WorldWideScience

Sample records for champ satellite measurements

  1. Recalibration of the CHAMP satellite magnetic field measurements

    International Nuclear Information System (INIS)

    The eight years of continuous CHAMP operation allows us to investigate the long-term behaviour of the vector magnetometer on board the satellite. For the processing of the FGM vector magnetometer data primarily nine instrument parameters are needed (three offsets, three scale factors and three misalignment angles). These are determined in pre-flight calibration and routinely in the in-flight scalar calibration. A review of the temporal evolution shows that the scale factors exhibit a clear change with time. This variation of the sensitivity can be well described by a logarithmic function. The offsets and the misalignment angles show no long-term trend. The Z component offset performs medium-term variations within the range of 1 nT. These have been corrected on a daily basis. When processing the FGM data over the whole period with the derived parameters, the difference between the FGM and OVM readings stays below 0.5 nT (corresponding to about 0.2 nT standard deviation). For a further improvement the error model has to be extended beyond the scalar calibration. Dynamic spacecraft magnetic fields varying over an orbit are falsely interpreted by the scalar calibration and cause apparent variations of the instrument parameters. In the case of CHAMP, the magnetic field generated by the power system is responsible for most of the remaining errors. We have applied an extended error model that can account for the time-varying disturbance fields. When considering them properly the standard deviation of scalar errors less than 0.1 nT can be achieved

  2. Global Lithospheric Apparent Susceptibility Distribution Converted from Geomagnetic Models by CHAMP and Swarm Satellite Magnetic Measurements

    Science.gov (United States)

    Du, Jinsong; Chen, Chao; Xiong, Xiong; Li, Yongdong; Liang, Qing

    2016-04-01

    Recently, because of continually accumulated magnetic measurements by CHAMP satellite and Swarm constellation of three satellites and well developed methodologies and techniques of data processing and geomagnetic field modeling etc., global lithospheric magnetic anomaly field models become more and more reliable. This makes the quantitative interpretation of lithospheric magnetic anomaly field possible for having an insight into large-scale magnetic structures in the crust and uppermost mantle. Many different approaches have been utilized to understand the magnetized sources, such as forward, inversion, statistics, correlation analysis, Euler deconvolution, signal transformations etc. Among all quantitative interpretation methods, the directly converting a magnetic anomaly map into a magnetic susceptibility anomaly map proposed by Arkani-Hamed & Strangway (1985) is, we think, the most fast quantitative interpretation tool for global studies. We just call this method AS85 hereinafter for short. Although Gubbins et al. (2011) provided a formula to directly calculate the apparent magnetic vector distribution, the AS85 method introduced constraints of magnetized direction and thus corresponding results are expected to be more robust especially in world-wide continents. Therefore, in this study, we first improved the AS85 method further considering non-axial dipolar inducing field using formulae by Nolte & Siebert (1987), initial model or priori information for starting coefficients in the apparent susceptibility conversion, hidden longest-wavelength components of lithospheric magnetic field and field contaminations from global oceanic remanent magnetization. Then, we used the vertically integrated susceptibility model by Hemant & Maus (2005) and vertically integrated remanent magnetization model by Masterton et al. (2013) to test the validity of our improved method. Subsequently, we applied the conversion method to geomagnetic field models by CHAMP and Swarm satellite

  3. Earth's lithospheric magnetic field determined to spherical harmonic degree 90 from CHAMP satellite measurements

    DEFF Research Database (Denmark)

    Maus, S.; Rother, M.; Hemant, K.;

    2006-01-01

    The CHAMP magnetic field mission is providing highly reliable measurements from which the global lithospheric magnetic field can be determined in unprecedented resolution and accuracy. Using almost 5 yr of data, we derive our fourth generation lithospheric field model termed MF4, which is expanded...

  4. Inversion of Magnetic Measurements of the CHAMP Satellite Over the Pannonian Basin

    Science.gov (United States)

    Kis, K. I.; Taylor, P. T.; Wittmann, G.; Toronyi, B.; Puszta, S.

    2011-01-01

    The Pannonian Basin is a deep intra-continental basin that formed as part of the Alpine orogeny. In order to study the nature of the crustal basement we used the long-wavelength magnetic anomalies acquired by the CHAMP satellite. The anomalies were distributed in a spherical shell, some 107,927 data recorded between January 1 and December 31 of 2008. They covered the Pannonian Basin and its vicinity. These anomaly data were interpolated into a spherical grid of 0.5 x 0.5, at the elevation of 324 km by the Gaussian weight function. The vertical gradient of these total magnetic anomalies was also computed and mapped to the surface of a sphere at 324 km elevation. The former spherical anomaly data at 425 km altitude were downward continued to 324 km. To interpret these data at the elevation of 324 km we used an inversion method. A polygonal prism forward model was used for the inversion. The minimum problem was solved numerically by the Simplex and Simulated annealing methods; a L2 norm in the case of Gaussian distribution parameters and a L1 norm was used in the case of Laplace distribution parameters. We INTERPRET THAT the magnetic anomaly WAS produced by several sources and the effect of the sable magnetization of the exsolution of hemo-ilmenite minerals in the upper crustal metamorphic rocks.

  5. High Precision Orbit Determination of CHAMP Satellite

    Institute of Scientific and Technical Information of China (English)

    ZHAO Qile; LIU Jingnan; GE Maorong

    2006-01-01

    The precision orbit determination of challenging minisatellite payload(CHAMP) satellite was done based on position and navigation data analyst(PANDA) software which is developed in Wuhan University, using the onboard GPS data of year 2002 from day 126 to 131. The orbit accuracy was assessed by analyzing the difference from GFZ post-processed science orbits (PSO), the GPS carrier and pseudo-range data residuals and the satellite laser ranging (SLR) residuals.

  6. Interpretation of the Total Magnetic Field Anomalies Measured by the CHAMP Satellite Over a Part of Europe and the Pannonian Basin

    Science.gov (United States)

    Kis, K. I.; Taylor, Patrick T.; Wittmann, G.; Toronyi, B.; Puszta, S.

    2012-01-01

    In this study we interpret the magnetic anomalies at satellite altitude over a part of Europe and the Pannonian Basin. These anomalies are derived from the total magnetic measurements from the CHAMP satellite. The anomalies reduced to an elevation of 324 km. An inversion method is used to interpret the total magnetic anomalies over the Pannonian Basin. A three dimensional triangular model is used in the inversion. Two parameter distributions: Laplacian and Gaussian are investigated. The regularized inversion is numerically calculated with the Simplex and Simulated Annealing methods and the anomalous source is located in the upper crust. A probable source of the magnetization is due to the exsolution of the hematite-ilmenite minerals.

  7. Rayleigh LIDAR and satellite (HALOE, SABER, CHAMP and COSMIC) measurements of stratosphere-mesosphere temperature over a southern sub-tropical site, Reunion (20.8 S; 55.5 E). Climatology and comparison study

    Energy Technology Data Exchange (ETDEWEB)

    Sivakumar, V. [Univ. de La Reunion, Reunion Island (FR). Lab. de l' Atmosphere et des Cyclones (LACy); Council for Scientific and Industrial Research (CSIR), Pretoria (ZA). National Laser Centre (NLC); Pretoria Univ. (South Africa). Dept. of Geography, Geoinformatics and Meteorology; KwaZulu Natal Univ., Durban (South Africa). School of Physics; Vishnu Prasanth, P. [Univ. de La Reunion, Reunion Island (FR). Lab. de l' Atmosphere et des Cyclones (LACy); Sree Vidyanikethan Engineering College, Tirupathi, Andhra Pradesh (India); Kishore, P. [California Univ., Irvine, CA (United States). Dept. of Earth System Science; Bencherif, H. [Univ. de La Reunion, Reunion Island (FR). Lab. de l' Atmosphere et des Cyclones (LACy); Keckhut, P. [IPSL (UMR 8190), Guyancourt (FR). Lab. Atmospheres Milieux Observations Spatiales (LATMOS)

    2011-07-01

    For the first time, climatology of the middle atmosphere thermal structure is presented, based on 14 years of LIDAR and satellite (HALOE, SABER, CHAMP and COSMIC) temperature measurements. The data is collected over a southern sub-tropical site, Reunion Island (20.8 S; 55.5 E), for the height range between 30 and 60 km. The overall monthly mean temperature shows a maximum of 265-270K at the stratopause height region from {proportional_to}44-52 km and peaks during the months of March and November. Furthermore, the temperature profiles are compared with different satellite datasets (HALOE, CHAMP, COSMIC and SABER) and the results are found to be in reasonable agreement with each other, although a relative difference in temperature of {+-}5 to 6K is noticed. In comparison, LIDAR shows higher/lower temperatures for the lower mesosphere/upper stratosphere height region. The differences in temperature measured by the LIDAR and satellite measurements are analogous with previous results available elsewhere. Long-term temperature measurements are used to further study seasonal oscillations, especially annual, semi-annual and quasi-biennial oscillations. In comparison with SAO, the measured spectral amplitudes of AO shows dominant amplitudes in both the upper stratosphere and lower mesosphere height regions. Using LIDAR and the other satellite measurements, the quasi-biennial oscillation was found to be approximately 26 months. The spectral amplitudes are comparable to the results reported earlier by other researchers. (orig.)

  8. External field characterization using CHAMP satellite data for induction studies

    Science.gov (United States)

    Kunagu, Praveen; Chandrasekhar, E.

    2013-06-01

    Knowledge of external inducing source field morphology is essential for precise estimation of electromagnetic (EM) induction response. A better characterization of the external source field of magnetospheric origin can be achieved by decomposing it into outer and inner magnetospheric contributions, which are best represented in Geocentric Solar Magnetospheric (GSM) and Solar Magnetic (SM) reference frames, respectively. Thus we propose a spherical harmonic (SH) model to estimate the outer magnetospheric contribution, following the iterative reweighted least squares approach, using the vector magnetic data of the CHAMP satellite. The data covers almost a complete solar cycle from July 2001 to September 2010, spanning 54,474 orbits. The SH model, developed using orbit-averaged vector magnetic data, reveals the existence of a stable outer magnetospheric contribution of about 7.39 nT. This stable field was removed from the CHAMP data after transforming to SM frame. The residual field in the SM frame acts as a primary source for induction in the Earth. The analysis of this time-series using wavelet transformation showed a dominant 27-day periodicity of the geomagnetic field. Therefore, we calculated the inductive EM C-response function in a least squares sense considering the 27-day period variation as the inducing signal. From the estimated C-response, we have determined that the global depth to the perfect substitute conductor is about 1132 km and its conductivity is around 1.05 S/m.

  9. External field characterization using CHAMP satellite data for induction studies

    Indian Academy of Sciences (India)

    Praveen Kunagu; E Chandrasekhar

    2013-06-01

    Knowledge of external inducing source field morphology is essential for precise estimation of electromagnetic (EM) induction response. A better characterization of the external source field of magnetospheric origin can be achieved by decomposing it into outer and inner magnetospheric contributions, which are best represented in Geocentric Solar Magnetospheric (GSM) and Solar Magnetic (SM) reference frames, respectively. Thus we propose a spherical harmonic (SH) model to estimate the outer magnetospheric contribution, following the iterative reweighted least squares approach, using the vector magnetic data of the CHAMP satellite. The data covers almost a complete solar cycle from July 2001 to September 2010, spanning 54,474 orbits. The SH model, developed using orbit-averaged vector magnetic data, reveals the existence of a stable outer magnetospheric contribution of about 7.39 nT. This stable field was removed from the CHAMP data after transforming to SM frame. The residual field in the SM frame acts as a primary source for induction in the Earth. The analysis of this time-series using wavelet transformation showed a dominant 27-day periodicity of the geomagnetic field. Therefore, we calculated the inductive EM -response function in a least squares sense considering the 27-day period variation as the inducing signal. From the estimated -response, we have determined that the global depth to the perfect substitute conductor is about 1132 km and its conductivity is around 1.05 S/m.

  10. Observatory crustal magnetic biases during CHAMP satellite mission

    Directory of Open Access Journals (Sweden)

    G. Verbanac

    2015-01-01

    Full Text Available Taking advantage of nine years of CHAMP satellite mission (June 2000–August 2009, we investigate the temporal evolution of the observatory monthly crustal magnetic biases. To determine biases we compute X (northward, Y (eastward and Z (vertically downward monthly means from 42 observatory one-minute or hourly values, and compare them to synthetic monthly means obtained from a GRIMM3 core field model (V. Lesur, personal communication, 2014. Both short period variations and long term trends in the monthly bias time series are analyzed. A comparison with biases based on MAGSAT and Ørsted satellite data, related to the 1979.92 and 1992.92 epochs is performed. Generally, the larger biases averaged over nine years and the larger differences between biases based on different models are found in Z component. This can be the signature of the induced magnetic fields. Although annual trends in most bias series are observed, no clear evidence that the constant crustal field changed significantly over the studied period is found. Time series of monthly biases exhibit distinct oscillatory pattern in the whole time span, which we assign to the external field contributions. The amplitudes of these variations are linked with the phase of the solar cycle, being significantly larger in the period 2000–2005 than in the period 2006–2009. Clear semi-annual variations are evident in all components, with extremes in spring and fall months of each year. Common external field pattern is found for European monthly biases. A dependence of the bias monthly variations on geomagnetic latitudes is not found for the non-European observatories. The results from this study represent a base to further exploit the observatory and repeat stations magnetic biases together with the data from the new satellite mission SWARM.

  11. Low latitude electron temperature observed by the CHAMP satellite

    Czech Academy of Sciences Publication Activity Database

    Stolle, C.; Truhlík, Vladimír; Richards, P.; Olsen, N.

    Copernicus GmbH, 2012. ISSN 1607-7962 Institutional support: RVO:68378289 Keywords : Topside ionosphere * electron temperature * CHAMP http://meetingorganizer.copernicus.org/EGU2012/EGU2012-7753-1.pdf

  12. CHAOS-a model of the Earth's magnetic field derived from CHAMP, Orsted, and SAC-C magnetic satellite data

    DEFF Research Database (Denmark)

    Olsen, Nils; Luhr, H.; Sabaka, T.J.;

    2006-01-01

    We have derived a model of the near-Earth magnetic field (up to spherical harmonic degree n= 50 for the static field, and up to n = 18 for the first time derivative) using more than 6.5 yr of high-precision geomagnetic measurements from the three satellites Orsted, CHAMP and SAC-C taken between 1...... 1999 March and 2005 December. Our modelling approach goes in several aspects beyond that used for recent models: (i) we use different data selection criteria and allow for higher geomagnetic activity (index Kp......We have derived a model of the near-Earth magnetic field (up to spherical harmonic degree n= 50 for the static field, and up to n = 18 for the first time derivative) using more than 6.5 yr of high-precision geomagnetic measurements from the three satellites Orsted, CHAMP and SAC-C taken between...

  13. ‘DEOS CHAMP-01C 70’: a model of the Earth’s gravity field computed from accelerations of the CHAMP satellite

    NARCIS (Netherlands)

    Ditmar, P.G.; Kuznetsov, V.; Van Eck van der Sluis, A.A.; Schrama, E.; Klees, R.

    2005-01-01

    Performance of a recently proposed technique for gravity field modeling has been assessed with data from the CHAMP satellite. The modeling technique is a variant of the acceleration approach. It makes use of the satellite accelerations that are derived from the kinematic orbit with the 3-point numer

  14. ASC Champ Orbit Model

    DEFF Research Database (Denmark)

    Riis, Troels; Jørgensen, John Leif

    1999-01-01

    This documents describes a test of the implementation of the ASC orbit model for the Champ satellite.......This documents describes a test of the implementation of the ASC orbit model for the Champ satellite....

  15. Changes of lithospheric magnetic anomalies with altitude (According to the CHAMP satellite)

    Science.gov (United States)

    Abramova, D. Yu.; Filippov, S. V.; Abramova, L. M.; Varentsov, I. M.; Lozovskii, I. N.

    2016-03-01

    Maps of the magnitude of the full vector and the vertical component of an anomalous lithospheric magnetic field over the Voronezh anticline (VA) for the three high-altitude observation levels were compiled based on geomagnetic measurements from the CHAMP satellite. The isometric positive anomaly centered at about 50° N and 37° E stands out. Its amplitude decreases with increasing observation altitude without changing the form. Comparison of the parameters of the detected anomaly with data obtained for this site by other methods confirms that it really exists and that its spatial position is accurately determined, which indicates the reliability of the values of the selected field of lithospheric anomalies. The change in the parameters of the magnetic anomaly with respect to the observation level over the Earth's surface is consistent with the concepts of geological structural features of the lithosphere in the region. The anomaly offset to the south on the satellite altitudes apparently indicates an uplift of crystalline basement rocks and a more southern position of VA deep roots relative to that accepted in the global magnetization model. The use of satellite data obtained at different altitudes opens up additional possibilities for the application of gradient methods in the interpretation of the magnetic fields of lithospheric anomalies.

  16. In-flight Quality and Accuracy of Attitude Measurements from the CHAMP Advanced Stellar Compass

    DEFF Research Database (Denmark)

    Jørgensen, Peter Siegbjørn; Jørgensen, John Leif; Denver, Troelz;

    2005-01-01

    The German geo-observations satellite CHAMP carries highly accurate vector instruments. The orientation of these relative to the inertial reference frame is obtained using star trackers. These advanced stellar compasses (ASC) are fully autonomous units, which provide, in real time, the absolute...... with modeling external noise sources often arise. The special CHAMP configuration with two star tracker cameras mounted fixed together provides an excellent opportunity to determine the AIA in-flight using the inter boresight angle....

  17. Spatial frequencies associated with the latitudinal structures of ionospheric currents seen by CHAMP satellite

    Science.gov (United States)

    Thomas, Neethal; Vichare, Geeta; Sinha, A. K.

    2016-07-01

    The CHAMP magnetic field variations during international quiet days of low solar activity period 2008-2009 are investigated. The present paper reports the existence of frequency peaks ≤20 mHz in the compressional component of the magnetic field in almost all CHAMP passes. The magnetic field variations associated with these frequencies have amplitude of a few tens of nT during the daytime. The geomagnetic activity and interplanetary magnetic field parameters were observed to be low during the period of study. The spectral powers of the observed frequencies show no dependence on solar wind velocity and cone angle; hence, the reported frequencies are not related to the geomagnetic pulsations. For frequency-peaks ≤15 mHz, strong local time dependence is observed with maximum power near noon and minimum at night. The longitudinal and seasonal variation of the powers of these frequency peaks match well with those of the equator-to-middle latitude ionospheric currents derived by the earlier studies. As a polar Low Earth Orbiting (LEO) satellite spans the entire range of latitudes within few minutes, it monitors the geomagnetic field variations caused by the quiet-time ionospheric currents flowing at different latitudes. This can result in certain frequencies in the magnetic field recorded by LEO satellites. We demonstrate that the frequencies <10 mHz are mainly due to the latitudinal structure of the equatorial electrojet. The observed frequencies in CHAMP data are therefore attributed to the latitudinal structures of the ionospheric currents that are monitored only by the polar LEO satellites and are found to alter the observations of geomagnetic pulsations (Pc4-5 and Pi2) significantly.

  18. First scalar magnetic anomaly map from CHAMP satellite data indicates weak lithospheric field

    DEFF Research Database (Denmark)

    Maus, S.; Rother, M.; Holme, R.;

    2002-01-01

    and external field model, we remove remaining unmodeled large-scale external contributions from 120 track segments by subtracting a best-fitting uniform field. In order to preserve N/S trending features, the data are not filtered along-track. Direct integration of the spherically gridded data yields......Satellite magnetic anomaly maps derived by different techniques from Magsat/POGO data vary by more than a factor of 2 in the deduced strength of the lithospheric magnetic field. Here, we present a first anomaly map from new CHAMP scalar magnetic field data. After subtracting a recent Ørsted main...

  19. Effects of solar disturbances on the thermosphere densities and winds from CHAMP and GRACE satellite accelerometer data

    Science.gov (United States)

    Sutton, Eric K.

    2008-10-01

    This dissertation focuses on using a new satellite data source to characterize the response of the thermosphere to several different types of dynamical forcing. In this study, the methods used to calculate a continuous database of atmospheric parameters are developed and validated. In particular, the instruments available on the CHAllenging Mini-satellite Payload (CHAMP) mission are used to deduce in-situ atmospheric density and a component of wind velocity in the thermosphere. The global coverage and thorough sampling of local time, afforded by the carefully chosen orbital parameters of the satellite mission, ensure the value of this dataset. In addition, the unprecedented spatial and temporal resolution provided by the CHAMP satellite enables the in-depth analyses of several response characteristics of the neutral atmosphere which have rarely, and in some cases never, been observed directly. Over large time scales, Solar Extreme Ultraviolet (EUV) radiation provides the majority of energy that heats the thermosphere, while Joule heating associated with high-latitude geomagnetic disturbances is a sporadic, yet often more intense source. Both of these sources are capable of providing short bursts of energy which can excite different modes of response, including atmospheric gravity waves and enhanced global circulation. These features are observed in CHAMP data and compared with numerical simulations from the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) developed by the National Center for Atmospheric Research (NCAR), which embodies our current level of understanding of the upper atmosphere.

  20. Fluctuations in the ionosphere related to Honshu Twin Large Earthquakes of September 2004 observed by the DEMETER and CHAMP satellites

    Science.gov (United States)

    Ryu, Kwangsun; Chae, Jang-Soo; Lee, Ensang; Parrot, Michel

    2014-12-01

    While investigating possible precursory signatures of large earthquakes in the ionospheric data measured by the DEMETER and CHAMP satellites, we found ionospheric disturbances related to large earthquakes (M=7.2 and 7.4) that occurred on September 2004 near the south coast of Honshu, Japan. The satellite data were statistically compared with an empirical model and local averages of the large set of data in the study period. A fluctuation in the electron density above the epicenter was observed roughly 2 weeks before the main earthquakes. Surveys of the space weather and geomagnetic activities suggest that these fluctuations were not caused by changes in space conditions or by a geomagnetic storm. The features were also distinct from well-known natural ionospheric anomalies. In addition, a peak-like profile in the ion temperature and lowered O+ density around the region of the epicenter was observed a week before the main earthquakes along the satellite passes whose longitudes are close to the epicenter. The features are more apparent when they are compared with the data more distant from the epicenter, suggesting that the disturbances occur along the geomagnetic field lines. The concurrent measurements of the ion drift velocity suggest the fluctuations were triggered by the vertical plasma drift. The observed anomalies disappeared ∼ 2 weeks after the quakes. According to the current theories on the seismo-ionospheric coupling, the horizontal electric field at the lower boundary of the ionosphere should have been strengthened by the seismic activity in order for the ionospheric plasma movements above the epicenter and its geomagnetic conjugate regions to trigger the observed ionospheric anomalies.

  1. The Design, Construction and Test of stray light suppression baffles for the CHAMP satellite

    DEFF Research Database (Denmark)

    Jørgensen, John Leif

    1997-01-01

    The Advanced Stellar Compass, to be delivered from IAU to the CHAMP project, requires some kind of stray-light suppressing shade to be mounted in front of the lens, in order to minimize the thermal impact and to maximize the performance envelope when subjected to non-stellar external light sources...

  2. First champ mission results for gravity, magnetic and atmospheric studies

    CERN Document Server

    Lühr, Hermann; Schwintzer, Peter

    2003-01-01

    In the summer of 2000 the German geo-research satellite CHAMP was launched into orbit. Its innovative payload arrangement and the low intial orbit allow CHAMP to simultaneously collect and almost continuously analyse precise data relating to gravity and magnetic fields at low altitude. In addition to this CHAMP also measures the neutral atmosphere and ionosphere using GPS techniques. Eighteen months after the launch, CHAMP research groups from all over the world met at the Geo-Forschungs-Zentrum in Potsdam for an initial exchange of experiences and results. The main outcome of this user meeting is summarized in this volume. Apart from technical information about the mission, the book offers a comprehensive insight into the present status of CHAMP data exploitation for Earth system research and practical applications in geodesy, geophysics and meteorology.

  3. IMF dependence of high-latitude thermospheric wind pattern derived from CHAMP cross-track measurements

    Science.gov (United States)

    Förster, M.; Rentz, S.; Köhler, W.; Liu, H.; Haaland, S. E.

    2008-06-01

    Neutral thermospheric wind pattern at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both North and South polar regions are statistically analyzed in their dependence on the Interplanetary Magnetic Field (IMF) direction in the GSM y-z plane (clock angle). We compare this dependency with magnetospheric convection pattern obtained from the Cluster EDI plasma drift measurements under the same sorting conditions. The IMF-dependency shows some similarity with the corresponding high-latitude plasma convection insofar that the larger-scale convection cells, in particular the round-shaped dusk cell for ByIMF+ (ByIMF-) conditions at the Northern (Southern) Hemisphere, leave their marks on the dominant general transpolar wind circulation from the dayside to the nightside. The direction of the transpolar circulation is generally deflected toward a duskward flow, in particular in the evening to nighttime sector. The degree of deflection correlates with the IMF clock angle. It is larger for ByIMF+ than for ByIMF- and is systematically larger (~5°) and appear less structured at the Southern Hemisphere compared with the Northern. Thermospheric cross-polar wind amplitudes are largest for BzIMF-/ByIMF- conditions at the Northern Hemisphere, but for BzIMF-/ByIMF+ conditions at the Southern because the magnetospheric convection is in favour of largest wind accelerations over the polar cap under these conditions. The overall variance of the thermospheric wind magnitude at Southern high latitudes is larger than for the Northern. This is probably due to a larger "stirring effect" at the Southern Hemisphere because of the larger distance between the geographic and geomagnetic frameworks.

  4. Determination of a gravity field model from one month of CHAMP satellite data using accelerations

    OpenAIRE

    Abt, Tin Lian

    2004-01-01

    A gravity field model has been estimated based on reduced dynamic and kinematic state vectors of CHAMP. Newton Interpolation has been used to calculate accelerations and Least-Squares Collocation to estimate the spherical harmonic coefficients. During data preprocessing positions and velocities of the reduced dynamic and kinematic state vectors are synchronized so that two corresponding data sets of one month (July 2002) with a sampling rate of 30s are achieved. Observations where the kine...

  5. First scalar magnetic anomaly map from CHAMP satellite data indicates weak lithospheric field

    OpenAIRE

    Maus, S.; Martin Rother; R. T. Holme; Hermann Lühr; Olsen, N; V. Haak

    2002-01-01

    Satel1ite magnetic anomaly maps derived by different techniques from Magsat/POGO data vary by more than a factor of 2 in the deduced strength of the lithospheric magnetic field. Here, we present a first anomaly map from new CHAMP scalar magnetic field data. After subtracting a recent 0rsted main and external field model, we remove remaining unmodeled large-scale external contributions from 120° track segments by subtracting a best-fitting uniform field. In order to preserve N/S trending featu...

  6. Spatial frequencies associated with the latitudinal structures of ionospheric currents seen by CHAMP satellite

    CERN Document Server

    Thomas, Neethal; Sinha, A K

    2015-01-01

    The CHAMP magnetic field variations during international quiet days of low solar activity period 2008-2009 are investigated. The present paper reports the existence of frequency-peaks < 20 mHz in the compressional component of the magnetic field in almost all CHAMP passes. The magnetic field variations associated with these frequencies have amplitude of a few tens of nT during daytime. The geomagnetic activity and interplanetary magnetic field parameters were observed to be low during the period of study. The spectral powers of the observed frequencies show no dependence on solar wind velocity and cone angle; hence the reported frequencies are not related to the geomagnetic pulsations. For frequency-peaks <15 mHz, strong local-time dependence is observed with maximum power near noon and minimum at night. The longitudinal and seasonal variations of the powers of these frequency-peaks match well with those of the equator-to-middle latitude ionospheric currents derived by the earlier studies. As a polar Lo...

  7. The specific features of gold ore provinces of the south of Siberia in a magnetic field at ground height and heights of flight of satellite Champ.

    Science.gov (United States)

    Litvinova, Tamara; Petrova, Alevtina

    2010-05-01

    The specific features of gold ore provinces of the south of Siberia in a magnetic field at ground height and heights of flight of satellite Champ. T.Litvinova -All-Russian Geological Research Institute (VSEGEI) A. Petrova - St. Petersburg, SPbF IZMIRAN, Russian Academy of Sciences, St. Petersburg For allocation of specific features known gold ore objects (Olimpiadninskoje, Suchoi Log, etc.) is executed the morphological analysis of the magnetic field received on materials of aeromagnetic data and satellite measurements at heights of 100 and 400 km. On the ground data on a map of magnetic anomalies of Russia of scale 1:2 500000 of 50 km on the extended structures crossing known gold ore deposits and promising ore units have been constructed geomagnetic and densitys sections up to depth. On geomagnetic and densitys sections to known large gold ore to deposits are dated deep synvertical the permeable zones described by a synlenticular -layered structure. Extended horizons of not magnetic formations are located on depths about 10, 12, 15-18, 30 and 40 km. On deep densitys sections reference sites ¬ the Suchoi Log, Olimpiadninskoje and Vodorazdelnoje ¬ is characterized by zones of inversion of density. Areas of the loosened breeds are dated to synvertical to deep zones of hydrothermal and fluid study of breeds inside which the loosened lenses in intervals of depths from 2 up to 5 km are formed, 8-13 km, 18-20 and 25-30 km of 35-40 km within the limits of the bottom bark. The analysis of a magnetic field has shown, that gold mineralization in researched region is dated for zones of long-living regional explosive infringements, to permeable terrigenous to thicknesses of depressions, to adjournment depression structures in units of crossing of tectonofluid zones of diagonal orientation. Terrigenous adjournment depression structures are shown on a geomagnetic section as the powerful deflections filled with low-magnetic thicknesses. These deflections are dated to

  8. Characterization of CHAMP magnetic data anomalies: magnetic contamination and measurement timing

    International Nuclear Information System (INIS)

    The CHAMP (CHAllenging Minisatellite Payload) mission ended after more than ten years in space on 19 September 2010. For achieving a high measurement accuracy of the magnetometers on CHAMP, detailed analyses of spacecraft magnetic characteristics in orbit are required. A decade of continuous magnetometer and housekeeping data are a good basis for evaluating some of the effects of variable spacecraft magnetic fields on the ambient field determination. It was found that some perturbations of FGM (FluxGate vector Magnetometer) or OVM (OVerhauser scalar Magnetometer) measurements are caused by stray fields induced by the power system, the ASC (advanced stellar compass) instrument or magneto-torquer currents. The magnetic effect of solar currents on FGM measurements varies with the local time of the orbit and amounts to 0.2 nT. In cases when one head of the ASC instrument was blinded by the sun, sometimes transient drops in instrument current strength occur, which were accompanied by magnetic disturbance signals (∼0.3 nT) in FGM measurements. The magnetic residual contamination of OVM data by the torquer currents was of order 0.1 nT but still detectable. An improved torquer correction matrix is derived which eliminates this effect. In-flight scalar calibration parameters revealed some of the effects of timing anomalies. Time lags between FGM and OVM readings are misinterpreted by the scalar calibration as variations of the angles between some of the sensor axes. The resulting amplitudes of the anomalies presented here lie in the range of some 0.1 nT, but they are systematic in nature. (paper)

  9. CHAMP gravity field recovery using the energy balance approach

    Directory of Open Access Journals (Sweden)

    Ch. Gerlach

    2003-01-01

    Full Text Available Since the early days of satellite geodesy energy balance based methods for gravity field determination have been considered. If non-conservative forces are known the Hamiltonian along the orbit is a constant of the motion. Thus the gravity field can be determined if position and velocity of the satellite are known and accelerometer measurements are available to model the non-conservative part. CHAMP is the first satellite that provides the user with those three kinds of data nearly continuously. Numerical investigations using real CHAMP data are presented to show the feasibility of the method. Using a semi-analytical approach the gravity field can be determined efficiently by a 2D-Fourier method. Those fast computations also give way to application of the method not only to a full gravity field recovery but also, e.g. for quick-look and validation of SST observations for satellite missions like CHAMP, GRACE or GOCE. The method can also be used for estimation of accelerometer calibration parameters.Key words. gravity field, energy balance, Jacobi-integral, non-conservative forces, accelerometer calibration, CHAMP

  10. External source field characterization and electromagnetic induction response of the deep earth using CHAMP satellite magnetic data

    OpenAIRE

    Venkata Praveen Kumar Kunagu

    2013-01-01

    The steady progresses in the precise measurement of geomagnetic field using land-based observatories and satellites and adapting sophisticated mathematical tools, viz., spherical harmonics, splines, wavelets etc., for data analysis and interpretation, have improved our knowledge about the presence of several contributing sources (both external and internal) in the measured magnetic field. However, for determining a precise global geomagnetic field model, a uniform and full global coverage dat...

  11. CHAMP Magnetic Anomalies of the Antarctic Crust

    Science.gov (United States)

    Kim, Hyung Rae; Gaya-Pique, Luis R.; vonFrese, Ralph R. B.; Taylor, Patrick T.; Kim, Jeong Woo

    2003-01-01

    Regional magnetic signals of the crust are strongly masked by the core field and its secular variations components and hence difficult to isolate in the satellite measurements. In particular, the un-modeled effects of the strong auroral external fields and the complicated- behavior of the core field near the geomagnetic poles conspire to greatly reduce the crustal magnetic signal-to-noise ratio in the polar regions relative to the rest of the Earth. We can, however, use spectral correlation theory to filter the static lithospheric and core field components from the dynamic external field effects. To help isolate regional lithospheric from core field components, the correlations between CHAMP magnetic anomalies and the pseudo magnetic effects inferred from gravity-derived crustal thickness variations can also be exploited.. Employing these procedures, we processed the CHAMP magnetic observations for an improved magnetic anomaly map of the Antarctic crust. Relative to the much higher altitude Orsted and noisier Magsat observations, the CHAMP magnetic anomalies at 400 km altitude reveal new details on the effects of intracrustal magnetic features and crustal thickness variations of the Antarctic.

  12. Comprehensive study of ULF upstream waves observed in the topside ionosphere by CHAMP and on the ground

    OpenAIRE

    Heilig, B; H. Lühr; Rother, M.

    2007-01-01

    Based on magnetic field measurements from the satellite CHAMP, a detailed picture could be obtained of the upstream wave (UW) distribution in the topside ionosphere. The low, near-polar orbit of CHAMP, covering all local times, allows the global distribution of this type of pulsation to be revealed. The observations from space are compared to recordings of the ground-based MM100 meridional array covering the latitude range 66° to 42° in magnetic coordinates. UWs show up very c...

  13. Comprehensive study of ULF upstream waves observed in the topside ionosphere by CHAMP and on the ground

    OpenAIRE

    Heilig, B; H. Lühr; Rother, M.

    2007-01-01

    Based on magnetic field measurements from the satellite CHAMP, a detailed picture could be obtained of the upstream wave (UW) distribution in the topside ionosphere. The low, near-polar orbit of CHAMP, covering all local times, allows the global distribution of this type of pulsation to be revealed. The observations from space are compared to recordings of the ground-based MM100 meridional array covering the latitude range 66° to 42° in magnetic coordinates. UWs show...

  14. Documentation for delivery of Star Tracker to CHAMP

    DEFF Research Database (Denmark)

    Madsen, Peter Buch; Betto, Maurizio; Jørgensen, John Leif;

    1999-01-01

    The documentation EIDP (End Item Data Package) describes all the tests which have been performed on the flight hardware of the Star Tracker for the German satellite CHAMP.......The documentation EIDP (End Item Data Package) describes all the tests which have been performed on the flight hardware of the Star Tracker for the German satellite CHAMP....

  15. Thermospheric vorticity at high geomagnetic latitudes from CHAMP data and its IMF dependence

    NARCIS (Netherlands)

    Förster, M.; Haaland, S.E.; Doornbos, E.N.

    2011-01-01

    Neutral thermospheric wind pattern at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both polar regions are used to deduce statistical neutral wind vorticity distributions and were analyzed in their dependence on the Interplanetary Magnetic Field (IMF

  16. Field-aligned current associated with low-latitude plasma blobs as observed by the CHAMP satellite

    Directory of Open Access Journals (Sweden)

    J. Park

    2010-03-01

    Full Text Available Here we give two examples of low-latitude plasma blobs accompanied by linearly polarized perpendicular magnetic deflections which imply that associated field-aligned currents (FACs have a 2-D sheet structure located at the blob walls. The estimated FAC density is of the order of 0.1 μA/m2. The direction of magnetic deflections points westward of the magnetic meridian and there is a linear correlation between perpendicular and parallel variations. All these properties are similar to those of equatorial plasma bubbles (EPBs. According to CHAMP observations from August 2000 to July 2004, blobs show except for these two good examples no clear signatures of 2-D FAC sheets at the walls. Generally, perpendicular magnetic deflections inside blobs are weaker than inside EPBs on average. Our results are consistent with existing theories: if a blob exists, (1 a significant part of EPB FAC will be closed through it, exhibiting similar perpendicular magnetic deflection inside EPBs and blobs, (2 the FAC closure through blobs leads to smaller perpendicular magnetic deflection at its poleward/downward side, and (3 superposition of different FAC elements might result in a complex magnetic signature around blobs.

  17. High speed pulsed magnetic fields measurements, using the Faraday effect; Mesures de champs magnetiques pulses rapides a l'aide de l'effet Faraday

    Energy Technology Data Exchange (ETDEWEB)

    Dillet, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-12-01

    For these measures, the information used is the light polarization plane rotation induced by the magnetic field in a glass probe. This rotation is detected using a polarizer-analyzer couple. The detector is a photomultiplier used with high-current and pulsed light. In a distributed magnet (gap: 6 x 3 x 3 cm) magnetic fields to measure are 300 gauss, lasting 0.1 {mu}s, with rise times {<=} 35 ns, repetition rate: 1/s. An oscilloscope is used to view the magnetic field from the P.M. plate signal. The value of the field is computed from a previous static calibration. Magnetic fields from 50 to 2000 gauss (with the probe now used) can be measured to about 20 gauss {+-} 5 per cent, with a frequency range of 30 MHz. (author) [French] Pour faire de telles mesures, on utilise comme information la rotation du plan de polarisation de la lumiere provoquee par le champ magnetique dans une sonde en verre. On detecte cette rotation au moyen d'un polariseur et d'un analyseur, qui sont regles a 45 deg. pour conserver un phenomene lineaire. Le detecteur est un photomultiplicateur travaillant en fort courant en lumiere pulsee. Dans un aimant distribue d'entrefer 6 x 3 x 3 cm, on obtient des champs magnetiques a mesurer de 300 gauss, durant 0.1 {mu}s, avec des temps de montee {<=} 35 ns; au taux de 1 fois par seconde. L'observation du champ se fait sur oscilloscope a partir du signal de plaque du P.M. La valeur absolue du champ est obtenue au moyen d'un etalonnage statique prealable. On peut ainsi mesurer a 20 gauss et {+-} 5 pour cent pres environ des champs magnetiques de 50 a 2000 gauss (avec la sonde actuelle) et avec une bande passante de 30 MHz. (auteur)

  18. Comprehensive study of ULF upstream waves observed in the topside ionosphere by CHAMP and on ground

    OpenAIRE

    Heilig, B; Hermann Lühr; Martin Rother

    2007-01-01

    Based on magnetic field measurements from the satellite CHAMP, a detailed picture could be obtained of the upstream wave (UW) distribution in the topside ionosphere. The low, near-polar orbit of CHAMP, covering all local times, allows the global distribution of this type of pulsation to be revealed. The observations from space are compared to recordings of the ground-based MM100 meridional array covering the latitude range 66° to 42° in magnetic coordinates. UWs show up very clearly in the co...

  19. IMF Dependence of High-Latitude Thermospheric Wind Pattern Derived from CHAMP Cross-Track Accelerometer Data and the Corresponding Magnetospheric Convection from Cluster EDI Measurements

    Science.gov (United States)

    Foerster, Matthias; Haaland, Stein E.; Rentz, Stefanie; Liu, Huixin

    Neutral thermospheric wind pattern at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both North and South polar regions are statistically analyzed in their dependence on the Interplanetary Magnetic Field (IMF) direction in the GSM y-z plane (clock angle). We compare this dependency with magnetospheric convection pattern using 1-min-averages of Cluster/EDI electric drift observations and the same IMF and solar wind sorting conditions. The spatially distributed Cluster/EDI measurements are mapped to a the common reference level at ionospheric F-region heights in a magnetic latitude/MLT grid. We obtained both regular thermospheric wind and plasma drift pattern according to the various IMF conditions. The IMF-dependency shows some similarity with the corresponding high-latitude plasma convection insofar that the larger-scale convection cells, in particular the round-shaped dusk cell for IMF By+ (By-) conditions at the Northern (Southern) Hemisphere, leave their marks on the dominant general transpolar wind circulation from the dayside to the nightside. The direction of the transpolar circulation is generally deflected toward a duskward flow, in particular in the evening to nighttime sector. The degree of deflection correlates with the IMF clock angle. It is larger for IMF By+ than for Byand is systematically larger (about 5 deg) and appear less structured at the Southern Hemisphere compared with the Northern. Thermospheric cross-polar wind amplitudes are largest for IMF Bz-/Byconditions (corresponding to sector 5) at the Northern Hemisphere, but for IMF Bz-/By+ conditions (sector 3) at the Southern because the magnetospheric convection is in favour of largest wind accelerations over the polar cap under these conditions. The overall variance of the thermospheric wind magnitude at Southern high latitudes is larger than for the Northern. This is probably due to a larger "stirring effect" at the Southern Hemisphere because

  20. Characteristics of satellite accelerometer measurements of thermospheric neutral winds at high latitudes

    Science.gov (United States)

    Doornbos, E.; Ridley, A. J.; Cnossen, I.; Aruliah, A. L.; Foerster, M.

    2015-12-01

    Thermospheric neutral winds play an important part in the coupled thermosphere-ionosphere system at high latitudes. Neutral wind speeds have been derived from the CHAMP and GOCE satellites, which carried precise accelerometers in low Earth orbits. Due to the need to simultaneously determine thermosphere neutral density from the accelerometer in-track measurements, only information on the wind component in the cross-track direction, perpendicular to the flight direction can be derived. However, contrary to ground-based Fabry-Perot interferometer and scanning Doppler imager observations of the thermosphere wind, these satellite-based measurements provide equally distributed coverage over both hemispheres. The sampling of seasonal and local time variations depend on the precession rate of the satellite's orbital plane, with CHAMP covering about 28 cycles of 24-hour local solar time coverage, during its 10 year mission (2000-2010), while the near sun-synchronous orbit of GOCE resulted in a much more limited local time coverage ranging from 6:20 to 8:00 (am and pm), during a science mission duration of 4 years (2009-2013). For this study, the wind data from both CHAMP and GOCE have been analysed in terms of seasonal variations and geographic and geomagnetic local solar time and latitude coordinates, in order to make statistical comparisons for both the Northern and Southern polar areas. The wind data from both satellites were studied independently and in combination, in order to investigate how the strengths and weaknesses of the instruments and orbit parameters of these missions affect investigations of interhemispheric differences. Finally, the data have been compared with results from coupled ionosphere-thermosphere models and from ground-based FPI and SDI measurements.

  1. Measurement-based perturbation theory and differential equation parameter estimation for high-precision high-resolution reconstruction of the Earth's gravitational field from satellite tracking measurements

    CERN Document Server

    Xu, Peiliang

    2016-01-01

    The numerical integration method has been routinely used to produce global standard gravitational models from satellite tracking measurements of CHAMP/GRACE types. It is implemented by solving the differential equations of the partial derivatives of a satellite orbit with respect to the unknown harmonic coefficients under the conditions of zero initial values. From the mathematical point of view, satellite gravimetry from satellite tracking is the problem of estimating unknown parameters in the Newton's nonlinear differential equations from satellite tracking measurements. We prove that zero initial values for the partial derivatives are incorrect mathematically and not permitted physically. The numerical integration method, as currently implemented and used in satellite gravimetry and statistics, is groundless. We use three different methods to derive new local solutions to the Newton's nonlinear governing differential equations of motion with a nominal reference orbit. Bearing in mind that satellite orbits ...

  2. GPS Radio Occultation: Results from CHAMP, GRACE and FORMOSAT-3/COSMIC

    Directory of Open Access Journals (Sweden)

    Jens Wickert

    2009-01-01

    Full Text Available The Taiwan/US FORMOSAT-3/COSMIC (FORMOsa SATellite mission - 3/Constellation Observing System for Meteorology, Ionosphere and Climate satellite nstellation was successfully launched on 14 April 2006. It is expected to leverage the use of the GPS (Global Positioning System radio occultation data for atmospheric and ionospheric research to improve global weather forecasts and aid climate change related studies. FORMOSAT-3/COSMIC, together with the European MetOp, German CHAMP and US/German GRACE-A satellites, form a 9 satellite constellation for precise atmospheric sounding on a global scale. This satellite constellation is expected to provide about 3500 occultation measurements daily. Recent results and the status of the CHAMP and GRACE-A orbit and occultation data analysis are reviewed and complemented with a review of initial results from FORMOSAT-3/COSMIC at GFZ. The significantly increased potential of the CHAMP, GRACE-A and FORMOSAT-3/COSMIC constellation for atmospheric tudies, ompared to single satellite missions, is demonstrated for selected applications such as global monitoring of water vapor distributions, tropopause parameters and ionospheric irregularities.

  3. Evaluation of the Geomagnetic Field Models based on Magnetometer Measurements for Satellite's Attitude Determination System

    Science.gov (United States)

    Cilden, Demet; Kaymaz, Zerefsan; Hajiyev, Chingiz

    2016-07-01

    Magnetometers are common attitude determination sensors for small satellites at low Earth orbit; therefore, magnetic field model of the Earth is necessary to estimate the satellite's attitude angles. Difference in the components of the magnetic field vectors -mostly used as unit vector. Therefore the angle between them (model and measurement data) affects the estimation accuracy of the satellite's attitude. In this study, geomagnetic field models are compared with satellite magnetic field observations in order to evaluate the models using the magnetometer results with high accuracy. For attitude determination system, IGRF model is used in most of the cases but the difference between the sensor and model increases when the geomagnetic activity occurs. Hence, several models including the empirical ones using the external variations in the Earth's geomagnetic field resulting from the solar wind and interplanetary magnetic field are of great importance in determination of the satellite's attitude correctly. IGRF model describes the internal-part of the geomagnetic field, on the other hand candidate models to IGRF, such as recently developed POMME-6 model based on Champ data, CHAOS-5 (CHAmp, Oersted, Swarm), T89 (Tsyganenko's model), include simple parameterizations of external fields of magnetospheric sources in addition to the internal field especially for low Earth orbiting satellites. Those models can be evaluated to see noticeable difference on extraterrestrial field effects on satellite's attitude determination system changing with its height. The comparisons are made between the models and observations and between the models under various magnetospheric activities. In this study, we will present our preliminary results from the comparisons and discuss their implications from the satellite attitude perspective.

  4. Estudio de las observaciones de tropopausa sobre el cono sur de Sudamérica mediante GPS a bordo de los satélites SAC-C y CHAMP Tropopause observation study over southern South America using GPS data from SAC-C and CHAMP satellites

    Directory of Open Access Journals (Sweden)

    S. Gabriela Lakkis

    2006-12-01

    Full Text Available En este trabajo se analiza la validez de la técnica de radio ocultación satelital (GPS llevada a cabo por los satélites SAC-C y CHAMP en tres estaciones chilenas y cuatro argentinas, como referencia del Cono Sur, durante el período 2001-2003. La validez de la técnica se discute por medio de la comparación de los parámetros atmosféricos obtenidos a partir de los satélites con los valores de radiosondeo. Una vez validada la ocultación para las latitudes estudiadas, en función de los datos satelitales se calcula temperatura, presión y altura de la tropopausa, así como valores de presión de vapor de agua y su comportamiento. De los resultados obtenidos del trabajo surge que las ocultaciones arrojan valores que se ajustan muy bien a los tradicionales radiosondeos, especialmente en la zona atmosférica comprendida entre superficie y los 10 kilómetros. De los registros satelitales se estimó que la tropopausa extratropical entre las longitudes 80° S y 60° S presenta valores de temperatura que fluctúan entre los 204 y los 222 K para el Hemisferio Sur hasta el trópico de Capricornio, con una altura mínima de 9 kilómetros y una máxima de 15.3 kilómetros. Para los valores de presión de vapor de agua se observó un comportamiento fuertemente decreciente a medida que se asciende desde la troposfera, hasta llegar a la estabilización en la estratosfera una vez atravesada la tropopausa, donde la variable presenta un cambio en la tasa de variación.Validation of radio occultation technique by Global Positioning System (GPS, carried out on board the SAC-C and CHAMP satellites, is analyzed over three stations of Chile and four for Argentine, as a reference for South America during 2001-2003. The discussion is based on the statistical comparison of the data of GPS with data from nearby radiosonde measurements. Though the occultation concept for obtaining profiles of atmospheric parameters, data derived from GPS, were used to calculate

  5. Comparison of ionospheric radio occultation CHAMP data with IRI 2001

    Directory of Open Access Journals (Sweden)

    N. Jakowski

    2004-01-01

    Full Text Available GPS radio occultation measurements on board low Earth orbiting satellites can provide vertical electron density profiles of the ionosphere from satellite orbit heights down to the bottomside. Ionospheric radio occultation (IRO measurements carried out onboard the German CHAMP satellite mission since 11 April 2001 were used to derive vertical electron density profiles (EDP’s on a routine basis. About 150 vertical electron density profiles may be retrieved per day thus providing a huge data basis for testing and developing ionospheric models. Although the validation of the EDP retrievals is not yet completed, the paper addresses a systematic comparison of about 78 000 electron density profiles derived from CHAMP IRO data with the International Reference Ionosphere (IRI 2001. The results are discussed for quite different geophysical conditions, e.g. as a function of latitude, local time and geomagnetic activity. The comparison of IRO data with corresponding IRI data indicates that IRI generally overestimates the upper part of the ionosphere whereas it underestimates the lower part of the ionosphere under high solar activity conditions. In a first order correction this systematic deviation could be compensated by introducing a height dependence correction factor in IRI profiling.

  6. Comprehensive study of ULF upstream waves observed in the topside ionosphere by CHAMP and on the ground

    OpenAIRE

    Heilig, B; H. Lühr; Rother, M.

    2007-01-01

    Based on magnetic field measurements from the satellite CHAMP, a detailed picture could be obtained of the upstream wave (UW) distribution in the topside ionosphere. The low, near-polar orbit of CHAMP, covering all local times, allows the global distribution of this type of pulsation to be revealed. The observations from space are compared to recordings of the ground-based MM100 meridional array covering the latitude range 66° to 42° in magnetic coordinates. UWs show up very clearly in the co...

  7. The adjoint sensitivity method of global electromagnetic induction for CHAMP magnetic data

    International Nuclear Information System (INIS)

    Complete text of publication follows. Martinec and McCreadie (2004) developed a time-domain spectral-finite element approach for the forward modelling of electromagnetic induction vector data as measured by the CHAMP satellite. Here, we present a new method of computing the sensitivity of the CHAMP electromagnetic induction data on the Earth's mantle electrical conductivity, which we term the adjoint sensitivity method. The forward and adjoint initial boundary-value problems, both solved in the time domain, are identical, except for the specification of prescribed boundary conditions. The respective boundary-value data at the satellite's altitude are the X magnetic component measured by the CHAMP vector magnetometer along satellite tracks for the forward method and the difference between the measured and predicted Z magnetic component for the adjoint method. The squares of these differences summed up over all CHAMP tracks determine the misfit. The sensitivity of the CHAMP data, that is the partial derivatives of the misfit function with respect to mantle conductivity parameters, are then determined by the scalar product of the forward and adjoint solutions, multiplied by the gradient of the conductivity and integrated over all CHAMP tracks. Such exactly determined sensitivities are checked against numerical differentiation of the misfit, and very good agreement is obtained. The attractiveness of the adjoint method lies in the fact that the adjoint sensitivities are calculated for little cost, regardless of the number of conductivity parameters. However, since the adjoint solution proceeds backwards in time, the forward solution must be stored at each time step, leading to memory requirements that are linear with respect to the number of steps undertaken. Having determined the sensitivities, we apply the conjugate gradient method to infer 1-D and 2-D conductivity structures of the Earth based on the CHAMP residual time serie (after the subtraction of static field

  8. Study of Normalized Technology of CHAMP Satellite Geomagnetic Survey Data Modeling in Magnetic Anomaly Field%磁异常场建模中的CHAMP卫星磁测数据通化技术的研究

    Institute of Scientific and Technical Information of China (English)

    罗开奇; 张有明

    2012-01-01

    Based on the CHAMP satellite geomagnetic survey data from 2000 to 2008, we have studied normalized technology of satellite geomagnetic survey data modeling in anomalous field, established Taylor polynomial model of Sichuan -Yunnan geomagnetic anomaly region and compared it with MF6 which is the latest geomagnetic anomaly field model%根据2000~2008年CHAMP卫星磁测数据,研究磁异常场建模中的卫星磁测数据通化技术,建立了川滇地区磁异常场的泰勒多项式模型,并和最新的磁异常场模型MF6做了比较.

  9. Enhanced E-layer ionization in the auroral zones observed by radio occultation measurements onboard CHAMP and Formosat-3/COSMIC

    OpenAIRE

    Mayer, C.; Jakowski, N.

    2009-01-01

    Particle precipitation of magnetospheric origin causes additional ionization in the auroral zone at E-layer heights. During night-time, in particular at winter-night, the E-layer ionization may dominate over the F2-layer ionization level. To study the geophysical conditions and characteristics of the related ionospheric processes in more detail, we use GPS radio occultation electron density profile retrievals from CHAMP and Formosat-3/COSMIC to extract thos...

  10. Analysis of the IMAGE RPI electron density data and CHAMP plasmasphere electron density reconstructions with focus on plasmasphere modelling

    Science.gov (United States)

    Gerzen, T.; Feltens, J.; Jakowski, N.; Galkin, I.; Reinisch, B.; Zandbergen, R.

    2016-09-01

    The electron density of the topside ionosphere and the plasmasphere contributes essentially to the overall Total Electron Content (TEC) budget affecting Global Navigation Satellite Systems (GNSS) signals. The plasmasphere can cause half or even more of the GNSS range error budget due to ionospheric propagation errors. This paper presents a comparative study of different plasmasphere and topside ionosphere data aiming at establishing an appropriate database for plasmasphere modelling. We analyze electron density profiles along the geomagnetic field lines derived from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite/Radio Plasma Imager (RPI) records of remote plasma sounding with radio waves. We compare these RPI profiles with 2D reconstructions of the topside ionosphere and plasmasphere electron density derived from GNSS based TEC measurements onboard the Challenging Minisatellite Payload (CHAMP) satellite. Most of the coincidences between IMAGE profiles and CHAMP reconstructions are detected in the region with L-shell between 2 and 5. In general the CHAMP reconstructed electron densities are below the IMAGE profile densities, with median of the CHAMP minus IMAGE residuals around -588 cm-3. Additionally, a comparison is made with electron densities derived from passive radio wave RPI measurements onboard the IMAGE satellite. Over the available 2001-2005 period of IMAGE measurements, the considered combined data from the active and passive RPI operations cover the region within a latitude range of ±60°N, all longitudes, and an L-shell ranging from 1.2 to 15. In the coincidence regions (mainly 2 ⩽ L ⩽ 4), we check the agreement between available active and passive RPI data. The comparison shows that the measurements are well correlated, with a median residual of ∼52 cm-3. The RMS and STD values of the relative residuals are around 22% and 21% respectively. In summary, the results encourage the application of IMAGE RPI data for

  11. An Assessment of Gravity Recovery with CHAMP Data

    Science.gov (United States)

    Lemoine, F. G.; Luthcke, S. B.; Rowlands, D. D.; Cox, C. M.; Chinn, D. S.; Pavlis, D. E.; Thompson, B.; Nerem, R. S.; Ray, R.; Chao, Benjamin F. (Technical Monitor)

    2002-01-01

    The CHAMP mission, launched in July 2000, is the first in the series of mapping missions for the Earth's geopotential scheduled for the first decade of the new millenium. Its unique contributions compared to all the previous generation of satellites whose data have been included in Earth geopotential models are the precision global tracking with GPS data, and the availability of precision accelerometry data to model the nonconservative forces. Over the past year we have implemented extensive modifications to our GEODYN orbit determination processing code and ancillary data preprocessors to process the GPS and accelerometry data from missions such as CHAMP and GRACE. We report on the analysis of up to 60 days of CHAMP data and how these data contribute to Earth geopotential solutions where the base model is a derivative of EGM96. Preliminary results with only 12.5 days of data processed clearly show the ability of the CHAMP data to improve the modeling of the zonals (1=10 to 40), the m-dailies, the primary resonance terms, and the sectoral harmonics. We will detail the results of our calibrations of the CHAMP accelerometry and assess the quality of test solutions that include these CHAMP data.

  12. ULF wave activity during the 2003 Halloween superstorm: multipoint observations from CHAMP, Cluster and Geotail missions

    Directory of Open Access Journals (Sweden)

    G. Balasis

    2012-12-01

    Full Text Available We examine data from a topside ionosphere and two magnetospheric missions (CHAMP, Cluster and Geotail for signatures of ultra low frequency (ULF waves during the exceptional 2003 Halloween geospace magnetic storm, when Dst reached ~−380 nT. We use a suite of wavelet-based algorithms, which are a subset of a tool that is being developed for the analysis of multi-instrument multi-satellite and ground-based observations to identify ULF waves and investigate their properties. Starting from the region of topside ionosphere, we first present three clear and strong signatures of Pc3 ULF wave activity (frequency 15–100 mHz in CHAMP tracks. We then expand these three time intervals for purposes of comparison between CHAMP, Cluster and Geotail Pc3 observations but also to be able to search for Pc4–5 wave signatures (frequency 1–10 mHz into Cluster and Geotail measurements in order to have a more complete picture of the ULF wave occurrence during the storm. Due to the fast motion through field lines in a low Earth orbit (LEO we are able to reliably detect Pc3 (but not Pc4–5 waves from CHAMP. This is the first time, to our knowledge, that ULF wave observations from a topside ionosphere mission are compared to ULF wave observations from magnetospheric missions. Our study provides evidence for the occurrence of a number of prominent ULF wave events in the Pc3 and Pc4–5 bands during the storm and offers a platform to study the wave evolution from high altitudes to LEO. The ULF wave analysis methods presented here can be applied to observations from the upcoming Swarm multi-satellite mission of ESA, which is anticipated to enable joint studies with the Cluster mission.

  13. CHAMP Tracking and Accelerometer Data Analysis Results

    Science.gov (United States)

    Lemoine, Frank G.; Luthcke, S. B.; Rowlands, D. D.; Pavlis, D. E.; Colombo, O. L.; Ray, Richard D.; Thompson, B.; Nerem, R. S.; Williams, Teresa A.; Smith, David E. (Technical Monitor)

    2002-01-01

    The CHAMP (Challenging Minisatellite Payload) mission's unique combination of sensors and orbit configuration will enable unprecedented improvements in modeling and understanding the Earth's static gravity field and its temporal variations. CHAMP is the first of two missions (GRACE (Gravity Recovery and Climate Experiment) to be launched in the later part of '01) that combine a new generation of GPS (Global Positioning System) receivers, a high precision three axis accelerometer, and star cameras for the precision attitude determination. In order to isolate the gravity signal for science investigations, it is necessary to perform a detailed reduction and analysis of the GPS and SLR tracking data in conjunction with the accelerometer and attitude data. Precision orbit determination based on the GPS and SLR (Satellite Laser Ranging) tracking data will isolate the orbit perturbations, while the accelerometer data will be used to distinguish the surface forces from those due to the geopotential (static, and time varying). In preparation for the CHAMP and GRACE missions, extensive modifications have been made to NASA/GSFC's GEODYN orbit determination software to enable the simultaneous reduction of spacecraft tracking (e.g. GPS and SLR), three axis accelerometer and precise attitude data. Several weeks of CHAMP tracking and accelerometer data have been analyzed and the results will be presented. Precision orbit determination analysis based on tracking data alone in addition to results based on the simultaneous reduction of tracking and accelerometer data will be discussed. Results from a calibration of the accelerometer will be presented along with the results from various orbit determination strategies. Gravity field modeling status and plans will be discussed.

  14. Analysis on motion of Earth’s center of mass observed with CHAMP mission

    Institute of Scientific and Technical Information of China (English)

    HWANG; CheinWay

    2008-01-01

    Geocenter motion (GCM) is one important topic for constructing and maintaining the terrestrial reference frame and its applications. GCM is studied from CHAMP with the multi-step approach in this paper. Geometric orbits of CHAMP in 2001-2006 are precisely determined with the kinematic method only from the satel-lite-borne GPS zero-difference data. Then a GCM time series is estimated from the precise kinematic orbits based on the theory of satellite dynamics to fit the CHAMP’s real geometric orbits. We compare the series with the geocenter series used in ITRF2005. Then the GCM series are analyzed with Fourier transform and wavelet transformation. The mean motions within 6 years in TX, TY and TZ direc-tions are respectively 0.8 mm, 2.2 mm, and 7.9 mm. The trends of GCM in the three directions are 0.495 mm/a, -0.004 mm/a, and 1.309 mm/a, respectively. The long-term movement (2001-2006) indicates that the crustal figure is changing. The seasonal variations are the main component which may be excitated by the mass redistribution of Earth’s fluid layer, e.g. ocean, atmosphere and continental water. The inter-annual variations are also found in the GCM series measured with CHAMP.

  15. Global characteristics of the lunar tidal modulation of the equatorial electrojet derived from CHAMP observations

    OpenAIRE

    Lühr, H.; T. A. Siddiqui; Maus, S.

    2012-01-01

    It has been known since many decades that lunar tide has an influence on the strength of the equatorial electrojet (EEJ). There has, however, never been a comprehensive study of the tidal effect on a global scale. Based on the continuous magnetic field measurements by the CHAMP satellite over 10 years it is possible to investigate the various aspects of lunar effects on the EEJ. The EEJ intensity is enhanced around times when the moon is overhead or at the antipode. This effect is particularl...

  16. Interpretation of CHAMP Magnetic Anomaly Data over the Pannonian Basin Region Using Lower Altitude Horizontal Gradient Data

    Science.gov (United States)

    Taylor, P. T.; Kis, K. I.; Wittmann, G.

    2013-01-01

    The ESA SWARM mission will have three earth orbiting magnetometer bearing satellites one in a high orbit and two side-by-side in lower orbits. These latter satellites will record a horizontal magnetic gradient. In order to determine how we can use these gradient measurements for interpretation of large geologic units we used ten years of CHAMP data to compute a horizontal gradient map over a section of southeastern Europe with our goal to interpret these data over the Pannonian Basin of Hungary.

  17. Synthese de champs sonores adaptative

    Science.gov (United States)

    Gauthier, Philippe-Aubert

    La reproduction de champs acoustiques est une approche physique au probleme technologique de la spatialisation sonore. Cette these concerne l'aspect physique de la reproduction de champs acoustiques. L'objectif principal est l'amelioration de la reproduction de champs acoustiques par "synthese de champs acoustiques" ("Wave Field Synthesis", WFS), une approche connue, basee sur des hypotheses de champ libre, a l'aide du controle actif par l'ajout de capteurs de l'erreur de reproduction et d'une boucle fermee. Un premier chapitre technique (chapitre 4) expose les resultats d'appreciation objective de la WFS par simulations et mesures experimentales. L'effet indesirable de la salle de reproduction sur les qualites objectives de la WFS fut illustre. Une premiere question de recherche fut ensuite abordee (chapitre 5), a savoir s'il est possible de reproduire des champs progressifs en salle dans un paradigme physique de controle actif: cette possibilite fut prouvee. L'approche technique privilegiee, "synthese de champs adaptative" ("Adaptive Wave Field Synthesis" [AWFS]), fut definie, puis simulee (chapitre 6). Cette approche d'AWFS comporte une originalite en controle actif et en reproduction de champs acoustiques: la fonction cout quadratique representant la minimisation des erreurs de reproduction inclut une regularisation de Tikhonov avec solution a priori qui vient de la WFS. L'etude de l'AWFS a l'aide de la decomposition en valeurs singulieres (chapitre 7) a permis de comprendre les mecanismes propres a l'AWFS. C'est la deuxieme principale originalite de la these. L'algorithme FXLMS (LMS et reference filtree) est modifie pour l'AWFS (chapitre 8). Le decouplage du systeme par decomposition en valeurs singulieres est illustre dans le domaine du traitement de signal et l'AWFS basee sur le controle independant des modes de rayonnement est simulee (chapitre 8). Ce qui constitue la troisieme originalite principale de cette these. Ces simulations du traitement de signal

  18. Measurement of Satellite Bunches at the LHC

    CERN Document Server

    Jeff, A; Boccardi, A; Bozyigit, S; Bravin, E; Lefevre, T; Rabiller, A; Roncarolo, F; Welsch, C P; Fisher, A S

    2012-01-01

    The RF gymnastics involved in the delivery of proton and lead ion bunches to the LHC can result in satellite bunches of varying intensity occupying the nominally empty RF buckets. Quantification of these satellites is crucial for bunch-by-bunch luminosity normalization as well as for machine protection. We present an overview of the longitudinal density monitor (LDM) which is the principal instrument for the measurement of satellite bunches in the LHC. The LDM uses single photon counting of synchrotron light. The very high energies reached in the LHC, combined with a dedicated undulator for diagnostics, allow synchrotron light measurements to be made with both protons and heavy ions. The arrival times of photons are collected over a few million turns, with the resulting histogram corrected for the effects of the detector’s deadtime and afterpulsing in order to reconstruct the longitudinal profile of the entire LHC ring. The LDM has achieved a dynamic range in excess of 105 and a time resolution of 90 ps. Ex...

  19. Radiation measurements on the ''Kosmos-900'' satellite

    International Nuclear Information System (INIS)

    Considered is the design and principle of operation of differential electron spectrometers positioned on the ''Kosmos-900'' satellite. Spectrometers are intended for detection of electron of the energy from 30 to 1600 keV with the help of semiconductor diffusion-drift silicon detectors placed in bending magnet systems with angular deviation of 180 deg. Presented are preliminary results of measuring electron fluxes on the ''Kosmos'-900'' satellite orbit. Spectrometer channel calibration has been made with the help of electron and γ sources. The results of determination of spectrometer efficiency are presented. Presented also are the differential energy spectra of electrons obtained in radiation Earth belt in magnetically calm period of 7.06 1977, 03sup(n)59sup(m)-04sup(n)0Ssup(m)

  20. Recent Results from CHAMP Tracking and Accelerometer Data Analysis

    Science.gov (United States)

    Luthcke, S. B.; Rowlands, D. D.; Lemoine, F. G.; Nerem, R. S.; Thompson, B.; Pavlis, E.; Williams, T. A.; Colombo, O. L.; Chao, Benjamin F. (Technical Monitor)

    2002-01-01

    The CHAMP mission's unique combination of sensors and orbit configuration will enable unprecedented improvements in modeling and understanding the Earth's static gravity field and its temporal variations. CHAMP is the first of two missions (GRACE to be launched in the early part of 02') that combine a new generation of Global Positioning System (GPS) receivers, a high precision three-axis accelerometer, and star cameras for the precision attitude determination. In order to isolate the gravity signal for science investigations, it is necessary to perform a detailed reduction and analysis of the GPS and Satellite Laser Ranging (SLR) tracking data in conjunction with the accelerometer and attitude data. Precision orbit determination based on the GPS and SLR tracking data will isolate the orbit perturbations, while the accelerometer data will be used to distinguish the non-gravitational forces from those due to the geopotential (static, and time varying). In preparation for the CHAMP and GRACE missions, extensive modifications have been made to NASA/GSFC's GEODYN orbit determination software to enable the simultaneous reduction of spacecraft tracking (e.g. GPS and SLR), three-axis accelerometer and precise attitude data. Several weeks of CHAMP tracking and accelerometer data have been analyzed and the results will be presented. Precision orbit determination analysis based on tracking data alone in addition to results based on the simultaneous reduction of tracking and accelerometer data will be discussed. Results from a calibration of the accelerometer will be presented along with the results from various orbit determination strategies.

  1. CHAOS-2-a geomagnetic field model derived from one decade of continuous satellite data

    DEFF Research Database (Denmark)

    Olsen, Nils; Mandea, M.; Sabaka, T.J.;

    2009-01-01

    We have derived a model of the near-Earth's magnetic field using more than 10 yr of high-precision geomagnetic measurements from the three satellites Orsted, CHAMP and SAC-C. This model is an update of the two previous models, CHAOS (Olsen et al. 2006) and xCHAOS (Olsen & Mandea 2008). Data...

  2. Advanced Stellar Compass, CHAMP, Interface Control Document

    DEFF Research Database (Denmark)

    Madsen, Peter Buch; Jørgensen, John Leif; Betto, Maurizio;

    1999-01-01

    The German government research establishment "GeoForschungsZentrum" developed under a contract to the German government a microsatellite named "Champ". The Space Instrumentation Group has made a Interface Control Document for the CHAMP, witch describes the Star Imager, the electrical interface, t...... mechanical interface and the TC/TM protocols for the communication between the Star Tracker and the OBDH.......The German government research establishment "GeoForschungsZentrum" developed under a contract to the German government a microsatellite named "Champ". The Space Instrumentation Group has made a Interface Control Document for the CHAMP, witch describes the Star Imager, the electrical interface, the...

  3. Determination Gradients of the Earth's Magnetic Field from the Measurements of the Satellites and Inversion of the Kursk Magnetic Anomaly

    Science.gov (United States)

    Karoly, Kis; Taylor, Patrick T.; Geza, Wittmann

    2014-01-01

    We computed magnetic field gradients at satellite altitude, over Europe with emphasis on the Kursk Magnetic Anomaly (KMA). They were calculated using the CHAMP satellite total magnetic anomalies. Our computations were done to determine how the magnetic anomaly data from the new ESA/Swarm satellites could be utilized to determine the structure of the magnetization of the Earths crust, especially in the region of the KMA. Since the ten years of 2 CHAMP data could be used to simulate the Swarm data. An initial East magnetic anomaly gradient map of Europe was computed and subsequently the North, East and Vertical magnetic gradients for the KMA region were calculated. The vertical gradient of the KMA was determined using Hilbert transforms. Inversion of the total KMA was derived using Simplex and Simulated Annealing algorithms. Our resulting inversion depth model is a horizontal quadrangle with upper 300-329 km and lower 331-339 km boundaries.

  4. Radiation measurements on the ''Kosmos-900'' satellite

    International Nuclear Information System (INIS)

    Presented are the experiment description and preliminary results of measuring the differential proton spectra in the energy range from 30 keV up to 30 MeV in the Earth radiation belts performed on the ''Kosmos-900'' satellite. According to the data obtained in the morning sector of magnetosphere a comparative analysis of differential proton spectra is carried out in the magnetically calm period of large duration and during magnetic agitation. In the range of Mc Ilvine parameter L approximately 3-5 differential proton spectra have maximum at the energy Ep approximately 100-300 keV. Maximum values Esub(max)(L) are higher in magnetically calm period than during magnetic agitation. This difference increases at L decrease, reaches the largest value on L=4 and decreases at further decrease of α. In the depth of plasmosphere (L approximately 3). Esub(max)(L) positions coincide in magnetically calm period and during magnetic agitation. A relation between Esub(max)(L) position in differential proton spectra and the average space distribution of cold plasma is traced

  5. Selected Geomagnetic Measurements From Several Satellites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — More than 17 million selected magnetic observations from several orbiting low-altitude satellites are contained in this digital collection. Except for MAGSAT, all...

  6. Features of highly structured equatorial plasma irregularities deduced from CHAMP observations

    DEFF Research Database (Denmark)

    Xiong, C.; Luhr, H.; Ma, S. Y.;

    2012-01-01

    In this study five years of CHAMP (Challenging Mini-satellite Payload) fluxgate magnetometer (FGM) data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs). We filtered the FGM data by using bandpasses with four different cut-off periods to get the EPBs with different...

  7. EMAG2: A 2-arc min resolution Earth Magnetic Anomaly Grid compiled from satellite, airborne, and marine magnetic measurements

    Science.gov (United States)

    Maus, S.; Barckhausen, U.; Berkenbosch, H.; Bournas, N.; Brozena, J.; Childers, V.; Dostaler, F.; Fairhead, J.D.; Finn, C.; von Frese, R.R.B; Gaina, C.; Golynsky, S.; Kucks, R.; Lu, Hai; Milligan, P.; Mogren, S.; Muller, R.D.; Olesen, O.; Pilkington, M.; Saltus, R.; Schreckenberger, B.; Thebault, E.; Tontini, F.C.

    2009-01-01

    A global Earth Magnetic Anomaly Grid (EMAG2) has been compiled from satellite, ship, and airborne magnetic measurements. EMAG2 is a significant update of our previous candidate grid for the World Digital Magnetic Anomaly Map. The resolution has been improved from 3 arc min to 2 arc min, and the altitude has been reduced from 5 km to 4 km above the geoid. Additional grid and track line data have been included, both over land and the oceans. Wherever available, the original shipborne and airborne data were used instead of precompiled oceanic magnetic grids. Interpolation between sparse track lines in the oceans was improved by directional gridding and extrapolation, based on an oceanic crustal age model. The longest wavelengths (>330 km) were replaced with the latest CHAMP satellite magnetic field model MF6. EMAG2 is available at http://geomag.org/models/EMAG2 and for permanent archive at http://earthref.org/ cgi-bin/er.cgi?s=erda.cgi?n=970. ?? 2009 by the American Geophysical Union.

  8. Monitoring auroral electrojets with satellite data

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Moretto, T.

    2013-01-01

    The strong horizontal ionospheric currents in the auroral oval constitute an important space weather parameter. Here we present a method to estimate the latitude location and intensity of these currents from measurements of variations in the magnetic field magnitude made by low Earth polar orbiting...... satellites. The method is simple enough to be implemented for real-time monitoring, especially since it does not require the full vector field measurement. We demonstrate the method on 5 years of Challenging Minisatellite Payload (CHAMP) data and show how the monitoring depends on the local time of the...... and complement existing ground-based indices. The CHAMP magnetometer in 350–450km altitude easily measures an electrojet which on the ground would produce an Auroral Electrojet (AE)-type signal as small as 20 nT. Thus, while the signal decreases roughly proportionally to the square of the distance to...

  9. Global monitoring of tropospheric water vapor with GPS radio occultation aboard CHAMP

    CERN Document Server

    Heise, S; Beyerle, G; Schmidt, T; Reigber, C

    2005-01-01

    The paper deals with application of GPS radio occultation (RO) measurements aboard CHAMP for the retrieval of tropospheric water vapor profiles. The GPS RO technique provides a powerful tool for atmospheric sounding which requires no calibration, is not affected by clouds, aerosols or precipitation, and provides an almost uniform global coverage. We briefly overview data processing and retrieval of vertical refractivity, temperature and water vapor profiles from GPS RO observations. CHAMP RO data are available since 2001 with up to 200 high resolution atmospheric profiles per day. Global validation of CHAMP water vapor profiles with radiosonde data reveals a bias of about 0.2 g/kg and a standard deviation of less than 1 g/kg specific humidity in the lower troposphere. We demonstrate potentials of CHAMP RO retrievals for monitoring the mean tropospheric water vapor distribution on a global scale.

  10. Efficient statistical classification of satellite measurements

    CERN Document Server

    Mills, Peter

    2012-01-01

    Supervised statistical classification is a vital tool for satellite image processing. It is useful not only when a discrete result, such as feature extraction or surface type, is required, but also for continuum retrievals by dividing the quantity of interest into discrete ranges. Because of the high resolution of modern satellite instruments and because of the requirement for real-time processing, any algorithm has to be fast to be useful. Here we describe an algorithm based on kernel estimation called Adaptive Gaussian Filtering that incorporates several innovations to produce superior efficiency as compared to three other popular methods: k-nearest-neighbour (KNN), Learning Vector Quantization (LVQ) and Support Vector Machines (SVM). This efficiency is gained with no compromises: accuracy is maintained, while estimates of the conditional probabilities are returned. These are useful not only to gauge the accuracy of an estimate in the absence of its true value, but also to re-calibrate a retrieved image and...

  11. An orbit determination from debris impacts on measurement satellites

    Science.gov (United States)

    Fujita, Koki; Tasaki, Mitsuhiko; Furumoto, Masahiro; Hanada, Toshiya

    2016-01-01

    This work proposes a method to determine orbital plane of a micron-sized space debris cloud utilizing their impacts on measurement satellites. Given that debris impacts occur on a line of intersection between debris and satellites orbital planes, a couple of debris orbital parameters, right ascension of the ascending node, inclination, and nodal regression rate can be determined by impact times and locations measured from more than two satellites in different earth orbits. This paper proves that unique solution for the debris orbital parameters is obtained from the measurement data, and derives a computational scheme to estimate them. The effectiveness of the proposed scheme is finally demonstrated by a simulation test, in which measurement data are obtained from a numerical simulation considering realistic debris' and satellites' orbits.

  12. Coordinated rocket and satellite measurements of an auroral event. I - Satellite observations and analysis

    Science.gov (United States)

    Rees, M. H.; Stewart, A. I.; Sharp, W. E.; Hays, P. B.; Hoffman, R. A.; Brace, L. H.; Doering, J. P.; Peterson, W. K.

    1977-01-01

    Results of a coordinated auroral experiment involving the Atmosphere Explorer C satellite and a sounding rocket are reported. Auroral primary electron fluxes and neutral gas densities measured by instruments on the satellite are used in a model calculation of the thermospheric manifestation of the aurora. There is encouraging agreement between the calculated and measured electron density, electron temperature, secondary electron flux, and O I emissions at 5577 and 6300 A. A discrepancy between the calculated and the rocket-measured 3914-A emission profile is discussed in terms of experiment geometry and auroral physics. The coordinated measurements are used to infer vertical fluxes of ionization and of electron thermal energy at high altitudes

  13. Comprehensive study of ULF upstream waves observed in the topside ionosphere by CHAMP and on the ground

    Directory of Open Access Journals (Sweden)

    B. Heilig

    2007-03-01

    Full Text Available Based on magnetic field measurements from the satellite CHAMP, a detailed picture could be obtained of the upstream wave (UW distribution in the topside ionosphere. The low, near-polar orbit of CHAMP, covering all local times, allows the global distribution of this type of pulsation to be revealed. The observations from space are compared to recordings of the ground-based MM100 meridional array covering the latitude range 66° to 42° in magnetic coordinates. UWs show up very clearly in the compressional component of the satellite magnetic field data, whereas on the ground, their signature is found in the H component, but it is mixed with oscillations from field line resonant pulsations. Here we first introduce a procedure for an automated detection of UW signatures, both in ground and space data. Then a statistical analysis is presented of UW pulsations recorded during a 132-day period, centred on the autumn 2001 equinox. Observations in the top-side ionosphere reveal a clear latitudinal distribution of the amplitudes. Largest signals are observed at the equator. Minima show up at about 40° latitude. The coherence between ground and satellite wave signatures is high over wide latitude and longitude ranges. We make suggestions about the entry mechanism of UWs from the foreshock region into the magnetosphere. The clear UW signature in satellite recordings between −60° and 60° latitude allows for detailed investigations of the dependence on solar wind conditions. We test the control of solar wind speed, interplanetary magnetic field strength and cone angle on UWs. For the first time, it is possible to derive details of the Doppler-shift effect by modifying the UW frequency from direct observations. The results reconcile foreshock wave generation predictions with near-Earth observations.

  14. A new satellite to satellite tracking algorithm from Doppler-shifted frequency measurements

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new satellite to satellite tracking (SST) algorithm from Doppler-shifted frequency measurements is proposed. The estimation principle is demonstrated and the mathematic model of SST is established. The state estimation methods for a user (the cooperative case) and target satellites (the non-cooperative case) are presented based on particle swarm optimization (PSO). The Cramer-Rao lower bounds (CRLB) are deduced as well. Performance of the new algorithm is validated through computer simulations, which proved that the proposed method is effective in terms of the estimation quality compared with CRLB and superior in accuracy to the Bearings-Only (BO) method in almost all simulation cases except for the case that an enough long tracking arc-length is obtained for a user satellite.

  15. Satellite measurements of high latitude convection electric fields.

    Science.gov (United States)

    Cauffman, D. P.; Gurnett, D. A.

    1972-01-01

    This paper reviews the first results of satellite experiments to measure magnetospheric convection electric fields using the double-probe technique. The earliest successful measurements were made with the low-altitude (680-2530 km) polar orbiting Injun-5 spacecraft. The Injun-5 results are compared with the initial findings of the electric field experiment on the polar orbiting OGO-6 satellite. Electric field measurements from the OGO-6 satellite have substantiated many of the initial Injun-5 observations with improved accuracy and sensitivity. The OGO-6 detector revealed the persistent occurrence of anti-sunward convection across the polar cap region at velocities not generally detectable with the Injun-5 experiment. The OGO-6 observations also provided information indicating that the location of the electric field reversal shifts equatorward during periods of increased magnetic activity. The implications of the electric field measurements for magnetospheric and auroral structure are summarized, and a list of specific recommendations for improving future experiments is presented.

  16. Satellite data sets for the atmospheric radiation measurement (ARM) program

    Energy Technology Data Exchange (ETDEWEB)

    Shi, L.; Bernstein, R.L. [SeaSpace Corp., San Diego, CA (United States)

    1996-04-01

    This abstract describes the type of data obtained from satellite measurements in the Atmospheric Radiation Measurement (ARM) program. The data sets have been widely used by the ARM team to derive cloud-top altitude, cloud cover, snow and ice cover, surface temperature, water vapor, and wind, vertical profiles of temperature, and continuoous observations of weather needed to track and predict severe weather.

  17. Analysis of one month of CHAMP state vector and accelerometer data for the recovery of the gravity potential

    Directory of Open Access Journals (Sweden)

    E. Howe

    2003-01-01

    Full Text Available The energy conservation method is based on knowledge of the state vector and measurements of nonconservative forces. This is or will be provided by CHAMP, GRACE and GOCE. Here the analysis of one month of CHAMP state vector and accelerometer data is described. The energy conservation method is used to estimate the gravity potential at satellite altitude. When doing so we consider the tidal potential from the sun and the moon, the explicit time variation of the gravity potential in inertial space and loss of energy due to external forces. Fast Spherical Collocation have been used to estimate a gravity field model to degree and order 90, UCPH2002 04. This gravity field model is compared to EGM96 and EIGEN-2. The largest differences with respect to EGM96 are found at those places where the gravity data used to determine EGM96 had the largest uncertainty. EIGEN-2 and UCPH2002 04 are similar, though there are some differences in Antarctica and Central Asia.

  18. Suspected seismo-ionospheric coupling observed by satellite measurements and GPS TEC related to the M7.9 Wenchuan earthquake of 12 May 2008

    OpenAIRE

    Ryu, K.; Parrot, Michel; Kim, S G; Jeon, K.S.; Pulinets, S; Oyama, K.-I.

    2014-01-01

    Anomalous changes in the ionospheric conditions related to the Wenchuan earthquake of 12 May 2008 are investigated using electron density (Ne) from Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and CHAMP satellites, electric field from DEMETER, and GPS-total electron content (TEC) maps. The normalized Ne from the DEMETER satellite reveal that the previously reported TEC increments before the earthquake can be considered as fragments of the gradual equat...

  19. The Preliminary Studies about the Mass Density, by Contrast the Data between NRLMSIS00's and CHAMP Satellite's at 400 km Altitude at the Time of Geomagnetic Super Storms%特大磁暴时CHAMP卫星质量密度和NRLMSIS00模式在400km高度上的对比及初步研究

    Institute of Scientific and Technical Information of China (English)

    丁哲; 王世金

    2012-01-01

    By contrast the data of mass density between NRLMSISOOs and CHAMP satellited at 400 km altitude at the time of geomagnetic super storms, the characters of the atmospheric mass density of the thermosphere is pre-send. The results show that the NRLMSISOO underestimates the impact of geomagnetic disturbance on the change of atmospheric density. In other words, the NRLMSISOO can not accurately reflect atmospheric density of the thermosphere at the time of geomagnetic super storms.%通过对比特大磁暴时CHAMP卫星探测的质量密度和NRLMSIS00模式,在400 km高度上的数据,阐述了特大磁暴时大气密度扰动的一些规律.结果表明:NRLMSIS00模式在特大磁暴时低估了地磁扰动对大气密度变化的影响,不能很好地反映出实际热层大气密度变化.

  20. Determination of atmospheric aerosol properties over land using satellite measurements

    NARCIS (Netherlands)

    Kokhanovsky, A.A.; Leeuw, G. de

    2009-01-01

    Mostly, aerosol properties are poorly understood because the aerosol properties are very sparse. The first workshop on the determination of atmospheric aerosol properties over land using satellite measurements is convened in Bremen, Germany. In this workshop, the topics of discussions included a var

  1. Substorm-related thermospheric density and wind disturbances derived from CHAMP observations

    Directory of Open Access Journals (Sweden)

    P. Ritter

    2010-06-01

    Full Text Available The input of energy and momentum from the magnetosphere is most efficiently coupled into the high latitude ionosphere-thermosphere. The phenomenon we are focusing on here is the magnetospheric substorm. This paper presents substorm related observations of the thermosphere derived from the CHAMP satellite. With its sensitive accelerometer the satellite can measure the air density and zonal winds. Based on a large number of substorm events the average high and low latitude thermospheric response to substorm onsets was deduced. During magnetic substorms the thermospheric density is enhanced first at high latitudes. Then the disturbance travels at an average speed of 650 m/s to lower latitudes, and 3–4 h later the bulge reaches the equator on the night side. Under the influence of the Coriolis force the travelling atmospheric disturbance (TAD is deflected westward. In accordance with present-day atmospheric models the disturbance zonal wind velocities during substorms are close to zero near the equator before midnight and attain moderate westward velocities after midnight. In general, the wind system is only weakly perturbed (Δvy<20 m/s by substorms.

  2. Magnetic crustal thickness in Greenland from CHAMP and Ørsted data

    DEFF Research Database (Denmark)

    Maule, Cathrine Fox; Purucker, Michael E.; Olsen, Nils

    2005-01-01

    The magnetic crustal thickness of Greenland and the surrounding area is determined by inversion of gridded values of the magnetic radial component as given by the IDEMM model, which is based on CHAMP and Ørsted data alone, and by the Comprehensive Model (CM4), which is based on satellite and obse...... using the equivalent source magnetic dipole method.......The magnetic crustal thickness of Greenland and the surrounding area is determined by inversion of gridded values of the magnetic radial component as given by the IDEMM model, which is based on CHAMP and Ørsted data alone, and by the Comprehensive Model (CM4), which is based on satellite and...... observatory data. After correcting for the remanent magnetization, we determine the vertically integrated magnetization of the crust. Making some simplifying assumptions about the susceptibility, the thickness of the magnetic crust is determined by iteratively improving an initial crustal thickness model...

  3. Interpretation of CHAMP magnetic anomaly data over the Pannonian Basin region using lower altitude and gradient data

    International Nuclear Information System (INIS)

    Complete text of publication follows. In 2005 (Taylor et al., 2005-Earth Observation with CHAMP Results from Three Years in Orbit) computed and interpreted a CHAMP satellite magnetic anomaly map, at 400 km altitude, over the Pannonian Basin and surrounding region using the method of Alsdorf et al. (1994). This area was chosen since it has one of the thinnest continental crusts in Europe and is the region of complex tectonic structures. The future SWARM satellite constellation of three spacecraft, with one at a high altitude and the other two lower, will initially be at the same altitude as CHAMP but eventually they will descent to a lower altitude. We recomputed our most recent satellite magnetic anomaly map, using the spherical-cap method of Haines (1985), the technique of Alsdorf et al. (1994) and from spherical harmonic coefficients of MF6 (Maus et al., 2008) employing the latest and lowest altitude CHAMP data, in order to evaluate and reinterpret these newer data to determine the advantage of lower altitude satellite data. The SWARM constellation will have the two lowest altitude satellites flying abreast, with a separation of between ca. 150 to 200 km. to record the horizontal magnetic gradient. Since the CHAMP satellite has been in orbit for eight years and has obtained an extensive range of data, both vertically and horizontally there is a large enough data base to compute the magnetic gradients over the Pannonian Basin region using the many orbits. We computed the magnetic anomaly gradients in order to determine how these component data will improve our interpretation and to preview what the SWARM mission will reveal with reference to the horizontal gradient anomalies.

  4. Inferring surface solar absorption from broadband satellite measurements

    Science.gov (United States)

    Cess, Robert D.; Vulis, Inna L.

    1989-01-01

    An atmospheric solar radiation model and surface albedo models that include wavelength dependence and surface anisotropy are combined to study the possibility of inferring the surface solar absorption from satellite measurements. The model includes ocean, desert, pasture land, savannah, and bog surface categories. Problems associated with converting narrowband measurements to broadband quantities are discussed, suggesting that it would be easier to infer surface solar absorption from broadband measurements directly. The practice of adopting a linear relationship between planetary and surface albedo to estimate surface albedos from satellite measurements is examined, showing that the linear conversion between broadband planetary and surface albedos is strongly dependent on vegetation type. It is suggested that there is a linear slope-offset relationship between surface and surface-atmosphere solar absorption.

  5. ULF wave activity during the 2003 Halloween superstorm: multipoint observations from CHAMP, Cluster and Geotail missions

    OpenAIRE

    Balasis, G.; I. A. Daglis; Zesta, E.; Papadimitriou, C.; Georgiou, M.; Haagmans, R.; Tsinganos, K.

    2012-01-01

    We examine data from a topside ionosphere and two magnetospheric missions (CHAMP, Cluster and Geotail) for signatures of ultra low frequency (ULF) waves during the exceptional 2003 Halloween geospace magnetic storm, when Dst reached ~−380 nT. We use a suite of wavelet-based algorithms, which are a subset of a tool that is being developed for the analysis of multi-instrument multi-satellite and ground-based observations to identify ULF waves and investigate their proper...

  6. ULF wave activity during the 2003 Halloween superstorm: multipoint observations from CHAMP, Cluster and Geotail missions

    OpenAIRE

    Balasis, G.; I. A. Daglis; Zesta, E.; Papadimitriou, C.; Georgiou, M.; Haagmans, R.; Tsinganos, K.

    2012-01-01

    We examine data from a topside ionosphere and two magnetospheric missions (CHAMP, Cluster and Geotail) for signatures of ultra low frequency (ULF) waves during the exceptional 2003 Halloween geospace magnetic storm, when Dst reached ~−380 nT. We use a suite of wavelet-based algorithms, which are a subset of a tool that is being developed for the analysis of multi-instrument multi-satellite and ground-based observations to identify ULF waves and investigate their properties. Starting...

  7. Long term analysis of ionospheric polar patches based on CHAMP TEC data

    OpenAIRE

    M. Noja; Claudia Stolle; Jaeheung Park; Hermann Lühr

    2013-01-01

    Total electron content (TEC) from LEO satellites offers great possibility to sound the upper ionosphere and plasmasphere. This paper describes a method to derive absolute TEC observations aboard CHAMP considering multipath effects and receiver differential code bias. The long‒term data set of 9 years GPS observations is used to investigate the climatological behavior of high‒latitude plasma patches in both hemispheres. The occurrence of polar patches has a clear correlation with the solar cyc...

  8. Monitoring Surface Climate With its Emissivity Derived From Satellite Measurements

    Science.gov (United States)

    Zhou, Daniel K.; Larar, Allen M.; Liu, Xu

    2012-01-01

    Satellite thermal infrared (IR) spectral emissivity data have been shown to be significant for atmospheric research and monitoring the Earth fs environment. Long-term and large-scale observations needed for global monitoring and research can be supplied by satellite-based remote sensing. Presented here is the global surface IR emissivity data retrieved from the last 5 years of Infrared Atmospheric Sounding Interferometer (IASI) measurements observed from the MetOp-A satellite. Monthly mean surface properties (i.e., skin temperature T(sub s) and emissivity spectra epsilon(sub v) with a spatial resolution of 0.5x0.5-degrees latitude-longitude are produced to monitor seasonal and inter-annual variations. We demonstrate that surface epsilon(sub v) and T(sub s) retrieved with IASI measurements can be used to assist in monitoring surface weather and surface climate change. Surface epsilon(sub v) together with T(sub s) from current and future operational satellites can be utilized as a means of long-term and large-scale monitoring of Earth 's surface weather environment and associated changes.

  9. Optimal estimation for the satellite attitude using star tracker measurements

    Science.gov (United States)

    Lo, J. T.-H.

    1986-01-01

    An optimal estimation scheme is presented, which determines the satellite attitude using the gyro readings and the star tracker measurements of a commonly used satellite attitude measuring unit. The scheme is mainly based on the exponential Fourier densities that have the desirable closure property under conditioning. By updating a finite and fixed number of parameters, the conditional probability density, which is an exponential Fourier density, is recursively determined. Simulation results indicate that the scheme is more accurate and robust than extended Kalman filtering. It is believed that this approach is applicable to many other attitude measuring units. As no linearization and approximation are necessary in the approach, it is ideal for systems involving high levels of randomness and/or low levels of observability and systems for which accuracy is of overriding importance.

  10. Cloud and Thermodynamic Parameters Retrieved from Satellite Ultraspectral Infrared Measurements

    Science.gov (United States)

    Zhou, Daniel K.; Smith, William L.; Larar, Allen M.; Liu, Xu; Taylor, Jonathan P.; Schluessel, Peter; Strow, L. Larrabee; Mango, Stephen A.

    2008-01-01

    Atmospheric-thermodynamic parameters and surface properties are basic meteorological parameters for weather forecasting. A physical geophysical parameter retrieval scheme dealing with cloudy and cloud-free radiance observed with satellite ultraspectral infrared sounders has been developed and applied to the Infrared Atmospheric Sounding Interferometer (IASI) and the Atmospheric InfraRed Sounder (AIRS). The retrieved parameters presented herein are from radiance data gathered during the Joint Airborne IASI Validation Experiment (JAIVEx). JAIVEx provided intensive aircraft observations obtained from airborne Fourier Transform Spectrometer (FTS) systems, in-situ measurements, and dedicated dropsonde and radiosonde measurements for the validation of the IASI products. Here, IASI atmospheric profile retrievals are compared with those obtained from dedicated dropsondes, radiosondes, and the airborne FTS system. The IASI examples presented here demonstrate the ability to retrieve fine-scale horizontal features with high vertical resolution from satellite ultraspectral sounder radiance spectra.

  11. Thermal plasma measurement unit for micro-satellites

    Science.gov (United States)

    Hruska, F.; Smilauer, J.; Kolmasova, I.; Truhlik, V.; Chum, J.

    2003-04-01

    The Thermal Plasma Measurement Unit (TPMU) is proposed for the PROBA II mission and for the future scientific satellite projects. The main purpose of the TPMU is to extend series of similar measurements carried out during last two decades onboard MAGION satellites. The other aim is to develop a new more reliable and accurate but still low cost instrument for the proved measurement method. The instrument comprises of a Sensor Block (TPMU-S) and a Processing Block (TPMU-P). The filed of view of the sensors, configured either in a linear array or in a triangle, should be oriented in direction of velocity vector. The sensor Block can be located either on the satellite surface or on the boom and connected by a cable with the Processing Block which is located behind it or inside the satellite body. The ion part consists of a planar ion trap sensor. The ion measurement can work in two modes the continuous ion flux measurement simultaneously with plasma potential and the measurement of retarding volt-ampere characteristics. The analysing voltage is in the range from 0 to 8/12/16/20V in 256 steps. The telemetry volume determines the time resolution of continuous measurement. The base voltage for analysing grid, on which the analysing sweep is superimposed, is given by the sum of floating potential and auxiliary voltage, calculated from measured electron temperature. All voltages can be disabled or set by command. The electron temperature measurement is based on radio frequency probe method, using the RF (~50 kHz), modulated by square wave (~10 Hz). The amplitude of RF is controlled in such a manner that the shift of probe potential is constant. The probe potential is periodically searched for minimum of electron temperature. The electron temperature is measured under an assumption of Maxwellian distribution. Preliminary technical data: Measured parameters - Total ion density (2e7 - 8e12 m-3) - Ion temperature (800 - 10000K) - Electron temperature (800 - 20000K) - Floating

  12. On-line measurement of magnetic fields at GANIL; Mesures en ligne du champ magnetique du G.A.N.I.L

    Energy Technology Data Exchange (ETDEWEB)

    Lemarie, A

    2008-03-15

    On-line measurement of the magnetic fields of electromagnets at GANIL (France) was studied and developed. This type of measurement is necessary for it allows the adjustment and the monitoring of the parameters which control the transport of particle beams from the accelerators to the experimental vaults. The developments were based on nuclear magnetic resonance (NMR) magnetometers and Hall-effect magnetometers. The limitations of operating NMR probes in inhomogeneous fields required particular solutions. Techniques of positioning and appropriate compensation for field gradients were put in place. NMR probes and Hall-effect probes are integrated into the electronics for monitoring and control according to the defined standards at GANIL. The unit comprises instrumentation which perfectly meets the needs, particularly from the point of view of the measurement and the monitoring of the magnetic parameters. (author)

  13. Land surface temperature and emissivity retrieval from satellite measurements

    International Nuclear Information System (INIS)

    Land surface temperature (LST) is maintained by the incoming solar and longwave irradiation, the outgoing terrestrial infrared radiation, the sensible and latent heat flux, and the ground heat flux. Therefore, LST is a good indicator of the energy balance at the Earth's surface. Long-term and reliable estimates of LST are required for multiple purposes, e.g. as input to general circulation models, numerical weather prediction, climate change detection, vegetation health monitoring, change detection related to desertification processes etc. Only satellite-based radiance measurements provide the temporal coverage and spatial resolution required to run these models and analyze the processes. For measurements in the atmospheric windows, the top-of-the-atmosphere (TOA) radiance is dominated by surface-leaving radiance. Therefore, LST can be estimated from radiances measured by satellite sensors. The sensor-specific TOA measurements are influenced by surface properties (LST and emissivity) and atmospheric absorption and transmission. Besides the complications due to atmospheric attenuation, a direct separation of LST and emissivity from passive radiometric measurements alone is not feasible because the problem is underdetermined: for a sensor with N spectral channels, there are N measurements but N + 1 unknowns (i.e. N spectral emissivities and LST). In order to make this ill-posed problem solvable, different assumptions for regularization of the underdetermined condition are made. This work is a contribution to the field of spaceborne remote sensing for measurement of Earth's surface temperature and emissivity from passive radiometry. At the Institute of Meteorology and Climate Research, Forschungszentrum Karlsruhe/University of Karlsruhe, Germany, NOAA AVHRR data are archived at the Meteorological Satellite Applications (MSA) group since several years and MSG SEVIRI data are received from 2004 using a High Rate User Station. The aim of this study was to select an

  14. Intercomparison of desert dust optical depth from satellite measurements

    Directory of Open Access Journals (Sweden)

    E. Carboni

    2012-08-01

    Full Text Available This work provides a comparison of satellite retrievals of Saharan desert dust aerosol optical depth (AOD during a strong dust event through March 2006. In this event, a large dust plume was transported over desert, vegetated, and ocean surfaces. The aim is to identify the differences between current datasets. The satellite instruments considered are AATSR, AIRS, MERIS, MISR, MODIS, OMI, POLDER, and SEVIRI. An interesting aspect is that the different algorithms make use of different instrument characteristics to obtain retrievals over bright surfaces. These include multi-angle approaches (MISR, AATSR, polarisation measurements (POLDER, single-view approaches using solar wavelengths (OMI, MODIS, and the thermal infrared spectral region (SEVIRI, AIRS. Differences between instruments, together with the comparison of different retrieval algorithms applied to measurements from the same instrument, provide a unique insight into the performance and characteristics of the various techniques employed. As well as the intercomparison between different satellite products, the AODs have also been compared to co-located AERONET data. Despite the fact that the agreement between satellite and AERONET AODs is reasonably good for all of the datasets, there are significant differences between them when compared to each other, especially over land. These differences are partially due to differences in the algorithms, such as assumptions about aerosol model and surface properties. However, in this comparison of spatially and temporally averaged data, it is important to note that differences in sampling, related to the actual footprint of each instrument on the heterogeneous aerosol field, cloud identification and the quality control flags of each dataset can be an important issue.

  15. CM5, a pre-Swarm comprehensive geomagnetic field model derived from over 12 yr of CHAMP, Ørsted, SAC-C and observatory data

    DEFF Research Database (Denmark)

    Sabaka, Terence J.; Olsen, Nils; Tyler, Robert H.;

    2015-01-01

    A comprehensive magnetic field model named CM5 has been derived from CHAMP, Orsted and SAC-C satellite and observatory hourly-means data from 2000 August to 2013 January using the Swarm Level-2 Comprehensive Inversion (CI) algorithm. Swarm is a recently launched constellation of three satellites to...... induction. SIVW has allowed for a much improved lithospheric field recovery over CM4 by exploiting CHAMP along-track difference data yielding resolution levels up to spherical harmonic degree 107, and has allowed for the successful extraction of the oceanic M2 tidal magnetic field from quiet, nightside data...

  16. Transportable IOT measurement station for direct-broadcast satellites

    Science.gov (United States)

    Ulbricht, Michael

    A transportable 11.7-12.5-GHz flux-density measurement facility for use in the in-orbit testing (IOT) of the FRG TV-Sat direct-broadcast satellites is described. Major components include a 1.2-m-diameter antenna, the fluxmeter, a radiometer to determine atmospheric attenuation, a weather station, and a control and data-processing computer; all of the components are mounted on a 5.10 x 2.35 x 2.70-m trailer. IOT performance parameters include gain/temperature ratio 15.9 dB/K, measurement range -97 to -117 dBW/sq m, measurement accuracy less than 0.5 dB rms, and measurement rate 250-650 msec. Photographs and a block diagram are provided.

  17. Features of highly structured equatorial plasma irregularities deduced from CHAMP observations

    Directory of Open Access Journals (Sweden)

    C. Xiong

    2012-08-01

    Full Text Available In this study five years of CHAMP (Challenging Mini-satellite Payload fluxgate magnetometer (FGM data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs. We filtered the FGM data by using band-passes with four different cut-off periods to get the EPBs with different maximum spatial scale sizes in the meridional plane ranging from 76–608 km. Associated with the EPB observations at about 400 km, the typical altitude of CHAMP during the year 2000–2005, we also investigate the post-sunset equatorial vertical plasma drift data from ROCSAT-1 (Republic of China Satellite 1. Since the height of the F-layer is highly correlated with the vertical plasma drift and solar flux, we sorted the ROCSAT-1 data into different groups by F10.7. From the integrated vertical drift we have estimated the post-sunset uplift of the ionosphere. By comparing the properties of EPB occurrence for different scale sizes with the global distribution of plasma vertical uplift, we have found that EPBs reaching higher altitudes are more structured than those which are sampled by CHAMP near the top side of the depleted fluxtube. Such a result is in accord with 3-D model simulations (Aveiro and Hysell, 2010. Small-scale EPB structures are observed by CHAMP when the irregularities reach apex heights of 800 km and more. Such events are encountered primarily in the Brazilian sector during the months around November, when the post-sunset vertical plasma drift is high.

  18. EMAG2. A 2-arc-minute resolution Earth magnetic anomaly grid compiled from satellite, airborne and marine magnetic measurements

    International Nuclear Information System (INIS)

    Complete text of publication follows. Airborne and marine magnetic data have been collected for more than half a century, providing extensive coverage of the Earth. Due to the changing main field from the Earth's core, and due to differences in quality and coverage, combining these data to a consistent global magnetic anomaly grid is challenging. A key ingredient is the long wavelength magnetic field observed by the low-orbiting CHAMP satellite. To produce a homogeneous grid, the marine and aeromagnetic trackline data are first line-leveled and then merged with the existing grids of continental-scale compilations by Least Squares Collocation. The method takes the anisotropy of the oceanic magnetic field into account. This leads to an improved representation of oceanic magnetic lineations and allows for the interpolation between adjacent tracks in sparsely surveyed regions, particularly in the southern oceans. In the final processing step the short-to- intermediate wavelengths of the near-surface grid are merged with the latest CHAMP satellite magnetic anomaly model MF6 (http://geomag.org/models/MF6.html). In analogy to NGDC's 2-arc-minute resolution ETOPO2 grid, the new magnetic anomaly grid is named EMAG2. The grid is available in digital form and as plug-ins for NASA World Wind, Google Earth and Google Maps at http://geomag.org.

  19. Flight experience on CHAMP and GRACE with ultra-sensitive accelerometers and return for LISA

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Manuel; Foulon, Bernard; Liorzou, Francoise; Touboul, Pierre [Physics and Instrumentation Department, Office National d' Etudes et de Recherches Aerospatiales, BP 72, 92322 Chatillon Cedex (France)

    2003-05-21

    The challenging drag-free sensor of the Laser Interferometer Space Antenna (LISA) mission is derived from electrostatic accelerometers developed for a long time in ONERA. The LISA sensor includes a gold platinum alloy inertial mass free-floating in space and used as reflectors for the laser interferometer. This test mass should not undergo more than 3x10{sup -15} m s{sup -2} Hz{sup -1/2} acceleration at 0.1 mHz. This tremendous performance is not close to what has been reached so far, but should be approached within one order of magnitude with the projected SMART-2 ESA mission by 2006. Meanwhile, ONERA has participated in several space missions with the flight of increasingly sensitive accelerometers. The German CHAMP mission aims at mapping the Earth's magnetic and gravity fields. More than two years data have been accumulated showing a resolution better than 3 x 10{sup -9} m s{sup -2} Hz{sup -1/2} for the accelerometer. With the JPL/NASA GRACE mission launched in March 2002, even more sensitive measurements have been obtained. From these two flight experiments with electrostatic sensors very similar in concept to that of LISA, the accelerometric environment on board a satellite is discussed at nanogravity levels. It is also shown that these first analyses are compatible with the expected LISA performance when the results are extrapolated to the LISA environment, needing femto-gravity levels.

  20. Field-aligned current distribution and response to interplanetary conditions during a superstorm―CHAMP observation

    Institute of Scientific and Technical Information of China (English)

    WANG Hui; MA ShuYing; Hermann LUEHR; ZHOU YunLiang; DANG Ge

    2007-01-01

    With geomagnetic measurements on board of CHAMP satellite, the characteristics of global large-scale field-aligned currents (FACs) in the topside ionosphere are investigated along with their responses to interplanetary conditions for the superstorm of November, 2003. It is found that (1) The storm-time FAC densities enhanced greatly in comparison with quiet period and the enhancements show hemispheric asymmetry of both summer-winter and sunlit-dark. (2) For the first time, it is revealed that the latitude-integrated FAC density is controlled mainly by solar wind dynamic pressure rather than IMF. (3) FACs expanded equatorward dramatically, with the lowest latitude being 45° Mlat or more; on the dayside this expansion was controlled directly by IMF Bz, showing an interaction time scale of about 25 min in the solar wind-magnetosphere-ionosphere coupling system, and a nonlinear saturation of the equatorward expansion when IMF Bz <-30 nT; while on the nightside, the expansion and recovery lagged about 3 h behind the IMF changes but nearly in phase with changes of SYM-H index. (4) During the storm main phase, the nightside FAC latitude coverage extended to 25° or wider, appearing multi-sheet current structure with more than 10 sheets.

  1. Measurement of Sun Induced Chlorophyll Fluorescence Using Hyperspectral Satellite Imagery

    Science.gov (United States)

    Irteza, S. M.; Nichol, J. E.

    2016-06-01

    Solar Induced Chlorophyll Fluorescence (SIF), can be used as an indicator of stress in vegetation. Several scientific approaches have been made and there is considerable evidence that steady state Chlorophyll fluorescence is an accurate indicator of plant stress hence a reliable tool to monitor vegetation health status. Retrieval of Chlorophyll fluorescence provides an insight into photochemical and carbon sequestration processes within vegetation. Detection of Chlorophyll fluorescence has been well understood in the laboratory and field measurement. Fluorescence retrieval methods were applied in and around the atmospheric absorption bands 02B (Red wavelength) approximately 690 nm and 02A (Far red wavelengths) 740 nm. Hyperion satellite images were acquired for the years 2012 to 2015 in different seasons. Atmospheric corrections were applied using the 6S Model. The Fraunhofer Line Discrimanator (FLD) method was applied for retrieval of SIF from the Hyperion images by measuring the signal around the absorption bands in both vegetated and non vegetated land cover types. Absorption values were extracted in all the selected bands and the fluorescence signal was detected. The relationships between NDVI and Fluorescence derived from the satellite images are investigated to understand vegetation response within the absorption bands.

  2. Global distribution of pauses observed with satellite measurements

    Indian Academy of Sciences (India)

    M Venkat Ratnam; P Kishore; Isabella Velicogna

    2013-04-01

    Several studies have been carried out on the tropopause, stratopause, and mesopause (collectively termed as ‘pauses’) independently; however, all the pauses have not been studied together. We present global distribution of altitudes and temperatures of these pauses observed with long-term space borne high resolution measurements of Global Positioning System (GPS) Radio Occultation (RO) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) aboard Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite. Here we study the commonality and differences observed in the variability of all the pauses. We also examined how good other datasets will represent these features among (and in between) different satellite measurements, re-analysis, and model data. Hemispheric differences observed in all the pauses are also reported. In addition, we show that asymmetries between northern and southern hemispheres continue up to the mesopause. We analyze inter and intra-seasonal variations and long-term trends of these pauses at different latitudes. Finally, a new reference temperature profile is shown from the ground to 110 km for tropical, mid-latitudes, and polar latitudes for both northern and southern hemispheres.

  3. Highlights from 40 Years of Satellite UV Measurements

    Science.gov (United States)

    Bhartia, Pawan K.

    2010-01-01

    This year we are celebrating the 40th anniversary of the launch of the Backscatter Ultraviolet (BUV) instrument on NASA's Nimbus-4 satellite. The purpose of this instrument was to demonstrate the capability to measure total column ozone and its vertical distribution from space. The success of this instrument led to about a dozen instruments of this type on various NASA and NOAA satellites. These instruments used a single photomultiplier tube (PMT) that restricted the measurements to 6-12 discrete wavelengths in the 250-380 nm range. With the availability of solid-state detector arrays in the past decade it has been possible to make similar measurements but with hyperspectral (contiguous in wavelength) sampling and enhanced spectral resolution. This has allowed global mapping of several weakly-absorbing trace gases including S0 2, NO2, BrO, HCHO, and CIIOCHO. Since these measurements are affected by clouds and aerosols, a great deal of effort has gone into understanding their effect on ultraviolet radiation- both upwelling and downwelling. The downwelling UV radiation is chemically and biologically active and has both negative (genetic damage, air pollution) and positive (production of vitamin D and OH radical) environmental effects. I will discuss how the interaction of Rayleigh-scattered UV radiation with clouds and aerosols produce a variety of interesting effects that are leading to new methods of remote sensing of their properties. The UV measurements can greatly enhance the information that one derives from more traditional methods that use infrared and visible part of the solar spectrum.

  4. The possible direct use of satellite radiance measurements by the Atmospheric Radiation Measurement Program

    International Nuclear Information System (INIS)

    The Atmospheric Radiation Measurement (ARM) Program is a major research program initiated by the Department of Energy to improve our understanding of radiative and cloud processes critical to predicting the Earth's climate and its changes. Central to this concept is the use of four to six intensively instrumented sites for long-term study and characterization of the processes of interest. The instrumentation suites will include ground-based, high-accuracy radiometers for measuring the short and longwave surface flux, as well as an extensive set of ground-and air-based instrumentation for characterizing the intervening atmospheric column. Satellite-based measurements are expected to play a very important role in providing top-of-the-atmosphere measurements. In this study, we examine the possibility of comparing ARM outputs directly with satellite measurements, thereby ensuring the independence of these two important data sets. Thus we focused on what do satellites really measure and how well do they measure it. On what can we do about the general lack of adequate visible channel calibration. On what is the best way for ARM to obtain near-real-time access to this unprocessed data. And on what is the optimum way for ARM to make use of satellite data

  5. Construct validity of Comprehensive High-Level Activity Mobility Predictor (CHAMP for male servicemembers with traumatic lower-limb loss

    Directory of Open Access Journals (Sweden)

    Robert S. Gailey, PhD, PT

    2013-10-01

    Full Text Available This study examined the convergent construct validity of a new performance-based assessment instrument called the Comprehensive High-Level Activity Mobility Predictor (CHAMP as a measure of high-level mobility in servicemembers (SMs with traumatic lower-limb loss (LLL. The study was completed by 118 SMs. Convergent construct validity of the CHAMP was established using the 6-minute walk test (6MWT as a measure of overall mobility and physical function and the Amputee Mobility Predictor (AMP as a measure of basic prosthetic mobility. The known group methods construct validity examined disparities in high-level mobility capability among SMs with different levels of LLL. The CHAMP score demonstrated a strong positive relationship between 6MWT distance (r = 0.80, p < 0.001 and AMP score (r = 0.87, p < 0.001, respectively. In addition, the CHAMP can discriminate between different levels of LLL. Study findings support the CHAMP as a valid performance-based assessment instrument of high-level mobility for SMs with traumatic LLL.

  6. MEaSUREs Land Surface Temperature from GOES satellites

    Science.gov (United States)

    Pinker, Rachel T.; Ma, Yingtao; Chen, Wen; Hulley, Glynn; Borbas, Eva; Hain, Chris; Hook, Simon

    2016-04-01

    Information on Land Surface Temperature (LST) can be generated from observations made from satellites in low Earth orbit (LEO) such as MODIS and ASTER and by sensors in geostationary Earth orbit (GEO) such as GOES. Both observations have unique advantages, however, when combined, introduced are challenges related to inhomogeneity of the resulting information. NASA has identified a major need for developing long-term, consistent, and calibrated data and products that are consistent across multiple missions and satellite sensors. Under a project titled: "A Unified and Coherent Land Surface Temperature and Emissivity Earth System Data Record (ESDR) for Earth Science" led by Jet Propulsion Laboratory, such an effort is underway. In this presentation we will describe part of that effort, dealing with the generation of an approach to derive LST information from the GOES satellites from 2000 and onward. Since implementation of the well-established split window approach is not possible after mid-2003 (will be possible again after the launch of GOES-R in October of 2016), there is a need to focus on retrievals from a single thermal channel in order to provide continuity in the LST record. The methodology development requires the generation of consistently calibrated GOES observations, identification of clear sky radiances, and development of retrieval algorithms that benefit from most recent advances in related fields that provide auxiliary information required for driving the inference schemes. Results will be presented from two approaches. One is based on a regression approach that utilizes a wide range of simulations using MODTRAN, SeeBor Version 5.0 global atmospheric profiles and. The second approach uses MERRA-2 reanalysis fields with the RTTOV radiative transfer model approach to derive LST from the LEO satellites, adjusted for the GEO characteristics. The advantage of this latter approach is in the consistency between this retrieval approaches and those used at JPL

  7. 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...

  8. Accuracy of Satellite-Measured Wave Heights in the Australian Region for Wave Power Applications

    Science.gov (United States)

    Meath, Sian E.; Aye, Lu; Haritos, Nicholas

    2008-01-01

    This article focuses on the accuracy of satellite data, which may then be used in wave power applications. The satellite data are compared to data from wave buoys, which are currently considered to be the most accurate of the devices available for measuring wave characteristics. This article presents an analysis of satellite- (Topex/Poseidon) and…

  9. Ocean tidal signals in observatory and satellite magnetic measurements

    DEFF Research Database (Denmark)

    Maus, S.; Kuvshinov, A.

    2004-01-01

    magnetic field generation by tidal ocean flow. We predict the motionally induced magnetic fields for the six major tidal constituents and compare their amplitudes with the spectra of night time observatory and satellite magnetic measurements for the Indian Ocean. The magnetic variations at the solar S2, K1......Ocean flow moves sea water through the Earth's magnetic field, inducing electric fields, currents and secondary magnetic fields. These motionally induced magnetic fields have a potential for the remote sensing of ocean flow variability. A first goal must be to gain a better understanding of......, and P1 periods turn out to be dominated by unrelated external fields. In contrast, observed lunar M2 and N2 tidal signals are in fair agreement with predictions from motional induction. The lunar diurnal O1 signal, visible at some observatories, could be caused by ocean flow but disagrees in amplitude...

  10. The impact of the new Earth gravity models on the measurement of the Lense-Thirring effect with a new satellite

    CERN Document Server

    Iorio, L

    2005-01-01

    In this paper we investigate the opportunities offered by the new Earth gravity models from the dedicated CHAMP and, especially, GRACE missions to the project of measuring the general relativistic Lense-Thirring effect with a new Earth's artificial satellite. It turns out that it would be possible to abandon the stringent, and expensive, requirements on the orbital geometry of the originally prosed LARES mission (same semimajor axis a=12270 km of the existing LAGEOS and inclination i=70 deg) by inserting the new spacecraft in a relatively low, and cheaper, orbit (a=7500-8000 km, i\\sim 70 deg) and suitably combining its node Omega with those of LAGEOS and LAGEOS II in order to cancel out the first even zonal harmonic coefficients of the multipolar expansion of the terrestrial gravitational potential J_2, J_4 along with their temporal variations. The total systematic error due to the mismodelling in the remaining even zonal harmonics would amount to \\sim 1% and would be insensitive to departures of the inclinat...

  11. A global model of mantle conductivity derived from 5 years of CHAMP, Orsted, and SAC-C magnetic data

    DEFF Research Database (Denmark)

    Kuvshinov, A.; Olsen, Nils

    2006-01-01

    We present a global 1-D conductivity model which is obtained by analysis of five years ( 2001 - 2005) of simultaneous magnetic data from the three satellites Orsted, CHAMP and SAC-C. After removal of core and crustal fields as predicted by a recent field model we used non-polar scalar and vector...... model which is rather similar to models derived from ground-based data....

  12. The performance of the FODA/IBEA satellite access scheme measured on the Italsat satellite

    OpenAIRE

    Celandroni, Nedo; Ferro, Erina; Potort?, Francesco

    1995-01-01

    This paper briefly describes the FODA/IBEA satellite access scheme and presents part of the experimental results of two studies carried out both on real-time and noo real-time traffic crossing a satellite networkaccessed with the FODA/IBEA access scheme. The jitter affecting the reaJ time data is studied and a solution indicated. while for non real-time data the performance of the capacity assignment algorithm is shown. Tests were carried on the ITALSAT satellite, by using the Multi-applicati...

  13. Thermospheric mass density measurement from precise orbit ephemeris

    Institute of Scientific and Technical Information of China (English)

    Junyu Chen; Jizhang Sang

    2016-01-01

    Atmospheric drag,which can be inferred from orbit information of low-Earth orbiting (LEO)satellites,provides a direct means of measuring mass density.The temporal resolution of derived mass density could be in the range from minutes to days,depending on the precision of the satellite orbit data.This paper presents two methods potentially being able to estimate thermosphere mass density from precise obit ephemeris with high temporal resolution.One method is based on the drag perturbation equation of the semi-major axis and the temporal resolution of retrieved density could be 150 s for CHAMP satellite.Another method generates corrections to densities computed from a baseline density model through a Kalman filter orbit drag coefficient determination (KFOD) process and the temporal resolution of derived density could be as high as 30 s for CHAMP satellite.The densities estimated from these two methods are compared with densities obtained from accelerometer data of CHAMP satellite.When the accelerometer data based densities are used as reference values,the mean relative accuracy of the densities derived from precision orbit data using the two methods is within approximately 10%.An application of the derived densities shows that the derived densities can reduce orbit predication errors.

  14. Cross-Validation of MIPAS/ENVISAT and GPS-RO/CHAMP Temperatures

    OpenAIRE

    Wang, D. Y.; Jens Wickert

    2004-01-01

    MIPAS/ENVISAT and GPS-RO/CHAMP measure temperature and water vapour profiles in the troposphere and temperature in the stratosphere. This analysis presents comparisons of the stratospheric temperatures retrieved from MIPAS limb mid-infrared emission measurement using the IMK data processor and from GPS radio occultation observations using GFZ retrieval routines. The data used for comparison are taken from the global observations of 14 days in September/October 2002 and 20 days in October/Nove...

  15. Measurements of transionospheric radio propagation parameters using the FORTE satellite

    International Nuclear Information System (INIS)

    We report initial measurements of ionospheric propagation parameters, particularly the total electron content (TEC), using the recently launched FORTE satellite. FORTE, which orbits the Earth at an altitude of 800 km and an inclination of 70 degree, contains a set of wideband radio receivers whose output is digitally recorded. A specialized triggering circuit identifies transient, broadband radio events, which include radiation from lightning, transionospheric pulse pairs, and man-made sources. Event data are transmitted to the ground station for analysis. In this paper we examine signals transmitted from an electromagnetic pulse generator operated at Los Alamos. The transmitter produces nearly impulsive signals in the VHF range. The received signal is dispersed by the ionosphere, and the received signal can be analyzed to deduce the total electron content along the path. By comparing the slant TEC thus measured with results from a ray-tracing code, we can deduce the vertical TEC to 800 km. Data from eight passes are presented. These types of data (in larger quantities) are of interest to operators of radar altimeters, who need data to corroborate their corrections for the ionospheric TEC. The combination of FORTE TEC data to 800 km and TEC measurements to 20,000 km (the Global Positioning System orbital altitude) can provide useful information for assessing the validity of models of plasmaspheric electron density. Initial estimates of the plasmaspheric density, on two daytime passes, are about 6 TECU. The signal received by FORTE, which is linearly polarized at the transmitter, is split into two magnetoionic modes by the ionosphere. The receiving antenna is also linearly polarized and therefore receives both modes. By measuring the beat frequency between the two modes, we can deduce the product of the geomagnetic field and the cosine of the angle between the field and the propagation vector. The possibility of using the measured slant TEC and the beat frequency to

  16. Hydrologic Science and Satellite Measurements of Surface Water (Invited)

    Science.gov (United States)

    Alsdorf, D. E.; Mognard, N. M.; Lettenmaier, D. P.

    2010-12-01

    While significant advances continue to be made for satellite measurements of surface waters, important science and application opportunities remain. Examples include the following: (1) Our current methods of measuring floodwater dynamics are either sparsely distributed or temporally inadequate. As an example, flood depths are measured by using high water marks, which capture only the peak of the flood wave, not its temporal variability. (2) Discharge is well measured at individual points along stream networks using in-situ gauges, but these do not capture within-reach hydraulic variability such as the water surface slope changes on the rising and falling limbs of flood waves. (3) Just a 1.0 mm/day error in ET over the Congo Basin translates to a 35,000 m3/s discharge error. Knowing the discharge of the Congo River and its many tributaries should significantly improve our understanding of the water balance throughout the basin. The Congo is exemplary of many other basins around the globe. (4) Arctic hydrology is punctuated by millions of unmeasured lakes. Globally, there might be as many as 30 million lakes larger than a hectare. Storage changes in these lakes are nearly unknown, but in the Arctic such changes are likely an indication of global warming. (5) Well over 100 rivers cross international boundaries, yet the sharing of water data is poor. Overcoming this helps to better manage the entire river basin while also providing a better assessment of potential water related disasters. The Surface Water and Ocean Topography (SWOT, http://swot.jpl.nasa.gov/) mission is designed to meet these needs by providing global measurements of surface water hydrodynamics. SWOT will allow estimates of discharge in rivers wider than 100m (50m goal) and storage changes in water bodies larger than 250m by 250m (and likely as small as one hectare).

  17. Novelty detection in time series of ULF magnetic and electric components obtained from DEMETER satellite experiments above Samoa (29 September 2009) earthquake region

    OpenAIRE

    M. Akhoondzadeh

    2013-01-01

    Using ULF (ultra low frequency) measurements of magnetometer and ICE (Instrument Champ Electrique) experiments on board the DEMETER satellite, possible irregularities in ULF magnetic and electric components have been surveyed in the vicinity of Samoa (29 September 2009) earthquake region. The data used in this paper cover the period from 1 August 2009 to 11 October 2009. The anomalous variations in magnetic components (Bx, B

  18. Coherent Uncertainty Analysis of Aerosol Measurements from Multiple Satellite Sensors

    Science.gov (United States)

    Petrenko, M.; Ichoku, C.

    2013-01-01

    Aerosol retrievals from multiple spaceborne sensors, including MODIS (on Terra and Aqua), MISR, OMI, POLDER, CALIOP, and SeaWiFS altogether, a total of 11 different aerosol products were comparatively analyzed using data collocated with ground-based aerosol observations from the Aerosol Robotic Network (AERONET) stations within the Multi-sensor Aerosol Products Sampling System (MAPSS, http://giovanni.gsfc.nasa.gov/mapss/ and http://giovanni.gsfc.nasa.gov/aerostat/). The analysis was performed by comparing quality-screened satellite aerosol optical depth or thickness (AOD or AOT) retrievals during 2006-2010 to available collocated AERONET measurements globally, regionally, and seasonally, and deriving a number of statistical measures of accuracy. We used a robust statistical approach to detect and remove possible outliers in the collocated data that can bias the results of the analysis. Overall, the proportion of outliers in each of the quality-screened AOD products was within 12%. Squared correlation coefficient (R2) values of the satellite AOD retrievals relative to AERONET exceeded 0.6, with R2 for most of the products exceeding 0.7 over land and 0.8 over ocean. Root mean square error (RMSE) values for most of the AOD products were within 0.15 over land and 0.09 over ocean. We have been able to generate global maps showing regions where the different products present advantages over the others, as well as the relative performance of each product over different landcover types. It was observed that while MODIS, MISR, and SeaWiFS provide accurate retrievals over most of the landcover types, multi-angle capabilities make MISR the only sensor to retrieve reliable AOD over barren and snow / ice surfaces. Likewise, active sensing enables CALIOP to retrieve aerosol properties over bright-surface shrublands more accurately than the other sensors, while POLDER, which is the only one of the sensors capable of measuring polarized aerosols, outperforms other sensors in

  19. Extending comprehensive models of the Earth's magnetic field with Orsted and CHAMP data

    DEFF Research Database (Denmark)

    Sabaka, T.J.; Olsen, Nils; Purucker, M.E.

    2004-01-01

    A new model of the quiet-time, near-Earth magnetic field has been derived using a comprehensive approach, which includes not only POGO and Magsat satellite data, but also data from the Orsted and CHAMP satellites. The resulting model shows great improvement over its predecessors in terms of...... completeness of sources, time span and noise reduction in parameters. With its well separated fields and extended time domain of 1960 to mid-2002, the model is able to detect the known sequence of geomagnetic jerks within this frame and gives evidence for an event of interest around 1997. Because all sources...... field exhibits significantly less noise than previous models as a result of improved data selection. The F-region currents, through which the satellites pass, are now treated as lying within meridional planes, as opposed to being purely radial. Results are consistent with those found previously for...

  20. Analysis of CHAMP scalar magnetic data to identify ocean circulation signals

    DEFF Research Database (Denmark)

    Manoj, C.; Maus, S.; Kuvshinov, Alexei;

    Unlike tidal ocean signals, the magnetic signal of ocean circulation has not yet been identified in satellite magnetic data. In particular, the steady signal of mean ocean flow is indistinguishable from time invariant crustal signals. One option, therefore, is to predict the seasonal and annual...... variations in the ocean flow signal from ocean circulation models and compare them with the corresponding variations in satellite magnetic residuals. We used the 11 year ECCO-1 simulation data to derive the ocean transport. A 3D EM induction code in its low frequency limit, was used to simulate the magnetic...... signals at satellite altitude. We predict annual variation amplitudes in the scalar anomaly of the order of 0.3 nT. We compare these predictions with the particularly quiet CHAMP night-time scalar data, subtracting core, mantle, crustal, ocean tidal, and magnetospheric contributions to the field. The...

  1. Plasma bubbles from the satellite-born measurements

    International Nuclear Information System (INIS)

    The topside sounder data from Intercosmos-19 satellite and MIR Orbital Space Station were analyzed for specific cases when the satellite found itself inside the plasma bubble. The attempt of ionogram interpretation is made. Some estimations of the bubble parameters are made. (author)

  2. Test results of satellite-borne charged particle measuring instrument

    International Nuclear Information System (INIS)

    A charged particle-measuring instrument to measure on the geostationary orbit the spectra of protons, α-particles and electrons emitted from the sun was manufactured, and its performance was assured by the test on the earth. The Geostationary Meteorological Satellite, on which the instrument will be mounted, will be launched into the geostationary orbit over the pacific ocean in the summer, 1977. The instrument has five systems of detectors to cover the measuring energy range and the kinds of particles, and data are collected every several channels separately. The tests on the earth were carried out by using a cyclotron and setting the energy ranges from 1 to 15 MeV (for protons) and 6 to 30 MeV (for α-particles) through the adjustment of the accelerating conditions and absorbers of the cyclotron. The performance of the instrument was confirmed by comparing the energy and number of the irradiated charged particles measured with the instrument and the reference detector under the same conditions. The results showed that the energy-detecting characteristic was within the error range of a few percent in most cases, and the counts were within the error of 30% against the expected values. The ditinguishing characteristic of the level discriminator was also nearly equal to the estimated result, through it degrades in the vicinity of the border of channels. However, the correction of data may be required when the instrument will be really used in space, because the conditions may be somewhat different from that on the earth. (Wakatsuki, Y.)

  3. The research of the soil moisture satellite measurements accuracy depending on the underlying surface characteristics

    Science.gov (United States)

    Borodina, Irina A.; Kizhner, Lubov I.; Bogoslovskiy, Nikolay N.; Rudikov, Dmitrii S.; Erin, Sergei I.

    2015-11-01

    The work is devoted to the assessment of the possibility of using satellite data to determine soil moisture. The direct satellite observations were compared with the direct observations at the stations. Pearson correlation coefficient and the relative errors were calculated. The comparison of the data from the direct measurements of the soil moisture and satellite measurements showed that for the 52% of the stations the correlation coefficients exceeded 0.5.

  4. Global Land Surface Emissivity Retrieved From Satellite Ultraspectral IR Measurements

    Science.gov (United States)

    Zhou, D. K.; Larar, A. M.; Liu, Xu; Smith, W. L.; Strow, L. L.; Yang, Ping; Schlussel, P.; Calbet, X.

    2011-01-01

    Ultraspectral resolution infrared (IR) radiances obtained from nadir observations provide information about the atmosphere, surface, aerosols, and clouds. Surface spectral emissivity (SSE) and surface skin temperature from current and future operational satellites can and will reveal critical information about the Earth s ecosystem and land-surface-type properties, which might be utilized as a means of long-term monitoring of the Earth s environment and global climate change. In this study, fast radiative transfer models applied to the atmosphere under all weather conditions are used for atmospheric profile and surface or cloud parameter retrieval from ultraspectral and/or hyperspectral spaceborne IR soundings. An inversion scheme, dealing with cloudy as well as cloud-free radiances observed with ultraspectral IR sounders, has been developed to simultaneously retrieve atmospheric thermodynamic and surface or cloud microphysical parameters. This inversion scheme has been applied to the Infrared Atmospheric Sounding Interferometer (IASI). Rapidly produced SSE is initially evaluated through quality control checks on the retrievals of other impacted surface and atmospheric parameters. Initial validation of retrieved emissivity spectra is conducted with Namib and Kalahari desert laboratory measurements. Seasonal products of global land SSE and surface skin temperature retrieved with IASI are presented to demonstrate seasonal variation of SSE.

  5. Estimating the Retrievability of Temperature Profiles from Satellite Infrared Measurements

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A method is developed to assess retrievability, namely the retrieval potential for atmospheric temperature profiles, from satellite infrared measurements in clear-sky conditions. This technique is based upon generalized linear inverse theory and empirical orthogonal function analysis. Utilizing the NCEP global temperature reanalysis data in January and July from 1999 to 2003, the retrievabilities obtained with the Atmospheric Infrared Sounder (AIRS) and the High Resolution Infrared Radiation Sounder/3 (HIRS/3)sounding channel data are derived respectively for each standard pressure level on a global scale. As an incidental result of this study, the optimum truncation number in the method of generalized linear inverse is deduced too. The results show that the retrievabilities of temperature obtained with the two datasets are similar in spatial distribution and seasonal change characteristics. As for the vertical distribution, the retrievabilities are low in the upper and lower atmosphere, and high between 400 hPa and 850 hPa. For the geographical distribution, the retrievabilities are low in the low-latitude oceanic regions and in some regions in Antarctica, and relatively high in mid-high latitudes and continental regions. Compared with the HIRS/3 data, the retrievability obtained with the AIRS data can be improved by an amount between 0.15 and 0.40.

  6. Conceptualisation statistique du champ de la culture

    OpenAIRE

    Deroin, Valérie; Chaintreau, Jean-François

    2015-01-01

    La définition du champ statistique de la culture a fait l’objet de travaux européens de 2009 à 2011, après que les nomenclatures nationales (nomenclature d’activités françaises, NAF Rév. 2) et européenne (nomenclature statistique des activités économiques dans la Communauté européenne, NACE Rév. 2) ont été rénovées en 2008. Sous l’égide d’Eurostat, l’Office statistique de l’Union européenne, un groupe de travail européen (Task Force 1) a conçu la structure du nouveau cadre statistique europée...

  7. CHaMP metrics - Columbia Habitat Monitoring Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of CHaMP is to generate and implement a standard set of fish habitat monitoring (status and trend) methods in up to 26 watersheds across the Columbia River...

  8. A statistical analysis of longitudinal dependences of upper thermospheric zonal winds at dip equator latitudes derived from CHAMP

    Science.gov (United States)

    Häusler, K.; Lühr, H.; Rentz, S.; Köhler, W.

    2007-08-01

    New observations, obtained by the accelerometer onboard the CHAMP satellite, reveal a detailed picture of the thermospheric zonal wind. Based on three years of data (2002 2004) we have studied the longitudinal dependence of the zonal delta wind (deviations from the zonal average) at the dip equator. The large number of passes (˜33 750) allows to consider several aspects of the wind characteristics at the same time. For this analysis we derived the longitudinal variation of the zonal delta wind at about 400 km altitude and investigated its dependence on solar flux, magnetic activity, and season. Major longitudinal dependences are confined to the morning hours, 03-09 local time (LT). The amplitude of the delta wind is approximately proportional to the latitudinal displacement of the magnetic dip equator from the geographic equator. The direction of the delta wind reverses sign between the June and December Solstices. During Equinox seasons these large scale features are almost absent. The flux level of solar EUV has no significant influence on the longitudinal variations. A dependence on magnetic activity could only be found during the post-sunset hours, 18-21 LT. Performing a Fourier transform of our delta wind velocities revealed a dominance of the wavenumber 4 in the Equinox data at some LT sectors. The wave-4 structure is a prevailing feature in the slowly precessing satellite frame, which has been recently reported, e.g. in nonmigrating tidal temperature measurements of the SABER instrument on the TIMED satellite in the Mesosphere Lower Thermosphere (MLT) region. Therefore, this statistical study of zonal wind longitudinal dependences provides new observational evidence for the coupling of the various atmospheric layers by nonmigrating tides.

  9. Global characteristics of the lunar tidal modulation of the equatorial electrojet derived from CHAMP observations

    Directory of Open Access Journals (Sweden)

    H. Lühr

    2012-03-01

    Full Text Available It has been known since many decades that lunar tide has an influence on the strength of the equatorial electrojet (EEJ. There has, however, never been a comprehensive study of the tidal effect on a global scale. Based on the continuous magnetic field measurements by the CHAMP satellite over 10 years it is possible to investigate the various aspects of lunar effects on the EEJ. The EEJ intensity is enhanced around times when the moon is overhead or at the antipode. This effect is particularly strong around noon, shortly after new and full moon. The lunar tide manifests itself as a semi-diurnal wave that precesses through all local times within one lunar month. The largest tidal amplitudes are observed around December solstice and smallest around June solstice. The tidal wave crest lags behind the moon phase. During December this amounts to about 4 days while it is around 2 days during other times of the year. We have not found significant longitudinal variations of the lunar influence on the EEJ. When comparing the average EEJ amplitude at high solar activity with that during periods of solar minimum conditions a solar cycle dependence can be found, but the ratio between tidal amplitude and EEJ intensity stays the same. Actually, tidal signatures standout clearer during times of low solar activity. We suggest that the tidal variations are caused by a current system added to the EEJ rather than by modulating the EEJ. Gravitational forcing of the lower atmosphere by the moon and the sun is assumed to be the driver of an upward propagating tidal wave. The larger tidal amplitudes around December solstice can be related to stratospheric warming events which seem to improve the conditions for upward propagation.

    The results described here have to large extent been presented as a Julius-Bartels Medal Lecture during the General Assembly 2011 of the European Geosciences Union.

  10. Lessons learned about the thermosphere-ionosphere system from the CHAMP mission

    International Nuclear Information System (INIS)

    Complete text of publication follows. The recent years have brought enormous progress for our understanding of the characteristics and the variability of the thermosphere. This is mainly based on the high-resolution measurements of the accelerometer on board the CHAMP satellite. It sampled the air drag from the solar maximum in 2001 to the minimum in 2008. This long data set enabled a lot of dedicated studies. One important finding is the close relation of thermospheric features to the geomagnetic field geometry. Here the ionised component has to take the role of the mediator between magnetic field and neutral gas. Examples of that are the equatorial mass density anomaly, the cusp density anomaly and the high-speed wind channel along the dip equator. The thermosphere reacts quite differently to solar and magnetic forcing. This is particularly evident when comparing the mass density on the day and night side at low latitudes. We were able to delineate the variations due to solar flux, season, and magnetic activity. It turns out that the controlling parameters, e.g. F10.7, Day-of-Year or Am influence the thermosphere in a linear fashion. Recently a lot of interest has been put in the tidal modulation of the high atmosphere. Also in the thermosphere at 400 km altitude the signatures of migrating and non-migrating tides have been identified. These are again well correlated with ionospheric signatures. On the evening and morning side terminator waves are identified which still wait for their proper interpretation. Representative examples of the listed effects will be presented.

  11. Marine fluorescence from high spectrally resolved satellite measurements

    Science.gov (United States)

    Wolanin, Aleksandra; Dinter, Tilman; Rozanov, Vladimir; Noël, Stefan; Vountas, Marco; Burrows, John P.; Bracher, Astrid

    2014-05-01

    When chlorophyll molecules absorb light, most of this energy is transformed into chemical energy in a process of photosynthesis. However, a fraction of the energy absorbed is reemitted as fluorescence. As a result of its relationship to photosynthetic e?ciency, information about chlorophyll fluorescence can be used to assess the physiological state of phytoplankton (Falkowski and Kolber,1995). In-situ measurements of chlorophyll fluorescence are widespread in physiological and ecophysiological studies. When retrieved from space, chlorophyll fluorescence can improve our knowledge of global biogeochemical cycles and phytoplankton productivity (Behrenfeld et al., 2009; Huot et al., 2013) by providing high coverage and periodicity. So far, the only satellite retrieval of sun-induced marine fluorescence, Fluorescence Line Height (FLH), was designed for MODIS (Abbott and Letelier, 1999), and later also applied to the similar sensor MERIS (Gower et al., 2004). However, it could so far not be evaluated on global scale. Here, we present a different approach to observe marine chlorophyll fluorescence, based on the Differential Optical Absorption Spectroscopy (DOAS) technique (Perner and Platt, 1979) applied to the hyperspectral data from Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and Global Ozone Monitoring Experiment-2 (GOME-2). Since fluorescence, as a trans-spectral process, leads to the shift of the wavelength of the radiation, it can be observed in the filling-in of Fraunhofer lines. In our retrieval, we evaluate the filling-in of the Zeeman triplet Fraunhofer line FeI at 684.3 nm, which is located very close to the emission peak of marine fluorescence (~685 nm). In order to conduct the chlorophyll fluorescence retrieval with the DOAS method, we calculated the reference spectra for chlorophyll fluorescence, based on simulations performed with the coupled ocean-atmosphere radiative transfer model SCIATRAN (Rozanov et al., 2014

  12. Time-variable gravity signal in Greenland revealed by high-low satellite-to-satellite tracking

    Science.gov (United States)

    Weigelt, M.; Dam, T.; Jäggi, A.; Prange, L.; Tourian, M. J.; Keller, W.; Sneeuw, N.

    2013-07-01

    In the event of a termination of the Gravity Recovery and Climate Experiment (GRACE) mission before the launch of GRACE Follow-On (due for launch in 2017), high-low satellite-to-satellite tracking (hl-SST) will be the only dedicated observing system with global coverage available to measure the time-variable gravity field (TVG) on a monthly or even shorter time scale. Until recently, hl-SST TVG observations were of poor quality and hardly improved the performance of Satellite Laser Ranging observations. To date, they have been of only very limited usefulness to geophysical or environmental investigations. In this paper, we apply a thorough reprocessing strategy and a dedicated Kalman filter to Challenging Minisatellite Payload (CHAMP) data to demonstrate that it is possible to derive the very long-wavelength TVG features down to spatial scales of approximately 2000 km at the annual frequency and for multi-year trends. The results are validated against GRACE data and surface height changes from long-term GPS ground stations in Greenland. We find that the quality of the CHAMP solutions is sufficient to derive long-term trends and annual amplitudes of mass change over Greenland. We conclude that hl-SST is a viable source of information for TVG and can serve to some extent to bridge a possible gap between the end-of-life of GRACE and the availability of GRACE Follow-On.

  13. CONCEPTUAL PAPER : Utilization of GPS Satellites for Precise Irradiation Measurement and Monitoring

    Indian Academy of Sciences (India)

    S. Vijayan

    2008-03-01

    Precise measurement of irradiance over the earth under various circumstances like solar flares, coronal mass ejections, over an 11-year solar cycle, etc. leads to better understanding of Sun–earth relationship. To continuously monitor the irradiance over earth-space regions several satellites at several positions are required. For that continuous and multiple satellite monitoring we can use GPS (Global Positioning System) satellites (like GLONASS, GALILEO, future satellites) installed with irradiance measuring and monitoring instruments. GPS satellite system consists of 24 constellations of satellites. Therefore usage of all the satellites leads to 24 measurements of irradiance at the top of the atmosphere (or 12 measurements of those satellites which are pointing towards the Sun) at an instant. Therefore in one day, numerous irradiance observations can be obtained for the whole globe, which will be very helpful for several applications like Albedo calculation, Earth Radiation Budget calculation, monitoring of near earth-space atmosphere, etc. Moreover, measuring irradiance both in ground (using ground instruments) and in space at the same instant of time over a same place, leads to numerous advantages. That is, for a single position we obtain irradiance at the top of the atmosphere, irradiance at ground and the difference in irradiance from over top of the atmosphere to the ground. Measurement of irradiance over the atmosphere and in ground at a precise location gives more fine details about the solar irradiance influence over the earth, path loss and interaction of irradiance with the atmosphere.

  14. POGO satellite orbit corrections: an opportunity to improve the quality of the geomagnetic field measurements?

    DEFF Research Database (Denmark)

    Stockmann, Reto; Christiansen, Freddy; Olsen, Nils;

    2015-01-01

    We present an attempt to improve the quality of the geomagnetic field measurements from the Polar Orbiting Geophysical Observatory (POGO) satellite missions in the late 1960s. Inaccurate satellite positions are believed to be a major source of errors for using the magnetic observations for field...

  15. 基于引力位系数相对权重的卫星重力场测量分析%Analysis for satellite gravity field measurement based on relative weight of gravitational coefficients

    Institute of Scientific and Technical Information of China (English)

    谷振丰; 刘红卫; 王兆魁; 张育林

    2013-01-01

    卫星重力场测量已成为最有效的全球重力场测量手段.本文结合典型的重力卫星和重力卫星研究计划,分析了卫星重力测量的三种原理,并基于各阶位系数的相对权重讨论了各种原理的应用优势.分析可知,卫星受摄轨道适用于恢复长波重力场,低轨星间距离变化率适用于恢复中长波重力场,重力梯度适用于恢复中短波重力场.针对中长波高精度重力场测量的需要,设计了综合获取低轨星间距离变化率与受摄轨道的重力卫星方案,该方案由两组内编队组成星星跟踪复合编队,轨道高度为250 km,星间距离为50~100 km.%Satellite gravity measurement has been the most efficient method for global gravity model recovery and geoid height determination. With a brief introduction of the representative satellite gravity missions, including CHAMP (A Challenging Minisatellite Payload for Geo-science and Application), GRACE (Gravity Recovery And Climate Experiment), GOCE (Gravity field and steady-state Ocean Circulation Explorer), Inner Formation, GRACE Follow-on and NGGM (Next-Generation Gravimetry Mission), their measuring principles were analyzed and classified into three kinds, which were gravity field recovery with the satellite ephemeris, gravity field recovery with the inter-satellite range-rate and gravity field recovery with gravity gradient measurements. Base on the definition of relative weight for the gravitational potential coefficients of different degrees, application advantages of each measuring principle were analyzed primarily. It is found that there are different sensitive bands for the three measuring principles and they are long wave gravity field recovery, medium-long wave gravity field recovery and medium-short wave gravity field recovery, respectively. The highest degree which could be recovered by a mission can be estimated through the analysis. For example, it is estimated that the CHAMP mission can improve the

  16. Processing Satellite Data for Slant Total Electron Content Measurements

    Science.gov (United States)

    Stephens, Philip John (Inventor); Komjathy, Attila (Inventor); Wilson, Brian D. (Inventor); Mannucci, Anthony J. (Inventor)

    2016-01-01

    A method, system, and apparatus provide the ability to estimate ionospheric observables using space-borne observations. Space-borne global positioning system (GPS) data of ionospheric delay are obtained from a satellite. The space-borne GPS data are combined with ground-based GPS observations. The combination is utilized in a model to estimate a global three-dimensional (3D) electron density field.

  17. Improving Quantitative Measurements using Different Segmentation Techniques for Satellite Images

    OpenAIRE

    Ravi Kumar, K.; K. Kavindra Kumar; R.S.V.M.Krishna; P. K. Bharadwaj

    2011-01-01

    Image segmentation is the most practical approach among all virtually automated image recognition systems. Feature extraction and recognition have numerous applications on telecommunication, weather forecasting, environment exploration and medical diagnosis. This paper deals with different image segmentation algorithms. The quality of satellite image is affected by atmosphere, temperature etc. By the usage of various segmentation techniques ,the image is divided into parts which have strong ...

  18. Superpixel-Based Roughness Measure for Multispectral Satellite Image Segmentation

    Directory of Open Access Journals (Sweden)

    César Antonio Ortiz Toro

    2015-11-01

    Full Text Available The new generation of artificial satellites is providing a huge amount of Earth observation images whose exploitation can report invaluable benefits, both economical and environmental. However, only a small fraction of this data volume has been analyzed, mainly due to the large human resources needed for that task. In this sense, the development of unsupervised methodologies for the analysis of these images is a priority. In this work, a new unsupervised segmentation algorithm for satellite images is proposed. This algorithm is based on the rough-set theory, and it is inspired by a previous segmentation algorithm defined in the RGB color domain. The main contributions of the new algorithm are: (i extending the original algorithm to four spectral bands; (ii the concept of the superpixel is used in order to define the neighborhood similarity of a pixel adapted to the local characteristics of each image; (iii and two new region merged strategies are proposed and evaluated in order to establish the final number of regions in the segmented image. The experimental results show that the proposed approach improves the results provided by the original method when both are applied to satellite images with different spectral and spatial resolutions.

  19. Comparison of Remote Spectrophotometric and Lidar Measurements of O3, NO2, and Temperature with Data of Satellite Measurements

    Science.gov (United States)

    Bazhenov, O. E.; Burlakov, V. D.; Grishaev, M. V.; Gridnev, Yu. V.; Dolgii, S. I.; Makeev, A. P.; Nevzorov, A. V.; Salnikova, N. S.

    2016-06-01

    We consider the results of remote spectrophotometric and lidar measurements of the total ozone and nitrogen dioxide contents and temperature, obtained at the Siberian Lidar Station (SLS) of V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences (Tomsk: 56.5°N; 85.0°E) in comparison with the results of analogous satellite measurements. The ground-based measurements of the total ozone (TO) content are performed with the help of M-124 ozonometer; and the measurements of the nitrogen dioxide (NO2) content are carried out with automatic spectrophotometer. The groundbased lidar measurements of temperature are conducted on the basis of SLS measurement complex. These measurements are compared with data of balloon-sonde and satellite measurements. The satellite measurements are performed by the TOMS and IASI instrumentation.

  20. The complete spectrum of the equatorial electrojet related to solar tides: CHAMP observations

    Directory of Open Access Journals (Sweden)

    H. Lühr

    2013-08-01

    Full Text Available Based on 10 yr of magnetic field measurements by the CHAMP satellite we draw a detailed picture of the equatorial electrojet (EEJ tidal variations. For the first time the complete EEJ spectrum related to average solar tides has been compiled. A large fraction of the resulting spectrum is related to the switch on/off of the EEJ between day and night. This effect has carefully been considered when interpreting the results. As expected, largest amplitudes are caused by the migrating tides representing the mean diurnal variation. Higher harmonics of the daily variations show a 1/f fall-off in amplitude. Such a spectrum is required to represent the vanishing of the EEJ current at night. The migrating tidal signal exhibits a distinct annual variation with large amplitudes during December solstice and equinox seasons but a depression by a factor of 1.7 around June–July. A rich spectrum of non-migrating tidal effects is deduced. Most prominent is the four-peaked longitudinal pattern around August. Almost 90% of the structure can be attributed to the diurnal eastward-propagating tide DE3. In addition the westward-propagating DW5 is contributing to wave-4. The second-largest non-migrating tide is the semi-diurnal SW4 around December solstice. It causes a wave-2 feature in satellite observations. The three-peaked longitudinal pattern, often quoted as typical for the December season, is significantly weaker. During the months around May–June a prominent wave-1 feature appears. To first order it represents a stationary planetary wave SPW1 which causes an intensification of the EEJ at western longitudes beyond 60° W and a weakening over Africa/India. In addition, a prominent ter-diurnal non-migrating tide TW4 causes the EEJ to peak later, at hours past 14:00 local time in the western sector. A particularly interesting non-migrating tide is the semi-diurnal SW3. It causes largest EEJ amplitudes from October through December. This tidal component shows a

  1. History of satellite missions and measurements of the Earth Radiation Budget (1957-1984)

    Science.gov (United States)

    House, F. B.; Gruber, A.; Hunt, G. E.; Mecherikunnel, A. T.

    1986-01-01

    The history of satellite missions and their measurements of the earth radiation budget from the beginning of the space age until the present time are reviewed. The survey emphasizes the early struggle to develop instrument systems to monitor reflected shortwave and emitted long-wave exitances from the earth, and the problems associated with the interpretation of these observations from space. In some instances, valuable data sets were developed from satellite measurements whose instruments were not specifically designed for earth radiation budget observations.

  2. Comparison of Temperature Measurements in the Middle Atmosphere by Satellite with Profiles Obtained by Meteorological Rockets

    Science.gov (United States)

    Goldberg, Richard A.; Schmidlin, Francis J.; Feofilov, Artem; Bedrick, M.; Rose, R. Lynn

    2012-01-01

    Measurements using the inflatable falling sphere technique have occasionally been used to obtain temperature results from density data and thereby provide comparison with temperature profiles obtained by satellite sounders in the mesosphere and stratosphere. To insure density measurements within narrow time frames and close in space, the inflatable falling sphere is launched within seconds of the nearly overhead satellite pass. Sphere measurements can be used to validate remotely measured temperatures but also have the advantage of measuring small-scale atmospheric features. Even so, with the dearth of remaining falling spheres available (the manufacture of these systems has been discontinued), it may be time to consider whether the remote measurements are mature enough to stand alone. Three field studies are considered, one in 2003 from Northern Sweden, and two in 2010 from the vicinity of Kwajalein Atoll in the South Pacific and from Barking Sands, Hawaii. All three sites are used to compare temperature retrievals between satellite and in situ falling spheres. The major satellite instruments employed are SABER, MLS, and AIRS. The comparisons indicate that remotely measured temperatures mimic the sphere temperature measurements quite well. The data also confirm that satellite retrievals, while not always at the exact location required for detailed studies in space and time, compare sufficiently well to be highly useful. Although the falling sphere will provide a measurement at a specific location and time, satellites only pass a given location daily or less frequently. This report reveals that averaged satellite measurements can provide temperatures and densities comparable to those obtained from the falling sphere, thereby providing a reliable measure of global temperature

  3. Statistical magnetic anomalies from satellite measurements for geologic analysis

    Science.gov (United States)

    Goyal, H. K.; Vonfrese, R. R. B.; Hinze, W. J.

    1985-01-01

    The errors of numerically averaging satellite magnetic anomaly data for geologic analysis are investigated using orbital anomaly simulations of crustal magnetic sources by Gauss-Legendre quadrature integration. These simulations suggest that numerical averaging errors constitute small and relatively minor contributions to the total error-budget of higher orbital estimates (approx. 400 km), whereas for lower orbital estimates the error of averaging may increase substantially. Least-squares collocation is also investigated as an alternative to numerical averaging and found to produce substantially more accurate anomaly estimates as the elevation of prediction is decreased towards the crustal sources.

  4. Spatial Distribution of Aerosols in Four U.S. Regions: Impacts on Satellite Measurements

    Science.gov (United States)

    Beyersdorf, A. J.; Ziemba, L. D.; Berkoff, T.; Burton, S. P.; Chen, G.; Corr, C.; Collins, J. E., Jr.; Crumeyrolle, S.; Cook, A. L.; Fenn, M. A.; Ferrare, R. A.; Hair, J. W.; Harper, D. B.; Hostetler, C. A.; Lin, J. J.; Martin, R.; Moore, R.; Rogers, R. R.; Scarino, A. J.; Seaman, S. T.; Shook, M.; Thornhill, K. L., II; Crawford, J. H.; Anderson, B. E.

    2015-12-01

    Aerosol measurements from satellites in geosynchronous orbit allow for a unique opportunity to measure urban air quality at higher spatial and temporal resolution than possible with current ground-based monitoring and satellites in low earth orbit. Geosynchronous satellites will be able to measure air quality throughout the day for a specific region of interest (such as North America for the planned NASA TEMPO satellite). However, a key constraint on satellite measurements is the spatial resolution of the retrieved data products. As the satellite footprint increases, the precision of aerosol properties improves but the ability of the satellite to measure small-scale variations in pollution diminishes. Currently, TEMPO is planned to measure aerosol optical depth (AOD) with a spatial resolution of 36 square-km. In this study, sub-pixel variability is used as a metric of how representative the satellite measurement is of ground-based air quality. Data from the DISCOVER-AQ airborne project are used to determine the sub-pixel variability in AOD, boundary layer extinction and other aerosol properties in four U.S. regions: Baltimore, Maryland, Houston, Texas, Denver, Colorado, and California's San Joaquin Valley. Sub-pixel variability in boundary layer extinction was lowest in Denver (one sigma variability of 3 /Mm at 36 square-km spatial resolution) due to low aerosol loadings and highest in the San Joaquin Valley (19 /Mm) due to variable boundary layer depths and stagnant conditions. Variability in AOD (measured by an airborne high-spectral resolution lidar) was more consistent among the sites (0.017 to 0.035) due to a reduced dependence on changes in the planetary boundary layer. The effects of our analysis will also be discussed in relation to the use of satellite measurements to infer air quality attainment. Larger satellite data footprints reduce the ability of satellites to identify small regions in urban areas with elevated pollution (i.e. hotspots) which was

  5. Towards an empirical measure of spacecraft innovation: The case of communication satellites

    Science.gov (United States)

    Szajnfarber, Zoe; Weigel, Annalisa L.

    2010-04-01

    This paper seeks to frame the discussion of innovation in the space sector and creates a platform for future analysis. To accomplish this, it addressed three aspects of the task of measurement. First, it surveys several distinct literatures to establish precedence for defining a spacecraft innovation metric. Second, the conceptual trade-offs associated with adopting this principle in the context of communication satellites are elucidated and treated. By defining product boundaries along the dimensions of product scope and market transactions, three paradigms for measurement are proposed; namely: (1) the communication satellite enterprise; (2) the physical satellite; and (3) communication service. Third, under the constraints of historical data collection realities, next-best estimators are put forward as proxies for the parameters required to implement the proposed metrics. Based on these proxies, the relative merits of each measurement paradigm are illustrated through an analysis of the innovation history of communication satellites.

  6. Combining human and machine processes (CHAMP)

    Science.gov (United States)

    Sudit, Moises; Sudit, David; Hirsch, Michael

    2015-05-01

    Machine Reasoning and Intelligence is usually done in a vacuum, without consultation of the ultimate decision-maker. The late consideration of the human cognitive process causes some major problems in the use of automated systems to provide reliable and actionable information that users can trust and depend to make the best Course-of-Action (COA). On the other hand, if automated systems are created exclusively based on human cognition, then there is a danger of developing systems that don't push the barrier of technology and are mainly done for the comfort level of selected subject matter experts (SMEs). Our approach to combining human and machine processes (CHAMP) is based on the notion of developing optimal strategies for where, when, how, and which human intelligence should be injected within a machine reasoning and intelligence process. This combination is based on the criteria of improving the quality of the output of the automated process while maintaining the required computational efficiency for a COA to be actuated in timely fashion. This research addresses the following problem areas: • Providing consistency within a mission: Injection of human reasoning and intelligence within the reliability and temporal needs of a mission to attain situational awareness, impact assessment, and COA development. • Supporting the incorporation of data that is uncertain, incomplete, imprecise and contradictory (UIIC): Development of mathematical models to suggest the insertion of a cognitive process within a machine reasoning and intelligent system so as to minimize UIIC concerns. • Developing systems that include humans in the loop whose performance can be analyzed and understood to provide feedback to the sensors.

  7. ChaMP Serendipitous Galaxy Cluster Survey

    Energy Technology Data Exchange (ETDEWEB)

    Barkhouse, Wayne A.; Green, P.J.; Vikhlinin, A.; Kim, D.-W.; Perley, D.; Cameron, R.; Silverman, J.; Mossman, A.; Burenin, R.; Jannuzi, B.T.; Kim, M.; Smith, M.G.; Smith,; Tananbaum, H.; Wilkes, B.J.; /Harvard-Smithsonian Ctr. Astrophys. /UC, Berkeley, Astron. Dept. /SLAC /Garching, Max Planck Inst., MPE /Moscow, Space Res. Inst. /NOAO, Tucson

    2006-04-03

    We present a survey of serendipitous extended X-ray sources and optical cluster candidates from the Chandra Multi-wavelength Project (ChaMP). Our main goal is to make an unbiased comparison of X-ray and optical cluster detection methods. In 130 archival Chandra pointings covering 13 square degrees, we use a wavelet decomposition technique to detect 55 extended sources, of which 6 are nearby single galaxies. Our X-ray cluster catalog reaches a typical flux limit of about {approx} 10{sup -14} erg s{sup -1} cm{sup -2}, with a median cluster core radius of 21''. For 56 of the 130 X-ray fields, we use the ChaMP's deep NOAO/4m MOSAIC g', r', and i' imaging to independently detect cluster candidates using a Voronoi tessellation and percolation (VTP) method. Red-sequence filtering decreases the galaxy fore/background contamination and provides photometric redshifts to z {approx} 0.7. From the overlapping 6.1 square degree X-ray/optical imaging, we find 115 optical clusters (of which 11% are in the X-ray catalog) and 28 X-ray clusters (of which 46% are in the optical VTP catalog). The median redshift of the 13 X-ray/optical clusters is 0.41, and their median X-ray luminosity (0.5-2 keV) is L{sub X} = (2.65 {+-} 0.19) x 10{sup 43} ergs s{sup -1}. The clusters in our sample that are only detected in our optical data are poorer on average ({approx} 4{sigma}) than the X-ray/optically matched clusters, which may partially explain the difference in the detection fractions.

  8. Diffusion d'un champ electromagnetique par un batiment modelise

    OpenAIRE

    Bourrely, Claude

    2008-01-01

    Cette étude présente la diffusion d'un champ électromagnétique par un batiment de bureaux modélisé suivant un réseau bipériodique, en particulier, l'objectif est de calculer le champ réfléchi et transmis. Ce champ est produit par une antenne extérieure au batiment, on suppose qu'elle émet une onde plane. On travaille dans un domaine de longueur d'onde qui est inférieur à la plus petite dimension de la structure, ce qui correspond à l'épaisseur des murs. Les calculs sont effectués suivant la m...

  9. La traversée du champ matrimonial

    OpenAIRE

    Macherel, Claude

    2003-01-01

    Le champ matrimonial, c'est cette portion de l'espace social où évoluent les célibataires épousables. Ces prétendant(e)s incarnent simultanément les enjeux, à la fois économiques et sexuels, des désirs qui polarisent le champ et, conjonction rare dans la vie sociale, les concurrents de la compétition pour ces enjeux. La première partie de l'article décrit ce champ, tel qu'il fonctionna jusqu'à la Seconde Guerre mondiale dans une société paysanne européenne, la vallée de Loetschen, en H...

  10. Large Diurnal Sea Surface Temperature Variability: Satellite and In Situ Measurements

    OpenAIRE

    Stramma, Lothar; Cornillon, Peter; Weller, Robert A.; James F. Price; Briscoe, Melbourne G.

    1986-01-01

    Data from a surface mooring located in the Sargasso Sea at 34°N, 70°W between May 1982 and May 1984 were compared with satellite data to investigate large diurnal sea surface temperature changes. Mooring and satellite measurements are in excellent agreement for those days on which no clouds covered the site at the time of the satellite pass. During the summer half-year at this site, there is a 20% charm of diurnal warming of more than 0.5°C, with values of up to 3.5°C observed in the two-year...

  11. High-orbit satellite reflection surface geometry information estimation using photometric measurement method

    Science.gov (United States)

    Zhang, Shixue

    2015-10-01

    The method to get high-orbit satellite basic information such as geometry and material characteristic, is an important goal in the field of space posture apperception. In this paper, we calculate the satellite magnitude by comparing the output value of camera's CCD between the known fixed star and the satellite. We select certain reference stars to calculate the luminance value of a certain object on the acquired image using a background-removing method. We make time-domain analysis of the measurement data, and get the statistic result. With the knowledge of the theory brightness of the target, we estimate the geometric characteristics of the target. We have got a serious of the images of a certain satellite on large telescope. The experimental results demonstrate that, the accuracy of the measured magnitude is better than 0.12Mv, and the estimation error of the target reflection surface size is less than 15%.

  12. Precession–nutation correction for star tracker attitude measurement of STECE satellite

    OpenAIRE

    Lai Yuwang; Liu Junhong; Ding Yonghe; Gu Defeng; Yi Dongyun

    2014-01-01

    Space Technology Experiment and Climate Exploration (STECE) is a small satellite mission of China for space technology experiment and climate exploration. A new test star tracker and one ASTRO 10 star tracker have been loaded on the STECE satellite to test the new star tracker’s measurement performance. However, there is no autonomous precession–nutation correction function for the test star tracker, which causes an apparent periodic deflection in the inter-boresight angle between the two sta...

  13. Investigation of the Crust of the Pannonian Basin, Hungary Using Low-Altitude CHAMP Horizontal Gradient Magnetic Anomalies

    Science.gov (United States)

    Taylor, Patrick T.; Kis, Karoly I.; Puszta, Sandor; Wittmann, Geza; Kim, Hyung Rae; Toronyi, B.

    2011-01-01

    The Pannonian Basin is a deep intra-continental basin that formed as part of the Alpine orogeny. It is some 600 by 500 km in area and centered on Hungary. This area was chosen since it has one of the thinnest continental crusts in Europe and is the region of complex tectonic structures. In order to study the nature of the crustal basement we used the long-wavelength magnetic anomalies acquired by the CHAMP satellite. The SWARM constellation, scheduled to be launched next year, will have two lower altitude satellites flying abreast, with a separation of between ca. 150 to 200 km. to record the horizontal magnetic gradient. Since the CHAMP satellite has been in orbit for eight years and has obtained an extensive range of data, both vertically and horizontally there is a large enough data base to compute the horizontal magnetic gradients over the Pannonian Basin region using these many CHAMP orbits. We recomputed a satellite magnetic anomaly map, using the spherical-cap method of Haines (1985), the technique of Alsdorf et al. (1994) and from spherical harmonic coefficients of MF6 (Maus et aI., 2008) employing the latest and lowest altitude CHAMP data. We then computed the horizontal magnetic anomaly gradients (Kis and Puszta, 2006) in order to determine how these component data will improve our interpretation and to preview what the SW ARM mission will reveal with reference to the horizontal gradient anomalies. The gradient amplitude of an 1000 km northeast-southwest profile through our horizontal component anomaly map varied from 0 to 0.025 nT/km with twin positive anomalies (0.025 and 0.023 nT/km) separated by a sharp anomaly negative at o nT/km. Horizontal gradient indicate major magnetization boundaries in the crust (Dole and Jordan, 1978 and Cordell and Grauch, 1985). Our gradient anomaly was modeled with a twodimensional body and the anomaly, of some 200 km, correlates with a 200 km area of crustal thinning in the southwestern Pannonian Basin.

  14. Time Series Correlated Error's Simulation Scheme with the Application to Simulate the Ephemerides Error of CHAMP

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Computer simulation experiment is very important in the phase of project design, the availability of simulated result highly depends on the scheme of error simulation. Time series observations are normally correlated. This paper first discusses the formula of correlated error propagation, then derives the formula of simulating time series correlated errors. This formula is then used to simulate correlated ephemerides errors of CHAMP, then the ephemerides are used to recover the gravity vector at satellite altitude with finite differential formula. The formulae derived in this paper are verified with the difference between the recovered gravity vectors and the true values' which are directly computed with the same gravity model as that generating the ephemerides.

  15. Long-term analysis of ionospheric polar patches based on CHAMP TEC data

    DEFF Research Database (Denmark)

    Noja, M.; Stolle, Claudia; Park, J.;

    2013-01-01

    Total electron content (TEC) from LEO satellites offers great possibility to sound the upper ionosphere and plasmasphere. This paper describes a method to derive absolute TEC observations aboard CHAMP considering multipath effects and receiver differential code bias. The long-term data set of 9...... a higher number of patches in the SH. The maximum occurrence rate of patches has been found at the dayside polar cusp during 12:00-18:00 MLT (magnetic local time) supporting the mechanisms for patch creation by local particle precipitation and by intrusion of subauroral plasma into the polar cap through...... creation follows a period of enhanced solar wind input into the magnetosphere/ionosphere. We further found an annual cycle in patch occurrence with maxima at equinox and December solstice and a June solstice minimum which reflects the global ionospheric seasonal asymmetry in electron density. We suggest...

  16. First ultraviolet reflectance measurements of several Kuiper Belt objects, Kuiper Belt object satellites, and new ultraviolet measurements of A Centaur

    Energy Technology Data Exchange (ETDEWEB)

    Stern, S. A.; Schindhelm, E. [Southwest Research Institute, 1050 Walnut Street, Boulder, CO 80302 (United States); Cunningham, N. J., E-mail: astern@swri.edu [Nebraska Wesleyan University, 5000 Saint Paul Avenue, Lincoln, NE 68504 (United States)

    2014-05-01

    We observed the 2600-3200 Å (hereafter, mid-UV) reflectance of two Kuiper Belt Objects (KBOs), two KBO satellites, and a Centaur, using the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS). Other than measurements of the Pluto system, these constitute the first UV measurements obtained of KBOs, and KBO satellites, and new HST UV measurements of the Centaur 2060 Chiron. We find significant differences among these objects, constrain the sizes and densities of Haumea's satellites, and report the detection of a possible spectral absorption band in Haumea's spectrum near 3050 Å. Comparisons of these objects to previously published UV reflectance measurements of Pluto and Charon are also made here.

  17. Comparisons of satellite-derived and in situ global sea surface temperature measurements

    Science.gov (United States)

    Njoku, Eni G.

    1985-01-01

    Attention is given to a series of three workshops held between January 1983 and February 1984 to compare presently available techniques for measuring SST. Measurements from SST from four satellite sensors were evaluated by direct comparison with one another and with measurements from ships, expendible bathythermographs, and buoys. The satellite data showed good agreement in a global rms sense (about 0.5-1.0 C), but several anomalous regional biases were observed. The biases are ascribed in some cases to instrument calibration deficiencies. In other cases, inadequacies of the retrieval algorithms are suspected to be the case. Suggestions for improving sensors and retrieval methods are discussed.

  18. Project CHAMP, 1984-1985. OEA Evaluation Report.

    Science.gov (United States)

    New York City Board of Education, Brooklyn. Office of Educational Assessment.

    In 1984-1985, the second year of a three-year funding cycle, Project CHAMP provided instruction to 600 primarily Chinese-speaking students of limited English proficiency (LEP) in grades 9-12 at Seward Park, Washington Irving, and Martin Luther King, Jr. High Schools in New York, New York. Seward Park was the primary site of the project and most…

  19. Project CHAMP, 1985-1986. OEA Evaluation Report.

    Science.gov (United States)

    New York City Board of Education, Brooklyn. Office of Educational Assessment.

    The Chinese Achievement and Mastery program, Project CHAMP, was a bilingual (Chinese/English) project offered at three high schools in Manhattan. The major goals were to enable Chinese students of limited English proficiency (LEP) to learn English and to master content in mathematics, science, global history, computer mathematics, and native…

  20. Project CHAMP, 1983-1984: OEA Evaluation Report.

    Science.gov (United States)

    New York City Board of Education, Brooklyn. Office of Educational Assessment.

    Project CHAMP provides instruction in English as a second language (ESL), native language arts, and content-area instruction in mathematics, science, and social studies to Chinese students of limited English proficiency (LEP) in three New York City high schools: Seward Park, Washington Irving, and Martin Luther King, Jr. In 1983-84, the first year…

  1. Project CHAMP, 1986-1987. OEA Evaluation Report.

    Science.gov (United States)

    Cabrera, Eulalia; And Others

    In its fourth year, Project CHAMP (Chinese Achievement and Mastery Program) provided instruction in English as a second language (ESL), native language arts, mathematics, science, and social studies to 728 limited-English-speaking Chinese immigrant students in grades nine through twelve at three schools. Content-area classes were taught in English…

  2. Measurements of ionospheric TEC in the direction of GPS satellites and comparison with three ionospheric models

    Directory of Open Access Journals (Sweden)

    E. Zuccheretti

    1997-06-01

    Full Text Available The IEN Galileo Ferraris uses GPS for time and frequency synchronization. To obtain high performance it is important to reduce the error due to the ionospheric time-delay in GPS measurements. Evaluations of TEC in the direction of GPS satellites, obtained from three different ionospheric models, have been compared with corresponding measurements by GPS signal.

  3. Hyperspectral and multispectral above-water radiometric measurements to monitor satellite data quality over coastal area

    Science.gov (United States)

    Ahmed, Samir; Harmel, Tristan; Gilerson, Alexander; Hlaing, Soe; Tonizzo, Alberto; Davis, Curtiss; Weidemann, Alan; Arnone, Robert

    2011-06-01

    The Long Island Sound Coastal Observational platform (LISCO) near Northport, New York, has been recently established to support satellite data validation. LISCO has both multispectral and hyperspectral radiometers for ocean color measurements. LISCO offers the potential for improving the calibration and validation activities of current and future Ocean Color satellite missions, as well as for satellite intercomparisons and spectral characterization of coastal waters. The multispectral measurements (SeaPRISM system) are part of the NASA AERONET - Ocean Color Network. In addition, LISCO expand observational capabilities for the continuous monitoring and assessment of the hyperspectral (HyperSAS system) and polarized properties Results of measurements made by both the multi- and hyper-spectral instruments, in operation since October 2009, are presented. Intercomparisons between HyperSAS and SeaPRISM data has been carried out, permitting the quantification of the main sources of uncertainty. The three main OCR satellites, MERIS, MODIS and SeaWiFS, have been evaluated against the LISCO dataset of quality-checked measurements of SeaPRISM and HYPERSAS. A first attempt of validation of the hyperspectral imagery provided by the HICO satellite mission is also presented.

  4. Satellite Infrared Radiation Measurements Prior to the Major Earthquakes

    Science.gov (United States)

    Ouzounov, Dimitar; Pulintes, S.; Bryant, N.; Taylor, Patrick; Freund, F.

    2005-01-01

    This work describes our search for a relationship between tectonic stresses and increases in mid-infrared (IR) flux as part of a possible ensemble of electromagnetic (EM) phenomena that may be related to earthquake activity. We present and &scuss observed variations in thermal transients and radiation fields prior to the earthquakes of Jan 22, 2003 Colima (M6.7) Mexico, Sept. 28 .2004 near Parkfield (M6.0) in California and Northern Sumatra (M8.5) Dec. 26,2004. Previous analysis of earthquake events has indicated the presence of an IR anomaly, where temperatures increased or did not return to its usual nighttime value. Our procedures analyze nighttime satellite data that records the general condtion of the ground after sunset. We have found from the MODIS instrument data that five days before the Colima earthquake the IR land surface nighttime temperature rose up to +4 degrees C in a 100 km radius around the epicenter. The IR transient field recorded by MODIS in the vicinity of Parkfield, also with a cloud free environment, was around +1 degree C and is significantly smaller than the IR anomaly around the Colima epicenter. Ground surface temperatures near the Parkfield epicenter four days prior to the earthquake show steady increase. However, on the night preceding the quake, a significant drop in relative humidity was indicated, process similar to those register prior to the Colima event. Recent analyses of continuous ongoing long- wavelength Earth radiation (OLR) indicate significant and anomalous variability prior to some earthquakes. The cause of these anomalies is not well understood but could be the result of a triggering by an interaction between the lithosphere-hydrosphere and atmospheric related to changes in the near surface electrical field and/or gas composition prior to the earthquake. The OLR anomaly usually covers large areas surrounding the main epicenter. We have found strong anomalies signal (two sigma) along the epicentral area signals on Dec 21

  5. Validation of satellite data with IASOA observatories and shipboard measurements in Arctic Ocean

    Science.gov (United States)

    Repina, Irina; Artamonov, Arseniy; Mazilkina, Alexandra; Valiullin, Denis; Stanichny, Sergey

    2016-04-01

    The paper shows the possibility of using surface observation data at high latitudes for the validation of different satellite products. We use data from International Arctic Systems for Observing the Atmosphere (IASOA) observatories and data from Nansen and Amundsen basins observation system (NABOS) project. The NABOS field experiment was carried out in the central part of the Arctic and in the eastern Arctic seas during summer and fall period of 2004-2009, 2013 and 2015. Newly improved satellite products and surface observations provide an opportunity to revisit remote-sensing capabilities for estimating shortwave and longwave radiative fluxes, as well as turbulent fluxes at high latitudes. Estimates of SW fluxes from the MODIS and LW fluxes from the NOAA satellites are evaluated against land observations from IASOA observatories, and unique shipboard measurements. Results show that the satellite products are in better agreement with observations than those from numerical models. Therefore, the large scale satellite based estimates should be useful for model evaluation and for providing information in formulating energy budgets at high latitudes. Visible and near-infrared albedos over snow and ice surfaces are retrieved from AVHRR. Comparison with surface measurements of albedo in arctic observatories and Arctic ocean shows very good agreement. Meteorological and micrometeorological observations were used to validate the surface temperature and surface heat fluxes in the satellite data. Compared data arrays are independent and sufficiently detailed to perform trustworthy evaluations. The spatial and temporal patterns of the resulting flux fields are investigated and compared with those derived from satellite observations such as HOAPS, from blended data such as AOFLUX (in the open water cases). A computation of the sensible heat flux at the surface is formulated on the basis of spatial variations of the surface temperature estimated from satellite data. Based on

  6. Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

    Directory of Open Access Journals (Sweden)

    Ghangho Kim

    2015-04-01

    Full Text Available A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO satellite using single-epoch measurements from a Global Positioning System (GPS receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS. Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state.

  7. IO and Glyoxal measured in the FT during the TORERO campaign - Implications for Satellite Retrievals

    Science.gov (United States)

    Dix, B. K.; Baidar, S.; Schoenhardt, A.; Volkamer, R. M.

    2012-12-01

    Atmospheric iodine monoxide (IO) destroys heat trapping ozone and can form aerosols. Glyoxal is an indicator for hydrocarbon oxidation, and a precursor for secondary organic aerosol. Solar stray light satellites show elevated IO and glyoxal over the tropical Pacific, but the quantitative interpretation and use of these measurements to constrain ocean sources is currently limited by missing information about vertical distributions. Here we report on observations of IO and glyoxal in the tropical marine boundary layer (MBL) and free troposphere (FT) over the Eastern Pacific Ocean. Measurements were performed using the University of Colorado airborne Multi-Axis DOAS instrument (CU AMAX-DOAS) aboard the NSF/NCAR GV research aircraft during the TORERO field campaign in January and February 2012. We present (1) vertical aerosol and trace gas profiles, and (2) case studies comparing aircraft IO data to IO observed from space by the SCIAMCHY satellite instrument. An earlier research flight over the Central tropical Pacific reveals that two thirds of the IO vertical column is located in the FT, and suggests a potentially strong sensitivity in satellite total columns to IO vertical distributions. Here we investigate the question whether satellites indicate MBL processes by means of TORERO measured trace gas profiles over different ocean environments in early attempts to provide an improved understanding of satellite maps.

  8. Comparison of land surface temperature measurements at NOAA CRN sites with airborne and satellite observations

    Science.gov (United States)

    Krishnan, P.; Kochendorfer, J.; Baker, B.; Dumas, E.; Meyers, T. P.; Guillevic, P.; Corda, S.; Muratore, J.; Martos, B.

    2011-12-01

    Land surface temperature (LST) is a key variable for studying global or regional land surface processes and the energy and water vapor exchange at the biosphere-atmosphere interface. In an effort to better quantify the spatial variability and overall representativeness of single-point surface temperature measurement being recorded at NOAA's Climate Reference Network (CRN) sites and to improve the accuracy of satellite land surface temperature measurements, airborne flight campaigns were conducted over two vegetated sites in Tennessee, USA during 2010 to 2011. During the campaign, multiple measurements of land surface temperature were made using Infra-Red temperature sensors at micrometeorological tower sites and onboard an instrumented Piper Navajo airborne research aircraft. In addition to this, coincident Moderate Resolution Imaging Spectroradiometer (MODIS) LST observations, onboard the NASA Terra and Aqua Earth Observing System satellites were used. The aircraft-based and satellite based land surface temperature measurements were compared to in situ, tower based LST measurements. Preliminary results show good agreement between in situ, aircraft and satellite measurements.

  9. Long-term stability of TES satellite radiance measurements

    OpenAIRE

    T. C. Connor; M. W. Shephard; V. H. Payne; K. E. Cady-Pereira; Kulawik, S. S.; Luo, M.; G. Osterman; M. Lampel

    2011-01-01

    The utilization of Tropospheric Emission Spectrometer (TES) Level 2 (L2) retrieval products for the purpose of assessing long term changes in atmospheric trace gas composition requires knowledge of the overall radiometric stability of the Level 1B (L1B) radiances. The purpose of this study is to evaluate the stability of the radiometric calibration of the TES instrument by analyzing the difference between measured and calculated brightness temperatures in selected window regions of the spectr...

  10. Long-term stability of TES satellite radiance measurements

    OpenAIRE

    T. C. Connor; M. W. Shephard; V. H. Payne; K. E. Cady-Pereira; Kulawik, S. S.; Luo, M.; G. Osterman; M. Lampel

    2011-01-01

    The utilization of Tropospheric Emission Spectrometer (TES) Level 2 (L2) retrieval products for the purpose of assessing long term changes in atmospheric trace gas composition requires knowledge of the overall radiometric stability of the Level 1B (L1B) radiances. The purpose of this study is to evaluate the stability of the radiometric calibration of the TES instrument by analyzing the difference between measured and calculated brightness temperatures in selected window reg...

  11. Utility of Satellite Magnetic Observations for Estimating Near-Surface Magnetic Anomalies

    Science.gov (United States)

    Kim, Hyung Rae; vonFrese, Ralph R. B.; Taylor, Patrick T.; Kim, Jeong Woo; Park, Chan Hong

    2003-01-01

    Regional to continental scale magnetic anomaly maps are becoming increasingly available from airborne, shipborne, and terrestrial surveys. Satellite data are commonly considered to fill the coverage gaps in regional compilations of these near-surface surveys. For the near-surface Antarctic magnetic anomaly map being produced by the Antarctic Digital Magnetic Anomaly Project (ADMAP), we show that near-surface magnetic anomaly estimation is greatly enhanced by the joint inversion of the near-surface data with the satellite observations relative to the conventional technique such as minimum curvature. Orsted observations are especially advantageous relative to the Magsat data that have order-of-magnitude greater measurement errors, albeit at much lower orbital altitudes. CHAMP is observing the geomagnetic field with the same measurement accuracy as the Orsted mission, but at the lower orbital altitudes covered by Magsat. Hence, additional significant improvement in predicting near-surface magnetic anomalies can result as these CHAMP data are available. Our analysis also suggests that considerable new insights on the magnetic properties of the lithosphere may be revealed by a further order-of-magnitude improvement in the accuracy of the magnetometer measurements at minimum orbital altitude.

  12. Measurements of satellite refrigerator compressor power consumption and efficiency

    International Nuclear Information System (INIS)

    Each of the thirty compressors installed around the ring and at switchyard is an oil-injected, two-stage, Mycom screw compressor, driven by either a 350 hp or 400 hp motor. The reader is referred to TM1198 by John Satti for a detailed description of these compressors and the associated equipment. Since the power consumed by these compressors is a major operating expense for our accelerator, we were interested in measuring the power consumption and efficiency of our compressors. Two compressors were studied in detail - one having a GE 350 hp motor (F0 No. 2) and one a new GE 400 hp high efficiency motor (F0 No. 1). Data were taken for each compressor with the high stage always fully loaded. These data and values calculated from the data are tabulated

  13. Long-term stability of TES satellite radiance measurements

    Directory of Open Access Journals (Sweden)

    T. C. Connor

    2011-03-01

    Full Text Available The utilization of Tropospheric Emission Spectrometer (TES Level 2 (L2 retrieval products for the purpose of assessing long term changes in atmospheric trace gas composition requires knowledge of the overall radiometric stability of the Level 1B (L1B radiances. The purpose of this study is to evaluate the stability of the radiometric calibration of the TES instrument by analyzing the difference between measured and calculated brightness temperatures in selected window regions of the spectrum. The Global Modeling and Assimilation Office (GMAO profiles for temperature and water vapor and the Real-Time Global Sea Surface Temperature (RTGSST are used as input to the Optimal Spectral Sampling (OSS radiative transfer model to calculate the simulated spectra. The TES reference measurements selected cover a 4-year period of time from mid 2005 through mid 2009 with the selection criteria being; observation latitudes greater than −30° and less than 30°, over ocean, Global Survey mode (nadir view and retrieved cloud optical depth of less than 0.01. The TES cloud optical depth retrievals are used only for screening purposes and no effects of clouds on the radiances are included in the forward model. This initial screening results in over 55 000 potential reference spectra spanning the four year period. Presented is a trend analysis of the time series of the residuals (observation minus calculations in the TES 2B1, 1B2, 2A1, and 1A1 bands which demonstrates that the trend in the residuals is not significantly different from zero over the 4-year period. This is one method used to demonstrate that the relative radiometric calibration is stable over time, which is very important for any longer term analysis of TES retrieved products (L2 particularly well-mixed species such as carbon dioxide and methane.

  14. Japanese Global Precipitation Measurement (GPM) mission status and application of satellite-based global rainfall map

    Science.gov (United States)

    Kachi, Misako; Shimizu, Shuji; Kubota, Takuji; Yoshida, Naofumi; Oki, Riko; Kojima, Masahiro; Iguchi, Toshio; Nakamura, Kenji

    2010-05-01

    As accuracy of satellite precipitation estimates improves and observation frequency increases, application of those data to societal benefit areas, such as weather forecasts and flood predictions, is expected, in addition to research of precipitation climatology to analyze precipitation systems. There is, however, limitation on single satellite observation in coverage and frequency. Currently, the Global Precipitation Measurement (GPM) mission is scheduled under international collaboration to fulfill various user requirements that cannot be achieved by the single satellite, like the Tropical Rainfall Measurement Mission (TRMM). The GPM mission is an international mission to achieve high-accurate and high-frequent rainfall observation over a global area. GPM is composed of a TRMM-like non-sun-synchronous orbit satellite (GPM core satellite) and constellation of satellites carrying microwave radiometer instruments. The GPM core satellite carries the Dual-frequency Precipitation Radar (DPR), which is being developed by the Japan Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT), and microwave radiometer provided by the National Aeronautics and Space Administration (NASA). Development of DPR instrument is in good progress for scheduled launch in 2013, and DPR Critical Design Review has completed in July - September 2009. Constellation satellites, which carry a microwave imager and/or sounder, are planned to be launched around 2013 by each partner agency for its own purpose, and will contribute to extending coverage and increasing frequency. JAXA's future mission, the Global Change Observation Mission (GCOM) - Water (GCOM-W) satellite will be one of constellation satellites. The first generation of GCOM-W satellite is scheduled to be launched in 2011, and it carries the Advanced Microwave Scanning Radiometer 2 (AMSR2), which is being developed based on the experience of the AMSR-E on EOS Aqua satellite

  15. MEASUREMENTS OF ELECTROMAGNETIC ULF FIELD ONBOARD THE MAGION-4 SATELLITE: ULF EXPERIMENT

    Czech Academy of Sciences Publication Activity Database

    Tříska, Pavel; Vojta, Jaroslav; Czapek, Alexandr; Chum, Jaroslav; Teodosiev, D.; Galev, G.; Shibaev, I.

    2003-01-01

    Roč. 17, - (2003), s. 47-53. ISSN 0861-1432 Institutional research plan: CEZ:AV0Z3042911 Keywords : Satellite * measurement * electromagnetic field * ULF Subject RIV: JV - Space Technology http://www.space.bas.bg/astro/eng.html

  16. Mobile satellite propagation measurements and modeling: A review of results for systems engineers

    Science.gov (United States)

    Stutzman, W. L. (Editor); Barts, R. M.; Bostian, C. W.; Butterworth, J. S.; Campbell, R.; Goldhirsh, J.; Vogel, W. J.

    1988-01-01

    An overview of Mobile Satellite System (MSS) propagation measurements and modeling is given, including a summary of results. The simple models presented should be of some use to systems engineers. A complete summary of propagation experiments with literature references is included.

  17. Study of wind speed attenuation at Kavaratti Island using land-based, offshore, and satellite measurements

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Rivankar, P.; Balakrishnan Nair, T.M.B.

    The role of dense coconut palms in attenuating the wind speed at Kavaratti Island, which is located in the southeastern Arabian Sea, is examined based on land-based and offshore wind measurements (U sub(10)) using anchored-buoy-mounted and satellite...

  18. Long-term stability of TES satellite radiance measurements

    Directory of Open Access Journals (Sweden)

    T. C. Connor

    2011-07-01

    Full Text Available The utilization of Tropospheric Emission Spectrometer (TES Level 2 (L2 retrieval products for the purpose of assessing long term changes in atmospheric trace gas composition requires knowledge of the overall radiometric stability of the Level 1B (L1B radiances. The purpose of this study is to evaluate the stability of the radiometric calibration of the TES instrument by analyzing the difference between measured and calculated brightness temperatures in selected window regions of the spectrum. The Global Modeling and Assimilation Office (GMAO profiles for temperature and water vapor and the Real-Time Global Sea Surface Temperature (RTGSST are used as input to the Optimal Spectral Sampling (OSS radiative transfer model to calculate the simulated spectra. The TES reference measurements selected cover a 4-year period of time from mid 2005 through mid 2009 with the selection criteria being; observation latitudes greater than −30° and less than 30°, over ocean, Global Survey mode (nadir view and retrieved cloud optical depth of less than or equal to 0.01. The TES cloud optical depth retrievals are used only for screening purposes and no effects of clouds on the radiances are included in the forward model. This initial screening results in over 55 000 potential reference spectra spanning the four year period. Presented is a trend analysis of the time series of the residuals (observation minus calculations in the TES 2B1, 1B2, 2A1, and 1A1 bands, with the standard deviation of the residuals being approximately equal to 0.6 K for bands 2B1, 1B2, 2A1, and 0.9 K for band 1A1. The analysis demonstrates that the trend in the residuals is not significantly different from zero over the 4-year period. This is one method used to demonstrate that the relative radiometric calibration is stable over time, which is very important for any longer term analysis of TES retrieved products (L2, particularly well-mixed species such as carbon dioxide and methane.

  19. ATM Quality of Service Parameters at 45 Mbps Using a Satellite Emulator: Laboratory Measurements

    Science.gov (United States)

    Ivancic, William D.; Bobinsky, Eric A.

    1997-01-01

    Results of 45-Mbps DS3 intermediate-frequency loopback measurements of asynchronous transfer mode (ATM) quality of service parameters (cell error ratio and cell loss ratio) are presented. These tests, which were conducted at the NASA Lewis Research Center in support of satellite-ATM interoperability research, represent initial efforts to quantify the minimum parameters for stringent ATM applications, such as MPEG-1 and MPEG-2 video transmission. Portions of these results were originally presented to the International Telecommunications Union's ITU-R Working Party 4B in February 1996 in support of their Draft Preliminary Recommendation on the Transmission of ATM Traffic via Satellite.

  20. Measurements of cosmic heavy nuclei on the microbe culture equipment aboard a recoverable satellite

    International Nuclear Information System (INIS)

    The intensities and distributions of the cosmic ray heavy nuclei have been measured by the plastic nuclear track detectors at the microbe culture equipment aboard a recoverable satellite launched in July 1994. The integral intensity of the particles with Z/β larger than 10 is (6.72 +- 0.41) x 10-2 (m-2·s-1·sr-1) inside the equipment. It is found that the particles with Z/β larger than 10 not only enter randomly, but also distribute inhomogeneously inside the satellite

  1. In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea

    Directory of Open Access Journals (Sweden)

    G. Zibordi

    2014-12-01

    Full Text Available The accuracy of primary satellite ocean color data products from the Moderate Resolution Imaging Spectroradiometer on-board Aqua (MODIS-A and the Visible/Infrared Imager/Radiometer Suite (VIIRS, is investigated in the Western Black Sea using in situ measurements from the Gloria site included in the Ocean Color component of the Aerosol Robotic Network (AERONET-OC. The analysis is also extended to an additional well-established AERONET-OC site in the northern Adriatic Sea characterized by optically complex coastal waters exhibiting similarities with those observed at the Gloria site. Results from the comparison of normalized-water leaving radiance LWN indicate biases of a few percent between satellite derived and in situ data at the center-wavelengths relevant for the determination of chlorophyll a concentration (443–547 nm, or equivalent. Remarkable is the consistency among the annual cycle determined with time series of satellite-derived and in situ LWN ratios at these center-wavelengths. Contrarily, the differences between in situ and satellite-derived LWN are pronounced at the blue (i.e., 412 nm and red (i.e., 667 nm, or equivalent center-wavelengths, suggesting difficulties in confidently applying satellite-derived radiometric data from these spectral regions for quantitative analysis in optically complex waters.

  2. Global measurements of sea surface temperature, wind speed and atmospheric water content from satellite microwave radiometry

    Science.gov (United States)

    Njoku, E. G.; Swanson, L.

    1983-01-01

    The Scanning Multichannel Microwave Radiometer (SMMR) was launched on the Seasat and Nimbus 7 satellites in 1978. The SMMR has the ability to measure sea surface temperature and wind speed with the aid of microwaves. In addition, the instrument was designed to measure water vapor and cloud liquid water with better spatial resolution than previous microwave radiometers, and to make sea-ice measurements with higher precision. A description is presented of the results of global analyses of sea surface temperature, wind speed, water vapor, and cloud liquid water, taking into account data provided by the SMMR on the Seasat satellite. It is found that the SMMR data show good self-consistency, and can usefully measure global distributions of sea surface temperatures, surface winds, water vapor, and cloud liquid water.

  3. Origine et dynamique des populations de colza hors des champs

    OpenAIRE

    Deville, A.; Garnier, A.; Lecomte, J; Huet, Sylvie; Roeznholc, Y.; Laredo, Catherine; Emeriau, V.; Merrien, A.; Messean, A.

    2002-01-01

    Dans le cadre de l'introduction de colzas transgéniques dans l'environnement, les populations de colza présentes en bordure de champs (populations hors-champs) sont susceptibles de poser un certain nombre de problèmes de gestion en cas d'échappement du transgène : problème de désherbage dans le cas de colzas résistants aux herbicides, rôle de relais du transgène et persistance de colzas transgéniques après un arrêt éventuel de leur mise en culture. L'estimation de ces risques associés à l'éch...

  4. A novel method for measuring the polarization angle of satellite radio waves

    Science.gov (United States)

    Antoniadis, D. A.

    1974-01-01

    One of the most important parameters for the study of the physics of the ionosphere is the columnar electron content. This can be obtained indirectly by measuring the Faraday rotation of signals emitted from satellites. Many different types of polarimeters have been developed for this purpose. Efforts to develop a new type of polarimeter, suitable for extensive network operation, led to a novel technique for measuring the polarization angle.

  5. Thermospheric zonal mean winds and tides revealed by CHAMP

    OpenAIRE

    Lieberman, R.S.; Akmaev, R. A.; Fuller-Rowell, T. J.; Doornbos, E.

    2013-01-01

    We present direct, global observations of longitudinally averaged CHAMP zonal winds gathered between 2003 and 2007. A diurnal variation dominates the global zonal wind. Westward flows are observed from the early morning through afternoon hours, while eastward flows peak in the evening. A semidiurnal harmonic is also present, with magnitudes that are approximately one third of the diurnal harmonic. The time mean wind indicates westward winds over much of the globe, with weak superrotation (+E,...

  6. NO2 measurements during the MANTRA 2002 balloon campaign: comparisons with satellite measurements, climatology, and the Canadian Middle Atmosphere Model.

    Science.gov (United States)

    Melo, S.; Mantra-Osiris-Sciamachy

    This work reports on the results from the Middle Atmospheric Nitrogen TRend Assessment (MANTRA) balloon campaign conducted at Vanscoy, Saskatchewan, Canada (52°N, 107°W) on September 3 2002. Vertical distributions of ozone and NO2 were measured from the balloon by 3 UV-visible grating spectrometers (SPS, MAESTRO-B, and SAOZ), all in solar occultation mode. Ozone profiles were obtained from ozonesondes launched daily through the campaigns. Another UV-visible spectrometer was operated on the ground measuring scattered sunlight in a zenith-sky configuration. Ozone and NO2 slant column densities were extracted from those measurements as a function of solar zenith angles, and NO2 vertical profiles were retrieved from the NO2 slant column values. Here we compare NO2 profiles measured during the MANTRA campaign with a climatology based on observations from satellites, other balloons, and a set of NDSC sites, as well as with the Canadian Middle Atmosphere Model (CMAM), a fully interactive chemistry-climate model. The results show a good agreement between the measurements, model and the climatology. Thus, in order to account for the NO2 diurnal variation, we use CMAM to compare the NO2 measurements during MANTRA with the measurements done by the OSIRIS instrument onboard the Odin satellite, and by the SCIAMACHY and MIPAS instruments onboard the ENVISAT satellite, over Vanscoy. Since the satellite overpasses did not exactly coincide in time and location with the MANTRA balloon flight, CMAM is a valuable tool making such comparison possible. Such approach is particularly justified during late summer because of low dynamical variability with the stratosphere being largely under photochemical and radiative control.

  7. Using Nighttime Satellite Imagery as a Proxy Measure of Human Well-Being

    Directory of Open Access Journals (Sweden)

    Tilottama Ghosh

    2013-11-01

    Full Text Available Improving human well-being is increasingly recognized as essential for movement toward a sustainable and desirable future. Estimates of different aspects of human well-being, such as Gross Domestic Product, or percentage of population with access to electric power, or measuring the distribution of income in society are often fraught with problems. There are few standardized methods of data collection; in addition, the required data is not obtained in a reliable manner and on a repetitive basis in many parts of the world. Consequently, inter-comparability of the data that does exist becomes problematic. Data derived from nighttime satellite imagery has helped develop various globally consistent proxy measures of human well-being at the gridded, sub-national, and national level. We review several ways in which nighttime satellite imagery has been used to measure the human well-being within nations.

  8. GIM在LEO卫星单频GPS定轨中的应用%The Application of GIM in Precise Orbit Determination for LEO Satellites with Single-frequency GPS Measurements

    Institute of Scientific and Technical Information of China (English)

    彭冬菊; 吴斌

    2012-01-01

    With the availability of precise GPS ephemeris and clock solution, the ionospheric range delay is left as the dominant error sources in the post-processing of space-borne GPS data from single-frequency receivers. Thus, the removal of ionospheric effects is a major prerequisite for an improved orbit reconstruction of LEO satellites equipped with low cost single-frequency GPS receivers. In this paper, the use of Global Ionospheric Maps (GIM) in kinematic and dynamic orbit determination for LEO satellites with single-frequency GPS measurements is discussed first, and then, estimating the scale factor of ionosphere to remove the ionospheric effects in C/A code pseudo-range measurements in both kinematic and adynamia orbit defemination approaches is addressed. As it is known the ionospheric path delay of space-borne GPS signals is strongly dependent on the orbit altitudes of LEO satellites, we selected real space-borne GPS data from CHAMP, GRACE, TerraSAR-X and SAC-C satellites with altitudes between 300 km and 800 km as sample data in this paper. It is demonstrated that the approach of eliminating ionospheric effects in space-borne C/A code pseudo-range by estimating the scale factor of ionosphere is highly effective. Employing this approach, the accuracy of both kinematic and dynamic orbits can be improved notably. Among those five LEO satellites, CHAMP with the lowest orbit altitude has the most remarkable orbit accuracy improvements, which are 55.6% and 47.6% for kinematic and dynamic approaches, respectively. SAC-C with the highest orbit altitude has the least orbit accuracy improvements accordingly, which are 47.8% and 38.2%, respectively.%电离层延迟误差是单频GPS (Global Positioning System)数据最主要的误差源,为提高基于单频GPS数据的LEO (Low Earth Orbiting)卫星定轨精度,必须消除/减弱GPS观测数据中电离层延迟影响.研究了全球电离层模型GIM (Global Ionospheric Maps)在基于单频GPS伪距数据的低轨卫星

  9. Ground-satellite conjugate observations of low-latitude travelling ionospheric disturbances

    Science.gov (United States)

    Ceren Moral, Aysegul; Shiokawa, Kazuo; Otsuka, Yuichi; Suzuki, Shin; Liu, Huixin; Yatini, Clara

    2016-07-01

    Equatorial travelling ionospheric disturbances (TIDs) are studied by using three CHAMP satellite overpasses on ground-based 630-nm airglow images. The airglow images are obtained from Kototabang (KTB), Indonesia (geographic coordinates: 0.2S, 100.3E, geomagnetic latitude: 10.6S). From 7-year data from October 2002 to October 2009, April 30, 2006 (event 1), September 28, 2006 (event 2) and April 12, 2004 (event 3) are the only TID events found in both ground and satellite measurements. They show southward-moving structures in 630-nm airglow images. The events 1 and 2 are single pulse with horizontal scales of ~500-1000 km and event 3 show three wave fronts with horizontal scale sizes of 500-700 km. For events 1 and 3, the neutral density in CHAMP shows out-of-phase variations with the airglow intensity, while event 2 is in-phase. For event 1, the relation between electron density and airglow intensity is out of phase, while relationships of event 2 and 3 are unclear. These unclear relationships suggest that ionospheric plasma variation is not the cause of the TIDs. In the case if gravity waves in the thermosphere is the source of the observed TIDs, in-phase and out-of-phase relationships of neutral density and airglow intensity can be explained by different vertical wavelengths of the gravity wave. We estimate possible vertical wavelengths for those events using observed wave parameters and modeled neutral winds.

  10. Extending comprehensive models of the Earth's magnetic field with Ørsted and CHAMP data

    Science.gov (United States)

    Sabaka, Terence J.; Olsen, Nils; Purucker, Michael E.

    2004-11-01

    A new model of the quiet-time, near-Earth magnetic field has been derived using a comprehensive approach, which includes not only POGO and Magsat satellite data, but also data from the Ørsted and CHAMP satellites. The resulting model shows great improvement over its predecessors in terms of completeness of sources, time span and noise reduction in parameters. With its well separated fields and extended time domain of 1960 to mid-2002, the model is able to detect the known sequence of geomagnetic jerks within this frame and gives evidence for an event of interest around 1997. Because all sources are coestimated in a comprehensive approach, intriguing north-south features typically filtered out with other methods are being discovered in the lithospheric representation of the model, such as the S Atlantic spreading ridge and Andean subduction zone lineations. In addition, this lithospheric field exhibits significantly less noise than previous models as a result of improved data selection. The F-region currents, through which the satellites pass, are now treated as lying within meridional planes, as opposed to being purely radial. Results are consistent with those found previously for Magsat, but an analysis at Ørsted altitude shows exciting evidence that the meridional currents associated with the equatorial electrojet likely close beneath the satellite. Besides the model, a new analysis technique has been developed to infer the portion of a model parameter state resolved by a particular data subset. This has proven very useful in diagnosing the cause of peculiar artefacts in the Magsat vector data, which seem to suggest the presence of a small misalignment bias in the vector magnetometer.

  11. Energetic particle radiations measured by particle detector on board CBERS-1 satellite

    Institute of Scientific and Technical Information of China (English)

    HAO YongQiang; XIAO Zuo; ZOU Hong; ZHANG DongHe

    2007-01-01

    Using the data measured by energetic particle detector on board CBERS-01 and -02 for the past five years, statistics was made to show the general features of MeV electrons and protons along a solar synchronous orbit at an altitude of 780 km. This height is in the bottom region of the Earth's radiation belts. Detectors are inside the satellite cabinet and such continuous monitoring of particle radiation environment inside a satellite has seldom conducted so far. After a proper and careful treatment, it is indicated that the data inside satellite are well correlated with the radiation environment outside. Besides the agreement of the general distribution characteristics of energetic electrons and protons with similar observations from other satellites, attention is particularly paid to the disturbed conditions. Variations of particle fluxes are closely related with solar proton events, in general, electron fluxes of outer belt are well correlated with Dst index after three days' delay while the electron injection occurred almost at the same day during great magnetic storms. It is confirmed that both energetic electrons and protons appear in the Polar Cap region only after the solar proton events.

  12. Measurement of quasi-static and low frequency electric fields on the Viking satellite

    International Nuclear Information System (INIS)

    The instrument for measurement of quasi-static and low frequency (dc and slow varying) electric fields on the Viking satellite is described. The instrument uses three spherical probe pairs to measure the full three-dimensional electric field vector with 18.75 ms time resolution. The probes are kept near plasma potential by means of a controllable bias current. A guard covering part of the booms is biased to a negative voltage to prevent photoelectrons escaping from the probes from reaching the satellite body. Current-voltage sweeps are performed to determine the plasma density and temperature and to select the optimal bias current. The bias currents to the probes and the voltage offset on the guards as well as the current-voltage sweeps are controlled by an on-board microprocessor which can be programmed from the ground and allows great flexibility. (authors)

  13. Coordinated rocket and satellite measurements of an auroral event. II - The rocket observations and analysis

    Science.gov (United States)

    Sharp, W. E.; Rees, M. H.; Stewart, A. I.

    1979-01-01

    A rocket-borne payload launched into an aurora and a simultaneous overpass of the Atmosphere Explorer C satellite yielded measurements of auroral optical emission rates, thermal ion and electron densities, and low-energy electron fluxes. Model calculations of the thermospheric manifestation of the aurora were performed through use of rocket-determined auroral ionization rates and satellite-determined neutral gas densities. Measured oxygen densities provided a means of assessing the quenching rate of an excited state of N2. Energy transfer from this excited state appears to be the major source of 5577-A emission. Optical emission at 6300 A cannot be explained either by electron impact on atomic oxygen or by dissociative recombination of O2(+).

  14. Optimality of incompletely measurable active and passive attitude control systems. [for satellites

    Science.gov (United States)

    Schiehlen, W.; Popp, K.

    1973-01-01

    Passive attitude control systems and active systems with incomplete state measurements are only suboptimal systems in the sense of optimal control theory, since optimal systems require complete state measurements or state estimations. An optimal system, then, requires additional hardware (especially in the case of flexible spacecraft) which results in higher costs. Therefore, it is a real engineering problem to determine how much an optimal system exceeds the suboptimal system, or in other words, what is the suboptimal system's degree of optimality. The problem will be treated in three steps: (1) definition of the degree of optimality for linear, time-invariant systems; (2) a computation method using the quadratic cost functional; (3) application to a gravity-gradient stabilized three-body satellite and a spinning flexible satellite.

  15. Lessons Learned during Thermal Hardware Integration on the Global Precipitation Measurement Satellite

    Science.gov (United States)

    Cottingham, Christine; Dwivedi, Vivek H.; Peters, Carlton; Powers, Daniel; Yang, Kan

    2012-01-01

    The Global Precipitation Measurement mission is a joint NASA/JAXA mission scheduled for launch in late 2013. The integration of thermal hardware onto the satellite began in the Fall of 2010 and will continue through the Summer of 2012. The thermal hardware on the mission included several constant conductance heat pipes, heaters, thermostats, thermocouples radiator coatings and blankets. During integration several problems arose and insights were gained that would help future satellite integrations. Also lessons learned from previous missions were implemented with varying degrees of success. These insights can be arranged into three categories. 1) the specification of flight hardware using analysis results and the available mechanical resources. 2) The integration of thermal flight hardware onto the spacecraft, 3) The preparation and implementation of testing the thermal flight via touch tests, resistance measurements and thermal vacuum testing.

  16. Measurements for satellite validation made from R/V ``Alliance`` during October and November 1991

    Energy Technology Data Exchange (ETDEWEB)

    Minnett, P.J.

    1993-08-01

    Measurements of sea-surface temperature, surface meteorology and atmospheric profiles taken from the R/V Alliance between 1 October and 9 November 1991. During this time the ship sailed from Amsterdam to La Spezia and then was deployed in the western Mediterranean Sea. The measurements are presented in graphical form, and daily statistics are given as tables. True winds, net long-wave radiation and turbulent air-sea fluxes have been calculated and are also presented. The measurements were made for application to studies of the accuracies of the retrieval of sea-surface temperature and atmospheric precipitable water from satellite radiometers.

  17. The deduction of in-track winds from satellite measurements of density and composition

    International Nuclear Information System (INIS)

    A method is proposed for obtaining the in-track wind component by exploiting the different ways in which two satellite-borne instruments interact with the airstream. It makes possible the completion of the three-dimensional wind vector from measurements which yield at most two components. This is especially important during geomagnetic storms when winds can cause serious errors in density measurements made by a single instrument. The method can be used to retrieve valuable information from existing data bases which contain measurements by three-axis accelerometers and chambered instruments such as closed-source mass spectrometers or pressure gages

  18. EHL Transition Temperature Measurements on a Geostationary Operational Environmental Satellite (GOES) Filter Wheel Bearing

    Science.gov (United States)

    Jansen, Mark J.; Jones, William R., Jr.; Pepper, Stephen V.; Predmore, Roamer E.; Shogrin, Bradley A.

    2001-01-01

    The elastohydrodynamic lubrication (EHL) transition temperature was measured for a Geostationary Operational Environmental Satellite (GOES) sounder filter wheel bearing in a vacuum tribometer. Conditions included both an 89 N (20 lb.) hard and soft load, 600 rpm, temperatures between 23 C (73 F) and 85 C (185 F), and a vacuum of approximately 1.3 x 10(exp -5) Pa. Elastohydrodynamic to mixed lubrication started to occur at approximately 70 C (158 F).

  19. Night sky brightness at sites from DMSP-OLS satellite measurements

    OpenAIRE

    Cinzano, Pierantonio; Elvidge, Cristopher D.

    2004-01-01

    We apply the sky brightness modelling technique introduced and developed by Roy Garstang to high-resolution DMSP-OLS satellite measurements of upward artificial light flux and to GTOPO30 digital elevation data in order to predict the brightness distribution of the night sky at a given site in the primary astronomical photometric bands for a range of atmospheric aerosol contents. This method, based on global data and accounting for elevation, Earth curvature and mountain screening, allows the ...

  20. Climatologies from satellite measurements: the impact of orbital sampling on the standard error of the mean

    Directory of Open Access Journals (Sweden)

    M. Toohey

    2013-04-01

    Full Text Available Climatologies of atmospheric observations are often produced by binning measurements according to latitude and calculating zonal means. The uncertainty in these climatological means is characterised by the standard error of the mean (SEM. However, the usual estimator of the SEM, i.e., the sample standard deviation divided by the square root of the sample size, holds only for uncorrelated randomly sampled measurements. Measurements of the atmospheric state along a satellite orbit cannot always be considered as independent because (a the time-space interval between two nearest observations is often smaller than the typical scale of variations in the atmospheric state, and (b the regular time-space sampling pattern of a satellite instrument strongly deviates from random sampling. We have developed a numerical experiment where global chemical fields from a chemistry climate model are sampled according to real sampling patterns of satellite-borne instruments. As case studies, the model fields are sampled using sampling patterns of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS and Atmospheric Chemistry Experiment Fourier-Transform Spectrometer (ACE-FTS satellite instruments. Through an iterative subsampling technique, and by incorporating information on the random errors of the MIPAS and ACE-FTS measurements, we produce empirical estimates of the standard error of monthly mean zonal mean model O3 in 5° latitude bins. We find that generally the classic SEM estimator is a conservative estimate of the SEM, i.e., the empirical SEM is often less than or approximately equal to the classic estimate. Exceptions occur only when natural variability is larger than the random measurement error, and specifically in instances where the zonal sampling distribution shows non-uniformity with a similar zonal structure as variations in the sampled field, leading to maximum sensitivity to arbitrary phase shifts between the sample distribution and

  1. Towards validation of ammonia (NH3 measurements from the IASI satellite

    Directory of Open Access Journals (Sweden)

    M. Van Damme

    2014-12-01

    Full Text Available Limited availability of ammonia (NH3 observations is currently a barrier for effective monitoring of the nitrogen cycle. It prevents a full understanding of the atmospheric processes in which this trace gas is involved and therefore impedes determining its related budgets. Since the end of 2007, the Infrared Atmospheric Sounding Interferometer (IASI satellite has been observing NH3 from space at a high spatiotemporal resolution. This valuable data set, already used by models, still needs validation. We present here a first attempt to validate IASI-NH3 measurements using existing independent ground-based and airborne data sets. The yearly distributions reveal similar patterns between ground-based and space-borne observations and highlight the scarcity of local NH3 measurements as well as their spatial heterogeneity and lack of representativity. By comparison with monthly resolved data sets in Europe, China and Africa, we show that IASI-NH3 observations are in fair agreement but that they are characterized by a smaller variation in concentrations. The use of hourly and airborne data sets to compare with IASI individual observations allows to investigate the impact of averaging as well as the representativity of independent observations for the satellite footprint. The importance of considering the latter and the added value of densely located airborne measurements at various altitudes to validate IASI-NH3 columns are discussed. Perspectives and guidelines for future validation work on NH3 satellite observations are presented.

  2. Computer-aided evaluation of the railway track geometry on the basis of satellite measurements

    Science.gov (United States)

    Specht, Cezary; Koc, Władysław; Chrostowski, Piotr

    2016-05-01

    In recent years, all over the world there has been a period of intensive development of GNSS (Global Navigation Satellite Systems) measurement techniques and their extension for the purpose of their applications in the field of surveying and navigation. Moreover, in many countries a rising trend in the development of rail transportation systems has been noticed. In this paper, a method of railway track geometry assessment based on mobile satellite measurements is presented. The paper shows the implementation effects of satellite surveying railway geometry. The investigation process described in the paper is divided on two phases. The first phase is the GNSS mobile surveying and the analysis obtained data. The second phase is the analysis of the track geometry using the flat coordinates from the surveying. The visualization of the measured route, separation and quality assessment of the uniform geometric elements (straight sections, arcs), identification of the track polygon (main directions and intersection angles) are discussed and illustrated by the calculation example within the article.

  3. Detection of the plasma density irregularities in the topside ionosphere with GPS measurements onboard Swarm satellites

    Science.gov (United States)

    Zakharenkova, Irina; Cherniak, Iurii

    2016-07-01

    We present new results on the detection of the topside ionospheric irregularities/plasma bubbles using GPS measurements from Precise Orbit Determination (POD) GPS antenna onboard Low Earth Orbit (LEO) satellites. For this purpose we analyze the GPS measurements onboard the ESA's constellation mission Swarm, consisted of three identical satellites with orbit altitude of 450-550 km. We demonstrate that LEO GPS can be an effective tool for monitoring the occurrence of the topside ionospheric irregularities and may essentially contribute to the multi-instrumental analysis of the ground-based and in situ data. In the present study we analyze the occurrence and global distribution of the equatorial ionospheric irregularities during post-sunset period. To support our observations and conclusions, we involve into our analysis in situ plasma density provided by Swarm constellation. Joint analysis of the Swarm GPS and in situ measurements allows us to estimate the occurrence rate of the topside ionospheric irregularities during 2014-2015. The obtained results demonstrate a high degree of similarities in the occurrence pattern of the seasonal and longitudinal distribution of the topside ionospheric irregularities derived on both types of the satellite observations. This work was partially funded by RFBR according to the research project No.16-05-01077 a.

  4. The absolute gravity measurement by FG5 gravimeter at Great Wall Station, Antarctica

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Gravity measurement is of great importance to the height datum in Antarctica.The absolute gravity measurement was carried out at Great Wall Station, Antarctica, using FG5 absolute gravity instrument.The gravity data was processed with corrections of earth tide, ocean tide, polar motion and the atmospher, and the RMS is within +3 x 10 -s ms-2.The vertical and horizontal gravity gradients were measured using 2 LaCoaste & Romberg (LCR) gravimeters.The absolute gravity measurement provides the fundamental data for the validation and calibration of the satellite gravity projects such as CHAMP, GRACE and GOCE, and for the high accuracy geoid model.

  5. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Current Technical Performance Measures

    Science.gov (United States)

    Cochran, S.; Panas, M.; Jamilkowski, M. L.; Miller, S. W.

    2015-12-01

    ABSTRACT The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The Joint Polar Satellite System will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a multi-mission enterprise system serving NOAA, NASA and their national and international partners. The CGS has demonstrated its scalability and flexibility to incorporate multiple missions efficiently and with minimal cost, schedule and risk, while strengthening global partnerships in weather and environmental monitoring. The CGS architecture is being upgraded to Block 2.0 in 2015 to "operationalize" S-NPP, leverage lessons learned to date in multi-mission support, take advantage of more reliable and efficient technologies, and satisfy new requirements and constraints in the continually evolving budgetary environment. To ensure the CGS meets these needs, we have developed 49 Technical Performance Measures (TPMs) across 10 categories, such as data latency, operational availability and scalability. This paper will provide an overview of the CGS Block 2.0 architecture, with particular focus on the 10 TPM categories listed above. We will provide updates on how we ensure the deployed architecture meets these TPMs to satisfy our multi-mission objectives with the deployment of Block 2.0.

  6. Application of Vision Metrology to In-Orbit Measurement of Large Reflector Onboard Communication Satellite for Next Generation Mobile Satellite Communication

    Science.gov (United States)

    Akioka, M.; Orikasa, T.; Satoh, M.; Miura, A.; Tsuji, H.; Toyoshima, M.; Fujino, Y.

    2016-06-01

    Satellite for next generation mobile satellite communication service with small personal terminal requires onboard antenna with very large aperture reflector larger than twenty meters diameter because small personal terminal with lower power consumption in ground base requires the large onboard reflector with high antenna gain. But, large deployable antenna will deform in orbit because the antenna is not a solid dish but the flexible structure with fine cable and mesh supported by truss. Deformation of reflector shape deteriorate the antenna performance and quality and stability of communication service. However, in case of digital beam forming antenna with phased array can modify the antenna beam performance due to adjustment of excitation amplitude and excitation phase. If we can measure the reflector shape precisely in orbit, beam pattern and antenna performance can be compensated with the updated excitation amplitude and excitation phase parameters optimized for the reflector shape measured every moment. Softbank Corporation and National Institute of Information and Communications Technology has started the project "R&D on dynamic beam control technique for next generation mobile communication satellite" as a contracted research project sponsored by Ministry of Internal Affairs and Communication of Japan. In this topic, one of the problem in vision metrology application is a strong constraints on geometry for camera arrangement on satellite bus with very limited space. On satellite in orbit, we cannot take many images from many different directions as ordinary vision metrology measurement and the available area for camera positioning is quite limited. Feasibility of vision metrology application and general methodology to apply to future mobile satellite communication satellite is to be found. Our approach is as follows: 1) Development of prototyping simulator to evaluate the expected precision for network design in zero order and first order 2) Trial

  7. Contribution to development of SPNDs for instantaneous and selective measurement of different radiation fields in nuclear reactors; Contribution au developpement de collectrons pour la mesure instantanee et selective des differents champs de rayonnements en reacteurs nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Blandin, Christophe [Institut National Polytechnique, 38 - Grenoble (France)

    1998-02-20

    The objective of this work was conceiving and experimentally optimizing the SPNDs (Self-Powdered Neutron Detector) able to control fast power transients in test reactors and also to cope with requirements of surveillanceand protection of EDF reactors. Thus, different SPND emitters of platinum, gadolinium, hafnium and cobalt were provided according to their nature with sheathing and stainless steel plugs as well as with zirconium over-sheathing in order to render them faster, more selective and adapted for wear checking. Special experimental devices were designed for measuring inside the Siloe reactor the promptness of the signals from SPND, on one hand, and their sensitivity to thermal and epithermal neutrons as well as to gamma rays, on the other hand. The follow-up of power transients in test reactors is ensured by the instantaneous measurement of thermal and epithermal neutron flux as well as of gamma field by means of three special SPND with gadolinium, hafnium and platinum. Also, we have defined the characteristics of a new SPND with cobalt, that delivers a current of unique neutronic origin, able to ensure the surveillance and protection of a power reactor over a period of at least six years.

  8. The retrieval of cloud microphysical properties using satellite measurements and an in situ database

    Directory of Open Access Journals (Sweden)

    Christophe Poix

    Full Text Available By combining AVHRR data from the NOAA satellites with information from a database of in situ measurements, large-scale maps can be generated of the microphysical parameters most immediately significant for the modelling of global circulation and climate. From the satellite data, the clouds can be classified into cumuliform, stratiform and cirrus classes and then into further sub-classes by cloud top temperature. At the same time a database of in situ measurements made by research aircraft is classified into the same sub-classes and a statistical analysis is used to derive relationships between the sub-classes and the cloud microphysical properties. These two analyses are then linked to give estimates of the microphysical properties of the satellite observed clouds. Examples are given of the application of this technique to derive maps of the probability of occurrence of precipitating clouds and of precipitating water content derived from a case study within the International Cirrus Experiment (ICE held in 1989 over the North Sea.

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

    Science.gov (United States)

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

    2016-02-01

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

  10. First results of measurements of extreme ultraviolet radiation onboard a geostationary satellite "ELECTRO-L"

    Science.gov (United States)

    Nusinov, Anatoliy; Kazachevskaya, Tamara; Gonjukh, David

    Measurements of the intensity of EUV emission in the hydrogen Lyman-alpha line were conducted by a broadband photometer VUSS-E onboard geostationary Hydrometeorological satellite "Electro" since March 2011. The solar hydrogen Lyman-alpha line (lambda = 121.6 nm) was monitored. The photomultiplier with LiF window used as a detector insensitive to visible light. Long-wavelength limit of the spectral band sensitivity of the instrument is about 200 nm, so the signal of the device is defined as the flux of solar radiation in the region of 123-200 nm. Its exclusion was carried out by calculation. Since the satellite "Electro" designed for remote sensing of the Earth, its line of sight focused on Earth. Alignment of instrument in the Sun direction was achieved by installing it on the solar panel, periodically moved in the solar direction. Correction of instrument readings, reduced due to the deviation of its axis from the Sun direction, carried out by calculation. Measurements were carried out every second. The first results of the measurements are presented. The difference in absolute calibration Electro-L/VUSS-E is within 5% of corresponding values for measurements TIMED satellite in those days, that is in agreement with laboratory calibrations. It is useful to measure the temperature of the instrument, as its variation on a small interval of time makes change the value of the output signal about 1-2 %. During first year of operation, the sensitivity of the apparatus remained within ± 2% of measured value, significant degradation of sensitivity was not observed. Over time of observation there have been several large flares of X class. The increase of the signal in the ultraviolet range does not exceed a few percent during these flares.

  11. Distribution and composition of suspended particulate matter in the Atlantic Ocean: Direct measurements and satellite data

    Science.gov (United States)

    Lisitzin, A. P.; Klyuvitkin, A. A.; Burenkov, V. I.; Kravchishina, M. D.; Politova, N. V.; Novigatsky, A. N.; Shevchenko, V. P.; Klyuvitkina, T. S.

    2016-01-01

    The main purpose of this work is to study the real distribution and spatial-temporal variations of suspended particulate matter and its main components in surface waters of the Atlantic Ocean on the basis of direct and satellite measurements for development of new and perfection of available algorithms for converting satellite data. The distribution fields of suspended particulate matter were calculated and plotted for the entire Atlantic Ocean. It is established that its distribution in the open ocean is subordinate to the latitudinal climatic zonality. The areas with maximum concentrations form latitudinal belts corresponding to high-productivity eutrophic and mesotrophic waters of the northern and southern temperate humid belts and with the equatorial humid zone. Phytoplankton, the productivity of which depends primarily on the climatic zonality, is the main producer of suspended particulate matter in the surface water layer.

  12. Secular Gravity Gradients in Non-Dynamical Chern-Simons Modified Gravity for Satellite Gradiometry Measurements

    CERN Document Server

    Qiang, Li-E

    2016-01-01

    With continuous advances in related technologies, relativistic gravitational experiments with orbiting gradiometers becomes feasible, which could naturally be incorporated into future satellite gravity missions. Tests of Chern-Simons modified gravity are meaningful since such a modification gives us insights into (possible) parity-violations in gravitation. In this work, we derive, at the post-Newtonian level, the new observables of secular gradients from the non-dynamical Chern-Simons modified gravity, which will greatly improve the constraint on the mass scale $M_{CS}$ that may be drawn from satellite gradiometry measurements. For superconducting gradiometers, a strong bound $M_{CS}\\geq 10^{-7}\\ eV$ could in principle be obtained. For future optical gradiometers based on similar technologies from the LISA PathFinder mission, a even stronger bound $M_{CS}\\geq 10^{-5}\\ eV$ might be expected.

  13. Ionizing radiation fluxes and dose measurements during the Kosmos 1887 satellite flight.

    Science.gov (United States)

    Charvat, J; Spurny, F; Kopecka, B; Votockova, I

    1990-01-01

    The results of dosimetric experiments performed during the flight of Kosmos 1887 biosatellite are presented. Two kinds of measurements were performed on the external surface of the satellite. First, the fluences and spectra of low energy charged particles were established. It was found that most of the particles registered by means of solid state nuclear track detectors are helium nuclei. Tracks of oxygen nuclei and some heavier charged particles were also observed. Thermoluminescent detectors were used to establish absorbed doses in open space on the satellite's surface and behind thin shielding. It was found that these doses were rather high; nevertheless, their decrease with shielding thickness is very rapid. Dosimetric and other consequences of the results obtained are analyzed and discussed. PMID:11537509

  14. Absorbed dose measurements on external surface of Kosmos-satellites with glass thermoluminescent detectors.

    Science.gov (United States)

    Akatov YuA; Arkhangelsky, V V; Kovalev, E E; Spurny, F; Votochkova, I

    1989-01-01

    In this paper we present absorbed dose measurements with glass thermoluminescent detectors on external surface of satellites of Kosmos-serie flying in 1983-87. Experiments were performed with thermoluminescent aluminophosphate glasses of thicknesses 0.1, 0.3, 0.4, 0.5, and 1 mm. They were exposed in sets of total thickness between 5 and 20 mm, which were protected against sunlight with thin aluminized foils. In all missions, extremely high absorbed dose values were observed in the first layers of detectors, up to the thickness of 0.2 to 0.5 gcm-2. These experimental results confirm that, during flights at 250 to 400 km, doses on the surface of the satellites are very high, due to the low energy component of the proton and electron radiation. PMID:11537297

  15. Ionizing radiation fluxes and dose measurements during the Kosmos 1887 satellite flight

    International Nuclear Information System (INIS)

    The results of dosimetric experiments performed during the flight of Kosmos 1887 biosatellite are presented. Two kinds of measurements were performed on the external surface of the satellite. First, the fluences and spectra of low energy charged particles were established. It was found that most of the particles registered by means of solid state nuclear track detectors are helium nuclei. Tracks of oxygen nuclei and some heavier charged particles were also observed. Thermoluminescent detectors were used to establish absorbed doses in open space on the satellite's surface and behind thin shielding. It was found that these doses were rather high; nevertheless, their decrease with shielding thickness is very rapid. Dosimetric and other consequences of the results obtained are analyzed and discussed. (author)

  16. Quantum-limited measurements of optical signals from a geostationary satellite

    CERN Document Server

    Günthner, Kevin; Elser, Dominique; Stiller, Birgit; Bayraktar, Ömer; Müller, Christian R; Saucke, Karen; Tröndle, Daniel; Heine, Frank; Seel, Stefan; Greulich, Peter; Zech, Herwig; Gütlich, Björn; Richter, Ines; Lutzer, Michael; Philipp-May, Sabine; Meyer, Rolf; Marquardt, Christoph; Leuchs, Gerd

    2016-01-01

    The measurement of quantum signals that traveled through long distances is of fundamental and technical interest. We present quantum-limited coherent measurements of optical signals, sent from a satellite in geostationary Earth orbit to an optical ground station. We bound the excess noise that the quantum states could have acquired after having propagated 38600 km through Earth's gravitational potential as well as its turbulent atmosphere. Our results indicate that quantum communication is feasible in principle in such a scenario, highlighting the possibility of a global quantum key distribution network for secure communication.

  17. Fertilisation de la courge de plein champ en AB

    OpenAIRE

    Vedie, Hélène

    2009-01-01

    Un essai fertilisation comparant différentes doses d'azote total apportées (0-50-100-150 unités/ha) et 2 formes d'engrais organique(tourteau de ricin et Orga 6)a été conduit en plein champ pendant l'été 2009. Les résultats montrent que l'optimum agronomique et économique de cet essai est de 100 unités/ha apportées avec le tourteau de ricin, qui s'avère plus efficient que l'autre engrais testé.

  18. Improved Forest Biomass and Carbon Estimations Using Texture Measures from WorldView-2 Satellite Data

    Directory of Open Access Journals (Sweden)

    Sandra Eckert

    2012-03-01

    Full Text Available Accurate estimation of aboveground biomass and carbon stock has gained importance in the context of the United Nations Framework Convention on Climate Change (UNFCCC and the Kyoto Protocol. In order to develop improved forest stratum–specific aboveground biomass and carbon estimation models for humid rainforest in northeast Madagascar, this study analyzed texture measures derived from WorldView-2 satellite data. A forest inventory was conducted to develop stratum-specific allometric equations for dry biomass. On this basis, carbon was calculated by applying a conversion factor. After satellite data preprocessing, vegetation indices, principal components, and texture measures were calculated. The strength of their relationships with the stratum-specific plot data was analyzed using Pearson’s correlation. Biomass and carbon estimation models were developed by performing stepwise multiple linear regression. Pearson’s correlation coefficients revealed that (a texture measures correlated more with biomass and carbon than spectral parameters, and (b correlations were stronger for degraded forest than for non-degraded forest. For degraded forest, the texture measures of Correlation, Angular Second Moment, and Contrast, derived from the red band, contributed to the best estimation model, which explained 84% of the variability in the field data (relative RMSE = 6.8%. For non-degraded forest, the vegetation index EVI and the texture measures of Variance, Mean, and Correlation, derived from the newly introduced coastal blue band, both NIR bands, and the red band, contributed to the best model, which explained 81% of the variability in the field data (relative RMSE = 11.8%. These results indicate that estimation of tropical rainforest biomass/carbon, based on very high resolution satellite data, can be improved by (a developing and applying forest stratum–specific models, and (b including textural information in addition to spectral information.

  19. Error Vector Magnitude (EVM) Measurement to Characterize Tracking and Data Relay Satellite (TDRS) Channel Impairment

    Science.gov (United States)

    Mebratu, Derssie; Kegege, Obadiah; Shaw, Harry

    2016-01-01

    Digital signal transmits via a carrier wave, demodulates at a receiver and locates an ideal constellation position. However, a noise distortion, carrier leakage and phase noise divert an actual constellation position of a signal and locate to a new position. In order to assess a source of noise and carrier leakage, Bit Error Rate (BER) measurement technique is also used to evaluate the number of erroneous bit per bit transmitted signal. In addition, we present, Error Vector Magnitude (EVM), which measures an ideal and a new position, assesses a source of signal distortion, and evaluates a wireless communication system's performance with a single metric. Applying EVM technique, we also measure the performance of a User Services Subsystem Component Replacement (USSCR) modem. Furthermore, we propose EVM measurement technique in the Tracking and Data Relay Satellite system (TDRS) to measure and evaluate a channel impairment between a ground (transmitter) and the terminal (receiver) at White Sands Complex.

  20. Subpixel Accuracy Analysis of Phase Correlation Shift Measurement Methods Applied to Satellite Imagery

    Directory of Open Access Journals (Sweden)

    S.M. Badwai

    2013-01-01

    Full Text Available the key point of super resolution process is the accurate measuring of sub-pixel shift. Any tiny error in measuring such shift leads to an incorrect image focusing. In this paper, methodology of measuring sub-pixel shift using Phase correlation (PC are evaluated using different window functions, then modified version of (PC method using high pass filter (HPF is introduced . Comprehensive analysis and assessment of (PC methods shows that different natural features yield different shift measurements. It is concluded that there is no universal window function for measuring shift; it mainly depends on the features in the satellite images. Even the question of which window is optimal of particular feature is generally remains open. This paper presents the design of a method for obtaining high accuracy sub pixel shift phase correlation using (HPF.The proposed method makes the change in the different locations that lack of edges easy.

  1. Feasible groundbased atmospheric and flux measurements by developing countries in support of satellite data

    Science.gov (United States)

    Mitra, A. P.

    To allow increasing participation of developing countries in global change studies, ground based measurement systems which can be easily comissioned and provide support to satellite observations so as to fit into global mapping need to be chosen carefully. Those relating to atmospheric parameters (greenhouse gas concentrations, emission fluxes, transport properties, etc.) are discussed here. The simplest and of most immediate interest relate to sources and sinks of CH_4 (primarily from rice paddy fields, animals, wetlands) and N_2O (soils, oceans). Measurement techniques and inter-country campaign plans are discussed. There are also important possibilities of using the same technique for measurements of emissions from biomass burning alongwith ozone measurements coupled with survey of biomass burning areas from satellites. Another major area concerns the proposed ITYO programme (International Tropospheric Ozone Year), for which, apart from balloon ozone ascents, use of UV-B radiometry at selected wavelengths is considered. The third area discussed concerns measurements of atmospheric aerosols using Multi-wavelength Radiometer (MWR). In addition, in the last few years, a number of advanced groundlevel systems have been installed at low latitudes, which, if made available widely to developing country scientists, and their participation supported financially, could provide a major opportunity for world class research. These include: the MST radar at Tirupati (India) Chung-Li (Taiwan) and Arecibo, Puerto Rico; the Lidars at Thumba and at Natal, Brazil; and the Laser Heterodyning System and mm-wave radiospectrometer at Delhi.

  2. Understanding data noise in gravity field recovery on the basis of inter-satellite ranging measurements acquired by the satellite gravimetry mission GRACE

    Science.gov (United States)

    Ditmar, Pavel; Teixeira da Encarnação, João; Hashemi Farahani, Hassan

    2012-06-01

    Spectral analysis of data noise is performed in the context of gravity field recovery from inter-satellite ranging measurements acquired by the satellite gravimetry mission GRACE. The motivation of the study is two-fold: (i) to promote a further improvement of GRACE data processing techniques and (ii) to assist designing GRACE follow-on missions. The analyzed noise realizations are produced as the difference between the actual GRACE inter-satellite range measurements and the predictions based on state-of-the-art force models. The exploited functional model is based on the so-called "range combinations," which can be understood as a finite-difference analog of inter-satellite accelerations projected onto the line-of-sight connecting the satellites. It is shown that low-frequency noise is caused by limited accuracy of the computed GRACE orbits. In the first instance, it leads to an inaccurate estimation of the radial component of the inter-satellite velocities. A large impact of this component stems from the fact that it is directly related to centrifugal accelerations, which have to be taken into account when the measured range-accelerations are linked with inter-satellite accelerations. Another effect of orbit inaccuracies is a miscalculation of forces acting on the satellites (particularly, the one described by the zero-degree term of the Earth's gravitational field). The major contributors to the noise budget at high frequencies (above 9 mHz) are (i) ranging sensor errors and (ii) limited knowledge of the Earth's static gravity field at high degrees. Importantly, we show that updating the model of the static field on the basis of the available data must be performed with a caution as the result may not be physical due to a non-unique recovery of high-degree coefficients. The source of noise in the range of intermediate frequencies (1-9 mHz), which is particularly critical for an accurate gravity field recovery, is not fully understood yet. We show, however, that

  3. Global gravity wave activity in the tropopause region from CHAMP radio occultation data

    Science.gov (United States)

    Schmidt, T.; de la Torre, A.; Wickert, J.

    2008-08-01

    We discuss the global gravity wave (GW) activity expressed by the specific potential energy in the altitude range from 5 km below to 10 km above the tropopause, derived from GPS radio occultation data from CHAMP (2001-2008). The GW analysis is based on vertical detrending of the individual measured temperature profiles by applying a Gaussian filter in two different ways: (i) filtering of the complete temperature profiles and (ii) separate filtering of the profiles for the tropospheric and lower stratospheric parts. The separate filtering method significantly reduces the usually observed wave activity enhancement in the tropopause region which highly depends on the performance of the complete filtering method to reproduce the change in the temperature gradient at the tropopause. We only consider vertical wavelengths less than 10 km. The global mean potential energy in the tropopause region deduced with these different background temperatures will be analyzed, differences will be emphasized and possible error sources of the new method will be considered.

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

    Directory of Open Access Journals (Sweden)

    S. Sharma

    2015-11-01

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

  5. Estimation of snow cover distribution in Beas basin, Indian Himalaya using satellite data and ground measurements

    Indian Academy of Sciences (India)

    H S Negi; A V Kulkarni; B S Semwal

    2009-10-01

    In the present paper,a methodology has been developed for the mapping of snow cover in Beas basin,Indian Himalaya using AWiFS (IRS-P6)satellite data.The complexities in the mapping of snow cover in the study area are snow under vegetation,contaminated snow and patchy snow. To overcome these problems,field measurements using spectroradiometer were carried out and reflectance/snow indices trend were studied.By evaluation and validation of different topographic correction models,it was observed that,the normalized difference snow index (NDSI)values remain constant with the variations in slope and aspect and thus NDSI can take care of topography effects.Different snow cover mapping methods using snow indices are compared to find the suitable mapping technique.The proposed methodology for snow cover mapping uses the NDSI (estimated using planetary re flectance),NIR band reflectance and forest/vegetation cover information.The satellite estimated snow or non-snow pixel information using proposed methodology was validated with the snow cover information collected at three observatory locations and it was found that the algorithm classify all the sample points correctly,once that pixel is cloud free.The snow cover distribution was estimated using one year (2004 –05)cloud free satellite data and good correlation was observed between increase/decrease areal extent of seasonal snow cover and ground observed fresh snowfall and standing snow data.

  6. Electron precipitation burst in the nighttime slot region measured simultaneously from two satellites

    International Nuclear Information System (INIS)

    Based on data acquired in 1982 with the Stimulated Emission of Energetic Particles payload on the low-altitude (170--280 km) S81-1 spacecraft and the Space Environment Monitor instrumentation on the NOAA 6 satellite (800--830 km), a study has been made of short-duration nighttime electron precipitation bursts at L = 2.0--35. From 54 passes of each satellite across the slot region simultaneously in time, 21 bursts were observed on the NOAA 6 spacecraft, and 76 on the S81-1 satellite. Five events, probably associated with lightning, were observed simultaneously from the two spacecraft within 1.2 s, providing a measure of the spatial extent of the bursts. This limited sample indicates that the intensity of precipitation events falls off with width in longitude and L shell but individual events extend as much as 50 in invariant latitude and 430 in longitude. The number of events above a given flux observed in each satellite was found to be approximately inversely proportional to the flux. The time average energy input to the atmosphere over the longitude range 180 0E to 360 0E at a local time of 2230 directly from short-duration bursts spanning a wide range of intensity enhancements was estimated to be about 6 x 10/sup -6/ ergs/cm2 s in the northern hemisphere and about 1.5 x 10/sup -5/ ergs/cm2 s in the southern hemisphere. In the south, this energy precipitation rate is lower than that from electrons in the drift loss cone by about 2 orders of magnitude. However, on the basis of these data alone we cannot discount weak bursts from being a major contributor to populating the drift loss cone with electrons which ultimately precipitate into the atmosphere. copyrightAmerican Geophysical Union 1987

  7. Global Carbon Monoxide Products from Combined AIRS, TES and MLS Measurements on A-Train Satellites

    Science.gov (United States)

    Warner, Juying X.; Yang, R.; Wei, Z.; Carminati, F.; Tangborn, A.; Sun, Z.; Lahoz, W.; Attie, J. L.; El Amraoui, L.; Duncan, B.

    2014-01-01

    This study tests a novel methodology to add value to satellite data sets. This methodology, data fusion, is similar to data assimilation, except that the background modelbased field is replaced by a satellite data set, in this case AIRS (Atmospheric Infrared Sounder) carbon monoxide (CO) measurements. The observational information comes from CO measurements with lower spatial coverage than AIRS, namely, from TES (Tropospheric Emission Spectrometer) and MLS (Microwave Limb Sounder). We show that combining these data sets with data fusion uses the higher spectral resolution of TES to extend AIRS CO observational sensitivity to the lower troposphere, a region especially important for air quality studies. We also show that combined CO measurements from AIRS and MLS provide enhanced information in the UTLS (upper troposphere/lower stratosphere) region compared to each product individually. The combined AIRS-TES and AIRS-MLS CO products are validated against DACOM (differential absorption mid-IR diode laser spectrometer) in situ CO measurements from the INTEX-B (Intercontinental Chemical Transport Experiment: MILAGRO and Pacific phases) field campaign and in situ data from HIPPO (HIAPER Pole-to-Pole Observations) flights. The data fusion results show improved sensitivities in the lower and upper troposphere (20-30% and above 20%, respectively) as compared with AIRS-only version 5 CO retrievals, and improved daily coverage compared with TES and MLS CO data.

  8. REKF and RUKF for pico satellite attitude estimation in the presence of measurement faults

    Institute of Scientific and Technical Information of China (English)

    Halil Ersin Söken; Chingiz Hajiyev

    2014-01-01

    When a pico satel ite is under normal operational condi-tions, whether it is extended or unscented, a conventional Kalman filter gives sufficiently good estimation results. However, if the measurements are not reliable because of any kind of malfunc-tions in the estimation system, the Kalman filter gives inaccurate results and diverges by time. This study compares two different robust Kalman filtering algorithms, robust extended Kalman filter (REKF) and robust unscented Kalman filter (RUKF), for the case of measurement malfunctions. In both filters, by the use of de-fined variables named as the measurement noise scale factor, the faulty measurements are taken into the consideration with a smal weight, and the estimations are corrected without affecting the characteristic of the accurate ones. The proposed robust Kalman filters are applied for the attitude estimation process of a pico satel-lite, and the results are compared.

  9. Regles de fusion en theorie des champs conformes

    Science.gov (United States)

    Begin, Luc

    1999-10-01

    Les théories de champs conformes constituent un domaine de recherche très actif avec de nombreuses applications en physique statistique, en matière condensée, en théorie des cordes, en mathématiques, etc. Nous analysons ici le calcul des règles de fusion dans les modèles Wess- Zumino-Witten par des méthodes positives. Les règles de fusion sont des quantités importantes puisqu'elles indiquent comment se combinent les champs primaires de la théorie. L'approche présentée est basée sur l'hypothèse que les règles de fusion sont décrites par un système d'inéquations linéaire et homogène et mène au concept original de «base de fusion». Cette approche simple et générale permet d'utiliser les méthodes combinatoires et de programmation linéaire pour construire les fonctions génératrices et les bases de fusion. Cette méthode permet d'obtenir des résultats originaux et explicites pour les algèbres su (3), su (4) et sp (4).

  10. Retrieval of ozone column content from airborne Sun photometer measurements during SOLVE II: comparison with coincident satellite and aircraft measurements

    Directory of Open Access Journals (Sweden)

    J. M. Livingston

    2005-01-01

    Full Text Available During the 2003 SAGE (Stratospheric Aerosol and Gas Experiment III Ozone Loss and Validation Experiment (SOLVE II, the fourteen-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14 was mounted on the NASA DC-8 aircraft and measured spectra of total and aerosol optical depth (TOD and AOD during the sunlit portions of eight science flights. Values of ozone column content above the aircraft have been derived from the AATS-14 measurements by using a linear least squares method that exploits the differential ozone absorption in the seven AATS-14 channels located within the Chappuis band. We compare AATS-14 columnar ozone retrievals with temporally and spatially near-coincident measurements acquired by the SAGE III and the Polar Ozone and Aerosol Measurement (POAM III satellite sensors during four solar occultation events observed by each satellite. RMS differences are 19 DU (6% of the AATS value for AATS-SAGE and 10 DU (3% of the AATS value for AATS-POAM. In these checks of consistency between AATS-14 and SAGE III or POAM III ozone results, the AATS-14 analyses use airmass factors derived from the relative vertical profiles of ozone and aerosol extinction obtained by SAGE III or POAM III.

    We also compare AATS-14 ozone retrievals for measurements obtained during three DC-8 flights that included extended horizontal transects with total column ozone data acquired by the Total Ozone Mapping Spectrometer (TOMS and the Global Ozone Monitoring Experiment (GOME satellite sensors. To enable these comparisons, the amount of ozone in the column below the aircraft is estimated either by assuming a climatological model or by combining SAGE and/or POAM data with high resolution in-situ ozone measurements acquired by the NASA Langley Research Center chemiluminescent ozone sensor, FASTOZ, during the aircraft vertical profile at the start or end of each flight. Resultant total column ozone values agree with corresponding TOMS and GOME measurements to

  11. Thermospheric density and satellite drag modeling

    Science.gov (United States)

    Mehta, Piyush Mukesh

    The United States depends heavily on its space infrastructure for a vast number of commercial and military applications. Space Situational Awareness (SSA) and Threat Assessment require maintaining accurate knowledge of the orbits of resident space objects (RSOs) and the associated uncertainties. Atmospheric drag is the largest source of uncertainty for low-perigee RSOs. The uncertainty stems from inaccurate modeling of neutral atmospheric mass density and inaccurate modeling of the interaction between the atmosphere and the RSO. In order to reduce the uncertainty in drag modeling, both atmospheric density and drag coefficient (CD) models need to be improved. Early atmospheric density models were developed from orbital drag data or observations of a few early compact satellites. To simplify calculations, densities derived from orbit data used a fixed CD value of 2.2 measured in a laboratory using clean surfaces. Measurements from pressure gauges obtained in the early 1990s have confirmed the adsorption of atomic oxygen on satellite surfaces. The varying levels of adsorbed oxygen along with the constantly changing atmospheric conditions cause large variations in CD with altitude and along the orbit of the satellite. Therefore, the use of a fixed CD in early development has resulted in large biases in atmospheric density models. A technique for generating corrections to empirical density models using precision orbit ephemerides (POE) as measurements in an optimal orbit determination process was recently developed. The process generates simultaneous corrections to the atmospheric density and ballistic coefficient (BC) by modeling the corrections as statistical exponentially decaying Gauss-Markov processes. The technique has been successfully implemented in generating density corrections using the CHAMP and GRACE satellites. This work examines the effectiveness, specifically the transfer of density models errors into BC estimates, of the technique using the CHAMP and

  12. Spatial and temporal variation of CO over Alberta using measurements from satellite, aircrafts, and ground stations

    Directory of Open Access Journals (Sweden)

    H. S. Marey

    2014-12-01

    Full Text Available Alberta is Canada's largest oil producer and its oil sand deposits comprise 30% of the world's oil reserves. The process of bitumen extraction and upgrading releases trace gases and aerosols to the atmosphere. In this study we present satellite-based analysis to explore, for the first time, various contributing factors that affect tropospheric carbon monoxide (CO levels over Alberta. The multispectral product that uses both near-infrared (NIR and the thermal-infrared (TIR radiances for CO retrieval from the Measurements of Pollution in the Troposphere (MOPITT are examined for the 12 year period from 2002–2013. Moderate Resolution Imaging Spectroradiometer (MODIS thermal anomaly product from 2001 to 2013 is employed to investigate the seasonal and temporal variations of forest fires. Additionally, in situ CO measurements at industrial and urban sites are compared to satellite data. Furthermore, the available MOZAIC/IAGOS (Measurement of Ozone, Water Vapor, Carbon Monoxide, Nitrogen Oxide by Airbus In-Service Aircraft/In service Aircraft for Global Observing System aircraft CO profiles (April 2009–December 2011 are used to validate MOPITT CO data. The climatological time curtain plot and spatial maps for CO over northern Alberta indicate the signatures of transported CO for two distinct biomass burning seasons, summer and spring. Distinct seasonal patterns of CO at the urban site s (Edmonton and Calgary cities point to the strong influence of traffic. Meteorological parameters play an important role on the CO spatial distribution at various pressure levels. Northern Alberta shows stronger upward lifting motion which leads to larger CO total column values while the poor dispersion in central and south Alberta exacerbates the surface CO pollution. Inter-annual variations of satellite data depict a slightly decreasing trend for both regions while the decline trend is more evident from ground observations, especially at the urban sites. MOPITT CO

  13. Note: Inter-satellite laser range-rate measurement by using digital phase locked loop

    International Nuclear Information System (INIS)

    This note presents an improved high-resolution frequency measurement system dedicated for the inter-satellite range-rate monitoring that could be used in the future’s gravity recovery mission. We set up a simplified common signal test instead of the three frequencies test. The experimental results show that the dominant noises are the sampling time jitter and the thermal drift of electronic components, which can be reduced by using the pilot-tone correction and passive thermal control. The improved noise level is about 10−8 Hz/Hz1/2@0.01Hz, limited by the signal-to-noise ratio of the sampling circuit

  14. Comparison of advanced Arctic Ocean model sea ice fields to satellite derived measurements

    OpenAIRE

    Dimitriou, David S.

    1998-01-01

    Numerical models have proven integral to the study of climate dynamics. Sea ice models are critical to the improvement of general circulation models used to study the global climate. The object of this study is to evaluate a high resolution ice-ocean coupled model by comparing it to derived measurements from SMMR and SSM/I satellite observations. Utilized for this study was the NASA Goddard Space Flight (GSFC) Sea Ice Concentration Data Set from the National Snow and Ice Data Center. Using an...

  15. Influence of atmospheric aerosols and desert reflectance properties on satellite radiance measurements

    Science.gov (United States)

    Bowker, D. E.; Davis, R. E.

    1992-01-01

    The influence of surface bidirectional reflectance factors, including shadowing, and of atmospheric aerosol variability are modeled for their effects on the remote sensing of desert targets from space in the 0.7-micron region at high spatial resolution. The white sand reflectance data of Salomonson (1968) are used as the basis for the simulation. The effects of the surface bi-directional reflectance and atmospheric aerosol on the nadir-normalized reflectance measured at the satellite are discussed individually and jointly. The net influence of these two factors is shown to depend on the magnitude of other parameters, such as the surface reflectance and solar zenith angle.

  16. Reflectometry measurements of the m=1 satellite mode in L- and H-mode plasmas in ASDEX

    International Nuclear Information System (INIS)

    In ASDEX, with strong NBI heating, often a large central m=1, n=1 mode is observed on the SXR emission. For PNBI ≥ 1 MW a mode rotating with the same frequency, the so-called 'm=1 satellite', is seen on the magnetic pick-up coils in the L and H-phases. Magnetic measurements in the divertor chamber suggest that the satellite mode might be located outside the separatrix, on open field lines reaching the divertor. Here we present results from localized microwave reflectometric measurements. The time evolution of the satellite mode frequency is studied for plasmas with different qa and the mode localization is estimated, confirming that it should be close to but outside the separatrix. The central toroidal rotation velocities of the plasma can be inferred from the measured frequencies of the satellite modes. (orig.)

  17. Retrieval of Black Carbon Absorption from Proposed Satellite Measurements Over the Ocean Glint

    Science.gov (United States)

    Kaufman, Y. J.; Matins, J. V.; Remer, L. A.; Schoeberl, M. R.; Yamasoe, M. A.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Haze and air pollution includes many chemicals that together form small particles suspended in the air called aerosols. One of the main ingredients found to affect climate and human health is Black Carbon. Black particles emitted from engines that do not burn the fuel completely, e.g. old trucks. Black carbon absorption of sunlight emerges as one of the key components of man-made forcing of climate. However, global characterization of black carbon emissions, distribution and pathways in which it can affect the amount of solar radiation absorbed by the atmosphere is very uncertain. A new method is proposed to measure sunlight absorption by fine aerosol particles containing black carbon over the ocean glint from a satellite mission designed for this purpose. The satellite will scan the same spot over the ocean in the glint plane and a plane 40 degrees off-glint a minute apart, collecting measurements of the reflected light across the solar spectrum. First the dark ocean off the glint is used to derive aerosol properties. Then the black carbon absorption is derived prop the attenuation of the bright glint by the aerosol layer. Such measurements if realized in a proposed future mission - COBRA are expected to produce global monthly climatology of black carbon absorption with high accuracy (110 to 15%) that can show their effect on climate.

  18. Average thermospheric wind patterns over the polar regions, as observed by CHAMP

    Directory of Open Access Journals (Sweden)

    H. Lühr

    2007-06-01

    Full Text Available Measurements of the CHAMP accelerometer are utilized to investigate the average thermospheric wind distribution in the polar regions at altitudes around 400 km. This study puts special emphasis on the seasonal differences in the wind patterns. For this purpose 131 days centered on the June solstice of 2003 are considered. Within that period CHAMP's orbit is precessing once through all local times. The cross-track wind estimates of all 2030 passes are used to construct mean wind vectors for 918 equal-area cells. These bin averages are presented in corrected geomagnetic coordinates. Both hemispheres are considered simultaneously providing summer and winter responses for the same prevailing geophysical conditions. The period under study is characterized by high magnetic activity (Kp=4− but moderate solar flux level (F10.7=124. Our analysis reveals clear wind features in the summer (Northern Hemisphere. Over the polar cap there is a fast day-to-night flow with mean speeds surpassing 600 m/s in the dawn sector. At auroral latitudes we find strong westward zonal winds on the dawn side. On the dusk side, however, an anti-cyclonic vortex is forming. The dawn/dusk asymmetry is attributed to the combined action of Coriolis and centrifugal forces. Along the auroral oval the sunward streaming plasma causes a stagnation of the day-to-night wind. This effect is particularly clear on the dusk side. On the dawn side it is evident only from midnight to 06:00 MLT. The winter (Southern Hemisphere reveals similar wind features, but they are less well ordered. The mean day-to-night wind over the polar cap is weaker by about 35%. Otherwise, the seasonal differences are mainly confined to the dayside (06:00–18:00 MLT. In addition, the larger offset between geographic and geomagnetic pole in the south also causes hemispheric differences of the thermospheric wind distribution.

  19. Average thermospheric wind patterns over the polar regions, as observed by CHAMP

    Science.gov (United States)

    Lühr, H.; Rentz, S.; Ritter, P.; Liu, H.; Häusler, K.

    2007-06-01

    Measurements of the CHAMP accelerometer are utilized to investigate the average thermospheric wind distribution in the polar regions at altitudes around 400 km. This study puts special emphasis on the seasonal differences in the wind patterns. For this purpose 131 days centered on the June solstice of 2003 are considered. Within that period CHAMP's orbit is precessing once through all local times. The cross-track wind estimates of all 2030 passes are used to construct mean wind vectors for 918 equal-area cells. These bin averages are presented in corrected geomagnetic coordinates. Both hemispheres are considered simultaneously providing summer and winter responses for the same prevailing geophysical conditions. The period under study is characterized by high magnetic activity (Kp=4-) but moderate solar flux level (F10.7=124). Our analysis reveals clear wind features in the summer (Northern) Hemisphere. Over the polar cap there is a fast day-to-night flow with mean speeds surpassing 600 m/s in the dawn sector. At auroral latitudes we find strong westward zonal winds on the dawn side. On the dusk side, however, an anti-cyclonic vortex is forming. The dawn/dusk asymmetry is attributed to the combined action of Coriolis and centrifugal forces. Along the auroral oval the sunward streaming plasma causes a stagnation of the day-to-night wind. This effect is particularly clear on the dusk side. On the dawn side it is evident only from midnight to 06:00 MLT. The winter (Southern) Hemisphere reveals similar wind features, but they are less well ordered. The mean day-to-night wind over the polar cap is weaker by about 35%. Otherwise, the seasonal differences are mainly confined to the dayside (06:00-18:00 MLT). In addition, the larger offset between geographic and geomagnetic pole in the south also causes hemispheric differences of the thermospheric wind distribution.

  20. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Architecture Overview and Technical Performance Measures

    Science.gov (United States)

    Grant, K. D.; Johnson, B. R.; Miller, S. W.; Jamilkowski, M. L.

    2014-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The Joint Polar Satellite System will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a multi-mission enterprise system serving NOAA, NASA and their national and international partners. The CGS provides a wide range of support to a number of missions. Originally designed to support S-NPP and JPSS, the CGS has demonstrated its scalability and flexibility to incorporate all of these other important missions efficiently and with minimal cost, schedule and risk, while strengthening global partnerships in weather and environmental monitoring. The CGS architecture will be upgraded to Block 2.0 in 2015 to satisfy several key objectives, including: "operationalizing" S-NPP, which had originally been intended as a risk reduction mission; leveraging lessons learned to date in multi-mission support; taking advantage of newer, more reliable and efficient technologies; and satisfying new requirements and constraints due to the continually evolving budgetary environment. To ensure the CGS meets these needs, we have developed 48 Technical Performance Measures (TPMs) across 9 categories: Data Availability, Data Latency, Operational Availability, Margin, Scalability, Situational Awareness, Transition (between environments and sites), WAN Efficiency, and Data Recovery Processing. This

  1. Test of general relativity and measurement of the lense-thirring effect with two earth satellites

    Science.gov (United States)

    Ciufolini; Pavlis; Chieppa; Fernandes-Vieira; Perez-Mercader

    1998-03-27

    The Lense-Thirring effect, a tiny perturbation of the orbit of a particle caused by the spin of the attracting body, was accurately measured with the use of the data of two laser-ranged satellites, LAGEOS and LAGEOS II, and the Earth gravitational model EGM-96. The parameter &mgr;, which measures the strength of the Lense-Thirring effect, was found to be 1.1 +/- 0.2; general relativity predicts &mgr; identical with 1. This result represents an accurate test and measurement of one of the fundamental predictions of general relativity, that the spin of a body changes the geometry of the universe by generating space-time curvature. PMID:9516109

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

    Science.gov (United States)

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

    2015-06-01

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

  3. Array of Neutral Density Relative Observations MEasuring Divergence in the Atmosphere (ANDROMEDA), A Constellation Concept for Studying Thermospheric Dynamics

    Science.gov (United States)

    Palo, S. E.; Pilinski, M.; Forbes, J. M.

    2015-12-01

    In addition to being critical to the prediction of satellite orbits, total mass density is a fundamental property of the thermosphere. Density measurements from accelerometers on the CHAMP satellite have revealed quasi-steady state distributions of density structures around the globe, density responses to changing solar and geomagnetic activity, and spatial structures of wave-like phenomena along the orbit. However, a basic limitation on the time scale of any observable phenomenon is the ~90-minute orbital period. Thus, single-satellite missions like CHAMP are unable to measure the time derivative of density or the mass flux divergence (MFD) at a single point in the atmosphere. While the two accelerometer-carrying GRACE satellites could theoretically measure the density time derivative, in practice this measurement is hampered by the very low-signal levels in the tenuous atmosphere at the ~500-km GRACE orbits, as well as inter-satellite biases and drifts. The Array of Neutral Density Relative Observations Measuring Divergence in the Atmosphere (ANDROMEDA) is a constellation of CubeSats aimed at improving our understanding of atmospheric dynamics by measuring and interpreting the characteristics of traveling atmospheric disturbances as well as the distribution of MFD in the thermosphere. The ANDROMEDA constellation consists of two to three identical CubeSats spaced approximately 300 km apart and making multi-point measurements of total mass density with an accuracy of benefit of the torque-balance technique is the high level of inter-satellite accuracy. The constellation will be deployed from the ISS and will make observations between 400 km and 250 km altitude as the satellite orbits decay. Distance between the spacecraft will be controlled by modifying the relative ballistic coefficients through small changes in the angle of attack. In this poster, we present the ANDROMEDA science objectives and requirement flow-down. We then describe the constellation design and

  4. Feasibility of a Constellation of Miniature Satellites for Performing Measurements of the Magnetic Field of the Earth

    DEFF Research Database (Denmark)

    Thomsen, Michael; Merayo, José M.G.; Brauer, Peter; Vennerstrøm, Susanne; Olsen, Nils; Tøffner-Clausen, Lars

    This paper studies the requirements for a small constellation of satellites to perform measurements of the magnetic field of the Earth and a payload and boom design for such a mission is discussed. After studying communication, power and mass requirements it is found that it is feasible to develop...... a 10 x 10 x 30 cm(3) satellite with a mass of about 2.5 kg, which can fulfill such a mission. We also study the feasibility of controlling a constellation of such small satellites by means of air drag by extracting one or more flaps. It is found that it is indeed possible, but for best performance...

  5. Upper tropospheric water vapour variability over tropical latitudes observed using radiosonde and satellite measurements

    Indian Academy of Sciences (India)

    Ghouse Basha; M Venkat Ratnam; B V Krishna Murthy

    2013-12-01

    The present study deals with using long-term database for upper tropospheric water vapour (UTWV) variability studies over three tropical stations (Gadanki, Singapore and Truk), where different climatic conditions prevail. Over Gadanki (13.5°N, 79.2°E) strong seasonal variation in UTWV is revealed but not over Singapore (1.37°N, 103.98°E) and Truk (7.46°N, 151.85°E) except at 100 hPa. It is examined whether high resolution radiosonde measurements represent well the UTWV by comparing with different satellite based (Atmospheric Infrared Sounder (AIRS), Advanced Microwave Sounding Unit-B (AMSUB) and Microwave Limb Sounder (MLS)) water vapour measurements. Very good comparison in the nature of variations of UTWV is observed between radiosonde data and satellite data, except over Singapore particularly with AIRS and MLS data, on long-term basis. An attempt is also made to examine the source for UTWV. A close relationship is found between UTWV and deep convection over Gadanki indicating that the source for UTWV is convection particularly during the summer monsoon season.

  6. Precession–nutation correction for star tracker attitude measurement of STECE satellite

    Directory of Open Access Journals (Sweden)

    Lai Yuwang

    2014-02-01

    Full Text Available Space Technology Experiment and Climate Exploration (STECE is a small satellite mission of China for space technology experiment and climate exploration. A new test star tracker and one ASTRO 10 star tracker have been loaded on the STECE satellite to test the new star tracker’s measurement performance. However, there is no autonomous precession–nutation correction function for the test star tracker, which causes an apparent periodic deflection in the inter-boresight angle between the two star trackers with respect to each other of up to ±500 arcsec, so the precession and nutation effect needs to be considered while assessing the test star tracker. This paper researches on the precession–nutation correction for the test star tracker’s attitude measurement and presents a precession–nutation correction method based on attitude quaternion data. The periodic deflection of the inter-boresight angle between the two star trackers has been greatly eliminated after the precession and nutation of the test star tracker’s attitude data have been corrected by the proposed method and the validity of the proposed algorithm has been demonstrated. The in-flight accuracy of the test star tracker has been assessed like attitude noise and low-frequency errors after the precession–nutation correction.

  7. Precession-nutation correction for star tracker attitude measurement of STECE satellite

    Institute of Scientific and Technical Information of China (English)

    Lai Yuwang; Liu Junhong; Ding Yonghe; Gu Defeng; Yi Dongyun

    2014-01-01

    Space Technology Experiment and Climate Exploration (STECE) is a small satellite mis-sion of China for space technology experiment and climate exploration. A new test star tracker and one ASTRO 10 star tracker have been loaded on the STECE satellite to test the new star tracker’s measurement performance. However, there is no autonomous precession-nutation correction func-tion for the test star tracker, which causes an apparent periodic deflection in the inter-boresight angle between the two star trackers with respect to each other of up to ±500 arcsec, so the preces-sion and nutation effect needs to be considered while assessing the test star tracker. This paper researches on the precession-nutation correction for the test star tracker’s attitude measurement and presents a precession-nutation correction method based on attitude quaternion data. The peri-odic deflection of the inter-boresight angle between the two star trackers has been greatly eliminated after the precession and nutation of the test star tracker’s attitude data have been corrected by the proposed method and the validity of the proposed algorithm has been demonstrated. The in-flight accuracy of the test star tracker has been assessed like attitude noise and low-frequency errors after the precession-nutation correction.

  8. Seven year particulate matter air quality assessment from surface and satellite measurements

    Directory of Open Access Journals (Sweden)

    P. Gupta

    2008-01-01

    Full Text Available Using seven years of the Moderate Resolution Imaging Spectroradiometer (MODIS aerosol optical thickness (AOT data and ground measurements of particulate matter mass over one site in the Southeastern United States (33.55 N, 86.82 W we present a comprehensive analysis of various aspects of particulate matter air quality. Monthly, seasonal and inter-annual relationships are examined with emphasis on sampling biases, quality indicators in the AOT product and various cloud clearing criteria. Our results indicate that PM2.5 mass concentration over Northern Birmingham has decreased by about 23% in year 2006 when compared to year 2002 and air quality during summer months are poor when compared to winter months. MODIS-Terra AOT data was available only about 50% of the time due to cloud cover and favorable surface conditions. However, the mean difference in monthly mean PM2.5 was less than 2.2 μgm−3 derived using all the data and from only those days when satellite AOT was available indicating that satellite data does not have sampling issues. The correlation between PM2.5 and MODIS AOT increased from 0.52 to 0.62 when hourly PM2.5 data were used instead of daily mean PM2.5 data. Changing box size for satellite data around the ground station during comparisons produced less than ±0.03 difference in mean AOT values for 90% of observations. Application of AOT quality flags reduced the sample size but does not affect AOT-PM2.5 relationship significantly. We recommend using AOT quality flags for daily analysis, whereas long time scale analysis can be performed without using all AOT retrievals to obtain better sampling. Our analysis indicates that satellite data is a useful tool for monitoring particulate matter air quality especially in regions where ground measurements are not available.

  9. Sporadic E Morphology from GPS-CHAMP Radio Occultation

    Science.gov (United States)

    Wu, Dong L.; Ao, Chi O.; Hajj, George A.; de la Torre Juarez, Manuel; Mannucci, Anthony J.

    2005-01-01

    The scintillations of phase and amplitude in terms of signal-to-noise ratio (SNR) of the GPS radio occultation signal are caused by thin ionization layers. These thin irregular electron density layers in the E region ionosphere are often called sporadic E (Es). For a monthly retrieval of Es morphology we use the variances of the phase and SNR fluctuations of worldwide 6000 GPS/CHAMP occultations in the E region. The Es climatology is studied globally with the SNR and phase variances in terms of monthly zonal means, seasonal maps, and diurnal and long-term variations. The zonal mean variances reveal strong, extended Es activities at summertime midlatitudes but weak, confined activities in wintertime high latitudes, peaking at 105 km. Global maps at 105-km altitude show clear dependence of Es activities on the geomagnetic dip angle, where the summertime midlatitude Es occurs mostly at dip angles of 30 deg. - 60 deg. and the wintertime high-latitude enhancement occurs mostly at dip angles greater than 80 deg. The midlatitude Es variances exhibit a strong semidiurnal variation with peak hours near 0800 1000 and 2000 local solar time, respectively. The peak hours are delayed slightly with decreasing height, suggesting influences from the semidiurnal tide. To provide more insights on the observed SNR and phase variances, we model radio wave propagation for the CHAMP observing geometry under several perturbed cases in the E region ionosphere. The model simulations indicate that the SNR variance has the maximum response to Es perturbations at vertical wavelengths of 1.2 km, whereas the phase response maximizes at 2 km (for the 1-s variance analysis). The characteristic scale depends little on the truncation time used in the SNR variance analysis, but it increases with the truncation time for the phase variances. Initial studies show that reasonable global Es morphology can be produced on a monthly and seasonal basis with the CHAMP one-antenna occultations. Better results

  10. Alfvén wave characteristics of equatorial plasma irregularities in the ionosphere derived from CHAMP observations

    Directory of Open Access Journals (Sweden)

    Hermann eLühr

    2014-08-01

    Full Text Available We report magnetic field observations of the components transverse to the main field in the frequency range 1-25 Hz from times of equatorial plasma irregularity crossings. These field variations are interpreted as Alfvénic signatures accompanying intermediate-scale (150 m – 4 km plasma density depletions. Data utilized are the high-resolution CHAMP magnetic field measurements sampled at 50 Hz along the north-south satellite track. The recorded signals do not reflect the temporal variation but the spatial distribution of Alfvénic signatures. This is the first comprehensive study of Alfvénic signatures related to equatorial plasma bubbles that covers the whole solar cycle from 2000 to 2010. A detailed picture of the wave characteristics can be drawn due to the large number (almost 9000 of events considered. Some important findings are: Alfvénic features are a common feature of intermediate-scale plasma structures. The zonal and meridional magnetic components are generally well correlated suggesting skewed current sheets. The sheets have an orientation that is on average deflect by about 32° away from magnetic east towards upward or downward depending on the hemisphere. We have estimated the Poynting flux flowing into the E region. Typical values are distributed over the range 10-8 - 10-6 W/m2. Large Poynting fluxes are related to steep spectra of the Alfvénic signal, which imply passages through regularly varying electron density structures. No dependence of the Poynting flux level on solar activity has been found. But below a certain solar flux value (F10.7 < 100 sfu practically no events are detected. There is a clear tendency that large Poynting flux events occur preferably at early hours after sunset (e.g. 20:00 local time. Towards later times the occurrence peak shifts successively towards lower energy levels. Finally we compare our observations with the recently published results of the high-resolution 3-D model simulations by Dao et

  11. An Assessment of Biases in Satellite CO2 Measurements Using Atmospheric Inversion

    Science.gov (United States)

    Baker, D. F.; O'Dell, C.

    2014-12-01

    Column-integrated CO2 mixing ratio measurements from satellite should provide a new view of the global carbon cycle, thanks to their ability to measure with great coverage in places that are poorly sampled by the in situ network (e.g. the tropics) using a new approach (full-column averages rather than point measurements). For this new insight to be useful, however, systematic errors in these data must first be identified and removed. Here we use atmospheric transport modeling to perform a global comparison of satellite CO2 measurements to higher-quality reference data (in situ data from flasks and aircraft, column CO2 data from the upward-looking spectrometers of the TCCON network) to assess systematic errors in the satellite data. This broad comparison is meant to complement the more direct validation done at specific TCCON sites. A suite of 3-D CO2 mixing ratio histories are generated across 2009-2014 using combinations of several different a priori fossil fuel, land biospheric, and oceanic CO2 fluxes run through the PCTM off-line atmospheric transport model driven by MERRA 1°x1.25° winds and vertical mixing parameters. Each member of the suite is forced to agree with in situ CO2 measurements (flask, tall tower, and routine light aircraft profiles) through use of a variational carbon data assimilation (4Dvar) system. The optimized 3-D CO2 fields are then compared to ACOS column CO2 retrievals of GOSAT data, with the differences being fit to different independent variables (aerosol optical depth, atmospheric path length, surface albedo, etc.) to derive a GOSAT bias correction. ACOS-GOSAT CO2 retrievals, corrected by this scheme, as well as with the "official" ACOS bias correction, will then be assimilated using the same 4Dvar approach. The benefit of the GOSAT data with and without the bias corrections will then be assessed by comparing the optimized CO2 fields to independent data (TCCON column data, as well as aircraft data left out of the in situ inversions

  12. Intercomparison of total precipitable water measurements made by satellite-borne microwave radiometers and ground-based GPS instruments

    Science.gov (United States)

    Mears, Carl A.; Wang, Junhong; Smith, Deborah; Wentz, Frank J.

    2015-03-01

    High-quality, high temporal resolution measurements of total precipitable water (TPW) can be made by evaluating the vapor-dependent delay of radio signals reaching land-based Global Positioning System (GPS) receivers from GPS satellites. These measurements are available since the mid-1990s when the GPS system became operational. Over the world's oceans, satellite-borne microwave imaging radiometers have been making measurements of TPW for more than 25 years. In this work, we perform an intercomparison of collocated TPW measurements made by these two disparate systems using measurements from 26 GPS stations located on small islands. The two types of measurements agree well, with typical satellite-station mean differences of less than 1.0 kg m-2. Analysis revealed several cases of inhomogeneities in the GPS data set, and two deficiencies in the Remote Sensing Systems satellite data, demonstrating the usefulness of intercomparison for improving the accuracy of both types of data. After the individual station, biases were removed, the standard deviation of the overall differences between individual satellites and GPS measurements ranged between 1.60 and 1.94 kg m-2. Twelve GPS stations had overlap time periods long enough to evaluate difference trends, yielding 59 satellite-station pairs when paired with different satellites. More than half of the pairs (39 of 59) did not show a significant trend. The 20 pairs with significant trends did not show trends of predominantly one sign, suggesting that neither system is plagued by a system-wide drift in TPW.

  13. Satellite Geomagnetism

    OpenAIRE

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade. The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite c...

  14. Night sky brightness at sites from DMSP-OLS satellite measurements

    CERN Document Server

    Cinzano, P

    2004-01-01

    We apply the sky brightness modelling technique introduced and developed by Roy Garstang to high-resolution DMSP-OLS satellite measurements of upward artificial light flux and to GTOPO30 digital elevation data in order to predict the brightness distribution of the night sky at a given site in the primary astronomical photometric bands for a range of atmospheric aerosol contents. This method, based on global data and accounting for elevation, Earth curvature and mountain screening, allows the evaluation of sky glow conditions over the entire sky for any site in the World, to evaluate its evolution, to disentangle the contribution of individual sources in the surrounding territory, and to identify main contributing sources. Sky brightness, naked eye stellar visibility and telescope limiting magnitude are produced as 3-dimensional arrays whose axes are the position on the sky and the atmospheric clarity. We compared our results to available measurements.

  15. NGSLR's Measurement of the Retro-Reflector Array Response of Various LEO to GNSS Satellites

    Science.gov (United States)

    McGarry, Jan; Clarke, Christopher; Degnan, John; Donovan, Howard; Hall, Benjamin; Hovarth, Julie; Zagwodzki, Thomas

    2012-01-01

    "NASA's Next Generation Satellite Laser Ranging System (NGSLR) has successfully demonstrated daylight and nighttime tracking this year to s atellites from LEO to GNSS orbits, using a 7-8 arcsecond beam divergence, a 43% QE Hamamatsu MCP-PMT with single photon detection, a narrow field of view (11 arcseconds), and a 1 mJ per pulse 2kHz repetition rate laser. We have compared the actual return rates we are getting against the theoretical link calculations, using the known system confi guration parameters, an estimate of the sky transmission using locall y measured visibility, and signal processing to extract the signal from the background noise. We can achieve good agreement between theory and measurement in most passes by using an estimated pOinting error. We will s.()w the results of this comparison along with our conclusio ns."

  16. Direct measurements of laser light aberration from the ARTEMIS geostationary satellite through thin clouds

    CERN Document Server

    Kuzkov, Volodymyr; Sodnik, Zoran

    2015-01-01

    A precise ground based telescope system was developed for laser communication experiments with the geostationary satellite ARTEMIS of ESA. Precise tracking of the satellite was realized by using time resolved coordinates of the satellite. During the experiments, the time propagation of laser signal from the satellite and the point-ahead angle for the laser beam were calculated. Some laser experiments though thin clouds were performed. A splitting of some images of the laser beam from the satellite along declination and right ascension coordinates of telescope could be observed through thin clouds. The splitting along the declination coordinate may be interpreted as refraction in the atmosphere. The splitting along the right ascension coordinate is equivalent to the calculated point-ahead angle for the satellite. We find out that a small part of laser beam was observed ahead of the velocity vector in the point where the satellite would be after the laser light from the satellite reaches the telescope. These re...

  17. How Consistent are Recent Variations in the Tropical Energy and Water Cycle Resolved by Satellite Measurements?

    Science.gov (United States)

    Robertson, F. R.; Lu, H.-I.

    2004-01-01

    One notable aspect of Earth's climate is that although the planet appears to be very close to radiative balance at top-of-atmosphere (TOA), the atmosphere itself and underlying surface are not. Profound exchanges of energy between the atmosphere and oceans, land and cryosphere occur over a range of time scales. Recent evidence from broadband satellite measurements suggests that even these TOA fluxes contain some detectable variations. Our ability to measure and reconstruct radiative fluxes at the surface and at the top of atmosphere is improving rapidly. One question is 'How consistent, physically, are these diverse remotely-sensed data sets'? The answer is of crucial importance to understanding climate processes, improving physical models, and improving remote sensing algorithms. In this work we will evaluate two recently released estimates of radiative fluxes, focusing primarily on surface estimates. The International Satellite Cloud Climatology Project 'FD' radiative flux profiles are available from mid-1983 to near present and have been constructed by driving the radiative transfer physics from the Goddard Institute for Space Studies (GISS) global model with ISCCP clouds and TOVS (TIROS Operational Vertical Sounder)thermodynamic profiles. Full and clear sky SW and LW fluxes are produced. A similar product from the NASA/GEWEX Surface Radiation Budget Project using different radiative flux codes and thermodynamics from the NASA/Goddard Earth Observing System (GEOS-1) assimilation model makes a similar calculation of surface fluxes. However this data set currently extends only through 1995. We also employ precipitation measurements from the Global Precipitation Climatology Project (GPCP) and the Tropical Rainfall Measuring Mission (TRMM). Finally, ocean evaporation estimates from the Special Sensor Microwave Imager (SSM/I) are considered as well as derived evaporation from the NCAR/NCEP Reanalysis. Additional information is included in the original extended

  18. CLAIRE: a Canadian Small Satellite Mission for Measurement of Greenhouse Gases

    Science.gov (United States)

    Sloan, James; Grant, Cordell; Germain, Stephane; Durak, Berke; McKeever, Jason; Latendresse, Vincent

    2016-07-01

    CLAIRE, a Canadian mission operated by GHGSat Inc. of Montreal, is the world's first satellite designed to measure greenhouse gas emissions from single targeted industrial facilities. Claire was launched earlier this year into a 500 km polar sun-synchronous orbit selected to provide an acceptable balance between return frequency and spatial resolution. Extensive simulations of oil & gas facilities, power plants, hydro reservoirs and even animal feedlots were used to predict the mission performance. The principal goal is to measure the emission rates of carbon dioxide and methane from selected targets with greater precision and lower cost than ground-based alternatives. CLAIRE will measure sources having surface areas less than 10 x 10 km2 with a spatial resolution better than 50 m, thereby providing industrial site operators and government regulators with the information they need to understand, manage and ultimately to reduce greenhouse gas emissions more economically. The sensor is based on a Fabry-Perot interferometer, coupled with a 2D InGaAs focal plane array operating in the short-wave infrared with a spectral resolution of about 0.1 nm. The patented, high étendue, instrument design provides signal to noise ratios that permit quantification of emission rates with accuracies adequate for most regulatory reporting thresholds. The very high spatial resolution of the density maps produced by the CLAIRE mission resolves plume shapes and emitter locations so that advanced dispersion models can derive accurate emission rates of multiple sources within the field of view. The satellite bus, provided by the University of Toronto's Space Flight Laboratory, is based on the well-characterized NEMO architecture, including hardware that has significant spaceflight heritage. The mission is currently undergoing initial test and validation measurements in preparation for commercial operation later this year.

  19. Direct measurements of laser light aberration from the ARTEMIS geostationary satellite through thin clouds

    OpenAIRE

    Kuzkov, Volodymyr; Kuzkov, Sergii; Sodnik, Zoran

    2015-01-01

    A precise ground based telescope system was developed for laser communication experiments with the geostationary satellite ARTEMIS of ESA. Precise tracking of the satellite was realized by using time resolved coordinates of the satellite. During the experiments, the time propagation of laser signal from the satellite and the point-ahead angle for the laser beam were calculated. Some laser experiments though thin clouds were performed. A splitting of some images of the laser beam from the sate...

  20. Intrication de champs quantiques mesoscopiques pour les communications quantiques

    OpenAIRE

    Blandino, Rémi

    2013-01-01

    Cette thèse s’inscrit dans le cadre de l’information quantique avec des variables continues, en utilisant des états quantiques du champ électromagnétique. En combinant les outils propres aux variables discrètes, o`u la lumière est décrite en termes de photons, avec les outils des variables continues, où la lumière est décrite en termes de quadratures, nous pouvons étudier théoriquement et produire expérimentalement des états non-classiques, ainsi que des protocoles élémentaires d’information ...

  1. La genèse du concept de champ quantique

    Science.gov (United States)

    Darrigol, O.

    This is a historical study of the roots of a concept which has proved to be essential in modern particle physics : the concept of quantum field. The first steps were accomplished by two young theoreticians : Pascual Jordan quantized the free electromagnetic field in 1925 by means of the formal rules of the just discovered matrix mechanics, and Paul Dirac quantized the whole system charges + field in 1927. Using Dirac's equation for electrons (1928) and Jordan's idea of quantized matter waves (second quantization), Werner Heisenberg and Wolfgang Pauli provided in 1929-1930 an extension of Dirac's radiation theory and the proof of its relativistic invariance. Meanwhile Enrico Fermi discovered independently a more elegant and pedagogical formulation. To appreciate the degree of historical necessity of the quantization of fields, and the value of contemporaneous critics to this approach, it was necessary to investigate some of the history of the old radiation theory. We present the various arguments however provisional or naïve or wrong they could be in retrospect. So we hope to contribute to a more vivid picture of notions which, once deprived of their historical setting, might seem abstruse to the modern user. Nous présentons une étude historique des origines d'un concept devenu essentiel dans la physique moderne des particules : le concept de champ quantique. Deux jeunes théoriciens franchirent les premières étapes : Pascual Jordan quantifia le champ électromagnétique en 1925 grâce aux règles formelles de la mécanique des matrices naissante, et Paul Dirac quantifia le système complet charges + champ en 1927. Au moyen de l'équation de l'électron de Dirac (1928) et de l'idée de Jordan d'ondes de matière quantifiées (deuxième quantification), Werner Heisenberg et Wolfgang Pauli donnèrent en 1929-1930 une extension de la théorie du rayonnement de Dirac et la preuve de son invariance relativiste. Pendant ce temps Enrico Fermi découvrit ind

  2. Emmanuelle de Champs, La déontologie politique

    Directory of Open Access Journals (Sweden)

    Anne Brunon-Ernst

    2009-07-01

    Full Text Available Emmanuelle de Champs est maître de conférences à l’université Paris VIII et membre du Centre Bentham. La déontologie politique est le fruit de son travail de thèse. Dans cet ouvrage, elle se penche sur la théorie constitutionnelle de Jeremy Bentham (1748-1832. Son approche est double, à la fois historique et philosophique. Le premier chapitre aborde de manière synthétique le système philosophique de Bentham qui sous-tend sa théorie constitutionnelle. Il est d’abord consacré à un panorama his...

  3. On the estimation of the equatorial electrojet magnetic signature and peak current density from polar orbiting satellite magnetic measurements

    International Nuclear Information System (INIS)

    Complete text of publication follows. Space-based geomagnetic observations are usually made on board low altitude near polar orbiting satellites. These satellites sweep all longitude sectors and provide quasi regular and homogenous global scale dataset. Especially, for the study of the equatorial electrojet (EEJ) features including its longitude dependence, only satellite magnetic measurements are capable of providing such global coverage. However, the orbit along-track methods of extracting the EEJ signature from satellite observations do not allow an accurate estimate of its peak current density in certain longitude sectors. By comparing ground-based and satellite observations, we show that satellite orbit along-track methods fit well the latitude profiles of the EEJ magnetic effect when the satellite paths are perpendicular to the dip-equator, as in most part of the longitude sectors of Asia and Africa. Otherwise, the EEJ latitude profiles are biased, which leads to poor estimate of the EEJ features (magnetic signature, peak-current density, position of the EEJ center, etc.), as in the Atlantic Ocean and most of South American sectors, where the dip-equator is strongly tilted from the East-West direction.

  4. Satellite quenching timescales in clusters from projected phase space measurements matched to simulated orbits

    Science.gov (United States)

    Oman, Kyle A.; Hudson, Michael J.

    2016-09-01

    We measure the star formation quenching efficiency and timescale in cluster environments. Our method uses N-body simulations to estimate the probability distribution of possible orbits for a sample of observed SDSS galaxies in and around clusters based on their position and velocity offsets from their host cluster. We study the relationship between their star formation rates and their likely orbital histories via a simple model in which star formation is quenched once a delay time after infall has elapsed. Our orbit library method is designed to isolate the environmental effect on the star formation rate due to a galaxy's present-day host cluster from `pre-processing' in previous group hosts. We find that quenching of satellite galaxies of all stellar masses in our sample (109 - 1011.5 M⊙) by massive (> 1013 M⊙) clusters is essentially 100 per cent efficient. Our fits show that all galaxies quench on their first infall, approximately at or within a Gyr of their first pericentric passage. There is little variation in the onset of quenching from galaxy-to-galaxy: the spread in this time is at most ˜2 Gyr at fixed M★. Higher mass satellites quench earlier, with very little dependence on host cluster mass in the range probed by our sample.

  5. Surface Emissivity Retrieved with Satellite Ultraspectral IR Measurements for Monitoring Global Change

    Science.gov (United States)

    Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Schluessel, Peter

    2009-01-01

    Surface and atmospheric thermodynamic parameters retrieved with advanced ultraspectral remote sensors aboard Earth observing satellites are critical to general atmospheric and Earth science research, climate monitoring, and weather prediction. Ultraspectral resolution infrared radiance obtained from nadir observations provide atmospheric, surface, and cloud information. Presented here is the global surface IR emissivity retrieved from Infrared Atmospheric Sounding Interferometer (IASI) measurements under "clear-sky" conditions. Fast radiative transfer models, applied to the cloud-free (or clouded) atmosphere, are used for atmospheric profile and surface parameter (or cloud parameter) retrieval. The inversion scheme, dealing with cloudy as well as cloud-free radiances observed with ultraspectral infrared sounders, has been developed to simultaneously retrieve atmospheric thermodynamic and surface (or cloud microphysical) parameters. Rapidly produced surface emissivity is initially evaluated through quality control checks on the retrievals of other impacted atmospheric and surface parameters. Surface emissivity and surface skin temperature from the current and future operational satellites can and will reveal critical information on the Earth s ecosystem and land surface type properties, which can be utilized as part of long-term monitoring for the Earth s environment and global climate change.

  6. Simultaneous conjugate ground-satellite ULF pulsation measurements at the middle latitudes

    Directory of Open Access Journals (Sweden)

    K. Prikner

    Full Text Available The spectra of three series of simultaneous ground (Budkov Observatory and satellite (Freja ULF measurements have been processed. The following features were studied in the FFT spectra, power-spectra and cross-spectra of the six-minute samples, recorded during quasi-conjugate approaches of Freja to the local Budkov magnetic field line: (a the Doppler frequency shift (about 1mHz and less in the predominant and some particular spectral components on Freja; (b the amplitude relations between the ground and satellite (ratios 0.3 to 0.8; (c phase shifts between particular signal components on the spacecraft above the ionosphere (in the azimuthal y-direction on Freja and on the ground (in the meridional x-direction at Budkov have been estimated (phase lags on the ground ≤ 0.9rad and (d also dynamical characteristics of the fundamental wave modes in the (x,y-plane, perpendicular to the magnetic field line, have been estimated for the predominant spectral components, considering standing oscillation along the field line. Azimuthal wave numbers were about 2.0, propagating northwest at ~400km/s.

  7. Measuring equipment of solar cell characteristics on board the satellite 'JIKIKEN' and data of radiation degradation

    International Nuclear Information System (INIS)

    In the measuring equipment of solar cell characteristics (SCM) on board the satellite ''JIKIKEN'' to investigate the degradation of solar cell output mainly in Van Allen belt in the geomagnetic sphere, solar cells were mounted on the special panel of SCM on the surface of the satellite. The solar cells were six n/p elements of 1 cm square with various cover glasses. After confirming the normal operation of SCM, the I-V (current-voltage) characteristics of the solar cells were investigated. The examination on short circuit current and maximum power is reported among the data obtained from the 32nd to the 622nd orbiting. The facts somewhat differing from the results published so far about the above two items have been obtained. The facts include that (1) when the thickness of fused quartz cover glasses on the back surface field solar cells was varied to 0.15, 0.3 and 0.6 mm, the degradation of the characteristics at 0.6 mm thick was larger than expected, specifically in the maximum power, though the degradation was less as the glasses were thicker. (2) The short circuit current obtained at the 5th orbiting decreased by 4.1 to 10.8% from the data on the ground before flight. The presumption of the causes is described. (Wakatsuki, Y.)

  8. Evaluation of Satellite and Reanalysis Soil Moisture Products over Southwest China Using Ground-Based Measurements

    Directory of Open Access Journals (Sweden)

    Jian Peng

    2015-11-01

    Full Text Available Long-term global satellite and reanalysis soil moisture products have been available for several years. In this study, in situ soil moisture measurements from 2008 to 2012 over Southwest China are used to evaluate the accuracy of four satellite-based products and one reanalysis soil moisture product. These products are the Advanced Microwave Scanning Radiometer for the Earth observing system (AMSR-E, the Advanced Scatterometer (ASCAT, the Soil Moisture and Ocean Salinity (SMOS, the European Space Agency’s Climate Change Initiative soil moisture (CCI SM, and the European Centre for Medium-Range Weather Forecasts (ECMWF Interim Reanalysis (ERA-Interim. The evaluation of soil moisture absolute values and anomalies shows that all the products can capture the temporal dynamics of in situ soil moisture well. For AMSR-E and SMOS, larger errors occur, which are likely due to the severe effects of radio frequency interference (RFI over the test region. In general, the ERA-Interim (R = 0.782, ubRMSD = 0.035 m3/m3 and CCI SM (R = 0.723, ubRMSD = 0.046 m3/m3 perform the best compared to the other products. The accuracy levels obtained are comparable to validation results from other regions. Therefore, local hydrological applications and water resource management will benefit from the long-term ERA-Interim and CCI SM soil moisture products.

  9. Early assessment of Integrated Multi-satellite Retrievals for Global Precipitation Measurement over China

    Science.gov (United States)

    Guo, Hao; Chen, Sheng; Bao, Anming; Behrangi, Ali; Hong, Yang; Ndayisaba, Felix; Hu, Junjun; Stepanian, Phillip M.

    2016-07-01

    Two post-real time precipitation products from the Integrated Multi-satellite Retrievals for Global Precipitation Measurement Mission (IMERG) are systematically evaluated over China with China daily Precipitation Analysis Product (CPAP) as reference. The IMERG products include the gauge-corrected IMERG product (IMERG_Cal) and the version of IMERG without direct gauge correction (IMERG_Uncal). The post-research TRMM Multisatellite Precipitation Analysis version 7 (TMPA-3B42V7) is also evaluated concurrently with IMERG for better perspective. In order to be consistent with CPAP, the evaluation and comparison of selected products are performed at 0.25° and daily resolutions from 12 March 2014 through 28 February 2015. The results show that: Both IMERG and 3B42V7 show similar performances. Compared to IMERG_Uncal, IMERG_Cal shows significant improvement in overall and conditional bias and in the correlation coefficient. Both IMERG_Cal and IMERG_Uncal perform relatively poor in winter and over-detect slight precipitation events in northwestern China. As an early validation of the GPM-era IMERG products that inherit the TRMM-era global satellite precipitation products, these findings will provide useful feedbacks and insights for algorithm developers and data users over China and beyond.

  10. A global ETCCDI based precipitation climatology from satellite and rain gauge measurements

    Science.gov (United States)

    Dietzsch, Felix; Andersson, Axel; Schröder, Marc; Ziese, Markus; Becker, Andreas

    2016-04-01

    The project framework MiKlip ("Mittelfristige Klimaprognosen") is focused onto the development of an operational forecast system for decadal climate predictions. The objective of the "Daily Precipitation Analysis for the validation of Global medium-range Climate predictions Operationalized" (DAPAGLOCO) project, is the development and operationalization of a global precipitation dataset for forecast validation of the MPI-ESM experiments used in MiKlip. The dataset is a combination of rain gauge measurement data over land and satellite-based precipitation retrievals over ocean. Over land, gauge data from the Global Precipitation Climatology Centre (GPCC) at Deutscher Wetterdienst (DWD) are used. Over ocean, retrievals from the Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data (HOAPS) dataset are used as data source. The currently available dataset consists of 21 years of data (1988-2008) and has a spatial resolution of 1°. So far, the MiKlip forecast validation is based upon the Expert Team on Climate Change and Detection Indices (ETCCDI). These indices focus on precipitation extrema in terms of spell durations, percentiles, averaged precipitation amounts and further more. The application of these indices on the DAPAGLOCO dataset in its current state delivers insight into the global distribution of precipitation characteristics and extreme events. The resulting global patterns of these characteristics and extrema are the main objective of the presentation.

  11. MONS on the Danish Roemer satellite Measuring Oscillations in Nearby Stars

    CERN Document Server

    Christensen-Dalsgaard, J

    2001-01-01

    MONS is the scientific project on the Danish Roemer satellite mission, which is being developed as part of the Danish Small Satellite Programme. The principal goal is to study solar-like oscillations in around 20 bright stars, with a precision that in the best cases will be limited only by the intrinsic stellar `noise'. The baseline orbit, a so-called Molniya orbit, allows access to essentially the entire sky during the planned 2-year mission. The main instrument is a short-focus reflecting telescope with an aperture of 32 cm, making two-colour measurements. A focused Field Monitor will be used to detect and correct for possible faint variable stars of substantial amplitude near the main target. In addition the Field Monitor, and the Star Trackers on the platform, may be used to observe a broad range of variable phenomena. The project has concluded the Systems Definition Phase by a successful review, and launch is scheduled for the middle of 2005.

  12. Light scattering and absorption properties of dust particles retrieved from satellite measurements

    International Nuclear Information System (INIS)

    We use the radiative transfer model and chemistry transport model to improve our retrievals of dust optical properties from satellite measurements. The optical depth and absorbing optical depth of mineral dust can be obtained from our improved retrieval algorithm. We find the nonsphericity and absorption of dust particles strongly affect the scattering signatures such as phase function and polarization at the ultraviolet wavelengths. From our retrieval results, we find the high levels of dust concentration occurred over most desert regions such as Saharan and Gobi deserts. The dust absorption is found to be sensitive to mineral chemical composition, particularly the fraction of strongly absorbing dust particles. The enhancement of polarization at the scattering angles exceeding 1200 is found for the nonspherical dust particles. If the polarization is neglected in the radiative transfer calculation, a maximum 50 percent error is introduced for the case of forward scattering and 25 percent error for the case of backscattering. We suggest that the application of polarimeter at the ultraviolet wavelengths has the great potential to improve the satellite retrievals of dust properties. Using refined optical model and radiative transfer model to calculate the solar radiative forcing of dust aerosols can reduce the uncertainties in aerosol radiative forcing assessment.

  13. Relative Sea Level Change in Western Alaska As Constructed from Satellite Altimetry and Repeat GPS Measurements.

    Science.gov (United States)

    DeGrandpre, K. G.; Freymueller, J. T.; Kinsman, N.

    2014-12-01

    Western Alaska is a remote region populated by small communities situated in low-lying coastal environments that are sensitive to variations in local relative sea level (RSL). RSL is the measurement of sea level relative to the local ground surface. Quantification of RSL variation requires measuring vertical velocities for both tectonic motion (onshore component) and the ocean surface (offshore component). Tide gauges in conjunction with tidal benchmarks record RSL, but in Western Alaska these datums are of short duration and too sparsely distributed both temporally and spatially to be able to accurately project RSL trends. Satellite altimetry is not suited for near shore estimates, but is used in this study because of the limited tide gauge coverage both spatially and temporally. During the summers of 2013 and 2014, campaign GPS surveys of geodetic benchmarks were undertaken to produce statistically significant velocity measurements of the tectonic component of sea level change for the Seward Peninsula, Yukon-Kuskokwim Delta, and Alaska Peninsula. Occupations of tidal benchmarks were also collected to compare historic tidal records from the mid-1900s to more recent data. Preliminary results from the GPS survey suggest regional subsidence of approximately 1-2 mm/yr of the Seward Peninsula, which supports one of the current glacial isostatic adjustment (GIA) models available for Western Alaska. The vertical velocity of the tectonic component and the satellite derived mean sea level trend will be coupled to produce a model of RSL change in Western Alaska that will be used to aid local communities in the development of adaptation strategies for changing coastal environments.

  14. Analysis of rain fade duration models for Earth-to-satellite path based on data measured in Malaysia

    Science.gov (United States)

    Dao, Hassan; Rafiqul, Islam Md; Al-Khateeb, Khalid A. S.

    2013-12-01

    Statistical analysis of rain fade duration is crucial information for system engineer to design and plan a fade mitigation technique (FMT) for the satellite communication system. An investigation is carried out based on data measured of one year period in Kuala Lumpur, Malaysia from satellite path of MEASAT3. This paper presents statistical analysis of measured fade duration on high elevation angle (77.4°) in Ku-band compared to three prediction models of fade duration. It is found that none of the models could predict measured fade duration distribution accurately.

  15. Analysis of rain fade duration models for Earth-to-satellite path based on data measured in Malaysia

    International Nuclear Information System (INIS)

    Statistical analysis of rain fade duration is crucial information for system engineer to design and plan a fade mitigation technique (FMT) for the satellite communication system. An investigation is carried out based on data measured of one year period in Kuala Lumpur, Malaysia from satellite path of MEASAT3. This paper presents statistical analysis of measured fade duration on high elevation angle (77.4°) in Ku-band compared to three prediction models of fade duration. It is found that none of the models could predict measured fade duration distribution accurately

  16. Quantifying Above-Cloud Aerosols through Integrating Multi-Sensor Measurements from A-Train Satellites

    Science.gov (United States)

    Zhang, Yan

    2012-01-01

    Quantifying above-cloud aerosols can help improve the assessment of aerosol intercontinental transport and climate impacts. Large-scale measurements of aerosol above low-level clouds had been generally unexplored until very recently when CALIPSO lidar started to acquire aerosol and cloud profiles in June 2006. Despite CALIPSO s unique capability of measuring above-cloud aerosol optical depth (AOD), such observations are substantially limited in spatial coverage because of the lidar s near-zero swath. We developed an approach that integrates measurements from A-Train satellite sensors (including CALIPSO lidar, OMI, and MODIS) to extend CALIPSO above-cloud AOD observations to substantially larger areas. We first examine relationships between collocated CALIPSO above-cloud AOD and OMI absorbing aerosol index (AI, a qualitative measure of AOD for elevated dust and smoke aerosol) as a function of MODIS cloud optical depth (COD) by using 8-month data in the Saharan dust outflow and southwest African smoke outflow regions. The analysis shows that for a given cloud albedo, above-cloud AOD correlates positively with AI in a linear manner. We then apply the derived relationships with MODIS COD and OMI AI measurements to derive above-cloud AOD over the whole outflow regions. In this talk, we will present spatial and day-to-day variations of the above-cloud AOD and the estimated direct radiative forcing by the above-cloud aerosols.

  17. Capabilities and uncertainties of aircraft measurements for the validation of satellite precipitation products – a virtual case study

    Directory of Open Access Journals (Sweden)

    Andrea Lammert

    2015-08-01

    Full Text Available Remote sensing sensors on board of research aircraft provide detailed measurements of clouds and precipitation which can be used as reference data to validate satellite products. Such satellite derived precipitation data using passive microwave radiometers with a resolution of typically 50×50km2$50\\times50\\,\\text{km}^2$ stands against high spatial and temporal resolved airborne measurements, but only along a chosen line. This paper focuses on analysis on the uncertainty arising from the different spatial resolution and coverage. Therefore we use a perfect model approach, with a high resolved forecast model yielding perfect virtual aircraft and satellite observations. The mean precipitation and standard deviation per satellite box were estimated with a Gaussian approach. The comparison of the mean values shows a high correlation of 0.92, but a very wide spread. As criterion to define good agreement between satellite mean and reference, we choose a deviation of one standard deviation of the virtual aircraft as threshold. Considering flight tracks in the range of 50 km (one overflight, the perfect agreement of satellite and aircraft observations is only detected in 65 % of the cases. To increase this low reliability the precipitation distributions of the virtual aircraft were fitted by a gamma density function. Using the same quality criterion, the usage of gamma density fit yields an improvement of the Aircraft reliability up to 80 %.

  18. Satellite Geomagnetism

    DEFF Research Database (Denmark)

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade...

  19. Exploration statistique des fluctuations temporelles et spatiales du champ d'impédance de sol et du champ acoustique

    OpenAIRE

    BAUME, O; GAUVREAU, B; Junker, F; Wackernagel, H.; BERENGIER, M; CHILES, JP

    2006-01-01

    L'influence des conditions atmosphériques sur la propagation du son est un point essentiel à considérer lorsque l'on cherche à estimer l'impact de sources sonores d'origine routière, ferroviaire ou industrielle. En effet, le phénomène de réfraction modifie la structure temporelle et spatiale du champ acoustique. Les gradients verticaux de célérité du son peuvent être considérés sur des périodes de l'ordre du 1/4 d'heure comme relativement stables et donc à ce titre représentatifs des conditio...

  20. Business-to-business marketing spoločnosti Champs, s.r.o.

    OpenAIRE

    Kasman, Tomáš

    2009-01-01

    The work dissertates about the specifics of the business to business marketing with an application in the Champs company. The theoretical part is focused on the definition of main differences between marketing on the consumer market and on the business market. Extra attention is dedicated to the marketing mix. On the one side the practical part is trying to create an appropriate marketing conception for the possible collaboration between Champs company and mBank - retail banking BRE Bank SA i...

  1. Methods of Evaluating Thermodynamic Properties of Landscape Cover Using Multispectral Reflected Radiation Measurements by the Landsat Satellite

    Directory of Open Access Journals (Sweden)

    Yuriy Puzachenko

    2013-09-01

    Full Text Available The paper discusses methods of evaluating thermodynamic properties of landscape cover based on multi-spectral measurements by the Landsat satellites. Authors demonstrate how these methods could be used for studying functionality of landscapes and for spatial interpolation of Flux NET system measurements.

  2. Global top-down smoke aerosol emissions estimation using satellite fire radiative power measurements

    Science.gov (United States)

    Ichoku, C.; Ellison, L.

    2013-10-01

    Biomass burning occurs seasonally in most vegetated parts of the world, consuming large amounts of biomass fuel, generating intense heat energy, and emitting corresponding amounts of smoke plumes that comprise different species of aerosols and trace gases. Accurate estimates of these emissions are required as model inputs to evaluate and forecast smoke plume transport and impacts on air quality, human health, clouds, weather, radiation, and climate. Emissions estimates have long been based on bottom-up approaches that are not only complex, but also fraught with compounding uncertainties. Fortunately, a series of recent studies have revealed that both the rate of biomass consumption and the rate of emission of aerosol particulate matter (PM) by open biomass burning are directly proportional to the rate of release of fire radiative energy (FRE), which is fire radiative power (FRP) that is measurable from satellite. This direct relationship enables the determination of coefficients of emission (Ce), which can be used to convert FRP or FRE to smoke aerosol emissions in the same manner as emission factors (EFs) are used to convert burned biomass to emissions. We have leveraged this relationship to generate the first global 1° × 1° gridded Ce product for smoke aerosol or total particulate matter (TPM) emissions using coincident measurements of FRP and aerosol optical thickness (AOT) from the Moderate-resolution Imaging Spectro-radiometer (MODIS) sensors aboard the Terra and Aqua satellites. This new Fire Energetics and Emissions Research version 1.0 (FEER.v1) Ce product has now been released to the community and can be obtained from http://feer.gsfc.nasa.gov/, along with the corresponding 1-to-1 mapping of their quality assurance (QA) flags that will enable the Ce values to be filtered by quality for use in various applications. The regional averages of Ce values for different ecosystem types were found to be in the ranges of: 16-21 g MJ-1 for savanna and grasslands

  3. Global atmospheric temperature monitoring with satellite microwave measurements - Method and results 1979-84

    Science.gov (United States)

    Spencer, Roy W.; Christy, John R.; Grody, Norman C.

    1990-01-01

    This paper describes a method for determining global atmospheric-temperature anomalies by means of satellite microwave radiometry. It is shown that microwave measurements of molecular oxygen thermal emission by the Microwave Sounding Units (MSUs) flying aboard the NOAA-6 and NOAA-7 can be used to monitor tropospheric temperature anomalies on global basis to a high level of precision. Comparisons between monthly MSU-derived hemispheric temperature anomalies with those computed from surface thermometer data show a very good agreement over the United States, although not for the hemispheres, especially the Southern Hemisphere. In this latter case, the poor agreement is ascribed to weaker thermal coupling between the ocean and the deep troposphere than that over the U.S. Annual anomalies for the hemispheres exhibit better correlations than do monthly anomalies.

  4. Using Satellite Measurements to Investigate Regional-scale Chemistry: The Case for Geostationary Observations

    Science.gov (United States)

    Fishman, Jack; Wozniak, Amy; Creilson, Jack

    2007-01-01

    One of the recommendations of the Decadal Survey that was recently released by the National Academy of Science was that of a geostationary platform from which to obtain trace gas measurements. The use of such a platform is particularly advantageous when applied to understanding the formation of regional air pollution. This study demonstrates the challenges of trying to utilize information from instruments on satellites in low-earth orbit (LEO). We also demonstrate the advantage gained through a simulation that would provide hourly observations. In this case study, we take advantage of the high resolution Level-2 orbital data available from the Ozone Monitoring Instrument (OMI), in conjunction with assimilated stratospheric column ozone fields, to evaluate if meaningful tropospheric ozone information can be obtained on a regional scale. We focus on a period on late June 2005 when a widespread pollution episode enveloped the Houston metropolitan area as well as a large region in southeast Texas.

  5. Multi-decadal satellite measurements of passive and eruptive volcanic SO2 emissions

    Science.gov (United States)

    Carn, Simon; Yang, Kai; Krotkov, Nickolay; Prata, Fred; Telling, Jennifer

    2015-04-01

    Periodic injections of sulfur gas species (SO2, H2S) into the stratosphere by volcanic eruptions are among the most important, and yet unpredictable, drivers of natural climate variability. However, passive (lower tropospheric) volcanic degassing is the major component of total volcanic emissions to the atmosphere on a time-averaged basis, but is poorly constrained, impacting estimates of global emissions of other volcanic gases (e.g., CO2). Stratospheric volcanic emissions are very well quantified by satellite remote sensing techniques, and we report ongoing efforts to catalog all significant volcanic SO2 emissions into the stratosphere and troposphere since 1978 using measurements from the ultraviolet (UV) Total Ozone Mapping Spectrometer (TOMS; 1978-2005), Ozone Monitoring Instrument (OMI; 2004 - present) and Ozone Mapping and Profiler Suite (OMPS; 2012 - present) instruments, supplemented by infrared (IR) data from HIRS, MODIS and AIRS. The database, intended for use as a volcanic forcing dataset in climate models, currently includes over 600 eruptions releasing a total of ~100 Tg SO2, with a mean eruption discharge of ~0.2 Tg SO2. Sensitivity to SO2 emissions from smaller eruptions greatly increased following the launch of OMI in 2004, but uncertainties remain on the volcanic flux of other sulfur species other than SO2 (H2S, OCS) due to difficulty of measurement. Although the post-Pinatubo 1991 era is often classified as volcanically quiescent, many smaller eruptions (Volcanic Explosivity Index [VEI] 3-4) since 2000 have injected significant amounts of SO2 into the upper troposphere - lower stratosphere (UTLS), peaking in 2008-2011. We also show how even smaller (VEI 2) tropical eruptions can impact the UTLS and sustain above-background stratospheric aerosol optical depth, thus playing a role in climate forcing on short timescales. To better quantify tropospheric volcanic degassing, we use ~10 years of operational SO2 measurements by OMI to identify the

  6. Changes in airborne bacteria during a tropical burning season are correlated with satellite aerosol measurements

    Science.gov (United States)

    Mims, F., III

    Agricultural burning in the tropics generates vast quantities of smoke that can blanket entire countries and attenuate photosynthetically active radiation (PAR). Thick smoke also reduces the solar ultraviolet-B wavelengths that synthesize vitamin-D precur- sors in vertebrates and suppress many viruses and non-pigmented bacteria. As many pathogenic bacteria are non-pigmented, the latter finding may explain some of the in- creases in respiratory and other diseases that occur during episodes of severe aerosol loading. At Alta Floresta, Brazil, during the 1997 burning season, the correlation (r^2) of UV-B measured at the surface with the ratio of non-pigmented to total airborne bacteria colony forming units (CFUs) was 0.83. The correlation of the aerosol index measured from orbit by TOMS with the ratio of non-pigmented to total airborne bac- teria CFUs was 0.71. These findings suggest the application of satellite measurements of optical depth as a first approximation epidemiological tool for remote regions that have seasonally smokey skies. Further comparisons are warranted of surface measure- ments of airborne bacteria, UV-B and PAR with TOMS and MODIS observations of optical depth during severe air pollution events.

  7. Surface Net Solar Radiation Estimated from Satellite Measurements: Comparisons with Tower Observations

    Science.gov (United States)

    Li, Zhanqing; Leighton, H. G.; Cess, Robert D.

    1993-01-01

    A parameterization that relates the reflected solar flux at the top of the atmosphere to the net solar flux at the surface in terms of only the column water vapor amount and the solar zenith angle was tested against surface observations. Net surface fluxes deduced from coincidental collocated satellite-measured radiances and from measurements from towers in Boulder during summer and near Saskatoon in winter have mean differences of about 2 W/sq m, regardless of whether the sky is clear or cloudy. Furthermore, comparisons between the net fluxes deduced from the parameterization and from surface measurements showed equally good agreement when the data were partitioned into morning and afternoon observations. This is in contrast to results from an empirical clear-sky algorithm that is unable to account adequately for the effects of clouds and that shows, at Boulder, a distinct morning to afternoon variation, which is presumably due to the predominance of different cloud types throughout the day. It is also demonstrated that the parameterization may be applied to irradiances at the top of the atmosphere that have been temporally averaged by using the temporally averaged column water vapor amount and the temporally averaged cosine of the solar zenith angle. The good agreement between the results of the parameterization and surface measurements suggests that the algorithm is a useful tool for a variety of climate studies.

  8. Future Satellite Gravimetry and Earth Dynamics

    CERN Document Server

    Flury, Jakob

    2005-01-01

    Currently, a first generation of dedicated satellite missions for the precise mapping of the Earth’s gravity field is in orbit (CHAMP, GRACE, and soon GOCE). The gravity data from these satellite missions provide us with very new information on the dynamics of planet Earth. In particular, on the mass distribution in the Earth’s interior, the entire water cycle (ocean circulation, ice mass balance, continental water masses, and atmosphere), and on changes in the mass distribution. The results are fascinating, but still rough with respect to spatial and temporal resolution. Technical progress in satellite-to-satellite tracking and in gravity gradiometry will allow more detailed results in the future. In this special issue, Earth scientists develop visions of future applications based on follow-on high-precision satellite gravimetry missions.

  9. The Italian software for GPS radio occultation: validation using COSMIC and CHAMP data

    Science.gov (United States)

    Perona, G.; Notarpietro, R.

    2009-04-01

    The GPS Radio Occultation (RO) is a remote sensing technique for the profiling of atmospheric parameters. It is based on the inversion of L1 and L2 GPS signals collected on-board a Low Earth Orbit (LEO) platform, when the transmitter rises or sets beyond the Earth's limb. The relative movement of both satellites allows a "quasi" vertical atmospheric scan and the profiles extracted using this technique are characterized by a high vertical resolution and a high accuracy. The RO technique is operatively applied for meteorological purposes since such observations can easily be assimilated into Numerical Weather Prediction models. Anyway it is very useful also for climatological purposes, for gravity wave observations and for Space Weather applications. Actually, three operative satellite missions are carrying on-board GPS receivers for RO purposes: the German CHAMP satellite, the European METOP-1 mission and the USA/Taiwan COSMIC constellation. Several other missions are planned for the next future. In particular, during the 2009 Spring season, the Indian OCEANSAT-2 mission carrying on-board the Italian ROSA (Radio Occultation Sounder of the Atmosphere) GPS receiver is expected to be launched. In the framework of this opportunity, the Italian Space Agency (ASI) founded a pool of Italian Universities and Research Centers for the implementation of the overall (and state-of-the-art) RO processing chain which is called ROSA-ROSSA (ROSA-Research and Operational Satellite and Software Activities). The ROSA-ROSSA will be integrated in the operative ROSA Ground Segment by an Italian Software farm (INNOVA, located in Matera, Italy), and this ground segment will operate in Italy (at the ASI Space Geodesy Center, near Matera) and in India (at the Indian National Remote Sensing Agency, near Hyderabad) starting from the 2009 Spring season. The "Base" version of the ROSA-ROSSA software was delivered to the Industrial partner at the end of 2008 for its integration inside the Italian

  10. Laboratory Measurements of the Dielectronic Recombination Satellite Transitions of He-Like FE XXV and H-Like FE XXVI

    Science.gov (United States)

    Gu, M. F.; Beiersdorfer, P.; Brown, G. V.; Graf, A.; Kelley, R. I.; Kilbourne, C. A.; Porter, F. S.; Kahn, S. M,

    2012-01-01

    We present laboratory spectra of dielectronic recombination (DR) satellite transitions attached to the He-like and H-like iron resonance lines obtained with the NASA Goddard Space Flight Center X-ray calorimeter and produced by a thermal plasma simu1ation technique on the EBIT-I electron beam ion trap at the Lawrence Livermore National Laboratory. We demonstrate that the calorimeter has sufficient spectral resolution in the 6-9 keV range to provide reliable measurements not only of standard DR satellite to resonance line intensities but also of DR satellite to DR satellite ratios that can be used to diagnose nonthermal electron distributions. Electron temperatures derived from the measured line intensities are consistent with the temperature of the simulated plasma. Temperature measurements based on DR satellite transitions have significant advantages over those based on collisional ionization equilibrium or continuum shape. Thus, successful demonstration of this method with the X-ray calorimeter is an important step fur its application in X-ray astronomy.

  11. Vertical profiles of aerosol optical properties over central Illinois and comparison with surface and satellite measurements

    Directory of Open Access Journals (Sweden)

    P. J. Sheridan

    2012-12-01

    Full Text Available Between June 2006 and September 2009, an instrumented light aircraft measured over 400 vertical profiles of aerosol and trace gas properties over eastern and central Illinois. The primary objectives of this program were to (1 measure the in situ aerosol properties and determine their vertical and temporal variability and (2 relate these aircraft measurements to concurrent surface and satellite measurements. The primary profile location was within 15 km of the NOAA/ESRL surface aerosol monitoring station near Bondville, Illinois. Identical instruments at the surface and on the aircraft ensured that the data from both platforms would be directly comparable and permitted a determination of how representative surface aerosol properties were of the lower column. Aircraft profiles were also conducted occasionally at two other nearby locations to increase the frequency of A-Train satellite underflights for the purpose of comparing in situ and satellite-retrieved aerosol data. Measurements of aerosol properties conducted at low relative humidity over the Bondville site compare well with the analogous surface aerosol data and do not indicate any major sampling issues or that the aerosol is radically different at the surface compared with the lowest flyby altitude of ~ 240 m above ground level. Statistical analyses of the in situ vertical profile data indicate that aerosol light scattering and absorption (related to aerosol amount decreases substantially with increasing altitude. Parameters related to the nature of the aerosol (e.g., single-scattering albedo, Ångström exponent, etc., however, are relatively constant throughout the mixed layer, and do not vary as much as the aerosol amount throughout the profile. While individual profiles often showed more variability, the median in situ single-scattering albedo was 0.93–0.95 for all sampled altitudes. Several parameters (e.g., submicrometer scattering fraction, hemispheric backscattering fraction, and

  12. Satellite measurements of large-scale air pollution - Measurements of forest fire smoke

    Science.gov (United States)

    Ferrare, Richard A.; Kaufman, Yoram J.; Fraser, Robert S.

    1990-01-01

    The transport, optical properties, total mass, and removal of smoke produced by forest fires in western Canada during late July and early August 1982 are studied using NOAA 7 AVHRR data. Color composite imagery is produced to track the movement of the smoke over Canada and the U.S. as the smoke traveled thousands of km from the source region. Smoke optical thickness, particle size, and single scattering albedo are computed using radiances measured by AVHRR bands 1 and 2. Results show that smoke optical thickness ranged from less that 0.1 to greater than 3.7 and the geometric mean mass radii ranged from 300 to 900 nm. The smoke single scattering albedo ranged from 0.9 to nearly 1.0. The total smoke mass over the eastern U.S. ranged from 0.1 to 0.5 Tg, which is close to the 0.5 Tg estimated from the forest fuel content. The smoke lifetime is estimated to be between 15 and 20 days.

  13. Radio Wave Propagation Measurements and Modeling for Land Mobile Satellite Systems

    OpenAIRE

    Mousselon, Laure

    2003-01-01

    The performance of a mobile satellite communications link is conditioned by the characteristics of the propagation path between a satellite and mobile users. The most important propagation effect in land mobile satellite system is roadside attenuation of the signals due to vegetation or urban structures. System designers should have the most reliable information about the statistics of the propagation channel to build reliable systems that can compensate for bad propagation conditions. I...

  14. First satellite measurements of chemical changes in coincidence with sprite activity

    Science.gov (United States)

    Arnone, Enrico; São Sabbas, Fernanda; Kero, Antti; Soula, Serge; Carlotti, Massimo; Chanrion, Olivier; Dinelli, Bianca Maria; Papandrea, Enzo; Castelli, Elisa; Neubert, Torsten

    2010-05-01

    The last twenty years have seen the discovery of electric discharges in the Earth's atmosphere above thunderstorms, the so-called sprites and jets. It has been suggested that they impact the atmospheric chemistry and possibly affect the ozone layer through their repeated occurrence. Whereas theoretical studies and laboratory experiments suggest enhancement of such gasses as nitrogen oxides by up to hundreds of percent within sprites, a definitive detection of their chemical effects have to date been unsuccessful. In this paper, we report on the first measurements of atmospheric chemical perturbations recorded in coincidence with sprite activity. A striking event occurred on 25 August 2003 when the MIPAS spectrometer onboard the Envisat satellite recorded spectroscopic measurements soon after a sequence of 11 sprites observed above Corsica (France) by Eurosprite ground facilities (details of the convective system are discussed in a companion paper by São Sabbas et al.). The measurements show an enhancement of ambient nitrous oxide by 80% at 52 km altitude in the region above the parent thunderstorm. The recorded chemical changes imply sprites can exert significant modification of the atmospheric chemistry at a regional scale, confirming model and laboratory predictions of sprite-chemistry, and requiring a new estimate of their global impact. The results of the analysis and their implications are discussed.

  15. Comprehensive Spectral Signal Investigation of a Larch Forest Combining - and Satellite-Based Measurements

    Science.gov (United States)

    Landmann, J. M.; Rutzinger, M.; Bremer, M.; chmidtner, K.

    2016-06-01

    Collecting comprehensive knowledge about spectral signals in areas composed by complex structured objects is a challenging task in remote sensing. In the case of vegetation, shadow effects on reflectance are especially difficult to determine. This work analyzes a larch forest stand (Larix decidua MILL.) in Pinnis Valley (Tyrol, Austria). The main goal is extracting the larch spectral signal on Landsat 8 (LS8) Operational Land Imager (OLI) images using ground measurements with the Cropscan Multispectral Radiometer with five bands (MSR5) simultaneously to satellite overpasses in summer 2015. First, the relationship between field spectrometer and OLI data on a cultivated grassland area next to the forest stand is investigated. Median ground measurements for each of the grassland parcels serve for calculation of the mean difference between the two sensors. Differences are used as "bias correction" for field spectrometer values. In the main step, spectral unmixing of the OLI images is applied to the larch forest, specifying the larch tree spectral signal based on corrected field spectrometer measurements of the larch understory. In order to determine larch tree and shadow fractions on OLI pixels, a representative 3D tree shape is used to construct a digital forest. Benefits of this approach are the computational savings compared to a radiative transfer modeling. Remaining shortcomings are the limited capability to consider exact tree shapes and nonlinear processes. Different methods to implement shadows are tested and spectral vegetation indices like the Normalized Difference Vegetation Index (NDVI) and Greenness Index (GI) can be computed even without considering shadows.

  16. ALGORITHM OF SAR SATELLITE ATTITUDE MEASUREMENT USING GPS AIDED BY KINEMATIC VECTOR

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, in order to improve the accuracy of the Synthetic Aperture Radar (SAR)satellite attitude using Global Positioning System (GPS) wide-band carrier phase, the SAR satellite attitude kinematic vector and Kalman filter are introduced. Introducing the state variable function of GPS attitude determination algorithm in SAR satellite by means of kinematic vector and describing the observation function by the GPS wide-band carrier phase, the paper uses the Kalman filter algorithm to obtian the attitude variables of SAR satellite. Compared the simulation results of Kalman filter algorithm with the least square algorithm and explicit solution, it is indicated that the Kalman filter algorithm is the best.

  17. Integration of satellite data and in situ measurements to improve coastal water quality monitoring

    Science.gov (United States)

    Lacava, Teodosio

    2015-04-01

    Coastal areas are "sensitive" zones exposed to different natural hazards and anthropic risks. The increasing level of urbanization, the even more irrational exploitation of those areas and, more generally, climate changes are some of the most relevant phenomena able to strongly change such sites. For these reasons, it is necessary to implement an adequate water quality monitoring system able to give a reliable description of water status for reducing the negative effects which coastal marine waters are exposed to. Remote sensing data offer a relevant contribution in this framework, providing, with a quite good level of accuracy, information about the spatial distribution of sea water constituents over large areas with high temporal rates and at relatively low costs. On the other hand, in situ measurements allow to analyze the history of these elements at a very small scale, both in terms of investigated area and period. The integration of these two kind of information may improve the monitoring in the space-time domain of a specific area, allowing also for a calibration, at local scale, of the satellite data/products. In this paper results achieved in such a context while carrying out two projects on Mediterranean Sea water quality will be described. More than 15 years of MODIS Ocean Colour data have been analyzed and compared with different specific in-situ and airborne data concerning different areas of Mediterranean Sea collected in the framework of the following projects: IOSMOS (IOnian Sea water quality MOnitoring by Satellite data, OP ERDF Basilicata) and MOMEDAS (MOnitoraggio delle acque del mar MEditerraneo mediante DAti Satellitari, OP Basilicata ESF). Specifically, preliminary achievements regarding the analysis of Chlorophyll-a (Chl-a) and diffuse attenuation coefficient at 490 nm (Kd 490) products as well as suspended sediment material (SSM) transport phenomena and the Sea Surface Temperature (SST) variations occurring in the analyzed areas will be

  18. Satellite-based RAR performance simulation for measuring directional ocean wave spectrum based on SAR inversion spectrum

    Institute of Scientific and Technical Information of China (English)

    REN Lin; MAO Zhihua; HUANG Haiqing; GONG Fang

    2010-01-01

    Some missions have been carried out to measure wave directional spectrum by synthetic aperture radar (SAR) and airborne real aperture radar (RAR) at a low incidence. Both them have their own advantages and limitations. Scientists hope that SAR and satellite-based RAR can complement each other for the research on wave properties in the future. For this study, the authors aim to simulate the satellite-based RAR system to validate performance for measuring the directional wave spectrum. The principal measurements are introduced and the simulation methods based on the one developed by Hauser are adopted and slightly modified. To enhance the authenticity of input spectrum and the wave spectrum measuring consistency for SAR and satellite-based RAR, the wave height spectrum inversed from Envisat ASAR data by cross spectrum technology is used as the input spectrum of the simulation system. In the process of simulation, the sea surface, backscattering signal, modulation spectrum and the estimated wave height spectrum are simulated in each look direction. Directional wave spectrum are measured based on the simulated observations from 0° to 360~. From the estimated wave spectrum, it has an 180° ambiguity like SAR, but it has no special high wave number cut off in all the direction. Finally, the estimated spectrum is compared with the input one in terms of the dominant wave wavelength, direction and SWH and the results are promising. The simulation shows that satellite-based RAR should be capable of measuring the directional wave properties. Moreover, it indicates satellite-based RAR basically can measure waves that SAR can measure.

  19. Improving the Accuracy of Satellite Sea Surface Temperature Measurements by Explicitly Accounting for the Bulk-Skin Temperature Difference

    Science.gov (United States)

    Castro, Sandra L.; Emery, William J.

    2002-01-01

    The focus of this research was to determine whether the accuracy of satellite measurements of sea surface temperature (SST) could be improved by explicitly accounting for the complex temperature gradients at the surface of the ocean associated with the cool skin and diurnal warm layers. To achieve this goal, work centered on the development and deployment of low-cost infrared radiometers to enable the direct validation of satellite measurements of skin temperature. During this one year grant, design and construction of an improved infrared radiometer was completed and testing was initiated. In addition, development of an improved parametric model for the bulk-skin temperature difference was completed using data from the previous version of the radiometer. This model will comprise a key component of an improved procedure for estimating the bulk SST from satellites. The results comprised a significant portion of the Ph.D. thesis completed by one graduate student and they are currently being converted into a journal publication.

  20. Signature of range observable in non-dynamical Chern-Simons modified gravity and the measurements with satellite-satellite tracking missions. Theoretical Studies

    CERN Document Server

    Qiang, Li-E

    2014-01-01

    Having great accuracy in the range and range rate measurements, the operating GRACE mission and the planed GRACE Follow On mission can in principle be employed to place strong constraints on certain relativistic gravity theories. In this paper, we work out in details the range observable in the non-dynamical Chern-Simons modified gravity for these Satellite-Satellite Tracking measurements. We find out that an characteristic time accumulating signal appears in the range observable in the non-dynamical Chern-Simons gravity, which has no analogy found in the standard metric theories of gravity. The magnitude of this Chern-Simons range signal will reach to a few times of $(\\frac{\\dot{\\theta}}{100r})meters$ for each free flight of these SST missions, here $\\dot{\\theta}$ measures the length scale of the theory and $r$ denotes the orbital radius of the SST mission. Therefore, with the 12 years data from the GRACE mission and the proper data analysis methods, one expects that the mass scale of the non-dynamical CS gr...

  1. A new ENSO index derived from satellite measurements of column ozone

    Directory of Open Access Journals (Sweden)

    J. R. Ziemke

    2010-02-01

    Full Text Available Column Ozone measured in tropical latitudes from Nimbus 7 TOMS, Earth Probe TOMS, NOAA SBUV, and Aura OMI satellite instruments are used to derive an El Niño-Southern Oscillation (ENSO index. This index, which covers a time period from 1979 to the present, is defined as the Ozone ENSO Index (OEI and is the first developed from atmospheric trace gas measurements. Using a data mining technique with existing ENSO indices of surface pressure and sea-surface temperature, the OEI is constructed by first averaging monthly mean column ozone over two broad regions in the western and eastern Pacific and taking their difference. This differencing yields a self-calibrating ENSO index which is independent of individual instrument calibration offsets and drifts in measurements over the long record. The combined Aura OMI and MLS ozone data confirm that zonal variability in total column ozone in the tropics caused by ENSO events lies almost entirely in the troposphere. As a result, the OEI can be derived directly from total column ozone instead of tropospheric column ozone. For clear-sky ozone measurements a +1 K change in Nino 3.4 index corresponds to +2.9 DU (Dobson Unit change in the OEI, while a +1 hPa change in SOI coincides with a −1.7 DU change in the OEI. For ozone measurements under all cloud conditions these numbers are +2.4 DU and −1.4 DU, respectively. As an ENSO index based upon ozone, it is potentially useful in evaluating climate models predicting long term changes in ozone and other trace gases.

  2. Spin dynamics of the LAGEOS satellite in support of a measurement of the Earth's gravitomagnetism

    Energy Technology Data Exchange (ETDEWEB)

    Habib, S. (Theoretical Astrophysics Group (T-6, MS B288), Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)); Holz, D.E. (Department of Physics, Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637 (United States) Theoretical Astrophysics Group (T-6, MS B288), Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)); Kheyfets, A. (Department of Mathematics, North Carolina State University, Raleigh, North Carolina 27695-8205 (United States)); Matzner, R.A. (Center for Relativity and Physics Department, The University of Texas at Austin, Austin, Texas 78712-1081 (United States) Applied Research Laboratories, The University of Texas at Austin, P.O. Box 8029, Austin, Texas 78713-8209 (United States)); Miller, W.A. (Theoretical Astrophysics Group (T-6, MS B288), Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States) Astrodynamics Bran

    1994-11-15

    LAGEOS is an accurately tracked, dense spherical satellite covered with 426 retroreflectors. Ciufolini has suggested the launch of an additional satellite (LAGEOS-3) into an orbit supplementary to that of the 1976-launched LAGEOS-1. In addition to providing a more accurate real-time measurement of the Earth's length of day and polar wobble, this paired-satellite experiment would provide the first direct measurement of the general relativistic frame-dragging effect. Of the five dominant error sources in this experiment, the largest one involves surface forces on the satellite, and their consequent impact on the orbital nodal precession. The surface forces are a function of the spin dynamics of the satellite. Consequently, we undertake here a theoretical effort to model the spin dynamics of LAGEOS. In this paper we derive, and solve numerically, a set of Euler equations that evolve the angular momentum vector for a slightly oblate spheroid of brass orbiting an Earth-like mass, idealized as being a perfect sphere and having a perfect polar-oriented dipole magnetic field. We have identified three phases of the rotational dynamics---a fast spin phase, a spin-orbit resonance phase, and an asymptotic (tidally locked) phase. From our numerical runs we give analytic expressions for this tidally locked phase.

  3. The use of visible-channel data from NOAA satellites to measure total ozone amount over Antarctica

    Science.gov (United States)

    Boime, Robert D.; Warren, Steven G.; Gruber, Arnold

    1994-01-01

    Accurate, detailed maps of total ozone were not available until the launch of the Total Ozone Mapping Spectrometer (TOMS) in late 1978. However, the Scanning Radiometer (SR), an instrument on board the NOAA series satellites during the 1970s, had a visible channel that overlapped closely with the Chappuis absorption band of ozone. We are investigating whether data from the SR can be used to map Antarctic ozone prior to 1978. The method is being developed with 1980s data from the Advanced Very High Resolution Radiometer (AVHRR), which succeeded the SR on the NOAA polar-orbiting satellites. Visible-derived total ozone maps can then be compared able on the NOAA satellites, which precludes the use of a differential absorption technique to measure ozone. Consequently, our method works exclusively over scenes whose albedos are large and unvarying, i.e. scenes that contain ice sheets and/or uniform cloud-cover. Initial comparisons of time series for October-December 1987 at locations in East Antarctica show that the visible absorption by ozone in measurable and that the technique may be usable for the 1970s, but with much less accuracy than TOMS. This initial test assumes that clouds, snow, and ice all reflect the same percentage of visible light towards the satellite, regardless of satellite position or environmental conditions. This assumption is our greatest source of error. To improve the accuracy of ozone retrievals, realistic anisotropic reflectance factors are needed, which are strongly influenced by cloud and snow surface features.

  4. Validation of ACE-FTS satellite data in the upper troposphere/lower stratosphere (UTLS) using non-coincident measurements

    OpenAIRE

    Hegglin, M. I.; Bernath, P. F.; C. D. Boone; W. H. Daffer; Hoor, P.; Manney, G. L.; Schiller, C.; Strong, K.; K. A. Walker

    2008-01-01

    CO, O3, and H2O data in the upper troposphere/lower stratosphere (UTLS) measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on Canada's SCISAT-1 satellite are validated using aircraft and ozonesonde measurements. In the UTLS, validation of chemical trace gas measurements is a challenging task due to small-scale variability in the tracer fields, strong gradients of the tracers across the tropopause, and sc...

  5. Data fusion with artificial neural networks (ANN) for classification of earth surface from microwave satellite measurements

    Science.gov (United States)

    Lure, Y. M. Fleming; Grody, Norman C.; Chiou, Y. S. Peter; Yeh, H. Y. Michael

    1993-01-01

    A data fusion system with artificial neural networks (ANN) is used for fast and accurate classification of five earth surface conditions and surface changes, based on seven SSMI multichannel microwave satellite measurements. The measurements include brightness temperatures at 19, 22, 37, and 85 GHz at both H and V polarizations (only V at 22 GHz). The seven channel measurements are processed through a convolution computation such that all measurements are located at same grid. Five surface classes including non-scattering surface, precipitation over land, over ocean, snow, and desert are identified from ground-truth observations. The system processes sensory data in three consecutive phases: (1) pre-processing to extract feature vectors and enhance separability among detected classes; (2) preliminary classification of Earth surface patterns using two separate and parallely acting classifiers: back-propagation neural network and binary decision tree classifiers; and (3) data fusion of results from preliminary classifiers to obtain the optimal performance in overall classification. Both the binary decision tree classifier and the fusion processing centers are implemented by neural network architectures. The fusion system configuration is a hierarchical neural network architecture, in which each functional neural net will handle different processing phases in a pipelined fashion. There is a total of around 13,500 samples for this analysis, of which 4 percent are used as the training set and 96 percent as the testing set. After training, this classification system is able to bring up the detection accuracy to 94 percent compared with 88 percent for back-propagation artificial neural networks and 80 percent for binary decision tree classifiers. The neural network data fusion classification is currently under progress to be integrated in an image processing system at NOAA and to be implemented in a prototype of a massively parallel and dynamically reconfigurable Modular

  6. The importance of transport model uncertainties for the estimation of CO2 sources and sinks using satellite measurements

    NARCIS (Netherlands)

    Houweling, S.; Aben, I.; Breon, F.-M.; Chevallier, F.; Deutscher, N.; Engelen, R.; Gerbig, C.; Griffith, D.; Hungershoefer, K.; Macatangay, R.; Marshall, J.; Notholt, J.; Peters, W.; Serrar, S.

    2010-01-01

    This study presents a synthetic model intercomparison to investigate the importance of transport model errors for estimating the sources and sinks of CO2 using satellite measurements. The experiments were designed for testing the potential performance of the proposed CO2 lidar A-SCOPE, but also appl

  7. Multi-decadal record of ice dynamics on Daugaard Jensen Gletscher, East Greenland, from satellite imagery and terrestrial measurements

    DEFF Research Database (Denmark)

    Stearns, L.A.; Hamilton, G.S.; Reeh, Niels

    2005-01-01

    The history of ice velocity and calving front position of Daugaard Jensen Gletscher, a large outlet glacier in East Greenland, is reconstructed from field measurements, aerial photography and satellite imagery for the period 1950-2001. The calving terminus of the glacier has remained in approxima...

  8. A New Time Measurement Method Using a High-End Global Navigation Satellite System to Analyze Alpine Skiing

    Science.gov (United States)

    Supej, Matej; Holmberg, Hans-Christer

    2011-01-01

    Accurate time measurement is essential to temporal analysis in sport. This study aimed to (a) develop a new method for time computation from surveyed trajectories using a high-end global navigation satellite system (GNSS), (b) validate its precision by comparing GNSS with photocells, and (c) examine whether gate-to-gate times can provide more…

  9. Surface energy balance and actual evapotranspiration of the transboundary Indus Basin estimated from satellite measurements and the ETLook model

    NARCIS (Netherlands)

    Bastiaansen, W.G.M.; Cheema, M.J.M.; Immerzeel, W.W.; Miltenburg, I.J.; Pelgrum, H.

    2012-01-01

    The surface energy fluxes and related evapotranspiration processes across the Indus Basin were estimated for the hydrological year 2007 using satellite measurements. The new ETLook remote sensing model (version 1) infers information on actual Evaporation (E) and actual Transpiration (T) from combine

  10. Comparison of mapped and measured total ionospheric electron content using global positioning system and beacon satellite observations

    International Nuclear Information System (INIS)

    Total ionospheric electron contents (TEC) were measured by global positioning system (GPS) dual-frequency receivers developed by the Jet Propulsion Laboratory. The measurements included P-code (precise ranging code) and carrier phase data for six GPS satellites during multiple five-hour observing sessions. A set of these GPS TEC measurements were mapped from the GPS lines of sight to the line of sight of a Faraday beacon satellite by statistically fitting the TEC data to a simple model of the ionosphere. The mapped GPS TEC values were compared with the Faraday rotation measurements. Because GPS transmitter offsets are different for each satellite and because some GPS receiver offsets were uncalibrated, the sums of the satellite and receiver offsets were estimated simultaneously with the TEC in a least squares procedure. The accuracy of this estimation procedure is evaluated indicating that the error of the GPS-determined line of sight TEC can be at or below 1 x 10 to the 16th el/sq cm. Consequently, the current level of accuracy is comparable to the Faraday rotation technique; however, GPS provides superior sky coverage. 15 references

  11. A method for monitoring glacier mass balance using satellite albedo measurements: application to Vatnajškull, Iceland

    NARCIS (Netherlands)

    Oerlemans, J.; Ruyter de Wildt, Martijn Sybren de; Björnsson, H.

    2002-01-01

    We compare satellite albedo images of Vatnajökull, Iceland, with massbalance measurements for the years 1991-99. We find that the equilibrium line is mostly not visible when it is located above its position of the previous year(s). Equilibrium-line detection is further hindered by clouds and a gradu

  12. Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: influence of local factors

    Directory of Open Access Journals (Sweden)

    B. Revilla-Romero

    2014-07-01

    Full Text Available One of the main challenges for global hydrological modelling is the limited availability of observational data for calibration and model verification. This is particularly the case for real time applications. This problem could potentially be overcome if discharge measurements based on satellite data were sufficiently accurate to substitute for ground-based measurements. The aim of this study is to test the potentials and constraints of the remote sensing signal of the Global Flood Detection System for converting the flood detection signal into river discharge values. The study uses data for 322 river measurement locations in Africa, Asia, Europe, North America and South America. Satellite discharge measurements were calibrated for these sites and a validation analysis with in situ discharge was performed. The locations with very good performance will be used in a future project where satellite discharge measurements are obtained on a daily basis to fill the gaps where real time ground observations are not available. These include several international river locations in Africa: Niger, Volta and Zambezi rivers. Analysis of the potential factors affecting the satellite signal was based on a classification decision tree (Random Forest and showed that mean discharge, climatic region, land cover and upstream catchment area are the dominant variables which determine good or poor performance of the measurement sites. In general terms, higher skill scores were obtained for locations with one or more of the following characteristics: a river width higher than 1 km; a large floodplain area and in flooded forest; with a potential flooded area greater than 40%; sparse vegetation, croplands or grasslands and closed to open and open forest; Leaf Area Index > 2; tropical climatic area; and without hydraulic infrastructures. Also, locations where river ice cover is seasonally present obtained higher skill scores. The work provides guidance on the best

  13. Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: influence of local factors

    Science.gov (United States)

    Revilla-Romero, B.; Thielen, J.; Salamon, P.; De Groeve, T.; Brakenridge, G. R.

    2014-11-01

    One of the main challenges for global hydrological modelling is the limited availability of observational data for calibration and model verification. This is particularly the case for real-time applications. This problem could potentially be overcome if discharge measurements based on satellite data were sufficiently accurate to substitute for ground-based measurements. The aim of this study is to test the potentials and constraints of the remote sensing signal of the Global Flood Detection System for converting the flood detection signal into river discharge values. The study uses data for 322 river measurement locations in Africa, Asia, Europe, North America and South America. Satellite discharge measurements were calibrated for these sites and a validation analysis with in situ discharge was performed. The locations with very good performance will be used in a future project where satellite discharge measurements are obtained on a daily basis to fill the gaps where real-time ground observations are not available. These include several international river locations in Africa: the Niger, Volta and Zambezi rivers. Analysis of the potential factors affecting the satellite signal was based on a classification decision tree (random forest) and showed that mean discharge, climatic region, land cover and upstream catchment area are the dominant variables which determine good or poor performance of the measurement sites. In general terms, higher skill scores were obtained for locations with one or more of the following characteristics: a river width higher than 1km; a large floodplain area and in flooded forest, a potential flooded area greater than 40%; sparse vegetation, croplands or grasslands and closed to open and open forest; leaf area index > 2; tropical climatic area; and without hydraulic infrastructures. Also, locations where river ice cover is seasonally present obtained higher skill scores. This work provides guidance on the best locations and limitations

  14. Signature of biased range in the non-dynamical Chern-Simons modified gravity and its measurements with satellite-satellite tracking missions: theoretical studies

    International Nuclear Information System (INIS)

    Having great accuracy in the range and range rate measurements, the GRACE mission and the planed GRACE follow on mission can in principle be employed to place strong constraints on certain relativistic gravitational theories. In this paper, we work out the range observable of the non-dynamical Chern-Simons modified gravity for the satellite-to-satellite tracking (SST) measurements. We find out that a characteristic time accumulating range signal appears in non-dynamical Chern-Simons gravity, which has no analogue found in the standard parity-preserving metric theories of gravity. The magnitude of this Chern-Simons range signal will reach a few times of χ cm for each free flight of these SST missions, here χ is the dimensionless post-Newtonian parameter of the non-dynamical Chern-Simons theory. Therefore, with the 12 years data of the GRACE mission, one expects that the mass scale MCS = (4ℎc)/(χa) of the non-dynamical Chern-Simons gravity could be constrained to be larger than 1.9 x 10.9 eV. For the GRACE FO mission that scheduled to be launched in 2017, the much stronger bound that MCS ≥ 5 x 10-7 eV is expected. (orig.)

  15. Signature of biased range in the non-dynamical Chern-Simons modified gravity and its measurements with satellite-satellite tracking missions: theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Li-E [Chang' an University, Department of Geophysics, College of Geology Engineering and Geomatics, Xi' an (China); Xu, Peng [Chinese Academy of Sciences, Academy of Mathematics and Systems Science, Beijing (China)

    2015-08-15

    Having great accuracy in the range and range rate measurements, the GRACE mission and the planed GRACE follow on mission can in principle be employed to place strong constraints on certain relativistic gravitational theories. In this paper, we work out the range observable of the non-dynamical Chern-Simons modified gravity for the satellite-to-satellite tracking (SST) measurements. We find out that a characteristic time accumulating range signal appears in non-dynamical Chern-Simons gravity, which has no analogue found in the standard parity-preserving metric theories of gravity. The magnitude of this Chern-Simons range signal will reach a few times of χ cm for each free flight of these SST missions, here χ is the dimensionless post-Newtonian parameter of the non-dynamical Chern-Simons theory. Therefore, with the 12 years data of the GRACE mission, one expects that the mass scale M{sub CS} = (4ℎc)/(χa) of the non-dynamical Chern-Simons gravity could be constrained to be larger than 1.9 x 10.9 eV. For the GRACE FO mission that scheduled to be launched in 2017, the much stronger bound that M{sub CS} ≥ 5 x 10{sup -7} eV is expected. (orig.)

  16. Advances In Global Aerosol Modeling Applications Through Assimilation of Satellite-Based Lidar Measurements

    Science.gov (United States)

    Campbell, James; Hyer, Edward; Zhang, Jianglong; Reid, Jeffrey; Westphal, Douglas; Xian, Peng; Vaughan, Mark

    2010-05-01

    Modeling the instantaneous three-dimensional aerosol field and its downwind transport represents an endeavor with many practical benefits foreseeable to air quality, aviation, military and science agencies. The recent proliferation of multi-spectral active and passive satellite-based instruments measuring aerosol physical properties has served as an opportunity to develop and refine the techniques necessary to make such numerical modeling applications possible. Spurred by high-resolution global mapping of aerosol source regions, and combined with novel multivariate data assimilation techniques designed to consider these new data streams, operational forecasts of visibility and aerosol optical depths are now available in near real-time1. Active satellite-based aerosol profiling, accomplished using lidar instruments, represents a critical element for accurate analysis and transport modeling. Aerosol source functions, alone, can be limited in representing the macrophysical structure of injection scenarios within a model. Two-dimensional variational (2D-VAR; x, y) assimilation of aerosol optical depth from passive satellite observations significantly improves the analysis of the initial state. However, this procedure can not fully compensate for any potential vertical redistribution of mass required at the innovation step. The expense of an inaccurate vertical analysis of aerosol structure is corresponding errors downwind, since trajectory paths within successive forecast runs will likely diverge with height. In this paper, the application of a newly-designed system for 3D-VAR (x,y,z) assimilation of vertical aerosol extinction profiles derived from elastic-scattering lidar measurements is described [Campbell et al., 2009]. Performance is evaluated for use with the U. S. Navy Aerosol Analysis and Prediction System (NAAPS) by assimilating NASA/CNES satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) 0.532 μm measurements [Winker et al., 2009

  17. Comparison of global irradiance measurements of the official Spanish radiometric network for 2006 with satellite estimated data

    Directory of Open Access Journals (Sweden)

    J. M. Sancho

    2011-01-01

    Full Text Available The monthly average values of daily global irradiance measured in broadband at 40 stations of the National Radiometric Network of the Spanish Meteorological Agency have been compared with the monthly values of SIS (Surface Incoming Shortwave radiation of the Climate Monitoring-Satellite Application Facility for 2006. It is calculated by the data from the instrument Spinning Enhanced Visible and Infrared Imager of the Meteosat Second Generation satellite and of the Advanced Very High Resolution Radiometer of the NOAA polar satellites. The results show a great similarity between the data from both sources of information, and the discrepancies found are around 5%. The aim of such a comparison is to evaluate the suitability of the use of the SIS data for the elaboration of an atlas of solar irradiance available in Spain.

  18. Monitoring the effect of restoration measures in Indonesian peatlands by radar satellite imagery.

    Science.gov (United States)

    Jaenicke, J; Englhart, S; Siegert, F

    2011-03-01

    In the context of the ongoing climate change discussions the importance of peatlands as carbon stores is increasingly recognised in the public. Drainage, deforestation and peat fires are the main reasons for the release of huge amounts of carbon from peatlands. Successful restoration of degraded tropical peatlands is of high interest due to their huge carbon store and sequestration potential. The blocking of drainage canals by dam building has become one of the most important measures to restore the hydrology and the ecological function of the peat domes. This study investigates the capability of using multitemporal radar remote sensing imagery for monitoring the hydrological effects of these measures. The study area is the former Mega Rice Project area in Central Kalimantan, Indonesia, where peat drainage and forest degradation is especially intense. Restoration measures started in July 2004 by building 30 large dams until June 2008. We applied change detection analysis with more than 80 ENVISAT ASAR and ALOS PALSAR images, acquired between 2004 and 2009. Radar signal increases of up to 1.36 dB show that high frequency multitemporal radar satellite imagery can be used to detect an increase in peat soil moisture after dam construction, especially in deforested areas with a high density of dams. Furthermore, a strong correlation between cross-polarised radar backscatter coefficients and groundwater levels above -50 cm was found. Monitoring peatland rewetting and quantifying groundwater level variations is important information for vegetation re-establishment, fire hazard warning and making carbon emission mitigation tradable under the voluntary carbon market or REDD (Reducing Emissions from Deforestation and Degradation) mechanism. PMID:20971549

  19. The Ørsted Satellite in the International Decade of Geopotential Field Research (Petrus Peregrinus Medal Lecture)

    Science.gov (United States)

    Friis-Christensen, E.

    2009-04-01

    The launch of the Danish satellite Ørsted on 23 February, 1999 marked the beginning of the "Decade of Geopotential Field Research", an international effort to promote and coordinate a continuous monitoring of the geopotential (magnetic and gravity) field variability in the near-Earth environment. Already the first years of Ørsted magnetic field observations showed that dramatic changes had taken place, in particular in the South Atlantic / South African continent during the 20 years that had elapsed without satellite data after the NASA MAGSAT satellite mapping of the Earth's magnetic field. Although only designed with a life time of 14 months, the Ørsted satellite has still been providing valuable data, 10 years after launch, and has during this time been accompanied by two other geomagnetic satellite missions, the German CHAMP and the Argentinean SAC-C, both with similar instrumentation as the Ørsted satellite. This long period of continuous satellite observations of the magnetic field brought a number of scientific results including the detection of rapidly changing flows at the top of the core and crucial contribution to the derivation of the first World Digital Magnetic Anomaly Map. Furthermore, the high quality of the observations made it possible to identify completely new satellite magnetic signatures related to oceanic tides, ionospheric pressure gradient currents, and magnetic signatures of plasma bubbles. As often in science, new observations trigger new questions, which need to be answered with even more sophisticated measurements. This challenge was taken up by ESA by its selection of Swarm as the 5th mission in the Earth Explorer Programme. The three satellite constellation mission Swarm will be launched in 2010-11 with the objective to provide the best ever survey of the geomagnetic field and its temporal evolution in order to improve our understanding of the Earth's interior and the Geospace environment including the Sun-Earth connection

  20. The Operational Utility of Space Environmental Measurements From Polar-Orbiting, Sun-Synchronous Satellites in AFWA Models and Applications

    Science.gov (United States)

    Citrone, P. J.; Bonadonna, M. F.; Cade, T.; Nobis, T. E.; Denig, W. F.

    2005-12-01

    Satellite-based measurements of the space environment provide vital data inputs to advanced space weather models and applications used by the Air Force Weather Agency (AFWA) to generate mission-tailored space weather intelligence in support of U.S. military operations. Since the 1970's, the Defense Meteorological Satellite Program (DMSP) has provided in-situ measurements of the topside ionosphere and of the differential energy flux of precipitating electrons and ions into the auroral and polar regions. Recently, DMSP has deployed a new class of ultraviolet remote sensors which offer opportunities for improved space environmental monitoring. The DMSP polar-orbiting, sun-synchronous satellite measurements provide critical data inputs for current and future AFWA space weather models that specify and forecast the global thermosphere, ionosphere, and magnetosphere. The AFWA Space Weather Technology Branch is pursuing an ongoing effort to transition to operations advanced research technologies associated with space environmental forecasting, to include related software applications used by AFWA to generate mission-tailored visualization products that depict space weather impacts on military systems. The Space Environmental Sensor Suite (SESS) on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) will offer improved capabilities in terms of characterization and timeliness for space environmental data required by AFWA to meet new and emerging Department of Defense space weather operational requirements.

  1. All satellites total ozone evaluation in the tropics by comparison with SAOZ-NDACC ground-based measurements

    Science.gov (United States)

    Pommereau, Jean-Pierre; Lerot, Christophe; Van Roozendael, Michel; Goutail, Florence; Pazmino, Andrea; Frihi, Aymen; Bekki, Slimane; Clerbaux, Cathy

    2016-07-01

    All satellites total ozone measurements available from SBUV, OMI-T, OMI-D, OMI-CCI, GOME-CCI, GOME2-CCI, SCIAMACHY-CCI, NPP and IASI, since 2001 until 2015 are compared to those provided by the UV-Vis SAOZ/NDACC spectrometer at the two tropical stations of Reunion Island in the Indian Ocean and Bauru in Southern Brazil. The differences between satellites and SAOZ except IASI do show systematic seasonal variations of 0-3% (0-9 DU) amplitude and sharp negative peaks in Jan-Mar in Reunion Is in the austral summer. Whereas the summer negative peaks seen particularly on IASI, OMI-T, NPP and OMI-CCI at Reunion are shown to correlate with hurricanes and those seen in Brazil with high altitude overshooting convective clouds both not properly removed, ozone minima outside these events are shown to correlate with high altitude volcanic plumes impacting all satellites as well as ground-based total ozone measurements The seasonality of the Sat-SAOZ difference of varying amplitude from 0 to 3% with the satellite is attributed to the satellite retrieval. Surprisingly and though there has been no change in either SAOZ instruments or data analysis processes, the amplitude of the seasonal cycle of the Sat-SAOZ difference reduces in 2012 and drops to less than ± 0.5% (1.5 DU) after 2013 in Reunion Island and less than ±1% in Bauru, reduction for which there is no clear explanation yet. Shown in the presentation will be the demonstration of the impact of hurricanes, high altitude convective clouds and volcanic plumes on satellites total ozone retrievals, followed by a discussion of possible causes of seasonality of Sat-SAOZ amplitude drop after 2012.

  2. Measuring Phased-Array Antenna Beampatterns with High Dynamic Range for the Murchison Widefield Array using 137 MHz ORBCOMM Satellites

    CERN Document Server

    Neben, A R; Hewitt, J N; Bernardi, G; Bowman, J D; Briggs, F; Cappallo, R J; Deshpande, A A; Goeke, R; Greenhill, L J; Hazelton, B J; Johnston-Hollitt, M; Kaplan, D L; Lonsdale, C J; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Oberoi, D; Ord, S M; Prabu, T; Shankar, N Udaya; Srivani, K S; Subrahmanyan, R; Tingay, S J; Wayth, R B; Webster, R L; Williams, A; Williams, C L

    2015-01-01

    Detection of the fluctuations in 21 cm line emission from neutral hydrogen during the Epoch of Reionization in thousand hour integrations poses stringent requirements on calibration and image quality, both of which necessitate accurate primary beam models. The Murchison Widefield Array (MWA) uses phased array antenna elements which maximize collecting area at the cost of complexity. To quantify their performance, we have developed a novel beam measurement system using the 137 MHz ORBCOMM satellite constellation and a reference dipole antenna. Using power ratio measurements, we measure the {\\it in situ} beampattern of the MWA antenna tile relative to that of the reference antenna, canceling the variation of satellite flux or polarization with time. We employ angular averaging to mitigate multipath effects (ground scattering), and assess environmental systematics with a null experiment in which the MWA tile is replaced with a second reference dipole. We achieve beam measurements over 30 dB dynamic range in beam...

  3. Communications satellite business ventures - Measuring the impact of technology programmes and related policies

    Science.gov (United States)

    Greenberg, J. S.

    1986-01-01

    An economic evaluation and planning procedure which assesses the effects of various policies on fixed satellite business ventures is described. The procedure is based on a stochastic financial simulation model, the Domsat II, which evaluates spacecraft reliability, market performance, and cost uncertainties. The application of the Domsat II model to the assessment of NASA's ion thrusters for on-orbit propulsion and GaAs solar cell technology is discussed. The effects of insurance rates and the self-insurance option on the financial performance of communication satellite business ventures are investigated. The selection of a transportation system for placing the satellites into GEO is analyzed.

  4. Magnetic signals generated by ocean flow in Swarm satellite data: prediction and observation

    Science.gov (United States)

    Einspigel, David; Velimsky, Jakub; Martinec, Zdenek; Sachl, Libor

    2015-04-01

    Motion of sea water in the Earth's main magnetic field generates the secondary induced field which can be decomposed into its poloidal and toroidal components. While the toroidal component is not directly observable outside the oceans, the poloidal magnetic field have been already validated by CHAMP satellite magnetic observations, land-based magnetic measurements and sea surface magnetic field measurements, despite the poloidal field being rather weak, reaching an intensity of up to a few nT. New possibilities of observations of the ocean-induced magnetic field came with the launching of ESA's Swarm mission satellites which have provided a valuable amount of high-precision and high-resolution measurements of the Earth's magnetic field. For a detection of weak ocean-induced signals and their interpretation, numerical modelling is crucial. We present results of modelling of the secondary magnetic field generated by ocean flow. Two ocean flow models are incorporated: 1) DEBOT, a barotropic model of ocean tide flow and 2) LSOMG, a baroclinic model of global ocean circulation. The secondary magnetic field is modelled by two different approaches: 1) a single-layer approximation model and 2) a three-dimensional time-domain electromagnetic induction model. A preliminary comparison of predicted signals and observed signals extracted from Swarm satellite data will be shown. The future aim is to assimilate magnetic data provided by Swarm mission into the models.

  5. Satellite quenching timescales in clusters from projected phase space measurements matched to simulated orbits

    CERN Document Server

    Oman, Kyle A

    2016-01-01

    We measure the star formation quenching efficiency and timescale in cluster environments. Our method uses N-body simulations to estimate the probability distribution of possible orbits for a sample of observed SDSS galaxies in and around clusters based on their position and velocity offsets from their host cluster. We study the relationship between their star formation rates and their likely orbital histories via a simple model in which star formation is quenched once a delay time after infall has elapsed. Our orbit library method is designed to isolate the environmental effect on the star formation rate due to a galaxy's present-day host cluster from `pre-processing' in previous group hosts. We find that quenching of satellite galaxies of all stellar masses in our sample ($10^{9}-10^{11.5}\\,{\\rm M}_\\odot$) by massive ($> 10^{13}\\,{\\rm M}_\\odot$) clusters is essentially $100$ per cent efficient. Our fits show that all galaxies quench on their first infall, approximately at or within a Gyr of their first peric...

  6. Vertical Crustal Motion Derived from Satellite Altimetry and Tide Gauges, and Comparisons with DORIS Measurements

    Science.gov (United States)

    Ray, R. D.; Beckley, B. D.; Lemoine, F. G.

    2010-01-01

    A somewhat unorthodox method for determining vertical crustal motion at a tide-gauge location is to difference the sea level time series with an equivalent time series determined from satellite altimetry, To the extent that both instruments measure an identical ocean signal, the difference will be dominated by vertical land motion at the gauge. We revisit this technique by analyzing sea level signals at 28 tide gauges that are colocated with DORIS geodetic stations. Comparisons of altimeter-gauge vertical rates with DORIS rates yield a median difference of 1.8 mm/yr and a weighted root-mean-square difference of2.7 mm/yr. The latter suggests that our uncertainty estimates, which are primarily based on an assumed AR(l) noise process in all time series, underestimates the true errors. Several sources of additional error are discussed, including possible scale errors in the terrestrial reference frame to which altimeter-gauge rates are mostly insensitive, One of our stations, Male, Maldives, which has been the subject of some uninformed arguments about sea-level rise, is found to have almost no vertical motion, and thus is vulnerable to rising sea levels. Published by Elsevier Ltd. on behalf of COSPAR.

  7. Solar measurements from the Airglow-Solar Spectrometer Instrument (ASSI) on the San Marco 5 satellite

    Science.gov (United States)

    Woods, Thomas N.

    1994-04-01

    The analysis of the solar spectral irradiance from the Airglow-Solar Spectrometer Instrument (ASSI) on the San Marco 5 satellite is the focus for this research grant. A pre-print copy of the paper describing the calibrations of and results from the San Marco ASSI is attached to this report. The calibration of the ASSI included (1) transfer of photometric calibration from a rocket experiment and the Solar Mesosphere Explorer (SME), (2) use of the on-board radioactive calibration sources, (3) validation of the ASSI sensitivity over its field of view, and (4) determining the degradation of the spectrometers. We have determined that the absolute values for the solar irradiance needs adjustment in the current proxy models of the solar UV irradiance, and the amount of solar variability from the proxy models are in reasonable agreement with the ASSI measurements. This research grant also has supported the development of a new solar EUV irradiance proxy model. We expected that the magnetic flux is responsible for most of the heating, via Alfen waves, in the chromosphere, transition region, and corona. From examining time series of solar irradiance data and magnetic fields at different levels, we did indeed find that the chromospheric emissions correlate best with the large magnetic field levels.

  8. Comparative Study of Ground Measured, Satellite-Derived, and Estimated Global Solar Radiation Data in Nigeria

    Directory of Open Access Journals (Sweden)

    Boluwaji M. Olomiyesan

    2016-01-01

    Full Text Available In this study, the performance of three global solar radiation models and the accuracy of global solar radiation data derived from three sources were compared. Twenty-two years (1984–2005 of surface meteorological data consisting of monthly mean daily sunshine duration, minimum and maximum temperatures, and global solar radiation collected from the Nigerian Meteorological (NIMET Agency, Oshodi, Lagos, and the National Aeronautics Space Agency (NASA for three locations in North-Western region of Nigeria were used. A new model incorporating Garcia model into Angstrom-Prescott model was proposed for estimating global radiation in Nigeria. The performances of the models used were determined by using mean bias error (MBE, mean percentage error (MPE, root mean square error (RMSE, and coefficient of determination (R2. Based on the statistical error indices, the proposed model was found to have the best accuracy with the least RMSE values (0.376 for Sokoto, 0.463 for Kaduna, and 0.449 for Kano and highest coefficient of determination, R2 values of 0.922, 0.938, and 0.961 for Sokoto, Kano, and Kaduna, respectively. Also, the comparative study result indicates that the estimated global radiation from the proposed model has a better error range and fits the ground measured data better than the satellite-derived data.

  9. Satellite passive microwave measurements of sea ice concentration: an optimal algorithm and challenges

    Directory of Open Access Journals (Sweden)

    N. Ivanova

    2015-02-01

    Full Text Available Sea ice concentration has been measured globally with satellite microwave radiometers for over 30 years. However there is still a need for better understanding of corresponding challenges and consequently identifying an optimal method for sea ice concentration retrieval suitable for climate monitoring. The method should minimize inter-sensor calibration discrepancies and sensitivity to error sources with climatic trends (e.g. atmospheric water vapour and water surface roughening by wind. This article presents the results of an extensive algorithm inter-comparison and validation experiment. Thirty sea ice algorithms entered the experiment where their skills were evaluated over low and high sea ice concentrations, thin ice and areas covered by melt ponds. In addition, atmospheric correction of input brightness temperatures and dynamic tie-points approach were suggested. A selection of thirteen algorithms is shown in the article to demonstrate the results. Based on the findings, an optimal approach was suggested to retrieve sea ice concentration globally for climate monitoring purposes.

  10. Statistical theory for estimating sampling errors of regional radiation averages based on satellite measurements

    Science.gov (United States)

    Smith, G. L.; Bess, T. D.; Minnis, P.

    1983-01-01

    The processes which determine the weather and climate are driven by the radiation received by the earth and the radiation subsequently emitted. A knowledge of the absorbed and emitted components of radiation is thus fundamental for the study of these processes. In connection with the desire to improve the quality of long-range forecasting, NASA is developing the Earth Radiation Budget Experiment (ERBE), consisting of a three-channel scanning radiometer and a package of nonscanning radiometers. A set of these instruments is to be flown on both the NOAA-F and NOAA-G spacecraft, in sun-synchronous orbits, and on an Earth Radiation Budget Satellite. The purpose of the scanning radiometer is to obtain measurements from which the average reflected solar radiant exitance and the average earth-emitted radiant exitance at a reference level can be established. The estimate of regional average exitance obtained will not exactly equal the true value of the regional average exitance, but will differ due to spatial sampling. A method is presented for evaluating this spatial sampling error.

  11. Study of wind speed attenuation at Kavaratti Island using land-based, offshore, and satellite measurements

    Science.gov (United States)

    Joseph, Antony; Rivonkar, Pradhan; Balakrishnan Nair, T. M.

    2012-06-01

    The role of dense coconut palms in attenuating the wind speed at Kavaratti Island, which is located in the southeastern Arabian Sea, is examined based on land-based and offshore wind measurements (U10) using anchored-buoy-mounted and satellite-borne sensors (QuikSCAT scatterometer and TMI microwave imager) during an 8-year period (2000-2007). It is found that round the year monthly-mean wind speed measurements from the Port Control Tower (PCT) located within the coconut palm farm at the Kavaratti Island are weaker by 15-61% relative to those made from the nearby offshore region. Whereas wind speed attenuation at the island is ~15-40% in the mid-June to mid-October south-west monsoon period, it is ~41-61% during the rest of the year. Wind direction measurements from all the devices overlapped, except in March-April during which the buoy measurements deviated from the other measurements by ~20°. U10 wind speed measurements from PCT during the November 2009 tropical cyclone "Phyan" indicated approximately 50-80% attenuation relative to those from the seaward boundary of the island's lagoon (and therefore least influenced by the coconut palms). The observed wind speed attenuation can be understood through the theory of free turbulent flow jets embodied in the boundary-layer fluid dynamics, according to which both the axial and transverse components of the efflux of flows discharged through the inter-leaves porosity (orifice) undergo increasing attenuation in the downstream direction with increasing distance from the orifice. Thus, the observed wind speed attenuation at Kavaratti Island is attributable to the decline in wind energy transmission from the seaward boundary of the coconut palm farm with distance into the farm. Just like mangrove forests function as bio-shields against forces from oceanic waves and stormsurges through their large above-ground aerial root systems and standing crop, and thereby playing a distinctive role in ameliorating the effects of

  12. Constraining NOx emissions using satellite NO2 measurements during 2013 DISCOVER-AQ Texas campaign

    Science.gov (United States)

    Souri, Amir Hossein; Choi, Yunsoo; Jeon, Wonbae; Li, Xiangshang; Pan, Shuai; Diao, Lijun; Westenbarger, David A.

    2016-04-01

    Reliable emission inventories are key to precisely model air pollutant concentrations. The relatively large reduction in NOx emissions that is well corroborated by satellite and in-situ observations over southeast Texas has resulted in discrepancies between observations and regional model simulations based on the National Emission Inventory (NEI) provided every three years in U.S. In this study, a Bayesian inversion of OMI tropospheric NO2 is conducted to update anthropogenic sources of NEI-2011 and soil-biogenic sources from BEIS3 (Biogenic Emission Inventory System version 3) over southeast Texas and west Louisiana during the 2013 DISCOVER-AQ Texas campaign. Results reveal that influences of the a priori profile used in OMI NO2 retrieval play a significant role in inconsistencies between model and satellite observations, which should be mitigated. A posteriori emissions are produced using the regional Community Multiscale Air Quality (CMAQ) model associated with Decoupled Direct Method (DDM) sensitivity analysis. The inverse estimate suggests a reduction in area (44%), mobile (30%), and point sources (60%) in high NOx areas (ENOx> 0.2 mol/s), and an increase in soil (∼52%) and area emissions (37%) in low NOx regions (ENOxsoil-biogenic emissions more likely resulted from under-estimation of ships emissions, and the Yienger- Levy scheme used in BEIS respectively. In order to validate the accuracy of updated NOx emissions, CMAQ simulation was performed and results were evaluated with independent surface NO2 measurements. Comparing to surface monitoring sites, we find improvements (before and after inverse modeling) for MB (1.95, -0.30 ppbv), MAB (3.65, 2.60 ppbv), RMSE (6.13, 4.37 ppbv), correlation (0.68, 0.69), and IOA (0.76, 0.82). The largest improvement is seen for morning time surface NO2 for which RMSE and MB are reduced considerably by ∼60% (5.05 to 2.07 ppbv) and 109% (3.49 to -0.3 ppbv). However, under-prediction of model NO2 in Houston on 09

  13. Visual analysis as a method of interpretation of the results of satellite ionospheric measurements for exploratory problems

    Science.gov (United States)

    Korneva, N. N.; Mogilevskii, M. M.; Nazarov, V. N.

    2016-05-01

    Traditional methods of time series analysis of satellite ionospheric measurements have some limitations and disadvantages that are mainly associated with the complex nonstationary signal structure. In this paper, the possibility of identifying and studying the temporal characteristics of signals via visual analysis is considered. The proposed approach is illustrated by the example of the visual analysis of wave measurements on the DEMETER microsatellite during its passage over the HAARP facility.

  14. Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: influence of local factors

    OpenAIRE

    Revilla-Romero, B.; Thielen, J.; Salamon, P.; T. De Groeve; G. R. Brakenridge

    2014-01-01

    One of the main challenges for global hydrological modelling is the limited availability of observational data for calibration and model verification. This is particularly the case for real-time applications. This problem could potentially be overcome if discharge measurements based on satellite data were sufficiently accurate to substitute for ground-based measurements. The aim of this study is to test the potentials and constraints of the remote sensing signal of the Globa...

  15. Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: influence of local factors

    OpenAIRE

    Revilla-Romero, B.; Thielen, J.; Salamon, P.; T. De Groeve; G. R. Brakenridge

    2014-01-01

    One of the main challenges for global hydrological modelling is the limited availability of observational data for calibration and model verification. This is particularly the case for real time applications. This problem could potentially be overcome if discharge measurements based on satellite data were sufficiently accurate to substitute for ground-based measurements. The aim of this study is to test the potentials and constraints of the remote sensing si...

  16. Analysis and interpretation of satellite measurements in the near-infrared spectral region: Atmospheric carbon dioxide and methane

    OpenAIRE

    Schneising, Oliver

    2008-01-01

    Carbon dioxide (CO2) and methane (CH4) are the two most important anthropogenic greenhouse gases. SCIAMACHY on ENVISAT is the first satellite instrument whose measurements are sensitive to concentration changes of the two gases at all altitude levels down to the Earth's surface where the source/sink signals are largest. Three years (2003-2005) of SCIAMACHY near-infrared nadir measurements have been processed to simultaneously retrieve vertical columns of CO2, CH4, and oxygen using the scienti...

  17. Large-scale sea surface temperature variability from satellite and shipboard measurements

    Science.gov (United States)

    Bernstein, R. L.; Chelton, D. B.

    1985-01-01

    A series of satellite sea surface temperature intercomparison workshops were conducted under NASA sponsorship at the Jet Propulsion Laboratory. Three different satellite data sets were compared with each other, with routinely collected ship data, and with climatology, for the months of November 1979, December 1981, March 1982, and July 1982. The satellite and ship data were differenced against an accepted climatology to produce anomalies, which in turn were spatially and temporally averaged into two-degree latitude-longitude, one-month bins. Monthly statistics on the satellite and ship bin average temperatures yielded rms differences ranging from 0.58 to 1.37 C, and mean differences ranging from -0.48 to 0.72 C, varying substantially from month to month, and sensor to sensor.

  18. Moist processes during MJO events as diagnosed from water isotopic measurements from the IASI satellite

    Science.gov (United States)

    Tuinenburg, O. A.; Risi, C.; Lacour, J. L.; Schneider, M.; Wiegele, A.; Worden, J.; Kurita, N.; Duvel, J. P.; Deutscher, N.; Bony, S.; Coheur, P. F.; Clerbaux, C.

    2015-10-01

    This study aims to investigate some characteristics of the moist processes of the Madden-Julian oscillation (MJO), by making use of joint HDO (or δD) and H2O vapor measurements. The MJO is the main intraseasonal mode of the tropical climate but is hard to properly simulate in global atmospheric models. The joint use of δD-H2O diagnostics yields additional information compared to sole humidity measurements. We use midtropospheric Infrared Atmospheric Sounding Interferometer (IASI) satellite δD and H2O measurements to determine the mean MJO humidity and δD evolution. Moreover, by making use of high temporal resolution data, we determine the variability in this evolution during about eight MJO events from 2010 to 2012 (including those monitored during the DYNAMO (the Dynamics of the MJO), CINDY (Cooperative Indian Ocean Experiment in Y2011) campaign). These data have a higher spatiotemporal coverage than previous δD measurements, enabling the sampling of individual MJO events. IASI measurements over the Indian Ocean confirm earlier findings that the moistening before the precipitation peak of an MJO event is due to water vapor slightly enriched in HDO. There is then a HDO depletion around the precipitation peak that also corresponds to the moister environment. Most interevent variability determined in the current study occurs 5 to 10 days after the MJO event. In 75% of the events, humidity decreases while the atmosphere remains depleted. In a quarter of the events, humidity increases simultaneously with an increase in δD. After this, the advection of relatively dry and enriched air brings back the state to the mean. Over the maritime continent, δD-H2O cycles are more variable on time scales shorter than the MJO and the interevent variability is larger than over the Indian Ocean. The sequence of moistening and drying processes as revealed by the q-δD cycles can be used as a benchmark to evaluate the representation of moist processes in models. This is done here

  19. Harmonized dataset of ozone profiles from satellite limb and occultation measurements

    Directory of Open Access Journals (Sweden)

    V. F. Sofieva

    2013-06-01

    Full Text Available In this paper, we present a HARMonized dataset of OZone profiles (HARMOZ based on limb and occultation measurements from Envisat (GOMOS, MIPAS and SCIAMACHY, Odin (OSIRIS, SMR and SCISAT (ACE-FTS satellite instruments. These measurements provide high-vertical-resolution ozone profiles covering the altitude range from the upper troposphere up to the mesosphere in years 2001–2012. HARMOZ has been created in the framework of European Space Agency Climate Change Initiative project. The harmonized dataset consists of original retrieved ozone profiles from each instrument, which are screened for invalid data by the instrument teams. While the original ozone profiles are presented in different units and on different vertical grids, the harmonized dataset is given on a common pressure grid in netcdf format. The pressure grid corresponds to vertical sampling of ~ 1 km below 20 km and 2–3 km above 20 km. The vertical range of the ozone profiles is specific for each instrument, thus all information contained in the original data is preserved. Provided altitude and temperature profiles allow the representation of ozone profiles in number density or mixing ratio on a pressure or altitude vertical grids. Geolocation, uncertainty estimates and vertical resolution are provided for each profile. For each instrument, optional parameters, which might be related to the data quality, are also included. For convenience of users, tables of biases between each pair of instruments for each month, as well as bias uncertainties, are provided. These tables characterize the data consistency and can be used in various bias and drift analyses, which are needed, for instance, for combining several datasets to obtain a long-term climate dataset. This user-friendly dataset can be interesting and useful for various analyses and applications, such as data merging, data validation, assimilation and scientific research. Dataset is available at: http

  20. Satellite Measurements of Lava Extrusion Rate at Volcán Reventador, Ecuador

    Science.gov (United States)

    Arnold, D. W. D.; Biggs, J.; Ebmeier, S. K.; Vallejo Vargas, S.; Naranjo, M. F.

    2015-12-01

    The extrusion rate of lava at active volcanoes provides a principle control on the style of eruptive behavior and the extent of lava flows, while also providing information about magma supply to the volcano. Measurements of extrusion rate at active volcanoes are therefore important for assessing hazard, and improving understanding of volcanic systems. Volcán Reventador is an asymmetric stratovolcano in the Cordillera Real of Ecuador. The largest historically observed eruption at Reventador in 2002 has been followed by several periods of eruptive activity. Eruptions are characterised by effusion of andesitic to basaltic-andesitic lava flows, and Vulcanian explosions. The ongoing eruption at Reventador therefor provides an excellent target for investigating the link between effusion rate, explosivity, and lava flow behaviour. Satellite InSAR provides regular observations of the volcano, even during night or periods of cloud cover. We use a dataset of Radarsat-2 and TanDEM-X imagery, with intervals of 11 to 192 days, over the period 2011 to 2014 to measure the extent, thickness and volume of new lava flows at Reventador. We use radar amplitude and inteferometric coherence to map 25 individual lava flows, as well as pyroclastic deposits and changes in lava dome morphology. We observe 43 Mm3 of deposits over a three year period, giving an average effusion rate of 0.5 m3s-1. We do not observe any ground deformation due to magmatic sources at Reventador, therefore variations in lava effusion rate can be interpreted as changes in the magma supply to the volcano. We investigate the link between variations in effusion rate and the length, area, thickness, and aspect ratio of lava flows, and the explosive-effusive transition. We also characterise the relationship between lava flow age, thickness, and subsidence rate.

  1. Retrieval of temperature profiles from CHAMP for climate monitoring: intercomparison with Envisat MIPAS and GOMOS and different atmospheric analyses

    Directory of Open Access Journals (Sweden)

    A. Gobiet

    2007-02-01

    Full Text Available This study describes and evaluates a Global Navigation Satellite System (GNSS radio occultation (RO retrieval scheme particularly aimed at delivering bias-free atmospheric parameters for climate monitoring and research. The focus of the retrieval is on the sensible use of a priori information for careful high-altitude initialisation in order to maximise the usable altitude range. The RO retrieval scheme has been meanwhile applied to more than five years of data (September 2001 to November 2006 from the German CHAllenging Minisatellite Payload for geoscientific research (CHAMP satellite. In this study it was validated against various correlative datasets including the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS and the Global Ozone Monitoring for Occultation of Stars (GOMOS sensors on Envisat, five different atmospheric analyses, and the operational CHAMP retrieval product from GeoForschungsZentrum (GFZ Potsdam. In the global mean within 10 to 30 km altitude we find that the present validation observationally constrains the potential RO temperature bias to be <0.2 K. Latitudinally resolved analyses show biases to be observationally constrained to <0.2–0.5 K up to 35 km in most cases, and up to 30 km in any case, even if severely biased (about 10 K or more a priori information is used in the high altitude initialisation of the retrieval. No evidence is found for the 10–35 km altitude range of RO bias sources other than those potentially propagated downward from initialisation, indicating that the widely quoted RO promise of "unbiasedness and long-term stability due to intrinsic self-calibration" can indeed be realized given care in the data processing to strictly limit structural uncertainty. The results demonstrate that an adequate high-altitude initialisation technique is crucial for accurate stratospheric RO retrievals and that still common methods of initialising the involved hydrostatic integral with an upper boundary

  2. CHASER: An Innovative Satellite Mission Concept to Measure the Effects of Aerosols on Clouds and Climate

    Science.gov (United States)

    Renno, N.; Williams, E.; Rosenfeld, D.; Fischer, D.; Fischer, J.; Kremic, T.; Agrawal, A.; Andreae, M.; Bierbaum, R.; Blakeslee, R.; Boerner, A.; Bowles, N.; Christian, H.; Dunion, J.; Horvath, A.; Huang, X.; Khain, A.; Kinne, S.; Lemos, M.-C.; Penner, J.

    2012-04-01

    The formation of cloud droplets on aerosol particles, technically known as the activation of cloud condensation nuclei (CCN), is the fundamental process driving the interactions of aerosols with clouds and precipitation. Knowledge of these interactions is foundational to our understanding of weather and climate. The Intergovernmental Panel on Climate Change (IPCC) and the Decadal Survey (NRC 2007) indicate that the uncertainty in how clouds adjust to aerosol perturbations dominates the uncertainty in the overall quantification of the radiative forcing attributable to human activities. The Clouds, Hazards, and Aerosols Survey for Earth Researchers (CHASER) mission concept responds to the IPCC and Decadal Survey concerns by studying the activation of CCN and their interactions with clouds and storms. CHASER proposes to revolutionize our understanding of the interactions of aerosols with clouds by making the first global measurements of the fundamental physical entity linking them: activated cloud condensation nuclei. The CHASER mission was conceptualized to measure all quantities necessary for determining the interactions of aerosols with clouds and storms. Measurements by current satellites allow the determination of crude profiles of cloud particle size but not of the activated CCN that seed them. CHASER uses a new technique (Freud et al. 2011; Rosenfeld et al. 2012) and high-heritage instruments to produce the first global maps of activated CCN and the properties of the clouds associated with them. CHASER measures the CCN concentration and cloud thermodynamic forcing simultaneously, allowing their effects to be distinguished. Changes in the behavior of a group of weather systems in which only one of the quantities varies (a partial derivative of the intensity with the desirable quantity) allow the determination of each effect statistically. The high uncertainties of current climate predictions limit their much-needed use in decision-making. CHASER mitigates this

  3. A summary of solar 1-8a measurements from the SMS and GOES satellites, 1977-1981

    International Nuclear Information System (INIS)

    The 1-8A band of synodic full-disc solar x-rays (1-8A) W/(m sup 2) have been measured nearly continuously from 1975 to 1981 aboard the SMS-1, SMS-2, GOES-1, GOES-2, and GOES-3 satellites. These measurements are scheduled to continue in an on-going series of GOES satellites. The 1-8A band of X-rays are proportional to the emission measure at coronal heights at temperatures greater than 2,000,000 K. In the past, attention has been centered on using solar x-ray measurements in the detection and description of solar flares and their ionospheric effects. Here we center on a practical method of describing solar 1-8A mean and background X-ray measurements in a continuous time series to describe long-term solar variability. Intercomparisons of the satellites using linear regression techniques and a useful background coronal index are described. Sources of error and statistical information on relative accuracy are discussed. Data are presented in monthly plots of hourly averages, in tables of daily mean and background indices, and in comparison to the Ottawa 10.7 cm radio flux

  4. Théorie quantique des champs expérimentale.

    OpenAIRE

    Bell, J. S.

    2006-01-01

    1 - Résumé2 - La méccanique quantique3 - Les équations du mouvement de heisenberg4 - Le formalisme canonique5 - Le champ scalaire réel6 - Interprétation en termes de particules7 - Interaction8 - L'opérateur S9 - Elément de matrice S10 - Les gaphes de Feynman11 - La renormalisation12 - Probabilités de transition et sections efficaces13 - Le champ vectoriel14 - Vide nu et vide réel15 - Les fonctions de Green16 - Intégrales fonctionnelles17 - Théorie de champ euclidienne18 - L'interdependance de...

  5. Une introduction aux liens entre Mécanique Statistique et Théorie des champs.

    OpenAIRE

    Bauer, Michel

    2006-01-01

    Avant propos.1 - Transitions de phases et limite continue. -A. Introduction -B. Notion de limite continue : marche aléatoire sur le réseau -C. Le modéle d'Ising en dimension 2 -D. Perspectives 2 - Phénomènes critique et théories des champs sur le résau -A. Retour au modéle d'Ising -B. Champ moyen et corrections -C. Régles de Feynman -D. Interprétation physique dans le cas homogéne -E. Le modélesigma non linéaire -F. Passage à la limite continue 3 - Théorie des champs continue -A. Régles de Fe...

  6. Champs aléatoires: autosimilarité, anisotropie et étude directionnelle

    OpenAIRE

    Biermé, Hermine

    2005-01-01

    Nous étudions des champs aléatoires pouvant modéliser certains milieux poreux. Nous nous intéressons à leurs statistiques au second ordre et en particulier à leur autosimilarité. Sous des hypothèses de stationnarité, une mesure spectrale caractérise le champ. L'homogénéité asymptotique directionnelle de la mesure détermine l'autosimilarité asymptotique du champ; le plus petit coefficient d'homogénéité dans une échelle logarithmique en donne l'ordre. Pour déterminer l'anisotropie on peut consi...

  7. ÉTUDE DES EFFETS BIOLOGIQUES DES CHAMPS ÉLECTROMAGNÉTIQUES NON INVASIFS

    OpenAIRE

    Lagroye, I.

    2009-01-01

    L'environnement électromagnétique, et donc l'exposition aux champs électromagnétiques, existe depuis toujours. En revanche, le nombre de sources d'exposition a augmenté de façon inégale au cours de l'histoire humaine. La source primaire principale et omni-présente est le champ magnétique statique terrestre, appelé champ géomagnétique. Sa valeur moyenne est de 50 µT. Dans l'Antiquité, le savant grec Thalès serait le premier à s'être intéressé à l'électricité, mais c'est à la fin du 18ème siècl...

  8. Tropospheric BrO column densities in the Arctic derived from satellite: retrieval and comparison to ground-based measurements

    Directory of Open Access Journals (Sweden)

    H. Sihler

    2012-11-01

    Full Text Available During polar spring, halogen radicals like bromine monoxide (BrO play an important role in the chemistry of tropospheric ozone destruction. Satellite measurements of the BrO distribution have become a particularly useful tool to investigate this probably natural phenomenon, but the separation of stratospheric and tropospheric partial columns of BrO is challenging. In this study, an algorithm was developed to retrieve tropospheric vertical column densities of BrO from data of high-resolution spectroscopic satellite instruments such as the second Global Ozone Monitoring Experiment (GOME-2. Unlike recently published approaches, the presented algorithm is capable of separating the fraction of BrO in the activated troposphere from the total BrO column solely based on remotely measured properties. The presented algorithm furthermore allows to estimate a realistic measurement error of the tropospheric BrO column. The sensitivity of each satellite pixel to BrO in the boundary layer is quantified using the measured UV radiance and the column density of the oxygen collision complex O4. A comparison of the sensitivities with CALIPSO LIDAR observations demonstrates that clouds shielding near-surface trace-gas columns can be reliably detected even over ice and snow. Retrieved tropospheric BrO columns are then compared to ground-based BrO measurements from two Arctic field campaigns in the Amundsen Gulf and at Barrow in 2008 and 2009, respectively. Our algorithm was found to be capable of retrieving enhanced near-surface BrO during both campaigns in good agreement with ground-based data. Some differences between ground-based and satellite measurements observed at Barrow can be explained by both elevated and shallow surface layers of BrO. The observations strongly suggest that surface release processes are the dominating source of BrO and that boundary layer meteorology influences the vertical distribution.

  9. Measuring Forest Biomass and Height from Space - Results from the assessment of ESA's BIOMASS satellite concept

    Science.gov (United States)

    Scipal, Klaus

    2010-05-01

    Knowledge about forest above-ground biomass is of fundamental importance in quantifying the terrestrial carbon cycle, but is also crucial in assessing forest resources and the ecosystem services provided by forests, and is an essential element in assessing carbon fluxes under the United Nations Framework Convention on Climate Change. For most parts of the world, in particular the tropical forests, information on biomass is currently very limited, at very coarse scales, and subject to large and unquantified errors. In response to the urgent need for greatly improved mapping of global biomass and the lack of any current space systems capable of addressing this need, the BIOMASS mission was proposed to the European Space Agency for the third cycle of Earth Explorer Core missions and was selected for Feasibility Study (Phase A) in March 2009. Over the five-year mission lifetime, it shall map the full range of the world's above-ground biomass with accuracy and spatial resolution compatible with the needs of national scale inventory and carbon flux calculations, and will map changes in forest biomass. The mission will carry a polarimetric P-Band SAR, capable of providing both direct measurements of biomass derived from inverting intensity data, and measurements of forest height derived from polarimetric interferometry. The BIOMASS payload consists of a fully polarimetric system operated at a centre frequency of 435 MHz (P-band) with a bandwidth of 6 MHz. To enable measurements at a scale comparable to that of deforestation and forest disturbance (i.e. around 1 ha), it is envisaged that BIOMASS will provide level-1 products with around 50 m x 50 m resolution at 4 looks, so around 16 looks at a scale of 1 ha. The satellite shall fly in a sun-synchronous dawn-dusk orbit to minimise ionospheric disturbances with a controlled drift to meet the revisit requirement for forest height recovery using Pol-InSAR techniques. The revisit time will be between 25-45 days to maintain

  10. Gravity field models from kinematic orbits of CHAMP, GRACE and GOCE satellites

    Czech Academy of Sciences Publication Activity Database

    Bezděk, Aleš; Sebera, Josef; Klokočník, Jaroslav; Kostelecký, J.

    2014-01-01

    Roč. 53, č. 3 (2014), s. 412-429. ISSN 0273-1177 R&D Projects: GA MŠk LH13071; GA ČR GA13-36843S Institutional support: RVO:67985815 Keywords : gravity field models * kinematic orbits * generalized least squares Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.358, year: 2014

  11. The Russian contribution in WDMAM-2011 magnetic anomalies and anomalies of satellite Champ

    Science.gov (United States)

    Livinova, Tamara; Glebovsky, Vladimir

    2010-05-01

    In VSEGEI is created the renovated digital cartographical model of an anomalous magnetic field (AMF) of territory of Russia and adjacent aquatory of scale 1:2 500000 on the basis of the available base summary digital materials prepared at various times by two organizations: VSEGEI and VNIIOkeangeologia. For this purpose uniform technological rules which have provided satisfactory synthesis of digital data files of an anomalous magnetic field in scale 1:2 500000 have been developed and realized. As a result of processing digital data file AMF the divergences reached 200 нТл, have been eliminated. For inclusion in WDMAM-2011 the Russian side the digital model counted on height 1 km on a grid 5х5км is offered. Anomalous values are designed from normal field VSEGEI of an epoch of 1965. The magnetic grid (5x5 km) within the Russian continental shelf compiled in VNIIOkeangeologia was leveled, adjusted and merged with those created in VSEGEI on shore of Russian Federation. Data processing is made by software Geosoft. Russian magnetic database in the Arctic Ocean was created as a result of adjusting of all historical and recent magnetic data sets, collected several organizations during the period about 40 years. Within the deep part of the Arctic Ocean this information was leveled, adjusted and combined with all available US magnetic data sets under cooperative project between and US Naval Research Laboratory. A result of this compilation is presented by grid of magnetic anomalies (5x5 km) that was used in the CAMP-GM project.

  12. Satellite-Altitude Geopotential Study of the Kursk Magnetic Anomaly (KMA)

    Science.gov (United States)

    Taylor, Patrick T.; Kim, Hyung Rae; vonFrese, Ralph R. B.; Potts, Laramie V.; Frawley, James J.

    2003-01-01

    With the successful launch of the Orsted, SAC-C and CHAMP satellites we are able to make both magnetic and gravity anomaly maps of the Earth's crust; magnetic from all three missions and gravity with CHAMP. We have used these data to study the KMA area of Russia. This is an important region for several reasons: (1) we have already made satellite magnetic anomaly maps of this region and they can be integrated with the gravity data from CHAMP for a comprehensive interpretation; (2) KMA contains the largest know reserves of iron-ore in the world; and (3) there are significant ground truth data available for this region from aeromagnetic, balloon surveys and geophysical mapping, including extensive rock magnetic/paleo-magnetic and geologic studies. Utilizing the gravity observations, collocated with the magnetic data enabled us to make a joint interpretation. While there is a high amplitude magnetic anomaly recorded over the KMA the gravity anomaly at satellite altitude revealed by CHAMP is only around 3-6 mGal but is not centered on the magnetic high. This would indicate that despite the fact that in the region of the KMA the rocks have a higher percentage of iron than in the surrounding formations the entire area is Archean-Proterozoic in age and therefore very dense.

  13. Water Accounting Plus (WA+) - a water accounting procedure for complex river basins based on satellite measurements

    Science.gov (United States)

    Karimi, P.; Bastiaanssen, W. G. M.; Molden, D.

    2013-07-01

    Coping with water scarcity and growing competition for water among different sectors requires proper water management strategies and decision processes. A pre-requisite is a clear understanding of the basin hydrological processes, manageable and unmanageable water flows, the interaction with land use and opportunities to mitigate the negative effects and increase the benefits of water depletion on society. Currently, water professionals do not have a common framework that links depletion to user groups of water and their benefits. The absence of a standard hydrological and water management summary is causing confusion and wrong decisions. The non-availability of water flow data is one of the underpinning reasons for not having operational water accounting systems for river basins in place. In this paper, we introduce Water Accounting Plus (WA+), which is a new framework designed to provide explicit spatial information on water depletion and net withdrawal processes in complex river basins. The influence of land use and landscape evapotranspiration on the water cycle is described explicitly by defining land use groups with common characteristics. WA+ presents four sheets including (i) a resource base sheet, (ii) an evapotranspiration sheet, (iii) a productivity sheet, and (iv) a withdrawal sheet. Every sheet encompasses a set of indicators that summarise the overall water resources situation. The impact of external (e.g., climate change) and internal influences (e.g., infrastructure building) can be estimated by studying the changes in these WA+ indicators. Satellite measurements can be used to acquire a vast amount of required data but is not a precondition for implementing WA+ framework. Data from hydrological models and water allocation models can also be used as inputs to WA+.

  14. Water Accounting Plus (WA+) - a water accounting procedure for complex river basins based on satellite measurements

    Science.gov (United States)

    Karimi, P.; Bastiaanssen, W. G. M.; Molden, D.

    2012-11-01

    Coping with the issue of water scarcity and growing competition for water among different sectors requires proper water management strategies and decision processes. A pre-requisite is a clear understanding of the basin hydrological processes, manageable and unmanageable water flows, the interaction with land use and opportunities to mitigate the negative effects and increase the benefits of water depletion on society. Currently, water professionals do not have a common framework that links hydrological flows to user groups of water and their benefits. The absence of a standard hydrological and water management summary is causing confusion and wrong decisions. The non-availability of water flow data is one of the underpinning reasons for not having operational water accounting systems for river basins in place. In this paper we introduce Water Accounting Plus (WA+), which is a new framework designed to provide explicit spatial information on water depletion and net withdrawal processes in complex river basins. The influence of land use on the water cycle is described explicitly by defining land use groups with common characteristics. Analogous to financial accounting, WA+ presents four sheets including (i) a resource base sheet, (ii) a consumption sheet, (iii) a productivity sheet, and (iv) a withdrawal sheet. Every sheet encompasses a set of indicators that summarize the overall water resources situation. The impact of external (e.g. climate change) and internal influences (e.g. infrastructure building) can be estimated by studying the changes in these WA+ indicators. Satellite measurements can be used for 3 out of the 4 sheets, but is not a precondition for implementing WA+ framework. Data from hydrological models and water allocation models can also be used as inputs to WA+.

  15. Possible experiment with two counter-orbiting drag-free satellites to obtain a new test of Einstein's general theory of relativity and improved measurements in geodesy

    International Nuclear Information System (INIS)

    In 1918, Lense and Thirring calculated that a moon orbiting a rotating planet would experience a nodal dragging effect due to general relativity. We describe an experiment to measure this effect to 1% with two counter-orbiting drag-free satellites in polar earth orbit. In addition to tracking data from existing ground stations, satellite-to-satellite Doppler ranging data are taken near the poles. New geophysical information is inherent in the polar data

  16. Tropospheric BrO column densities in the Arctic from satellite: retrieval and comparison to ground-based measurements

    Directory of Open Access Journals (Sweden)

    H. Sihler

    2012-05-01

    Full Text Available During polar spring, halogen radicals like bromine monoxide (BrO play an important role in the chemistry of tropospheric ozone destruction. Satellite measurements of the BrO-distribution have become a particularly useful tool to investigate this probably natural phenomenon, but the separation of stratospheric and tropospheric partial columns of BrO is challenging. In this study, an algorithm was developed to retrieve tropospheric vertical column densities of BrO from data of high-resolution spectroscopic satellite instruments such as the second Global Ozone Monitoring Experiment (GOME-2. Unlike recently published approaches, the presented algorithm is capable of separating the fraction of BrO in the activated troposphere from the total BrO column solely based on remotely measured properties. The sensitivity of each satellite pixel to BrO in the boundary-layer is quantified using the measured UV-radiance and the column density of the oxygen collision complex O4. A comparison of the sensitivities with CALIPSO LIDAR observations demonstrates that clouds shielding near-surface trace-gas columns can be reliably detected even over ice and snow. Retrieved tropospheric BrO columns are then compared to ground-based BrO measurements from two Arctic field campaigns in the Amundsen Gulf and at Barrow in 2008 and 2009, respectively. Our algorithm was found to be capable of retrieving enhanced near-surface BrO during both campaigns in good agreement to ground-based data. Some differences between ground-based and satellite measurements observed at Barrow can be explained by both, elevated and shallow surface layers of BrO. The observations strongly suggest that surface release processes are the dominating source of BrO and that boundary-layer meteorology influences the vertical distribution.

  17. Neural Networks Technique for Filling Gaps in Satellite Measurements: Application to Ocean Color Observations.

    Science.gov (United States)

    Krasnopolsky, Vladimir; Nadiga, Sudhir; Mehra, Avichal; Bayler, Eric; Behringer, David

    2016-01-01

    A neural network (NN) technique to fill gaps in satellite data is introduced, linking satellite-derived fields of interest with other satellites and in situ physical observations. Satellite-derived "ocean color" (OC) data are used in this study because OC variability is primarily driven by biological processes related and correlated in complex, nonlinear relationships with the physical processes of the upper ocean. Specifically, ocean color chlorophyll-a fields from NOAA's operational Visible Imaging Infrared Radiometer Suite (VIIRS) are used, as well as NOAA and NASA ocean surface and upper-ocean observations employed--signatures of upper-ocean dynamics. An NN transfer function is trained, using global data for two years (2012 and 2013), and tested on independent data for 2014. To reduce the impact of noise in the data and to calculate a stable NN Jacobian for sensitivity studies, an ensemble of NNs with different weights is constructed and compared with a single NN. The impact of the NN training period on the NN's generalization ability is evaluated. The NN technique provides an accurate and computationally cheap method for filling in gaps in satellite ocean color observation fields and time series. PMID:26819586

  18. Measurements of VLF-particle interactions at the South Atlantic Magnetic Anomaly on board a Brazilian geophysical satellite

    International Nuclear Information System (INIS)

    A summary of the proposal for measurements of VLF wave-particle interactions, expected to occur at the South Atlantic magnetic anomaly, to be carried out on board a Brazilian geophysical satellite, will be presented. The expected domain of such interactions refers to electromagnetic VLF waves and to energetic-relativistic inner belt electrons, pitch angle diffusing into the atmosphere via cyclotron resonances. The detectors involve a tri-axial search coil magnetometer and a surface barrier silicon telescope. A modified and preliminary version of this proposed experiment will be carried out on board long duration balloon flights, well before the beginning of the intended satellite measurements. For the ballon flights the particle detector will be replaced by an x-ray detector, which can also monitor parameters related to the electron precipitation. (author)

  19. A new model of Earth's radial conductivity structure derived from over 10 yr of satellite and observatory magnetic data

    DEFF Research Database (Denmark)

    Püthe, Christoph; Kuvshinov, Alexey; Khan, Amir;

    2015-01-01

    We present a newmodel of the radial (1-D) conductivity structure of Earth's mantle. This model is derived frommore than 10 yr of magnetic measurements from the satellites ørsted, CHAMP, SAC-C and the Swarm trio as well as the global network of geomagnetic observatories. After removal of core and...... crustal field as predicted by a recent field model, we fit the magnetic data with spherical harmonic coefficients describing ring current activity and associated induction effects and estimate global C-responses at periods between 1.5 and 150 d. The C-responses are corrected for 3-D effects due to....... Analysis of the Hessian of the cost function reveals that the data are most sensitive to structures at depths between 800 and 1200 km, in agreement with the results obtained from the probabilistic approach. Preliminary interpretation of the inverted conductivity structure based on laboratory...

  20. Validation of ACE-FTS satellite data in the upper troposphere/lower stratosphere (UTLS using non-coincident measurements

    Directory of Open Access Journals (Sweden)

    P. Hoor

    2008-03-01

    Full Text Available CO, O3, and H2O data in the upper troposphere/lower stratosphere (UTLS measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS on Canada's SCISAT-1 satellite are validated using aircraft and ozonesonde measurements. In the UTLS, validation of chemical trace gas measurements is a challenging task due to small-scale variability in the tracer fields, strong gradients of the tracers across the tropopause, and scarcity of measurements suitable for validation purposes. Validation based on coincidences therefore suffers from geophysical noise. Two alternative methods for the validation of satellite data are introduced, which avoid the usual need for coincident measurements: tracer-tracer correlations, and vertical tracer profiles relative to tropopause height. Both are increasingly being used for model validation as they strongly suppress geophysical variability and thereby provide an "instantaneous climatology". This allows comparison of measurements between non-coincident data sets which yields information about the precision and a statistically meaningful error-assessment of the ACE-FTS satellite data in the UTLS. By defining a trade-off factor, we show that the measurement errors can be reduced by including more measurements obtained over a wider longitude range into the comparison, despite the increased geophysical variability. Applying the methods then yields the following upper bounds to the relative differences in the mean found between the ACE-FTS and SPURT aircraft measurements in the upper troposphere (UT and lower stratosphere (LS, respectively: for CO ±9% and ±12%, for H2O ±30% and ±18%, and for O3 ±25% and ±19%. The relative differences for O3 can be narrowed down by using a larger dataset obtained from ozonesondes, yielding a high bias in the ACE-FTS measurements of 18% in the UT and relative differences of ±8% for measurements in the LS

  1. Validation of ACE-FTS satellite data in the upper troposphere/lower stratosphere (UTLS) using non-coincident measurements

    Science.gov (United States)

    Hegglin, M. I.; Boone, C. D.; Manney, G. L.; Shepherd, T. G.; Walker, K. A.; Bernath, P. F.; Daffer, W. H.; Hoor, P.; Schiller, C.

    2008-03-01

    CO, O3, and H2O data in the upper troposphere/lower stratosphere (UTLS) measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on Canada's SCISAT-1 satellite are validated using aircraft and ozonesonde measurements. In the UTLS, validation of chemical trace gas measurements is a challenging task due to small-scale variability in the tracer fields, strong gradients of the tracers across the tropopause, and scarcity of measurements suitable for validation purposes. Validation based on coincidences therefore suffers from geophysical noise. Two alternative methods for the validation of satellite data are introduced, which avoid the usual need for coincident measurements: tracer-tracer correlations, and vertical tracer profiles relative to tropopause height. Both are increasingly being used for model validation as they strongly suppress geophysical variability and thereby provide an "instantaneous climatology". This allows comparison of measurements between non-coincident data sets which yields information about the precision and a statistically meaningful error-assessment of the ACE-FTS satellite data in the UTLS. By defining a trade-off factor, we show that the measurement errors can be reduced by including more measurements obtained over a wider longitude range into the comparison, despite the increased geophysical variability. Applying the methods then yields the following upper bounds to the relative differences in the mean found between the ACE-FTS and SPURT aircraft measurements in the upper troposphere (UT) and lower stratosphere (LS), respectively: for CO ±9% and ±12%, for H2O ±30% and ±18%, and for O3 ±25% and ±19%. The relative differences for O3 can be narrowed down by using a larger dataset obtained from ozonesondes, yielding a high bias in the ACE-FTS measurements of 18% in the UT and relative differences of ±8% for measurements in the LS. When taking into account the smearing effect of the vertically limited

  2. Global equatorial ionosphericvertical plasma drifts measured by the AE-E satellite

    OpenAIRE

    Fejer, Bela G.; E. R. de Paula; Heelis, R. A.; Hanson, W B

    1995-01-01

    Ion drift meter observations from the Atmosphere Explorer E satellite during the period of January 1977 to December 1979 are used to study the dependence of equatorial (dip latitudes ≤ 7.5°) F region vertical plasma drifts (east-west electric fields) on solar activity, season, and longitude. The satellite-observed ion drifts show large day-to-day and seasonal variations. Solar cycle effects are most pronounced near the dusk sector with a large increase of the prereversal velocity enhancement ...

  3. Estimation of predictability of agrophytocenoses productivity on the basis of mathematical modeling, field experiments and satellite measurements

    OpenAIRE

    Pisman, T.; Pugacheva, I.; Shevyrnogov, A.

    2008-01-01

    Estimation of predictability of agrophytocenoses productivity was made by comparing the results of investigation of a mathematical model, field experiments and satellite measurements. The mathematical model of the seasonal dynamics of agrophytocenoses productivity was built with account of air temperature. For model investigation the coefficients were used that were calculated on the basis of the results of field experiments conducted in the Republic of Khakassia. The objects of t...

  4. Surface energy balance and actual evapotranspiration of the transboundary Indus Basin estimated from satellite measurements and the ETLook model

    OpenAIRE

    W. G. M. Bastiaanssen; Cheema, M. J. M.; Immerzeel, W. W.; Mittenburg, I.J.; Pelgrum, H.

    2012-01-01

    The surface energy fluxes and related evapotranspiration processes across the Indus Basin were estimated for the hydrological year 2007 using satellite measurements. The new ETLook remote sensing model (version 1) infers information on actual Evaporation (E) and actual Transpiration (T) from combined optical and passive microwave sensors, which can observe the land-surface even under persistent overcast conditions. A two-layer Penman–Monteith equation was applied for quantifying soil and cano...

  5. Oil Pollution Of The Southeastern Baltic Sea By Satellite Remote Sensing Data And In-Situ Measurements

    OpenAIRE

    Bulycheva Elena V.; Krek Aleksander V.; Kostianoy Andrey G.; Semenov Aleksander V.; Joksimovich Aleksandar

    2015-01-01

    Results of operational satellite monitoring of oil pollution of the sea surface together with in-situ measurements of the oil products concentration in the water column for the first time allowed to establish relation between the surface pollution originated from ships, and the general characteristics of spatial and temporal distribution of oil products in the water column in the Southeastern Baltic Sea. Areas with heightened concentrations of oil products in the surface and bottom layers wer...

  6. Reconstructing ozone chemistry from Asian wild fires using models, satellite and aircraft measurements during the ARCTAS campaign

    OpenAIRE

    R. Dupont; Pierce, B; Worden, J.; J. Hair; Fenn, M.; P. Hamer; Natarajan, M; T. Schaack; Lenzen, A.; Apel, E.; J. Dibb; G. Diskin; Huey, G.; A. Weinheimer; Knapp, D.

    2010-01-01

    We use ozone (O3) and carbon monoxide (CO) satellite measurements from the Tropospheric Emission Spectrometer (TES), simulations from the Real-time Air Quality Modeling System (RAQMS) and aircraft data from the NASA DC8 aircraft to characterize the chemical and dynamical evolution of Asian wildfire plumes during the spring ARCTAS campaign 2008. On the 19 April, NASA DC8 O3 and aerosol Differential Absorption Lidar (DIAL) observed two biomass burni...

  7. Validation of ACE-FTS satellite data in the upper troposphere/lower stratosphere (UTLS using non-coincident measurements

    Directory of Open Access Journals (Sweden)

    M. I. Hegglin

    2007-09-01

    Full Text Available CO, O3, and H2O data in the upper troposphere/lower stratosphere (UTLS measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS on Canada's SCISAT-1 satellite are validated using aircraft measurements. In the UTLS, validation of chemical trace gas measurements is a challenging task due to small-scale variability in the tracer fields, strong gradients of the tracers across the tropopause, and scarcity of measurements suitable for validation purposes. Two alternative methods for the validation of the satellite data are introduced, which avoid the usual need for coincident measurements: tracer-tracer correlations, and vertical profiles relative to the tropopause height. Both largely reduce geophysical variability and thereby provide an "instantaneous climatology", allowing measurement comparison with non-coincident data which yields information about the precision, and a statistically meaningful error-assessment of the ACE-FTS satellite data. We found that the ACE-FTS CO and lower stratospheric O3 agree with the aircraft measurements within ±10% and ±5%, respectively. The ACE-FTS O3 in the UT exhibits a high bias of up to 40%. H2O indicates a low bias with relative differences of around 20% in the LS and 40% in the UT, respectively. When taking into account the smearing effect of the vertically limited spacing between measurements of the ACE-FTS instrument, the errors decrease by 5–15% around the tropopause. The ACE-FTS instrument hence offers unprecedented precision and vertical resolution in the UTLS, that will allow a new global perspective on UTLS tracer distributions.

  8. Comparisons of optical properties of the coastal ocean derived from satellite ocean color and in situ measurements.

    Science.gov (United States)

    Chang, Grace C; Gould, Richard W

    2006-10-30

    Satellite-derived optical properties are compared to in situ mooring and ship-based measurements at a coastal site. Comparisons include remote sensing reflectance (R(rs)), chlorophyll concentration (Chl) using two different Chl algorithms, and spectral absorption [a(pg)(lambda)] and backscattering coefficients [b(b)(555)] using three different bio-optical algorithms. For mooring/shipboard comparisons, we observed mean relative errors of 70.5%/-3.8% (SeaWiFS OC4v4), -21.4%/-49.3% (SeaWiFS Stumpf), 109.5%/13.4% (MODIS OC3m) and 0.5%/-48.9% (MODIS Stumpf) for Chl. For satellite-derived and mooring comparisons of a(pg)(412), we found mean relative errors of -69.4% (-67.1%), -52.6% (- 48.9%), and -62.7% (-65.4%) for the Arnone, GSM, and QAA algorithms for SeaWiFS (MODIS), respectively. Mean relative errors of 21.3%, 19.9%, and 16.5% were found between SeaWiFS-derived (Arnone, GSM, and QAA algorithms, respectively) and moored b(b)(555) measurements. Discrepancies in Rrs at blue wavelengths are attributed to the satellite atmospheric correction and sea surface variations of the moored radiometers. High spatial and temporal variability of bio-optical properties coupled with differences in measurement techniques (pixel versus point) contribute to inconsistencies between remotely sensed and in situ biooptical properties. PMID:19529411

  9. Ground and CHAMP observations of field-aligned current circuits generated by lower atmospheric disturbances and expectations to the SWARM to clarify their three dimensional structure

    Science.gov (United States)

    Iyemori, Toshihiko; Nakanishi, Kunihito; Aoyama, Tadashi; Lühr, Hermann

    2014-05-01

    Acoustic gravity waves propagated to the ionosphere cause dynamo currents in the ionosphere. They divert along geomagnetic field lines of force to another hemisphere accompanying electric field and then flow in the ionosphere of another hemisphere by the electric field forming closed current circuits. The oscillating current circuits with the period of acoustic waves generate magnetic variations on the ground, and they are observed as long period geomagnetic pulsations. This effect has been detected during big earthquakes, strong typhoons, tornados etc. On a low-altitude satellite orbit, the spatial distribution (i.e., structure) of the current circuits along the satellite orbit should be detected as temporal magnetic oscillations, and the effect is confirmed by a CHAMP data analysis. On the spatial structure, in particular, in the longitudinal direction, it has been difficult to examine by a single satellite or from ground magnetic observations. The SWARM satellites will provide an unique opportunity to clarify the three dimensional structure of the field-aligned current circuits.

  10. Extracting Ocean-Generated Tidal Magnetic Signals from Swarm Data through Satellite Gradiometry

    DEFF Research Database (Denmark)

    Sabaka, Terence J.; Tyler, Robert H.; Olsen, Nils

    2016-01-01

    constellation provides important north-south along-track gradiometry information, it is the unique low spacecraft pair that allows for east-west cross-track gradiometry. This latter type is crucial in delivering an M2 estimate of similar quality with that derived from over 10 yrs of CHAMP satellite data, but...

  11. Assessment of the Global Monthly Mean Surface Insolation Estimated from Satellite Measurements Using Global Energy Balance Archive Data.

    Science.gov (United States)

    Li, Zhanqing; Whitlock, Charles H.; Charlock, Thomas P.

    1995-02-01

    Global datasets of surface radiation budget (SRB) have been obtained from satellite programs. These satellite-based estimates need validation with ground-truth observations. This study validates the estimates of monthly mean surface insolation contained in two satellite-based SRB datasets with the surface measurements made at worldwide radiation stations from the Global Energy Balance Archive (GEBA). One dataset was developed from the Earth Radiation Budget Experiment (ERBE) using the algorithm of Li et al. (ERBE/SRB), and the other from the International Satellite Cloud Climatology Project (ISCCP) using the algorithm of Pinker and Laszlo and that of Staylor (GEWEX/SRB). Since the ERBE/SRB data contain the surface net solar radiation only, the values of surface insolation were derived by making use of the surface albedo data contained in the GEWEX/SRB product. The resulting surface insolation has a bias error near zero and a root-mean-square error (RMSE) between 8 and 28 W m2. The RMSE is mainly associated with poor representation of surface observations within a grid cell. When the number of surface observations are sufficient, the random error is estimated to be about 5 W m2 with present satellite-based estimates. In addition to demonstrating the strength of the retrieving method, the small random error demonstrates how well the ERBE derives the monthly mean fluxes at the top of the atmosphere (TOA). A larger scatter is found for the comparison of transmissivity than for that of insolation. Month to month comparison of insolation reveals a weak seasonal trend in bias error with an amplitude of about 3 W m2. As for the insolation data from the GEWEX/SRB, larger bias errors of 5-10 W m2 are evident with stronger seasonal trends and almost identical RMSEs.

  12. The effect of ancillary data on components of the earth's radiation budget as computed from satellite measurements

    International Nuclear Information System (INIS)

    Full text: Various ancillary data, describing the radiative transfer properties of the atmosphere and of the erth's surface, are required to determine the cloud field properties within the atmosphere and the radiation budget components at its boundaries from related satellite measurements. These is in particular. information on the surface reflectance and skin temperature to identify clouds and aerosols in the troposphere. Vertical profiles of atmospheric gas concentrations and of the aerosols as well are often proscribed from direct sampling over a small ensemble of areas. Most quantities undergo in particular over continents strong diurnal variations. Such information on quantities, which often vary strongly in space and time, needs also be derived from satellite measurements. Thus it is expected that it contains systematic errors and also artefacts which are expected to propagate into the final results on the Earth's cloud fields and radiation budget components. With examples from the International Satellite Cloud Climatology Project (ISCCP), from the GEWEX Surface Radiation Budget Project (SRB) and the Cloud and Radiation Experiments (CERES), which all aim for global fields and long time series, we were able to identify error sources, which if not corrected already lead to erroneous conclusions in the interpretation of time series. During the presentation several examples will be discussed including also methodological errors (e.g. computation of the insolation at the Top of the Atmosphere and of the Pinatubo aerosol clouds). We conclude, that at least all data of these three projects need to be re-analyzed preceded by a reanalysis of all ancillary data. This conclusion hold also for all other project making use of the results of all three projects including the retrieval of aerosols from satellite measurements. The presently available data sets of all three projects should not yet be used for analyses of longer time series. Our efforts are part of a complete

  13. Validity of satellite measurements used for the monitoring of UV radiation risk on health

    Directory of Open Access Journals (Sweden)

    F. Jégou

    2011-06-01

    Full Text Available In order to test the validity of ultraviolet index (UVI satellite products and UVI model simulations for general public information, intercomparison involving three satellite instruments (SCIAMACHY, OMI and GOME-2, the Chemistry and Transport Model, Modélisation de la Chimie Atmosphérique Grande Echelle (MOCAGE, and ground-based instruments was performed in 2008 and 2009. The intercomparison highlighted a systematic high bias of ~1 UVI in the OMI clear-sky products compared to the SCIAMACHY and TUV model clear-sky products. The OMI and GOME-2 all-sky products are close to the ground-based observations with a low 6 % positive bias, comparable to the results found during the satellite validation campaigns. This result shows that OMI and GOME-2 all-sky products are well appropriate to evaluate the UV-risk on health. The study has pointed out the difficulty to take into account either in the retrieval algorithms or in the models, the large spatial and temporal cloud modification effect on UV radiation. This factor is crucial to provide good quality UV information. OMI and GOME-2 show a realistic UV variability as a function of the cloud cover. Nevertheless these satellite products do not sufficiently take into account the radiation reflected by clouds. MOCAGE numerical forecasts show good results during periods with low cloud covers, but are actually not adequate for overcast conditions; this is why Météo-France currently uses human-expertised cloudiness (rather than direct outputs from Numerical Prediction Models together with MOCAGE clear-sky UV indices for its operational forecasts. From now on, the UV monitoring could be done using free satellite products (OMI, GOME-2 and operational forecast for general public by using modelling, as long as cloud forecasts and the parametrisation of the impact of cloudiness on UV radiation are adequate.

  14. Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

    Science.gov (United States)

    Schweitzer, S.; Kirchengast, G.; Proschek, V.

    2011-10-01

    LEO-LEO infrared-laser occultation (LIO) is a new occultation technique between Low Earth Orbit (LEO) satellites, which applies signals in the short wave infrared spectral range (SWIR) within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO) method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity) and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms) of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We conclude that

  15. Evapotranspiration Estimation over Yangtze River Basin from GRACE satellite measurement and in situ data

    Science.gov (United States)

    Li, Qiong; Luo, Zhicai; Zhong, Bo; Wang, Haihong; Zhou, Zebing

    2016-04-01

    As the critical component of hydrologic cycle, evapotranspiration (ET) plays an important role in global water exchanges and energy flow across the hydrosphere, atmosphere and biosphere. Influenced by the Asian monsoon, the Yangtze River Basin (YRB) suffer from the several severe floods and droughts over the last decades due to the significant difference between temporal and spatial distribution terrestrial water storages. As an indispensable part, it is practically important to assessment ET in the YRB accompany with increased population and rapid economic and agriculture development. Average ET over the YRB is computed as the residual of terrestrial water budget using the Gravity Recovery and Climate Experiment (GRACE) satellite-based measurements and the ground-based observations. The GRACE-based ET were well coincidence with the ET from MODIS, with the correlation coefficient of 0.853, and the correlation coefficient is 0.696 while comparing with the ET ground-based observation. The mean monthly average of ET from these various estimates is 56.9 mm/month over the whole YRB, and peak between June and August. Monthly variations of ET reach a maximum in Wujiang with 69.11 mm/month and a minimum in Jinshajiang with 39.01 mm/month. Based on the correlation between ET and independent estimates of near-surface temperature and soil moisture, it is showed that as the temperature increased, the ET of the seven sub-catchment were rising except for the Poyang Lake and Donting Lake. And we also can infer that the midstream of YRB is significant correlated with ESON especially in the Hanjiang basin. The Surface Humidity Index over the YRB was gradually decreased and its variations in each sub-catchment showed a significant decreasing trend in Jinshajiang and Mingjiang. This research has important potential for use in large-scale water budget assessments and intercomparison studies. Acknowledgements: This research is supported by the National Natural Science Foundation of

  16. Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

    Directory of Open Access Journals (Sweden)

    S. Schweitzer

    2011-10-01

    Full Text Available LEO-LEO infrared-laser occultation (LIO is a new occultation technique between Low Earth Orbit (LEO satellites, which applies signals in the short wave infrared spectral range (SWIR within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We

  17. Biogeography and phenology of satellite-measured phytoplankton seasonality in the California current

    Science.gov (United States)

    Foukal, Nicholas P.; Thomas, Andrew C.

    2014-10-01

    Thirteen years (1998-2010) of satellite-measured chlorophyll a are used to establish spatial patterns in climatological phytoplankton biomass seasonality across the California Current System (CCS) and its interannual variability. Multivariate clustering based on the shape of the local climatological seasonal cycle divides the study area into four groups: two with spring-summer maxima representing the northern and southern coastal upwelling zones, one with a summer minimum offshore in mid-latitudes and a fourth with very weak seasonality in between. Multivariate clustering on the seasonal cycles from all 13 years produces the same four seasonal cycle types and provides a view of the interannual variability in seasonal biogeography. Over the study period these seasonal cycles generally appear in similar locations as the climatological clusters. However, considerable interannual variability in the geography of the seasonal cycles is evident across the CCS, the most spatially extensive of which are associated with the 1997-1999 El Niño-Southern Oscillation (ENSO) signal and the 2005 delayed spring transition off the Oregon and northern and central California coasts. We quantify linear trends over the study period in the seasonal timing of the two seasonal cycles that represent the biologically productive coastal upwelling zones using four different metrics of phenology. In the northern upwelling region, the date of the spring maximum is delaying (1.34 days yr-1) and the central tendency of the summer elevated chlorophyll period is advancing (0.63 days yr-1). In the southern coastal upwelling region, both the initiation and cessation of the spring maximum are delaying (1.78 days yr-1 and 2.44 days yr-1, respectively) and the peak is increasing in duration over the study period. Connections between observed interannual shifts in phytoplankton seasonality and physical forcing, expressed as either basin-scale climate signals or local forcing, show phytoplankton

  18. Extracting ocean-generated tidal magnetic signals from Swarm data through satellite gradiometry

    Science.gov (United States)

    Sabaka, Terence J.; Tyler, Robert H.; Olsen, Nils

    2016-04-01

    Ocean-generated magnetic field models of the Principal Lunar, M2, and the Larger Lunar elliptic, N2, semidiurnal tidal constituents were estimated through a "Comprehensive Inversion" of the first 20.5 months of magnetic measurements from European Space Agency's (ESA) Swarm satellite constellation mission. While the constellation provides important north-south along-track gradiometry information, it is the unique low-spacecraft pair that allows for east-west cross-track gradiometry. This latter type is crucial in delivering an M2 estimate of similar quality with that derived from over 10 years of CHAMP satellite data but over a shorter interval, at higher altitude, and during more magnetically disturbed conditions. Recovered N2 contains nonoceanic signal but is highly correlated with theoretical models in regions of maximum oceanic amplitude. Thus, satellite magnetic gradiometry may eventually enable the monitoring of ocean electrodynamic properties at temporal resolutions of 1 to 2 years, which may have important implications for the inference of ocean temperature and salinity.

  19. Extracting Ocean-Generated Tidal Magnetic Signals from Swarm Data Through Satellite Gradiometry

    Science.gov (United States)

    Sabaka, Terence J.; Tyler, Robert H.; Olsen, Nils

    2016-01-01

    Ocean-generated magnetic field models of the Principal Lunar, M2, and the Larger Lunar elliptic, N2, semidiurnal tidal constituents were estimated through a "Comprehensive Inversion" of the first 20.5 months of magnetic measurements from European Space Agency's (ESA) Swarm satellite constellation mission. While the constellation provides important north-south along-track gradiometry information, it is the unique low-spacecraft pair that allows for east-west cross-track gradiometry. This latter type is crucial in delivering an M2 estimate of similar quality with that derived from over 10 years of CHAMP satellite data but over a shorter interval, at higher altitude, and during more magnetically disturbed conditions. Recovered N2 contains nonoceanic signal but is highly correlated with theoretical models in regions of maximum oceanic amplitude. Thus, satellite magnetic gradiometry may eventually enable the monitoring of ocean electrodynamic properties at temporal resolutions of 1 to 2 years, which may have important implications for the inference of ocean temperature and salinity.

  20. Preliminary study of a dust event over Beijing by using satellite data and ground-based measurements

    Science.gov (United States)

    Shen, Xianxia; Liu, Chaoshun; Shi, Runhe; Bai, Kaixu; Wang, Chao; Gao, Wei

    2013-09-01

    This paper discusses the analysis of the severe dust storm that occurred over Beijing from 26th April to 3rd May in 2012 with the use of combined satellite observations and ground-based measurements. In this study, we analyze the pollution characteristics of particulate matters near ground, with the main focus on spatio-temporal and vertical distributions of aerosol during this event by using ground-based Aerosol Robotic Network (AERONET), MODerate resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data. Results show that the Aerosol Optical Depth (AOD) measured at 550 nm from the AERONET Beijing station has an ascending trend with a peak value of 2.5 on 1st May. Moreover, the AOD variation from the MODIS data agrees well with AERONET observations during the same time period. In addition, the vertical distribution of total attenuated backscatter coefficient (TABC), volume depolarization ratio (VDR) and color ratio (CR) of CALIPSO data are comprehensively analyzed. Results from these analyses show that the dust mainly accumulates in the layer at altitudes of 1.5 to 4.5 km on 1st May. In this dust layer, the values of TABC are generally around 0.002~0.0045 km-1sr-1 and VDR and CR are typically around 0.1~0.5 and 0.6~1.4 respectively. Thus, the combined satellite and ground-based observations are of great use for monitoring and analyzing air quality with high accuracy.

  1. Comparative Analysis of Satellite Measurements Calculation Results Using the Postprocessing Services: Asg-Eupos (Poland), Apps (USA) and CSRS (Canada)

    Science.gov (United States)

    Mika, Monika; Kudach, Jakub

    2014-06-01

    The publication has a cognitive research character. It presents a comparative analysis of free Internet services in Poland and abroad, used to adjust the data obtained using satellite measurement techniques. The main aim of this work is to describe and compare free tools for satellite data processing and to examine them for possible use in the surveying works in Poland. Among the many European and global services three of them dedicated to satellite measurements were selected: ASG-EUPOS (Poland), APPS (USA) and CSRS (Canada). The publication contains the results of calculations using these systems. Calculations were based on RINEX files obtained via postprocessing service (ASG-EUPOS network) POZGEO D for 12 reference stations in the South Poland. In order to examine differences in results between the ASG-EUPOS, APPS and CSRS the transformation points coordinate to a single coordinate system ETRF 2000 (in force in Poland) was made. Studies have shown the possibility of the calculation in Poland (in postprocessing mode) using the analyzed applications with global coverage.

  2. Performance Measurements of the Submillimeter Wave Astronomy Satellite (SWAS) Solar Array Deployment System

    OpenAIRE

    Sneiderman, Gary

    1995-01-01

    This paper discusses some unique features of the solar array deployment system used on the Submillimeter Wave Astronomy Satellite (SWAS). The mechanism system is highly optimized, incorporates no single-use components, and is fully testable in a one-"g" environment. A single High Output Paraffin (HOP) linear actuator drives the mechanisms used to deploy and lock each wing of solar array panels. The solar arrays open slowly, requiring only enough force to overcome inefficiencies and friction. ...

  3. Anomaly crust fields from MAGSAT satellite measurements:their processing and interpretation

    OpenAIRE

    A. K. Frunze; A. L. Kharitonov; N. M. Rotanova

    2004-01-01

    The space distribution of the magnetic anomaly field for the Pacific Ocean is obtained from data of the satellite MAGSAT. A number of long-wavelength magnetic anomalies of the region are identified. A spectrum analysis of a number of profiles of the anomaly field is performed disclosing typical scales of such anomalies. The wave transform of the anomaly magnetic profiles reveals and explicitly exposes the structure of the considered profile. A schematic complex cross-section is construct...

  4. Measuring water storage fluctuations in lake Dongting, China, by Topex/Poseidon satellite altimetry.

    Science.gov (United States)

    Zhang, Jiqun; Xu, Kaiqin; Yang, Yonghui; Qi, Lianhui; Hayashi, Seiji; Watanabe, Masataka

    2006-04-01

    Although satellite radar altimetry was developed and optimized for open oceans, it has been used to monitor variations in the level of inland water-bodies such as lakes and rivers. Here, for the first time, we have further used the altimetry-derived variation of water level for estimating the fluctuation of water storage as an addition to the present in situ water storage estimation systems to be used in remote areas and in emergency situation such as in the events flooding monitoring and for studying the effect of climate change. Lake Dongting, the second largest lake in China, influenced frequently by flooding, was, therefore, chosen to demonstrate the potential of the technique. By using the concept of an "assumed reference point", we converted Topex/Poseidon satellite altimetry data on water level variations in Lake Dongting to "water level" data. The "water level" time-series data and in situ water storage were used to establish a rating curve. From the rating curve, we converted data on "water level" derived from seven years (1993-1999) of Topex/Poseidon data to actual water storage in Lake Dongting. The result reveals that the seasonal and annual fluctuations of water storage occurred during the 1990s with a more frequent flooding at the late 1990s' especially the flooding in whole catchment level in 1998 and 1999. The study supports the usefulness of satellite altimetry for dense and continuous monitoring of the temporal variations in water dynamic in moderate to large lakes. PMID:16502025

  5. The first estimates of global nucleation mode aerosol concentrations based on satellite measurements

    Directory of Open Access Journals (Sweden)

    M. Kulmala

    2011-11-01

    Full Text Available Atmospheric aerosols play a key role in the Earth's climate system by scattering and absorbing solar radiation and by acting as cloud condensation nuclei. Satellites are increasingly used to obtain information on properties of aerosol particles with a diameter larger than about 100 nm. However, new aerosol particles formed by nucleation are initially much smaller and grow into the optically active size range on time scales of many hours. In this paper we derive proxies, based on process understanding and ground-based observations, to determine the concentrations of these new particles and their spatial distribution using satellite data. The results are applied to provide seasonal variation of nucleation mode concentration. The proxies describe the concentration of nucleation mode particles over continents. The source rates are related to both regional nucleation and nucleation associated with more restricted sources. The global pattern of nucleation mode particle number concentration predicted by satellite data using our proxies is compared qualitatively against both observations and global model simulations.

  6. The solar activity dependence of nonmigrating tides in electron density at low and middle latitudes observed by CHAMP and GRACE

    Science.gov (United States)

    Zhou, Yun-Liang; Wang, Li; Xiong, Chao; Lühr, Hermann; Ma, Shu-Ying

    2016-04-01

    In this paper we use more than a decade of in situ electron density observations from CHAMP and GRACE satellites to investigate the solar activity dependence of nonmigrating tides at both low and middle latitudes. The results indicate that the longitudinal patterns of F region electron density vary with season and latitude, which are exhibiting a wavenumber 4 (WN4) pattern around September equinox at low latitudes and WN1/WN2 patterns during local summer at the southern/northern middle latitudes. These wave patterns in the F region ionosphere can clearly be seen during both solar maximum and minimum years. At low latitudes the absolute amplitudes of DE3 (contributing to the WN4 pattern) are found to be highly related to the solar activity, showing larger amplitudes during solar maximum years. Similarly a solar activity dependence can also be found for the absolute amplitudes of D0, DW2 and DE1 (contributing to the WN1 and WN2 pattern) at middle latitudes. The relative amplitudes (normalized by the zonal mean) of these nonmigrating tides at both low and middle altitudes show little dependence on solar activity. We further found a clear modulation by the quasi-biennial oscillation (QBO) of the relative DE3 amplitudes in both satellite observations, which is consistent with the QBO dependence as reported for the E region temperatures and zonal wind. It also supports the strong coupling of the low-latitude nonmigrating tidal activity between the E and F regions. However, the QBO dependence cannot be found for the relative amplitudes of the nonmigrating tides at middle latitudes, which implies that these tides are generated in situ at F region altitudes.

  7. Storm time dynamics of auroral electrojets: CHAMP observation and the Space Weather Modeling Framework comparison

    Directory of Open Access Journals (Sweden)

    H. Wang

    2008-03-01

    Full Text Available We investigate variations of the location and intensity of auroral currents during two magnetic storm periods based on magnetic field measurements from CHAMP separately for both hemispheres, as well as for the dayside and nightside. The corresponding auroral electrojet current densities are on average enhanced by about a factor of 7 compared to the quiet time current strengths. The nightside westward current densities are on average 1.8 (2.2 times larger than the dayside eastward current densities in the Northern (Southern Hemisphere. Both eastward and westward currents are present during the storm periods with the most intense electrojets appearing during the main phase of the storm, before the ring current maximizes in strength. The eastward and westward electrojet centers can expand to 55° MLat during intense storms, as is observed on 31 March 2001 with Dst=−387 nT. The equatorward shift of auroral currents on the dayside is closely controlled by the southward IMF, while the latitudinal variations on the nightside are better described by the variations of the Dst index. However, the equatorward and poleward motion of the nightside auroral currents occur earlier than the Dst variations. The Space Weather Modeling Framework (SWMF can capture the general dynamics of the storm time current variations. Both the model and the actual data show that the currents tend to saturate when the merging electric field is larger than 10 mV/m. However, the exact prediction of the temporal development of the currents is still not satisfactory.

  8. Measurements and IRI Model Predictions During the Recent Solar Minimum

    Science.gov (United States)

    Bilitza, Dieter; Brown, Steven A.; Wang, Mathew Y.; Souza, Jonas R.; Roddy, Patrick A.

    2012-01-01

    Cycle 23 was exceptional in that it lasted almost two years longer than its predecessors and in that it ended in an extended minimum period that proved all predictions wrong. Comparisons of the International Reference Ionosphere (IRI) with CHAMP and GRACE in-situ measurements of electron density during the minimum have revealed significant discrepancies at 400-500 km altitude. Our study investigates the causes for these discrepancies with the help of ionosonde and Planar Langmuir Probe (PLP) data from the Communications/Navigation Outage Forecasting System (C/NOFS) satellite. Our C/NOFS comparisons confirm the earlier CHAMP and GRACE results. But the ionosonde measurements of the F-peak plasma frequency (foF2) show generally good agreement throughout the whole solar cycle. At mid-latitude stations yearly averages of the data-model difference are within 10% and at low latitudes stations within 20%. The 60-70% differences found at 400-500 km altitude are not seen at the F peak. We will discuss how these seemingly contradicting results from the ionosonde and in situ data-model comparisons can be explained and which parameters need to be corrected in the IRI model.

  9. A possible experiment with two counter-orbiting drag-free satellites to obtain a new test of Einstein's general theory of relativity and improved measurements in geodesy

    Science.gov (United States)

    Van Patten, R. A.; Everitt, C. W. F.

    1976-01-01

    In 1918, Lense and Thirring calculated that a moon in orbit around a massive rotating planet would experience a nodal dragging effect due to general relativity. We describe an experiment to measure this effect by means of two counter-orbiting drag-free satellites in polar orbit about the earth. For a 2-1/2 year experiment, the measurement should approach an accuracy of 1%. An independent measurement of the geodetic precession of the orbit plane due to the motion about the sun may also be possible to about 10% accuracy. In addition to precision tracking data from existing ground stations, satellite-to-satellite Doppler data are taken at points of passing near the poles to yield an accurate measurement of the separation distance between the two satellites. New geophysical information on both earth harmonics and tidal effects is inherent in this polar ranging data.

  10. Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

    Directory of Open Access Journals (Sweden)

    S. Schweitzer

    2011-05-01

    Full Text Available LEO-LEO infrared-laser occultation (LIO is a new occultation technique between Low Earth Orbit (LEO satellites, which applies signals in the short wave infrared spectral range (SWIR within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO method, recently introduced by Kirchengast and Schweitzer (2011, that enables to retrieve thermodynamic profiles (pressure, temperature, humidity and accurate altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. For enabling trace species retrieval based on differential transmission, the LIO signals are spectrally located as pairs, one in the centre of a suitable absorption line of a target species (absorption signal and one close by but outside of any absorption lines (reference signal. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss the atmospheric influences on the transmission and differential transmission of LIO signals. Refraction effects, trace species absorption (by target species, and cross-sensitivity to foreign species, aerosol extinction and Rayleigh scattering are studied in detail. The influences of clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation are discussed as well. We show that the influence of defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle and by a design with close frequency spacing of absorption and reference signals within 0.5 %. The influences of Rayleigh scattering and thermal radiation on the received signal intensities are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions but this

  11. Feasibility of tropical cyclone intensity estimation using satellite-borne radiometer measurements: An observing system simulation experiment

    Science.gov (United States)

    Sieron, Scott B.; Zhang, Fuqing; Emanuel, Kerry A.

    2013-10-01

    study evaluates the potential of a proposed technique in using satellite-borne radiometer measurements and weather analyses to estimate the intensity of tropical cyclones. This theory shows that intensity is essentially directly related to the temperature deficit of cloud top versus sea surface, and the surplus in saturation entropy in the eyewall versus its surroundings. The eyewall entropy estimate comes from measurements of cloud top temperature and pressure, and the analysis provides the environmental saturation entropy. An Observing Systems Simulation Experiment was conducted, and the results were compared to those from previous studies using cloud-profiling radar altimetry measurements. The use of cloud top pressure measurements may produce more accurate results. Inherent challenges still require caution in considering operational implementation.

  12. Upper ocean fine-scale features in synthetic aperture radar imagery. Part I: Simultaneous satellite and in-situ measurements

    Science.gov (United States)

    Soloviev, A.; Maingot, C.; Matt, S.; Fenton, J.; Lehner, S.; Brusch, S.; Perrie, W. A.; Zhang, B.

    2011-12-01

    The new generation of synthetic aperture radar (SAR) satellites provides high resolution images that open new opportunities for identifying and studying fine features in the upper ocean. The problem is, however, that SAR images of the sea surface can be affected by atmospheric phenomena (rain cells, fronts, internal waves, etc.). Implementation of in-situ techniques in conjunction with SAR is instrumental for discerning the origin of features on the image. This work is aimed at the interpretation of natural and artificial features in SAR images. These features can include fresh water lenses, sharp frontal interfaces, internal wave signatures, as well as slicks of artificial and natural origin. We have conducted field experiments in the summer of 2008 and 2010 and in the spring of 2011 to collect in-situ measurements coordinated with overpasses of the TerraSAR-X, RADARSAT-2, ALOS PALSAR, and COSMO SkyMed satellites. The in-situ sensors deployed in the Straits of Florida included a vessel-mounted sonar and CTD system to record near-surface data on stratification and frontal boundaries, a bottom-mounted Nortek AWAC system to gather information on currents and directional wave spectra, an ADCP mooring at a 240 m isobath, and a meteorological station. A nearby NOAA NEXRAD Doppler radar station provided a record of rainfall in the area. Controlled releases of menhaden fish oil were performed from our vessel before several satellite overpasses in order to evaluate the effect of surface active materials on visibility of sea surface features in SAR imagery under different wind-wave conditions. We found evidence in the satellite images of rain cells, squall lines, internal waves of atmospheric and possibly oceanic origin, oceanic frontal interfaces and submesoscale eddies, as well as anthropogenic signatures of ships and their wakes, and near-shore surface slicks. The combination of satellite imagery and coordinated in-situ measurements was helpful in interpreting fine

  13. Influence of ice particle model on retrieving cloud optical thickness from satellite measurements: model comparison and implication for climate study

    Directory of Open Access Journals (Sweden)

    Z. Zhang

    2009-01-01

    Full Text Available The influence is investigated of the assumed ice particle microphysical and optical model on inferring ice cloud optical thickness (τ from satellite measurements of the Earth's reflected shortwave radiance. Ice cloud τ are inferred, and subsequently compared, using products from MODIS (MODerate resolution Imaging Spectroradiometer and POLDER (POLarization and Directionality of the Earth's Reflectances. POLDER τ values are found to be substantially smaller than those from collocated MODIS data. It is shown that this difference is caused primarily by the use of different ice particle bulk scattering models in the two retrievals, and more specifically, the scattering phase function. Furthermore, the influence of the ice particle model on the derivation of ice cloud radiative forcing (CRF from satellite retrievals is studied. Three sets of shortwave CRF are calculated using different combinations of the retrieval and associated ice particle models. It is shown that the uncertainty associated with an ice particle model may lead to two types of errors in estimating CRF from satellite retrievals. One stems from the retrieval itself and the other is due to the optical properties, such as the asymmetry factor, used for CRF calculations. Although a comparison of the CRFs reveals that these two types of errors tend to cancel each other, significant differences are still found between the three CRFs, which indicates that the ice particle model affects not only optical thickness retrievals but also CRF calculations. In addition to CRF, the effect of the ice particle model on the derivation of seasonal variation of τ from satellite measurements is discussed. It is shown that optical thickness retrievals based on the same MODIS observations, but derived using different assumptions of the ice particle model, can be substantially different. These differences can be divided into two parts. The first-order difference is mainly caused by the

  14. The Influence of Satellite Center-of-gravity Measurement Error on the Baseline of Formation Flying Satellites%卫星质心测量误差对编队卫星基线的影响

    Institute of Scientific and Technical Information of China (English)

    秦显平

    2015-01-01

    针对卫星质心测量误差影响编队卫星基线的问题,首先从编队卫星相对定轨的原理出发,分析了卫星质心误差的影响,然后考虑到编队卫星有效基线通常为载荷天线之间的基线,提出了天线基线与质心基线的定义。采用2015-12-08两颗编队卫星的实测数据,计算分析了卫星质心测量误差对质心基线和天线基线的影响,结果表明:卫星质心测量误差对质心基线的影响明显大于对天线基线的影响;卫星质心测量误差对天线基线的影响约为质心测量误差的10%。%To the question of the influence of satellite center-of-gravity measurement error on the baseline of formation fly-ing satellites,the influence of satellite center-of-gravity measurement error was analyzed from the principle of formation flying satellites relative orbit determination firstly.Then,in view of the useful baseline is usually the distance between the payload in-struments of two satellites,the definition of the baseline of two payload instruments antennas and the baseline of two satellites center-of-gravity were established.The baseline of two formation flying satellites center-of-gravity and the baseline of two an-tennas were computed by using the global positioning system data observed December 8,2005.The results of computation show that the measurement error of the satellite center-of-gravity makes the baseline error of two satellites center-of-gravity greatly than that of two antennas.The two antennas baseline error is about 10 percent of the two satellites center-of-gravity baseline error.

  15. An automated fog monitoring system for the Indo-Gangetic Plains based on satellite measurements

    Science.gov (United States)

    Patil, Dinesh; Chourey, Reema; Rizvi, Sarwar; Singh, Manoj; Gautam, Ritesh

    2016-05-01

    Fog is a meteorological phenomenon that causes reduction in regional visibility and affects air quality, thus leading to various societal and economic implications, especially disrupting air and rail transportation. The persistent and widespread winter fog impacts the entire the Indo-Gangetic Plains (IGP), as frequently observed in satellite imagery. The IGP is a densely populated region in south Asia, inhabiting about 1/6th of the world's population, with a strong upward pollution trend. In this study, we have used multi-spectral radiances and aerosol/cloud retrievals from Terra/Aqua MODIS data for developing an automated web-based fog monitoring system over the IGP. Using our previous and existing methodologies, and ongoing algorithm development for the detection of fog and retrieval of associated microphysical properties (e.g. fog droplet effective radius), we characterize the widespread fog detection during both daytime and nighttime. Specifically, for the night time fog detection, the algorithm employs a satellite-based bi-spectral brightness temperature difference technique between two spectral channels: MODIS band-22 (3.9μm) and band-31 (10.75μm). Further, we are extending our algorithm development to geostationary satellites, for providing continuous monitoring of the spatial-temporal variation of fog. We anticipate that the ongoing and future development of a fog monitoring system would be of assistance to air, rail and vehicular transportation management, as well as for dissemination of fog information to government agencies and general public. The outputs of fog detection algorithm and related aerosol/cloud parameters are operationally disseminated via http://fogsouthasia.com/.

  16. Deforestation fires versus understory fires in the Amazon Basin: What can we learn from satellite-based CO measurements?

    Science.gov (United States)

    Martinez-Alonso, S.; Deeter, M. N.; Worden, H. M.; Gille, J. C.; Clerbaux, C.; George, M.

    2014-12-01

    Deforestation fires in the Amazon Basin abound during the dry season (July to October) and are mostly associated with "slash and burn" agricultural practices. Understory fires occur when fires escape from deforested areas into neighboring standing forests; they spread slowly below the canopy, affecting areas that may be comparable or even larger than clear-cut areas. The interannual variabilities of understory fires and deforestation rates appear to be uncorrelated. Areas burned in understory fires are particularly extensive during droughts. Because they progress below a canopy of living trees, understory fires and their effects are not as easily identifiable from space as deforestation fires. Here we analyze satellite remote sensing products for CO and fire to investigate differences between deforestation fires and understory fires in the Amazon Basin under varying climatic conditions. The MOPITT (Measurements Of Pollution In The Troposphere) instrument on board NASA's Terra satellite has been measuring tropospheric CO since 2000, providing the longest global CO record to date. IASI (the Infrared Atmospheric Sounding Interferometer) A and B are two instruments on board METOP-A and -B, respectively, measuring, among others, CO since 2006 and 2012. MODIS (the Moderate Resolution Imaging Spectroradiometer) instruments on board NASA's Terra and Aqua satellites provide, among other products, a daily record of fires and their effects since 2000 and 2002, respectively. The temporal extent of all these datasets allows for the detailed analysis of drought versus non-drought years. Initial results indicate that MOPITT CO emissions during the dry season peaked in 2005, 2007, and 2010. Those were draught years and coincide with peaks in area affected by understory fires.

  17. Measurement of the gravitational redshift effect with RadioAstron satellite

    CERN Document Server

    Birukov, A V; Litvinov, D A; Porayko, N K; Rudenko, V N

    2015-01-01

    RadioAstron satellite admits in principle a testing the gravitational redshift effect with an accuracy of better than $10^{-5}$. It would surpass the result of Gravity Probe A mission at least an order of magnitude. However, RadioAstron's communications and frequency transfer systems are not adapted for a direct application of the non relativistic Doppler and troposphere compensation scheme used in the Gravity Probe A experiment. This leads to degradation of the redshift test accuracy approximately to the level 0.01. We discuss the way to overcome this difficulty and present preliminary results based on data obtained during special observing sessions scheduled for testing the new techniques.

  18. On the Validation of Air Quality Models in Megacities using Satellite Measurements: A Case Study in the Pearl River Delta

    Science.gov (United States)

    Kuhlmann, Gerrit; Cheung, Hung-Ming; Hartl, Andreas; Wenig, Mark O.; Lam, Yun-Fat

    2014-05-01

    Recently, many efforts have been made to improve satellite measurements of air pollutants for applications on a regional scale [1-3]. These improved measurements can be used to validate chemistry transport simulations in megacities. However, special care must be taken for such validations, because the trace gas retrieval algorithm depends in part on the chemistry transport simulation itself. In our study, we compared chemistry transport simulations with nitrogen dioxide (NO2) measurements of the Ozone Monitoring Instrument (OMI) in the Pearl River Delta (PRD) megacity (South China). Our objective was to determine the feasibility to validate models using current satellite products. The Community Multiscale Air Quality (CMAQ) Modelling System, has been used to model air pollutants in winter 2006/2007. The model domain encloses the PRD with a horizontal grid resolution of 3 km. We included an improved vertical advection scheme and updated emissions using the newest inventory available. In the OMI NO2 retrieval algorithms [4,5], an air mass factor (AMF) converts slant column densities (SCD) to vertical column densities (VCD). The AMF describes the instrument sensitivity and depends on surface reflectance, atmospheric scattering and the NO2 profile shape. We computed improved AMFs with the radiative transfer model SCIATRAN using terrain height, NO2 profile shapes and aerosol profiles taken from CMAQ. These model-dependent parameter are validated with NO2 and aerosol concentrations of the PRD air quality network. Updated surface reflectances are taken from MODIS. The OMI measurements are mapped to the CMAQ grid using a newly developed gridding algorithm [6]. Finally, the VCDs have been converted to ground concentrations using the NO2 profile shapes. In our validation, we removed the dependency of the trace gase retrieval on a chemistry transport model. As a result, the retrieval uncertainties of the satellite product were reduced significantly. The approach allows to

  19. A neural network detection system for lower-hybrid cavities in electron plasma density measured by the FREJA satellite

    International Nuclear Information System (INIS)

    This paper presents a lower-hybrid cavity detection system, CDS, for measurements of electron plasma density on the FREJA satellite wave experiment. The system can reduce the amount of data to be analysed by as much as 96% and still retain more than 85% of the desired information. The CDS is a combination of a hybrid neural network, HNN and expert rules. The HNN is a Self Organizing Map, SOM, combined with a feed forward back propagation neural net, BP. The CDS can be controlled by the user to operate with various degrees of sensitivity. Maximum detection capability is as high as 95% with data reduction lowered to 85%. 10 refs

  20. Comparison of the simultaneous measurement results of SCR fluxes received by geostationary satellites 'Electro-L' and 'GOES'

    International Nuclear Information System (INIS)

    In the present paper the comparison of the results of the simultaneous measurements of solar proton fluxes on board geostationary satellites 'GOES' and 'Electro' was made for the purpose of calibration of 'Electro-L' detectors and determination of the possibility to utilize 'Electro-L' data for space weather monitoring. It was shown that the solar proton observation data on board 'Electro-L' recalculated to energy thresholds of 'GOES' 10 and 30 MeV are in a good consistent with 'GOES' data and may be used for control of radiation conditions in near-earth space.

  1. Peculiarities of distribution of oil polution in the Southeastern Baltic by satellite data and in situ measurements

    Science.gov (United States)

    Bulycheva, E. V.; Krek, A. V.; Kostianoy, A. G.

    2016-01-01

    The results of satellite monitoring of oil pollution of the sea surface and field measurements of the concentration of oil products in the water column and bottom sediments for the first time allowed the establishment of a relation between the surface pollution from ships and the general characteristics of spatial and temporal distribution of oil products in the Southeastern Baltic Sea. Areas with increased concentrations of oil products in the surface and bottom layers were determined in the southeastern Baltic Sea. The basic directions of pollution spread, which are consistent with the main direction of annual mean transport of substances in the Gdansk Basin, are determined.

  2. Improvements in Near-Terminator and Nocturnal Cloud Masks using Satellite Imager Data over the Atmospheric Radiation Measurement Sites

    Energy Technology Data Exchange (ETDEWEB)

    Trepte, Q.Z.; Minnis, P.; Heck, P.W.; Palikonda, R.

    2005-03-18

    Cloud detection using satellite measurements presents a big challenge near the terminator where the visible (VIS; 0.65 {micro}m) channel becomes less reliable and the reflected solar component of the solar infrared 3.9-{micro}m channel reaches very low signal-to-noise ratio levels. As a result, clouds are underestimated near the terminator and at night over land and ocean in previous Atmospheric Radiation Measurement (ARM) Program cloud retrievals using Geostationary Operational Environmental Satellite (GOES) imager data. Cloud detection near the terminator has always been a challenge. For example, comparisons between the CLAVR-x (Clouds from Advanced Very High Resolution Radiometer [AVHRR]) cloud coverage and Geoscience Laser Altimeter System (GLAS) measurements north of 60{sup o}N indicate significant amounts of missing clouds from AVHRR because this part of the world was near the day/night terminator viewed by AVHRR. Comparisons between MODIS cloud products and GLAS at the same regions also shows the same difficulty in the MODIS cloud retrieval (Pavolonis and Heidinger 2005). Consistent detection of clouds at all times of day is needed to provide reliable cloud and radiation products for ARM and other research efforts involving the modeling of clouds and their interaction with the radiation budget. To minimize inconsistencies between daytime and nighttime retrievals, this paper develops an improved twilight and nighttime cloud mask using GOES-9, 10, and 12 imager data over the ARM sites and the continental United States (CONUS).

  3. Dynamic and chemical controls on new particle formation occurrence and characteristics from in situ and satellite-based measurements

    Science.gov (United States)

    Sullivan, R. C.; Pryor, S. C.

    2016-02-01

    We analyze the association between satellite-based measurements of chemical conditions (sulfur dioxide (SO2), nitrogen dioxide (NO2), and formaldehyde (HCHO) concentrations), insolation (UV), and aerosol particle properties (aerosol optical depth (AOD) and Ångström exponent (AE)); and the occurrence of new particle formation (NPF), formation rates (J6), growth rates (GR), and survival probabilities (SP) using particle size distribution measurements taken during two extended field campaigns at a forested location in southern Indiana. When conditionally sampled by event occurrence and non-occurrence the satellite-derived parameters exhibit significant differences and also show some degree of skill in predicting NPF though logistic regression analysis. During leaf-on measurement periods, NPF occurrence exhibits strong seasonality (NPF is more frequent in spring vs. summer) and is associated with a low condensational sink, while leaf-off NPF occurrence is associated with high near-surface UV receipt. Multiple linear regression equations of J6, GR, and SP using the chemical conditions as predictors exhibit some significant r2 values (p regression coefficients do not differ significantly from zero.

  4. A comparison of ship and satellite measurements of cloud properties in the southeast Pacific stratus deck

    Directory of Open Access Journals (Sweden)

    M. A. Brunke

    2010-02-01

    Full Text Available Here, liquid water path (LWP, cloud fraction, cloud top height, and cloud base height are retrieved by a suite of satellite instruments (the CPR aboard CloudSat, CALIOP aboard CALIPSO, and MODIS aboard Aqua and compared to ship observations from research cruises made in 2001 and 2003–2007 into the stratus/stratocumulus deck over the southeast Pacific Ocean. It is found that CloudSat LWP is generally too high over this region and the CloudSat/CALIPSO cloud bases are too low which is to be expected from the increased sensitivity to precipitation by both the radar and lidar. This results in a relationship (LWP~h9 between CloudSat LWP and CALIPSO cloud thickness (h that is very different from the adiabatic relationship (LWP~h2 from in situ observations. Furthermore, comparing results from a global model (CAM3.1 to ship observations reveals that, while the simulated LWP is quite reasonable, the model cloud is too thick and too low, allowing the model to have LWPs that are almost independent of h. Such differences may be reduced in future versions of both the satellite data and the model.

  5. Comparison of Magnetic Anomalies of Lithospheric Origin Measured by Satellite and Airborne Magnetometers over Western Canada

    Science.gov (United States)

    Langel, R. A.; Coles, R. L.; Mayhew, M. A.

    1979-01-01

    Crustal magnetic anomaly data from the OGO 2, 4 and 6 (Pogo) satellites are compared with upward-continued aeromagnetic data between 50 deg -85 deg N latitude and 220 deg - 260 deg E longitude. Agreement is good both in anomaly location and in amplitude, giving confidence that it is possible to proceed with the derivation and interpretation of satellite anomaly maps in all parts of the globe. The data contain a magnetic high over the Alpha ridge suggesting continental composition and a magnetic low over the southern Canada basin and northern Canadian Arctic islands (Sverdrup basin). The low in the Sverdrup basin corresponds to a region of high heat flow, suggesting a shallow Curie isotherm. A ridge of high field, with two distinct peaks in amplitude, is found over the northern portion of the platform deposits and a relative high is located in the central portion of the Churchill province. No features are present to indicate a magnetic boundary between Slave and Bear provinces, but a trend change is evident between Slave and Churchill provinces. South of 60 deg latitude a broad magnetic low is located over very thick (40-50 km) crust, interpreted to be a region of low magnetization.

  6. Effect of active thunderstorm on ionospheric electron and ion temperatures as measured by the SROSS-C2 satellite

    International Nuclear Information System (INIS)

    Complete text of publication follows. It has been realized that the ionospheric temperatures and ion densities are influenced by the lightning/ Sprite activity. The ionospheric temperatures (electron and ion temperatures) were measured by the RPA payload aboard the Indian SROSS-C2. To see the effect of active thunderstorm the ionospheric electron and ion temperatures have been compared to the values on normal days. The data collected by SROSS-C2 satellite using RPA payload during the period from 1995-1998 has been analyzed for anomalous variations due to thunderstorm activity in the altitude range from 425 to 625 km. The data on thunderstorm activity for the same period was obtained from India Meteorological Department (IMD), Pune. The measurements corresponding to three different locations viz. Bhopal (23.16 deg N, 77.36 deg E), Panji (15.30 deg N, 73.55 deg E) and Trivandrum (08.29 deg N, 76.59 deg E) have been analyzed. It is a difficult task to study the ionospheric temperature using the satellite data in respect of thunderstorm activity because very rarely passes of satellite match the thunderstorm activity at a meteorological data station. The first task is to match the satellite data corresponding to the thunderstorms activities. During the period from 1995 to 1998, it has been found that seven events of thunderstorms correspond to the satellite data. The recorded average electron and ion temperature during active thunderstorms have been compared with the average normal days electron and ion temperature for the same time interval. Care has been taken to select the satellite data, which is free from diurnal, seasonal, latitudinal, longitudinal and altitude effects. The average of normal time electron and ion temperatures have been made for a month, starting almost 15 days before the thunderstorm day and continuing to 15 days more after that. Thus the possibility of seasonal effect has completely been ruled out because all data points correspond to the same

  7. Studies on aerosol properties during ICARB–2006 campaign period at Hyderabad, India using ground-based measurements and satellite data

    Indian Academy of Sciences (India)

    K V S Badarinath; Shailesh Kumar Kharol

    2008-07-01

    Continuous and campaign-based aerosol field measurements are essential in understanding fundamental atmospheric aerosol processes and for evaluating their effect on global climate, environment and human life. Synchronous measurements of Aerosol Optical Depth (AOD), Black Carbon (BC) aerosol mass concentration and aerosol particle size distribution were carried out during the campaign period at tropical urban regions of Hyderabad, India. Daily satellite datasets of DMSP-OLS were processed for night-time forest fires over the Indian region in order to understand the additional sources (forest fires) of aerosol. The higher values in black carbon aerosol mass concentration and aerosol optical depth correlated well with forest fires occurring over the region. Ozone Monitoring Instrument (OMI) aerosol index (AI) variations showed absorbing aerosols over the region and correlated with ground measurements.

  8. Measurements of tropospheric NO2 in Romania using a zenith-sky mobile DOAS system and comparisons with satellite observations.

    Science.gov (United States)

    Constantin, Daniel-Eduard; Merlaud, Alexis; Van Roozendael, Michel; Voiculescu, Mirela; Fayt, Caroline; Hendrick, François; Pinardi, Gaia; Georgescu, Lucian

    2013-01-01

    In this paper we present a new method for retrieving tropospheric NO2 Vertical Column Density (VCD) from zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements using mobile observations. This method was used during three days in the summer of 2011 in Romania, being to our knowledge the first mobile DOAS measurements peformed in this country. The measurements were carried out over large and different areas using a mobile DOAS system installed in a car. We present here a step-by-step retrieval of tropospheric VCD using complementary observations from ground and space which take into account the stratospheric contribution, which is a step forward compared to other similar studies. The detailed error budget indicates that the typical uncertainty on the retrieved NO2tropospheric VCD is less than 25%. The resulting ground-based data set is compared to satellite measurements from the Ozone Monitoring Instrument (OMI) and the Global Ozone Monitoring Experiment-2 (GOME-2). For instance, on 18 July 2011, in an industrial area located at 47.03°N, 22.45°E, GOME-2 observes a tropospheric VCD value of (3.4 ± 1.9) × 1015 molec./cm2, while average mobile measurements in the same area give a value of (3.4 ± 0.7) × 10(15) molec./cm2. On 22 August 2011, around Ploiesti city (44.99°N, 26.1°E), the tropospheric VCD observed by satellites is (3.3 ± 1.9) × 10(15) molec./cm2 (GOME-2) and (3.2 ± 3.2) × 10(15) molec./cm2 (OMI), while average mobile measurements give (3.8 ± 0.8) × 10(15) molec./cm2. Average ground measurements over "clean areas", on 18 July 2011, give (2.5 ± 0.6) × 10(15) molec./cm2 while the satellite observes a value of (1.8 ± 1.3) × 10(15) molec./cm2. PMID:23519349

  9. Measurements of Tropospheric NO2 in Romania Using a Zenith-Sky Mobile DOAS System and Comparisons with Satellite Observations

    Directory of Open Access Journals (Sweden)

    Gaia Pinardi

    2013-03-01

    Full Text Available In this paper we present a new method for retrieving tropospheric NO2 Vertical Column Density (VCD from zenith-sky Differential Optical Absorption Spectroscopy (DOAS measurements using mobile observations. This method was used during three days in the summer of 2011 in Romania, being to our knowledge the first mobile DOAS measurements peformed in this country. The measurements were carried out over large and different areas using a mobile DOAS system installed in a car. We present here a step-by-step retrieval of tropospheric VCD using complementary observations from ground and space which take into account the stratospheric contribution, which is a step forward compared to other similar studies. The detailed error budget indicates that the typical uncertainty on the retrieved NO2tropospheric VCD is less than 25%. The resulting ground-based data set is compared to satellite measurements from the Ozone Monitoring Instrument (OMI and the Global Ozone Monitoring Experiment-2 (GOME-2. For instance, on 18 July 2011, in an industrial area located at 47.03°N, 22.45°E, GOME-2 observes a tropospheric VCD value of (3.4 ± 1.9 × 1015 molec./cm2, while average mobile measurements in the same area give a value of (3.4 ± 0.7 × 1015 molec./cm2. On 22 August 2011, around Ploiesti city (44.99°N, 26.1°E, the tropospheric VCD observed by satellites is (3.3 ± 1.9 × 1015 molec./cm2 (GOME-2 and (3.2 ± 3.2 × 1015 molec./cm2 (OMI, while average mobile measurements give (3.8 ± 0.8 × 1015 molec./cm2. Average ground measurements over “clean areas”, on 18 July 2011, give (2.5 ± 0.6 × 1015 molec./cm2 while the satellite observes a value of (1.8 ± 1.3 × 1015 molec./cm2.

  10. A new natural hazards data-base for volcanic ash and SO2 from global satellite remote sensing measurements

    Science.gov (United States)

    Prata, F.; Stebel, K.

    2013-12-01

    Over the last few years there has been a recognition of the utility of satellite measurements to identify and track volcanic emissions that present a natural hazard to human populations. Mitigation of the volcanic hazard to life and the environment requires understanding of the properties of volcanic emissions, identifying the hazard in near real-time and being able to provide timely and accurate forecasts to affected areas. Amongst the many ways to measure volcanic emissions, satellite remote sensing is capable of providing global quantitative retrievals of important microphysical parameters such as ash mass loading, ash particle effective radius, infrared optical depth, SO2 partial and total column abundance, plume altitude, aerosol optical depth and aerosol absorbing index. The eruption of Eyjafjallajokull in April-May, 2010 led to increased research and measurement programs to better characterize properties of volcanic ash and the need to establish a data-base in which to store and access these data was confirmed. The European Space Agency (ESA) has recognized the importance of having a quality controlled data-base of satellite retrievals and has funded an activity (VAST) to develop novel remote sensing retrieval schemes and a data-base, initially focused on several recent hazardous volcanic eruptions. As a first step, satellite retrievals for the eruptions of Eyjafjallajokull, Grimsvotn, Puyhue-Cordon Caulle, Nabro, Merapi, Okmok, Kasatochi and Sarychev Peak are being considered. Here we describe the data, retrievals and methods being developed for the data-base. Three important applications of the data-base are illustrated related to the ash/aviation problem, to the impact of the Merapi volcanic eruption on the local population, and to estimate SO2 fluxes from active volcanoes-as a means to diagnose future unrest. Dispersion model simulations are also being included in the data-base. In time, data from conventional in situ sampling instruments, airborne and

  11. A study of Asian dust plumes using satellite, surface, and aircraft measurements during the INTEX-B field experiment

    Science.gov (United States)

    Logan, Timothy; Xi, Baike; Dong, Xiquan; Obrecht, Rebecca; Li, Zhanqing; Cribb, Maureen

    2010-04-01

    Asian dust events occur frequently during the boreal spring season. Their optical properties have been analyzed by using a combination of source region (ground-based and satellite) and remote Pacific Ocean (aircraft) measurements during the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B) field campaign which lasted from 7 April to 15 May 2006. A strong dust event originating from the Gobi Desert and passing over the Xianghe surface site on 17 April 2006 has been extensively analyzed. The surface averaged aerosol optical depth (AOD) values increased from 0.17 (clear sky) to 4.0 (strong dust), and the Angström exponent (α) dropped from 1.26 (clear sky) to below 0.1. Its total downwelling SW flux over the Xianghe site (thousands of kilometers away from the dust source region) is only 46% of the clear-sky value with almost no direct transmission and nearly double the diffuse SW clear-sky value. This event was also captured 6 days later by satellite observations as well as the UND/NASA DC-8 aircraft over the eastern Pacific Ocean. The DC-8 measurements in the remote Pacific region further classified the plumes into dust dominant, pollution dominant, and a mixture of dust and pollution events. HYSPLIT backward trajectories not only verified the origins of each case we selected but also showed (1) two possible origins for the dust: the Gobi and Taklimakan deserts; and (2) pollution: urban areas in eastern China, Japan, and other industrialized cities east of the two deserts. Based on the averaged satellite retrieved AOD data (0.5° × 0.5° grid box), declining AOD values with respect to longitude demonstrated the evolution of the transpacific transport pathway of Asian dust and pollution over the period of the field campaign.

  12. Angular velocity estimation from measurement vectors of star tracker.

    Science.gov (United States)

    Liu, Hai-bo; Yang, Jun-cai; Yi, Wen-jun; Wang, Jiong-qi; Yang, Jian-kun; Li, Xiu-jian; Tan, Ji-chun

    2012-06-01

    In most spacecraft, there is a need to know the craft's angular rate. Approaches with least squares and an adaptive Kalman filter are proposed for estimating the angular rate directly from the star tracker measurements. In these approaches, only knowledge of the vector measurements and sampling interval is required. The designed adaptive Kalman filter can filter out noise without information of the dynamic model and inertia dyadic. To verify the proposed estimation approaches, simulations based on the orbit data of the challenging minisatellite payload (CHAMP) satellite and experimental tests with night-sky observation are performed. Both the simulations and experimental testing results have demonstrated that the proposed approach performs well in terms of accuracy, robustness, and performance. PMID:22695598

  13. A Statistical Correlation Between Low L-shell Electrons Measured by NOAA Satellites and Strong Earthquakes

    Science.gov (United States)

    Fidani, C.

    2015-12-01

    More than 11 years of the Medium Energy Protons Electrons Detector data from the NOAA polar orbiting satellites were analyzed. Significant electron counting rate fluctuations were evidenced during geomagnetic quiet periods by using a set of adiabatic coordinates. Electron counting rates were compared to earthquakes by defining a seismic event L-shell obtained radially projecting the epicenter geographical positions to a given altitude. Counting rate fluctuations were grouped in every satellite semi-orbit together with strong seismic events and these were chosen with the L-shell coordinates close to each other. Electron data from July 1998 to December 2011 were compared for nearly 1,800 earthquakes with magnitudes larger than or equal to 6, occurring worldwide. When considering 30 - 100 keV energy channels by the vertical NOAA telescopes and earthquake epicenter projections at altitudes greater that 1,300 km, a 4 sigma correlation appeared where time of particle precipitations Tpp occurred 2 - 3 hour prior time of large seismic events Teq. This was in physical agreement with different correlation times obtained from past studies that considered particles with greater energies. The correlation suggested a 4-8 hour advance in preparedness of strong earthquakes influencing the ionosphere. Considering this strong correlation between earthquakes and electron rate fluctuations, and the hypothesis that such fluctuations originated with magnetic disturbances generated underground, a small scale experiment with low cost at ground level is advisable. Plans exists to perform one or more unconventional experiments around an earthquake affected area by private investor in Italy.

  14. Validation of three satellite-derived databases of surface solar radiation using measurements performed at 42 stations in Brazil

    Science.gov (United States)

    Thomas, Claire; Wey, Etienne; Blanc, Philippe; Wald, Lucien

    2016-06-01

    The SoDa website (www.soda-pro.com) is populated with numerous solar-related Web services. Among them, three satellite-derived irradiation databases can be manually or automatically accessed to retrieve radiation values within the geographical coverage of the Meteosat Second Generation (MSG) satellite: the two most advanced versions of the HelioClim-3 database (versions 4 and 5, respectively HC3v4 and HC3v5), and the CAMS radiation service. So far, these databases have been validated against measurements of several stations in Europe and North Africa only. As the quality of such databases depends on the geographical regions and the climates, this paper extends this validation campaign and proposes an extensive comparison on Brazil and global irradiation received on a horizontal surface. Eleven stations from the Brazilian Institute of Space Research (INPE) network offer 1 min observations, and thirty-one stations from the Instituto Nacional de Meteorologia (INMET) network offer hourly observations. The satellite-derived estimates have been compared to the corresponding observations on hourly, daily and monthly basis. The bias relative to the mean of the measurements for HC3v5 is mostly comprised between 1 and 3 %, and that for HC3v4 between 2 and 5 %. These are very satisfactory results and they demonstrate that HC3v5, and to a lesser extent HC3v4, may be used in studies of long-term changes in SSI in Brazil. The situation is not so good with CAMS radiation service for which the relative bias is mostly comprised between 5 and 10 %. For hourly irradiation, the relative RMSE ranges from 15 to 33 %. The correlation coefficient is very large for all stations and the three databases, with an average of 0.96. The three databases reproduce well the hour from hour changes in SSI. The errors show a tendency to increase with the viewing angle of the MSG satellite. They are greater in tropical areas where the relative humidity in the atmosphere is important. It is concluded

  15. POD improvements of GALILEO satellites through the measurement of their non-gravitational accelerations by means of an onboard accelerometer

    Science.gov (United States)

    Peron, Roberto; Lucchesi, David M.; Santoli, Francesco; Iafolla, Valerio; Fiorenza, Emiliano; Lefevre, Carlo; Lucente, Marco; Magnafico, Carmelo; Kalarus, Maciej; Zielinski, Janusz

    2016-04-01

    The Precise Orbit Determination (POD) of the satellites of the Global Navigation Satellite Systems (GNSS) represents the basic prerequisite in order to provide refined ephemerides for their orbit, aimed at providing a precise and accurate positioning on the Earth. An important factor that impacts negatively in the POD of these satellites is the limited modeling of the accelerations produced by the non-gravitational accelerations. These, indeed, are subtle and generally complex to model properly, especially in the case of a complex in shape spacecraft, with solar panels and antennae for microwave link and the mutual shadowing effects among the many surfaces involved. We have to notice that their modeling has an important impact in the determination of a number of geophysical parameters of interest, such as stations coordinates, Earth's geocenter and orientation parameters. In the case of GNSS satellites, the main NGP acceleration is the one produced by the direct solar radiation pressure, with non-negligible contributions due to Earth's albedo, thermal effects and power radiated by the antennae. The models developed so far for these perturbative effects have shown many limits, as pointed out in the literature. Currently, the models developed for the NGPs are mainly based on empirical blind models (with the goal of absorb unknowns quantities) and more recently with the use of wing-box models, that try to provide a finite-elements approach to the modeling. The European Space Agency (ESA) - in the context of the development of the GALILEO constellation, and especially in view of the next generation of GALILEO spacecraft - besides being interested in possible improvements of the NGPs models, is also envisaging the use of an onboard accelerometer to directly measure them in order to improve the POD of each spacecraft of the constellation. We have been involved in this study by means of a proposal to ESA denominated GALileo and ACcelerometry (GALAC) led by the Space

  16. Validation of three satellite-derived databases of surface solar radiation using measurements performed at 42 stations in Brazil

    Science.gov (United States)

    Thomas, Claire; Wey, Etienne; Blanc, Philippe; Wald, Lucien

    2016-06-01

    The SoDa website (www.soda-pro.com" target="_blank">www.soda-pro.com) is populated with numerous solar-related Web services. Among them, three satellite-derived irradiation databases can be manually or automatically accessed to retrieve radiation values within the geographical coverage of the Meteosat Second Generation (MSG) satellite: the two most advanced versions of the HelioClim-3 database (versions 4 and 5, respectively HC3v4 and HC3v5), and the CAMS radiation service. So far, these databases have been validated against measurements of several stations in Europe and North Africa only. As the quality of such databases depends on the geographical regions and the climates, this paper extends this validation campaign and proposes an extensive comparison on Brazil and global irradiation received on a horizontal surface. Eleven stations from the Brazilian Institute of Space Research (INPE) network offer 1 min observations, and thirty-one stations from the Instituto Nacional de Meteorologia (INMET) network offer hourly observations. The satellite-derived estimates have been compared to the corresponding observations on hourly, daily and monthly basis. The bias relative to the mean of the measurements for HC3v5 is mostly comprised between 1 and 3 %, and that for HC3v4 between 2 and 5 %. These are very satisfactory results and they demonstrate that HC3v5, and to a lesser extent HC3v4, may be used in studies of long-term changes in SSI in Brazil. The situation is not so good with CAMS radiation service for which the relative bias is mostly comprised between 5 and 10 %. For hourly irradiation, the relative RMSE ranges from 15 to 33 %. The correlation coefficient is very large for all stations and the three databases, with an average of 0.96. The three databases reproduce well the hour from hour changes in SSI. The errors show a tendency to increase with the viewing angle of the MSG satellite. They are greater in tropical areas where the relative humidity in the

  17. Estimated total emissions of trace gases from the Canberra wildfires of 2003: a new method using satellite measurements of aerosol optical depth and the MOZART chemical transport model

    OpenAIRE

    Paton-Walsh, C.; L. K. Emmons; S. R. Wilson

    2010-01-01

    In this paper we describe a new method for estimating trace gas emissions from large vegetation fires using measurements of aerosol optical depth from the MODIS instruments onboard NASA's Terra and Aqua satellites, combined with the atmospheric chemical transport model MOZART. The model allows for an estimate of double counting of enhanced levels of aerosol optical depth in consecutive satellite overpasses. Using this method we infer an estimated total emission of 10±3 Tg of c...

  18. Cardiovascular Health in Anxiety or Mood Problems Study (CHAMPS): study protocol for a randomized controlled trial

    OpenAIRE

    Tully, Phillip J; Turnbull, Deborah A; Horowitz, John D; Beltrame, John F.; Selkow, Terina; Baune, Bernhard T; Markwick, Elizabeth; Sauer-Zavala, Shannon; Baumeister, Harald; Cosh, Suzanne; Gary A Wittert

    2016-01-01

    Background Previous psychological and pharmacological interventions have primarily focused on depression disorders in populations with cardiovascular diseases (CVDs) and the efficacy of anxiety disorder interventions is only more recently being explored. Transdiagnostic interventions address common emotional processes and the full range of anxiety and depression disorders often observed in populations with CVDs. The aim of CHAMPS is to evaluate the feasibility of a unified protocol (UP) for t...

  19. A study of the geographic coverage properties of a satellite borne Doppler lidar wind velocity measuring system

    Science.gov (United States)

    Pate, T. H.

    1982-01-01

    Geographic coverage frequency and geographic shot density for a satellite borne Doppler lidar wind velocity measuring system are measured. The equations of motion of the light path on the ground were derived and a computer program devised to compute shot density and coverage frequency by latitude-longitude sections. The equations for the coverage boundaries were derived and a computer program developed to plot these boundaries, thus making it possible, after an application of a map coloring algorithm, to actually see the areas of multiple coverage. A theoretical cross-swath shot density function that gives close approximations in certain cases was also derived. This information should aid in the design of an efficient data-processing system for the Doppler lidar.

  20. Mobile System for the Measurement of Dose Rates with locations determined by means of satellite positioning technology

    International Nuclear Information System (INIS)

    Our laboratory has been developing and implementing a Real Time Radiological Warning Network around the Almaraz Nuclear Power Plant since 1990. It consists of six gamma dosimetry stations, two devices for the detection of radio-iodines and alpha, beta, and gamma emissions in air, a monitor for the continuous measurement of gamma radiation in water, and two basic meteorological stations. In this context, we have developed a mobile station endowed with a device for the measurement of dose rates which uses satellite positioning technology (GPS) so that it can be located remotely. The information gathered is sent back to our central laboratory in real/or deferred time through the digital mobile telephone network. A twofold utility is foreseen for this station: (a) action in the case of a radiological alert situation detected by our network, and (b) the performance of radiological-dosimetric studies of distant geographical zones. (Author)

  1. A comparison of wet and dry season ozone and CO over Brazil using in situ and satellite measurements

    International Nuclear Information System (INIS)

    Several field experiments have measured the regional effects of biomass burning. Two such experiments, designed to understand the chemistry of the Amazon rainforest during both the wet season and dry season, were conducted in the Amazon Basin. The first experiment, ABLE-2A (Amazon Boundary Layer Experiment), took place from July to August 1985, the early dry season, when biomass burning was just beginning. The second experiment, ABLE-2B, took place during the wet season, from April to May 1987, when little biomass burning was occurring. Comparing ABLE ozone data with tropospheric ozone concentrations derived from satellite data, using the method described by Fishman et al., shows a strong correlation between the direct measurements and the derived ozone concentrations, as well as a direct correlation of both to biomass burning. This comparison gives credence to the use of space-based platforms to monitor global chemistry and, in this case, the regional effects of biomass burning

  2. Ground-satellite measurement of Direct Normal Irradiance in South Portugal and its interaction with local atmospheric effects

    Science.gov (United States)

    Cavaco, Afonso; Canhoto, Paulo; Gonçalves da Silva, Hugo; Collares Pereira, Manuel

    2016-04-01

    Direct Normal Irradiance (DNI) is of crucial importance for the performance of Solar Thermal Plants (STP) and their use of solar concentrators. This has triggered a worldwide interest in the evaluation of this resource that started around 40 years ago (Collares-Pereira and Rabl, 1979). This is especially relevant in regions that have exceptional good solar resources, as it is the case of the South of Portugal (Cavaco et al, 2016). For that reason a network of seven meteorological stations measuring Direct (DNI), Global and Diffuse Solar Irradiance has been installed in this region, one year ago. This study presents the first results from that initial effort. First, this network will be used in correlating ground-based measurements with satellite data, in order to improve data calibration of remote acquisition. This will allow the extension of the results to other locations. The long-term validity of the present time-series will be secured by statistical correlation with previous local Global and Diffuse Solar Irradiance data. Second, new insights are expected to emerge on the complex relation between DNI and local meteorological variables (namely, relative humidity, optical thickness, and atmospheric turbidity), in order to improve the selection of possible locations for STP. These relations will be connected to the calibration of satellite data and to the statistical weighting of the various atmospheric elements in the TMY algorithm, thus giving a physical meaning to those different weights. Collares-Pereira, M. and Rabl, A. (1979). The average distribution of solar radiation correlations between Diffuse and hemispherical and between daily and hourly insolation values. Solar Energy 22(2), 155-164. Cavaco, A., Canhoto, P., Costa, M.J., and Collares-Pereira, M. (2016). DNI measurements in the South of Portugal: Long term results through direct comparison with global and diffuse radiation measurements and existing time series. Energy Procedia (in press).

  3. Characterisation of Central-African emissions based on MAX-DOAS measurements, satellite observations and model simulations over Bujumbura, Burundi.

    Science.gov (United States)

    Gielen, Clio; Hendrick, Francois; Pinardi, Gaia; De Smedt, Isabelle; Stavrakou, Trissevgeni; Yu, Huan; Fayt, Caroline; Hermans, Christian; Bauwens, Maité; Ndenzako, Eugene; Nzohabonayo, Pierre; Akimana, Rachel; Niyonzima, Sébastien; Müller, Jean-Francois; Van Roozendael, Michel

    2016-04-01

    Central Africa is known for its strong biogenic, pyrogenic, and to a lesser extent anthropogenic emissions. Satellite observations of species like nitrogen dioxide (NO2) and formaldehyde (HCHO), as well as inverse modelling results have shown that there are large uncertainties associated with the emissions in this region. There is thus a need for additional measurements, especially from the ground, in order to better characterise the biomass-burning and biogenic products emitted in this area. We present MAX-DOAS measurements of NO2, HCHO, and aerosols performed in Central Africa, in the city of Bujumbura, Burundi (3°S, 29°E, 850m). A MAX-DOAS instrument has been operating at this location by BIRA-IASB since late 2013. Aerosol-extinction and trace-gases vertical profiles are retrieved by applying the optimal-estimation-based profiling tool bePRO to the measured O4, NO2 and HCHO slant-column densities. The MAX-DOAS vertical columns and profiles are used for investigating the diurnal and seasonal cycles of NO2, HCHO, and aerosols. Regarding the aerosols, the retrieved AODs are compared to co-located AERONET sun photometer measurements for verification purpose, while in the case of NO2 and HCHO, the MAX-DOAS vertical columns and profiles are used for validating GOME-2 and OMI satellite observations. To characterise the biomass-burning and biogenic emissions in the Bujumbura region, the trace gases and aerosol MAX-DOAS retrievals are used in combination to MODIS fire counts/radiative-power and GOME-2/OMI NO2 and HCHO satellite data, as well as simulations from the NOAA backward trajectory model HYSPLIT. First results show that HCHO seasonal variation around local noon is driven by the alternation of rain and dry periods, the latter being associated with intense biomass-burning agricultural activities and forest fires in the south/south-east and transport from this region to Bujumbura. In contrast, NO2 is seen to depend mainly on local emissions close to the city, due

  4. First evidence for correlations between electron fluxes measured by NOAA-POES satellites and large seismic events

    Energy Technology Data Exchange (ETDEWEB)

    Battiston, Roberto [Dipartimento di Fisica and INFN-Trento Center for Fundamental Physics and Applications (TIPFA), Povo (Italy); Vitale, Vincenzo [Istituto Nazionale di Fisica Nucleare, sez. Perugia and ASI Science Data Center, Frascati (Italy)

    2013-10-15

    We present the result for the search of correlations between the precipitation of low energy electrons (E>0.3MeV) trapped within the Van Allen Belts and earthquakes with magnitude above 5 Richter scale. We used the electron data measured by the NOAA POES 15,16,17 and 18 satellites collected during a period of 13 years, corresponding to about 18 thousands M>5 earthquakes registered in the NEIC catalog of the U.S. Geological Survey. We defined Particle Burst (PB) the fluctuations of electrons counting rate having a probability <1% to be a background fluctuation. Within a time window of ±36 hours, we observe a clear correlation peak at −1.25±0.25 hours. This result is obtained using data driven algorithms independent from specific modelling of the lithosphere-ionosphere coupling and adding the data collected by each POES satellite. The significance of the observed correlation peak is 5.7 s.d. corresponding to a probability of 1.210{sup −6} of being a statistical fluctuation. The observed correlation involves about 1.410{sup −3} of the earthquakes in that period of time. It provides the first statistically convincing evidence for the existence of a detectable coupling mechanism between the lithosphere and the magnetosphere having well defined time characteristics.

  5. The PAMELA experiment on satellite and its capability in cosmic rays measurements

    CERN Document Server

    Adriani, O; Barbarino, G C; Barbier, L M; Bartalucci, S; Bazilevskaja, G; Bellotti, R; Bertazzoni, S; Bidoli, V; Boezio, M; Bogomolov, E A; Bonechi, L; Bonvicini, V; Boscherini, M; Bravar, U; Cafagna, F; Campana, D; Carlson, Per J; Casolino, M; Castellano, M; Castellini, G; Christian, E R; Ciacio, F; Circella, M; D'Alessandro, R; De Marzo, C N; De Pascale, M P; Finetti, N; Furano, G; Gabbanini, A; Galper, A M; Giglietto, N; Grandi, M; Grigorieva, A; Guarino, F; Hof, M; Koldashov, S V; Korotkov, M G; Krizmanic, J F; Krutkov, S; Lund, J; Marangelli, B; Marino, L; Menn, W; Mikhailov, V V; Mirizzi, N; Mitchell, J W; Mocchiutti, E; Moiseev, A A; Morselli, A; Mukhametshin, R; Ormes, J F; Osteria, G; Ozerov, J V; Papini, P; Pearce, M; Perego, A; Piccardi, S; Picozza, P; Ricci, M; Salsano, A; Schiavon, Paolo; Scian, G; Simon, M; Sparvoli, R; Spataro, B; Spillantini, P; Spinelli, P; Stephens, S A; Stochaj, S J; Stozhkov, Yu I; Straulino, S; Streitmatter, R E; Taccetti, F; Tesi, M; Vacchi, A; Vannuccini, E; Vasiljev, G; Vignoli, V; Voronov, S A; Yurkin, Y; Zampa, G; Zampa, N

    2002-01-01

    The PAMELA equipment will be assembled in 2001 and installed on board the Russian satellite Resurs. PAMELA is conceived mainly to study the antiproton and positron fluxes in cosmic rays up to high energy (190 GeV for p-bar and 270 GeV for e sup +) and to search antinuclei, up to 30 GeV/n, with a sensitivity of 10 sup - sup 7 in the He-bar/He ratio. The PAMELA telescope consists of: a magnetic spectrometer made up of a permanent magnet system equipped with double sided microstrip silicon detectors; a transition radiation detector made up of active layers of proportional straw tubes interleaved with carbon fibre radiators; and a silicon-tungsten imaging calorimeter made up of layers of tungsten absorbers and silicon detector planes. A time-of-flight system and anti-coincidence counters complete the PAMELA equipment. In the past years, tests have been done on each subdetector of PAMELA; the main results are presented and their implications on the anti-particles identification capability in cosmic rays are discus...

  6. Satellites measure recent rates of groundwater depletion in California's Central Valley

    Science.gov (United States)

    Famiglietti, J. S.; Lo, M.; Ho, S. L.; Bethune, J.; Anderson, K. J.; Syed, T. H.; Swenson, S. C.; de Linage, C. R.; Rodell, M.

    2011-02-01

    In highly-productive agricultural areas such as California's Central Valley, where groundwater often supplies the bulk of the water required for irrigation, quantifying rates of groundwater depletion remains a challenge owing to a lack of monitoring infrastructure and the absence of water use reporting requirements. Here we use 78 months (October, 2003-March, 2010) of data from the Gravity Recovery and Climate Experiment satellite mission to estimate water storage changes in California's Sacramento and San Joaquin River Basins. We find that the basins are losing water at a rate of 31.0 ± 2.7 mm yr-1 equivalent water height, equal to a volume of 30.9 km3 for the study period, or nearly the capacity of Lake Mead, the largest reservoir in the United States. We use additional observations and hydrological model information to determine that the majority of these losses are due to groundwater depletion in the Central Valley. Our results show that the Central Valley lost 20.4 ± 3.9 mm yr-1 of groundwater during the 78-month period, or 20.3 km3 in volume. Continued groundwater depletion at this rate may well be unsustainable, with potentially dire consequences for the economic and food security of the United States.

  7. Annual Detection of Forest Cover Loss Using Time Series Satellite Measurements of Percent Tree Cover

    Directory of Open Access Journals (Sweden)

    Xiao-Peng Song

    2014-09-01

    Full Text Available We introduce and test a new method to detect annual forest cover loss from time series estimates of percent tree cover. Our approach is founded on two realistic assumptions: (1 land cover disturbances are rare events over large geographic areas that occur within a short time frame; and (2 spatially discrete land cover disturbances are continuous processes over time. Applying statistically rigorous algorithms, we first detect disturbance pixels as outliers of an underlying chi-square distribution. Then, we fit nonlinear, logistic curves for each identified change pixel to simultaneously characterize the magnitude and timing of the disturbance. Our method is applied using the yearly Vegetation Continuous Fields (VCF tree cover product from Moderate Resolution Imaging Spectroradiometer (MODIS, and the resulting disturbance-year estimates are evaluated using a large sample of Landsat-based forest disturbance data. Temporal accuracy is ~65% at 250-m, annual resolution and increases to >85% when temporal resolution is relaxed to ±1 yr. The r2 of MODIS VCF-based disturbance rates against Landsat ranges from 0.7 to 0.9 at 5-km spatial resolution. The general approach developed in this study can be potentially applied at a global scale and to other land cover types characterized as continuous variables from satellite data.

  8. Determination of the Earth's lithospheric magnetic field with satellite data

    Science.gov (United States)

    Kotsiaros, Stavros; Olsen, Nils; Finlay, Christopher

    2016-07-01

    Satellites such as Magsat, Ørsted, CHAMP and Swarm provide the most effective means of determining on a global scale the Earth's lithospheric magnetic field. In particular, the Swarm three-satellite constellation mission aims at capturing the smallest-scale features of the lithospheric field that have ever been captured from space. To achieve that, explicit advantage of the constellation aspect of Swarm has to be taken by using gradient estimates. We derive lithospheric field models using more than one year of magnetic gradient data, which are approximated by first differences of field vector data between the two lower Swarm satellites and along each satellite orbit, respectively. We find that gradient data are less sensitive to large-scale external field fluctuations. Moreover, gradient data appear to be a very efficient way of increasing the resolution of lithospheric field models and thus providing an initial validation of the gradient concept underlying the Swarm mission.

  9. Satellite chlorophyll fluorescence measurements reveal large-scale decoupling of photosynthesis and greenness dynamics in boreal evergreen forests.

    Science.gov (United States)

    Walther, Sophia; Voigt, Maximilian; Thum, Tea; Gonsamo, Alemu; Zhang, Yongguang; Köhler, Philipp; Jung, Martin; Varlagin, Andrej; Guanter, Luis

    2016-09-01

    Mid-to-high latitude forests play an important role in the terrestrial carbon cycle, but the representation of photosynthesis in boreal forests by current modelling and observational methods is still challenging. In particular, the applicability of existing satellite-based proxies of greenness to indicate photosynthetic activity is hindered by small annual changes in green biomass of the often evergreen tree population and by the confounding effects of background materials such as snow. As an alternative, satellite measurements of sun-induced chlorophyll fluorescence (SIF) can be used as a direct proxy of photosynthetic activity. In this study, the start and end of the photosynthetically active season of the main boreal forests are analysed using spaceborne SIF measurements retrieved from the GOME-2 instrument and compared to that of green biomass, proxied by vegetation indices including the Enhanced Vegetation Index (EVI) derived from MODIS data. We find that photosynthesis and greenness show a similar seasonality in deciduous forests. In high-latitude evergreen needleleaf forests, however, the length of the photosynthetically active period indicated by SIF is up to 6 weeks longer than the green biomass changing period proxied by EVI, with SIF showing a start-of-season of approximately 1 month earlier than EVI. On average, the photosynthetic spring recovery as signalled by SIF occurs as soon as air temperatures exceed the freezing point (2-3 °C) and when the snow on the ground has not yet completely melted. These findings are supported by model data of gross primary production and a number of other studies which evaluated in situ observations of CO2 fluxes, meteorology and the physiological state of the needles. Our results demonstrate the sensitivity of space-based SIF measurements to light-use efficiency of boreal forests and their potential for an unbiased detection of photosynthetic activity even under the challenging conditions interposed by evergreen

  10. Simultaneous measurements from the Millstone Hill radar and the Active satellite during the SAID/SAR arc event of the March 1990 CEDAR storm

    Directory of Open Access Journals (Sweden)

    M. Förster

    Full Text Available During a nearby passage of the Active satellite above the Millstone Hill radar on 21 March 1990 at local sunset, the satellite and the radar performed simultaneous measurements of upper ionospheric parameters in nearly the same spatial volume. For this purpose the radar carried out a special azimuth-elevation scan to track the satellite. Direct comparisons of radar data and in situ satellite measurements have been carried out quite rarely. In this case, the coincidence of co-ordinated measurements and active ionospheric-magnetospheric processes during an extended storm recovery phase presents a unique occasion resulting in a very valuable data set. The measurements show generally good agreement both during quiet prestorm and storm conditions and the combination of radar and satellite observations gives a more comprehensive picture of the physical processes involved. We find a close relationship between the rapid westward ion drift peak at subauroral latitudes (SAID event and the occurrence of a stable auroral red (SAR arc observed after sunset by an all-sky imager and reported in an earlier study of this event. The SAID electric field is caused by the penetration of energetic ions with energies between about 1 keV and 100 keV into the outer plasmasphere to a latitude equatorward of the extent of the plasmasheet electrons. Charge separation results in the observed polarisation field and the SAID. Unusually high molecular ion densities measured by the satellite at altitudes of 700-870 km at subauroral and auroral latitudes point on strong upward-directed ion acceleration processes and an intense neutral gas upwelling. These structures are collocated with a narrow trough in electron density and an electron temperature peak as observed simultaneously by the radar and the satellite probes.

    Key words. Ionosphere (ionosphere-magnetosphere interactions; plasma temperature and density; Magnetospheric physics (plasmasphere.

  11. Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements

    Directory of Open Access Journals (Sweden)

    C. A. M. Brenninkmeijer

    2011-02-01

    Full Text Available We infer CO2 surface fluxes using satellite observations of mid-tropospheric CO2 from the Tropospheric Emission Spectrometer (TES and measurements of CO2 from surface flasks in a time-independent inversion analysis based on the GEOS-Chem model. Using TES CO2 observations over oceans, spanning 40° S–40° N, we find that the horizontal and vertical coverage of the TES and flask data are complementary. This complementarity is demonstrated by combining the datasets in a joint inversion, which provides better constraints than from either dataset alone, when a posteriori CO2 distributions are evaluated against independent ship and aircraft CO2 data. In particular, the joint inversion offers improved constraints in the tropics where surface measurements are sparse, such as the tropical forests of South America, which the joint inversion suggests was a weak sink of −0.17 ± 0.20 Pg C in 2006. Aggregating the annual surface-to-atmosphere fluxes from the joint inversion yields −1.13 ± 0.21 Pg C for the global ocean, −2.77 ± 0.20 Pg C for the global land biosphere and −3.90 ± 0.29 Pg C for the total global natural flux (defined as the sum of all biospheric, oceanic, and biomass burning contributions but excluding CO2 emissions from fossil fuel combustion. These global ocean, global land and total global fluxes are shown to be in the range of other inversion results for 2006. To achieve these results, a latitude dependent bias in TES CO2 in the Southern Hemisphere was assessed and corrected using aircraft flask data, and we demonstrate that our results have low sensitivity to variations in the bias correction approach. Overall, this analysis suggests that future carbon data assimilation systems can benefit by integrating in situ and satellite observations of CO2 and that the vertical information provided by satellite observations of mid-tropospheric CO2 combined with measurements of surface CO2, provides an important additional constraint for

  12. The Zurich Environmental Study (ZENS) of Galaxies in Groups along the Cosmic Web. II. Galaxy Structural Measurements and the Concentration of Morphologically Classified Satellites in Diverse Environments

    Science.gov (United States)

    Cibinel, A.; Carollo, C. M.; Lilly, S. J.; Miniati, F.; Silverman, J. D.; van Gorkom, J. H.; Cameron, E.; Finoguenov, A.; Norberg, P.; Peng, Y.; Pipino, A.; Rudick, C. S.

    2013-10-01

    We present structural measurements for the galaxies in the 0.05 = 1010 M ⊙, the concentration of disk satellites increases with increasing stellar mass separately within each morphological bin of B/T. The known increase in concentration with stellar mass for disk satellites is thus due, at least in part, to an increase in galaxy central stellar density at constant B/T. The correlation between concentration and galaxy stellar mass becomes progressively steeper for later morphological types. The concentration of disk satellites shows a barely significant dependence on δLSS or R/R 200. The strongest environmental effect is found with group mass for >1010 M ⊙ disk-dominated satellites, which are ~10% more concentrated in high mass groups than in lower mass groups. Based on observations collected at the European Southern Observatory, La Silla Chile, Program ID 177.A-0680.

  13. Comparison of measured and satellite-derived spectral diffuse attenuation coefficients for the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Talaulikar, M.; Desa, E.; Matondkar, S.G.P.; Mascarenhas, A.

    -data-driven and one is semi-analytical are presented. The measurements were carried out in all water types and the mean values of the measured spectral Kd(Lambda) are 0.105, 0.092, 0.077, 0.082, 0.110 and 0.490 m sup(-1) for wavelength Lambda at 412, 443, 490, 510...

  14. DETERMINATION OF EFFECTIVE ELASTIC THICKNESS OF THE COLOMBIAN ANDES USING SATELLITE-DERIVED GRAVITY DATA

    Directory of Open Access Journals (Sweden)

    Casallas1 Iván

    2010-06-01

    Full Text Available

    Gravity anomaly values derived from Global Geopotential Models (calculated from the CHAMP and GRACE satellite missions, are compared with free air ground gravity data to find the best representation of surface data. Using these values and topographical heights extracted from digital topography models, we applied the isostatic response function (admittance to a collection of profiles, to find an average of elastic thickness for the Colombian Andes.

  15. 单星对卫星仅测角被动跟踪的三维可观测性研究%Observability of Satellite-to-Satellite Three-Dimensional Passive Tracking Using Bearings-Only Measurements

    Institute of Scientific and Technical Information of China (English)

    李强; 时荔蕙; 王洪先; 郭福成

    2009-01-01

    单个卫星观测器对卫星的仅测角被动跟踪技术在空间目标监视中具有重要价值.研究了单个卫星观测器对卫星仅测角被动跟踪中的重要理论问题--系统可观测性问题.在三维情况下基于角度测量信息建立了目标加速度由其位置、速度确定的运动模型,推导了该模型的系统可观测充要条件,最后严格证明了三维情况下单星对卫星的仅测角被动跟踪系统满足上述可观测充要条件.%Single satellite to satellite passive tracking using bearings-only measurements have great significance in Space Surveillance System. This paper addresses the state observability problem, which is an important theory issue for sat-ellite-to-satellite passive tracking. The kinetic models, in which the target accelerations are decided by their position and velocity vectors, are developed from bearings-only measurements in a three-dimensional case. The necessary and sufficient conditions for system observability in the corresponding case are deduced. Finally, the system observability of single satel-lite to satellite passive tracking from bearings-only measurements can be fulfilled is then proven in detail.

  16. The emerging understanding of magnetic reconnection through laboratory experiments, theory and modeling and in situ satellite measurements

    Science.gov (United States)

    Drake, James F.

    2015-08-01

    Magnetic reconnection is the driver of explosive energy release in laboratory, space and astrophysical plasma systems. It plays a centralrole in such diverse phenomena as solar and stellar flares, flares in pulsar nebulae, gamma ray bursts and possibly even in the productionof energetic particles in supernova shocks. The close interaction of scientists doing laboratory experiments, in situ satellite measurements and theory and modeling has led to remarkable progress on key issues such as the mechanisms for fast energy release and heating and particle acceleration. There are, however, many open issues. The talk will address the emerging understanding of reconnection as well as areas where significant uncertainty remains. The role of new laboratory experiments such as FLARE at PPPL and the recently launched four-spacecraft MMS mission in resolving open issues will be discussed.

  17. Satellite-based measurements of surface deformation reveal fluid flow associated with the geological storage of carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Vasco, D.W.; Rucci, A.; Ferretti, A.; Novali, F.; Bissell, R.; Ringrose, P.; Mathieson, A.; Wright, I.

    2009-10-15

    Interferometric Synthetic Aperture Radar (InSAR), gathered over the In Salah CO{sub 2} storage project in Algeria, provides an early indication that satellite-based geodetic methods can be effective in monitoring the geological storage of carbon dioxide. An injected volume of 3 million tons of carbon dioxide, from one of the first large-scale carbon sequestration efforts, produces a measurable surface displacement of approximately 5 mm/year. Using geophysical inverse techniques we are able to infer flow within the reservoir layer and within a seismically detected fracture/ fault zone intersecting the reservoir. We find that, if we use the best available elastic Earth model, the fluid flow need only occur in the vicinity of the reservoir layer. However, flow associated with the injection of the carbon dioxide does appear to extend several kilometers laterally within the reservoir, following the fracture/fault zone.

  18. First evidence for correlations between electron fluxes measured by NOAA-POES satellites and large seismic events

    International Nuclear Information System (INIS)

    We present the result for the search of correlations between the precipitation of low energy electrons (E>0.3MeV) trapped within the Van Allen Belts and earthquakes with magnitude above 5 Richter scale. We used the electron data measured by the NOAA POES 15,16,17 and 18 satellites collected during a period of 13 years, corresponding to about 18 thousands M>5 earthquakes registered in the NEIC catalog of the U.S. Geological Survey. We defined Particle Burst (PB) the fluctuations of electrons counting rate having a probability −6 of being a statistical fluctuation. The observed correlation involves about 1.410−3 of the earthquakes in that period of time. It provides the first statistically convincing evidence for the existence of a detectable coupling mechanism between the lithosphere and the magnetosphere having well defined time characteristics

  19. Stress level in wild harbour porpoises (Phocoena phocoena) during satellite tagging measured by respiration, heart rate and cortisol

    DEFF Research Database (Denmark)

    Eskesen, Ida Grønborg; Teilmann, J.; Geertsen, B. M.;

    2009-01-01

    During satellite tagging of harbour porpoises (Phocoena phocoena), heart rate, respiration rate and cortisol value were measured to evaluate stress effects during handling and tagging. Respiration rates were obtained using video recordings, heart rates were recorded and serum cortisol levels were...... analysed from blood samples. Differences in heart rates, respiration rates and cortisol levels before and during the tagging events were investigated. An overall significant decrease Of 31.5% in respiration rate was found during the tagging event period, while mature porpoises respired significantly more...... often titan immature individuals. Though significant differences in heart rates were found for some individuals, no general significant change for all animals was detected. We found no correlation between cortisol concentration and either heart rate or respiration rate, nor did we find any relationships...

  20. Electron density on an altitude of 1000 km in calm and disturbed conditions measured by the ''Kosmos-381'' satellite

    International Nuclear Information System (INIS)

    The results are presented of the treatment of data of measurements of the electron concentration, Nsub(e), at an altitude of 1000 km obtained with the aid of the Cosmos-381 satellite under quiet (Σ Ksub(p) 15) conditions, and also during the magnetic storm of 14.12.1970. Under quiet conditions an equatorial maximum (Nsub(e) approximately 4 x 104 electrons/cm3) was observed in the latitude d tributionis At night, ionization at the altitude of 1000 km is independent of the latitude, Nsub(e) approximately 5 x 103 electrons/cm3. During the storm with a sudden beginning on 14.12.1970 the latitude distribution had a wavelike shape. The electron concentration in the main phase of the storm perceptibly increased at all latitudes, the restoration phase was characterized by a reduction in Nsub(e), which was more pronounced for the southern hemisphere, and less for the Northern one

  1. Nouvelles approches en theorie du champ moyen dynamique: le cas du pouvoir thermoelectrique et celui de l'effet orbital d'un champ magnetique

    Science.gov (United States)

    Arsenault, Louis-Francois

    Les applications reliees a la generation d'energie motivent la recherche de materiaux ayant un fort pouvoir thermoelectrique (S). De plus, S nous renseigne sur certaines proprietes fondamentales des materiaux, comme, par exemple, la transition entre l'etat coherent et incoherent des quasi-particules lorsque la temperature augmente. Empiriquement, la presence de fortes interactions electron-electron peut mener a un pouvoir thermoelectrique geant. Nous avons donc etudie le modele le plus simple qui tient compte de ces fortes interactions, le modele de Hubbard. La theorie du champ moyen dynamique (DMFT) est tout indiquee dans ce cas. Nous nous sommes concentres sur un systeme tridimensionnel (3d) cubique a face centree (fcc), et ce, pour plusieurs raisons. A) Ce type de cristal est tres commun dans la nature. B) La DMFT donne de tres bons resultats en 3d et donc ce choix sert aussi de preuve de principe de la methode. C) Finalement, a cause de la frustration electronique intrinseque au fcc, celui-ci ne presente pas de symetrie particule-trou, ce qui est tres favorable a l'apparition d'une grande valeur de S. Ce travail demontre que lorsque le materiau est un isolant a demi-remplissage a cause des fortes interactions (isolant de Mott), il est possible d'obtenir de grands pouvoirs thermoelectriques en le dopant legerement. C'est un resultat pratique important. Du point de vue methodologique, nous avons montre comment la limite de frequence infinie de S et l'approche dite de Kelvin, qui considere la limite de frequence nulle avant la limite thermodynamique pour S, donnent des estimations fiables de la vraie limite continue (DC) dans les domaines de temperature appropriee. Ces deux approches facilitent grandement les calculs en court-circuit ant la necessite de recourir a de problematiques prolongements analytiques. Nous avons trouve que la methode de calcul a frequence infinie fonctionne bien lorsque les echelles d'energie sont relativement faibles. En d'autres termes

  2. Hydrological mass changes inferred from high-low satellite-to-satellite tracking data

    Science.gov (United States)

    van Dam, Tonie; Tourian, Mohammad; Wiegelt, Mathias; Sneeuw, Nico; Jaggi, Adrian; Prange, Lars

    2013-04-01

    The technique of deriving time variable gravity (TVG) field observations from high-low satellite-to-satellite tracking (hl-SST) is beginning to establish itself as a valuable and supplementary source for the determination and description of long wavelength geophysical phenomena. Recent developments in data processing techniques have pushed the limits of the accuracy of these types of observations and now allows for realistic determinations of long-term trends and annual amplitudes of hydrological signals. We use CHAMP data and a dedicated signal processing to derive annual and inter-annual variations in the largest catchments of the Earth system, e.g. Amazon, Ob and Lena. Results are validated by computing the correlation of aggregated water storage changes from CHAMP (and GRACE) with the hydro-meteorological storage changes. High noise levels demand a stronger filtering, e.g. larger filtering radius (1000-1400km), than usually applied in case of GRACE. We therefore also investigate the effect of filtering on the consistency with the hydrological mass changes and estimate the signal to noise ratio and the spatial and temporal dependency of the noise. We will show that hl-SST observations are a viable source of information for TVG which can potentially serve as a reliable substitute in the likely event that GRACE fails before GRACE Follow On is launched.

  3. Multi-annual changes of NOx emissions in megacity regions: nonlinear trend analysis of satellite measurement based estimates

    Directory of Open Access Journals (Sweden)

    J. P. Burrows

    2010-09-01

    Full Text Available Hazardous impact of air pollutant emissions from megacities on atmospheric composition on regional and global scales is currently an important issue in atmospheric research. However, the quantification of emissions and related effects is frequently a difficult task, especially in the case of developing countries, due to the lack of reliable data and information. This study examines possibilities to retrieve multi-annual NOx emissions changes in megacity regions from satellite measurements of nitrogen dioxide and to quantify them in terms of linear and nonlinear trends. By combining the retrievals of the GOME and SCIAMACHY satellite instrument data with simulations performed by the CHIMERE chemistry transport model, we obtain the time series of NOx emission estimates for the 12 largest urban agglomerations in Europe and the Middle East in the period from 1996 to 2008. We employ then a novel method allowing estimation of a nonlinear trend in a noisy time series of an observed variable. The method is based on the probabilistic approach and the use of artificial neural networks; it does not involve any quantitative a priori assumptions. As a result, statistically significant nonlinearities in the estimated NOx emission trends are detected in 5 megacities (Bagdad, Madrid, Milan, Moscow and Paris. Statistically significant upward linear trends are detected in Istanbul and Tehran, while downward linear trends are revealed in Berlin, London and the Ruhr agglomeration. The presence of nonlinearities in NOx emission changes in Milan, Paris and Madrid is confirmed by comparison of simulated NOx concentrations with independent air quality monitoring data. A good quantitative agreement between the linear trends in the simulated and measured near surface NOx concentrations is found in London.

  4. Reconstructing ozone chemistry from Asian wild fires using models, satellite and aircraft measurements during the ARCTAS campaign

    Directory of Open Access Journals (Sweden)

    R. Dupont

    2010-11-01

    Full Text Available We use ozone (O3 and carbon monoxide (CO satellite measurements from the Tropospheric Emission Spectrometer (TES, simulations from the Real-time Air Quality Modeling System (RAQMS and aircraft data from the NASA DC8 aircraft to characterize the chemical and dynamical evolution of Asian wildfire plumes during the spring ARCTAS campaign 2008. On the 19 April, NASA DC8 O3 and aerosol Differential Absorption Lidar (DIAL observed two biomass burning plumes originating from North-Western Asia (Kazakhstan and South-Eastern Asia (Thailand that advected eastward over the Pacific reaching North America in 10 to 12 days. Using both TES observations and RAQMS chemical analyses, we track the wildfire plumes from their source to the ARCTAS DC8 platform. Comparison between satellite O3 and CO measurements and model results show consistency when the TES averaging kernel and constraint vector are applied to the model. However, RAQMS CO simulations suggest that TES observations do not capture the full range of CO variability in the plume due to low sensitivity. In both plumes, exchanges between the stratosphere and the troposphere tend to be a major factor influencing O3 concentrations. However, fire emissions of ozone precursors increase photochemical ozone production, particularly in the Thailand wildfire plume. Analysis shows that the Kazakhstan plume is responsible for increases of O3 and CO mixing ratios up to 6.4 ppbv and 38 ppbv in the lower troposphere, and the Thailand plume is responsible for increases of O3 and CO mixing ratios up to 11 ppbv and 71 ppbv in the upper troposphere.

  5. Simulations of the Holuhraun eruption 2014 with WRF-Chem and evaluation with satellite and ground based SO2 measurements

    Science.gov (United States)

    Hirtl, Marcus; Arnold-Arias, Delia; Flandorfer, Claudia; Maurer, Christian; Mantovani, Simone; Natali, Stefano

    2016-04-01

    Volcanic eruptions, with gas or/and particle emissions, directly influence our environment, with special significance when they either occur near inhabited regions or are transported towards them. In addition to the well-known affectation of air traffic, with large economic impacts, the ground touching plumes can lead directly to an influence of soil, water and even to a decrease of air quality. The eruption of Holuhraun in August 2014 in central Iceland is the country's largest lava and gas eruption since the Lakagígar eruption in 1783. Nevertheless, very little volcanic ash was produced. The main atmospheric threat from this event was the SO2 pollution that frequently violated the Icelandic National Air Quality Standards in many population centers. However, the SO2 affectation was not limited to Iceland but extended to mainland Europe. The on-line coupled model WRF-Chem is used to simulate the dispersion of SO2 for this event that affected the central European regions. The volcanic emissions are considered in addition to the anthropogenic and biogenic ground sources at European scale. A modified version of WRF-Chem version 4.1 is used in order to use time depending injection heights and mass fluxes which were obtained from in situ observations. WRF-Chem uses complex gas- (RADM2) and aerosol- (MADE-SORGAM) chemistry and is operated on a European domain (12 km resolution), and a nested grid covering the Alpine region (4 km resolution). The study is showing the evaluation of the model simulations with satellite and ground based measurement data of SO2. The analysis is conducted on a data management platform, which is currently developed in the frame of the ESA-funded project TAMP "Technology and Atmospheric Mission Platform": it provides comprehensive functionalities to visualize and numerically compare data from different sources (model, satellite and ground-measurements).

  6. Assimilation of IASI satellite CO fields into a global chemistry transport model for validation against aircraft measurements

    Directory of Open Access Journals (Sweden)

    A. Klonecki

    2011-12-01

    Full Text Available A modelling system for assimilation of CO total columns measured by the IASI/MetOp was developed. The system, based on a sub-optimal Kalman filter coupled with the LMDz-INCA chemistry transport model, allows both assimilating long periods of historical data and making rapid forecasts of the CO concentrations in the middle troposphere based on latest available measurements. Tests of the forecast system were conducted during the international POLARCAT campaigns. A specific treatment that takes into account the representativeness of observations at the scale of the model grid is applied to the IASI CO columns and associated errors before their assimilation in the model. This paper presents the results of assimilation of eight months of historical satellite data measured in 2008. Comparisons of the assimilated CO profiles with independent in situ CO measurements from the MOZAIC program and the POLARCAT aircraft campaigns indicate that the assimilation leads to a considerable improvement of the model simulations in the middle troposphere as compared with a control run with no assimilation. Model biases in the simulation of background values are reduced and improvement in the simulation of very high concentrations is observed. The improvement is due to the transport by the model of the information present in the IASI CO retrievals. The consistency of the improvement contributes to the validation of the IASI CO data.

  7. Multi-Element Abundance Measurements from Medium-Resolution Spectra. II. Catalog of Stars in Milky Way Dwarf Satellite Galaxies

    CERN Document Server

    Kirby, Evan N; Simon, Joshua D; Geha, Marla C; Rockosi, Constance M; Sneden, Christopher; Cohen, Judith G; Sohn, Sangmo Tony; Majewski, Steven R; Siegel, Michael

    2010-01-01

    We present a catalog of Fe, Mg, Si, Ca, and Ti abundances for 2961 red giant stars that are likely members of eight dwarf satellite galaxies of the Milky Way (MW): Sculptor, Fornax, Leo I, Sextans, Leo II, Canes Venatici I, Ursa Minor, and Draco. For the purposes of validating our measurements, we also observed 445 red giants in MW globular clusters and 21 field red giants in the MW halo. The measurements are based on Keck/DEIMOS medium-resolution spectroscopy combined with spectral synthesis. We estimate uncertainties in [Fe/H] by quantifying the dispersion of [Fe/H] measurements in a sample of stars in monometallic globular clusters. We estimate uncertainties in Mg, Si, Ca, and Ti abundances by comparing our medium-resolution spectroscopic measurements to high-resolution spectroscopic abundances of the same stars. For this purpose, our DEIMOS sample included 132 red giants with published high-resolution spectroscopy in globular clusters, the MW halo field, and dwarf galaxies. The standard deviations of the ...

  8. Ship-based Aerosol Optical Depth Measurements in the Atlantic Ocean, Comparison with Satellite Retrievals and GOCART Model

    Science.gov (United States)

    Smirnov, A.; Holben, B. N.; Sakerin, S.; Kabanov, D.; Slutsker, I.; Remer, L. A.; Kahn, R.; Ignatov, A.; Chin, M.; Diehl, T. L.; Mishchenko, M.; Liu, L.; Kucsera, T. L.; Giles, D.; Eck, T. F.; Torres, O.; Kopelevich, O.

    2005-12-01

    Aerosol optical depth measurements were made in October -December 2004 aboard of R/V Akademik Sergey Vavilov. The cruise area included the Atlantic transect from North Sea to Cape Town and then a crossing in the South Atlantic to Ushuaia, Argentina. The hand-held Microtops II sunphotometer was used to acquire 314 series of measurements spanning 38 days. The sunphotometer was pre-calibrated at the NASA Goddard Space Flight Center against a master sun/sky radiometer instrument of the Aerosol Robotic Network (AERONET). The direct sun measurements were acquired in five spectral channels: 340, 440, 675, 870 and 940 nm. To retrieve aerosol optical depths we applied AERONET processing algorithm (Version 2) to the raw data. Aerosol optical depth values were close to background oceanic conditions (0.04-0.08) in the open oceanic areas not influenced by continental sources. Spectral dependence can be described as almost neutral (Angstrom parameter was less than 0.6), especially in the Southern Atlantic. A notable latitudinal variability of optical depth was observed between 15N and 21S, which was associated with the aerosol transport from Africa. Correlations between optical depth and meteorological parameters were considered and comparison between ship-based measurements and AERONET sites along the cruise track was made. Aerosol optical depths were compared to the global transport model (GOCART) simulations and satellite retrievals from MODIS, MISR, and AVHRR.

  9. Determination of stability and instability of oceanic processes on a global scale using satellite measurements

    Science.gov (United States)

    Shevyrnogov, Anatoly; Vysotskaya, Galina

    According to different estimates from the mid-nineteenth century the average surface temper-ature has increased by 0.3-0.6o C. In different parts of the Earth this warming is manifested in varying degrees, but almost anywhere the temperature increase by itself did not have catas-trophic effects on ecosystems and human activity. Extreme climatic events have a much greater influence on the environment. The Global Ocean is the largest part of the biosphere of the Earth, and, thus, investigation of chlorophyll concentration dynamics is extremely important for studying global carbon cycles. In this paper we propose a generalized approach to the study of dynamics of the "ocean-atmosphere" system using the methods of statistical evaluation of long-term series of satellite (AVHRR, SeaWiFS and MODIS) and ground-true data, based on the theory of stochastic dynamic systems. To study the dynamics of the ocean for the period from 1985 through 2008 we used data on the temperature of the surface layer of the ocean and chlorophyll concentration because it is a good indicator of how atmospheric and oceanic processes. As it is known a priori that extremely high and extremely low chlorophyll concen-trations or sea surface temperature are associated with different physical processes, when mean or total biomass in the ocean is calculated, the processes induced by different physical reasons superpose. Thus, no correlation can be reached between the calculated total dynamics and some physical process. In this paper we applied the method of statistical distribution analysis of data to every pixel. With this approach, extreme values are investigated in greater detail. We divided the range of values for every pixel into 5 parts; seasonal variations were taken into account. The spatiotemporal distribution of the dynamics of extreme and average values was investigated. This approach made possible discovering the commonality of processes in the different oceans and defining a problem of

  10. Spatio-temporal variability of satellite derived aerosol optical thickness and ground measurements over East China

    Science.gov (United States)

    Meng, Fei; Shi, Tongguang

    2016-04-01

    Two-year records of Visible Infrared Imaging Radiometer Suite (VIIRS) Intermediate Product (IP) data on the aerosol optical thickness (AOT) at 550 nm were evaluated by comparing them with sun-sky radiometer measurements from the Chinese sun hazemeter network (CSHNET) and the aerosol robotic network (AERONET). The monthly and seasonal variations in the aerosol optical properties over eastern China were then investigated using collocated VIIRS IP data and CSHNET and AERONET measurements.Results show that the performances of the current VIIRS IP AOT retrievals at the provisional stage were consistent with ground measurements. Similar characteristics of seasonal and monthly variations were found among the measurements, though the observational methodologies were different, showing maxima in the summer and spring and minima in the winter and autumn.

  11. The Surface Water and Ocean Topography Satellite Mission - An Assessment of Swath Altimetry Measurements of River Hydrodynamics

    Science.gov (United States)

    Wilson, Matthew D.; Durand, Michael; Alsdorf, Douglas; Chul-Jung, Hahn; Andreadis, Konstantinos M.; Lee, Hyongki

    2012-01-01

    The Surface Water and Ocean Topography (SWOT) satellite mission, scheduled for launch in 2020 with development commencing in 2015, will provide a step-change improvement in the measurement of terrestrial surface water storage and dynamics. In particular, it will provide the first, routine two-dimensional measurements of water surface elevations, which will allow for the estimation of river and floodplain flows via the water surface slope. In this paper, we characterize the measurements which may be obtained from SWOT and illustrate how they may be used to derive estimates of river discharge. In particular, we show (i) the spatia-temporal sampling scheme of SWOT, (ii) the errors which maybe expected in swath altimetry measurements of the terrestrial surface water, and (iii) the impacts such errors may have on estimates of water surface slope and river discharge, We illustrate this through a "virtual mission" study for a approximately 300 km reach of the central Amazon river, using a hydraulic model to provide water surface elevations according to the SWOT spatia-temporal sampling scheme (orbit with 78 degree inclination, 22 day repeat and 140 km swath width) to which errors were added based on a two-dimension height error spectrum derived from the SWOT design requirements. Water surface elevation measurements for the Amazon mainstem as may be observed by SWOT were thereby obtained. Using these measurements, estimates of river slope and discharge were derived and compared to those which may be obtained without error, and those obtained directly from the hydraulic model. It was found that discharge can be reproduced highly accurately from the water height, without knowledge of the detailed channel bathymetry using a modified Manning's equation, if friction, depth, width and slope are known. Increasing reach length was found to be an effective method to reduce systematic height error in SWOT measurements.

  12. Dynamic and reduced-dynamic precise orbit determination of satellites in low earth orbits

    International Nuclear Information System (INIS)

    The precise positioning of satellites in Low Earth Orbits (LEO) has become a key technology for advanced space missions. Dedicated satellite missions, such as CHAMP, GRACE and GOCE, that aim to map the Earths gravity field and its variation over time with unprecedented accuracy, initiated the demand for highly precise orbit solutions of LEO satellites. Furthermore, a wide range of additional science opportunities opens up with the capability to generate accurate LEO orbits. For all considered satellite missions, the primary measurement system for navigation is a spaceborne GPS receiver. The goal of this thesis is to establish and implement methods for Precise Orbit Determination (POD) of LEO satellites using GPS. Striving for highest precision using yet efficient orbit generation strategies, the attained orbit solutions are aimed to be competitive with the most advanced solutions of other institutions. Dynamic and reduced-dynamic orbit models provide the basic concepts of this work. These orbit models are subsequently adjusted to the highly accurate GPS measurements. The GPS measurements are introduced at the zero difference level in the ionosphere free linear combination. Appropriate procedures for GPS data screening and editing are established to detect erroneous data and to employ measurements of good quality only. For the dynamic orbit model a sophisticated force model, especially designed for LEO satellites, has been developed. In order to overcome the limitations that are induced by the deficiencies of the purely dynamical model, two different types of empirical parameters are introduced into the force model. These reduced-dynamic orbit models allow for the generation of much longer orbital arcs while preserving the spacecraft dynamics to the most possible extent. The two methods for reduced-dynamic orbit modeling are instantaneous velocity changes (pulses) or piecewise constant accelerations. For both techniques highly efficient modeling algorithms are

  13. Spectrally Enhanced Cloud Objects—A generalized framework for automated detection of volcanic ash and dust clouds using passive satellite measurements: 1. Multispectral analysis

    Science.gov (United States)

    Pavolonis, Michael J.; Sieglaff, Justin; Cintineo, John

    2015-08-01

    While satellites are a proven resource for detecting and tracking volcanic ash and dust clouds, existing algorithms for automatically detecting volcanic ash and dust either exhibit poor overall skill or can only be applied to a limited number of sensors and/or geographic regions. As such, existing techniques are not optimized for use in real-time applications like volcanic eruption alerting and data assimilation. In an effort to significantly improve upon existing capabilities, the Spectrally Enhanced Cloud Objects (SECO) algorithm was developed. The SECO algorithm utilizes a combination of radiative transfer theory, a statistical model, and image processing techniques to identify volcanic ash and dust clouds in satellite imagery with a very low false alarm rate. This fully automated technique is globally applicable (day and night) and can be adapted to a wide range of low earth orbit and geostationary satellite sensors or even combinations of satellite sensors. The SECO algorithm consists of four primary components: conversion of satellite measurements into robust spectral metrics, application of a Bayesian method to estimate the probability that a given satellite pixel contains volcanic ash and/or dust, construction of cloud objects, and the selection of cloud objects deemed to have the physical attributes consistent with volcanic ash and/or dust clouds. The first two components of the SECO algorithm are described in this paper, while the final two components are described in a companion paper.

  14. Evaluation of Point Positioning Using the Global Positioning System and the Quasi-Zenith Satellite System as Measured from South Korea

    Science.gov (United States)

    Choi, Byung-Kyu; Cho, Chang-Hyun; Cho, Jung Ho

    2015-12-01

    The Quasi-Zenith Satellite System (QZSS), a dedicated regional Japanese satellite system currently under development, was designed to complement the performance of the Global Positioning System (GPS). The high elevation angle of the QZSS satellite is expected to enhance the effectiveness of GPS in urban environments. Thus, the work described in this paper, aimed to investigate the effect of QZSS on GPS performance, by processing the GPS and QZSS measurements recorded at the Bohyunsan reference station in South Korea. We used these data, to evaluate the satellite visibility, carrier-to-noise density (C/No), performance of single point positioning, and Dilution of Precision (DOP). The QZSS satellite is currently available over South Korea for 19 hours at an elevation angle of more than 10 degrees. The results showed that the impact of the QZSS on users' vertical positioning is greatest when the satellite is above 80 degrees of elevation. As for Precise Point Positioning (PPP) performance, the combined GPS/QZSS kinematic PPP was found to improve the positioning accuracy compared to the GPS only kinematic PPP.

  15. Shipboard Sunphotometer Measurements of Aerosol Optical Depth Spectra and Columnar Water Vapor During ACE-2 and Comparison with Selected Land, Ship, Aircraft, and Satellite Measurements

    Science.gov (United States)

    Livingston, John M.; Kapustin, Vladimir N.; Schmid, Beat; Russell, Philip B.; Quinn, Patricia K.; Bates, Timothy S.; Durkee, Philip A.; Smith, Peter J.; Freudenthaler, Volker; Wiegner, Matthias; Covert, Dave S.; Gasso, Santiago; Hegg, Dean; Collins, Donald R.; Flagan, Richard C.; Seinfeld, John H.; Vitale, Vito; Tomasi, Claudio

    2000-01-01

    Analyses of aerosol optical depth (AOD) and colurnmn water vapor (CWV) measurements acquired with NASA Ames Research Center's 6-channel Airborne Tracking Sunphotometer (AATS-6) operated aboard the R/V Professor Vodyanitskiy during the 2nd Aerosol Characterization Experiment (ACE-2) are discussed. Data are compared with various in situ and remote measurements for selected cases. The focus is on 10 July, when the Pelican airplane flew within 70 km of the ship near the time of a NOAA-14/AVHRR satellite overpass and AOD measurements with the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14) above the marine boundary layer (MBL) permitted calculation of AOD within the MBL from the AATS-6 measurements. A detailed column closure test is performed for MBL AOD on 10 July by comparing the AATS-6 MBL AODs with corresponding values calculated by combining shipboard particle size distribution measurements with models of hygroscopic growth and radiosonde humidity profiles (plus assumptions on the vertical profile of the dry particle size distribution and composition). Large differences (30-80% in the mid-visible) between measured and reconstructed AODs are obtained, in large part because of the high sensitivity of the closure methodology to hygroscopic growth models, which vary considerably and have not been validated over the necessary range of particle size/composition distributions. The wavelength dependence of AATS-6 AODs is compared with the corresponding dependence of aerosol extinction calculated from shipboard measurements of aerosol size distribution and of total scattering mearured by a shipboard integrating nephelometer for several days. Results are highly variable, illustrating further the great difficulty of deriving column values from point measurements. AATS-6 CWV values are shown to agree well with corresponding values derived from radiosonde measurements during 8 soundings on 7 days and also with values calculated from measurements taken on 10 July with

  16. Evaluating the design of satellite scanning radiometers for earth radiation budget measurements with system simulations. Part 1: Instantaneous estimates

    Science.gov (United States)

    Stowe, Larry; Ardanuy, Philip; Hucek, Richard; Abel, Peter; Jacobowitz, Herbert

    1991-10-01

    A set of system simulations was performed to evaluate candidate scanner configurations to fly as a part of the Earth Radiation Budget Instrument (ERBI) on the polar platforms during the 1990's. The simulation is considered of instantaneous sampling (without diurnal averaging) of the longwave and shortwave fluxes at the top of the atmosphere (TOA). After measurement and subsequent inversion to the TOA, the measured fluxes were compared to the reference fluxes for 2.5 deg lat/long resolution targets. The reference fluxes at this resolution are obtained by integrating over the 25 x 25 = 625 grid elements in each target. The differences between each of these two resultant spatially averaged sets of target measurements (errors) are taken and then statistically summarized. Five instruments are considered: (1) the Conically Scanning Radiometer (CSR); (2) the ERBE Cross Track Scanner; (3) the Nimbus-7 Biaxial Scanner; (4) the Clouds and Earth's Radiant Energy System Instrument (CERES-1); and (5) the Active Cavity Array (ACA). Identical studies of instantaneous error were completed for many days, two seasons, and several satellite equator crossing longitudes. The longwave flux errors were found to have the same space and time characteristics as for the shortwave fluxes, but the errors are only about 25 pct. of the shortwave errors.

  17. Separating aerosol microphysical effects and satellite measurement artifacts of the relationships between warm rain onset height and aerosol optical depth

    Science.gov (United States)

    Zhu, Yannian; Rosenfeld, Daniel; Yu, Xing; Li, Zhanqing

    2015-08-01

    The high resolution (375 m) of the Visible Infrared Imaging Radiometer Suite on board the Suomi National Polar-Orbiting Partnership satellite allows retrieving relatively accurately the vertical evolution of convective cloud drop effective radius (re) with height or temperature. A tight relationship is found over SE Asia and the adjacent seas during summer between the cloud-free aerosol optical depth (AOD) and the cloud thickness required for the initiation of warm rain, as represented by the satellite-retrieved cloud droplet re of 14 µm, for a subset of conditions that minimize measurement artifacts. This cloud depth (ΔT14) is parameterized as the difference between the cloud base temperature and the temperature at the height where re exceeds 14 µm (T14). For a unit increase of AOD, the height of rain initiation is increased by about 5.5 km. The concern of data artifacts due to the increase in AOD near clouds was mitigated by selecting only scenes with cloud fraction (CF) 0.1 and ΔT14 > ~20°C, the increase of ΔT14 gradually levels off with further increase of AOD, possibly because the AOD is enhanced by aerosol upward transport and detrainment through the clouds below the T14 isotherm. The bias in the retrieved re due to the different geometries of solar illumination was also quantified. It was shown that the retrievals are valid only for backscatter views or when avoiding scenes with significant amount of cloud self-shadowing. These artifacts might have contributed to past reported relationships between cloud properties and AOD.

  18. Satellite measurements of the Madden-Julian oscillation in wintertime stratospheric ozone over the Tibetan Plateau and East Asia

    Science.gov (United States)

    Zhang, Yuli; Liu, Yi; Liu, Chuanxi; Sofieva, V. F.

    2015-11-01

    We investigate the Madden-Julian Oscillation (MJO) signal in wintertime stratospheric ozone over the Tibetan Plateau and East Asia using the harmonized dataset of satellite ozone profiles. Two different MJO indices—the all-season Real-Time multivariate MJO index (RMM) and outgoing longwave radiation-based MJO index (OMI)—are used to compare the MJO-related ozone anomalies. The results show that there are pronounced eastward-propagating MJO-related stratospheric ozone anomalies (mainly within 20-200 hPa) over the subtropics. The negative stratospheric ozone anomalies are over the Tibetan Plateau and East Asia in MJO phases 4-7, when MJO-related tropical deep convective anomalies move from the equatorial Indian Ocean towards the western Pacific Ocean. Compared with the results based on RMM, the MJO-related stratospheric column ozone anomalies based on OMI are stronger and one phase ahead. Further analysis suggests that different sampling errors, observation principles and retrieval algorithms may be responsible for the discrepancies among different satellite measurements. The MJO-related stratospheric ozone anomalies can be attributed to the MJO-related circulation anomalies, i.e., the uplifted tropopause and the northward shifted westerly jet in the upper troposphere. Compared to the result based on RMM, the upper tropospheric westerly jet may play a less important role in generating the stratospheric column ozone anomalies based on OMI. Our study indicates that the circulation-based MJO index (RMM) can better characterize the MJO-related anomalies in tropopause pressure and thus the MJO influence on atmospheric trace gases in the upper troposphere and lower stratosphere, especially over subtropical East Asia.

  19. Improved Satellite Retrievals of NO2 and SO2 over the Canadian Oil Sands and Comparisons with Surface Measurements

    Science.gov (United States)

    McLinden, C. A.; Fioletov, V.; Boersma, K. F.; Kharol, S. K.; Krotkov, N.; Lamsal, L.; Makar, P. A.; Martin, R. V.; Veefkind, J. P.; Yang, K.

    2014-01-01

    Satellite remote sensing is increasingly being used to monitor air quality over localized sources such as the Canadian oil sands. Following an initial study, significantly low biases have been identified in current NO2 and SO2 retrieval products from the Ozone Monitoring Instrument (OMI) satellite sensor over this location resulting from a combination of its rapid development and small spatial scale. Air mass factors (AMFs) used to convert line-of-sight "slant" columns to vertical columns were re-calculated for this region based on updated and higher resolution input information including absorber profiles from a regional-scale (15 km × 15 km resolution) air quality model, higher spatial and temporal resolution surface reflectivity, and an improved treatment of snow. The overall impact of these new Environment Canada (EC) AMFs led to substantial increases in the peak NO2 and SO2 average vertical column density (VCD), occurring over an area of intensive surface mining, by factors of 2 and 1.4, respectively, relative to estimates made with previous AMFs. Comparisons are made with long-term averages of NO2 and SO2 (2005-2011) from in situ surface monitors by using the air quality model to map the OMI VCDs to surface concentrations. This new OMI-EC product is able to capture the spatial distribution of the in situ instruments (slopes of 0.65 to 1.0, correlation coefficients of greater than 0.9). The concentration absolute values from surface network observations were in reasonable agreement, with OMI-EC NO2 and SO2 biased low by roughly 30%. Several complications were addressed including correction for the interference effect in the surface NO2 instruments and smoothing and clear-sky biases in the OMI measurements. Overall these results highlight the importance of using input information that accounts for the spatial and temporal variability of the location of interest when performing retrievals.

  20. Improved satellite retrievals of NO2 and SO2 over the Canadian oil sands and comparisons with surface measurements

    Directory of Open Access Journals (Sweden)

    C. A. McLinden

    2013-08-01

    Full Text Available Satellite remote sensing is increasingly being used to monitor air quality over localized sources such as the Canadian oil sands. Following an initial study, significant low biases have been identified in current NO2 and SO2 retrieval products from the Ozone Monitoring instrument (OMI satellite sensor over this location resulting from a combination of its rapid development and small spatial scale. Air mass factors (AMFs used to convert line-of-sight "slant" columns to vertical columns were re-calculated for this region based on updated and higher resolution input information including absorber profiles from a regional scale (15 km × 15 km resolution air quality (AQ model, higher spatial and temporal resolution surface reflectivity, and an improved treatment of snow. The overall impact of these new Environment Canada (EC AMFs led to substantial increases in the peak NO2 and SO2 average vertical column density (VCD, occurring over an area of intensive surface mining, by factors of 2 and 1.4, respectively, relative to estimates made with previous AMFs. Comparisons are made with long-term averages of NO2 and SO2 from in-situ surface monitors by using the AQ model to map the OMI VCDs to surface concentrations. This new OMI-EC product is able to capture the spatial distribution of the in-situ instruments (slopes of 0.7 to 1.0; correlation coefficients of 0.9. The concentration absolute values from surface network observations were in reasonable agreement, with OMI-EC NO2 and SO2 biased low by roughly 30%. Several complications were addressed including correction for the interference effect in the surface NO2 instruments and smoothing and clear-sky biases in the OMI measurements. Overall these results highlight the importance of using input information that accounts for the spatial and temporal variability of the location of interest when performing retrievals.

  1. Improved satellite retrievals of NO2 and SO2 over the Canadian oil sands and comparisons with surface measurements

    Science.gov (United States)

    McLinden, C. A.; Fioletov, V.; Boersma, K. F.; Kharol, S. K.; Krotkov, N.; Lamsal, L.; Makar, P. A.; Martin, R. V.; Veefkind, J. P.; Yang, K.

    2014-04-01

    Satellite remote sensing is increasingly being used to monitor air quality over localized sources such as the Canadian oil sands. Following an initial study, significantly low biases have been identified in current NO2 and SO2 retrieval products from the Ozone Monitoring Instrument (OMI) satellite sensor over this location resulting from a combination of its rapid development and small spatial scale. Air mass factors (AMFs) used to convert line-of-sight "slant" columns to vertical columns were re-calculated for this region based on updated and higher resolution input information including absorber profiles from a regional-scale (15 km × 15 km resolution) air quality model, higher spatial and temporal resolution surface reflectivity, and an improved treatment of snow. The overall impact of these new Environment Canada (EC) AMFs led to substantial increases in the peak NO2 and SO2 average vertical column density (VCD), occurring over an area of intensive surface mining, by factors of 2 and 1.4, respectively, relative to estimates made with previous AMFs. Comparisons are made with long-term averages of NO2 and SO2 (2005-2011) from in situ surface monitors by using the air quality model to map the OMI VCDs to surface concentrations. This new OMI-EC product is able to capture the spatial distribution of the in situ instruments (slopes of 0.65 to 1.0, correlation coefficients of >0.9). The concentration absolute values from surface network observations were in reasonable agreement, with OMI-EC NO2 and SO2 biased low by roughly 30%. Several complications were addressed including correction for the interference effect in the surface NO2 instruments and smoothing and clear-sky biases in the OMI measurements. Overall these results highlight the importance of using input information that accounts for the spatial and temporal variability of the location of interest when performing retrievals.

  2. MOBY, A Radiometric Buoy for Performance Monitoring and Vicarious Calibration of Satellite Ocean Color Sensors: Measurement and Data Analysis Protocols. Chapter 2

    Science.gov (United States)

    Clark, Dennis K.; Yarbrough, Mark A.; Feinholz, Mike; Flora, Stephanie; Broenkow, William; Kim, Yong Sung; Johnson, B. Carol; Brown, Steven W.; Yuen, Marilyn; Mueller, James L.

    2003-01-01

    The Marine Optical Buoy (MOBY) is the centerpiece of the primary ocean measurement site for calibration of satellite ocean color sensors based on independent in situ measurements. Since late 1996, the time series of normalized water-leaving radiances L(sub WN)(lambda) determined from the array of radiometric sensors attached to MOBY are the primary basis for the on-orbit calibrations of the USA Sea-viewing Wide Field-of-view Sensor (SeaWiFS), the Japanese Ocean Color and Temperature Sensor (OCTS), the French Polarization Detection Environmental Radiometer (POLDER), the German Modular Optoelectronic Scanner on the Indian Research Satellite (IRS1-MOS), and the USA Moderate Resolution Imaging Spectrometer (MODIS). The MOBY vicarious calibration L(sub WN)(lambda) reference is an essential element in the international effort to develop a global, multi-year time series of consistently calibrated ocean color products using data from a wide variety of independent satellite sensors. A longstanding goal of the SeaWiFS and MODIS (Ocean) Science Teams is to determine satellite-derived L(sub WN)(labda) with a relative combined standard uncertainty of 5 %. Other satellite ocean color projects and the Sensor Intercomparison for Marine Biology and Interdisciplinary Oceanic Studies (SIMBIOS) project have also adopted this goal, at least implicitly. Because water-leaving radiance contributes at most 10 % of the total radiance measured by a satellite sensor above the atmosphere, a 5 % uncertainty in L(sub WN)(lambda) implies a 0.5 % uncertainty in the above-atmosphere radiance measurements. This level of uncertainty can only be approached using vicarious-calibration approaches as described below. In practice, this means that the satellite radiance responsivity is adjusted to achieve the best agreement, in a least-squares sense, for the L(sub WN)(lambda) results determined using the satellite and the independent optical sensors (e.g. MOBY). The end result of this approach is to

  3. Electromagnetic fields, pacemakers and defibrillators; Champs electromagnetiques, cardiostimulateurs et defibrillateurs

    Energy Technology Data Exchange (ETDEWEB)

    Guiguet, J.C. [Agence Nationale des Frequences (ANFR), 94 - Maisons Alfort (France); Dodinot, B.; Sadoul, N.; Blangy, H. [Centre Hospitalier Universitaire Nancy-Brabois, Clinique Cardiologique, 54 - Vandoeuvre Brabois (France); Nadi, M.; Hedjiedj, A.; Schmitt, P. [Universite Henri Poincare-Nancy, Lab. d' Instrumentation Electronique de Nancy, Faculte des Sciences, 54 - Vandoeuvre les Nancy (France); Joly, L.; Dodinot, B.; Aliot, E. [Centre Hospitalier Universitaire Nancy-Brabois, Service de Cardiologie, 54 - Vandoeuvre-les-Nancy (France); Silny, J. [Aachen University (Germany); Franck, R.; Himbert, C.; Hidden-Lucet, F.; Petitot, J.C.; Fontaine, G. [Hopital Pitie-Salpetriere, Institut de Cardiologie, Service de Rythmologie, 75 - Paris (France); Souques, M.; Lambrozo, J. [Electricite de France (EDF-Gaz de France), Service des Etudes Medicales, 75 - Paris (France); Magne, I.; Bailly, J.M. [Electricite de France (EDF-Gaz de France), Div. Recherche Developpement, 77 - Moret sur Loing (France); Trigano, J.A. [Centre Hospitalier Universitaire, Hopital Nord, 13 - Marseille (France); Burais, N. [CEGELY, Ecole Centrale de Lyon, 69 - Ecully (France); Gaspard, J.Y. [Magtech, 69 - Ecully (France); Andrivet, Ph. [Societe Medtronic France, 92 - Boulogne-Billancourt (France)

    2004-07-01

    Presentation of electromagnetic sources constituted by various radio transmitters contributing to different radio communication services in the environment. Results of a measures campaign to assess the electromagnetic field in the close neighbourhood of various stations. Analysis by frequency domains. (author)

  4. Comparison of in-situ measurements and satellite-derived surface emissivity over Italian volcanic areas

    Science.gov (United States)

    Silvestri, Malvina; Musacchio, Massimo; Cammarano, Diego; Fabrizia Buongiorno, Maria; Amici, Stefania; Piscini, Alessandro

    2016-04-01

    In this work we compare ground measurements of emissivity collected during dedicated fields campaign on Mt. Etna and Solfatara of Pozzuoli volcanoes and acquired by means of Micro-FTIR (Fourier Thermal Infrared spectrometer) instrument with the emissivity obtained by using single ASTER data (Advanced Spaceborne Thermal Emission and Reflection Radiometer, ASTER 05) and the ASTER emissivity map extract from ASTER Global Emissivity Database (GED), released by LP DAAC on April 2, 2014. The database was developed by the National Aeronautics and Space Administration's (NASA) Jet Propulsion Laboratory (JPL), California Institute of Technology. The database includes land surface emissivity derived from ASTER data acquired over the contiguous United States, Africa, Arabian Peninsula, Australia, Europe, and China. Through this analysis we want to investigate the differences existing between the ASTER-GED dataset (average from 2000 to 2008 seasoning independent) and fall in-situ emissivity measurement. Moreover the role of different spatial resolution characterizing ASTER and MODIS, 90mt and 1km respectively, by comparing them with in situ measurements, is analyzed. Possible differences can be due also to the different algorithms used for the emissivity estimation, Temperature and Emissivity Separation algorithm for ASTER TIR band( Gillespie et al, 1998) and the classification-based emissivity method (Snyder and al, 1998) for MODIS. Finally land surface temperature products generated using ASTER-GED and ASTER 05 emissivity are also analyzed. Gillespie, A. R., Matsunaga, T., Rokugawa, S., & Hook, S. J. (1998). Temperature and emissivity separation from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images. IEEE Transactions on Geoscience and Remote Sensing, 36, 1113‑1125. Snyder, W.C., Wan, Z., Zhang, Y., & Feng, Y.-Z. (1998). Classification-based emissivity for land surface temperature measurement from space. International Journal of Remote Sensing

  5. Developments and applications of the Global Satellite Mapping of Precipitation (GSMaP) for the Global Precipitation Measurement (GPM)

    Science.gov (United States)

    Kachi, Misako; Aonashi, Kazumasa; Kubota, Takuji; Shige, Shoichi; Ushio, Tomoo; Mega, Tomoaki; Yamamoto, Munehisa; Hamada, Atsushi; Seto, Shinta; Takayabu, Yukari N.; Oki, Riko

    2016-04-01

    The Global Satellite Mapping of Precipitation (GSMaP) is a global rainfall map based on a blended Microwave-Infrared product and has been developed in Japan for the Global Precipitation Measurement (GPM) mission. To fulfill gaps of passive microwave observations, we developed a method to interpolate observations between each microwave imager by utilizing information from the Infrared imagers on board the geostationary satellites, and achieved production of an hourly global rainfall map in 0.1-degree latitude/longitude grid. The latest GSMaP version 6 product was released in September 2014 to the public as one of Japanese GPM products after the launch of the GPM Core Observatory, which is Japan and U.S. joint mission and carrying both the Dual-frequency Precipitation Radar (DPR) and GPM Microwave Imager (GMI), in February 2014. In the next version (version 7), which is scheduled to be released in the summer 2016, we plan to apply databases produced from DPR instead of those from PR, and to introduce snow retrieval algorithm for the passive microwave instruments that have higher frequency channels. The GSMaP near-real-time version (GSMaP_NRT) product is available 4-hour after observation through the "JAXA Global Rainfall Watch" web site (http://sharaku.eorc.jaxa.jp/GSMaP) since 2008. To assure near-real-time data availability, the GSMaP_NRT system simplified part of the algorithm and its processing procedure. Therefore, the GSMaP_NRT product gives higher priority to data latency than accuracy. Since its data release, GSMaP_NRT data has been used by various users for various purposes, such as rainfall monitoring, flood alert and warning, drought monitoring, crop yield forecast, and agricultural insurance. There are, however, several requirements from users for GSMaP improvements not only for accuracy but also specification. Among those requests for data specification, the most popular ones are shortening of data latency time and higher horizontal resolution. To reduce

  6. Earth radiation budget measurement from a spinning satellite: Conceptual design of detectors

    Science.gov (United States)

    Sromovsky, L. A.; Revercomb, H. E.; Suomi, V. E.

    1975-01-01

    The conceptual design, sensor characteristics, sensor performance and accuracy, and spacecraft and orbital requirements for a spinning wide-field-of-view earth energy budget detector were investigated. The scientific requirements for measurement of the earth's radiative energy budget are presented. Other topics discussed include the observing system concept, solar constant radiometer design, plane flux wide FOV sensor design, fast active cavity theory, fast active cavity design and error analysis, thermopile detectors as an alternative, pre-flight and in-flight calibration plane, system error summary, and interface requirements.

  7. MULTI-ELEMENT ABUNDANCE MEASUREMENTS FROM MEDIUM-RESOLUTION SPECTRA. III. METALLICITY DISTRIBUTIONS OF MILKY WAY DWARF SATELLITE GALAXIES

    International Nuclear Information System (INIS)

    We present metallicity distribution functions (MDFs) for the central regions of eight dwarf satellite galaxies of the Milky Way: Fornax, Leo I and II, Sculptor, Sextans, Draco, Canes Venatici I, and Ursa Minor. We use the published catalog of abundance measurements from the previous paper in this series. The measurements are based on spectral synthesis of iron absorption lines. For each MDF, we determine maximum likelihood fits for Leaky Box, Pre-Enriched, and Extra Gas (wherein the gas supply available for star formation increases before it decreases to zero) analytic models of chemical evolution. Although the models are too simplistic to describe any MDF in detail, a Leaky Box starting from zero metallicity gas fits none of the galaxies except Canes Venatici I well. The MDFs of some galaxies, particularly the more luminous ones, strongly prefer the Extra Gas Model to the other models. Only for Canes Venatici I does the Pre-Enriched Model fit significantly better than the Extra Gas Model. The best-fit effective yields of the less luminous half of our galaxy sample do not exceed 0.02 Zsun, indicating that gas outflow is important in the chemical evolution of the less luminous galaxies. We surmise that the ratio of the importance of gas infall to gas outflow increases with galaxy luminosity. Strong correlations of average [Fe/H] and metallicity spread with luminosity support this hypothesis.

  8. Multi-Element Abundance Measurements from Medium-Resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies

    CERN Document Server

    Kirby, Evan N; Simon, Joshua D; Cohen, Judith G; Guhathakurta, Puragra

    2010-01-01

    We present metallicity distribution functions (MDFs) for the central regions of eight dwarf satellite galaxies of the Milky Way: Fornax, Leo I and II, Sculptor, Sextans, Draco, Canes Venatici I, and Ursa Minor. We use the published catalog of abundance measurements from the previous paper in this series. The measurements are based on spectral synthesis of iron absorption lines. For each MDF, we determine maximum likelihood fits for Leaky Box, Pre-Enriched, and Extra Gas (wherein the gas supply available for star formation increases before it decreases to zero) analytic models of chemical evolution. Although the models are too simplistic to describe any MDF in detail, a Leaky Box starting from zero metallicity gas fits none of the galaxies except Canes Venatici I well. The MDFs of some galaxies, particularly the more luminous ones, strongly prefer the Extra Gas Model to the other models. Only for Canes Venatici I does the Pre-Enriched Model fit significantly better than the Extra Gas Model. The best-fit effect...

  9. Direct measurement of sub-pixel structure of the EPIC MOS CCD on-board the XMM/NEWTON satellite

    International Nuclear Information System (INIS)

    We have used a mesh experiment in order to measure the sub-pixel structure of the EPIC MOS CCDs on-board the XMM/NEWTON satellite. The EPIC MOS CCDs have 40 μm-square pixels which have an open electrode structure in order to improve the detection efficiency for low-energy X-rays. We obtained restored pixel images for various X-ray event grades (e.g. split-pixel events, single pixel events, etc.) at various X-ray energies. We confirmed that the open electrode structure results in a distorted horizontal pixel boundary. The open electrode region generates both single pixel events and vertically split events, but no horizontally split events. Because the single pixel events usually show the best energy resolution, we discuss a method of increasing the fraction of single pixel events from the open electrode region. Furthermore, we have directly measured the thickness of the electrodes and dead-layers by comparing spectra from the open electrode region with those from the other regions: electrodes, electrode finger and channel stop. We can say that EPIC MOS CCDs are more radiation hard than front-illumination chips of ACIS on-board Chandra X-ray Observatory because of their extra absorption thickness above the charge transfer channel. We calculated the mean pixel response and found that our estimation has a good agreement with that of the ground calibration of EPIC MOS CCD

  10. Imaging Earth's crustal magnetic field with satellite data. A regularised spherical triangle tessellation approach

    International Nuclear Information System (INIS)

    Complete text of publication follows. We will present a method for imaging the global crustal magnetic field at Earth's surface using a local basis representation and a minimum norm approach. The local basis consists of a spherical triangle tessellation (STT) parameterisation of the vertical component of the crustal field at Earth's surface. The Green's function for Laplace's equation in spherical geometry with Neumann boundary conditions provides the necessary forward modelling scheme. We solve the inverse problem of estimating the crustal field from magnetic observations by minimising an objective function consisting of a mean absolute deviation (L1 -norm) measure of misfit plus a norm measuring model complexity. Both quadratic and entropy measures of field complexity are investigated. Applying our technique to real observations collected by the CHAMP, Orsted and SAC-C satellites, we obtain stable images of the crustal magnetic field at Earth's surface that include sharp features with high amplitude. These images provide a perspective on the crustal magnetic field complementary to that given by conventional spherical harmonic models.

  11. Adjacency effect estimation by ground spectra measurement and satellite optical sensor synchronous observation data

    Institute of Scientific and Technical Information of China (English)

    Jianwen Ma; Xue Chen

    2006-01-01

    @@ This paper addresses the estimation of adjacency effect of CBERS-2 image.The adjacency effect influences the digital number (DN) value of a pixel by adding surrounding scattering signals and path scattering signals.Based on the theory of radiation transfer model,a procedure is designed to measure the reflectance from the surface target materials and the materials in a box,which is 1.5 m above the surface to avoid upwelling reflectance.The results show that the adjacency effect varies from visible,near infrared and becomes steady within short infrared wavelength region;the adjacency effect weakens with the increase of distance between testing sites.The adjacency effect of CBERS-2 image is corrected and the quality of the resulting image is improved.

  12. Simultaneous radio and satellite optical measurements of high-altitude sprite current and lightning continuing current

    Science.gov (United States)

    Cummer, Steven A.; Frey, Harald U.; Mende, Stephen B.; Hsu, Rue-Ron; Su, Han-Tzong; Chen, Alfred B.; Fukunishi, Hiroshi; Takahashi, Yukihiro

    2006-10-01

    We report coordinated measurements of lightning and resulting sprites using ground-level magnetic field sensors (altitude optical emissions from the lightning flash, indicating that this radio signature is produced by continuing lightning current. Second, in two events with strong postreturn stroke extremely low frequency (ELF) magnetic pulses, the optical emissions demonstrate that there are no observable intensifications of low-altitude optical emissions associated with those pulses. If they were produced by a lightning process, such as an M-component, the connection between optical emissions and current seen in the return stroke and the continuing current suggests they should be visible. However, as has been observed previously, the bright, high-altitude optical emissions associated with the sprite are simultaneous with the ELF pulse. This is strong evidence that these ELF pulses originate in high-altitude electric current in the sprite itself and are not produced by a low-altitude lightning process.

  13. Satellite passive microwave rain rate measurement over croplands during spring, summer and fall

    International Nuclear Information System (INIS)

    Rain rate algorithms for spring, summer and fall that have been developed from comparisons between the brightness temperatures measured by the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and rain rates derived from operational WSR-57 radars over land are described. Data were utilized from a total of 25 SMMR passes and 234 radars, resulting in ∼12 000 observations of ∼1600 km2 areas. Multiple correlation coefficients of 0.63, 0.80 and 0.75 are achieved for the spring, summer and fall algorithms, respectively. Most of this information is in the form of multifrequency contrast in brightness temperature, which is interpreted as a measurement of the degree to which the land-emitted radiation is attenuated by the rain systems. The SMMR 37 GHz channel has more information on rain rate than any other channel. By combining the lower frequency channels with the 37 GHz observations, variations in land and precipitation thermometric temperatures can be removed, leaving rain attenuation as the major effect on brightness temperature. Polarization screening at 37 GHz is found to be sufficient to screen out cases of wet ground, which is only important when the ground is relatively vegetation free. Heavy rain cases are found to be a significant part of the algorithms' success, because of the strong microwave signatures (low brightness temperatures) that result from the presence of precipitation-sized ice in the upper portions of heavily precipitating storms. If IR data are combined with the summer microwave data, an improved (0.85) correlation with radar rain rates is achieved

  14. Validation of satellite altimeter range measurements over salar de Uyuni, Bolivia

    Science.gov (United States)

    Fricker, H. A.; Roca, M.; Laxon, S. W.; Carabajal, C. C.; Quinn, K.; Borsa, A. A.; Minster, J. B.

    2003-12-01

    The salar de Uyuni in the Bolivian altiplano covers approximately 9600 km2, and is the largest dry salt lake in the world. This vast, flat stable surface is ideal for estimation of the range bias on altimeter instruments such as GLAS on board ICESat (launched 12th January 2003), RA-2 on board ENVISAT (launched March 1st 2002) and the ERS-2 radar altimeter (RA, launched 1995), and to compare the measurements from these altimeters. Here we describe a kinematic GPS survey of the salar de Uyuni that was carried out in August/September 2002 and was designed to calibrate GLAS and RA-2. The eastern part of the salar was surveyed with 8 grids 22.5 km x 13.5 km at 2.25 km spacing, and with 2 grids which straddled one ascending and one descending ERS-2/ENVISAT orbit across this part of the salar, one 44.5 x 9 km, the other 18 x 13.5 km. Comparison of GPS heights from one GPS grid to the next and crossover analysis at intersections suggests that RMS accuracy of the GPS measurement is around 2 cm. We retracked the altimeter waveforms by fitting the system point target response to retrieve the altimeter surface elevation. We fitted a gaussian-smoothed surface to the GPS heights collected around the ERS-2/ENVISAT grids and interpolated these surfaces to the locations of altimeter footprints to obtain an estimate of the range bias for each instruments (GLAS, RA-2 and the ERS-2 RA). We also compare our results with data from one cycle of TOPEX data, which was collected during an orbit manoeuvre phase in September 2002. Ground tracks from this cycle serendipitously crossed our survey area at the same time we were on the ground.

  15. Question No. 5: What Role Can Satellites Take, as a Complement to Ground Based Measurement Systems, to Provide Sustained Observations to Monitor GHG Emissions?

    Science.gov (United States)

    Chahine, Moustafa; Olsen, Edward

    2011-01-01

    What role can satellites take, as a complement to ground based measurement systems, to provide sustained observations to monitor GHG emissions (e.g., CO2, CH4, O3, N2O, CFC s, NH3, and NF3) that contribute to global warming?

  16. The surface albedo of the Vatnajökull ice cap, Iceland: comparison between satellite-derived and ground-based measurements

    NARCIS (Netherlands)

    Reijmer, C.; Knap, W.H.; Oerlemans, J.

    1999-01-01

    The temporal and spatial variations in the surface albedo of the Vatnajökull ice cap, Iceland, are investigated. A time series of the surface albedo is composed for the summer of 1996 using satellite radiance measurements from the Advanced Very High Resolution Radiometer (AVHRR). This time series is

  17. Dynamics of the outer belt of energetic electrons according to the data of simultaneous measurements at the Interkosmos-19 and Kosmos-900 satellites

    International Nuclear Information System (INIS)

    Dynamics of the outer belt of energetic electrons according to the data of simultaneous measurements at the ''Interkosmos-19'' and ''Kosmos-900'' satellites under different geomagnetic activity in March, 1979, is investigated. Electron differential spectra are presented. For the first time a rapid diffusional electron wave is registered during magnetic storm in a wide energy range

  18. Structure de bandes et transport électronique dans les nanotubes de carbone sous champ magnétique intense

    OpenAIRE

    Nanot, Sebastien

    2009-01-01

    Des mesures de transport électronique dans des nanotubes de carbone multiparois individuels sous champ magnétique pulsé (60T) sont présentées dans cette thèse. L'objectif est d'observer les modifications de la dispersion électronique par le champ magnétique. Des nanotubes de très bonne qualité cristalline sont connectés sur des distances courtes entre contacts, permettant d'atteindre des régimes de transport quasi-balistiques ou faiblement diffusifs, la paroi externe contribuant principalemen...

  19. Recent glacier changes in the Tien Shan observed by satellite gravity measurements

    Science.gov (United States)

    Jin, Shuanggen; Tian, X.; Feng, G.

    2016-08-01

    The glaciers in the Tien Shan are extensive and play an important role in water cycle in central Asia. However, it is difficult to accurately monitor glacier variations in the Tien Shan due to the lack of in situ widespread measurements. In this paper, glacier mass variations in the Tian Shan are obtained and investigated from 10 years of monthly GRACE gravity solutions (January 2003-December 2012) and the WaterGAP Global Hydrology Model (WGHM), including seasonal, secular and interannual variations . Results show that significant seasonal variations of glacier mass are found with the maximum normally in April-June and the minimum around in November-December. The trends in all four regions are positive from 2002 to 2005 and negative from 2005 to 2012, indicating that the Tien Shan glaciers are increasing prior to 2005 and significantly melting after 2005. These changes are consistent with the temperature change in the Tien Shan. In addition, in the past decade the precipitation has decreased and evapotranspiration has increased, which have joint influences on glacier mass changes in different regions of the Tien Shan.

  20. Power laws and inverse motion modelling: application to turbulence measurements from satellite images

    Directory of Open Access Journals (Sweden)

    Pablo D. Mininni

    2012-01-01

    Full Text Available In the context of tackling the ill-posed inverse problem of motion estimation from image sequences, we propose to introduce prior knowledge on flow regularity given by turbulence statistical models. Prior regularity is formalised using turbulence power laws describing statistically self-similar structure of motion increments across scales. The motion estimation method minimises the error of an image observation model while constraining second-order structure function to behave as a power law within a prescribed range. Thanks to a Bayesian modelling framework, the motion estimation method is able to jointly infer the most likely power law directly from image data. The method is assessed on velocity fields of 2-D or quasi-2-D flows. Estimation accuracy is first evaluated on a synthetic image sequence of homogeneous and isotropic 2-D turbulence. Results obtained with the approach based on physics of fluids outperform state-of-the-art. Then, the method analyses atmospheric turbulence using a real meteorological image sequence. Selecting the most likely power law model enables the recovery of physical quantities, which are of major interest for turbulence atmospheric characterisation. In particular, from meteorological images we are able to estimate energy and enstrophy fluxes of turbulent cascades, which are in agreement with previous in situ measurements.

  1. Satellite measurements oversee China’s sulfur dioxide emission reductions from coal-fired power plants

    Science.gov (United States)

    Wang, Siwen; Zhang, Qiang; Martin, Randall V.; Philip, Sajeev; Liu, Fei; Li, Meng; Jiang, Xujia; He, Kebin

    2015-11-01

    To evaluate the real reductions in sulfur dioxide (SO2) emissions from coal-fired power plants in China, Ozone Monitoring Instrument (OMI) remote sensing SO2 columns were used to inversely model the SO2 emission burdens surrounding 26 isolated power plants before and after the effective operation of their flue gas desulfurization (FGD) facilities. An improved two-dimensional Gaussian fitting method was developed to estimate SO2 burdens under complex background conditions, by using the accurate local background columns and the customized fitting domains for each target source. The OMI-derived SO2 burdens before effective FGD operation were correlated well with the bottom-up emission estimates (R = 0.92), showing the reliability of the OMI-derived SO2 burdens as a linear indicator of the associated source strength. OMI observations indicated that the average lag time period between installation and effective operation of FGD facilities at these 26 power plants was around 2 years, and no FGD facilities have actually operated before the year 2008. The OMI estimated average SO2 removal equivalence (56.0%) was substantially lower than the official report (74.6%) for these 26 power plants. Therefore, it has been concluded that the real reductions of SO2 emissions in China associated with the FGD facilities at coal-fired power plants were considerably diminished in the context of the current weak supervision measures.

  2. On the Global Water Productivity Distribution for Major Cereal Crops: some First Results from Satellite Measurements

    Science.gov (United States)

    Bastiaanssen, W. G.; Verstegen, J. A.; Steduto, P.; Goudriaan, R.; Wada, Y.

    2014-12-01

    Feeding the world requires 70 percent more food for an additional 2.3 billion people by 2050. The increasing competition for water resources prompts the modern consumer society to become more efficient with scarce water resources. The water footprint of agriculture is hundred times more than the footprint for domestic water use, yet we do not fully know how much water is used in relation to the amount of food being produced. Water Productivity describes the crop yield per unit of water consumed and is the ultimate indicator for the efficiency of water use in agriculture. Our basic understanding of actual and benchmark values for Water Productivity is limited, partially because operational measurements and guidelines for Water Productivity do not currently exist. Remote sensing algorithms have been developed over the last 20 years to compute crop yield Y and evapotranspiration ET, often in an independent manner. The new WatPro and GlobWat algorithms are based on directly solving the Y/ET ratio. Several biophysical parameter and processes such as solar radiation, Leaf Area Index, stomatal aperture and soil moisture affect biomass production and crop transpiration simultaneously, and this enabled us to simplify the schematization of a Y/ET model. Global maps of wheat, rice and maize were prepared from various open-access data sources, and Y/ET was computed across a period of 10 years. The global distribution demonstrates that 66 percent of the world's agricultural land cultivated with wheat, rice and corn performs below average. Furthermore, Water Productivity in most countries exhibits a significant spatial variability. Therefore, there is significant scope to produce the same food - or more food - from less water resources if packages with good practices are locally implemented. The global maps of water productivity will be demonstrated, along with some country examples.

  3. Evaluation of TRMM multi-satellite precipitation analysis (TMPA) against terrestrial measurement over a humid sub-tropical basin, India

    Science.gov (United States)

    Kumar, Dheeraj; Gautam, Amar Kant; Palmate, Santosh S.; Pandey, Ashish; Suryavanshi, Shakti; Rathore, Neha; Sharma, Nayan

    2016-04-01

    To support the GPM mission which is homologous to its predecessor, the Tropical Rainfall Measuring Mission (TRMM), this study has been undertaken to evaluate the accuracy of Tropical Rainfall Measuring Mission multi-satellite precipitation analysis (TMPA) daily-accumulated precipitation products for 5 years (2008-2012) using the statistical methods and contingency table method. The analysis was performed on daily, monthly, seasonal and yearly basis. The TMPA precipitation estimates were also evaluated for each grid point i.e. 0.25° × 0.25° and for 18 rain gauge stations of the Betwa River basin, India. Results indicated that TMPA precipitation overestimates the daily and monthly precipitation in general, particularly for the middle sub-basin in the non-monsoon season. Furthermore, precision of TMPA precipitation estimates declines with the decrease of altitude at both grid and sub-basin scale. The study also revealed that TMPA precipitation estimates provide better accuracy in the upstream of the basin compared to downstream basin. Nevertheless, the detection capability of daily TMPA precipitation improves with increase in altitude for drizzle rain events. However, the detection capability decreases during non-monsoon and monsoon seasons when capturing moderate and heavy rain events, respectively. The veracity of TMPA precipitation estimates was improved during the rainy season than during the dry season at all scenarios investigated. The analyses suggest that there is a need for better precipitation estimation algorithm and extensive accuracy verification against terrestrial precipitation measurement to capture the different types of rain events more reliably over the sub-humid tropical regions of India.

  4. MULTI-ELEMENT ABUNDANCE MEASUREMENTS FROM MEDIUM-RESOLUTION SPECTRA. II. CATALOG OF STARS IN MILKY WAY DWARF SATELLITE GALAXIES

    International Nuclear Information System (INIS)

    We present a catalog of Fe, Mg, Si, Ca, and Ti abundances for 2961 stars in eight dwarf satellite galaxies of the Milky Way (MW): Sculptor, Fornax, Leo I, Sextans, Leo II, Canes Venatici I, Ursa Minor, and Draco. For the purposes of validating our measurements, we also observed 445 red giants in MW globular clusters and 21 field red giants in the MW halo. The measurements are based on Keck/DEIMOS medium-resolution spectroscopy (MRS) combined with spectral synthesis. We estimate uncertainties in [Fe/H] by quantifying the dispersion of [Fe/H] measurements in a sample of stars in monometallic globular clusters (GCs). We estimate uncertainties in Mg, Si, Ca, and Ti abundances by comparing to high-resolution spectroscopic abundances of the same stars. For this purpose, a sample of 132 stars with published high-resolution spectroscopy in GCs, the MW halo field, and dwarf galaxies has been observed with MRS. The standard deviations of the differences in [Fe/H] and ([α/Fe]) (the average of [Mg/Fe], [Si/Fe], [Ca/Fe], and [Ti/Fe]) between the two samples is 0.15 and 0.16, respectively. This catalog represents the largest sample of multi-element abundances in dwarf galaxies to date. The next papers in this series draw conclusions on the chemical evolution, gas dynamics, and star formation histories from the catalog presented here. The wide range of dwarf galaxy luminosity reveals the dependence of dwarf galaxy chemical evolution on galaxy stellar mass.

  5. Analysis of BeiDou Satellite Measurements with Code Multipath and Geometry-Free Ionosphere-Free Combinations

    Directory of Open Access Journals (Sweden)

    Qile Zhao

    2016-01-01

    Full Text Available Using GNSS observable from some stations in the Asia-Pacific area, the carrier-to-noise ratio (CNR and multipath combinations of BeiDou Navigation Satellite System (BDS, as well as their variations with time and/or elevation were investigated and compared with those of GPS and Galileo. Provided the same elevation, the CNR of B1 observables is the lowest among the three BDS frequencies, while B3 is the highest. The code multipath combinations of BDS inclined geosynchronous orbit (IGSO and medium Earth orbit (MEO satellites are remarkably correlated with elevation, and the systematic “V” shape trends could be eliminated through between-station-differencing or modeling correction. Daily periodicity was found in the geometry-free ionosphere-free (GFIF combinations of both BDS geostationary Earth orbit (GEO and IGSO satellites. The variation range of carrier phase GFIF combinations of GEO satellites is −2.0 to 2.0 cm. The periodicity of carrier phase GFIF combination could be significantly mitigated through between-station differencing. Carrier phase GFIF combinations of BDS GEO and IGSO satellites might also contain delays related to satellites. Cross-correlation suggests that the GFIF combinations’ time series of some GEO satellites might vary according to their relative geometries with the sun.

  6. Analysis of BeiDou Satellite Measurements with Code Multipath and Geometry-Free Ionosphere-Free Combinations

    Science.gov (United States)

    Zhao, Qile; Wang, Guangxing; Liu, Zhizhao; Hu, Zhigang; Dai, Zhiqiang; Liu, Jingnan

    2016-01-01

    Using GNSS observable from some stations in the Asia-Pacific area, the carrier-to-noise ratio (CNR) and multipath combinations of BeiDou Navigation Satellite System (BDS), as well as their variations with time and/or elevation were investigated and compared with those of GPS and Galileo. Provided the same elevation, the CNR of B1 observables is the lowest among the three BDS frequencies, while B3 is the highest. The code multipath combinations of BDS inclined geosynchronous orbit (IGSO) and medium Earth orbit (MEO) satellites are remarkably correlated with elevation, and the systematic “V” shape trends could be eliminated through between-station-differencing or modeling correction. Daily periodicity was found in the geometry-free ionosphere-free (GFIF) combinations of both BDS geostationary Earth orbit (GEO) and IGSO satellites. The variation range of carrier phase GFIF combinations of GEO satellites is −2.0 to 2.0 cm. The periodicity of carrier phase GFIF combination could be significantly mitigated through between-station differencing. Carrier phase GFIF combinations of BDS GEO and IGSO satellites might also contain delays related to satellites. Cross-correlation suggests that the GFIF combinations’ time series of some GEO satellites might vary according to their relative geometries with the sun. PMID:26805831

  7. Analysis of BeiDou Satellite Measurements with Code Multipath and Geometry-Free Ionosphere-Free Combinations.

    Science.gov (United States)

    Zhao, Qile; Wang, Guangxing; Liu, Zhizhao; Hu, Zhigang; Dai, Zhiqiang; Liu, Jingnan

    2016-01-01

    Using GNSS observable from some stations in the Asia-Pacific area, the carrier-to-noise ratio (CNR) and multipath combinations of BeiDou Navigation Satellite System (BDS), as well as their variations with time and/or elevation were investigated and compared with those of GPS and Galileo. Provided the same elevation, the CNR of B1 observables is the lowest among the three BDS frequencies, while B3 is the highest. The code multipath combinations of BDS inclined geosynchronous orbit (IGSO) and medium Earth orbit (MEO) satellites are remarkably correlated with elevation, and the systematic "V" shape trends could be eliminated through between-station-differencing or modeling correction. Daily periodicity was found in the geometry-free ionosphere-free (GFIF) combinations of both BDS geostationary Earth orbit (GEO) and IGSO satellites. The variation range of carrier phase GFIF combinations of GEO satellites is -2.0 to 2.0 cm. The periodicity of carrier phase GFIF combination could be significantly mitigated through between-station differencing. Carrier phase GFIF combinations of BDS GEO and IGSO satellites might also contain delays related to satellites. Cross-correlation suggests that the GFIF combinations' time series of some GEO satellites might vary according to their relative geometries with the sun. PMID:26805831

  8. Methods of satellite oceanography

    Science.gov (United States)

    Stewart, R. H.

    1985-01-01

    The theoretical basis for remote sensing measurements of climate and ocean dynamics is examined. Consideration is given to: the absorption of electromagnetic radiation in the atmosphere; scattering in the atmosphere; and satellite observations using visible light. Consideration is also given to: the theory of radio scatter from the sea; scatter of centimeter waves from the sea; and the theory of operation of synthetic aperture radars. Additional topics include: the coordinate systems of satellite orbits for oceanographic remote sensing applications; the operating features of the major U.S. satellite systems for viewing the ocean; and satellite altimetry.

  9. THE ZURICH ENVIRONMENTAL STUDY (ZENS) OF GALAXIES IN GROUPS ALONG THE COSMIC WEB. II. GALAXY STRUCTURAL MEASUREMENTS AND THE CONCENTRATION OF MORPHOLOGICALLY CLASSIFIED SATELLITES IN DIVERSE ENVIRONMENTS

    International Nuclear Information System (INIS)

    We present structural measurements for the galaxies in the 0.05 GROUP), group-centric distance (R/R200), ranking into central or satellite, and large-scale structure density (δLSS). Global galaxy structure is quantified both parametrically and non-parametrically. We correct all these measurements for observational biases due to point-spread function blurring and surface brightness effects as a function of galaxy size, magnitude, steepness of light profile, and ellipticity. Structural parameters are derived also for bulges, disks, and bars. We use the galaxy bulge-to-total ratios (B/T) together with the calibrated non-parametric structural estimators to implement a quantitative morphological classification that maximizes purity in the resulting morphological samples. We investigate how the concentration C of satellite galaxies depends on galaxy mass for each Hubble type and on MGROUP, R/R200, and δLSS. At galaxy masses M ≥ 1010 M☉, the concentration of disk satellites increases with increasing stellar mass separately within each morphological bin of B/T. The known increase in concentration with stellar mass for disk satellites is thus due, at least in part, to an increase in galaxy central stellar density at constant B/T. The correlation between concentration and galaxy stellar mass becomes progressively steeper for later morphological types. The concentration of disk satellites shows a barely significant dependence on δLSS or R/R200. The strongest environmental effect is found with group mass for >1010 M☉ disk-dominated satellites, which are ∼10% more concentrated in high mass groups than in lower mass groups

  10. THE ZURICH ENVIRONMENTAL STUDY (ZENS) OF GALAXIES IN GROUPS ALONG THE COSMIC WEB. II. GALAXY STRUCTURAL MEASUREMENTS AND THE CONCENTRATION OF MORPHOLOGICALLY CLASSIFIED SATELLITES IN DIVERSE ENVIRONMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Cibinel, A.; Carollo, C. M.; Lilly, S. J.; Miniati, F.; Cameron, E.; Peng, Y.; Pipino, A.; Rudick, C. S. [Institute of Astronomy, ETH Zurich, CH-8093 Zurich (Switzerland); Silverman, J. D. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8583 (Japan); Van Gorkom, J. H. [Department of Astronomy, Columbia University, New York, NY 10027 (United States); Finoguenov, A. [Max-Planck-Institut für extraterrestrische Physik, D-84571 Garching (Germany); Norberg, P., E-mail: cibinel@phys.ethz.ch, E-mail: marcella@phys.ethz.ch [Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)

    2013-10-20

    We present structural measurements for the galaxies in the 0.05 < z < 0.0585 groups of the Zurich Environmental Study, aimed at establishing how galaxy properties depend on four environmental parameters: group halo mass (M{sub GROUP}), group-centric distance (R/R{sub 200}), ranking into central or satellite, and large-scale structure density (δ{sub LSS}). Global galaxy structure is quantified both parametrically and non-parametrically. We correct all these measurements for observational biases due to point-spread function blurring and surface brightness effects as a function of galaxy size, magnitude, steepness of light profile, and ellipticity. Structural parameters are derived also for bulges, disks, and bars. We use the galaxy bulge-to-total ratios (B/T) together with the calibrated non-parametric structural estimators to implement a quantitative morphological classification that maximizes purity in the resulting morphological samples. We investigate how the concentration C of satellite galaxies depends on galaxy mass for each Hubble type and on M{sub GROUP}, R/R{sub 200}, and δ{sub LSS}. At galaxy masses M ≥ 10{sup 10} M{sub ☉}, the concentration of disk satellites increases with increasing stellar mass separately within each morphological bin of B/T. The known increase in concentration with stellar mass for disk satellites is thus due, at least in part, to an increase in galaxy central stellar density at constant B/T. The correlation between concentration and galaxy stellar mass becomes progressively steeper for later morphological types. The concentration of disk satellites shows a barely significant dependence on δ{sub LSS} or R/R{sub 200}. The strongest environmental effect is found with group mass for >10{sup 10} M{sub ☉} disk-dominated satellites, which are ∼10% more concentrated in high mass groups than in lower mass groups.

  11. Ocean Optics Protocols for Satellite Ocean Color Sensor Validation. Volume 4; Inherent Optical Properties: Instruments, Characterizations, Field Measurements and Data Analysis Protocols; Revised

    Science.gov (United States)

    Mueller, J. L. (Editor); Fargion, Giuletta S. (Editor); McClain, Charles R. (Editor); Pegau, Scott; Zaneveld, J. Ronald V.; Mitchell, B. Gregg; Kahru, Mati; Wieland, John; Stramska, Malgorzat

    2003-01-01

    This document stipulates protocols for measuring bio-optical and radiometric data for the Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project activities and algorithm development. The document is organized into 6 separate volumes as Ocean Optics Protocols for Satellite Ocean Color Sensor Validation, Revision 4. Volume I: Introduction, Background and Conventions; Volume II: Instrument Specifications, Characterization and Calibration; Volume III: Radiometric Measurements and Data Analysis Methods; Volume IV: Inherent Optical Properties: Instruments, Characterization, Field Measurements and Data Analysis Protocols; Volume V: Biogeochemical and Bio-Optical Measurements and Data Analysis Methods; Volume VI: Special Topics in Ocean Optics Protocols and Appendices. The earlier version of Ocean Optics Protocols for Satellite Ocean Color Sensor Validation, Revision 3 (Mueller and Fargion 2002, Volumes 1 and 2) is entirely superseded by the six volumes of Revision 4 listed above.

  12. Ocean Optics Protocols for Satellite Ocean Color Sensor Validation, Revision 4, Volume IV: Inherent Optical Properties: Instruments, Characterizations, Field Measurements and Data Analysis Protocols

    Science.gov (United States)

    Mueller, J. L.; Fargion, G. S.; McClain, C. R. (Editor); Pegau, S.; Zanefeld, J. R. V.; Mitchell, B. G.; Kahru, M.; Wieland, J.; Stramska, M.

    2003-01-01

    This document stipulates protocols for measuring bio-optical and radiometric data for the Sensor Intercomparision and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project activities and algorithm development. The document is organized into 6 separate volumes as Ocean Optics Protocols for Satellite Ocean Color Sensor Validation, Revision 4. Volume I: Introduction, Background, and Conventions; Volume II: Instrument Specifications, Characterization and Calibration; Volume III: Radiometric Measurements and Data Analysis Methods; Volume IV: Inherent Optical Properties: Instruments, Characterization, Field Measurements and Data Analysis Protocols; Volume V: Biogeochemical and Bio-Optical Measurements and Data Analysis Methods; Volume VI: Special Topics in Ocean Optics Protocols and Appendices. The earlier version of Ocean Optics Protocols for Satellite Ocean Color Sensor Validation, Revision 3 is entirely superseded by the six volumes of Revision 4 listed above.

  13. MIPAS database: new HNO3 line parameters at 7.6 μm validated with MIPAS satellite measurements

    Directory of Open Access Journals (Sweden)

    A. Perrin

    2015-11-01

    Full Text Available Improved line positions and intensities have been generated for the 7.6 μm spectral region of nitric acid. They were obtained relying on a recent reinvestigation of the nitric acid band system at 7.6 μm and comparisons of HNO3 volume mixing ratio profiles retrieved from the "Michelson Interferometer for Passive Atmospheric Sounding" (MIPAS limb emission radiances in the 11 and 7.6 μm domains. This has led to an improved database called "MIPAS-2015". Comparisons with available laboratory information (individual line intensities, integrated absorption cross sections, and absorption cross sections show that MIPAS-2015 provides an improved description of the 7.6 μm region of nitric acid. This study should help to improve HNO3 satellite retrievals by allowing measurements to be performed simultaneously in the 11 and 7.6 μm micro-windows. In particular, it should be useful to analyze existing MIPAS and IASI spectra as well as spectra to be recorded by the forthcoming "Infrared Atmospheric Sounding Interferometer – New Generation" (IASI-NG instrument.

  14. Fine-scale features on the sea surface in SAR satellite imagery – Part 1: Simultaneous in-situ measurements

    Directory of Open Access Journals (Sweden)

    S. Brusch

    2012-09-01

    Full Text Available This work is aimed at identifying the origin of fine-scale features on the sea surface in synthetic aperture radar (SAR imagery with the help of in-situ measurements as well as numerical models (presented in a companion paper. We are interested in natural and artificial features starting from the horizontal scale of the upper ocean mixed layer, around 30–50 m. These features are often associated with three-dimensional upper ocean dynamics. We have conducted a number of studies involving in-situ observations in the Straits of Florida during SAR satellite overpass. The data include examples of sharp frontal interfaces, wakes of surface ships, internal wave signatures, as well as slicks of artificial and natural origin. Atmospheric processes, such as squall lines and rain cells, produced prominent signatures on the sea surface. This data has allowed us to test an approach for distinguishing between natural and artificial features and atmospheric influences in SAR images that is based on a co-polarized phase difference filter.

  15. Enhancement in electron and ion temperatures due to solar flares as measured by SROSS-C2 satellite

    Directory of Open Access Journals (Sweden)

    D. K. Sharma

    2004-06-01

    Full Text Available The observations on the ionospheric electron and ion temperatures (Te and Ti measured by the RPA payload aboard the SROSS-C2 satellite have been used to study the effect of solar flares on ionospheric heating. The data on solar flare has been obtained from the National Geophysical Data Center (NGDC Boulder, Colorado (USA. It has been found that the electron and ion temperatures have a consistent enhancement during the solar flares on the dayside Earth's ionosphere. The estimated enhancement for the average electron temperature is from 1.3 to 1.9 times whereas for ion temperature it is from 1.2 to 1.4 times to the normal days average temperature. The enhancement of ionospheric temperatures due to solar flares is correlated with the diurnal variation of normal days' ionospheric temperatures. The solar flare does not have any significant effect on the nightside ionosphere. A comparison with the temperature obtained from the IRI-95 model also shows a similar enhancement.

  16. Method of measuring sea surface water temperature with a satellite including wideband passive synthetic-aperture multichannel receiver

    Science.gov (United States)

    Stacey, J. M. (Inventor)

    1985-01-01

    A wideband passive synthetic-aperture multichannel receiver with an antenna is mounted on a satellite which travels in an orbit above the Earth passing over large bodies of water, e.g., the Atlantic Ocean. The antenna is scanned to receive signals over a wide frequency band from each incremental surface area (pixel) of the water which are related to the pixel's sea temperature. The received signals are fed to several channels which are tuned to separate selected frequencies. Their outputs are fed to a processor with a memory for storage. As the antenna points to pixels within a calibration area around a buoy of known coordinates, signals are likewise received and stored. Exactly measured sea temperature is received from the buoy. After passing over several calibration areas, a forward stepwise regression analysis is performed to produce an expression which selects the significant from the insignificant channels and assigns weights (coefficients) to them. The expression is used to determine the sea temperature at each pixel based on the signals received therefrom. Wind temperature, pressure, and wind speed at each pixel can also be calculated.

  17. Assessing net ecosystem carbon exchange of U S terrestrial ecosystems by integrating eddy covariance flux measurements and satellite observations

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Qianlai [Purdue University; Law, Beverly E. [Oregon State University; Baldocchi, Dennis [University of California, Berkeley; Ma, Siyan [University of California, Berkeley; Chen, Jiquan [University of Toledo, Toledo, OH; Richardson, Andrew [Harvard University; Melillo, Jerry [Marine Biological Laboratory; Davis, Ken J. [Pennsylvania State University; Hollinger, D. [USDA Forest Service; Wharton, Sonia [University of California, Davis; Falk, Matthias [University of California, Davis; Paw, U. Kyaw Tha [University of California, Davis; Oren, Ram [Duke University; Katulk, Gabriel G. [Duke University; Noormets, Asko [North Carolina State University; Fischer, Marc [Lawrence Berkeley National Laboratory (LBNL); Verma, Shashi [University of Nebraska; Suyker, A. E. [University of Nebraska, Lincoln; Cook, David R. [Argonne National Laboratory (ANL); Sun, G. [USDA Forest Service; McNulty, Steven G. [USDA Forest Service; Wofsy, Steve [Harvard University; Bolstad, Paul V [University of Minnesota; Burns, Sean [University of Colorado, Boulder; Monson, Russell K. [University of Colorado, Boulder; Curtis, Peter [Ohio State University, The, Columbus; Drake, Bert G. [Smithsonian Environmental Research Center, Edgewater, MD; Foster, David R. [Harvard University; Gu, Lianhong [ORNL; Hadley, Julian L. [Harvard University; Litvak, Marcy [University of New Mexico, Albuquerque; Martin, Timothy A. [University of Florida, Gainesville; Matamala, Roser [Argonne National Laboratory (ANL); Meyers, Tilden [NOAA, Oak Ridge, TN; Oechel, Walter C. [San Diego State University; Schmid, H. P. [Indiana University; Scott, Russell L. [USDA ARS; Torn, Margaret S. [Lawrence Berkeley National Laboratory (LBNL)

    2011-01-01

    More accurate projections of future carbon dioxide concentrations in the atmosphere and associated climate change depend on improved scientific understanding of the terrestrial carbon cycle. Despite the consensus that U.S. terrestrial ecosystems provide a carbon sink, the size, distribution, and interannual variability of this sink remain uncertain. Here we report a terrestrial carbon sink in the conterminous U.S. at 0.63 pg C yr 1 with the majority of the sink in regions dominated by evergreen and deciduous forests and savannas. This estimate is based on our continuous estimates of net ecosystem carbon exchange (NEE) with high spatial (1 km) and temporal (8-day) resolutions derived from NEE measurements from eddy covariance flux towers and wall-to-wall satellite observations from Moderate Resolution Imaging Spectroradiometer (MODIS). We find that the U.S. terrestrial ecosystems could offset a maximum of 40% of the fossil-fuel carbon emissions. Our results show that the U.S. terrestrial carbon sink varied between 0.51 and 0.70 pg C yr 1 over the period 2001 2006. The dominant sources of interannual variation of the carbon sink included extreme climate events and disturbances. Droughts in 2002 and 2006 reduced the U.S. carbon sink by 20% relative to a normal year. Disturbances including wildfires and hurricanes reduced carbon uptake or resulted in carbon release at regional scales. Our results provide an alternative, independent, and novel constraint to the U.S. terrestrial carbon sink.

  18. MIPAS database: new HNO3 line parameters at 7.6  µm validated with MIPAS satellite measurements

    Science.gov (United States)

    Perrin, Agnès; Flaud, Jean-Marie; Ridolfi, Marco; Vander Auwera, Jean; Carlotti, Massimo

    2016-05-01

    Improved line positions and intensities have been generated for the 7.6 µm spectral region of nitric acid. They were obtained relying on a recent reinvestigation of the nitric acid band system at 7.6 µm and comparisons of HNO3 volume mixing ratio profiles retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) limb emission radiances in the 11 and 7.6 µm domains. This has led to an improved database called MIPAS-2015. Comparisons with available laboratory information (individual line intensities, integrated absorption cross sections, and absorption cross sections) show that MIPAS-2015 provides an improved description of the 7.6 µm region of nitric acid. This study should help to improve HNO3 satellite retrievals by allowing measurements to be performed simultaneously in the 11 and 7.6 µm micro-windows. In particular, it should be useful to analyze existing MIPAS and IASI spectra as well as spectra to be recorded by the forthcoming Infrared Atmospheric Sounding Interferometer - New Generation (IASI-NG) instrument.

  19. Global Electric Circuit Implications of Combined Aircraft Storm Electric Current Measurements and Satellite-Based Diurnal Lightning Statistics

    Science.gov (United States)

    Mach, Douglas M.; Blakeslee, Richard J.; Bateman, Monte G.

    2011-01-01

    Using rotating vane electric field mills and Gerdien capacitors, we measured the electric field profile and conductivity during 850 overflights of thunderstorms and electrified shower clouds (ESCs) spanning regions including the Southeastern United States, the Western Atlantic Ocean, the Gulf of Mexico, Central America and adjacent oceans, Central Brazil, and the South Pacific. The overflights include storms over land and ocean, and with positive and negative fields above the storms. Over three-quarters (78%) of the land storms had detectable lightning, while less than half (43%) of the oceanic storms had lightning. Integrating our electric field and conductivity data, we determined total conduction currents and flash rates for each overpass. With knowledge of the storm location (land or ocean) and type (with or without lightning), we determine the mean currents by location and type. The mean current for ocean thunderstorms is 1.7 A while the mean current for land thunderstorms is 1.0 A. The mean current for ocean ESCs 0.41 A and the mean current for land ESCs is 0.13 A. We did not find any significant regional or latitudinal based patterns in our total conduction currents. By combining the aircraft derived storm currents and flash rates with diurnal flash rate statistics derived from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) low Earth orbiting satellites, we reproduce the diurnal variation in the global electric circuit (i.e., the Carnegie curve) to within 4% for all but two short periods of time. The agreement with the Carnegie curve was obtained without any tuning or adjustment of the satellite or aircraft data. Given our data and assumptions, mean contributions to the global electric circuit are 1.1 kA (land) and 0.7 kA (ocean) from thunderstorms, and 0.22 kA (ocean) and 0.04 (land) from ESCs, resulting in a mean total conduction current estimate for the global electric circuit of 2.0 kA. Mean storm counts are 1100 for land

  20. Origin of energetic ions in the polar cusp inferred from ion composition measurements by the Viking satellite

    Directory of Open Access Journals (Sweden)

    G. Kremser

    Full Text Available The magnetospheric ion composition spectrometer MICS on the Swedish Viking satellite provided measurements of the ion composition in the energy range 10.1 keV/eleqE/Qleq326.0 keV/e. Data obtained during orbit 842 were used to investigate the ion distribution in the northern polar cusp and its vicinity. The satellite traversed the outer ring current, boundary region, cusp proper and plasma mantle during its poleward movement. H+ and He++ ions were encountered in all of these regions. He+ ions were present only in the ring current. The number of O+ and O++ ions was very small. Heavy high-charge state ions typical for the solar wind were observed for the first time, most of them in the poleward part of the boundary region and in the cusp proper. The H+ ions exhibited two periods with high intensities. One of them, called the BR/CP event, appeared at energies up to 50 keV. It started at the equatorward limit of the boundary region and continued into the cusp proper. Energy spectra indicate a ring current origin for the BR/CP event. Pitch angle distributions show downward streaming of H+ ions at its equatorward limit and upward streaming on the poleward side. This event is interpreted as the result of pitch angle scattering of ring current ions by fluctuations in the magnetopause current layer in combination with poleward convection. The other of the two periods with high H+ ion intensities, called the accelerated ion event, was superimposed on the BR/CP event. It was restricted to energies leq15 keV and occurred in the poleward part of the boundary region. This event is regarded as the high-energy tail of magnetosheath ions that were accelerated while penetrating into the magnetosphere. The cusp region thus contains ions of magnetospheric as well as of magnetosheath origin. The appearance of the ions depends, in addition to the ion source, on the