Bohn, B.; Görsdorf, U.; Leinweber, R.; Päschke, E.; Baars, H.; Seifert, P.; Klein Baltink, H.

    2014-12-01

    The German research initiative ''High Definition Clouds and Precipitation for advancing Climate Prediction, HD(CP)2'' aims for an improved representation of clouds and precipitation in climate models. Model development and its evaluation require comprehensive observational datasets. A specific work package was established to create uniform and documented observational datasets for the HD(CP)2 data base. Datasets included ground-based remote-sensing (Doppler lidars, ceilometers, microwave radiometers, and cloud radars) and in-situ (meteorological and radiation sensors) measurements. Four supersites (Jülich ObservatorY for Cloud Evolution (JOYCE), Lindenberg Meteorological Observatory - Richard Assmann Observatory (RAO), and Leipzig Aerosol and Cloud Remote Observations System (LACROS) in Germany, and Cabauw experimental site for atmospheric research (Cesar) in the Netherlands) are finalizing the operational procedures to provide quality controlled (and calibrated if possible) remote-sensing and in-situ observations, retrievals on atmospheric boundary layer state (e.g. winds, mixing layer height, humidity and temperature), and cloud macro and micro physical properties with uncertainty estimations or at least quality flags. During the project new processing and retrieval methods were developed if no commonly agreed or satisfying methods were available. Especially, large progress was made concerning uncertainty estimation and automated quality control. Additionally, the data from JOYCE are used in a radiative closure studies under cloudy conditions to evaluate retrievals of cloud properties. The current status of work progress will be presented.

  8. Height compensation using ground inclination estimation in inertial sensor-based pedestrian navigation.

    PubMed

    Park, Sang Kyeong; Suh, Young Soo

    2011-01-01

    In an inertial sensor-based pedestrian navigation system, the position is estimated by double integrating external acceleration. A new algorithm is proposed to reduce z axis position (height) error. When a foot is on the ground, a foot angle is estimated using accelerometer output. Using a foot angle, the inclination angle of a road is estimated. Using this road inclination angle, height difference of one walking step is estimated and this estimation is used to reduce height error. Through walking experiments on roads with different inclination angles, the usefulness of the proposed algorithm is verified. PMID:22164061

  9. Height Compensation Using Ground Inclination Estimation in Inertial Sensor-Based Pedestrian Navigation

    PubMed Central

    Park, Sang Kyeong; Suh, Young Soo

    2011-01-01

    In an inertial sensor-based pedestrian navigation system, the position is estimated by double integrating external acceleration. A new algorithm is proposed to reduce z axis position (height) error. When a foot is on the ground, a foot angle is estimated using accelerometer output. Using a foot angle, the inclination angle of a road is estimated. Using this road inclination angle, height difference of one walking step is estimated and this estimation is used to reduce height error. Through walking experiments on roads with different inclination angles, the usefulness of the proposed algorithm is verified. PMID:22164061

  10. Comparison of the CALIPSO satellite and ground-based observations of cirrus clouds at the ARM TWP sites

    SciTech Connect

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

    2011-11-10

    Statistics of ice cloud macrophysical and optical properties from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) instrument on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite are compared with those from ground-based lidar observations over a 31 month period. Ground-based lidar observations are taken from the micropulse lidars (MPL) at the three Department of Energy Atmospheric Radiation Measurement (ARM) tropical western pacific (TWP) sites: Manus, Nauru and Darwin. CALIPSO observations show a larger cloud fraction at high altitudes while the ground-based MPLs show a larger cloud fraction at low altitudes. The difference in mean ice cloud top and base heights at the Manus and Nauru sites are all within 0.51 km, although differences are statistically significant. Mean ice cloud geometrical thickness agree to within 0.05 km at the Manus and Nauru sites. Larger differences exist at Darwin due to excessive degradation of the MPL output power during our sampling period. Both sets of observations show thicker clouds during the nighttime which may be real but could also be partially an artifact of the decreased signal-to-noise ratio during the daytime. The number of ice cloud layers per profile are also shown to be consistent after accounting for the difference in spatial resolution. For cloud optical depths, four different retrieval methods are compared, two for each set of observations. All products show that the majority of ice cloud optical depths ({approx}60%) fall below an optical depth of 0.2. For most comparisons all four retrievals agree to within the uncertainty intervals. We find that both CALIPSO retrievals agree best to ground-based optical depths when the lidar ratio in the latter is retrieved instead of set to a fixed value. Also thoroughly compared is the cloud properties for the subset of ice clouds which reside in the tropical tropopause layer (TTL).

  11. Comparison of macroscopic cloud data from ground-based measurements using VIS/NIR and IR instruments at Lindenberg, Germany

    NASA Astrophysics Data System (ADS)

    Feister, Uwe; Möller, Hans; Sattler, Theo; Shields, Janet; Görsdorf, Ulrich; Güldner, Jürgen

    2010-05-01

    A comparison between different types of ground-based sensors has been carried out to derive macroscopic cloud data such as cloud cover and cloud-base heights. The instruments compared in the campaign at the Meteorological Observatory Lindenberg in the period May to September 2006 include an infrared (IR) sky scanner called Nubiscope, a Daylight VIS/NIR Whole Sky Imager (WSI), a ceilometer LD-40 measuring in the near infrared region (NIR) and a Ka band cloud radar measuring in the micro wave band (extremely high frequency or EHF) region. In addition, our data analysis included regular hourly cloud observations by weather observers, and vertical profiles of temperature, humidity and winds taken from six-hourly radio soundings at the site. The comparison has been focused on performance and features of the Nubiscope as a prototype instrument for automatic cloud observations. Cloud cover (CC) derived from the Nubiscope cloud algorithm compares quite well with CC derived from both WSI and from observations. CC differences are within ± 2 Okta in 67% of cases between Nubiscope and observations, and in 90% of cases between Nubiscope and WSI. The cloud detection capability as derived from the zenith signals of Nubiscope and WSI shows coincidence in about 90% of cases. For cloud-base heights (CBHs) from Nubiscope data and ceilometer as well as from radar reflectivity, the comparison showed a general good correspondence in the lower and middle troposphere up to heights of about 6 km with some systematic difference due to the different detection methods. For the upper troposphere above 6 km the differences become widespread and more random. Cloud detection capabilities of the instruments are also illustrated by a case study of moving clouds with patterns similar to contrails that were erroneously classified as such by the weather observer mainly due to lack of height information that the ceilometer did not provide. By combined information from WSI, radio sonde humidity and radar, they were shown not to be contrails, but most likely low-level water clouds either of natural origin or built from aircraft at their ascent or descent flight close to the airport.

  12. Cloud Based Processing of Large Photometric Surveys

    NASA Astrophysics Data System (ADS)

    Farivar, R.; Brunner, R. J.; Santucci, R.; Campbell, R.

    2013-10-01

    Astronomy, as is the case with many scientific domains, has entered the realm of being a data rich science. Nowhere is this reflected more clearly than in the growth of large area surveys, such as the recently completed Sloan Digital Sky Survey (SDSS) or the Dark Energy Survey, which will soon obtain PB of imaging data. The data processing on these large surveys is a major challenge. In this paper, we demonstrate a new approach to this common problem. We propose the use of cloud-based technologies (e.g., Hadoop MapReduce) to run a data analysis program (e.g., SExtractor) across a cluster. Using the intermediate key/value pair design of Hadoop, our framework matches objects across different SExtractor invocations to create a unified catalog from all SDSS processed data. We conclude by presenting our experimental results on a 432 core cluster and discuss the lessons we have learned in completing this challenge.

  13. Comparing the cloud vertical structure derived from several methods based on radiosonde profiles and ground-based remote sensing measurements

    NASA Astrophysics Data System (ADS)

    Costa-Surós, M.; Calbó, J.; González, J. A.; Long, C. N.

    2014-08-01

    The cloud vertical distribution and especially the cloud base height, which is linked to cloud type, are important characteristics in order to describe the impact of clouds on climate. In this work, several methods for estimating the cloud vertical structure (CVS) based on atmospheric sounding profiles are compared, considering the number and position of cloud layers, with a ground-based system that is taken as a reference: the Active Remote Sensing of Clouds (ARSCL). All methods establish some conditions on the relative humidity, and differ in the use of other variables, the thresholds applied, or the vertical resolution of the profile. In this study, these methods are applied to 193 radiosonde profiles acquired at the Atmospheric Radiation Measurement (ARM) Southern Great Plains site during all seasons of the year 2009 and endorsed by Geostationary Operational Environmental Satellite (GOES) images, to confirm that the cloudiness conditions are homogeneous enough across their trajectory. The perfect agreement (i.e., when the whole CVS is estimated correctly) for the methods ranges between 26 and 64%; the methods show additional approximate agreement (i.e., when at least one cloud layer is assessed correctly) from 15 to 41%. Further tests and improvements are applied to one of these methods. In addition, we attempt to make this method suitable for low-resolution vertical profiles, like those from the outputs of reanalysis methods or from the World Meteorological Organization's (WMO) Global Telecommunication System. The perfect agreement, even when using low-resolution profiles, can be improved by up to 67% (plus 25% of the approximate agreement) if the thresholds for a moist layer to become a cloud layer are modified to minimize false negatives with the current data set, thus improving overall agreement.

  14. 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.

  15. 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.

  16. Research on cloud-based remote measurement and analysis system

    NASA Astrophysics Data System (ADS)

    Gao, Zhiqiang; He, Lingsong; Su, Wei; Wang, Can; Zhang, Changfan

    2015-02-01

    The promising potential of cloud computing and its convergence with technologies such as cloud storage, cloud push, mobile computing allows for creation and delivery of newer type of cloud service. Combined with the thought of cloud computing, this paper presents a cloud-based remote measurement and analysis system. This system mainly consists of three parts: signal acquisition client, web server deployed on the cloud service, and remote client. This system is a special website developed using asp.net and Flex RIA technology, which solves the selective contradiction between two monitoring modes, B/S and C/S. This platform supplies customer condition monitoring and data analysis service by Internet, which was deployed on the cloud server. Signal acquisition device is responsible for data (sensor data, audio, video, etc.) collection and pushes the monitoring data to the cloud storage database regularly. Data acquisition equipment in this system is only conditioned with the function of data collection and network function such as smartphone and smart sensor. This system's scale can adjust dynamically according to the amount of applications and users, so it won't cause waste of resources. As a representative case study, we developed a prototype system based on Ali cloud service using the rotor test rig as the research object. Experimental results demonstrate that the proposed system architecture is feasible.

  17. Body height estimation based on dimensions of sacral and coccygeal vertebrae.

    PubMed

    Pelin, Can; Duyar, Izzet; Kayahan, Esra M; Zağyapan, Ragiba; Ağildere, A Muhteşem; Erar, Aydin

    2005-03-01

    This study is to evaluate whether it is possible to predict living stature from sacral and coccygeal vertebral dimensions. Individual vertebral body heights, sacral height (SH), and sacrococcygeal height (SCH) were recorded from the magnetic resonance images of 42 adult males. Sum of the heights of five sacral vertebrae (sigmaS), the first four coccygeal vertebrae (sigmaC), and the total height of the sacral and the first four coccygeal vertebrae together (sigmaSC) were also recorded. Linear regression equations for stature estimation were produced using the above mentioned variables. The regression equations were constructed and tested by using jack-knife procedure. Statistical analyses indicated that the combined variables (SH, SCH, sigmaS, sigmaC, sigmaSC) were more accurate predictors of stature than the heights of individual vertebrae. The results of the study pointed out that the equations derived from sacrococcygeal dimensions perform somewhat better than ones based on foot and head variables, but worse than those based on long-bone length. As a conclusion, the dimensions of sacral and coccygeal vertebrae could be used for stature estimation when long bones are not available. PMID:15813539

  18. Testing the Parameterizations of Cloud Base Mass-Flux for Shallow Cumulus Clouds using Cloud Radar Observations

    NASA Astrophysics Data System (ADS)

    Chandra, A.; Kollias, P.; Albrecht, B. A.; Zhu, P.; Klein, S. A.; Zhang, Y.

    2010-12-01

    Shallow cumulus clouds have significant impact on the vertical distributions of heat and moisture and on surface energy fluxes over land through their effect on incoming shortwave radiation. The present resolutions of General Circulation Model (GCM) and Numerical weather prediction (NWP) models are not fine enough to simulate shallow clouds directly, leaving not much choice other than parameterizations evaluated using either Large Eddy Simulation (LES) and observations. The representation of these clouds in numerical models is an important and challenging issue in model development, because of its potential impacts on near-surface weather and long-term climate simulations. Recent studies through LES have shown that the mass flux is the important parameter for determining the characteristics of cumulus transports within cloud layer. Based on LES results and scaling arguments, substantial efforts have been made to parameterize the cloud base mass flux to improve the interactions between the subcloud and cloud layer. Despite these efforts, what factors control the mass flux and how the interaction between subcloud and cloud layers should be parameterized is not fully understood. From the observational perspective, studies have been done using aircraft and remote sensing platform to address the above issue; there have been insufficient observations to develop detailed composite studies under different conditions. The Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) in Southern Great Plains (SGP) offers unique long-term measurements from cloud radars (35 and 94 GHz) along with synergetic measurements to address the above problem of non-precipitating shallow cumulus clouds over the SGP region. Doppler velocities from the cloud radar are processed to remove the insect contamination using a fuzzy-logic approach before they are used for the mass-flux calculation. The present observations are used to validate the existing mass-flux relations used in parameterizations. The possible factors [such as, effect of wind shear, transition layer strength, lower tropospheric relative humidity, large-scale vertical velocity and stability (CAPE and CIN)] that affects the mass-flux in addition to the convective velocity (w*) are studied using sounding and ECMWF model dataset. Furthermore, the data are classified based on time of the day, and for various cloud fractions and composite profiles are calculated to define the differences for different regimes.

  19. 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.

  20. Stereoscopic Retrieval of Smoke Plume Heights and Motion from Space-Based Multi-Angle Imaging, Using the MISR INteractive eXplorer(MINX)

    NASA Technical Reports Server (NTRS)

    Nelson, David L.; Kahn, Ralph A.

    2014-01-01

    Airborne particles desert dust, wildfire smoke, volcanic effluent, urban pollution affect Earth's climate as well as air quality and health. They are found in the atmosphere all over the planet, but vary immensely in amount and properties with season and location. Most aerosol particles are injected into the near-surface boundary layer, but some, especially wildfire smoke, desert dust and volcanic ash, can be injected higher into the atmosphere, where they can stay aloft longer, travel farther, produce larger climate effects, and possibly affect human and ecosystem health far downwind. So monitoring aerosol injection height globally can make important contributions to climate science and air quality studies. The Multi-angle Imaging Spectro-Radiometer (MISR) is a space borne instrument designed to study Earths clouds, aerosols, and surface. Since late February 2000 it has been retrieving aerosol particle amount and properties, as well as cloud height and wind data, globally, about once per week. The MINX visualization and analysis tool complements the operational MISR data products, enabling users to retrieve heights and winds locally for detailed studies of smoke plumes, at higher spatial resolution and with greater precision than the operational product and other space-based, passive remote sensing techniques. MINX software is being used to provide plume height statistics for climatological studies as well as to investigate the dynamics of individual plumes, and to provide parameterizations for climate modeling.

  1. Retrievals of Cloud Fraction and Cloud Albedo from Surface-based Shortwave Radiation Measurements: A Comparison of 16 Year Measurements

    SciTech Connect

    Xie, Yu; Liu, Yangang; Long, Charles N.; Min, Qilong

    2014-07-27

    Ground-based radiation measurements have been widely conducted to gain information on clouds and the surface radiation budget; here several different techniques for retrieving cloud fraction (Long2006, Min2008 and XL2013) and cloud albedo (Min2008, Liu2011 and XL2013) from ground-based shortwave broadband and spectral radiation measurements are examined, and sixteen years of retrievals collected at the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site are compared. The comparison shows overall good agreement between the retrievals of both cloud fraction and cloud albedo, with noted differences however. The Long2006 and Min2008 cloud fractions are greater on average than the XL2013 values. Compared to Min2008 and Liu2011, the XL2013 retrieval of cloud albedo tends to be greater for thin clouds but smaller for thick clouds, with the differences decreasing with increasing cloud fraction. Further analysis reveals that the approaches that retrieve cloud fraction and cloud albedo separately may suffer from mutual contamination of errors in retrieved cloud fraction and cloud albedo. Potential influences of cloud absorption, land-surface albedo, cloud structure, and measurement instruments are explored.

  2. Building height retrieval from airborne VHR SAR imagery based on an iterative simulation and matching procedure

    NASA Astrophysics Data System (ADS)

    Brunner, Dominik; Lemoine, Guido; Bruzzone, Lorenzo

    2008-10-01

    The new spaceborne very high resolution (VHR) synthetic aperture radar (SAR) sensors onboard the TerraSARX and COSMO-SkyMED satellites have a spatial resolution of up to 1 meter. In VHR SAR data, features from individual urban structures (like buildings) can be identified in their characteristic settings in urban settlement patterns. In this paper, we present a novel methodology for the height estimation for generic man made structures from single power SAR data. The proposed approach is based on the definition of a hypothesis on the height of the building and on the simulation of a SAR image for testing that hypothesis. Then a matching procedure is applied between the estimated and the actual SAR images in order to validate the height assumption. The process is iterated for different initial height assumptions until the matching function is satisfied and thus the building height is estimated. The efficiency and the properties of the proposed method are demonstrated for the height estimation of a set of 38 flat- and gable roof buildings using a VHR airborne SAR scene for a residential area in Dorsten, Germany.

  3. CLOUD BASE SIGNATURE IN TRANSMISSION SPECTRA OF EXOPLANET ATMOSPHERES

    SciTech Connect

    Vahidinia, Sanaz; Cuzzi, Jeffrey N.; Marley, Mark; Fortney, Jonathan

    2014-07-01

    We present an analytical model for the transmission spectrum of a transiting exoplanet, showing that a cloud base can produce an observable inflection point in the spectrum. The wavelength and magnitude of the inflection can be used to break the degeneracy between the atmospheric pressure and the abundance of the main cloud material, however, the abundance still depends on cloud particle size. An observed inflection also provides a specific point on the atmospheric P-T profile, giving us a ''thermometer'' to directly validate or rule out postulated cloud species. We apply the model to the transit spectrum of HD 189733b.

  4. RACORO continental boundary layer cloud investigations. 2. Large-eddy simulations of cumulus clouds and evaluation with in-situ and ground-based observations

    DOE PAGESBeta

    Endo, Satoshi; Fridlind, Ann M.; Lin, Wuyin; Vogelmann, Andrew M.; Toto, Tami; Ackerman, Andrew S.; McFarquhar, Greg M.; Jackson, Robert C.; Jonsson, Haflidi H.; Liu, Yangang

    2015-06-19

    A 60-hour case study of continental boundary layer cumulus clouds is examined using two large-eddy simulation (LES) models. The case is based on observations obtained during the RACORO Campaign (Routine Atmospheric Radiation Measurement [ARM] Aerial Facility [AAF] Clouds with Low Optical Water Depths [CLOWD] Optical Radiative Observations) at the ARM Climate Research Facility's Southern Great Plains site. The LES models are driven by continuous large-scale and surface forcings, and are constrained by multi-modal and temporally varying aerosol number size distribution profiles derived from aircraft observations. We compare simulated cloud macrophysical and microphysical properties with ground-based remote sensing and aircraft observations.more » The LES simulations capture the observed transitions of the evolving cumulus-topped boundary layers during the three daytime periods, and generally reproduce variations of droplet number concentration with liquid water content (LWC), corresponding to the gradient between the cloud centers and cloud edges at given heights. The observed LWC values fall within the range of simulated values; the observed droplet number concentrations are commonly higher than simulated, but differences remain on par with potential estimation errors in the aircraft measurements. Sensitivity studies examine the influences of bin microphysics versus bulk microphysics, aerosol advection, supersaturation treatment, and aerosol hygroscopicity. Simulated macrophysical cloud properties are found to be insensitive in this non-precipitating case, but microphysical properties are especially sensitive to bulk microphysics supersaturation treatment and aerosol hygroscopicity.« less

  5. RACORO continental boundary layer cloud investigations. 2. Large-eddy simulations of cumulus clouds and evaluation with in-situ and ground-based observations

    SciTech Connect

    Endo, Satoshi; Fridlind, Ann M.; Lin, Wuyin; Vogelmann, Andrew M.; Toto, Tami; Ackerman, Andrew S.; McFarquhar, Greg M.; Jackson, Robert C.; Jonsson, Haflidi H.; Liu, Yangang

    2015-06-19

    A 60-hour case study of continental boundary layer cumulus clouds is examined using two large-eddy simulation (LES) models. The case is based on observations obtained during the RACORO Campaign (Routine Atmospheric Radiation Measurement [ARM] Aerial Facility [AAF] Clouds with Low Optical Water Depths [CLOWD] Optical Radiative Observations) at the ARM Climate Research Facility's Southern Great Plains site. The LES models are driven by continuous large-scale and surface forcings, and are constrained by multi-modal and temporally varying aerosol number size distribution profiles derived from aircraft observations. We compare simulated cloud macrophysical and microphysical properties with ground-based remote sensing and aircraft observations. The LES simulations capture the observed transitions of the evolving cumulus-topped boundary layers during the three daytime periods, and generally reproduce variations of droplet number concentration with liquid water content (LWC), corresponding to the gradient between the cloud centers and cloud edges at given heights. The observed LWC values fall within the range of simulated values; the observed droplet number concentrations are commonly higher than simulated, but differences remain on par with potential estimation errors in the aircraft measurements. Sensitivity studies examine the influences of bin microphysics versus bulk microphysics, aerosol advection, supersaturation treatment, and aerosol hygroscopicity. Simulated macrophysical cloud properties are found to be insensitive in this non-precipitating case, but microphysical properties are especially sensitive to bulk microphysics supersaturation treatment and aerosol hygroscopicity.

  6. RACORO continental boundary layer cloud investigations: 2. Large-eddy simulations of cumulus clouds and evaluation with in situ and ground-based observations

    NASA Astrophysics Data System (ADS)

    Endo, Satoshi; Fridlind, Ann M.; Lin, Wuyin; Vogelmann, Andrew M.; Toto, Tami; Ackerman, Andrew S.; McFarquhar, Greg M.; Jackson, Robert C.; Jonsson, Haflidi H.; Liu, Yangang

    2015-06-01

    A 60 h case study of continental boundary layer cumulus clouds is examined using two large-eddy simulation (LES) models. The case is based on observations obtained during the RACORO Campaign (Routine Atmospheric Radiation Measurement (ARM) Aerial Facility (AAF) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations) at the ARM Climate Research Facility's Southern Great Plains site. The LES models are driven by continuous large-scale and surface forcings and are constrained by multimodal and temporally varying aerosol number size distribution profiles derived from aircraft observations. We compare simulated cloud macrophysical and microphysical properties with ground-based remote sensing and aircraft observations. The LES simulations capture the observed transitions of the evolving cumulus-topped boundary layers during the three daytime periods and generally reproduce variations of droplet number concentration with liquid water content (LWC), corresponding to the gradient between the cloud centers and cloud edges at given heights. The observed LWC values fall within the range of simulated values; the observed droplet number concentrations are commonly higher than simulated, but differences remain on par with potential estimation errors in the aircraft measurements. Sensitivity studies examine the influences of bin microphysics versus bulk microphysics, aerosol advection, supersaturation treatment, and aerosol hygroscopicity. Simulated macrophysical cloud properties are found to be insensitive in this nonprecipitating case, but microphysical properties are especially sensitive to bulk microphysics supersaturation treatment and aerosol hygroscopicity.

  7. Point Cloud Server (pcs) : Point Clouds In-Base Management and Processing

    NASA Astrophysics Data System (ADS)

    Cura, R.; Perret, J.; Paparoditis, N.

    2015-08-01

    In addition to the traditional Geographic Information System (GIS) data such as images and vectors, point cloud data has become more available. It is appreciated for its precision and true three-Dimensional (3D) nature. However, managing the point cloud can be difficult due to scaling problems and specificities of this data type. Several methods exist but are usually fairly specialised and solve only one aspect of the management problem. In this work, we propose a complete and efficient point cloud management system based on a database server that works on groups of points rather than individual points. This system is specifically designed to solve all the needs of point cloud users: fast loading, compressed storage, powerful filtering, easy data access and exporting, and integrated processing. Moreover, the system fully integrates metadata (like sensor position) and can conjointly use point clouds with images, vectors, and other point clouds. The system also offers in-base processing for easy prototyping and parallel processing and can scale well. Lastly, the system is built on open source technologies; therefore it can be easily extended and customised. We test the system will several billion points of point clouds from Lidar (aerial and terrestrial ) and stereo-vision. We demonstrate ~ 400 million pts/h loading speed, user-transparent greater than 2 to 4:1 compression ratio, filtering in the approximately 50 ms range, and output of about a million pts/s, along with classical processing, such as object detection.

  8. Lidar based vegetation height models to quantify carbon stocks in Galveston saltmarshes

    NASA Astrophysics Data System (ADS)

    Kulawardhana, R. W.; Popescu, S. C.; Feagin, R. A.

    2012-12-01

    Concern over global climate change has stimulated much interest in identifying existing and potential carbon sinks. Wetland ecosystems are highly recognized for their high productivity and thus as major terrestrial carbon (C) sinks. The rapid decline in the extent and health of these wetland ecosystems has created a need for non-destructive methods for the study of their C dynamics. However, these biomass estimates are mostly based on vegetation structural properties, particularly based on vegetation height models. Hence, for better quantification of vegetation biomass and C estimates, the accuracy of vegetation height models derived using lidar data is of paramount importance. Yet, unlike in woody vegetation dominated ecosystems, the use of lidar in saltmarshes is limited due to several reasons: 1) relatively dense vegetation cover limits laser penetration affecting the accuracy of terrain and thus vegetation height estimates; and 2) relatively shorter vegetation demands high point density data with high vertical accuracy to capture relatively smaller differences between terrain and vegetation canopy surfaces. Thus, the use of lidar data to characterize saltmarsh vegetation community demands appropriate methodologies. Our overall objective in this study was to develop a methodology for deriving salt marsh vegetation height models using airborne lidar data. More specific objectives involved: (1) understanding the interaction between discrete-return airborne lidar data and marsh vegetation; (2) finding appropriate grid sizes for deriving terrain and vegetation height models; and (3) analyze lidar-derived surface accuracies by comparing estimates to field measurements. In this study, we used 1m point spacing airborne lidar data from Federal Emergency Management Agency (FEMA) program to derive vegetation height models (VHM) for Spartina alterniflora saltmarshes in Galveston, Texas. We first derived digital terrain models (DEMs) and verified their vertical accuracy using field elevation data obtained using survey grade GPS. These DEMs served as input for deriving VHMs at different grid sizes (i.e. 1m, 3m, 5m and 10m). These VHMs were evaluated against field-collected vegetation height measurements collected using different approaches. Field measurements of vegetation heights include visual estimates for different grid sizes and also individual plant and culm heights. With this work, we seek to develop a remote sensing (RS) based approach to predict vegetation biomass (and thus C) in these salt marsh ecosystems using lidar data available for much of the coastal United States. Our study brings a contribution to the methods of estimating biomass and thus C estimates based on light detection and ranging (lidar) data as a nondestructive method.

  9. 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.

    2014-09-01

    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. liquid water content) and microphysical (e.g. effective radius) 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.

  10. Search Engine Prototype System Based on Cloud Computing

    NASA Astrophysics Data System (ADS)

    Han, Jinyu; Hu, Min; Sun, Hongwei

    With the development of Internet, IT support systems need to provide more storage space and faster computing power for Internet applications such as search engine. The emergence of cloud computing can effectively solve these problems. We present a search engine prototype system based on cloud computing platform in this paper.

  11. Development of Satellite-based Climatology of Low-level Cloud and Fog in Mountain Terrain

    NASA Astrophysics Data System (ADS)

    Duan, Y.; Barros, A. P.

    2014-12-01

    The presence of orographic clouds and fog has major environmental and economic implications that the potential shift in the space-time distribution can effectively redistribute freshwater resources and threaten the sustainability of the ecology, geomorphology and hydrology of mountainous regions and adjacent basins. This includes the Southern Appalachian Mountains, which rely closely on the moisture input from fog, cap clouds and light rainfall, as well as cloud forests in the Andes with frequent occurrence of dense fog. However, the applicability of fog forecasting models becomes limited in regions of complex terrain. The motivation of this project is to develop a satellite-based hydroclimatology and physical parameterization of orographic low-level clouds and fog regimes in the Southern Appalachians using a general methodology that can be applied to mountainous regions elsewhere. An algorithm for the detection and extraction of stratus clouds and fog was developed using changes in vertical gradients of CPR reflectivity and liquid water products from almost 5-years of CLOUDSAT and SRTM terrain data. This population of low-level clouds and fog will be analyzed with GOES infrared and visible imagery, MODIS and CALIPSO products, and with airport cloud height and visibility records to expand the spatial coverage beyond narrow satellite sensor swaths. The climatology will be further developed through integration with results from WRF simulations for selected periods since the bulk of the PMM network has been in place (2008-present) to aid in defining meteorological and time-of-day constraints in the interpretation of simulated satellite radar reflectivity profiles. The overarching goal is to infer a representation of the diurnal cycle, seasonal and inter-annual variations of the vertical distribution of LWC and hydrometeors in orographic clouds and fog that vary spatially with landform toward developing a more general parameterization of seeder-feeder interactions in microphysical models.

  12. Community-based complex cloud data center

    NASA Astrophysics Data System (ADS)

    Filiposka, Sonja; Juiz, Carlos

    2015-02-01

    The communication infrastructure is a critical component of a large-scale cloud data center. It needs to provide the best performance available while keeping overprovisioning and, lately even more important, power consumption, to the minimum. Aiming to provide a unified solution that will have high performance together with economical benefits and power consumption reduction, in this paper, we propose a new community-based scale-free model for data center network architecture. By comparing the proposed model to other similar solutions we show that the performance of the network in terms of average path length, bandwidth and resilience is similar to the state-of-the-art models. In our presented detailed analysis of the model properties, our focus is set on exploring how heterogeneity in terms of different type of network equipment influences the basic network properties. We also present solutions and network metrics that can be used in conjunction to the introduced community structure in order to additionally increase the performance.

  13. Injury Severity Score based estimation of height of fall in bus rolling down the cliff.

    PubMed

    Radojevic, Nemanja; Curovic, Ivana; Atanasijevic, Tatjana; Lazovic, Ranko

    2015-08-01

    A case of bus rollover into the canyon, 40 m down the road, with 47 occupants out of which 18 were fatally injured, was used to compute the Injury Severity Score (ISS) for each passengers as well as the equivalent free fall for this particular accident, to be compared to the height of fall as estimated by the Lau's model based on ISS, resulting the conclusion whether Lau's model and the computation of ISS can be considered reliable to estimate the height of fall in any other case. Dealing with this, we would be also able to assess a protective potential of the bus on occupants while it falls from the height. By using classic energy-related mechanical formulas the presented rollover down the cliff has been transferred into a corresponding free fall from the height (10 m). ISS for each passenger has been used to establish height bands of the corresponding free fall. The analysis of the presented case showed that only 30% of bus passengers sustained injuries similar to the injuries expected in the fall from height in the range of 10-20 m. The chances to be non-severely injured as a consequence of the fall in a bus is 43%, but still remains a very high chance (27%) to sustain injures more severe than expected for the equivalent free fall from height out of a vehicle. Moreover, eight passengers sustained pulmonary detraction which is characteristic of the fall above 40 m. The conclusion is that this mathematical computing for transferring one way of motion into another one may be useful for any other event similar to the fall from height and further usage of Lau's modules. Also, estimated severity of the injuries expressed through ISS can be merely an approximating indicator of the height of the fall of the bus, so ISS is not able to estimate the exact height. Finally, in majority of cases the protective potential of the bus may preserve from severe body damage, but the mortality rate still stands on a very high level. PMID:26165672

  14. Comparing the cloud vertical structure derived from several methods based on measured atmospheric profiles and active surface measurements

    NASA Astrophysics Data System (ADS)

    Costa-Surós, M.; Calbó, J.; González, J. A.; Long, C. N.

    2013-06-01

    The cloud vertical distribution and especially the cloud base height, which is linked to cloud type, is an important characteristic in order to describe the impact of clouds in a changing climate. In this work several methods to estimate the cloud vertical structure (CVS) based on atmospheric sounding profiles are compared, considering number and position of cloud layers, with a ground based system which is taken as a reference: the Active Remote Sensing of Clouds (ARSCL). All methods establish some conditions on the relative humidity, and differ on the use of other variables, the thresholds applied, or the vertical resolution of the profile. In this study these methods are applied to 125 radiosonde profiles acquired at the ARM Southern Great Plains site during all seasons of year 2009 and endorsed by GOES images, to confirm that the cloudiness conditions are homogeneous enough across their trajectory. The overall agreement for the methods ranges between 44-88%; four methods produce total agreements around 85%. Further tests and improvements are applied on one of these methods. In addition, we attempt to make this method suitable for low resolution vertical profiles, which could be useful in atmospheric modeling. The total agreement, even when using low resolution profiles, can be improved up to 91% if the thresholds for a moist layer to become a cloud layer are modified to minimize false negatives with the current data set, thus improving overall agreement.

  15. Reconciling Ground-Based and Space-Based Estimates of the Frequency of Occurrence and Radiative Effect of Clouds around Darwin, Australia

    SciTech Connect

    Protat, Alain; Young, Stuart; McFarlane, Sally A.; L'Ecuyer, Tristan; Mace, Gerald G.; Comstock, Jennifer M.; Long, Charles N.; Berry, Elizabeth; Delanoe, Julien

    2014-02-01

    The objective of this paper is to investigate whether estimates of the cloud frequency of occurrence and associated cloud radiative forcing as derived from ground-based and satellite active remote sensing and radiative transfer calculations can be reconciled over a well instrumented active remote sensing site located in Darwin, Australia, despite the very different viewing geometry and instrument characteristics. It is found that the ground-based radar-lidar combination at Darwin does not detect most of the cirrus clouds above 10 km (due to limited lidar detection capability and signal obscuration by low-level clouds) and that the CloudSat radar - Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) combination underreports the hydrometeor frequency of occurrence below 2 km height, due to instrument limitations at these heights. The radiative impact associated with these differences in cloud frequency of occurrence is large on the surface downwelling shortwave fluxes (ground and satellite) and the top-of atmosphere upwelling shortwave and longwave fluxes (ground). Good agreement is found for other radiative fluxes. Large differences in radiative heating rate as derived from ground and satellite radar-lidar instruments and RT calculations are also found above 10 km (up to 0.35 Kday-1 for the shortwave and 0.8 Kday-1 for the longwave). Given that the ground-based and satellite estimates of cloud frequency of occurrence and radiative impact cannot be fully reconciled over Darwin, caution should be exercised when evaluating the representation of clouds and cloud-radiation interactions in large-scale models and limitations of each set of instrumentation should be considered when interpreting model-observations differences.

  16. Uav-Based Photogrammetric Point Clouds - Tree STEM Mapping in Open Stands in Comparison to Terrestrial Laser Scanner Point Clouds

    NASA Astrophysics Data System (ADS)

    Fritz, A.; Kattenborn, T.; Koch, B.

    2013-08-01

    In both ecology and forestry, there is a high demand for structural information of forest stands. Forest structures, due to their heterogeneity and density, are often difficult to assess. Hence, a variety of technologies are being applied to account for this "difficult to come by" information. Common techniques are aerial images or ground- and airborne-Lidar. In the present study we evaluate the potential use of unmanned aerial vehicles (UAVs) as a platform for tree stem detection in open stands. A flight campaign over a test site near Freiburg, Germany covering a target area of 120 × 75 [m2] was conducted. The dominant tree species of the site is oak (quercus robur) with almost no understory growth. Over 1000 images with a tilt angle of 45° were shot. The flight pattern applied consisted of two antipodal staggered flight routes at a height of 55 [m] above the ground. We used a Panasonic G3 consumer camera equipped with a 14-42 [mm] standard lens and a 16.6 megapixel sensor. The data collection took place in leaf-off state in April 2013. The area was prepared with artificial ground control points for transformation of the structure-from-motion (SFM) point cloud into real world coordinates. After processing, the results were compared with a terrestrial laser scanner (TLS) point cloud of the same area. In the 0.9 [ha] test area, 102 individual trees above 7 [cm] diameter at breast height were located on in the TLS-cloud. We chose the software CMVS/PMVS-2 since its algorithms are developed with focus on dense reconstruction. The processing chain for the UAV-acquired images consists of six steps: a. cleaning the data: removing of blurry, under- or over exposed and off-site images; b. applying the SIFT operator [Lowe, 2004]; c. image matching; d. bundle adjustment; e. clustering; and f. dense reconstruction. In total, 73 stems were considered as reconstructed and located within one meter of the reference trees. In general stems were far less accurate and complete as in the TLS-point cloud. Only few stems were considered to be fully reconstructed. From the comparison of reconstruction achievement with respect to height above ground, we can state that reconstruction accuracy decreased in the crown layer of the stand. In addition we were cutting 50 [cm] slices in z-direction and applied a robust cylinder fit to the stem slices. Radii of the TLS-cloud and the SFM-cloud surprisingly correlated well with a Pearson's correlation coefficient of r = 0.696. This first study showed promising results for UAV-based forest structure modelling. Yet, there is a demand for additional research with regard to vegetation stages, flight pattern, processing setup and the utilisation of spectral information.

  17. pCloud: A Cloud-based Power Market Simulation Environment

    SciTech Connect

    Rudkevich, Aleksandr; Goldis, Evgeniy

    2012-12-02

    This research conducted by the Newton Energy Group, LLC (NEG) is dedicated to the development of pCloud: a Cloud-based Power Market Simulation Environment. pCloud is offering power industry stakeholders the capability to model electricity markets and is organized around the Software as a Service (SaaS) concept -- a software application delivery model in which software is centrally hosted and provided to many users via the internet. During the Phase I of this project NEG developed a prototype design for pCloud as a SaaS-based commercial service offering, system architecture supporting that design, ensured feasibility of key architecture's elements, formed technological partnerships and negotiated commercial agreements with partners, conducted market research and other related activities and secured funding for continue development of pCloud between the end of Phase I and beginning of Phase II, if awarded. Based on the results of Phase I activities, NEG has established that the development of a cloud-based power market simulation environment within the Windows Azure platform is technologically feasible, can be accomplished within the budget and timeframe available through the Phase II SBIR award with additional external funding. NEG believes that pCloud has the potential to become a game-changing technology for the modeling and analysis of electricity markets. This potential is due to the following critical advantages of pCloud over its competition: - Standardized access to advanced and proven power market simulators offered by third parties. - Automated parallelization of simulations and dynamic provisioning of computing resources on the cloud. This combination of automation and scalability dramatically reduces turn-around time while offering the capability to increase the number of analyzed scenarios by a factor of 10, 100 or even 1000. - Access to ready-to-use data and to cloud-based resources leading to a reduction in software, hardware, and IT costs. - Competitive pricing structure, which will make high-volume usage of simulation services affordable. - Availability and affordability of high quality power simulators, which presently only large corporate clients can afford, will level the playing field in developing regional energy policies, determining prudent cost recovery mechanisms and assuring just and reasonable rates to consumers. - Users that presently do not have the resources to internally maintain modeling capabilities will now be able to run simulations. This will invite more players into the industry, ultimately leading to more transparent and liquid power markets.

  18. Characteristics of Borneo and Sumatra fire plume heights and smoke clouds and their impact on regional El Nio-induced drought

    NASA Astrophysics Data System (ADS)

    Tosca, Michael; Randerson, James; Zender, Charles; Flanner, Mark; Nelson, David; Diner, David; Rasch, Phil; Logan, Jennifer

    2010-05-01

    During the dry season, anthropogenic fires burn the tropical forests and peatlands of equatorial Asia and produce regionally expansive smoke clouds. We estimated the altitude of smoke from these fires, characterized the sensitivity of this smoke to regional drought and El Nio variability, and investigated its effect on climate. We used the MISR satellite product and MISR INteractive eXplorer (MINX) software to estimate the heights of 382 smoke plumes (smoke with a visible surface source and transport direction) on Borneo and 121 plumes on Sumatra for 2001-2009. In addition, we estimated the altitudes of 10 smoke clouds (opaque regions of smoke with no detectable surface source or transport direction) on Borneo for 2006. Most smoke plumes (80%) were observed during El Nio events (2002, 2004, 2006, 2009); this is consistent with higher aerosol optical depths observed during El Nio-induced drought. Annually averaged plume heights on Borneo were positively correlated to the Oceanic Nio Index (ONI), an indicator of El Nio (r2 = 0.53). The mean plume height for all El Nio years was 765.8 19.7m, compared to 711.4 28.7 for non-El Nio years. The median altitude of all 10 smoke clouds observed on Borneo during 2006 was 1313m, compared to a median 787m for smoke plume grid cells. The area covered by all smoke plumes from 2006 corresponded to approximately three individual smoke clouds. We investigated the climate response to these expansive smoke clouds using the Community Atmosphere Model (CAM). Climate variables from two 30 year simulations were compared: one simulation was forced with fire emissions typical of a dry (El Nio) burning year, while the other was forced with emissions typical of a low (La Nia) burning year. Fire aerosols reduced net shortwave radiation at the surface during August-October by an average of 10% in the region encompassing most of Sumatra and Borneo (90E-120E, 5S-5N). The reductions in net radiation cooled both ocean (0.5 0.3C) and land (0.4 0.2C) temperatures during these months. Tropospheric heating from black carbon (BC) absorption increased substantially (20.5 9.3 W m-2), but was balanced by an overall reduction in latent heating. The combination of decreased SSTs and increased atmospheric heating reduced regional precipitation by 0.9 0.6 mm d-1 (10%). This implies that the vulnerability of ecosystems to fire was increased because the reductions in precipitation exceeded those for evapotranspiration. Together, the satellite and modeling results imply a possible positive feedback loop in which anthropogenic burning in the region intensifies drought stress during El Nio.

  19. Cloud cover classification through simultaneous ground-based measurements of solar and infrared radiation

    NASA Astrophysics Data System (ADS)

    Orsini, Antonio; Tomasi, Claudio; Calzolari, Francescopiero; Nardino, Marianna; Cacciari, Alessandra; Georgiadis, Teodoro

    2002-04-01

    Simultaneous measurements of downwelling short-wave solar irradiance and incoming total radiation flux were performed at the Reeves Nevè glacier station (1200 m MSL) in Antarctica on 41 days from late November 1994 to early January 1995, employing the upward sensors of an albedometer and a pyrradiometer. The downwelling short-wave radiation measurements were analysed following the Duchon and O'Malley [J. Appl. Meteorol. 38 (1999) 132] procedure for classifying clouds, using the 50-min running mean values of standard deviation and the ratio of scaled observed to scaled clear-sky irradiance. Comparing these measurements with the Duchon and O'Malley rectangular boundaries and the local human observations of clouds collected on 17 days of the campaign, we found that the Duchon and O'Malley classification method obtained a success rate of 93% for cirrus and only 25% for cumulus. New decision criteria were established for some polar cloud classes providing success rates of 94% for cirrus, 67% for cirrostratus and altostratus, and 33% for cumulus and altocumulus. The ratios of the downwelling short-wave irradiance measured for cloudy-sky conditions to that calculated for clear-sky conditions were analysed in terms of the Kasten and Czeplak [Sol. Energy 24 (1980) 177] formula together with simultaneous human observations of cloudiness, to determine the empirical relationship curves providing reliable estimates of cloudiness for each of the three above-mentioned cloud classes. Using these cloudiness estimates, the downwelling long-wave radiation measurements (obtained as differences between the downward fluxes of total and short-wave radiation) were examined to evaluate the downwelling long-wave radiation flux normalised to totally overcast sky conditions. Calculations of the long-wave radiation flux were performed with the MODTRAN 3.7 code [Kneizys, F.X., Abreu, L.W., Anderson, G.P., Chetwynd, J.H., Shettle, E.P., Berk, A., Bernstein, L.S., Robertson, D.C., Acharya, P., Rothman, L.S., Selby, J.E.A., Gallery, W.O., Clough, S.A., 1996. In: Abreu, L.W., Anderson, G.P. (Eds.), The MODTRAN 2/3 Report and LOWTRAN 7 MODEL. Contract F19628-91-C.0132, Phillips Laboratory, Geophysics Directorate, PL/GPOS, Hanscom AFB, MA, 261 pp.] for both clear-sky and cloudy-sky conditions, considering various cloud types characterised by different cloud base altitudes and vertical thicknesses. From these evaluations, best-fit curves of the downwelling long-wave radiation flux were defined as a function of the cloud base height for the three polar cloud classes. Using these relationship curves, average estimates of the cloud base height were obtained from the three corresponding sub-sets of long-wave radiation measurements. The relative frequency histograms of the cloud base height defined by examining these three sub-sets were found to present median values of 4.7, 1.7 and 3.6 km for cirrus, cirrostratus/altostratus and cumulus/altocumulus, respectively, while median values of 6.5, 1.8 and 2.9 km were correspondingly determined by analysing only the measurements taken together with simultaneous cloud observations.

  20. Stellar Encounters with the Oort Cloud Based on Hipparcos Data

    NASA Technical Reports Server (NTRS)

    Garcia-Sanchez, J.; Preston, R. A.; Jones, D. L.; Weissman, P. R.; Lestrade, J. F.; Latham, D. W.; Stefanik, R. P.

    1998-01-01

    We have combined Hipparcos proper motion and parallax data for nearby stars with ground-based radial velocity measurements to find stars which may have passed (or will pass) close enough to the Sun to perturb the Oort cloud.

  1. Plume height, volume, and classification of explosive volcanic eruptions based on the Weibull function

    NASA Astrophysics Data System (ADS)

    Bonadonna, Costanza; Costa, Antonio

    2013-08-01

    The Weibull distribution between volume and square root of isopach area has been recently introduced for determining volume of tephra deposits, which is crucial to the assessment of the magnitude and hazards of explosive volcanoes. We show how the decay of the size of the largest lithics with the square root of isopleth area can also be well described using a Weibull function and how plume height correlates strongly with corresponding Weibull parameters. Variations of median grain size (Md ϕ) values with square root of area of the associated contours can be, similarly, well fitted with a Weibull function. Weibull parameters, derived for both the thinning of tephra deposits and the decrease of grain size (both maximum lithic diameter and Md ϕ), with a proxy for the distance from vent (e.g., square root of isoline areas) can be combined to classify the style of explosive volcanic eruptions. Accounting for the uncertainty in the derivation of eruptive parameters (e.g., plume height and volume of tephra deposits) is crucial to any classification of eruptive style and hazard assessment. Considering a typical uncertainty of 20 % for the determination of plume height, a new eruption classification scheme based on selected Weibull parameters is proposed. Ultraplinian, Plinian, Subplinian, and small-moderate explosive eruptions are defined on the ground of plume height and mass eruption rate. Overall, the Weibull fitting represents a versatile and reliable strategy for the estimation of both the volume of tephra deposits and the height of volcanic plumes and for the classification of eruptive style. Nonetheless, due to the typically large uncertainties (mainly due to availability of data, compilation of isopach and isopleth maps, and discrepancies from empirical best fits), plume height, volume, and magnitude of explosive eruptions cannot be considered as absolute values, regardless of the technique used. It is important that various empirical and analytical methods are applied in order to assess such an uncertainty.

  2. The Retrieval of Stratocumulus Cloud Properties by Ground-Based Cloud Radar.

    NASA Astrophysics Data System (ADS)

    Fox, Neil I.; Illingworth, Anthony J.

    1997-05-01

    The radiative characteristics of stratocumulus clouds are dependent upon their microphysical properties, primarily the liquid water content and effective radius of the drop population. Aircraft observations of droplet spectra in warm stratocumulus over the North Atlantic and around the British Isles by the Hercules C-130 aircraft of the U.K. Meteorological Office Meteorological Research Flight have been used to calculate the radar reflectivity, liquid water content, and effective radius. Empirically derived relationships, found from more than 4000 km of flight data on 11 separate days, that link reflectivity with either liquid water content or effective radius have been derived. These empirical relationships are significantly different from those predicted if the cloud droplet spectrum is modeled as a gamma function. Occasional drizzle-sized drops are frequently present within the cloud, and even though their concentration is very low, they dominate the reflectivity and these empirical relationships fail. However, although the drizzle drops increase the reflectivity, they have a negligible effect on the liquid water content and effective radius of the cloud. As these drops have a significant fall velocity in comparison to the cloud droplets, it is suggested that a ground-based Doppler radar could separate the components of the reflectivity due to bimodal drop spectra and the vertical structure of the cloud properties that determine radiative transfer could be retrieved.

  3. Cloud Computing Based E-Learning System

    ERIC Educational Resources Information Center

    Al-Zoube, Mohammed; El-Seoud, Samir Abou; Wyne, Mudasser F.

    2010-01-01

    Cloud computing technologies although in their early stages, have managed to change the way applications are going to be developed and accessed. These technologies are aimed at running applications as services over the internet on a flexible infrastructure. Microsoft office applications, such as word processing, excel spreadsheet, access database…

  4. Cloud Computing Based E-Learning System

    ERIC Educational Resources Information Center

    Al-Zoube, Mohammed; El-Seoud, Samir Abou; Wyne, Mudasser F.

    2010-01-01

    Cloud computing technologies although in their early stages, have managed to change the way applications are going to be developed and accessed. These technologies are aimed at running applications as services over the internet on a flexible infrastructure. Microsoft office applications, such as word processing, excel spreadsheet, access database

  5. Hierarchical control of ride height system for electronically controlled air suspension based on variable structure and fuzzy control theory

    NASA Astrophysics Data System (ADS)

    Xu, Xing; Zhou, Kongkang; Zou, Nannan; Jiang, Hong; Cui, Xiaoli

    2015-09-01

    The current research of air suspension mainly focuses on the characteristics and design of the air spring. In fact, electronically controlled air suspension (ECAS) has excellent performance in flexible height adjustment during different driving conditions. However, the nonlinearity of the ride height adjusting system and the uneven distribution of payload affect the control accuracy of ride height and the body attitude. Firstly, the three-point measurement system of three height sensors is used to establish the mathematical model of the ride height adjusting system. The decentralized control of ride height and the centralized control of body attitude are presented to design the ride height control system for ECAS. The exact feedback linearization method is adopted for the nonlinear mathematical model of the ride height system. Secondly, according to the hierarchical control theory, the variable structure control (VSC) technique is used to design a controller that is able to adjust the ride height for the quarter-vehicle anywhere, and each quarter-vehicle height control system is independent. Meanwhile, the three-point height signals obtained by three height sensors are tracked to calculate the body pitch and roll attitude over time, and then by calculating the deviation of pitch and roll and its rates, the height control correction is reassigned based on the fuzzy algorithm. Finally, to verify the effectiveness and performance of the proposed combined control strategy, a validating test of ride height control system with and without road disturbance is carried out. Testing results show that the height adjusting time of both lifting and lowering is over 5 s, and the pitch angle and the roll angle of body attitude are less than 0.15°. This research proposes a hierarchical control method that can guarantee the attitude stability, as well as satisfy the ride height tracking system.

  6. Robust Analysis of Network-Based Real-Time Kinematic for GNSS-Derived Heights

    PubMed Central

    Bae, Tae-Suk; Grejner-Brzezinska, Dorota; Mader, Gerald; Dennis, Michael

    2015-01-01

    New guidelines and procedures for real-time (RT) network-based solutions are required in order to support Global Navigation Satellite System (GNSS) derived heights. Two kinds of experiments were carried out to analyze the performance of the network-based real-time kinematic (RTK) solutions. New test marks were installed in different surrounding environments, and the existing GPS benchmarks were used for analyzing the effect of different factors, such as baseline lengths, antenna types, on the final accuracy and reliability of the height estimation. The RT solutions are categorized into three groups: single-base RTK, multiple-epoch network RTK (mRTN), and single-epoch network RTK (sRTN). The RTK solution can be biased up to 9 mm depending on the surrounding environment, but there was no notable bias for a longer reference base station (about 30 km) In addition, the occupation time for the network RTK was investigated in various cases. There is no explicit bias in the solution for different durations, but smoother results were obtained for longer durations. Further investigation is needed into the effect of changing the occupation time between solutions and into the possibility of using single-epoch solutions in precise determination of heights by GNSS. PMID:26516856

  7. Robust Analysis of Network-Based Real-Time Kinematic for GNSS-Derived Heights.

    PubMed

    Bae, Tae-Suk; Grejner-Brzezinska, Dorota; Mader, Gerald; Dennis, Michael

    2015-01-01

    New guidelines and procedures for real-time (RT) network-based solutions are required in order to support Global Navigation Satellite System (GNSS) derived heights. Two kinds of experiments were carried out to analyze the performance of the network-based real-time kinematic (RTK) solutions. New test marks were installed in different surrounding environments, and the existing GPS benchmarks were used for analyzing the effect of different factors, such as baseline lengths, antenna types, on the final accuracy and reliability of the height estimation. The RT solutions are categorized into three groups: single-base RTK, multiple-epoch network RTK (mRTN), and single-epoch network RTK (sRTN). The RTK solution can be biased up to 9 mm depending on the surrounding environment, but there was no notable bias for a longer reference base station (about 30 km) In addition, the occupation time for the network RTK was investigated in various cases. There is no explicit bias in the solution for different durations, but smoother results were obtained for longer durations. Further investigation is needed into the effect of changing the occupation time between solutions and into the possibility of using single-epoch solutions in precise determination of heights by GNSS. PMID:26516856

  8. Cloud-based printing for mobile devices

    NASA Astrophysics Data System (ADS)

    Bhatti, Nina; O'Brien-Strain, Eamonn; Liu, Jerry

    2010-02-01

    Consumers are increasingly using their smart phones to view web pages. However, there is no native operating system support for printing these web pages. We propose to overcome two barriers to printing from mobile devices - the inability to connect and transmit to a printer and the typically poor format of printed web pages. Our system includes a client component that causes the web browser to upload the page (as a URL reference for public pages or the DOM content for private pages) to a cloud service that extracts the content and formats it for printing. We transfer the printready content to the HP CloudPrint service and leverage its ability to locate printers and transmit print jobs. We have built a working system the uses iPhones and Windows Mobile devices clients, but the system can be extended to include other clients.

  9. Volcanic plume height measured by seismic waves based on a mechanical model

    USGS Publications Warehouse

    Prejean, Stephanie G.; Brodsky, Emily E.

    2011-01-01

    In August 2008 an unmonitored, largely unstudied Aleutian volcano, Kasatochi, erupted catastrophically. Here we use seismic data to infer the height of large eruptive columns such as those of Kasatochi based on a combination of existing fluid and solid mechanical models. In so doing, we propose a connection between a common, observable, short-period seismic wave amplitude to the physics of an eruptive column. To construct a combined model, we estimate the mass ejection rate of material from the vent on the basis of the plume height, assuming that the height is controlled by thermal buoyancy for a continuous plume. Using the estimated mass ejection rate, we then derive the equivalent vertical force on the Earth through a momentum balance. Finally, we calculate the far-field surface waves resulting from the vertical force. The model performs well for recent eruptions of Kasatochi and Augustine volcanoes if v, the velocity of material exiting the vent, is 120-230 m s-1. The consistency between the seismically inferred and measured plume heights indicates that in these cases the far-field ~1 s seismic energy radiated by fluctuating flow in the volcanic jet during the eruption is a useful indicator of overall mass ejection rates. Thus, use of the model holds promise for characterizing eruptions and evaluating ash hazards to aircraft in real time on the basis of far-field short-period seismic data. This study emphasizes the need for better measurements of eruptive plume heights and a more detailed understanding of the full spectrum of seismic energy radiated coeruptively.

  10. Barrier height enhancement of Ni/GaN Schottky diode using Ru based passivation scheme

    SciTech Connect

    Kumar, Ashish Kumar, Mukesh; Singh, R.; Kaur, Riajeet; Joshi, Amish G.; Vinayak, Seema

    2014-03-31

    Wet chemical passivation of n-GaN surface using Ru based solution has been reported. X-ray photoelectron spectroscopy characterization of the GaN surface revealed removal of surface oxides by the introduction of Ru complex species. Ni/n-GaN Schottky barrier diodes were fabricated on passivated GaN and a remarkable improvement in Schottky barrier height from 0.76 eV to 0.92 eV was observed.

  11. A 12-channel VMEbus-based pulse-height analysis module

    SciTech Connect

    Arnone, G.J.

    1993-12-01

    The author describes a 12-channel VMEbus-based pulse-height analysis board that was designed for use in a high-rate, multidetector, gamma-ray imaging system. This module was designed to minimize dead-time losses and to allow all key parameters to be software controlled. Gamma-ray detectors are connected directly to this module, eliminating the need for additional electronics.

  12. Ground-based remote sensing of methane height profiles with a tunable diode laser heterodyne spectrometer

    SciTech Connect

    Koide, M.; Taguchi, M.; Fukunsishi, H.; Okano, S.

    1995-02-01

    Height distributions of methane in the troposphere and stratosphere were derived from high resolution absorption spectra observed with a ground-based tunable diode laser heterodyne spectrometer. The center wavenumber of the measured methane absorption line is 1223.1561/cm. In the retrieval of methane height profiles, a volume mixing ratio of methane was assumed to have a constant value in the troposphere and to decrease with a constant rate in the stratosphere. The tropospheric mixing ratio and the decreasing rate in stratosphere were derived to be 1.7 +/- 0.1 ppmv and -0.06 ppmv/km, respectively, for measurements at Tsukuba (36.0 deg N, 140.1 deg E) on December 17 and 20, 1991.

  13. An extreme value model for maximum wave heights based on weather types

    NASA Astrophysics Data System (ADS)

    Rueda, Ana; Camus, Paula; Méndez, Fernando J.; Tomás, Antonio; Luceño, Alberto

    2016-02-01

    Extreme wave heights are climate-related events. Therefore, special attention should be given to the large-scale weather patterns responsible for wave generation in order to properly understand wave climate variability. We propose a classification of weather patterns to statistically downscale daily significant wave height maxima to a local area of interest. The time-dependent statistical model obtained here is based on the convolution of the stationary extreme value model associated to each weather type. The interdaily dependence is treated by a climate-related extremal index. The model's ability to reproduce different time scales (daily, seasonal, and interannual) is presented by means of its application to three locations in the North Atlantic: Mayo (Ireland), La Palma Island, and Coruña (Spain).

  14. Land appraisal based on cloud model and sales comparison approach

    NASA Astrophysics Data System (ADS)

    Hu, Shiyuan; Li, Deren; Liu, Yaolin; Li, Deyi; Yu, Haifeng

    2007-06-01

    Focusing on the two key aspects of the traditional sales comparison approach, case selection and case quantification of the factors, this article tries to introduce the cloud model and Case-Based Reasoning into sales comparison approach, and brings about the land appraisal approach based on the cloud model and the sales comparison approach. This approach is based on the cloud model, completely considers the fuzziness and the randomness in objects and human knowledge, describes case features with the cloud model, uses cloud uncertainty reasoning, realizes the conversion between the qualitative description and the quantification value of transaction case features ; Also based on case-based reasoning, it analyzes the correlation among different cases, searches for the required comparable one; After the modification of the different land prices of different cases, it completely considers the case features and the weight of the cases, sets up land appraisal model, and finds the price of the case. At last, it gives an example analysis whose result proves the validity and feasibility of the method.

  15. A Cloud-Based Simulation Architecture for Pandemic Influenza Simulation

    PubMed Central

    Eriksson, Henrik; Raciti, Massimiliano; Basile, Maurizio; Cunsolo, Alessandro; Fröberg, Anders; Leifler, Ola; Ekberg, Joakim; Timpka, Toomas

    2011-01-01

    High-fidelity simulations of pandemic outbreaks are resource consuming. Cluster-based solutions have been suggested for executing such complex computations. We present a cloud-based simulation architecture that utilizes computing resources both locally available and dynamically rented online. The approach uses the Condor framework for job distribution and management of the Amazon Elastic Computing Cloud (EC2) as well as local resources. The architecture has a web-based user interface that allows users to monitor and control simulation execution. In a benchmark test, the best cost-adjusted performance was recorded for the EC2 H-CPU Medium instance, while a field trial showed that the job configuration had significant influence on the execution time and that the network capacity of the master node could become a bottleneck. We conclude that it is possible to develop a scalable simulation environment that uses cloud-based solutions, while providing an easy-to-use graphical user interface. PMID:22195089

  16. A cloud-based simulation architecture for pandemic influenza simulation.

    PubMed

    Eriksson, Henrik; Raciti, Massimiliano; Basile, Maurizio; Cunsolo, Alessandro; Fröberg, Anders; Leifler, Ola; Ekberg, Joakim; Timpka, Toomas

    2011-01-01

    High-fidelity simulations of pandemic outbreaks are resource consuming. Cluster-based solutions have been suggested for executing such complex computations. We present a cloud-based simulation architecture that utilizes computing resources both locally available and dynamically rented online. The approach uses the Condor framework for job distribution and management of the Amazon Elastic Computing Cloud (EC2) as well as local resources. The architecture has a web-based user interface that allows users to monitor and control simulation execution. In a benchmark test, the best cost-adjusted performance was recorded for the EC2 H-CPU Medium instance, while a field trial showed that the job configuration had significant influence on the execution time and that the network capacity of the master node could become a bottleneck. We conclude that it is possible to develop a scalable simulation environment that uses cloud-based solutions, while providing an easy-to-use graphical user interface. PMID:22195089

  17. Global surface-based cloud observation for ISCCP

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Visual observations of cloud cover are hindered at night due to inadequate illumination of the clouds. This usually leads to an underestimation of the average cloud cover at night, especially for the amounts of middle and high clouds, in climatologies on surface observations. The diurnal cycles of cloud amounts, if based on all the surface observations, are therefore in error, but they can be obtained more accurately if the nighttime observations are screened to select those made under sufficient moonlight. Ten years of nighttime weather observations from the northern hemisphere in December were classified according to the illuminance of moonlight or twilight on the cloud tops, and a threshold level of illuminance was determined, above which the clouds are apparently detected adequately. This threshold corresponds to light from a full moon at an elevation angle of 6 degrees or from a partial moon at higher elevation, or twilight from the sun less than 9 degrees below the horizon. It permits the use of about 38% of the observations made with the sun below the horizon. The computed diurnal cycles of total cloud cover are altered considerably when this moonlight criterion is imposed. Maximum cloud cover over much of the ocean is now found to be at night or in the morning, whereas computations obtained without benefit of the moonlight criterion, as in our published atlases, showed the time of maximum to be noon or early afternoon in many regions. Cloud cover is greater at night than during the day over the open oceans far from the continents, particularly in summer. However, near noon maxima are still evident in the coastal regions, so that the global annual average oceanic cloud cover is still slightly greater during the day than at night, by 0.3%. Over land, where daytime maxima are still obtained but with reduced amplitude, average cloud cover is 3.3% greater during the daytime. The diurnal cycles of total cloud cover we obtain are compared with those of ISCCP for a few regions; they are generally in better agreement if the moonlight criterion is imposed on the surface observations. Using the moonlight criterion, we have analyzed ten years (1982-1991) of surface weather observations over land and ocean, worldwide, for total cloud cover and for the frequency of occurrence of clear sky, fog and precipitation The global average cloud cover (average of day and night) is about 2% higher if we impose the moonlight criterion than if we use all observations. The difference is greater in winter than in summer, because of the fewer hours of darkness in the summer. The amplitude of the annual cycle of total cloud cover over the Arctic Ocean and at the South Pole is diminished by a few percent when the moonlight criterion is imposed. The average cloud cover for 1982-1991 is found to be 55% for northern hemisphere land, 53% for southern hemisphere land, 66% for northern hemisphere ocean, and 70% for southern hemisphere ocean, giving a global average of 64%. The global average for daytime is 64.6% for nighttime 63.3%.

  18. INS/EKF-based stride length, height and direction intent detection for walking assistance robots.

    PubMed

    Brescianini, Dario; Jung, Jun-Young; Jang, In-Hun; Park, Hyun Sub; Riener, Robert

    2011-01-01

    We propose an algorithm used to obtain the information on stride length, height difference, and direction based on user's intent during walking. For exoskeleton robots used to assist paraplegic patients' walking, this information is used to generate gait patterns by themselves in on-line. To obtain this information, we attach an inertial measurement unit(IMU) on crutches and apply an extended kalman filter-based error correction method to reduce the phenomena of drift due to bias of the IMU. The proposed method is verifed in real walking scenarios including walking, climbing up-stairs, and changing direction of walking with normal. PMID:22275567

  19. A cloud model-based approach for water quality assessment.

    PubMed

    Wang, Dong; Liu, Dengfeng; Ding, Hao; Singh, Vijay P; Wang, Yuankun; Zeng, Xiankui; Wu, Jichun; Wang, Lachun

    2016-07-01

    Water quality assessment entails essentially a multi-criteria decision-making process accounting for qualitative and quantitative uncertainties and their transformation. Considering uncertainties of randomness and fuzziness in water quality evaluation, a cloud model-based assessment approach is proposed. The cognitive cloud model, derived from information science, can realize the transformation between qualitative concept and quantitative data, based on probability and statistics and fuzzy set theory. When applying the cloud model to practical assessment, three technical issues are considered before the development of a complete cloud model-based approach: (1) bilateral boundary formula with nonlinear boundary regression for parameter estimation, (2) hybrid entropy-analytic hierarchy process technique for calculation of weights, and (3) mean of repeated simulations for determining the degree of final certainty. The cloud model-based approach is tested by evaluating the eutrophication status of 12 typical lakes and reservoirs in China and comparing with other four methods, which are Scoring Index method, Variable Fuzzy Sets method, Hybrid Fuzzy and Optimal model, and Neural Networks method. The proposed approach yields information concerning membership for each water quality status which leads to the final status. The approach is found to be representative of other alternative methods and accurate. PMID:26995351

  20. Nuclear spectroscopy pulse height analysis based on digital signal processing techniques

    SciTech Connect

    Simoes, J.B.; Simoes, P.C.P.S.; Correia, C.M.B.A.

    1995-08-01

    A digital approach to pulse height analysis is presented. It consists of entire pulse digitization, using a flash analog-to-digital converter (ADC), being its height estimated by a floating point digital signal processor (DSP) as one parameter of a model best fitting to the pulse samples. The differential nonlinearity (DNL) is reduced by simultaneously adding to the pulse, prior to its digitization, two analog signals provided by a digital-to-analog converter (DAC). One of them is a small amplitude dither signal used to eliminate a bias introduced by the fitting algorithm. The other, with large amplitude, corrects the ADC nonlinearities by a method similar to the well known Gatti`s sliding scale. The simulations carried out showed that, using a 12-bit flash ADC, a 14-bit DAC and a dedicated floating point DSP performing a polynomial fitting to the samples around the pulse peak, it is actually possible to process about 10,000 events per second, with a constant height pulse dispersion of only 4 on 8,192 channels and a very good differential linearity. A prototype system based on the Texas Instruments floating point DSP TMS320C31 and built following the presented methodology has already been tested and performed as expected.

  1. Intuitive Terrain Reconstruction Using Height Observation-Based Ground Segmentation and 3D Object Boundary Estimation

    PubMed Central

    Song, Wei; Cho, Kyungeun; Um, Kyhyun; Won, Chee Sun; Sim, Sungdae

    2012-01-01

    Mobile robot operators must make rapid decisions based on information about the robot’s surrounding environment. This means that terrain modeling and photorealistic visualization are required for the remote operation of mobile robots. We have produced a voxel map and textured mesh from the 2D and 3D datasets collected by a robot’s array of sensors, but some upper parts of objects are beyond the sensors’ measurements and these parts are missing in the terrain reconstruction result. This result is an incomplete terrain model. To solve this problem, we present a new ground segmentation method to detect non-ground data in the reconstructed voxel map. Our method uses height histograms to estimate the ground height range, and a Gibbs-Markov random field model to refine the segmentation results. To reconstruct a complete terrain model of the 3D environment, we develop a 3D boundary estimation method for non-ground objects. We apply a boundary detection technique to the 2D image, before estimating and refining the actual height values of the non-ground vertices in the reconstructed textured mesh. Our proposed methods were tested in an outdoor environment in which trees and buildings were not completely sensed. Our results show that the time required for ground segmentation is faster than that for data sensing, which is necessary for a real-time approach. In addition, those parts of objects that were not sensed are accurately recovered to retrieve their real-world appearances. PMID:23235454

  2. Comparing the cloud vertical structure derived from several methods based on measured atmospheric profiles and active surface measurements

    NASA Astrophysics Data System (ADS)

    Costa-Surós, M.; Calbó, J.; González, J. A.; Long, C. N.

    2014-04-01

    The cloud vertical distribution and especially the cloud base height, which is linked to cloud type, is an important characteristic in order to describe the impact of clouds on climate. In this work several methods to estimate the cloud vertical structure (CVS) based on atmospheric sounding profiles are compared, considering number and position of cloud layers, with a ground based system which is taken as a reference: the Active Remote Sensing of Clouds (ARSCL). All methods establish some conditions on the relative humidity, and differ on the use of other variables, the thresholds applied, or the vertical resolution of the profile. In this study these methods are applied to 193 radiosonde profiles acquired at the ARM Southern Great Plains site during all seasons of year 2009 and endorsed by GOES images, to confirm that the cloudiness conditions are homogeneous enough across their trajectory. The perfect agreement (i.e. when the whole CVS is correctly estimated) for the methods ranges between 26-64%; the methods show additional approximate agreement (i.e. when at least one cloud layer is correctly assessed) from 15-41%. Further tests and improvements are applied on one of these methods. In addition, we attempt to make this method suitable for low resolution vertical profiles, like those from the outputs of reanalysis methods or from the WMO's Global Telecommunication System. The perfect agreement, even when using low resolution profiles, can be improved up to 67% (plus 25% of approximate agreement) if the thresholds for a moist layer to become a cloud layer are modified to minimize false negatives with the current data set, thus improving overall agreement.

  3. Cloud-Based Collaborative Writing and the Common Core Standards

    ERIC Educational Resources Information Center

    Yim, Soobin; Warschauer, Mark; Zheng, Binbin; Lawrence, Joshua F.

    2014-01-01

    The Common Core State Standards emphasize the integration of technology skills into English Language Arts (ELA) instruction, recognizing the demand for technology-based literacy skills to be college- and career- ready. This study aims to examine how collaborative cloud-based writing is used in in a Colorado school district, where one-to-one

  4. Cloud-Based Collaborative Writing and the Common Core Standards

    ERIC Educational Resources Information Center

    Yim, Soobin; Warschauer, Mark; Zheng, Binbin; Lawrence, Joshua F.

    2014-01-01

    The Common Core State Standards emphasize the integration of technology skills into English Language Arts (ELA) instruction, recognizing the demand for technology-based literacy skills to be college- and career- ready. This study aims to examine how collaborative cloud-based writing is used in in a Colorado school district, where one-to-one…

  5. Cloud physics and cloud water sampler comparison during FEBUKO

    NASA Astrophysics Data System (ADS)

    Wieprecht, W.; Acker, K.; Mertes, S.; Collett, J.; Jaeschke, W.; Brüggemann, E.; Möller, D.; Herrmann, H.

    Optical methods for counting and sizing cloud droplets and a wide range of cloud water sampling methods were used to characterize the atmospheric liquid phase during the FEBUKO cloud experiments. Results near cloud base as well as more than 300 m inside the hill cap clouds are presented, reflecting their inhomogeneous nature. The cloud droplet number varies from 50 to 1000 cm -3 and drop sizes between 1 and 20 μm diameter are most frequent. Variations in the liquid water content (LWC) and in the total ion content (TIC) are much smaller when the measurement position is deeper in the cloud. Near cloud base variability in updraft strength and, near cloud top, entrainment processes (droplet evaporation by mixing with drier air, aerosol and gas scavenging) disturb the adiabatic conditions and produce large variations in LWC and chemical composition. Six different active cloud water collectors and impactors were running side by side; they differ in the principle of sampling, in the throughput of cloudy air per unit time and in the calculated 50% cutoff diameter, which influence also their sampling efficiency. Two of them are designed to collect cloud water in two droplet size fractions. Three cloud events were selected by the FEBUKO team for detailed cloud physical and chemical analyses because they serve best the modelling demands concerning connected flow between the upwind, summit and downwind sites for process studies. Frequency distributions of the LWC and, also of the cloud base height are given as statistical parameters for both FEBUKO experiments.

  6. An overview of platforms for cloud based development.

    PubMed

    Fylaktopoulos, G; Goumas, G; Skolarikis, M; Sotiropoulos, A; Maglogiannis, I

    2016-01-01

    This paper provides an overview of the state of the art technologies for software development in cloud environments. The surveyed systems cover the whole spectrum of cloud-based development including integrated programming environments, code repositories, software modeling, composition and documentation tools, and application management and orchestration. In this work we evaluate the existing cloud development ecosystem based on a wide number of characteristics like applicability (e.g. programming and database technologies supported), productivity enhancement (e.g. editor capabilities, debugging tools), support for collaboration (e.g. repository functionality, version control) and post-development application hosting and we compare the surveyed systems. The conducted survey proves that software engineering in the cloud era has made its initial steps showing potential to provide concrete implementation and execution environments for cloud-based applications. However, a number of important challenges need to be addressed for this approach to be viable. These challenges are discussed in the article, while a conclusion is drawn that although several steps have been made, a compact and reliable solution does not yet exist. PMID:26835220

  7. Knowledge-Based Object Detection in Laser Scanning Point Clouds

    NASA Astrophysics Data System (ADS)

    Boochs, F.; Karmacharya, A.; Marbs, A.

    2012-07-01

    Object identification and object processing in 3D point clouds have always posed challenges in terms of effectiveness and efficiency. In practice, this process is highly dependent on human interpretation of the scene represented by the point cloud data, as well as the set of modeling tools available for use. Such modeling algorithms are data-driven and concentrate on specific features of the objects, being accessible to numerical models. We present an approach that brings the human expert knowledge about the scene, the objects inside, and their representation by the data and the behavior of algorithms to the machine. This "understanding" enables the machine to assist human interpretation of the scene inside the point cloud. Furthermore, it allows the machine to understand possibilities and limitations of algorithms and to take this into account within the processing chain. This not only assists the researchers in defining optimal processing steps, but also provides suggestions when certain changes or new details emerge from the point cloud. Our approach benefits from the advancement in knowledge technologies within the Semantic Web framework. This advancement has provided a strong base for applications based on knowledge management. In the article we will present and describe the knowledge technologies used for our approach such as Web Ontology Language (OWL), used for formulating the knowledge base and the Semantic Web Rule Language (SWRL) with 3D processing and topologic built-ins, aiming to combine geometrical analysis of 3D point clouds, and specialists' knowledge of the scene and algorithmic processing.

  8. A cloud-based system for automatic glaucoma screening.

    PubMed

    Fengshou Yin; Damon Wing Kee Wong; Ying Quan; Ai Ping Yow; Ngan Meng Tan; Gopalakrishnan, Kavitha; Beng Hai Lee; Yanwu Xu; Zhuo Zhang; Jun Cheng; Jiang Liu

    2015-08-01

    In recent years, there has been increasing interest in the use of automatic computer-based systems for the detection of eye diseases including glaucoma. However, these systems are usually standalone software with basic functions only, limiting their usage in a large scale. In this paper, we introduce an online cloud-based system for automatic glaucoma screening through the use of medical image-based pattern classification technologies. It is designed in a hybrid cloud pattern to offer both accessibility and enhanced security. Raw data including patient's medical condition and fundus image, and resultant medical reports are collected and distributed through the public cloud tier. In the private cloud tier, automatic analysis and assessment of colour retinal fundus images are performed. The ubiquitous anywhere access nature of the system through the cloud platform facilitates a more efficient and cost-effective means of glaucoma screening, allowing the disease to be detected earlier and enabling early intervention for more efficient intervention and disease management. PMID:26736579

  9. Automatic Single Tree Detection in Plantations using UAV-based Photogrammetric Point clouds

    NASA Astrophysics Data System (ADS)

    Kattenborn, T.; Sperlich, M.; Bataua, K.; Koch, B.

    2014-08-01

    For reasons of documentation, management and certification there is a high interest in efficient inventories of palm plantations on the single plant level. Recent developments in unmanned aerial vehicle (UAV) technology facilitate spatial and temporal flexible acquisition of high resolution 3D data. Common single tree detection approaches are based on Very High Resolution (VHR) satellite or Airborne Laser Scanning (ALS) data. However, VHR data is often limited to clouds and does commonly not allow for height measurements. VHR and in particualar ALS data are characterized by high relatively high acquisition costs. Sperlich et al. (2013) already demonstrated the high potential of UAV-based photogrammetric point clouds for single tree detection using pouring algorithms. This approach was adjusted and improved for an application on palm plantation. The 9.4ha test site on Tarawa, Kiribati, comprised densely scattered growing palms, as well as abundant undergrowth and trees. Using a standard consumer grade camera mounted on an octocopter two flight campaigns at 70m and 100m altitude were performed to evaluate the effect Ground Sampling Distance (GSD) and image overlap. To avoid comission errors and improve the terrain interpolation the point clouds were classified based on the geometric characteristics of the classes, i.e. (1) palm, (2) other vegetation (3) and ground. The mapping accuracy amounts for 86.1 % for the entire study area and 98.2 % for dense growing palm stands. We conclude that this flexible and automatic approach has high capabilities for operational use.

  10. A method of threaten ordering based on cloud model theory

    NASA Astrophysics Data System (ADS)

    Yu, Xin; Wang, Hua; Jiao, Licheng

    2009-10-01

    Situation assessment (SA) is a complex decision-making process in modern aerial defense system. Threaten ordering (TO) problem is one of the most difficult steps in SA. There are a lot of uncertain factors in TO, and traditional evaluation methods have some disadvantages on algorithm measures. To overcome these disadvantages, a method of TO based on cloud model theory is proposed. Firstly the factors of air-targets threat evaluation are analyzed in this paper. Then the reasoning mechanism base on cloud model is designed. In this step the cloud model is used to depict the attributes of target, the model parameters are defined, and the reasoning rule library is established by using the method of Multiple Attribute Decision Making (MADM). The data of targets were input to the reasoning mechanism, and the threat value was gained. Finally the simulation experiments are given to verify the validity of the method.

  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. Retrieval algorithms for cloud motion from ground-based images

    NASA Astrophysics Data System (ADS)

    Bakalova, Kalinka

    We present the preliminary results of a project, focused on obtaining information about the velocity and direction of motion of air masses by means of ground-based measurements of visible cloud motion. This information can be used in short-term local weather forecast and is helpful in studies of the dynamics of the physical processes in clouds. We report the recent progress in the development of algorithms and tools for retrieving the three-dimensional field of vectors of velocity of cloud motion from time series of ground-based digital images. The visible motion of a cloud is the compound effect of the translational drift of the cloud as a whole with the velocity of the adjacent air masses, and of deformations due to the physical processes in the atmosphere. Because of the continuous changes of shape, extracting the translational component in the displacement of a cloud from a series of consecutive images is a highly non-trivial problem. Our approach consists in selecting a set of characteristic reference patterns of the cloud on the first image of the series, tracking them on the subsequent images, and evaluating this way the individual displacement of each reference pattern. Specific algorithms are being developed for the optimal choice of the reference patterns on the starting image and the recognition of these patterns on the subsequent images, depending on the type of the observed cloud. For clouds with low contrast or no edges, such as Stratus, Nimbostratus and Stratocumulus, implementations of the Optical Flow method are under development. For clouds with distinct contours, such as Cumulus and Altocumulus, the edges are decomposed into one-dimensional curvilinear patterns. To reduce the uncertainties, a multi-parametric model of the transformations of the cloud shape between images is defined next which, besides parallel transport, also involves dilatation, rotation, and possibly some local deformations. The parameters of the model are calculated from the individual displacements of the patterns by a least-square fit. What is obtained this way is a smooth approximation to the two-dimensional field of angular velocities of the cloud surface as seen from the observer's position. The three-dimensional vectors of velocity of the cloud are calculated by combining the results of multiple synchronous observations from distant sites. Prior to be put together, the data from different observers are corrected for optical distortion. We analyse the various sources of uncertainty of the calculated velocities of air masses, related to inaccuracy of the digital images, to identification errors in tracking the reference patterns on the series of images and to triangulation. We show that external telemetric information about the distance to the observed clouds may reduce the uncertainty of the results. We also discuss the optimal choice of the time interval between consecutive images as a compromise between the increasing requirements for computational power and the higher efficiency of the pattern recognition methods at shorter time intervals. The work is partially supported by the Bulgarian NFSR under contract NZ-1414/04.

  13. Estimation of liquid water cloud height and fraction using simulated AMSU-A and MHS data. [Advanced Microwave Sounding Unit and Microwave Humidity Sounder

    NASA Technical Reports Server (NTRS)

    Huang, Hung-Lung; Diak, George R.

    1992-01-01

    The rms retrieval errors in cloud top pressure for fully overcast conditions over both land and water surfaces are shown for AMSU-A oxygen channel pair 3 and 5 and MHS water vapor channel pair 4 and 5. For both pairs, the decrease of retrieval skill from high cloud is evident for almost all liquid water contents. For high cloud and medium cloud, the water vapor pair outperforms the oxygen pair. Retrieval accuracy is the best for high and middle clouds and degrades as the cloud top is lower in the atmosphere.

  14. A cloud-based medical image repository

    NASA Astrophysics Data System (ADS)

    Maeder, Anthony J.; Planitz, Birgit M.; El Rifai, Diaa

    2012-02-01

    Many widely used digital medical image collections have been established but these are generally used as raw data sources without related image analysis toolsets. Providing associated functionality to allow specific types of operations to be performed on these images has proved beneficial in some cases (e.g. brain image registration and atlases). However, toolset development to provide generic image analysis functions on medical images has tended to be ad hoc, with Open Source options proliferating (e.g. ITK). Our Automated Medical Image Collection Annotation (AMICA) system is both an image repository, to which the research community can contribute image datasets, and a search/retrieval system that uses automated image annotation. AMICA was designed for the Windows Azure platform to leverage the flexibility and scalability of the cloud. It is intended that AMICA will expand beyond its initial pilot implementation (for brain CT, MR images) to accommodate a wide range of modalities and anatomical regions. This initiative aims to contribute to advances in clinical research by permitting a broader use and reuse of medical image data than is currently attainable. For example, cohort studies for cases with particular physiological or phenotypical profiles will be able to source and include enough cases to provide high statistical power, allowing more individualised risk factors to be assessed and thus allowing screening and staging processes to be optimised. Also, education, training and credentialing of clinicians in image interpretation, will be more effective because it will be possible to select instances of images with specific visual aspects, or correspond to types of cases where reading performance improvement is desirable.

  15. Cloud-Based Technologies: Faculty Development, Support, and Implementation

    ERIC Educational Resources Information Center

    Diaz, Veronica

    2011-01-01

    The number of instructional offerings in higher education that are online, blended, or web-enhanced, including courses and programs, continues to grow exponentially. Alongside the growth of e-learning, higher education has witnessed the explosion of cloud-based or Web 2.0 technologies, a term that refers to the vast array of socially oriented,…

  16. A Cloud-based Approach to Medical NLP

    PubMed Central

    Chard, Kyle; Russell, Michael; Lussier, Yves A.; Mendonça, Eneida A; Silverstein, Jonathan C.

    2011-01-01

    Natural Language Processing (NLP) enables access to deep content embedded in medical texts. To date, NLP has not fulfilled its promise of enabling robust clinical encoding, clinical use, quality improvement, and research. We submit that this is in part due to poor accessibility, scalability, and flexibility of NLP systems. We describe here an approach and system which leverages cloud-based approaches such as virtual machines and Representational State Transfer (REST) to extract, process, synthesize, mine, compare/contrast, explore, and manage medical text data in a flexibly secure and scalable architecture. Available architectures in which our Smntx (pronounced as semantics) system can be deployed include: virtual machines in a HIPAA-protected hospital environment, brought up to run analysis over bulk data and destroyed in a local cloud; a commercial cloud for a large complex multi-institutional trial; and within other architectures such as caGrid, i2b2, or NHIN. PMID:22195072

  17. Game Theory Based Trust Model for Cloud Environment

    PubMed Central

    Gokulnath, K.; Uthariaraj, Rhymend

    2015-01-01

    The aim of this work is to propose a method to establish trust at bootload level in cloud computing environment. This work proposes a game theoretic based approach for achieving trust at bootload level of both resources and users perception. Nash equilibrium (NE) enhances the trust evaluation of the first-time users and providers. It also restricts the service providers and the users to violate service level agreement (SLA). Significantly, the problem of cold start and whitewashing issues are addressed by the proposed method. In addition appropriate mapping of cloud user's application to cloud service provider for segregating trust level is achieved as a part of mapping. Thus, time complexity and space complexity are handled efficiently. Experiments were carried out to compare and contrast the performance of the conventional methods and the proposed method. Several metrics like execution time, accuracy, error identification, and undecidability of the resources were considered. PMID:26380365

  18. Atmospheric Cloud Forecasting in Support of Space Based Applications

    NASA Astrophysics Data System (ADS)

    Alliss, R. J.; Felton, B.; Apling, D.

    2013-09-01

    Many space based applications from imaging to communications are impacted by the atmosphere. Atmospheric impacts such as optical turbulence and clouds are the main drivers for these types of systems. For example, in space based optical communications, clouds will produce channel fades on the order of many hundreds of decibels (dB) thereby breaking the communication link. Optical turbulence can also produce fades but can be compensated for by adaptive optics. The ability to forecast the current and future location and optical thickness of clouds for spaced based to ground optical communications is therefore critical in order to achieve a highly reliable system. We have developed an innovative method for producing such forecasts. These forecasts are intended to provide lead times on the order of several hours so that communication links can be transferred from a current clear ground location to another more desirable ground site. The system is referred to as the Cloud Propagator Forecast (CPF) and it operates on successive, satellite remotely sensed, cloud analyses to produce reliable probability forecasts of future cloud cover conditions at each point location or for the expectation of the amount of skycover in a local skydome about each point location. The forecasting algorithm is a combination of empirical Lagrangian and Eulerian regression over multiple spatial scales, but treats time auto-regressively. Input cloud masks are transformed into proxies first. A cloud cover proxy is a variable which has a more Gaussian distribution than literal cloud cover. For a given pixel, the cloud cover proxy is computed first by determining whether at the initialization time the pixel was clear or cloudy. Clear pixels will be assigned only positive proxies; cloudy pixels will be given only negative proxies. The degree the assigned proxy is different than zero depends on the fraction of pixels in a small neighboring space which have similar cloudy/clearness. The neighboring space is approximately the spatial scale of a skydome and has a temporal scale of one hour. Pixels which are unlike their neighbors will have proxies close to zero, those largely identical to their neighbors will has proxies close to plus or minus one. Final cloud proxies are computed using a non-linear transform to stretch out the extremes into a pseudo-Gaussian distribution. The model then decomposes the proxy fields into scale-filtered components. Longer spatial scale patterns are expected to be more predictable over time; shorted scales less so. Differentiating them allows the model to retain the maximum predictive skill through training. The resulting forecasts have several desirable characteristics. First, they evidence substantial skill when compared to persistence. Additionally, these forecasts extrapolate movement of cloud features, and also allow for degradation of fine scale features without compromising more predictable larger scales. The forecasts are reliable, in that specific probability categories will assess at their stated probabilities, and also consequently unbiased. Details of the algorithm and results used for a realtime spaced based application will be shown at the conference.

  19. Evaluation of Tropical Cirrus Cloud Properties Derived from ECMWF Model Output and Ground Based Measurements over Nauru Island

    SciTech Connect

    Comstock, Jennifer M.; Jakob, Christian

    2004-05-26

    Cirrus clouds play an important role both radiatively and dynamically in the tropics. Understanding the mechanisms responsible for the formation and persistence of tropical cirrus is an important step in accurately predicting cirrus in forecast models. In this study, we compare ground-based measurements of cloud properties with those predicted by the ECMWF model at a location in the tropical western Pacific. Our comparisons of cloud height and optical depth over an 8 month time period indicate that the model and measurements agree relatively well. The ECMWF model predicts cirrus anvils associated with deep convection during convectively active periods, and also isolated cirrus events that are influenced by large-scale vertical ascent. We also show through examination of an upper tropospheric cirrus case that the model produces tropospheric waves that appear to influence the morphology and maintenance of the cirrus layer.

  20. Cloud based emergency health care information service in India.

    PubMed

    Karthikeyan, N; Sukanesh, R

    2012-12-01

    A hospital is a health care organization providing patient treatment by expert physicians, surgeons and equipments. A report from a health care accreditation group says that miscommunication between patients and health care providers is the reason for the gap in providing emergency medical care to people in need. In developing countries, illiteracy is the major key root for deaths resulting from uncertain diseases constituting a serious public health problem. Mentally affected, differently abled and unconscious patients can't communicate about their medical history to the medical practitioners. Also, Medical practitioners can't edit or view DICOM images instantly. Our aim is to provide palm vein pattern recognition based medical record retrieval system, using cloud computing for the above mentioned people. Distributed computing technology is coming in the new forms as Grid computing and Cloud computing. These new forms are assured to bring Information Technology (IT) as a service. In this paper, we have described how these new forms of distributed computing will be helpful for modern health care industries. Cloud Computing is germinating its benefit to industrial sectors especially in medical scenarios. In Cloud Computing, IT-related capabilities and resources are provided as services, via the distributed computing on-demand. This paper is concerned with sprouting software as a service (SaaS) by means of Cloud computing with an aim to bring emergency health care sector in an umbrella with physical secured patient records. In framing the emergency healthcare treatment, the crucial thing considered necessary to decide about patients is their previous health conduct records. Thus a ubiquitous access to appropriate records is essential. Palm vein pattern recognition promises a secured patient record access. Likewise our paper reveals an efficient means to view, edit or transfer the DICOM images instantly which was a challenging task for medical practitioners in the past years. We have developed two services for health care. 1. Cloud based Palm vein recognition system 2. Distributed Medical image processing tools for medical practitioners. PMID:22865161

  1. Prediction of plantar soft tissue stiffness based on sex, age, bodyweight, height and body mass index.

    PubMed

    Teoh, Jee Chin; Lee, Taeyong

    2016-02-01

    15% of Diabetes Mellitus (DM) patients suffer high risk of ulceration and 85% of the amputation involving DM population is caused by non-healing ulcers. These findings elucidate the fact that foot ulcer can result in major amputation especially to the DM and elderly population. Therefore, early diagnosis of abnormally stiffened plantar soft tissue is needed to prevent the catastrophic tissue damage. In order to differentiate between normal and pathological tissues, a threshold reference value that defines healthy tissue is required. The objective of this study is to perform a multivariate analysis to estimate the healthy plantar tissue stiffness values based on the individuals physical attributes such as bodyweight (BW), height and body mass index (BMI) as well as their age and sex. 100 healthy subjects were recruited. Indentation was performed on 2nd metatarsal head pad at 3 different dorsiflexion angles of 0°, 20°, 40° and the hallux and heel at 0°. The results showed the important influences of BW, height and BMI in determining the plantar tissue stiffness. On the other hand, age and sex only play minimal roles. The study can be further extended to increase the reliability and accuracy of the proposed predictive model by evaluating several other related parameters such as body fat content, footwear usage, frequency of sports participation, etc. PMID:26474035

  2. Cloud Characteristics by Using Doppler Radar over Kolkata

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Pradhan, D.; Singh, H. A. K.; Gupta, M. M.; De, A. K.; Das, J.; Sarkar, S. K.

    2007-07-01

    In present days radio communication scenario, three issues are considered to be the most important. These are reliability, directivity and regulation of transmitted power. All such issues can be taken care provided the characterization of our tropospheric medium is done with good degree accuracy. The radio wave propagating above 10 GHz is affected severely by rain and cloud. In case of rain, the attenuation of radio wave is the main concerned but for cloud along with attenuation, noise temperature generated by cloud is also another issue. Cloud attenuation and cloud noise temperature can be deduced if cloud morphology in terms of cloud coverage, cloud height, cloud thickness, cloud liquid water content etc. is available. The meteorologists of India have studied cloud morphology as well as cloud dynamics for the weather forecasting purposes. But in this paper, an attempt has been made to deduce results on cloud parameters for radio wave propagation studies by utilizing the observations taken by the sophisticated computer controlled Doppler radar belonging to the India Meteorological Department over Kolkata. The Doppler radar operates in C-band at frequency ˜ 2700-2900 MHz with peak power 500 kW. Several cloud parameters viz. radar reflectivity, cloud thickness, cloud height, cloud vertical integrated liquid water content etc. have been studied in probability distribution scale. Based on cloud height, the temperature of the cloud has been determined. It is seen that over Kolkata, the cloud height ˜ 6.5 km occur for maximum percentage of time. The cloud temp has been estimated by using the lapse rate of the temperature with height, which is ˜ 6.5°c km. By using the cloud height, cloud temperature and cloud liquid water content, the attenuation of radio wave due to cloud at microwave and millimeter wave frequency bands, over Kolkata have been derived. It is seen that attenuation value varies from 0.2 dB / km to 30 dB / km over the frequency range from 10 GHz to 100 GHz. The noise temperature generated by cloud has been estimated and found to be from 8°K to 202°K at the frequency range from 10 GHz to 70 GHz with cloud thickness ˜ 1 km and at cloud temperature ˜ 260 °K. Such noise affects the signal to noise (S/N) ratio of the communication system.

  3. Comparisons of Aerosol-Cloud Observations Between a Ground-based Raman-Mie Lidar and CALIPSO

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Chaw, S.; Gross, B.; Charles, L.; Vladutescu, V.; Cao, N.; Moshary, F.; Ahmed, S.

    2007-12-01

    Global vertical profiles of aerosol and cloud are currently being observed by satellite CALIPSO. Based on the inherent properties of elastic-scattering lidar, the lidar ratio (extinction-to-backscatter ratio) becomes very important to quantitatively retrieve the distribution of aerosol/cloud extinction or backscatter coefficient. In this presentation, we examine the feasibility of using MODIS-retrieved aerosol optical depth over ocean to constrain the aerosol lidar ratio in the CALIPSO retrieval of aerosol extinction profile with Fernald algorithm, and then compare these lidar-ratios to those derived from both column measurements by the CIMEL Sunphotometer and a combination of the ground-based lidar and radiometer. We explore the variability of lidar ratios for the different types of aerosol over the US east coast. In addition, we present our validation measurements for aerosol vertical profiles. So far, 13 near simultaneous observations by our ground-based multi-wavelength Raman-Mie lidar which operated in New York City (40.821N, 73.949W), have been obtained together with other supporting measurements. In particular, comparisons of aerosol extinction profiles are performed between the ground- based lidar and CALIPSO observations and the vertical distribution of smoke plumes, aloft aerosol layer, urban aerosol and PBL height are presented and compared. Retrievals of optically thin clouds heights and optical depth in the low- and high-altitude from CALIPSO and MODIS/Aqua, respectively, are examined with respect to ground- based lidar measurements and several biases in the measurements are presented.

  4. Streaming support for data intensive cloud-based sequence analysis.

    PubMed

    Issa, Shadi A; Kienzler, Romeo; El-Kalioby, Mohamed; Tonellato, Peter J; Wall, Dennis; Bruggmann, Rémy; Abouelhoda, Mohamed

    2013-01-01

    Cloud computing provides a promising solution to the genomics data deluge problem resulting from the advent of next-generation sequencing (NGS) technology. Based on the concepts of "resources-on-demand" and "pay-as-you-go", scientists with no or limited infrastructure can have access to scalable and cost-effective computational resources. However, the large size of NGS data causes a significant data transfer latency from the client's site to the cloud, which presents a bottleneck for using cloud computing services. In this paper, we provide a streaming-based scheme to overcome this problem, where the NGS data is processed while being transferred to the cloud. Our scheme targets the wide class of NGS data analysis tasks, where the NGS sequences can be processed independently from one another. We also provide the elastream package that supports the use of this scheme with individual analysis programs or with workflow systems. Experiments presented in this paper show that our solution mitigates the effect of data transfer latency and saves both time and cost of computation. PMID:23710461

  5. Streaming Support for Data Intensive Cloud-Based Sequence Analysis

    PubMed Central

    Issa, Shadi A.; Kienzler, Romeo; El-Kalioby, Mohamed; Tonellato, Peter J.; Wall, Dennis; Bruggmann, Rémy; Abouelhoda, Mohamed

    2013-01-01

    Cloud computing provides a promising solution to the genomics data deluge problem resulting from the advent of next-generation sequencing (NGS) technology. Based on the concepts of “resources-on-demand” and “pay-as-you-go”, scientists with no or limited infrastructure can have access to scalable and cost-effective computational resources. However, the large size of NGS data causes a significant data transfer latency from the client's site to the cloud, which presents a bottleneck for using cloud computing services. In this paper, we provide a streaming-based scheme to overcome this problem, where the NGS data is processed while being transferred to the cloud. Our scheme targets the wide class of NGS data analysis tasks, where the NGS sequences can be processed independently from one another. We also provide the elastream package that supports the use of this scheme with individual analysis programs or with workflow systems. Experiments presented in this paper show that our solution mitigates the effect of data transfer latency and saves both time and cost of computation. PMID:23710461

  6. A cloud-based multimodality case file for mobile devices.

    PubMed

    Balkman, Jason D; Loehfelm, Thomas W

    2014-01-01

    Recent improvements in Web and mobile technology, along with the widespread use of handheld devices in radiology education, provide unique opportunities for creating scalable, universally accessible, portable image-rich radiology case files. A cloud database and a Web-based application for radiologic images were developed to create a mobile case file with reasonable usability, download performance, and image quality for teaching purposes. A total of 75 radiology cases related to breast, thoracic, gastrointestinal, musculoskeletal, and neuroimaging subspecialties were included in the database. Breast imaging cases are the focus of this article, as they best demonstrate handheld display capabilities across a wide variety of modalities. This case subset also illustrates methods for adapting radiologic content to cloud platforms and mobile devices. Readers will gain practical knowledge about storage and retrieval of cloud-based imaging data, an awareness of techniques used to adapt scrollable and high-resolution imaging content for the Web, and an appreciation for optimizing images for handheld devices. The evaluation of this software demonstrates the feasibility of adapting images from most imaging modalities to mobile devices, even in cases of full-field digital mammograms, where high resolution is required to represent subtle pathologic features. The cloud platform allows cases to be added and modified in real time by using only a standard Web browser with no application-specific software. Challenges remain in developing efficient ways to generate, modify, and upload radiologic and supplementary teaching content to this cloud-based platform. Online supplemental material is available for this article. PMID:24819664

  7. The Impacts of an Observationally-Based Cloud Fraction and Condensate Overlap Parameterization on a GCM's Cloud Radiative Effect

    NASA Technical Reports Server (NTRS)

    Oreopoulos, Lazaros; Lee, Dongmin; Norris, Peter; Yuan, Tianle

    2011-01-01

    It has been shown that the details of how cloud fraction overlap is treated in GCMs has substantial impact on shortwave and longwave fluxes. Because cloud condensate is also horizontally heterogeneous at GCM grid scales, another aspect of cloud overlap should in principle also be assessed, namely the vertical overlap of hydrometeor distributions. This type of overlap is usually examined in terms of rank correlations, i.e., linear correlations between hydrometeor amount ranks of the overlapping parts of cloud layers at specific separation distances. The cloud fraction overlap parameter and the rank correlation of hydrometeor amounts can be both expressed as inverse exponential functions of separation distance characterized by their respective decorrelation lengths (e-folding distances). Larger decorrelation lengths mean that hydrometeor fractions and probability distribution functions have high levels of vertical alignment. An analysis of CloudSat and CALIPSO data reveals that the two aspects of cloud overlap are related and their respective decorrelation lengths have a distinct dependence on latitude that can be parameterized and included in a GCM. In our presentation we will contrast the Cloud Radiative Effect (CRE) of the GEOS-5 atmospheric GCM (AGCM) when the observationally-based parameterization of decorrelation lengths is used to represent overlap versus the simpler cases of maximum-random overlap and globally constant decorrelation lengths. The effects of specific overlap representations will be examined for both diagnostic and interactive radiation runs in GEOS-5 and comparisons will be made with observed CREs from CERES and CloudSat (2B-FLXHR product). Since the radiative effects of overlap depend on the cloud property distributions of the AGCM, the availability of two different cloud schemes in GEOS-5 will give us the opportunity to assess a wide range of potential cloud overlap consequences on the model's climate.

  8. 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

  9. 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

  10. TRIDEC Cloud - a Web-based Platform for Tsunami Early Warning tested with NEAMWave14 Scenarios

    NASA Astrophysics Data System (ADS)

    Hammitzsch, Martin; Spazier, Johannes; Reißland, Sven; Necmioglu, Ocal; Comoglu, Mustafa; Ozer Sozdinler, Ceren; Carrilho, Fernando; Wächter, Joachim

    2015-04-01

    In times of cloud computing and ubiquitous computing the use of concepts and paradigms introduced by information and communications technology (ICT) have to be considered even for early warning systems (EWS). Based on the experiences and the knowledge gained in research projects new technologies are exploited to implement a cloud-based and web-based platform - the TRIDEC Cloud - to open up new prospects for EWS. The platform in its current version addresses tsunami early warning and mitigation. It merges several complementary external and in-house cloud-based services for instant tsunami propagation calculations and automated background computation with graphics processing units (GPU), for web-mapping of hazard specific geospatial data, and for serving relevant functionality to handle, share, and communicate threat specific information in a collaborative and distributed environment. The TRIDEC Cloud can be accessed in two different modes, the monitoring mode and the exercise-and-training mode. The monitoring mode provides important functionality required to act in a real event. So far, the monitoring mode integrates historic and real-time sea level data and latest earthquake information. The integration of sources is supported by a simple and secure interface. The exercise and training mode enables training and exercises with virtual scenarios. This mode disconnects real world systems and connects with a virtual environment that receives virtual earthquake information and virtual sea level data re-played by a scenario player. Thus operators and other stakeholders are able to train skills and prepare for real events and large exercises. The GFZ German Research Centre for Geosciences (GFZ), the Kandilli Observatory and Earthquake Research Institute (KOERI), and the Portuguese Institute for the Sea and Atmosphere (IPMA) have used the opportunity provided by NEAMWave14 to test the TRIDEC Cloud as a collaborative activity based on previous partnership and commitments at the European scale. The TRIDEC Cloud has not been involved officially in Part B of the NEAMWave14 scenarios. However, the scenarios have been used by GFZ, KOERI, and IPMA for testing in exercise runs on October 27-28, 2014. Additionally, the Greek NEAMWave14 scenario has been tested in an exercise run by GFZ only on October 29, 2014 (see ICG/NEAMTWS-XI/13). The exercise runs demonstrated that operators in warning centres and stakeholders of other involved parties just need a standard web browser to access a full-fledged TEWS. The integration of GPU accelerated tsunami simulation computations have been an integral part to foster early warning with on-demand tsunami predictions based on actual source parameters. Thus tsunami travel times, estimated times of arrival and estimated wave heights are available immediately for visualization and for further analysis and processing. The generation of warning messages is based on internationally agreed message structures and includes static and dynamic information based on earthquake information, instant computations of tsunami simulations, and actual measurements. Generated messages are served for review, modification, and addressing in one simple form for dissemination via Cloud Messages, Shared Maps, e-mail, FTP/GTS, SMS, and FAX. Cloud Messages and Shared Maps are complementary channels and integrate interactive event and simulation data. Thus recipients are enabled to interact dynamically with a map and diagrams beyond traditional text information.

  11. Octree-based region growing for point cloud segmentation

    NASA Astrophysics Data System (ADS)

    Vo, Anh-Vu; Truong-Hong, Linh; Laefer, Debra F.; Bertolotto, Michela

    2015-06-01

    This paper introduces a novel, region-growing algorithm for the fast surface patch segmentation of three-dimensional point clouds of urban environments. The proposed algorithm is composed of two stages based on a coarse-to-fine concept. First, a region-growing step is performed on an octree-based voxelized representation of the input point cloud to extract major (coarse) segments. The output is then passed through a refinement process. As part of this, there are two competing factors related to voxel size selection. To balance the constraints, an adaptive octree is created in two stages. Empirical studies on real terrestrial and airborne laser scanning data for complex buildings and an urban setting show the proposed approach to be at least an order of magnitude faster when compared to a conventional region growing method and able to incorporate semantic-based feature criteria, while achieving precision, recall, and fitness scores of at least 75% and as much as 95%.

  12. [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

  13. Smart Learning Services Based on Smart Cloud Computing

    PubMed Central

    Kim, Svetlana; Song, Su-Mi; Yoon, Yong-Ik

    2011-01-01

    Context-aware technologies can make e-learning services smarter and more efficient since context-aware services are based on the user’s behavior. To add those technologies into existing e-learning services, a service architecture model is needed to transform the existing e-learning environment, which is situation-aware, into the environment that understands context as well. The context-awareness in e-learning may include the awareness of user profile and terminal context. In this paper, we propose a new notion of service that provides context-awareness to smart learning content in a cloud computing environment. We suggest the elastic four smarts (E4S)—smart pull, smart prospect, smart content, and smart push—concept to the cloud services so smart learning services are possible. The E4S focuses on meeting the users’ needs by collecting and analyzing users’ behavior, prospecting future services, building corresponding contents, and delivering the contents through cloud computing environment. Users’ behavior can be collected through mobile devices such as smart phones that have built-in sensors. As results, the proposed smart e-learning model in cloud computing environment provides personalized and customized learning services to its users. PMID:22164048

  14. Risk of Esophageal Adenocarcinoma Decreases With Height, Based on Consortium Analysis and Confirmed by Mendelian Randomization

    PubMed Central

    Thrift, Aaron P.; Risch, Harvey A.; Onstad, Lynn; Shaheen, Nicholas J.; Casson, Alan G.; Bernstein, Leslie; Corley, Douglas A.; Levine, David M.; Chow, Wong–Ho; Reid, Brian J.; Romero, Yvonne; Hardie, Laura J.; Liu, Geoffrey; Wu, Anna H.; Bird, Nigel C.; Gammon, Marilie D.; Ye, Weimin; Whiteman, David C.; Vaughan, Thomas L.

    2014-01-01

    BACKGROUND & AIMS Risks for some cancers increase with height. We investigated the relationship between height and risk of esophageal adenocarcinoma (EAC) and its precursor, Barrett’s esophagus (BE). METHODS We analyzed epidemiologic and genome-wide genomic data from individuals of European ancestry in the Barrett’s and Esophageal Adenocarcinoma Consortium, from 999 cases of EAC, 2061 cases of BE, and 2168 population controls. Multivariable logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for associations between height and risks of EAC and BE. We performed a Mendelian randomization analysis to estimate an unconfounded effect of height on EAC and BE using a genetic risk score derived from 243 genetic variants associated with height as an instrumental variable. RESULTS Height was associated inversely with EAC (per 10-cm increase in height: OR, 0.70; 95% CI, 0.62–0.79 for men and OR, 0.57; 95% CI 0.40–0.80 for women) and BE (per 10-cm increase in height: OR, 0.69; 95% CI, 0.62–0.77 for men and OR, 0.61; 95% CI, 0.48–0.77 for women). The risk estimates were consistent across strata of age, education level, smoking, gastroesophageal reflux symptoms, body mass index, and weight. Mendelian randomization analysis yielded results quantitatively similar to those from the conventional epidemiologic analysis. CONCLUSIONS Height is associated inversely with risks of EAC and BE. Results from the Mendelian randomization study showed that the inverse association observed did not result from confounding factors. Mechanistic studies of the effect of height on EAC and BE are warranted; height could have utility in clinical risk stratification. PMID:24530603

  15. Designing the Cloud-based DOE Systems Biology Knowledgebase

    SciTech Connect

    Lansing, Carina S.; Liu, Yan; Yin, Jian; Corrigan, Abigail L.; Guillen, Zoe C.; Kleese van Dam, Kerstin; Gorton, Ian

    2011-09-01

    Systems Biology research, even more than many other scientific domains, is becoming increasingly data-intensive. Not only have advances in experimental and computational technologies lead to an exponential increase in scientific data volumes and their complexity, but increasingly such databases themselves are providing the basis for new scientific discoveries. To engage effectively with these community resources, integrated analyses, synthesis and simulation software is needed, regularly supported by scientific workflows. In order to provide a more collaborative, community driven research environment for this heterogeneous setting, the Department of Energy (DOE) has decided to develop a federated, cloud based cyber infrastructure - the Systems Biology Knowledgebase (Kbase). Pacific Northwest National Laboratory (PNNL) with its long tradition in data intensive science lead two of the five initial pilot projects, these two focusing on defining and testing the basic federated cloud-based system architecture and develop a prototype implementation. Hereby the community wide accessibility of biological data and the capability to integrate and analyze this data within its changing research context were seen as key technical functionalities the Kbase needed to enable. In this paper we describe the results of our investigations into the design of a cloud based federated infrastructure for: (1) Semantics driven data discovery, access and integration; (2) Data annotation, publication and sharing; (3) Workflow enabled data analysis; and (4) Project based collaborative working. We describe our approach, exemplary use cases and our prototype implementation that demonstrates the feasibility of this approach.

  16. Efficient Resources Provisioning Based on Load Forecasting in Cloud

    PubMed Central

    Hu, Rongdong; Jiang, Jingfei; Liu, Guangming; Wang, Lixin

    2014-01-01

    Cloud providers should ensure QoS while maximizing resources utilization. One optimal strategy is to timely allocate resources in a fine-grained mode according to application's actual resources demand. The necessary precondition of this strategy is obtaining future load information in advance. We propose a multi-step-ahead load forecasting method, KSwSVR, based on statistical learning theory which is suitable for the complex and dynamic characteristics of the cloud computing environment. It integrates an improved support vector regression algorithm and Kalman smoother. Public trace data taken from multitypes of resources were used to verify its prediction accuracy, stability, and adaptability, comparing with AR, BPNN, and standard SVR. Subsequently, based on the predicted results, a simple and efficient strategy is proposed for resource provisioning. CPU allocation experiment indicated it can effectively reduce resources consumption while meeting service level agreements requirements. PMID:24701160

  17. Association between Short Maternal Height and Low Birth Weight: a Hospital-based Study in Japan

    PubMed Central

    2016-01-01

    Anthropometry measurements, such as height and weight, have recently been used to predict poorer birth outcomes. However, the relationship between maternal height and birth outcomes remains unclear. We examined the effect of shorter maternal height on low birth weight (LBW) among 17,150 pairs of Japanese mothers and newborns. Data for this analysis were collected from newborns who were delivered at a large hospital in Japan. Maternal height was the exposure variable, and LBW and admission to the neonatal intensive care unit were the outcome variables. Logistic regression models were used to estimate the associations. The shortest maternal height quartile (131.0–151.9 cm) was related to LBW (OR 1.91 [95% CI 1.64, 2.22]). The groups with the second (152.0–157.9 cm) and the third shortest maternal height quartiles (158.0–160.9 cm) were also related to LBW. A P trend with one quartile change also showed a significant relationship. The relationship between maternal height and NICU admission disappeared when the statistical model was adjusted for LBW. A newborn’s small size was one factor in the relationship between shorter maternal height and NICU admission. In developed countries, shorter mothers provide a useful prenatal target to anticipate and plan for LBW newborns and NICU admission. PMID:26955234

  18. Association between Short Maternal Height and Low Birth Weight: a Hospital-based Study in Japan.

    PubMed

    Inoue, Sachiko; Naruse, Hiroo; Yorifuji, Takashi; Kato, Tsuguhiko; Murakoshi, Takeshi; Doi, Hiroyuki; Subramanian, S V

    2016-03-01

    Anthropometry measurements, such as height and weight, have recently been used to predict poorer birth outcomes. However, the relationship between maternal height and birth outcomes remains unclear. We examined the effect of shorter maternal height on low birth weight (LBW) among 17,150 pairs of Japanese mothers and newborns. Data for this analysis were collected from newborns who were delivered at a large hospital in Japan. Maternal height was the exposure variable, and LBW and admission to the neonatal intensive care unit were the outcome variables. Logistic regression models were used to estimate the associations. The shortest maternal height quartile (131.0-151.9 cm) was related to LBW (OR 1.91 [95% CI 1.64, 2.22]). The groups with the second (152.0-157.9 cm) and the third shortest maternal height quartiles (158.0-160.9 cm) were also related to LBW. A P trend with one quartile change also showed a significant relationship. The relationship between maternal height and NICU admission disappeared when the statistical model was adjusted for LBW. A newborn's small size was one factor in the relationship between shorter maternal height and NICU admission. In developed countries, shorter mothers provide a useful prenatal target to anticipate and plan for LBW newborns and NICU admission. PMID:26955234

  19. Cloud Based Metalearning System for Predictive Modeling of Biomedical Data

    PubMed Central

    Vukićević, Milan

    2014-01-01

    Rapid growth and storage of biomedical data enabled many opportunities for predictive modeling and improvement of healthcare processes. On the other side analysis of such large amounts of data is a difficult and computationally intensive task for most existing data mining algorithms. This problem is addressed by proposing a cloud based system that integrates metalearning framework for ranking and selection of best predictive algorithms for data at hand and open source big data technologies for analysis of biomedical data. PMID:24892101

  20. Influence of Subpixel Scale Cloud Top Structure on Reflectances from Overcast Stratiform Cloud Layers

    NASA Technical Reports Server (NTRS)

    Loeb, N. G.; Varnai, Tamas; Winker, David M.

    1998-01-01

    Recent observational studies have shown that satellite retrievals of cloud optical depth based on plane-parallel model theory suffer from systematic biases that depend on viewing geometry, even when observations are restricted to overcast marine stratus layers, arguably the closest to plane parallel in nature. At moderate to low sun elevations, the plane-parallel model significantly overestimates the reflectance dependence on view angle in the forward-scattering direction but shows a similar dependence in the backscattering direction. Theoretical simulations are performed that show that the likely cause for this discrepancy is because the plane-parallel model assumption does not account for subpixel, scale variations in cloud-top height (i.e., "cloud bumps"). Monte Carlo simulation, comparing ID model radiances to radiances from overcast cloud field with 1) cloud-top height variation, but constant cloud volume extinction; 2) flat tops but horizontal variations in cloud volume extinction; and 3) variations in both cloud top height and cloud extinction are performed over a approximately equal to 4 km x 4 km domain (roughly the size of an individual GAC AVHRR pixel). The comparisons show that when cloud-top height variations are included, departures from 1D theory are remarkably similar (qualitatively) to those obtained observationally. In contrast, when clouds are assumed flat and only cloud extinction is variable, reflectance differences are much smaller and do not show any view-angle dependence. When both cloud-top height and cloud extinction variations are included, however, large increases in cloud extinction variability can enhance reflectance difference. The reason 3D-1D reflectance differences are more sensitive to cloud-top height variations in the forward-scattering direction (at moderate to low, sun elevations) is because photons leaving the cloud field in that direction experience fewer scattering events (low-order scattering) and are restricted to the topmost portions of the cloud. While reflectance deviations from 1D theory are much larger for bumpy clouds than for flat clouds with variable cloud extinction, differences in cloud albedo are comparable for these two cases.

  1. Assimilating Aircraft-based measurements to improve the State of Distal Volcanic Ash Cloud

    NASA Astrophysics Data System (ADS)

    Fu, Guangliang; Lin, Hai Xiang; Heemink, Arnold; Segers, Arjo; Lu, Sha; Palsson, Thorgeir

    2015-04-01

    The sudden eruption at the 1666 m high, ice-capped Eyjafjallajökull volcano, in south Iceland during 14 April to 23 May 2010, had caused an unprecedented closure of the European and North Atlantic airspace resulting in global economic losses of US5 billion. This has initiated a lot of research on how to improve aviation advice after eruption onset. Good estimation of both the state of volcanic ash cloud and the emission of volcano are crucial for providing a successful aviation advice. Currently most of the approaches, employing satellite-based and ground-based measurements, are in the focus of improving the definition of Eruption Source Parameters (ESPs) such as plume height and mass eruption rate, which are certainly very important for estimating volcano emission and state of volcanic ash cloud near to the volcano. However, for ash cloud state in a far field, these approaches can hardly make improvements. This is mainly because the influence of ESPs on the ash plume becomes weaker as the distance to the volcano is getting farther, thus for a distal plume the information of ESPs will have little influence. This study aims to find an efficient way to improve the state of distal volcanic ash cloud. We use real-life aircraft-based observations, measured along Dutch border between Borken and Twist during the 2010 Eyjafjallajökull eruption, in an data assimilation system combining with a transport model to identify the potential benefit of this kind of observations and the influence on the ash state around Dutch border. We show that assimilating aircraft-based measurements can significantly improve the state of distal ash clouds, and further provide an improved aviation advice on distal ash plume. We compare the performances of different sequential data assimilation methods. The results show standard Ensemble Kalman Filter (EnKF) works better than others, which is because of the strong nonlinearity of the dynamics and the EnKF's resampling Gaussianity nature. Furthermore, another important aspect of data assimilation methodology related to time-correlated errors is also investigated. The result shows for assimilating aircraft-based timely measurements in a far field, time-correlation of model errors on the state is critical to the performance of the assimilation system.

  2. A global survey of aerosol-liquid water cloud overlap based on four years of CALIPSO-CALIOP data

    NASA Astrophysics Data System (ADS)

    Devasthale, A.; Thomas, M. A.

    2010-09-01

    The presence of aerosols over highly reflective liquid water cloud tops poses a big challenge in simulating their radiative impacts. Particularly, absorbing aerosols, such as smoke, may have significant impact in such situations and even change the sign of net radiative forcing. Until now, it was not possible to obtain information on such overlap events realistically from the existing passive satellite sensors. However, the CALIOP instrument onboard NASA's CALIPSO satellite allows us to examine these events with an unprecedented accuracy. Using four years of collocated CALIPSO 5 km Aerosol and Cloud Layer Version 3 Products (June 2006-May 2010), we quantify, for the first time, the macrophysical characteristics of overlapping aerosol and water cloud layers globally. We investigate seasonal variability in these characteristics over six latitude bands to understand the hemispheric differences. We compute a) the percentage cases when such overlap is seen globally and seasonally when all aerosol types are included (AAO case) in the analysis, b) the joint histograms of aerosol layer base height and cloud layer top height, and c) the joint histograms of aerosol and cloud geometrical thicknesses in such overlap cases. We also investigate frequency of smoke aerosol-cloud overlap (SAO case). The results show a distinct seasonality in overlap frequency in both AAO and SAO cases. Globally, the frequency is highest during JJA months in AAO case, while for the SAO case, it is highest in SON months. The seasonal mean overlap frequency can regionally exceed 20% in AAO case and 10% in SAO case. There is a tendency that the vertical separation between aerosol and cloud layers increases from high to low latitude regions in the both hemispheres. In about 5-10% cases the vertical distance between aerosol and cloud layers is less than 100 m, while about in 45-60% cases it less than a kilometer in the annual means for different latitudinal bands. The frequency of occurrence of thicker aerosol layers gradually increases from poles to tropics. In about 70-80% cases, aerosol layers are less than a kilometer thick, while in about 18-22% cases they are 1-2 km thick. The frequency of aerosol layers 2-3 km thick is about 4-5% in the tropical belts during overlap events. The results further highlight spatial and temporal variations in aerosol-liquid water cloud overlap and suggest that the frequency of occurrence of such overlap events is far from being negligible globally.

  3. Chemical and physical influences on aerosol activation in liquid clouds: a study based on observations from the Jungfraujoch, Switzerland

    NASA Astrophysics Data System (ADS)

    Hoyle, Christopher R.; Webster, Clare S.; Rieder, Harald E.; Nenes, Athanasios; Hammer, Emanuel; Herrmann, Erik; Gysel, Martin; Bukowiecki, Nicolas; Weingartner, Ernest; Steinbacher, Martin; Baltensperger, Urs

    2016-03-01

    A simple statistical model to predict the number of aerosols which activate to form cloud droplets in warm clouds has been established, based on regression analysis of data from four summertime Cloud and Aerosol Characterisation Experiments (CLACE) at the high-altitude site Jungfraujoch (JFJ). It is shown that 79 % of the observed variance in droplet numbers can be represented by a model accounting only for the number of potential cloud condensation nuclei (defined as number of particles larger than 80 nm in diameter), while the mean errors in the model representation may be reduced by the addition of further explanatory variables, such as the mixing ratios of O3, CO, and the height of the measurements above cloud base. The statistical model has a similar ability to represent the observed droplet numbers in each of the individual years, as well as for the two predominant local wind directions at the JFJ (northwest and southeast). Given the central European location of the JFJ, with air masses in summer being representative of the free troposphere with regular boundary layer in-mixing via convection, we expect that this statistical model is generally applicable to warm clouds under conditions where droplet formation is aerosol limited (i.e. at relatively high updraught velocities and/or relatively low aerosol number concentrations). A comparison between the statistical model and an established microphysical parametrization shows good agreement between the two and supports the conclusion that cloud droplet formation at the JFJ is predominantly controlled by the number concentration of aerosol particles.

  4. Space Science Cloud: a Virtual Space Science Research Platform Based on Cloud Model

    NASA Astrophysics Data System (ADS)

    Hu, Xiaoyan; Tong, Jizhou; Zou, Ziming

    Through independent and co-operational science missions, Strategic Pioneer Program (SPP) on Space Science, the new initiative of space science program in China which was approved by CAS and implemented by National Space Science Center (NSSC), dedicates to seek new discoveries and new breakthroughs in space science, thus deepen the understanding of universe and planet earth. In the framework of this program, in order to support the operations of space science missions and satisfy the demand of related research activities for e-Science, NSSC is developing a virtual space science research platform based on cloud model, namely the Space Science Cloud (SSC). In order to support mission demonstration, SSC integrates interactive satellite orbit design tool, satellite structure and payloads layout design tool, payload observation coverage analysis tool, etc., to help scientists analyze and verify space science mission designs. Another important function of SSC is supporting the mission operations, which runs through the space satellite data pipelines. Mission operators can acquire and process observation data, then distribute the data products to other systems or issue the data and archives with the services of SSC. In addition, SSC provides useful data, tools and models for space researchers. Several databases in the field of space science are integrated and an efficient retrieve system is developing. Common tools for data visualization, deep processing (e.g., smoothing and filtering tools), analysis (e.g., FFT analysis tool and minimum variance analysis tool) and mining (e.g., proton event correlation analysis tool) are also integrated to help the researchers to better utilize the data. The space weather models on SSC include magnetic storm forecast model, multi-station middle and upper atmospheric climate model, solar energetic particle propagation model and so on. All the services above-mentioned are based on the e-Science infrastructures of CAS e.g. cloud storage and cloud computing. SSC provides its users with self-service storage and computing resources at the same time.At present, the prototyping of SSC is underway and the platform is expected to be put into trial operation in August 2014. We hope that as SSC develops, our vision of Digital Space may come true someday.

  5. Cloud cover estimation: Use of GOES imagery in development of cloud cover data base for insolation assessment

    NASA Technical Reports Server (NTRS)

    Huning, J. R.; Logan, T. L.; Smith, J. H.

    1982-01-01

    The potential of using digital satellite data to establish a cloud cover data base for the United States, one that would provide detailed information on the temporal and spatial variability of cloud development are studied. Key elements include: (1) interfacing GOES data from the University of Wisconsin Meteorological Data Facility with the Jet Propulsion Laboratory's VICAR image processing system and IBIS geographic information system; (2) creation of a registered multitemporal GOES data base; (3) development of a simple normalization model to compensate for sun angle; (4) creation of a variable size georeference grid that provides detailed cloud information in selected areas and summarized information in other areas; and (5) development of a cloud/shadow model which details the percentage of each grid cell that is cloud and shadow covered, and the percentage of cloud or shadow opacity. In addition, comparison of model calculations of insolation with measured values at selected test sites was accomplished, as well as development of preliminary requirements for a large scale data base of cloud cover statistics.

  6. Evaluating the Usage of Cloud-Based Collaboration Services through Teamwork

    ERIC Educational Resources Information Center

    Qin, Li; Hsu, Jeffrey; Stern, Mel

    2016-01-01

    With the proliferation of cloud computing for both organizational and educational use, cloud-based collaboration services are transforming how people work in teams. The authors investigated the determinants of the usage of cloud-based collaboration services including teamwork quality, computer self-efficacy, and prior experience, as well as its…

  7. Learning-based computing techniques in geoid modeling for precise height transformation

    NASA Astrophysics Data System (ADS)

    Erol, B.; Erol, S.

    2013-03-01

    Precise determination of local geoid is of particular importance for establishing height control in geodetic GNSS applications, since the classical leveling technique is too laborious. A geoid model can be accurately obtained employing properly distributed benchmarks having GNSS and leveling observations using an appropriate computing algorithm. Besides the classical multivariable polynomial regression equations (MPRE), this study attempts an evaluation of learning based computing algorithms: artificial neural networks (ANNs), adaptive network-based fuzzy inference system (ANFIS) and especially the wavelet neural networks (WNNs) approach in geoid surface approximation. These algorithms were developed parallel to advances in computer technologies and recently have been used for solving complex nonlinear problems of many applications. However, they are rather new in dealing with precise modeling problem of the Earth gravity field. In the scope of the study, these methods were applied to Istanbul GPS Triangulation Network data. The performances of the methods were assessed considering the validation results of the geoid models at the observation points. In conclusion the ANFIS and WNN revealed higher prediction accuracies compared to ANN and MPRE methods. Beside the prediction capabilities, these methods were also compared and discussed from the practical point of view in conclusions.

  8. Statistic analysis of the ionospheric topside scale height based on COSMIC RO measurements

    NASA Astrophysics Data System (ADS)

    Xu, T. L.; Jin, H. L.; Xu, X.; Guo, P.; Wang, Y. B.; Ping, J. S.

    2013-11-01

    The ionospheric topside basis scale height, Hsc, presents the height range above the F2 layer peak height at which the peak electron density (NmF2) decays by a factor of an exponent (~2.718). The data periods of Hsc derived from the COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) RO (Radio Occultation) are from 1st January 2007 to 31st December 2011. Time series of Hsc during these five years in specified regions are analyzed. The most significant finding in this study is that the Hsc variations in a relatively small region demonstrate annual periodicities but do not last the whole day. The variation fluctuation is related to the geomagnetic latitudes and presents a good symmetry in two geomagnetic hemispheres. A novel phenomenon is that scale height and peak height also reveal the geomagnetic equator ionosphere anomaly as well as peak density. The peak density anomaly presents two crests along the geomagnetic equator while the scale height and peak height exhibit single-line distribution. Diurnal variation of Hsc is also investigated in this study. There is a deep valley at 08:00 LT and the peak is at around 12:00 LT. The high values last the whole afternoon.

  9. Observations of the Interaction and/or Transport of Aerosols with Cloud or Fog during DRAGON Campaigns from AERONET Ground-Based Remote Sensing

    NASA Astrophysics Data System (ADS)

    Eck, Thomas; Holben, Brent; Schafer, Joel; Giles, David; Kim, Jhoon; Kim, Young; Sano, Itaru; Reid, Jeffrey; Pickering, Kenneth; Crawford, James; Sinyuk, Alexander; Trevino, Nathan

    2014-05-01

    Ground-based remote sensing observations from Aerosol Robotic Network (AERONET) sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties and/or in difficulty identifying some major pollution transport events due to aerosols being imbedded in cloud systems. AERONET has established Distributed Regional Aerosol Gridded Observation Networks (DRAGON) during field campaigns that are short-term (~2-3 months) relatively dense spatial networks of ~15 to 45 sun and sky scanning photometers. Recent major DRAGON field campaigns in Japan and South Korea (Spring 2012) and California (Winter 2013) have yielded observations of aerosol transport associated with clouds and/or aerosol properties modification as a result of fog interaction. Analysis of data from the Korean and Japan DRAGON campaigns shows that major fine-mode aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations often filter out significant pollution aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm was utilized to isolate and analyze the fine-mode aerosol optical depth signal for these cases of persistent and extensive cloud cover. Additionally, extensive fog that was coincident with aerosol layer height on some days in both Korea and California resulted in large increases in fine mode aerosol radius, with a mode of cloud-processed or residual aerosol of radius ~0.4-0.5 micron sometimes observed. Cloud processed aerosol may occur much more frequently than AERONET data suggest due to inherent difficulty in observing aerosol properties near clouds from remote sensing observations. These biases of aerosols associated with clouds would likely be even greater for satellite remote sensing retrievals of aerosol properties near clouds due to 3-D effects and sub-pixel cloud contamination issues.

  10. Cloud-Based Model Calibration Using OpenStudio: Preprint

    SciTech Connect

    Hale, E.; Lisell, L.; Goldwasser, D.; Macumber, D.; Dean, J.; Metzger, I.; Parker, A.; Long, N.; Ball, B.; Schott, M.; Weaver, E.; Brackney, L.

    2014-03-01

    OpenStudio is a free, open source Software Development Kit (SDK) and application suite for performing building energy modeling and analysis. The OpenStudio Parametric Analysis Tool has been extended to allow cloud-based simulation of multiple OpenStudio models parametrically related to a baseline model. This paper describes the new cloud-based simulation functionality and presents a model cali-bration case study. Calibration is initiated by entering actual monthly utility bill data into the baseline model. Multiple parameters are then varied over multiple iterations to reduce the difference between actual energy consumption and model simulation results, as calculated and visualized by billing period and by fuel type. Simulations are per-formed in parallel using the Amazon Elastic Cloud service. This paper highlights model parameterizations (measures) used for calibration, but the same multi-nodal computing architecture is available for other purposes, for example, recommending combinations of retrofit energy saving measures using the calibrated model as the new baseline.

  11. Web-based CERES Clouds QC Property Viewing Tool

    NASA Astrophysics Data System (ADS)

    Smith, R. A.; Chu, C.; Sun-Mack, S.; Chen, Y.; Heckert, E.; Minnis, P.

    2014-12-01

    This presentation will display the capabilities of a web-based CERES cloud property viewer. Terra data will be chosen for examples. It will demonstrate viewing of cloud properties in gridded global maps, histograms, time series displays, latitudinal zonal images, binned data charts, data frequency graphs, and ISCCP plots. Images can be manipulated by the user to narrow boundaries of the map as well as color bars and value ranges, compare datasets, view data values, and more. Other atmospheric studies groups will be encouraged to put their data into the underlying NetCDF data format and view their data with the tool. A laptop will hopefully be available to allow conference attendees to try navigating the tool.

  12. Measuring the accuracy of self-reported height and weight in a community-based sample of young people

    PubMed Central

    2012-01-01

    Background Self-reported anthropometric data are commonly used to estimate prevalence of obesity in population and community-based studies. We aim to: 1) Determine whether survey participants are able and willing to self-report height and weight; 2) Assess the accuracy of self-reported compared to measured anthropometric data in a community-based sample of young people. Methods Participants (16–29 years) of a behaviour survey, recruited at a Melbourne music festival (January 2011), were asked to self-report height and weight; researchers independently weighed and measured a sub-sample. Body Mass Index was calculated and overweight/obesity classified as ≥25kg/m2. Differences between measured and self-reported values were assessed using paired t-test/Wilcoxon signed ranks test. Accurate report of height and weight were defined as <2cm and <2kg difference between self-report and measured values, respectively. Agreement between classification of overweight/obesity by self-report and measured values was assessed using McNemar’s test. Results Of 1405 survey participants, 82% of males and 72% of females self-reported their height and weight. Among 67 participants who were also independently measured, self-reported height and weight were significantly less than measured height (p=0.01) and weight (p<0.01) among females, but no differences were detected among males. Overall, 52% accurately self-reported height, 30% under-reported, and 18% over-reported; 34% accurately self-reported weight, 52% under-reported and 13% over-reported. More females (70%) than males (35%) under-reported weight (p=0.01). Prevalence of overweight/obesity was 33% based on self-report data and 39% based on measured data (p=0.16). Conclusions Self-reported measurements may underestimate weight but accurately identified overweight/obesity in the majority of this sample of young people. PMID:23170838

  13. Use of active and passive ground based remote sensors to explore cloud droplet modifications in aerosol-cloud interactions

    NASA Astrophysics Data System (ADS)

    Han, Zaw Thet

    We explore the potential aerosol impact on cloud optical properties which is a strong modifier of climate forcing. Previous studies have shown that increased aerosol loading can affect the cloud optical properties such as cloud optical depth and cloud droplet effective radius in rural areas, particularly at the Atmospheric Radiation Measurement, Southern Great Plain site. In this study, we attempt to observe and quantify aerosol-cloud interaction over New York City, using a combination of passive and active radiometric sensors. In particular, we look for signatures of the Twomey indirect effect which states that the droplet size of water phase clouds will decrease with increasing aerosols. We find that under certain conditions, a strong signature is found between the cloud drop effective radius and extinction and this effect is in part due to vertical wind uptake. In demonstrating the Aerosol Cloud Interaction, we use multiple approaches. For example, we derive the integrated liquid water path using both a multiband neural network and dual channel approach and show general agreement between two methods while the DC approach seems more robust. We also find that these measurements are difficult and sensitive to the position of the aerosols relative to the cloud base. As a corollary, we explore whether near surface aerosol loading can effecting the cloud by using particulate matter (PM2.5) and find that the effects are too variable to be given any statistical weight. Finally, we explore the potential of modifying our approach to remove the noisy and difficult measurement of Raman LIDAR derived extinction with calibrated LIDAR backscatter. The results seem to show a general improvement in correlation and offer the possibility of increasing the number of cases observed.

  14. Regime based investigation of the second aerosol indirect effect for liquid water clouds using satellite data

    NASA Astrophysics Data System (ADS)

    Unglaub, Claudia; Quaas, Johannes

    2015-04-01

    Anthropogenic aerosols may affect cloud micro physical processes and subsequently cloud liquid water path via the so-called "second aerosol indirect effects". To obtain a better quantification of such effects the variability of the liquid water path is investigated to study the sensitivity of liquid water clouds to perturbations in the cloud droplet number concentration. For the statistical analysis the A-Train satellite constellation CCCM data product is used. We will analyze the ISCCP cloud class based correlation between the satellite-derived liquid water path and cloud droplet number concentration for liquid water clouds. Furthermore a possible new cloud classification for the high resolution CCCM data set will be presented. The goal of these studies is a better understanding and the assessment of the radiative forcing by the second aerosol indirect effects on liquid water clouds.

  15. Earthquake Scenario-Based Tsunami Wave Heights in the Eastern Mediterranean and Connected Seas

    NASA Astrophysics Data System (ADS)

    Necmioglu, Ocal; Özel, Nurcan Meral

    2015-12-01

    We identified a set of tsunami scenario input parameters in a 0.5° × 0.5° uniformly gridded area in the Eastern Mediterranean, Aegean (both for shallow- and intermediate-depth earthquakes) and Black Seas (only shallow earthquakes) and calculated tsunami scenarios using the SWAN-Joint Research Centre (SWAN-JRC) code ( Mader 2004; Annunziato 2007) with 2-arcmin resolution bathymetry data for the range of 6.5—Mwmax with an Mw increment of 0.1 at each grid in order to realize a comprehensive analysis of tsunami wave heights from earthquakes originating in the region. We defined characteristic earthquake source parameters from a compiled set of sources such as existing moment tensor catalogues and various reference studies, together with the Mwmax assigned in the literature, where possible. Results from 2,415 scenarios show that in the Eastern Mediterranean and its connected seas (Aegean and Black Sea), shallow earthquakes with Mw ≥ 6.5 may result in coastal wave heights of 0.5 m, whereas the same wave height would be expected only from intermediate-depth earthquakes with Mw ≥ 7.0 . The distribution of maximum wave heights calculated indicate that tsunami wave heights up to 1 m could be expected in the northern Aegean, whereas in the Black Sea, Cyprus, Levantine coasts, northern Libya, eastern Sicily, southern Italy, and western Greece, up to 3-m wave height could be possible. Crete, the southern Aegean, and the area between northeast Libya and Alexandria (Egypt) is prone to maximum tsunami wave heights of >3 m. Considering that calculations are performed at a minimum bathymetry depth of 20 m, these wave heights may, according to Green's Law, be amplified by a factor of 2 at the coastline. The study can provide a basis for detailed tsunami hazard studies in the region.

  16. Toward Understanding of Differences in Current Cloud Retrievals of ARM Ground-based Measurements

    SciTech Connect

    Zhao, Chuanfeng; Xie, Shaocheng; Klein, Stephen A.; Protat, Alain; Shupe, Matthew D.; McFarlane, Sally A.; Comstock, Jennifer M.; Delanoe, Julien; Deng, Min; Dunn, Maureen; Hogan, Robin; Huang, Dong; Jensen, Michael; Mace, Gerald G.; McCoy, Renata; O'Conner, Ewan J.; Turner, Dave; Wang, Zhien

    2012-05-30

    Accurate observations of cloud microphysical properties are needed for evaluating and improving the representation of cloud processes in climate models. However, large differences are found in current cloud products retrieved from ground-based remote sensing measurements using various retrieval algorithms. Understanding the differences is an important step to address uncertainties in the cloud retrievals. In this study, an in-depth analysis of nine existing ground-based cloud retrievals using ARM remote sensing measurements is carried out. We place emphasize on boundary layer overcast clouds and high level ice clouds, which are the focus of many current retrieval development efforts due to their radiative importance and relatively simple structure. Large systematic discrepancies in cloud microphysical properties are found in these two types of clouds among the nine cloud retrieval products, particularly for the cloud liquid and ice effective radius. It is shown that most of these large differences have their roots in the retrieval algorithms used by these cloud products, including the retrieval theoretical bases, assumptions, as well as input and constraint parameters. This study suggests the need to further validate current retrieval theories and assumptions and even the development of new retrieval algorithms with more observations under different cloud regimes.

  17. Cloud-based distributed control of unmanned systems

    NASA Astrophysics Data System (ADS)

    Nguyen, Kim B.; Powell, Darren N.; Yetman, Charles; August, Michael; Alderson, Susan L.; Raney, Christopher J.

    2015-05-01

    Enabling warfighters to efficiently and safely execute dangerous missions, unmanned systems have been an increasingly valuable component in modern warfare. The evolving use of unmanned systems leads to vast amounts of data collected from sensors placed on the remote vehicles. As a result, many command and control (C2) systems have been developed to provide the necessary tools to perform one of the following functions: controlling the unmanned vehicle or analyzing and processing the sensory data from unmanned vehicles. These C2 systems are often disparate from one another, limiting the ability to optimally distribute data among different users. The Space and Naval Warfare Systems Center Pacific (SSC Pacific) seeks to address this technology gap through the UxV to the Cloud via Widgets project. The overarching intent of this three year effort is to provide three major capabilities: 1) unmanned vehicle control using an open service oriented architecture; 2) data distribution utilizing cloud technologies; 3) a collection of web-based tools enabling analysts to better view and process data. This paper focuses on how the UxV to the Cloud via Widgets system is designed and implemented by leveraging the following technologies: Data Distribution Service (DDS), Accumulo, Hadoop, and Ozone Widget Framework (OWF).

  18. Current and future advances in optical multiangle remote sensing of aerosols and clouds based on Terra/MISR experience

    NASA Astrophysics Data System (ADS)

    Diner, David J.; Davies, Roger; Kahn, Ralph; Martonchik, John; Gaitley, Barbara; Davis, Ab

    2006-12-01

    Through acquisition of well-calibrated near-nadir and oblique-angle imagery (0° - 70° zenith angles) at moderately high spatial resolution (275 m - 1.1 km), the Multi-angle Imaging SpectroRadiometer (MISR) experiment aboard NASA's Terra satellite has taken atmospheric remote sensing in new directions. Retrieval algorithms that were largely conceptual prior to Terra launch in 1999 have led to publicly available aerosol and cloud products with direct application to global climate and particulate air quality research. Automated algorithms making use of stereoscopic parallax, time lapse among the nine angular views, and the variation in radiance with view angle, scattering angle, and wavelength (446-866 nm) make possible unique data sets including geometric cloud and aerosol plume heights derived independently of emissivity or temperature assumptions; height-resolved cloud-tracked winds; and aerosol optical depth and particle type over a wide variety of surfaces including bright desert source regions. To illustrate these capabilities, examples of regional and global MISR data products, quantitative evaluations of product accuracies based on comparisons with independent data sources, and time series showing seasonal and interannual variations are presented here. Future sensor improvements aimed at building upon MISR heritage, including expanding the spectral coverage to ultraviolet and shortwave infrared wavelengths, adding polarization channels, and widening the sensor swath, are also discussed.

  19. Global aerosol effects on convective clouds

    NASA Astrophysics Data System (ADS)

    Wagner, Till; Stier, Philip

    2013-04-01

    Atmospheric aerosols affect cloud properties, and thereby the radiation balance of the planet and the water cycle. The influence of aerosols on clouds is dominated by increase of cloud droplet and ice crystal numbers (CDNC/ICNC) due to enhanced aerosols acting as cloud condensation and ice nuclei. In deep convective clouds this increase in CDNC/ICNC is hypothesised to increase precipitation because of cloud invigoration through enhanced freezing and associated increased latent heat release caused by delayed warm rain formation. Satellite studies robustly show an increase of cloud top height (CTH) and precipitation with increasing aerosol optical depth (AOD, as proxy for aerosol amount). To represent aerosol effects and study their influence on convective clouds in the global climate aerosol model ECHAM-HAM, we substitute the standard convection parameterisation, which uses one mean convective cloud for each grid column, with the convective cloud field model (CCFM), which simulates a spectrum of convective clouds, each with distinct values of radius, mixing ratios, vertical velocity, height and en/detrainment. Aerosol activation and droplet nucleation in convective updrafts at cloud base is the primary driver for microphysical aerosol effects. To produce realistic estimates for vertical velocity at cloud base we use an entraining dry parcel sub cloud model which is triggered by perturbations of sensible and latent heat at the surface. Aerosol activation at cloud base is modelled with a mechanistic, Köhler theory based, scheme, which couples the aerosols to the convective microphysics. Comparison of relationships between CTH and AOD, and precipitation and AOD produced by this novel model and satellite based estimates show general agreement. Through model experiments and analysis of the model cloud processes we are able to investigate the main drivers for the relationship between CTH / precipitation and AOD.

  20. Testing a polarimetric cloud imager aboard research vessel Polarstern: comparison of color-based and polarimetric cloud detection algorithms.

    PubMed

    Barta, András; Horváth, Gábor; Horváth, Ákos; Egri, Ádám; Blahó, Miklós; Barta, Pál; Bumke, Karl; Macke, Andreas

    2015-02-10

    Cloud cover estimation is an important part of routine meteorological observations. Cloudiness measurements are used in climate model evaluation, nowcasting solar radiation, parameterizing the fluctuations of sea surface insolation, and building energy transfer models of the atmosphere. Currently, the most widespread ground-based method to measure cloudiness is based on analyzing the unpolarized intensity and color distribution of the sky obtained by digital cameras. As a new approach, we propose that cloud detection can be aided by the additional use of skylight polarization measured by 180° field-of-view imaging polarimetry. In the fall of 2010, we tested such a novel polarimetric cloud detector aboard the research vessel Polarstern during expedition ANT-XXVII/1. One of our goals was to test the durability of the measurement hardware under the extreme conditions of a trans-Atlantic cruise. Here, we describe the instrument and compare the results of several different cloud detection algorithms, some conventional and some newly developed. We also discuss the weaknesses of our design and its possible improvements. The comparison with cloud detection algorithms developed for traditional nonpolarimetric full-sky imagers allowed us to evaluate the added value of polarimetric quantities. We found that (1) neural-network-based algorithms perform the best among the investigated schemes and (2) global information (the mean and variance of intensity), nonoptical information (e.g., sun-view geometry), and polarimetric information (e.g., the degree of polarization) improve the accuracy of cloud detection, albeit slightly. PMID:25968023

  1. Cloud Study Investigators: Using NASA's CERES S'COOL in Problem-Based Learning

    ERIC Educational Resources Information Center

    Moore, Susan; Popiolkowski, Gary

    2011-01-01

    1This article describes how, by incorporating NASA's Students' Cloud Observations On-Line (S'COOL) project into a problem-based learning (PBL) activity, middle school students are engaged in authentic scientific research where they observe and record information about clouds and contribute ground truth data to NASA's Clouds and the Earth's…

  2. Cloud Study Investigators: Using NASA's CERES S'COOL in Problem-Based Learning

    ERIC Educational Resources Information Center

    Moore, Susan; Popiolkowski, Gary

    2011-01-01

    1This article describes how, by incorporating NASA's Students' Cloud Observations On-Line (S'COOL) project into a problem-based learning (PBL) activity, middle school students are engaged in authentic scientific research where they observe and record information about clouds and contribute ground truth data to NASA's Clouds and the Earth's

  3. CloudSat Preps for Launch at Vandenberg Air Force Base, CA

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The CloudSat spacecraft sits encapsulated within its Boeing Delta launch vehicle dual payload attach fitting at Vandenberg Air Force Base, Calif. CloudSat will share its ride to orbit late next month with NASA's CALIPSO spacecraft. The two spacecraft are designed to reveal the secrets of clouds and aerosols.

  4. Climate change signal and uncertainty in CMIP5-based projections of global ocean surface wave heights

    NASA Astrophysics Data System (ADS)

    Wang, Xiaolan L.; Feng, Yang; Swail, Val R.

    2015-05-01

    This study uses the analysis of variance approaches to quantify the climate change signal and uncertainty in multimodel ensembles of statistical simulations of significant wave height (Hs), which are based on the CMIP5 historical, RCP4.5 and RCP8.5 forcing scenario simulations of sea level pressure. Here the signal of climate change refers to the temporal variations caused by the prescribed forcing. "Significant" means "significantly different from zero at 5% level." In a four-model ensemble of Hs simulations, the common signalthe signal that is simulated in all the four modelsis found to strengthen over time. For the historical followed by RCP8.5 scenario, the common signal in annual mean Hs is found to be significant in 16.6% and 82.2% of the area by year 2005 and 2099, respectively. The global average of the variance proportion of the common signal increases from 0.75% in year 2005 to 12.0% by year 2099. The signal is strongest in the eastern tropical Pacific (ETP), featuring significant increases in both the annual mean and maximum of Hs in this region. The climate model uncertainty (i.e., intermodel variability) is significant nearly globally; its magnitude is comparable to or greater than that of the common signal in most areas, except in the ETP where the signal is much larger. In a 20-model ensemble of Hs simulations for the period 2006-2099, the model uncertainty is found to be significant globally; it is about 10 times as large as the variability between the RCP4.5 and RCP8.5 scenarios. The copyright line for this article was changed on 10 JUNE 2015 after original online publication.

  5. Importance of aggregation and small ice crystals in cirrus clouds, based on observations and an ice particle growth model

    NASA Technical Reports Server (NTRS)

    Mitchell, David L.; Chai, Steven K.; Dong, Yayi; Arnott, W. Patrick; Hallett, John

    1993-01-01

    The 1 November 1986 FIRE I case study was used to test an ice particle growth model which predicts bimodal size spectra in cirrus clouds. The model was developed from an analytically based model which predicts the height evolution of monomodal ice particle size spectra from the measured ice water content (IWC). Size spectra from the monomodal model are represented by a gamma distribution, N(D) = N(sub o)D(exp nu)exp(-lambda D), where D = ice particle maximum dimension. The slope parameter, lambda, and the parameter N(sub o) are predicted from the IWC through the growth processes of vapor diffusion and aggregation. The model formulation is analytical, computationally efficient, and well suited for incorporation into larger models. The monomodal model has been validated against two other cirrus cloud case studies. From the monomodal size spectra, the size distributions which determine concentrations of ice particles less than about 150 mu m are predicted.

  6. Dental implants typically help retain peri-implant vertical bone height: evidence-based analysis.

    PubMed

    Greenstein, Gary; Cavallaro, John

    2013-01-01

    The dental literature is assessed regarding the ability of dental implants to maintain vertical bone height after various implant placement scenarios: immediate, delayed, insertion into partially and fully edentate healed ridges, and under overdentures. Studies are also reviewed to determine if bone loss after implant insertion is continuous. Numerous investigations that support the concept that implants preserve bone height are identified. In addition, the data indicate that a minuscule amount of annual bone loss usually persists after implant placement, but it is often clinically imperceptible. PMID:24428502

  7. Cloud Thickness from Offbeam Returns - Thor Lidar

    NASA Technical Reports Server (NTRS)

    Cahalan, R.; Kolasinski, J.; McGill, M.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Physical thickness of a cloud layer, and sometimes multiple cloud layers, can be estimated from the time delay of off-beam returns from a pulsed laser source illuminating one side of the cloud layer. In particular, the time delay of light returning from the outer diffuse halo of light surrounding the beam entry point, relative to the time delay at beam center, determines the cloud physical thickness. The delay combined with the pulse stretch gives the optical thickness. The halo method works best for thick cloud layers, typically optical thickness exceeding 2, and thus compliments conventional lidar which cannot penetrate thick clouds. Cloud layer top and base have been measured independently over the ARM/SGP site using conventional laser ranging (lidar) and the top minus base thickness are compared with a cloud top halo estimate obtained from the NASA/Goddard THOR System (THOR = THickness from Offbeam Returns). THOR flies on the NASA P3, and measures the halo timings from several km above cloud top, at the same time providing conventional lidar cloud top height. The ARM/SGP micropulse lidar provides cloud base height for validation.

  8. Cloud based, Open Source Software Application for Mitigating Herbicide Drift

    NASA Astrophysics Data System (ADS)

    Saraswat, D.; Scott, B.

    2014-12-01

    The spread of herbicide resistant weeds has resulted in the need for clearly marked fields. In response to this need, the University of Arkansas Cooperative Extension Service launched a program named Flag the Technology in 2011. This program uses color-coded flags as a visual alert of the herbicide trait technology within a farm field. The flag based program also serves to help avoid herbicide misapplication and prevent herbicide drift damage between fields with differing crop technologies. This program has been endorsed by Southern Weed Science Society of America and is attracting interest from across the USA, Canada, and Australia. However, flags have risk of misplacement or disappearance due to mischief or severe windstorms/thunderstorms, respectively. This presentation will discuss the design and development of a cloud-based, free application utilizing open-source technologies, called Flag the Technology Cloud (FTTCloud), for allowing agricultural stakeholders to color code their farm fields for indicating herbicide resistant technologies. The developed software utilizes modern web development practices, widely used design technologies, and basic geographic information system (GIS) based interactive interfaces for representing, color-coding, searching, and visualizing fields. This program has also been made compatible for a wider usability on different size devices- smartphones, tablets, desktops and laptops.

  9. Comparison of Cloud Properties from CALIPSO-CloudSat and Geostationary Satellite Data

    NASA Technical Reports Server (NTRS)

    Nguyen, L.; Minnis, P.; Chang, F.; Winker, D.; Sun-Mack, S.; Spangenberg, D.; Austin, R.

    2007-01-01

    Cloud properties are being derived in near-real time from geostationary satellite imager data for a variety of weather and climate applications and research. Assessment of the uncertainties in each of the derived cloud parameters is essential for confident use of the products. Determination of cloud amount, cloud top height, and cloud layering is especially important for using these real -time products for applications such as aircraft icing condition diagnosis and numerical weather prediction model assimilation. Furthermore, the distribution of clouds as a function of altitude has become a central component of efforts to evaluate climate model cloud simulations. Validation of those parameters has been difficult except over limited areas where ground-based active sensors, such as cloud radars or lidars, have been available on a regular basis. Retrievals of cloud properties are sensitive to the surface background, time of day, and the clouds themselves. Thus, it is essential to assess the geostationary satellite retrievals over a variety of locations. The availability of cloud radar data from CloudSat and lidar data from CALIPSO make it possible to perform those assessments over each geostationary domain at 0130 and 1330 LT. In this paper, CloudSat and CALIPSO data are matched with contemporaneous Geostationary Operational Environmental Satellite (GOES), Multi-functional Transport Satellite (MTSAT), and Meteosat-8 data. Unlike comparisons with cloud products derived from A-Train imagers, this study considers comparisons of nadir active sensor data with off-nadir retrievals. These matched data are used to determine the uncertainties in cloud-top heights and cloud amounts derived from the geostationary satellite data using the Clouds and the Earth s Radiant Energy System (CERES) cloud retrieval algorithms. The CERES multi-layer cloud detection method is also evaluated to determine its accuracy and limitations in the off-nadir mode. The results will be useful for constraining the use of the passive retrieval data in models and for improving the accuracy of the retrievals.

  10. Three-dimensional geospatial information service based on cloud computing

    NASA Astrophysics Data System (ADS)

    Zhai, Xi; Yue, Peng; Jiang, Liangcun; Wang, Linnan

    2014-01-01

    Cloud computing technologies can support high-performance geospatial services in various domains, such as smart city and agriculture. Apache Hadoop, an open-source software framework, can be used to build a cloud environment on commodity clusters for storage and large-scale processing of data sets. The Open Geospatial Consortium (OGC) Web 3-D Service (W3DS) is a portrayal service for three-dimensional (3-D) geospatial data. Its performance could be improved by cloud computing technologies. This paper investigates how OGC W3DS could be developed in a cloud computing environment. It adopts the Apache Hadoop as the framework to provide a cloud implementation. The design and implementation of the 3-D geospatial information cloud service is presented. The performance evaluation is performed over data retrieval tests running in a cloud platform built by Hadoop clusters. The evaluation results provide a valuable reference on providing high-performance 3-D geospatial information cloud services.

  11. Comparison of CERES-MODIS Stratus Cloud Properties with Ground-Based Measurements at the DOE ARM Southern Great Plains Site

    NASA Technical Reports Server (NTRS)

    Dong, Xiquan; Minnis Patrick; Xi, Baike; Sun-Mack, Sunny; Chen, Yan

    2008-01-01

    Overcast stratus cloud properties derived for the Clouds and the Earth's Radiant Energy system (CERES) Project using Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) data are compared with observations taken at the Atmospheric Radiation Measurement (ARM) Southern Great Plains site from March 2000 through December 2004. Retrievals from ARM surface-based data were averaged over a 1-hour interval centered at the time of each satellite overpass, and the CERES-MODIS cloud properties were averaged within a 30-km x 30 km box centered on the ARM SGP site. Two datasets were analyzed: all of the data (ALL) which include multilayered, single-layered, and slightly broken stratus decks and a subset, single-layered unbroken decks (SL). The CERES-MODIS effective cloud heights were determined from effective cloud temperature using a lapse rate method with the surface temperature specified as the 24-h mean surface air temperature. For SL stratus, they are, on average, within the ARM radar-lidar estimated cloud boundaries and are 0.534 +/- 0.542 km and 0.108 +/- 0.480 km lower than the cloud physical tops and centers, respectively, and are comparable for day and night observations. The mean differences and standard deviations are slightly larger for ALL data, but not statistically different to those of SL data. The MODIS-derived effective cloud temperatures are 2.7 +/- 2.4 K less than the surface-observed SL cloud center temperatures with very high correlations (0.86-0.97). Variations in the height differences are mainly caused by uncertainties in the surface air temperatures, lapse rates, and cloud-top height variability. The biases are mainly the result of the differences between effective and physical cloud top, which are governed by cloud liquid water content and viewing zenith angle, and the selected lapse rate, -7.1 K km(exp -1). Based on a total of 43 samples, the means and standard deviations of the differences between the daytime Terra and surface retrievals of effective radius r(sub e), optical depth, and liquid water path for SL stratu are 0.1 +/- 1.9 micrometers (1.2 +/- 23.5%), -1.3 +/- 9.5 (-3.6 +/-26.2%), and 0.6 +/- 49.9 gm (exp -2) (0.3 +/- 27%), respectively, while the corresponding correlation coefficients are 0.44, 0.87, and 0.89. For Aqua, they are 0.2 +/- 1.9 micrometers (2.5 +/- 23.4%), 2.5 +/- 7.8 (7.8 +/- 24.3%), and 28.1 +/- 52.7 gm (exp -2) (17.2 +/- 32.2%), as well as 0.35, 0.96, and 0.93 from a total of 21 cases. The results for ALL cases are comparable. Although a bias in R(sub e) was expected because the satellite retrieval of effective radius only represents the top of the cloud, the surface-based radar retrievals revealed that the vertical profile of r(sub e) is highly variable with smaller droplets occurring at cloud top in some cases. The larger bias in optical depth and liquid water path for Aqua is due, at least partially, to differences in the Terra and Aqua MODIS visible channel calibrations. methods for improving the cloud-top height and microphysical property retrievals are suggested.

  12. An Expert Fitness Diagnosis System Based on Elastic Cloud Computing

    PubMed Central

    Tseng, Kevin C.; Wu, Chia-Chuan

    2014-01-01

    This paper presents an expert diagnosis system based on cloud computing. It classifies a user's fitness level based on supervised machine learning techniques. This system is able to learn and make customized diagnoses according to the user's physiological data, such as age, gender, and body mass index (BMI). In addition, an elastic algorithm based on Poisson distribution is presented to allocate computation resources dynamically. It predicts the required resources in the future according to the exponential moving average of past observations. The experimental results show that Naïve Bayes is the best classifier with the highest accuracy (90.8%) and that the elastic algorithm is able to capture tightly the trend of requests generated from the Internet and thus assign corresponding computation resources to ensure the quality of service. PMID:24723842

  13. An expert fitness diagnosis system based on elastic cloud computing.

    PubMed

    Tseng, Kevin C; Wu, Chia-Chuan

    2014-01-01

    This paper presents an expert diagnosis system based on cloud computing. It classifies a user's fitness level based on supervised machine learning techniques. This system is able to learn and make customized diagnoses according to the user's physiological data, such as age, gender, and body mass index (BMI). In addition, an elastic algorithm based on Poisson distribution is presented to allocate computation resources dynamically. It predicts the required resources in the future according to the exponential moving average of past observations. The experimental results show that Naïve Bayes is the best classifier with the highest accuracy (90.8%) and that the elastic algorithm is able to capture tightly the trend of requests generated from the Internet and thus assign corresponding computation resources to ensure the quality of service. PMID:24723842

  14. A cloud computing based 12-lead ECG telemedicine service

    PubMed Central

    2012-01-01

    Background Due to the great variability of 12-lead ECG instruments and medical specialists’ interpretation skills, it remains a challenge to deliver rapid and accurate 12-lead ECG reports with senior cardiologists’ decision making support in emergency telecardiology. Methods We create a new cloud and pervasive computing based 12-lead Electrocardiography (ECG) service to realize ubiquitous 12-lead ECG tele-diagnosis. Results This developed service enables ECG to be transmitted and interpreted via mobile phones. That is, tele-consultation can take place while the patient is on the ambulance, between the onsite clinicians and the off-site senior cardiologists, or among hospitals. Most importantly, this developed service is convenient, efficient, and inexpensive. Conclusions This cloud computing based ECG tele-consultation service expands the traditional 12-lead ECG applications onto the collaboration of clinicians at different locations or among hospitals. In short, this service can greatly improve medical service quality and efficiency, especially for patients in rural areas. This service has been evaluated and proved to be useful by cardiologists in Taiwan. PMID:22838382

  15. An efficient framework for modeling clouds from Landsat8 images

    NASA Astrophysics Data System (ADS)

    Yuan, Chunqiang; Guo, Jing

    2015-03-01

    Cloud plays an important role in creating realistic outdoor scenes for video game and flight simulation applications. Classic methods have been proposed for cumulus cloud modeling. However, these methods are not flexible for modeling large cloud scenes with hundreds of clouds in that the user must repeatedly model each cloud and adjust its various properties. This paper presents a meteorologically based method to reconstruct cumulus clouds from high resolution Landsat8 satellite images. From these input satellite images, the clouds are first segmented from the background. Then, the cloud top surface is estimated from the temperature of the infrared image. After that, under a mild assumption of flat base for cumulus cloud, the base height of each cloud is computed by averaging the top height for pixels on the cloud edge. Then, the extinction is generated from the visible image. Finally, we enrich the initial shapes of clouds using a fractal method and represent the recovered clouds as a particle system. The experimental results demonstrate our method can yield realistic cloud scenes resembling those in the satellite images.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  17. Towards Cloud-based Asynchronous Elasticity for Iterative HPC Applications

    NASA Astrophysics Data System (ADS)

    da Rosa Righi, Rodrigo; Facco Rodrigues, Vinicius; André da Costa, Cristiano; Kreutz, Diego; Heiss, Hans-Ulrich

    2015-10-01

    Elasticity is one of the key features of cloud computing. It allows applications to dynamically scale computing and storage resources, avoiding over- and under-provisioning. In high performance computing (HPC), initiatives are normally modeled to handle bag-of-tasks or key-value applications through a load balancer and a loosely-coupled set of virtual machine (VM) instances. In the joint-field of Message Passing Interface (MPI) and tightly-coupled HPC applications, we observe the need of rewriting source codes, previous knowledge of the application and/or stop-reconfigure-and-go approaches to address cloud elasticity. Besides, there are problems related to how profit this new feature in the HPC scope, since in MPI 2.0 applications the programmers need to handle communicators by themselves, and a sudden consolidation of a VM, together with a process, can compromise the entire execution. To address these issues, we propose a PaaS-based elasticity model, named AutoElastic. It acts as a middleware that allows iterative HPC applications to take advantage of dynamic resource provisioning of cloud infrastructures without any major modification. AutoElastic provides a new concept denoted here as asynchronous elasticity, i.e., it provides a framework to allow applications to either increase or decrease their computing resources without blocking the current execution. The feasibility of AutoElastic is demonstrated through a prototype that runs a CPU-bound numerical integration application on top of the OpenNebula middleware. The results showed the saving of about 3 min at each scaling out operations, emphasizing the contribution of the new concept on contexts where seconds are precious.

  18. 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.

  19. Unification of Intercontinental Height Systems based on the Fixed Geodetic Boundary Value Problem - A Case Study in Spherical Approximation

    NASA Astrophysics Data System (ADS)

    Grombein, T.; Seitz, K.; Heck, B.

    2013-12-01

    In general, national height reference systems are related to individual vertical datums defined by specific tide gauges. The discrepancy of these vertical datums causes height system biases that range in an order of 1-2 m at a global scale. Continental height systems can be connected by spirit leveling and gravity measurements along the leveling lines as performed for the definition of the European Vertical Reference Frame. In order to unify intercontinental height systems, an indirect connection is needed. For this purpose, global geopotential models derived from recent satellite missions like GOCE provide an important contribution. However, to achieve a highly-precise solution, a combination with local terrestrial gravity data is indispensable. Such combinations result in the solution of a Geodetic Boundary Value Problem (GBVP). In contrast to previous studies, mostly related to the traditional (scalar) free GBVP, the present paper discusses the use of the fixed GBVP for height system unification, where gravity disturbances instead of gravity anomalies are applied as boundary values. The basic idea of our approach is a conversion of measured gravity anomalies to gravity disturbances, where unknown datum parameters occur that can be associated with height system biases. In this way, the fixed GBVP can be extended by datum parameters for each datum zone. By evaluating the GBVP at GNSS/leveling benchmarks, the unknown datum parameters can be estimated in a least squares adjustment. Beside the developed theory, we present numerical results of a case study based on the spherical fixed GBVP and boundary values simulated by the use of the global geopotential model EGM2008. In a further step, the impact of approximations like linearization as well as topographic and ellipsoidal effects is taken into account by suitable reduction and correction terms.

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

    SciTech Connect

    Luke,E.; Kollias, P.

    2007-08-06

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

  1. Entrainment and mixing mechanism in monsoon clouds

    NASA Astrophysics Data System (ADS)

    Bera, Sudarsan; Prabhakaran, Thara; Pandithurai, Govindan; Brenguier, Jean-Louis

    2015-04-01

    Entrainment and consequent mixing impacts the cloud microphysical parameters and droplet size distribution (DSD) significantly which are very important for cloud radiative properties and the mechanism for first rain drop formation. The entrainment and mixing mechanisms are investigated in this study using in situ observations in warm cumulus clouds over monsoon region. Entrainment is discussed in the framework of the homogeneous and inhomogeneous mixing concepts and their effects on cloud droplet size distribution, number concentration, liquid water content and mean radius are described. The degree of homogeneity increases with droplet number concentration and adiabatic fraction, indicating homogeneous type mixing in the cloud core where dilution is less. Inhomogeneous mixing is found to be a dominating process at cloud edges where dilution is significant. Cloud droplet size distribution (DSD) is found to shift towards lower sizes during a homogeneous mixing event in the cloud core whereas spectral width of DSD decreases due to inhomogeneous mixing at cloud edges. Droplet size spectra suggests that largest droplets are mainly formed in the less diluted cloud core while diluted cloud edges have relatively smaller droplets, so that raindrop formation occurs mainly in the core of the cloud. The origin of the entrained parcels in deep cumulus clouds is investigated using conservative thermodynamical parameters. The entrained parcels originate from a level close to the observation level or slightly below through lateral edges. Cloud edges are significantly diluted due to entrainment of sub-saturated environmental air which can penetrate several hundred meters inside the cloud before it gets mixed completely with the cloud mass. Less diluted parcels inside the cloud core originates from a level much below the cloud base height. Penetrating downdraft from cloud top is seldom observed at the observation level and strong downdrafts may be attributed to in-cloud oscillation of parcels.

  2. Simulation Platform: a cloud-based online simulation environment.

    PubMed

    Yamazaki, Tadashi; Ikeno, Hidetoshi; Okumura, Yoshihiro; Satoh, Shunji; Kamiyama, Yoshimi; Hirata, Yutaka; Inagaki, Keiichiro; Ishihara, Akito; Kannon, Takayuki; Usui, Shiro

    2011-09-01

    For multi-scale and multi-modal neural modeling, it is needed to handle multiple neural models described at different levels seamlessly. Database technology will become more important for these studies, specifically for downloading and handling the neural models seamlessly and effortlessly. To date, conventional neuroinformatics databases have solely been designed to archive model files, but the databases should provide a chance for users to validate the models before downloading them. In this paper, we report our on-going project to develop a cloud-based web service for online simulation called "Simulation Platform". Simulation Platform is a cloud of virtual machines running GNU/Linux. On a virtual machine, various software including developer tools such as compilers and libraries, popular neural simulators such as GENESIS, NEURON and NEST, and scientific software such as Gnuplot, R and Octave, are pre-installed. When a user posts a request, a virtual machine is assigned to the user, and the simulation starts on that machine. The user remotely accesses to the machine through a web browser and carries out the simulation, without the need to install any software but a web browser on the user's own computer. Therefore, Simulation Platform is expected to eliminate impediments to handle multiple neural models that require multiple software. PMID:21741207

  3. Video-Based Point Cloud Generation Using Multiple Action Cameras

    NASA Astrophysics Data System (ADS)

    Teo, T.

    2015-05-01

    Due to the development of action cameras, the use of video technology for collecting geo-spatial data becomes an important trend. The objective of this study is to compare the image-mode and video-mode of multiple action cameras for 3D point clouds generation. Frame images are acquired from discrete camera stations while videos are taken from continuous trajectories. The proposed method includes five major parts: (1) camera calibration, (2) video conversion and alignment, (3) orientation modelling, (4) dense matching, and (5) evaluation. As the action cameras usually have large FOV in wide viewing mode, camera calibration plays an important role to calibrate the effect of lens distortion before image matching. Once the camera has been calibrated, the author use these action cameras to take video in an indoor environment. The videos are further converted into multiple frame images based on the frame rates. In order to overcome the time synchronous issues in between videos from different viewpoints, an additional timer APP is used to determine the time shift factor between cameras in time alignment. A structure form motion (SfM) technique is utilized to obtain the image orientations. Then, semi-global matching (SGM) algorithm is adopted to obtain dense 3D point clouds. The preliminary results indicated that the 3D points from 4K video are similar to 12MP images, but the data acquisition performance of 4K video is more efficient than 12MP digital images.

  4. The impact of frenulum height on strains in maxillary denture bases

    PubMed Central

    Bilhan, Hakan; Baysal, Gokhan; Sunbuloglu, Emin; Bozdag, Ergun

    2013-01-01

    PURPOSE The midline fracture of maxillary complete dentures is a frequently encountered complication. The purpose of this study was to assess the effect of frenulum height on midline strains of maxillary complete dentures. MATERIALS AND METHODS A removable maxillary complete denture was fabricated and duplicated seven times. Four different labial frenulum heights were tested for stresses occurring on the palatal cameo surface. The strains were measured with strain gauges placed on 5 different locations and the stresses were calculated. To mimic occlusal forces bilaterally 100 N of load was applied from the premolar and molar region. RESULTS A statistically significant association between the height of the labial frenulum and the calculated stresses and strains was shown (P<.05) predominantly on the midline and especially on the incisive papilla. The results showed that stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. CONCLUSION Within the limitations of this in vitro study, it can be concluded that the stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. Surgical or mechanical precautions should be taken to prevent short-term failure of maxillary complete dentures due to stress concentration and low cycle fatigue tendency at the labial frenulum region. PMID:24353878

  5. UAV based tree height estimation in apple orchards: potential of multiple approaches

    NASA Astrophysics Data System (ADS)

    Mejia-Aguilar, Abraham; Tomelleri, Enrico; Vilardi, Andrea; Zebisch, Marc

    2015-04-01

    Canopy height, as part of vegetation structure, is ecologically important for ecological studies on biomass, matter flows or meteorology. Measuring the growth of canopy can be undertaken by the use multiple remote sensing techniques. In this study, we firstly use data generated from an Unmanned Aerial Vehicles (UAV) with a simultaneous consumer-grade RGB and modified IR cameras, configured in nadir and multi-angle views to generate 3D models for Digital Surface Model (DSM) and Digital Terrain Models (DTM) in order to estimate tree height in apple orchards in South Tyrol, Italy. We evaluate the use of Ground Control Points (GCP) to minimize the error in scale and orientation. Then, we validate and compare the results of our primary data collection with data generated by geolocated field measurements over several selected tree species. Additionally, we compare DSM and DTM obtained from a recent 1-meter resolution LIDAR campaign (Light Detection and Ranging). The main purpose of this study is to contrast multiple estimation approaches and evaluate their utility for the estimation of canopy height, highlighting the use of UAV systems as a fast, reliable and non-expensive technique especially for small scale applications. The study is conducted in a homogenous tree canopy consisting of apple orchards located in Caldaro -South Tyrol, Italy. We end with proposing a potential low-cost and inexpensive application combining models for DSM from the UAV with DTM obtained from LIDAR for applications that should be updated frequently.

  6. CloudWF: A Computational Workflow System for Clouds Based on Hadoop

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; de Sterck, Hans

    This paper describes CloudWF, a scalable and lightweight computational workflow system for clouds on top of Hadoop. CloudWF can run workflow jobs composed of multiple Hadoop MapReduce or legacy programs. Its novelty lies in several aspects: a simple workflow description language that encodes workflow blocks and block-to-block dependencies separately as standalone executable components; a new workflow storage method that uses Hadoop HBase sparse tables to store workflow information internally and reconstruct workflow block dependencies implicitly for efficient workflow execution; transparent file staging with Hadoop DFS; and decentralized workflow execution management relying on the MapReduce framework for task scheduling and fault tolerance. This paper describes the design and implementation of CloudWF.

  7. Geometric data perturbation-based personal health record transactions in cloud computing.

    PubMed

    Balasubramaniam, S; Kavitha, V

    2015-01-01

    Cloud computing is a new delivery model for information technology services and it typically involves the provision of dynamically scalable and often virtualized resources over the Internet. However, cloud computing raises concerns on how cloud service providers, user organizations, and governments should handle such information and interactions. Personal health records represent an emerging patient-centric model for health information exchange, and they are outsourced for storage by third parties, such as cloud providers. With these records, it is necessary for each patient to encrypt their own personal health data before uploading them to cloud servers. Current techniques for encryption primarily rely on conventional cryptographic approaches. However, key management issues remain largely unsolved with these cryptographic-based encryption techniques. We propose that personal health record transactions be managed using geometric data perturbation in cloud computing. In our proposed scheme, the personal health record database is perturbed using geometric data perturbation and outsourced to the Amazon EC2 cloud. PMID:25767826

  8. Geometric Data Perturbation-Based Personal Health Record Transactions in Cloud Computing

    PubMed Central

    Balasubramaniam, S.; Kavitha, V.

    2015-01-01

    Cloud computing is a new delivery model for information technology services and it typically involves the provision of dynamically scalable and often virtualized resources over the Internet. However, cloud computing raises concerns on how cloud service providers, user organizations, and governments should handle such information and interactions. Personal health records represent an emerging patient-centric model for health information exchange, and they are outsourced for storage by third parties, such as cloud providers. With these records, it is necessary for each patient to encrypt their own personal health data before uploading them to cloud servers. Current techniques for encryption primarily rely on conventional cryptographic approaches. However, key management issues remain largely unsolved with these cryptographic-based encryption techniques. We propose that personal health record transactions be managed using geometric data perturbation in cloud computing. In our proposed scheme, the personal health record database is perturbed using geometric data perturbation and outsourced to the Amazon EC2 cloud. PMID:25767826

  9. Segment based shape matching in terrestrial laser scanning point clouds

    NASA Astrophysics Data System (ADS)

    Bremer, Magnus; Rutzinger, Martin; Wichmann, Volker

    2013-04-01

    Change detection of dynamic surface elements is an important application in geomorphological analysis. In order to be able to investigate such changes, the high spatial resolution and accuracy of the laser scanning technology is exploited. Dealing with laser scanning data, most change detection approaches are aiming at the assessment of volumetric changes due to erosion and deposition by geomorphologic processes. In these cases the areas of erosion and deposition are spatially separated and can be investigated in a cut-and-fill analysis. Where slow changes are controlled by interior deformation of material mixtures due to gravity, surface changes are mostly due to slight movements of objects and not to absolute material losses and gains. In complex terrain an object-based approach for the reconstruction of 3D change vectors is required. Depending on the level of scale, terrain can be subdivided into a large number of small planar patches. Using 3D point cloud data from terrestrial laser scanning, this can be done by a planar segmentation procedure grouping laser points of flat surfaces. Rotating each point cloud segment into its best fit plane, its 2D footprint shows specific local surface characteristics. Thus, each surface patch has a unique fingerprint that can be described by a variety of segment features. In an experimental framework we test the capability of shape based matching for the derivation of change vectors on dynamic surfaces. To consider different data characteristics such as varying point densities and scan perspectives, terrestrial laser scans of a rock glacier are acquired from three positions with an Optech ILRIS3D terrestrial laser scanner. Additionally, the point density is manipulated in order to simulate three different levels of point density. For the matching of surface patches, we test various non-metric shape features such as roundness, concavity and elongation. Besides, we use metric shape features such as patch area, perimeter and the modified Hausdorff-Distance for the detection of similar patches. Comparing metric and non-metric segment features the non-metric features show a more robust matching of surface patches in point clouds with differing point density and perspectives. However, with high point densities and similar scan perspectives, a combination of non-metric and metric features shows the best matching results.

  10. Analysis of the Security and Privacy Requirements of Cloud-Based Electronic Health Records Systems

    PubMed Central

    Fernández, Gonzalo; López-Coronado, Miguel

    2013-01-01

    Background The Cloud Computing paradigm offers eHealth systems the opportunity to enhance the features and functionality that they offer. However, moving patients’ medical information to the Cloud implies several risks in terms of the security and privacy of sensitive health records. In this paper, the risks of hosting Electronic Health Records (EHRs) on the servers of third-party Cloud service providers are reviewed. To protect the confidentiality of patient information and facilitate the process, some suggestions for health care providers are made. Moreover, security issues that Cloud service providers should address in their platforms are considered. Objective To show that, before moving patient health records to the Cloud, security and privacy concerns must be considered by both health care providers and Cloud service providers. Security requirements of a generic Cloud service provider are analyzed. Methods To study the latest in Cloud-based computing solutions, bibliographic material was obtained mainly from Medline sources. Furthermore, direct contact was made with several Cloud service providers. Results Some of the security issues that should be considered by both Cloud service providers and their health care customers are role-based access, network security mechanisms, data encryption, digital signatures, and access monitoring. Furthermore, to guarantee the safety of the information and comply with privacy policies, the Cloud service provider must be compliant with various certifications and third-party requirements, such as SAS70 Type II, PCI DSS Level 1, ISO 27001, and the US Federal Information Security Management Act (FISMA). Conclusions Storing sensitive information such as EHRs in the Cloud means that precautions must be taken to ensure the safety and confidentiality of the data. A relationship built on trust with the Cloud service provider is essential to ensure a transparent process. Cloud service providers must make certain that all security mechanisms are in place to avoid unauthorized access and data breaches. Patients must be kept informed about how their data are being managed. PMID:23965254

  11. Cloud based toolbox for image analysis, processing and reconstruction tasks.

    PubMed

    Bednarz, Tomasz; Wang, Dadong; Arzhaeva, Yulia; Lagerstrom, Ryan; Vallotton, Pascal; Burdett, Neil; Khassapov, Alex; Szul, Piotr; Chen, Shiping; Sun, Changming; Domanski, Luke; Thompson, Darren; Gureyev, Timur; Taylor, John A

    2015-01-01

    This chapter describes a novel way of carrying out image analysis, reconstruction and processing tasks using cloud based service provided on the Australian National eResearch Collaboration Tools and Resources (NeCTAR) infrastructure. The toolbox allows users free access to a wide range of useful blocks of functionalities (imaging functions) that can be connected together in workflows allowing creation of even more complex algorithms that can be re-run on different data sets, shared with others or additionally adjusted. The functions given are in the area of cellular imaging, advanced X-ray image analysis, computed tomography and 3D medical imaging and visualisation. The service is currently available on the website www.cloudimaging.net.au . PMID:25381109

  12. A Cloud Computing Based Patient Centric Medical Information System

    NASA Astrophysics Data System (ADS)

    Agarwal, Ankur; Henehan, Nathan; Somashekarappa, Vivek; Pandya, A. S.; Kalva, Hari; Furht, Borko

    This chapter discusses an emerging concept of a cloud computing based Patient Centric Medical Information System framework that will allow various authorized users to securely access patient records from various Care Delivery Organizations (CDOs) such as hospitals, urgent care centers, doctors, laboratories, imaging centers among others, from any location. Such a system must seamlessly integrate all patient records including images such as CT-SCANS and MRI'S which can easily be accessed from any location and reviewed by any authorized user. In such a scenario the storage and transmission of medical records will have be conducted in a totally secure and safe environment with a very high standard of data integrity, protecting patient privacy and complying with all Health Insurance Portability and Accountability Act (HIPAA) regulations.

  13. Remote Sensing of Cloud Properties using Ground-based Measurements of Zenith Radiance

    NASA Technical Reports Server (NTRS)

    Chiu, J. Christine; Marshak, Alexander; Knyazikhin, Yuri; Wiscombe, Warren J.; Barker, Howard W.; Barnard, James C.; Luo, Yi

    2006-01-01

    An extensive verification of cloud property retrievals has been conducted for two algorithms using zenith radiances measured by the Atmospheric Radiation Measurement (ARM) Program ground-based passive two-channel (673 and 870 nm) Narrow Field-Of-View Radiometer. The underlying principle of these algorithms is that clouds have nearly identical optical properties at these wavelengths, but corresponding spectral surface reflectances (for vegetated surfaces) differ significantly. The first algorithm, the RED vs. NIR, works for a fully three-dimensional cloud situation. It retrieves not only cloud optical depth, but also an effective radiative cloud fraction. Importantly, due to one-second time resolution of radiance measurements, we are able, for the first time, to capture detailed changes in cloud structure at the natural time scale of cloud evolution. The cloud optical depths tau retrieved by this algorithm are comparable to those inferred from both downward fluxes in overcast situations and microwave brightness temperatures for broken clouds. Moreover, it can retrieve tau for thin patchy clouds, where flux and microwave observations fail to detect them. The second algorithm, referred to as COUPLED, couples zenith radiances with simultaneous fluxes to infer 2. In general, the COUPLED and RED vs. NIR algorithms retrieve consistent values of tau. However, the COUPLED algorithm is more sensitive to the accuracies of measured radiance, flux, and surface reflectance than the RED vs. NIR algorithm. This is especially true for thick overcast clouds where it may substantially overestimate z.

  14. Genetic and Environmental Effects on Weight, Height, and BMI Under 18 Years in a Chinese Population-Based Twin Sample.

    PubMed

    Liu, Qingqing; Yu, Canqing; Gao, Wenjing; Cao, Weihua; Lyu, Jun; Wang, Shengfeng; Pang, Zengchang; Cong, Liming; Dong, Zhong; Wu, Fan; Wang, Hua; Wu, Xianping; Jiang, Guohong; Wang, Binyou; Li, Liming

    2015-10-01

    This study examined the genetic and environmental effects on variances in weight, height, and body mass index (BMI) under 18 years in a population-based sample from China. We selected 6,644 monozygotic and 5,969 dizygotic twin pairs from the Chinese National Twin Registry (CNTR) aged under 18 years (n = 12,613). Classic twin analyses with sex limitation were used to estimate the genetic and environmental components of weight, height, and BMI in six age groups. Sex-limitation of genetic and shared environmental effects was observed, especially when puberty begins. Heritability for weight, height, and BMI was low at 0-2 years old (less than 20% for both sexes) but increased over time, accounting for half or more of the variance in the 15-17 year age group for boys. For girls, heritabilities for weight, height and BMI was maintained at approximately 30% after puberty. Common environmental effects on all body measures were high for girls (59-87%) and presented a small peak during puberty. Genetics appear to play an increasingly important role in explaining the variation in weight, height, and BMI from early childhood to late adolescence, particularly in boys. Common environmental factors exert their strongest and most independent influence specifically in the pre-adolescent period and more significantly in girls. These findings emphasize the need to target family and social environmental interventions in early childhood years, especially for females. Further studies about puberty-related genes and social environment are needed to clarify the mechanism of sex differences. PMID:26379063

  15. Dealing with clouds from space-based ultraspectral IR observations

    NASA Astrophysics Data System (ADS)

    Zhou, D.; Smith, W.; Liu, X.; Larar, A.; Mango, S.; Huang, H.-L.

    Hyperspectral infrared sounders with nadir observations are limited by the cloud cover It is critical to detect the clouds in satellite measurements and to accurately retrieve the atmospheric and surface parameters with cloud contamination measurements An inversion scheme has been developed dealing with cloudy as well as cloud-free radiances observed with ultraspectral infrared sounders to simultaneously retrieve surface atmospheric thermodynamic and cloud microphysical parameters A fast radiative transfer model which applies to the clouded atmosphere is used for atmospheric profile and cloud parameter retrieval A one-dimensional 1-d variational multi-variable inversion solution is used to iteratively improve the background state defined by an eigenvector-regression-retrieval The solution is iterated in order to account for non-linearity in the 1-d variational solution NPOESS Airborne Sounder Testbed -- Interferometer NAST-I retrievals are compared with coincident observations obtained from dropsondes and the nadir-pointing Cloud Physics Lidar CPL This work was motivated by the need to obtain solutions for atmospheric soundings from infrared radiances observed for every individual field of view regardless of cloud cover from future ultraspectral geostationary satellite sounding instruments such as the Geosynchronous Imaging Fourier Transform Spectrometer GIFTS and the Hyperspectral Environmental Suite HES However this retrieval approach can also be applied to the ultraspectral sounding instruments to fly on polar satellites such

  16. A cloud cover model based on satellite data

    NASA Technical Reports Server (NTRS)

    Somerville, P. N.; Bean, S. J.

    1980-01-01

    A model for worldwide cloud cover using a satellite data set containing infrared radiation measurements is proposed. The satellite data set containing day IR, night IR and incoming and absorbed solar radiation measurements on a 2.5 degree latitude-longitude grid covering a 45 month period was converted to estimates of cloud cover. The global area was then classified into homogeneous cloud cover regions for each of the four seasons. It is noted that the developed maps can be of use to the practicing climatologist who can obtain a considerable amount of cloud cover information without recourse to large volumes of data.

  17. The Atmospheric Infrared Sounder Version 6 Cloud Products

    NASA Technical Reports Server (NTRS)

    Kahn, B. H.; Irion, F. W.; Dang, V. T.; Manning, E. M.; Nasiri, S. L.; Naud, C. M.; Blaisdell, J. M.; Schreier, M. M..; Yue, Q.; Bowman, K. W.; Fetzer, E. J.; Hulley, G. C.; Liou, K. N.; Lubin, D.; Ou, S. C.; Susskind, J.; Takano, Y.; Tian, B.; Worden, J. R.

    2014-01-01

    The version 6 cloud products of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instrument suite are described. The cloud top temperature, pressure, and height and effective cloud fraction are now reported at the AIRS field-of-view (FOV) resolution. Significant improvements in cloud height assignment over version 5 are shown with FOV-scale comparisons to cloud vertical structure observed by the CloudSat 94 GHz radar and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP). Cloud thermodynamic phase (ice, liquid, and unknown phase), ice cloud effective diameter D(sub e), and ice cloud optical thickness (t) are derived using an optimal estimation methodology for AIRS FOVs, and global distributions for 2007 are presented. The largest values of tau are found in the storm tracks and near convection in the tropics, while D(sub e) is largest on the equatorial side of the midlatitude storm tracks in both hemispheres, and lowest in tropical thin cirrus and the winter polar atmosphere. Over the Maritime Continent the diurnal variability of tau is significantly larger than for the total cloud fraction, ice cloud frequency, and D(sub e), and is anchored to the island archipelago morphology. Important differences are described between northern and southern hemispheric midlatitude cyclones using storm center composites. The infrared-based cloud retrievals of AIRS provide unique, decadal-scale and global observations of clouds over portions of the diurnal and annual cycles, and capture variability within the mesoscale and synoptic scales at all latitudes.

  18. A cloud climatology of the Southern Great Plains ARM CART

    SciTech Connect

    Lazarus, S.M.; Krueger, S.K.; Mace, G.G.

    2000-05-15

    Cloud amount statistics from three different sources were processed and compared. Surface observations from a National Centers for Environmental Prediction dataset were used. The data (Edited Cloud Report; ECR) consist of synoptic weather reports that have been edited to facilitate cloud analysis. Two stations near the Southern Great Plains (SGP) Cloud and Radiation Test Bed (CART) in north-central Oklahoma (Oklahoma City, Oklahoma and Wichita, Kansas) were selected. The ECR data span a 10-yr period from December 1981 to November 1991. The International Satellite Cloud Climatology Project (ISCCP) provided cloud amounts over the SGP CART for an 8-yr period (1983--91). Cloud amounts were also obtained from Micro Pulse Lidar (MPL) and Belfort Ceilometer (BLC) cloud-base height measurements made at the SGP CART over a 1-yr period. The annual and diurnal cycles of cloud amount as a function of cloud height and type were analyzed. The three datasets closely agree for total cloud amount. Good agreement was found in the ECR and MPL-BLC monthly low cloud amounts. With the exception of summer and midday in other seasons, the ISCCP low cloud amount estimates are generally 5%--10% less than the others. The ECR high cloud amount estimates are typically 10%--15% greater than those obtained from either the ISCCP or MPL-BLC datasets. The observed diurnal variations of altocumulus support the authors' model results of radiatively induced circulations.

  19. Cloud-based large-scale air traffic flow optimization

    NASA Astrophysics Data System (ADS)

    Cao, Yi

    The ever-increasing traffic demand makes the efficient use of airspace an imperative mission, and this paper presents an effort in response to this call. Firstly, a new aggregate model, called Link Transmission Model (LTM), is proposed, which models the nationwide traffic as a network of flight routes identified by origin-destination pairs. The traversal time of a flight route is assumed to be the mode of distribution of historical flight records, and the mode is estimated by using Kernel Density Estimation. As this simplification abstracts away physical trajectory details, the complexity of modeling is drastically decreased, resulting in efficient traffic forecasting. The predicative capability of LTM is validated against recorded traffic data. Secondly, a nationwide traffic flow optimization problem with airport and en route capacity constraints is formulated based on LTM. The optimization problem aims at alleviating traffic congestions with minimal global delays. This problem is intractable due to millions of variables. A dual decomposition method is applied to decompose the large-scale problem such that the subproblems are solvable. However, the whole problem is still computational expensive to solve since each subproblem is an smaller integer programming problem that pursues integer solutions. Solving an integer programing problem is known to be far more time-consuming than solving its linear relaxation. In addition, sequential execution on a standalone computer leads to linear runtime increase when the problem size increases. To address the computational efficiency problem, a parallel computing framework is designed which accommodates concurrent executions via multithreading programming. The multithreaded version is compared with its monolithic version to show decreased runtime. Finally, an open-source cloud computing framework, Hadoop MapReduce, is employed for better scalability and reliability. This framework is an "off-the-shelf" parallel computing model that can be used for both offline historical traffic data analysis and online traffic flow optimization. It provides an efficient and robust platform for easy deployment and implementation. A small cloud consisting of five workstations was configured and used to demonstrate the advantages of cloud computing in dealing with large-scale parallelizable traffic problems.

  20. Cloud Service Solving N-Body Problem Based on Windows Azure Platform

    NASA Astrophysics Data System (ADS)

    Augustyn, Dariusz Rafał; Warchał, Łukasz

    This paper shows how to use cloud computing to solve N-body problem. It presents an idea and implementation of cloud service based on Windows Azure Platform. Clients can access cloud service via Internet over HTTP protocol. They create computation tasks supplying simulation parameters such as number of steps, time step and XML file with body definitions (initial position, mass and velocity). Presented solution uses Barnes-Hut Algorithm (based on adaptive oct tree) to reduce computation complexity form N ×N to N logN. All body interactions are computed in parallel, on worker nodes in cloud.

  1. Post-Adoption Issues Related to Cloud-Based IT Solutions: A Multi-Method Investigation

    ERIC Educational Resources Information Center

    Xiao, Xiao

    2013-01-01

    Due to their low cost of implementation and considerable elasticity, cloud-based IT solutions are being widely adopted or considered in organizations across various industries. However, such IT solutions bring forth several unique challenges--challenges that make it difficult for organizations to achieve successful utilization of cloud-based

  2. Cloud Optical Depth Measured with Ground-Based, Uncooled Infrared Imagers

    NASA Technical Reports Server (NTRS)

    Shaw, Joseph A.; Nugent, Paul W.; Pust, Nathan J.; Redman, Brian J.; Piazzolla, Sabino

    2012-01-01

    Recent advances in uncooled, low-cost, long-wave infrared imagers provide excellent opportunities for remotely deployed ground-based remote sensing systems. However, the use of these imagers in demanding atmospheric sensing applications requires that careful attention be paid to characterizing and calibrating the system. We have developed and are using several versions of the ground-based "Infrared Cloud Imager (ICI)" instrument to measure spatial and temporal statistics of clouds and cloud optical depth or attenuation for both climate research and Earth-space optical communications path characterization. In this paper we summarize the ICI instruments and calibration methodology, then show ICI-derived cloud optical depths that are validated using a dual-polarization cloud lidar system for thin clouds (optical depth of approximately 4 or less).

  3. Web-Based Self-Reported Height, Weight, and Body Mass Index Among Swedish Adolescents: A Validation Study

    PubMed Central

    Kull, Inger; Nilsson, Sara; Bergström, Anna

    2015-01-01

    Background Web-collected height and weight are increasingly used in epidemiological studies; however, the validity has rarely been evaluated. Objective The aim of the study was to validate self-reported height, weight, and corresponding body mass index (BMI) among Swedish adolescents aged approximately 16 years. A secondary aim was to investigate possible prediction factors for validity of self-reported BMI. Methods The study included 1698 adolescents from the population-based cohort BAMSE. Height and weight were collected through a Web-based questionnaire and subsequently measured using standard procedures. Differences between reported and measured height, weight, and corresponding BMI were compared by t tests and agreement was evaluated by Pearson correlation and Bland-Altman plots. Multivariable linear regression analysis was used to investigate whether lifestyle and demographic factors predicted validity of self-reported BMI. Results On average, weight was underestimated by 1.1 kg and height was overestimated by 0.5 cm, leading to an underestimation of BMI by 0.5 kg/m2. Correlation coefficients were .98 for height, .97 for weight, and .94 for BMI, and highly significant. Females underestimated weight to a higher extent than males and overweight and obese participants underestimated weight to a higher extent than normal-weight participants, which resulted in higher underestimation of BMI. Underweight participants, on the contrary, overestimated weight and correspondingly BMI. Overall, a high proportion of participants were classified into the correct BMI category; however, among overweight and obese participants, only 60.2% (139/231) and 46% (20/44) were correctly classified, respectively. In the multivariable prediction model, only gender and BMI status significantly predicted discrepancy between reported and measured BMI. Conclusions Web-collected BMI may be used as a valid, quick, and cost-effective alternative to measured BMI among Swedish adolescents. The accuracy of self-reported BMI declines with increasing BMI and self-reported BMI should not be used to estimate the prevalence of overweight or obesity. PMID:25791395

  4. A Semantic Based Policy Management Framework for Cloud Computing Environments

    ERIC Educational Resources Information Center

    Takabi, Hassan

    2013-01-01

    Cloud computing paradigm has gained tremendous momentum and generated intensive interest. Although security issues are delaying its fast adoption, cloud computing is an unstoppable force and we need to provide security mechanisms to ensure its secure adoption. In this dissertation, we mainly focus on issues related to policy management and access…

  5. A Semantic Based Policy Management Framework for Cloud Computing Environments

    ERIC Educational Resources Information Center

    Takabi, Hassan

    2013-01-01

    Cloud computing paradigm has gained tremendous momentum and generated intensive interest. Although security issues are delaying its fast adoption, cloud computing is an unstoppable force and we need to provide security mechanisms to ensure its secure adoption. In this dissertation, we mainly focus on issues related to policy management and access

  6. Cloud Privacy Audit Framework: A Value-Based Design

    ERIC Educational Resources Information Center

    Coss, David Lewis

    2013-01-01

    The rapid expansion of cloud technology provides enormous capacity, which allows for the collection, dissemination and re-identification of personal information. It is the cloud's resource capabilities such as these that fuel the concern for privacy. The impetus of these concerns are not to far removed from those expressed by Mason in 1986

  7. Cloud Privacy Audit Framework: A Value-Based Design

    ERIC Educational Resources Information Center

    Coss, David Lewis

    2013-01-01

    The rapid expansion of cloud technology provides enormous capacity, which allows for the collection, dissemination and re-identification of personal information. It is the cloud's resource capabilities such as these that fuel the concern for privacy. The impetus of these concerns are not to far removed from those expressed by Mason in 1986…

  8. Automatic analysis of stereoscopic GOES/GOES and GOES/NOAA image pairs for measurement of hurricane cloud top height and structure

    NASA Technical Reports Server (NTRS)

    Hasler, A. F.; Strong, J.; Pierce, H.; Woodward, R. H.

    1989-01-01

    Results are presented from a baseline study using an synthetic stereo image pair to test the Automatic Stereo Analysis (ASA) technique for reproducing cloud top structure. The ASA analysis, display, and calibration procedures are described. A GEO/LEO (GOES/NOAA AVHRR) image pair from Hurrican Allen in 1980 is used to illustrate the results that can be obtained using the ASA technique. Also, results are presented from applying the ASA technique to a GEO/GEO (GOES/GOES) image pair of Hurricane Gilbert in 1988.

  9. Edge features extraction from 3D laser point cloud based on corresponding images

    NASA Astrophysics Data System (ADS)

    Li, Xin-feng; Zhao, Zi-ming; Xu, Guo-qing; Geng, Yan-long

    2013-09-01

    An extraction method of edge features from 3D laser point cloud based on corresponding images was proposed. After the registration of point cloud and corresponding image, the sub-pixel edge can be extracted from the image using gray moment algorithm. Then project the sub-pixel edge to the point cloud in fitting scan-lines. At last the edge features were achieved by linking the crossing points. The experimental results demonstrate that the method guarantees accurate fine extraction.

  10. Coarse-fine vertical scanning based optical profiler for structured surface measurement with large step height

    NASA Astrophysics Data System (ADS)

    Zheng, Yi; Liu, Xiaojun; Lei, Zili; Li, Qian; Yang, Xiao; Chen, Liangzhou; Lu, Wenlong

    2015-02-01

    White light interference (WLI) optical profiler had been used widely for structured surface measurement. To achieve high measuring accuracy, piezoelectric ceramic (PZT) was usually used as the vertical scanning unit, which was normally less than 100um and only for small range structured surface measurement. With the development of advanced manufacturing technology, precision structured surfaces with large step height were appearing. To satisfy the measurement requirements of this kind of precision structured surfaces, WLI optical profiler with large range had to be developed. In this paper, an optical profiler was proposed, in which a coarse-fine vertical scanning system was adopted to expand its measurement range to 10mm while its resolution still at nanometer level.

  11. OpenID connect as a security service in Cloud-based diagnostic imaging systems

    NASA Astrophysics Data System (ADS)

    Ma, Weina; Sartipi, Kamran; Sharghi, Hassan; Koff, David; Bak, Peter

    2015-03-01

    The evolution of cloud computing is driving the next generation of diagnostic imaging (DI) systems. Cloud-based DI systems are able to deliver better services to patients without constraining to their own physical facilities. However, privacy and security concerns have been consistently regarded as the major obstacle for adoption of cloud computing by healthcare domains. Furthermore, traditional computing models and interfaces employed by DI systems are not ready for accessing diagnostic images through mobile devices. RESTful is an ideal technology for provisioning both mobile services and cloud computing. OpenID Connect, combining OpenID and OAuth together, is an emerging REST-based federated identity solution. It is one of the most perspective open standards to potentially become the de-facto standard for securing cloud computing and mobile applications, which has ever been regarded as "Kerberos of Cloud". We introduce OpenID Connect as an identity and authentication service in cloud-based DI systems and propose enhancements that allow for incorporating this technology within distributed enterprise environment. The objective of this study is to offer solutions for secure radiology image sharing among DI-r (Diagnostic Imaging Repository) and heterogeneous PACS (Picture Archiving and Communication Systems) as well as mobile clients in the cloud ecosystem. Through using OpenID Connect as an open-source identity and authentication service, deploying DI-r and PACS to private or community clouds should obtain equivalent security level to traditional computing model.

  12. Geometric and optical properties of cirrus clouds inferred from three-year ground-based lidar and CALIOP measurements over Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Kim, Yumi; Kim, Sang-Woo; Kim, Man-Hae; Yoon, Soon-Chang

    2014-03-01

    This study examines cirrus cloud top and bottom heights (CTH and CBH, respectively) and the associated optical properties revealed by ground-based lidar in Seoul (SNU-L), Korea, and space-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), which were obtained during a three-year measurement period between July 2006 and June 2009. From two selected cases, we determined good agreement in CTH and CBH with cirrus cloud optical depth (COD) between ground-based lidar and space-borne CALIOP. In particular, CODs at a wavelength of 532 nm calculated from the three years of SNU-L and CALIOP measurements were 0.417 ± 0.394 and 0.425 ± 0.479, respectively. The fraction of COD lower than 0.1 was approximately 17% and 25% of the total SNU-L and CALIOP profiles, respectively, and approximately 50% of both lidar profiles were classified as sub-visual or optically thin such that COD was < 0.3. The mean depolarization ratio was estimated to be 0.30 ± 0.06 for SNU-L and 0.34 ± 0.08 for CALIOP. The monthly variation of CODs from SNU-L and CALIOP measurements was not distinct, whereas cirrus altitudes from both SNU-L and CALIOP showed distinct monthly variation. CALIOP observations showed that cirrus clouds reached the tropopause level in all months, whereas the up-looking SNU-L did not detect cirrus clouds near the tropopause in summer due to signal attenuation by underlying optically thick clouds. The cloud layer thickness (CLT) and COD showed a distinct linear relationship up to approximately 2 km of the CLT; however, the COD did not increase, but remained constant when the CLT was greater than 2.0 km. The ice crystal content, lidar signal attenuation, and the presence of multi-layered cirrus clouds may have contributed to this tendency.

  13. Extended field observations of cirrus clouds using a ground-based cloud observing system

    NASA Technical Reports Server (NTRS)

    Ackerman, Thomas P.

    1994-01-01

    The evolution of synoptic-scale dynamics associated with a middle and upper tropospheric cloud event that occurred on 26 November 1991 is examined. The case under consideration occurred during the FIRE CIRRUS-II Intensive Field Observing Period held in Coffeyville, KS during Nov. and Dec., 1991. Using data from the wind profiler demonstration network and a temporally and spatially augmented radiosonde array, emphasis is given to explaining the evolution of the kinematically-derived ageostrophic vertical circulations and correlating the circulation with the forcing of an extensively sampled cloud field. This is facilitated by decomposing the horizontal divergence into its component parts through a natural coordinate representation of the flow. Ageostrophic vertical circulations are inferred and compared to the circulation forcing arising from geostrophic confluence and shearing deformation derived from the Sawyer-Eliassen Equation. It is found that a thermodynamically indirect vertical circulation existed in association with a jet streak exit region. The circulation was displaced to the cyclonic side of the jet axis due to the orientation of the jet exit between a deepening diffluent trough and building ridge. The cloud line formed in the ascending branch of the vertical circulation with the most concentrated cloud development occurring in conjunction with the maximum large-scale vertical motion. The relationship between the large scale dynamics and the parameterization of middle and upper tropospheric clouds in large-scale models is discussed and an example of ice water contents derived from a parameterization forced by the diagnosed vertical motions and observed water vapor contents is presented.

  14. Intercomparison of satellite- and ground-based cloud fraction over Switzerland (2000-2012)

    NASA Astrophysics Data System (ADS)

    Fontana, Fabio; Lugrin, David; Seiz, Gabriela; Meier, Marion; Foppa, Nando

    2013-07-01

    Satellite data provide the opportunity for systematic and continuous observation of cloud cover over large spatial scales. In this paper, we describe the generation of two new high spatial resolution (0.05°) daytime cloud fraction data sets over Switzerland. The data sets are based on the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask products. The data sets cover the period from March 1, 2000 to February 29, 2012 (Terra/MODIS) and July 1, 2002 to February 29, 2012 (Aqua/MODIS) and represent mid-morning and early-afternoon cloud cover over Switzerland. Time series clearly reflected seasonal variations in cloud fraction over Switzerland. A comparison with cloud fraction observations at four Synop stations (Chur, Locarno/Monti, Payerne, Zurich/Kloten) revealed an agreement of monthly mean mid-morning cloud fraction (MMCF) within ± 1 octa (i.e., 12.5%). Relative to Synop observations, MMCF was positively biased by 0.3-5.0%, except at Payerne (- 2.5%). Linear correlation coefficients ranged from 0.878 to 0.972. Results were similar for monthly mean early-afternoon cloud fraction (MACF). Cloud fraction was found to be higher in the early-afternoon when compared to mid-morning, except at Payerne and Zurich/Kloten in fall, which is explained by typical daytime cloud cover patterns in Switzerland. Analysis of daily mid-morning cloud fraction showed that largest discrepancies were observed in partly cloudy conditions, which is mainly explained by differences in observation times and observation geometry. Our results demonstrate that the newly processed cloud fraction data sets from the MODIS sensor can play an important role in complementing traditional Synop observations in support of systematic cloud cover monitoring within the National Climate Observing System (GCOS Switzerland).

  15. Cloud parameters using Ground Based Remote Sensing Systems and Satellites over urban coastal area

    NASA Astrophysics Data System (ADS)

    Han, Z. T.; Gross, B.; Moshary, F.; Wu, Y.; Ahmed, S. A.

    2013-12-01

    Determining cloud radiative and microphysical properties are very important as a means to assess their effect on earths energy balance. While MODIS and GOES have been used for estimating cloud properties, assessing cloud properties directly has been difficult due the lack of consistent ground based sensor measurements except in such established places such as the ARM site in Oklahoma. However, it is known that significant aerosol seeding from urban and/or maritime sources can modify cloud properties such as effective radius and cloud optical depth and therefore evaluation of satellite retrievals in such a unique area offers novel opportunities to assess the potential of satellite retrievals to distinguish these mechanisms In our study, we used a multi-filter rotating shadow band radiometer (MFRSR) and micro wave radiometer (MWR) to retrieve the cloud optical depth and cloud droplets effective radius . In particular, we make a statistical study during summer 2013 where water phase clouds dominate and assess the accuracy of both MODIS and GOES satellite cloud products including LWP, COD and Reff. Most importantly, we assess performance against satellite observing geometries. Much like previous studies at the ARM site, we observe significant biases in the effective radius when the solar zenith angle is too large. In addition, we show that biases are also sensitive to the LWP limiting such measurement s in assessing potential aerosol-cloud signatures Finally, we discuss preliminary aerosol-cloud interactions from our ground system where local lidar is used to assess aerosols below clouds and explore the Aerosol Cloud Index.

  16. Cloud retrieval using ship-based spectral transmissivity measurements

    NASA Astrophysics Data System (ADS)

    Brueckner, M.; Macke, A.; Wendisch, M.; Kanitz, T.; Pospichal, B.

    2013-05-01

    Within the scope of the OCEANET-Project (autonomous measurement platforms for energy and material exchange between ocean and atmosphere) on board of the research vessel Polarstern clouds have been investigated over the Atlantic Ocean under different atmospheric conditions and climate zones by active and passive remote sensing. An existing measurement platform, including lidar, microwave radiometer, all sky camera and broadband radiation sensors, has been extended by spectral radiation measurements with the COmpact RAdiation measurements System (CORAS). CORAS measures spectral downward radiances and irradiances in the visible to near-infrared wavelength region. The data were corrected to consider the movements of the ship and with it the misalignment of the sensor plane from earth's horizon. Using observed and modeled spectral transmitted radiances cloud properties such as cloud optical thickness (τ) and effective radius (reff) were retrieved. The vertical cloud structure with limitations for thick clouds is obtained from lidar and microwave radiometer measurements. The all sky camera provides information on the horizontal cloud variability. Cloud optical thickness and effective radius, will be retrieved by using a plane parallel radiative transfer model.

  17. Cloud-property retrieval using merged HIRS and AVHRR data

    NASA Technical Reports Server (NTRS)

    Baum, Bryan A.; Wielicki, Bruce A.; Minnis, Patrick; Parker, Lindsay

    1992-01-01

    A technique is developed that uses a multispectral, multiresolution method to improve the overall retrieval of mid- to high-level cloud properties by combining HIRS sounding channel data with higher spatial resolution AVHRR radiometric data collocated with the HIRS footprint. Cirrus cloud radiative and physical properties are determined using satellite data, surface-based measurements provided by rawinsondes and lidar, and aircraft-based lidar data collected during the First International Satellite Cloud Climatology Program Regional Experiment in Wisconsin during the months of October and November 1986. HIRS cloud-height retrievals are compared to ground-based lidar and aircraft lidar when possible. Retrieved cloud heights are found to have close agreement with lidar for thin cloud, but are higher than lidar for optically thick cloud. The results of the reflectance-emittance relationships derived are compared to theoretical scattering model results for both water-droplet spheres and randomly oriented hexagonal ice crystals. It is found that the assumption of 10-micron water droplets is inadequate to describe the reflectance-emittance relationship for the ice clouds seen here. Use of this assumption would lead to lower cloud heights using the ISCCP approach. The theoretical results show that use of hexagonal ice crystal phase functions could lead to much improved results for cloud retrieval algorithms using a bispectral approach.

  18. FAME-C: cloud property retrieval using synergistic AATSR and MERIS observations

    NASA Astrophysics Data System (ADS)

    Carbajal Henken, C. K.; Lindstrot, R.; Preusker, R.; Fischer, J.

    2014-11-01

    A newly developed daytime cloud property retrieval algorithm, FAME-C (Freie Universität Berlin AATSR MERIS Cloud), is presented. Synergistic observations from the Advanced Along-Track Scanning Radiometer (AATSR) and the Medium Resolution Imaging Spectrometer (MERIS), both mounted on the polar-orbiting Environmental Satellite (Envisat), are used for cloud screening. For cloudy pixels two main steps are carried out in a sequential form. First, a cloud optical and microphysical property retrieval is performed using an AATSR near-infrared and visible channel. Cloud phase, cloud optical thickness, and effective radius are retrieved, and subsequently cloud water path is computed. Second, two cloud top height products are retrieved based on independent techniques. For cloud top temperature, measurements in the AATSR infrared channels are used, while for cloud top pressure, measurements in the MERIS oxygen-A absorption channel are used. Results from the cloud optical and microphysical property retrieval serve as input for the two cloud top height retrievals. Introduced here are the AATSR and MERIS forward models and auxiliary data needed in FAME-C. Also, the optimal estimation method, which provides uncertainty estimates of the retrieved property on a pixel basis, is presented. Within the frame of the European Space Agency (ESA) Climate Change Initiative (CCI) project, the first global cloud property retrievals have been conducted for the years 2007-2009. For this time period, verification efforts are presented, comparing, for four selected regions around the globe, FAME-C cloud optical and microphysical properties to cloud optical and microphysical properties derived from measurements of the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite. The results show a reasonable agreement between the cloud optical and microphysical property retrievals. Biases are generally smallest for marine stratocumulus clouds: -0.28, 0.41 μm and -0.18 g m-2 for cloud optical thickness, effective radius and cloud water path, respectively. This is also true for the root-mean-square deviation. Furthermore, both cloud top height products are compared to cloud top heights derived from ground-based cloud radars located at several Atmospheric Radiation Measurement (ARM) sites. FAME-C mostly shows an underestimation of cloud top heights when compared to radar observations. The lowest bias of -0.3 km is found for AATSR cloud top heights for single-layer clouds, while the highest bias of -3.0 km is found for AATSR cloud top heights for multilayer clouds. Variability is low for MERIS cloud top heights for low-level clouds, and high for MERIS cloud top heights for mid-level and high-level single-layer clouds, as well as for both AATSR and MERIS cloud top heights for multilayer clouds.

  19. Preliminary results of measurements by automated probes Vega 1 and 2 or particle concentration in clouds of Venus at heights 47-63 KM

    NASA Technical Reports Server (NTRS)

    Zhulanov, Y. V.; Mukhin, L. M.; Nenarokov, D. F.

    1986-01-01

    Results of the preliminary processing of the Vega 1 and 2 descender data on the cloud layer structure of the Venusian atmosphere are discussed. A photoelectric counter for aerosol particles is described together with its optical and pneumatic circuits and operation algorithm. Vertical profiles of concentrations of particles with a diameter of 0.4 microns agree quantitatively with the Pioneer-Venus and Venera 9 and 10 data. Concentrations of these particles are: in the B layer, up to 190/cu cm; in the C layer, up to 10/cu cm; and in the D layer, up to 130/cu cm. Layers have sharp boundaries with a significant vertical heterogeneity of the aerosol concentration field inside them.

  20. Investigation of Low Altitude Water Ice Cloud Formation in Mars using a Laboratory Based Cloud Chamber

    NASA Astrophysics Data System (ADS)

    Ladino Moreno, L. A.; Abbatt, J.

    2012-12-01

    The ice nuclei abilities of the two available Martian regolith analogs (the Mojave Mars simulant and Johnson Space Center Mars-1) to form low altitude water ice clouds in the Martian atmosphere were investigated with the help of the University of Toronto continuous flow diffusion chamber (UT-CFDC). Polydisperse aerosol particles (below 1μm) generated using a dry disperser and monodisperse aerosol particles (100 nm and 240 nm) generated with an atomizer were exposed to different supersaturations with respect to ice as a function of temperature. Experiments using 100 nm size selected sulfuric acid particles defined the homogeneous freezing threshold in the chamber. Both simulants were found to be active ice nuclei in the deposition nucleation mode between 223 K and 203 K. The Mojave Mars simulant particles were found to be slightly better ice nuclei than the Johnson Space Center Mars-1 particles since they require lower supersaturations to nucleate ice at the different tested temperatures. It was observed that the critical supersaturation (Scrit) to activate 1 % of the aerosol particles increased with decreasing temperature. It was also found that Scrit decreased when the particle size was increased from 100 nm to 240 nm. The Johnson Space Center Mars-1 analog behaves similarly to the well known terrestrial ice nuclei such as kaolinite and Arizona test dust particles, whereas, the Mojave Mars simulant behaves closer to another clay, montmorillonite. The m parameter values and the contact angles were calculated from the experimental Scrit. Those values follow the literature trends; however, our values are larger than in previous studies perhaps due to the use of submicron aerosol particles and the lower sensitivity of our system for determining the Scrit values. A general finding is that the barrier to ice nucleation becomes larger at lower temperatures. This behaviour is typically neglected in most of the microphysical models since the nucleation rates at this temperature range are assumed as non temperature dependent. This should be re-evaluated based in the literature data and present results.

  1. A storm surge intensity classification based on extreme water level and concomitant wave height

    NASA Astrophysics Data System (ADS)

    Dong, Sheng; Gao, Junguo; Li, Xue; Wei, Yong; Wang, Liang

    2015-04-01

    Storm surge is one of the predominant natural threats to coastal communities. Qingdao is located on the southern coast of the Shandong Peninsula in China. The storm surge disaster in Qingdao depends on various influencing factors such as the intensity, duration, and route of the passing typhoon, and thus a comprehensive understanding of natural coastal hazards is essential. In order to make up the defects of merely using the warning water level, this paper presents two statistical distribution models (Poisson Bi-variable Gumbel Logistic Distribution and Poisson Bi-variable Log-normal Distribution) to classify the intensity of storm surge. We emphasize the joint return period of typhoon-induced water levels and wave heights measured in the coastal area of Qingdao since 1949. The present study establishes a new criterion to classify the intensity grade of catastrophic storms using the typhoon surge estimated by the two models. A case study demonstrates that the new criterion is well defined in terms of probability concept, is easy to implement, and fits well the calculation of storm surge intensity. The procedures with the proposed statistical models would be useful for the disaster mitigation in other coastal areas influenced by typhoons.

  2. Temporal changes in bias of body mass index scores based on self-reported height and weight

    PubMed Central

    Stommel, M; Osier, N

    2013-01-01

    Objectives: To investigate temporal changes in the bias associated with self-reported (as opposed to measured) body mass index (BMI) and explore the relationship of such bias to changing social attitudes towards obesity. Methods: Using data from the National Health and Nutrition Examination Survey covering two time periods, 1988–1994 and 2005–2008, discrepancy scores between self-reported vs measured BMI were generated. Changes in the sensitivity of BMI categories based on self-reports were examined for six weight groups, both for the US adult population as a whole and major demographic groups. Linear regression models were used to examine temporal changes in average bias, as well as attitudes about weight within each weight category and by demographic group. Results: Between 2005–2008 and 1988–1994, the bias towards underestimation of a person's BMI based on interview responses has declined among obese individuals, a trend evident in virtually all demographic subgroups explored. Conversely, most demographic groups showed little change in the extent of bias among underweight and normal-weight individuals. Although the 2005–2008 survey respondents underestimated their measured BMI more than the 1988–1994 respondents, this shift can be entirely explained by the increased prevalence of obesity in more recent years. In fact, obese individuals in 2005–2008 were less likely to overreport their height and underreport their weight than their counterparts in the 1988–1994. Evidence from responses to questions about ideal weight and desire to lose weight point in the direction of a shift in social attitudes, which may make it easier to ‘admit' to greater weight in surveys. Conclusion: Over the past 20 years, the bias in self-reported height and weight has declined leading to more accurate BMI categorizations based on self-report. This change is likely to affect efforts to find correction factors to adjust BMI scores based on self-reported height and weight. PMID:22546777

  3. Post-Adoption Issues Related to Cloud-Based IT Solutions: A Multi-Method Investigation

    ERIC Educational Resources Information Center

    Xiao, Xiao

    2013-01-01

    Due to their low cost of implementation and considerable elasticity, cloud-based IT solutions are being widely adopted or considered in organizations across various industries. However, such IT solutions bring forth several unique challenges--challenges that make it difficult for organizations to achieve successful utilization of cloud-based…

  4. Trust-Enhanced Cloud Service Selection Model Based on QoS Analysis

    PubMed Central

    Pan, Yuchen; Ding, Shuai; Fan, Wenjuan; Li, Jing; Yang, Shanlin

    2015-01-01

    Cloud computing technology plays a very important role in many areas, such as in the construction and development of the smart city. Meanwhile, numerous cloud services appear on the cloud-based platform. Therefore how to how to select trustworthy cloud services remains a significant problem in such platforms, and extensively investigated owing to the ever-growing needs of users. However, trust relationship in social network has not been taken into account in existing methods of cloud service selection and recommendation. In this paper, we propose a cloud service selection model based on the trust-enhanced similarity. Firstly, the direct, indirect, and hybrid trust degrees are measured based on the interaction frequencies among users. Secondly, we estimate the overall similarity by combining the experience usability measured based on Jaccard’s Coefficient and the numerical distance computed by Pearson Correlation Coefficient. Then through using the trust degree to modify the basic similarity, we obtain a trust-enhanced similarity. Finally, we utilize the trust-enhanced similarity to find similar trusted neighbors and predict the missing QoS values as the basis of cloud service selection and recommendation. The experimental results show that our approach is able to obtain optimal results via adjusting parameters and exhibits high effectiveness. The cloud services ranking by our model also have better QoS properties than other methods in the comparison experiments. PMID:26606388

  5. Trust-Enhanced Cloud Service Selection Model Based on QoS Analysis.

    PubMed

    Pan, Yuchen; Ding, Shuai; Fan, Wenjuan; Li, Jing; Yang, Shanlin

    2015-01-01

    Cloud computing technology plays a very important role in many areas, such as in the construction and development of the smart city. Meanwhile, numerous cloud services appear on the cloud-based platform. Therefore how to how to select trustworthy cloud services remains a significant problem in such platforms, and extensively investigated owing to the ever-growing needs of users. However, trust relationship in social network has not been taken into account in existing methods of cloud service selection and recommendation. In this paper, we propose a cloud service selection model based on the trust-enhanced similarity. Firstly, the direct, indirect, and hybrid trust degrees are measured based on the interaction frequencies among users. Secondly, we estimate the overall similarity by combining the experience usability measured based on Jaccard's Coefficient and the numerical distance computed by Pearson Correlation Coefficient. Then through using the trust degree to modify the basic similarity, we obtain a trust-enhanced similarity. Finally, we utilize the trust-enhanced similarity to find similar trusted neighbors and predict the missing QoS values as the basis of cloud service selection and recommendation. The experimental results show that our approach is able to obtain optimal results via adjusting parameters and exhibits high effectiveness. The cloud services ranking by our model also have better QoS properties than other methods in the comparison experiments. PMID:26606388

  6. Correlating Ground-Based Lightning Measurements with Ash Cloud Satellite Data from the 2010 Eruption of Eyjafjallajökull Volcano, Iceland

    NASA Astrophysics Data System (ADS)

    McMahon, N. D.; Thomas, R. J.; Pavolonis, M. J.; Sieglaff, J.; Aster, R. C.

    2012-12-01

    Airborne volcanic ash is a major aviation hazard. For example, the 2010 eruption of Eyjafjallajökull volcano in Iceland resulted in the largest air-traffic shutdown since World War II. More than 100,000 flights were grounded, stranding passengers in Europe and across the globe, and producing a multi-billion dollar economic impact. Because of the high impact on aviation, sophisticated tools are needed to provide real-time alerts, tracking, and forecasting of volcanic clouds. In an attempt address the 5-minute volcanic cloud warning criteria established by the international aviation community, an automated volcanic cloud alert system for the Geostationary Operational Environmental Satellite - R Series (GOES-R) built upon the automated ash cloud alert system for the Advanced Very High Resolution Radiometer (AVHRR) is in development. The new system will be capable of identifying ash and SO2 clouds with greater accuracy. One component of GOES-R will be a lightning mapper. To study the temporal, spatial, and physical relationships between ash clouds and lightning, and the utility of lightning detection in a real-time alert system, we analyze data collected by the Lightning Mapping Array, a ground-based lightning detection network, in conjunction with satellite data gathered by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument aboard Meteosat-9 during in the 2010 eruption of Eyjafjallajökull volcano. We correlate lightning characteristics, intensity, and distribution with plume location, height, mass loading, and effective particle radius. Lightning mapping in volcanic ash clouds potentially will allow for better characterization of the ash cloud and aid in forecasting the distribution of ash and its effects on aviation.

  7. Cloud parallel processing of tandem mass spectrometry based proteomics data.

    PubMed

    Mohammed, Yassene; Mostovenko, Ekaterina; Henneman, Alex A; Marissen, Rob J; Deelder, André M; Palmblad, Magnus

    2012-10-01

    Data analysis in mass spectrometry based proteomics struggles to keep pace with the advances in instrumentation and the increasing rate of data acquisition. Analyzing this data involves multiple steps requiring diverse software, using different algorithms and data formats. Speed and performance of the mass spectral search engines are continuously improving, although not necessarily as needed to face the challenges of acquired big data. Improving and parallelizing the search algorithms is one possibility; data decomposition presents another, simpler strategy for introducing parallelism. We describe a general method for parallelizing identification of tandem mass spectra using data decomposition that keeps the search engine intact and wraps the parallelization around it. We introduce two algorithms for decomposing mzXML files and recomposing resulting pepXML files. This makes the approach applicable to different search engines, including those relying on sequence databases and those searching spectral libraries. We use cloud computing to deliver the computational power and scientific workflow engines to interface and automate the different processing steps. We show how to leverage these technologies to achieve faster data analysis in proteomics and present three scientific workflows for parallel database as well as spectral library search using our data decomposition programs, X!Tandem and SpectraST. PMID:22916831

  8. Extraction of Profile Information from Cloud Contaminated Radiances. Appendixes 2

    NASA Technical Reports Server (NTRS)

    Smith, W. L.; Zhou, D. K.; Huang, H.-L.; Li, Jun; Liu, X.; Larar, A. M.

    2003-01-01

    Clouds act to reduce the signal level and may produce noise dependence on the complexity of the cloud properties and the manner in which they are treated in the profile retrieval process. There are essentially three ways to extract profile information from cloud contaminated radiances: (1) cloud-clearing using spatially adjacent cloud contaminated radiance measurements, (2) retrieval based upon the assumption of opaque cloud conditions, and (3) retrieval or radiance assimilation using a physically correct cloud radiative transfer model which accounts for the absorption and scattering of the radiance observed. Cloud clearing extracts the radiance arising from the clear air portion of partly clouded fields of view permitting soundings to the surface or the assimilation of radiances as in the clear field of view case. However, the accuracy of the clear air radiance signal depends upon the cloud height and optical property uniformity across the two fields of view used in the cloud clearing process. The assumption of opaque clouds within the field of view permits relatively accurate profiles to be retrieved down to near cloud top levels, the accuracy near the cloud top level being dependent upon the actual microphysical properties of the cloud. The use of a physically correct cloud radiative transfer model enables accurate retrievals down to cloud top levels and below semi-transparent cloud layers (e.g., cirrus). It should also be possible to assimilate cloudy radiances directly into the model given a physically correct cloud radiative transfer model using geometric and microphysical cloud parameters retrieved from the radiance spectra as initial cloud variables in the radiance assimilation process. This presentation reviews the above three ways to extract profile information from cloud contaminated radiances. NPOESS Airborne Sounder Testbed-Interferometer radiance spectra and Aqua satellite AIRS radiance spectra are used to illustrate how cloudy radiances can be used in the profile retrieval process.

  9. Cloud and aerosol optics by polarized micro pulse Lidar and ground based measurements of zenith radiance

    NASA Astrophysics Data System (ADS)

    Delgadillo, Rodrigo

    Clouds impact Earth's climate through cloud transmission and reflection properties. Clouds reflect approximately 15 percent of the incoming solar radiation at the top of the atmosphere. A key cloud radiative variable is cloud optical depth, which gives information about how much light is transmitted through a cloud. Historically, remote measurements of cloud optical depth have been limited to uniform overcast conditions and had low temporal and spatial resolution. We present a novel method to measure cloud optical depth for coastal regions from spectral zenith radiance measurements for optically thin clouds, which removes some of these limitations. Our measurement site is part of South Florida's Cloud-Aerosol-Rain Observatory (CAROb), located on Virginia Key, FL (6 km from Miami). This work is based on Marshak et al.'s method for finding cloud optical depth from vegetative sites that provide a strong spectral contrast between red and near infrared surface albedo. However, given the unique nature of our site, which contains water, vegetation, beach, and urban surface types, we found no such spectral contrast at those wavelength pairs. We measured albedo, with hyperspectral resolution, for different surface types around our measurement site to estimate the effective spectral albedo for the area centered on the site with a 5km radius. From this analysis, we found the best possible albedo contrast (573.9 and 673.1 nm) for our site. We tested the derived cloud optical depth from zenith radiance at these two wavelengths against a concurrently running polarized micro pulse LIDAR (MPL) and found good agreement.

  10. Cloud layer thicknesses from a combination of surface and upper-air observations

    NASA Technical Reports Server (NTRS)

    Poore, Kirk D.; Wang, Junhong; Rossow, William B.

    1995-01-01

    Cloud layer thicknesses are derived from base and top altitudes by combining 14 years (1975-1988) of surface and upper-air observations at 63 sites in the Northern Hemisphere. Rawinsonde observations are employed to determine the locations of cloud-layer top and base by testing for dewpoint temperature depressions below some threshold value. Surface observations serve as quality checks on the rawinsonde-determined cloud properties and provide cloud amount and cloud-type information. The dataset provides layer-cloud amount, cloud type, high, middle, or low height classes, cloud-top heights, base heights and layer thicknesses, covering a range of latitudes from 0 deg to 80 deg N. All data comes from land sites: 34 are located in continental interiors, 14 are near coasts, and 15 are on islands. The uncertainties in the derived cloud properties are discussed. For clouds classified by low-, mid-, and high-top altitudes, there are strong latitudinal and seasonal variations in the layer thickness only for high clouds. High-cloud layer thickness increases with latitude and exhibits different seasonal variations in different latitude zones: in summer, high-cloud layer thickness is a maximum in the Tropics but a minimum at high latitudes. For clouds classified into three types by base altitude or into six standard morphological types, latitudinal and seasonal variations in layer thickness are very small. The thickness of the clear surface layer decreases with latitude and reaches a summer minimum in the Tropics and summer maximum at higher latitudes over land, but does not vary much over the ocean. Tropical clouds occur in three base-altitude groups and the layer thickness of each group increases linearly with top altitude. Extratropical clouds exhibit two groups, one with layer thickness proportional to their cloud-top altitude and one with small (less than or equal to 1000 m) layer thickness independent of cloud-top altitude.

  11. Prediction Based Design of Fire Detection for Buildings with Ceiling Heights between 9m and 18m

    NASA Technical Reports Server (NTRS)

    Davis, W. D.; Notarianni, K. A.

    1998-01-01

    The purpose of this paper is to provide the experimental and theoretical background necessary to extend guidelines to ceiling heights between 9 m and 18 m. Based on the results of experiments conducted in 15 m and 22 m high hangars, detector activation thresholds and detector spacing are analyzed for both smoke and heat detectors. Only ceiling mounted detection devices are analyzed in this paper. In addition to the detector threshold study, the predictive capabilities of computer fire model simulations were compared with experimental results. This comparison, which is based on 12 fire tests, resulted in the development of a new ceiling jet algorithm to model phenomena which had not been included in previous algorithms. The improved algorithm provides a better representation of the development of the ceiling jet temperature to a growing hot layer and a better estimation of plume centerline temperature. Guidelines are examined, based on the experimental results, for fire detector spacing, placement, and sensitivity. Recommendations concerning the use of computer fire models at these heights are made as a function of fire size and hot layer development. The role of draft curtains is discussed and their impact on detector activation is demonstrated.

  12. 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.

  13. The Cloud Detection and Ultraviolet Monitoring Experiment (CLUE)

    NASA Technical Reports Server (NTRS)

    Barbier, Louis M.; Loh, Eugene C.; Krizmanic, John F.; Sokolsky, Pierre; Streitmatter, Robert E.

    2004-01-01

    In this paper we describe a new balloon instrument - CLUE - which is designed to monitor ultraviolet (uv) nightglow levels and determine cloud cover and cloud heights with a CO2 slicing technique. The CO2 slicing technique is based on the MODIS instrument on NASA's Aqua and Terra spacecraft. CLUE will provide higher spatial resolution (0.5 km) and correlations between the uv and the cloud cover.

  14. Facial plastic surgery area acquisition method based on point cloud mathematical model solution.

    PubMed

    Li, Xuwu; Liu, Fei

    2013-09-01

    It is one of the hot research problems nowadays to find a quick and accurate method of acquiring the facial plastic surgery area to provide sufficient but irredundant autologous or in vitro skin source for covering extensive wound, trauma, and burnt area. At present, the acquisition of facial plastic surgery area mainly includes model laser scanning, point cloud data acquisition, pretreatment of point cloud data, three-dimensional model reconstruction, and computation of area. By using this method, the area can be computed accurately, but it is hard to control the random error, and it requires a comparatively longer computation period. In this article, a facial plastic surgery area acquisition method based on point cloud mathematical model solution is proposed. This method applies symmetric treatment to the point cloud based on the pretreatment of point cloud data, through which the comparison diagram color difference map of point cloud error before and after symmetry is obtained. The slicing mathematical model of facial plastic area is got through color difference map diagram. By solving the point cloud data in this area directly, the facial plastic area is acquired. The point cloud data are directly operated in this method, which can accurately and efficiently complete the surgery area computation. The result of the comparative analysis shows the method is effective in facial plastic surgery area. PMID:24036743

  15. A Novel Cost Based Model for Energy Consumption in Cloud Computing

    PubMed Central

    Horri, A.; Dastghaibyfard, Gh.

    2015-01-01

    Cloud data centers consume enormous amounts of electrical energy. To support green cloud computing, providers also need to minimize cloud infrastructure energy consumption while conducting the QoS. In this study, for cloud environments an energy consumption model is proposed for time-shared policy in virtualization layer. The cost and energy usage of time-shared policy were modeled in the CloudSim simulator based upon the results obtained from the real system and then proposed model was evaluated by different scenarios. In the proposed model, the cache interference costs were considered. These costs were based upon the size of data. The proposed model was implemented in the CloudSim simulator and the related simulation results indicate that the energy consumption may be considerable and that it can vary with different parameters such as the quantum parameter, data size, and the number of VMs on a host. Measured results validate the model and demonstrate that there is a tradeoff between energy consumption and QoS in the cloud environment. Also, measured results validate the model and demonstrate that there is a tradeoff between energy consumption and QoS in the cloud environment. PMID:25705716

  16. A shape-based segmentation method for mobile laser scanning point clouds

    NASA Astrophysics Data System (ADS)

    Yang, Bisheng; Dong, Zhen

    2013-07-01

    Segmentation of mobile laser point clouds of urban scenes into objects is an important step for post-processing (e.g., interpretation) of point clouds. Point clouds of urban scenes contain numerous objects with significant size variability, complex and incomplete structures, and holes or variable point densities, raising great challenges for the segmentation of mobile laser point clouds. This paper addresses these challenges by proposing a shape-based segmentation method. The proposed method first calculates the optimal neighborhood size of each point to derive the geometric features associated with it, and then classifies the point clouds according to geometric features using support vector machines (SVMs). Second, a set of rules are defined to segment the classified point clouds, and a similarity criterion for segments is proposed to overcome over-segmentation. Finally, the segmentation output is merged based on topological connectivity into a meaningful geometrical abstraction. The proposed method has been tested on point clouds of two urban scenes obtained by different mobile laser scanners. The results show that the proposed method segments large-scale mobile laser point clouds with good accuracy and computationally effective time cost, and that it segments pole-like objects particularly well.

  17. A novel cost based model for energy consumption in cloud computing.

    PubMed

    Horri, A; Dastghaibyfard, Gh

    2015-01-01

    Cloud data centers consume enormous amounts of electrical energy. To support green cloud computing, providers also need to minimize cloud infrastructure energy consumption while conducting the QoS. In this study, for cloud environments an energy consumption model is proposed for time-shared policy in virtualization layer. The cost and energy usage of time-shared policy were modeled in the CloudSim simulator based upon the results obtained from the real system and then proposed model was evaluated by different scenarios. In the proposed model, the cache interference costs were considered. These costs were based upon the size of data. The proposed model was implemented in the CloudSim simulator and the related simulation results indicate that the energy consumption may be considerable and that it can vary with different parameters such as the quantum parameter, data size, and the number of VMs on a host. Measured results validate the model and demonstrate that there is a tradeoff between energy consumption and QoS in the cloud environment. Also, measured results validate the model and demonstrate that there is a tradeoff between energy consumption and QoS in the cloud environment. PMID:25705716

  18. Effect of Clouds on Apertures of Space-based Air Fluorescence Detectors

    NASA Technical Reports Server (NTRS)

    Sokolsky, P.; Krizmanic, J.

    2003-01-01

    Space-based ultra-high-energy cosmic ray detectors observe fluorescence light from extensive air showers produced by these particles in the troposphere. Clouds can scatter and absorb this light and produce systematic errors in energy determination and spectrum normalization. We study the possibility of using IR remote sensing data from MODIS and GOES satellites to delimit clear areas of the atmosphere. The efficiency for detecting ultra-high-energy cosmic rays whose showers do not intersect clouds is determined for real, night-time cloud scenes. We use the MODIS SST cloud mask product to define clear pixels for cloud scenes along the equator and use the OWL Monte Carlo to generate showers in the cloud scenes. We find the efficiency for cloud-free showers with closest approach of three pixels to a cloudy pixel is 6.5% exclusive of other factors. We conclude that defining a totally cloud-free aperture reduces the sensitivity of space-based fluorescence detectors to unacceptably small levels.

  19. Prediction Based Proactive Thermal Virtual Machine Scheduling in Green Clouds

    PubMed Central

    Kinger, Supriya; Kumar, Rajesh; Sharma, Anju

    2014-01-01

    Cloud computing has rapidly emerged as a widely accepted computing paradigm, but the research on Cloud computing is still at an early stage. Cloud computing provides many advanced features but it still has some shortcomings such as relatively high operating cost and environmental hazards like increasing carbon footprints. These hazards can be reduced up to some extent by efficient scheduling of Cloud resources. Working temperature on which a machine is currently running can be taken as a criterion for Virtual Machine (VM) scheduling. This paper proposes a new proactive technique that considers current and maximum threshold temperature of Server Machines (SMs) before making scheduling decisions with the help of a temperature predictor, so that maximum temperature is never reached. Different workload scenarios have been taken into consideration. The results obtained show that the proposed system is better than existing systems of VM scheduling, which does not consider current temperature of nodes before making scheduling decisions. Thus, a reduction in need of cooling systems for a Cloud environment has been obtained and validated. PMID:24737962

  20. Prediction based proactive thermal virtual machine scheduling in green clouds.

    PubMed

    Kinger, Supriya; Kumar, Rajesh; Sharma, Anju

    2014-01-01

    Cloud computing has rapidly emerged as a widely accepted computing paradigm, but the research on Cloud computing is still at an early stage. Cloud computing provides many advanced features but it still has some shortcomings such as relatively high operating cost and environmental hazards like increasing carbon footprints. These hazards can be reduced up to some extent by efficient scheduling of Cloud resources. Working temperature on which a machine is currently running can be taken as a criterion for Virtual Machine (VM) scheduling. This paper proposes a new proactive technique that considers current and maximum threshold temperature of Server Machines (SMs) before making scheduling decisions with the help of a temperature predictor, so that maximum temperature is never reached. Different workload scenarios have been taken into consideration. The results obtained show that the proposed system is better than existing systems of VM scheduling, which does not consider current temperature of nodes before making scheduling decisions. Thus, a reduction in need of cooling systems for a Cloud environment has been obtained and validated. PMID:24737962

  1. Vertical Structure of Ice Cloud Layers From CloudSat and CALIPSO Measurements and Comparison to NICAM Simulations

    NASA Technical Reports Server (NTRS)

    Ham, Seung-Hee; Sohn, Byung-Ju; Kato, Seiji; Satoh, Masaki

    2013-01-01

    The shape of the vertical profile of ice cloud layers is examined using 4 months of CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) global measurements taken on January, April, July, and October 2007. Ice clouds are selected using temperature profiles when the cloud base is located above the 253K temperature level. The obtained ice water content (IWC), effective radius, or extinction coefficient profiles are normalized by their layer mean values and are expressed in the normalized vertical coordinate, which is defined as 0 and 1 at the cloud base and top heights, respectively. Both CloudSat and CALIPSO observations show that the maximum in the IWC and extinction profiles shifts toward the cloud bottom, as the cloud depth increases. In addition, clouds with a base reaching the surface in a high-latitude region show that the maximum peak of the IWC and extinction profiles occurs near the surface, which is presumably due to snow precipitation. CloudSat measurements show that the seasonal difference in normalized cloud vertical profiles is not significant, whereas the normalized cloud vertical profile significantly varies depending on the cloud type and the presence of precipitation. It is further examined if the 7 day Nonhydrostatic Icosahedral Atmospheric Model (NICAM) simulation results from 25 December 2006 to 1 January 2007 generate similar cloud profile shapes. NICAM IWC profiles also show maximum peaks near the cloud bottom for thick cloud layers and maximum peaks at the cloud bottom for low-level clouds near the surface. It is inferred that oversized snow particles in the NICAM cloud scheme produce a more vertically inhomogeneous IWC profile than observations due to quick sedimentation.

  2. Diagnosing causes of cloud parameterization deficiencies using ARM measurements over SGP site

    SciTech Connect

    Wu, W.; Liu, Y.; Betts, A. K.

    2010-03-15

    Decade-long continuous surface-based measurements at Great Southern Plains (SGP) collected by the US Department of Energy’s Atmospheric Radiation Measurement (ARM) Climate Research Facility are first used to evaluate the three major reanalyses (i.e., ERA-Interim, NCEP/NCAR Reanalysis I and NCEP/DOE Reanalysis II) to identify model biases in simulating surface shortwave cloud forcing and total cloud fraction. The results show large systematic lower biases in the modeled surface shortwave cloud forcing and cloud fraction from all the three reanalysis datasets. Then we focus on diagnosing the causes of these model biases using the Active Remote Sensing of Clouds (ARSCL) products (e.g., vertical distribution of cloud fraction, cloud-base and cloud-top heights, and cloud optical depth) and meteorological measurements (temperature, humidity and stability). Efforts are made to couple cloud properties with boundary processes in the diagnosis.

  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. 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.

  5. Ground-based remote sensing of thin clouds in the Arctic

    NASA Astrophysics Data System (ADS)

    Garrett, T. J.; Zhao, C.

    2012-11-01

    This paper describes a method for using interferometer measurements of downwelling thermal radiation to retrieve the properties of single-layer clouds. Cloud phase is determined from ratios of thermal emission in three "micro-windows" where absorption by water vapor is particularly small. Cloud microphysical and optical properties are retrieved from thermal emission in two micro-windows, constrained by the transmission through clouds of stratospheric ozone emission. Assuming a cloud does not approximate a blackbody, the estimated 95% confidence retrieval errors in effective radius, visible optical depth, number concentration, and water path are, respectively, 10%, 20%, 38% (55% for ice crystals), and 16%. Applied to data from the Atmospheric Radiation Measurement program (ARM) North Slope of Alaska - Adjacent Arctic Ocean (NSA-AAO) site near Barrow, Alaska, retrievals show general agreement with ground-based microwave radiometer measurements of liquid water path. Compared to other retrieval methods, advantages of this technique include its ability to characterize thin clouds year round, that water vapor is not a primary source of retrieval error, and that the retrievals of microphysical properties are only weakly sensitive to retrieved cloud phase. The primary limitation is the inapplicability to thicker clouds that radiate as blackbodies.

  6. Buildings and Terrain of Urban Area Point Cloud Segmentation based on PCL

    NASA Astrophysics Data System (ADS)

    Liu, Ying; Zhong, Ruofei

    2014-03-01

    One current problem with laser radar point data classification is building and urban terrain segmentation, this paper proposes a point cloud segmentation method base on PCL libraries. PCL is a large cross-platform open source C++ programming library, which implements a large number of point cloud related efficient data structures and generic algorithms involving point cloud retrieval, filtering, segmentation, registration, feature extraction and curved surface reconstruction, visualization, etc. Due to laser radar point cloud characteristics with large amount of data, unsymmetrical distribution, this paper proposes using the data structure of kd-tree to organize data; then using Voxel Grid filter for point cloud resampling, namely to reduce the amount of point cloud data, and at the same time keep the point cloud shape characteristic; use PCL Segmentation Module, we use a Euclidean Cluster Extraction class with Europe clustering for buildings and ground three-dimensional point cloud segmentation. The experimental results show that this method avoids the multiple copy system existing data needs, saves the program storage space through the call of PCL library method and class, shortens the program compiled time and improves the running speed of the program.

  7. CALIOP-derived Smoke Plume Injection Height

    NASA Astrophysics Data System (ADS)

    Soja, A. J.; Winker, D. M.; Choi, H. D.; Fairlie, T. D.; Westberg, D. J.; Roller, C. M.; Pouliot, G.; Vaughan, M.; Pierce, T. E.; Trepte, C. R.; Rao, V.

    2014-12-01

    Biomass burning is a dominant natural and anthropogenic disturbance that feeds back to the climate system. Fire regimes, ecosystem fuels, fire severity and intensity vary widely, even within the same system, largely under the control of weather and climate. These strongly influence fire plume injection height and thus the transport of related biomass burning emissions, affecting air quality, human health and the climate system. If our knowledge of plume injection height is incorrect, transport models of those emissions will likewise be incorrect, adversely affecting our ability to analyze and predict climate feedbacks (i.e. black carbon to the Arctic, precipitation, cloud-radiation relationships) and public health (air quality forecast). Historically, plume height was based on the pioneering work of G.A. Briggs [1969; 1971] and verified with limited field campaigns. However, we currently have two satellite instruments, Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) onboard CALIPSO (afternoon overpass) and Multi-angle Imaging SpectroRadiometer (MISR) onboard TERRA (morning overpass), that can provide the statistics necessary to verify our assumptions and improve fire plume injection height estimates for use in both small- and large-scale models. We have developed a methodology to assess fire plume injection height using the Langley Trajectory Model (LaTM), CALIOP, Hazard Mapping System (HMS) smoke plume, and MODerate Resolution Imaging Spectrometer (MODIS) thermal anomaly data that is capable of generating two distinct types of verification data. A single CALIOP smoke-filled aerosol envelop can be traced back to numerous fire events, and using multiple CALIOP transects from numerous days, a daily smoke plume injection height evolution from a single fire can be defined. Additionally, we have linked the smoke plumes to ecosystems and the meteorological variables that define fire weather. In concert, CALIOP and MISR data can produce the statistical knowledge necessary to improve our understanding of the dynamics of fire plume injection height, thus improving our ability to forecast poor air quality and to accurately define smoke feedbacks to climate change.

  8. A new NASA/MSFC mission analysis global cloud cover data base

    NASA Technical Reports Server (NTRS)

    Brown, S. C.; Jeffries, W. R., III

    1985-01-01

    A global cloud cover data set, derived from the USAF 3D NEPH Analysis, was developed for use in climate studies and for Earth viewing applications. This data set contains a single parameter - total sky cover - separated in time by 3 or 6 hr intervals and in space by approximately 50 n.mi. Cloud cover amount is recorded for each grid point (of a square grid) by a single alphanumeric character representing each 5 percent increment of sky cover. The data are arranged in both quarterly and monthly formats. The data base currently provides daily, 3-hr observed total sky cover for the Northern Hemisphere from 1972 through 1977 less 1976. For the Southern Hemisphere, there are data at 6-hr intervals for 1976 through 1978 and at 3-hr intervals for 1979 and 1980. More years of data are being added. To validate the data base, the percent frequency of or = 0.3 and or = 0.8 cloud cover was compared with ground observed cloud amounts at several locations with generally good agreement. Mean or other desired cloud amounts can be calculated for any time period and any size area from a single grid point to a hemisphere. The data base is especially useful in evaluating the consequence of cloud cover on Earth viewing space missions. The temporal and spatial frequency of the data allow simulations that closely approximate any projected viewing mission. No adjustments are required to account for cloud continuity.

  9. Ground-based remote sensing scheme for monitoring aerosol-cloud interactions

    NASA Astrophysics Data System (ADS)

    Sarna, Karolina; Russchenberg, Herman W. J.

    2016-03-01

    A new method for continuous observation of aerosol-cloud interactions with ground-based remote sensing instruments is presented. The main goal of this method is to enable the monitoring of the change of the cloud droplet size due to the change in the aerosol concentration. We use high-resolution measurements from a lidar, a radar and a radiometer, which allow us to collect and compare data continuously. This method is based on a standardised data format from Cloudnet and can be implemented at any observatory where the Cloudnet data set is available. Two example case studies were chosen from the Atmospheric Radiation Measurement (ARM) Program deployment on Graciosa Island, Azores, Portugal, in 2009 to present the method. We use the cloud droplet effective radius (re) to represent cloud microphysical properties and an integrated value of the attenuated backscatter coefficient (ATB) below the cloud to represent the aerosol concentration. All data from each case study are divided into bins of the liquid water path (LWP), each 10 g m-2 wide. For every LWP bin we present the correlation coefficient between ln re and ln ATB, as well as ACIr (defined as ACIr = -d ln re/d ln ATB, change in cloud droplet effective radius with aerosol concentration). Obtained values of ACIr are in the range 0.01-0.1. We show that ground-based remote sensing instruments used in synergy can efficiently and continuously monitor aerosol-cloud interactions.

  10. Move It or Lose It: Cloud-Based Data Storage

    ERIC Educational Resources Information Center

    Waters, John K.

    2010-01-01

    There was a time when school districts showed little interest in storing or backing up their data to remote servers. Nothing seemed less secure than handing off data to someone else. But in the last few years the buzz around cloud storage has grown louder, and the idea that data backup could be provided as a service has begun to gain traction in

  11. Move It or Lose It: Cloud-Based Data Storage

    ERIC Educational Resources Information Center

    Waters, John K.

    2010-01-01

    There was a time when school districts showed little interest in storing or backing up their data to remote servers. Nothing seemed less secure than handing off data to someone else. But in the last few years the buzz around cloud storage has grown louder, and the idea that data backup could be provided as a service has begun to gain traction in…

  12. An Elliptic Curve Based Schnorr Cloud Security Model in Distributed Environment.

    PubMed

    Muthurajan, Vinothkumar; Narayanasamy, Balaji

    2016-01-01

    Cloud computing requires the security upgrade in data transmission approaches. In general, key-based encryption/decryption (symmetric and asymmetric) mechanisms ensure the secure data transfer between the devices. The symmetric key mechanisms (pseudorandom function) provide minimum protection level compared to asymmetric key (RSA, AES, and ECC) schemes. The presence of expired content and the irrelevant resources cause unauthorized data access adversely. This paper investigates how the integrity and secure data transfer are improved based on the Elliptic Curve based Schnorr scheme. This paper proposes a virtual machine based cloud model with Hybrid Cloud Security Algorithm (HCSA) to remove the expired content. The HCSA-based auditing improves the malicious activity prediction during the data transfer. The duplication in the cloud server degrades the performance of EC-Schnorr based encryption schemes. This paper utilizes the blooming filter concept to avoid the cloud server duplication. The combination of EC-Schnorr and blooming filter efficiently improves the security performance. The comparative analysis between proposed HCSA and the existing Distributed Hash Table (DHT) regarding execution time, computational overhead, and auditing time with auditing requests and servers confirms the effectiveness of HCSA in the cloud security model creation. PMID:26981584

  13. An Elliptic Curve Based Schnorr Cloud Security Model in Distributed Environment

    PubMed Central

    Muthurajan, Vinothkumar; Narayanasamy, Balaji

    2016-01-01

    Cloud computing requires the security upgrade in data transmission approaches. In general, key-based encryption/decryption (symmetric and asymmetric) mechanisms ensure the secure data transfer between the devices. The symmetric key mechanisms (pseudorandom function) provide minimum protection level compared to asymmetric key (RSA, AES, and ECC) schemes. The presence of expired content and the irrelevant resources cause unauthorized data access adversely. This paper investigates how the integrity and secure data transfer are improved based on the Elliptic Curve based Schnorr scheme. This paper proposes a virtual machine based cloud model with Hybrid Cloud Security Algorithm (HCSA) to remove the expired content. The HCSA-based auditing improves the malicious activity prediction during the data transfer. The duplication in the cloud server degrades the performance of EC-Schnorr based encryption schemes. This paper utilizes the blooming filter concept to avoid the cloud server duplication. The combination of EC-Schnorr and blooming filter efficiently improves the security performance. The comparative analysis between proposed HCSA and the existing Distributed Hash Table (DHT) regarding execution time, computational overhead, and auditing time with auditing requests and servers confirms the effectiveness of HCSA in the cloud security model creation. PMID:26981584

  14. Integration of cloud-based storage in BES III computing environment

    NASA Astrophysics Data System (ADS)

    Wang, L.; Hernandez, F.; Deng, Z.

    2014-06-01

    We present an on-going work that aims to evaluate the suitability of cloud-based storage as a supplement to the Lustre file system for storing experimental data for the BES III physics experiment and as a backend for storing files belonging to individual members of the collaboration. In particular, we discuss our findings regarding the support of cloud-based storage in the software stack of the experiment. We report on our development work that improves the support of CERN' s ROOT data analysis framework and allows efficient remote access to data through several cloud storage protocols. We also present our efforts providing the experiment with efficient command line tools for navigating and interacting with cloud storage-based data repositories both from interactive sessions and grid jobs.

  15. Towards a quantification of ocean wave heights off the west coast of Ireland using land based seismic data

    NASA Astrophysics Data System (ADS)

    Donne, S.; Bean, C. J.; Lokmer, I.; Lambkin, K.; Creamer, C.

    2012-12-01

    Ocean gravity waves are driven by atmospheric pressure systems. Their interactions with one another and reflection off coastlines generate pressure changes at the sea floor. These pressure fluctuations are the cause of continuous background seismic noise known as microseisms. The levels of microseism activity vary as a function of the sea state and increase during periods of intensive ocean wave activity. In 2011 a seismic network was deployed along the west coast of Ireland to continuously record microseisms generated in the Atlantic Ocean, as part of the Wave Observation (WaveObs) project based in University College Dublin. This project aims to determine the characteristics of the causative ocean gravity waves through calibration of the microseism data with ocean buoy data. In initial tests we are using a Backpropagation Feed-forward Artificial Neural Network (BP ANN) to establish the underlying relationships between microseisms and ocean waves. ANNs were originally inspired by studies of the mammalian brain and nervous system and are designed to learn by example. If successful these tools could then be used to estimate ocean wave heights and wave periods using a land-based seismic network and complement current wave observations being made offshore by marine buoys. Preliminary ANN results are promising with the network successfully able to reconstruct trends in ocean wave heights and periods. Microseisms can provide significant information about oceanic processes. With a deeper understanding of how these processes work there is potential for 1) locating and tracking the evolution of the largest waves in the Atlantic and 2) reconstructing the wave climate off the west coast of Ireland using legacy seismic data on a longer time scale than is currently available using marine based observations.

  16. Modeling Jupiter's Cloud Decks And Bands

    NASA Astrophysics Data System (ADS)

    Zuchowski, Lena C.; Read, P. L.; Yamazaki, H.

    2007-10-01

    A simple Jovian cloud model based on an existing version for Venus and Mars has been developed for the Oxford Planetary Unified model System (OPUS), a sophisticated GCM solving the extended hydrodynamic primitive equations. NH3-ice, NH4SH, H2O-ice and H2O-liquid are supposed to form the major cloud decks on Jupiter. These four species have been modeled by OPUS. We obtained NH3-ice clouds at realistic heights and with the expected structure of high, dense clouds in zones as well as almost cloud free belts. The two water clouds formed deeper in the atmosphere below 4 bar and showed maximum cloud content in the South temperate belt area. The newly developed simple OPUS cloud scheme was therefore able to represent Jupiter's cloud structure reasonably realistic. OPUS operates a Newtonian forcing scheme for temperature and the zonal momentum components. A sensitivity study was conducted examining the effects of different thermal and momentum forcing constants on the atmospheric configurations and cloud decks obtained. It could be seen that thermal forcing induces upwelling in zones with strength proportional to the radiative time constant. Weak thermal forcing produced cloud decks of uniform heights and lesser density contrasts between belts and zones. A reversed pattern of upwelling maxima could be induced by strong momentum forcing in the three bottom layers of the model. Based on the passive cloud scheme a Jovian moist convection mixing scheme is currently developed for OPUS. The convection parametrization uses a heat engine framework and is envisioned to further improve the realism of the model.

  17. Global distribution of total cloud cover and cloud type amounts over the ocean

    SciTech Connect

    Warren, S.G.; Hahn, C.J.; London, J.; Chervin, R.M.; Jenne, R.L. . Dept. of Atmospheric Sciences; Colorado Univ., Boulder, CO . Cooperative Inst. for Research in Environmental Sciences; Colorado Univ., Boulder, CO . Dept. of Astrophysical, Planetary, and Atmospheric Sciences; National Center for Atmospheric Research, Boulder, CO )

    1988-12-01

    This is the fourth of a series of atlases to result from a study of the global cloud distribution from ground-based observations. The first two atlases (NCAR/TN-201+STR and NCAR/TN-241+STR) described the frequency of occurrence of each cloud type and the co-occurrence of different types, but included no information about cloud amounts. The third atlas (NCAR/TN-273+STR) described, for the land areas of the earth, the average total cloud cover and the amounts of each cloud type, and their geographical, diurnal, seasonal, and interannual variations, as well as the average base heights of the low clouds. The present atlas does the same for the ocean areas of the earth.

  18. 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

  19. 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

  20. Retrieval of Aerosol Height with TROPOMI

    NASA Astrophysics Data System (ADS)

    Sanders, A. F. J.; de Haan, J. F.; Veefkind, J. P.

    2012-04-01

    The Tropospheric Monitoring Instrument (TROPOMI), to be launched in 2015, will feature a new aerosol product providing the height of aerosol layers. Aerosol Layer Height will be one of two aerosol products, the other one being the Absorbing Aerosol Index. TROPOMI is a UV-VIS-NIR imaging spectrometer with daily global coverage. It will be part of ESA's Sentinel-5 Precursor mission. Algorithm development for the aerosol height product is currently underway at KNMI. In this presentation we will introduce the algorithm, highlight some of the development issues and discuss possible applications and example aerosol cases. Aerosol height observations from the near-infrared wavelength range will improve retrieval of other aerosol properties, particularly retrieval of absorption optical thickness. An increase in absorption in the ultraviolet wavelength range can be due to a higher imaginary part of the refractive index or to the aerosol layer being at a higher altitude. Independent height observations will therefore further constrain retrieval of the single scattering albedo. Furthermore, aerosol profile information is an important parameter when estimating radiative forcings and climate impacts of aerosol, it is a significant source of uncertainty in trace gas retrieval and it helps in understanding atmospheric transport mechanisms. Finally, timely available, global observations of aerosol height will be of interest to aviation safety agencies. The retrieval algorithm for aerosol height will be based on absorption by oxygen in the A-band (759-770 nm). Aerosols are assumed to be contained in a single layer. A spectral fit of reflectance (resolution 0.5 nm) across the absorption band provides layer height. The retrieval method will be optimal estimation to ensure a proper error analysis. Sensitivity studies have indicated that accuracy and precision of retrieved height for cloud-free scenes will be well below the TROPOMI science requirements (1 km). They have also shown that retrieval is robust against inaccurate knowledge of the single scattering albedo and that precise knowledge of the phase function or the surface albedo is not needed.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  2. Improved cloud parameterization for Arctic climate simulations based on satellite data

    NASA Astrophysics Data System (ADS)

    Klaus, Daniel; Dethloff, Klaus; Dorn, Wolfgang; Rinke, Annette

    2015-04-01

    The defective representation of Arctic cloud processes and properties remains a crucial problem in climate modelling and in reanalysis products. Satellite-based cloud observations (MODIS and CPR/CALIOP) and single-column model simulations (HIRHAM5-SCM) were exploited to evaluate and improve the simulated Arctic cloud cover of the atmospheric regional climate model HIRHAM5. The ECMWF reanalysis dataset 'ERA-Interim' (ERAint) was used for the model initialization, the lateral boundary forcing as well as the dynamical relaxation inside the pan-Arctic domain. HIRHAM5 has a horizontal resolution of 0.25° and uses 40 pressure-based and terrain-following vertical levels. In comparison with the satellite observations, the HIRHAM5 control run (HH5ctrl) systematically overestimates total cloud cover, but to a lesser extent than ERAint. The underestimation of high- and mid-level clouds is strongly outweighed by the overestimation of low-level clouds. Numerous sensitivity studies with HIRHAM5-SCM suggest (1) the parameter tuning, enabling a more efficient Bergeron-Findeisen process, combined with (2) an extension of the prognostic-statistical (PS) cloud scheme, enabling the use of negatively skewed beta distributions. This improved model setup was then used in a corresponding HIRHAM5 sensitivity run (HH5sens). While the simulated high- and mid-level cloud cover is improved only to a limited extent, the large overestimation of low-level clouds can be systematically and significantly reduced, especially over sea ice. Consequently, the multi-year annual mean area average of total cloud cover with respect to sea ice is almost 14% lower than in HH5ctrl. Overall, HH5sens slightly underestimates the observed total cloud cover but shows a halved multi-year annual mean bias of 2.2% relative to CPR/CALIOP at all latitudes north of 60° N. Importantly, HH5sens produces a more realistic ratio between the cloud water and ice content. The considerably improved cloud simulation manifests in a more correct radiative transfer and better energy budget in the atmospheric boundary layer and results also in a more realistic surface energy budget associated with more reasonable turbulent fluxes. All this mitigates the positive temperature, relative humidity and horizontal wind speed biases in the lower model levels.

  3. Towards a quantification of ocean wave heights off the west coast of Ireland using land based seismic data

    NASA Astrophysics Data System (ADS)

    Donne, Sarah; Bean, Chris; Lokmer, Ivan; Creamer, Columba; Lambkin, Keith

    2013-04-01

    Ocean gravity waves are driven by atmospheric pressure systems. Their interactions with one another and the production of standing waves in the water column generate pressure changes at the sea floor. These pressure fluctuations are the cause of continuous background seismic noise known as microseisms. The levels of microseism activity vary as a function of the sea state and increase during periods of intensive ocean wave activity. In 2011 a seismic network was deployed along the west coast of Ireland to continuously record microseisms generated in the Atlantic Ocean. This project aims to determine the characteristics of the causative ocean gravity waves through calibration of the microseism data with ocean buoy data. In initial tests we are using a Backpropagation Feed-forward Artificial Neural Network (BP ANN) to establish the underlying relationships between microseisms and ocean waves. If successful these tools could then be used to estimate ocean wave heights and wave periods using a land-based seismic network and complement current wave observations being made offshore by marine buoys. Preliminary ANN results are promising with the network successfully able to reconstruct trends in ocean wave heights and periods. Microseisms can provide significant information about oceanic processes. With a deeper understanding of how these processes work there is potential for 1) locating and tracking the evolution of the largest waves in the North-East Atlantic and 2) reconstructing the wave climate off the west coast of Ireland using legacy seismic data on a longer time scale than is currently available using marine based observations.

  4. Determination of Planetary Boundary Layer Height from Ground Based Wind Profiler and Lidar Measurements using the Covariance Wavelet Transform (CWT)

    NASA Astrophysics Data System (ADS)

    Compton, Jaime Cole

    This thesis documents the application of the Covariance Wavelet Transform (CWT) to lidar and, for the first time to our knowledge, wind profiler data to examine the possibility of accurate and continuous planetary boundary layer height (PBLH) measurements on short temporal resolution (one and fifteen minute averages respectively). Comparisons between PBLHs derived from the Elastic Lidar Facility (ELF) through application of the CWT and daytime radiosonde launches from Beltsville and RFK Stadium as part of the September 2009 NOAA/ARL and NCEP field study show an R2 = 0.84 correlation. PBLHs from ELF aided in diagnosing issues with the automatic PBLH calculation from Aircraft Communications Addressing and Reporting System (ACARS) profiles in the Real-Time Mesoscale Analysis used by plume dispersion modelers. Determining the mixing in the PBL was one goal of a study of the spatial and diurnal variations of the PBL height over Maryland for July 2011, during NASA's Earth Venture mission DISCOVER-AQ. A semi-automated PBLH detection algorithm utilizing the CWT for wind profiler data was developed. This algorithm was tested on data from the 915 MHz wind profiler at Beltsville, Maryland, and compared against PBLHs derived from ground based radiosondes measured at Beltsville. Comparisons were also done between PBLHs derived from ground based lidars at UMBC and Beltsville. Results from the comparison show an R 2 = 0.89, 0.92, and 0.94 correlation between the radiosonde PBLHs and the lidars and wind profiler PBLHs, respectively. Accurate determination of the PBLH by applying the CWT to lidar and wind profilers will allow for improved air quality forecasting and understanding of regional pollution dynamics.

  5. COMBAT: mobile-Cloud-based cOmpute/coMmunications infrastructure for BATtlefield applications

    NASA Astrophysics Data System (ADS)

    Soyata, Tolga; Muraleedharan, Rajani; Langdon, Jonathan; Funai, Colin; Ames, Scott; Kwon, Minseok; Heinzelman, Wendi

    2012-05-01

    The amount of data processed annually over the Internet has crossed the zetabyte boundary, yet this Big Data cannot be efficiently processed or stored using today's mobile devices. Parallel to this explosive growth in data, a substantial increase in mobile compute-capability and the advances in cloud computing have brought the state-of-the- art in mobile-cloud computing to an inflection point, where the right architecture may allow mobile devices to run applications utilizing Big Data and intensive computing. In this paper, we propose the MObile Cloud-based Hybrid Architecture (MOCHA), which formulates a solution to permit mobile-cloud computing applications such as object recognition in the battlefield by introducing a mid-stage compute- and storage-layer, called the cloudlet. MOCHA is built on the key observation that many mobile-cloud applications have the following characteristics: 1) they are compute-intensive, requiring the compute-power of a supercomputer, and 2) they use Big Data, requiring a communications link to cloud-based database sources in near-real-time. In this paper, we describe the operation of MOCHA in battlefield applications, by formulating the aforementioned mobile and cloudlet to be housed within a soldier's vest and inside a military vehicle, respectively, and enabling access to the cloud through high latency satellite links. We provide simulations using the traditional mobile-cloud approach as well as utilizing MOCHA with a mid-stage cloudlet to quantify the utility of this architecture. We show that the MOCHA platform for mobile-cloud computing promises a future for critical battlefield applications that access Big Data, which is currently not possible using existing technology.

  6. Development and clinical study of mobile 12-lead electrocardiography based on cloud computing for cardiac emergency.

    PubMed

    Fujita, Hideo; Uchimura, Yuji; Waki, Kayo; Omae, Koji; Takeuchi, Ichiro; Ohe, Kazuhiko

    2013-01-01

    To improve emergency services for accurate diagnosis of cardiac emergency, we developed a low-cost new mobile electrocardiography system "Cloud Cardiology®" based upon cloud computing for prehospital diagnosis. This comprises a compact 12-lead ECG unit equipped with Bluetooth and Android Smartphone with an application for transmission. Cloud server enables us to share ECG simultaneously inside and outside the hospital. We evaluated the clinical effectiveness by conducting a clinical trial with historical comparison to evaluate this system in a rapid response car in the real emergency service settings. We found that this system has an ability to shorten the onset to balloon time of patients with acute myocardial infarction, resulting in better clinical outcome. Here we propose that cloud-computing based simultaneous data sharing could be powerful solution for emergency service for cardiology, along with its significant clinical outcome. PMID:23920851

  7. Point clouds segmentation as base for as-built BIM creation

    NASA Astrophysics Data System (ADS)

    Macher, H.; Landes, T.; Grussenmeyer, P.

    2015-08-01

    In this paper, a three steps segmentation approach is proposed in order to create 3D models from point clouds acquired by TLS inside buildings. The three scales of segmentation are floors, rooms and planes composing the rooms. First, floor segmentation is performed based on analysis of point distribution along Z axis. Then, for each floor, room segmentation is achieved considering a slice of point cloud at ceiling level. Finally, planes are segmented for each room, and planes corresponding to ceilings and floors are identified. Results of each step are analysed and potential improvements are proposed. Based on segmented point clouds, the creation of as-built BIM is considered in a future work section. Not only the classification of planes into several categories is proposed, but the potential use of point clouds acquired outside buildings is also considered.

  8. Estimating Aircraft Heading Based on Laserscanner Derived Point Clouds

    NASA Astrophysics Data System (ADS)

    Koppanyi, Z.; Toth, C., K.

    2015-03-01

    Using LiDAR sensors for tracking and monitoring an operating aircraft is a new application. In this paper, we present data processing methods to estimate the heading of a taxiing aircraft using laser point clouds. During the data acquisition, a Velodyne HDL-32E laser scanner tracked a moving Cessna 172 airplane. The point clouds captured at different times were used for heading estimation. After addressing the problem and specifying the equation of motion to reconstruct the aircraft point cloud from the consecutive scans, three methods are investigated here. The first requires a reference model to estimate the relative angle from the captured data by fitting different cross-sections (horizontal profiles). In the second approach, iterative closest point (ICP) method is used between the consecutive point clouds to determine the horizontal translation of the captured aircraft body. Regarding the ICP, three different versions were compared, namely, the ordinary 3D, 3-DoF 3D and 2-DoF 3D ICP. It was found that 2-DoF 3D ICP provides the best performance. Finally, the last algorithm searches for the unknown heading and velocity parameters by minimizing the volume of the reconstructed plane. The three methods were compared using three test datatypes which are distinguished by object-sensor distance, heading and velocity. We found that the ICP algorithm fails at long distances and when the aircraft motion direction perpendicular to the scan plane, but the first and the third methods give robust and accurate results at 40m object distance and at ~12 knots for a small Cessna airplane.

  9. Macroscopic cloud properties in the WRF NWP model: An assessment using sky camera and ceilometer data

    NASA Astrophysics Data System (ADS)

    Arbizu-Barrena, Clara; Pozo-Vázquez, David; Ruiz-Arias, José A.; Tovar-Pescador, Joaquín.

    2015-10-01

    The ability of six microphysical parameterizations included in the Weather Research and Forecasting (WRF) numerical weather prediction (NWP) model to represent various macroscopic cloud characteristics at multiple spatial and temporal resolutions is investigated. In particular, the model prediction skills of cloud occurrence, cloud base height, and cloud cover are assessed. When it is possible, the results are provided separately for low-, middle-, and high-level clouds. The microphysical parameterizations assessed are WRF single-moment six-class, Thompson, Milbrandt-Yau, Morrison, Stony Brook University, and National Severe Storms Laboratory double moment. The evaluated macroscopic cloud properties are determined based on the model cloud fractions. Two cloud fraction approaches, namely, a binary cloud fraction and a continuous cloud fraction, are investigated. Model cloud cover is determined by overlapping the vertically distributed cloud fractions following three different strategies. The evaluation is conducted based on observations gathered with a ceilometer and a sky camera located in Jaén (southern Spain). The results prove that the reliability of the WRF model mostly depends on the considered cloud parameter, cloud level, and spatiotemporal resolution. In our test bed, it is found that WRF model tends to (i) overpredict the occurrence of high-level clouds irrespectively of the spatial resolution, (ii) underestimate the cloud base height, and (iii) overestimate the cloud cover. Overall, the best cloud estimates are found for finer spatial resolutions (1.3 and 4 km with slight differences between them) and coarser temporal resolutions. The roles of the parameterization choice of the microphysics scheme and the cloud overlapping strategy are, in general, less relevant.

  10. Analysis of interstellar cloud structure based on IRAS images

    NASA Technical Reports Server (NTRS)

    Scalo, John M.

    1992-01-01

    The goal of this project was to develop new tools for the analysis of the structure of densely sampled maps of interstellar star-forming regions. A particular emphasis was on the recognition and characterization of nested hierarchical structure and fractal irregularity, and their relation to the level of star formation activity. The panoramic IRAS images provided data with the required range in spatial scale, greater than a factor of 100, and in column density, greater than a factor of 50. In order to construct densely sampled column density maps of star-forming clouds, column density images of four nearby cloud complexes were constructed from IRAS data. The regions have various degrees of star formation activity, and most of them have probably not been affected much by the disruptive effects of young massive stars. The largest region, the Scorpius-Ophiuchus cloud complex, covers about 1000 square degrees (it was subdivided into a few smaller regions for analysis). Much of the work during the early part of the project focused on an 80 square degree region in the core of the Taurus complex, a well-studied region of low-mass star formation.

  11. Convective cloud fields in the Atlantic sector of the Arctic: Satellite and ground-based observations

    NASA Astrophysics Data System (ADS)

    Esau, I. N.; Chernokulsky, A. V.

    2015-12-01

    Convective cloudiness in the Atlantic sector of the Arctic is considered as an atmospheric spatially self-organized convective field. Convective cloud development is usually studied as a local process reflecting the convective instability of the turbulent planetary boundary layer over a heated surface. The convective cloudiness has a different dynamical structure in high latitudes. Cloud development follows cold-air outbreaks into the areas with a relatively warm surface. As a result, the physical and morphological characteristics of clouds, such as the type of convective cloud, and their geographical localization are interrelated. It has been shown that marginal sea ice and coastal zones are the most frequently occupied by Cu hum, Cu med convective clouds, which are organized in convective rolls. Simultaneously, the open water marine areas are occupied by Cu cong, Cb, which are organized in convective cells. An intercomparison of cloud statistics using satellite data ISCCP and ground-based observations has revealed an inconsistency in the cloudiness trends in these data sources: convective cloudiness decreases in ISCCP data and increases in the groundbased observation data. In general, according to the stated hypothesis, the retreat of the sea-ice boundary may lead to an increase in the amount of convective clouds.

  12. Using ground-based stereo cameras to derive cloud-level wind fields.

    PubMed

    Porter, John N; Cao, Guang Xia

    2009-08-15

    Upper-level wind fields are obtained by tracking the motion of cloud features as seen in calibrated ground-based stereo cameras. By tracking many cloud features, it is possible to obtain horizontal wind speed and direction over a cone area throughout the troposphere. Preliminary measurements were made at the Mauna Loa Observatory, and resulting wind measurements are compared with winds from the Hilo, Hawaii radiosondes. PMID:19684790

  13. 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.

  14. Analysis of Satellite-Based Polar Mesospheric Cloud Observations

    NASA Astrophysics Data System (ADS)

    Benze, Susanne

    Polar Mesospheric Clouds (PMCs) are thin water-ice clouds that form in the summer polar mesopause region. Since PMCs are sensitive to changes in the upper atmospheric temperature and water vapor abundance, they can be used to understand the dynamics of the upper mesosphere. It has also been suggested that they are important indicators of mesospheric climate change. PMCs have been successfully observed from the ground and with remote sensing instruments, for example the Cloud Imaging and Particle Size (CIPS) experiment on the Aeronomy of Ice in the Mesosphere (AIM) satellite, and the Solar Backscatter UltraViolet (SBUV) instruments. This thesis presents validation of CIPS observations by showing a comparison of PMC occurrence frequency, cloud and background albedo as observed by CIPS and SBUV. It is found that frequency and cloud albedo are in excellent agreement, with a small (10%) low bias in the CIPS v3.20 operational frequencies at more equatorward PMC latitudes on the descending node. The background albedo, however, shows a still unresolved bias that depends on hemisphere. Overall, the results show that CIPS PMC data are valid for scientific analysis. Furthermore, this thesis investigates and quantifies the relative importance of several coupling mechanisms that contribute to variability in the PMC season onset, such as the solar cycle and intra-hemispheric and inter-hemispheric coupling. It is found that the Southern Hemisphere (SH) PMC season onset is controlled primarily by the timing of the SH stratospheric wind reversal from its winter to summer state, with a smaller but still important contribution from the solar cycle. Inter-hemispheric coupling triggered by winter stratospheric wind variations plays a significant role in controlling the Northern Hemisphere (NH) PMC season onset dates, again with additional control by the solar cycle. These couplings explain most of the observed variability in the PMC onset dates as observed by SBUV over the past three decades. Preliminary results indicate that the Specified Dynamics version of the Whole Atmosphere Community Climate Model (SD-WACCM) will be a useful tool for more detailed studies of the mechanisms that control PMC variability. Future studies extending the presented CIPS validation and PMC variability investigation are suggested.

  15. Combining UAV-based plant height from crop surface models, visible, and near infrared vegetation indices for biomass monitoring in barley

    NASA Astrophysics Data System (ADS)

    Bendig, Juliane; Yu, Kang; Aasen, Helge; Bolten, Andreas; Bennertz, Simon; Broscheit, Janis; Gnyp, Martin L.; Bareth, Georg

    2015-07-01

    In this study we combined selected vegetation indices (VIs) and plant height information to estimate biomass in a summer barley experiment. The VIs were calculated from ground-based hyperspectral data and unmanned aerial vehicle (UAV)-based red green blue (RGB) imaging. In addition, the plant height information was obtained from UAV-based multi-temporal crop surface models (CSMs). The test site is a summer barley experiment comprising 18 cultivars and two nitrogen treatments located in Western Germany. We calculated five VIs from hyperspectral data. The normalised ratio index (NRI)-based index GnyLi (Gnyp et al., 2014) showed the highest correlation (R2 = 0.83) with dry biomass. In addition, we calculated three visible band VIs: the green red vegetation index (GRVI), the modified GRVI (MGRVI) and the red green blue VI (RGBVI), where the MGRVI and the RGBVI are newly developed VI. We found that the visible band VIs have potential for biomass prediction prior to heading stage. A robust estimate for biomass was obtained from the plant height models (R2 = 0.80-0.82). In a cross validation test, we compared plant height, selected VIs and their combination with plant height information. Combining VIs and plant height information by using multiple linear regression or multiple non-linear regression models performed better than the VIs alone. The visible band GRVI and the newly developed RGBVI are promising but need further investigation. However, the relationship between plant height and biomass produced the most robust results. In summary, the results indicate that plant height is competitive with VIs for biomass estimation in summer barley. Moreover, visible band VIs might be a useful addition to biomass estimation. The main limitation is that the visible band VIs work for early growing stages only.

  16. Model-Based Estimation of Forest Canopy Height in Red and Austrian Pine Stands Using Shuttle Radar Topography Mission and Ancillary Data: a Proof-of-Concept Study

    SciTech Connect

    Brown Jr., C G; Sarabandi, K; Pierce, L E

    2007-04-06

    In this paper, accurate tree stand height retrieval is demonstrated using C-band Shuttle Radar Topography Mission (SRTM) height and ancillary data. The tree height retrieval algorithm is based on modeling uniform tree stands with a single layer of randomly oriented vegetation particles. For such scattering media, the scattering phase center height, as measured by SRTM, is a function of tree height, incidence angle, and the extinction coefficient of the medium. The extinction coefficient for uniform tree stands is calculated as a function of tree height and density using allometric equations and a fractal tree model. The accuracy of the proposed algorithm is demonstrated using SRTM and TOPSAR data for 15 red pine and Austrian pine stands (TOPSAR is an airborne interferometric synthetic aperture radar). The algorithm yields root-mean-square (rms) errors of 2.5-3.6 m, which is a substantial improvement over the 6.8-8.3-m rms errors from the raw SRTM minus National Elevation Dataset Heights.

  17. Comprehensive Stability Evaluation of Rock Slope Using the Cloud Model-Based Approach

    NASA Astrophysics Data System (ADS)

    Liu, Zaobao; Shao, Jianfu; Xu, Weiya; Xu, Fei

    2014-11-01

    This article presents the cloud model-based approach for comprehensive stability evaluation of complicated rock slopes of hydroelectric stations in mountainous area. This approach is based on membership cloud models which can account for randomness and fuzziness in slope stability evaluation. The slope stability is affected by various factors and each of which is ranked into five grades. The ranking factors are sorted into four categories. The ranking system of slope stability is introduced and then the membership cloud models are applied to analyze each ranking factor for generating cloud memberships. Afterwards, the obtained cloud memberships are synthesized with the factor weights given by experts for comprehensive stability evaluation of rock slopes. The proposed approach is used for the stability evaluation of the left abutment slope in Jinping 1 Hydropower Station. It is shown that the cloud model-based strategy can well consider the effects of each ranking factor and therefore is feasible and reliable for comprehensive stability evaluation of rock slopes.

  18. Feasibility and Demonstration of a Cloud-Based RIID Analysis System

    SciTech Connect

    Wright, Michael C; Hertz, Kristin; Johnson, Will; Sword, Eric D; Younkin, James R; Sadler, L.E.

    2014-01-01

    A significant limitation in the operational utility of handheld and backpack radioisotope identifiers (RIIDs) is the inability of their onboard algorithms to accurately and reliably identify the isotopic sources of the measured gamma-ray energy spectrum. A possible solution is to move the spectral analysis computations to an external device, the cloud, where significantly greater capabilities are available. The implementation and demonstration of a prototype cloud-based RIID analysis system have shown this type of system to be feasible with currently available communication and computational technology. A system study has shown that the potential user community could derive significant benefits from an appropriately implemented cloud-based analysis system and has identified the design and operational characteristics required by the users and stakeholders for such a system. A general description of the hardware and software necessary to implement reliable cloud-based analysis, the value of the cloud expressed by the user community, and the aspects of the cloud implemented in the demonstrations are discussed.

  19. Feasibility and demonstration of a cloud-based RIID analysis system

    NASA Astrophysics Data System (ADS)

    Wright, Michael C.; Hertz, Kristin L.; Johnson, William C.; Sword, Eric D.; Younkin, James R.; Sadler, Lorraine E.

    2015-06-01

    A significant limitation in the operational utility of handheld and backpack radioisotope identifiers (RIIDs) is the inability of their onboard algorithms to accurately and reliably identify the isotopic sources of the measured gamma-ray energy spectrum. A possible solution is to move the spectral analysis computations to an external device, the cloud, where significantly greater capabilities are available. The implementation and demonstration of a prototype cloud-based RIID analysis system have shown this type of system to be feasible with currently available communication and computational technology. A system study has shown that the potential user community could derive significant benefits from an appropriately implemented cloud-based analysis system and has identified the design and operational characteristics required by the users and stakeholders for such a system. A general description of the hardware and software necessary to implement reliable cloud-based analysis, the value of the cloud expressed by the user community, and the aspects of the cloud implemented in the demonstrations are discussed.

  20. Analysis of global cloudiness. 2: Comparison of ground-based and satellite-based cloud climatologies

    SciTech Connect

    Mokhov, I.I.; Schlesinger, M.E. |

    1994-08-01

    Cloud climatologies are developed and intercompared for International Satellite Cloud Climatology Project (ISCCO) (1983-1988), Meteor I (1971-1980), Meteor II (1979-1988), and Nimbus 7 (1979-1985) satellite observations, and for Berlyand and Strokina (1975, 1980) and Warren et al. (1986, 1988) ground-based observations. The satellite annual-mean, global- mean cloudiness, 0.57 +/- 0.05, is less than the ground-based value, 0.61 +/- 0.01, predominantly because of the low value for Nimbus 7. There is agreement between the satellite means of ISCCP, 0.62, and Meteor II, 0.61, and the ground-based means of Warren et al., 0.62, and Berlyand and Strokina, 0.60. Each satellite- and ground-based climatology shows that the hemispheric- mean cloudiness is larger in summer than that in winter in both the northern and southern hemispheres. Excluding Nimbus 7 observations, the zonal- mean cloudiness distributions for January, July, and July minus January display reasonably good agreement between 60 deg S and 60 deg N. In polar latitudes there is significant disagreement among the different climatologies, even in the sign of cloudiness changes from winter to summer. This evinces the need for special cloudiness experiments in polar regions, particularly in winter and summer.

  1. Education on the Cloud: Researching Student-Centered, Cloud-Based Learning Prospects in the Context of a European Network

    ERIC Educational Resources Information Center

    Panoutsopoulos, Hercules; Donert, Karl; Papoutsis, Panos; Kotsanis, Ioannis

    2015-01-01

    During the last few years, ongoing developments in the technological field of Cloud computing have initiated discourse on the potential of the Cloud to be systematically exploited in educational contexts. Research interest has been stimulated by a range of advantages of Cloud technologies (e.g. adaptability, flexibility, scalability,…

  2. Canopy BRF simulation of forest with different crown shape and height in larger scale based on Radiosity method

    NASA Astrophysics Data System (ADS)

    Song, Jinling; Qu, Yonghua; Wang, Jindi; Wan, Huawei; Liu, Xiaoqing

    2007-06-01

    Radiosity method is based on the computer simulation of 3D real structures of vegetations, such as leaves, branches and stems, which are composed by many facets. Using this method we can simulate the canopy reflectance and its bidirectional distribution of the vegetation canopy in visible and NIR regions. But with vegetations are more complex, more facets to compose them, so large memory and lots of time to calculate view factors are required, which are the choke points of using Radiosity method to calculate canopy BRF of lager scale vegetation scenes. We derived a new method to solve the problem, and the main idea is to abstract vegetation crown shapes and to simplify their structures, which can lessen the number of facets. The facets are given optical properties according to the reflectance, transmission and absorption of the real structure canopy. Based on the above work, we can simulate the canopy BRF of the mix scenes with different species vegetation in the large scale. In this study, taking broadleaf trees as an example, based on their structure characteristics, we abstracted their crowns as ellipsoid shells, and simulated the canopy BRF in visible and NIR regions of the large scale scene with different crown shape and different height ellipsoids. Form this study, we can conclude: LAI, LAD the probability gap, the sunlit and shaded surfaces are more important parameter to simulate the simplified vegetation canopy BRF. And the Radiosity method can apply us canopy BRF data in any conditions for our research.

  3. Towards Composing Data Aware Systems Biology Workflows on Cloud Platforms: A MeDICi-based Approach

    SciTech Connect

    Gorton, Ian; Liu, Yan; Yin, Jian; Kulkarni, Anand V.; Wynne, Adam S.

    2011-09-08

    Cloud computing is being increasingly adopted for deploying systems biology scientific workflows. Scientists developing these workflows use a wide variety of fragmented and competing data sets and computational tools of all scales to support their research. To this end, the synergy of client side workflow tools with cloud platforms is a promising approach to share and reuse data and workflows. In such systems, the location of data and computation is essential consideration in terms of quality of service for composing a scientific workflow across remote cloud platforms. In this paper, we describe a cloud-based workflow for genome annotation processing that is underpinned by MeDICi - a middleware designed for data intensive scientific applications. The workflow implementation incorporates an execution layer for exploiting data locality that routes the workflow requests to the processing steps that are colocated with the data. We demonstrate our approach by composing two workflowswith the MeDICi pipelines.

  4. Research of MPPT for photovoltaic generation based on two-dimensional cloud model

    NASA Astrophysics Data System (ADS)

    Liu, Shuping; Fan, Wei

    2013-03-01

    The cloud model is a mathematical representation to fuzziness and randomness in linguistic concepts. It represents a qualitative concept with expected value Ex, entropy En and hyper entropy He, and integrates the fuzziness and randomness of a linguistic concept in a unified way. This model is a new method for transformation between qualitative and quantitative in the knowledge. This paper is introduced MPPT (maximum power point tracking, MPPT) controller based two- dimensional cloud model through analysis of auto-optimization MPPT control of photovoltaic power system and combining theory of cloud model. Simulation result shows that the cloud controller is simple and easy, directly perceived through the senses, and has strong robustness, better control performance.

  5. Remote sensing monitoring of volcanic ash clouds based on PCA method

    NASA Astrophysics Data System (ADS)

    Li, Chengfan; Dai, Yangyang; Zhao, Junjuan; Zhou, Shiqiang; Yin, Jingyuan; Xue, Dan

    2014-12-01

    Volcanic ash clouds threaten the aviation safety and cause global environmental effects. It is possible to effectively monitor the volcanic ash cloud with the aid of thermal infrared remote sensing technology. Principal component analysis (PCA) is able to remove the inter-band correlation and eliminate the data redundancy of remote sensing data. Taking the Eyjafjallajokull volcanic ash clouds formed on 15 and 19 April 2010 as an example, in this paper, the PCA method is used to monitor the volcanic ash cloud based on MODIS bands selection; the USGS standard spectral database and the volcanic absorbing aerosol index (AAI) are applied as contrasts to the monitoring result. The results indicate that: the PCA method is much simpler; its spectral matching rates reach 74.65 and 76.35%, respectively; and the PCA method has higher consistency with volcanic AAI distribution.

  6. Remote Sensing Monitoring of Volcanic Ash Clouds Based on PCA Method

    NASA Astrophysics Data System (ADS)

    Li, Chengfan; Dai, Yangyang; Zhao, Junjuan; Yin, Jingyuan; Xue, Dan

    2015-04-01

    Volcanic ash clouds threaten the aviation safety and cause global environmental effects. It is possible to effectively monitor the volcanic ash cloud with the aid of thermal infrared remote sensing technology. Principal component analysis (PCA) is able to remove the inter-band correlation and eliminate the data redundancy of remote sensing data. Taking the Eyjafjallajokull volcanic ash clouds formed on 15 and 19 April 2010 as an example, in this paper, the PCA method is used to monitor the volcanic ash cloud based on MODIS bands selection; the USGS standard spectral database and the volcanic absorbing aerosol index (AAI) are applied as contrasts to the monitoring result. The results indicate that: the PCA method is much simpler; its spectral matching rates reach 74.65 and 76.35%, respectively; and the PCA method has higher consistency with volcanic AAI distribution.

  7. Validation of MAX-DOAS Cloud classification technique by other techniques based on three years observations in Wuxi, China

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Wagner, Thomas; Xie, Pinhua; Beirle, Steffen; Dörner, Steffen; Remmers, Julia; Li, Ang; Wu, Dexia

    2014-05-01

    Multi-Axis-Differential Optical Absorption Spectroscopy (MAX-DOAS) observations of trace gases can be strongly influenced by clouds and aerosols. Thus it is important to identify clouds and characterise their properties. In the former work (Wagner et al. 2013) we found the colour index, radiance and O4 absorption from MAX-DOAS measurements are sensitive to the properties of cloud and aerosol and built a sophisticated classification scheme. In this work we further improved the identification of clouds and aerosol for each elevation sequence of MAX-DOAS based on three years of measurements (2011 to 2013) in Wuxi, China (31.57°N, 120.31°E). The cloud classification results were verified by comparing with other cloud or aerosol data sets such as the aerosol optical depth (AOD) from the AERONET Taihu monitoring site (31.42° N, 120.22° E), MODIS Level 2 cloud products and cloud parameters in level 2b productions of OMI and GOME-2 from TEMIS. We find good agreement with the MAX-DOAS cloud classification using statistical analyses. Based on the results of MAX-DOAS cloud classification, we investigate the influence of clouds and aerosol to the MAX-DOAS measurements of the NO2 tropospheric vertical column density. We compare the influence of clouds and aerosols on the atmospheric light paths with their influence of the NO2 photolysis and thus on the partitioning between NO2 and NO.

  8. Cloud Based Web 3d GIS Taiwan Platform

    NASA Astrophysics Data System (ADS)

    Tsai, W.-F.; Chang, J.-Y.; Yan, S. Y.; Chen, B.

    2011-09-01

    This article presents the status of the web 3D GIS platform, which has been developed in the National Applied Research Laboratories. The purpose is to develop a global earth observation 3D GIS platform for applications to disaster monitoring and assessment in Taiwan. For quick response to preliminary and detailed assessment after a natural disaster occurs, the web 3D GIS platform is useful to access, transfer, integrate, display and analyze the multi-scale huge data following the international OGC standard. The framework of cloud service for data warehousing management and efficiency enhancement using VMWare is illustrated in this article.

  9. 2D Radiative Processes Near Cloud Edges

    NASA Technical Reports Server (NTRS)

    Varnai, T.

    2012-01-01

    Because of the importance and complexity of dynamical, microphysical, and radiative processes taking place near cloud edges, the transition zone between clouds and cloud free air has been the subject of intense research both in the ASR program and in the wider community. One challenge in this research is that the one-dimensional (1D) radiative models widely used in both remote sensing and dynamical simulations become less accurate near cloud edges: The large horizontal gradients in particle concentrations imply that accurate radiative calculations need to consider multi-dimensional radiative interactions among areas that have widely different optical properties. This study examines the way the importance of multidimensional shortwave radiative interactions changes as we approach cloud edges. For this, the study relies on radiative simulations performed for a multiyear dataset of clouds observed over the NSA, SGP, and TWP sites. This dataset is based on Microbase cloud profiles as well as wind measurements and ARM cloud classification products. The study analyzes the way the difference between 1D and 2D simulation results increases near cloud edges. It considers both monochromatic radiances and broadband radiative heating, and it also examines the influence of factors such as cloud type and height, and solar elevation. The results provide insights into the workings of radiative processes and may help better interpret radiance measurements and better estimate the radiative impacts of this critical region.

  10. Nowcasting of cloud cover with MSG

    NASA Astrophysics Data System (ADS)

    Sirch, Tobias; Bugliaro, Luca

    2014-05-01

    In this poster, an algorithm is shown to detect water and ice clouds seperately and forecast their developement for the next timesteps. It is based on Meteosat SEVIRI (Spinning Enhanced Visible and Infrared Imager) data from almost all channels with a timestep of 15 minutes. In order to derive cloud cover, optical depth and height of ice clouds the "Cirrus Optical properties derived from CALIOP and SEVIRI during day and night" (COCS) algorithm (Kox 2012) was used. For the determination of water clouds a cloud mask was developed. For a most accurate forecast the detected clouds are divided into two groups, convective and advective, and afterwards treated seperately. The forecast of advective clouds basically takes place with the pyramidal matcher ("optical flow" technique, Zinner et al. 2008) by determining a motion vector field from two consecutive images. The clouds are then classified as objects with similar properties (optical depth, temperature) and a forecast for each object separately is then performed. For the detection of convective clouds the tracking and nowcasting algorithm Cb-TRAM (CumulonimBus TRacking And Monitoring, Zinner et al. 2008) is used, which divides convection into three stages. The further development und thus the forecast of these clouds is dependent of the current stage. Appications to selected case studies will be shown.

  11. Ground-based remote sensing of thin clouds in the Arctic

    NASA Astrophysics Data System (ADS)

    Garrett, T. J.; Zhao, C.

    2013-05-01

    This paper describes a method for using interferometer measurements of downwelling thermal radiation to retrieve the properties of single-layer clouds. Cloud phase is determined from ratios of thermal emission in three "micro-windows" at 862.5 cm-1, 935.8 cm-1, and 988.4 cm-1 where absorption by water vapour is particularly small. Cloud microphysical and optical properties are retrieved from thermal emission in the first two of these micro-windows, constrained by the transmission through clouds of primarily stratospheric ozone emission at 1040 cm-1. Assuming a cloud does not approximate a blackbody, the estimated 95% confidence retrieval errors in effective radius re, visible optical depth τ, number concentration N, and water path WP are, respectively, 10%, 20%, 38% (55% for ice crystals), and 16%. Applied to data from the Atmospheric Radiation Measurement programme (ARM) North Slope of Alaska - Adjacent Arctic Ocean (NSA-AAO) site near Barrow, Alaska, retrievals show general agreement with both ground-based microwave radiometer measurements of liquid water path and a method that uses combined shortwave and microwave measurements to retrieve re, τ and N. Compared to other retrieval methods, advantages of this technique include its ability to characterise thin clouds year round, that water vapour is not a primary source of retrieval error, and that the retrievals of microphysical properties are only weakly sensitive to retrieved cloud phase. The primary limitation is the inapplicability to thicker clouds that radiate as blackbodies and that it relies on a fairly comprehensive suite of ground based measurements.

  12. An Interactive Web-Based Analysis Framework for Remote Sensing Cloud Computing

    NASA Astrophysics Data System (ADS)

    Wang, X. Z.; Zhang, H. M.; Zhao, J. H.; Lin, Q. H.; Zhou, Y. C.; Li, J. H.

    2015-07-01

    Spatiotemporal data, especially remote sensing data, are widely used in ecological, geographical, agriculture, and military research and applications. With the development of remote sensing technology, more and more remote sensing data are accumulated and stored in the cloud. An effective way for cloud users to access and analyse these massive spatiotemporal data in the web clients becomes an urgent issue. In this paper, we proposed a new scalable, interactive and web-based cloud computing solution for massive remote sensing data analysis. We build a spatiotemporal analysis platform to provide the end-user with a safe and convenient way to access massive remote sensing data stored in the cloud. The lightweight cloud storage system used to store public data and users' private data is constructed based on open source distributed file system. In it, massive remote sensing data are stored as public data, while the intermediate and input data are stored as private data. The elastic, scalable, and flexible cloud computing environment is built using Docker, which is a technology of open-source lightweight cloud computing container in the Linux operating system. In the Docker container, open-source software such as IPython, NumPy, GDAL, and Grass GIS etc., are deployed. Users can write scripts in the IPython Notebook web page through the web browser to process data, and the scripts will be submitted to IPython kernel to be executed. By comparing the performance of remote sensing data analysis tasks executed in Docker container, KVM virtual machines and physical machines respectively, we can conclude that the cloud computing environment built by Docker makes the greatest use of the host system resources, and can handle more concurrent spatial-temporal computing tasks. Docker technology provides resource isolation mechanism in aspects of IO, CPU, and memory etc., which offers security guarantee when processing remote sensing data in the IPython Notebook. Users can write complex data processing code on the web directly, so they can design their own data processing algorithm.

  13. A Novel Approach to Generate Essential New CALIPSO-based Products: Biomass Burning Plume Injection Height Using CALIOP, MODIS and the NASA Langley Trajectory Model

    NASA Astrophysics Data System (ADS)

    Vaughan, M.; Soja, A. J.; Fairlie, T. D.; Westberg, D. J.; Pouliot, G.

    2012-12-01

    There is a significant connection between biomass burning (BB) emissions, the terrestrial environment and the atmosphere, which has strong implications for feedbacks to Air Quality and to the climate system. BB has the potential to alter numerous land and atmospheric processes and their full influence to feedback to interactive systems is currently being exposed (i.e. black carbon on spring Arctic ice). The heights to which BB emissions are injected influence their transport, their interaction with clouds, which alters albedo, and their ability to modify patterns of precipitation. We are working with our applications partners, primarily the Environmental Protection Agency and regional partners, to generate BB plume injection height products using multiple platforms, sensors and models (CALIOP, MODIS, NOAA HMS, Langley Trajectory Model) that will provide value to national and international scientific and air quality communities, the CALIPSO science and algorithm teams, and to public land, fire, and air quality management and regulations communities. Specifically, we are: (1) developing mean statistics that link CALIOP air parcels and BB injection height to the variables that control these dynamics, which include ecosystems, fire-specific and meteorological variables; and (2) defining the daily evolution of smoke plumes for specific fires. Statistics that link fire behavior and weather to plume rise are crucial for verifying and enhancing plume rise parameterization in regional- and global-scale models used for air quality, chemical transport and climate.

  14. Comparing satellite- to ground-based automated and manual cloud coverage observations - a case study

    NASA Astrophysics Data System (ADS)

    Werkmeister, A.; Lockhoff, M.; Schrempf, M.; Tohsing, K.; Liley, B.; Seckmeyer, G.

    2015-05-01

    In this case study we compare cloud fractional cover measured by radiometers on polar satellites (AVHRR) and on one geostationary satellite (SEVIRI) to ground-based manual (SYNOP) and automated observations by a cloud camera (Hemispherical Sky Imager, HSI). These observations took place in Hannover, Germany, and in Lauder, New Zealand, over time frames of 3 and 2 months, respectively. Daily mean comparisons between satellite derivations and the ground-based HSI found the deviation to be 6 ± 14% for AVHRR and 8 ± 16% for SEVIRI, which can be considered satisfactory. AVHRR's instantaneous differences are smaller (2 ± 22%) than instantaneous SEVIRI cloud fraction estimates (8 ± 29%) when compared to HSI due to resolution and scenery effect issues. All spaceborne observations show a very good skill in detecting completely overcast skies (cloud cover ≥ 6 oktas) with probabilities between 92 and 94% and false alarm rates between 21 and 29% for AVHRR and SEVIRI in Hannover, Germany. In the case of a clear sky (cloud cover lower than 3 oktas) we find good skill with detection probabilities between 72 and 76%. We find poor skill, however, whenever broken clouds occur (probability of detection is 32% for AVHRR and 12% for SEVIRI in Hannover, Germany). In order to better understand these discrepancies we analyze the influence of algorithm features on the satellite-based data. We find that the differences between SEVIRI and HSI cloud fractional cover (CFC) decrease (from a bias of 8 to almost 0%) with decreasing number of spatially averaged pixels and decreasing index which determines the cloud coverage in each "cloud-contaminated" pixel of the binary map. We conclude that window size and index need to be adjusted in order to improve instantaneous SEVIRI and AVHRR estimates. Due to its automated operation and its spatial, temporal and spectral resolution, we recommend as well that more automated ground-based instruments in the form of cloud cameras should be installed as they cover larger areas of the sky than other automated ground-based instruments. These cameras could be an essential supplement to SYNOP observation as they cover the same spectral wavelengths as the human eye.

  15. Height control of laser metal-wire deposition based on iterative learning control and 3D scanning

    NASA Astrophysics Data System (ADS)

    Heralić, Almir; Christiansson, Anna-Karin; Lennartson, Bengt

    2012-09-01

    Laser Metal-wire Deposition is an additive manufacturing technique for solid freeform fabrication of fully dense metal structures. The technique is based on robotized laser welding and wire filler material, and the structures are built up layer by layer. The deposition process is, however, sensitive to disturbances and thus requires continuous monitoring and adjustments. In this work a 3D scanning system is developed and integrated with the robot control system for automatic in-process control of the deposition. The goal is to ensure stable deposition, by means of choosing a correct offset of the robot in the vertical direction, and obtaining a flat surface, for each deposited layer. The deviations in the layer height are compensated by controlling the wire feed rate on next deposition layer, based on the 3D scanned data, by means of iterative learning control. The system is tested through deposition of bosses, which is expected to be a typical application for this technique in the manufacture of jet engine components. The results show that iterative learning control including 3D scanning is a suitable method for automatic deposition of such structures. This paper presents the equipment, the control strategy and demonstrates the proposed approach with practical experiments.

  16. Accelerating and democratizing science through cloud-based services.

    SciTech Connect

    Foster, I.

    2011-05-01

    Many businesses today save time and money, and increase their agility, by outsourcing mundane IT tasks to cloud providers. The author argues that similar methods can be used to overcome the complexities inherent in increasingly data-intensive, computational, and collaborative scientific research. He describes Globus Online, a system that he and his colleagues are developing to realize this vision. he scientific community today has unprecedented opportunities to effect transformational change in how individuals and teams engage in discovery. The driving force is a set of interrelated new capabilities that, when harnessed, can enable dramatic acceleration in the discovery process: greater availability of massive data, exponentially faster computers, ultra-high-speed networks, and deep interdisciplinary collaboration. The opportunity - and challenge - is to make these capabilities accessible not just to a few 'big science' projects but to every researcher at every level. Here, I argue that the key to seizing this opportunity is embracing software delivery methods that haven't been widely adopted in research, notably software as a service (SaaS) - a technology that forms an important part of what people refer to as the cloud. I also describe projects in the Computation Institute at the University of Chicago and Argonne National Laboratory that aim to realize this vision, focusing initially on data movement and management.

  17. Long-term impacts of aerosols on vertical development of cloud and precipitation

    SciTech Connect

    Li Z.; Liu Y.; Niu, F.; Fan, J.; Rosenfeld, D.; Ding, Y.

    2011-11-13

    Aerosols alter cloud density and the radiative balance of the atmosphere. This leads to changes in cloud microphysics and atmospheric stability, which can either suppress or foster the development of clouds and precipitation. The net effect is largely unknown, but depends on meteorological conditions and aerosol properties. Here, we examine the long-term impact of aerosols on the vertical development of clouds and rainfall frequencies, using a 10-year dataset of aerosol, cloud and meteorological variables collected in the Southern Great Plains in the United States. We show that cloud-top height and thickness increase with aerosol concentration measured near the ground in mixed-phase clouds-which contain both liquid water and ice-that have a warm, low base. We attribute the effect, which is most significant in summer, to an aerosol-induced invigoration of upward winds. In contrast, we find no change in cloud-top height and precipitation with aerosol concentration in clouds with no ice or cool bases. We further show that precipitation frequency and rain rate are altered by aerosols. Rain increases with aerosol concentration in deep clouds that have a high liquid-water content, but declines in clouds that have a low liquid-water content. Simulations using a cloud-resolving model confirm these observations. Our findings provide unprecedented insights of the long-term net impacts of aerosols on clouds and precipitation.

  18. Dynamic resource allocation engine for cloud-based real-time video transcoding in mobile cloud computing environments

    NASA Astrophysics Data System (ADS)

    Adedayo, Bada; Wang, Qi; Alcaraz Calero, Jose M.; Grecos, Christos

    2015-02-01

    The recent explosion in video-related Internet traffic has been driven by the widespread use of smart mobile devices, particularly smartphones with advanced cameras that are able to record high-quality videos. Although many of these devices offer the facility to record videos at different spatial and temporal resolutions, primarily with local storage considerations in mind, most users only ever use the highest quality settings. The vast majority of these devices are optimised for compressing the acquired video using a single built-in codec and have neither the computational resources nor battery reserves to transcode the video to alternative formats. This paper proposes a new low-complexity dynamic resource allocation engine for cloud-based video transcoding services that are both scalable and capable of being delivered in real-time. Firstly, through extensive experimentation, we establish resource requirement benchmarks for a wide range of transcoding tasks. The set of tasks investigated covers the most widely used input formats (encoder type, resolution, amount of motion and frame rate) associated with mobile devices and the most popular output formats derived from a comprehensive set of use cases, e.g. a mobile news reporter directly transmitting videos to the TV audience of various video format requirements, with minimal usage of resources both at the reporter's end and at the cloud infrastructure end for transcoding services.

  19. GEWEX Cloud System Study (GCSS) cirrus cloud working group: modelling case development based on 9 March 2000 ARM SGP observations

    NASA Astrophysics Data System (ADS)

    Yang, H.; Dobbie, S.; Mace, G. G.; Ross, A.; Quante, M.

    2011-10-01

    The GCSS working group on cirrus focuses on inter-comparison of model simulations for models ranging from very detailed microphysical and dynamical models through to general circulation models (GCMs). In the previous GCSS inter-comparison, it was a surprise to the modeling community how much of a range there was in ice water path predictions by different cirrus models for such idealized cases. There was some grouping according to the complexity of models; however, there were no observations with which to distinguish between model performance. The aim of the current GCSS cirrus inter-comparison is to base the study on a rigorously observed case study. In this way, the case may be used to identify which models in the inter-comparison are performing well and highlight areas for model development as well as provide a base case for future models to compare against when being developed or when testing new developments within existing models. In this paper, we present the case development for the current GCSS working group study on cirrus cloud. This paper summarizes how the case was developed and based on the 9 March 2000 Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) intensive observation period (IOP). To our knowledge, this case offers the most detailed case study for cirrus comparison available, with extensive effort to derive the most appropriate large scale forcing as possible which is such a significant determinant of clouds. We anticipate this will offer significant improvement over past comparisons which have mostly been loosely based on observations. Notably this study makes use of retrievals of observations of ice water content, ice number concentration, and fall velocity, thus offering several constraints to evaluate model performance. The case study is developed utilizing various observations including ARM SGP remote sensing including the Millimeter cloud radar (MMCR), radiometers, radiosondes, aircraft observations, satellite observations, objective analysis and complemented with results from the Rapid Update Cycle (RUC) model output and bespoke gravity wave simulations using the 3-dimensional velocities over mountains (3DVOM) model. An initial modelling assessment of the case has been shown using the UK Met Office Large Eddy Simulation Model (LEM) which supports the use of this case for the full inter-comparison study.

  20. Sensing Clouds via Spacecraft Radio Occultation Observations

    NASA Technical Reports Server (NTRS)

    Kursinski, E. R.; Wu, F.; Limaye, S.; Wu, M.- L.

    2000-01-01

    The presence of clouds dramatically alters the opacity and radiative transfer within Earth's atmosphere at both short and long wavelengths. Knowledge of cloud top and base is needed to estimate the Outgoing Long wave Radiation (OLR) to space and the net radiation at the surface from a given atmospheric profile. Satellite observations are required to provide the global perspective needed for climate. Cloud top pressure can be determined to some accuracy from spaceborne radiance measurements when cloud opacities are sufficiently large and cloud top temperatures are sufficiently low to readily them from the surface. Cloud base is particularly difficult to determine from space. The relatively small sensitivity of long wavelengths must be used to penetrate the clouds while at the same time providing sufficient sensitivity to detect the cloud base. We are studying the indirect sensitivity of radio occultation observations to clouds through their impact on the refractivity structure. The tradewind inversion is an excellent example where a very sharp refractivity structure coincides with the top of the tradewind cumulus and stratus clouds. In general, any cloud with sufficient IR opacity will have large transmissivity gradient at cloud top (base) which will result in large cooling (heating) which will create a thermal inversion at cloud top (base). Both liquid and ice clouds can reach this critical opacity. The thermal inversion and sharp change in specific humidity will cause a sharp change in the refractivity gradient which can be identified in the radio occultation results, particularly the signal amplitude. The occultations yield very accurate information on the height of such features. The heating at cloud base drives convection causing the air to follow a moist adiabat within the Cloud which further helps constrain the interpretation of the observations. The upward expansion of such opaque clouds due to convection may be an important mechanism supplying moisture into the upper troposphere. We will present simulations using high resolution radiosondes from field campaigns representing the expected signatures of such features. We will also present initial results of comparisons between GPS observations and GOES-derived cloud tops to assess the utility of this concept.

  1. Assessment of cloud related fine mode AOD enhancements based on AERONET SDA product

    NASA Astrophysics Data System (ADS)

    Arola, A. T.; Eck, T. F.; Kokkola, H.; Laaksoviita, T.; Lindfors, A. V.; Pitkänen, M. R. A.; Romakkaniemi, S.

    2014-12-01

    AERONET (AErosol RObotic NETwork), which is a network of ground-based sun photometers, includes also so-called Aerosol Spectral Deconvolution Algorithm (SDA) that utilizes spectral total extinction AOD data to infer the component fine and coarse mode optical depths at 500nm. Based on its assumptions, SDA identifies cloud optical depth as the coarse mode AOD component and therefore effectively computes the fine mode AOD also in mixed cloud-aerosol observations. Therefore, it can be argued that the more representative AOD for fine mode fraction should be based on all direct sun measurements and not only on those cloud-screened for clear-sky conditions, in other words on those from Level 1 (L1) instead of Level 2 (L2). The objective of our study was to assess, including all the available AERONET sites, the magnitude of this cloud enhancement in fine mode AOD, in other words contrasting SDA L1 and L2 in our analysis. Assuming that the cloud-screening correctly separates the cloudy and clear-sky conditions, then the increases in fine mode AOD in can be due to various cloud-related processes, mainly by in-cloud processing and hygroscopic growth. We estimated these cloud-related enhancements in fine mode AOD seasonally and found, for instance, than in June-July season the average over all the AERONET sites was 0.034, when total fine mode AOD from L2 data was 0.192, therefore the relative enhancement was 18%. It is difficult to separate the fine mode AOD enhancements due to in-cloud processing and hygroscopic growth, but we attempted to get some understanding by conducting a similar analysis for SDA-based fine mode Angstrom Exponent patterns. Moreover, we included OMI NO2 and Glyoxal data, to infer whether the regional patterns of fine mode AOD enhancements contain similar features than these two data products that could serve as a proxy of the strength of in-cloud processing.

  2. Automatic Atlas Based Electron Density and Structure Contouring for MRI-based Prostate Radiation Therapy on the Cloud

    NASA Astrophysics Data System (ADS)

    Dowling, J. A.; Burdett, N.; Greer, P. B.; Sun, J.; Parker, J.; Pichler, P.; Stanwell, P.; Chandra, S.; Rivest-Hénault, D.; Ghose, S.; Salvado, O.; Fripp, J.

    2014-03-01

    Our group have been developing methods for MRI-alone prostate cancer radiation therapy treatment planning. To assist with clinical validation of the workflow we are investigating a cloud platform solution for research purposes. Benefits of cloud computing can include increased scalability, performance and extensibility while reducing total cost of ownership. In this paper we demonstrate the generation of DICOM-RT directories containing an automatic average atlas based electron density image and fast pelvic organ contouring from whole pelvis MR scans.

  3. Increases of Chamber Height and Base Diameter Have Contrasting Effects on Grazing Rate of Two Cladoceran Species: Implications for Microcosm Studies

    PubMed Central

    Pan, Ying; Zhang, Yunshu; Peng, Yan; Zhao, Qinghua; Sun, Shucun

    2015-01-01

    Aquatic microcosm studies often increase either chamber height or base diameter (to increase water volume) to test spatial ecology theories such as “scale” effects on ecological processes, but it is unclear whether the increase of chamber height or base diameter have the same effect on the processes, i.e., whether the effect of the shape of three-dimensional spaces is significant. We orthogonally manipulated chamber height and base diameter and determined swimming activity, average swimming velocity and grazing rates of the cladocerans Daphnia magna and Moina micrura (on two algae Scenedesmus quadricauda and Chlorella vulgaris; leading to four aquatic algae-cladoceran systems in total) under different microcosm conditions. Across all the four aquatic systems, increasing chamber height at a given base diameter significantly decreased the duration and velocity of horizontal swimming, and it tended to increase the duration but decrease the velocity of vertical swimming. These collectively led to decreases in both average swimming velocity and grazing rate of the cladocerans in the tall chambers (at a given base diameter), in accordance with the positive relationship between average swimming velocity and grazing rate. In contrast, an increase of base diameter at a given chamber height showed contrasting effects on the above parameters. Consistently, at a given chamber volume increasing ratio of chamber height to base diameter decreased the average swimming velocity and grazing rate across all the aquatic systems. In general, increasing chamber depth and base diameter may exert contrasting effects on zooplankton behavior and thus phytoplankton-zooplankton interactions. We suggest that spatial shape plays an important role in determining ecological process and thus should be considered in a theoretical framework of spatial ecology and also the physical setting of aquatic microcosm experiments. PMID:26273836

  4. Cloud vertical structures detected by lidar and its statistical results at HeRO site in Hefei, China

    NASA Astrophysics Data System (ADS)

    Sun, Lu; Liu, Dong; Wang, Zhien; Wang, Zhenzhu; Wu, Decheng; Bo, Guangyu; Wang, Yingjian

    2014-11-01

    Extensive studies have illustrated the importance of obtaining exact vertical structures of clouds and aerosols for satellite and relevant climate simulations. However, challenging exists, for example, in distinguishing clouds from aerosols at times. Accurate cloud vertical profiles are mainly determined by cloud bases and heights. Based on the ground-based lidar observations in Hefei Radiation Observatory (HeRO), the vertical structures of clouds and aerosols in Hefei area(31.89N 117.17E) during May 2012-May 2014 have been investigated. The results show that the cloud fraction in the autumn and winter is less than that in the summer and spring, and is largest in the spring followed by the summer. The cloud fractions in the autumn and winter are comparable. The low cloud accounts for the most portion of the total. Compared with the cloud of the other heights, the high cloud is the least in the winter. Nearly 50% of the total vertical profiles can be detected by lidar as clouds and the proportion of the cloud of different heights seems to be stable annually. The fraction of low cloud is nearly 45%, medium cloud is nearly 35%, and high cloud is nearly 20%. In comparison with the results derived from CALIPSO, it is found that high cloud is usually missed for the ground-based lidar, while low cloud is usually omitted for the satellite observations. A combination of ground-based and space-borne lidar could lead to more reliable results. Further analysis will be performed in future studies.

  5. Ship-Track Clouds, Aerosol, and Ship Dynamic Effects; A Climate Perspective from Ship-Based Measurements

    SciTech Connect

    Porch, W.M.

    1998-10-13

    Ship-track clouds are marine boundary layer clouds that form behind ocean ships and are observed from satellites in the visible and near infrared. Ship-track clouds provide a rare opportunity to connect aerosol cloud condensation nuclei (CCN) emissions and observable changes in marine stratiform clouds. A very small change in the reflectivity of these eastern Pacific and Atlantic clouds (about 4%) provides a climate feedback of similar magnitude to doubling CO{sub 2} (increasing cloud reflectivity corresponds to global cooling). The Department of Energy sponsored research from 1991 to 1995 to study ship-track clouds including two ocean-based experiments in the summers of 1991 and 1994. These experiments showed that ship-track cloud properties were often more complex those related to a reduction of droplet size with an increase in number associated with increasing CCN from the ship's plume. The clouds showed evidence of morphological changes more likely to be associated with cloud dynamic effects either initiated by the increased CCN or directly by the ship's heat output or turbulent air wake. The fact that marine stratiform clouds, that are susceptible to ship track formation, are starved for both CCN and convective turbulence complicates the separation of the two effects.

  6. 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; Schfler, 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.

  7. Targeting and impacts of AgI cloud seeding based on rain chemical composition and cloud top phase characterization

    NASA Astrophysics Data System (ADS)

    Zipori, Assaf; Rosenfeld, Daniel; Shpund, Jacob; Steinberg, David M.; Erel, Yigal

    2012-10-01

    During four winters when cloud seeding took place, precipitation samples were collected at three stations in the catchment area of the Sea of Galilee (target stations) and in one station west of the seeding line (control station). Chemical analyses were carried out on more than 4000 rain samples in order to determine the major and trace metal compositions and enrichment factors of Ag (EF) with respect to Al, where Al is used as a tracer for natural dust. In addition, satellite images were analyzed to characterize the cloud phase and the temperature of the tops of the rain clouds using the EUMETSAT second generation geostationary satellite. Our results show that the seeding agent (AgI) arrives to the target stations, as indicated by significantly higher EFAg values of Ag there compared to the control station. Furthermore, we found higher EFAg values in precipitation samples from mixed-phase clouds compared to precipitation from warm or fully glaciated clouds. This difference was observed only at the target stations. Therefore, our results are consistent with the hypothesis that AgI contributes actively to precipitation formation processes in mixed-phase clouds, where ice content is controlled by ice nuclei (IN) concentration. This is in accordance with the conventional wisdom that AgI should be mostly active in such clouds, but not in clouds that are already naturally glaciated or in warm clouds, and it supports previous statistical studies which claimed that cloud seeding enhanced rainfall in Northern Israel.

  8. Cloud-based systems for monitoring earthquakes and other environmental quantities

    NASA Astrophysics Data System (ADS)

    Clayton, R. W.; Olson, M.; Liu, A.; Chandy, M.; Bunn, J.; Guy, R.

    2013-12-01

    There are many advantages to using a cloud-based system to record and analyze environmental quantities such as earthquakes, radiation, various gases, dust and meteorological parameters. These advantages include robustness and dynamic scalability, and also reduced costs. In this paper, we present our experiences over the last three years in developing a cloud-based earthquake monitoring system (the Community Seismic Network). This network consists of over 600 sensors (accelerometers) in the S. California region that send data directly to the Google App Engine where they are analyzed. The system is capable of handing many other types of sensor data and generating a situation-awareness analysis as a product. Other advantages to the cloud-based system are integration with other peer networks, and being able to deploy anywhere in the world without have to build addition computing infrastructure.

  9. A sensitivity-based approach to optimize the surface treatment of a low-height tramway noise barrier

    NASA Astrophysics Data System (ADS)

    Jolibois, Alexandre

    Transportation noise has become a main nuisance in urban areas, in the industrialized world and across the world, to the point that according to the World Health Organization 65% of the European population is exposed to excessive noise and 20% to night-time levels that may harm their health. There is therefore a need to find new ways to mitigate transportation noise in urban areas. In this work, a possible device to achieve this goal is studied: a low-height noise barrier. It consists of a barrier typically less than one meter high placed close to the source, designed to decrease significantly the noise level for nearby pedestrians and cyclists. A numerical method which optimizes the surface treatment of a low-height barrier in order to increase its insertion loss is presented. Tramway noise barriers are especially studied since the noise sources are in this case close to the ground and would be attenuated more by the barrier. The acoustic behavior of the surface treatment is modeled via its admittance. It can be itself described by a few parameters (flow resistivity, geometrical dimensions...), which can then be optimized. It is proposed to couple porous layers and micro-perforated panel (MPP) resonators in order to take advantage of their different acoustic properties. Moreover, the optimization is achieved using a sensitivity-based method, since in this framework the gradient of the attenuation can be evaluated accurately and efficiently. Several shapes are considered: half-cylinder, quarter-cylinder, straight wall, T-shape and square shape. In the case of a half-cylindrical geometry, a semi-analytical solution for the sound field in terms of a series of cylindrical waves is derived, which simplifies the sensitivity calculation and optimization process. The boundary element method (BEM) is used to evaluate the attenuation for the remaining shapes, and in this case the sensitivity is evaluated using the adjoint state approach. For all considered geometries, it is found that placing an absorbing treatment close to the source is indeed necessary to attenuate the multiple re ections happening between the tramway and the barrier, and that a tuned MPP resonator on the top of the barrier can yield better performance than a uniform absorbent treatment. More advanced numerical modeling and scale model measurements seem to confirm these results.

  10. Validation of CERES-MODIS Arctic cloud properties using CloudSat/CALIPSO and ARM NSA observations

    NASA Astrophysics Data System (ADS)

    Giannecchini, K.; Dong, X.; Xi, B.; Minnis, P.; Kato, S.

    2011-12-01

    The traditional passive satellite studies of cloud properties in the Arctic are often affected by the complex surface features present across the region. Nominal visual and thermal contrast exists between Arctic clouds and the snow- and ice-covered surfaces beneath them, which can lead to difficulties in satellite retrievals of cloud properties. However, the addition of active sensors to the A-Train constellation of satellites has increased the availability of validation sources for cloud properties derived from passive sensors in the data-sparse high-latitude regions. In this study, Arctic cloud fraction and cloud heights derived from the NASA CERES team (CERES-MODIS) have been compared with CloudSat/CALIPSO and DOE ARM NSA radar-lidar observations over Barrow, AK, for the two-year period from 2007 to 2008. An Arctic-wide comparison of cloud fraction and height between CERES-MODIS and CloudSat/CALIPSO was then conducted for the same time period. The CERES-MODIS cloud properties, which include cloud fraction and cloud effective heights, were retrieved using the 4-channel VISST (Visible Infrared Solar-Infrared Split-window Technique) [Minnis et al.,1995]. CloudSat/CALIPSO cloud fraction and cloud-base and -top heights were from version RelB1 data products determined by both the 94 GHz radar onboard CloudSat and the lidar on CALIPSO with a vertical resolution of 30 m below 8.2 km and 60 m above. To match the surface and satellite observations/retrievals, the ARM surface observations were averaged into 3-hour intervals centered at the time of the satellite overpass, while satellite observations were averaged within a 3°x3° grid box centered on the Barrow site. The preliminary results have shown that all observed CFs have peaks during April-May and September-October, and dips during winter months (January-February) and summer months (June-July) during the study period of 2007-2008. ARM radar-lidar and CloudSat/CALIPSO show generally good agreement in CF (0.79 vs. 0.74), while CERES-MODIS derived values are much lower (0.60). CERES-MODIS derived cloud effective height (2.7 km) falls between the CloudSat/CALIPSO derived cloud base (0.6 km) and top (6.4 km) and the ARM ceilometers and MMCR derived cloud base (0.9 km) and radar derived cloud top (5.8 km). When extended to the entire Arctic, although the CERES-MODIS and Cloudsat/CALIPSO derived annual mean CFs agree within a few percents, there are significant differences over several regions, and the maximum cloud heights derived from CloudSat/CALIPSO (13.4 km) and CERES-MODIS (10.7 km) show the largest disagreement during early spring.

  11. Global model of the F2 layer peak height for low solar activity based on GPS radio-occultation data

    NASA Astrophysics Data System (ADS)

    Shubin, V. N.; Karpachev, A. T.; Tsybulya, K. G.

    2013-11-01

    We propose a global median model SMF2 (Satellite Model of the F2 layer) of the ionospheric F2-layer height maximum (hmF2), based on GPS radio-occultation data for low solar activity periods (F10.7A<80). The model utilizes data provided by GPS receivers onboard satellites CHAMP (~100,000 hmF2 values), GRACE (~70,000) and COSMIC (~2,000,000). The data were preprocessed to remove cases where the absolute maximum of the electron density lies outside the F2 region. Ground-based ionospheric sounding data were used for comparison and validation. Spatial dependence of hmF2 is modeled by a Legendre-function expansion. Temporal dependence, as a function of Universal Time (UT), is described by a Fourier expansion. Inputs of the model are: geographical coordinates, month and F10.7A solar activity index. The model is designed for quiet geomagnetic conditions (Kр=1-2), typical for low solar activity. SMF2 agrees well with the International Reference Ionosphere model (IRI) in those regions, where the ground-based ionosonde network is dense. Maximal difference between the models is found in the equatorial belt, over the oceans and the polar caps. Standard deviations of the radio-occultation and Digisonde data from the predicted SMF2 median are 10-16 km for all seasons, against 13-29 km for IRI-2012. Average relative deviations are 3-4 times less than for IRI, 3-4% against 9-12%. Therefore, the proposed hmF2 model is more accurate than IRI-2012.

  12. An adaptive process-based cloud infrastructure for space situational awareness applications

    NASA Astrophysics Data System (ADS)

    Liu, Bingwei; Chen, Yu; Shen, Dan; Chen, Genshe; Pham, Khanh; Blasch, Erik; Rubin, Bruce

    2014-06-01

    Space situational awareness (SSA) and defense space control capabilities are top priorities for groups that own or operate man-made spacecraft. Also, with the growing amount of space debris, there is an increase in demand for contextual understanding that necessitates the capability of collecting and processing a vast amount sensor data. Cloud computing, which features scalable and flexible storage and computing services, has been recognized as an ideal candidate that can meet the large data contextual challenges as needed by SSA. Cloud computing consists of physical service providers and middleware virtual machines together with infrastructure, platform, and software as service (IaaS, PaaS, SaaS) models. However, the typical Virtual Machine (VM) abstraction is on a per operating systems basis, which is at too low-level and limits the flexibility of a mission application architecture. In responding to this technical challenge, a novel adaptive process based cloud infrastructure for SSA applications is proposed in this paper. In addition, the details for the design rationale and a prototype is further examined. The SSA Cloud (SSAC) conceptual capability will potentially support space situation monitoring and tracking, object identification, and threat assessment. Lastly, the benefits of a more granular and flexible cloud computing resources allocation are illustrated for data processing and implementation considerations within a representative SSA system environment. We show that the container-based virtualization performs better than hypervisor-based virtualization technology in an SSA scenario.

  13. Web-based Tsunami Early Warning System with instant Tsunami Propagation Calculations in the GPU Cloud

    NASA Astrophysics Data System (ADS)

    Hammitzsch, M.; Spazier, J.; Reißland, S.

    2014-12-01

    Usually, tsunami early warning and mitigation systems (TWS or TEWS) are based on several software components deployed in a client-server based infrastructure. The vast majority of systems importantly include desktop-based clients with a graphical user interface (GUI) for the operators in early warning centers. However, in times of cloud computing and ubiquitous computing the use of concepts and paradigms, introduced by continuously evolving approaches in information and communications technology (ICT), have to be considered even for early warning systems (EWS). Based on the experiences and the knowledge gained in three research projects - 'German Indonesian Tsunami Early Warning System' (GITEWS), 'Distant Early Warning System' (DEWS), and 'Collaborative, Complex, and Critical Decision-Support in Evolving Crises' (TRIDEC) - new technologies are exploited to implement a cloud-based and web-based prototype to open up new prospects for EWS. This prototype, named 'TRIDEC Cloud', merges several complementary external and in-house cloud-based services into one platform for automated background computation with graphics processing units (GPU), for web-mapping of hazard specific geospatial data, and for serving relevant functionality to handle, share, and communicate threat specific information in a collaborative and distributed environment. The prototype in its current version addresses tsunami early warning and mitigation. The integration of GPU accelerated tsunami simulation computations have been an integral part of this prototype to foster early warning with on-demand tsunami predictions based on actual source parameters. However, the platform is meant for researchers around the world to make use of the cloud-based GPU computation to analyze other types of geohazards and natural hazards and react upon the computed situation picture with a web-based GUI in a web browser at remote sites. The current website is an early alpha version for demonstration purposes to give the concept a whirl and to shape science's future. Further functionality, improvements and possible profound changes have to implemented successively based on the users' evolving needs.

  14. A cloud-based X73 ubiquitous mobile healthcare system: design and implementation.

    PubMed

    Ji, Zhanlin; Ganchev, Ivan; O'Droma, Máirtín; Zhang, Xin; Zhang, Xueji

    2014-01-01

    Based on the user-centric paradigm for next generation networks, this paper describes a ubiquitous mobile healthcare (uHealth) system based on the ISO/IEEE 11073 personal health data (PHD) standards (X73) and cloud computing techniques. A number of design issues associated with the system implementation are outlined. The system includes a middleware on the user side, providing a plug-and-play environment for heterogeneous wireless sensors and mobile terminals utilizing different communication protocols and a distributed "big data" processing subsystem in the cloud. The design and implementation of this system are envisaged as an efficient solution for the next generation of uHealth systems. PMID:24737958

  15. Numerical modeling of polarization properties of the return signals in ground-based LIDAR cloud sensing

    NASA Astrophysics Data System (ADS)

    Kablukova, E. G.; Kargin, B. A.; Lisenko, A. A.

    2015-10-01

    The paper presents results of numerical statistical simulations of experiments of ground-based sensing of cloud layers by terahertz linearly polarized radiation for certain wavelengths from the atmospheric transparency windows. Summarized results of many years' field measurements of liquid droplet size distributions in temperate latitudes of the Earth and the distributions obtained by aircraft experiments off Great Britain's coast are used in the scattering layer models. The models of the scattering medium take into account the vertical stratification of water vapor concentration in the atmosphere and the differences in cloud layer microstructure at the top and the base.

  16. Criteria for the evaluation of a cloud-based hospital information system outsourcing provider.

    PubMed

    Low, Chinyao; Hsueh Chen, Ya

    2012-12-01

    As cloud computing technology has proliferated rapidly worldwide, there has been a trend toward adopting cloud-based hospital information systems (CHISs). This study examines the critical criteria for selecting the CHISs outsourcing provider. The fuzzy Delphi method (FDM) is used to evaluate the primary indicator collected from 188 useable responses at a working hospital in Taiwan. Moreover, the fuzzy analytic hierarchy process (FAHP) is employed to calculate the weights of these criteria and establish a fuzzy multi-criteria model of CHISs outsourcing provider selection from 42 experts. The results indicate that the five most critical criteria related to CHISs outsourcing provider selection are (1) system function, (2) service quality, (3) integration, (4) professionalism, and (5) economics. This study may contribute to understanding how cloud-based hospital systems can reinforce content design and offer a way to compete in the field by developing more appropriate systems. PMID:22366976

  17. mPano: cloud-based mobile panorama view from single picture

    NASA Astrophysics Data System (ADS)

    Li, Hongzhi; Zhu, Wenwu

    2013-09-01

    Panorama view provides people an informative and natural user experience to represent the whole scene. The advances on mobile augmented reality, mobile-cloud computing, and mobile internet can enable panorama view on mobile phone with new functionalities, such as anytime anywhere query where a landmark picture is and what the whole scene looks like. To generate and explore panorama view on mobile devices faces significant challenges due to the limitations of computing capacity, battery life, and memory size of mobile phones, as well as the bandwidth of mobile Internet connection. To address the challenges, this paper presents a novel cloud-based mobile panorama view system that can generate and view panorama-view on mobile devices from a single picture, namely "Pano". In our system, first, we propose a novel iterative multi-modal image retrieval (IMIR) approach to get spatially adjacent images using both tag and content information from the single picture. Second, we propose a cloud-based parallel server synthing approach to generate panorama view in cloud, against today's local-client synthing approach that is almost impossible for mobile phones. Third, we propose predictive-cache solution to reduce latency of image delivery from cloud server to the mobile client. We have built a real mobile panorama view system and perform experiments. The experimental results demonstrated the effectiveness of our system and the proposed key component technologies, especially for landmark images.

  18. From pixels to patches: a cloud classification method based on a bag of micro-structures

    NASA Astrophysics Data System (ADS)

    Li, Qingyong; Zhang, Zhen; Lu, Weitao; Yang, Jun; Ma, Ying; Yao, Wen

    2016-03-01

    Automatic cloud classification has attracted more and more attention with the increasing development of whole sky imagers, but it is still in progress for ground-based cloud observation. This paper proposes a new cloud classification method, named bag of micro-structures (BoMS). This method treats an all-sky image as a collection of micro-structures mapped from image patches, rather than a collection of pixels. It represents the image with a weighted histogram of micro-structures. Based on this representation, BoMS recognizes the cloud class of the image by a support vector machine (SVM) classifier. Five classes of sky condition are identified: cirriform, cumuliform, stratiform, clear sky, and mixed cloudiness. BoMS is evaluated on a large data set, which contains 5000 all-sky images captured by a total-sky cloud imager located in Tibet (29.25° N, 88.88° E). BoMS achieves an accuracy of 90.9 % for 10-fold cross-validation, and it outperforms state-of-the-art methods with an increase of 19 %. Furthermore, influence of key parameters in BoMS is investigated to verify their robustness.

  19. Curb-Based Street Floor Extraction from Mobile Terrestrial LIDAR Point Cloud

    NASA Astrophysics Data System (ADS)

    Ibrahim, S.; Lichti, D.

    2012-07-01

    Mobile terrestrial laser scanners (MTLS) produce huge 3D point clouds describing the terrestrial surface, from which objects like different street furniture can be generated. Extraction and modelling of the street curb and the street floor from MTLS point clouds is important for many applications such as right-of-way asset inventory, road maintenance and city planning. The proposed pipeline for the curb and street floor extraction consists of a sequence of five steps: organizing the 3D point cloud and nearest neighbour search; 3D density-based segmentation to segment the ground; morphological analysis to refine out the ground segment; derivative of Gaussian filtering to detect the curb; solving the travelling salesman problem to form a closed polygon of the curb and point-inpolygon test to extract the street floor. Two mobile laser scanning datasets of different scenes are tested with the proposed pipeline. The results of the extracted curb and street floor are evaluated based on a truth data. The obtained detection rates for the extracted street floor for the datasets are 95% and 96.53%. This study presents a novel approach to the detection and extraction of the road curb and the street floor from unorganized 3D point clouds captured by MTLS. It utilizes only the 3D coordinates of the point cloud.

  20. Unified height systems after GOCE

    NASA Astrophysics Data System (ADS)

    Rummel, Reiner; Gruber, Thomas; Sideris, Michael; Rangelova, Elena; Woodworth, Phil; Hughes, Chris; Ihde, Johannes; Liebsch, Gunter; Rülke, Axel; Gerlach, Christian; Haagmans, Roger

    2015-04-01

    The objectives of global height unification are twofold, (1) the realization of accurate geopotential numbers C together with their standard deviation σ(C) at a selected set of stations (datum points of national height systems, geodetic fundamental stations (IERS), primary tide gauges (PSMSL) and primary reference clocks (IERS)) and (2) the determination of height off-sets between all existing regional/national height systems and one global height reference. In the future the primary method of height determination will be GPS-levelling with very stringent requirements concerning the consistency of the positioning and the gravity potential difference part. Consistency is required in terms of the applied standards (ITRF, zero tide system, geodetic reference system). Geopotential differences will be based on a next generation geopotential model combining GOCE and GRACE and a best possible collection of global terrestrial and altimetric gravity and topographic data. Ultimately, the envisaged accuracy of height unification is about 10 cm2/s2 (or 1cm). At the moment, in well surveyed regions, an accuracy of about 40 to 60 cm2/s2 (or 4 to 6cm) is attainable. Objective One can be realized by straight forward computation of geopotential numbers C, i.e. geopotential differences relative to an adopted height reference. No adjustment is required for this. Objective Two, the unification of existing height systems is achieved by employing a least-squares adjustment based on the GBVP-approach. In order to attain a non-singular solution, this requires for each included datum zone at least one geo-referenced station per zone, i.e. its ellipsoidal height h and, in addition, the corresponding physical height H (geopotential number, normal height, orthometric height, etc.). Changes in geopotential numbers of consecutive realizations reflect (1) temporal changes of station heights, (2) improvements or changes of the applied geopotential (or geoid) model and (3) improvements of the adopted standards and methodology. This procedure will allow bringing all included stations into one and the same height datum. In sparsely surveyed regions of our planet the uncertainty of height off-sets may be at the level of 20 to 40cm (with extreme values up to 1m). In coastal regions, applying ocean levelling, these numbers may be improved. Ocean levelling is the combination of a "best" ocean topography model with either an altimetric mean sea surface or, at tide gauges, mean sea level as derived from a combination of tide gauge recording and GNSS positioning. The classical geoid definition and realization is operational at the level of a decimeter but poses significant theoretical and operational challenges at the sub-decimetre level.

  1. The Cloud-Based Integrated Data Viewer (IDV)

    NASA Astrophysics Data System (ADS)

    Fisher, Ward

    2015-04-01

    Maintaining software compatibility across new computing environments and the associated underlying hardware is a common problem for software engineers and scientific programmers. While there are a suite of tools and methodologies used in traditional software engineering environments to mitigate this issue, they are typically ignored by developers lacking a background in software engineering. The result is a large body of software which is simultaneously critical and difficult to maintain. Visualization software is particularly vulnerable to this problem, given the inherent dependency on particular graphics hardware and software API's. The advent of cloud computing has provided a solution to this problem, which was not previously practical on a large scale; Application Streaming. This technology allows a program to run entirely on a remote virtual machine while still allowing for interactivity and dynamic visualizations, with little-to-no re-engineering required. Through application streaming we are able to bring the same visualization to a desktop, a netbook, a smartphone, and the next generation of hardware, whatever it may be. Unidata has been able to harness Application Streaming to provide a tablet-compatible version of our visualization software, the Integrated Data Viewer (IDV). This work will examine the challenges associated with adapting the IDV to an application streaming platform, and include a brief discussion of the underlying technologies involved. We will also discuss the differences between local software and software-as-a-service.

  2. Cloud microphysical background for the Israel-4 cloud seeding experiment

    NASA Astrophysics Data System (ADS)

    Freud, Eyal; Koussevitzky, Hagai; Goren, Tom; Rosenfeld, Daniel

    2015-05-01

    The modest amount of rainfall in Israel occurs in winter storms that bring convective clouds from the Mediterranean Sea when the cold post frontal air interacts with its relatively warm surface. These clouds were seeded in the Israel-1 and Israel-2 cloud glaciogenic seeding experiments, which have shown statistically significant positive effect of added rainfall of at least 13% in northern Israel, whereas the Israel-3 experiment showed no added rainfall in the south. This was followed by operational seeding in the north since 1975. The lack of physical evidence for the causes of the positive effects in the north caused a lack of confidence in the statistical results and led to the Israel-4 randomized seeding experiment in northern Israel. This experiment started in the winter of 2013/14. The main difference from the previous experiments is the focus on the orographic clouds in the catchment of the Sea of Galilee. The decision to commence the experiment was partially based on evidence supporting the existence of seeding potential, which is reported here. Aircraft and satellite microphysical and dynamic measurements of the clouds document the critical roles of aerosols, especially sea spray, on cloud microstructure and precipitation forming processes. It was found that the convective clouds over sea and coastal areas are naturally seeded hygroscopically by sea spray and develop precipitation efficiently. The diminution of the large sea spray aerosols farther inland along with the increase in aerosol concentrations causes the clouds to develop precipitation more slowly. The short time available for the precipitation forming processes in super-cooled orographic clouds over the Golan Heights farthest inland represents the best glaciogenic seeding potential.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  4. Cloud Property Retrieval Products for Graciosa Island, Azores

    DOE Data Explorer

    Dong, Xiquan

    2014-05-05

    The motivation for developing this product was to use the Dong et al. 1998 method to retrieve cloud microphysical properties, such as cloud droplet effective radius, cloud droplets number concentration, and optical thickness. These retrieved properties have been used to validate the satellite retrieval, and evaluate the climate simulations and reanalyses. We had been using this method to retrieve cloud microphysical properties over ARM SGP and NSA sites. We also modified the method for the AMF at Shouxian, China and some IOPs, e.g. ARM IOP at SGP in March, 2000. The ARSCL data from ARM data archive over the SGP and NSA have been used to determine the cloud boundary and cloud phase. For these ARM permanent sites, the ARSCL data was developed based on MMCR measurements, however, there were no data available at the Azores field campaign. We followed the steps to generate this derived product and also include the MPLCMASK cloud retrievals to determine the most accurate cloud boundaries, including the thin cirrus clouds that WACR may under-detect. We use these as input to retrieve the cloud microphysical properties. Due to the different temporal resolutions of the derived cloud boundary heights product and the cloud properties product, we submit them as two separate netcdf files.

  5. RBioCloud: A Light-Weight Framework for Bioconductor and R-based Jobs on the Cloud.

    PubMed

    Varghese, Blesson; Patel, Ishan; Barker, Adam

    2015-01-01

    Large-scale ad hoc analytics of genomic data is popular using the R-programming language supported by over 700 software packages provided by Bioconductor. More recently, analytical jobs are benefitting from on-demand computing and storage, their scalability and their low maintenance cost, all of which are offered by the cloud. While biologists and bioinformaticists can take an analytical job and execute it on their personal workstations, it remains challenging to seamlessly execute the job on the cloud infrastructure without extensive knowledge of the cloud dashboard. How analytical jobs can not only with minimum effort be executed on the cloud, but also how both the resources and data required by the job can be managed is explored in this paper. An open-source light-weight framework for executing R-scripts using Bioconductor packages, referred to as `RBioCloud', is designed and developed. RBioCloud offers a set of simple command-line tools for managing the cloud resources, the data and the execution of the job. Three biological test cases validate the feasibility of RBioCloud. The framework is available from http://www.rbiocloud.com. PMID:26357328

  6. QoS-aware health monitoring system using cloud-based WBANs.

    PubMed

    Almashaqbeh, Ghada; Hayajneh, Thaier; Vasilakos, Athanasios V; Mohd, Bassam J

    2014-10-01

    Wireless Body Area Networks (WBANs) are amongst the best options for remote health monitoring. However, as standalone systems WBANs have many limitations due to the large amount of processed data, mobility of monitored users, and the network coverage area. Integrating WBANs with cloud computing provides effective solutions to these problems and promotes the performance of WBANs based systems. Accordingly, in this paper we propose a cloud-based real-time remote health monitoring system for tracking the health status of non-hospitalized patients while practicing their daily activities. Compared with existing cloud-based WBAN frameworks, we divide the cloud into local one, that includes the monitored users and local medical staff, and a global one that includes the outer world. The performance of the proposed framework is optimized by reducing congestion, interference, and data delivery delay while supporting users' mobility. Several novel techniques and algorithms are proposed to accomplish our objective. First, the concept of data classification and aggregation is utilized to avoid clogging the network with unnecessary data traffic. Second, a dynamic channel assignment policy is developed to distribute the WBANs associated with the users on the available frequency channels to manage interference. Third, a delay-aware routing metric is proposed to be used by the local cloud in its multi-hop communication to speed up the reporting process of the health-related data. Fourth, the delay-aware metric is further utilized by the association protocols used by the WBANs to connect with the local cloud. Finally, the system with all the proposed techniques and algorithms is evaluated using extensive ns-2 simulations. The simulation results show superior performance of the proposed architecture in optimizing the end-to-end delay, handling the increased interference levels, maximizing the network capacity, and tracking user's mobility. PMID:25123456

  7. Standing adult human phantoms based on 10th, 50th and 90th mass and height percentiles of male and female Caucasian populations

    NASA Astrophysics Data System (ADS)

    Cassola, V. F.; Milian, F. M.; Kramer, R.; de Oliveira Lira, C. A. B.; Khoury, H. J.

    2011-07-01

    Computational anthropomorphic human phantoms are useful tools developed for the calculation of absorbed or equivalent dose to radiosensitive organs and tissues of the human body. The problem is, however, that, strictly speaking, the results can be applied only to a person who has the same anatomy as the phantom, while for a person with different body mass and/or standing height the data could be wrong. In order to improve this situation for many areas in radiological protection, this study developed 18 anthropometric standing adult human phantoms, nine models per gender, as a function of the 10th, 50th and 90th mass and height percentiles of Caucasian populations. The anthropometric target parameters for body mass, standing height and other body measures were extracted from PeopleSize, a well-known software package used in the area of ergonomics. The phantoms were developed based on the assumption of a constant body-mass index for a given mass percentile and for different heights. For a given height, increase or decrease of body mass was considered to reflect mainly the change of subcutaneous adipose tissue mass, i.e. that organ masses were not changed. Organ mass scaling as a function of height was based on information extracted from autopsy data. The methods used here were compared with those used in other studies, anatomically as well as dosimetrically. For external exposure, the results show that equivalent dose decreases with increasing body mass for organs and tissues located below the subcutaneous adipose tissue layer, such as liver, colon, stomach, etc, while for organs located at the surface, such as breasts, testes and skin, the equivalent dose increases or remains constant with increasing body mass due to weak attenuation and more scatter radiation caused by the increasing adipose tissue mass. Changes of standing height have little influence on the equivalent dose to organs and tissues from external exposure. Specific absorbed fractions (SAFs) have also been calculated with the 18 anthropometric phantoms. The results show that SAFs decrease with increasing height and increase with increasing body mass. The calculated data suggest that changes of the body mass may have a significant effect on equivalent doses, primarily for external exposure to organs and tissue located below the adipose tissue layer, while for superficial organs, for changes of height and for internal exposures the effects on equivalent dose are small to moderate.

  8. GEWEX Cloud System Study (GCSS) cirrus cloud working group: development of an observation-based case study for model evaluation

    NASA Astrophysics Data System (ADS)

    Yang, H.; Dobbie, S.; Mace, G. G.; Ross, A.; Quante, M.

    2012-06-01

    The GCSS working group on cirrus focuses on an inter-comparison of model simulations ranging from very detailed microphysical and dynamical models through to general circulation models (GCMs). The past GCSS cirrus cloud inter-comparison highlighted the wide range in modelling results that was a surprise to the modelling community. That inter-comparison was idealised and, therefore, a key issue was that it did not benefit from observations to help distinguish between model performances. In this work, we aim to address this key issue by developing an observationally based case study to be used for the GCSS cirrus modelling inter-comparison study. We focused on developing a case that had sufficient observations with which to evaluate models, to help identify which models in the inter-comparison are performing well and highlight areas for model development. Furthermore, it will provide a base case for future model comparisons or testing of new or updated models. This paper outlines the modelling case development and the inter-comparison results will be presented in a follow-on paper. The case was based on the 9 March 2000 Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) during an intensive observation period (IOP). The case was developed utilising various observations including ARM SGP remote sensing including the MilliMeter Cloud Radar (MMCR), radiometers, radiosondes, aircraft observations, satellite observations, objective analysis and complemented with results from the Rapid Update Cycle (RUC) model as well as bespoke gravity wave simulations used to provide the best estimate for large scale forcing. The retrievals of ice water content, ice number concentration and fall velocity provide several constraints to evaluate model performances. Initial testing of the case has been reported using the UK Met Office Large Eddy Simulation Model (LEM) which suggests the case is appropriate for the model inter-comparison study. To our knowledge, this case offers the most detailed case study for cirrus comparison available and we anticipate this will offer significant benefits over past comparisons which have mostly been loosely based on observations.

  9. Measurement-based estimates of direct radiative effects of absorbing aerosols above clouds

    NASA Astrophysics Data System (ADS)

    Feng, Nan; Christopher, Sundar A.

    2015-07-01

    The elevated layers of absorbing smoke aerosols from western African (e.g., Gabon and Congo) biomass burning activities have been frequently observed above low-level stratocumulus clouds off the African coast, which presents an excellent natural laboratory for studying the effects of aerosols above clouds (AAC) on regional energy balance in tropical and subtropical environments. Using spatially and temporally collocated Moderate Resolution Imaging Spectroradiometer, Ozone Monitoring Instrument (OMI), and Clouds and the Earth's Radiant Energy System data sets, the top-of-atmosphere shortwave aerosol direct shortwave radiative effects (ARE) of absorbing aerosols above low-level water clouds in the southeast Atlantic Ocean was examined in this study. The regional averaged instantaneous ARE has been estimated to be 36.7 ± 20.5 Wm-2 (regional mean ± standard deviation) along with a mean positive OMI Aerosol Index at 1.3 in August 2006 based on multisensors measurements. The highest magnitude of instantaneous ARE can even reach 138.2 Wm-2. We assess that the 660 nm cloud optical depth (COD) values of 8-12 is the critical value above (below) which aerosol absorption (scattering) effect dominates and further produces positive (negative) ARE values. The results further show that ARE values are more sensitive to aerosols above lower COD values than cases for higher COD values. This is among the first studies to provide quantitative estimates of shortwave ARE due to AAC events from an observational perspective.

  10. Three-dimensional reconstruction method of Tang Dynasty building based on point clouds

    NASA Astrophysics Data System (ADS)

    Wang, Yinghui; Zhang, Huanhuan; Zhao, Yanni; Hao, Wen; Ning, Xiaojuan; Shi, Zhenghao; Zhao, Minghua

    2015-12-01

    We present a method to reconstruct the three-dimensional (3-D) Tang Dynasty building model from raw point clouds. Different from previous building modeling techniques, our method is developed for the Tang Dynasty building which does not exhibit planar primitives, facades, and repetitive structural elements as residential low- or high-rise buildings. The proposed method utilizes the structural property of the Tang Dynasty building to process the original point clouds. First, the raw point clouds are sliced into many parallel layers to generate a top-bottom hierarchical structure, and each layer is resampled to achieve a subset purification of 3-D point clouds. In addition, a series of different building components of the building are recognized by clustering these purifications of 3-D point clouds. In particular, we get the tree-structured topology of these different building components during slicing and clustering. Second, different solutions are explored to reconstruct its 3-D model for different building components. The overall model of building can be gotten based on the building components and tree-structured topology. Experimental results demonstrate that the proposed method is more efficient for generating a high realistic 3-D model of the Tang Dynasty building.

  11. A Tag Cloud-Based Visualization for Geo-Referenced Text Information

    NASA Astrophysics Data System (ADS)

    Li, X.; Hua, Y.-X.; Zhao, J.-X.; Wang, L.-N.; Wang, P.

    2013-11-01

    Large amounts of geo-referenced text information such as messages from microblog websites are continuously becoming more popular. In this paper, we introduce a new visualization method based on tag clouds for geo-referenced text information. We process large amounts of geo-referenced text, using several visual metaphors including tag clouds, for the exploration of information on maps, instead of using just conventional cartographic approaches. The results show that this method can be useful for presentation and exploration of such geo-referenced text information.

  12. Cloud-Based Applications for Organizing and Reviewing Plastic Surgery Content

    PubMed Central

    Luan, Anna; Momeni, Arash; Lee, Gordon K.

    2015-01-01

    Cloud-based applications including Box, Dropbox, Google Drive, Evernote, Notability, and Zotero are available for smartphones, tablets, and laptops and have revolutionized the manner in which medical students and surgeons read and utilize plastic surgery literature. Here we provide an overview of the use of Cloud computing in practice and propose an algorithm for organizing the vast amount of plastic surgery literature. Given the incredible amount of data being produced in plastic surgery and other surgical subspecialties, it is prudent for plastic surgeons to lead the process of providing solutions for the efficient organization and effective integration of the ever-increasing data into clinical practice. PMID:26576208

  13. Cloud-Based Applications for Organizing and Reviewing Plastic Surgery Content.

    PubMed

    Luan, Anna; Momeni, Arash; Lee, Gordon K; Galvez, Michael G

    2015-01-01

    Cloud-based applications including Box, Dropbox, Google Drive, Evernote, Notability, and Zotero are available for smartphones, tablets, and laptops and have revolutionized the manner in which medical students and surgeons read and utilize plastic surgery literature. Here we provide an overview of the use of Cloud computing in practice and propose an algorithm for organizing the vast amount of plastic surgery literature. Given the incredible amount of data being produced in plastic surgery and other surgical subspecialties, it is prudent for plastic surgeons to lead the process of providing solutions for the efficient organization and effective integration of the ever-increasing data into clinical practice. PMID:26576208

  14. Use of Cloud-Based Graphic Narrative Software in Medical Ethics Teaching

    ERIC Educational Resources Information Center

    Weber, Alan S.

    2015-01-01

    Although used as a common pedagogical tool in K-12 education, online graphic narrative ("comics") software has not generally been incorporated into advanced professional or technical education. This contribution reports preliminary data from a study on the use of cloud-based graphics software Pixton.com to teach basic medical ethics…

  15. Using a Cloud-Based Computing Environment to Support Teacher Training on Common Core Implementation

    ERIC Educational Resources Information Center

    Robertson, Cory

    2013-01-01

    A cloud-based computing environment, Google Apps for Education (GAFE), has provided the Anaheim City School District (ACSD) a comprehensive and collaborative avenue for creating, sharing, and editing documents, calendars, and social networking communities. With this environment, teachers and district staff at ACSD are able to utilize the deep

  16. Using a Cloud-Based Computing Environment to Support Teacher Training on Common Core Implementation

    ERIC Educational Resources Information Center

    Robertson, Cory

    2013-01-01

    A cloud-based computing environment, Google Apps for Education (GAFE), has provided the Anaheim City School District (ACSD) a comprehensive and collaborative avenue for creating, sharing, and editing documents, calendars, and social networking communities. With this environment, teachers and district staff at ACSD are able to utilize the deep…

  17. Exploring Architecture Options for a Federated, Cloud-based System Biology Knowledgebase

    SciTech Connect

    Gorton, Ian; Liu, Yan; Yin, Jian

    2010-12-02

    This paper evaluates various cloud computing technologies and resources for building a system biology knowledge base system. This system will host a huge amount of data and contain a flexible sets of workflows to operate on these data. It will enable system biologist to share their data and algorithms to allow research results to be reproduced, shared, and reused across the system biology community.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  19. Nature of the ultraviolet absorber in the Venus clouds - Inferences based on Pioneer Venus data

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.; Ragent, B.; Boese, R.; Tomasko, M. G.; Blamont, J.; Knollenberg, R. G.; Esposito, L. W.; Stewart, A. I.; Travis, L.

    1979-01-01

    Several photometric measurements of Venus made from the Pioneer Venus orbiter and probes indicate that solar near-ultraviolet radiation is being absorbed throughout much of the main cloud region, but little above the clouds or within the first one or two optical depths. Radiative transfer calculations were carried out to simulate both Pioneer Venus and ground-based data for a number of proposed cloud compositions. This comparison rules out models invoking nitrogen dioxide, meteoritic material, and volatile metals as the source of the ultraviolet absorption. Models involving either small (approximately 1 micrometer) or large (approximately 10 micrometers) sulfur particles have same serious difficulties, while ones invoking sulfur dioxide gas appear to be promising.

  20. A point-cloud-based multiview stereo algorithm for free-viewpoint video.

    PubMed

    Liu, Yebin; Dai, Qionghai; Xu, Wenli

    2010-01-01

    This paper presents a robust multiview stereo (MVS) algorithm for free-viewpoint video. Our MVS scheme is totally point-cloud-based and consists of three stages: point cloud extraction, merging, and meshing. To guarantee reconstruction accuracy, point clouds are first extracted according to a stereo matching metric which is robust to noise, occlusion, and lack of texture. Visual hull information, frontier points, and implicit points are then detected and fused with point fidelity information in the merging and meshing steps. All aspects of our method are designed to counteract potential challenges in MVS data sets for accurate and complete model reconstruction. Experimental results demonstrate that our technique produces the most competitive performance among current algorithms under sparse viewpoint setups according to both static and motion MVS data sets. PMID:20224136

  1. Ship detection from high-resolution imagery based on land masking and cloud filtering

    NASA Astrophysics Data System (ADS)

    Jin, Tianming; Zhang, Junping

    2015-12-01

    High resolution satellite images play an important role in target detection application presently. This article focuses on the ship target detection from the high resolution panchromatic images. Taking advantage of geographic information such as the coastline vector data provided by NOAA Medium Resolution Coastline program, the land region is masked which is a main noise source in ship detection process. After that, the algorithm tries to deal with the cloud noise which appears frequently in the ocean satellite images, which is another reason for false alarm. Based on the analysis of cloud noise's feature in frequency domain, we introduce a windowed noise filter to get rid of the cloud noise. With the help of morphological processing algorithms adapted to target detection, we are able to acquire ship targets in fine shapes. In addition, we display the extracted information such as length and width of ship targets in a user-friendly way i.e. a KML file interpreted by Google Earth.

  2. CIMIDx: Prototype for a Cloud-Based System to Support Intelligent Medical Image Diagnosis With Efficiency

    PubMed Central

    2015-01-01

    Background The Internet has greatly enhanced health care, helping patients stay up-to-date on medical issues and general knowledge. Many cancer patients use the Internet for cancer diagnosis and related information. Recently, cloud computing has emerged as a new way of delivering health services but currently, there is no generic and fully automated cloud-based self-management intervention for breast cancer patients, as practical guidelines are lacking. Objective We investigated the prevalence and predictors of cloud use for medical diagnosis among women with breast cancer to gain insight into meaningful usage parameters to evaluate the use of generic, fully automated cloud-based self-intervention, by assessing how breast cancer survivors use a generic self-management model. The goal of this study was implemented and evaluated with a new prototype called “CIMIDx”, based on representative association rules that support the diagnosis of medical images (mammograms). Methods The proposed Cloud-Based System Support Intelligent Medical Image Diagnosis (CIMIDx) prototype includes two modules. The first is the design and development of the CIMIDx training and test cloud services. Deployed in the cloud, the prototype can be used for diagnosis and screening mammography by assessing the cancers detected, tumor sizes, histology, and stage of classification accuracy. To analyze the prototype’s classification accuracy, we conducted an experiment with data provided by clients. Second, by monitoring cloud server requests, the CIMIDx usage statistics were recorded for the cloud-based self-intervention groups. We conducted an evaluation of the CIMIDx cloud service usage, in which browsing functionalities were evaluated from the end-user’s perspective. Results We performed several experiments to validate the CIMIDx prototype for breast health issues. The first set of experiments evaluated the diagnostic performance of the CIMIDx framework. We collected medical information from 150 breast cancer survivors from hospitals and health centers. The CIMIDx prototype achieved high sensitivity of up to 99.29%, and accuracy of up to 98%. The second set of experiments evaluated CIMIDx use for breast health issues, using t tests and Pearson chi-square tests to assess differences, and binary logistic regression to estimate the odds ratio (OR) for the predictors’ use of CIMIDx. For the prototype usage statistics for the same 150 breast cancer survivors, we interviewed 114 (76.0%), through self-report questionnaires from CIMIDx blogs. The frequency of log-ins/person ranged from 0 to 30, total duration/person from 0 to 1500 minutes (25 hours). The 114 participants continued logging in to all phases, resulting in an intervention adherence rate of 44.3% (95% CI 33.2-55.9). The overall performance of the prototype for the good category, reported usefulness of the prototype (P=.77), overall satisfaction of the prototype (P=.31), ease of navigation (P=.89), user friendliness evaluation (P=.31), and overall satisfaction (P=.31). Positive evaluations given by 100 participants via a Web-based questionnaire supported our hypothesis. Conclusions The present study shows that women felt favorably about the use of a generic fully automated cloud-based self- management prototype. The study also demonstrated that the CIMIDx prototype resulted in the detection of more cancers in screening and diagnosing patients, with an increased accuracy rate. PMID:25830608

  3. Applications of stereoscopic height computations from dual geosynchronous satellite data/joint NASA-Japan stereo project

    NASA Technical Reports Server (NTRS)

    Fujita, T. T.; Dodge, J. C.

    1982-01-01

    Stereoscopic heights of the top of an Oklahoma thunderstorm were computed, finding that high cloud tops are not always characterized by very cold IR temperature. The identical method was also applied to the computation of stereo heights based on GOES West and GMS stereo pairs obtained under the NASA-JAPAN cooperative program. It was found that stereo techniques are extremely useful in understanding the structure of thunderstorms in the United States, as well as that of hurricanes over the South Pacific.

  4. Temperature dependent electron effective mass and barrier height in HfO2 based metal/oxide/metal devices

    NASA Astrophysics Data System (ADS)

    El Kamel, F.

    2015-07-01

    Electrical measurements are realized on Cu/HfO2/Pt capacitors to extract the electron effective mass in HfO2 and the barrier height at the Cu/HfO2 interface. The dominant conduction mechanisms are found to be the Schottky emission at medium voltages and the Fowler-Nordheim tunneling at high voltages. Previous research has usually been carried out by assuming a constant value for either the electron effective mass in oxide or the interfacial potential barrier height to determine the other parameter. However, in contrast to that general practice, an iterative method was proposed in the present study to determine, at the same time, the electron effective mass in HfO2 and the barrier height at the Cu/HfO2 interface without making any prior assumption about their values. The temperature dependence of these two parameters was also studied in the 298-423 K range. It is found that they strongly vary with temperature. The effective mass decreases quadratically with temperature, while the barrier height increases linearly with temperature.

  5. 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.

  6. Characteristics of cirrus clouds in the tropical lower stratosphere

    NASA Astrophysics Data System (ADS)

    Iwasaki, Suginori; Luo, Zhengzhao Johnny; Kubota, Hisayuki; Shibata, Takashi; Okamoto, Hajime; Ishimoto, Hiroshi

    2015-10-01

    A unique type of cloud in the tropical lower stratosphere, which we call "stratospheric cirrus", is described in this study. Stratospheric cirrus clouds are generally detached from overshooting deep convection and are much smaller than subvisual cirrus often observed near the tropical tropopause. We analyzed two cases of stratospheric cirrus in the tropical and subtropical lower stratosphere captured by the space-borne lidar, Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Both cases occurred 2-3 hours after the most active phase of the nearby convective cloud clusters. Case 1 has a double-layer structure above the cold point height (CPH); the CPH and two cloud top heights are, respectively, 17.8, 18.9, and 19.9 km. Case 2 has a single cloud layer where CPH and the cloud top height are, respectively, 16.5 and 18.7 km. The mode radius and ice water content of the stratospheric cirrus clouds are estimated to be 4-10 μm and 0.2-0.8 mg/m3 based on the radar-lidar method and consideration of the cloud particle terminal velocity. Comparisons with previous numerical model simulation studies suggest that the double-layer stratospheric cirrus clouds are likely from an overshooting plume, pushed up into the stratosphere in an overshoot when warm stratospheric air is inhomogeneously mixed with cold overshooting air. The single-layer stratospheric cirrus cloud is associated with some non-negligible wind shear, so it could be a jumping cirrus cloud, although we cannot rule out the possibility that it came from an overshooting plume because of the similarity in cloud characteristics and morphology between the two cases. Guided by the case studies, an automatic algorithm was developed to select stratospheric cirrus clouds for global survey and statistical analysis. A total of four years of CALIPSO and space-borne cloud radar (CloudSat) data were analyzed. Statistical analysis suggests that stratospheric cirrus clouds occur on the order of 3.0 × 103 times a year between 30 °S and 30 °N. Many of the stratospheric cirrus clouds are found in the pre-monsoon season in the South and Southeast Asia, where convection is deep and intense.

  7. Cloud Control

    ERIC Educational Resources Information Center

    Weinstein, Margery

    2012-01-01

    Your learning curriculum needs a new technological platform, but you don't have the expertise or IT equipment to pull it off in-house. The answer is a learning system that exists online, "in the cloud," where learners can access it anywhere, anytime. For trainers, cloud-based coursework often means greater ease of instruction resulting in greater

  8. Cloud Control

    ERIC Educational Resources Information Center

    Weinstein, Margery

    2012-01-01

    Your learning curriculum needs a new technological platform, but you don't have the expertise or IT equipment to pull it off in-house. The answer is a learning system that exists online, "in the cloud," where learners can access it anywhere, anytime. For trainers, cloud-based coursework often means greater ease of instruction resulting in greater…