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Bernard Pinty - One of the best experts on this subject based on the ideXlab platform.

  • generating global surface albedo products from multiple Geostationary Satellites
    Remote Sensing of Environment, 2008
    Co-Authors: Yves Govaerts, Alessio Lattanzio, Malcolm Taberner, Bernard Pinty
    Abstract:

    Operational weather Geostationary Satellites have acquired data for more than two decades and offer thus the possibility to generate long time series of Essential Climate Variables like surface albedo as suggested by GCOS. This paper investigates the possibility to generate consistent global, to the exception of the polar regions, surface broadband albedo product from these Satellites. In this context, the paper addresses two specific issues. Firstly, the spatial consistency of surface albedo derived from five different Geostationary Satellites is examined in detail. Secondly, this product is compared with the equivalent MODIS one to define the temporal consistency between surface albedo derived with old Geostationary instruments and technologically advanced radiometers like MODIS. The analysis of the surface albedo products has revealed a good agreement between the products derived from the various Geostationary Satellites. Comparison of this global product with the one routinely derived from MODIS shows that on the average, the mean relative difference between these two data sets agree within 10%. These first encouraging results open therefore a new avenue for the exploitation of the archived data for the generation of long time series, covering the last 25 years or so, of global surface albedo from Geostationary weather Satellites.

  • Generating Global Surface Albedo Products from Multiple Geostationary Satellites
    Remote Sensing of Environment, 2008
    Co-Authors: Yves Govaerts, Alessio Lattanzio, Malcolm Taberner, Bernard Pinty
    Abstract:

    Operational weather Geostationary Satellites have acquired data for more than two decades and offers thus the possibility to generate long time series of essential climate variables like surface albedo as suggested by GCOS. This paper investigates the possibility to generate a consistent global surface broadband albedo map from these Satellites. In this context, the paper addresses two specific issues. Firstly, the spatial consistency of surface albedo derived from five different Geostationary Satellites is examined in details. Secondly, this product has been compared with the equivalent MODIS one to define the temporal consistency between surface albedo derived with old Geostationary instrument and technologically advanced instrument like MODIS.JRC.H.3-Global environement monitorin

  • Consistent surface albedo retrieval from two adjacent Geostationary Satellites
    Geophysical Research Letters, 2004
    Co-Authors: Yves Govaerts, Alessio Lattanzio, Bernard Pinty, Johannes Schmetz
    Abstract:

    [1] Monitoring and understanding climate changes of the Earth require the generation of long-term and consistent global data set from observations. In this context, Geostationary satellite observations could play a significant role thanks to the long duration of the missions and the corresponding archives. In particular, their frequent acquisition cycle throughout the day can be used to document the surface anisotropy and therefore surface albedo. This paper investigates the possibility to generate a consistent surface albedo maps from two adjacent Geostationary Satellites, namely Meteosat-5 and -7. The analysis relies on the comparison of albedo values derived over the common observed area. These values agree favorably between the two spacecrafts.

Yves Govaerts - One of the best experts on this subject based on the ideXlab platform.

  • generating global surface albedo products from multiple Geostationary Satellites
    Remote Sensing of Environment, 2008
    Co-Authors: Yves Govaerts, Alessio Lattanzio, Malcolm Taberner, Bernard Pinty
    Abstract:

    Operational weather Geostationary Satellites have acquired data for more than two decades and offer thus the possibility to generate long time series of Essential Climate Variables like surface albedo as suggested by GCOS. This paper investigates the possibility to generate consistent global, to the exception of the polar regions, surface broadband albedo product from these Satellites. In this context, the paper addresses two specific issues. Firstly, the spatial consistency of surface albedo derived from five different Geostationary Satellites is examined in detail. Secondly, this product is compared with the equivalent MODIS one to define the temporal consistency between surface albedo derived with old Geostationary instruments and technologically advanced radiometers like MODIS. The analysis of the surface albedo products has revealed a good agreement between the products derived from the various Geostationary Satellites. Comparison of this global product with the one routinely derived from MODIS shows that on the average, the mean relative difference between these two data sets agree within 10%. These first encouraging results open therefore a new avenue for the exploitation of the archived data for the generation of long time series, covering the last 25 years or so, of global surface albedo from Geostationary weather Satellites.

  • Generating Global Surface Albedo Products from Multiple Geostationary Satellites
    Remote Sensing of Environment, 2008
    Co-Authors: Yves Govaerts, Alessio Lattanzio, Malcolm Taberner, Bernard Pinty
    Abstract:

    Operational weather Geostationary Satellites have acquired data for more than two decades and offers thus the possibility to generate long time series of essential climate variables like surface albedo as suggested by GCOS. This paper investigates the possibility to generate a consistent global surface broadband albedo map from these Satellites. In this context, the paper addresses two specific issues. Firstly, the spatial consistency of surface albedo derived from five different Geostationary Satellites is examined in details. Secondly, this product has been compared with the equivalent MODIS one to define the temporal consistency between surface albedo derived with old Geostationary instrument and technologically advanced instrument like MODIS.JRC.H.3-Global environement monitorin

  • Consistent surface albedo retrieval from two adjacent Geostationary Satellites
    Geophysical Research Letters, 2004
    Co-Authors: Yves Govaerts, Alessio Lattanzio, Bernard Pinty, Johannes Schmetz
    Abstract:

    [1] Monitoring and understanding climate changes of the Earth require the generation of long-term and consistent global data set from observations. In this context, Geostationary satellite observations could play a significant role thanks to the long duration of the missions and the corresponding archives. In particular, their frequent acquisition cycle throughout the day can be used to document the surface anisotropy and therefore surface albedo. This paper investigates the possibility to generate a consistent surface albedo maps from two adjacent Geostationary Satellites, namely Meteosat-5 and -7. The analysis relies on the comparison of albedo values derived over the common observed area. These values agree favorably between the two spacecrafts.

Alessio Lattanzio - One of the best experts on this subject based on the ideXlab platform.

  • generating global surface albedo products from multiple Geostationary Satellites
    Remote Sensing of Environment, 2008
    Co-Authors: Yves Govaerts, Alessio Lattanzio, Malcolm Taberner, Bernard Pinty
    Abstract:

    Operational weather Geostationary Satellites have acquired data for more than two decades and offer thus the possibility to generate long time series of Essential Climate Variables like surface albedo as suggested by GCOS. This paper investigates the possibility to generate consistent global, to the exception of the polar regions, surface broadband albedo product from these Satellites. In this context, the paper addresses two specific issues. Firstly, the spatial consistency of surface albedo derived from five different Geostationary Satellites is examined in detail. Secondly, this product is compared with the equivalent MODIS one to define the temporal consistency between surface albedo derived with old Geostationary instruments and technologically advanced radiometers like MODIS. The analysis of the surface albedo products has revealed a good agreement between the products derived from the various Geostationary Satellites. Comparison of this global product with the one routinely derived from MODIS shows that on the average, the mean relative difference between these two data sets agree within 10%. These first encouraging results open therefore a new avenue for the exploitation of the archived data for the generation of long time series, covering the last 25 years or so, of global surface albedo from Geostationary weather Satellites.

  • Generating Global Surface Albedo Products from Multiple Geostationary Satellites
    Remote Sensing of Environment, 2008
    Co-Authors: Yves Govaerts, Alessio Lattanzio, Malcolm Taberner, Bernard Pinty
    Abstract:

    Operational weather Geostationary Satellites have acquired data for more than two decades and offers thus the possibility to generate long time series of essential climate variables like surface albedo as suggested by GCOS. This paper investigates the possibility to generate a consistent global surface broadband albedo map from these Satellites. In this context, the paper addresses two specific issues. Firstly, the spatial consistency of surface albedo derived from five different Geostationary Satellites is examined in details. Secondly, this product has been compared with the equivalent MODIS one to define the temporal consistency between surface albedo derived with old Geostationary instrument and technologically advanced instrument like MODIS.JRC.H.3-Global environement monitorin

  • Retrieval of a global consistent land surface albedo from Geostationary Satellites
    2006
    Co-Authors: Alessio Lattanzio
    Abstract:

    Recently, the Global Climate Observing System (GCOS) committee recognized the need for establishing a benchmark for assessing land-surface albedo products and implementing a system for the retrieval of surface albedo from existing and archived Geostationary Satellites to form a global climatology of albedo for the entire period of available measurements. The effort currently undertaken at EUMETSAT to fulfil the second part of this recommendation will be presented, i.e., the possibility to derive spatially consistent datasets of broadband land surface albedo from different Geostationary Satellites. For this purpose 10 days of data acquired by GOES-10, GOES-8 and GMS-5 Meteosat-5 and Meteosat-7 have been calibrated and processed to derive surface albedos. The result of processing data acquired by this ensemble has been the generation of the first near global map of surface albedo derived from Geostationary spacecrafts.

  • Consistent surface albedo retrieval from two adjacent Geostationary Satellites
    Geophysical Research Letters, 2004
    Co-Authors: Yves Govaerts, Alessio Lattanzio, Bernard Pinty, Johannes Schmetz
    Abstract:

    [1] Monitoring and understanding climate changes of the Earth require the generation of long-term and consistent global data set from observations. In this context, Geostationary satellite observations could play a significant role thanks to the long duration of the missions and the corresponding archives. In particular, their frequent acquisition cycle throughout the day can be used to document the surface anisotropy and therefore surface albedo. This paper investigates the possibility to generate a consistent surface albedo maps from two adjacent Geostationary Satellites, namely Meteosat-5 and -7. The analysis relies on the comparison of albedo values derived over the common observed area. These values agree favorably between the two spacecrafts.

Mitchell D Goldberg - One of the best experts on this subject based on the ideXlab platform.

  • determining diurnal variations of land surface emissivity from Geostationary Satellites
    Journal of Geophysical Research, 2012
    Co-Authors: Yong Zhang, Mitchell D Goldberg, Timothy J Schmit, Lihang Zhou, Paul W Menzel
    Abstract:

    [1] Infrared (IR) land surface emissivity (LSE) with a high temporal and spatial resolution is very important for deriving other products using IR radiance measurements as well as assimilating IR radiances in numerical weather prediction (NWP) models over land. Retrieved from various satellite instruments, many LSE databases are available for operational and research use. Most are updated only monthly; assuming emissivity does not change within the month. However, laboratory measurements have shown that emissivity increases by 1.7% to 16% when soil moisture content becomes higher, especially in sandy soils in the 8.2–9.2 μm range. And a clearly defined wave-like diurnal pattern of decreasing surface soil moisture during the day and recovery (or increased soil moisture) at night was observed. Therefore, it is expected that LSE possesses a diurnal wave-pattern variation with low values during day time and high values during nighttime. The physically based GOES-R ABI LSE algorithm uniquely exploits the Geostationary Satellites' high temporal resolution. The algorithm was developed and applied to the radiance measurements from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) on the Meteosat Second Generation (MSG) Meteosat-8/9. The results over the Sahara Desert show that 8.7μm emissivity has a significant diurnal wave-pattern variation, with high values during nighttime and low values during day time. 10.8μm emissivity also shows a similar diurnal variation, but with a smaller amplitude compared to 8.7 μm. 12.0 μm emissivity has an even weaker diurnal variation, and an opposite pattern as 8.7 and 10.8 μm. Evidence is provided to demonstrate that the SEVIRI LSE diurnal wave-pattern variations are real, not artifacts from the retrieval algorithm. The impacts of diurnal variations of errors in GFS forecast (temperature and moisture profiles) and in land surface temperature (LST) are analyzed; they are found to be minor compared to the LSE diurnal variations shown by SEVIRI.

  • diurnal seasonal and weather related variations of land surface temperature observed from Geostationary Satellites
    Geophysical Research Letters, 2008
    Co-Authors: Konstantin Y Vinnikov, M Rama Varma K Raja, Dan Tarpley, Mitchell D Goldberg
    Abstract:

    [1] The time series of clear-sky Land Surface Temperatures (LST) for one year, 2001, obtained from pyrgeometric observations at five selected US surface radiation (SURFRAD) stations and independently retrieved for the locations of these stations from Infrared Imager hourly observations of two Geostationary Satellites, GOES-8 and GOES-10, are presented as a sum of time-dependent expected value (diurnal and seasonal cycles), and weather-related anomalies. The availability of three independent observations is used to assess random and systematic errors in LST data. Temporal variation of the expected value is approximated as a superposition of the first two annual and diurnal Fourier harmonics. This component of temporal variations of LST absorbs all systematic errors; which themselves are often a subject of diurnal and seasonal variations. The results revealed that the weather-related temporal variation of LST is much smaller than the temporal variations of the expected value, but much larger than the random errors of observation. Scale of temporal autocorrelation of weather-related component of clear-sky LST variations is about 3 days.

  • remote sensing of aerosol and radiation from Geostationary Satellites
    Advances in Space Research, 2008
    Co-Authors: Istvan Laszlo, Dan Tarpley, Shobha Kondragunta, Pubu Ciren, H Liu, Mitchell D Goldberg
    Abstract:

    Abstract The paper presents a high-level overview of current and future remote sensing of aerosol and shortwave radiation budget carried out at the US National Oceanic and Atmospheric Administration (NOAA) from the US Geostationary Operational Environmental Satellite (GOES) series. The retrievals from the current GOES imagers are based on physical principles. Aerosol and radiation are estimated in separate processing from the comparison of satellite-observed reflectances derived from a single visible channel with those calculated from detailed radiative transfer. The radiative transfer calculation accounts for multiple scattering by molecules, aerosol and cloud and absorption by the major atmospheric gases. The retrievals are performed operationally every 30 min for aerosol and every hour for radiation for pixel sizes of 4-km (aerosol) and 15- to 50-km (radiation). Both retrievals estimate the surface reflectance as a byproduct from the time composite of clear visible reflectances assuming fixed values of the aerosol optical depth. With the launch of GOES-R NOAA will begin a new era of Geostationary remote sensing. The Advanced Baseline Imager (ABI) onboard GOES-R will offer capabilities for aerosol remote sensing similar to those currently provided by the Moderate Resolution Imaging Spectroradiometer (MODIS) flown on the NASA Earth Observing System (EOS) Satellites. The ABI aerosol algorithm currently under development uses a multi-channel approach to estimate the aerosol optical depth and aerosol model simultaneously, both over water and land. Its design is strongly inspired by the MODIS aerosol algorithm. The ABI shortwave radiation budget algorithm is based on the successful GOES Surface and Insolation Product system of NOAA and the NASA Clouds and the Earth’s Radiant Energy System (CERES), Surface and Atmospheric Radiation Budget (SARB) algorithm. In all phases of the development, the algorithms are tested with proxy data generated from existing satellite observations and forward simulations. Final assessment of the performance will be made after the launch of GOES-R scheduled in 2012.

Damiana Losa - One of the best experts on this subject based on the ideXlab platform.

  • High vs Low Thrust Station Keeping Maneuver Planning for Geostationary Satellites
    2007
    Co-Authors: Damiana Losa
    Abstract:

    Our thesis work focuses on the problem of station keeping maneuver planning for Geostationary Satellites equipped with thrusters at low thrust level. We evaluate the opportunity of substituting such a planning to the more traditional one used for Geostationary Satellites equipped with thrusters at high thrust. Since the birth of low thrust technology, its use has always met with the spacecraft companies approval. The well-known advantage of low fuel consumption due to the high specific impulse achieved by the high values of specific impulsion makes this technology highly competitive with respect to the high trust level one, especially during transfer and rendez vous phases of space missions. The trajectory optimization problems which have to be solved during the mission design in order to analyze the feasibility of transfer and rendez vous mission phases have begun to be solved with alternative optimization solutions, since the low thrust propulsion systems have to be activated for longer periods of the transfer time. High thrust trajectory optimization problems, typically formulated as discrete, have been replaced with low thrust trajectory optimization problems formulated as continuous and solved by continuous control techniques. The goal of this thesis is to understand what is the impact of the low thrust propulsion technology on the station keeping phase feasibility analysis performed during the design of a Geostationary mission. In particular we study the impact that the low thrust propulsion systems have on the station keeping maneuver planning and on the realization of the whole station keeping control loop. The goal is to deduce whether the maneuver planning related with this technology is competitive with respect to the more classical one based on high thrust level. Usually the well known long term strategies for the SK maneuver are deduced from simplified propagation orbit models (in function of mean orbital elements) mainly because the following three conditions are met: high thrust level propulsions, SK dead band box sizes not very stringent and the possibility to execute low frequency maneuvers. In the framework of this dissertation, given the low thrust level propulsion and increasingly stringent dead band requirements, we think it is more appropriate to make the hypothesis of a much higher maneuver execution frequency in order to achieve a finer control of the GEO satellite position and to use an orbit propagation model described by the motion equations in terms of osculating elements. For the maneuver planning we propose a solution based on a direct approach considered as the transcription in terms of parameter optimization problem of the constrained optimal control problem associated to the planning task. Two optimization techniques have been considered: the fixed horizon optimization under constraints and the receding horizon one. This second is also used with the linearized motion equations appropriately transformed via a Lyapunov variable change on the state space of the osculating equinoctial element deviations. This Lyapunov transformation leads to the definition of a new set of orbital parameters. It makes the planning process more immediately understandable from a control viewpoint and easier to implement from a numerical viewpoint, thanks to the differential flatness and inclusion concepts. All the low thrust maneuver planning results are obtained in a first time in terms of thrust velocity increments and in a second time directly in terms of thrust, considering typical propulsion system configurations with the goal of determining the more efficient one in nominal conditions and in the condition of failure of one of the thrusters. The problem of collocation of more Geostationary Satellites in a same big box has not been explicitly addressed but is implicitly solved once the fine control technique with a relative stringent dead band requirement is proposed for each satellite.

  • Station keeping of Geostationary Satellites with on-off electric thrusters
    2006
    Co-Authors: Damiana Losa, Marco Lovera, Thierry Dargent, Jean-paul Marmorat, Joël Amalric
    Abstract:

    The aim of this paper is to consider the modelling and control issues arising in the design of a station keeping system for Geostationary Satellites based on on-off electric thrusters. In particular, a model for the dynamics of a Geostationary satellite affected by perturbations is derived and the electric station keeping problem is then formulated as an optimisation problem with mixed (continuous and discrete) constraints. Simulation results showing the feasibility of the control task on a spacecraft equipped with electric thrusters are also presented and discussed.

  • Station keeping of Geostationary Satellites with on-off electric thrusters
    2006 IEEE Conference on Computer Aided Control System Design 2006 IEEE International Conference on Control Applications 2006 IEEE International Sympos, 2006
    Co-Authors: Damiana Losa, Marco Lovera, Thierry Dargent, Jean-paul Marmorat, Joël Amalric
    Abstract:

    International audienceThe aim of this paper is to consider the modelling and control issues arising in the design of a station keeping system for Geostationary Satellites based on on-off electric thrusters. In particular, a model for the dynamics of a Geostationary satellite affected by perturbations is derived and the electric station keeping problem is then formulated as an optimisation problem with mixed (continuous and discrete) constraints. Simulation results showing the feasibility of the control task on a spacecraft equipped with electric thrusters are also presented and discussed

  • Electric Station Keeping of Geostationary Satellites: a Differential Inclusion Approach
    2005
    Co-Authors: Damiana Losa, Marco Lovera, Rémi Drai, Thierry Dargent, Joël Amalric
    Abstract:

    The aim of this paper is to consider the modelling and control issues arising in the design of a station keeping system for Geostationary Satellites based on electric propulsion. In particular, a linear time-varying model for the dynamics of a Geostationary satellite affected by perturbations is derived and the longitude and latitude station keeping problem is then formulated as a constrained linear quadratic optimal control problem. A direct method based on the so-called differential inclusion approach is then proposed. Simulation results showing the feasibility of the control task on a spacecraft equipped with electric thrusters are also presented and discussed.

  • Electric Station Keeping of Geostationary Satellites: a Differential Inclusion Approach
    Proceedings of the 44th IEEE Conference on Decision and Control, 1
    Co-Authors: Damiana Losa, Marco Lovera, Rémi Drai, Thierry Dargent, Joël Amalric
    Abstract:

    International audienceThe aim of this paper is to consider the modelling and control issues arising in the design of a station keeping system for Geostationary Satellites based on electric propulsion. In particular, a linear time-varying model for the dynamics of a Geostationary satellite affected by perturbations is derived and the longitude and latitude station keeping problem is then formulated as a constrained linear quadratic optimal control problem. A direct method based on the so-called differential inclusion approach is then proposed. Simulation results showing the feasibility of the control task on a spacecraft equipped with electric thrusters are also presented and discussed