WorldWideScience

Sample records for airborne p-band ice

  1. Design of an airborne P-band ice sounding radar

    DEFF Research Database (Denmark)

    Dall, Jørgen; Skou, Niels; Kusk, Anders;

    2006-01-01

    This paper presents the top-level design of an airborne, P-band ice sounding radar under development at the Technical University of Denmark. The ice sounder is intended to help gaining experience with the electromagnetic properties of the Antarctic ice sheet at P-band. A secondary objective is to...... digital signal generator, a microstrip antenna array, a conventional RF-architecture with a central transmitter and two receive channels as well as internal calibration loops. In 2008 the first data acquisition campaign will take place in Greenland....

  2. P-sounder: an airborne P-band ice sounding radar

    DEFF Research Database (Denmark)

    Dall, Jørgen; Skou, Niels; Kusk, Anders;

    2007-01-01

    This paper presents the top-level design of an airborne, P-band ice sounding radar under development at the Technical University of Denmark. The ice sounder is intended to provide more information on the electromagnetic properties of the Antarctic ice sheet at P-band. A secondary objective is to ...... digital signal generator, a microstrip antenna array, a conventional RF-architecture with a central transmitter, four receivers, and internal calibration loops. In 2008 the first data acquisition campaign will take place in Greenland....

  3. P-band polarimetric ice sounder: concept and first results

    DEFF Research Database (Denmark)

    Dall, Jørgen; Hernández, Carlos Cilla; Kristensen, Steen Savstrup;

    2008-01-01

    direction. In May 2008, a proof-of-concept campaign was organized in Greenland, where data were acquired over the ice sheet. The system proved capable of detecting the bedrock under 3 km thick ice and of mapping the internal ice layers down to a depth of at least 1.3 km. In this paper, the system concept......ESA has assigned the Technical University of Denmark to develop an airborne P-band ice sounding radar demonstrator. The intention is to obtain a better understanding of the electromagnetic properties of the Antarctic ice sheet at P-band and to test novel ice sounding techniques in preparation...... for a potential spaceborne ice sounding radar. The airborne system is a coherent, high-resolution and fully polarimetric radar. Aperture synthesis is applied in the along track direction and an experimental surface clutter suppression technique based on a multi-aperture antenna can be applied in the across track...

  4. P-band radar ice sounding in Antarctica

    DEFF Research Database (Denmark)

    Dall, Jørgen; Kusk, Anders; Kristensen, Steen Savstrup; Nielsen, Ulrik; Forsberg, René; Lin, C.-C.; Gebert, N.; Casal, T.; Davidson, M.; Bekaert, D.; Buck, C.

    In February 2011, the Polarimetric Airborne Radar Ice Sounder (POLARIS) was flown in Antarctica in order to assess the feasibility of a potential space-based radar ice sounding mission. The campaign has demonstrated that the basal return is detectable in areas with up to 3 km thick cold ice, in...

  5. Single and Multipolarimetric P-Band SAR Tomography of Subsurface Ice Structure

    DEFF Research Database (Denmark)

    Banda, Francesco; Dall, Jørgen; Tebaldini, Stefano

    2016-01-01

    was motivated by the fact that cryospheric remote sensing is of fundamental importance in order to understand more in depth the morphology and the dynamic processes regulating ice sheets. The main objective of the tomographic experiment of the campaign herein discussed was indeed to assess the......In this paper, first results concerning the characterization of the subsurface of ice sheets and glaciers through single and multipolarization synthetic aperture radar (SAR) tomography (TomoSAR) are illustrated. To this aim, the processing of data acquired in the framework of the European Space...... capability of P-band SAR to retrieve any information about ice subsurface structure. Imaging has been achieved through TomoSAR techniques, applied to airborne multibaseline data acquired in the southwest of Greenland. Different imaging approaches are compared, and the main results achieved are presented: It...

  6. Design of a Small, Low Cost, P-Band Airborne Polarimetric Synthetic Aperture Radar

    NARCIS (Netherlands)

    Figueras i Ventura, J.; Hoogeboom, P.

    2004-01-01

    A preliminary study of the design of a small, low cost, P-band airborne, polarimetric Synthetic Aperture Radar desired by the Wageningen University and the Borneo Orangutan Survival Foundation (BOS) to carry out forest biomass monitoring in Indonesia is presented. The requirements of the application

  7. Polarimetric ice sounding at P-band: First results

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2009-01-01

    For polar ice sheets valuable stress and strain information can be deduced from the crystal orientation fabric (COF) and its prevailing c-axis alignment. Polarimetric radio echo sounding is a promising technique to measure the anisotropic electromagnetic propagation and reflection properties...

  8. Development of an airborne ice sounding radar front-end

    DEFF Research Database (Denmark)

    Krozer, Viktor; Hernandez, C C; Vazquez Roy, J L;

    2007-01-01

    This paper describes the design of an airborne P-band ice sounding radar. The ice sounder design features a microstrip antenna array with a relative operating bandwidth of 20%, compact RF components, a high efficiency high-power LDMOS power amplifier with >60% power-added efficiency across a...

  9. Experimental Determination of Electromagnetic Propagation and Scattering Properties of Ice-Sheets at P-Band

    Science.gov (United States)

    Lin, Chung-Chi; Rommen, Björn; Buck, Christopher; Casal, Tania; Dall, Jørgen; Kusk, Anders; Nielsen, Ulrik; Corr, Hugh; Ginestet, Arnaud; Decerprit, Guillaume; Walker, Nick; Kristensen, Steen S.

    2014-05-01

    The electromagnetic (EM) propagation and scattering properties of the ice and its inclusions strongly affect radar reception signals in radio echo sounding of ice-sheets. In particular, those properties are very strongly dependent on the sensing frequency, with penetration depth rapidly decreasing with increasing frequency. Furthermore, the surface scattering signals, which mask the radar echoes from the depth, increases monotonically with frequency. In spite of those drawbacks, the recent interests in the use of P-band (435 MHz), as compared to the more established sensing frequencies at 60 and 150 MHz, are driven mainly by two reasons: (1) the use of a shorter wavelength improves the spatial selectivity of the sensor as a reasonably sized antenna system could generate narrow beams; (2) P-band is the lowest frequency band allocated for active sensing from space, potentially adequate for satellite-based sounding of ice-sheets. New datasets acquired by P-band radar sounders are becoming available, e.g. from the systems built by University of Kansas and ESA's POLARIS instrument built by Technical University of Denmark, thus opening a possibility to quantitatively compare the merits and drawback of ice sounding at P-band. This paper will report the result of the analysis carried out on the POLARIS data which were acquired over East Antarctica in Feb. 2011 in the frame of the Danish IceGrav 2011 campaign. More specifically, ice sounding measurements were performed over the areas of Dronning/Queen Maud Land and its coastal ice-shelves (e.g. Princess Astrid Coast and Fimbul ice-shelf), and Adelaide Island. Different ice types and regimes have been covered in order to build up a comprehensive catalogue of the ice electromagnetic properties. In addition to the POLARIS data, some in-situ data on the surface roughness, ice core data from EPICA and ice-shelf basal roughness data from an upward looking sonar experiment (Autosub Under Ice programme, 2005) have been gathered

  10. EcoSAR: NASA's P-band fully polarimetric single pass interferometric airborne radar

    Science.gov (United States)

    Osmanoglu, B.; Rincon, R. F.; Fatoyinbo, T. E.; Lee, S. K.; Sun, G.; Daniyan, O.; Harcum, M. E.

    2014-12-01

    EcoSAR is a new airborne synthetic aperture radar imaging system, developed at the NASA Goddard Space Flight Center. It is a P-band sensor that employs a non-conventional and innovative design. The EcoSAR system was designed as a multi-disciplinary instrument to image the 3-dimensional surface of the earth from a single pass platform with two antennas. EcoSAR's principal mission is to penetrate the forest canopy to return vital information about the canopy structure and estimate biomass. With a maximum bandwidth of 200 MHz in H and 120 MHz in V polarizations it can provide sub-meter resolution imagery of the study area. EcoSAR's dual antenna, 32 transmit and receive channel architecture provides a test-bed for developing new algorithms in InSAR data processing such as single pass interferometry, full polarimetry, post-processing synthesis of multiple beams, simultaneous measurement over both sides of the flight track, selectable resolution and variable incidence angle. The flexible architecture of EcoSAR will create new opportunities in radar remote sensing of forest biomass, permafrost active layer thickness, and topography mapping. EcoSAR's first test flight occurred between March 27th and April 1st, 2014 over the Andros Island in Bahamas and Corcovado and La Selva National Parks in Costa Rica. The 32 channel radar system collected about 6 TB of radar data in about 12 hours of data collection. Due to the existence of radio and TV communications in the operational frequency band, acquired data contains strong radar frequency interference, which had to be removed prior to beamforming and focusing. Precise locations of the antennas are tracked using high-rate GPS and inertial navigation units, which provide necessary information for accurate processing of the imagery. In this presentation we will present preliminary imagery collected during the test campaign, show examples of simultaneous dual track imaging, as well as a single pass interferogram. The

  11. SAR focusing of P-band ice sounding data using back-projection

    DEFF Research Database (Denmark)

    Kusk, Anders; Dall, Jørgen

    2010-01-01

    accommodated at the expense of computation time. The back-projection algorithm can be easily parallelized however, and can advantageously be implemented on a graphics processing unit (GPU). Results from using the back-projection algorithm on POLARIS ice sounder data from North Greenland shows that the quality...... of data is improved by the processing, and the performance of the GPU implementation allows for very fast focusing....

  12. ESA'S POLarimetric Airborne Radar Ice Sounder (POLARIS): design and first results

    DEFF Research Database (Denmark)

    Dall, Jørgen; Kristensen, Steen Savstrup; Krozer, Viktor;

    2010-01-01

    been encountered. ESA s POLarimetric Airborne Radar Ice Sounder (POLARIS) is intended to provide a better understanding of P-band scattering and propagation through ice sheets and to verify novel surface clutter suppression techniques in preparation for a potential space-based ice sounding mission....... POLARIS is a nadir-looking, fully polarimetric radar featuring aperture synthesis, a multi-aperture antenna for surface clutter suppression and a large dynamic range based on a shallow/deep sounding approach. The system is installed in a De Haviland DHC-6 Twin Otter aircraft, and in May 2008, a proof......-of-concept campaign was conducted in Greenland. This study outlines the design and implementation of the system, and based on first results it is concluded that in the central dry snow zone of Greenland, POLARIS can resolve shallow and deep internal ice layers, penetrate the thickest ice encountered and detect...

  13. Wideband Dual-Polarization Microstrip Patch Antenna Array for Airborne Ice Sounder

    DEFF Research Database (Denmark)

    Vazquez-Roy, Jose Luis; Krozer, Viktor; Dall, Jørgen

    2012-01-01

    We present the design and realization of an antenna array based on cavity-backed microstrip patch antenna elements, with a relative operating bandwidth exceeding 20% at a return-loss level better than 15 dB. The antenna array of four elements did not show any compromise in bandwidth. It exhibited...... sidelobe levels better than 15 dB, with a gain of around 12 dBi. Excellent agreement was achieved between measurements and predictions for the designs of both the single element and the array. This antenna is part of the European Space Agency's airborne polarimetric P-band terrestrial ice sounder....

  14. Surface Clutter Suppression Techniques Applied to P-band Multi-Channel SAR Ice Sounder Data from East Antarctica

    DEFF Research Database (Denmark)

    Lin, Chung-Chi; Bekaert, David; Gebert, Nicolas;

    Radar ice sounding allows for the retrieval of ice depth and provides information on ba-sal topography, basal conditions, flow, and layering. In the prospect of a possible future satellite ice sounding mission, surface clutters are expected to severely hamper measurement of radar ech-oes from......., Lausanne, developed and built the radiator-elements of the enhanced POLARIS. Several datasets were acquired in the multi-channel configuration during the Feb. 2011 campaign over East Antarctica. The POLARIS instrument will be briefly introduced, followed by an overview of the sounding campaign. Finally...

  15. Multichannel surface clutter suppression: East Antarctica P-band SAR ice sounding in the presence of grating lobes

    DEFF Research Database (Denmark)

    Bekaert, David; Gebert, Nicolas; Lin, Chung-Chi;

    2014-01-01

    of the receive channels were used to suppress the surface 'clutter'. However, with a channel spacing of 1.4 times the wavelength, the grating lobe imposes a limitation to the off-nadir angular range in which clutter can be effectively attenuated. Results of ice sounding over Jutulstraumen glacier are...

  16. Sea Ice Thickness, Freeboard, and Snow Depth products from Operation IceBridge Airborne Data

    Science.gov (United States)

    Kurtz, N. T.; Farrell, S. L.; Studinger, M.; Galin, N.; Harbeck, J. P.; Lindsay, R.; Onana, V. D.; Panzer, B.; Sonntag, J. G.

    2013-01-01

    The study of sea ice using airborne remote sensing platforms provides unique capabilities to measure a wide variety of sea ice properties. These measurements are useful for a variety of topics including model evaluation and improvement, assessment of satellite retrievals, and incorporation into climate data records for analysis of interannual variability and long-term trends in sea ice properties. In this paper we describe methods for the retrieval of sea ice thickness, freeboard, and snow depth using data from a multisensor suite of instruments on NASA's Operation IceBridge airborne campaign. We assess the consistency of the results through comparison with independent data sets that demonstrate that the IceBridge products are capable of providing a reliable record of snow depth and sea ice thickness. We explore the impact of inter-campaign instrument changes and associated algorithm adaptations as well as the applicability of the adapted algorithms to the ongoing IceBridge mission. The uncertainties associated with the retrieval methods are determined and placed in the context of their impact on the retrieved sea ice thickness. Lastly, we present results for the 2009 and 2010 IceBridge campaigns, which are currently available in product form via the National Snow and Ice Data Center

  17. NASA IceBridge: Scientific Insights from Airborne Surveys of the Polar Sea Ice Covers

    Science.gov (United States)

    Richter-Menge, J.; Farrell, S. L.

    2015-12-01

    The NASA Operation IceBridge (OIB) airborne sea ice surveys are designed to continue a valuable series of sea ice thickness measurements by bridging the gap between NASA's Ice, Cloud and Land Elevation Satellite (ICESat), which operated from 2003 to 2009, and ICESat-2, which is scheduled for launch in 2017. Initiated in 2009, OIB has conducted campaigns over the western Arctic Ocean (March/April) and Southern Oceans (October/November) on an annual basis when the thickness of sea ice cover is nearing its maximum. More recently, a series of Arctic surveys have also collected observations in the late summer, at the end of the melt season. The Airborne Topographic Mapper (ATM) laser altimeter is one of OIB's primary sensors, in combination with the Digital Mapping System digital camera, a Ku-band radar altimeter, a frequency-modulated continuous-wave (FMCW) snow radar, and a KT-19 infrared radiation pyrometer. Data from the campaigns are available to the research community at: http://nsidc.org/data/icebridge/. This presentation will summarize the spatial and temporal extent of the OIB campaigns and their complementary role in linking in situ and satellite measurements, advancing observations of sea ice processes across all length scales. Key scientific insights gained on the state of the sea ice cover will be highlighted, including snow depth, ice thickness, surface roughness and morphology, and melt pond evolution.

  18. Measurements of sea ice by satellite and airborne altimetry

    DEFF Research Database (Denmark)

    Kildegaard Rose, Stine

    the modal freeboard heights of 55 cm retrieved from the laser scanner data with the 25 cm retrieved from CryoSat-2 indicates a snow layer of 30 cm, due to the theory that a laser is reflected at the air/snow interface, while the radar is reflected at the snow/ice interface. In the other area, the...... has been in retreat every since. The mass balance of the sea ice is an important input to climate models, where the ice thickness is the most uncertain parameter. In this study, data from the CryoSat-2 radar altimeter satellite are used. CryoSat-2 has been measuring the sea ice in the Arctic Ocean...... modal freeboard is found to be 35 cm for both the airborne and satellite data implying, that the radar signal is here reflected from the snow surface, probably due to weather conditions. CryoSat-2 is very sensitive to returns from specular surfaces, even if they appear o_-nadir. This contaminates the...

  19. Using Airborne SAR Interferometry to Measure the Elevation of a Greenland Ice Cap

    DEFF Research Database (Denmark)

    Dall, Jørgen; Keller, K.; Madsen, S.N.;

    2000-01-01

    A digital elevation model (DEM) of an ice cap in Greenland has been generated from airborne SAR interferometry data, calibrated with a new algorithm, and compared with airborne laser altimetry profiles and carrier-phase differential GPS measurements of radar reflectors deployed on the ice cap. The...

  20. Sea-ice thickness from airborne laser altimetry over the Arctic Ocean north of Greenland

    DEFF Research Database (Denmark)

    Hvidegaard, Sine Munk; Forsberg, René

    2002-01-01

    We present a new method to measure ice thickness of polar sea-ice freeboard heights, using airborne laser altimetry combined with a precise geoid model, giving estimates of thickness of ice through isostatic equilibrium assumptions. In the paper we analyze a number of flights from the Polar Sea off...

  1. The use of airborne laser data to calibrate satellite radar altimetry data over ice sheets

    DEFF Research Database (Denmark)

    Ekholm, Simon; Bamber, J.L.; Krabill, W.B.

    -precision airborne laser profiling data from the so-called Arctic Ice Mapping project as a tool to determine that bias and to calibrate the satellite altimetry. This is achieved by a simple statistical analysis of the airborne laser profiles, which defines the mean amplitude of the local surface undulations as a...

  2. Topography and Penetration of the Greenland Ice Sheet Measured with Airborne SAR Interferometry

    DEFF Research Database (Denmark)

    Dall, Jørgen; Madsen, Søren Nørvang; Keller, K.;

    2001-01-01

    A digital elevation model (DEM) of the Geikie ice sap in East Greenland has been generated from interferometric C-band synthetic aperture radar (SAR) data acquired with the airborne EMISAR system. GPS surveyed radar reflectors and an airborne laser altimeter supplemented the experiment. The accur...

  3. Airborne measurement of tropospheric ice nuclei aerosols using the Portable Ice Nucleation Chamber (PINC)

    Science.gov (United States)

    Chou, C.; Stetzer, O.; Sierau, B.; Lohmann, U.

    2009-04-01

    Ice clouds and mixed phase clouds have different microphysical and radiative properties that need to be assessed in order to understand their impact on the climate. Indeed, on one hand ice crystals found in the ice phase have the ability to scatter incoming solar radiation and absorb terrestrial radiation. On the other hand, about 70% of the tropical precipitation forms via the ice-phase, this means an impact on the hydrological cycle. Investigation of the ability of an aerosol to act as Ice Nuclei (IN) requires knowledge of the thermodynamics conditions, i.e. relative humidity and temperature at which this aerosol form ice crystal. The PerformPINC project was a research campaign within the Education & Training program of the EUropean Fleet for Airborne Research (EUFAR). The project objectives were to measure the number concentration of IN in free and upper troposphere using the Portable Ice Nucleation Chamber (PINC) recently developed by the Institute for Atmospheric Climate Sciences at the ETH Zürich, and thus as a primary objective, testing the technical performance of the instrument during in-situ airborne measurements at different conditions within the chamber. The PINC is the portable version of the Zurich Ice Nucleation Chamber (ZINC) (Stetzer et al., 2008) and is meant for in-situ measurements. Both ZINC and PINC follow the same principle as the Continuous Flow Diffusion Chamber of the Colorado University (Rogers, 1988) that has proven to be of good performance in previous airborne in-situ campaigns (DeMott et al., 2003a). Unlike the CFDC, the PINC has a flat design composed of a main chamber, and an evaporation part. The cooling system of the PINC is also different and consists for the warm side of two BD120 compressors mounted in parallel. For the cold side, it is four BD120 compressors in parallel mounted to another BD120 compressor in serial, thus allowing us to reach lower temperature than the warm side. Aerosols are collected through an inlet where

  4. Waveform classification of airborne synthetic aperture radar altimeter over Arctic sea ice

    OpenAIRE

    Zygmuntowska, M.; Khvorostovsky, K.; V. Helm; S. Sandven

    2013-01-01

    Sea ice thickness is one of the most sensitive variables in the Arctic climate system. In order to quantify changes in sea ice thickness, CryoSat-2 was launched in 2010 carrying a Ku-band radar altimeter (SIRAL) designed to measure sea ice freeboard with a few centimeters accuracy. The instrument uses the synthetic aperture radar technique providing signals with a resolution of about 300m along track. In this study, airborne Ku-band radar altimeter data over different ...

  5. Sea-ice thickness from airborne laser altimetry over the Arctic Ocean north of Greenland

    DEFF Research Database (Denmark)

    Hvidegaard, Sine Munk; Forsberg, René

    2002-01-01

    We present a new method to measure ice thickness of polar sea-ice freeboard heights, using airborne laser altimetry combined with a precise geoid model, giving estimates of thickness of ice through isostatic equilibrium assumptions. In the paper we analyze a number of flights from the Polar Sea o...... Northern Greenland, and estimate accuracies of the estimated freeboard values to be at a 13 cm level, corresponding to about 1 m in absolute thickness....

  6. Greenland Ice sheet mass balance from satellite and airborne altimetry

    OpenAIRE

    Khan, Shfaqat Abbas; Bevis, M. G.; Wahr, J. M.; Wouters, B.; Sasgen, I.; van Dam, T. M.; Van Den Broeke, M. R.; Hanna, E; Huybrechts, P.; Kjaer, K. H.; N. J. Korsgaard; Bjork, A. A.; Kjeldsen, K.K.

    2013-01-01

    Ice loss from the Greenland Ice Sheet (GrIS) is dominated by loss in the marginal areas. Dynamic induced ice loss and its associated ice surface lowering is often largest close to the glacier calving front and may vary from rates of tens of meters per years to a few meters per year over relatively short distances. Hence, high spatial resolution data are required to accurately estimate volume changes. Here, we estimate ice volume change rate of the Greenland ice sheet using data from Ice, Clou...

  7. CBSIT 2009: Airborne Validation of Envisat Radar Altimetry and In Situ Ice Camp Measurements Over Arctic Sea Ice

    Science.gov (United States)

    Connor, Laurence; Farrell, Sinead; McAdoo, David; Krabill, William; Laxon, Seymour; Richter-Menge, Jacqueline; Markus, Thorsten

    2010-01-01

    The past few years have seen the emergence of satellite altimetry as valuable tool for taking quantitative sea ice monitoring beyond the traditional surface extent measurements and into estimates of sea ice thickness and volume, parameters that arc fundamental to improved understanding of polar dynamics and climate modeling. Several studies have now demonstrated the use of both microwave (ERS, Envisat/RA-2) and laser (ICESat/GLAS) satellite altimeters for determining sea ice thickness. The complexity of polar environments, however, continues to make sea ice thickness determination a complicated remote sensing task and validation studies remain essential for successful monitoring of sea ice hy satellites. One such validation effort, the Arctic Aircraft Altimeter (AAA) campaign of2006. included underflights of Envisat and ICESat north of the Canadian Archipelago using NASA's P-3 aircraft. This campaign compared Envisat and ICESat sea ice elevation measurements with high-resolution airborne elevation measurements, revealing the impact of refrozen leads on radar altimetry and ice drift on laser altimetry. Continuing this research and validation effort, the Canada Basin Sea Ice Thickness (CBSIT) experiment was completed in April 2009. CBSIT was conducted by NOAA. and NASA as part of NASA's Operation Ice Bridge, a gap-filling mission intended to supplement sea and land ice monitoring until the launch of NASA's ICESat-2 mission. CBIST was flown on the NASA P-3, which was equipped with a scanning laser altimeter, a Ku-band snow radar, and un updated nadir looking photo-imaging system. The CB5IT campaign consisted of two flights: an under flight of Envisat along a 1000 km track similar to that flown in 2006, and a flight through the Nares Strait up to the Lincoln Sea that included an overflight of the Danish GreenArc Ice Camp off the coast of northern Greenland. We present an examination of data collected during this campaign, comparing airborne laser altimeter measurements

  8. King George Island ice cap geometry updated with airborne GPR measurements

    Directory of Open Access Journals (Sweden)

    M. Rückamp

    2012-07-01

    Full Text Available Ice geometry is a mandatory requirement for numerical modelling purposes. In this paper we present a consistent data set for the ice thickness, the bedrock topography and the ice surface topography of the King George Island ice cap (Arctowski icefield and the adjacent central part. The new data set is composed of ground based and airborne ground penetrating radar (GPR and differential GPS (DGPS measurements, obtained during several field campaigns. Blindow et al. (2010 already provided a comprehensive overview of the ground based measurements carried out in the safely accessible area of the ice cap. The updated data set incorporates airborne measurements in the heavily crevassed coastal areas. Therefore, in this paper special attention is paid to the airborne measurements by addressing the instrument used, survey procedure, and data processing in more detail. In particular, the inclusion of airborne GPR measurements with the 30 MHz BGR-P30-System developed at the Institute of Geophysics (University of Münster completes the picture of the ice geometry substantially. The compiled digital elevation model of the bedrock shows a rough, highly variable topography with pronounced valleys, ridges, and troughs. Mean ice thickness is 240 ± 6 m, with a maximum value of 422 ± 10 m in the surveyed area. Noticeable are bounded areas in the bedrock topography below sea level where marine based ice exists. The provided data set is required as a basis for future monitoring attempts or as input for numerical modelling experiments. The data set is available from the PANGAEA database at http://dx.doi.org/10.1594/PANGAEA.770567.

  9. Tropospheric Airborne Meteorological Data Reporting (TAMDAR) Icing Sensor Performance During the 2003 Alliance Icing Research Study (AIRS II)

    Science.gov (United States)

    Murray, John J.; Schaffner, Philip R.; Minnis, Patrick; Nguyen, Louis; Delnore, Victor E.; Daniels, Taumi S.; Grainger, C. A.; Delene, D.; Wolff, C. A.

    2004-01-01

    The Tropospheric Airborne Meteorological Data Reporting (TAMDAR) sensor was deployed onboard the University of North Dakota Citation II aircraft in the Alliance Icing Research Study (AIRS II) from Nov 19 through December 14, 2003. TAMDAR is designed to measure and report winds, temperature, humidity, turbulence and icing from regional commercial aircraft (Daniels et. al., 2004). TAMDAR icing sensor performance is compared to a) in situ validation data from the Citation II sensor suite, b) Current Icing Potential products developed by the National Center for Atmospheric Research (NCAR) and available operationally on the NOAA Aviation Weather Center s Aviation Digital Data Server (ADDS) and c) NASA Advanced Satellite Aviation-weather Products (ASAP) cloud microphysical products.

  10. Mapping of Ice in the Odden by Satellite and Airborne Remote Sensing

    DEFF Research Database (Denmark)

    Pedersen, Leif Toudal; Hansen, K.Q.; Valeur, H.;

    1999-01-01

    A detailed analysis of the ice conditions in the Odden area of the Greenland Sea was carried out using data from active and passive microwave sensors, supplemented by airborne data. The study focuses on the 1992-1993 winter season, the only winter during the period 1993-1995 in which an Odden fea...

  11. Validation of Airborne FMCW Radar Measurements of Snow Thickness Over Sea Ice in Antarctica

    Science.gov (United States)

    Galin, Natalia; Worby, Anthony; Markus, Thorsten; Leuschen, Carl; Gogineni, Prasad

    2012-01-01

    Antarctic sea ice and its snow cover are integral components of the global climate system, yet many aspects of their vertical dimensions are poorly understood, making their representation in global climate models poor. Remote sensing is the key to monitoring the dynamic nature of sea ice and its snow cover. Reliable and accurate snow thickness data are currently a highly sought after data product. Remotely sensed snow thickness measurements can provide an indication of precipitation levels, predicted to increase with effects of climate change in the polar regions. Airborne techniques provide a means for regional-scale estimation of snow depth and distribution. Accurate regional-scale snow thickness data will also facilitate an increase in the accuracy of sea ice thickness retrieval from satellite altimeter freeboard estimates. The airborne data sets are easier to validate with in situ measurements and are better suited to validating satellite algorithms when compared with in situ techniques. This is primarily due to two factors: better chance of getting coincident in situ and airborne data sets and the tractability of comparison between an in situ data set and the airborne data set averaged over the footprint of the antennas. A 28-GHz frequency modulated continuous wave (FMCW) radar loaned by the Center for Remote Sensing of Ice Sheets to the Australian Antarctic Division is used to measure snow thickness over sea ice in East Antarctica. Provided with the radar design parameters, the expected performance parameters of the radar are summarized. The necessary conditions for unambiguous identification of the airsnow and snowice layers for the radar are presented. Roughnesses of the snow and ice surfaces are found to be dominant determinants in the effectiveness of layer identification for this radar. Finally, this paper presents the first in situ validated snow thickness estimates over sea ice in Antarctica derived from an FMCW radar on a helicopterborne platform.

  12. Integrated Airborne and In-Situ Measurements over Land-Fast Ice near Barrow, AK.

    Science.gov (United States)

    Brozena, J. M.; Gardner, J. M.; Liang, R.; Ball, D.; Richter-Menge, J.; Claffey, K. J.; Abelev, A.; Hebert, D. A.; Jones, K.

    2014-12-01

    During March of 2014, the Naval Research Laboratory and the Cold Regions Research and Engineering Laboratory collected an integrated set of airborne and in-situ measurements over two areas of floating, but land-fast ice near the coast of Barrow, AK. The near-shore site was just north of Point Barrow, and the "offshore" site was ~ 20 km east of Point Barrow. The in-situ data provided ground-truth for airborne measurements from a scanning LiDAR (Riegl Q 560i), digital photogrammetry (Applanix DSS-439) and a snow radar procured from the Center for Remote Sensing of Ice Sheets of the University of Kansas. The objective of the survey was to aid our understanding of the use of the airborne data to calibrate/validate Cryosat-2 data. Sampling size or "footprint" plays a critical role in the attempt to compare in-situ measurements with airborne (or satellite) measurements. Thus the in-situ data were arranged to minimize aliasing. Ground measurements were collected along transects at both sites consisting of a 2 km long profile of snow depth and ice thickness measurements with periodic boreholes. A 60 m x 400 m swath of snow depth measurements was centered on this profile. Airborne data were collected on five overflights of the two transect areas. The LiDAR measured total freeboard (ice + snow) referenced to leads in the ice, and produced swaths 200-300 m wide. The radar measured snow thickness. The freeboard and snow thickness measurements are used to estimate ice thickness via isostasy and density estimates. The central swath of in situ snow depth data allows examination of the effects of cross-track variations considering the relatively large footprint of the snow radar. Assuming a smooth, flat surface the radar range resolution in air is < 4 cm, but the along-track sampling distance is ~ 3 m after unfocussed SAR processing. The width of the footprint varies from ~ 9 m up to about 40 m (beam-limited) for uneven surfaces. However, the radar could not resolve snow thickness

  13. Using Airborne Lidar Data from IcePod to Measure Annual and Seasonal Ice Changes Over Greenland

    Science.gov (United States)

    Frearson, N.; Bertinato, C.; Das, I.

    2014-12-01

    The IcePod is a multi-sensor airborne science platform that supports a wide suite of instruments, including a Riegl VQ-580 infrared scanning laser, GPS-inertial positioning system, shallow and deep-ice radars, visible-wave and infrared cameras, and upward-looking pyrometer. These instruments allow us to image the ice from top to bottom, including the surface of melt-water plumes that originate at the ice-ocean boundary. In collaboration with the New York Air National Guard 109th Airlift Wing, the IcePod is flown on LC-130 aircraft, which presents the unique opportunity to routinely image the Greenland ice sheet several times within a season. This is particularly important for mass balance studies, as we can measure elevation changes during the melt season. During the 2014 summer, laser data was collected via IcePod over the Greenland ice sheet, including Russell Glacier, Jakobshavn Glacier, Eqip Glacier, and Summit Camp. The Icepod will also be routinely operated in Antarctica. We present the initial testing, calibration, and error estimates from the first set of laser data that were collected on IcePod. At a survey altitude of 1000 m, the laser swath covers ~ 1000 m. A Northrop-Grumman LN-200 tactical grade IMU is rigidly attached to the laser scanner to provide attitude data at a rate of 200 Hz. Several methods were used to determine the lever arm between the IMU center of navigation and GPS antenna phase center, terrestrial scanning laser, total station survey, and optimal estimation. Additionally, initial bore sight calibration flights yielded misalignment angles within an accuracy of ±4 cm. We also performed routine passes over the airport ramp in Kangerlussuaq, Greenland, comparing the airborne GPS and Lidar data to a reference GPS-based ground survey across the ramp, spot GPS points on the ramp and a nearby GPS base station. Positioning errors can severely impact the accuracy of a laser altimeter when flying over remote regions such as across the ice sheets

  14. Greenland Ice sheet mass balance from satellite and airborne altimetry

    DEFF Research Database (Denmark)

    Khan, Shfaqat Abbas; Bevis, M. G.; Wahr, J. M.;

    decade, while dynamic ice loss increased during 2003-2009, but has since been decreasing. Finally, we assess the estimated mass loss using GPS observations from stations located along the edge of the GrIS and measurements from the Gravity Recovery and Climate Experiment (GRACE) satellite gravity mission....

  15. Essential Climate Variables for the Ice Sheets from Space and Airborne measurements

    DEFF Research Database (Denmark)

    Fredenslund Levinsen, Joanna

    studyexploits the advantages of radar and laser altimetry to analyze surface elevationchanges and build a Digital Elevation Model of the ice sheet. Selected advantagesare radar data’s continuity in time and laser data’s higher horizontal andvertical accuracy. Therefore, ESA Envisat and CryoSat-2 radar altimetry...... dataare used in conjunction with laser data from NASA’s ICESat and airborneATM and LVIS instruments, and from ESA’s airborne CryoVEx campaign.The study is part of the ESA Ice Sheets CCI project. With the release ofREAPER data, one goal is to use the more than two decades of ESA radaraltimetry to develop a...... long-term surface elevation change product from 1992 topresent. The optimal method is found by comparing ten different solutions submittedby the scientific community across the choice of altimeter and method: A combination of repeat-tracks and cross-overs. The former produces estimatesalong repeat...

  16. The use of airborne laser data to calibrate satellite radar altimetry data over ice sheets

    DEFF Research Database (Denmark)

    Ekholm, Simon; Bamber, J.L.; Krabill, W.B.

    2002-01-01

    Satellite radar altimetry is the most important data source for ice sheet elevation modeling but it is well established that the accuracy of such data from satellite borne radar altimeters degrade seriously with increasing surface slope and level of roughness. A significant fraction of the slope......-precision airborne laser profiling data from the so-called Arctic Ice Mapping project as a tool to determine that bias and to calibrate the satellite altimetry. This is achieved by a simple statistical analysis of the airborne laser profiles, which defines the mean amplitude of the local surface undulations as a......-correlated noise can be effectively removed by the so-called relocation error correction method. The adjustment, however, produces a different spatial sampling of the data, which introduces a non-negligible slope related bias to the computation of digital elevation models. In this paper we incorporate high...

  17. Ice-sheet elevations from across-track processing of airborne interferometric radar altimetry

    OpenAIRE

    R. L. Hawley; SHEPHERD, A; Cullen, R; V. Helm; Wingham, D. J.

    2009-01-01

    Interferometric Radar Altimeters (IRA's) use dual receive antennas to overcome one of the spatial limitations of pulse-limited altimeters. In a conventional IRA measurement, the range and across-track direction of a scatterer are determined using the phase difference between the antennas. We demonstrate a method of determining multiple elevation points across a swath orthogonal to the instrument ground track in regions of steep terrain, such as ice-sheet margins. We use data from an airborne ...

  18. Airborne radar survey above Vostok region, east-central Antarctica: ice thickness and Lake Vostok geometry

    OpenAIRE

    Tabacco, I. E.; Department of Earth Science, University of Milan, Via Cicognara 7, I-20129 Milan, Italy; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zuccheretti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Forieri, A.; Department of Earth Science, University of Milan, Via Cicognara 7, I-20129 Milan, Italy; Della Vedova, A.; Department of Earth Science, University of Milan, Via Cicognara 7, I-20129 Milan, Italy

    2002-01-01

    During the 1999-2000 Italian Expedition, an airborne radar survey was performed along 12 transects across Lake Vostok, Antarctica, and its western and eastern margins. Ice thickness, subglacial elevation and the precise location of lake boundaries were determined. Radar data confirm the geometry derived from previous surveys, but with some slight differences. We measured a length of up to 260 km, a maximum width of 81 km and an area of roughly 14000 km2. Along the major axis, from north...

  19. Waveform classification of airborne synthetic aperture radar altimeter over Arctic sea ice

    Directory of Open Access Journals (Sweden)

    M. Zygmuntowska

    2013-08-01

    Full Text Available Sea ice thickness is one of the most sensitive variables in the Arctic climate system. In order to quantify changes in sea ice thickness, CryoSat-2 was launched in 2010 carrying a Ku-band radar altimeter (SIRAL designed to measure sea ice freeboard with a few centimeters accuracy. The instrument uses the synthetic aperture radar technique providing signals with a resolution of about 300 m along track. In this study, airborne Ku-band radar altimeter data over different sea ice types have been analyzed. A set of parameters has been defined to characterize the differences in strength and width of the returned power waveforms. With a Bayesian-based method, it is possible to classify about 80% of the waveforms from three parameters: maximum of the returned power waveform, the trailing edge width and pulse peakiness. Furthermore, the maximum of the power waveform can be used to reduce the number of false detections of leads, compared to the widely used pulse peakiness parameter. For the pulse peakiness the false classification rate is 12.6% while for the power maximum it is reduced to 6.5%. The ability to distinguish between different ice types and leads allows us to improve the freeboard retrieval and the conversion from freeboard into sea ice thickness, where surface type dependent values for the sea ice density and snow load can be used.

  20. Waveform analysis of airborne synthetic aperture radar altimeter over Arctic sea ice

    Directory of Open Access Journals (Sweden)

    M. Zygmuntowska

    2013-03-01

    Full Text Available Sea ice thickness is one of the most sensitive variables in the Arctic climate system. In order to quantify changes in sea ice thickness, CryoSat was launched in 2010 carrying a Ku-band Radar Altimeter (SIRAL designed to measure sea ice freeboard with a few centimeters accuracy. The instrument uses the synthetic aperture radar technique providing signals with a resolution of about 300 m along track. In this study, airborne Ku-band radar altimeter data over different sea ice types has been analyzed. A set of parameters has been defined to characterize the difference in strength and width of the returned power waveforms. With a Bayesian based method it is possible to classify about 80% of the waveforms by three parameters: maximum of the returned power echo, the trailing edge width and pulse peakiness. Furthermore, the radar power echo maximum can be used to minimize the rate of false detection of leads compared to the widely used Pulse Peakiness parameter. The possibility to distinguish between different ice types and open water allows to improve the freeboard retrieval and the conversion into sea ice thickness where surface type dependent values for the sea ice density and snow load can be used.

  1. Integration of airborne altimetry and in situ radar measurements to estimate marine ice thickness beneath the Larsen C ice shelf, Antarctic Peninsula

    Science.gov (United States)

    McGrath, D.; Steffen, K.; Rodriguez Lagos, J.

    2010-12-01

    Observed atmospheric and oceanic warming is driving significant retreat and / or collapse of ice shelves along the Antarctic Peninsula totaling over 25,000 km2 in the past five decades. Basal melting of meteoric ice can occur near the grounding line of deep glacier inflows if the ocean water is above the pressure melting point. Buoyant meltwater will develop thermohaline circulation, rising beneath the ice shelf, where it may become supercooled and subsequently refreeze in ice draft minima. Marine ice, due to its warm and thus relatively viscous nature, is hypothesized to suture parallel flow bands, increasing ice shelf stability by arresting fracture propagation and controlling iceberg calving dimensions. Thus efforts to model ice shelf stability require accurate estimates of marine ice location and thickness. Ice thickness of a floating ice shelf can be determined in two manners: (1) from measurements of ice elevation above sea level and the calculation of ice thickness from assumptions of hydrostatic equilibrium, and (2) from radar echo measurements of the ice-water interface. Marine ice can confound the latter because its high dielectric constant and strong absorptive properties attenuate the radar energy, often preventing a return signal from the bottom of the ice shelf. These two methods are complementary for determining the marine ice component though because positive anomalies in (1) relative to (2) suggest regions of marine ice accretion. Nearly 350 km of ice penetrating radar (25 MHz) surveys were collected on the Larsen C ice shelf, in conjunction with kinematic GPS measurements and collocated with surface elevation data from the NASA Airborne Topographic Mapper (ATM) as part of the ICE Bridge mission in 2009. Basal ice topography and total ice thickness is accurately mapped along the survey lines and compared with calculated ice thickness from both the kinematic GPS and ATM elevation data. Positive anomalies are discussed in light of visible imagery and

  2. Airborne Polarimetric, Two-Color Laser Altimeter Measurements of Lake Ice Cover: A Pathfinder for NASA's ICESat-2 Spaceflight Mission

    Science.gov (United States)

    Harding, David; Dabney, Philip; Valett, Susan; Yu, Anthony; Vasilyev, Aleksey; Kelly, April

    2011-01-01

    The ICESat-2 mission will continue NASA's spaceflight laser altimeter measurements of ice sheets, sea ice and vegetation using a new measurement approach: micropulse, single photon ranging at 532 nm. Differential penetration of green laser energy into snow, ice and water could introduce errors in sea ice freeboard determination used for estimation of ice thickness. Laser pulse scattering from these surface types, and resulting range biasing due to pulse broadening, is assessed using SIMPL airborne data acquired over icecovered Lake Erie. SIMPL acquires polarimetric lidar measurements at 1064 and 532 nm using the micropulse, single photon ranging measurement approach.

  3. Airborne discrimination between ice and water: application to the laser measurement of chlorophyll-in-water in a marginal ice zone

    International Nuclear Information System (INIS)

    The concurrent active -passive measurement capabilities of the NASA Airborne Oceanographic Lidar have been used to a) discriminate between ice and water in a large ice field within the Greenland Sea and b) achieve the detection and measurement of chlorophyll-in-water by laser-induced and water-Raman-normalized pigment fluorescence. Passive upwelled radiances from sea ice are significantly stronger than those from the neighboring water, even when the optical receiver field-of-view is only partially filled with ice. Thus, weaker passive upwelled radiances, together with concurrently acquired laser-induced spectra, can rather confidently be assigned to the intervening water column. The laser-induced spectrum can then be processed using previously established methods to measure the chlorophyll-in-water concentration. Significant phytoplankton patchiness and elevated chlorophyll concentrations were found within the waters of the melting ice compared to ice-free regions just outside the ice field

  4. A Modified Nonlinear Chirp Scaling Algorithm for Air-borne Ice Radar

    International Nuclear Information System (INIS)

    In this paper, a modified nonlinear chirp scaling (MNLCS) algorithm for air-borne ice radar data is proposed. The spatial geometry based on the two-layer medium is analyzed for the studying of MNLCS. The algorithm can compensate the refraction effects and the propagation velocity changes in different mediums automatically, and can improve the focusing feature of the scatters. According to the model of echo signal, the phase compensation factors and realized steps of the algorithm are given. Numerical experiments are executed. The experimental results show the effectiveness of the proposed algorithm

  5. Effects of surface roughness on sea ice freeboard retrieval with an Airborne Ku-Band SAR radar altimeter

    DEFF Research Database (Denmark)

    Hendricks, Stefan; Stenseng, Lars; Helm, Veit;

    2010-01-01

    Results from two years of the CryoSat Validation Experiment (CryoVEx) over sea ice in the western Arctic Ocean are presented. The estimation of freeboard, the height of sea ice floating above the water level, is one the main goals of the CryoSat-2 mission of the European Space Agency (ESA) in order...... of the airborne validation dataset, since the radar overestimates the amount of open water and thin ice as well the freeboard of heavy ice deformation zones....

  6. Recent ice sheet snow accumulation and firn storage of meltwater inferred by ground and airborne radars

    Science.gov (United States)

    Miege, Clement

    Recent surface mass balance changes in space and time over the polar ice sheets need to be better constrained in order to estimate the ice-sheet contribution to sea-level rise. The mass balance of any ice body is obtained by subtracting mass losses from mass gains. In response to climate changes of the recent decades, ice-sheet mass losses have increased, making ice-sheet mass balance negative and raising sea level. In this work, I better quantify the mass gained by snowfall across the polar ice sheets; I target specific regions over both Greenland and West Antarctica where snow accumulation changes are occurring due to rising air temperature. Southeast Greenland receives 30% of the total snow accumulation of the Greenland ice sheet. In this work, I combine internal layers observed in ice-penetrating radar data with firn cores to derive the last 30 years of accumulation and to measure the spatial pattern of accumulation toward the southeast coastline. Below 1800 m elevation, in the percolation zone, significant surface melt is observed in the summer, which challenges both firn-core dating and internal-layer tracing. While firn-core drilling at 1500 m elevation, liquid water was found at ˜20-m depth in a firn aquifer that persisted over the winter. The presence of this water filling deeper pore space in the firn was unexpected, and has a significant impact on the ice sheet thermal state and the estimate of mass balance made using satellite altimeters. Using a 400-MHz ice-penetrating radar, the extent of this widespread aquifer was mapped on the ground, and also more extensively from the air with a 750-MHz airborne radar as part of the NASA Operation IceBridge mission. Over three IceBridge flight campaigns (2011-2013), based on radar data, the firn aquifer is estimated to cover ˜30,000 km2 area within the wet-snow zone of the ice sheet. I use repeated flightlines to understand the temporal variability of the water trapped in the firn aquifer and to simulate its

  7. Comparison of space borne radar altimetry and airborne laser altimetry over sea ice in the Fram Strait

    DEFF Research Database (Denmark)

    Giles, K.A.; Hvidegaard, Sine Munk

    2006-01-01

    This paper describes the first comparison of satellite radar and airborne laser altimetry over sea ice. In order to investigate the differences between measurements from the two different instruments we explore the statistical properties of the data and determine reasonable scales in space and ti...

  8. Airborne observations of a subvisible midlevel Arctic ice cloud: microphysical and radiative characterization

    Directory of Open Access Journals (Sweden)

    A. Lampert

    2009-01-01

    Full Text Available During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR campaign, which was conducted in March and April 2007, an optically thin ice cloud was observed at around 3 km altitude south of Svalbard. The microphysical and radiative properties of this particular subvisible midlevel cloud were investigated with complementary remote sensing and in-situ instruments. Collocated airborne lidar remote-sensing and spectral solar radiation measurements were performed at a flight altitude of 2300 m below the cloud base. Under almost stationary atmospheric conditions, the same subvisible midlevel cloud was probed with various in-situ sensors roughly 30 min later.

    From individual ice crystal samples detected with the Cloud Particle Imager and the ensemble of particles measured with the Polar Nephelometer, we retrieved the single-scattering albedo, the scattering phase function as well as the volume extinction coefficient and the effective diameter of the crystal population. Furthermore, a lidar ratio of 21 (±6 sr was deduced by two independent methods. These parameters in conjunction with the cloud optical thickness obtained from the lidar measurements were used to compute spectral and broadband radiances and irradiances with a radiative transfer code. The simulated results agreed with the observed spectral downwelling radiance within the range given by the measurement uncertainty. Furthermore, the broadband radiative simulations estimated a net (solar plus thermal infrared radiative forcing of the subvisible midlevel ice cloud of −0.4 W m−2 (−3.2 W m−2 in the solar and +2.8 W m−2 in the thermal infrared wavelength range.

  9. The accuracy of satellite radar altimeter data over the Greenland ice sheet determined from airborne laser data

    DEFF Research Database (Denmark)

    Bamber, J.L.; Ekholm, Simon; Krabill, W.

    1998-01-01

    with airborne laser altimeter data an absolute accuracy typically in the range 2-10 cm +/- 10 cm. Comparison of differences between the radar and laser derived elevations, showed a correlation with surface slope. The difference between the two data sets ranged from 84 cm +/- 79 cm for slopes below 0......The 336 days of the geodetic phase of ERS-1 provides dense coverage, by satellite radar altimetry, of the whole of the Greenland ice sheet. These data have been used to produce a digital elevation model of the ice sheet. The errors present in the altimeter data were investigated via a comparison.......1 degrees, to 10.3 m +/- 8.4 m for a slope of 0.7 degrees ( the half power beam-width of the ERS-1 radar altimeter). An explanation for the behaviour of the difference as a function of surface slope is given in terms of the pattern of surface roughness on the ice sheet....

  10. Airborne Laser Altimetry Mapping of the Greenland Ice Sheet: Application to Mass Balance Assessment

    Science.gov (United States)

    Abdalati, W.; Krabill, W.; Frederick, E.; Manizade, S.; Martin, C.; Sonntag, J.; Swift, R.; Thomas, R.; Wright, W.; Yungel, J.

    2000-01-01

    In 1998 and '99, the Arctic Ice Mapping (AIM) program completed resurveys of lines occupied 5 years earlier revealing elevation changes of the Greenland ice sheet and identifying areas of significant thinning, thickening and balance. In planning these surveys, consideration had to be given to the spatial constraints associated with aircraft operation, the spatial nature of ice sheet behavior, and limited resources, as well as temporal issues, such as seasonal and interannual variability in the context of measurement accuracy. This paper examines the extent to which the sampling and survey strategy is valid for drawing conclusions on the current state of balance of the Greenland ice sheet. The surveys covered the entire ice sheet with an average distance of 21.4 km between each location on the ice sheet and the nearest flight line. For most of the ice sheet, the elevation changes show relatively little spatial variability, and their magnitudes are significantly smaller than the observed elevation change signal. As a result, we conclude that the density of the sampling and the accuracy of the measurements are sufficient to draw meaningful conclusions on the state of balance of the entire ice sheet over the five-year survey period. Outlet glaciers, however, show far more spatial and temporal variability, and each of the major ones is likely to require individual surveys in order to determine its balance.

  11. Development of an airborne MMW FM-CW radar for mapping river ice

    Science.gov (United States)

    Yankielum, Norbert E.; Ferrick, Michael G.; Weyrick, Patricia B.

    1993-01-01

    Analyses of a river's freezeup ice cover stability and its breakup rely on detailed knowledge of the cover's thickness and the variability of that thickness. A high-resolution, millimeter wave (26.5- to 40-GHz) Frequency Modulated-Continuous Wave radar with real-time data acquisition and digital signal processing and display capability was deployed from a low-flying (3-10 m) helicopter to continuously acquire, process and display data during an ice thickness profiling survey of a 24-km study reach. A nominal sheet ice thickness of 50 cm, occasional areas of new ice sheet as thin as 5 cm, open leads, and massive ice accumulations on the order of 5 m thick were encountered. Radar profiling data agreed with ground truth from borehole measurements of the sheet ice, and provided a more detailed view of the ice conditions than that obtained from a low altitude video survey. The radar system provided rapid, safe and accurate data acquisition, allowing detailed mapping of the ice conditions throughout the reach.

  12. Comparison of space borne radar altimetry and airborne laser altimetry over sea ice in the Fram Strait

    DEFF Research Database (Denmark)

    Giles, K.A.; Hvidegaard, Sine Munk

    2006-01-01

    This paper describes the first comparison of satellite radar and airborne laser altimetry over sea ice. In order to investigate the differences between measurements from the two different instruments we explore the statistical properties of the data and determine reasonable scales in space and time...... at which to examine them. The resulting differences between the data sets show that the laser and the radar are reflecting from different surfaces and that the magnitude of the difference decreases with increasing surface air temperature. This suggests that the penetration depth of the radar signal......, into the snow, varies with temperature. The results also show the potential for computing Arctic wide snow depth maps by combining measurements from laser and radar altimeters....

  13. Airborne lidar measurements of surface ozone depletion over Arctic sea ice

    OpenAIRE

    Seabrook, J. A.; Whiteway, J. A.; Gray, L. H.; Staebler, R.; A. Herber

    2013-01-01

    A differential absorption lidar (DIAL) for measurement of atmospheric ozone concentration was operated aboard the Polar 5 research aircraft in order to study the depletion of ozone over Arctic sea ice. The lidar measurements during a flight over the sea ice north of Barrow, Alaska, on 3 April 2011 found a surface boundary layer depletion of ozone over a range of 300 km. The photochemical destruction of surface level ozone was strongest at the most northern point of the flight, and steadily de...

  14. An airborne millimeter-wave FM-CW radar for thickness profiling of freshwater ice

    Science.gov (United States)

    Yankielun, Norbert E.

    1992-11-01

    The ability to profile rapidly and accurately the structure of freshwater ice down to a thickness of a few centimeters over large surfaces of frozen ponds, lakes, and rivers has wide military, industrial, commercial, and recreational application, including safety and trafficability surveys. A prototype broadband millimeter wave (26.5 to 40 GHz) Frequency Modulated-Continuous Wave (FM-CW) radar, employing real-time data acquisition and Digital Signal Processing (DSP) techniques, was developed for continuously recording the thickness profile of freshwater ice. Thickness resolution is better than 3 cm plus or minus 10 percent, which improves on short-pulse and FM-CW radars operating at frequencies less than 10 GHz. These other radars have a best reported thickness resolution of approximately 10 cm with a plus or minus 10 percent accuracy; this is insufficient because a freshwater ice sheet as thin as 5 cm, floating on water, can be safely traversed by an individual of average weight. System specifications include a 15-dBm output RF (Radio Frequency) power level, a 0.066-second sweep rate and less than a 50 dB Signal-to-Noise Ratio (SNR). This radar was tested on the ground and from a helicopter at heights of up to 7 m above ice surfaces at speeds up to 40 km/hr. Pond and river ice sheets between 3 and 35 cm thick, with and without fresh snow cover, and with minimal surface roughness were profiled. Results showed direct correlation between radar and borehole thickness measurements. Losses from volume scattering by imbedded air bubbles did not significantly affect the system's capability to discern the air/ice and ice/water scattering boundaries.

  15. The abundance of ice nuclei during airborne measurements over Germany and the Caribbean

    Science.gov (United States)

    Danielczok, A..; Bingemer, H.; Curtius, J.; DeMott, P. J.

    2012-04-01

    The tropospheric abundance of ice nuclei (IN) acting at -8 to -18 °C in the deposition and condensation nucleation modes was investigated during series of research flights on board a Learjet over northern Germany in June 2011 and on board of the NSF/NCAR C-130 during the ICE IN CLOUDS EXPERIMENT - TROPICAL (ICE-T) over the Caribbean in July 2011. Ice nuclei were collected from the air by electrostatic precipitation of aerosol onto silicon substrates. Samples were subsequently analyzed in the laboratory by the isothermal static vapor diffusion chamber FRIDGE (FRankfurt Ice Nuclei Deposition FreezinG Experiment). IN abundance in the free and upper troposphere varied between < 1 and 50 IN L-1 in the upper troposphere over Germany, and between < 1 to 40 IN L-1 in the lower and middle troposphere in the Caribbean. A few dust layers were encountered. The results will be presented and discussed in the light of trajectory analysis and other supporting information.

  16. Airborne EM sea-ice thickness profiling over brackish Baltic sea water

    OpenAIRE

    Haas, Christian

    2004-01-01

    Helicopter-borne electromagnetic-inductive (EM) ice thickness measurements have been performed in February 2003 along the Finish Baltic Sea coast. Both, the Gulf of Finland and the Gulf of Bothnia were surveyed. Measurements have been performed with a small, two-frequency EM-Bird, a towed sensor suspended 20 m below the heli-copter and operated 15 m above the ice surface. Results show that sufficiently accurate measurements were obtained even with minimum water salinities of 3 ppt in the Bay ...

  17. L and P Band MMIC T/R Module Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is specifically written to address the need for improved L and P band T/R modules. The solicitation calls for investigation and development of core...

  18. L and P Band MMIC T/R Module Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is specifically written to address the need for improved L and P band T/R modules for use in active microwave surveillance of earth surface and...

  19. Characterization of the ice nucleation activity of an airborne Penicillium species

    Science.gov (United States)

    Yordanova, Petya; Hill, Thomas C. J.; Pummer, Bernhard G.; Franc, Gary D.; Pöschl, Ulrich; Fröhlich-Nowoisky, Janine

    2016-04-01

    Microorganisms are ubiquitous both on and above the Earth. Several bacterial and fungal spe-cies are the focus of atmospheric studies due to their ability to trigger ice formation at high subzero temperatures. Thus, they have potential to modify cloud albedo, lifetime and precipita-tion, and ultimately the hydrological cycle. Several fungal strains have already been identified as possessing ice nucleation (IN) activity, and recent studies have shown that IN active fungi are present in the cultivable community of air and soil samples [1, 2]. However, the abundance, diversity, and sources of fungal ice nuclei in the atmosphere are still poorly characterized. In this study, fungal colonies obtained from air samples were screened for IN activity in the droplet-freezing assay described in Fröhlich-Nowoisky et al., 2015 [2]. Out of 128 tested iso-lates, two were found to catalyze ice formation at temperatures up to -4°C. By DNA analysis, both isolates were classified as Penicillium spp. The freezing activity of both was further char-acterized after different filtration, heat, and enzymatic treatments in the temperature range from ‑4°C to ‑15°C. Preliminary results show that a proteinaceous compound is responsible for the IN activity. Furthermore, ongoing experiments indicate that the activity is associated only with the hyphae. [1] Huffman, et al. (2013): Atmos. Chem. Phys., 13, 6151-6164. [2] Fröhlich-Nowoisky et al. (2015): Biogeosciences, 12: 1057-1071.

  20. A Comparison of Snow Depth on Sea Ice Retrievals Using Airborne Altimeters and an AMSR-E Simulator

    Science.gov (United States)

    Cavalieri, D. J.; Marksu, T.; Ivanoff, A.; Miller, J. A.; Brucker, L.; Sturm, M.; Maslanik, J. A.; Heinrichs, J. F.; Gasiewski, A.; Leuschen, C.; Krabill, W.; Sonntag, J.

    2011-01-01

    A comparison of snow depths on sea ice was made using airborne altimeters and an Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) simulator. The data were collected during the March 2006 National Aeronautics and Space Administration (NASA) Arctic field campaign utilizing the NASA P-3B aircraft. The campaign consisted of an initial series of coordinated surface and aircraft measurements over Elson Lagoon, Alaska and adjacent seas followed by a series of large-scale (100 km ? 50 km) coordinated aircraft and AMSR-E snow depth measurements over portions of the Chukchi and Beaufort seas. This paper focuses on the latter part of the campaign. The P-3B aircraft carried the University of Colorado Polarimetric Scanning Radiometer (PSR-A), the NASA Wallops Airborne Topographic Mapper (ATM) lidar altimeter, and the University of Kansas Delay-Doppler (D2P) radar altimeter. The PSR-A was used as an AMSR-E simulator, whereas the ATM and D2P altimeters were used in combination to provide an independent estimate of snow depth. Results of a comparison between the altimeter-derived snow depths and the equivalent AMSR-E snow depths using PSR-A brightness temperatures calibrated relative to AMSR-E are presented. Data collected over a frozen coastal polynya were used to intercalibrate the ATM and D2P altimeters before estimating an altimeter snow depth. Results show that the mean difference between the PSR and altimeter snow depths is -2.4 cm (PSR minus altimeter) with a standard deviation of 7.7 cm. The RMS difference is 8.0 cm. The overall correlation between the two snow depth data sets is 0.59.

  1. Remote Sensing of Liquid Water and Ice Cloud Optical Thickness and Effective Radius in the Arctic: Application of Airborne Multispectral MAS Data

    Science.gov (United States)

    King, Michael D.; Platnick, Steven; Yang, Ping; Arnold, G. Thomas; Gray, Mark A.; Riedi, Jerome C.; Ackerman, Steven A.; Liou, Kuo-Nan

    2003-01-01

    A multispectral scanning spectrometer was used to obtain measurements of the reflection function and brightness temperature of clouds, sea ice, snow, and tundra surfaces at 50 discrete wavelengths between 0.47 and 14.0 microns. These observations were obtained from the NASA ER-2 aircraft as part of the FIRE Arctic Clouds Experiment, conducted over a 1600 x 500 km region of the north slope of Alaska and surrounding Beaufort and Chukchi Seas between 18 May and 6 June 1998. Multispectral images of the reflection function and brightness temperature in 11 distinct bands of the MODIS Airborne Simulator (MAS) were used to derive a confidence in clear sky (or alternatively the probability of cloud), shadow, and heavy aerosol over five different ecosystems. Based on the results of individual tests run as part of the cloud mask, an algorithm was developed to estimate the phase of the clouds (water, ice, or undetermined phase). Finally, the cloud optical thickness and effective radius were derived for both water and ice clouds that were detected during one flight line on 4 June. This analysis shows that the cloud mask developed for operational use on MODIS, and tested using MAS data in Alaska, is quite capable of distinguishing clouds from bright sea ice surfaces during daytime conditions in the high Arctic. Results of individual tests, however, make it difficult to distinguish ice clouds over snow and sea ice surfaces, so additional tests were added to enhance the confidence in the thermodynamic phase of clouds over the Beaufort Sea. The cloud optical thickness and effective radius retrievals used 3 distinct bands of the MAS, with the newly developed 1.62 and 2.13 micron bands being used quite successfully over snow and sea ice surfaces. These results are contrasted with a MODIS-based algorithm that relies on spectral reflectance at 0.87 and 2.13 micron.

  2. A sea-ice thickness retrieval model for 1.4 GHz radiometry and application to airborne measurements over low salinity sea-ice

    Directory of Open Access Journals (Sweden)

    L. Kaleschke

    2010-12-01

    Full Text Available In preparation for the European Space Agency's (ESA Soil Moisture and Ocean Salinity (SMOS mission, we investigated the potential of L-band (1.4 GHz radiometry to measure sea-ice thickness.

    Sea-ice brightness temperature was measured at 1.4 GHz and ice thickness was measured along nearly coincident flight tracks during the SMOS Sea-Ice campaign in the Bay of Bothnia in March 2007. A research aircraft was equipped with the L-band Radiometer EMIRAD and coordinated with helicopter based electromagnetic induction (EM ice thickness measurements.

    We developed a three layer (ocean-ice-atmosphere dielectric slab model for the calculation of ice thickness from brightness temperature. The dielectric properties depend on the relative brine volume which is a function of the bulk ice salinity and temperature.

    The model calculations suggest a thickness sensitivity of up to 1.5 m for low-salinity (multi-year or brackish sea-ice. For Arctic first year ice the modelled thickness sensitivity is less than half a meter. It reduces to a few centimeters for temperatures approaching the melting point.

    The campaign was conducted under unfavorable melting conditions and the spatial overlap between the L-band and EM-measurements was relatively small. Despite these disadvantageous conditions we demonstrate the possibility to measure the sea-ice thickness with the certain limitation up to 1.5 m.

    The ice thickness derived from SMOS measurements would be complementary to ESA's CryoSat-2 mission in terms of the error characteristics and the spatiotemporal coverage. The relative error for the SMOS ice thickness retrieval is expected to be not less than about 20%.

  3. A sea ice thickness retrieval model for 1.4 GHz radiometry and application to airborne measurements over low salinity sea ice

    Directory of Open Access Journals (Sweden)

    L. Kaleschke

    2009-11-01

    Full Text Available In preparation for the European Space Agency's (ESA Soil Moisture and Ocean Salinity (SMOS mission we investigated the potential of L-band (1.4 GHz radiometery to measure sea ice thickness.

    Sea ice brightness temperature was measured at 1.4 GHz and ice thickness were measured along nearly coincident flight tracks during the SMOS Sea-Ice campaign in the Bay of Bothnia in March 2007. A research aircraft was equipped with the L-band Radiometer EMIRAD and coordinated with helicopter based electromagnetic induction (EM ice thickness measurements.

    We developed a three layer (ocean-ice-atmosphere dielectric slab model for the calculation of ice thickness from brightness temperature. The dielectric properties depend on the relative brine volume which is a function of the bulk ice salinity and temperature.

    The model calculations suggest a thickness sensitivity of up to 1.5 m for low-salinity (multi-year or brackish sea ice. For Arctic first year ice the modeled thickness sensitivity is roughly half a meter. It reduces to a few centimeters for temperatures approaching the melting point. Although the campaign was conducted under such unfavorable melting conditions and despite limited spatial overlap between the L-band and EM-measurements was small we demonstrate a large potential for retrieving the ice thickness in the range of 0.2 to 1.5 m.

    Furthermore, we show that the ice thickness derived from SMOS measurements would be complementary to ESA's CryoSat-2 mission in terms of the error characteristics and the spatio-temporal coverage.

  4. Tropospheric Airborne Meteorological Data and Reporting (TAMDAR) Icing Sensor Performance during the 2003/2004 Alliance Icing Research Study (AIRS II)

    Science.gov (United States)

    Murray, John J.; Nguyen, Louis A.; Daniels, Taumi; Minnis, Patrick; Schaffner, Phillip R.; Cagle, Melinda F.; Nordeen, Michele L.; Wolff, Cory A.; Anderson, Mark V.; Mulally, Daniel J.

    2005-01-01

    NASA Langley Research Center and its research partners from the University of North Dakota (UND) and the National Center for Atmospheric Research (NCAR) participated in the AIRS II campaign from November 17 to December 17, 2003. AIRS II provided the opportunity to compare TAMDAR in situ in-flight icing condition assessments with in situ data from the UND Citation II aircraft's Rosemont system. TAMDAR is designed to provide a general warning of ice accretion and to report it directly into the Meteorological Data Communications and Reporting System (MDCRS). In addition to evaluating TAMDAR with microphysical data obtained by the Citation II, this study also compares these data to the NWS operational in-flight icing Current Icing Potential (CIP) graphic product and with the NASA Advanced Satellite Aviation-weather Products (ASAP) Icing Severity product. The CIP and ASAP graphics are also examined in this study to provide a context for the Citation II's sorties in AIRS II.

  5. Effects of surface roughness on sea ice freeboard retrieval with an Airborne Ku-Band SAR radar altimeter

    OpenAIRE

    Hendricks, Stefan; Stenseng, Lars; Helm, Veit; Haas, Christian

    2010-01-01

    Results from two years of the CryoSat Validation Experiment (CryoVEx) over sea ice in the western Arctic Ocean are presented. The estimation of freeboard, the height of sea ice floating above the water level, is one the main goals of the CryoSat-2 mission of the European Space Agency (ESA) in order to investigate sea ice volume changes on an Arctic wide scale. Freeboard retrieval requires precise radar range measurements to the ice surface, therefore we investigate the penetration of the Ku-B...

  6. Reconfigurable, Wideband Radar Transceiver and Antenna for P-band Stretch Processing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — IAI proposes to develop a Reconfigurable Wideband Radar Transceiver, with direct digital synthesis of P-band radar frequencies, novel high bandwidth P-band antenna...

  7. The accuracy of satellite radar altimeter data over the Greenland ice sheet determined from airborne laser data

    DEFF Research Database (Denmark)

    Bamber, J.L.; Ekholm, Simon; Krabill, W.

    1998-01-01

    with airborne laser altimeter data an absolute accuracy typically in the range 2-10 cm +/- 10 cm. Comparison of differences between the radar and laser derived elevations, showed a correlation with surface slope. The difference between the two data sets ranged from 84 cm +/- 79 cm for slopes below 0...

  8. ESA airborne campaigns in support of Earth Explorers

    Science.gov (United States)

    Casal, Tania; Davidson, Malcolm; Schuettemeyer, Dirk; Perrera, Andrea; Bianchi, Remo

    2013-04-01

    In the framework of its Earth Observation Programmes the European Space Agency (ESA) carries out ground based and airborne campaigns to support geophysical algorithm development, calibration/validation, simulation of future spaceborne earth observation missions, and applications development related to land, oceans and atmosphere. ESA has been conducting airborne and ground measurements campaigns since 1981 by deploying a broad range of active and passive instrumentation in both the optical and microwave regions of the electromagnetic spectrum such as lidars, limb/nadir sounding interferometers/spectrometers, high-resolution spectral imagers, advanced synthetic aperture radars, altimeters and radiometers. These campaigns take place inside and outside Europe in collaboration with national research organisations in the ESA member states as well as with international organisations harmonising European campaign activities. ESA campaigns address all phases of a spaceborne missions, from the very beginning of the design phase during which exploratory or proof-of-concept campaigns are carried out to the post-launch exploitation phase for calibration and validation. We present four recent campaigns illustrating the objectives and implementation of such campaigns. Wavemill Proof Of Concept, an exploratory campaign to demonstrate feasibility of a future Earth Explorer (EE) mission, took place in October 2011 in the Liverpool Bay area in the UK. The main objectives, successfully achieved, were to test Astrium UKs new airborne X-band SAR instrument capability to obtain high resolution ocean current and topology retrievals. Results showed that new airborne instrument is able to retrieve ocean currents to an accuracy of ± 10 cms-1. The IceSAR2012 campaign was set up to support of ESA's EE Candidate 7,BIOMASS. Its main objective was to document P-band radiometric signatures over ice-sheets, by upgrading ESA's airborne POLARIS P-band radar ice sounder with SAR capability. Campaign

  9. Recent Elevation Changes on Bagley Ice Valley, Guyot and Yahtse Glaciers, Alaska, from ICESat Altimetry, Star-3i Airborne, and SRTM Spaceborne DEMs

    Science.gov (United States)

    Muskett, R. R.; Sauber, J. M.; Lingle, C. S.; Rabus, B. T.; Tangborn, W. V.; Echelmeyer, K. A.

    2005-12-01

    Three- to 5-year surface elevation changes on Bagley Ice Valley, Guyot and Yahtse Glaciers, in the eastern Chugach and St. Elias Mtns of south-central Alaska, are estimated using ICESat-derived data and digital elevation models (DEMs) derived from interferometric synthetic aperture radar (InSAR) data. The surface elevations of these glaciers are influenced by climatic warming superimposed on surge dynamics (in the case of Bagley Ice Valley) and tidewater glacier dynamics (in the cases of Guyot and Yahtse Glaciers) in this coastal high-precipitation regime. Bagley Ice Valley / Bering Glacier last surged in 1993-95. Guyot and Yahtse Glaciers, as well as the nearby Tyndell Glacier, have experienced massive tidewater retreat during the past century, as well as during recent decades. The ICESat-derived elevation data we employ were acquired in early autumn in both 2003 and 2004. The NASA/NIMA Shuttle Radar Topography Mission (SRTM) DEM that we employ was derived from X-band InSAR data acquired during this 11-22 Feb. 2000 mission and processed by the German Aerospace Center. This DEM was corrected for estimated systematic error, and a mass balance model was employed to account for seasonal snow accumulation. The Star-3i airborne, X-band, InSAR-derived DEM that we employ was acquired 4-13 Sept. 2000 by Intermap Technologies, Inc., and was also processed by them. The ICESat-derived profiles crossing Bagley Ice Valley, differenced with Star-3i DEM elevations, indicate preliminary mean along-profile elevation increases of 5.6 ± 3.4 m at 1315 m altitude, 7.4 ± 2.7 m at 1448 m altitude, 4.7 ± 1.9 m at 1557 m altitude, 1.3 ± 1.4 m at 1774 m altitude, and 2.5 ± 1.5 m at 1781 m altitude. This is qualitatively consistent with the rising surface on Bagley Ice Valley observed by Muskett et al. [2003]. The ICESat-derived profiles crossing Yahtse Glacier, differenced with the SRTM DEM elevations, indicate preliminary mean elevation changes (negative implies decrease) of -0.9 ± 3

  10. Ultra-Wideband, Dual-Polarized, Beam-Steering P-Band Array Antenna

    Science.gov (United States)

    duToit, Cornelis

    2014-01-01

    A dual-polarized, wide-bandwidth (200 MHz for one polarization, 100 MHz for the orthogonal polarization) antenna array at P-band was designed to be driven by NASA's EcoSAR digital beam former. EcoSAR requires two wide P-band antenna arrays mounted on the wings of an aircraft, each capable of steering its main beam up to 35deg off-boresight, allowing the twin radar beams to be steered at angles to the flight path. The science requirements are mainly for dual-polarization capability and a wide bandwidth of operation of up to 200 MHz if possible, but at least 100 MHz with high polarization port isolation and low cross-polarization. The novel design geometry can be scaled with minor modifications up to about four times higher or down to about half the current design frequencies for any application requiring a dual-polarized, wide-bandwidth steerable antenna array. EcoSAR is an airborne interferometric P-band synthetic aperture radar (SAR) research application for studying two- and three-dimensional fine-scale measurements of terrestrial ecosystem structure and biomass, which will ultimately aid in the broader study of the carbon cycle and climate change. The two 2×8 element Pband antenna arrays required by the system will be separated by a baseline of about 25 m, allowing for interferometry measurements. The wide 100-to- 200-MHz bandwidth dual-polarized beams employed will allow the determination of the amount of biomass and even tree height on the ground. To reduce the size of the patches along the boresight dimension in order to fit them into the available space, two techniques were employed. One technique is to add slots along the edges of each patch where the main electric currents are expected to flow, and the other technique is to bend the central part of the patch away from the ground plane. The latter also facilitates higher mechanical rigidity. The high port isolation of more than 40 dB was achieved by employing a highly symmetrical feed mechanism for each

  11. AirMOSS P-Band Radar Retrieval of Subcanopy Soil Moisture Profile

    Science.gov (United States)

    Tabatabaeenejad, A.; Burgin, M. S.; Duan, X.; Moghaddam, M.

    2013-12-01

    Knowledge of soil moisture, as a key variable of the Earth system, plays an important role in our under-standing of the global water, energy, and carbon cycles. The importance of such knowledge has led NASA to fund missions such as Soil Moisture Active and Passive (SMAP) and Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS). The AirMOSS mission seeks to improve the estimates of the North American Net Ecosystem Exchange (NEE) by providing high-resolution observations of the root zone soil moisture (RZSM) over regions representative of the major North American biomes. AirMOSS flies a P-band SAR to penetrate vegetation and into the root zone to provide estimates of RZSM. The flights cover areas containing flux tower sites in regions from the boreal forests in Saskatchewan, Canada, to the tropical forests in La Selva, Costa Rica. The radar snapshots are used to generate estimates of RZSM via inversion of a scattering model of vegetation overlying soils with variable moisture profiles. These retrievals will be used to generate a time record of RZSM, which will be integrated with an ecosystem demography model in order to estimate the respiration and photosynthesis carbon fluxes. The aim of this work is the retrieval of the moisture profile over AirMOSS sites using the collected P-band radar data. We have integrated layered-soil scattering models into a forest scattering model; for the backscattering from ground and for the trunk-ground double-bounce mechanism, we have used a layered small perturbation method and a coherent scattering model of layered soil, respectively. To estimate the soil moisture profile, we represent it as a second-order polynomial in the form of az2 + bz + c, where z is the depth and a, b, and c are the coefficients to be retrieved from radar measurements. When retrieved, these coefficients give us the soil moisture up to a prescribed depth of validity. To estimate the unknown coefficients of the polynomial, we use simulated

  12. A High Efficiency 1kWatt GaN amplifier for P-Band pulsed applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An improved efficiency amplifier for high power pulse applications at P-Band will be investigated that will support space based RADAR systems. Current P-Band pulsed...

  13. A High Efficiency 1kWatt GaN Amplifier for P-Band Pulsed Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An improved efficiency amplifier for high power pulse applications at P-Band will be investigated that will support space based RADAR systems. Current P-Band pulsed...

  14. Improved ice loss estimate of the northwestern Greenland ice sheet

    OpenAIRE

    Kjeldsen, K. K.; Khan, S. A.; van den Broeke, M.R.; van Angelen, J.H.

    2013-01-01

    We estimate ice volume change rates in the northwest Greenland drainage basin during 2003–2009 using Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter data. Elevation changes are often reported to be largest near the frontal portion of outlet glaciers. To improve the volume change estimate, we supplement the ICESat data with altimeter surveys from NASA’s Airborne Topographic Mapper from 2002 to 2010 and NASA’s Land, Vegetation and Ice Sensor from 2010. The Airborne data are mai...

  15. A combined approach of remote sensing and airborne electromagnetics to determine the volume of polynya sea ice in the Laptev Sea

    Directory of Open Access Journals (Sweden)

    L. Rabenstein

    2013-02-01

    Full Text Available A combined interpretation of synthetic aperture radar (SAR satellite images and helicopter electromagnetic (HEM sea-ice thickness data has provided an estimate of sea-ice volume formed in Laptev Sea polynyas during the winter of 2007/08. The evolution of the surveyed sea-ice areas, which were formed between late December 2007 and middle April 2008, was tracked using a series of SAR images with a sampling interval of 2–3 days. Approximately 160 km of HEM data recorded in April 2008 provided sea-ice thicknesses along profiles that transected sea-ice varying in age from 1–116 days. For the volume estimates, thickness information along the HEM profiles was extrapolated to zones of the same age. The error of areal mean thickness information was estimated to be between 0.2 m for younger ice and up to 1.55 m for older ice, with the primary error source being the spatially limited HEM coverage. Our results have demonstrated that the modal thicknesses and mean thicknesses of level ice correlated with the sea-ice age, but that varying dynamic and thermodynamic sea-ice growth conditions resulted in a rather heterogeneous sea-ice thickness distribution on scales of tens of kilometers. Taking all uncertainties into account, total sea-ice area and volume produced within the entire surveyed area were 52 650 km2 and 93.6 ± 26.6 km3. The surveyed polynya contributed 2.0 ± 0.5% of the sea-ice produced throughout the Arctic during the 2007/08 winter. The SAR-HEM volume estimate compares well with the 112 km3 ice production calculated with a high resolution ocean sea-ice model. Measured modal and mean-level ice thicknesses correlate with calculated freezing-degree-day thicknesses with a factor of 0.87–0.89, which was too low to justify the assumption of homogeneous thermodynamic growth conditions in the area, or indicates a strong dynamic thickening of level ice by rafting of even thicker ice.

  16. A combined approach of remote sensing and airborne electromagnetics to determine the volume of polynya sea ice in the Laptev Sea

    Directory of Open Access Journals (Sweden)

    L. Rabenstein

    2013-06-01

    Full Text Available A combined interpretation of synthetic aperture radar (SAR satellite images and helicopter electromagnetic (HEM sea-ice thickness data has provided an estimate of sea-ice volume formed in Laptev Sea polynyas during the winter of 2007/08. The evolution of the surveyed sea-ice areas, which were formed between late December 2007 and middle April 2008, was tracked using a series of SAR images with a sampling interval of 2–3 days. Approximately 160 km of HEM data recorded in April 2008 provided sea-ice thicknesses along profiles that transected sea ice varying in age from 1 to 116 days. For the volume estimates, thickness information along the HEM profiles was extrapolated to zones of the same age. The error of areal mean thickness information was estimated to be between 0.2 m for younger ice and up to 1.55 m for older ice, with the primary error source being the spatially limited HEM coverage. Our results have demonstrated that the modal thicknesses and mean thicknesses of level ice correlated with the sea-ice age, but that varying dynamic and thermodynamic sea-ice growth conditions resulted in a rather heterogeneous sea-ice thickness distribution on scales of tens of kilometers. Taking all uncertainties into account, total sea-ice area and volume produced within the entire surveyed area were 52 650 km2 and 93.6 ± 26.6 km3. The surveyed polynya contributed 2.0 ± 0.5% of the sea-ice produced throughout the Arctic during the 2007/08 winter. The SAR-HEM volume estimate compares well with the 112 km3 ice production calculated with a~high-resolution ocean sea-ice model. Measured modal and mean-level ice thicknesses correlate with calculated freezing-degree-day thicknesses with a factor of 0.87–0.89, which was too low to justify the assumption of homogeneous thermodynamic growth conditions in the area, or indicates a strong dynamic thickening of level ice by rafting of even thicker ice.

  17. Electrical performance verification methodology for the P-band SAR payload of the BIOMASS candidate mission

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Kim, Oleksiy S.; Breinbjerg, Olav; Pontoppidan, K; Østergaard, A.; Lin, C. C.

    2012-01-01

    In this paper, an electrical performance verification methodology is proposed for the large deployable reflector antenna of the BIOMASS P-band (435 MHz) synthetic aperture radar (SAR). The proposed methodology is based on measurement of the feed characteristics, such as complex pattern and...

  18. The relation between Arctic sea ice surface elevation and draft: A case study using coincident AUV sonar and airborne scanning laser

    DEFF Research Database (Denmark)

    Doble, Martin J.; Skourup, Henriette; Wadhams, Peter;

    2011-01-01

    = 3.4 (level) and R = 4.2 (deformed). The "minimum elevation within a footprint" characteristic reported for CryoSat was less stable, significantly overestimating R for level ice (R > 5) and deformed ice (R > 6). The mean draft difference between measurements and isostasy suggests 70 m as an isostatic...

  19. Use of the SAR (Synthetic Aperture Radar) P band for detection of the Moche and Lambayeque canal networks in the Apurlec region, Perù

    Science.gov (United States)

    Ilaria Pannaccione Apa, Maria; Santovito, Maria Rosaria; Pica, Giulia; Catapano, Ilaria; Fornaro, Gianfranco; Lanari, Riccardo; Soldovieri, Francesco; Wester La Torre, Carlos; Fernandez Manayalle, Marco Antonio; Longo, Francesco; Facchinetti, Claudia; Formaro, Roberto

    2016-04-01

    In recent years, research attention has been devoted to the development of a new class of airborne radar systems using low frequency bands ranging from VHF/UHF to P and L ones. In this frame, the Italian Space Agency (ASI) has promoted the development of a new multi-mode and multi-band airborne radar system, which can be considered even a "proof-of-concept" for the next space-borne missions. In particular, in agreement with the ASI, the research consortium CO.RI.S.T.A. has in charge the design, development and flight validation of such a kind of system, which is the first airborne radar entirely built in Italy. The aim was to design and realize a radar system able to work in different modalities as: nadir-looking sounder at VHF band (163 MHz); side-looking imager (SAR) at P band with two channels at 450 MHz and 900 MHz. The P-band is a penetration radar. Exploiting penetration features of low frequency electromagnetic waves, dielectric discontinuities of observed scene due to inhomogeneous materials rise up and can be detected on the resulting image. Therefore buried objects or targets placed under vegetation may be detected. Penetration capabilities essentially depend on microwave frequency. Typically, penetration distance is inversely proportional to microwave frequency. The higher the frequency, the lower the penetration depth. Terrain characteristics affect penetration capabilities. Humidity acts as a shield to microwave penetration. Hence terrain with high water content are not good targets for P-band applicability. Science community, governments and space agencies have increased their interest about low frequency radar for their useful applicability in climatology, ecosystem monitoring, glaciology, archaeology. The combination of low frequency and high relative bandwidth of such a systems has a large applicability in both military and civilian applications, ranging from forestry applications, biomass measuring, archaeological and geological exploration

  20. A combined approach of remote sensing and airborne electromagnetics to determine the volume of polynya sea ice in the Laptev Sea

    OpenAIRE

    L. Rabenstein; T. Krumpen; Hendricks, S.; C. Koeberle; Haas, C.; Hoelemann, J. A.

    2013-01-01

    A combined interpretation of synthetic aperture radar (SAR) satellite images and helicopter electromagnetic (HEM) sea-ice thickness data has provided an estimate of sea-ice volume formed in Laptev Sea polynyas during the winter of 2007/08. The evolution of the surveyed sea-ice areas, which were formed between late December 2007 and middle April 2008, was tracked using a series of SAR images with a sampling interval of 2–3 days. Approximately 160 km of HEM data recorded in April 2008 provided ...

  1. Direction-of-Arrival Estimation for Radar Ice Sounding Surface Clutter Suppression

    DEFF Research Database (Denmark)

    Nielsen, Ulrik; Dall, Jørgen

    2015-01-01

    recent surface clutter suppression techniques are based on multi-phase-center systems combined with sophisticated coherent postprocessing. The performance of the techniques can be improved by accurate direction-of-arrival (DOA) estimates of the surface clutter. This paper deals with data-driven DOA...... estimation for surface clutter signals, which includes a formulation of the mathematical foundation of spatial aliasing. DOA estimation is applied to data acquired with the P-band POLarimetric Airborne Radar Ice Sounder at the Jutulstraumen Glacier, Antarctica. The effects of spatial aliasing related to a...... large phase center spacing are analyzed, and an unwrapping procedure is presented and applied to the data. Finally, DOA estimation of full-scene data is analyzed and used to show an along-track and incidence (off-nadir) angle dependent variation of the effective scattering center of the surface return...

  2. Ground Observation and Correction of P-band Radar Imaging Ionospheric Effects

    Directory of Open Access Journals (Sweden)

    Zhao Ning

    2014-02-01

    Full Text Available For high resolution space-borne P-band SAR system, ionospheric effects could cause serious phase errors. These errors are causally related to the radar frequency and the TEC of ionosphere and make the image quality degraded. To guarantee the image quality, the ionosphere errors must be emended. Based on the mismatched filter model caused by ionosphere, it is pointed out that accurate ionosphere TEC is the key for phase error correction, a high precision ionosphere TEC measurement method is further put forward by using the phase errors of SAR echoes, which is validated by processing the data of a ground based P-band radar with well focused radar image of the international space station obtained. The results indicate that the method can effectively increase the accuracy of ionosphere TEC estimation, and thus improve the radar imaging quality, it is applicable to low frequency space-borne SAR systems for reducing the ionosphere effects.

  3. Spaceborne Applications of P Band Imaging Radars for Measuring Forest Biomass

    OpenAIRE

    Rignot, EJ; Zimmermann, R.; van Zyl, JJ

    1995-01-01

    In three sites of boreal and temperate forests, P band HH, HV, and VV polarization data combined estimate total aboveground dry woody biomass within 12 to 27% of the values derived from allometric equations, depending on forest complexity. Biomass estimates derived from HV-polarization data only are 2 to 14% less accurate. When the radar operates at circular polarization, the errors exceed 100% over flooded forests, wet or damaged trees and sparse open tall forests because double-bounce refle...

  4. Improved ice loss estimate of the northwestern Greenland ice sheet

    DEFF Research Database (Denmark)

    Kjeldsen, K. K.; Khan, Shfaqat Abbas; Wahr, J.;

    2013-01-01

    We estimate ice volume change rates in the northwest Greenland drainage basin during 2003–2009 using Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter data. Elevation changes are often reported to be largest near the frontal portion of outlet glaciers. To improve the volume change...... estimate, we supplement the ICESat data with altimeter surveys from NASA's Airborne Topographic Mapper from 2002 to 2010 and NASA's Land, Vegetation and Ice Sensor from 2010. The Airborne data are mainly concentrated along the ice margin and thus have a significant impact on the estimate of the volume...

  5. Proposal of a novel compact P-band magnetically insulated transmission line oscillator with inclined vanes

    International Nuclear Information System (INIS)

    In this paper, we present a novel compact P-band magnetically insulated transmission line oscillator (MILO) with specially inclined slow-wave-structure (SWS) vanes to decrease its total dimension and weight. The dispersion characteristics of the inclined SWS are investigated in detail and made comparisons with that of the traditional straight SWS. The results show that the inclined SWS is more advantageous in operating on a steady frequency in a wide voltage range and has a better asymmetric mode segregation and a relatively large band-gap between the TM00 and TM01 modes which are in favor of avoiding the asymmetric and transverse mode competition. Besides, the transverse dimension of the proposed novel inclined SWS with the same operation frequency is decreased by about 50%, and correspondingly the device volume shrinks remarkably to its 0.35 times. In particle-in-cell simulation, the electron bunching spokes are obviously formed in the inclined SWS, and a P-band high-power microwave with a power of 5.8 GW, frequency of 645 MHz, and efficiency of 17.2% is generated by the proposed device, which indicates the feasibility of the compact design with the inclined vanes at the P-band

  6. Probing obscured, high redshift galaxies using deep P-band continuum imaging with GMRT

    CERN Document Server

    Wadadekar, Yogesh; Ishwara-Chandra, C H; Singh, Veeresh; Beelen, Alexandre; Omont, Alain

    2014-01-01

    We have carried out a deep (150 micro Jy rms) P-band, continuum imaging survey of about 40 square degrees of sky in the XMM-LSS, Lockman Hole and ELAIS-N1 fields with the GMRT. Our deep radio data, combined with deep archival observations in the X-ray (XMM/Chandra), optical (SDSS, CFHTLS), near-infrared (UKIDSS, VISTA/VIDEO), mid-infrared (Spitzer/SWIRE, Spitzer/SERVS) and far-infrared (Spitzer/SWIRE, Herschel/HerMES) will enable us to obtain an accurate census of star-forming and active galaxies out to z~2. This panchromatic coverage enables accurate determination of photometric redshifts and accurate modeling of the spectral energy distribution. We are using our large, merged photometric catalog of over 10000 galaxies to pursue a number of science goals.

  7. Soil Moisture Estimate under Forest using a Semi-empirical Model at P-Band

    Science.gov (United States)

    Truong-Loi, M.; Saatchi, S.; Jaruwatanadilok, S.

    2013-12-01

    In this paper we show the potential of a semi-empirical algorithm to retrieve soil moisture under forests using P-band polarimetric SAR data. In past decades, several remote sensing techniques have been developed to estimate the surface soil moisture. In most studies associated with radar sensing of soil moisture, the proposed algorithms are focused on bare or sparsely vegetated surfaces where the effect of vegetation can be ignored. At long wavelengths such as L-band, empirical or physical models such as the Small Perturbation Model (SPM) provide reasonable estimates of surface soil moisture at depths of 0-5cm. However for densely covered vegetated surfaces such as forests, the problem becomes more challenging because the vegetation canopy is a complex scattering environment. For this reason there have been only few studies focusing on retrieving soil moisture under vegetation canopy in the literature. Moghaddam et al. developed an algorithm to estimate soil moisture under a boreal forest using L- and P-band SAR data. For their studied area, double-bounce between trunks and ground appear to be the most important scattering mechanism. Thereby, they implemented parametric models of radar backscatter for double-bounce using simulations of a numerical forest scattering model. Hajnsek et al. showed the potential of estimating the soil moisture under agricultural vegetation using L-band polarimetric SAR data and using polarimetric-decomposition techniques to remove the vegetation layer. Here we use an approach based on physical formulation of dominant scattering mechanisms and three parameters that integrates the vegetation and soil effects at long wavelengths. The algorithm is a simplification of a 3-D coherent model of forest canopy based on the Distorted Born Approximation (DBA). The simplified model has three equations and three unknowns, preserving the three dominant scattering mechanisms of volume, double-bounce and surface for three polarized backscattering

  8. IceBridge BedMachine Greenland

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains bed topography beneath the Greenland Ice Sheet based on mass conservation derived from airborne radar tracks and satellite radar. The data...

  9. GPR capabilities for ice thickness sampling of low salinity ice and for detecting oil in ice

    Energy Technology Data Exchange (ETDEWEB)

    Lalumiere, Louis [Sensors by Design Ltd. (Canada)

    2011-07-01

    This report discusses the performance and capabilities test of two airborne ground-penetrating radar (GPR) systems of the Bedford Institute of Oceanography (BIO), Noggin 1000 and Noggin 500, for monitoring low salinity snow and ice properties which was used to measure the thickness of brackish ice on Lake Melville in Labrador and on a tidal river in Prince Edward Island. The work of other researchers is documented and the measurement techniques proposed are compared to the actual GPR approach. Different plots of GPR data taken over snow and freshwater ice and over ice with changing salinity are discussed. An interpretation of brackish ice GPR plots done by the Noggin 1000 and Noggin 500 systems is given based on resolution criterion. Additionally, the capability of the BIO helicopter-borne GPR to detect oil-in-ice has been also investigated, and an opinion on the likelihood of the success of GPR as an oil-in-ice detector is given.

  10. Radiostratigraphy and age structure of the Greenland Ice Sheet

    OpenAIRE

    Macgregor, JA; Fahnestock, MA; Catania, GA; Paden, JD; Prasad Gogineni, S; Young, SK; Rybarski, SC; Mabrey, AN; Wagman, BM; M. Morlighem

    2015-01-01

    Several decades of ice-penetrating radar surveys of the Greenland and Antarctic ice sheets have observed numerous widespread internal reflections. Analysis of this radiostratigraphy has produced valuable insights into ice sheet dynamics and motivates additional mapping of these reflections. Here we present a comprehensive deep radiostratigraphy of the Greenland Ice Sheet from airborne deep ice-penetrating radar data collected over Greenland by The University of Kansas between 1993 and 2013. T...

  11. European Space Agency Campaign Activities in Support of Earth Observation Projects: Examples for Snow and Ice

    Science.gov (United States)

    Schüttemeyer, D.; Davidson, M.; Casal, T.; Perrera, A.; Bianchi, R.; Kern, M.; Scipal, K.

    2012-04-01

    studies at phase A level for further down-selection in 2013. The Candidate missions under consideration are: -BIOMASS - Global measurements of forest biomass and extent, -CoReH2O - (Cold Regions Hydrology High-resolution Observatory) - Detailed observations of key snow, ice and water cycle characteristics, -PREMIER - (PRocess Exploration through Measurements of Infrared and millimetre- wave Emitted Radiation)-Understanding the processes that link trace gases, radiation, chemistry and climate in the atmosphere. This paper focuses on describing the current setup for campaign execution in the context of CoReH2O and BIOMASS focusing on applications for Snow and Ice. The CoReH2O primary mission objectives are to observe snow water equivalent, to improve the modelling of snow and ice processes, and to advance the prediction of stream flow in regions where snow and glacier melt are important components of the water balance. Snow cover and glaciers are not only key components of the water balance in high latitudes, but are also vital resources of fresh water for many densely populated areas at mid and low latitudes. A dual frequency SAR, operating at X-band (9.6 GHz) and Ku-band (17.2 GHz), VV and VH polarizations, with a swath width of about 100 km, has been selected for this mission. It will operate in two consecutive mission phases to deliver snow and ice information over two temporal scales (3 days and 12-15 days). The BIOMASS primary mission objectives are to improve estimates of carbon stocks and fluxes over land through global measurements of forest biomass and changes in this biomass with time. The mission concept is based on novel spaceborne P-band synthetic aperture polarimetric radar operating at 435 MHz and with 6 MHz bandwidth. Among the additional application areas of the mission, the potential of BIOMASS to provide ice sheet motion products and subsurface structure maps is considered of highest scientific interest as - with the longer wavelength at P-Band -the

  12. The Ecosystems SAR (EcoSAR) an Airborne P-band Polarimetric InSAR for the Measurement of Vegetation Structure, Biomass and Permafrost

    Science.gov (United States)

    Rincon, Rafael F.; Fatoyinbo, Temilola; Ranson, K. Jon; Osmanoglu, Batuhan; Sun, Guoqing; Deshpande, Manohar D.; Perrine, Martin L.; Du Toit, Cornelis F.; Bonds, Quenton; Beck, Jaclyn; Lu, Daniel

    2014-01-01

    EcoSAR is a new synthetic aperture radar (SAR) instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. The instrument uses a phased-array beamforming architecture and supports full polarimetric measurements and single pass interferometry. This Instrument development is part of NASA's Earth Science Technology Office Instrument Incubator Program (ESTO IIP).

  13. Reconstructing ice-sheet accumulation rates at ridge B, East Antarctica

    OpenAIRE

    Leysinger Vieli, G. J.-M. C.; Siegert, M.J.; Payne, A.J.

    2004-01-01

    Understanding how ice sheets responded to past climate change is fundamental to forecasting how they will respond in the future. Numerical models calculating the evolution of ice sheets depend upon accumulation data, which are principally available from ice cores. Here, we calculate past rates of ice accumulation using internal layering. The englacial structure of the East Antarctic ice divide at ridge B is extracted from airborne ice-penetrating radar. The isochronous surfaces are dated at t...

  14. Recent summer sea ice thickness surveys in Fram Strait and associated ice volume fluxes

    OpenAIRE

    T. Krumpen; R. Gerdes; Haas, C.; Hendricks, S.; A. Herber; Selyuzhenok, V.; Smedsrud, L.; Spreen, G.

    2016-01-01

    Fram Strait is the main gateway for sea ice export out of the Arctic Ocean, and therefore observations there give insight into the composition and properties of Arctic sea ice in general and how it varies over time. A data set of ground-based and airborne electromagnetic ice thickness measurements collected during summer between 2001 and 2012 is presented here, including long transects well into the southern part of the Transpolar Drift obtained using fixed-wing aircrafts. T...

  15. Large-scale ice thickness distribution of first-year sea ice in spring and summer north of Svalbard

    OpenAIRE

    Renner, Angelika; Hendricks, Stefan; Gerland, Sebastian; Beckers, Justin M.; Haas, Christian; Krumpen, Thomas

    2013-01-01

    The large-scale thickness distribution of sea ice was measured during several campaigns in the European Arctic north of Svalbard from 2007 using an airborne electromagnetic induction device. In August 2010 and April–May 2011, this was complemented by extensive on-ice work including measurements of snow thickness and freeboard. Ice thicknesses show a clear difference between the seasons, with thicker ice during spring than in summer. In spring 2011, negative freeboard and flooding were observe...

  16. High-resolution ice thickness and bed topography of a land-terminating section of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Lindbäck, K.; Pettersson, R.; Doyle, S. H.;

    2014-01-01

    We present ice thickness and bed topography maps with high spatial resolution (250 to 500 m) of a and-terminating section of the Greenland Ice Sheet derived from combined ground-based and airborne radar surveys. The data have a total area of ~12000 km2 and cover the whole ablation area of the....... The covered area is one of the most studied regions of the Greenland Ice Sheet with studies of mass balance, dynamics, and supraglacial lakes, and our combined dataset can be valuable for detailed studies of ice sheet dynamics and hydrology. The compiled datasets of ground-based and airborne radar...

  17. Airborne campaigns for CryoSat pre-launch calibration and validation

    DEFF Research Database (Denmark)

    Hvidegaard, Sine Munk; Forsberg, René; Skourup, Henriette;

    2010-01-01

    From 2003 to 2008 DTU Space together with ESA and several international partners carried out airborne and ground field campaigns in preparation for CryoSat validation; called CryoVEx: CryoSat Validation Experiments covering the main ice caps in Greenland, Canada and Svalbard and sea ice...... in the Arctic Ocean. The main goal of the airborne surveys was to acquire coincident scanning laser and CryoSat type radar elevation measurements of the surface; either sea ice or land ice. Selected lines have been surveyed along with detailed mapping of validation sites coordinated with insitu field work...

  18. Mass Balance Changes and Ice Dynamics of Greenland and Antarctic Ice Sheets from Laser Altimetry

    Science.gov (United States)

    Babonis, G. S.; Csatho, B.; Schenk, T.

    2016-06-01

    During the past few decades the Greenland and Antarctic ice sheets have lost ice at accelerating rates, caused by increasing surface temperature. The melting of the two big ice sheets has a big impact on global sea level rise. If the ice sheets would melt down entirely, the sea level would rise more than 60 m. Even a much smaller rise would cause dramatic damage along coastal regions. In this paper we report about a major upgrade of surface elevation changes derived from laser altimetry data, acquired by NASA's Ice, Cloud and land Elevation Satellite mission (ICESat) and airborne laser campaigns, such as Airborne Topographic Mapper (ATM) and Land, Vegetation and Ice Sensor (LVIS). For detecting changes in ice sheet elevations we have developed the Surface Elevation Reconstruction And Change detection (SERAC) method. It computes elevation changes of small surface patches by keeping the surface shape constant and considering the absolute values as surface elevations. We report about important upgrades of earlier results, for example the inclusion of local ice caps and the temporal extension from 1993 to 2014 for the Greenland Ice Sheet and for a comprehensive reconstruction of ice thickness and mass changes for the Antarctic Ice Sheets.

  19. Airborne geoid determination

    DEFF Research Database (Denmark)

    Forsberg, René; Olesen, Arne Vestergaard; Bastos, L.; Gidskehaug, A.; Meyer, U.; Timmen, L.

    2000-01-01

    Airborne geoid mapping techniques may provide the opportunity to improve the geoid over vast areas of the Earth, such as polar areas, tropical jungles and mountainous areas, and provide an accurate "seam-less" geoid model across most coastal regions. Determination of the geoid by airborne methods...... relies on the development of airborne gravimetry, which in turn is dependent on developments in kinematic GPS. Routine accuracy of airborne gravimetry are now at the 2 mGal level, which may translate into 5-10 cm geoid accuracy on regional scales. The error behaviour of airborne gravimetry is well...

  20. Altimetry study performed using an airborne GNSS-reflectometer

    OpenAIRE

    Rodríguez Álvarez, Nereida; Acevo Herrera, René; Aguasca Solé, Alberto; Valencia Domènech, Enric; Camps Carmona, Adriano José; Vall-Llossera Ferran, Mercedes Magdalena; Bosch Lluís, Xavier; Ramos Pérez, Isaac

    2010-01-01

    The Global Navigation Satellite Signals Reflections (GNSSR)techniques have been widely used for remote sensing purposes retrieving geophysical parameters over different types of surfaces. Over the ocean, altimetry or sea state can be retrieved. Over land, soil moisture can be inferred and over ice, altimetry, and ice age are also retrieved. This paper presents the results of using GNSS-R techniques to retrieve altimetry from the measurements of an airborne GNSS-Reflectometer. Peer Reviewed

  1. ESA CryoVEx 2014 - Airborne ASIRAS radar and laser scanner measurements during 2014 CryoVEx campaign in the Arctic

    OpenAIRE

    Hvidegaard, S. M.; Nielsen, J. E.; Sørensen, L Sandberg; Simonsen, S. B.; H. Skourup; Forsberg, R.; V. Helm; Bjerg, T.

    2015-01-01

    This report outlines the airborne field operations with the ESA airborne Ku‐band interferometric radar (ASIRAS), coincident airborne laser scanner (ALS) and vertical photography to acquire data over sea‐ and land ice along validation sites and CryoSat‐2 ground tracks. The airborne campaign was coordinated by DTU Space using the Norlandair Twin Otter (TF‐POF). The campaign consisted of two experiment periods: Mid‐march to early April and late April to mid‐May with focus on sea ice and land ice...

  2. ESA CryoVEx 2012:Airborne field campaign with ASIRAS radar, EM induction sounder and laser scanner

    OpenAIRE

    Skourup, Henriette; Einarsson, Indriði; Forsberg, René; Haas, C.; Helms, V.; Hvidegaard, Sine Munk; Nilsson, Johan; Olesen, Arne Vestergaard; Olesen, Adolfientje Kasenda

    2012-01-01

    This report describes the airborne part of the Arctic CryoSat Validation Experiment (CryoVEx) 2012, which took place in the period March 25 – May 5, 2012, and includes; 1) Data collected with the ESA airborne Ku‐band interferometric radar (ASIRAS), coincident airborne laser scanner (ALS) and vertical photography to acquire data over sea‐ and land ice along CryoSat‐2 ground tracks. The airborne campaign was coordinated by DTU Space using the Norlandair Twin Otter (TF‐POF). 2) Sea ice thickness...

  3. Microwaves in Airborne Surveillance

    OpenAIRE

    Christopher, S.

    2013-01-01

    The use of microwave spectrum is widespread due to its convenience. Therefore, enormous amount of information is available in the free space channel. Obviously, mining this channel for surveillance is quite common. Airborne surveillance offers significant advantages in military operations. This paper talks of the usage of microwaves in airborne surveillance systems, in general, and in the Indian airborne early warning and control (AEW&C) System, in particular. It brings out the multiple s...

  4. The airborne EMIRAD L-band radiometer system

    DEFF Research Database (Denmark)

    Søbjærg, Sten Schmidl; Kristensen, Steen Savstrup; Balling, Jan E.;

    2013-01-01

    EMIRAD system has been installed on three different airborne platforms for measurements of sea surface signatures and salinity, soil moisture, and the homogeneity of the Antarctic SMOS calibration site. The installations are shown in the paper, and some major results for ocean and ice observations are...

  5. Ice flux divergence anomalies on 79north Glacier, Greenland

    DEFF Research Database (Denmark)

    Seroussi, H.; Morlighem, M.; Rignot, E.;

    2011-01-01

    The ice flux divergence of a glacier is an important quantity to examine because it determines the rate of temporal change of its thickness. Here, we combine high-resolution ice surface velocity observations of Nioghalvfjerdsfjorden (79north) Glacier, a major outlet glacier in north Greenland, with...... a dense grid of ice thickness data collected with an airborne radar sounder in 1998, to examine its ice flux divergence. We detect large variations, up to 100 m/yr, in flux divergence on grounded ice that are incompatible with what we know of the glacier surface mass balance, basal mass balance and...... onto a regular grid using a scheme (here block kriging) that does not conserve mass or ice flux. This problem is not unique to 79north Glacier but is common to all conventional ice thickness surveys of glaciers and ice sheets; and fundamentally limits the application of ice thickness grids to high...

  6. Ice Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, atmospheric trace gases, and other aspects of climate and environment derived from ice cores drilled on glaciers and ice...

  7. IceBridge: Bringing a Field Campaign Home

    Science.gov (United States)

    Woods, J.; Beck, J.; Bartholow, S.

    2015-12-01

    IceBridge, a six-year NASA mission, is the largest airborne survey of Earth's polar ice ever flown. It will yield an unprecedented three-dimensional view of Arctic and Antarctic ice sheets, ice shelves and sea ice. These flights will provide a yearly, multi-instrument look at the behavior of the rapidly changing features of the Greenland and Antarctic ice. Data collected during IceBridge will help scientists bridge the gap in polar observations between NASA's Ice, Cloud and Land Elevation Satellite (ICESat) -- in orbit since 2003 -- and ICESat-2, planned for 2017. ICESat stopped collecting science data in 2009, making IceBridge critical for ensuring a continuous series of observations. IceBridge will use airborne instruments to map Arctic and Antarctic areas once a year at a minimum, with new campaigns being developed during the Arctic melt season. IceBridge flights are conducted in the spring and summer for the Arctic and in the fall over Antarctica. Other smaller airborne surveys around the world are also part of the IceBridge campaign. IceBridge actively engages the public and educators through a variety of outlets ranging from communications strategies through social media outlets, to larger organized efforts such as PolarTREC. In field activities include blog posts, photo updates, in flight chat sessions, and more intensive live events to include google hangouts, where field team members can interact with the public during a scheduled broadcast. The IceBridge team provides scientists and other team members with the training and support to become communicators in their own right. There is an exciting new initiative where IceBridge will be collaborating with Undergraduate and Graduate students to integrate the next generation of scientists and communicators into the Science Teams. This will be explored through partnerships with institutions that are interested in mentoring through project based initiatives.

  8. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  9. Characterizing Arctic sea ice topography using high-resolution IceBridge data

    Science.gov (United States)

    Petty, Alek A.; Tsamados, Michel C.; Kurtz, Nathan T.; Farrell, Sinead L.; Newman, Thomas; Harbeck, Jeremy P.; Feltham, Daniel L.; Richter-Menge, Jackie A.

    2016-05-01

    We present an analysis of Arctic sea ice topography using high-resolution, three-dimensional surface elevation data from the Airborne Topographic Mapper, flown as part of NASA's Operation IceBridge mission. Surface features in the sea ice cover are detected using a newly developed surface feature picking algorithm. We derive information regarding the height, volume and geometry of surface features from 2009 to 2014 within the Beaufort/Chukchi and Central Arctic regions. The results are delineated by ice type to estimate the topographic variability across first-year and multi-year ice regimes. The results demonstrate that Arctic sea ice topography exhibits significant spatial variability, mainly driven by the increased surface feature height and volume (per unit area) of the multi-year ice that dominates the Central Arctic region. The multi-year ice topography exhibits greater interannual variability compared to the first-year ice regimes, which dominates the total ice topography variability across both regions. The ice topography also shows a clear coastal dependency, with the feature height and volume increasing as a function of proximity to the nearest coastline, especially north of Greenland and the Canadian Archipelago. A strong correlation between ice topography and ice thickness (from the IceBridge sea ice product) is found, using a square-root relationship. The results allude to the importance of ice deformation variability in the total sea ice mass balance, and provide crucial information regarding the tail of the ice thickness distribution across the western Arctic. Future research priorities associated with this new data set are presented and discussed, especially in relation to calculations of atmospheric form drag.

  10. Ice Cream

    NARCIS (Netherlands)

    Scholten, E.

    2014-01-01

    Ice cream is a popular dessert, which owes its sensorial properties (mouth feel) to its complex microstructure. The microstructure is a result of the combination of the ingredients and the production process. Ice cream is produced by simultaneous freezing and shearing of the ice cream mix, which res

  11. Legal Ice?

    DEFF Research Database (Denmark)

    Strandsbjerg, Jeppe

    The idealised land|water dichotomy is most obviously challenged by ice when ‘land practice’ takes place on ice or when ‘maritime practice’ is obstructed by ice. Both instances represent disparity between the legal codification of space and its social practice. Logically, then, both instances call...... for alternative legal thought and practice; in the following I will emphasise the former and reflect upon the relationship between ice, law and politics. Prior to this workshop I had worked more on the relationship between cartography, geography and boundaries than specifically on ice. Listening to...

  12. Surface return direction-of-arrival analysis for radar ice sounding surface clutter suppression

    DEFF Research Database (Denmark)

    Nielsen, Ulrik; Dall, Jørgen

    2015-01-01

    with coherent signal processing techniques can improve the suppression, in particular if the direction of arrival (DOA) of the clutter signal is estimated accurately. This paper deals with data-driven DOA estimation. By using P-band data from the ice shelf in Antarctica it is demonstrated that a...... varying penetration depth influences the DOA....

  13. Laser Altimetry Sampling Strategies over Sea Ice

    Science.gov (United States)

    Farrell, Sinead L.; Markus, Thorsten; Kwok, Ron; Connor, Laurence

    2011-01-01

    With the conclusion of the science phase of the Ice, Cloud and land Elevation Satellite (ICESat) mission in late 2009, and the planned launch of ICESat-2 in late 2015, NASA has recently established the IceBridge program to provide continuity between missions. A major goal of IceBridge is to obtain a sea-ice thickness time series via airborne surveys over the Arctic and Southern Oceans. Typically two laser altimeters, the Airborne Topographic Mapper (ATM) and the Land, Vegetation and Ice Sensor (LVIS), are utilized during IceBridge flights. Using laser altimetry simulations of conventional analogue systems such as ICESat, LVIS and ATM, with the multi-beam system proposed for ICESat-2, we investigate differences in measurements gathered at varying spatial resolutions and the impact on sea-ice freeboard. We assess the ability of each system to reproduce the elevation distributions of two seaice models and discuss potential biases in lead detection and sea-surface elevation, arising from variable footprint size and spacing. The conventional systems accurately reproduce mean freeboard over 25km length scales, while ICESat-2 offers considerable improvements over its predecessor ICESat. In particular, its dense along-track sampling of the surface will allow flexibility in the algorithmic approaches taken to optimize the signal-to-noise ratio for accurate and precise freeboard retrieval.

  14. Airborne wind energy

    CERN Document Server

    Ahrens, Uwe; Schmehl, Roland

    2013-01-01

    This reference offers an overview of the field of airborne wind energy. As the first book of its kind, it provides a consistent compilation of the fundamental theories, a compendium of current research and development activities as well as economic and regulatory aspects. In five parts, the book demonstrates the relevance of Airborne Wind Energy and the role that this emerging field of technology can play for the transition towards a renewable energy economy. Part I on 'Fundamentals' contains seven general chapters explaining the principles of airborne wind energy and its different variants, o

  15. Sea Ice

    Science.gov (United States)

    Perovich, D.; Gerland, S.; Hendricks, S.; Meier, Walter N.; Nicolaus, M.; Richter-Menge, J.; Tschudi, M.

    2013-01-01

    During 2013, Arctic sea ice extent remained well below normal, but the September 2013 minimum extent was substantially higher than the record-breaking minimum in 2012. Nonetheless, the minimum was still much lower than normal and the long-term trend Arctic September extent is -13.7 per decade relative to the 1981-2010 average. The less extreme conditions this year compared to 2012 were due to cooler temperatures and wind patterns that favored retention of ice through the summer. Sea ice thickness and volume remained near record-low levels, though indications are of slightly thicker ice compared to the record low of 2012.

  16. Sea ice terminology

    Energy Technology Data Exchange (ETDEWEB)

    1980-09-01

    A group of definitions of terms related to sea ice is presented, as well as a graphic representation of late winter ice zonation of the Beaufort Sea Coast. Terms included in the definition list are belt, bergy bit, bight, brash ice, calving, close pack ice, compacting, compact pack ice, concentration, consolidated pack ice, crack, diffuse ice edge, fast ice, fast-ice boundary, fast-ice edge, first-year ice, flaw, flaw lead, floe, flooded ice, fractured, fractured zone, fracturing, glacier, grey ice, grey-white ice, growler, hummock, iceberg, iceberg tongue, ice blink, ice boundary, ice cake, ice edge, ice foot, ice free, ice island, ice shelf, large fracture, lead, medium fracture, multiyear ice, nilas, old ice, open pack ice, open water, pack ice, polar ice, polynya, puddle, rafted ice, rafting, ram, ridge, rotten ice, second-year ice, shearing, shore lead, shore polynya, small fracture, strip, tabular berg, thaw holes, very close pack ice, very open pack ice, water sky, young coastal ice, and young ice.

  17. Ice Water Path Retrieval Using Microwave and Submillimetre Wave Observations

    Science.gov (United States)

    Brath, Manfred; Grützun, Verena; Mendrok, Jana; Fox, Stuart; Eriksson, Patrick; Buehler, Stefan A.

    2016-04-01

    There is an ongoing need for data on ice clouds. The ice water path as an essential climate variable is a fundamental parameter to describe ice clouds. Combined passive microwave and submillimetre wave measurements are capable to sample the size distribution of the ice particles and are sensitive to relevant particle sizes. This makes combined microwave and submillimetre wave measurements useful for estimates of ice water path. Furthermore, instead of being sensitive for the upper ice column as for example for passive visible and passive infrared measurements, combined microwave and submillimetre wave measurements can sample the full ice column. We developed a retrieval algorithm for ice water path based on a neural network approach using combined microwave and submillimetre wave measurements, from about 20 channels in the range between 89 GHz and 664 GHz of the electromagnetic sprectra. We trained a neural network by using 1D radiative transfer simulations which were conducted using the Atmospheric Radiative Transfer Simulator (ARTS). The radiative transfer simulations were fed by atmospheric profiles from a numerical weather prediction model. We will present an analysis of the retrieval. Additionally, we will present results of retrieved IWP from combined ISMAR (International SubMillimetre Airborne Radiometer) and MARSS (Microwave Airborne Radiometer Scanning System) measurements on board of the Facility for Airborne Atmospheric Measurements (FAAM) aircraft during March 2015 over the North Atlantic.

  18. Airborne campaigns for CryoSat prelaunch calibration and validation

    DEFF Research Database (Denmark)

    Skourup, Henriette; Hanson, Susanne; Hvidegaard, Sine Munk;

    2011-01-01

    After the successful launch of CryoSat-2 in April 2010, the first direct validation campaign of the satellite is planned for spring 2011. DTU Space has been involved in ESA’s CryoSat Validation Experiment (CryoVEx) with airborne activities since 2003. To validate the prelaunch performance...... of the CryoSat radar altimeter (SIRAL), an airborne version of the SIRAL altimeter (ASIRAS) has been flown together with a laser scanner in 2006 and 2008. Of particular interest is to study the penetration depth of the radar altimeter over both land- and sea ice. This can be done by comparing the radar...

  19. The airborne laser

    Science.gov (United States)

    Lamberson, Steven; Schall, Harold; Shattuck, Paul

    2007-05-01

    The Airborne Laser (ABL) is an airborne, megawatt-class laser system with a state-of-the-art atmospheric compensation system to destroy enemy ballistic missiles at long ranges. This system will provide both deterrence and defense against the use of such weapons during conflicts. This paper provides an overview of the ABL weapon system including: the notional operational concept, the development approach and schedule, the overall aircraft configuration, the technologies being incorporated in the ABL, and the current program status.

  20. Interstellar Ices

    CERN Document Server

    Boogert, A C A

    2003-01-01

    Currently ~36 different absorption bands have been detected in the infrared spectra of cold, dense interstellar and circumstellar environments. These are attributed to the vibrational transitions of ~17 different molecules frozen on dust grains. We review identification issues and summarize the techniques required to extract information on the physical and chemical evolution of these ices. Both laboratory simulations and line of sight studies are essential. Examples are given for ice bands observed toward high mass protostars, fields stars and recent work on ices in disks surrounding low mass protostars. A number of clear trends have emerged in recent years. One prominent ice component consists of an intimate mixture between H2O, CH3OH and CO2 molecules. Apparently a stable balance exists between low temperature hydrogenation and oxidation reactions on grain surfaces. In contrast, an equally prominent ice component, consisting almost entirely of CO, must have accreted directly from the gas phase. Thermal proc...

  1. Superdirective narrowband first-order probe versus wideband higher-order probe for spherical near-field antenna measurements at P-band

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Kim, Oleksiy S.; Breinbjerg, Olav

    2013-01-01

    A comparative study of the wideband 400-1200 MHz higher-order probe and the narrowband 431 MHz first-order probe, in terms of their advantages and disadvantages for spherical near-field antenna measurements at P-band, is presented. The comparison is based on the experimental data and focused on p...... pattern shape and other electrical characteristics, work efforts related to physical handling, probe calibrations, and post processing....

  2. Systems for measuring thickness of temperate and polar ice from the ground or from the air.

    Science.gov (United States)

    Watts, R.D.; Wright, D.L.

    1981-01-01

    Equipment has been designed and tested for ground-based and airborne sounding of temperate glaciers. Echoes have been obtained from ice depths of 550m using the airborne system and about 1000m using the ground-based system. -from Authors

  3. Ice shelf melt rates and 3D imaging

    Science.gov (United States)

    Lewis, Cameron Scott

    Ice shelves are sensitive indicators of climate change and play a critical role in the stability of ice sheets and oceanic currents. Basal melting of ice shelves plays an important role in both the mass balance of the ice sheet and the global climate system. Airborne- and satellite based remote sensing systems can perform thickness measurements of ice shelves. Time separated repeat flight tracks over ice shelves of interest generate data sets that can be used to derive basal melt rates using traditional glaciological techniques. Many previous melt rate studies have relied on surface elevation data gathered by airborne- and satellite based altimeters. These systems infer melt rates by assuming hydrostatic equilibrium, an assumption that may not be accurate, especially near an ice shelf's grounding line. Moderate bandwidth, VHF, ice penetrating radar has been used to measure ice shelf profiles with relatively coarse resolution. This study presents the application of an ultra wide bandwidth (UWB), UHF, ice penetrating radar to obtain finer resolution data on the ice shelves. These data reveal significant details about the basal interface, including the locations and depth of bottom crevasses and deviations from hydrostatic equilibrium. While our single channel radar provides new insight into ice shelf structure, it only images a small swatch of the shelf, which is assumed to be an average of the total shelf behavior. This study takes an additional step by investigating the application of a 3D imaging technique to a data set collected using a ground based multi channel version of the UWB radar. The intent is to show that the UWB radar could be capable of providing a wider swath 3D image of an ice shelf. The 3D images can then be used to obtain a more complete estimate of the bottom melt rates of ice shelves.

  4. Mapping of a Hydrological Ice Sheet Drainage Basin on the West Greenland Ice Sheet Margin from ERS-1/2 SAR Interferometry, Ice-Radar Measurement, and Modelling

    DEFF Research Database (Denmark)

    Ahlstrøm, Andreas P.; Bøggild, C.E.; Stenseng, L.;

    2002-01-01

    -track interferometric synthetic aperture radar (SAR) and a bedrock topography derived from an airborne 60 MHz ice-penetrating radar. The extent of the delineation was calculated from a water-pressure potential as a function of the ice-sheet surface and bedrock elevations and a hydraulic factor κ describing the relative...... measured basin run-off could thus be explained by small year-to-year variations of the κ-factor...

  5. Airborne bacteria in the atmosphere: Presence, purpose, and potential

    Science.gov (United States)

    Smets, Wenke; Moretti, Serena; Denys, Siegfried; Lebeer, Sarah

    2016-08-01

    Numerous recent studies have highlighted that the types of bacteria present in the atmosphere often show predictable patterns across space and time. These patterns can be driven by differences in bacterial sources of the atmosphere and a wide range of environmental factors, including UV intensity, precipitation events, and humidity. The abundance of certain bacterial taxa is of interest, not only for their ability to mediate a range of chemical and physical processes in the atmosphere, such as cloud formation and ice nucleation, but also for their implications -both beneficial and detrimental-for human health. Consequently, the widespread importance of airborne bacteria has stimulated the search for their applicability. Improving air quality, modelling the dispersal of airborne bacteria (e.g. pathogens) and biotechnological purposes are already being explored. Nevertheless, many technological challenges still need to be overcome to fully understand the roles of airborne bacteria in our health and global ecosystems.

  6. Major new sources of biological ice nuclei

    Science.gov (United States)

    Moffett, B. F.; Hill, T.; Henderson-Begg, S. K.

    2009-12-01

    Almost all research on biological ice nucleation has focussed on a limited number of bacteria. Here we characterise several major new sources of biogenic ice nuclei. These include mosses, hornworts, liverworts and cyanobacteria. Ice nucleation in the eukaryotic bryophytes appears to be ubiquitous. The temperature at which these organisms nucleate is that at which the difference in vapour pressure over ice and water is at or close to its maximum. At these temperatures (-8 to -18 degrees C) ice will grow at the expense of supercooled water. These organisms are dependent for their water on occult precipitation - fog, dew and cloudwater which by its nature is not collected in conventional rain gauges. Therefore we suggest that these organism produce ice nuclei as a water harvesting mechanism. Since the same mechanism would also drive the Bergeron-Findeisen process, and as moss is known to become airborne, these nuclei may have a role in the initiation of precipitation. The properties of these ice nuclei are very different from the well characterised bacterial nuclei. We will also present DNA sequence data showing that, although related, the proteins responsible are only very distantly related to the classical bacterial ice nuclei.

  7. Airborne Topographic Mapper Calibration Procedures and Accuracy Assessment

    Science.gov (United States)

    Martin, Chreston F.; Krabill, William B.; Manizade, Serdar S.; Russell, Rob L.; Sonntag, John G.; Swift, Robert N.; Yungel, James K.

    2012-01-01

    Description of NASA Airborn Topographic Mapper (ATM) lidar calibration procedures including analysis of the accuracy and consistancy of various ATM instrument parameters and the resulting influence on topographic elevation measurements. The ATM elevations measurements from a nominal operating altitude 500 to 750 m above the ice surface was found to be: Horizontal Accuracy 74 cm, Horizontal Precision 14 cm, Vertical Accuracy 6.6 cm, Vertical Precision 3 cm.

  8. Utilizing The Synergy of Airborne Backscatter Lidar and In-Situ Measurements for Evaluating CALIPSO

    Directory of Open Access Journals (Sweden)

    Tsekeri Alexandra

    2016-01-01

    Full Text Available Airborne campaigns dedicated to satellite validation are crucial for the effective global aerosol monitoring. CALIPSO is currently the only active remote sensing satellite mission, acquiring the vertical profiles of the aerosol backscatter and extinction coefficients. Here we present a method for CALIPSO evaluation from combining lidar and in-situ airborne measurements. The limitations of the method have to do mainly with the in-situ instrumentation capabilities and the hydration modelling. We also discuss the future implementation of our method in the ICE-D campaign (Cape Verde, August 2015.

  9. Utilizing The Synergy of Airborne Backscatter Lidar and In-Situ Measurements for Evaluating CALIPSO

    Science.gov (United States)

    Tsekeri, Alexandra; Amiridis, Vassilis; Marenco, Franco; Marinou, Eleni; Rosenberg, Phil; Solomos, Stavros; Trembath, Jamie; Allan, James; Bacak, Asan; Nenes, Athanasios

    2016-06-01

    Airborne campaigns dedicated to satellite validation are crucial for the effective global aerosol monitoring. CALIPSO is currently the only active remote sensing satellite mission, acquiring the vertical profiles of the aerosol backscatter and extinction coefficients. Here we present a method for CALIPSO evaluation from combining lidar and in-situ airborne measurements. The limitations of the method have to do mainly with the in-situ instrumentation capabilities and the hydration modelling. We also discuss the future implementation of our method in the ICE-D campaign (Cape Verde, August 2015).

  10. Microwaves in Airborne Surveillance

    Directory of Open Access Journals (Sweden)

    S. Christopher

    2013-03-01

    Full Text Available The use of microwave spectrum is widespread due to its convenience. Therefore, enormous amount of information is available in the free space channel. Obviously, mining this channel for surveillance is quite common. Airborne surveillance offers significant advantages in military operations. This paper talks of the usage of microwaves in airborne surveillance systems, in general, and in the Indian airborne early warning and control (AEW&C System, in particular. It brings out the multiple sub-systems onboard the aircraft comprising the AEW&C system and their spectral coverage. Co-location of several systems has its own problems and resolving them in terms of geometric location, frequency band and time of operation are covered. AEW&C, being an airborne system, has several other requirements  including minimal weight, volume and power considerations, lightning protection, streamlining, structural integrity, thermal management, vibration tolerance, corrosion prevention, erosion resistance, static charge discharge capability, bird strike resilience, etc. The methods adopted to cater to all these requirements in the microwave systems that are used in the AEW&C system are discussed. Paper ultimately speaks of the microwave systems that are designed and developed for the Indian AEW&C system to surmount these unusual constraints.Defence Science Journal, 2013, 63(2, pp.138-144, DOI:http://dx.doi.org/10.14429/dsj.63.4255

  11. International Symposium on Airborne Geophysics

    Science.gov (United States)

    Mogi, Toru; Ito, Hisatoshi; Kaieda, Hideshi; Kusunoki, Kenichiro; Saltus, Richard W.; Fitterman, David V.; Okuma, Shigeo; Nakatsuka, Tadashi

    2006-05-01

    Airborne geophysics can be defined as the measurement of Earth properties from sensors in the sky. The airborne measurement platform is usually a traditional fixed-wing airplane or helicopter, but could also include lighter-than-air craft, unmanned drones, or other specialty craft. The earliest history of airborne geophysics includes kite and hot-air balloon experiments. However, modern airborne geophysics dates from the mid-1940s when military submarine-hunting magnetometers were first used to map variations in the Earth's magnetic field. The current gamut of airborne geophysical techniques spans a broad range, including potential fields (both gravity and magnetics), electromagnetics (EM), radiometrics, spectral imaging, and thermal imaging.

  12. Elevation Change Measurements of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Forsberg, R.; Keller, K.; Nielsen, C. S.; Gundestrup, N.; Tscherning, C. C.; Madsen, Søren Nørvang; Dall, Jørgen

    2000-01-01

    Repeated GPS measurements have been performed at the centre of the Greenland Ice Sheet since 1992. Results have shown that the ice sheet is essentially stable at this location, with GPS-determined strain and elevation change rates in good accordance with yearly snow accumulation and glaciological....... The paper outlines the surveys carried out, some preliminary results, and intercomparisons of GPS, laser altimetry and SAR techniques.......Repeated GPS measurements have been performed at the centre of the Greenland Ice Sheet since 1992. Results have shown that the ice sheet is essentially stable at this location, with GPS-determined strain and elevation change rates in good accordance with yearly snow accumulation and glaciological...... flow models. In a local ice cap in East Greenland (Geikie Plateau) repeated GPS, airborne laser altimetry and SAR interferometry have been used to study ice movements in the more climatically variable coastal zone, where meter-level annual elevation changes are possible due to the high precipitation...

  13. A spongy icing model for aircraft icing

    Directory of Open Access Journals (Sweden)

    Li Xin

    2014-02-01

    Full Text Available Researches have indicated that impinging droplets can be entrapped as liquid in the ice matrix and the temperature of accreting ice surface is below the freezing point. When liquid entrapment by ice matrix happens, this kind of ice is called spongy ice. A new spongy icing model for the ice accretion problem on airfoil or aircraft has been developed to account for entrapped liquid within accreted ice and to improve the determination of the surface temperature when entering clouds with supercooled droplets. Different with conventional icing model, this model identifies icing conditions in four regimes: rime, spongy without water film, spongy with water film and glaze. By using the Eulerian method based on two-phase flow theory, the impinging droplet flow was investigated numerically. The accuracy of the Eulerian method for computing the water collection efficiency was assessed, and icing shapes and surface temperature distributions predicted with this spongy icing model agree with experimental results well.

  14. A spongy icing model for aircraft icing

    Institute of Scientific and Technical Information of China (English)

    Li Xin; Bai Junqiang; Hua Jun; Wang Kun; Zhang Yang

    2014-01-01

    Researches have indicated that impinging droplets can be entrapped as liquid in the ice matrix and the temperature of accreting ice surface is below the freezing point. When liquid entrapment by ice matrix happens, this kind of ice is called spongy ice. A new spongy icing model for the ice accretion problem on airfoil or aircraft has been developed to account for entrapped liquid within accreted ice and to improve the determination of the surface temperature when enter-ing clouds with supercooled droplets. Different with conventional icing model, this model identifies icing conditions in four regimes:rime, spongy without water film, spongy with water film and glaze. By using the Eulerian method based on two-phase flow theory, the impinging droplet flow was investigated numerically. The accuracy of the Eulerian method for computing the water collection efficiency was assessed, and icing shapes and surface temperature distributions predicted with this spongy icing model agree with experimental results well.

  15. Comparison of sea-ice freeboard and thickness distributions from aircraft data and cryosat-2

    DEFF Research Database (Denmark)

    accurate range measurements. During the CryoSat Validation Experiment (CryoVEx) 2011 in the Lincoln Sea, Cryosat-2 underpasses were accomplished with two aircraft, which carried an airborne laser-scanner, a radar altimeter and an electromagnetic induction device for direct sea-ice thickness retrieval. Both...... aircraft flew in close formation at the same time of a CryoSat-2 overpass. This is a study about the comparison of the sea-ice freeboard and thickness distribution of airborne validation and CryoSat-2 measurements within the multi-year sea-ice region of the Lincoln Sea in spring, with respect to the...

  16. CryoSat2 Pre-Launch Validation Measurements on Arctic Sea Ice

    DEFF Research Database (Denmark)

    Nicolaus, Marcel; Hendricks, Stefan; Stenseng, Lars;

    2010-01-01

    sea ice and its snow cover will contribute to increasing our understanding of atmosphere-ice-ocean interaction and improve our ability to quantify observed changes. Our validation measurements show that the penetration depth of the radar signal strongly depends on snow cover characteristics...... (seasonality and underlying ice type) and is often not the snow-ice interface, as commonly assumed. Validation transects, using airborne electromagnetic ice-thickness measurements, are shown to be a powerful tool for regional-scale validation experiments during different seasons....

  17. Airborne forest fire research

    Science.gov (United States)

    Mattingly, G. S.

    1974-01-01

    The research relating to airborne fire fighting systems is reviewed to provide NASA/Langley Research Center with current information on the use of aircraft in forest fire operations, and to identify research requirements for future operations. A literature survey, interview of forest fire service personnel, analysis and synthesis of data from research reports and independent conclusions, and recommendations for future NASA-LRC programs are included.

  18. Particulate airborne impurities

    OpenAIRE

    Wilkinson, Kai

    2013-01-01

    The cumulative effects of air pollutants are of principal concern in research on environmental protection in Sweden. Post-industrial society has imposed many limits on emitted air pollutants, yet the number of reports on the negative effects from them is increasing, largely due to human activity in the form of industrial emissions and increased traffic flows. Rising concerns over the health effects from airborne particulate matter (PM) stem from in vitro, in vivo, and cohort studies revealing...

  19. GRYPHON : Airborne lifestyle concept

    OpenAIRE

    Evers, Erik

    2014-01-01

    The result of the project, the Gryphon, is a helicopter concept designed for private use. The intention of the project has been to investigate how safe, personal airborne mobility could be an attractive transportation alternative in the future. As an aspirational concept the goal has been to inspire and show an exciting way to enjoy a modern, sustainable lifestyle close to nature without the need for conventional infrastructure.

  20. Airborne wireless communication systems, airborne communication methods, and communication methods

    Science.gov (United States)

    Deaton, Juan D.; Schmitt, Michael J.; Jones, Warren F.

    2011-12-13

    An airborne wireless communication system includes circuitry configured to access information describing a configuration of a terrestrial wireless communication base station that has become disabled. The terrestrial base station is configured to implement wireless communication between wireless devices located within a geographical area and a network when the terrestrial base station is not disabled. The circuitry is further configured, based on the information, to configure the airborne station to have the configuration of the terrestrial base station. An airborne communication method includes answering a 911 call from a terrestrial cellular wireless phone using an airborne wireless communication system.

  1. Ice cloud processing of ultra-viscous/glassy aerosol particles leads to enhanced ice nucleation ability

    Directory of Open Access Journals (Sweden)

    B. J. Murray

    2012-04-01

    Full Text Available The ice nucleation potential of airborne glassy aqueous aerosol particles has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 247 and 216 K. Four different solutes were used as proxies for oxygenated organic matter found in the atmosphere: raffinose, 4-hydroxy-3-methoxy-DL-mandelic acid (HMMA, levoglucosan, and a multi-component mixture of raffinose with five dicarboxylic acids and ammonium sulphate. Similar to previous experiments with citric acid aerosols, all particles were found to nucleate ice heterogeneously before reaching the homogeneous freezing threshold provided that the freezing cycles were started well below the respective glass transition temperatures of the compounds; this is discussed in detail in a separate article. In this contribution, we identify a further mechanism by which glassy aerosols can promote ice nucleation below the homogeneous freezing limit. If the glassy aerosol particles are probed in freezing cycles started only a few degrees below their respective glass transition temperatures, they enter the liquid regime of the state diagram upon increasing relative humidity (moisture-induced glass-to-liquid transition before being able to act as heterogeneous ice nuclei. Ice formation then only occurs by homogeneous freezing at elevated supersaturation levels. When ice forms the remaining solution freeze concentrates and re-vitrifies. If these ice cloud processed glassy aerosol particles are then probed in a second freezing cycle at the same temperature, they catalyse ice formation at a supersaturation threshold between 5 and 30% with respect to ice. By analogy with the enhanced ice nucleation ability of insoluble ice nuclei like mineral dusts after they nucleate ice once, we refer to this phenomenon as pre-activation. We propose a number of possible explanations for why glassy aerosols that have re-vitrified in

  2. Greenland ice sheet mass balance: a review

    DEFF Research Database (Denmark)

    Khan, Shfaqat Abbas; Aschwanden, Andy; Bjørk, Anders A.;

    2015-01-01

    Over the past quarter of a century the Arctic has warmed more than any other region on Earth, causing a profound impact on the Greenland ice sheet (GrIS) and its contribution to the rise in global sea level. The loss of ice can be partitioned into processes related to surface mass balance and to...... and melt-induced mass losses exhibit rapid short-term fluctuations that, when extrapolated into the future, could yield erroneous long-term trends. In this paper we review the GrIS mass loss over more than a century by combining satellite altimetry, airborne altimetry, interferometry, aerial...... photographs and gravimetry data sets together with modelling studies. We revisit the mass loss of different sectors and show that they manifest quite different sensitivities to atmospheric and oceanic forcing. In addition, we discuss recent progress in constructing coupled ice-ocean-atmosphere models required...

  3. Airborne radioactive contamination monitoring

    International Nuclear Information System (INIS)

    Current technologies for the detection of airborne radioactive contamination do not provide real-time capability. Most of these techniques are based on the capture of particulate matter in air onto filters which are then processed in the laboratory; thus, the turnaround time for detection of contamination can be many days. To address this shortcoming, an effort is underway to adapt LRAD (Long-Range-Alpha-Detection) technology for real-time monitoring of airborne releases of alpa-emitting radionuclides. Alpha decays in air create ionization that can be subsequently collected on electrodes, producing a current that is proportional to the amount of radioactive material present. Using external fans on a pipe containing LRAD detectors, controlled samples of ambient air can be continuously tested for the presence of radioactive contamination. Current prototypes include a two-chamber model. Sampled air is drawn through a particulate filter and then through the first chamber, which uses an electrostatic filter at its entrance to remove ambient ionization. At its exit, ionization that occurred due to the presence of radon is collected and recorded. The air then passes through a length of pipe to allow some decay of short-lived radon species. A second chamber identical to the first monitors the remaining activity. Further development is necessary on air samples without the use of particulate filtering, both to distinguish ionization that can pass through the initial electrostatic filter on otherwise inert particulate matter from that produced through the decay of radioactive material and to separate both of these from the radon contribution. The end product could provide a sensitive, cost-effective, real-time method of determining the presence of airborne radioactive contamination

  4. Airborne field strength monitoring

    Directory of Open Access Journals (Sweden)

    J. Bredemeyer

    2007-06-01

    Full Text Available In civil and military aviation, ground based navigation aids (NAVAIDS are still crucial for flight guidance even though the acceptance of satellite based systems (GNSS increases. Part of the calibration process for NAVAIDS (ILS, DME, VOR is to perform a flight inspection according to specified methods as stated in a document (DOC8071, 2000 by the International Civil Aviation Organization (ICAO. One major task is to determine the coverage, or, in other words, the true signal-in-space field strength of a ground transmitter. This has always been a challenge to flight inspection up to now, since, especially in the L-band (DME, 1GHz, the antenna installed performance was known with an uncertainty of 10 dB or even more. In order to meet ICAO's required accuracy of ±3 dB it is necessary to have a precise 3-D antenna factor of the receiving antenna operating on the airborne platform including all losses and impedance mismatching. Introducing precise, effective antenna factors to flight inspection to achieve the required accuracy is new and not published in relevant papers yet. The authors try to establish a new balanced procedure between simulation and validation by airborne and ground measurements. This involves the interpretation of measured scattering parameters gained both on the ground and airborne in comparison with numerical results obtained by the multilevel fast multipole algorithm (MLFMA accelerated method of moments (MoM using a complex geometric model of the aircraft. First results will be presented in this paper.

  5. Seasonal evolution of melt ponds on Arctic sea ice

    Science.gov (United States)

    Webster, Melinda A.; Rigor, Ignatius G.; Perovich, Donald K.; Richter-Menge, Jacqueline A.; Polashenski, Christopher M.; Light, Bonnie

    2015-09-01

    The seasonal evolution of melt ponds has been well documented on multiyear and landfast first-year sea ice, but is critically lacking on drifting, first-year sea ice, which is becoming increasingly prevalent in the Arctic. Using 1 m resolution panchromatic satellite imagery paired with airborne and in situ data, we evaluated melt pond evolution for an entire melt season on drifting first-year and multiyear sea ice near the 2011 Applied Physics Laboratory Ice Station (APLIS) site in the Beaufort and Chukchi seas. A new algorithm was developed to classify the imagery into sea ice, thin ice, melt pond, and open water classes on two contrasting ice types: first-year and multiyear sea ice. Surprisingly, melt ponds formed ˜3 weeks earlier on multiyear ice. Both ice types had comparable mean snow depths, but multiyear ice had 0-5 cm deep snow covering ˜37% of its surveyed area, which may have facilitated earlier melt due to its low surface albedo compared to thicker snow. Maximum pond fractions were 53 ± 3% and 38 ± 3% on first-year and multiyear ice, respectively. APLIS pond fractions were compared with those from the Surface Heat Budget of the Arctic Ocean (SHEBA) field campaign. APLIS exhibited earlier melt and double the maximum pond fraction, which was in part due to the greater presence of thin snow and first-year ice at APLIS. These results reveal considerable differences in pond formation between ice types, and underscore the importance of snow depth distributions in the timing and progression of melt pond formation.

  6. Greenland Ice Surface Elevations from NASA ATM Airborne Lidar

    Data.gov (United States)

    National Aeronautics and Space Administration — Scanning laser altimeters were flown over the Greenland icesheet during late spring or early summer from 1993 to 1999. Flights spanned the entire icesheet, sampling...

  7. Compositae dermatitis from airborne parthenolide

    DEFF Research Database (Denmark)

    Paulsen, E; Christensen, Lars Porskjær; Andersen, Klaus Ejner

    2007-01-01

    BACKGROUND: Compositae dermatitis confined to exposed skin has often been considered on clinical grounds to be airborne. Although anecdotal clinical and plant chemical reports suggest true airborne allergy, no proof has been procured. Feverfew (Tanacetum parthenium) is a European Compositae plant...

  8. Spatial pattern of mass loss processes across the Greenland Ice Sheet from the Little Ice Age to 2010

    DEFF Research Database (Denmark)

    Kjaer, K. H.; Korsgaard, N. J.; Kjeldsen, K. K.;

    The Greenland Ice Sheet loses mass through surface meltwater runoff and discharge from marine terminating outlet glaciers. The spatial variability and magnitude of these processes have been studied and described in detail for the past decades. Here, we combine the mass loss between the LIA to 2010...... with a SMB model extending back to ~1900 in order to investigate the spatial distribution of mass loss processes. We use high quality aerial stereo photogrammetric imagery recorded between 1978 and 1987 to map morphological features such as trim lines and end moraines marking the maximum ice extent of...... the LIA, which enables us to obtain vertical point-based differences associated with former ice extent. These point measurements are combined with contemporary ice surface differences derived using NASA's Airborne Topographic Mapper (ATM) from 2003-2010, NASA's Ice, Cloud, and land Elevation Satellite...

  9. A study of Arctic sea ice freeboard heights, gravity anomalies and dynamic topography from ICESat measurementes

    DEFF Research Database (Denmark)

    Skourup, Henriette

    used to estimate the sea ice freeboard, and shows good qualitative correlation to QuikSCAT scatterometer data. As the method depends on the presence of open water, the method is underestimating the sea ice freeboard heights, when compared to coincident high resolution airborne lidar measurements in...... Arctic is a combination of sea ice and open water. The sea surface height is found by a "lowest-level" filtering procedure, originally developed for airborne lidar measurements, which assumes that the lowest levels measured represent the open water in the ice pack. The sea surface obtained this way is...... are investigated. The ICESat gravity grid shows all the major tectonic features of the Arctic Ocean at high resolution. The results show that the laser altimetry data provides excellent gravity results comparable to open ocean altimetry even over the most heavy ice conditions. Subtracting a geoid...

  10. Elevation change and remote-sensing mass-balance methods on the Greenland ice sheet

    DEFF Research Database (Denmark)

    Ahlstrøm, Andreas P.; Reeh, Niels; Christensen, Erik Lintz;

    -density coverage. During campaigns in 2000, 2003 and 2005, we have collected and processed ice-sheet surface elevation and ice-thickness data, acquired with a laser altimeter and a 60~MHz ice-penetrating radar. Both instruments were mounted on a small Twin-Otter aircraft which were positioned using three onboard...... differential GPS instruments and corrected for pitch, roll and crab using an Inertial Navigation System. Knowledge of elevation change and ice thickness alone does not provide mass balance, but when combined with the surface velocity field obtained from satellite repeat-track interferometric synthetic aperture...... last decade. Large amounts of data have been collected from satellite and airborne platforms, yielding surface elevation changes and surface velocity fields. Here we present data from the Greenland Ice-Sheet margin acquired with a new small-scale airborne system, designed for regional high...

  11. Airborne transmission of lyssaviruses.

    Science.gov (United States)

    Johnson, N; Phillpotts, R; Fooks, A R

    2006-06-01

    In 2002, a Scottish bat conservationist developed a rabies-like disease and subsequently died. This was caused by infection with European bat lyssavirus 2 (EBLV-2), a virus closely related to Rabies virus (RABV). The source of this infection and the means of transmission have not yet been confirmed. In this study, the hypothesis that lyssaviruses, particularly RABV and the bat variant EBLV-2, might be transmitted via the airborne route was tested. Mice were challenged via direct introduction of lyssavirus into the nasal passages. Two hours after intranasal challenge with a mouse-adapted strain of RABV (Challenge Virus Standard), viral RNA was detectable in the tongue, lungs and stomach. All of the mice challenged by direct intranasal inoculation developed disease signs by 7 days post-infection. Two out of five mice challenged by direct intranasal inoculation of EBLV-2 developed disease between 16 and 19 days post-infection. In addition, a simple apparatus was evaluated in which mice could be exposed experimentally to infectious doses of lyssavirus from an aerosol. Using this approach, mice challenged with RABV, but not those challenged with EBLV-2, were highly susceptible to infection by inhalation. These data support the hypothesis that lyssaviruses, and RABV in particular, can be spread by airborne transmission in a dose-dependent manner. This could present a particular hazard to personnel exposed to aerosols of infectious RABV following accidental release in a laboratory environment. PMID:16687600

  12. Airborne monitoring system

    International Nuclear Information System (INIS)

    A complete system for tracking, mapping, and performing a composition analysis of a radioactive plume and contaminated area was developed at the NRCN. The system includes two major units : An airborne unit for monitoring and a ground station for analyzing. The airborne unit is mounted on a helicopter and includes file following. Four radiation sensor, two 2'' x 2'' Nal (Tl) sensors horizontally separated by lead shield for mapping and spectroscopy, and two Geiger Mueller (GM) tubes as part of the safety system. A multichannel analyzer card is used for spectroscopy. A navigation system, based on GPS and a barometric altitude meter, is used to locate the plume or ground data. The telemetry system, consisting of a transceiver and a modem, transfers all the data in real time to the ground station. An industrial PC (Field Works) runs a dedicated C++ Windows application to manage the acquired data. An independent microprocessor based backup system includes a recorder, display, and key pad. The ground station is based on an industrial PC, a telemetry system, a color printer and a modem to communicate with automatic meteorology stations in the relevant area. A special software controls the ground station. Measurement results are analyzed in the ground station to estimate plume parameters including motion, location, size, velocity, and perform risk assessment. (authors)

  13. Ice Observatory

    Science.gov (United States)

    blugerman, n.

    2015-10-01

    My project is to make ice observatories to perceive astral movements as well as light phenomena in the shape of cosmic rays and heat, for example.I find the idea of creating an observation point in space, that in time will change shape and eventually disappear, in consonance with the way we humans have been approaching the exploration of the universe since we started doing it. The transformation in the elements we use to understand big and small transformations, within the universe elements.

  14. Ice ages

    International Nuclear Information System (INIS)

    The Earth's climate undergoes great changes in cycles of 104 to 105 years. Deep sea sediments contain proof of these changes. The critical parameter is the O18/O16 isotope ratio. The astronomical theory is discussed of ice ages based on the changes in the shape of the Earth's orbit around the sun. Forecasts for the future are given - in the coming years the climate is expected to get warmer owing to increased CO2 levels in the atmosphere, and then a long cooler period is expected to follow. (M.D.)

  15. Ice warriors

    Energy Technology Data Exchange (ETDEWEB)

    Woof, M.

    2004-02-01

    Sitting under a glacier, SNSK's productive Svea North longwall mine is like no other. Situated on the Norwegian archipelago of Spitzbergen this is one of the Europe's two top producing coal mines and produced 2.7 mt of coal in 2003. A long tunnel has recently been built under the glacier with a conveyor system, to overcome problems of hauling coal along the ice road. The building of this tunnel is described in the article. The longwall mining operation and equipment used is described. 4 figs.

  16. ESA CryoVEx 2011:Airborne field campaign with ASIRAS radar, EM induction sounder and laser scanner

    OpenAIRE

    Skourup, Henriette; Barletta, Valentina Roberta; Einarsson, Indriði; Forsberg, René; Haas, C.; V. Helm; S. Hendricks; Hvidegaard, Sine Munk; Sørensen, Louise Sandberg

    2013-01-01

    After the successful launch of CryoSat‐2 in April 2010, the first direct Arctic validation campaign of the satellite was carried out in the period April 15 ‐ May 8, 2011. This report describes the airborne part of the CryoSat Validation Experiment (CryoVEx) 2011, and includes;1) Data collected with the ESA airborne Ku‐band interferometric radar (ASIRAS), coincident airborne laser scanner (ALS) and vertical photography to acquire data over sea‐ and land ice along CryoSat‐2 ground tracks. The a...

  17. Great Lakes Ice Charts

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Charts show ice extent and concentration three times weekly during the ice season, for all lakes except Ontario, from the 1973/74 ice season through the 2001/2002...

  18. Observations from the Programme for Monitoring of the Greenland Ice Sheet

    Science.gov (United States)

    Andersen, S. B.; Ahlstrom, A. P.; Andersen, M. L.; Box, J. E.; Citterio, M.; Colgan, W. T.; Fausto, R. S.; van As, D.; Forsberg, R.; Skourup, H.; Sandberg Sørensen, L.; Kristensen, S. S.; Dall, J.; Kusk, A.; Petersen, D.

    2014-12-01

    The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) is as an on-going effort initiated in 2007 to monitor changes in the mass budget of the Greenland Ice Sheet. The aim of the programme is to quantify the mass loss of the Greenland ice sheet and track changes in the extent of the glaciers, ice caps and ice sheet margin. Specifically, PROMICE aims to estimate the mass loss derived from three fundamentally different sources: Surface melt water runoff from the ice sheet margin Iceberg production Mass loss of individual glaciers and ice caps surrounding the ice sheet The first is observed by a network of automatic weather stations (AWS) on the ice sheet margin measuring ice ablation as well as meteorological parameters. The second is determined by establishing a so-called 'flux gate' along the entire ice sheet margin and keeping track of the ice passing through this gate. The flux gate is obtained from airborne surveys of ice sheet surface elevation and thickness. The volume of the ice passing through the gate is derived from maps of the surface velocity of the ice sheet, produced from satellite radar. The third is investigated through regular mapping of area and elevation of the approximately 20.000 individual glaciers and ice caps in Greenland. Mapping is carried out using recent satellite imagery as well as aerial ortho-photos. Within PROMICE data sets from these activities are collected. They include observations from the network of currently about 20 AWS on the margin of the Greenland ice sheet. Airborne surveys, yielding surface elevation and ice depth along the entire margin of the Greenland ice sheet carried out in 2007 and 2011. A map of all Greenland ice masses, based on the highest detail aero-photogrammetric maps produced from mid-80's aerial photographs. Real-time data from the PROMICE AWS network is shown at the web site www.promice.org and the data is freely available for download. Data from the airborne surveys and mapping activities are

  19. A marine biogenic source of atmospheric ice-nucleating particles

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, T. W.; Ladino, L. A.; Alpert, Peter A.; Breckels, M. N.; Brooks, I. M.; Browse, J.; Burrows, Susannah M.; Carslaw, K. S.; Huffman, J. A.; Judd, C.; Kilthau, W. P.; Mason, R. H.; McFiggans, Gordon; Miller, L. A.; Najera, J.; Polishchuk, E. A.; Rae, S.; Schiller, C. L.; Si, M.; Vergara Temprado, J.; Whale, Thomas; Wong, J P S; Wurl, O.; Yakobi-Hancock, J. D.; Abbatt, JPD; Aller, Josephine Y.; Bertram, Allan K.; Knopf, Daniel A.; Murray, Benjamin J.

    2015-09-09

    The formation of ice in clouds is facilitated by the presence of airborne ice nucleating particles1,2. Sea spray is one of the major global sources of atmospheric particles, but it is unclear to what extent these particles are capable of nucleating ice3–11. Here we show that material in the sea surface microlayer, which is enriched in surface active organic material representative of that found in sub-micron sea- spray aerosol12–21, nucleates ice under conditions that occur in mixed-phase clouds and high-altitude ice clouds. The ice active material is likely biogenic and is less than ~0.2 ?m in size. We also show that organic material (exudate) released by a common marine diatom nucleates ice when separated from cells and propose that organic material associated with phytoplankton cell exudates are a candidate for the observed ice nucleating ability of the microlayer samples. By combining our measurements with global model simulations of marine organic aerosol, we show that ice nucleating particles of marine origin are dominant in remote marine environments, such as the Southern Ocean, the North Pacific and the North Atlantic.

  20. Modeling for Airborne Contamination

    International Nuclear Information System (INIS)

    The objective of Modeling for Airborne Contamination (referred to from now on as ''this report'') is to provide a documented methodology, along with supporting information, for estimating the release, transport, and assessment of dose to workers from airborne radioactive contaminants within the Monitored Geologic Repository (MGR) subsurface during the pre-closure period. Specifically, this report provides engineers and scientists with methodologies for estimating how concentrations of contaminants might be distributed in the air and on the drift surfaces if released from waste packages inside the repository. This report also provides dose conversion factors for inhalation, air submersion, and ground exposure pathways used to derive doses to potentially exposed subsurface workers. The scope of this report is limited to radiological contaminants (particulate, volatile and gaseous) resulting from waste package leaks (if any) and surface contamination and their transport processes. Neutron activation of air, dust in the air and the rock walls of the drift during the preclosure time is not considered within the scope of this report. Any neutrons causing such activation are not themselves considered to be ''contaminants'' released from the waste package. This report: (1) Documents mathematical models and model parameters for evaluating airborne contaminant transport within the MGR subsurface; and (2) Provides tables of dose conversion factors for inhalation, air submersion, and ground exposure pathways for important radionuclides. The dose conversion factors for air submersion and ground exposure pathways are further limited to drift diameters of 7.62 m and 5.5 m, corresponding to the main and emplacement drifts, respectively. If the final repository design significantly deviates from these drift dimensions, the results in this report may require revision. The dose conversion factors are further derived by using concrete of sufficient thickness to simulate the drift

  1. Microwave emission from high Arctic Sea ice during freeze-up

    Science.gov (United States)

    Hollinger, J. P.; Troy, B. E.; Ramseier, R. O.; Asmus, K. W.; Hartman, M. F.; Luther, C. A.

    1984-09-01

    A cooperative sea ice remote sensing experiment was conducted in the eastern Beaufort Sea and Mould Bay area during the freeze-up period in October 1981. Airborne millimeter-wave imagery at 90, 140, and 220 GHz, and nadir microwave radiometric measurements at 19, 22, and 31 GHz, were made from a U. S. Naval Research Laboratory aircraft, while the Canadian Atmospheric Environment Service conducted an extensive concurrent surface measurement program. This study demonstrates for the first time the high-resolution capability of 90 GHz to investigate detailed ice morphology and to define ice types. The 140 and 220 GHz imagery is the first ever made of sea ice at these high frequencies. Emissivities are determined for young ice, second-year ice (SY), multiyear ice (MY), new ice, old shorefast ice, and open water. The young ice exhibits the emissivity typical of first-year (FY) ice types, i.e., near unity and independent of frequency. The emissivities of new ice and open water increase with frequency, and that of MY ice decreases with frequency. Those of SY ice and old shorefast ice, measured here for the first time, also decrease with frequency but are larger in value than the MY emissivity. Ice type discrimination is optimum at 90 GHz, i.e., the spread in microwave signature between FY ice and old ice (SY and MY) is greatest at 90 GHz. The MY emissivity is lower than that of open water at both 90 and 140 GHz. The measurements presented here provide a basis for development of algorithms to exploit the potential of the Mission Sensor Microwave/Imager (SSM/I) to be launched on a Defense Meteorological Satellite in 1985 and, in particular, the 85.5-GHz SSM/I channels for ice type, concentration, and edge determination.

  2. Forecasting Turbine Icing Events

    DEFF Research Database (Denmark)

    Davis, Neil; Hahmann, Andrea N.; Clausen, Niels-Erik;

    In this study, we present a method for forecasting icing events. The method is validated at two European wind farms in with known icing events. The icing model used was developed using current ice accretion methods, and newly developed ablation algorithms. The model is driven by inputs from the WRF...... mesoscale model, allowing for both climatological estimates of icing and short term icing forecasts. The current model was able to detect periods of icing reasonably well at the warmer site. However at the cold climate site, the model was not able to remove ice quickly enough leading to large ice...... accumulations, which have not been seen in observations. In addition to the model evaluation we were able to investigate the potential occurrence of ice induced power loss at two wind parks in Europe using observed data. We found that the potential loss during an icing event is large even when the turbine...

  3. Forecasting Turbine Icing Events

    DEFF Research Database (Denmark)

    Davis, Neil; Hahmann, Andrea N.; Clausen, Niels-Erik;

    2012-01-01

    In this study, we present a method for forecasting icing events. The method is validated at two European wind farms in with known icing events. The icing model used was developed using current ice accretion methods, and newly developed ablation algorithms. The model is driven by inputs from the WRF...... mesoscale model, allowing for both climatological estimates of icing and short term icing forecasts. The current model was able to detect periods of icing reasonably well at the warmer site. However at the cold climate site, the model was not able to remove ice quickly enough leading to large ice...... accumulations, which have not been seen in observations. In addition to the model evaluation we were able to investigate the potential occurrence of ice induced power loss at two wind parks in Europe using observed data. We found that the potential loss during an icing event is large even when the turbine...

  4. Airborne Cloud Computing Environment (ACCE)

    Science.gov (United States)

    Hardman, Sean; Freeborn, Dana; Crichton, Dan; Law, Emily; Kay-Im, Liz

    2011-01-01

    Airborne Cloud Computing Environment (ACCE) is JPL's internal investment to improve the return on airborne missions. Improve development performance of the data system. Improve return on the captured science data. The investment is to develop a common science data system capability for airborne instruments that encompasses the end-to-end lifecycle covering planning, provisioning of data system capabilities, and support for scientific analysis in order to improve the quality, cost effectiveness, and capabilities to enable new scientific discovery and research in earth observation.

  5. Multi-decadal dynamic thinning on the northwest margin of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Korsgaard, Niels Jákup; Kjær, Kurt H.; Khan, Shfaqat Abbas;

    Ice mass changes in the Greenland Ice Sheet have been estimated since the early 1990s from the GRACE (Gravity Recovery and Climate Experiment) satellite gravity mission, of ice sheet thinning from satellite radar altimetry and airborne laser altimetry, and of increased velocities of outlet glaciers...... from radar interferometric surveys. Prior to 2000 existing altimetry data provides comparatively limited spatial resolution and ice losses near ice sheet margins are most likely underestimated and existing data is unable to document the persisting change within outlet glaciers. Subsequent estimates...... of increasing dynamic induced ice loss. GRACE data show that this increased mass loss initiated in 2005 ceased in late 2009, thus, defining a dynamic thinning event as seen previous along the coast in southeast Greenland. Here, we present a multi-decadal perspective on ice mass change from northwestern...

  6. Multi-decadal dynamic thinning on the northwest margin of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Korsgaard, Niels Jákup; Kjær, Kurt H.; Khan, Shfaqat Abbas; Wahr, John M; Bamber, Jonathan L; Hurkmans, Ruud TWL; Timm, Lars H; Kjeldsen, Kristian Kjellerup; Bjørk, Anders Anker; Larsen, Nicolaj Krog

    Ice mass changes in the Greenland Ice Sheet have been estimated since the early 1990s from the GRACE (Gravity Recovery and Climate Experiment) satellite gravity mission, of ice sheet thinning from satellite radar altimetry and airborne laser altimetry, and of increased velocities of outlet glaciers...... from radar interferometric surveys. Prior to 2000 existing altimetry data provides comparatively limited spatial resolution and ice losses near ice sheet margins are most likely underestimated and existing data is unable to document the persisting change within outlet glaciers. Subsequent estimates for...... the entire ice sheet show increased mass loss from 137 Gt/yr in 2002–2003 to 286 Gt/yr in 2007–2009. Also evidence from the GRACE, GPS (Global Positioning System), and ICESat (Ice, Cloud and land Elevation Satellite) as well as surface mass balance data suggests there is an ongoing northward migration...

  7. Evaluation of Arctic Sea Ice Thickness Simulated by Arctic Ocean Model Intercomparison Project Models

    Science.gov (United States)

    Johnson, Mark; Proshuntinsky, Andrew; Aksenov, Yevgeny; Nguyen, An T.; Lindsay, Ron; Haas, Christian; Zhang, Jinlun; Diansky, Nikolay; Kwok, Ron; Maslowski, Wieslaw; Hakkinen, Sirpa; Ashik, Igor; De Cuevas, Beverly

    2012-01-01

    Six Arctic Ocean Model Intercomparison Project model simulations are compared with estimates of sea ice thickness derived from pan-Arctic satellite freeboard measurements (2004-2008); airborne electromagnetic measurements (2001-2009); ice draft data from moored instruments in Fram Strait, the Greenland Sea, and the Beaufort Sea (1992-2008) and from submarines (1975-2000); and drill hole data from the Arctic basin, Laptev, and East Siberian marginal seas (1982-1986) and coastal stations (1998-2009). Despite an assessment of six models that differ in numerical methods, resolution, domain, forcing, and boundary conditions, the models generally overestimate the thickness of measured ice thinner than approximately 2 mand underestimate the thickness of ice measured thicker than about approximately 2m. In the regions of flat immobile landfast ice (shallow Siberian Seas with depths less than 25-30 m), the models generally overestimate both the total observed sea ice thickness and rates of September and October ice growth from observations by more than 4 times and more than one standard deviation, respectively. The models do not reproduce conditions of fast ice formation and growth. Instead, the modeled fast ice is replaced with pack ice which drifts, generating ridges of increasing ice thickness, in addition to thermodynamic ice growth. Considering all observational data sets, the better correlations and smaller differences from observations are from the Estimating the Circulation and Climate of the Ocean, Phase II and Pan-Arctic Ice Ocean Modeling and Assimilation System models.

  8. Along-Track Products from NASA's Operation IceBridge Flight Line Data

    Science.gov (United States)

    Rogers, S. R.; Scambos, T. A.; Raup, B. H.; Haran, T. M.; Kaminski, M. L.

    2011-12-01

    A set of value-added data products (VAPs)is being developed at the National Snow and Ice Data Center (NSIDC) from the along-flight multi-sensor data sets gathered during the IceBridge flights of the DC-8 and P-3 NASA aircraft. These new products co-locate data from the IceBridge sensor suite and derive useful analysis parameters using one or more of the data streams. There are two along-track data sets being developed at NSIDC, one intended to facilitate ice sheet dynamics investigations, and one to characterize ice sheet surface and near-surface processes. Ice dynamics along-track products currently incorporate data from the Airborne Topographic Mapper (ATM), Sanders Gravimeter, Multi-Channel Coherent Depth Sounder (MCORDS) ice-penetrating radar system, and Digital Mapping System (DMS) camera. Derived products currently include regional slope (four hundred meter horizontal scale) and driving stress. Ice-dynamics along-track products currently under development focus on comparisons of the gravity and ice thickness data, as well as more detailed ice flow analysis. The along-track IceBridge data will be integrated with existing ice-sheet-wide data sets (for Greenland and Antarctica) such as DEMs, bed elevation and ice thickness, free-air anomaly from satellite data, and balance velocity. Ice sheet surface properties along-track products combine co-located data from the ATM, snow radar or accumulation radar, and DMS instrument, extracting roughness data, layer depth for radar reflections and images along with basic instrument measurement values. In addition to scientific parameters, various data vetting parameters determine how well aligned the sensors are for a given flight line point. A related product for sea ice properties, sea ice freeboard, and estimated sea ice thickness is being developed by NASA-GSFC personnel. The along-track VAPs are formatted into comma-separated values files for easy access by the science community. They are being integrated into the

  9. UAV applications for thermodynamic profiling: Emphasis on ice fog research

    Science.gov (United States)

    Gultepe, Ismail; Heymsfield, Andrew J.; Fernando, Harindra J. S.; Hoch, Sebastian W.; Ware, Randolph

    2016-04-01

    Ice fog occurs often over the Arctic, cold climatic, and mountainous regions for about 30% of time where temperature (T) can go down to -10°C or below. Ice Nucleation (IN) and cooling processes play an important role by the controlling the intensity of ice fog conditions that affect aviation application, transportation, and local climate. Ice fog can also occur at T above -10°C but close to 0°C it occurs due to freezing of supercooled droplets that include an IN. To better document ice fog conditions, observations from the ice fog events of the Indirect and Semi-Direct Aerosol effects on Climate (ISDAC) project, Barrow, Alaska, Fog Remote Sensing And Modeling (FRAM) project Yellowknife, Northwest Territories, and the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) project, Heber City, Utah, were analyzed.. Measurements difficulties of small ice fog particles at cold temperatures and low-level flying restrictions prevent observations from aircraft within the surface boundary layer. However, unmanned Aerial Vehicles (UAVs) can be operated safely to measure IN number concentration, Relative Humidity with respect to ice (RHi), T, horizontal wind speed (Uh) and direction, and ice crystal spectra less than about 500 micron. Thermodynamic profiling by a Radiometrics Profiling Microwave Radiometer (PMWR) and Vaisala CL51 ceilometer was used to describe ice fog conditions in the vertical and its time development. In this presentation, ice fog characteristics and its thermodynamic environment will be presented using both ground-based and airborne platforms such as a UAV with new sensors. Some examples of measurements from the UAV for future research, and challenges related to both ice fog measurements and visibility parameterization will also be presented.

  10. Organic matter matters for ice nuclei of agricultural soil origin

    Directory of Open Access Journals (Sweden)

    Y. Tobo

    2014-04-01

    Full Text Available Heterogeneous ice nucleation is a~crucial process for forming ice-containing clouds and subsequent ice-induced precipitation. The importance for ice nucleation of airborne desert soil dusts composed predominantly of minerals is relatively well understood. On the other hand, the potential influence of agricultural soil dusts on ice nucleation has been poorly recognized, despite recent estimates that they may account for up to ∼25% of the global atmospheric dust load. We have conducted freezing experiments with various dusts, including agricultural soil dusts derived from the largest dust source region in North America. Here we show evidence for the significant role of soil organic matter (SOM in particles acting as ice nuclei (IN under mixed-phase cloud conditions. We find that the ice nucleating ability of the agricultural soil dusts is similar to that of desert soil dusts, but is reduced to almost the same level as that of clay minerals (e.g., kaolinite after either H2O2 digestion or dry heating to 300 °C. In addition, based on chemical composition analysis, we show that organic-rich particles are more important than mineral particles for the ice nucleating ability of the agricultural soil dusts at temperatures warmer than about −36 °C. Finally, we suggest that such organic-rich particles of agricultural origin (namely, SOM particles may contribute significantly to the ubiquity of organic-rich IN in the global atmosphere.

  11. Automatic polar ice thickness estimation from SAR imagery

    Science.gov (United States)

    Rahnemoonfar, Maryam; Yari, Masoud; Fox, Geoffrey C.

    2016-05-01

    Global warming has caused serious damage to our environment in recent years. Accelerated loss of ice from Greenland and Antarctica has been observed in recent decades. The melting of polar ice sheets and mountain glaciers has a considerable influence on sea level rise and altering ocean currents, potentially leading to the flooding of the coastal regions and putting millions of people around the world at risk. Synthetic aperture radar (SAR) systems are able to provide relevant information about subsurface structure of polar ice sheets. Manual layer identification is prohibitively tedious and expensive and is not practical for regular, longterm ice-sheet monitoring. Automatic layer finding in noisy radar images is quite challenging due to huge amount of noise, limited resolution and variations in ice layers and bedrock. Here we propose an approach which automatically detects ice surface and bedrock boundaries using distance regularized level set evolution. In this approach the complex topology of ice and bedrock boundary layers can be detected simultaneously by evolving an initial curve in radar imagery. Using a distance regularized term, the regularity of the level set function is intrinsically maintained that solves the reinitialization issues arising from conventional level set approaches. The results are evaluated on a large dataset of airborne radar imagery collected during IceBridge mission over Antarctica and Greenland and show promising results in respect to hand-labeled ground truth.

  12. Airborne Particulate Threat Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Patrick Treado; Oksana Klueva; Jeffrey Beckstead

    2008-12-31

    Aerosol threat detection requires the ability to discern between threat agents and ambient background particulate matter (PM) encountered in the environment. To date, Raman imaging technology has been demonstrated as an effective strategy for the assessment of threat agents in the presence of specific, complex backgrounds. Expanding our understanding of the composition of ambient particulate matter background will improve the overall performance of Raman Chemical Imaging (RCI) detection strategies for the autonomous detection of airborne chemical and biological hazards. Improving RCI detection performance is strategic due to its potential to become a widely exploited detection approach by several U.S. government agencies. To improve the understanding of the ambient PM background with subsequent improvement in Raman threat detection capability, ChemImage undertook the Airborne Particulate Threat Assessment (APTA) Project in 2005-2008 through a collaborative effort with the National Energy Technology Laboratory (NETL), under cooperative agreement number DE-FC26-05NT42594. During Phase 1 of the program, a novel PM classification based on molecular composition was developed based on a comprehensive review of the scientific literature. In addition, testing protocols were developed for ambient PM characterization. A signature database was developed based on a variety of microanalytical techniques, including scanning electron microscopy, FT-IR microspectroscopy, optical microscopy, fluorescence and Raman chemical imaging techniques. An automated particle integrated collector and detector (APICD) prototype was developed for automated collection, deposition and detection of biothreat agents in background PM. During Phase 2 of the program, ChemImage continued to refine the understanding of ambient background composition. Additionally, ChemImage enhanced the APICD to provide improved autonomy, sensitivity and specificity. Deliverables included a Final Report detailing our

  13. Characterizing Subglacial Interfaces With Airborne Radar Sounding Techniques

    Science.gov (United States)

    Peters, M. E.; Blankenship, D. D.; Morse, D. L.

    2004-12-01

    Ice sheets are sensitive indicators of global change including sea-level rise. An ice sheet's subglacial interface is an important factor controlling its dynamic behavior. In particular, the grounding zones of ice streams and subglacial lakes are complex systems involving the interaction of the moving ice mass with underlying materials such as liquid water, saturated lubricating tills, and rough or frozen bedrock sticky spots. Imaging and characterizing the subglacial environment of ice sheets is fundamental to understanding these complex systems. Airborne radar sounding is a powerful and well-known technique for studying ice sheets and glaciers and their contiguous underlying environments. We present results from data acquired in 2001 over the ice stream C grounding zone in West Antarctica, as well as over a hypothesized subglacial lake near the South Pole. These data were acquired using a uniquely configured coherent airborne radar system. Our focus has been to characterize the subglacial interface through radar echo analysis based on reflection and scattering theory. The radar system uses a programmable signal source linked to a 10 kW transmitter and a dual-channel coherent down-conversion receiver. The radar operates in chirped pulse mode at 60 MHz with 15 MHz bandwidth. High and low-gain channels allow for recording a wide dynamic range of echoes simultaneously and without range-dependent gain control. Data acquisition includes integrations of 16 returned radar signals about every 15 cm along-track. Pulse compression and synthetic aperture radar (SAR) processing were components of data analysis. Subglacial echoes are influenced by the physical properties of the interface such as the composition and roughness of the materials at the interface. Other important factors include dielectric losses and volumetric scattering losses from propagation through the ice as well as transmission and refraction at the air-ice interface. Unfocussed SAR narrows the along

  14. Wave-Ice interaction

    Institute of Scientific and Technical Information of China (English)

    沈奚海莉

    2001-01-01

    The growth and movement of sea ice cover are influenced by the presence of wave field. Inturn, the wave field is influenced by the presence of ice cover. Their interaction is not fully understood.In this paper, we discuss some current understanding on wave attenuation when it propagates through frag-mented ice cover, ice drift due to the wave motion, and the growth characteristics of ice cover in wave field.

  15. Doped Colloidal Artificial Ice

    OpenAIRE

    Libal, A.; Reichhardt, C. J. Olson; Reichhardt, C.

    2015-01-01

    We examine square and kagome artificial spin ice for colloids confined in arrays of double-well traps. Unlike magnetic artificial spin ices, colloidal and vortex artificial spin ice realizations allow creation of doping sites through double occupation of individual traps. We find that doping square and kagome ice geometries produces opposite effects. For square ice, doping creates local excitations in the ground state configuration that produce a local melting effect as the temperature is rai...

  16. Overview of the Airborne Tropical TRopopause EX

    Science.gov (United States)

    Singh, Hanwant B.; Jensen, Eric J.; Pfister, Leonhard

    2014-01-01

    The NASA Airborne Tropical TRopopause EXperiment (ATTREX) is a series of airborne campaigns focused on understanding physical processes in the Tropical Tropopause Layer (TTL) and their role in atmospheric chemistry and climate. ATTREX is using the high-altitude, long-duration NASA Global Hawk Unmanned Air System to make in situ and remote-sensing measurements spanning the Pacific. A particular ATIREX emphasis is to better understand the dehydration of air as it passes through the cold tropical tropopause region. The ATTREX payload contains 12 in situ and remote sensing instruments that measure water vapor, clouds, multiple gaseous tracers (CO, CO2, CH4, NMHC, SF6, CFCs, N2O), reactive chemical compounds (O3, BrO, NO2), meteorological parameters, and radiative fluxes. ATTREX flight series have been conducted in the fall of 2011 from Armstrong Flight Research Center (AFRC) in California, in the winter of 2013 from AFRC, and in the winter/spring of 2014 from Guam. The first two f light series provided extensive sampling of the central and eastern Pacific, whereas the last flight series permitted sampling in the western Pacific. The sampling strategy has primarily involved repeated ascents and descents through the depth of the TTL (about 13-19 km). Over 100 TTL profiles were obtained on each flight series. The ATTREX dataset includes TTL water vapor measurements with unprecedented accuracy, ice crystal size distributions and habits. The cloud and water measurements provide unique information about TTL cloud formation, the persistence of supersaturation with respect to ice, and dehydration. The plethora of tracers measured on the Global Hawk flights are providing unique information about TTL transport pathways and time scales. The meteorological measurements are revealing dynamical phenomena controlling the TTL thermal structure, and the radiation measurements are providing information about heating rates associated with TTL clouds and water vapor. This presentation

  17. Resolving bathymetry from airborne gravity along Greenland fjords

    Science.gov (United States)

    Boghosian, Alexandra; Tinto, Kirsty; Cochran, James R.; Porter, David; Elieff, Stefan; Burton, Bethany L.; Bell, Robin E.

    2015-12-01

    Recent glacier mass loss in Greenland has been attributed to encroaching warming waters, but knowledge of fjord bathymetry is required to investigate this mechanism. The bathymetry in many Greenland fjords is unmapped and difficult to measure. From 2010 to 2012, National Aeronautics and Space Administration's Operation IceBridge collected a unique set of airborne gravity, magnetic, radar, and lidar data along the major outlet glaciers and fjords in Greenland. We applied a consistent technique using the IceBridge gravity data to create 90 bathymetric profiles along 54 Greenland fjords. We also used this technique to recover subice topography where warm or crevassed ice prevents the radar system from imaging the bed. Here we discuss our methodology, basic assumptions and error analysis. We present the new bathymetry data and discuss observations in six major regions of Greenland covered by IceBridge. The gravity models provide a total of 1950 line kilometers of bathymetry, 875 line kilometers of subice topography, and 12 new grounding line depths.

  18. Arctic sea ice freeboard from AltiKa and comparison with CryoSat-2 and Operation IceBridge

    Science.gov (United States)

    Armitage, Thomas W. K.; Ridout, Andy L.

    2015-08-01

    Satellite radar altimeters have improved our knowledge of Arctic sea ice thickness over the past decade. The main sources of uncertainty in sea ice thickness retrievals are associated with inadequate knowledge of the snow layer depth and the radar interaction with the snow pack. Here we adapt a method of deriving sea ice freeboard from CryoSat-2 to data from the AltiKa Ka band radar altimeter over the 2013-14 Arctic sea ice growth season. AltiKa measures basin-averaged freeboards between 4.4 cm and 6.9 cm larger than CryoSat-2 in October and March, respectively. Using airborne laser and radar measurements from spring 2013 and 2014, we estimate the effective scattering horizon for each sensor. While CryoSat-2 echoes penetrate to the ice surface over first-year ice and penetrate the majority (82 ± 3%) of the snow layer over multiyear ice, AltiKa echoes are scattered from roughly the midpoint (46 ± 5%) of the snow layer over both ice types.

  19. South African Airborne Operations

    Directory of Open Access Journals (Sweden)

    McGill Alexander

    2012-02-01

    Full Text Available Airborne operations entail the delivery of ground troops and their equipment by air to their area of operations. They can also include the subsequent support of these troops and their equipment by air. Historically, and by definition, this would encompass delivery by fixed-wing powered aircraft, by glider, by parachute or by helicopter. Almost any troops can be delivered by most of these means. However, the technical expertise and physical as well as psychological demands required by parachuting have resulted in specialist troops being selected and trained for this role. Some of the material advantages of using parachute troops, or paratroops, are: the enormous strategic reach provided by the long-distance transport aircraft used to convey them; the considerable payload which these aircraft are capable of carrying; the speed with which the parachute force can deploy; and the fact that no infrastructure such as airfields are required for their arrival. Perhaps most attractively to cash-strapped governments, the light equipment scales of parachute units’ makes them economical to establish and maintain. There are also less tangible advantages: the soldiers selected are invariably volunteers with a willingness or even desire to tackle challenges; their selection and training produces tough, confident and aggressive troops, psychologically geared to face superior odds and to function independently from other units; and their initiative and self-reliance combined with a high level of physical fitness makes them suitable for a number of different and demanding roles.

  20. A comparative analysis of the sea ice freeboard from CryoSat. CryoVEx and IceBridge

    DEFF Research Database (Denmark)

    Kildegaard Rose, Stine; Connor, Laurence N.; Farrell, Sinead L.; Forsberg, René; Newman, Thomas; Pedersen, Leif T.; Smith, Walter H. F.; Skourup, Henriette; Stenseng, Lars

    The CryoSat Validation Experiment (CryoVEx) has been conducted by ESA, to examine the uncertainties in the satellite measurement of e.g. sea ice thickness. In this study, we aim to estimate the sea ice freeboard from CryoSat-2, and compare it with the high-resolution Airborne Laser Scanner (ALS......) measurements collected along CryoSat-2 ground tracks from the CryoVEx 2012 campaign, together with NASA’s Operation IceBridge data. We will use the CryoSat SAR data level 1b (L1b) to discriminate the leads and from this, estimate the sea ice freeboard. Furthermore, we are looking at the CryoSat level 2 (L2...

  1. Pine Island Glacier ice shelf melt distributed at kilometre scales

    Directory of Open Access Journals (Sweden)

    P. Dutrieux

    2013-04-01

    Full Text Available By thinning and accelerating, West Antarctic ice streams are contributing about 10% of the observed global sea level rise. Much of this ice loss is from Pine Island Glacier, which has thinned since at least 1992, driven by changes in ocean heat transport beneath its ice shelf and retreat of the grounding line. Details of the processes driving this change, however, remain largely elusive, hampering our ability to predict the future behaviour of this and similar systems. Here, a Lagrangian methodology is developed to measure oceanic melting of such rapidly advecting ice. High-resolution satellite and airborne observations of ice surface velocity and elevation are used to quantify patterns of basal melt under the Pine Island Glacier ice shelf and the associated adjustments to ice flow. At the broad scale, melt rates of up to 100 m yr−1 occur near the grounding line, reducing to 30 m yr−1 just 20 km downstream. Between 2008 and 2011, basal melting was largely compensated by ice advection, allowing us to estimate an average loss of ice to the ocean of 87 km3 yr−1, in close agreement with 2009 oceanographically-constrained estimates. At smaller scales, a network of basal channels typically 500 m to 3 km wide is sculpted by concentrated melt, with kilometre-scale anomalies reaching 50% of the broad-scale basal melt. Basal melting enlarges the channels close to the grounding line, but farther downstream melting tends to diminish them. Kilometre-scale variations in melt are a key component of the complex ice-ocean interaction beneath the ice shelf, implying that greater understanding of their effect, or very high resolution models, are required to predict the sea-level contribution of the region.

  2. Development and improvement of airborne remote sensing radar platforms

    Science.gov (United States)

    Arnold, Emily J.

    With the recent record ice melt in the Arctic as well as the dramatic changes occurring in the Antarctic, the need and urgency to characterize ice sheets in these regions has become a research thrust of both the NSF and NASA. Airborne remote sensing is the most effective way to collect the necessary data on a large scale with fine resolution. Current models for determining the relationship between the world's great ice sheets and global sea-level are limited by the availability of data on bed topography, glacier volume, internal layers, and basal conditions. This need could be satisfied by equipping long range aircraft with an appropriately sensitive suite of sensors. The goal of this work is to enable two new airborne radar installations for use in cryospheric surveying, and improve these systems as well as future systems by addressing aircraft integration effects on antenna-array performance. An aerodynamic fairing is developed to enable a NASA DC-8 to support a 5-element array for CReSIS's MCoRDS radar, and several structures are also developed to enable a NASA P-3 to support a 15-element MCoRDS array, as well as three other radar antenna-arrays used for cryospheric surveying. Together, these aircraft have flown almost 200 missions and collected 550 TB of unique science data. In addition, a compensation method is developed to improve beamforming and clutter suppression on wing-mounted arrays by mitigating phase center errors due to wing-flexure. This compensation method is applied to the MVDR beamforming algorithm to improve clutter suppression by using element displacement information to apply appropriate phase shifts. The compensation demonstrated an average SINR increase of 5-10 dB. The hardware contributions of this work have substantially contributed to the state-of-the-art for polar remotes sensing, as evidenced by new data sets made available to the science community and widespread use and citation of the data. The investigations of aircraft integration

  3. The International SubMillimetre Airborne Radiometer (ISMAR) - First results from the STICCS and COSMIC campaigns

    Science.gov (United States)

    Mendrok, Jana; Eriksson, Patrick; Fox, Stuart; Brath, Manfred; Buehler, Stefan

    2016-04-01

    Multispectral millimeter- and submillimeter-wave observations bear the potential to measure properties of non-thin ice clouds like mass content and mean particle size. The next generation of European meteorological satellites, the MetOp-SG series, will carry the first satellite-borne submillimeter sounder, the Ice Cloud Imager (ICI). An airborne demonstrator, the International SubMillimetre Airborne Radiometer (ISMAR), is operated together with other remote sensing instruments and in-situ probes on the FAAM aircraft. Scientific measurements from two campaings in the North Atlantic region, STICCS and COSMIC, are available so far. Here we will introduce the ISMAR instrument, present the acquired measurements from the STICCS and COSMIC campaigns and show some first results. This will include estimation of instrument performance, first analysis of clear-sky and cloudy cases and discussion of selected features observed in the measurements (e.g. polarisation signatures).

  4. Mass loss of Greenland from GRACE, IceSat and CryoSat

    DEFF Research Database (Denmark)

    Forsberg, René; Sørensen, Louise Sandberg; Fredenslund Levinsen, Joanna;

    2013-01-01

    CryoSat data over the Greenland Ice Sheet are used to continue elevation height change data over the Greenland ice sheet, following a decade of detailed monitoring of ice sheet changes with GRACE and IceSat. The combination and validation of the different data for measuring changes is quantified...... by using available airborne lidar data from IceBridge and CryoVEx. There is a special challenge of using CryoSat as fill-in between EnviSat and Sentinel-3 for the longterm measurements of surface elevation changes, a key essential climate variable in the ESA Climate Change Initiative. Another challenge...... is the joint utilization of both altimetry and gravity field change measurements for consistent estimates of regional change patterns. In the paper we analyze GRACE, IceSat and CryoSat data since 2003, and present consistent estimates of overall mass changes with average values around -220 GT/year, showing...

  5. Multi-decadal dynamic thinning on the northwest margin of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Korsgaard, Niels Jákup; Kjær, Kurt H.; Khan, Shfaqat Abbas;

    Ice mass changes in the Greenland Ice Sheet have been estimated since the early 1990s from the GRACE (Gravity Recovery and Climate Experiment) satellite gravity mission, of ice sheet thinning from satellite radar altimetry and airborne laser altimetry, and of increased velocities of outlet glaciers...... northwestern Greenland using the stereoscopic coverage by aerial photographs recorded in 1985, which captures the beginning of the present warming in the late 1980s. The derived Digital Elevation Model (DEM) based on the aerial photographs are superior in coverage and spatial resolution to other early surface...... change records with a 25 m grid resolution and vertical uncertainty of 4.6m. Comparative DEMs were derived from laser altimetry data recorded in 2005 and 2010. Ice loss from the Greenland Ice Sheet (GrIS) can be partitioned into surface mass balance (SMB) processes (runoff and precipitation) and ice...

  6. Assessment of long-range kinematic GPS positioning errors by comparison with airborne laser altimetry and satellite altimetry

    DEFF Research Database (Denmark)

    Zhang, X.H.; Forsberg, René

    2007-01-01

    area of the Arctic Ocean north of Greenland, near-coincident in time and space with the ICESat satellite laser altimeter. Both of these flights were more than 800 km long. Comparisons between different GPS methods and four different software packages do not suggest a clear preference for any one, with...... Greenland. Part of the latter 30 cm error is likely due to errors in the airborne LIDAR measurement and calibration, as well as errors in the "ground truth" ocean surfaces due to drifting sea-ice. Nevertheless, the potential of the PPP method for generating 10 cm level kinematic height positioning over long......Long-range airborne laser altimetry and laser scanning (LIDAR) or airborne gravity surveys in, for example, polar or oceanic areas require airborne kinematic GPS baselines of many hundreds of kilometers in length. In such instances, with the complications of ionospheric biases, it can be a real...

  7. Temperate Ice Depth-Sounder: A proved concept for temperate ice sounding

    Science.gov (United States)

    Jara-Olivares, V. A.; Rodriguez-Morales, F.; Leuschen, C.; Ayyangar, H.; Gogineni, P. S.

    2010-12-01

    blocks: the digital section, the radio-frequency (RF) section, and the antenna. It is designed to weigh less than 2 kg, excluding the power supply. The digital section generates the transmit waveforms, as well as the timing and control signals. It also digitizes the output signal from the receiver and stores the data in binary format using a computer. The RF-section consists of a high-power transmitter and a low-noise receiver with variable gain (digitally controlled). In regards to the antenna, TIDSoR uses an electrically small 4-m dipole antenna and can operate in dual- or single-antenna configurations for surface-based and airborne platforms. In a single-antenna configuration, the radiating element can be time-shared between the transmitter and receiver by means of a transmit/receive switch. The radar antenna is currently being re-designed for installation on the tail boom of a P-3 Orion for airborne operation. In this configuration, TIDSoR could be supported by the aircraft power system. In this paper, we will discuss the status of the instrument and our most recent results from data collected in Greenland and Antarctica, showing successful sounding of ice up to 2-km thick. Finally, we will discuss the adaptation of this system for airborne operation.

  8. Ice Adhesion Testing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — Uses Evaluate and compare the relative performance of materials and surfcae coating based on their ability to aid in ice removal Test the effectiveness of de-icing...

  9. Forecast Icing Product

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Forecast Icing Product (FIP) is an automatically-generated index suitable for depicting areas of potentially hazardous airframe icing. The FIP algorithm uses...

  10. IOMASA SEA ICE DEVELOPMENTS

    DEFF Research Database (Denmark)

    Andersen, Søren; Tonboe, Rasmus; Heygster, Georg; Melsheimer, Christian; Pedersen, Leif Toudal; Schyberg, Harald; Tveter, Frank; Dahlgren, Per; Lundelius, Tomas; Gustafsson, Nils

    2005-01-01

    Sensitivity studies show that the radiometer ice concentration estimate can be biased by +10% by anomalous atmospheric emissivity and -20% by anomalous ice surface emissivity. The aim of the sea ice activities in EU 5th FP project IOMASA is to improve sea ice concentration estimates at higher...... spatial resolution. The project is in the process of facilitating an ice concentration observing system through validation and a better understanding of the microwave radiative transfer of the sea ice and overlying snow layers. By use of a novel modelling approach, it is possible to better detect and...... determine the circumstances that may lead to anomalous sea ice concentration retrieval as well as to assess and possibly minimize the sensitivities of the retrieval system. Through an active partnership with the SAF on Ocean and Sea Ice, a prototype system will be implemented as an experimental product...

  11. Ice rule correlations in stuffed spin ice

    International Nuclear Information System (INIS)

    Stuffed spin ice is a chemical variation of a spin ice material like Ho2Ti2O7 in which extra magnetic ions are inserted into the crystal structure. Previous studies have shown that the degree of stuffing has very little effect on the residual entropy in the system, which takes a value very close to the spin ice entropy. We argue, however, that the observation of this entropy does not imply long range coherence of the ice rules, that determine the local spin configurations. We have characterized deviations from the ice rules by means of a polarized neutron diffraction study of a single crystal of Ho2+δTi2−δO7−δ/2 with δ = 0.3. Our results demonstrate that the ice rules in stuffed spin ice are strictly valid only over a relatively short range, and that at longer range stuffed spin ice exhibits some characteristics of a ‘cluster glass’, with a tendency to more conventional ferromagnetic correlations. (paper)

  12. Pine Island glacier ice shelf melt distributed at kilometre scales

    Directory of Open Access Journals (Sweden)

    P. Dutrieux

    2013-09-01

    Full Text Available By thinning and accelerating, West Antarctic ice streams are contributing about 10% of the observed global sea level rise. Much of this ice loss is from Pine Island Glacier, which has thinned since at least 1992, driven by changes in ocean heat transport beneath its ice shelf and retreat of the grounding line. Details of the processes driving this change, however, remain largely elusive, hampering our ability to predict the future behaviour of this and similar systems. Here, a Lagrangian methodology is developed to measure oceanic melting of such rapidly advecting ice. High-resolution satellite and airborne observations of ice surface velocity and elevation are used to quantify patterns of basal melt under the Pine Island Glacier ice shelf and the associated adjustments to ice flow. At the broad scale, melt rates of up to 100 m yr−1 occur near the grounding line, reducing to 30 m yr−1 just 20 km downstream. Between 2008 and 2011, basal melting was largely compensated by ice advection, allowing us to estimate an average loss of ice to the ocean of 87 km3 yr−1, in close agreement with 2009 oceanographically constrained estimates. At smaller scales, a network of basal channels typically 500 m to 3 km wide is sculpted by concentrated melt, with kilometre-scale anomalies reaching 50% of the broad-scale basal melt. Basal melting enlarges the channels close to the grounding line, but farther downstream melting tends to diminish them. Kilometre-scale variations in melt are a key component of the complex ice–ocean interaction beneath the ice shelf, implying that greater understanding of their effect, or very high resolution models, are required to predict the sea-level contribution of the region.

  13. Remote sensing for the oil in ice Joint Industry Program 2007-2009

    Energy Technology Data Exchange (ETDEWEB)

    Dickins, D. [DF Dickins Associates LLC, La Jolla, CA (United States); Andersen, J.H.S [Norconsult, Horten (Norway); Brandvik, P.J.; Singsaas, I. [SINTEF Materials and Chemistry, Trondheim (Norway); Buvik, T. [Trondheim Dog Training Centre, Trondheim (Norway); Bradford, J. [Boise State Univ., Boise, ID (United States); Hall, R. [Kongsberg Satellite Services, Tromso (Norway); Babiker, M.; Kloster, K.; Sandven, S. [Nansen Environmental and Remote Sensing Center, Bergen (Norway)

    2009-07-01

    The challenge of detecting, mapping and tracking oil spills on ice were discussed with particular reference to the importance of spill detection and mapping for Arctic oil spills, where the oil can be hidden from view under snow and ice during periods of almost total darkness. The remote sensing project (P5) with in the Oil-in-Ice Joint Industry Program aimed to establish whether off-the-shelf technologies and sensors could detect oil in the presence of ice in particular scenarios. The specific goals were to evaluate the limitations and capabilities of currently operational remote sensors for spill surveillance in ice regimes encountered during the 2008 and 2009 field experiments and to draw conclusions regarding which sensors are most likely to be effective in a variety of oil and ice situations. The project focused on proven, commercially available systems and technologies. These included airborne sensors such as Ultra-violet/Infrared ( UV/IR ), forward looking infrared (FLIR) and synthetic aperture radar/side-looking airborne radars (SAR/SLAR); all weather satellite systems involving SAR; dogs for surface oil detection; and ground penetrating radar (GPR) for low level airborne oil on ice detection. The key finding was that flexible combinations of sensors operating from a variety of platforms are needed to cover a range of oil in ice scenarios. The most effective solution to detect oil patches during periods of darkness or fog was to deploy closely spaced global positioning system (GPS) tracking buoys to follow the ice and the oil. 34 refs., 1 tab., 17 figs.

  14. Empirical sea ice thickness retrieval during the freeze-up period from SMOS high incident angle observations

    Directory of Open Access Journals (Sweden)

    M. Huntemann

    2014-03-01

    Full Text Available Sea ice thickness information is important for sea ice modelling and ship operations. Here a method to detect the thickness of sea ice up to 50 cm during the freeze-up season based on high incidence angle observations of the Soil Moisture and Ocean Salinity (SMOS satellite working at 1.4 GHz is suggested. By comparison of thermodynamic ice growth data with SMOS brightness temperatures, a high correlation to intensity and an anticorrelation to the difference between vertically and horizontally polarised brightness temperatures at incidence angles between 40 and 50° are found and used to develop an empirical retrieval algorithm sensitive to thin sea ice up to 50 cm thickness. The algorithm shows high correlation with ice thickness data from airborne measurements and reasonable ice thickness patterns for the Arctic freeze-up period.

  15. Airborne gamma-ray spectrometry

    DEFF Research Database (Denmark)

    Hovgaard, Jens

    A new method - Noise Adjusted Singular Value Decomposition, NASVD - for processing gamma-ray spectra has been developed as part of a Ph.D. project. By using this technique one is able to decompose a large set of data - for example from airborne gamma-ray surveys - into a few spectral components. ...

  16. Synchronizing ice cores from the Renland and Agassiz ice caps to the Greenland Ice Core Chronology

    DEFF Research Database (Denmark)

    Vinther, Bo Møllesøe; Clausen, Henrik Brink; Fischer, D. A.; Koerner, R. M.; Johnsen, Sigfus Johann; Andersen, Katrine Krogh; Dahl-Jensen, Dorthe; Rasmussen, Sune Olander; Steffensen, Jørgen Peder; Svensson, Anders

    Four ice cores from the Agassiz ice cap in the Canadian high arctic and one ice core from the Renland ice cap in eastern Greenland have been synchronized to the Greenland Ice Core Chronology 2005 (GICC05) which is based on annual layer counts in the DYE-3, GRIP and NGRIP ice cores. Volcanic...

  17. Estimation of Sea Ice Thickness Distributions through the Combination of Snow Depth and Satellite Laser Altimetry Data

    Science.gov (United States)

    Kurtz, Nathan T.; Markus, Thorsten; Cavalieri, Donald J.; Sparling, Lynn C.; Krabill, William B.; Gasiewski, Albin J.; Sonntag, John G.

    2009-01-01

    Combinations of sea ice freeboard and snow depth measurements from satellite data have the potential to provide a means to derive global sea ice thickness values. However, large differences in spatial coverage and resolution between the measurements lead to uncertainties when combining the data. High resolution airborne laser altimeter retrievals of snow-ice freeboard and passive microwave retrievals of snow depth taken in March 2006 provide insight into the spatial variability of these quantities as well as optimal methods for combining high resolution satellite altimeter measurements with low resolution snow depth data. The aircraft measurements show a relationship between freeboard and snow depth for thin ice allowing the development of a method for estimating sea ice thickness from satellite laser altimetry data at their full spatial resolution. This method is used to estimate snow and ice thicknesses for the Arctic basin through the combination of freeboard data from ICESat, snow depth data over first-year ice from AMSR-E, and snow depth over multiyear ice from climatological data. Due to the non-linear dependence of heat flux on ice thickness, the impact on heat flux calculations when maintaining the full resolution of the ICESat data for ice thickness estimates is explored for typical winter conditions. Calculations of the basin-wide mean heat flux and ice growth rate using snow and ice thickness values at the 70 m spatial resolution of ICESat are found to be approximately one-third higher than those calculated from 25 km mean ice thickness values.

  18. The Search for a Habitable Europa: Radar, Water and an Active Ice Shell

    Science.gov (United States)

    Blankenship, D. D.; Schmidt, B. E.; Young, D. A.; Schroeder, D. M.; Greenbaum, J. S.

    2011-10-01

    Future Europa exploration will seek to characterize the distribution of shallow subsurface water as well as to understand the formation of surface features through dynamic ice-shell processes. Radar sounding will be a critical tool for detecting these features, and should be of primary interest to the astrobiology community for understanding how and where life might arise on Europa. To develop successful instrumentation and data interpretation techniques for exploring Europa, we must leverage analogous terrestrial environments and processes. Airborne ice penetrating radar is now a mature tool in terrestrial studies of Earth's ice sheets, and orbital examples have been successful at the Moon and Mars.

  19. Comparison of sea-ice freeboard distributions from aircraft data and cryosat-2

    DEFF Research Database (Denmark)

    Ricker, Robert; Hendricks, Stefan; Helm, Veit;

    2012-01-01

    highly accurate range measurements. During the CryoSat Validation Experiment (CryoVEx) 2011 in the Lincoln Sea Cryosat-2 underpasses were accomplished with two aircraft which carried an airborne laser scanner, a radar altimeter and an electromagnetic induction device for direct sea ice thickness...... retrieval. Both aircraft flew in close formation at the same time of a CryoSat-2 overpass. This is a study about the comparison of the sea-ice freeboard distribution of laser scanner and radar altimeter measurements with the CryoSat-2 product within the multi-year sea ice region of the Lincoln Sea in spring...

  20. ICE SLURRY APPLICATIONS.

    Science.gov (United States)

    Kauffeld, M; Wang, M J; Goldstein, V; Kasza, K E

    2010-12-01

    The role of secondary refrigerants is expected to grow as the focus on the reduction of greenhouse gas emissions increases. The effectiveness of secondary refrigerants can be improved when phase changing media are introduced in place of single phase media. Operating at temperatures below the freezing point of water, ice slurry facilitates several efficiency improvements such as reductions in pumping energy consumption as well as lowering the required temperature difference in heat exchangers due to the beneficial thermo-physical properties of ice slurry. Research has shown that ice slurry can be engineered to have ideal ice particle characteristics so that it can be easily stored in tanks without agglomeration and then be extractable for pumping at very high ice fraction without plugging. In addition ice slurry can be used in many direct contact food and medical protective cooling applications. This paper provides an overview of the latest developments in ice slurry technology. PMID:21528014

  1. Sea Ice Deformation State From Synthetic Aperture Radar Imagery - Part II: Effects of Spatial Resolution and Noise Level

    DEFF Research Database (Denmark)

    Dierking, Wolfgang; Dall, Jørgen

    2008-01-01

    C- and L-band airborne synthetic aperture radar (SAR) imagery acquired at like- and cross-polarization over sea ice under winter conditions is examined with the objective to study the discrimination between level ice and ice deformation features. High-resolution low-noise data were analysed in th...... ice. The retrieval of deformation parameters using simulated images that resemble ERS-2 SAR, Envisat ASAR and ALOS PALSAR data products is discussed. Basic differences between real and simulated ERS-2 SAR images are analyzed.......C- and L-band airborne synthetic aperture radar (SAR) imagery acquired at like- and cross-polarization over sea ice under winter conditions is examined with the objective to study the discrimination between level ice and ice deformation features. High-resolution low-noise data were analysed...... in the first paper. In this second paper, the main topics are the effects of spatial resolution and signal-to-noise ratio. Airborne, high-resolution SAR scenes are used to generate a sequence of images with increasingly coarser spatial resolution from 5 m to 25 m, keeping the number of looks constant...

  2. Autonomous Aerial Ice Observation for Ice Defense

    Directory of Open Access Journals (Sweden)

    Joakim Haugen

    2014-10-01

    Full Text Available One of the tasks in ice defense is to gather information about the surrounding ice environment using various sensor platforms. In this manuscript we identify two monitoring tasks known in literature, namely dynamic coverage and target tracking, and motivate how these tasks are relevant in ice defense using RPAS. An optimization-based path planning concept is outlined for solving these tasks. A path planner for the target tracking problem is elaborated in more detail and a hybrid experiment, which consists of both a real fixed-wing aircraft and simulated objects, is included to show the applicability of the proposed framework.

  3. A TEM analysis of nanoparticulates in a Polar ice core

    International Nuclear Information System (INIS)

    This paper explores the prospect for analyzing nanoparticulates in age-dated ice cores representing times in antiquity to establish a historical reference for atmospheric particulate regimes. Analytical transmission electron microscope (TEM) techniques were utilized to observe representative ice-melt water drops dried down on carbon/formvar or similar coated grids. A 10,000-year-old Greenland ice core was melted, and representative water drops were transferred to coated grids in a clean room environment. Essentially, all particulates observed were aggregates and either crystalline or complex mixtures of nanocrystals. Especially notable was the observation of carbon nanotubes and related fullerene-like nanocrystal forms. These observations are similar with some aspects of contemporary airborne particulates including carbon nanotubes and complex nanocrystal aggregates

  4. Programme for Monitoring of the Greenland Ice Sheet (PROMICE)

    Science.gov (United States)

    Ahlstrom, A. P.; Andersen, M. L.; Andersen, S. B.; Boncori, J. M.; Citterio, M.; Dall, J.; Fausto, R. S.; Forsberg, R.; Kristensen, S. S.; Petersen, D.; Skourup, H.; van As, D.

    2011-12-01

    The Greenland Ice Sheet is currently experiencing a dramatic mass loss, with a contribution to sea level rise that is causing concern globally. In order to increase our understanding of the processes leading to this mass loss and to better quantify the contribution to sea level rise, the Danish government initiated the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) in 2007. The aim of PROMICE is to quantify the mass loss from surface melting and iceberg calving through a combination of observation and modelling. Data on the surface climate and melting is collected from a comprehensive network of automatic weather stations (AWS) spanning all regions of the Greenland Ice Sheet margin. In-situ GPS instruments on the ice margin as well as on selected outlet glaciers provide velocity observations. The in-situ data will be merged with satellite-derived velocity maps over large parts of the Greenland Ice Sheet and repeated airborne surveys of elevation and ice thickness along the entire margin to obtain the annual ice flux towards the ocean. We present results from these comprehensive observation campaigns and demonstrate the use of our online database system for public access to near real-time AWS data. Additionally, we present an estimate of the total area covered by glaciers and ice caps surrounding the ice sheet that is not based on extrapolation from partial inventories. The area estimate is derived using topographic maps from GEUS covering the entirety of Greenland at scales of 1:100.000 or 1:250.000.

  5. Advances in marine ice profiling for oil and gas applications

    International Nuclear Information System (INIS)

    Developments in acoustic profiling technologies have allowed ever more accurate and information-rich extraction of data on the draft, undersurface topography and immediately adjacent water column environment of polar and other marine and freshwater ice covers. The purpose of these advances was to replace and improve upon other, often inconvenient, costly and/or otherwise unsatisfactory methodologies such as the use of upward looking sonar (ULS) sounders on submarines as well as deployments of airborne- sensors such as laser profilometers and electromagnetic induction instrumentation. ULS is a primary source of data for measurements of ice thickness. Self-contained units now have the data capacity and accuracy/resolution sufficient for unattended operation. Recent technological advances have now led to the next generation of ice profiling sonar (IPS), incorporating much expanded on-board data storage capacity and powerful onboard real-time firmware. This paper outlined the nature of the issues addressed in past oil and gas related ice profiling studies. The paper focused on identifying the key items of interest and the remaining uncertainties in the derived products. All of the data gathered in this regard was obtained with first generation profiling instrumentation of the type initially introduced by Melling and coworkers in 1995. The additional features of a recently introduced next generation IPS instrument were briefly described. The observed and potential benefits offered in oil and gas related applications were also presented. It was concluded that the next generation ice profilers sets the stage for research and development into the measurement of new ice parameters, the combination of information from ice profilers and all-weather radar satellite systems, and the possibility of remote access to the ice profiler data from multi-year moorings located well within the main Arctic Ocean ice pack. 11 refs., 10 figs

  6. Measurements of ice nuclei concentrations and compositions in the maritime tropics

    Science.gov (United States)

    McMeeking, G. R.; Danielczok, A.; Bingemer, H.; Klein, H.; Hill, T. C.; Franc, G. D.; Martinez, M.; Venero, I.; Mayol-Bracero, O. L.; Ardon-Dryer, K.; Levin, Z.; Anderson, J.; Twohy, C. H.; Toohey, D. W.; DeMott, P. J.

    2011-12-01

    Tropical maritime cumulus clouds represent an important component of the global water cycle, but the relative roles of primary and secondary ice production in these clouds are poorly understood. Heterogeneous ice nuclei (IN) are responsible for ice initiation in towering tropical cumulus clouds, so information regarding their abundance, distribution, source compositions and dependence on cloud temperature is crucial to understanding the ice production processes. Here we present recent measurements of ice nuclei (IN) concentrations measured from ground-based and airborne (NSF/NCAR C-130) platforms during the Ice in Clouds-Tropical experiment, which took place in July 2011 over the Caribbean Sea near St. Croix in the US Virgin Islands. IN measurement techniques included airborne ambient and cloud particle residual measurements using a continuous flow diffusion chamber and off-line analysis of samples collected from the aircraft and two ground sites located on the island of Puerto Rico. Off-line measurements of IN concentrations included analysis by the Frankfurt Ice Nuclei Deposition FreezinG Experiment (FRIDGE) system and drop freezing via two methods of particles collected from filter samples. The measurement period included some periods with a strong Saharan dust influence that resulted in higher IN concentrations compared to clean maritime conditions. First analysis of IN physical, chemical and biological composition, and investigation of relationships between IN concentrations and total aerosol concentrations, composition and size are also presented.

  7. Estimation of Arctic Sea Ice Freeboard and Thickness Using CryoSat-2

    Science.gov (United States)

    Lee, S.; Im, J.; Kim, J. W.; Kim, M.; Shin, M.

    2014-12-01

    . With the freeboard height calculated using the lead detection approach, sea ice thickness was finally estimated using the Archimedes' buoyancy principle. The estimated sea ice freeboard and thickness were validated using ESA airborne Ku-band interferometric radar and Airborne Electromagnetic (AEM) data.

  8. Land Ice: Greenland & Antarctic ice mass anomaly

    Data.gov (United States)

    National Aeronautics and Space Administration — Data from NASA's Grace satellites show that the land ice sheets in both Antarctica and Greenland are losing mass. The continent of Antarctica (left chart) has been...

  9. Surface undulations of Antarctic ice streams tightly controlled by bedrock topography

    Directory of Open Access Journals (Sweden)

    J. De Rydt

    2012-10-01

    Full Text Available Full Stokes models predict that fast-flowing ice streams transmit information about their bedrock topography most efficiently to the surface for basal undulations with length scales between 1 and 20 times the mean ice thickness. This typical behaviour is independent on the precise values of the flow law and sliding law exponents, and should be universally observable. However, no experimental evidence for this important theoretical prediction has been obtained so far, hence ignoring an important test for the physical validity of current-day ice flow models. In our work we use recently acquired airborne radar data for the Rutford Ice Stream and Evans Ice Stream, and we show that the surface response of fast-flowing ice is highly sensitive to bedrock irregularities with wavelengths of several ice thicknesses. The sensitivity depends on the slip ratio, i.e. the ratio between mean basal sliding velocity and mean deformational velocity. We find that higher values of the slip ratio generally lead to a more efficient transfer, whereas the transfer is significantly dampened for ice that attains most of its surface velocity by creep. Our findings underline the importance of bedrock topography for ice stream dynamics on spatial scales up to 20 times the mean ice thickness. Our results also suggest that local variations in the flow regime and surface topography at this spatial scale cannot be explained by variations in basal slipperiness.

  10. SMOS derived sea ice thickness: algorithm baseline, product specifications and initial verification

    Directory of Open Access Journals (Sweden)

    X. Tian-Kunze

    2013-12-01

    Full Text Available Following the launch of ESA's Soil Moisture and Ocean salinity (SMOS mission it has been shown that brightness temperatures at a low microwave frequency of 1.4 GHz (L-band are sensitive to sea ice properties. In a first demonstration study, sea ice thickness has been derived using a semi-empirical algorithm with constant tie-points. Here we introduce a novel iterative retrieval algorithm that is based on a sea ice thermodynamic model and a three-layer radiative transfer model, which explicitly takes variations of ice temperature and ice salinity into account. In addition, ice thickness variations within a SMOS footprint are considered through a statistical thickness distribution function derived from high-resolution ice thickness measurements from NASA's Operation IceBridge campaign. This new algorithm has been used for the continuous operational production of a SMOS based sea ice thickness data set from 2010 on. This data set is compared and validated with estimates from assimilation systems, remote sensing data, and airborne electromagnetic sounding data. The comparisons show that the new retrieval algorithm has a considerably better agreement with the validation data and delivers a more realistic Arctic-wide ice thickness distribution than the algorithm used in the previous study.

  11. Deep Radiostratigraphy of the East Antarctic Plateau: Connecting the Dome C and Vostok Ice Core Sites

    Science.gov (United States)

    Cavitte, Marie G. P.; Blankenship, Donald D.; Young, Duncan A.; Schroeder, Dustin M.; Parrenin, Frederic; Lemeur, Emmanuel; Macgregor, Joseph A.; Siegert, Martin J.

    2016-01-01

    Several airborne radar-sounding surveys are used to trace internal reflections around the European Project for Ice Coring in Antarctica Dome C and Vostok ice core sites. Thirteen reflections, spanning the last two glacial cycles, are traced within 200 km of Dome C, a promising region for million-year-old ice, using the University of Texas Institute for Geophysics High-Capacity Radar Sounder. This provides a dated stratigraphy to 2318 m depth at Dome C. Reflection age uncertainties are calculated from the radar range precision and signal-to-noise ratio of the internal reflections. The radar stratigraphy matches well with the Multichannel Coherent Radar Depth Sounder (MCoRDS) radar stratigraphy obtained independently. We show that radar sounding enables the extension of ice core ages through the ice sheet with an additional radar-related age uncertainty of approximately 1/3-1/2 that of the ice cores. Reflections are extended along the Byrd-Totten Glacier divide, using University of Texas/Technical University of Denmark and MCoRDS surveys. However, core-to-core connection is impeded by pervasive aeolian terranes, and Lake Vostok's influence on reflection geometry. Poor radar connection of the two ice cores is attributed to these effects and suboptimal survey design in affected areas. We demonstrate that, while ice sheet internal radar reflections are generally isochronal and can be mapped over large distances, careful survey planning is necessary to extend ice core chronologies to distant regions of the East Antarctic ice sheet.

  12. An Ultra Wide-Band Radar Altimeter for Ice Sheet Surface Elevation and Snow Cover Over Sea Ice Measurement

    Science.gov (United States)

    Patel, A. E.; Gogineni, P. S.; Leuschen, C.; Rodriguez-Morales, F.; Panzer, B.

    2010-12-01

    The Ice sheets of Greenland and Antarctica are losing mass at a rapid rate and there has been significant decrease in sea ice volume over the last few years. CryoSat-II with optimized radar altimeter for ice-sheet and sea ice surface elevation measurements is launched. We developed ultra wide-band FM-CW radar that operates over the frequency range from 13-17 GHz for airborne measurements. The radar is designed to provide high-resolution surface-elevation data and also map near surface layers in polar firn with high precision. It is designed to generate an ultra linear transmit chirp using a fast settling PLL with a reference signal from Direct Digital Synthesizer (DDS). The pulse length of the transmit chirp is 240-us and pulse repetition frequency is 2-KHz. The peak transmit power of the system is 100-mW, radiated using horn antennas. The radar was deployed in Greenland and Antarctica in 2009-10 as a part of Operation Ice Bridge campaign to collect data in conjunction with other instruments including Airborne Topographic Mapper (ATM) and Digital Mapping System Camera (DMS). The radar also collected data under the Cryosat-II path. This paper will provide an overview of the Ku-Band radar design along with results from the 2009-2010 field campaigns. The data collected over polar firn shows near surface internal layers down to a depth of about 15-m with a resolution of 15-cm. When flying over sea ice the radar provides snow cover thickness data to a depth of about 0.5-m. Even over highly crevassed areas, such as outlet glaciers, the radar is able to detect large surface elevation changes of a few tens of meters with high resolution.

  13. Measurement of pressure ridges in SAR images of sea ice - Preliminary results on scattering theory

    Science.gov (United States)

    Vesecky, J. F.; Smith, M. P.; Daida, J. M.; Samadani, R.; Camiso, J. C.

    1992-01-01

    Sea ice ridges and keels (hummocks and bummocks) are important in sea ice research for both scientific and practical reasons. A long-term objective is to make quantitative measurements of sea ice ridges using synthetic aperture radar (SAR) images. The preliminary results of a scattering model for sea ice ridge are reported. The approach is through the ridge height variance spectrum Psi(K), where K is the spatial wavenumber, and the two-scale scattering model. The height spectrum model is constructed to mimic height statistics observed with an airborne optical laser. The spectrum model is used to drive a two-scale scattering model. Model results for ridges observed at C- and X-band yield normalized radar cross sections that are 10 to 15 dB larger than the observed cross sections of multiyear ice over the range of angles of incidence from 10 to 70 deg.

  14. Airborne Ultrasonic Tactile Display BCI

    OpenAIRE

    Hamada, Katsuhiko; Mori, Hiromu; Shinoda, Hiroyuki; Rutkowski, Tomasz M.

    2015-01-01

    This chapter presents results of our project, which studied whether contactless and airborne ultrasonic tactile display (AUTD) stimuli delivered to a user's palms could serve as a platform for a brain computer interface (BCI) paradigm. We used six palm positions to evoke combined somatosensory brain responses to implement a novel contactless tactile BCI. This achievement was awarded the top prize in the Annual BCI Research Award 2014 competition. This chapter also presents a comparison with a...

  15. Naled ice growth

    Science.gov (United States)

    Schohl, G. A.; Ettema, R.

    1986-02-01

    Based on theoretical formulation and dimensional analysis, supported by the results of laboratory experiments, a theory and a detailed description of naled ice growth are presented. The theory, concepts, and data should be of interest to engineers concerned with the effects of naleds (also referred to as aufeis or icings) on engineering works. The growth of a two dimensional, or laterally confined (flume), naled is shown to depend primarily on seven, independent, dimensionless parameters. The early, two dimensional, phase of growth, a naled consists of a mixture of ice and water, or ice-water slush, forming on a frigid base. The influence of two of the three remaining parameters is not felt until after a transition time has passed. The continuing, cyclic process by which slush layers form and eventually freeze results in the ice laminations that are a feature of naled ice.

  16. Annual Greenland accumulation rates (2009-2012) from airborne snow radar

    Science.gov (United States)

    Koenig, Lora S.; Ivanoff, Alvaro; Alexander, Patrick M.; MacGregor, Joseph A.; Fettweis, Xavier; Panzer, Ben; Paden, John D.; Forster, Richard R.; Das, Indrani; McConnell, Joesph R.; Tedesco, Marco; Leuschen, Carl; Gogineni, Prasad

    2016-08-01

    Contemporary climate warming over the Arctic is accelerating mass loss from the Greenland Ice Sheet through increasing surface melt, emphasizing the need to closely monitor its surface mass balance in order to improve sea-level rise predictions. Snow accumulation is the largest component of the ice sheet's surface mass balance, but in situ observations thereof are inherently sparse and models are difficult to evaluate at large scales. Here, we quantify recent Greenland accumulation rates using ultra-wideband (2-6.5 GHz) airborne snow radar data collected as part of NASA's Operation IceBridge between 2009 and 2012. We use a semiautomated method to trace the observed radiostratigraphy and then derive annual net accumulation rates for 2009-2012. The uncertainty in these radar-derived accumulation rates is on average 14 %. A comparison of the radar-derived accumulation rates and contemporaneous ice cores shows that snow radar captures both the annual and long-term mean accumulation rate accurately. A comparison with outputs from a regional climate model (MAR) shows that this model matches radar-derived accumulation rates in the ice sheet interior but produces higher values over southeastern Greenland. Our results demonstrate that snow radar can efficiently and accurately map patterns of snow accumulation across an ice sheet and that it is valuable for evaluating the accuracy of surface mass balance models.

  17. NASA Student Airborne Research Program

    Science.gov (United States)

    Schaller, E. L.; Shetter, R. E.

    2012-12-01

    The NASA Student Airborne Research Program (SARP) is a unique summer internship program for advanced undergraduates and early graduate students majoring in the STEM disciplines. SARP participants acquire hands-on research experience in all aspects of an airborne research campaign, including flying onboard an major NASA resource used for studying Earth system processes. In summer 2012, thirty-two participants worked in four interdisciplinary teams to study surface, atmospheric, and oceanographic processes. Participants assisted in the operation of instruments onboard the NASA P-3B aircraft where they sampled and measured atmospheric gases and imaged land and water surfaces in multiple spectral bands. Along with airborne data collection, students participated in taking measurements at field sites. Mission faculty and research mentors helped to guide participants through instrument operation, sample analysis, and data reduction. Over the eight-week program, each student developed an individual research project from the data collected and delivered a conference-style final presentation on his/her results. We will discuss the results and effectiveness of the program from the first four summers and discuss plans for the future.

  18. Small Icing Wind Tunnel

    Czech Academy of Sciences Publication Activity Database

    Horák, V.; Hoření, Bohumír; Rozehnal, D.; Svoboda, E.

    Brno: University of Defence, 2007, s. 91-98. ISBN 978-80-7231-238-2. [ICMT'07, The international conference on military technologies. Brno (CZ), 02.05.2007-04.05.2007] R&D Projects: GA MPO FT-TA/026 Institutional research plan: CEZ:AV0Z20600510 Keywords : aircraft icing * icing wind tunnel * ice accretion Subject RIV: JR - Other Machinery

  19. Glacier dynamics after the disintegration of Wordie Ice Shelf, Antarctic Peninsula

    Science.gov (United States)

    Wendt, Anja; Bown, Francisca; Rivera, Andrés.; Wendt, Jens; Zamora, Rodrigo; Bravo, Claudio; Zenteno, Pablo; Casassa, Gino; Carrasco, Jorge; Quintana, Juan

    2010-05-01

    The retreat of Wordie Ice Shelf in the 1980s was the first recent episode in a series of ice-shelf collapse events which culminated in a substantial break-up of Wilkins Ice Shelf in April 2009. This widespread behaviour of ice shelves in the Antarctic Peninsula has been attributed to atmospheric and oceanic warming. While atmospheric warming leads to a prolonged melt season and increased melt ponding, oceanic warming increases bottom melting eroding ice shelves from below. Glaciers feeding into these ice shelves are known to accelerate because of the loss of the buttressing force the ice shelf exerted. Although the loss of the ice shelf itself does not contribute to sea level rise, the increased glacier outflow results in a surface lowering of the grounded glaciers associated with a mass loss and a positive contribution to sea level. Based on remote sensing, airborne and in-situ data collected during 3 recent field campaigns, we study the behaviour of glaciers flowing into Wordie Bay and its relationship to ice-shelf history and local meteorological conditions. Satellite images from different optical and radar sensors (ASTER, Landsat, ERS, and Envisat) were used to map the ice-shelf extent throughout recent years and show an almost complete disappearance of Wordie Ice Shelf. The comparison of surface elevations acquired by airborne laser scanning on Fleming Glacier in 2004 and 2008 reveals a surface elevation decrease of up to 4 m/yr at the grounding line. GPS measurements at sites first surveyed in the 1970s show that the glacier maintains higher ice flow velocities than before the retreat of Wordie Ice Shelf. A continuous GPS station deployed at the upper reaches of Fleming Glacier for one year allows studying changes in ice flow velocity throughout the year. In summary, high ice flow velocities together with the marked surface elevation at the grounding line indicate that the glaciers in Wordie Bay are still losing mass and have not attained a new equilibrium

  20. Monitoring and evaluation techniques for airborne contamination

    Energy Technology Data Exchange (ETDEWEB)

    Xia Yihua [China Inst. of Atomic Energy, Beijing (China)

    1997-06-01

    Monitoring and evaluation of airborne contamination are of great importance for the purpose of protection of health and safety of workers in nuclear installations. Because airborne contamination is one of the key sources to cause exposure to individuals by inhalation and digestion, and to cause diffusion of contaminants in the environment. The main objectives of monitoring and evaluation of airborne contamination are: to detect promptly a loss of control of airborne material, to help identify those individuals and predict exposure levels, to assess the intake and dose commitment to the individuals, and to provide sufficient documentation of airborne radioactivity. From the viewpoint of radiation protection, the radioactive contaminants in air can be classified into the following types: airborne aerosol, gas and noble gas, and volatile gas. In this paper, the following items are described: sampling methods and techniques, measurement and evaluation, and particle size analysis. (G.K.)

  1. Airborne Measurements of Coarse Mode Aerosol Composition and Abundance

    Science.gov (United States)

    Froyd, K. D.; Murphy, D. M.; Brock, C. A.; Ziemba, L. D.; Anderson, B. E.; Wilson, J. C.

    2015-12-01

    Coarse aerosol particles impact the earth's radiative balance by direct scattering and absorption of light and by promoting cloud formation. Modeling studies suggest that coarse mode mineral dust and sea salt aerosol are the dominant contributors to aerosol optical depth throughout much of the globe. Lab and field studies indicate that larger aerosol particles tend to be more efficient ice nuclei, and recent airborne measurements confirm the dominant role of mineral dust on cirrus cloud formation. However, our ability to simulate coarse mode particle abundance in large scale models is limited by a lack of validating measurements above the earth's surface. We present airborne measurements of coarse mode aerosol abundance and composition over several mid-latitude, sub-tropical, and tropical regions from the boundary layer to the stratosphere. In the free troposphere the coarse mode constitutes 10-50% of the total particulate mass over a wide range of environments. Above North America mineral dust typically dominates the coarse mode, but biomass burning particles and sea salt also contribute. In remote environments coarse mode aerosol mainly consists of internally mixed sulfate-organic particles. Both continental and marine convection can enhance coarse aerosol mass through direct lofting of primary particles and by secondary accumulation of aerosol material through cloud processing.

  2. IceBridge Data Management and Access Strategies at NSIDC

    Science.gov (United States)

    Oldenburg, J.; Tanner, S.; Collins, J. A.; Lewis, S.; FitzGerrell, A.

    2013-12-01

    NASA's Operation IceBridge (OIB) mission, initiated in 2009, collects airborne remote sensing measurements over the polar regions to bridge the gap between NASA's Ice, Cloud and Land Elevation satellite (ICESat) mission and the upcoming ICESat-2 mission in 2016. OIB combines an evolving mix of instruments to gather data on topography, ice and snow thickness, high-resolution photography, and other properties that are more difficult or impossible to measure via satellite. Once collected, these data are stored and made available at the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado. To date, there are nearly 90 terabytes of data available, and there are about three more years of data collection left. The main challenges faced in data management at NSIDC are derived from the quantity and heterogeneity of the data. To deal with the quantity of data, the technical teams at NSIDC have significantly automated the data ingest, metadata generation, and other required data management steps. Heterogeneity of data and the evolution of the Operation over time make technical automation complex. To limit complexity, the IceBridge team has agreed to such practices as using specific data file formats, limiting file sizes, using specific filename templates, etc. These agreements evolve as Operation IceBridge moves forward. The metadata generated about the flights and the data collected thereon make the storage of the data more robust, and enable data discoverability. With so much metadata, users can search the vast collection with ease using specific parameters about the data they seek. An example of this in action is the IceBridge data portal developed at NSIDC, http://nsidc.org/icebridge/portal/. This portal uses the GPS data from the flights projected onto maps as well as other flight and instrument metadata to help the user find the exact data file they seek. This implementation is only possible with dependable data management beneath the surface. The data files

  3. Electrospray Collection of Airborne Contaminants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In stark contrast to current stagnation-based methods for capturing airborne particulates and biological aerosols, our demonstrated, cost-effective electrospray...

  4. Variability of Basal Melt Beneath the Pine Island Glacier Ice Shelf, West Antarctica

    Science.gov (United States)

    Bindschadler, Robert; Vaughan, David G.; Vornberger, Patricia

    2011-01-01

    Observations from satellite and airborne platforms are combined with model calculations to infer the nature and efficiency of basal melting of the Pine Island Glacier ice shelf, West Antarctica, by ocean waters. Satellite imagery shows surface features that suggest ice-shelf-wide changes to the ocean s influence on the ice shelf as the grounding line retreated. Longitudinal profiles of ice surface and bottom elevations are analyzed to reveal a spatially dependent pattern of basal melt with an annual melt flux of 40.5 Gt/a. One profile captures a persistent set of surface waves that correlates with quasi-annual variations of atmospheric forcing of Amundsen Sea circulation patterns, establishing a direct connection between atmospheric variability and sub-ice-shelf melting. Ice surface troughs are hydrostatically compensated by ice-bottom voids up to 150m deep. Voids form dynamically at the grounding line, triggered by enhanced melting when warmer-than-average water arrives. Subsequent enlargement of the voids is thermally inefficient (4% or less) compared with an overall melting efficiency beneath the ice shelf of 22%. Residual warm water is believed to cause three persistent polynyas at the ice-shelf front seen in Landsat imagery. Landsat thermal imagery confirms the occurrence of warm water at the same locations.

  5. Tomographic Techniques for Radar Ice Sounding

    DEFF Research Database (Denmark)

    Nielsen, Ulrik

    the literature. The investigation also includes atheoretical study of beamforming and direction-of-arrival (DOA) estimationtechniques. In addition to the primary treatment of clutter suppression,additional novel applications of tomography are also explored. Based on an experimental multi......-phase-center dataset acquired withthe POLarimetric Airborne Radar Ice Sounder (POLARIS), single-passtomographic surface clutter suppression capabilities are demonstratedfor the system. Using repeat-pass POLARIS data, a method based ondata-driven DOA estimation is used to show an along-track variation ofthe effective...... scattering center of the surface return, which is caused bya varying penetration depth. As an alternative to the traditional echogram, a new DOA representationthat offers a better visualization of the desired signals and clutteris suggested. Based on this alternative presentation, a novel techniquefor...

  6. CryoVEx 2011-12 Airborne Campaigns for CryoSat Validation

    DEFF Research Database (Denmark)

    Skourup, Henriette; Hvidegaard, Sine Munk; Forsberg, René;

    2013-01-01

    After the successful launch of CryoSat-2 in April 2010, the first direct validation campaign of the satellite was carried out in the April-May 2011. Part of this was repeated in Spring 2012. DTU Space has been involved in ESA’s CryoSat Validation Experiment (CryoVEx) with airborne activities since...... 2003. To validate the performance of the CryoSat-2 radar altimeter (SIRAL), the aircraft is equipped with an airborne version of the SIRAL altimeter (ASIRAS) together with a laser scanner. Of particular interest is to study the penetration depth of SIRAL into both land- and sea ice. This can be done...... of Alert and sea ice around Svalbard in the Fram Strait. Selected tracks were planned to match CryoSat-2 passes and a few of them were flown in formation flight with the AlfredWegener Institute (AWI) Polar- 5 carrying an EM induction sounder. The paper presents an overview of the 2011-12 airborne campaigns...

  7. Sputtering of water ice

    DEFF Research Database (Denmark)

    Baragiola, R.A.; Vidal, R.A.; Svendsen, W.;

    2003-01-01

    We present results of a range of experiments of sputtering of water ice together with a guide to the literature. We studied how sputtering depends on the projectile energy and fluence, ice growth temperature, irradiation temperature and external electric fields. We observed luminescence from...

  8. Ice sheet in peril

    DEFF Research Database (Denmark)

    Hvidberg, Christine Schøtt

    2016-01-01

    Earth's large ice sheets in Greenland and Antarctica are major contributors to sea level change. At present, the Greenland Ice Sheet (see the photo) is losing mass in response to climate warming in Greenland (1), but the present changes also include a long-term response to past climate transitions...

  9. Testing The Ice

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The country’s fourth scientific expedition tothe North Pole starts OBSERVATION STATIONS:Members of China’s fourth Arctic expedition set up polar bear-proof "apple houses" on the ice surface of the Arctic Ocean on August 8 The Chinese ice breaker Xuelong

  10. Infrared Retrievals of Ice Cloud Properties and Uncertainties with an Optimal Estimation Retrieval Method

    Science.gov (United States)

    Wang, C.; Platnick, S. E.; Meyer, K.; Zhang, Z.

    2014-12-01

    We developed an optimal estimation (OE)-based method using infrared (IR) observations to retrieve ice cloud optical thickness (COT), cloud effective radius (CER), and cloud top height (CTH) simultaneously. The OE-based retrieval is coupled with a fast IR radiative transfer model (RTM) that simulates observations of different sensors, and corresponding Jacobians in cloudy atmospheres. Ice cloud optical properties are calculated using the MODIS Collection 6 (C6) ice crystal habit (severely roughened hexagonal column aggregates). The OE-based method can be applied to various IR space-borne and airborne sensors, such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and the enhanced MODIS Airborne Simulator (eMAS), by optimally selecting IR bands with high information content. Four major error sources (i.e., the measurement error, fast RTM error, model input error, and pre-assumed ice crystal habit error) are taken into account in our OE retrieval method. We show that measurement error and fast RTM error have little impact on cloud retrievals, whereas errors from the model input and pre-assumed ice crystal habit significantly increase retrieval uncertainties when the cloud is optically thin. Comparisons between the OE-retrieved ice cloud properties and other operational cloud products (e.g., the MODIS C6 and CALIOP cloud products) are shown.

  11. SMILES ice cloud products

    Science.gov (United States)

    MilláN, L.; Read, W.; Kasai, Y.; Lambert, A.; Livesey, N.; Mendrok, J.; Sagawa, H.; Sano, T.; Shiotani, M.; Wu, D. L.

    2013-06-01

    Upper tropospheric water vapor and clouds play an important role in Earth's climate, but knowledge of them, in particular diurnal variation in deep convective clouds, is limited. An essential variable to understand them is cloud ice water content. The Japanese Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on board the International Space Station (ISS) samples the atmosphere at different local times allowing the study of diurnal variability of atmospheric parameters. We describe a new ice cloud data set consisting of partial Ice Water Path and Ice Water Content. Preliminary comparisons with EOS-MLS, CloudSat-CPR and CALIOP-CALIPSO are presented. Then, the diurnal variation over land and over open ocean for partial ice water path is reported. Over land, a pronounced diurnal variation peaking strongly in the afternoon/early evening was found. Over the open ocean, little temporal dependence was encountered. This data set is publicly available for download in HDF5 format.

  12. Islands in the ice

    DEFF Research Database (Denmark)

    Jørgensen, Tina; Kjær, Kurt H.; Haile, James Seymour;

    2012-01-01

    Nunataks are isolated bedrocks protruding through ice sheets. They vary in age, but represent island environments in 'oceans' of ice through which organism dispersals and replacements can be studied over time. The J.A.D. Jensen's Nunataks at the southern Greenland ice sheet are the most isolated...... nunataks on the northern hemisphere - some 30 km from the nearest biological source. They constitute around 2 km(2) of ice-free land that was established in the early Holocene. We have investigated the changes in plant composition at these nunataks using both the results of surveys of the flora over the...... where the botanical survey was exhaustive. As no animals and humans are found on the nunataks, this change in diversity over a period of just 42 years must relate to environmental changes probably being climate-driven. This suggests that even the flora of fairly small and isolated ice-free areas reacts...

  13. Coating Reduces Ice Adhesion

    Science.gov (United States)

    Smith, Trent; Prince, Michael; DwWeese, Charles; Curtis, Leslie

    2008-01-01

    The Shuttle Ice Liberation Coating (SILC) has been developed to reduce the adhesion of ice to surfaces on the space shuttle. SILC, when coated on a surface (foam, metal, epoxy primer, polymer surfaces), will reduce the adhesion of ice by as much as 90 percent as compared to the corresponding uncoated surface. This innovation is a durable coating that can withstand several cycles of ice growth and removal without loss of anti-adhesion properties. SILC is made of a binder composed of varying weight percents of siloxane(s), ethyl alcohol, ethyl sulfate, isopropyl alcohol, and of fine-particle polytetrafluoroethylene (PTFE). The combination of these components produces a coating with significantly improved weathering characteristics over the siloxane system alone. In some cases, the coating will delay ice formation and can reduce the amount of ice formed. SILC is not an ice prevention coating, but the very high water contact angle (greater than 140 ) causes water to readily run off the surface. This coating was designed for use at temperatures near -170 F (-112 C). Ice adhesion tests performed at temperatures from -170 to 20 F (-112 to -7 C) show that SILC is a very effective ice release coating. SILC can be left as applied (opaque) or buffed off until the surface appears clear. Energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS) data show that the coating is still present after buffing to transparency. This means SILC can be used to prevent ice adhesion even when coating windows or other objects, or items that require transmission of optical light. Car windshields are kept cleaner and SILC effectively mitigates rain and snow under driving conditions.

  14. Evaluation of Arctic Sea Ice Thickness Simulated by AOMIP Models

    Science.gov (United States)

    Johnson, Mark; Proshutinsky, Andrey; Aksenov, Yevgeny; Nguyen, An T.; Lindsay, Ron; Haas, Christian; Zhang, Jinlun; Diansky, Nimolay; Kwok, Ron; Maslowski, Wieslaw; Hakkinen, Sirpa; Ashik, Igor; de Cuevas, Beverly

    2011-01-01

    We compare results from six AOMIP model simulations with estimates of sea ice thickness obtained from ICESat, moored and submarine-based upward looking sensors, airborne electromagnetic measurements and drill holes. Our goal is to find patterns of model performance to guide model improvement. The satellite data is pan-arctic from 2004-2008, ice-draft data is from moored instruments in Fram Strait, the Greenland Sea and the Beaufort Sea from 1992-2008 and from submarines from 1975-2000. The drill hole data are from the Laptev and East Siberian marginal seas from 1982-1986 and from coastal stations from 1998-2009. While there are important caveats when comparing modeled results with measurements from different platforms and time periods such as these, the models agree well with moored ULS data. In general, the AOMIP models underestimate the thickness of measured ice thicker than about 2 m and overestimate thickness of ice thinner than 2 m. The simulated results are poor over the fast ice and marginal seas of the Siberian shelves. Averaging over all observational data sets, the better correlations and smaller differences from observed thickness are from the ECCO2 and UW models.

  15. Chemical Microsensor Instrument for UAV Airborne Atmospheric Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering, Inc. (MEI) proposes to develop a miniaturized Airborne Chemical Microsensor Instrument (ACMI) suitable for real-time, airborne measurements of...

  16. Geophex airborne unmanned survey system

    International Nuclear Information System (INIS)

    The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This nonintrusive system will provide open-quotes stand-offclose quotes capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. This system permits two operators to rapidly conduct geophysical characterization of hazardous environmental sites. During a survey, the operators remain remote from, but within visual distance, of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak anomalies can be detected

  17. Airborne Research Experience for Educators

    Science.gov (United States)

    Costa, V. B.; Albertson, R.; Smith, S.; Stockman, S. A.

    2009-12-01

    The Airborne Research Experience for Educators (AREE) Program, conducted by the NASA Dryden Flight Research Center Office of Education in partnership with the AERO Institute, NASA Teaching From Space Program, and California State University Fullerton, is a complete end-to-end residential research experience in airborne remote sensing and atmospheric science. The 2009 program engaged ten secondary educators who specialize in science, technology, engineering or mathematics in a 6-week Student Airborne Research Program (SARP) offered through NSERC. Educators participated in collection of in-flight remote sensor data during flights aboard the NASA DC-8 as well as in-situ research on atmospheric chemistry (bovine emissions of methane); algal blooms (remote sensing to determine location and degree of blooms for further in-situ analysis); and crop classification (exploration of how drought conditions in Central California have impacted almond and cotton crops). AREE represents a unique model of the STEM teacher-as-researcher professional development experience because it asks educators to participate in a research experience and then translate their experiences into classroom practice through the design, implementation, and evaluation of instructional materials that emphasize the scientific research process, inquiry-based investigations, and manipulation of real data. Each AREE Master Educator drafted a Curriculum Brief, Teachers Guide, and accompanying resources for a topic in their teaching assignment Currently, most professional development programs offer either a research experience OR a curriculum development experience. The dual nature of the AREE model engaged educators in both experiences. Educators’ content and pedagogical knowledge of STEM was increased through the review of pertinent research articles during the first week, attendance at lectures and workshops during the second week, and participation in the airborne and in-situ research studies, data

  18. Geophex Airborne Unmanned Survey System

    Energy Technology Data Exchange (ETDEWEB)

    Won, I.J.; Keiswetter, D. [Geophex, Ltd., Raleigh, NC (United States)

    1995-10-01

    The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide {open_quotes}stand-off{close_quotes} capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. This system permits rapid geophysical characterization of hazardous environmental sites. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected.

  19. GLERL Radiation Transfer Through Freshwater Ice

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Radiation transmittance (ratio of transmitted to incident radiation) through clear ice, refrozen slush ice and brash ice, from ice surface to ice-water interface in...

  20. Arctic Ocean gravity, geoid and sea-ice freeboard heights from ICESat and GRACE

    DEFF Research Database (Denmark)

    Forsberg, René; Skourup, Henriette

    2005-01-01

    coverage of multi-year sea-ice; however, comparison to an airborne lidar underflight north of Greenland shows that the lowest-level filtering scheme may introduce a bias. We finally use the ICESat and GRACE results to derive new gravity anomalies by Fourier inversion. The satellite-only gravity field shows...... all major tectonic features of the Arctic Ocean, and has an accuracy of 6 mGal compared to recent airborne gravity data, illustrating the usefulness of ICESat data for gravity field determination....

  1. Airborne Oceanographic Lidar (AOL) (Global Carbon Cycle)

    Science.gov (United States)

    2003-01-01

    This bimonthly contractor progress report covers the operation, maintenance and data management of the Airborne Oceanographic Lidar and the Airborne Topographic Mapper. Monthly activities included: mission planning, sensor operation and calibration, data processing, data analysis, network development and maintenance and instrument maintenance engineering and fabrication.

  2. A system for airborne SAR interferometry

    DEFF Research Database (Denmark)

    Madsen, Søren Nørvang; Skou, Niels; Granholm, Johan;

    1996-01-01

    Interferometric synthetic aperture radar (INSAR) systems have already demonstrated that elevation maps can be generated rapidly with single pass airborne across-track interferometry systems (XTT), and satellite repeat track interferometry (RTT) techniques have been used to map both elevation and......) the status of the airborne interferometry activities at DCRS, including the present system configuration, recent results, and some scientific applications of the system....

  3. Geophex Airborne Unmanned Survey System

    International Nuclear Information System (INIS)

    Ground-based surveys place personnel at risk due to the proximity of buried unexploded ordnance (UXO) items or by exposure to radioactive materials and hazardous chemicals. The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide stand-off capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected. The Geophex Airborne Unmanned Survey System (GAUSS) is designed to detect and locate small-scale anomalies at hazardous sites using magnetic and electromagnetic survey techniques. The system consists of a remotely-piloted, radio-controlled, model helicopter (RCH) with flight computer, light-weight geophysical sensors, an electronic positioning system, a data telemetry system, and a computer base-station. The report describes GAUSS and its test results

  4. Airborne fourier infrared spectrometer system

    International Nuclear Information System (INIS)

    A commercial Fourier Transform Infrared (FTIR) spectrometer has been interfaced to a 35 cm aperture telescope and a digital data processing and display system and flown in a downward-viewing configuration on a Queen Air aircraft. Real-time spectral analysis and display software were developed to provide the means to direct aircraft flight operations based on atmospheric and/or surface features identified on 1 to 8 cm-1 resolution infrared spectra. Data are presented from ground-based tests consisting of simultaneous horizontal path measurements by the FTIR system and an infrared differential absorption lidar (DIAL) observing gas volumes generated in an open-ended chamber. Airborne FUR data are presented on the tracking of a surface-released puff of SF6 gas to a downwind distance of 45 km in a time period of 1.5 hours. The experiment demonstrated the real time tracking of a gas tracer cloud to provide atmospheric transport and diffusion information and for directing airborne in-situ sensors for optimum cloud sampling. 5 refs., 5 figs

  5. Cyclic steps on ice

    Science.gov (United States)

    Yokokawa, M.; Izumi, N.; Naito, K.; Parker, G.; Yamada, T.; Greve, R.

    2016-05-01

    Boundary waves often form at the interface between ice and fluid flowing adjacent to it, such as ripples under river ice covers, and steps on the bed of supraglacial meltwater channels. They may also be formed by wind, such as the megadunes on the Antarctic ice sheet. Spiral troughs on the polar ice caps of Mars have been interpreted to be cyclic steps formed by katabatic wind blowing over ice. Cyclic steps are relatives of upstream-migrating antidunes. Cyclic step formation on ice is not only a mechanical but also a thermodynamic process. There have been very few studies on the formation of either cyclic steps or upstream-migrating antidunes on ice. In this study, we performed flume experiments to reproduce cyclic steps on ice by flowing water, and found that trains of steps form when the Froude number is larger than unity. The features of those steps allow them to be identified as ice-bed analogs of cyclic steps in alluvial and bedrock rivers. We performed a linear stability analysis and obtained a physical explanation of the formation of upstream-migrating antidunes, i.e., precursors of cyclic steps. We compared the results of experiments with the predictions of the analysis and found the observed steps fall in the range where the analysis predicts interfacial instability. We also found that short antidune-like undulations formed as a precursor to the appearance of well-defined steps. This fact suggests that such antidune-like undulations correspond to the instability predicted by the analysis and are precursors of cyclic steps.

  6. An airborne 95 GHz dual-polarized radar for cloud studies

    Energy Technology Data Exchange (ETDEWEB)

    Pazmany, A.L.; McIntosh, R.E. (Univ. of Massachusetts, Amherst, MA (United States). Microwave Remote Sensing Lab.); Kelly, R.D.; Vali, G. (Univ. of Wyoming, Laramie, WY (United States). Dept. of Atmospheric Sciences)

    1994-07-01

    A 95 GHz dual-polarization radar system was developed and flown on the University of Wyoming King Air research aircraft, from which it measured reflectivity, depolarization, and Doppler-derived velocity mean and standard deviation of a variety of clouds. This paper describes the radar and a data acquisition system that uses commercially available digitizers, signal processors, and signal generators. The authors also describe the tradeoffs between spatial resolution and their ability to estimate reflectivity and velocity. This paper presents the first known airborne measurements of clouds made at 95 GHz; these are thought to be the most highly resolved millimeter-wave cloud images made to date. Depolarization, measured in terms of the linear depolarization ratio (LDR), was especially high in the melting band and in regions containing pristine ice crystals. These measurements demonstrate the advances that high-spatial-resolution airborne millimeter-wave radars offer for the study of cloud microphysical properties.

  7. Initial Cooling Experiment (ICE)

    CERN Multimedia

    Photographic Service

    1978-01-01

    In 1977, in a record-time of 9 months, the magnets of the g-2 experiment were modified and used to build a proton/antiproton storage ring: the "Initial Cooling Experiment" (ICE). It served for the verification of the cooling methods to be used for the "Antiproton Project". Stochastic cooling was proven the same year, electron cooling followed later. Also, with ICE the experimental lower limit for the antiproton lifetime was raised by 9 orders of magnitude: from 2 microseconds to 32 hours. For its previous life as g-2 storage ring, see 7405430. More on ICE: 7711282, 7809081, 7908242.

  8. 趣话ice

    Institute of Scientific and Technical Information of China (English)

    刘奉越

    2002-01-01

    在英语中,ice是一个很普通的词,它的基本含义是“冰,冰块”。如:The sportsman slipped on the ice and one of his legs was broken.(这个运动员在冰上滑倒了,一条腿摔断了。)它还可指“冰淇淋”,相当于ice cream。如.After having two ices I felt uncomfortable.

  9. PROTONIC PHOTOCONDUCTIVITY OF ICE

    OpenAIRE

    Petrenko, V.; Ebinuma, T.; Maeno, N.

    1987-01-01

    A number of attempts have been made to find the protonic photoconductivity of ice (abbreviated as PPC hereafter), but most of them were not successful. Camp and Spears (1) tried to excite PPC of pure ice single crystals by a xenon lamp and concluded that the probability of photodissociation of ice, if any, is very small. De Haas et al. (2) and Itagaki et al. (3) used gamma-rays, X-rays, or electron beams, and found a change in the electrical conductivity. Very high-energy beams were used in t...

  10. Ice nucleation terminology

    Science.gov (United States)

    Vali, G.; DeMott, P.; Möhler, O.; Whale, T. F.

    2014-08-01

    Progress in the understanding of ice nucleation is being hampered by the lack of uniformity in how some terms are used in the literature. This even extends to some ambiguity of meanings attached to some terms. Suggestions are put forward here for common use of terms. Some are already well established and clear of ambiguities. Others are less engrained and will need a conscious effort in adoption. Evolution in the range of systems where ice nucleation is being studied enhances the need for a clear nomenclature. The ultimate limit in the clarity of definitions is, of course, the limited degree to which ice nucleation processes are understood.

  11. Sea Ice Topography Profiling using Laser Altimetry from Small Unmanned Aircraft Systems

    Science.gov (United States)

    Crocker, Roger Ian

    Arctic sea ice is undergoing a dramatic transition from a perennial ice pack with a high prevalence of old multiyear ice, to a predominantly seasonal ice pack comprised primarily of young first-year and second-year ice. This transition has brought about changes in the sea ice thickness and topography characteristics, which will further affect the evolution and survivability of the ice pack. The varying ice conditions have substantial implications for commercial operations, international affairs, regional and global climate, our ability to model climate dynamics, and the livelihood of Arctic inhabitants. A number of satellite and airborne missions are dedicated to monitoring sea ice, but they are limited by their spatial and temporal resolution and coverage. Given the fast rate of sea ice change and its pervasive implications, enhanced observational capabilities are needed to augment the current strategies. The CU Laser Profilometer and Imaging System (CULPIS) is designed specifically for collecting fine-resolution elevation data and imagery from small unmanned aircraft systems (UAS), and has a great potential to compliment ongoing missions. This altimeter system has been integrated into four different UAS, and has been deployed during Arctic and Antarctic science campaigns. The CULPIS elevation measurement accuracy is shown to be 95±25 cm, and is limited primarily by GPS positioning error (<25 cm), aircraft attitude determination error (<20 cm), and sensor misalignment error (<20 cm). The relative error is considerably smaller over short flight distances, and the measurement precision is shown to be <10 cm over a distance of 200 m. Given its fine precision, the CULPIS is well suited for measuring sea ice topography, and observed ridge height and ridge separation distributions are found to agree with theoretical distributions to within 5%. Simulations demonstrate the inability of course-resolution measurements to accurately represent the theoretical distributions

  12. Milankovitch solar rdiation variations and ice age ice sheet sizes

    International Nuclear Information System (INIS)

    The fluctuations in the size of ice age ice sheets are caclulated using glacier mechanics and the Milankovitch solar radiation variations. The calculations are greatly simplified by considering only two-dimensional ice sheets with profiles that would be appropriate if ice obeyed the flow law of a perfectly plastic solid. The solar radiation variations seem to be large enough to account for ice ages. (author)

  13. Vortex ice in nanostructured superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia J [Los Alamos National Laboratory; Libal, Andras J [Los Alamos National Laboratory

    2008-01-01

    We demonstrate using numerical simulations of nanostructured superconductors that it is possible to realize vortex ice states that are analogous to square and kagome ice. The system can be brought into a state that obeys either global or local ice rules by applying an external current according to an annealing protocol. We explore the breakdown of the ice rules due to disorder in the nanostructure array and show that in square ice, topological defects appear along grain boundaries, while in kagome ice, individual defects appear. We argue that the vortex system offers significant advantages over other artificial ice systems.

  14. A new regional high-resolution map of basal and surface topography for the Greenland ice-sheet margin at Paakitsoq, West Greenland

    DEFF Research Database (Denmark)

    Mottram, R.; Nielsen, C.; Ahlstrøm, A. P.;

    2009-01-01

    In 2005 an airborne survey was carried out from a Twin Otter aircraft at Pâkitsup Akuliarusersua (Paakitsoq) near Ilulissat in West Greenland. The survey aimed to measure ice thickness with a 60 MHz cohrent radar and surface elevation with a scanning laser altimeter.......In 2005 an airborne survey was carried out from a Twin Otter aircraft at Pâkitsup Akuliarusersua (Paakitsoq) near Ilulissat in West Greenland. The survey aimed to measure ice thickness with a 60 MHz cohrent radar and surface elevation with a scanning laser altimeter....

  15. Ice Cream Stick Math.

    Science.gov (United States)

    Paddock, Cynthia

    1992-01-01

    Described is a teaching technique which uses the collection of ice cream sticks as a means of increasing awareness of quantity in a self-contained elementary special class for students with learning disabilities and mild mental retardation. (DB)

  16. Global ice sheet modeling

    International Nuclear Information System (INIS)

    The University of Maine conducted this study for Pacific Northwest Laboratory (PNL) as part of a global climate modeling task for site characterization of the potential nuclear waste respository site at Yucca Mountain, NV. The purpose of the study was to develop a global ice sheet dynamics model that will forecast the three-dimensional configuration of global ice sheets for specific climate change scenarios. The objective of the third (final) year of the work was to produce ice sheet data for glaciation scenarios covering the next 100,000 years. This was accomplished using both the map-plane and flowband solutions of our time-dependent, finite-element gridpoint model. The theory and equations used to develop the ice sheet models are presented. Three future scenarios were simulated by the model and results are discussed

  17. Bathymetry of Grounding Zones and Sub-Ice Shelf Cavities of the Amundsen Sea, from Operation IceBridge Gravity Inversions

    Science.gov (United States)

    Tinto, K. J.; Cochran, J. R.; Bell, R. E.

    2012-12-01

    lying offshore of the Thwaites Glacier grounding line. Dotson ice shelf flows approximately north-south, fed mainly by the Kohler Glacier. Offshore, at the northern front of the ice shelf, swath bathymetry shows water depths of ~800-1000 m. Under the central part of the ice shelf gravity anomalies are ~50 mGal lower, indicating water depths down to 1400 m under 350 m thick ice. Within ~25 km of the grounding zone the average bathymetry is ~400 m shallower and the ice thicker, leaving a water cavity of ~500 m. The ice shelf is pinned by an ice rise at the boundary between thinner and thicker ice. Crosson and Dotson ice shelves are divided by an east-west trending line of ice rises and nunataks. In the last decade, airborne surveys have provided evidence for grounding line retreat in this region and satellite surveys have suggested possible pathways for circulation between the two ice shelves. Meanwhile models of melting patterns require accurate bathymetric models in order to replicate observed patterns of ice shelf thinning. Knowledge of the sea floor geometry of the Amundsen Sea is therefore a prerequisite for understanding the changes in both ice shelves and glaciers of the region.

  18. Temperate Ice Depth-Sounding Radar

    Science.gov (United States)

    Jara-Olivares, V. A.; Player, K.; Rodriguez-Morales, F.; Gogineni, P.

    2008-12-01

    . It also digitizes the output signal from the receiver and stores the data in binary format using a portable computer. The RF-section consists of a high- power transmitter and a low-noise receiver with digitally controlled variable gain. The antenna is time-shared between the transmitter and receiver by means of a transmit/receive (T/R) switch. In regards to the antenna, we have made a survey study of various electrically small antennas (ESA) to choose the most suitable radiating structure for this application. Among the different alternatives that provide a good trade-off between electrical performance and small size, we have adopted an ESA dipole configuration for airborne platforms and a half-wavelength radiator for the surface-based version. The airborne antenna solution is given after studying the geometry of the aerial vehicle and its fuselage contribution to the antenna radiation pattern. Dipoles are made of 11.6 mm diameter cables (AWG 0000) or printed patches embedded into the aircraft fuselage, wings, or both. The system is currently being integrated and tested. TIDSoR is expected to be deployed during the spring 2008 either in Alaska or Greenland for surface based observations. In this paper, we will discuss our design considerations and current progress towards the development of this radar system. [1] Center for Remote Sensing of Ice Sheets (Cresis), Sept 2008, [Online]. Available: http://www.cresis.ku.edu

  19. Ice slurry accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, K.G.; Kauffeld, M.

    1998-06-01

    More and more refrigeration systems are designed with secondary loops, thus reducing the refrigerant charge of the primary refrigeration plant. In order not to increase energy consumption by introducing a secondary refrigerant, alternatives to the well established single phase coolants (brines) and different concepts of the cooling plant have to be evaluated. Combining the use of ice-slurry - mixture of water, a freezing point depressing agent (antifreeze) and ice particles - as melting secondary refrigerant and the use of a cool storage makes it possible to build plants with secondary loops without increasing the energy consumption and investment. At the same time the operating costs can be kept at a lower level. The accumulation of ice-slurry is compared with other and more traditional storage systems. The method is evaluated and the potential in different applications is estimated. Aspects of practically use of ice-slurry has been examined in the laboratory at the Danish Technological Institute (DTI). This paper will include the final conclusions from this work concerning tank construction, agitator system, inlet, outlet and control. The work at DTI indicates that in some applications systems with ice-slurry and accumulation tanks have a great future. These applications are described by a varying load profile and a process temperature suiting the temperature of ice-slurry (-3 - -8/deg. C). (au)

  20. Ice-Borehole Probe

    Science.gov (United States)

    Behar, Alberto; Carsey, Frank; Lane, Arthur; Engelhardt, Herman

    2006-01-01

    An instrumentation system has been developed for studying interactions between a glacier or ice sheet and the underlying rock and/or soil. Prior borehole imaging systems have been used in well-drilling and mineral-exploration applications and for studying relatively thin valley glaciers, but have not been used for studying thick ice sheets like those of Antarctica. The system includes a cylindrical imaging probe that is lowered into a hole that has been bored through the ice to the ice/bedrock interface by use of an established hot-water-jet technique. The images acquired by the cameras yield information on the movement of the ice relative to the bedrock and on visible features of the lower structure of the ice sheet, including ice layers formed at different times, bubbles, and mineralogical inclusions. At the time of reporting the information for this article, the system was just deployed in two boreholes on the Amery ice shelf in East Antarctica and after successful 2000 2001 deployments in 4 boreholes at Ice Stream C, West Antarctica, and in 2002 at Black Rapids Glacier, Alaska. The probe is designed to operate at temperatures from 40 to +40 C and to withstand the cold, wet, high-pressure [130-atm (13.20-MPa)] environment at the bottom of a water-filled borehole in ice as deep as 1.6 km. A current version is being outfitted to service 2.4-km-deep boreholes at the Rutford Ice Stream in West Antarctica. The probe (see figure) contains a sidelooking charge-coupled-device (CCD) camera that generates both a real-time analog video signal and a sequence of still-image data, and contains a digital videotape recorder. The probe also contains a downward-looking CCD analog video camera, plus halogen lamps to illuminate the fields of view of both cameras. The analog video outputs of the cameras are converted to optical signals that are transmitted to a surface station via optical fibers in a cable. Electric power is supplied to the probe through wires in the cable at a

  1. Airborne gamma ray spectrometer surveying

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency (IAEA) in its role as collector and disseminator of information on nuclear techniques has long had an interest in gamma ray spectrometer methods and has published a number of Technical Reports on various aspects of the subject. At an Advisory Group Meeting held in Vienna in November 1986 to review appropriate activities the IAEA could take following the Chernobyl accident, it was recommended that preparation begin on a new Technical Report on airborne gamma ray spectrometer surveying, taking into account the use of the technique for environmental monitoring as well as for nuclear emergency response requirements. Shortly thereafter the IAEA became the lead organization in the Radioelement Geochemical Mapping section of the International Geological Correlation Programme/United Nations Educational, Scientific and Cultural Organization (UNESCO) Project on International Geochemical Mapping. These two factors led to the preparation of the present Technical Report. 18 figs, 4 tabs

  2. Airborne synthetic aperture acoustic imaging.

    Science.gov (United States)

    Soumekh, M

    1997-01-01

    This paper presents a system model and inversion for airborne synthetic aperture acoustic (SAA) imaging. The system model accurately represents the intercation of the acoustic source and the target region at near range values. Moreover, the model incorporates the fact that the relative speed of the vehicle's (transmitter/receiver) with respect to the target region is comparable to the acoustic wave propagation speed. The inversion utilizes the principle of spectral decomposition of spherical phase functions to develop a wavefront reconstruction method from SAA data. Processing issues and selection of appropriate acoustic FM-CW sources are discussed. Results are provided that exhibit the superior accuracy of the proposed SAA system model and inversion over their synthetic aperture radar (SAR) counterpart in which the vehicle's speed is assumed to be much smaller than the wave propagation speed. PMID:18282912

  3. Predictors of airborne endotoxin in the home.

    OpenAIRE

    Park, J. H.; Spiegelman, D L; Gold, D R; Burge, H A; Milton, D K

    2001-01-01

    We identified home characteristics associated with the level of airborne endotoxin in 111 Boston-area homes enrolled in a cohort study of home exposures and childhood asthma, and we developed a predictive model to estimate airborne endotoxin. We measured endotoxin in family-room air and in dust from the baby's bed, family room, bedroom, and kitchen floor. Level of airborne endotoxin was weakly correlated (r < 0.3) with level of endotoxin in each of the four types of dust samples and was signi...

  4. Comparison of sea-ice freeboard distributions from aircraft data and cryosat-2

    OpenAIRE

    Ricker, Robert; Hendricks, Stefan; Helm, Veit; Gerdes, Rudiger; Skourup, Henriette; Ouwehand, L.

    2012-01-01

    The only remote sensing technique capable of obtaining sea ice thickness on basin-scale are satellite altimeter missions, such as the 2010 launched CryoSat-2. It is equipped with a Ku-Band radar altimeter which measures the height of the ice surface above the water level. This method requires highly accurate range measurements. During the CryoSat Validation Experiment (CryoVEx) 2011 in the Lincoln Sea Cryosat-2 underpasses were accomplished with two aircraft which carried an airborne laser sc...

  5. The Glacier and Ice Surface Topography Interferometer: UAVSAR's Single-pass Ka-Band Interferometer

    Science.gov (United States)

    Moller, D.; Hensley, S.; Wu, X.; Michel, T.; Muellerschoen, R.; Carswell, J.; Fisher, C.; Miller, T.; Milligan, L.; Sadowy, G.; Sanchez-Barbetty, M.; Lou, Y.

    2013-12-01

    In May 2009 a new radar technique for mapping ice surface topography was demonstrated in a Greenland campaign as part of the NASA International Polar Year (IPY) activities. This was achieved with the airborne Glacier and Ice Surface Topography Interferometer (GLISTIN-A): a 35.6 GHz single-pass interferometer. The proof-of-concept demonstration was achieved by interfacing Ka-band RF and antenna hardware with the Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR). The GLISTIN-A was implemented as a custom installation of the NASA Dryden Flight Research Center Gulfstream III. Instrument performance indicated swath widths over the ice between 5-7km, with height precisions ranging from 30cm-3m at a posting of 3m x 3m. Following the success of the IPY campaign, the Earth Science Techonology Office (ESTO) Airborne Innovative Technology Transition (AITT) program funded the upgrade of GLISTIN-A to a permanently-available pod-only system compatible with unpressurized operation. The AITT made three fundamental upgrades to improve system performance: 1. State-of-the-art solid-state power amplifiers (80W peak) were integrated directly on the antenna panel reducing front-end losses; 2. A ping-pong capability was incorporated to effectively double the baseline thereby improving height measurement precision by a factor of two; and 3. A high-fidelity calibration loop was implemented which is critical for routine processing. Upon completion of our engineering flights in February 2013, GLISTIN-A flew a brief campaign to Alaska (4/24-4/27/13). The purpose was to fully demonstrate GLISTIN-A's ability to generate high-precision, high resolution maps of ice surface topography with swaths in excess of 10km. Furthermore, the question of the utility of GLISTIN-A for sea-ice mapping, tracking and inventory has received a great deal of interest. To address this GLISTIN-A collected data over sea-ice in the Beaufort sea including an underflight of CryoSAT II. Note that there are

  6. Phase-sensitive radar on thick Antarctic ice - how well does it work?

    Science.gov (United States)

    Binder, Tobias; Eisen, Olaf; Helm, Veit; Humbert, Angelika; Steinhage, Daniel

    2016-04-01

    Phase-sensitive radar (pRES) has become one of the mostly used tools to determine basal melt rates as well as vertical strain in ice sheets. Whereas most applications are performed on ice shelves, only few experiments were conducted on thick ice in Greenland or Antarctica. The technical constrains on an ice shelf to deduce basal melt rates are less demanding than on inland ice of more than 2 km thickness. First, the ice itself is usually only several 100s of meters thick; and, second, the reflection coefficient at the basal interface between sea water and ice is the second strongest one possible. Although the presence of marine ice with higher conductivities might increase attenuation in the lower parts, most experiments on shelves were successful. To transfer this technology to inland regions, either for the investigation of basal melt rates of subglacial hydrological networks or for determining vertical strain rates in basal regions, a reliable estimate of the current system performance is necessary. To this end we conducted an experiment at and in the vicinity of the EPICA deep ice core drill site EDML in Dronning Maud Land, Antarctica. That site has been explored in extraordinary detail with different geophysical methods and provides an already well-studied ice core and borehole, in particular with respect to physical properties like crystal orientation fabric, dielectric properties and matching of internal radar horizons with conductivity signals. We present data from a commercially available pRES system initially recorded in January 2015 and repeated measurements in January 2016. The pRES data are matched to existing and already depth-calibrated airborne radar data. Apart from identifying prominent internal layers, e.g. the one originating from the deposits of the Toba eruption at around 75 ka, we put special focus on the identification of the basal reflection at multiple polarizations. We discuss the potential uncertainty estimates and requirements to

  7. Recent summer sea ice thickness surveys in the Fram Strait and associated volume fluxes

    Directory of Open Access Journals (Sweden)

    T. Krumpen

    2015-09-01

    Full Text Available Fram Strait is the main gateway for sea ice export out of the Arctic Ocean, and therefore observations there give insight into composition and properties of Arctic sea ice in general and how it varies over time. An extensive data set of ground-based and airborne electromagnetic ice thickness measurements collected between 2001 and 2012 is presented here, including long transects well into the southern part of the Transpolar Drift obtained using fixed-wing aircrafts. The source area for the surveyed ice is primarily the Laptev Sea, and the estimated age is consistent with a decreased from 3 to 2 years between 1990 and 2012. The data consistently also show a general thinning for the last decade, with a decrease in modal thickness of second year and multiyear ice, and a decrease in mean thickness and fraction of ice thicker than 3 m. Local melting in the strait was investigated in two surveys performed in the downstream direction, showing a decrease of 0.19 m degree−1 latitude south of 81° N probably driven by bottom melting from warm water of Atlantic origin. Further north variability in ice thickness is more related to differences in age and deformation. The thickness observations were combined with ice area export estimates to calculate summer volume fluxes of sea ice. This shows that it is possible to determine volume fluxes through Fram Strait during summer when satellite based sea ice thickness information is missing. While the ice area export based on satellite remote sensing shows positive trends since 2001, the mean fluxes during summer (July and August are small (18 km3, and long-term trends are uncertain due to the limited surveys available.

  8. The Ice Selective Inlet: a novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds

    Science.gov (United States)

    Kupiszewski, P.; Weingartner, E.; Vochezer, P.; Schnaiter, M.; Bigi, A.; Gysel, M.; Rosati, B.; Toprak, E.; Mertes, S.; Baltensperger, U.

    2015-08-01

    Climate predictions are affected by high uncertainties partially due to an insufficient knowledge of aerosol-cloud interactions. One of the poorly understood processes is formation of mixed-phase clouds (MPCs) via heterogeneous ice nucleation. Field measurements of the atmospheric ice phase in MPCs are challenging due to the presence of much more numerous liquid droplets. The Ice Selective Inlet (ISI), presented in this paper, is a novel inlet designed to selectively sample pristine ice crystals in mixed-phase clouds and extract the ice residual particles contained within the crystals for physical and chemical characterization. Using a modular setup composed of a cyclone impactor, droplet evaporation unit and pumped counterflow virtual impactor (PCVI), the ISI segregates particles based on their inertia and phase, exclusively extracting small ice particles between 5 and 20 μm in diameter. The setup also includes optical particle spectrometers for analysis of the number size distribution and shape of the sampled hydrometeors. The novelty of the ISI is a droplet evaporation unit, which separates liquid droplets and ice crystals in the airborne state, thus avoiding physical impaction of the hydrometeors and limiting potential artefacts. The design and validation of the droplet evaporation unit is based on modelling studies of droplet evaporation rates and computational fluid dynamics simulations of gas and particle flows through the unit. Prior to deployment in the field, an inter-comparison of the optical particle size spectrometers and a characterization of the transmission efficiency of the PCVI was conducted in the laboratory. The ISI was subsequently deployed during the Cloud and Aerosol Characterization Experiment (CLACE) 2013 and 2014 - two extensive international field campaigns encompassing comprehensive measurements of cloud microphysics, as well as bulk aerosol, ice residual and ice nuclei properties. The campaigns provided an important opportunity for a

  9. Airborne Digital Camera. A digital view from above; Airborne Digital Camera. Der digitale Blick von oben

    Energy Technology Data Exchange (ETDEWEB)

    Roeser, H.P. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Berlin (Germany). Inst. fuer Weltraumsensorik und Planetenerkundung

    1999-09-01

    The Airborne Digital Camera is based on the WAOSS camera of the MARS-96 mission. The camera will provide a new basis for airborne photogrammetry and remote exploration. The ADC project aims at the development of the first commercial digital airborne camera. [German] Die Wurzeln des Projektes Airborne Digital Camera (ADC) liegen in der Mission MARS-96. Die hierfuer konzipierte Marskamera WAOSS lieferte die Grundlage fuer das innovative Konzept einer digitalen Flugzeugkamera. Diese ist auf dem Weg, die flugzeuggestuetzte Photogrammetrie und Fernerkundung auf eine technologisch voellig neue Basis zu stellen. Ziel des Projektes ADC ist die Entwicklung der ersten kommerziellen digitalen Luftbildkamera. (orig.)

  10. Single-photon, Dual-color, Polarimetric Laser Altimeter Measurements of Lake Ice Freeboard, Roughness and Scattering Properties

    Science.gov (United States)

    Harding, D. J.; Dabney, P.; Valett, S.; Shuman, C. A.

    2009-12-01

    The Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) is an advanced technology airborne laser altimeter developed with a focus on remote sensing of ice sheets and sea ice including their melt state. Its development was sponsored by the NASA Earth Science Technology Office Instrument Incubator Program. SIMPL utilizes micropulse single photon laser ranging at 532 nm (green) and 1064 nm (near-infrared) wavelengths in a four-beam push-broom configuration. Currently, the instrument is capable of flight altitudes of up to 5000 m; this spreads the 4 profiles over a cross-track distance of 30 m providing an estimate of both along-track and cross-track slope magnitudes and directions. For both wavelengths on each beam, depolarization is measured as the ratio of received energy perpendicular and parallel to the plane-polarized transmit beams. The precision of the single photon ranges is 8 cm and a range observation is acquired every 5 to 10 cm at airborne flight speeds. This performance enables measurement of ice freeboard and surface roughness at 5 m length scales based on the height dispersion of single photon ranges aggregated along the profiles. The depolarization ratio is a function of the scattering properties of the target, specifically the proportions of specular reflection and surface and volume scattering. The relationship between surface roughness and depolarization at green and near-IR wavelengths will be illustrated using data acquired during flights over Lake Erie ice cover in February 2009, an analog for sea ice. Observed in simultaneously acquired digital video frames, the ice cover appears to be a heterogeneous amalgamation of ice types, thicknesses and ages. The lake ice is covered by snow in places and contains numerous open water leads to enable ice freeboard detection relative to the water surface. The depolarization ratio differentiates open water, young clear ice, older granular ice and snow cover. The variability of the ratio along a

  11. Modeling Commercial Turbofan Engine Icing Risk With Ice Crystal Ingestion

    Science.gov (United States)

    Jorgenson, Philip C. E.; Veres, Joseph P.

    2013-01-01

    The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which are ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in

  12. Miniaturized Airborne Imaging Central Server System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is a miniaturized airborne imaging central server system (MAICSS). MAICSS is designed as a high-performance computer-based electronic backend that...

  13. Miniaturized Airborne Imaging Central Server System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is a miniaturized airborne imaging central server system (MAICSS). MAICSS is designed as a high-performance-computer-based electronic backend that...

  14. Airborne Multi-Gas Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mesa Photonics proposes to develop an Airborne Multi-Gas Sensor (AMUGS) based upon two-tone, frequency modulation spectroscopy (TT-FMS). Mesa Photonics has...

  15. Software for airborne radiation monitoring system

    International Nuclear Information System (INIS)

    The Airborne Radiation Monitoring System monitors radioactive contamination in the air or on the ground. The contamination source can be a radioactive plume or an area contaminated with radionuclides. This system is composed of two major parts: Airborne Unit carried by a helicopter, and Ground Station carried by a truck. The Airborne software is intended to be the core of a computerized airborne station. The software is written in C++ under MS-Windows with object-oriented methodology. It has been designed to be user-friendly: function keys and other accelerators are used for vital operations, a help file and help subjects are available, the Human-Machine-Interface is plain and obvious. (authors)

  16. Reconfigurable Weather Radar for Airborne Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Intelligent Automation, Inc (IAI) and its university partner, University of Oklahoma (OU), Norman, propose a forward-looking airborne environment sensor based on...

  17. Voxel inversion of airborne EM data

    DEFF Research Database (Denmark)

    Fiandaca, Gianluca G.; Auken, Esben; Christiansen, Anders Vest C A.V.C.;

    2013-01-01

    jointly inverting airborne and ground-based geophysical data. Furthermore, geological and groundwater models most often refer to a regular voxel grid not correlated to the geophysical model space, and incorporating the geophysical data into the geological/hydrological modelling grids is problematic. We...... of prior information. Inversion of geophysical data usually refers to a model space being linked to the actual observation points. For airborne surveys the spatial discretization of the model space reflects the flight lines. Often airborne surveys are carried out in areas where other ground......-based geophysical data are available. The model space of geophysical inversions is usually referred to the positions of the measurements, and ground-based model positions do not generally coincide with the airborne model positions. Consequently, a model space based on the measuring points is not well suited for...

  18. Regenerable Lunar Airborne Dust Filter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Effective methods are needed to control pervasive Lunar Dust within spacecraft and surface habitations. Once inside, airborne transmission is the primary mode of...

  19. Airborne Infrared Search and Track Systems

    Directory of Open Access Journals (Sweden)

    Hari Babu Srivastava

    2007-09-01

    Full Text Available Infrared search and track (IRST systems are required for fighter aircraft to enable them to passively search, detect, track, classify, and prioritise multiple airborne targets under all aspects, look-up, look-down, and co-altitude conditions and engage them at as long ranges as possible. While the IRST systems have been proven in performance for ground-based and naval-based platforms, it is still facing some technical problems for airborne applications. These problems arise from uncertainty in target signature, atmospheric effects, background clutter (especially dense and varying clouds, signal and data processing algorithms to detect potential targets at long ranges and some hardware limitations such as large memory requirement to store and process wide field of view data. In this paper, an overview of airborne IRST as a system has been presented with detailed comparative simulation results of different detectionitracking algorithms and the present status of airborne IRSTs

  20. Quantifying landscape change in an arctic coastal lowland using repeat airborne LiDAR

    International Nuclear Information System (INIS)

    Increases in air, permafrost, and sea surface temperature, loss of sea ice, the potential for increased wave energy, and higher river discharge may all be interacting to escalate erosion of arctic coastal lowland landscapes. Here we use airborne light detection and ranging (LiDAR) data acquired in 2006 and 2010 to detect landscape change in a 100 km2 study area on the Beaufort Sea coastal plain of northern Alaska. We detected statistically significant change (99% confidence interval), defined as contiguous areas (>10 m2) that had changed in height by at least 0.55 m, in 0.3% of the study region. Erosional features indicative of ice-rich permafrost degradation were associated with ice-bonded coastal, river, and lake bluffs, frost mounds, ice wedges, and thermo-erosional gullies. These features accounted for about half of the area where vertical change was detected. Inferred thermo-denudation and thermo-abrasion of coastal and river bluffs likely accounted for the dominant permafrost-related degradational processes with respect to area (42%) and volume (51%). More than 300 thermokarst pits significantly subsided during the study period, likely as a result of storm surge flooding of low-lying tundra (<1.4 m asl) as well as the lasting impact of warm summers in the late-1980s and mid-1990s. Our results indicate that repeat airborne LiDAR can be used to detect landscape change in arctic coastal lowland regions at large spatial scales over sub-decadal time periods. (letter)

  1. The JAC airborne EM system : AEM-05

    OpenAIRE

    Levaniemi, H.; Beamish, D; Hautaniemi, H.; Kurimo, M.; Suppala, I.; Vironmaki, J.; Cuss, R.J.; Lahti, M; Tartaras, E.

    2009-01-01

    This paper describes the airborne electromagnetic (AEM) system operated by the Joint Airborne geoscience Capability (JAC), a partnership between the Finnish and British Geological Surveys. The system is a component of a 3-in-1, fixed-wing facility acquiring magnetic gradiometer and full spectrum radiometric data alongside the wing-tip, frequency-domain AEM measurements. The AEM system has recently (2005) been upgraded from 2 to 4 frequencies and now provides a bandwidth from 900 Hz to 25 kHz....

  2. Airborne laser swath mapping of the Denton Hills, Transantarctic Mountains, Antarctica: Applications for structural and glacial geomorphic mapping

    Science.gov (United States)

    Wilson, Terry; Csathó, Beata

    2007-01-01

    High-resolution digital elevation data acquired by airborne laser scanning (ALS) for the Denton Hills, along the coastal foothills of the Royal Society Range, Transantarctic Mountains, are examined for applications to bedrock and glacial geomorphic mapping. Digital elevation models (DEMs), displayed as shaded-relief images and slope maps, portray geomorphic landscape features in unprecedented detail across the region. Structures of both ductile and brittle origin, ranging in age from the Paleozoic to the Quaternary, can be mapped from the DEMs. Glacial features, providing a record of the limits of grounded ice, of lake paleoshorelines, and of proglacial lake-ice conveyor deposits, are also prominent on the DEMs. The ALS-derived topographic data have great potential for a range of mapping applications in regions of ice-free terrain in Antarctica

  3. Larsen Ice Shelf, Antarctica

    Science.gov (United States)

    2002-01-01

    Warmer surface temperatures over just a few months in the Antarctic can splinter an ice shelf and prime it for a major collapse, NASA and university scientists report in the latest issue of the Journal of Glaciology. Using satellite images of tell-tale melt water on the ice surface and a sophisticated computer simulation of the motions and forces within an ice shelf, the scientists demonstrated that added pressure from surface water filling crevasses can crack the ice entirely through. The process can be expected to become more widespread if Antarctic summer temperatures increase. This true-color image from Landsat 7, acquired on February 21, 2000, shows pools of melt water on the surface of the Larsen Ice Shelf, and drifting icebergs that have split from the shelf. The upper image is an overview of the shelf's edge, while the lower image is displayed at full resolution of 30 meters (98 feet) per pixel. The labeled pond in the lower image measures roughly 1.6 by 1.6 km (1.0 x 1.0 miles). Full text of Press Release More Images and Animations Image courtesy Landsat 7 Science Team and NASA GSFC

  4. The ICES system

    International Nuclear Information System (INIS)

    ICES is an integrated system used in the various engineering fields. It is made up of the Basic System and the applied Subsystems. ICES is controlled by the Operating System of the computer, from which it calls for suitable services: space allocation, loading of the modules etc... To be able to use software of this type on a computer the Operating System should be made more general. The Subsystems are developed with special programs included in the ICES Basic System. Each Subsystem is associated with an area of application. In other words, a Subsystem can only treat a previously defined ''class of problems''. The engineer (user) communicates with the Subsystem using a language oriented towards the problem (POL) also previously defined using the CDL language. The use of the (POL) language makes the engineer-computer contact much easier. The applied programs written in ICETRAN, once supplied as input to the ICETRAN Precompiler, become Fortran programs with special characteristics. A Fortran compiler produces the corresponding object programs with which, using the ICES ''Link-edit'' procedures, one obtains the modules which can be executed by an ICES Subsystem

  5. IDEOLOGICALLY CHALLENGING ENTERTAINMENT (ICE

    Directory of Open Access Journals (Sweden)

    Dana Lori Chalmers

    2015-09-01

    Full Text Available Ideologically Challenging Entertainment (ICE is entertainment that challenges ‘us vs. them’ ideologies associated with radicalization, violent conflict and terrorism. ICE presents multiple perspectives on a conflict through mainstream entertainment. This article introduces the theoretical underpinnings of ICE, the first ICE production and the audience responses to it. The first ICE production was Two Merchants: The Merchant of Venice adapted to challenge ideologies of the Arab-Israeli Conflict. A mixed-methods study of audience responses explored whether this production inspired audiences to shift their ideological views. Each performance included two versions of the adaptation: a Jewish dominated society with an Arab Muslim minority, contrasted with an Arab Muslim dominated society and a Jewish minority. A mixed-methods study of audience responses explored whether this production inspired audiences to shift their ideological views to become more tolerant of differences away from ideological radicalization. Of audience members who did not initially agree with the premise of the production, 40% reconsidered their ideological views, indicating increased tolerance, greater awareness of and desire to change their own prejudices. In addition, 86% of the audience expressed their intention to discuss the production with others, thereby encouraging critical engagement with, and broader dissemination of the message. These outcomes suggest that high quality entertainment – as defined by audience responses to it - can become a powerful tool in the struggle against radicalised ideologies.

  6. Data archaeology at ICES

    Science.gov (United States)

    Dooley, Harry D.

    1992-01-01

    This paper provides a brief overview of the function of the International Council for the Exploration of the Sea (ICES), both past and present, in particular in the context of its interest in compiling oceanographic data sets. Details are provided of the procedures it adopted to ensure adequate internationally collaborative marine investigations during the first part of the century, such as how it provided a forum for action by its member states, how it coordinated and published the results of scientific programs, and how it provided a foundation, through scientists employed in the ICES Office, for the establishment of the original oceanographic marine databases and associated products, and the scientific interpretation of the results. The growth and expansion of this area of ICES activity is then traced, taking into account the changing conditions for oceanographic data management resulting from the establishment of the National Data Centres, as well as the World Data Centres for Oceanography, which were created to meet the needs of the International Geophysical Year (IGY). Finally, there is a discussion of the way in which the very existence of ICES has proved to be a valuable source of old data, some of which have not yet been digitized, but which can be readily retrieved because they have been very carefully documented throughout the years. Lessons from this activity are noted, and suggestions are made on how the past experiences of ICES can be utilized to ensure the availability of marine data to present and future generations of scientists.

  7. Ice Cores of the National Ice Core Laboratory

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. National Ice Core Laboratory (NICL) is a facility for storing, curating, and studying ice cores recovered from the polar regions of the world. It provides...

  8. Challenges and Opportunities of Airborne Metagenomics

    KAUST Repository

    Behzad, H.

    2015-05-06

    Recent metagenomic studies of environments, such as marine and soil, have significantly enhanced our understanding of the diverse microbial communities living in these habitats and their essential roles in sustaining vast ecosystems. The increase in the number of publications related to soil and marine metagenomics is in sharp contrast to those of air, yet airborne microbes are thought to have significant impacts on many aspects of our lives from their potential roles in atmospheric events such as cloud formation, precipitation, and atmospheric chemistry to their major impact on human health. In this review, we will discuss the current progress in airborne metagenomics, with a special focus on exploring the challenges and opportunities of undertaking such studies. The main challenges of conducting metagenomic studies of airborne microbes are as follows: 1) Low density of microorganisms in the air, 2) efficient retrieval of microorganisms from the air, 3) variability in airborne microbial community composition, 4) the lack of standardized protocols and methodologies, and 5) DNA sequencing and bioinformatics-related challenges. Overcoming these challenges could provide the groundwork for comprehensive analysis of airborne microbes and their potential impact on the atmosphere, global climate, and our health. Metagenomic studies offer a unique opportunity to examine viral and bacterial diversity in the air and monitor their spread locally or across the globe, including threats from pathogenic microorganisms. Airborne metagenomic studies could also lead to discoveries of novel genes and metabolic pathways relevant to meteorological and industrial applications, environmental bioremediation, and biogeochemical cycles.

  9. Airborne infections and modern building technology

    Energy Technology Data Exchange (ETDEWEB)

    LaForce, F.M.

    1986-01-01

    Over the last 30 yr an increased appreciation of the importance of airborne infection has evolved. The concept of droplet nuclei, infectious particles from 0.5 to 3 ..mu.. which stay suspended in air for long periods of time, has been accepted as an important determinant of infectivity. Important airborne pathogens in modern buildings include legionella pneumophila, Aspergillus sp., thermophilic actinomycetes, Mycobacterium tuberculosis, measles, varicella and rubella. Perhaps, the most important microbiologic threat to most buildings is L. pneumophila. This organism can multiply in water cooling systems and contaminate effluent air which can be drawn into a building and efficiently circulated throughout by existing ventilation systems. Hospitals are a special problem because of the concentration of immunosuppressed patients who are uniquely susceptible to airborne diseases such as aspergillosis, and the likelihood that patients ill from diseases that can be spread via the airborne route will be concentrated. Humidifiers are yet another problem and have been shown to be important in several outbreaks of allergic alveolitis and legionellosis. Control of airborne infections is largely an effort at identifying and controlling reservoirs of infection. This includes regular biocide treatment of cooling towers and evaporative condensers and identification and isolation of patients with diseases that may be spread via the airborne route.

  10. Overview of the Airborne Tropical TRopopause EXperiment (ATTREX)

    Science.gov (United States)

    Jensen, Eric

    2015-01-01

    The NASA Airborne Tropical TRopopause EXperiment (ATTREX) is a series of airborne campaigns focused on understanding physical processes in the Tropical Tropopause Layer (TTL) and their role in atmospheric chemistry and climate. ATTREX is using the high-altitude, long-duration NASA Global Hawk Unmanned Air System to make in situ and remote-sensing measurements spanning the Pacific. A particular ATTREX emphasis is to better understand the dehydration of air as it passes through the cold tropical tropopause region. The ATTREX payload contains 12 in situ and remote sensing instruments that measure water vapor, clouds, multiple gaseous tracers (CO, CO2, CH4, NMHC, SF6, CFCs, N2O), reactive chemical compounds (O3, BrO, NO2), meteorological parameters, and radiative fluxes. ATTREX flight series have been conducted in the fall of 2011 from Armstrong Flight Research Center (AFRC) in California, in the winter of 2013 from AFRC, and in the winter/spring of 2014 from Guam. The first two flight series provided extensive sampling of the central and eastern Pacific, whereas the last flight series permitted sampling in the western Pacific. The sampling strategy has primarily involved repeated ascents and descents through the depth of the TTL (about 13-19 km). Over 100 TTL profiles were obtained on each flight series. The ATTREX dataset includes TTL water vapor measurements with unprecedented accuracy, ice crystal size distributions and habits. The cloud and water measurements provide unique information about TTL cloud formation, the persistence of super-saturation with respect to ice, and dehydration. The plethora of tracers measured on the Global Hawk flights are providing unique information about TTL transport pathways and time scales. The meteorological measurements are revealing dynamical phenomena controlling the TTL thermal structure, and the radiation measurements are providing information about heating rates associated with TTL clouds and water vapor. This presentation

  11. The Great Ice Age

    Science.gov (United States)

    Ray, Louis L.

    1992-01-01

    The Great Ice Age, a recent chapter in the Earth's history, was a period of recurring widespread glaciations. During the Pleistocene Epoch of the geologic time scale, which began about a million or more years ago, mountain glaciers formed on all continents, the icecaps of Antarctica and Greenland were more extensive and thicker than today, and vast glaciers, in places as much as several thousand feet thick, spread across northern North America and Eurasia. So extensive were these glaciers that almost a third of the present land surface of the Earth was intermittently covered by ice. Even today remnants of the great glaciers cover almost a tenth of the land, indicating that conditions somewhat similar to those which produced the Great Ice Age are still operating in polar and subpolar climates.

  12. EASE-Grid Sea Ice Age

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides weekly estimates of sea ice age for the Arctic Ocean from remotely sensed sea ice motion and sea ice extent. The ice age data are derived...

  13. Ice-nucleating bacteria control the order and dynamics of interfacial water

    Science.gov (United States)

    Pandey, Ravindra; Usui, Kota; Livingstone, Ruth A.; Fischer, Sean A.; Pfaendtner, Jim; Backus, Ellen H. G.; Nagata, Yuki; Fröhlich-Nowoisky, Janine; Schmüser, Lars; Mauri, Sergio; Scheel, Jan F.; Knopf, Daniel A.; Pöschl, Ulrich; Bonn, Mischa; Weidner, Tobias

    2016-01-01

    Ice-nucleating organisms play important roles in the environment. With their ability to induce ice formation at temperatures just below the ice melting point, bacteria such as Pseudomonas syringae attack plants through frost damage using specialized ice-nucleating proteins. Besides the impact on agriculture and microbial ecology, airborne P. syringae can affect atmospheric glaciation processes, with consequences for cloud evolution, precipitation, and climate. Biogenic ice nucleation is also relevant for artificial snow production and for biomimetic materials for controlled interfacial freezing. We use interface-specific sum frequency generation (SFG) spectroscopy to show that hydrogen bonding at the water-bacteria contact imposes structural ordering on the adjacent water network. Experimental SFG data and molecular dynamics simulations demonstrate that ice-active sites within P. syringae feature unique hydrophilic-hydrophobic patterns to enhance ice nucleation. The freezing transition is further facilitated by the highly effective removal of latent heat from the nucleation site, as apparent from time-resolved SFG spectroscopy. PMID:27152346

  14. Basement Structure and History of Ice Flow of the Recovery Lake Basins

    Science.gov (United States)

    Tinto, K. J.; Langley, K.; Bell, R. E.; Block, A. E.; Sinisalo, A. K.; Wolovick, M.; Das, I.; Abdi, A.; Creyts, T. T.

    2012-12-01

    The Recovery Catchment drains 8% of the East Antarctic ice Sheet. Close to the onset of fast flow, broad regions of relatively flat ice surface have been previously interpreted as a series of four large subglacial lake basins. We give new insights into the basal hydrology and the influence of inferred basal geology on ice dynamics of this area by combining all available ground, airborne and satellite geophysics data for the region. We provide evidence that the flat ice surface is underlain by topographic basins with small (map the small pockets of water also indicates areas of wet sediment throughout much of the Recovery system. Comparison of ice velocities from in-situ GPS stations, radar layer tracking and InSAR indicate a consistent ice flow direction and magnitude over the basins for at least the past 4000 years. The differing basal conditions have a clear influence on the onset of fast flow. Over areas where pockets of basal water was imaged in the radar, InSAR velocities show a clear step increase in ice velocity while areas underlain by wet sediments undergo a gradual velocity increase. Both subglacial topography and basal properties influence the onset of fast flow across the Recovery Basins.

  15. Understanding Europa's Ice Shell and Subsurface Water Through Terestrial Analogs for Flyby Radar Sounding

    Science.gov (United States)

    Blankenship, D. D.; Grima, C.; Young, D. A.; Schroeder, D. M.; Soderlund, K. M.; Gim, Y.; Plaut, J. J.; Patterson, G.; Moussessian, A.

    2015-12-01

    The recently approved NASA mission to Europa proposes to study this ice-covered moon of Jupiter though a series of fly-by observations of its surface and subsurface from a spacecraft in Jovian orbit. The science goal of this mission is to "explore Europa to investigate its habitability". One of the primary instruments in the selected scientific payload is a multi-frequency, multi-channel ice penetrating radar system. The "Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON)" will play a critical role in achieving the mission's habitability driven science objectives, which include characterizing the distribution of any shallow subsurface water, searching for an ice-ocean interface and evaluating a spectrum of ice-ocean-atmosphere exchange hypotheses. The development of successful measurement and data interpretation techniques for exploring Europa will need to leverage knowledge of analogous terrestrial environments and processes. Towards this end, we will discuss a range of terrestrial radioglaciological analogs for hypothesized physical, chemical, and biological processes on Europa and present airborne data collected with the University of Texas dual-frequency radar system over a variety of terrestrial targets. These targets include water filled fractures, brine rich ice, water lenses, accreted marine ice, and ice surfaces with roughness ranging from firn to crevasse fields and will provide context for understanding and optimizing the observable signature of these processes in future radar data collected at Europa.

  16. Spatial complexity of ice flow across the Antarctic Ice Sheet

    Science.gov (United States)

    Ng, Felix S. L.

    2015-11-01

    Fast-flowing ice streams carry ice from the interior of the Antarctic Ice Sheet towards the coast. Understanding how ice-stream tributaries operate and how networks of them evolve is essential for developing reliable models of the ice sheet’s response to climate change. A particular challenge is to unravel the spatial complexity of flow within and across tributary networks. Here I define a measure of planimetric flow convergence, which can be calculated from satellite measurements of the ice sheet’s surface velocity, to explore this complexity. The convergence map of Antarctica clarifies how tributaries draw ice from its interior. The map also reveals curvilinear zones of convergence along lateral shear margins of streaming, and abundant ripples associated with nonlinear ice rheology and changes in bed topography and friction. Convergence on ice-stream tributaries and their feeding zones is uneven and interspersed with divergence. For individual drainage basins, as well as the ice sheet as a whole, fast flow cannot converge or diverge as much as slow flow. I therefore deduce that flow in the ice-stream networks is subject to mechanical regulation that limits flow-orthonormal strain rates. These findings provide targets for ice-sheet simulations and motivate more research into the origin and dynamics of tributarization.

  17. Vacancy Concentration in Ice

    DEFF Research Database (Denmark)

    Mogensen, O. E.; Eldrup, Morten Mostgaard

    1977-01-01

    Based on the diffusion constant for self-diffusion in ice, which is believed to take place by a vacancy mechanism, we estimate the relative vacancy concentration near the melting point to be at least ∼ 10−6, i.e. much higher than previous estimates of about 10−10.......Based on the diffusion constant for self-diffusion in ice, which is believed to take place by a vacancy mechanism, we estimate the relative vacancy concentration near the melting point to be at least ∼ 10−6, i.e. much higher than previous estimates of about 10−10....

  18. ICE Online Detainee Locator System

    Data.gov (United States)

    Department of Homeland Security — The Online Detainee Locator datasets provide the location of a detainee who is currently in ICE custody, or who was release from ICE custody for any reason with the...

  19. Analysis of airborne particulate matter

    International Nuclear Information System (INIS)

    An airborne particulate matter (APM) consists of many kinds of solid and liquid particles in air. APM analysis methods and the application examples are explained on the basis of paper published after 1998. Books and general remarks, sampling and the measurement of concentration and particle distribution, elemental analysis methods and the present state of analysis of species are introduced. Tapered Element Oscillating Microbalance (TEOM) method can collect continuously the integrating mass, but indicates lower concentration. Cu, Ni, Zn, Co, Fe(2), Mn, Cd, Fe(3) and Pb, the water-soluble elements, are determined by ion-chromatography after ultrasonic extraction of the aqueous solution. The detection limit of them is from 10 to 15 ppb (30 ppb Cd and 60 ppb Pb). The elemental carbon (EC) and organic carbon (OC) are separated by the thermal mass measurement-differential scanning calorimeter by means of keeping at 430degC for 60 min. 11 research organizations compared the results of TC (Total Carbon) and EC by NIOSH method 5040 and the thermal method and obtained agreement of TC. ICP-MS has been developed in order to determine correctly and quickly the trace elements. The determination methods for distinction of chemical forms in the environment were developed. GC/MS, LC/MS and related technologies for determination of organic substances are advanced. Online real-time analysis of APN, an ideal method, is examined. (S.Y.)

  20. Analysis of the Effect of Radio Frequency Interference on Repeat Track Airborne InSAR System

    Directory of Open Access Journals (Sweden)

    Ding Bin

    2012-03-01

    Full Text Available The SAR system operating at low frequency is susceptible to Radio Frequency Interference (RFI from television station, radio station, and some other civil electronic facilities. The presence of RFI degrades the SAR image quality, and obscures the targets in the scene. Furthermore, RFI can cause interferometric phase error in repeat track InSAR system. In order to analyze the effect of RFI on interferometric phase of InSAR, real measured RFI signal are added on cone simulated SAR echoes. The imaging and interferometric processing results of both the RFI-contaminated and raw data are given. The effect of real measured RFI signal on repeat track InSAR system is analyzed. Finally, the imaging and interferometric processing results of both with and without RFI suppressed of the P band airborne repeat track InSAR real data are presented, which demonstrates the efficiency of the RFI suppression method in terms of decreasing the interferometric phase errors caused by RFI.

  1. Ice crystal ingestion by turbofans

    Science.gov (United States)

    Rios Pabon, Manuel A.

    This Thesis will present the problem of inflight icing in general and inflight icing caused by the ingestion of high altitude ice crystals produced by high energy mesoscale convective complexes in particular, and propose a new device to prevent it based on dielectric barrier discharge plasma. Inflight icing is known to be the cause of 583 air accidents and more than 800 deaths in more than a decade. The new ice crystal ingestion problem has caused more than 100 flights to lose engine power since the 1990's, and the NTSB identified it as one of the causes of the Air France flight 447 accident in 1-Jun2008. The mechanics of inflight icing not caused by ice crystals are well established. Aircraft surfaces exposed to supercooled liquid water droplets will accrete ice in direct proportion of the droplet catch and the freezing heat transfer process. The multiphase flow droplet catch is predicted by the simple sum of forces on each spherical droplet and a droplet trajectory calculation based on Lagrangian or Eulerian analysis. The most widely used freezing heat transfer model for inflight icing caused by supercooled droplets was established by Messinger. Several computer programs implement these analytical models to predict inflight icing, with LEWICE being based on Lagrangian analysis and FENSAP being based on Eulerian analysis as the best representatives among them. This Thesis presents the multiphase fluid mechanics particular to ice crystals, and explains how it differs from the established droplet multiphase flow, and the obstacles in implementing the former in computational analysis. A new modification of the Messinger thermal model is proposed to account for ice accretion produced by ice crystal impingement. Because there exist no computational and experimental ways to fully replicate ice crystal inflight icing, and because existing ice protections systems consume vast amounts of energy, a new ice protection device based on dielectric barrier discharge plasma is

  2. Greenland Ice Sheet Retreat Since the Little Ice Age

    OpenAIRE

    Beitch, Marci Jillian

    2014-01-01

    Late 20th century and 21st century satellite imagery of the perimeter of the Greenland Ice Sheet (GrIS) provide high resolution observations of the ice sheet margins. Examining changes in ice margin positions over time yield measurements of GrIS area change and rates of margin retreat. However, longer records of ice sheet margin change are needed to establish more accurate predictions of the ice sheet's future response to global conditions. In this study, the trimzone, the area of deglaciated...

  3. The little ice age

    Energy Technology Data Exchange (ETDEWEB)

    Grove, J.M.

    1988-01-01

    The Little Ice Age, a period of glacier expansion in alpine regions that began sometime between the twelfth and sixteenth centuries and lasted until late in the nineteenth century, was recorded not only in glacial features dated by geologic techniques but also in historical documents such as field sketches, land values, and weather records, especially in the Alps. Indirect evidence of its impact in other parts of the world includes the records of sea-ice extent near Iceland and Greenland, the fate of the Viking settlements in Greenland, and many other suggestions that the climate was colder in the recent past than it is today. Jean Grove's book is an authoritative, superbly documented, and excellently written summary of the abundant evidence of climatic change during the last few centuries in the context of broader climatic variations of the last 10,000 years. This summary provides a much-needed perspective for considering the magnitude and frequency of natural climatic variations in the past, given predictions for the future. In the final chapter, Grove notes that natural climatic variations, including another minor ice age, might be expected in the future but at the end of the Little Ice Age coincided with the increased burning of fossil fuels during the industralization of Europe and North America. This coincidence does indeed suggest that modern scientists already have had a significant impact on the global climate.

  4. Melting ice, growing trade?

    Directory of Open Access Journals (Sweden)

    Sami Bensassi

    2016-05-01

    Full Text Available Abstract Large reductions in Arctic sea ice, most notably in summer, coupled with growing interest in Arctic shipping and resource exploitation have renewed interest in the economic potential of the Northern Sea Route (NSR. Two key constraints on the future viability of the NSR pertain to bathymetry and the future evolution of the sea ice cover. Climate model projections of future sea ice conditions throughout the rest of the century suggest that even under the most “aggressive” emission scenario, increases in international trade between Europe and Asia will be very low. The large inter-annual variability of weather and sea ice conditions in the route, the Russian toll imposed for transiting the NSR, together with high insurance costs and scarce loading/unloading opportunities, limit the use of the NSR. We show that even if these obstacles are removed, the duration of the opening of the NSR over the course of the century is not long enough to offer a consequent boost to international trade at the macroeconomic level.

  5. Ice stadium in Prague

    Czech Academy of Sciences Publication Activity Database

    Svobodová, Markéta

    Prague: Prostor - architektura, interiér, design, 2012 - (Švácha, R.), s. 150-153 ISBN 978-80-87064-09-2 Institutional support: RVO:68378033 Keywords : ice stadium * Josef Fuchs * Bohumil Steigenhöfer Subject RIV: AL - Art, Architecture, Cultural Heritage

  6. Exploring Liquid Water Beneath Glaciers and Permafrost in Antarctica Through Airborne Electromagnetic Surveys

    Science.gov (United States)

    Auken, E.; Tulaczyk, S. M.; Foley, N.; Dugan, H.; Schamper, C.; Peter, D.; Virginia, R. A.; Sørensen, K.

    2015-12-01

    Here, we demonstrate how high powered airborne electromagnetic resistivity is efficiently used to map 3D domains of unfrozen water below glaciers and permafrost in the cold regions of the Earth. Exploration in these parts of the world has typically been conducted using radar methods, either ground-based or from an airborne platform. Radar is an excellent method if the penetrated material has a low electrical conductivity, but in materials with higher conductivity, such as sediments with liquid water, the energy is attenuated . Such cases are efficiently explored with electromagnetic methods, which attenuate less quickly in conductive media and can therefore 'see through' conductors and return valuable information about their electrical properties. In 2011, we used a helicopter-borne, time-domain electromagnetic sensor to map resistivity in the subsurface across the McMurdo Dry Valleys (MDV). The MDV are a polar desert in coastal Antarctica where glaciers, permafrost, ice-covered lakes, and ephemeral summer streams coexist. In polar environments, this airborne electromagnetic system excels at finding subsurface liquid water, as water which remains liquid under cold conditions must be sufficiently saline, and therefore electrically conductive. In Taylor Valley, in the MDV, our data show extensive subsurface low resistivity layers beneath higher resistivity layers, which we interpret as cryoconcentrated hypersaline brines lying beneath glaciers and frozen permafrost. These brines appear to be contiguous with surface lakes, subglacial regions, and the Ross Sea, which could indicate a regional hydrogeologic system wherein solutes may be transported between surface reservoirs by ionic diffusion and subsurface flow. The system as of 2011 had a maximum exploration depth of about 300 m. However, newer and more powerful airborne systems can explore to a depth of 500 - 600 m and new ground based instruments will get to 1000 m. This is sufficient to penetrate to the base of

  7. A new regional high-resolution map of basal and surface topography for the Greenland ice-sheet margin at Paakitsoq, West Greenland

    OpenAIRE

    Mottram, R.; Nielsen, C.; Ahlstrøm, A. P.; Reeh, N.; Kristensen, Steen Savstrup; Christensen, Erik Lintz; Forsberg, René; Stenseng, Lars

    2009-01-01

    In 2005 an airborne survey was carried out from a Twin Otter aircraft at Pâkitsup Akuliarusersua (Paakitsoq) near Ilulissat in West Greenland. The survey aimed to measure ice thickness with a 60 MHz cohrent radar and surface elevation with a scanning laser altimeter.

  8. Mapping permafrost with airborne electromagnetics

    Science.gov (United States)

    Minsley, B. J.; Ball, L. B.; Bloss, B. R.; Kass, A.; Pastick, N.; Smith, B. D.; Voss, C. I.; Walsh, D. O.; Walvoord, M. A.; Wylie, B. K.

    2014-12-01

    Permafrost is a key characteristic of cold region landscapes, yet detailed assessments of how the subsurface distribution of permafrost impacts the environment, hydrologic systems, and infrastructure are lacking. Data acquired from several airborne electromagnetic (AEM) surveys in Alaska provide significant new insight into the spatial extent of permafrost over larger areas (hundreds to thousands of square kilometers) than can be mapped using ground-based geophysical methods or through drilling. We compare several AEM datasets from different areas of interior Alaska, and explore the capacity of these data to infer geologic structure, permafrost extent, and related hydrologic processes. We also assess the impact of fires on permafrost by comparing data from different burn years within similar geological environments. Ultimately, interpretations rely on understanding the relationship between electrical resistivity measured by AEM surveys and the physical properties of interest such as geology, permafrost, and unfrozen water content in the subsurface. These relationships are often ambiguous and non-unique, so additional information is useful for reducing uncertainty. Shallow (upper ~1m) permafrost and soil characteristics identified from remotely sensed imagery and field observations help to constrain and aerially extend near-surface AEM interpretations, where correlations between the AEM and remote sensing data are identified using empirical multivariate analyses. Surface nuclear magnetic resonance (sNMR) measurements quantify the contribution of unfrozen water at depth to the AEM-derived electrical resistivity models at several locations within one survey area. AEM surveys fill a critical data gap in the subsurface characterization of permafrost environments and will be valuable in future mapping and monitoring programs in cold regions.

  9. THE SPITZER ICE LEGACY: ICE EVOLUTION FROM CORES TO PROTOSTARS

    International Nuclear Information System (INIS)

    Ices regulate much of the chemistry during star formation and account for up to 80% of the available oxygen and carbon. In this paper, we use the Spitzer c2d Legacy ice survey, complimented with data sets on ices in cloud cores and high-mass protostars, to determine standard ice abundances and to present a coherent picture of the evolution of ices during low- and high-mass star formation. The median ice composition H2O:CO:CO2:CH3OH:NH3:CH4:XCN is 100:29:29:3:5:5:0.3 and 100:13:13:4:5:2:0.6 toward low- and high-mass protostars, respectively, and 100:31:38:4:-:-:- in cloud cores. In the low-mass sample, the ice abundances with respect to H2O of CH4, NH3, and the component of CO2 mixed with H2O typically vary by 2O. In contrast, some CO and CO2 ice components, XCN, and CH3OH vary by factors 2-10 between the lower and upper quartile. The XCN band correlates with CO, consistent with its OCN- identification. The origin(s) of the different levels of ice abundance variations are constrained by comparing ice inventories toward different types of protostars and background stars, through ice mapping, analysis of cloud-to-cloud variations, and ice (anti-)correlations. Based on the analysis, the first ice formation phase is driven by hydrogenation of atoms, which results in an H2O-dominated ice. At later prestellar times, CO freezes out and variations in CO freezeout levels and the subsequent CO-based chemistry can explain most of the observed ice abundance variations. The last important ice evolution stage is thermal and UV processing around protostars, resulting in CO desorption, ice segregation, and the formation of complex organic molecules. The distribution of cometary ice abundances is consistent with the idea that most cometary ices have a protostellar origin.

  10. Airborne laser communication technology and flight test

    Science.gov (United States)

    Meng, Li-xin; Zhang, Li-zhong; Li, Xiao-ming; Li, Ying-chao; Jiang, Hui-lin

    2015-11-01

    Reconnaissance aircraft is an important node of the space-air-ground integrated information network, on which equipped with a large number of high-resolution surveillance equipment, and need high speed communications equipment to transmit detected information in real time. Currently RF communication methods cannot meet the needs of communication bandwidth. Wireless laser communication has outstanding advantages high speed, high capacity, security, etc., is an important means to solve the high-speed information transmission of airborne platforms. In this paper, detailed analysis of how the system works, the system components, work processes, link power and the key technologies of airborne laser communication were discussed. On this basis, a prototype airborne laser communications was developed, and high-speed, long-distance communications tests were carried out between the two fixed-wing aircraft, and the airborne precision aiming, atmospheric laser communication impacts on laser communication were tested. The experiments ultimately realize that, the communication distance is 144km, the communication rate is 2.5Gbps. The Airborne laser communication experiments provide technical basis for the application of the conversion equipment.

  11. Active airborne contamination control using electrophoresis

    International Nuclear Information System (INIS)

    In spite of our best efforts, radioactive airborne contamination continues to be a formidable problem at many of the Department of Energy (DOE) weapons complex sites. For workers that must enter areas with high levels of airborne contamination, personnel protective equipment (PPE) can become highly restrictive, greatly diminishing productivity. Rather than require even more restrictive PPE for personnel in some situations, the Rocky Flats Plant (RFP) is actively researching and developing methods to aggressively combat airborne contamination hazards using electrophoretic technology. With appropriate equipment, airborne particulates can be effectively removed and collected for disposal in one simple process. The equipment needed to implement electrophoresis is relatively inexpensive, highly reliable, and very compact. Once airborne contamination levels are reduced, less PPE is required and a significant cost savings may be realized through decreased waste and maximized productivity. Preliminary ''cold,'' or non-radioactive, testing results at the RFP have shown the technology to be effective on a reasonable scale, with several potential benefits and an abundance of applications

  12. Modelling the Antarctic Ice Sheet

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Holm, A.

    2015-01-01

    Science) Antarctic Ice Sheet (DAIS) model (Shaffer 2014) is forced by reconstructed time series of Antarctic temperature, global sea level and ocean subsurface temperature over the last two glacial cycles. In this talk a modelling work of the Antarctic ice sheet over most of the Cenozoic era using the......The Antarctic ice sheet is a major player in the Earth’s climate system and is by far the largest depository of fresh water on the planet. Ice stored in the Antarctic ice sheet (AIS) contains enough water to raise sea level by about 58 m, and ice loss from Antarctica contributed significantly to...... DAIS model will be presented. G. Shaffer (2014) Formulation, calibration and validation of the DAIS model (version 1), a simple Antarctic ice sheet model sensitive to variations of sea level and ocean subsurface temperature, Geosci. Model Dev., 7, 1803‐1818...

  13. Airborne radioactivity surveys in geologic exploration

    Science.gov (United States)

    Moxham, R.M.

    1958-01-01

    The value of airborne radioactivity surveys in guiding uranium exploration has been well established. Recent improvements in circuitry and development of semiquantitative analytical techniques permit a more comprehensive evaluation of the geologic distribution of radioactive materials that may prove useful in exploration for other minerals and in regional geologic studies. It is shown that placer deposits of heavy minerals can be detected from the air, and that the geometric configuration and average grade of the surficial part of the deposit can be approximated. Uranium-bearing phosphorite deposits may be similarly evaluated. Airborne surveys over the Coastal Plain area, Texas, show that

  14. Sandia Multispectral Airborne Lidar for UAV Deployment

    Energy Technology Data Exchange (ETDEWEB)

    Daniels, J.W.; Hargis,Jr. P.J.; Henson, T.D.; Jordan, J.D.; Lang, A.R.; Schmitt, R.L.

    1998-10-23

    Sandia National Laboratories has initiated the development of an airborne system for W laser remote sensing measurements. System applications include the detection of effluents associated with the proliferation of weapons of mass destruction and the detection of biological weapon aerosols. This paper discusses the status of the conceptual design development and plans for both the airborne payload (pointing and tracking, laser transmitter, and telescope receiver) and the Altus unmanned aerospace vehicle platform. Hardware design constraints necessary to maintain system weight, power, and volume limitations of the flight platform are identified.

  15. Attenuation of airborne debris from LMFBR accidents

    International Nuclear Information System (INIS)

    Experimental and theoretical studies have been performed to characterize the behavior of airborne particulates (aerosols) expected to be produced by hypothetical core disassembly accidents (HCDA's) in liquid metal fast breeder reactors (LMFBR's). These aerosol studies include work on aerosol transport in a 20-m high, 850-m3 closed vessel at moderate concentrations; aerosol transport in a small vessel under conditions of high concentration (approx. 1000 g/m3), high turbulence, and high temperature (approx. 20000C); and aerosol transport through various leak paths. These studies have shown that little, if any, airborne debris from LMFBR HCDA's would reach the atmosphere exterior to an intact reactor containment building

  16. Modelling airborne dispersion of coarse particulate material

    International Nuclear Information System (INIS)

    Methods of modelling the airborne dispersion and deposition of coarse particulates are presented, with the emphasis on the heavy particles identified as possible constituents of releases from damaged AGR fuel. The first part of this report establishes the physical characteristics of the irradiated particulate in airborne emissions from AGR stations. The second part is less specific and describes procedures for extending current dispersion/deposition models to incorporate a coarse particulate component: the adjustment to plume spread parameters, dispersion from elevated sources and dispersion in conjunction with building effects and plume rise. (author)

  17. Attenuation of airborne debris from LMFBR accidents

    International Nuclear Information System (INIS)

    Experimental and theoretical studies have been performed to characterize the behavior of airborne particulates (aerosols) expected to be produced by hypothetical core disassembly accidents (HCDA's) in liquid metal fast breeder reactors (LMFBR's). These aerosol studies include work on aerosol transport in a 20-m high, 850-m3 closed vessel at moderate concentrations; aerosol transport in a small vessel under conditions of high concentration (approximately 1,000 g/m3), high turbulence, and high temperature (approximately 20000C); and aerosol transport through various leak paths. These studies have shown that tittle, if any, airborne debris from LMFBR HCDA's would reach the atmosphere exterior to an intact reactor containment building. (author)

  18. Optimal site selection for a high-resolution ice core record in East Antarctica

    Science.gov (United States)

    Vance, Tessa R.; Roberts, Jason L.; Moy, Andrew D.; Curran, Mark A. J.; Tozer, Carly R.; Gallant, Ailie J. E.; Abram, Nerilie J.; van Ommen, Tas D.; Young, Duncan A.; Grima, Cyril; Blankenship, Don D.; Siegert, Martin J.

    2016-03-01

    Ice cores provide some of the best-dated and most comprehensive proxy records, as they yield a vast and growing array of proxy indicators. Selecting a site for ice core drilling is nonetheless challenging, as the assessment of potential new sites needs to consider a variety of factors. Here, we demonstrate a systematic approach to site selection for a new East Antarctic high-resolution ice core record. Specifically, seven criteria are considered: (1) 2000-year-old ice at 300 m depth; (2) above 1000 m elevation; (3) a minimum accumulation rate of 250 mm years-1 IE (ice equivalent); (4) minimal surface reworking to preserve the deposited climate signal; (5) a site with minimal displacement or elevation change in ice at 300 m depth; (6) a strong teleconnection to midlatitude climate; and (7) an appropriately complementary relationship to the existing Law Dome record (a high-resolution record in East Antarctica). Once assessment of these physical characteristics identified promising regions, logistical considerations (for site access and ice core retrieval) were briefly considered. We use Antarctic surface mass balance syntheses, along with ground-truthing of satellite data by airborne radar surveys to produce all-of-Antarctica maps of surface roughness, age at specified depth, elevation and displacement change, and surface air temperature correlations to pinpoint promising locations. We also use the European Centre for Medium-Range Weather Forecast ERA 20th Century reanalysis (ERA-20C) to ensure that a site complementary to the Law Dome record is selected. We find three promising sites in the Indian Ocean sector of East Antarctica in the coastal zone from Enderby Land to the Ingrid Christensen Coast (50-100° E). Although we focus on East Antarctica for a new ice core site, the methodology is more generally applicable, and we include key parameters for all of Antarctica which may be useful for ice core site selection elsewhere and/or for other purposes.

  19. Cloud chamber experiments on the origin of ice crystal complexity in cirrus clouds

    Science.gov (United States)

    Schnaiter, Martin; Järvinen, Emma; Vochezer, Paul; Abdelmonem, Ahmed; Wagner, Robert; Jourdan, Olivier; Mioche, Guillaume; Shcherbakov, Valery N.; Schmitt, Carl G.; Tricoli, Ugo; Ulanowski, Zbigniew; Heymsfield, Andrew J.

    2016-04-01

    This study reports on the origin of small-scale ice crystal complexity and its influence on the angular light scattering properties of cirrus clouds. Cloud simulation experiments were conducted at the AIDA (Aerosol Interactions and Dynamics in the Atmosphere) cloud chamber of the Karlsruhe Institute of Technology (KIT). A new experimental procedure was applied to grow and sublimate ice particles at defined super- and subsaturated ice conditions and for temperatures in the -40 to -60 °C range. The experiments were performed for ice clouds generated via homogeneous and heterogeneous initial nucleation. Small-scale ice crystal complexity was deduced from measurements of spatially resolved single particle light scattering patterns by the latest version of the Small Ice Detector (SID-3). It was found that a high crystal complexity dominates the microphysics of the simulated clouds and the degree of this complexity is dependent on the available water vapor during the crystal growth. Indications were found that the small-scale crystal complexity is influenced by unfrozen H2SO4 / H2O residuals in the case of homogeneous initial ice nucleation. Angular light scattering functions of the simulated ice clouds were measured by the two currently available airborne polar nephelometers: the polar nephelometer (PN) probe of Laboratoire de Métérologie et Physique (LaMP) and the Particle Habit Imaging and Polar Scattering (PHIPS-HALO) probe of KIT. The measured scattering functions are featureless and flat in the side and backward scattering directions. It was found that these functions have a rather low sensitivity to the small-scale crystal complexity for ice clouds that were grown under typical atmospheric conditions. These results have implications for the microphysical properties of cirrus clouds and for the radiative transfer through these clouds.

  20. Oceanographic conditions beneath Fimbul Ice Shelf, Antarctica

    OpenAIRE

    Abrahamsen, Einar Povl

    2012-01-01

    Antarctic ice shelves play a key role in the global climate system, acting as important sites for the cooling of shelf waters, thereby facilitating deep and bottom water formation. Many of the processes that take place under large ice shelves can be observed more conveniently beneath smaller ice shelves such as Fimbul Ice Shelf, an ice shelf in the eastern Weddell Sea. Fimbul Ice Shelf and nearby ice shelves might also play a significant regional role: although no bottom water is produced in ...

  1. Recent Observations of Increased Thinning of the Greenland Ice Sheet Measured by Aircraft GPS and Laser Altimetry

    Science.gov (United States)

    Krabill, William B.

    2004-01-01

    The Arctic Ice Mapping group (Project AIM) at the NASA Goddard Space Flight Center Wallops Flight Facility has been conducting systematic topographic surveys of the Greenland Ice Sheet (GIs) since 1993, using scanning airborne laser altimeters combined with Global Positioning System (GPS) technology onboard NASA's P-3 aircraft. Flight lines have covered all major ice drainage basins, with repeating surveys after a 5-year interval during the decade of the 90's. Analysis of this data documented significant thinning in many areas near the ice sheet margins and an overall negative mass balance of the GIS (Science, 2000). In 2001, 2002, and 2003 many of these flight lines were re-surveyed, providing evidence of continued or accelerated thinning in all observed areas around the margin of the GIs. Additionally, however, a highly-anomalous snowfall was observed between 2002 and 2003 in SE Greenland - perhaps an indicator of a shift in the regional climate?

  2. IceCube

    International Nuclear Information System (INIS)

    Neutrino astronomy beyond the Sun was first imagined in the late 1950s; by the 1970s, it was realized that kilometer-scale neutrino detectors were required. The first such instrument, IceCube, is near completion and taking data. Its scientific missions include the observation of Galactic supernova explosions, the search for dark matter, and the study of the neutrinos themselves. These reach energies more than two orders of magnitude beyond those produced by accelerator beams. In these lectures, we will focus on IceCube's most publicized mission, the search for the sources of cosmic rays. We will conclude with an overview of the first results obtained with the partially completed detector.These lectures are based on a review paper co-authored with Spencer Klein (arXiv:astroph.HE/1007.1247) to be published in Review of Scientific Instruments.

  3. 76 FR 76333 - Notification for Airborne Wind Energy Systems (AWES)

    Science.gov (United States)

    2011-12-07

    ... Federal Aviation Administration 14 CFR Part 77 Notification for Airborne Wind Energy Systems (AWES) AGENCY...,'' to airborne wind energy systems (AWES). In addition, this notice requests information from airborne wind energy system developers and the public related to these systems so that the FAA...

  4. 14 CFR 135.175 - Airborne weather radar equipment requirements.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a... conditions that can be detected with airborne weather radar equipment, may reasonably be expected along...

  5. 14 CFR 125.223 - Airborne weather radar equipment requirements.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airborne weather radar equipment... Equipment Requirements § 125.223 Airborne weather radar equipment requirements. (a) No person may operate an airplane governed by this part in passenger-carrying operations unless approved airborne weather...

  6. 14 CFR 121.357 - Airborne weather radar equipment requirements.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airborne weather radar equipment... § 121.357 Airborne weather radar equipment requirements. (a) No person may operate any transport... December 31, 1964, unless approved airborne weather radar equipment has been installed in the airplane....

  7. Radar and infrared remote sensing of terrain, water resources, arctic sea ice, and agriculture

    Science.gov (United States)

    Biggs, A. W.

    1983-01-01

    Radar range measurements, basic waveforms of radar systems, and radar displays are initially described. These are followed by backscatter from several types of terrain and vegetation as a function of frequency and grazing angle. Analytical models for this backscatter include the facet models of radar return, with range-angle, velocity-range, velocity-angle, range, velocity, and angular only discriminations. Several side-looking airborne radar geometries are presented. Radar images of Arctic sea ice, fresh water lake ice, cloud-covered terrain, and related areas are presented to identify applications of radar imagery. Volume scatter models are applied to radar imagery from alpine snowfields. Short pulse ice thickness radar for subsurface probes is discussed in fresh-water ice and sea ice detection. Infrared scanners, including multispectral, are described. Diffusion of cold water into a river, Arctic sea ice, power plant discharges, volcanic heat, and related areas are presented in thermal imagery. Multispectral radar and infrared imagery are discussed, with comparisons of photographic, infrared, and radar imagery of the same terrain or subjects.

  8. ICE SLURRY APPLICATIONS

    OpenAIRE

    Kauffeld, M.; Wang, M.J.; Goldstein, V.; Kasza, K.E.

    2010-01-01

    The role of secondary refrigerants is expected to grow as the focus on the reduction of greenhouse gas emissions increases. The effectiveness of secondary refrigerants can be improved when phase changing media are introduced in place of single phase media. Operating at temperatures below the freezing point of water, ice slurry facilitates several efficiency improvements such as reductions in pumping energy consumption as well as lowering the required temperature difference in heat exchangers ...

  9. The Joy of Ice

    Science.gov (United States)

    MacAyeal, D. R.

    2013-12-01

    The effectiveness of cryospheric science in addressing its main purpose (predicting and assessing response to climate change) is powerfully, but intangibly enhanced by the mysterious nature and the remote locations of ice and snow phenomena. Study of the cryosphere, in essence, depends as much on the universal human desire to satisfy curiosity as it does on the fact that cryospheric science informs humanity about the consequences of the environmental changes now clearly visible in all realms of the cryosphere. In my presentation, I shall consider the study of ice-shelf dynamics and stability, and shall draw on the perspective of my 37 years of involvement in this small, but important corner of glaciology, to show where curiosity has, and continues to be, a major driver of understanding. Joyful moments within the development of ice-shelf glaciology include examples where complete misunderstandings and blind alleys have ironically led to unexpected insight into how related phenomena operate, including: the flow of ice streams, the role of sticky spots, styles and drivers of iceberg calving, tidewater glacier terminus behavior, the source mechanisms and interpretations of cryospheric related seismic signals, and the dynamics of iceberg-drift-steering ocean circulation in basins separated by mid-ocean ridges. The familiar joke, "Why did the man who lost his keys on a dark night only search underneath the streetlamp?", is apt for cryospheric science--but with a perverse twist: We cryospheric scientists are more akin to the man who is driven to also grope for the key in the darkness because of the chance that in addition to the key, the car that the key will start might also be found somewhere beyond the glow of the streetlamp.

  10. Ice Giant Exploration

    Science.gov (United States)

    Rymer, A. M.; Arridge, C. S.; Masters, A.; Turtle, E. P.; Simon, A. A.; Hofstadter, M. D.; Turrini, D.; Politi, R.

    2015-12-01

    The Ice Giants in our solar system, Uranus and Neptune, are fundamentally different from their Gas Giant siblings Jupiter and Saturn, from the different proportions of rock and ice to the configuration of their planetary magnetic fields. Kepler space telescope discoveries of exo-planets indicate that planets of this type are among the most ubiquitous universally and therefore a future mission to explore the nature of the Ice Giants in our own solar system will provide insights into the nature of extra-solar system objects in general. Uranus has the smallest self- luminosity of all the planets, potentially related to catastrophic events early in the planet's history, which also may explain Uranus' large obliquity. Uranus' atmosphere is subject to extreme seasonal forcing making it unique in the Solar System. Neptune is also unique in a number of ways, notably its large moon Triton which is likely a captured Kuiper Belt Object and one of only two moons in the solar system with a robustly collisional atmosphere. Similar to Uranus, the angle between the solar wind and the magnetic dipole axis is subject to large-amplitude variations on both diurnal and seasonal timescales, but peculiarly it has one of the quietest magnetospheres of the solar system, at least according to Voyager 2, the only spacecraft to encounter Neptune to date. A comprehensive mission, as advocated in the Decadal Survey, would provide enormous science return but is also challenging and expensive. In this presentation we will discuss mission scenarios and suggest how collaboration between disciplines and internationally can help us to pursue a mission that includes Ice Giant exploration.

  11. Mars Ice Age, Simulated

    Science.gov (United States)

    2003-01-01

    December 17, 2003This simulated view shows Mars as it might have appeared during the height of a possible ice age in geologically recent time.Of all Solar System planets, Mars has the climate most like that of Earth. Both are sensitive to small changes in orbit and tilt. During a period about 2.1 million to 400,000 years ago, increased tilt of Mars' rotational axis caused increased solar heating at the poles. A new study using observations from NASA's Mars Global Surveyor and Mars Odyssey orbiters concludes that this polar warming caused mobilization of water vapor and dust into the atmosphere, and buildup of a surface deposit of ice and dust down to about 30 degrees latitude in both hemispheres. That is the equivalent of the southern Unites States or Saudi Arabia on Earth. Mars has been in an interglacial period characterized by less axial tilt for about the last 300,000 years. The ice-rich surface deposit has been degrading in the latitude zone of 30 degrees to 60 degrees as water-ice returns to the poles.In this illustration prepared for the December 18, 2003, cover of the journal Nature, the simulated surface deposit is superposed on a topography map based on altitude measurements by Global Surveyor and images from NASA's Viking orbiters of the 1970s.Mars Global Surveyor and Mars Odyssey are managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, for the NASA Office of Space Science, Washington.

  12. PHIPS-HALO: the airborne Particle Habit Imaging and Polar Scattering probe - Part 1: Design and operation

    Science.gov (United States)

    Abdelmonem, Ahmed; Järvinen, Emma; Duft, Denis; Hirst, Edwin; Vogt, Steffen; Leisner, Thomas; Schnaiter, Martin

    2016-07-01

    The number and shape of ice crystals present in mixed-phase and ice clouds influence the radiation properties, precipitation occurrence and lifetime of these clouds. Since clouds play a major role in the climate system, influencing the energy budget by scattering sunlight and absorbing heat radiation from the earth, it is necessary to investigate the optical and microphysical properties of cloud particles particularly in situ. The relationship between the microphysics and the single scattering properties of cloud particles is usually obtained by modelling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. There is a demand to obtain both information correspondently and simultaneously for individual cloud particles in their natural environment. For evaluating the average scattering phase function as a function of ice particle habit and crystal complexity, in situ measurements are required. To this end we have developed a novel airborne optical sensor (PHIPS-HALO) to measure the optical properties and the corresponding microphysical parameters of individual cloud particles simultaneously. PHIPS-HALO has been tested in the AIDA cloud simulation chamber and deployed in mountain stations as well as research aircraft (HALO and Polar 6). It is a successive version of the laboratory prototype instrument PHIPS-AIDA. In this paper we present the detailed design of PHIPS-HALO, including the detection mechanism, optical design, mechanical construction and aerodynamic characterization.

  13. Subsonic Aircraft Safety Icing Study

    Science.gov (United States)

    Jones, Sharon Monica; Reveley, Mary S.; Evans, Joni K.; Barrientos, Francesca A.

    2008-01-01

    NASA's Integrated Resilient Aircraft Control (IRAC) Project is one of four projects within the agency s Aviation Safety Program (AvSafe) in the Aeronautics Research Mission Directorate (ARMD). The IRAC Project, which was redesigned in the first half of 2007, conducts research to advance the state of the art in aircraft control design tools and techniques. A "Key Decision Point" was established for fiscal year 2007 with the following expected outcomes: document the most currently available statistical/prognostic data associated with icing for subsonic transport, summarize reports by subject matter experts in icing research on current knowledge of icing effects on control parameters and establish future requirements for icing research for subsonic transports including the appropriate alignment. This study contains: (1) statistical analyses of accident and incident data conducted by NASA researchers for this "Key Decision Point", (2) an examination of icing in other recent statistically based studies, (3) a summary of aviation safety priority lists that have been developed by various subject-matter experts, including the significance of aircraft icing research in these lists and (4) suggested future requirements for NASA icing research. The review of several studies by subject-matter experts was summarized into four high-priority icing research areas. Based on the Integrated Resilient Aircraft Control (IRAC) Project goals and objectives, the IRAC project was encouraged to conduct work in all of the high-priority icing research areas that were identified, with the exception of the developing of methods to sense and document actual icing conditions.

  14. The Spitzer ice legacy: Ice evolution from cores to protostars

    CERN Document Server

    Oberg, Karin I; Pontoppidan, Klaus M; Broek, Saskia van den; van Dishoeck, Ewine F; Bottinelli, Sandrine; Blake, Geoffrey A; Evans, Neal J

    2011-01-01

    Ices regulate much of the chemistry during star formation and account for up to 80% of the available oxygen and carbon. In this paper, we use the Spitzer c2d ice survey, complimented with data sets on ices in cloud cores and high-mass protostars, to determine standard ice abundances and to present a coherent picture of the evolution of ices during low- and high-mass star formation. The median ice composition H2O:CO:CO2:CH3OH:NH3:CH4:XCN is 100:29:29:3:5:5:0.3 and 100:13:13:4:5:2:0.6 toward low- and high-mass protostars, respectively, and 100:31:38:4:-:-:- in cloud cores. In the low-mass sample, the ice abundances with respect to H2O of CH4, NH3, and the component of CO2 mixed with H2O typically vary by <25%, indicative of co-formation with H2O. In contrast, some CO and CO2 ice components, XCN and CH3OH vary by factors 2-10 between the lower and upper quartile. The XCN band correlates with CO, consistent with its OCN- identification. The origin(s) of the different levels of ice abundance variations are cons...

  15. IceCube systematic errors investigation: Simulation of the ice

    International Nuclear Information System (INIS)

    IceCube is a neutrino observatory for astroparticle and astronomy research at the South Pole. It uses one cubic kilometer of Antartica's deepest ice (1500 m-2500 m in depth) to detect Cherenkov light, generated by charged particles traveling through the ice, with an array of phototubes encapsulated in glass pressure spheres. The arrival time as well as the charge deposited of the detected photons represent the base measurements that are used for track and energy reconstruction of those charged particles. The optical properties of the deep antarctic ice vary from layer to layer. Measurements of the ice properties and their correct modeling in Monte Carlo simulation is then of primary importance for the correct understanding of the IceCube telescope behavior. After a short summary about the different methods to investigate the ice properties and to calibrate the detector, we show how the simulation obtained by using this information compares to the measured data and how systematic errors due to uncertain ice properties are determined in IceCube.

  16. IceCube systematic errors investigation: Simulation of the ice

    Energy Technology Data Exchange (ETDEWEB)

    Resconi, Elisa; Wolf, Martin [Max-Planck-Institute for Nuclear Physics, Heidelberg (Germany); Schukraft, Anne [RWTH, Aachen University (Germany)

    2010-07-01

    IceCube is a neutrino observatory for astroparticle and astronomy research at the South Pole. It uses one cubic kilometer of Antartica's deepest ice (1500 m-2500 m in depth) to detect Cherenkov light, generated by charged particles traveling through the ice, with an array of phototubes encapsulated in glass pressure spheres. The arrival time as well as the charge deposited of the detected photons represent the base measurements that are used for track and energy reconstruction of those charged particles. The optical properties of the deep antarctic ice vary from layer to layer. Measurements of the ice properties and their correct modeling in Monte Carlo simulation is then of primary importance for the correct understanding of the IceCube telescope behavior. After a short summary about the different methods to investigate the ice properties and to calibrate the detector, we show how the simulation obtained by using this information compares to the measured data and how systematic errors due to uncertain ice properties are determined in IceCube.

  17. Airborne Gravity: NGS' Airborne Gravity Data for AN01 (2009-2010)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Airborne gravity data for Alaska collected in 2009-2010 over 2 surveys. This data set is part of the Gravity for the Re-definition of the American Vertical Datum...

  18. Status of the Signals of Opportunity Airborne Demonstrator (SoOp-AD)

    Science.gov (United States)

    Garrison, Jim; Lin, Yao-Cheng; Piepmeier, Jeff; Knuble, Joe; Hersey, Ken; Du Toit, Cornelus; Joseph, Alicia; Deshpande, Manohar; Alikakos, George; O'Brien, Steve; Katzberg, Stephen

    2016-01-01

    Root zone soil moisture (RZSM) is not directly measured by any current satellite instrument, despite its importance as a key link between surface hydrology and deeper processes. Presently, model assimilation of surface measurements or indirect estimates using other methods must be used to estimate this value. Signals of Opportunity (SoOp) methods, exploiting reflected P- and S-band communication satellite signals, have many of the benefits of both active and passive microwave remote sensing. Reutilization of active transmitters, with forward-scattering geometry, presents a strong reflected signal even at orbital altitudes. Microwave radiometry is advantageous as it measures emissivity, which is directly related to dielectric constant and sensitive to water content of soil. Synthetic aperture radar (SAR) is used in P-band (400 MHz) for soil moisture and biomass, but faces issues in obtaining permission to transmit due to spectrum regulations, particularly over North America and Europe. A primary advantage of SAR is excellent spatial resolution. Signals-of-opportunity (SoOp) reflectometry provides a good compromise between radiometry and SAR by providing decent sensitivity and special resolution for RZSM measurements without issues of spectrum access. Further, a SoOp instrument would not be limited to operating in only a few protected frequencies and is also expected to have less susceptibility to radio-frequency interference (RFI). Although advantageous if available, SoOp techniques do not require the ability to demodulate or decode the communication signals. The SoOp instrument is receive only and therefore requires much less electrical power than a SAR and is more similar to a radiometer in receiver architecture. These unique features of SoOp circumvent past obstacles to a spaceborne P-band remote sensing mission and have the potential to enable new RZSM measurements that are not possible with present technology. We will present the latest development status of a

  19. The Slope Imaging Multi-polarization Photon-counting Lidar: an Advanced Technology Airborne Laser Altimeter

    Science.gov (United States)

    Dabney, P.; Harding, D. J.; Huss, T.; Valett, S.; Yu, A. W.; Zheng, Y.

    2009-12-01

    The Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) is an airborne laser altimeter developed through the NASA Earth Science Technology Office Instrument Incubator Program with a focus on cryopshere remote sensing. The SIMPL instrument incorporates a variety of advanced technologies in order to demonstrate measurement approaches of potential benefit for improved airborne laser swath mapping and spaceflight laser altimeter missions. SIMPL incorporates beam splitting, single-photon ranging and polarimetry technologies at green and near-infrared wavelengths in order to achieve simultaneous sampling of surface elevation, slope, roughness and scattering properties, the latter used to differentiate surface types. The transmitter is a 1 nsec pulse width, 11 kHz, 1064 nm microchip laser, frequency doubled to 532 nm and split into four plane-polarized beams using birefringent calcite crystal in order to maintain co-alignment of the two colors. The 16 channel receiver splits the received energy for each beam into the two colors and each color is split into energy parallel and perpendicular to the transmit polarization plane thereby proving a measure of backscatter depolarization. The depolarization ratio is sensitive to the proportions of specular reflection and surface and volume scattering, and is a function of wavelength. The ratio can differentiate, for example, water, young translucent ice, older granular ice and snow. The solar background count rate is controlled by spatial filtering using a pinhole array and by spectral filtering using temperature-controlled narrow bandwidth filters. The receiver is fiber coupled to 16 Single Photon Counting Modules (SPCMs). To avoid range biases due to the long dead time of these detectors the probability of detection per laser fire on each channel is controlled to be below 30%, using mechanical irises and flight altitude. Event timers with 0.1 nsec resolution in combination the narrow transmit pulse yields single

  20. Topology optimized cloak for airborne sound

    DEFF Research Database (Denmark)

    Andkjær, Jacob Anders; Sigmund, Ole

    2013-01-01

    Directional acoustic cloaks that conceal an aluminum cylinder for airborne sound waves are presented in this paper. Subwavelength cylindrical aluminum inclusions in air constitute the cloak design to aid practical realizations. The positions and radii of the subwavelength cylinders are determined...

  1. A system for airborne SAR interferometry

    DEFF Research Database (Denmark)

    Madsen, Søren Nørvang; Skou, Niels; Granholm, Johan; Woelders, Kim; Christensen, Erik Lintz

    1996-01-01

    perturbations of the surface of the Earth. The Danish Center for Remote Sensing (DCRS) has experimented with airborne INSAR since 1993. Multiple track data are collected in a special mode in which the radar directly steers the aircraft which allows for very precise control of the flight path. Such data sets...

  2. The National Airborne Field Experiment Data Sets

    DEFF Research Database (Denmark)

    Walker, J. P.; Balling, Jan E.; Bell, M.; Berg, A.; Berger, M.; Biasoni, D.; Botha, E.; Boulet, G.; Chen, Y.; Christen, E.; deJeu, R.; Derosnay, P.; Dever, C.; Draper, C.; Fenollar, J.; Gomez, C.; Grant, J. P.; Hacker, J.; Hafeez, M.; Hancock, G.; Hansen, D.; Holz, L.; Hornbuckle, J.; Hurkmans, R.; Jackson, T.; Johanson, J.; Jones, P.; Jones, S.; Kalma, J.; Kerr, Y.; Kim, E.; Kuzmin, V.; Lakshmi, V.; Lopez, E.; Maggioni, V.; Maisongrande, P.; Martinez, C.; McKee, L.; Merlin, O.; Mladenova, I.; O'Neill, P.; Panciera, R.; Paruscio, V.; Pipunic, R.; Rawls, W.; Rinaldi, M.; Ruediger, C.; Saco, P.; Saleh, K.; Savstrup-Kristensen, S.; Shoemark, V.; Skou, N.; Soebjaerg, S.; Summerell, G.; Teuling, A. J.; Thompson, H.; Thyer, M.; Toyra, J.; Tsang, A.; Wells, T.; Wursteisen, P.; Young, R.

    The National Airborne Field Experiment's (NAFE) were a series of intensive experiments recently conducted in different parts of Australia. These hydrologic-focused experiments have been designed to answer a range of questions which can only be resolved through carefully planned and executed field...

  3. Materiel requirements for airborne minefield detection system

    Science.gov (United States)

    Bertsche, Karl A.; Huegle, Helmut

    1997-07-01

    Within the concept study, Material Requirements for an airborne minefield detection systems (AMiDS) the following topics were investigated: (i) concept concerning airborne minefield detection technique sand equipment, (ii) verification analysis of the AMiDS requirements using simulation models and (iii) application concept of AMiDS with regard o tactics and military operations. In a first approach the problems concerning unmanned airborne minefield detection techniques within a well-defined area were considered. The complexity of unmanned airborne minefield detection is a result of the following parameters: mine types, mine deployment methods, tactical requirements, topography, weather conditions, and the size of the area to be searched. In order to perform the analysis, a simulation model was developed to analyze the usability of the proposed remote controlled air carriers. The basic flight patterns for the proposed air carriers, as well as the preparation efforts of military operations and benefits of such a system during combat support missions were investigated. The results of the conceptual study showed that a proposed remote controlled helicopter drone could meet the stated German MOD scanning requirements of mine barriers. Fixed wing air carriers were at a definite disadvantage because of their inherently large turning loops. By implementing a mine detection system like AMiDS minefields can be reconnoitered before an attack. It is therefore possible either to plan, how the minefields can be circumvented or where precisely breaching lanes through the mine barriers are to be cleared for the advancing force.

  4. Experimental airborne transmission of PRRS virus

    DEFF Research Database (Denmark)

    Kristensen, C.S.; Bøtner, Anette; Takai, H.; Nielsen, J.P.; Jorsal, Sven Erik Lind

    A series of three experiments, differing primarily in airflow volume, were performed to evaluate the likelihood of airborne transmission of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) from infected to non-infected pigs. Pigs were housed in two units (unit A and unit B) located 1 m...

  5. Use of airborne vehicles as research platforms

    OpenAIRE

    Gratton, GB

    2012-01-01

    This is the accepted version of the following chapter: Gratton, G. 2012. Use of Airborne Vehicles as Research Platforms. Encyclopedia of Aerospace Engineering, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/9780470686652.eae604/full. Copyright @ John Wiley & Sons 2012.

  6. The East Antarctic Ice Sheet and the Gamburtsev Subglacial Mountains (Invited)

    Science.gov (United States)

    Bell, R. E.; Studinger, M.; Ferraccioli, F.; Damaske, D.; Finn, C.; Braaten, D. A.; Fahnestock, M. A.; Jordan, T. A.; Corr, H.; Elieff, S.; Frearson, N.; Block, A. E.; Rose, K.

    2009-12-01

    Models of the onset of glaciation in Antarctica routinely document the early growth of the ice sheet on the summit of the Gamburtsev Subglacial Mountains in the center of the East Antarctic Craton. While ice sheet models replicate the formation of the East Antarctic ice sheet 35 million years ago, the age, evolution and structure of the Gamburtsev Mountains remain completely unresolved. During the International Polar Year scientists from seven nations have launched a major collaborative program (AGAP) to explore the Gamburtsev Subglacial Mountains buried by the East Antarctic ice sheet and bounded by numerous subglacial lakes. The AGAP umbrella is a multi-national, multi-disciplinary effort and includes aerogeophysics, passive seismology, traverse programs and will be complimented by future ice core and bedrock drilling. A major new airborne data set including gravity; magnetics; ice thickness; SAR images of the ice-bed interface; near-surface and deep internal layers; and ice surface elevation is providing insights into a more dynamic East Antarctica. More than 120,000 km of aerogeophysical data have been acquired from two remote field camps during the 2008/09 field season. AGAP effort was designed to address several fundamental questions including: 1) What role does topography play in the nucleation of continental ice sheets? 2) How do tectonic processes control the formation, distribution, and stability of subglacial lakes? The preliminary analysis of this major new data set indicated these 3000m high mountains are deeply dissected by a dendritic system. The northern margin of the mountain range terminates against the inland extent of the Lambert Graben. Evidence of the onset of glaciation is preserved as cirques and U shaped valleys along the axis of the uplifted massifs. The geomorphology reflects the interaction between the ice sheet and the Gamburtsev Mountains. Bright reflectors in the radar data in the deep valleys indicate the presence of water that has

  7. Ionospheric Effects on Spaceborne P Band Synthetic Aperture Radar Imaging%电离层对星载P波段合成孔径雷达成像的影响

    Institute of Scientific and Technical Information of China (English)

    姚佰栋; 时晶晶

    2015-01-01

    This paper analyzed the relationship between the signal’s carrier frequency, bandwidth, the ionospheric total electronics content(TEC) and scintillation intensity with P band synthetic aperture radar(SAR)’s image resolution. The point target imaging simulation results shown that SAR’s range resolution was closely related with the signal’s carrier frequency, bandwidth and the ionospheric TEC when the wave propagated in the ionosphere, and the ionosphere also caused the SAR image offset in range direction. In addition the azimuth resolution is mainly inlfuenced by the ionospheric scintillation effect, the azimuth resolution decreased rapidly with the enhancement of scintillation’s intensity. While in strong scintillation conditions, the azimuth resolution declined seriously, even could not image.%文章分析了信号载频、带宽、电离层总电子量(Total Electronics Content,TEC)以及闪烁强度等因素对于P波段合成孔径雷达(Synthetic Aperture Radar,SAR)成像分辨率的影响,并进行了点目标成像仿真研究。仿真结果表明,在电离层中传播时SAR距离向分辨率与信号载频、带宽以及电离层总电子量大小密切相关,同时会导致SAR距离向图像偏移;方位向分辨率受电离层闪烁效应的影响,随着闪烁强度的增强,方位向分辨率逐渐降低,当处于强闪烁条件下时,方位向无法成像。

  8. CALIOPE airborne CO{sub 2} DIAL (CACDI) system design

    Energy Technology Data Exchange (ETDEWEB)

    Mietz, D.; Archuleta, B.; Archuleta, J. [and others

    1997-09-01

    Los Alamos National Laboratory is currently developing an airborne CO{sub 2} Differential Absorption Lidar (DIAL) system based on second generation technology demonstrated last summer at NTS. The CALIOPE Airborne CO{sub 2} DIAL (CACDI) system requirements have been compiled based on the mission objectives and SONDIAL model trade studies. Subsystem designs have been developed based on flow down from these system requirements, as well as experience gained from second generation ground tests and N-ABLE (Non-proliferation AirBorne Lidar Experiments) airborne experiments. This paper presents the CACDI mission objectives, system requirements, the current subsystem design, and provides an overview of the airborne experimental plan.

  9. The Influence of Platelet Ice and Snow on Antarctic Landfast Sea Ice

    OpenAIRE

    Hoppmann, Mario; Nicolaus, Marcel

    2012-01-01

    Sea ice fastened to coasts, icebergs and ice shelves is of crucial importance for climate- and ecosystems. Near Antarctic ice shelves, this land-fast sea ice exhibits two unique characteristics: a significant fraction of incorporated ice platelets and a thick snow cover, leading to surface flooding and snow-ice formation. In order to investigate the spatial and temporal variability of sea-ice and snow thicknesses, we have initiated a regular observation program on the land-fast sea ice of ...

  10. Towards an ice free Arctic

    International Nuclear Information System (INIS)

    The article surveys the rate of ice melting in Arctic and forecasts that the region will be free of ice during this century. Observations of the atmospheric and sea climate, total ice areas for the period 1978 to 1998 and predictions for the areas from 1990 to 2040 by using two different models are presented. Possible reasons for the changes are discussed and some views on the consequences for the Norwegian climate presented

  11. PSL Icing Facility Upgrade Overview

    Science.gov (United States)

    Griffin, Thomas A.; Dicki, Dennis J.; Lizanich, Paul J.

    2014-01-01

    The NASA Glenn Research Center Propulsion Systems Lab (PSL) was recently upgraded to perform engine inlet ice crystal testing in an altitude environment. The system installed 10 spray bars in the inlet plenum for ice crystal generation using 222 spray nozzles. As an altitude test chamber, the PSL is capable of simulating icing events at altitude in a groundtest facility. The system was designed to operate at altitudes from 4,000 to 40,000 ft at Mach numbers up to 0.8M and inlet total temperatures from -60 to +15 degF. This paper and presentation will be part of a series of presentations on PSL Icing and will cover the development of the icing capability through design, developmental testing, installation, initial calibration, and validation engine testing. Information will be presented on the design criteria and process, spray bar developmental testing at Cox and Co., system capabilities, and initial calibration and engine validation test. The PSL icing system was designed to provide NASA and the icing community with a facility that could be used for research studies of engine icing by duplicating in-flight events in a controlled ground-test facility. With the system and the altitude chamber we can produce flight conditions and cloud environments to simulate those encountered in flight. The icing system can be controlled to set various cloud uniformities, droplet median volumetric diameter (MVD), and icing water content (IWC) through a wide variety of conditions. The PSL chamber can set altitudes, Mach numbers, and temperatures of interest to the icing community and also has the instrumentation capability of measuring engine performance during icing testing. PSL last year completed the calibration and initial engine validation of the facility utilizing a Honeywell ALF502-R5 engine and has duplicated in-flight roll back conditions experienced during flight testing. This paper will summarize the modifications and buildup of the facility to accomplish these tests.

  12. THE INITIAL COOLING EXPERIMENT (ICE)

    CERN Multimedia

    1977-01-01

    ICE was built during 1977, in a record time of 9 months, using the modified bending magnets of the g-2 muon storage ring (see 7405430). ICE was a proton and antiproton storage ring, built to verify the validity of stochastic and electron cooling for the antiproton project to be launched in 1978. More on the ICE experimental programme with 7802099. See also 7809081, 7908242.

  13. Fram Strait sea ice outflow

    Science.gov (United States)

    Kwok, R.; Cunningham, G. F.; Pang, S. S.

    2004-01-01

    We summarize 24 years of ice export estimates and examine, over a 9-year record, the associated variability in the time-varying upward-looking sonar (ULS) thickness distributions of the Fram Strait. A more thorough assessment of the PMW (passive microwave) ice motion with 5 years of synthetic aperture radar (SAR)observations shows the uncertainties to be consistent with that found by Kwok and Rothrock [1999], giving greater confidence to the record of ice flux calculations.

  14. Ice Sheets and the Anthropocene

    OpenAIRE

    Wolff, Eric W.

    2014-01-01

    Ice could play a role in identifying and defining the Anthropocene. The recurrence of northern hemisphere glaciation and the stability of the Greenland Ice Sheet are both potentially vulnerable to human impact on the environment. However, only a very long hiatus in either would be unusual in the context of the Quaternary Period, requiring the definition of a geological boundary. Human influence can clearly be discerned in several ice-core measurements. These include a sharp boundary in radioa...

  15. Cloud particle size distributions measured with an airborne digital in-line holographic instrument

    Directory of Open Access Journals (Sweden)

    J. P. Fugal

    2009-03-01

    Full Text Available Holographic data from the prototype airborne digital holographic instrument HOLODEC (Holographic Detector for Clouds, taken during test flights are digitally reconstructed to obtain the size (equivalent diameters in the range 23 to 1000 μm, three-dimensional position, and two-dimensional profile of ice particles and then ice particle size distributions and number densities are calculated using an automated algorithm with minimal user intervention. The holographic method offers the advantages of a well-defined sample volume size that is not dependent on particle size or airspeed, and offers a unique method of detecting shattered particles. The holographic method also allows the volume sample rate to be increased beyond that of the prototype HOLODEC instrument, limited solely by camera technology.

    HOLODEC size distributions taken in mixed-phase regions of cloud compare well to size distributions from a PMS FSSP probe also onboard the aircraft during the test flights. A conservative algorithm for detecting shattered particles utilizing the particles depth-position along the optical axis eliminates the obvious ice particle shattering events from the data set. In this particular case, the size distributions of non-shattered particles are reduced by approximately a factor of two for particles 15 to 70 μm in equivalent diameter, compared to size distributions of all particles.

  16. Ice-driven CO2 feedback on ice volume

    Directory of Open Access Journals (Sweden)

    W. F. Ruddiman

    2006-02-01

    Full Text Available The origin of the major ice-sheet variations during the last 2.7 million years remains a mystery. Neither the dominant 41 000-year cycles in δ18O and ice-volume during the late Pliocene and early Pleistocene nor the late-Pleistocene variations near 100 000 years is a linear (''Milankovitch'' response to summer insolation forcing. Both result from non-linear behavior within the climate system. Greenhouse gases (primarily CO2 are a plausible source of this non-linearity, but confusion has persisted over whether the gases force ice volume or are a positive feedback. During the last several hundred thousand years, CO2 and ice volume (marine δ18O have varied in phase both at the 41 000-year obliquity cycle and within the ~100 000-year eccentricity band. This timing argues against greenhouse-gas forcing of a slow ice response and instead favors ice control of a fast CO2 response. Because the effect of CO2 on temperature is logarithmic, the temperature/CO2 feedback on ice volume is also logarithmic. In the schematic model proposed here, ice sheets were forced by insolation changes at the precession and obliquity cycles prior to 0.9 million years ago and responded in a linear way, but CO2 feedback amplified (roughly doubled the ice response at 41 000 years. After 0.9 million years ago, as polar climates continued to cool, ablation weakened. CO2 feedback continued to amplify ice-sheet growth at 41 000-year intervals, but weaker ablation permitted ice to survive subsequent insolation maxima of low intensity. These longer-lived ice sheets persisted until peaks in northern summer insolation paced abrupt deglaciations every 100 000±15 000 years. Most ice melting during deglaciations was achieved by the same CO2/temperature feedback that had built the ice sheets, but now acting in the opposite direction. Several processes have the northern geographic origin, as well as the requisite orbital tempo and phasing, to have been the mechanisms by which ice sheets

  17. Airborne laser sensors and integrated systems

    Science.gov (United States)

    Sabatini, Roberto; Richardson, Mark A.; Gardi, Alessandro; Ramasamy, Subramanian

    2015-11-01

    The underlying principles and technologies enabling the design and operation of airborne laser sensors are introduced and a detailed review of state-of-the-art avionic systems for civil and military applications is presented. Airborne lasers including Light Detection and Ranging (LIDAR), Laser Range Finders (LRF), and Laser Weapon Systems (LWS) are extensively used today and new promising technologies are being explored. Most laser systems are active devices that operate in a manner very similar to microwave radars but at much higher frequencies (e.g., LIDAR and LRF). Other devices (e.g., laser target designators and beam-riders) are used to precisely direct Laser Guided Weapons (LGW) against ground targets. The integration of both functions is often encountered in modern military avionics navigation-attack systems. The beneficial effects of airborne lasers including the use of smaller components and remarkable angular resolution have resulted in a host of manned and unmanned aircraft applications. On the other hand, laser sensors performance are much more sensitive to the vagaries of the atmosphere and are thus generally restricted to shorter ranges than microwave systems. Hence it is of paramount importance to analyse the performance of laser sensors and systems in various weather and environmental conditions. Additionally, it is important to define airborne laser safety criteria, since several systems currently in service operate in the near infrared with considerable risk for the naked human eye. Therefore, appropriate methods for predicting and evaluating the performance of infrared laser sensors/systems are presented, taking into account laser safety issues. For aircraft experimental activities with laser systems, it is essential to define test requirements taking into account the specific conditions for operational employment of the systems in the intended scenarios and to verify the performance in realistic environments at the test ranges. To support the

  18. Fluid dynamics of planetary ices

    CERN Document Server

    Greve, Ralf

    2009-01-01

    The role of water ice in the solar system is reviewed from a fluid-dynamical point of view. On Earth and Mars, water ice forms ice sheets, ice caps and glaciers at the surface, which show glacial flow under their own weight. By contrast, water ice is a major constituent of the bulk volume of the icy satellites in the outer solar system, and ice flow can occur as thermal convection. The rheology of polycrystalline aggregates of ordinary, hexagonal ice Ih is described by a power law, different forms of which are discussed. The temperature dependence of the ice viscosity follows an Arrhenius law. Therefore, the flow of ice in a planetary environment constitutes a thermo-mechanically coupled problem; its model equations are obtained by inserting the flow law and the thermodynamic material equations in the balance laws of mass, momentum and energy. As an example of gravity-driven flow, the polar caps of Mars are discussed. For the north-polar cap, large-scale flow velocities of the order of 0.1...1 mm/a are likely...

  19. Ice and conical structure interactions

    OpenAIRE

    LU, Wenjun

    2010-01-01

    The pursuit of energy in Arctic waters drives people to design ocean structures applying new concepts.Conical structures which shift the ice failure mode from crushing to bending could reduce the total iceload. Moreover, its symmetric geometry naturally achieves the requirement of ice-vaning and reduces the risk of possible large ice loads induced by the failure of ice-vaning that might be encountered by other shapes of floaters. The thesis is based on the model test results of a group of con...

  20. Marine ice profiling : future directions

    Energy Technology Data Exchange (ETDEWEB)

    Marko, J.R.; Fissel, D.B. [ASL Environmental Sciences Inc., Sidney, BC (Canada)

    2006-11-15

    High sampling-frequency ice profiling tools are needed to characterize ice covers for the purposes of offshore development and climate-change studies. This paper reviewed the contribution that upward-looking sonars moored on the sea floor have made towards the qualitative and quantitative understandings of ocean ice covers, with particular reference to the IPS4 Ice Profiler developed by ASL Environmental Sciences Inc. This water column profiler enables quasi-continuous measurements of ice draft along curvilinear tracks to accuracies as great as 0.05 m. This paper provided a description of both the instrument and measurement methodology, including an outline of the steps involved in the extraction of ice drafts from range information. The IPS4 has been used to acquire and store data from more than 100 deployments in polar and sub-polar ice-infested regions. The acquired data on ice properties is used to characterize platform and operations design, planning, navigation support and for scientific ice and climate studies. The combined application of the IPS4 and a sister instrument specialized for shallow water environments has resulted in new deployment methodologies in addition to simple ice draft measurements of the ice undersurface and draft statistics. These include the detection of unconsolidated ice content in lower portions of ice keels or loose ice under ice covers in shallow waters. The development of new generation IPS5 instrumentation is guided by perceived future needs in both conventional draft profiling and in new applications. The IPS5 will offer users improved access to better, more complete, information on ice and other components of the upper ocean and freshwater environments. This paper also reviewed ASL's vision of this instrumentation and progress toward prototype construction. ASL is also finalizing the design and manufacture of a plastic pressure case to address corrosion problems associated with long term deployments. The new instrument

  1. Climatic implications of ice microphysics

    Energy Technology Data Exchange (ETDEWEB)

    Liou, K.N. [Univ. of Utah, Salt Lake City, UT (United States)

    1995-09-01

    Based on aircraft measurements of mid-latitude cirrus clouds, ice crystal size distribution and ice water content (IWC) are shown to be dependent on temperature. This dependence is also evident from the theoretical consideration of ice crystal growth. Using simple models of the diffusion and accretion growth of ice particles, the computed mean ice crystal size and IWC compare reasonably well with the measured mean values. The temperature dependence of ice crystal size and IWC has important climatic implications in that the temperature field perturbed by external radiative forcings, such as greenhouse warming, can alter the composition of ice crystal clouds. Through radiative transfer, ice microphysics can in turn affect the temperature field. Higher IWC would increase cloud solar albedo and infrared emissivity, while for a given IWC, larger crystals would reduce cloud albedo and emissivity. The competing effects produced by greenhouse temperature perturbations via ice micro-physics and radiation interactions and feedbacks are assessed by a one-dimensional radiative-convective climate model that includes an advanced radiation parameterization program. 3 figs.

  2. The importance of large scale sea ice drift and ice type distribution on ice extent in the Weddell Sea

    OpenAIRE

    Schwegmann, Sandra; Timmermann, Ralph; Haas, Christian; Gerdes, Rüdiger; Lemke, Peter

    2009-01-01

    In austral winter large regions of the Southern Ocean are covered by seasonal sea ice which disappears in summer. Only in few regions sea ice persists during the summer and becomes second year ice. Most of this second year ice is located in the Weddell Sea, making this region particularly interesting. The variation of the ice covered area modifies the exchange of heat, mass and momentum between ocean and atmosphere. Therefore knowledge of ice extent and its variability is necessary for an ad...

  3. Ice storm `98

    Energy Technology Data Exchange (ETDEWEB)

    Soulard, F.; Trant, D.; Filoso, J.; Van Wesenbeeck, P. [Statistics Canada, Ottawa, ON (Canada). Environment Statistics Program

    1998-12-31

    As much as 100 millimeters of freezing rain fell on central and eastern Canada between January 4 to 10, 1998. This study concentrates on Canada`s St. Lawrence River Valley where total precipitation exceeded 73 mm in Kingston, 85 mm in Ottawa and 100 mm in areas south of Montreal. By comparison, the largest previously recorded ice storms left between 30 and 40 mm of ice. A state of emergency was declared for the affected regions. 56 per cent of Quebec`s population and 11 per cent of Ontario`s population were affected by the storm. Over 1000 power transmission towers collapsed and more than 30,000 wooden utility poles were brought down. In Quebec, nearly 1.4 million customers were left without electricity. In Ontario that number was about 230,000. While some manufacturers benefited directly from the storm, including makers of hydro and telephone poles, batteries and specialized electrical equipment, the overall economic losses for Montreal and Ottawa were high as estimates run to $585 million and $114 million, respectively. Almost 5 million sugar maple taps in Quebec and Ontario were located and suffered some damage in the affected areas. Nearly one-quarter (274,000) of all dairy cows were also located in the affected areas. Since in the absence of electricity they could not be milked, many of them suffered from mastitis. Many succumbed, others that survived may never attain their former level of productivity. As of June 1998, over 600,000 insurance claims totaling one billion dollars had been filed by Canadian households and businesses from the area affected by the ice storm.1 fig.

  4. Improved ice loss estimate of the northwestern Greenland ice sheet

    NARCIS (Netherlands)

    Kjeldsen, K.K.; Khan, S.A.; van den Broeke, M.R.; van Angelen, J.H.

    2013-01-01

    We estimate ice volume change rates in the northwest Greenland drainage basin during 2003–2009 using Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter data. Elevation changes are often reported to be largest near the frontal portion of outlet glaciers. To improve the volume change est

  5. Monitoring Fram Strait sea ice outflow and thin ice thickness

    Science.gov (United States)

    Kwok, R.

    2001-01-01

    We propose to: 1) use sequential SAR maps to monitor the profile of sea ice motion through Fram Strait over the period 2003 throught 2005; and 2) explore the potential of using L-band polarimetric data to determine the thickness of thin ice over the same region.

  6. Delicious ice cream, why does salt thaw ice?

    Science.gov (United States)

    Bagnoli, Franco

    2016-04-01

    During winter, we use to spread salt to thaw ice on the streets. In a physics show, one can be almost sure that after showing this effect, the answer to what happens to temperature will be "it increases". But no! It goes down, in such amount that one can complement the show by producing hand-made ice creams [1].

  7. Proceedings of ICED'09

    DEFF Research Database (Denmark)

    The 17th International Conference on Engineering Design, ICED'09, was held August 24-27 2009 at Stanford University, California, USA. The Conference is the flagship event of the Design Society, a society dedicated to contributing to a broad and established understanding of development and design...... thinking, theory, and practice, with a premium placed on evidence-based research. The papers are published in a total of ten volumes of Proceedings, in addition to electronic publication. This volume contains 32 papers concerned with Design for X, Design to X, where X can represent a variety of attributes...

  8. Optimal site selection for a high resolution ice core record in East Antarctica

    Science.gov (United States)

    Vance, T.; Roberts, J.; Moy, A.; Curran, M.; Tozer, C.; Gallant, A.; Abram, N.; van Ommen, T.; Young, D.; Grima, C.; Blankenship, D.; Siegert, M.

    2015-11-01

    Ice cores provide some of the best dated and most comprehensive proxy records, as they yield a vast and growing array of proxy indicators. Selecting a site for ice core drilling is nonetheless challenging, as the assessment of potential new sites needs to consider a variety of factors. Here, we demonstrate a systematic approach to site selection for a new East Antarctic high resolution ice core record. Specifically, seven criteria are considered: (1) 2000 year old ice at 300 m depth, (2) above 1000 m elevation, (3) a minimum accumulation rate of 250 mm yr-1 IE, (4) minimal surface re-working to preserve the deposited climate signal, (5) a site with minimal displacement or elevation change of ice at 300 m depth, (6) a strong teleconnection to mid-latitude climate and (7) an appropriately complementary relationship to the existing Law Dome record (a high resolution record in East Antarctica). Once assessment of these physical characteristics identified promising regions, logistical considerations (for site access and ice core retrieval) were briefly considered. We use Antarctic surface mass balance syntheses, along with ground-truthing of satellite data by airborne radar surveys to produce all-of-Antarctica maps of surface roughness, age at specified depth, elevation and displacement change and surface air temperature correlations to pinpoint promising locations. We also use the European Centre for Medium-Range Weather Forecast ERA 20th Century reanalysis (ERA-20C) to ensure a site complementary to the Law Dome record is selected. We find three promising sites in the Indian Ocean sector of East Antarctica in the coastal zone from Enderby Land to the Ingrid Christensen Coast (50-100° E). Although we focus on East Antarctica for a new ice core site, the methodology is more generally applicable and we include key parameters for all of Antarctica which may be useful for ice core site selection elsewhere and/or for other purposes.

  9. Scavenging of biomass burning refractory black carbon and ice nuclei in a Western Pacific extratropical storm

    Directory of Open Access Journals (Sweden)

    J. L. Stith

    2011-01-01

    Full Text Available In situ airborne sampling of refractory black carbon (rBC particles and Ice Nuclei (IN was conducted in and near an extratropical cyclonic storm in the Western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Cloud hydrometeors were evaporated by a counterflow virtual impactor and the residue was sampled by a single particle soot photometer (SP2 instrument and a continuous flow diffusion chamber ice nucleus detector. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. In storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here −24 to −29 °C, IN measurements from ice particle residues generally agreed well with simultaneous measurements of total ice concentrations provided that the measurements were made at ambient temperatures similar to those in the CFDC chamber, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures (−22 to −6.4 °C, ice particle concentrations were similar to IN concentrations at CFDC chamber temperatures representative of colder temperatures. This is consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by sedimentation to lower altitudes. Homogeneous freezing did not appear to contribute significantly to midlevel ice concentrations and rime-splintering was also unlikely due to the absence of significant supercooled liquid water in the warm sector clouds. IN number concentrations were typically about a~factor of five to ten lower than simultaneous measurements of rBC concentrations in cloud.

  10. 14 CFR 29.1419 - Ice protection.

    Science.gov (United States)

    2010-01-01

    ... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment Safety Equipment § 29.1419 Ice protection. (a) To obtain... analysis and physical evaluation prescribed in paragraph (b) of this section, the effectiveness of the ice... of the rotorcraft in icing conditions. Miscellaneous Equipment...

  11. Primary spectrum and composition with IceCube/IceTop

    CERN Document Server

    ,

    2016-01-01

    IceCube, with its surface array IceTop, detects three different components of extensive air showers: the total signal at the surface, GeV muons in the periphery of the showers and TeV muons in the deep array of IceCube. The spectrum is measured with high resolution from the knee to the ankle with IceTop. Composition and spectrum are extracted from events seen in coincidence by the surface array and the deep array of IceCube. The muon lateral distribution at the surface is obtained from the data and used to provide a measurement of the muon density at 600 meters from the shower core up to 30 PeV. Results are compared to measurements from other experiments to obtain an overview of the spectrum and composition over an extended range of energy. Consistency of the surface muon measurements with hadronic interaction models and with measurements at higher energy is discussed.

  12. Using ice-penetrating radars to date ice-rise formation and Late Holocene ice-sheet retreat in the Ronne Ice Shelf region, West Antarctica

    Science.gov (United States)

    Kingslake, Jonathan; Hindmarsh, Richard; King, Edward; Corr, Hugh

    2015-04-01

    The history of the West Antarctic Ice Sheet in the region currently occupied by the Ronne Ice Shelf is poorly known. This reflects a lack of accessible recently deglaciated surfaces, which prohibits conventional paleo glaciological techniques that can provide evidence of past ice-sheet extent and retreat, for example ocean coring or exposure-dating of geological material. We use a glaciological technique, Raymond Effect Dating, to constrain the retreat of the ice sheet through the Ronne Ice Shelf region. During two Antarctic field seasons, we used a pulse-echo ice-penetrating radar to image the base and internal stratigraphy of four ice rises - areas of grounded ice containing ice divides. Towing the radar with skidoos, we conducted over 2000 km of surveys on the Skytrain, Korff, Henry and Fowler Ice Rises and the ice shelf between them. We also used a step-frequency radar called pRES to measure the vertical ice flow in the vicinity of each ice divide. Isochronal ice layers imaged during the surveys deforming in a predictable way with ice flow, meaning that their shape contains information about past ice flow. Directly beneath ice divides the downward motion of the ice is impeded by an ice-dynamical phenomenon called the Raymond Effect. This causes layers beneath the divides to form 'Raymond Arches' that grow over time. We will present the data and simulate the growth of the Raymond Arches using our pRES-measured vertical ice velocities and date the onset of ice-divide flow at each ice rise by comparing the size of simulated arches to the arches imaged during our radar surveys. We consider the main sources of uncertainty associated with these ice-rise formation dates and discuss what they can tell us about the retreat of the West Antarctic Ice Sheet through this region during the last few thousand years.

  13. Continued thinning of sea ice at the North Pole and in the Transpolar Drift?

    Science.gov (United States)

    Haas, C.; Etienne, J.

    2007-12-01

    The extent of Arctic sea ice is strongly decreasing, with a new record summer minimum observed in 2007. However, the interpretation of this rapid decline in the context of climate change is hampered by the lack of ice thickness data, as it is unclear how much of the retreat is due to variations in thermodynamic or dynamic boundary conditions. A 350 km long ice thickness profile was obtained in April 2007 between the North Pole and 87N, 58W by means of helicopter-borne electromagnetic profiling. The measurements revealed the presence of predominantly second-year ice with a mean total (snow plus ice) thickness of 3.31 +/- 1.51 m and a modal total thickness of 2.35 m. There was no strong ice thickness trend towards the coast of Ellesmere Island. Ground-based measurements showed a bi-modal snow thickness distribution, with 0.05 m of snow on first-year ice and 0.2 to 0.4 m on second-year ice. If compared with earlier sporadic measurements in the same region between 1991 and 2001, the results indicate a continued ice thinning of 0.3 to 0.7 m between 2001 and 2007. However, the comparison is complicated by the unknown amplitude of the seasonal thickness cycle, as previous measurements were only performed during August. Therefore, the paper discusses the use of additional data like e.g. from ice mass balance buoys which can give insights into the thermodynamic components of sea ice mass balance, and outlines the urgent need for more systematic snow and ice thickness observations. This need has unfortunately only barely been met so far during the ongoing International Polar Year. The paper will also present plans for future, more systematic airborne campaigns, which could cover the whole region of the Arctic Ocean. These include an Arctic airship crossing of the Total Pole Airship project, and an Arctic circumnavigation with a new, German BT67 airplane.

  14. The physics of ice cream

    Science.gov (United States)

    Clarke, Chris

    2003-05-01

    Almost everybody likes ice cream, so it can provide an excellent vehicle for discussing and demonstrating a variety of physical phenomena, such as Newton's law of cooling, Boyle's law and the relationship between microstructure and macroscopic properties (e.g. Young's modulus). Furthermore, a demonstration of freezing point depression can be used to make ice cream in the classroom!

  15. Ice sheet hydrology from observations

    International Nuclear Information System (INIS)

    The hydrological systems of ice sheets are complex. Our view of the system is split, largely due to the complexity of observing the systems. Our basic knowledge of processes have been obtained from smaller glaciers and although applicable in general to the larger scales of the ice sheets, ice sheets contain features not observable on smaller glaciers due to their size. The generation of water on the ice sheet surface is well understood and can be satisfactorily modeled. The routing of water from the surface down through the ice is not complicated in terms of procat has been problematic is the way in which the couplings between surface and bed has been accomplished through a kilometer of cold ice, but with the studies on crack propagation and lake drainage on Greenland we are beginning to understand also this process and we know water can be routed through thick cold ice. Water generation at the bed is also well understood but the main problem preventing realistic estimates of water generation is lack of detailed information about geothermal heat fluxes and their geographical distribution beneath the ice. Although some average value for geothermal heat flux may suffice, for many purposes it is important that such values are not applied to sub-regions of significantly higher fluxes. Water generated by geothermal heat constitutes a constant supply and will likely maintain a steady system beneath the ice sheet. Such a system may include subglacial lakes as steady features and reconfiguration of the system is tied to time scales on which the ice sheet geometry changes so as to change pressure gradients in the basal system itself. Large scale re-organization of subglacial drainage systems have been observed beneath ice streams. The stability of an entirely subglacially fed drainage system may hence be perturbed by rapid ice flow. In the case of Antarctic ice streams where such behavior has been observed, the ice streams are underlain by deformable sediments. It is

  16. The IceProd Framework

    DEFF Research Database (Denmark)

    Aartsen, M.G.; Abbasi, R.; Ackermann, M.;

    2015-01-01

    IceCube is a one-gigaton instrument located at the geographic South Pole, designed to detect cosmic neutrinos, iden- tify the particle nature of dark matter, and study high-energy neutrinos themselves. Simulation of the IceCube detector and processing of data require a significant amount of...... computational resources. IceProd is a distributed management system based on Python, XML-RPC and GridFTP. It is driven by a central database in order to coordinate and admin- ister production of simulations and processing of data produced by the IceCube detector. IceProd runs as a separate layer on top of other...... middleware and can take advantage of a variety of computing resources, including grids and batch systems such as CREAM, Condor, and PBS. This is accomplished by a set of dedicated daemons that process job submission in a coordinated fashion through the use of middleware plugins that serve to abstract the...

  17. Ice sheet hydrology from observations

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Peter (Dept. of Physical Geography and Quaternary Geology, Stockholm Univ-, Stockholm (Sweden))

    2010-11-15

    The hydrological systems of ice sheets are complex. Our view of the system is split, largely due to the complexity of observing the systems. Our basic knowledge of processes have been obtained from smaller glaciers and although applicable in general to the larger scales of the ice sheets, ice sheets contain features not observable on smaller glaciers due to their size. The generation of water on the ice sheet surface is well understood and can be satisfactorily modeled. The routing of water from the surface down through the ice is not complicated in terms of procat has been problematic is the way in which the couplings between surface and bed has been accomplished through a kilometer of cold ice, but with the studies on crack propagation and lake drainage on Greenland we are beginning to understand also this process and we know water can be routed through thick cold ice. Water generation at the bed is also well understood but the main problem preventing realistic estimates of water generation is lack of detailed information about geothermal heat fluxes and their geographical distribution beneath the ice. Although some average value for geothermal heat flux may suffice, for many purposes it is important that such values are not applied to sub-regions of significantly higher fluxes. Water generated by geothermal heat constitutes a constant supply and will likely maintain a steady system beneath the ice sheet. Such a system may include subglacial lakes as steady features and reconfiguration of the system is tied to time scales on which the ice sheet geometry changes so as to change pressure gradients in the basal system itself. Large scale re-organization of subglacial drainage systems have been observed beneath ice streams. The stability of an entirely subglacially fed drainage system may hence be perturbed by rapid ice flow. In the case of Antarctic ice streams where such behavior has been observed, the ice streams are underlain by deformable sediments. It is

  18. The importance of large scale sea ice drift and ice type distribution on ice extent in the Weddell Sea

    Science.gov (United States)

    Schwegmann, S.; Haas, C.; Timmermann, R.; Gerdes, R.; Lemke, P.

    2009-12-01

    In austral winter large parts of Antarctic Seas are covered by sea ice. This modifies the exchange of heat, mass and momentum between ocean and atmosphere. The knowledge of ice extent and its variability is necessary for an adequate simulation of those fluxes and thus for climate modelling. The goal of this study is the observation of interannual and seasonal ice extent variations and their underlying causes. Variability is analysed by using monthly means of microwave and scatterometer satellite data. Results are correlated with ice drift variations calculated from a Finite Element Sea ice-Ocean Model (FESOM) and with satellite derived sea ice drift products to determine the dependency of ice extent on sea ice drift. An additional cause for changing ice extent could be the variability of ice type distribution, i.e. the contribution of first and second year ice to the total ice covered area. These ice types are determined on monthly time scales from scatterometer satellite data. Ice class distribution and sea ice drift variability are compared with the characteristics and variability of the Southern Annular Mode (SAM) to evaluate the relative importance of different sea ice parameters for shaping Weddell Sea ice extent and its variability.

  19. New Fluid Prevents Railway Ice

    Science.gov (United States)

    2001-01-01

    Through a licensing agreement between NASA's Ames Research Center and Midwest Industrial Supply, Inc. (MIS), two MIS products have been enhanced with NASA's anti-icing fluid technology. MIS offers the new fluid in two commercial products, the Zero Gravity(TM) Third Rail Anti-Icer/Deicer and the Ice Free Switch(R). Using NASA's fluid technology, these products form a protective-coating barrier that prevents the buildup of ice and snow. Applying the fluid to the railway components prior to ice or snowstorm works as an anti-icing fluid, remaining in place to melt precipitation as it hits the surface. It also functions as a deicing fluid. If applied to an already frozen switch or rail, it will quickly melt the ice, free the frozen parts, and then remain in place to prevent refreezing. Additional benefits include the ability to cling to vertical rail surfaces and resist the effects of rain and wind. With the Ice Free Switch, it takes only five minutes to treat the switch by spraying, brushing, or pouring on the product. Ice Free Switch requires as little as one gallon per switch whereas other deicing fluids require five to ten gallons of liquid to effectively melt ice. Zero Gravity serves the same anti-icing/deicing purposes but applies fluid to the third rail through a system that is easily installed onto mass transit cars. A tank of fluid and a dispensing system are placed underneath the train car and the fluid is applied as the train runs its route.

  20. Analyzing Options for Airborne Emergency Wireless Communications

    Energy Technology Data Exchange (ETDEWEB)

    Michael Schmitt; Juan Deaton; Curt Papke; Shane Cherry

    2008-03-01

    In the event of large-scale natural or manmade catastrophic events, access to reliable and enduring commercial communication systems is critical. Hurricane Katrina provided a recent example of the need to ensure communications during a national emergency. To ensure that communication demands are met during these critical times, Idaho National Laboratory (INL) under the guidance of United States Strategic Command has studied infrastructure issues, concerns, and vulnerabilities associated with an airborne wireless communications capability. Such a capability could provide emergency wireless communications until public/commercial nodes can be systematically restored. This report focuses on the airborne cellular restoration concept; analyzing basic infrastructure requirements; identifying related infrastructure issues, concerns, and vulnerabilities and offers recommended solutions.

  1. Comprehensive characterization of indoor airborne bacterial profile

    Institute of Scientific and Technical Information of China (English)

    P.L.Chan; P.H.F.Yu; Y.W.Cheng; C.Y.Chan; P.K.Wong

    2009-01-01

    This is the first detailed characterization of the air-borne bacterial profiles in indoor environments and two restaurants were selected for this study.Fifteen genera of bacteria were isolated from each restaurant and identified by three different bacterial identification systems including MIDI, Biolog and Riboprinter?.The dominant bacteria of both restaurants were Gram-positive bacteria in which Micrococcus and Bacillus species were the most abundant species.Most bacteria identified were representative species of skin and respiratory tract of human, and soil.Although the bacterial levels in these restaurants were below the limit of the Hong Kong Indoor Air Quality Objective (HKIAQO) Level 1 standard (i.e., < 500 cfu/m3), the majority of these bacteria were opportunistic pathogens.These results suggested that the identity of airborne bacteria should also be included in the IAQ to ensure there is a safety guideline for the public.

  2. Geoid of Nepal from airborne gravity survey

    DEFF Research Database (Denmark)

    Forsberg, René; Olesen, Arne Vestergaard; Einarsson, Indriði;

    2011-01-01

    An airborne gravity survey of Nepal was carried out December 2010 in a cooperation between DTU-Space, Nepal Survey Department, and NGA, USA. The entire country was flown with survey lines spaced 6 nm with a King Air aircraft, with a varying flight altitude from 4 to 10 km. The survey operations...... were a major challenge due to excessive jet streams at altitude as well as occasional excessive mountain waves. Despite the large 400 mGal+ range of gravity anomaly changes from the Indian plains to the Tibetan Plateau, results appear accurate to a few mGal, with proper evaluation from cross...... as well as recent GPS-heights of Mt. Everest. The new airborne data also provide an independent validation of GOCE gravity field results at the local ~100 km resolution scale....

  3. First airborne transient em survey in antarctica

    DEFF Research Database (Denmark)

    Auken, Esben; Mikucki, J. J.; Sørensen, Kurt Ingvard K.I.;

    2012-01-01

    A first airborne transient electromagnetic survey was flown in Antarctica in December 2011 with the SkyTEM system. This transient airborne EM system has been optimized in Denmark for almost ten years and was specially designed for ground water mapping. The SkyTEM tool is ideal for mapping...... conductive targets, and the transient AEM method provides a better understanding of the saline ground water system for microbiology, paleoclimate studies, or geothermal potential. In this study we present preliminary results from our field survey which resulted in more than 1000 km of flight lines. The...... are presented here, the Taylor Valley demonstrating the promising capabilities of the geophysical method to map permafrost and the saline ground water systems....

  4. Simulating City-level Airborne Infectious Diseases

    CERN Document Server

    Shan, Mei; Yifan, Zhu; Zhenghu, Zu; Tao, Zheng; Boukhanovsky, A V; Sloot, P M A

    2012-01-01

    With the exponential growth in the world population and the constant increase in human mobility, the danger of outbreaks of epidemics is rising. Especially in high density urban areas such as public transport and transfer points, where people come in close proximity of each other, we observe a dramatic increase in the transmission of airborne viruses and related pathogens. It is essential to have a good understanding of the `transmission highways' in such areas, in order to prevent or to predict the spreading of infectious diseases. The approach we take is to combine as much information as is possible, from all relevant sources and integrate this in a simulation environment that allows for scenario testing and decision support. In this paper we lay out a novel approach to study Urban Airborne Disease spreading by combining traffic information, with geo-spatial data, infection dynamics and spreading characteristics.

  5. Forage: a sensitive indicator of airborne radioactivity

    International Nuclear Information System (INIS)

    This paper presents the results of using Ge(Li) γ-ray spectroscopy to measure radioactivity concentration of forage in the vicinity of the Joseph M. Farley Nuclear Plant, Houston County, AL., over a 31/2 yr period. The report period includes 2 yr of pre-operational and 11/2 yr of operational sampling. Although the objective of forage sampling was the measurement of manmade airborne fallout radioactivity, several natural radioisotopes were also found to be present. A summary of natural radioactivity data for all samples measured during the period from August 1975 to December 1978 is given. Approximately 10 days after each of four Chinese atmospheric nuclear tests conducted during the sampling period fresh fission product fallout was measured on the forage. The information from these nuclear tests shows forage sampling to be a convenient and sensitive monitoring tool for airborne fallout radioactivity. (author)

  6. Evidence for elevated and spatially variable geothermal flux beneath the West Antarctic Ice Sheet.

    Science.gov (United States)

    Schroeder, Dustin M; Blankenship, Donald D; Young, Duncan A; Quartini, Enrica

    2014-06-24

    Heterogeneous hydrologic, lithologic, and geologic basal boundary conditions can exert strong control on the evolution, stability, and sea level contribution of marine ice sheets. Geothermal flux is one of the most dynamically critical ice sheet boundary conditions but is extremely difficult to constrain at the scale required to understand and predict the behavior of rapidly changing glaciers. This lack of observational constraint on geothermal flux is particularly problematic for the glacier catchments of the West Antarctic Ice Sheet within the low topography of the West Antarctic Rift System where geothermal fluxes are expected to be high, heterogeneous, and possibly transient. We use airborne radar sounding data with a subglacial water routing model to estimate the distribution of basal melting and geothermal flux beneath Thwaites Glacier, West Antarctica. We show that the Thwaites Glacier catchment has a minimum average geothermal flux of ∼ 114 ± 10 mW/m(2) with areas of high flux exceeding 200 mW/m(2) consistent with hypothesized rift-associated magmatic migration and volcanism. These areas of highest geothermal flux include the westernmost tributary of Thwaites Glacier adjacent to the subaerial Mount Takahe volcano and the upper reaches of the central tributary near the West Antarctic Ice Sheet Divide ice core drilling site. PMID:24927578

  7. Validating CERES Radiative Fluxes in the Arctic with Airborne Radiative Flux Measurements from the ARISE Campaign

    Science.gov (United States)

    Corbett, J.; Bucholtz, A.; Kato, S.; Rose, F. G.; Smith, W. L., Jr.

    2015-12-01

    The Clouds and the Earth's Radiant Energy System (CERES) instruments on board NASA's Terra, Aqua, and Soumi-NPP satellites provide the only measurements of reflected solar shortwave and emitted longwave radiative flux over the Arctic. Various methods have shown the uncertainty of CERES fluxes over sea ice to be higher than other scene types. However validation against an independent radiative flux measurement has never been attempted. We present here an attempt to better quantify the uncertainty of time-and-space averaged CERES flux measurements using airborne measurements from the Arctic Radiation - IceBridge Sea Ice Experiment (ARISE). The ARISE campaign took place during September of 2014 based out of Fairbanks, Alaska, with most of the measurements taken in the vicinity of the sea ice edge between 125°W and 150°W, and 71°N to 77°N. For six of the flights, measurements were taken in a lawnmower type pattern over either 100 x 200 km box regions at a constant altitude of >6 km, or 100 x 100 km box regions at an altitude of between 200 m to 500 m. They were designed to resemble the CERES Level 3 spatial averaging grids, and were located and timed to coincide with a high number of CERES overpasses. On board the aircraft were a set of upward and downward facing shortwave and longwave broadband radiometers (BBR), along with other instruments measuring meteorological conditions and cloud properties. We have compared the broadband radiative fluxes from BBR with those from CERES for the three days where the aircraft was flying the high altitude pattern. We use the Fu-Liou radiative transfer model to account for differences in the measurement altitude between BBR and CERES. We will present results of the comparisons between the computed fluxes and the measured longwave and shortwave radiative fluxes.

  8. The IceProd (IceCube Production) Framework

    International Nuclear Information System (INIS)

    IceProd is a data processing and management framework developed by the IceCube Neutrino Observatory for processing of Monte Carlo simulations and data. IceProd runs as a separate layer on top of middleware or cluster job schedulers and can take advantage of a variety of computing resources including grids such as EGI, OSG, and NorduGrid as well as local clusters running batch systems like HT Condor, PBS, and SGE. This is accomplished by a set of dedicated daemons which process job submission in a coordinated fashion through the use of middleware plug-ins that serve to abstract the details of job submission and job management. IceProd can also manage complex workflow DAGs across distributed computing grids in order to optimize usage of resources. We describe several aspects of IceProd's design and it's applications in collaborative computing environments. We also briefly discuss design aspects of a second generation IceProd, currently being tested in IceCube.

  9. Airborne microorganisms and dust from livestock houses

    OpenAIRE

    Zhao, Y.; Aarnink, A.J.A.; Jong, de, M.C.M.; Groot Koerkamp, P.W.G.

    2011-01-01

    The objective of this study was to evaluate the efficiencies and suitability of samplers for airborne microorganisms and dust, which could be used in practical livestock houses. Two studies were performed: 1) Testing impaction and cyclone pre-separators for dust sampling in livestock houses; 2) Determining sampling efficiencies of four bioaerosol samplers for bacteria and virus. Study 1. The overloading problem of the EU reference impaction pre-separator (IPS) was tested in layer houses and c...

  10. Challenges and Opportunities of Airborne Metagenomics

    OpenAIRE

    Behzad, Hayedeh; Gojobori, Takashi; Mineta, Katsuhiko

    2015-01-01

    Recent metagenomic studies of environments, such as marine and soil, have significantly enhanced our understanding of the diverse microbial communities living in these habitats and their essential roles in sustaining vast ecosystems. The increase in the number of publications related to soil and marine metagenomics is in sharp contrast to those of air, yet airborne microbes are thought to have significant impacts on many aspects of our lives from their potential roles in atmospheric events su...

  11. The impact of fireworks on airborne particles

    OpenAIRE

    R. Vecchi; Bernardoni, V.; Cricchio, D; A. D'Alessandro; P. Fermo; F. Lucarelli(Agenzia Spaziale Italiana); S. Nava; Piazzalunga, A.; Valli, G.

    2008-01-01

    Fireworks are one of the most unusual sources of pollution in atmosphere; although transient, these pollution episodes are responsible for high concentrations of particles (especially metals and organic compounds) and gases. In this paper, results of a study on chemical-physical properties of airborne particles (elements, ions, organic and elemental carbon and particles size distributions) collected during a fireworks episode in Milan (Italy) are reported. Elements typically emitted during py...

  12. Simulating city-level airborne infectious diseases

    OpenAIRE

    Mei, S.; Chen, B; Zhu, Y; Lees, M.H.; Boukhanovsky, A.V.; Sloot, P.M.A.

    2015-01-01

    With the exponential growth in the world population and the constant increase in human mobility, the possible impact of outbreaks of epidemics on cities is increasing, especially in high-density urban areas such as public transportation and transfer points. The volume and proximity of people in these areas can lead to an observed dramatic increase in the transmission of airborne viruses and related pathogens. Due to the critical role these areas play in transmission, it is vital that we have ...

  13. HIGH RESOLUTION AIRBORNE SHALLOW WATER MAPPING

    OpenAIRE

    Steinbacher, F.; M. Pfennigbauer; M. Aufleger; Ullrich, A

    2012-01-01

    In order to meet the requirements of the European Water Framework Directive (EU-WFD), authorities face the problem of repeatedly performing area-wide surveying of all kinds of inland waters. Especially for mid-sized or small rivers this is a considerable challenge imposing insurmountable logistical efforts and costs. It is therefore investigated if large-scale surveying of a river system on an operational basis is feasible by employing airborne hydrographic laser scanning. In cooperati...

  14. Wavelet Based Fractal Analysis of Airborne Pollen

    OpenAIRE

    Degaudenzi, M. E.; Arizmendi, C. M.

    1998-01-01

    The most abundant biological particles in the atmosphere are pollen grains and spores. Self protection of pollen allergy is possible through the information of future pollen contents in the air. In spite of the importance of airborne pol len concentration forecasting, it has not been possible to predict the pollen concentrations with great accuracy, and about 25% of the daily pollen forecasts have resulted in failures. Previous analysis of the dynamic characteristics of atmospheric pollen tim...

  15. MITAS: multisensor imaging technology for airborne surveillance

    Science.gov (United States)

    Thomas, John D.

    1991-08-01

    MITAS, a unique and low-cost solution to the problem of collecting and processing multisensor imaging data for airborne surveillance operations has been developed, MITAS results from integrating the established and proven real-time video processing, target tracking, and sensor management software of TAU with commercially available image exploitation and map processing software. The MITAS image analysis station (IAS) supports airborne day/night reconnaissance and surveillance missions involving low-altitude collection platforms employing a suite of sensors to perform reconnaissance functions against a variety of ground and sea targets. The system will detect, locate, and recognize threats likely to be encountered in support of counternarcotic operations and in low-intensity conflict areas. The IAS is capable of autonomous, near real-time target exploitation and has the appropriate communication links to remotely located IAS systems for more extended analysis of sensor data. The IAS supports the collection, fusion, and processing of three main imaging sensors: daylight imagery (DIS), forward looking infrared (FLIR), and infrared line scan (IRLS). The MITAS IAS provides support to all aspects of the airborne surveillance mission, including sensor control, real-time image enhancement, automatic target tracking, sensor fusion, freeze-frame capture, image exploitation, target data-base management, map processing, remote image transmission, and report generation.

  16. Airborne multispectral detection of regrowth cotton fields

    Science.gov (United States)

    Westbrook, John K.; Suh, Charles P.-C.; Yang, Chenghai; Lan, Yubin; Eyster, Ritchie S.

    2015-01-01

    Effective methods are needed for timely areawide detection of regrowth cotton plants because boll weevils (a quarantine pest) can feed and reproduce on these plants beyond the cotton production season. Airborne multispectral images of regrowth cotton plots were acquired on several dates after three shredding (i.e., stalk destruction) dates. Linear spectral unmixing (LSU) classification was applied to high-resolution airborne multispectral images of regrowth cotton plots to estimate the minimum detectable size and subsequent growth of plants. We found that regrowth cotton fields can be identified when the mean plant width is ˜0.2 m for an image resolution of 0.1 m. LSU estimates of canopy cover of regrowth cotton plots correlated well (r2=0.81) with the ratio of mean plant width to row spacing, a surrogate measure of plant canopy cover. The height and width of regrowth plants were both well correlated (r2=0.94) with accumulated degree-days after shredding. The results will help boll weevil eradication program managers use airborne multispectral images to detect and monitor the regrowth of cotton plants after stalk destruction, and identify fields that may require further inspection and mitigation of boll weevil infestations.

  17. Airborne laser altimeter measurements of landscape topography

    International Nuclear Information System (INIS)

    Measurements of topography can provide a wealth of information on landscape properties for managing hydrologic and geologic systems and conserving natural and agricultural resources. This article discusses the application of an airborne laser altimeter to measure topography and other landscape surface properties. The airborne laser altimeter makes 4000 measurements per second with a vertical recording resolution of 5 cm. Data are collected digitally with a personal computer. A video camera, borehole sighted with the laser, records an image for locating flight lines. GPS data are used to locate flight line positions on the landscape. Laser data were used to measure vegetation canopy topography, height, cover, and distribution and to measure microtopography of the land surface and gullies with depths of 15–20 cm. Macrotopography of landscape profiles for segments up to 4 km were in agreement with available topographic maps but provided more detail. Larger gullies with and without vegetation, and stream channel cross sections and their associated floodplains have also been measured and reported in other publications. Landscape segments for any length could be measured for either micro- or macrotopography. Airborne laser altimeter measurements of landscape profiles can provide detailed information on landscape properties or specific needs that will allow better decisions on the design and location of structures (i.e., roads, pipe, and power lines) and for improving the management and conservation of natural and agricultural landscapes. (author)

  18. Airborne Tactical Free-Electron Laser

    Energy Technology Data Exchange (ETDEWEB)

    Whitney, Roy; Neil, George

    2007-02-01

    The goal of 100 kilowatts (kW) of directed energy from an airborne tactical platform has proved challenging due to the size and weight of most of the options that have been considered. However, recent advances in Free-Electron Lasers appear to offer a solution along with significant tactical advantages: a nearly unlimited magazine, time structures for periods from milliseconds to hours, radar like functionality, and the choice of the wavelength of light that best meets mission requirements. For an Airborne Tactical Free-Electron Laser (ATFEL) on a platforms such as a Lockheed C-130J-30 and airships, the two most challenging requirements, weight and size, can be met by generating the light at a higher harmonic, aggressively managing magnet weights, managing cryogenic heat loads using recent SRF R&D results, and using FEL super compact design concepts that greatly reduce the number of components. The initial R&D roadmap for achieving an ATFEL is provided in this paper. Performing this R&D is expected to further reduce the weight, size and power requirements for the FELs the Navy is currently developing for shipboard applications, as well as providing performance enhancements for the strategic airborne MW class FELs. The 100 kW ATFEL with its tactical advantages may prove sufficiently attractive for early advancement in the queue of deployed FELs.

  19. The 20th century retreat of ice caps in Iceland derived from airborne SAR

    DEFF Research Database (Denmark)

    Magnússon, Eyjólfur; Björnsson, Helgi; Dall, Jørgen; Pálsson, Finnur

    the surges in W-Vatnajokull in the 20th century are observed in the SAR data including the most recent surges in the 1990s. Interestingly no push moraines were observed in front of the surge advance, but the moraines appear when the glaciers start retreating. We estimate that the collective decrease...

  20. Design and performance Assessment of an Airborne Ice Sounding Radar Front-End

    DEFF Research Database (Denmark)

    Hernández, Carlos Cilla; Krozer, Viktor; Vidkjær, Jens;

    2008-01-01

    -phase and out-of-phase power dividers with a relative bandwidth of 20% and more than 75W CW power handling, high power SPDT PIN switch with 90W CW power handling and a 70W CW High efficiency LDMOS power amplifier with ≫60% power-added efficiency. The system comprises also a digital signal generator, a...... digital front-end and a control unit. The system was functionally tested in March 2008 and had a first successful proof-of-concept campaign in Greenland in May 2008....

  1. POLARIS: ESA's airborne ice sounding radar front-end design, performance assessment and first results

    DEFF Research Database (Denmark)

    Hernández, Carlos Cilla; Krozer, Viktor; Vidkjær, Jens;

    2009-01-01

    B noise figure, 160 ns receiver recovery time and -46 dBc 3rd order IMD products. The system comprises also, a digital front-end, a digital signal generator, a microstrip antenna array and a control unit. All the subsystems were integrated, certified and functionally tested, and in May 2008 a successful...

  2. First Results from an Airborne Ka-band SAR Using SweepSAR and Digital Beamforming

    Science.gov (United States)

    Sadowy, Gregory; Ghaemi, Hirad; Hensley, Scott

    2012-01-01

    NASA/JPL has developed SweepSAR technique that breaks typical Synthetic Aperture Radar (SAR) trade space using time-dependent multi-beam DBF on receive. Developing SweepSAR implementation using array-fed reflector for proposed DESDynI Earth Radar Mission concept. Performed first-of-a-kind airborne demonstration of the SweepSAR concept at Ka-band (35.6 GHz). Validated calibration and antenna pattern data sufficient for beam forming in elevation. (1) Provides validation evidence that the proposed Deformation Ecosystem Structure Dynamics of Ice (DESDynI) SAR architecture is sound. (2) Functions well even with large variations in receiver gain / phase. Future plans include using prototype DESDynI SAR digital flight hardware to do the beam forming in real-time onboard the aircraft.

  3. Optical detection and characterization of ice crystals in LACIS

    Science.gov (United States)

    Kiselev, Alexei; Clauß, Tina; Niedermeier, Dennis; Hartmann, Susan; Wex, Heike; Stratmann, Frank

    2010-05-01

    Science and Technology Research Institute at the University of Hertfordshire, UK. The SID instruments have been developed primarily as wing-mounted systems for airborne studies of cloud ice particles. SID3 records the forward scattered light pattern with high angular resolution using an intensified CCD (780 by 582 pixels) at a rate of 20 images per second. In addition to the SID3 capabilities, LISA is able to measure the circular depolarization ratio in the range of scattering angles from 166° to 172°. Whereas particle size, shape and orientation are characterized by the angular distribution of forward-scattered light, the measured value of the circular depolarization can be used to validate the existing theoretical models of light scattering by irregular particles (RTDF, GSVM, T-Matrix, DDA). The first measurements done at the LACIS facility have demonstrated a promising sensitivity of LISA's depolarization channel to the shape of ice crystals. Results showed an increase of the mean circular depolarization ratio from 1.5 (characteristic for the liquid water droplets above 3 µm) to 2.5 for the "just frozen" almost-spherical droplets in the same size range. The presentation will describe details of instruments set up and present some exemplary results from experiments carried out at LACIS and AIDA (KIT) facilities.

  4. A new airborne Polar Nephelometer for the measurement of optical and microphysical cloud properties. Part II: Preliminary tests

    Directory of Open Access Journals (Sweden)

    O. Crépel

    Full Text Available A new optical sensor, the airborne Polar Nephelometer, has been tested in an open wind tunnel. The wind tunnel was operated in cloudy conditions including either cloud water droplets or ice crystals, or a mixture of these particles. The sensor is designed to measure the optical and microphysical parameters of cloud particles sized from a few micrometers to about 500 µm diameter. Basically, the probe measures the scattering phase function of an ensemble of cloud particles which intersect a collimated laser beam near the focal point of a paraboloidal mirror. From the measured scattering phase function the retrieval of the droplet-size spectra and subsequent derived quantities such as liquid water content and size parameters can be calculated using an inversion method. The particle phase discrimination (water droplets/ice particles can be derived from the shape of the scattering phase function and the sensitivity of the probe allows the detection of small ice crystals (typically of 5 µm diameter. The paper describes the preliminary results obtained by the prototype version of the Polar Nephelometer in various cloudy conditions. These results are compared with direct microphysical measurements obtained by usual PMS probes also mounted in the wind tunnel. Complementary results obtained in a cold chamber are presented in order to illustrate the reliability of the Polar Nephelometer in the presence of small ice crystals.

  5. Sea ice-albedo climate feedback mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, J.L.; Curry, J.A. [Univ. of Colorado, Boulder, CO (United States); Ebert, E.E. [Bureau of Meterology Research Center, Melbourne (Australia)

    1995-02-01

    The sea ice-albedo feedback mechanism over the Arctic Ocean multiyear sea ice is investigated by conducting a series of experiments using several one-dimensional models of the coupled sea ice-atmosphere system. In its simplest form, ice-albedo feedback is thought to be associated with a decrease in the areal cover of snow and ice and a corresponding increase in the surface temperature, further decreasing the area cover of snow and ice. It is shown that the sea ice-albedo feedback can operate even in multiyear pack ice, without the disappearance of this ice, associated with internal processes occurring within the multiyear ice pack (e.g., duration of the snow cover, ice thickness, ice distribution, lead fraction, and melt pond characteristics). The strength of the ice-albedo feedback mechanism is compared for several different thermodynamic sea ice models: a new model that includes ice thickness distribution., the Ebert and Curry model, the Mayjut and Untersteiner model, and the Semtner level-3 and level-0 models. The climate forcing is chosen to be a perturbation of the surface heat flux, and cloud and water vapor feedbacks are inoperative so that the effects of the sea ice-albedo feedback mechanism can be isolated. The inclusion of melt ponds significantly strengthens the ice-albedo feedback, while the ice thickness distribution decreases the strength of the modeled sea ice-albedo feedback. It is emphasized that accurately modeling present-day sea ice thickness is not adequate for a sea ice parameterization; the correct physical processes must be included so that the sea ice parameterization yields correct sensitivities to external forcing. 22 refs., 6 figs., 1 tab.

  6. INITIAL COOLING EXPERIMENT (ICE)

    CERN Multimedia

    1978-01-01

    ICE was built in 1977, in a record time of 9 months, using the modified bending magnets of the g-2 muon storage ring. Its purpose was to verify the validity of stochastic and electron cooling for the antiproton project, to be launched in 1978. Already early in 1978, stochastic cooling proved a resounding success, such that the antiproton (p-pbar)project was entirely based on it. Tests of electron cooling followed later: protons of 46 MeV kinetic energy were cooled with an electron beam of 26 kV and 1.3 A. The cage seen prominently in the foreground houses the HV equipment, adjacent to the "cooler" installed in a straight section of the ring. With some modifications, the cooler was later transplanted into LEAR (Low Energy Antiproton Ring) and then, with further modifications, into the AD (Antiproton Decelerator), where it cools antiprotons to this day (2006). See also: 7711282, 7802099, 7908242.

  7. INITIAL COOLING EXPERIMENT (ICE)

    CERN Multimedia

    1979-01-01

    ICE was built in 1977, using the modified bending magnets of the g-2 muon storage ring (see 7405430). Its purpose was to verify the validity of stochastic and electron cooling for the antiproton project. Stochastic cooling proved a resounding success early in 1978 and the antiproton project could go ahead, now entirely based on stochastic cooling. Electron cooling was experimented with in 1979. The 26 kV equipment is housed in the cage to the left of the picture, adjacent to the "e-cooler" located in a straight section of the ring. With some modifications, the cooler was later transplanted into LEAR (Low Energy Antiproton Ring) and then, with further modifications, into the AD (Antiproton Decelerator), where it cools antiprotons to this day (2006). See also: 7711282, 7802099, 7809081.

  8. Survival and ice nucleation activity of bacteria as aerosols in a cloud simulation chamber

    Science.gov (United States)

    Amato, P.; Joly, M.; Schaupp, C.; Attard, E.; Möhler, O.; Morris, C. E.; Brunet, Y.; Delort, A.-M.

    2015-06-01

    The residence time of bacterial cells in the atmosphere is predictable by numerical models. However, estimations of their aerial dispersion as living entities are limited by a lack of information concerning survival rates and behavior in relation to atmospheric water. Here we investigate the viability and ice nucleation (IN) activity of typical atmospheric ice nucleation active bacteria (Pseudomonas syringae and P. fluorescens) when airborne in a cloud simulation chamber (AIDA, Karlsruhe, Germany). Cell suspensions were sprayed into the chamber and aerosol samples were collected by impingement at designated times over a total duration of up to 18 h, and at some occasions after dissipation of a cloud formed by depressurization. Aerosol concentration was monitored simultaneously by online instruments. The cultivability of airborne cells decreased exponentially over time with a half-life time of 250 ± 30 min (about 3.5 to 4.5 h). In contrast, IN activity remained unchanged for several hours after aerosolization, demonstrating that IN activity was maintained after cell death. Interestingly, the relative abundance of IN active cells still airborne in the chamber was strongly decreased after cloud formation and dissipation. This illustrates the preferential precipitation of IN active cells by wet processes. Our results indicate that from 106 cells aerosolized from a surface, one would survive the average duration of its atmospheric journey estimated at 3.4 days. Statistically, this corresponds to the emission of 1 cell that achieves dissemination every ~ 33 min m-2 of cultivated crops fields, a strong source of airborne bacteria. Based on the observed survival rates, depending on wind speed, the trajectory endpoint could be situated several hundreds to thousands of kilometers from the emission source. These results should improve the representation of the aerial dissemination of bacteria in numeric models.

  9. Minimizing Intra-Campaign Biases in Airborne Laser Altimetry By Thorough Calibration of Lidar System Parameters

    Science.gov (United States)

    Sonntag, J. G.; Chibisov, A.; Krabill, K. A.; Linkswiler, M. A.; Swenson, C.; Yungel, J.

    2015-12-01

    Present-day airborne lidar surveys of polar ice, NASA's Operation IceBridge foremost among them, cover large geographical areas. They are often compared with previous surveys over the same flight lines to yield mass balance estimates. Systematic biases in the lidar system, especially those which vary from campaign to campaign, can introduce significant error into these mass balance estimates and must be minimized before the data is released by the instrument team to the larger scientific community. NASA's Airborne Topographic Mapper (ATM) team designed a thorough and novel approach in order to minimize these biases, and here we describe two major aspects of this approach. First, we conduct regular ground vehicle-based surveys of lidar calibration targets, and overfly these targets on a near-daily basis during field campaigns. We discuss our technique for conducting these surveys, in particular the measures we take specifically to minimize systematic height biases in the surveys, since these can in turn bias entire campaigns of lidar data and the mass balance estimates based on them. Second, we calibrate our GPS antennas specifically for each instrument installation in a remote-sensing aircraft. We do this because we recognize that the metallic fuselage of the aircraft can alter the electromagnetic properties of the GPS antenna mounted to it, potentially displacing its phase center by several centimeters and biasing lidar results accordingly. We describe our technique for measuring the phase centers of a GPS antenna installed atop an aircraft, and show results which demonstrate that different installations can indeed alter the phase centers significantly.

  10. Measuring airborne microorganisms and dust from livestock houses

    OpenAIRE

    Yang Zhao, Yang

    2011-01-01

      Airborne transmission has been suspected to be responsible for epidemics of highly infectious disease in livestock production. In such transmission, the pathogenic microorganisms may associate with dust particles. However, the extent to which airborne transmission plays a role in the spread of diseases between farms, and the relationship between microorganisms and dust remain unclear. In order to better understand airborne transmission and to set up effective control techniques, this s...

  11. Sources of airborne microorganisms in the built environment

    OpenAIRE

    Prussin, Aaron J.; Marr, Linsey C.

    2015-01-01

    Abstract Each day people are exposed to millions of bioaerosols, including whole microorganisms, which can have both beneficial and detrimental effects. The next chapter in understanding the airborne microbiome of the built environment is characterizing the various sources of airborne microorganisms and the relative contribution of each. We have identified the following eight major categories of sources of airborne bacteria, viruses, and fungi in the built environment: humans...

  12. Airborne EM applied to environmental geoscience in the UK

    OpenAIRE

    Beamish, D

    2002-01-01

    The British Geological Survey (BGS) has been highlighting the need for modern, multi-sensor airborne geophysical data in the UK. Here David Beamish, geophysicist with the BGS, describes the first trial airborne electromagnetic data acquired and its relevance to environmental geoscience. The lack of modern, multi-sensor (magnetic, radiometric and electromagnetic) data represents one of the most serious gaps in the geoscience knowledge base of the UK, and a national, high resolution airborne su...

  13. First results of airborne trials of a 64-channel laser fluorosensor for oil detection

    International Nuclear Information System (INIS)

    A new 64 channel airborne laser fluorosensor for oil detection has been assembled and tested. The laser environmental airborne fluorosensor (LEAF) consists of a XeCl excimer laser, a 64 spectral channel, range-gated receiver, and an operator console that includes a data logger. LEAF is easily installed in any aircraft having a 10 in. camera hatch. Laser pulses are reflected off the surface being investigated and the fluorescence signals from each pulse are digitized along with other data. A series of flight tests of the LEAF system was conducted over several targets including contaminated and clean ponds at an oil refinery and a test site containing oil spilled on ice, sand, and gravel. LEAF was shown able to detect reproducible and distinct signatures from fresh and aged oily material on various surfaces. Changes in spectral shape due to weathering could be detected using simple algorithms, even from small areas which receive less than 10 laser shots per measurement. 9 refs., 12 figs., 1 tab

  14. SIMPL Laser Altimeter Measurements of Lake Erie Ice Cover: a Pathfinder for ICESat-2

    Science.gov (United States)

    Harding, D. J.; Dabney, P.; Valett, S. R.; Kelly, A.

    2010-12-01

    NASA’s ICESat-2 missions, scheduled for launch in 2015, will make measurements of ice sheet elevation change, sea ice thickness change and vegetation height using a micro-pulse, multi-beam laser altimeter employing single photon ranging at 532 nm (green). Lake Erie ice and snow cover data acquired in February 2009 by the Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) provides pathfinder information enabling improved understanding of this next-generation altimeter measurement approach. SIMPL is an airborne, multi-beam laser altimeter developed through the NASA Earth Science Technology Office Instrument Incubator Program with a focus on cryopshere remote sensing. SIMPL operates at 532 nm and 1064 nm using a micropulse laser, achieving a ranging precision of 8 cm per single photon, and acquires reflected energy parallel and perpendicular to the transmit pulse polarization plane. Approximately 30,000 single photon returns per second are acquired from snow and ice at the nominal flight altitude of 8,000 ft. The resulting two-color information on surface and volume scattering properties enables differentiation of open water and ice types with varying optical properties. For open water, SIMPL data documents laser pulse penetration at 532 nm in the water column, relative to the surface defined by the 1064 nm data. And increasing amount of perpendicularly polarized light with depth relative to the parallel polarization, indicating an increasing fraction of multiply scattered photons, provides a measure of water column optical depth. The observed ice cover types (skim, nias, new grey ice, new grey-white ice) represent the early stages of sea ice formation. Differences in surface roughness and transparency of the ice types are indicated by the 532 nm and 1064 nm perpendicular/parallel depolarization ratio measures of the degree of multiple scattering. The understanding of laser pulse interactions with water, ice and snow using this first-of-its-kind data set

  15. High variability of the heterogeneous ice nucleation potential of oxalic acid dihydrate and sodium oxalate

    Science.gov (United States)

    Wagner, R.; Möhler, O.; Saathoff, H.; Schnaiter, M.; Leisner, T.

    2010-08-01

    The heterogeneous ice nucleation potential of airborne oxalic acid dihydrate and sodium oxalate particles in the deposition and condensation mode has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 244 and 228 K. Previous laboratory studies have highlighted the particular role of oxalic acid dihydrate as the only species amongst a variety of other investigated dicarboxylic acids to be capable of acting as a heterogeneous ice nucleus in both the deposition and immersion mode. We could confirm a high deposition mode ice activity for 0.03 to 0.8 μm sized oxalic acid dihydrate particles that were either formed by nucleation from a gaseous oxalic acid/air mixture or by rapid crystallisation of highly supersaturated aqueous oxalic acid solution droplets. The critical saturation ratio with respect to ice required for deposition nucleation was found to be less than 1.1 and the size-dependent ice-active fraction of the aerosol population was in the range from 0.1 to 22%. In contrast, oxalic acid dihydrate particles that had crystallised from less supersaturated solution droplets and had been allowed to slowly grow in a supersaturated environment from still unfrozen oxalic acid solution droplets over a time period of several hours were found to be much poorer heterogeneous ice nuclei. We speculate that under these conditions a crystal surface structure with less-active sites for the initiation of ice nucleation was generated. Such particles partially proved to be almost ice-inactive in both the deposition and condensation mode. At times, the heterogeneous ice nucleation ability of oxalic acid dihydrate significantly changed when the particles had been processed in preceding cloud droplet activation steps. Such behaviour was also observed for the second investigated species, namely sodium oxalate. Our experiments address the atmospheric scenario that coating layers

  16. High variability of the heterogeneous ice nucleation potential of oxalic acid dihydrate and sodium oxalate

    Directory of Open Access Journals (Sweden)

    R. Wagner

    2010-04-01

    Full Text Available The heterogeneous ice nucleation potential of airborne oxalic acid dihydrate and sodium oxalate particles in the deposition and condensation mode has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 244 and 228 K. Previous laboratory studies have highlighted the particular role of oxalic acid dihydrate as the only species amongst a variety of other investigated dicarboxylic acids to be capable of acting as a heterogeneous ice nucleus in both the deposition and immersion mode. We could confirm a high deposition mode ice activity for 0.03 to 0.8 μm sized oxalic acid dihydrate particles that were either formed by nucleation from a gaseous oxalic acid/air mixture or by rapid crystallisation of highly supersaturated aqueous oxalic acid solution droplets. The critical saturation ratio with respect to ice required for deposition nucleation was found to be less than 1.1 and the size-dependent ice-active fraction of the aerosol population was in the range from 0.1 to 22%. In contrast, oxalic acid dihydrate particles that had crystallised from less supersaturated solution droplets and had been allowed to slowly grow in a supersaturated environment from still unfrozen oxalic acid solution droplets over a time period of several hours were found to be much poorer heterogeneous ice nuclei. We speculate that under these conditions a crystal surface structure with less-active sites for the initiation of ice nucleation was generated. Such particles partially proved to be almost ice-inactive in both the deposition and condensation mode. At times, the heterogeneous ice nucleation ability of oxalic acid dihydrate significantly changed when the particles had been processed in preceding cloud droplet activation steps. Such behaviour was also observed for the second investigated species, namely sodium oxalate. Our experiments address the atmospheric scenario

  17. High variability of the heterogeneous ice nucleation potential of oxalic acid dihydrate and sodium oxalate

    Directory of Open Access Journals (Sweden)

    R. Wagner

    2010-08-01

    Full Text Available The heterogeneous ice nucleation potential of airborne oxalic acid dihydrate and sodium oxalate particles in the deposition and condensation mode has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 244 and 228 K. Previous laboratory studies have highlighted the particular role of oxalic acid dihydrate as the only species amongst a variety of other investigated dicarboxylic acids to be capable of acting as a heterogeneous ice nucleus in both the deposition and immersion mode. We could confirm a high deposition mode ice activity for 0.03 to 0.8 μm sized oxalic acid dihydrate particles that were either formed by nucleation from a gaseous oxalic acid/air mixture or by rapid crystallisation of highly supersaturated aqueous oxalic acid solution droplets. The critical saturation ratio with respect to ice required for deposition nucleation was found to be less than 1.1 and the size-dependent ice-active fraction of the aerosol population was in the range from 0.1 to 22%. In contrast, oxalic acid dihydrate particles that had crystallised from less supersaturated solution droplets and had been allowed to slowly grow in a supersaturated environment from still unfrozen oxalic acid solution droplets over a time period of several hours were found to be much poorer heterogeneous ice nuclei. We speculate that under these conditions a crystal surface structure with less-active sites for the initiation of ice nucleation was generated. Such particles partially proved to be almost ice-inactive in both the deposition and condensation mode. At times, the heterogeneous ice nucleation ability of oxalic acid dihydrate significantly changed when the particles had been processed in preceding cloud droplet activation steps. Such behaviour was also observed for the second investigated species, namely sodium oxalate. Our experiments address the atmospheric scenario

  18. IceTop: The surface component of IceCube

    International Nuclear Information System (INIS)

    IceTop, the surface component of the IceCube Neutrino Observatory at the South Pole, is an air shower array with an area of 1 km2. The detector allows a detailed exploration of the mass composition of primary cosmic rays in the energy range from about 100 TeV to 1 EeV by exploiting the correlation between the shower energy measured in IceTop and the energy deposited by muons in the deep ice. In this paper we report on the technical design, construction and installation, the trigger and data acquisition systems as well as the software framework for calibration, reconstruction and simulation. Finally the first experience from commissioning and operating the detector and the performance as an air shower detector will be discussed.

  19. IceTop: The surface component of IceCube

    CERN Document Server

    Abbasi, R; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Altmann, D; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Baum, V; Bay, R; Beattie, K; Beatty, J J; Bechet, S; Tjus, J Becker; Becker, K -H; Bell, M; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bose, D; Böser, S; Botner, O; Brayeur, L; Brown, A M; Bruijn, R; Brunner, J; Buitink, S; Caballero-Mora, K S; Carson, M; Casey, J; Casier, M; Chirkin, D; Christy, B; Clevermann, F; Cohen, S; Cowen, D F; Silva, A H Cruz; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Díaz-Vélez, J C; Dreyer, J; Dumm, J P; Dunkman, M; Eagan, R; Eisch, J; Elliott, C; Ellsworth, R W; Engdegård, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Franke, R; Frantzen, K; Fuchs, T; Gaisser, T K; Gallagher, J; Gerhardt, L; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Goodman, J A; Góra, D; Grant, D; Groß, A; Grullon, S; Gurtner, M; Ha, C; Ismail, A Haj; Hallgren, A; Halzen, F; Hanson, K; Heereman, D; Heimann, P; Heinen, D; Helbing, K; Hellauer, R; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Japaridze, G S; Jlelati, O; Johansson, H; Kappes, A; Karg, T; Karle, A; Kiryluk, J; Kislat, F; Kläs, J; Klein, S R; Klepser, S; Köhne, J -H; Kohnen, G; Kolanoski, H; Köpke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Krasberg, M; Kroll, G; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Laihem, K; Landsman, H; Larson, M J; Lauer, R; Lesiak-Bzdak, M; Lünemann, J; Madsen, J; Maruyama, R; Mase, K; Matis, H S; McDermott, A; McNally, F; Meagher, K; Merck, M; Mészáros, P; Meures, T; Miarecki, S; Middell, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Movit, S M; Nahnhauer, R; Naumann, U; Nießen, P; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Panknin, S; Paul, L; Pepper, J A; Heros, C Pérez de los; Pieloth, D; Pirk, N; Posselt, J; Price, P B; Przybylski, G T; Rädel, L; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Richman, M; Riedel, B; Rodrigues, J P; Roth, J; Rothmaier, F; Rott, C; Roucelle, C; Ruhe, T; Rutledge, D; Ruzybayev, B; Ryckbosch, D; Saba, S M; Salameh, T; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Scheel, M; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schöneberg, S; Schönherr, L; Schönwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Seo, S H; Sestayo, Y; Seunarine, S; Shulman, L; Smith, M W E; Soiron, M; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stasik, A; Stezelberger, T; Stokstad, R G; Stößl, A; Stoyanov, S; Strahler, E A; Ström, R; Sulanke, K-H; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Usner, M; van der Drift, D; van Eijndhoven, N; Van Overloop, A; van Santen, J; Vehring, M; Voge, M; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Wasserman, R; Weaver, Ch; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, C; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zilles, A; Zoll, M

    2012-01-01

    IceTop, the surface component of the IceCube Neutrino Observatory at the South Pole, is an air shower array with an area of 1 km2. The detector allows a detailed exploration of the mass composition of primary cosmic rays in the energy range from about 100 TeV to 1 EeV by exploiting the correlation between the shower energy measured in IceTop and the energy deposited by muons in the deep ice. In this paper we report on the technical design, construction and installation, the trigger and data acquisition systems as well as the software framework for calibration, reconstruction and simulation. Finally the first experience from commissioning and operating the detector and the performance as an air shower detector will be discussed.

  20. Wing airfoil ice accretion model

    Czech Academy of Sciences Publication Activity Database

    Hoření, Bohumír; Horák, V.

    Bucharest : Military technical academy, 2005, 3.56-3.62. ISBN 973-640-074-3. [Internationally attended scientific conference /31./ : modern technologies in the XXI century. Bucharest (RO), 03.11.2005-04.11.2005] R&D Projects: GA AV ČR KSK2076106; GA ČR GA103/04/0970; GA MPO FT-TA/026 Institutional research plan: CEZ:AV0Z2060917 Keywords : aircraft icing * ice accretion * icing modell Subject RIV: JU - Aeronautics, Aerodynamics, Aircrafts

  1. Ice Nucleation Activity in Lichens

    OpenAIRE

    Kieft, Thomas L.

    1988-01-01

    A newly discovered form of biological ice nucleus associated with lichens is described. Ice nucleation spectra of a variety of lichens from the southwestern United States were measured by the drop-freezing method. Several epilithic lichen samples of the genera Rhizoplaca, Xanthoparmelia, and Xanthoria had nuclei active at temperatures as warm as −2.3°C and had densities of 2.3 × 106 to more than 1 × 108 nuclei g−1 at −5°C (2 to 4 orders of magnitude higher than any plants infected with ice nu...

  2. Rewritable artificial magnetic charge ice

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yong-Lei; Xiao, Zhili; Snezhko, Alexey; Xu, Jing; Ocola, Leonidas E.; Divan, Ralu; Pearson, John E.; Crabtree, George W.; Kwok, Wai-Kwong

    2016-05-20

    Artificial ices enable the study of geometrical frustration by design and through direct observation. However, it has proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. We designed an artificial spin structure that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. We also developed a technique to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multifunctionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice could provide a setting for designing magnetic monopole defects, tailoring magnonics, and controlling the properties of other two-dimensional materials.

  3. Rewritable artificial magnetic charge ice

    Science.gov (United States)

    Wang, Yong-Lei; Xiao, Zhi-Li; Snezhko, Alexey; Xu, Jing; Ocola, Leonidas E.; Divan, Ralu; Pearson, John E.; Crabtree, George W.; Kwok, Wai-Kwong

    2016-05-01

    Artificial ices enable the study of geometrical frustration by design and through direct observation. However, it has proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. We designed an artificial spin structure that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. We also developed a technique to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multifunctionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice could provide a setting for designing magnetic monopole defects, tailoring magnonics, and controlling the properties of other two-dimensional materials.

  4. Influence of winter sea-ice motion on summer ice cover in the Arctic

    Directory of Open Access Journals (Sweden)

    Noriaki Kimura

    2013-11-01

    Full Text Available Summer sea-ice cover in the Arctic varies largely from year to year owing to several factors. This study examines one such factor, the relationship between interannual difference in winter ice motion and ice area in the following summer. A daily-ice velocity product on a 37.5-km resolution grid is prepared using the satellite passive microwave sensor Advanced Microwave Scanning Radiometer—Earth Observing System data for the nine years of 2003–2011. Derived daily-ice motion reveals the dynamic modification of the winter ice cover. The winter ice divergence/convergence is strongly related to the summer ice cover in some regions; the correlation coefficient between the winter ice convergence and summer ice area ranges between 0.5 and 0.9 in areas with high interannual variability. This relation implies that the winter ice redistribution controls the spring ice thickness and the summer ice cover.

  5. Ice911 Research: Preserving and Rebuilding Multi-Year Ice

    Science.gov (United States)

    Field, L. A.; Chetty, S.; Manzara, A.

    2013-12-01

    A localized surface albedo modification technique is being developed that shows promise as a method to increase multi-year ice using reflective floating materials, chosen so as to have low subsidiary environmental impact. Multi-year ice has diminished rapidly in the Arctic over the past 3 decades (Riihela et al, Nature Climate Change, August 4, 2013) and this plays a part in the continuing rapid decrease of summer-time ice. As summer-time ice disappears, the Arctic is losing its ability to act as the earth's refrigeration system, and this has widespread climatic effects, as well as a direct effect on sea level rise, as oceans heat, and once-land-based ice melts into the sea. We have tested the albedo modification technique on a small scale over five Winter/Spring seasons at sites including California's Sierra Nevada Mountains, a Canadian lake, and a small man-made lake in Minnesota, using various materials and an evolving array of instrumentation. The materials can float and can be made to minimize effects on marine habitat and species. The instrumentation is designed to be deployed in harsh and remote locations. Localized snow and ice preservation, and reductions in water heating, have been quantified in small-scale testing. Climate modeling is underway to analyze the effects of this method of surface albedo modification in key areas on the rate of oceanic and atmospheric temperature rise. We are also evaluating the effects of snow and ice preservation for protection of infrastructure and habitat stabilization. This paper will also discuss a possible reduction of sea level rise with an eye to quantification of cost/benefit. The most recent season's experimentation on a man-made private lake in Minnesota saw further evolution in the material and deployment approach. The materials were successfully deployed to shield underlying snow and ice from melting; applications of granular materials remained stable in the face of local wind and storms. Localized albedo

  6. ICE911 Research: Preserving and Rebuilding Reflective Ice

    Science.gov (United States)

    Field, L. A.; Chetty, S.; Manzara, A.; Venkatesh, S.

    2014-12-01

    We have developed a localized surface albedo modification technique that shows promise as a method to increase reflective multi-year ice using floating materials, chosen so as to have low subsidiary environmental impact. It is now well-known that multi-year reflective ice has diminished rapidly in the Arctic over the past 3 decades and this plays a part in the continuing rapid decrease of summer-time ice. As summer-time bright ice disappears, the Arctic is losing its ability to reflect summer insolation, and this has widespread climatic effects, as well as a direct effect on sea level rise, as oceans heat and once-land-based ice melts into the sea. We have tested the albedo modification technique on a small scale over six Winter/Spring seasons at sites including California's Sierra Nevada Mountains, a Canadian lake, and a small man-made lake in Minnesota, using various materials and an evolving array of instrumentation. The materials can float and can be made to minimize effects on marine habitat and species. The instrumentation is designed to be deployed in harsh and remote locations. Localized snow and ice preservation, and reductions in water heating, have been quantified in small-scale testing. We have continued to refine our material and deployment approaches, and we have had laboratory confirmation by NASA. In the field, the materials were successfully deployed to shield underlying snow and ice from melting; applications of granular materials remained stable in the face of local wind and storms. We are evaluating the effects of snow and ice preservation for protection of infrastructure and habitat stabilization, and we are concurrently developing our techniques to aid in water conservation. Localized albedo modification options such as those being studied in this work may act to preserve ice, glaciers, permafrost and seasonal snow areas, and perhaps aid natural ice formation processes. If this method is deployed on a large enough scale, it could conceivably

  7. Arctic Sea Ice Freeboard from Icebridge Acquisitions in 2009: Estimates and Comparisons with ICEsat

    Science.gov (United States)

    Kwok, R.; Cunningham, Glenn F.; Manizade, S. S.; Krabill, W. B.

    2012-01-01

    During the spring of 2009, the Airborne Topographic Mapper (ATM) system on the IceBridge mission acquired cross-basin surveys of surface elevations of Arctic sea ice. In this paper, the total freeboard derived from four 2000 km transects are examined and compared with those from the 2009 ICESat campaign. Total freeboard, the sum of the snow and ice freeboards, is the elevation of the air-snow interface above the local sea surface. Prior to freeboard retrieval, signal dependent range biases are corrected. With data from a near co-incident outbound and return track on 21 April, we show that our estimates of the freeboard are repeatable to within 4 cm but dependent locally on the density and quality of sea surface references. Overall difference between the ATM and ICESat freeboards for the four transects is 0.7 (8.5) cm (quantity in bracket is standard deviation), with a correlation of 0.78 between the data sets of one hundred seventy-eight 50 km averages. This establishes a level of confidence in the use of ATM freeboards to provide regional samplings that are consistent with ICESat. In early April, mean freeboards are 41 cm and 55 cm over first year and multiyear sea ice (MYI), respectively. Regionally, the lowest mean ice freeboard (28 cm) is seen on 5 April where the flight track sampled the large expanse of seasonal ice in the western Arctic. The highest mean freeboard (71 cm) is seen in the multiyear ice just west of Ellesmere Island from 21 April. The relatively large unmodeled variability of the residual sea surface resolved by ATM elevations is discussed.

  8. Towards airborne nanoparticle mass spectrometry with nanomechanical string resonators

    DEFF Research Database (Denmark)

    Schmid, Silvan; Kurek, Maksymilian; Boisen, Anja

    2013-01-01

    airborne nanoparticle sensors. Recently, nanomechanical mass spectrometry was established. One of the biggest challenges of nanomechanical sensors is the low efficiency of diffusion-based sampling. We developed an inertial-based sampling method that enables the efficient sampling of airborne nanoparticles...... first bending mode. Mass spectrometry of airborne nanoparticles requires the simultaneous operation in the first and second mode, which can be implemented in the transduction scheme of the resonator. The presented results lay the cornerstone for the realization of a portable airborne nanoparticle mass...

  9. High-Performance Airborne Optical Carbon Dioxide Analyzer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Environmental species measurement on airborne atmospheric research craft is a demanding application for optical sensing techniques. Yet optical techniques offer...

  10. Monitoring under ice phyto- and zooplankton blooms with the Nereid Under Ice remotely operated vehicle

    OpenAIRE

    Fernández-Méndez, Mar; Laney, Samuel R.; Katlein, Christian; Whitcomb, Louis L.; Elliott, Stephen; Jakuba, Mike V.; Boetius, Antje; German, Christopher R.

    2015-01-01

    The perennially ice-covered Central Arctic is changing rapidly due to extensive sea-ice retreat and the loss of multiyear ice. The thinning of the ice allows more light to reach the water column enhancing productivity. These changes in the under ice ecosystem can lead to under-ice phytoplankton blooms which may increase grazing and carbon export. However, our knowledge of the interactions between sea ice, sub-ice and under-ice communities is still poor, especially in high latitudes. A key lim...

  11. Airframe Icing Research Gaps: NASA Perspective

    Science.gov (United States)

    Potapczuk, Mark

    2009-01-01

    qCurrent Airframe Icing Technology Gaps: Development of a full 3D ice accretion simulation model. Development of an improved simulation model for SLD conditions. CFD modeling of stall behavior for ice-contaminated wings/tails. Computational methods for simulation of stability and control parameters. Analysis of thermal ice protection system performance. Quantification of 3D ice shape geometric characteristics Development of accurate ground-based simulation of SLD conditions. Development of scaling methods for SLD conditions. Development of advanced diagnostic techniques for assessment of tunnel cloud conditions. Identification of critical ice shapes for aerodynamic performance degradation. Aerodynamic scaling issues associated with testing scale model ice shape geometries. Development of altitude scaling methods for thermal ice protections systems. Development of accurate parameter identification methods. Measurement of stability and control parameters for an ice-contaminated swept wing aircraft. Creation of control law modifications to prevent loss of control during icing encounters. 3D ice shape geometries. Collection efficiency data for ice shape geometries. SLD ice shape data, in-flight and ground-based, for simulation verification. Aerodynamic performance data for 3D geometries and various icing conditions. Stability and control parameter data for iced aircraft configurations. Thermal ice protection system data for simulation validation.

  12. Transmission line icing measurement on photogrammetry method

    Science.gov (United States)

    Huang, Huan; Ma, Xiaohong; Zhao, Lijin; Du, Hao; Luo, Hong; Mao, Xianyin; Tang, Min; Liu, Yawen

    2015-12-01

    Icing thickness parameter is the basic data for power sector to make decision for icing accident prevention. In this paper, a transmission line icing measurement method is proposed. It used the photogrammetry method to realize icing parameters measurement through the integration of high resolution camera, laser range finder and inertial measurement unit. Compared with traditional icing measurement method, this method is flexible and is the effective supplement of the fixed icing detection terminal. And its high accuracy measurement guarantees the reliability of the icing thickness parameters.

  13. Trace elements in a dated ice core from Antarctica

    International Nuclear Information System (INIS)

    Aerosol particles from both natural and anthropogenic sources are emitted into the atmosphere and transported by wind systems by various mechanisms. Once airborne, the particles, which contain various trace elements, accumulate on the earth's surface as either condensation nuclei or by dry fallout processes. In the polar regions, these particles are incorporated and deposited in snow layers in sequential time-unit increments. The trace analysis of elements contained in dated annual snow layers provides a measure of the elemental chemistry content of the atmosphere for the same time interval. A 164-m-deep, 10-cm-diam ice core was obtained at Byrd Station, Antarctica, in November 1989. Other physical and chemistry studies on this ice core have identified its detailed chronology in annual increments for the past 1360 yr. This study presents the results of the instrumental neutron activation analysis (INAA) measurements made on 26 individually dated samples of this core, selected between the 6.43- and 118.15-m depths

  14. Holocene accumulation and ice flow near the West Antarctic Ice Sheet Divide ice core site

    Science.gov (United States)

    Koutnik, Michelle R.; Fudge, T. J.; Conway, Howard; Waddington, Edwin D.; Neumann, Thomas A.; Cuffey, Kurt M.; Buizert, Christo; Taylor, Kendrick C.

    2016-05-01

    The West Antarctic Ice Sheet Divide Core (WDC) provided a high-resolution climate record from near the Ross-Amundsen Divide in Central West Antarctica. In addition, radar-detected internal layers in the vicinity of the WDC site have been dated directly from the ice core to provide spatial variations in the age structure of the region. Using these two data sets together, we first infer a high-resolution Holocene accumulation-rate history from 9.2 kyr of the ice-core timescale and then confirm that this climate history is consistent with internal layers upstream of the core site. Even though the WDC was drilled only 24 km from the modern ice divide, advection of ice from upstream must be taken into account. We evaluate histories of accumulation rate by using a flowband model to generate internal layers that we compare to observed layers. Results show that the centennially averaged accumulation rate was over 20% lower than modern at 9.2 kyr before present (B.P.), increased by 40% from 9.2 to 2.3 kyr B.P., and decreased by at least 10% over the past 2 kyr B.P. to the modern values; these Holocene accumulation-rate changes in Central West Antarctica are larger than changes inferred from East Antarctic ice-core records. Despite significant changes in accumulation rate, throughout the Holocene the regional accumulation pattern has likely remained similar to today, and the ice-divide position has likely remained on average within 5 km of its modern position. Continent-scale ice-sheet models used for reconstructions of West Antarctic ice volume should incorporate this accumulation history.

  15. Radiative properties of ice clouds

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, D.L.; Koracin, D.; Carter, E. [Desert Research Institute, Reno, NV (United States)

    1996-04-01

    A new treatment of cirrus cloud radiative properties has been developed, based on anomalous diffraction theory (ADT), which does not parameterize size distributions in terms of an effective radius. Rather, is uses the size distribution parameters directly, and explicitly considers the ice particle shapes. There are three fundamental features which characterize this treatment: (1) the ice path radiation experiences as it travels through an ice crystal is parameterized, (2) only determines the amount of radiation scattered and absorbed, and (3) as in other treatments, the projected area of the size distribution is conserved. The first two features are unique to this treatment, since it does not convert the ice particles into equivalent volume or area spheres in order to apply Mie theory.

  16. Melting of Ice under Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Schwegler, E; Sharma, M; Gygi, F; Galli, G

    2008-07-31

    The melting of ice under pressure is investigated with a series of first principles molecular dynamics simulations. In particular, a two-phase approach is used to determine the melting temperature of the ice-VII phase in the range of 10 to 50 GPa. Our computed melting temperatures are consistent with existing diamond anvil cell experiments. We find that for pressures between 10 to 40 GPa, ice melts as a molecular solid. For pressures above {approx}45 GPa there is a sharp increase in the slope of the melting curve due to the presence of molecular dissociation and proton diffusion in the solid, prior to melting. The onset of significant proton diffusion in ice-VII as a function of increasing temperature is found to be gradual and bears many similarities to that of a type-II superionic solid.

  17. Let's Make Metric Ice Cream

    Science.gov (United States)

    Zimmerman, Marianna

    1975-01-01

    Describes a classroom activity which involved sixth grade students in a learning situation including making ice cream, safety procedures in a science laboratory, calibrating a thermometer, using metric units of volume and mass. (EB)

  18. Greenland Ice Sheet Mass Balance

    Science.gov (United States)

    Reeh, N.

    1984-01-01

    Mass balance equation for glaciers; areal distribution and ice volumes; estimates of actual mass balance; loss by calving of icebergs; hydrological budget for Greenland; and temporal variations of Greenland mass balance are examined.

  19. Hydrodynamics and Thermodynamics of Ice Particle Accretion

    OpenAIRE

    Kintea, Daniel Martin

    2016-01-01

    Icing in warm environments, e.g. in aircraft engines or heated measurement probes, occurs if airplanes fly through areas with high amounts of atmospheric ice crystals. Ingested into the warm engine, they start to melt, resulting in an airflow laden with mixed-phase particles consisting of water and ice. Liquid water deposits on component surfaces, which enables ice particles to adhere to them, forming ice accretion of considerable thickness. Such an accretion reduces reliability, power and ef...

  20. A study of ice response spectra

    Institute of Scientific and Technical Information of China (English)

    LIU Chunguang; JIA Lingling

    2009-01-01

    Some problems concerning the ice forces and ice response spectra are studied from both theoretical and practical points of view. On the basis of structural analysis,the analysis method of ice response spectra is proposed, since it plays an important role in the prediction of maximum structural response in cold regions. And it is illustrated that it is easy to study the structural response to ice using the ice response spectra.

  1. Satellite altimeter remote sensing of ice caps

    OpenAIRE

    Rinne, Eero Juhani

    2011-01-01

    This thesis investigates the use of satellite altimetry techniques for measuring surface elevation changes of ice caps. Two satellite altimeters, Radar Altimeter 2 (RA-2) and Geoscience Laser Altimeter System (GLAS) are used to assess the surface elevation changes of three Arctic ice caps. This is the first time the RA-2 has been used to assess the elevation changes of ice caps - targets much smaller than the ice sheets which are the instrument’s primary land ice targets. Algor...

  2. Ice thickness measurements by Raman scattering

    CERN Document Server

    Pershin, Sergey M; Klinkov, Vladimir K; Yulmetov, Renat N; Bunkin, Alexey F

    2014-01-01

    A compact Raman LIDAR system with a spectrograph was used for express ice thickness measurements. The difference between the Raman spectra of ice and liquid water is employed to locate the ice-water interface while elastic scattering was used for air-ice surface detection. This approach yields an error of only 2 mm for an 80-mm-thick ice sample, indicating that it is promising express noncontact thickness measurements technique in field experiments.

  3. Simulating Ice Accretion Effects on Engine Performance

    Science.gov (United States)

    Jorgenson, Philip C. E.; Veres, Joseph P.; Wright, William

    2011-01-01

    Develop a modeling tool that can be used to predict the onset of engine icing due to ice crystal ingestion. The tool will be capable of modeling the effects of ice build up as well as its effect on engine performance. Perform a parametric study of an engine with simulated ice blockage effects at altitude conditions. Using the tool, estimate the effect of blockage in the low pressure compressor due to ice buildup (accretion), and its effects on engine performance.

  4. Ice sheet hydrology - a review

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Peter; Naeslund, Jens-Ove [Dept. of Physical Geography and Quaternary Geology, Stockholm Univ., Stockholm (Sweden); Rodhe, Lars [Geological Survey of Sweden, Uppsala (Sweden)

    2007-03-15

    This report summarizes the theoretical knowledge on water flow in and beneath glaciers and ice sheets and how these theories are applied in models to simulate the hydrology of ice sheets. The purpose is to present the state of knowledge and, perhaps more importantly, identify the gaps in our understanding of ice sheet hydrology. Many general concepts in hydrology and hydraulics are applicable to water flow in glaciers. However, the unique situation of having the liquid phase flowing in conduits of the solid phase of the same material, water, is not a commonly occurring phenomena. This situation means that the heat exchange between the phases and the resulting phase changes also have to be accounted for in the analysis. The fact that the solidus in the pressure-temperature dependent phase diagram of water has a negative slope provides further complications. Ice can thus melt or freeze from both temperature and pressure variations or variations in both. In order to provide details of the current understanding of water flow in conjunction with deforming ice and to provide understanding for the development of ideas and models, emphasis has been put on the mathematical treatments, which are reproduced in detail. Qualitative results corroborating theory or, perhaps more often, questioning the simplifications made in theory, are also given. The overarching problem with our knowledge of glacier hydrology is the gap between the local theories of processes and the general flow of water in glaciers and ice sheets. Water is often channelized in non-stationary conduits through the ice, features which due to their minute size relative to the size of glaciers and ice sheets are difficult to incorporate in spatially larger models. Since the dynamic response of ice sheets to global warming is becoming a key issue in, e.g. sea-level change studies, the problems of the coupling between the hydrology of an ice sheet and its dynamics is steadily gaining interest. New work is emerging

  5. Ice sheet hydrology - a review

    International Nuclear Information System (INIS)

    This report summarizes the theoretical knowledge on water flow in and beneath glaciers and ice sheets and how these theories are applied in models to simulate the hydrology of ice sheets. The purpose is to present the state of knowledge and, perhaps more importantly, identify the gaps in our understanding of ice sheet hydrology. Many general concepts in hydrology and hydraulics are applicable to water flow in glaciers. However, the unique situation of having the liquid phase flowing in conduits of the solid phase of the same material, water, is not a commonly occurring phenomena. This situation means that the heat exchange between the phases and the resulting phase changes also have to be accounted for in the analysis. The fact that the solidus in the pressure-temperature dependent phase diagram of water has a negative slope provides further complications. Ice can thus melt or freeze from both temperature and pressure variations or variations in both. In order to provide details of the current understanding of water flow in conjunction with deforming ice and to provide understanding for the development of ideas and models, emphasis has been put on the mathematical treatments, which are reproduced in detail. Qualitative results corroborating theory or, perhaps more often, questioning the simplifications made in theory, are also given. The overarching problem with our knowledge of glacier hydrology is the gap between the local theories of processes and the general flow of water in glaciers and ice sheets. Water is often channelized in non-stationary conduits through the ice, features which due to their minute size relative to the size of glaciers and ice sheets are difficult to incorporate in spatially larger models. Since the dynamic response of ice sheets to global warming is becoming a key issue in, e.g. sea-level change studies, the problems of the coupling between the hydrology of an ice sheet and its dynamics is steadily gaining interest. New work is emerging

  6. Electromelting of Confined Monolayer Ice

    OpenAIRE

    Qiu, Hu; Guo, Wanlin

    2013-01-01

    In sharp contrast to the prevailing view that electric fields promote water freezing, here we show by molecular dynamics simulations that monolayer ice confined between two parallel plates can melt into liquid water under perpendicularly applied electric field. The melting temperature of the monolayer ice decreases with the increasing strength of the external field due to field-induced disruption of the water-wall interaction induced well-ordered network of hydrogen bond. This electromelting ...

  7. Rewritable Artificial Magnetic Charge Ice

    OpenAIRE

    Wang, Yong-Lei; Xiao, Zhi-Li; Snezhko, Alexey; Xu, Jing; Ocola, Leonidas E.; Divan, Ralu; Pearson, John E.; Crabtree, George W.; Kwok, Wai-Kwong

    2016-01-01

    Artificial ices enable the study of geometrical frustration by design and through direct observation. However, it has proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. We designed an artificial spin structure that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. We also developed a technique to precisely manipulate the local magnetic charge state...

  8. Potassium chloride-bearing ice VII and ice planet dynamics

    Science.gov (United States)

    Frank, Mark R.; Scott, Henry P.; Aarestad, Elizabeth; Prakapenka, Vitali B.

    2016-02-01

    Accurate modeling of planetary interiors requires that the pressure-volume-temperature (PVT) properties of phases present within the body be well understood. The high-pressure polymorphs of H2O have been studied extensively due to the abundance of ice phases in icy moons and, likely, vast number of extra-solar planetary bodies, with only select studies evaluating impurity-laden ices. In this study, ice formed from a 1.6 mol percent KCl-bearing aqueous solution was studied up to 32.89 ± 0.19 GPa and 625 K, and the incorporation of K+ and Cl- ionic impurities into the ice VII structure was documented. The compression data at 295 K were fit with a third order Birch-Murnaghan equation of state and yielded a bulk modulus (KT0), its pressure derivative (KT0‧), and zero pressure volume (V0) of 24.7 ± 0.9 GPa, 4.44 ± 0.09, and 39.2 ± 0.2 Å3, respectively. The impurity-laden ice was found to be 6-8% denser than ice VII formed from pure H2O. Thermal expansion coefficients were also determined for several isothermal compression curves at elevated temperatures, and a PVT equation of state was obtained. The melting curve of ice VII with incorporated K+ and Cl- was estimated by fitting experimental data up to 10.2 ± 0.4 GPa, where melting occurred at 625 K, to the Simon-Glatzel equation. The melting curve of this impurity-laden ice is systematically depressed relative to that of pure H2O by approximately 45 K and 80 K at 4 and 11 GPa, respectively. A portion of the K+ and Cl- contained within the ice VII structure was observed to exsolve with increasing temperature. This suggests that an internal differentiating process could concentrate a K-rich phase deep within H2O-rich planets, and we speculate that this could supply an additional source of heat through the radioactive decay of 40K. Our data illustrate ice VII can incorporate significant concentrations of K+ and Cl- and increasing the possibility of deep-sourced and solute-rich plumes in moderate to large sized H2O

  9. Better constraints on the sea-ice state using global sea-ice data assimilation

    Directory of Open Access Journals (Sweden)

    P. Mathiot

    2012-06-01

    Full Text Available Short-term and decadal sea-ice prediction systems need a realistic initial state, generally obtained using ice-ocean model simulations with data assimilation. However, only sea-ice concentration and velocity data are currently assimilated. In this work, an Ensemble Kalman Filter system is used to assimilate observed ice concentration and freeboard (i.e. thickness of emerged sea ice data into a global coupled ocean–sea-ice model. The impact and effectiveness of our data assimilation system is assessed in two steps: firstly, through the assimilation of synthetic data (i.e., model-generated data and, secondly, through the assimilation of satellite data. While ice concentrations are available daily, freeboard data used in this study are only available during six one-month periods spread over 2005–2007. Our results show that the simulated Arctic and Antarctic sea-ice extents are improved by the assimilation of synthetic ice concentration data. Assimilation of synthetic ice freeboard data improves the simulated sea-ice thickness field. Using real ice concentration data enhances the model realism in both hemispheres. Assimilation of ice concentration data significantly improves the total hemispheric sea-ice extent all year long, especially in summer. Combining the assimilation of ice freeboard and concentration data leads to better ice thickness, but does not further improve the ice extent. Moreover, the improvements in sea-ice thickness due to the assimilation of ice freeboard remain visible well beyond the assimilation periods.

  10. Extraction of Ice Sheet Layers from Two Intersected Radar Echograms Near Neem Ice Core in Greenland

    Science.gov (United States)

    Xiong, S.; Muller, J.-P.

    2016-06-01

    Accumulation of snow and ice over time result in ice sheet layers. These can be remotely sensed where there is a contrast in electromagnetic properties, which reflect variations of the ice density, acidity and fabric orientation. Internal ice layers are assumed to be isochronous, deep beneath the ice surface, and parallel to the direction of ice flow. The distribution of internal layers is related to ice sheet dynamics, such as the basal melt rate, basal elevation variation and changes in ice flow mode, which are important parameters to model the ice sheet. Radar echo sounder is an effective instrument used to study the sedimentology of the Earth and planets. Ice Penetrating Radar (IPR) is specific kind of radar echo sounder, which extends studies of ice sheets from surface to subsurface to deep internal ice sheets depending on the frequency utilised. In this study, we examine a study site where folded ice occurs in the internal ice sheet south of the North Greenland Eemian ice drilling (NEEM) station, where two intersected radar echograms acquired by the Multi-channel Coherent Radar Depth Sounder (MCoRDS) employed in the NASA's Operation IceBridge (OIB) mission imaged this folded ice. We propose a slice processing flow based on a Radon Transform to trace and extract these two sets of curved ice sheet layers, which can then be viewed in 3-D, demonstrating the 3-D structure of the ice folds.

  11. Development of 3D Ice Accretion Measurement Method

    Science.gov (United States)

    Lee, Sam; Broeren, Andy P.; Addy, Harold E., Jr.; Sills, Robert; Pifer, Ellen M.

    2012-01-01

    Icing wind tunnels are designed to simulate in-flight icing environments. The chief product of such facilities is the ice accretion that forms on various test articles. Documentation of the resulting ice accretion key piece of data in icing-wind-tunnel tests. Number of currently used options for documenting ice accretion in icing-wind-tunnel testing.

  12. Even Shallower Exploration with Airborne Electromagnetics

    Science.gov (United States)

    Auken, E.; Christiansen, A. V.; Kirkegaard, C.; Nyboe, N. S.; Sørensen, K.

    2015-12-01

    Airborne electromagnetics (EM) is in many ways undergoing the same type rapid technological development as seen in the telecommunication industry. These developments are driven by a steadily increasing demand for exploration of minerals, groundwater and geotechnical targets. The latter two areas demand shallow and accurate resolution of the near surface geology in terms of both resistivity and spatial delineation of the sedimentary layers. Airborne EM systems measure the grounds electromagnetic response when subject to either a continuous discrete sinusoidal transmitter signal (frequency domain) or by measuring the decay of currents induced in the ground by rapid transmission of transient pulses (time domain). In the last decade almost all new developments of both instrument hardware and data processing techniques has focused around time domain systems. Here we present a concept for measuring the time domain response even before the transient transmitter current has been turned off. Our approach relies on a combination of new instrument hardware and novel modeling algorithms. The newly developed hardware allows for measuring the instruments complete transfer function which is convolved with the synthetic earth response in the inversion algorithm. The effect is that earth response data measured while the transmitter current is turned off can be included in the inversion, significantly increasing the amount of available information. We demonstrate the technique using both synthetic and field data. The synthetic examples provide insight on the physics during the turn off process and the field examples document the robustness of the method. Geological near surface structures can now be resolved to a degree that is unprecedented to the best of our knowledge, making airborne EM even more attractive and cost-effective for exploration of water and minerals that are crucial for the function of our societies.

  13. Forage: A sensitive indicator for airborne radioactivity

    International Nuclear Information System (INIS)

    As a part of the radiological environmental monitoring program at the Joseph M. Parley Nuclear Plant to meet the requirements of NRC Regulations 10 CRF 50, Appendix I, routine sampling of forage was implemented. Indicator plots of forage (grass) were established at the plant site boundary in the two Meteorological sectors having the highest X/Q values for ground-level dispersion of airborne radioactivity. Likewise, a control plot was established in a sector having a significantly lower X/Q value at a distance of 18 miles. Procedures for maintenance of the grass plots, sampling of forage, and sample preparation for measurement of gamma radioactivity with a Ge (Li) detector were developed during the reported three year measurement period. Three atmospheric nuclear tests by the Peoples Republic of China in 1976 and 1977 has proven forage sampling to be convenient, sensitive, and in the judgement of the authors gives results which are superior to most other media sampled for airborne radioactivity. Typical measured levels of radioactivity from 150 to greater than 10,000 pCi/kg (dry weight) were obtained for the principal fission products in the Chinese bomb fallout, which included 95Zr-95Nb, 103Ru, 131I, 140Ba-140La, 141Ce, and 144Ce. On a unit weight basis the level of radioactivity measured was consistently higher for forage than for green leafy vegetables. This was attributed to the higher surface area for the forage. For comparison, plots of airborne concentrations for gross beta and particulate gamma emitters are shown during the time periods that include the Chinese nuclear tests. (author)

  14. 1. Airborne 2. Hangár

    OpenAIRE

    Johnson, Christy

    2008-01-01

    Hangár, Bakelit Multi Art Center 7th L1 Dance Festival, Budapest, Hungary Installation, 2008 AIRBORNE (projection-sound-monitor installation) was sited in the Hangár, B.A.C. as part of the 7th L1 Dance Festival in Budapest, Hungary (March 2008). This work continues Johnson's interest in and use of 'found' material (16mm wind tunnel footage), and performative methods (sound recording of Channel 9 on United Airlines). This immersive work explores the turbulence of suspension and sets ...

  15. Analysis of airborne pollen grains in Denizli

    OpenAIRE

    GÜVENSEN, Aykut; ÇELİK, Ali; TOPUZ, Bülent; ÖZTÜRK, Münir

    2013-01-01

    Airborne pollen distribution in Denizli Province was measured volumetrically during 2 consecutive years, 2005 and 2006, on a weekly basis. A total of 11,981 pollen grains/m3 belonging to 42 taxa were determined. In 2005 the total was 5368 pollen grains/m3 and in 2006 it was 6613 pollen grains/m3. Among the taxa recorded, 26 belonged to arboreal and 16 to nonarboreal taxa. At the end of the 2 years total pollen counts comprised 79.68% arboreal, 19.48% nonarboreal, and 0.84% unidentified taxa. ...

  16. Response of passive microwave sea ice concentration algorithms to thin ice

    DEFF Research Database (Denmark)

    Heygster, Georg; Huntemann, Marcus; Ivanova, Natalia; Saldo, Roberto; Pedersen, Leif Toudal

    The influence of sea ice thickness brightness temperatures and ice concentrations retrieved from passive microwave observations is quantified, using horizontally homogeneous sea ice thickness retrievals from ESA's SMOS sensor observations at high incidence angles. Brightness temperatures are...

  17. Canadian Ice Service Arctic Regional Sea Ice Charts in SIGRID-3 Format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Canadian Ice Service (CIS) produces digital Arctic regional sea ice charts for marine navigation, climate research, and input to the Global Digital Sea Ice Data...

  18. Getting around Antarctica: new high-resolution mappings of the grounded and freely-floating boundaries of the Antarctic ice sheet created for the International Polar Year

    Directory of Open Access Journals (Sweden)

    R. Bindschadler

    2011-07-01

    Full Text Available Two ice-dynamic transitions of the Antarctic ice sheet – the boundary of grounded ice features and the freely-floating boundary – are mapped at 15-m resolution by participants of the International Polar Year project ASAID using customized software combining Landsat-7 imagery and ICESat/GLAS laser altimetry. The grounded ice boundary is 53 610 km long; 74 % abuts to floating ice shelves or outlet glaciers, 19 % is adjacent to open or sea-ice covered ocean, and 7 % of the boundary ice terminates on land. The freely-floating boundary, called here the hydrostatic line, is the most landward position on ice shelves that expresses the full amplitude of oscillating ocean tides. It extends 27 521 km and is discontinuous. Positional (one-sigma accuracies of the grounded ice boundary vary an order of magnitude ranging from ±52 m for the land and open-ocean terminating segments to ±502 m for the outlet glaciers. The hydrostatic line is less well positioned with errors over 2 km. Elevations along each line are selected from 6 candidate digital elevation models based on their agreement with ICESat elevation values and surface shape inferred from the Landsat imagery. Elevations along the hydrostatic line are converted to ice thicknesses by applying a firn-correction factor and a flotation criterion. BEDMAP-compiled data and other airborne data are compared to the ASAID elevations and ice thicknesses to arrive at quantitative (one-sigma uncertainties of surface elevations of ±3.6, ±9.6, ±11.4, ±30 and ±100 m for five ASAID-assigned confidence levels. Over one-half of the surface elevations along the grounded ice boundary and over one-third of the hydrostatic line elevations are ranked in the highest two confidence categories. A comparison between ASAID-calculated ice shelf thicknesses and BEDMAP-compiled data indicate a thin-ice bias of 41.2 ± 71.3 m for the ASAID ice thicknesses. The relationship between the seaward offset of the hydrostatic line

  19. Getting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year

    Science.gov (United States)

    Bindschadler, R.; Choi, H.; Wichlacz, A.; Bingham, R.; Bohlander, J.; Brunt, K.; Corr, H.; Drews, R.; Fricker, H.; Hall, M.; Hindmarsh, R.; Kohler, J.; Padman, L.; Rack, W.; Rotschkly, G.; Urbini, S.; Vornberger, P.; Young, N.

    2011-01-01

    Two ice-dynamic transitions of the Antarctic ice sheet - the boundary of grounded ice features and the freely-floating boundary - are mapped at 15-m resolution by participants of the International Polar Year project ASAID using customized software combining Landsat-7 imagery and ICESat/GLAS laser altimetry. The grounded ice boundary is 53 610 km long; 74% abuts to floating ice shelves or outlet glaciers, 19% is adjacent to open or sea-ice covered ocean, and 7% of the boundary ice terminates on land. The freely-floating boundary, called here the hydrostatic line, is the most landward position on ice shelves that expresses the full amplitude of oscillating ocean tides. It extends 27 521 km and is discontinuous. Positional (one-sigma) accuracies of the grounded ice boundary vary an order of magnitude ranging from +/- 52m for the land and open-ocean terminating segments to +/- 502m for the outlet glaciers. The hydrostatic line is less well positioned with errors over 2 km. Elevations along each line are selected from 6 candidate digital elevation models based on their agreement with ICESat elevation values and surface shape inferred from the Landsat imagery. Elevations along the hydrostatic line are converted to ice thicknesses by applying a firn-correction factor and a flotation criterion. BEDMAP-compiled data and other airborne data are compared to the ASAID elevations and ice thicknesses to arrive at quantitative (one-sigma) uncertainties of surface elevations of +/-3.6, +/-9.6, +/-11.4, +/-30 and +/-100m for five ASAID-assigned confidence levels. Over one-half of the surface elevations along the grounded ice boundary and over one-third of the hydrostatic line elevations are ranked in the highest two confidence categories. A comparison between ASAID-calculated ice shelf thicknesses and BEDMAP-compiled data indicate a thin-ice bias of 41.2+/-71.3m for the ASAID ice thicknesses. The relationship between the seaward offset of the hydrostatic line from the grounded ice

  20. Ice elevation change from Swath Processing of CryoSat SARIn Mode Data

    Science.gov (United States)

    Foresta, Luca; Gourmelen, Noel; Shepherd, Andrew; Muir, Alan; Nienow, Pete

    2015-04-01

    Reference and repeat-observations of Glacier and Ice Sheet Margin (GISM) topography are critical to identify changes in ice elevation, provide estimates of mass gain or loss and thus quantify the contribution of the cryosphere to sea level rise (e.g. McMillan et al., 2014). The Synthetic Interferometric Radar Altimeter (SIRAL) onboard the ESA radar altimetry CryoSat (CS) mission has collected ice elevation measurements since 2010. The corresponding SARIn mode of operation, activated over GISM areas, provides high spatial resolution in the along-track direction while resolving the angular origin of echoes (i.e. across-track). The current ESA SARIn processor calculates the elevation of the Point Of Closest Approach (POCA) within each waveform and maps of elevation change in Antarctica and Greenland have been produced using the regular CS height product (McMillan et al., 2014; Helm et al., 2014). Data from the CS-SARIn mode has also been used to produce measurements of ice elevation beyond the POCA, also known as swath elevation (Hawley et al. 2009; Gray et al., 2013; ESA-STSE CryoTop project). Here we use the swath processing approach to generate maps of ice elevation change from selected regions around the margins of the Greenland and Antarctic Ice Sheets. We discuss the impact of the swath processing on the spatial resolution and precision of the resulting ice elevation field and compare our results to current dh/dt estimates. References: ESA STSE CryoTop project - http://www.stse-cryotop.org/ Gray L., Burgess D., Copland L., Cullen R., Galin N., Hawley R. and Helm V. Interferometric swath processing of Cryosat data for glacial ice topography. The Cryosphere, 7(6):1857-1867, December 2013. Hawley R.L., Shepherd A., Cullen R., Helm V. and WIngham D.J. Ice-sheet elevations from across-track processing of airborne interferometric radar altimetry. Geophysical Research Letters, 36(22):L22501, November 2009. Helm V., Humbert A. and Miller H. Elevation and elevation

  1. Observations of ice nuclei and heterogeneous freezing in a Western Pacific extratropical storm

    Science.gov (United States)

    Stith, J. L.; Twohy, C. H.; Demott, P. J.; Baumgardner, D.; Campos, T.; Gao, R.; Anderson, J.

    2011-07-01

    In situ airborne sampling of refractory black carbon (rBC) particles and Ice Nuclei (IN) was conducted in and near an extratropical cyclonic storm in the western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. Cloud hydrometeors were evaporated by a counterflow virtual impactor (CVI) and the residuals were sampled by a single particle soot photometer (SP2) instrument, a continuous flow diffusion chamber ice nucleus detector (CFDC) and collected for electron microscope analysis. In clouds containing large ice particles, multiple residual particles were observed downstream of the CVI for each ice particle sampled on average. The fraction of rBC compared to total particles in the residual particles increased with decreasing condensed water content, while the fraction of IN compared to total particles did not, suggesting that the scavenging process for rBC is different than for IN. In the warm sector storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here -24 to -29 °C), IN concentrations from ice particle residuals generally agreed with simultaneous measurements of total ice concentrations or were higher in regions where aggregates of crystals were found, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures, ice concentrations were affected by aggregation and were somewhat less than measured IN concentrations at colder temperatures. The results are consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by aggregation and sedimentation to lower altitudes. Compositional analysis of the aerosol and back trajectories of the air in the warm sector suggested a possible biomass burning source for much

  2. Observations of ice nuclei and heterogeneous freezing in a Western Pacific extratropical storm

    Directory of Open Access Journals (Sweden)

    J. L. Stith

    2011-07-01

    Full Text Available In situ airborne sampling of refractory black carbon (rBC particles and Ice Nuclei (IN was conducted in and near an extratropical cyclonic storm in the western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. Cloud hydrometeors were evaporated by a counterflow virtual impactor (CVI and the residuals were sampled by a single particle soot photometer (SP2 instrument, a continuous flow diffusion chamber ice nucleus detector (CFDC and collected for electron microscope analysis. In clouds containing large ice particles, multiple residual particles were observed downstream of the CVI for each ice particle sampled on average. The fraction of rBC compared to total particles in the residual particles increased with decreasing condensed water content, while the fraction of IN compared to total particles did not, suggesting that the scavenging process for rBC is different than for IN. In the warm sector storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here −24 to −29 °C, IN concentrations from ice particle residuals generally agreed with simultaneous measurements of total ice concentrations or were higher in regions where aggregates of crystals were found, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures, ice concentrations were affected by aggregation and were somewhat less than measured IN concentrations at colder temperatures. The results are consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by aggregation and sedimentation to lower altitudes. Compositional analysis of the aerosol and back trajectories of the air in the warm sector suggested a possible biomass

  3. Diversity of cultured bacteria from the perennial ice block of Scarisoara Ice Cave, Romania

    OpenAIRE

    Corina Iţcuş; Mădălina-Denisa Pascu; Traian Brad; Aurel Perşoiu; Cristina Purcarea

    2016-01-01

    Cave ice ecosystems represent a poorly investigated glacial environment. Diversity of cave ice bacteria and their distribution in perennial ice deposits of this underground glacial habitat could constitute a proxy for microbial response to climatic and environmental changes. Scarisoara Ice Cave (Romania) hosts one of the oldest and largest cave ice blocks worldwide. Here we report on cultured microbial diversity of recent, 400, and 900 years-old perennial ice from this cave, representing the ...

  4. 30 CFR 56.5001 - Exposure limits for airborne contaminants.

    Science.gov (United States)

    2010-07-01

    ... asbestos standard found in 29 CFR 1910.1001, Appendix A, or a method at least equivalent to that method in... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Exposure limits for airborne contaminants. 56... Quality and Physical Agents Air Quality § 56.5001 Exposure limits for airborne contaminants. Except...

  5. 30 CFR 57.5001 - Exposure limits for airborne contaminants.

    Science.gov (United States)

    2010-07-01

    ... contrast microscopy (PCM) using the OSHA Reference Method in OSHA's asbestos standard found in 29 CFR 1910... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Exposure limits for airborne contaminants. 57... Underground § 57.5001 Exposure limits for airborne contaminants. Except as permitted by § 57.5005— (a)...

  6. Adaptive Restoration of Airborne Daedalus AADS1268 ATM Thermal Data

    International Nuclear Information System (INIS)

    To incorporate the georegistration and restoration processes into airborne data processing in support of U.S. Department of Energy's nuclear emergency response task, we developed an adaptive restoration filter for airborne Daedalus AADS1268 ATM thermal data based on the Wiener filtering theory. Preliminary assessment shows that this filter enhances the detectability of small weak thermal anomalies in AADS1268 thermal images

  7. 14 CFR 135.173 - Airborne thunderstorm detection equipment requirements.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airborne thunderstorm detection equipment... Aircraft and Equipment § 135.173 Airborne thunderstorm detection equipment requirements. (a) No person may... the aircraft is equipped with either approved thunderstorm detection equipment or approved...

  8. Decontamination of airborne bacteria in meat processing plants

    Science.gov (United States)

    Air has been established as a source of bacterial contamination in meat processing facilities. Airborne bacteria may affect product shelf life, and have food safety implications. The effectiveness of reactive oxygen species (ROS) generating AirOcare equipment on the reduction of airborne bacteria in...

  9. Monitoring of airborne radioactivity (radon, thoron and daughters; radioactive dust)

    International Nuclear Information System (INIS)

    The processes resulting in airborne radioactivity from uranium and thorium ores are discussed. Measurement methods for radioactive dust, radon and thoron gas and radon and thoron daughters are described and assessed. The monitoring equipment required for measurement of airborne radioactivity is described

  10. Decontamination of airborne bacteria in meat processing plants

    Science.gov (United States)

    The effectiveness of reactive oxygen species (ROS) generating AirOcare equipment on the reduction of airborne bacteria in a meat processing environment was determined. Bacterial strains found in ground beef were used to artificially contaminate the air using a 6-jet Collison nebulizer. Airborne bact...

  11. Moving Target Indication for Multi-channel Airborne Radar Systems

    NARCIS (Netherlands)

    Lidicky, L.

    2010-01-01

    Moving target indication (MTI) using radar is of great interest in civil and military applications. Its uses include airborne or space-borne surveillance of ground moving vehicles (cars, trains) or ships at sea, for instance. Airborne (space-borne) radar offers several advantages when compared to op

  12. SOFIA's Airborne Astronomy Ambassadors: An External Evaluation of Cycle 1

    Science.gov (United States)

    Phillips, Michelle

    2015-01-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) represents a partnership between NASA and the German Aerospace Center (DLR). The observatory itself is a Boeing 747 SP that has been modified to serve as the world's largest airborne research observatory. The SOFIA Airborne Astronomy Ambassadors (AAA) program is a component of SOFIA's…

  13. UAVSAR: An Airborne Window on Earth Surface Deformation

    Science.gov (United States)

    Hensley, Scott

    2011-01-01

    This study demonstrates that UAVSAR's precision autopilot and electronic steering have allowed for the reliable collection of airborne repeat pass radar interferometric data for deformation mapping. Deformation maps from temporal scales ranging from hours to months over a variety of signals of geophysical interest illustrate the utility of UAVSAR airborne repeat pass interferometry to these studies.

  14. Observations and simulations of three-dimensional radiative interactions between Arctic boundary layer clouds and ice floes

    Directory of Open Access Journals (Sweden)

    M. Schäfer

    2015-01-01

    Full Text Available Based on airborne spectral imaging observations three-dimensional (3-D radiative effects between Arctic boundary layer clouds and ice floes have been identified and quantified. A method is presented to discriminate sea ice and open water in case of clouds from imaging radiance measurements. This separation simultaneously reveals that in case of clouds the transition of radiance between open water and sea ice is not instantaneously but horizontally smoothed. In general, clouds reduce the nadir radiance above bright surfaces in the vicinity of sea ice – open water boundaries, while the nadir radiance above dark surfaces is enhanced compared to situations with clouds located above horizontal homogeneous surfaces. With help of the observations and 3-D radiative transfer simulations, this effect was quantified to range between 0 and 2200 m distance to the sea ice edge. This affected distance Δ L was found to depend on both, cloud and sea ice properties. For a ground overlaying cloud in 0–200 m altitude, increasing the cloud optical thickness from τ = 1 to τ = 10 decreases Δ L from 600 to 250 m, while increasing cloud base altitude or cloud geometrical thickness can increase Δ L; Δ L(τ = 1/10 = 2200 m/1250 m for 500–1000 m cloud altitude. To quantify the effect for different shapes and sizes of the ice floes, various albedo fields (infinite straight ice edge, circles, squares, realistic ice floe field were modelled. Simulations show that Δ L increases by the radius of the ice floe and for sizes larger than 6 km (500–1000 m cloud altitude asymptotically reaches maximum values, which corresponds to an infinite straight ice edge. Furthermore, the impact of these 3-D-radiative effects on retrieval of cloud optical properties was investigated. The enhanced brightness of a dark pixel next to an ice edge results in uncertainties of up to 90 and 30% in retrievals of cloud optical thickness and effective radius reff, respectively. With help of

  15. Role of ice dynamics in anomalous ice conditions in the Beaufort Sea during 2006 and 2007

    Science.gov (United States)

    Hutchings, J. K.; Rigor, I. G.

    2012-05-01

    A new record minimum in summer sea ice extent was set in 2007 and an unusual polynya formed in the Beaufort Sea ice cover during the summer of 2006. Using a combination of visual observations from cruises, ice drift, and satellite passive microwave sea ice concentration, we show that ice dynamics during preceding years included events that preconditioned the Beaufort ice pack for the unusual patterns of opening observed in both summers. Intrusions of first year ice from the Chukchi Sea to the Northern Beaufort, and increased pole-ward ice transport from the western Arctic during summer has led to reduced replenishment of multiyear ice, older than five years, in the western Beaufort, resulting in a younger, thinner ice pack in most of the Beaufort. We find ice younger than five years melts out completely by the end of summer, south of 76N. The 2006 unusual polynya was bounded to the south by an ice tongue composed of sea ice older than 5 years, and formed when first year and second year ice melted between 76N and the older ice to the south. In this paper we demonstrate that a recent shift in ice circulation patterns in the western Arctic preconditions the Beaufort ice pack for increased seasonal ice zone extent.

  16. Airborne gamma radiation soil moisture measurements over short flight lines

    Science.gov (United States)

    Peck, Eugene L.; Carrol, Thomas R.; Lipinski, Daniel M.

    1990-01-01

    Results are presented on airborne gamma radiation measurements of soil moisture condition, carried out along short flight lines as part of the First International Satellite Land Surface Climatology Project Field Experiment (FIFE). Data were collected over an area in Kansas during the summers of 1987 and 1989. The airborne surveys, together with ground measurements, provide the most comprehensive set of airborne and ground truth data available in the U.S. for calibrating and evaluating airborne gamma flight lines. Analysis showed that, using standard National Weather Service weights for the K, Tl, and Gc radiation windows, the airborne soil moisture estimates for the FIFE lines had a root mean square error of no greater than 3.0 percent soil moisture. The soil moisture estimates for sections having acquisition time of at least 15 sec were found to be reliable.

  17. What Determines the Ice Polymorph in Clouds?

    Science.gov (United States)

    Hudait, Arpa; Molinero, Valeria

    2016-07-20

    Ice crystals in the atmosphere nucleate from supercooled liquid water and grow by vapor uptake. The structure of the ice polymorph grown has strong impact on the morphology and light scattering of the ice crystals, modulates the amount of water vapor in ice clouds, and can impact the molecular uptake and reactivity of atmospheric aerosols. Experiments and molecular simulations indicate that ice nucleated and grown from deeply supercooled liquid water is metastable stacking disordered ice. The ice polymorph grown from vapor has not yet been determined. Here we use large-scale molecular simulations to determine the structure of ice that grows as a result of uptake of water vapor in the temperature range relevant to cirrus and mixed-phase clouds, elucidate the molecular mechanism of the formation of ice at the vapor interface, and compute the free energy difference between cubic and hexagonal ice interfaces with vapor. We find that vapor deposition results in growth of stacking disordered ice only under conditions of extreme supersaturation, for which a nonequilibrium liquid layer completely wets the surface of ice. Such extreme conditions have been used to produce stacking disordered frost ice in experiments and may be plausible in the summer polar mesosphere. Growth of ice from vapor at moderate supersaturations in the temperature range relevant to cirrus and mixed-phase clouds, from 200 to 260 K, produces exclusively the stable hexagonal ice polymorph. Cubic ice is disfavored with respect to hexagonal ice not only by a small penalty in the bulk free energy (3.6 ± 1.5 J mol(-1) at 260 K) but also by a large free energy penalty at the ice-vapor interface (89.7 ± 12.8 J mol(-1) at 260 K). The latter originates in higher vibrational entropy of the hexagonal-terminated ice-vapor interface. We predict that the free energy penalty against the cubic ice interface should decrease strongly with temperature, resulting in some degree of stacking disorder in ice grown from

  18. Calibration Matters: Advances in Strapdown Airborne Gravimetry

    Science.gov (United States)

    Becker, D.

    2015-12-01

    Using a commercial navigation-grade strapdown inertial measurement unit (IMU) for airborne gravimetry can be advantageous in terms of cost, handling, and space consumption compared to the classical stable-platform spring gravimeters. Up to now, however, large sensor errors made it impossible to reach the mGal-level using such type IMUs as they are not designed or optimized for this kind of application. Apart from a proper error-modeling in the filtering process, specific calibration methods that are tailored to the application of aerogravity may help to bridge this gap and to improve their performance. Based on simulations, a quantitative analysis is presented on how much IMU sensor errors, as biases, scale factors, cross couplings, and thermal drifts distort the determination of gravity and the deflection of the vertical (DOV). Several lab and in-field calibration methods are briefly discussed, and calibration results are shown for an iMAR RQH unit. In particular, a thermal lab calibration of its QA2000 accelerometers greatly improved the long-term drift behavior. Latest results from four recent airborne gravimetry campaigns confirm the effectiveness of the calibrations applied, with cross-over accuracies reaching 1.0 mGal (0.6 mGal after cross-over adjustment) and DOV accuracies reaching 1.1 arc seconds after cross-over adjustment.

  19. Handling Trajectory Uncertainties for Airborne Conflict Management

    Science.gov (United States)

    Barhydt, Richard; Doble, Nathan A.; Karr, David; Palmer, Michael T.

    2005-01-01

    Airborne conflict management is an enabling capability for NASA's Distributed Air-Ground Traffic Management (DAG-TM) concept. DAGTM has the goal of significantly increasing capacity within the National Airspace System, while maintaining or improving safety. Under DAG-TM, autonomous aircraft maintain separation from each other and from managed aircraft unequipped for autonomous flight. NASA Langley Research Center has developed the Autonomous Operations Planner (AOP), an onboard decision support system that provides airborne conflict management (ACM) and strategic flight planning support for autonomous aircraft pilots. The AOP performs conflict detection, prevention, and resolution from nearby traffic aircraft and area hazards. Traffic trajectory information is assumed to be provided by Automatic Dependent Surveillance Broadcast (ADS-B). Reliable trajectory prediction is a key capability for providing effective ACM functions. Trajectory uncertainties due to environmental effects, differences in aircraft systems and performance, and unknown intent information lead to prediction errors that can adversely affect AOP performance. To accommodate these uncertainties, the AOP has been enhanced to create cross-track, vertical, and along-track buffers along the predicted trajectories of both ownship and traffic aircraft. These buffers will be structured based on prediction errors noted from previous simulations such as a recent Joint Experiment between NASA Ames and Langley Research Centers and from other outside studies. Currently defined ADS-B parameters related to navigation capability, trajectory type, and path conformance will be used to support the algorithms that generate the buffers.

  20. Airborne multidimensional integrated remote sensing system

    Science.gov (United States)

    Xu, Weiming; Wang, Jianyu; Shu, Rong; He, Zhiping; Ma, Yanhua

    2006-12-01

    In this paper, we present a kind of airborne multidimensional integrated remote sensing system that consists of an imaging spectrometer, a three-line scanner, a laser ranger, a position & orientation subsystem and a stabilizer PAV30. The imaging spectrometer is composed of two sets of identical push-broom high spectral imager with a field of view of 22°, which provides a field of view of 42°. The spectral range of the imaging spectrometer is from 420nm to 900nm, and its spectral resolution is 5nm. The three-line scanner is composed of two pieces of panchromatic CCD and a RGB CCD with 20° stereo angle and 10cm GSD(Ground Sample Distance) with 1000m flying height. The laser ranger can provide height data of three points every other four scanning lines of the spectral imager and those three points are calibrated to match the corresponding pixels of the spectral imager. The post-processing attitude accuracy of POS/AV 510 used as the position & orientation subsystem, which is the aerial special exterior parameters measuring product of Canadian Applanix Corporation, is 0.005° combined with base station data. The airborne multidimensional integrated remote sensing system was implemented successfully, performed the first flying experiment on April, 2005, and obtained satisfying data.

  1. Determination of leachable uranium in airborne particulates

    International Nuclear Information System (INIS)

    The uranium content of airborne particulates collected on cellulose filters was investigated. As a case study, filter samples from the large area of Thessaloniki, Greece, were used. For the uranium determination instrumental neutron activation analysis was used. To obtain equal counting conditions for all samples after irradiation, independent from the initial matrix, uranium was leached from the filter by using a 0.1M NH4HCO3 solution, forming a stable uranyl complex [UO2(CO3)3]. This complex was absorbed in a batch process on a small amount of chelating ion exchanger Srafion NMRR, which was directly irradiated in the reactor of the NCSR Demokritos. Over the investigated time period in 1997 the mean concentration was found to be 0.047 ng U/m3. In relation to the collected amount of airborne particulates having a mean concentration of 0.52 μg/gU. It can be assumed as a natural uranium level in the environment. (author)

  2. Airborne soil organic particles generated by precipitation

    Science.gov (United States)

    Wang, Bingbing; Harder, Tristan H.; Kelly, Stephen T.; Piens, Dominique S.; China, Swarup; Kovarik, Libor; Keiluweit, Marco; Arey, Bruce W.; Gilles, Mary K.; Laskin, Alexander

    2016-06-01

    Airborne organic particles play a critical role in Earth's climate, public health, air quality, and hydrological and carbon cycles. However, sources and formation mechanisms for semi-solid and solid organic particles are poorly understood and typically neglected in atmospheric models. Laboratory evidence suggests that fine particles can be formed from impaction of mineral surfaces by droplets. Here, we use chemical imaging of particles collected following rain events in the Southern Great Plains, Oklahoma, USA and after experimental irrigation to show that raindrop impaction of soils generates solid organic particles. We find that after rain events, sub-micrometre solid particles, with a chemical composition consistent with soil organic matter, contributed up to 60% of atmospheric particles. Our irrigation experiments indicate that intensive water impaction is sufficient to cause ejection of airborne soil organic particles from the soil surface. Chemical imaging and micro-spectroscopy analysis of particle physico-chemical properties suggest that these particles may have important impacts on cloud formation and efficiently absorb solar radiation. We suggest that raindrop-induced formation of solid organic particles from soils may be a widespread phenomenon in ecosystems such as agricultural systems and grasslands where soils are exposed to strong, episodic precipitation events.

  3. Laser Systems For Use With Airborne Platforms

    Science.gov (United States)

    Jepsky, Joseph

    1984-10-01

    This paper describes a family of airborne laser systems in use for terrain profiling, surveying, mapping, altimetry, collision avoidance and shipboard landing systems using fixed and rotary wing aircraft as the platforms. The laser altimeter has also been used in systems compatible with the Army T-16 and. T-22 carrier missiles (platform). Both pulsed gallium arsenide and Nd:YAG (neodymium-doped, yttrium-aluminum-garnet) laser rangefinders have been used for these applications. All of these systems use ACCI's advanced measurement techniques that permit range accuracies of 8 cm, single shot, 1 cm averaged, to be achieved. Pulse rates up to 4 Khz are employed for airborne profiling. This high data density rate provides 1 data point every 2" along the aircraft flight line at aircraft speed of 500 knots. Scanning modes for some applications are employed. Systems have been integrated with all current inertial navigation systems (Litton, Ferranti and Honeywell), as well as a number of microwave positioning systems. Removal of aircraft motion from the laser range measurements by use of an accelerometer is described. Flight data from a number of program performed by U.S. and Canadian Federal Agencies, in addition to those of commercial surveying and mapping companies are described.

  4. Architecture and Algorithms for an Airborne Network

    CERN Document Server

    Sen, Arunabha; Silva, Tiffany; Das, Nibedita; Kundu, Anjan

    2010-01-01

    The U.S. Air Force currently is in the process of developing an Airborne Network (AN) to provide support to its combat aircrafts on a mission. The reliability needed for continuous operation of an AN is difficult to achieve through completely infrastructure-less mobile ad hoc networks. In this paper we first propose an architecture for an AN where airborne networking platforms (ANPs - aircrafts, UAVs and satellites) form the backbone of the AN. In this architecture, the ANPs can be viewed as mobile base stations and the combat aircrafts on a mission as mobile clients. The combat aircrafts on a mission move through a space called air corridor. The goal of the AN design is to form a backbone network with the ANPs with two properties: (i) the backbone network remains connected at all times, even though the topology of the network changes with the movement of the ANPs, and (ii) the entire 3D space of the air corridor is under radio coverage at all times by the continuously moving ANPs. In addition to proposing an...

  5. Auxiliary DCP data acquisition system. [airborne system

    Science.gov (United States)

    Snyder, R. V.

    1975-01-01

    An airborne DCP Data Aquisition System has been designed to augment the ERTS satellite data recovery system. The DCP's are data collection platforms located at pertinent sites. With the appropriate sensors they are able to collect, digitally encode and transmit environmental parameters to the ERTS satellite. The satellite in turn relays these transmissions to a ground station for processing. The satellite is available for such relay duty a minimum of two times in a 24-hour period. The equipment is to obtain continuous DCP data during periods of unusual environmental activity--storms, floods, etc. Two circumstances contributed to the decision to design such a system; (1) Wallops Station utilizes surveillance aircraft in support of rocket launches and also in support of earth resources activities; (2) the area in which Wallops is located, the Delaware and Chesapeake Bay areas, are fertile areas for DCP usage. Therefore, by developing an airborne DCP receiving station and installing it on aircraft more continuous DCP data can be provided from sites in the surrounding areas at relatively low cost.

  6. The Next Generation Airborne Polarimetric Doppler Radar

    Science.gov (United States)

    Vivekanandan, J.; Lee, Wen-Chau; Loew, Eric; Salazar, Jorge; Chandrasekar, V.

    2013-04-01

    NCAR's Electra Doppler radar (ELDORA) with a dual-beam slotted waveguide array using dual-transmitter, dual-beam, rapid scan and step-chirped waveform significantly improved the spatial scale to 300m (Hildebrand et al. 1996). However, ELDORA X-band radar's penetration into precipitation is limited by attenuation and is not designed to collect polarimetric measurements to remotely estimate microphysics. ELDORA has been placed on dormancy because its airborne platform (P3 587) was retired in January 2013. The US research community has strongly voiced the need to continue measurement capability similar to the ELDORA. A critical weather research area is quantitative precipitation estimation/forecasting (QPE/QPF). In recent years, hurricane intensity change involving eye-eyewall interactions has drawn research attention (Montgomery et al., 2006; Bell and Montgomery, 2006). In the case of convective precipitation, two issues, namely, (1) when and where convection will be initiated, and (2) determining the organization and structure of ensuing convection, are key for QPF. Therefore collocated measurements of 3-D winds and precipitation microphysics are required for achieving significant skills in QPF and QPE. Multiple radars in dual-Doppler configuration with polarization capability estimate dynamical and microphysical characteristics of clouds and precipitation are mostly available over land. However, storms over complex terrain, the ocean and in forest regions are not observable by ground-based radars (Bluestein and Wakimoto, 2003). NCAR/EOL is investigating potential configurations for the next generation airborne radar that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. ELDORA's slotted waveguide array radar is not compatible for dual-polarization measurements. Therefore, the new design has to address both dual-polarization capability and platform requirements to replace the ELDORA system. NCAR maintains a C-130

  7. Airborne hyperspectral observations of surface and cloud directional reflectivity using a commercial digital camera

    Directory of Open Access Journals (Sweden)

    A. Ehrlich

    2012-04-01

    Full Text Available Spectral radiance measurements by a digital single-lens reflex camera were used to derive the directional reflectivity of clouds and different surfaces in the Arctic. The camera has been calibrated radiometrically and spectrally to provide accurate radiance measurements with high angular resolution. A comparison with spectral radiance measurements with the Spectral Modular Airborne Radiation measurement sysTem (SMART-Albedometer showed an agreement within the uncertainties of both instruments (6% for both. The directional reflectivity in terms of the hemispherical directional reflectance factor (HDRF was obtained for sea ice, ice-free ocean and clouds. The sea ice, with an albedo of ρ = 0.96 (at 530 nm wavelength, showed an almost isotropic HDRF, while sun glint was observed for the ocean HDRF (ρ = 0.12. For the cloud observations with ρ = 0.62, the cloudbow – a backscatter feature typically for scattering by liquid water droplets – was covered by the camera. For measurements above heterogeneous stratocumulus clouds, the required number of images to obtain a mean HDRF that clearly exhibits the cloudbow has been estimated at about 50 images (10 min flight time. A representation of the HDRF as a function of the scattering angle only reduces the image number to about 10 (2 min flight time.

    The measured cloud and ocean HDRF have been compared to radiative transfer simulations. The ocean HDRF simulated with the observed surface wind speed of 9 m s−1 agreed best with the measurements. For the cloud HDRF, the best agreement was obtained by a broad and weak cloudbow simulated with a cloud droplet effective radius of Reff = 4 μm. This value agrees with the particle sizes derived from in situ measurements and retrieved from the spectral radiance of the SMART-Albedometer.

  8. Vapor deposition of water on graphitic surfaces: Formation of amorphous ice, bilayer ice, ice I, and liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Lupi, Laura; Kastelowitz, Noah; Molinero, Valeria, E-mail: Valeria.Molinero@utah.edu [Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850 (United States)

    2014-11-14

    Carbonaceous surfaces are a major source of atmospheric particles and could play an important role in the formation of ice. Here we investigate through molecular simulations the stability, metastability, and molecular pathways of deposition of amorphous ice, bilayer ice, and ice I from water vapor on graphitic and atomless Lennard-Jones surfaces as a function of temperature. We find that bilayer ice is the most stable ice polymorph for small cluster sizes, nevertheless it can grow metastable well above its region of thermodynamic stability. In agreement with experiments, the simulations predict that on increasing temperature the outcome of water deposition is amorphous ice, bilayer ice, ice I, and liquid water. The deposition nucleation of bilayer ice and ice I is preceded by the formation of small liquid clusters, which have two wetting states: bilayer pancake-like (wetting) at small cluster size and droplet-like (non-wetting) at larger cluster size. The wetting state of liquid clusters determines which ice polymorph is nucleated: bilayer ice nucleates from wetting bilayer liquid clusters and ice I from non-wetting liquid clusters. The maximum temperature for nucleation of bilayer ice on flat surfaces, T{sub B}{sup max} is given by the maximum temperature for which liquid water clusters reach the equilibrium melting line of bilayer ice as wetting bilayer clusters. Increasing water-surface attraction stabilizes the pancake-like wetting state of liquid clusters leading to larger T{sub B}{sup max} for the flat non-hydrogen bonding surfaces of this study. The findings of this study should be of relevance for the understanding of ice formation by deposition mode on carbonaceous atmospheric particles, including soot.

  9. Airborne observations of cloud properties on HALO during NARVAL

    Science.gov (United States)

    Konow, Heike; Hansen, Akio; Ament, Felix

    2016-04-01

    second phase of NARVAL will focus on trade-wind cumuli observations and the NAWDEX (North-Atlantik Waveguide EXperiment) campaign will investigate the warm sector and frontal zones of mid-latitude cyclones. During the first NARVAL campaign, a broad range of cloud regimes from shallow cumuli to cumulonimbus and cold fronts was observed. Derived cloud covers from different instruments on board HALO varied by as much as 25 % since cloud radar, microwave radiometers, lidar and dropsondes measure different aspects of clouds. A cloud mask combining these observations provides a complimentary view of clouds and allows for identification of joint cloud characteristics (e.g., cloud top of ice or water clouds, cloud depth). We will present benefits gained from this combination of measurements and provide a more comprehensive view on clouds and cloud properties in different cloud regimes. Furthermore, we will give an overview of the plans for future campaigns and demonstrate what new insights we can gain from these airborne observations within the scope of past and future campaigns.

  10. Quantification of segregation dynamics in ice mixtures

    OpenAIRE

    Öberg, Karin I.; Fayolle, Edith C.; Cuppen, Herma M.; van Dishoeck, Ewine F.; Linnartz, Harold

    2009-01-01

    (Abridged) The observed presence of pure CO2 ice in protostellar envelopes is attributed to thermally induced ice segregation, but a lack of quantitative experimental data has prevented its use as a temperature probe. Quantitative segregation studies are also needed to characterize diffusion in ices, which underpins all ice dynamics and ice chemistry. This study aims to quantify the segregation mechanism and barriers in different H2O:CO2 and H2O:CO ice mixtures covering a range of astrophysic...

  11. Turbulence and heat exchange under ice

    OpenAIRE

    Sirevaag, Anders

    2003-01-01

    Turbulent fluxes of heat and salt were measured under sea ice at four different locations around Spitsbergen. In Kongsfjorden on West Spitsbergen additional measurements of heat fluxes in the ice and in the atmosphere were done and compared in an air/sea/ice heat budget. Ocean heat flux in Kongsfjorden is about 13 W/m2 and comparison with the other heat fluxes at the ice/ocean interface shows a good agreement. From the heat budget at the ice/ocean interface, the ice growth during three subseq...

  12. The Greenland Ice Mapping Project

    Science.gov (United States)

    Joughin, I.; Smith, B.; Howat, I. M.; Moon, T. A.; Scambos, T. A.

    2015-12-01

    Numerous glaciers in Greenland have sped up rapidly and unpredictably during the first part of the 21st Century. We started the Greenland Ice Mapping Project (GIMP) to produce time series of ice velocity for Greenland's major outlet glaciers. We are also producing image time series to document the advance and retreat of glacier calving fronts and other changes in ice-sheet geometry (e.g., shrinking ice caps and ice shelves). When the project began, there was no digital elevation model (DEM) with sufficient accuracy and resolution to terrain-correct the SAR-derived products. Thus, we also produced the 30-m GIMP DEM, which, aside from improving our processing, is an important product in its own right. Although GIMP focuses on time series, complete spatial coverage for initializing ice sheet models also is important. There are insufficient data, however, to map the full ice sheet in any year. There is good RADARSAT coverage for many years in the north, but the C-band data decorrelate too quickly to measure velocity in the high accumulation regions of the southeast. For such regions, ALOS data usually correlate well, but speckle-tracking estimates at L-band are subject to large ionospheric artifacts. Interferometric phase data are far less sensitive to the effect of the ionosphere, but velocity estimates require results from crossing orbits. Thus, to produce a nearly complete mosaic we used data from multiple sensors, beginning with ERS-1/2 data from the mid 1990s. By using a primarily phase-only solution for much of the interior, we have reduced the velocity errors to ~1-3 m/yr. For the faster moving ice-sheet margin where phase data cannot be unwrapped, we used speckle-tracking data. In particular, we have relied on TerraSAR-X for many fast-moving glaciers because the ionosphere far less affects X-band data. This pan-Greenland velocity map as well as many of the time series would not have been possible without an extensive archive of data collected using six

  13. Ice-condenser aerosol tests

    International Nuclear Information System (INIS)

    This report presents the results of an experimental investigation of aerosol particle transport and capture using a full-scale height and reduced-scale cross section test facility based on the design of the ice compartment of a pressurized water reactor (PWR) ice-condenser containment system. Results of 38 tests included thermal-hydraulic as well as aerosol particle data. Particle retention in the test section was greatly influenced by thermal-hydraulic and aerosol test parameters. Test-average decontamination factor (DF) ranged between 1.0 and 36 (retentions between ∼0 and 97.2%). The measured test-average particle retentions for tests without and with ice and steam ranged between DF = 1.0 and 2.2 and DF = 2.4 and 36, respectively. In order to apparent importance, parameters that caused particle retention in the test section in the presence of ice were steam mole fraction (SMF), noncondensible gas flow rate (residence time), particle solubility, and inlet particle size. Ice-basket section noncondensible flows greater than 0.1 m3/s resulted in stable thermal stratification whereas flows less than 0.1 m3/s resulted in thermal behavior termed meandering with frequent temperature crossovers between flow channels. 10 refs., 66 figs., 16 tabs

  14. Sea Ice Concentration and Extent

    Science.gov (United States)

    Comiso, Josefino C.

    2014-01-01

    Among the most seasonal and most dynamic parameters on the surface of the Earth is sea ice which at any one time covers about 3-6% of the planet. In the Northern Hemisphere, sea ice grows in extent from about 6 x 10(exp 6) sq km to 16 x 10(exp 6) sq km, while in the Southern Hemisphere, it grows from about 3 x 10(exp 6) sq km to about 19 x 10(exp 6) sq km (Comiso, 2010; Gloersen et al., 1992). Sea ice is up to about 2-3 m thick in the Northern Hemisphere and about 1 m thick in the Southern Hemisphere (Wadhams, 2002), and compared to the average ocean depth of about 3 km, it is a relatively thin, fragile sheet that can break due to waves and winds or melt due to upwelling of warm water. Being constantly advected by winds, waves, and currents, sea ice is very dynamic and usually follows the directions of the many gyres in the polar regions. Despite its vast expanse, the sea ice cover was previously left largely unstudied and it was only in recent years that we have understood its true impact and significance as related to the Earths climate, the oceans, and marine life.

  15. Ice-condenser aerosol tests

    Energy Technology Data Exchange (ETDEWEB)

    Ligotke, M.W.; Eschbach, E.J.; Winegardner, W.K. (Pacific Northwest Lab., Richland, WA (United States))

    1991-09-01

    This report presents the results of an experimental investigation of aerosol particle transport and capture using a full-scale height and reduced-scale cross section test facility based on the design of the ice compartment of a pressurized water reactor (PWR) ice-condenser containment system. Results of 38 tests included thermal-hydraulic as well as aerosol particle data. Particle retention in the test section was greatly influenced by thermal-hydraulic and aerosol test parameters. Test-average decontamination factor (DF) ranged between 1.0 and 36 (retentions between {approximately}0 and 97.2%). The measured test-average particle retentions for tests without and with ice and steam ranged between DF = 1.0 and 2.2 and DF = 2.4 and 36, respectively. In order to apparent importance, parameters that caused particle retention in the test section in the presence of ice were steam mole fraction (SMF), noncondensible gas flow rate (residence time), particle solubility, and inlet particle size. Ice-basket section noncondensible flows greater than 0.1 m{sup 3}/s resulted in stable thermal stratification whereas flows less than 0.1 m{sup 3}/s resulted in thermal behavior termed meandering with frequent temperature crossovers between flow channels. 10 refs., 66 figs., 16 tabs.

  16. Recrystallization inhibition in ice due to ice binding protein activity detected by nuclear magnetic resonance

    Directory of Open Access Journals (Sweden)

    Jennifer R. Brown

    2014-09-01

    Full Text Available Liquid water present in polycrystalline ice at the interstices between ice crystals results in a network of liquid-filled veins and nodes within a solid ice matrix, making ice a low porosity porous media. Here we used nuclear magnetic resonance (NMR relaxation and time dependent self-diffusion measurements developed for porous media applications to monitor three dimensional changes to the vein network in ices with and without a bacterial ice binding protein (IBP. Shorter effective diffusion distances were detected as a function of increased irreversible ice binding activity, indicating inhibition of ice recrystallization and persistent small crystal structure. The modification of ice structure by the IBP demonstrates a potential mechanism for the microorganism to enhance survivability in ice. These results highlight the potential of NMR techniques in evaluation of the impact of IBPs on vein network structure and recrystallization processes; information useful for continued development of ice-interacting proteins for biotechnology applications.

  17. Characterization of an IceTop tank for the IceCube surface extension IceVeto

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Julian; Auffenberg, Jan; Hansmann, Bengt; Rongen, Martin; Stahlberg, Martin; Wiebusch, Christopher [III. Physikalisches Institut B, RWTH Aachen University (Germany); Collaboration: IceCube-Collaboration

    2015-07-01

    IceTop is an air-shower detector located at the South Pole on the surface above the IceCube detector. It consists of 81 detector stations with two Cherenkov tanks each. The tanks are filled with clear ice and instrumented with two photomultipliers. IceTop detects cosmic-ray induced air-showers above an energy threshold of ∝300 TeV. Muons and neutrinos from these air-showers are the main background for astrophysical neutrino searches with IceCube. The usage of IceTop to veto air-showers largely reduces this background in the field of view. To enlarge the field of view an extension of the surface detector, IceVeto, is planned. Therefore, we investigate the properties of an original IceTop tank as a laboratory reference for the development of new detection module designs. First results of these measurements are presented.

  18. The safety band of Antarctic ice shelves

    Science.gov (United States)

    Fürst, Johannes Jakob; Durand, Gaël; Gillet-Chaulet, Fabien; Tavard, Laure; Rankl, Melanie; Braun, Matthias; Gagliardini, Olivier

    2016-05-01

    The floating ice shelves along the seaboard of the Antarctic ice sheet restrain the outflow of upstream grounded ice. Removal of these ice shelves, as shown by past ice-shelf recession and break-up, accelerates the outflow, which adds to sea-level rise. A key question in predicting future outflow is to quantify the extent of calving that might precondition other dynamic consequences and lead to loss of ice-shelf restraint. Here we delineate frontal areas that we label as `passive shelf ice’ and that can be removed without major dynamic implications, with contrasting results across the continent. The ice shelves in the Amundsen and Bellingshausen seas have limited or almost no `passive’ portion, which implies that further retreat of current ice-shelf fronts will yield important dynamic consequences. This region is particularly vulnerable as ice shelves have been thinning at high rates for two decades and as upstream grounded ice rests on a backward sloping bed, a precondition to marine ice-sheet instability. In contrast to these ice shelves, Larsen C Ice Shelf, in the Weddell Sea, exhibits a large `passive’ frontal area, suggesting that the imminent calving of a vast tabular iceberg will be unlikely to instantly produce much dynamic change.

  19. Initial evaluation of airborne water vapour measurements by the IAGOS-GHG CRDS system

    Science.gov (United States)

    Filges, Annette; Gerbig, Christoph; Smit, Herman G. J.; Krämer, Martina; Spelten, Nicole

    2013-04-01

    Accurate and reliable airborne measurements of water vapour are still a challenge. Presently, no airborne humidity sensor exists that covers the entire range of water vapour content between the surface and the upper troposphere/lower stratosphere (UT/LS) region with sufficient accuracy and time resolution. Nevertheless , these data are a pre-requisite to study the underlying processes in the chemistry and physics of the atmosphere. The DENCHAR project (Development and Evaluation of Novel Compact Hygrometer for Airborne Research) addresses this deficit by developing and characterizing novel or improved compact airborne hygrometers for different airborne applications within EUFAR (European Facility for Airborne Research). As part of the DENCHAR inter-comparison campaign in Hohn (Germany), 23 May - 1 June 2011, a commercial gas analyzer (G2401-m, Picarro Inc.,US), based on cavity ring-down spectroscopy (CRDS), was installed on a Learjet to measure water vapour, CO2, CH4 and CO. The CRDS components are identical to those chosen for integration aboard commercial airliner within IAGOS (In-service Aircraft for a Global Observing System). Thus the campaign allowed for the initial assessment validation of the long-term IAGOS H2O measurements by CRDS against reference instruments with a long performance record (FISH, the Fast In-situ Stratospheric Hygrometer, and CR2 frostpoint hygrometer, both research centre Juelich). The inlet system, a one meter long 1/8" FEP-tube connected to a Rosemount TAT housing (model 102BX, deiced) installed on a window plate of the aircraft, was designed to eliminate sampling of larger aerosols, ice particles, and water droplets, and provides about 90% of ram-pressure. In combination with a lowered sample flow of 0.1 slpm (corresponding to a 4 second response time), this ensured a fully controlled sample pressure in the cavity of 140 torr throughout an aircraft altitude operating range up to 12.5 km without the need of an upstream sampling pump

  20. Experimental Studies in Ice Nucleation

    Science.gov (United States)

    Wright, Timothy Peter

    Ice nuclei play a critical role in the formation of precipitation in mixed phase clouds. Modification of IN concentrations can lead to changes in cloud lifetimes and precipitation size. Presented in this study are experimental investigations into ice nuclei in an ongoing effort to reduce the uncertainties that ice nuclei have on cloud processes and climate. This research presents a new version of the cold stage drop freezing assay to investigate the time-dependence of heterogeneous nucleation. The temperature range for the instrument spans from the melting point of water to the homogeneous freezing limit of ˜-38 deg C. Temperature stability for the instrument allowed for experimental operation for up to four days while interrogating the same sample. Up to a one hundred fold increase in the number of analyzed drops was accomplished through an in-house written automated drop freezing detection software package. Combined instrument design improvements allow for the analysis of IN concentrations down to ˜10-8 ice nuclei per picoliter of sample water. A new variant of the multiple-component stochastic model for heterogeneous ice nucleation was used to investigate the time dependence of heterogeneous freezing processes. This was accomplished by analyzing how the changes in the cooling rate can impact the observed nucleation rate. The model employed four material-dependent parameters to accurately capture the observed freezing of water drops containing Arizona Test Dust. The parameters were then used to accurately predict the freezing behavior of the drops in time dependent experiments. The time dependence freezing of a wide range of materials was then investigated. These materials included the minerals montmorillonite and kaolinite, the biological proxy ice nuclei contained within the product Icemax, and flame soot generated from the incomplete combustion of ethylene gas. The time dependence for ice nuclei collected from rainwater samples was also investigated. The