Integration of optical and Synthetic Aperture Radar (SAR) imagery for delivering operational annual crop inventories     

Heather McNairn  Catherine Champagne  Jiali Shang  Delmar Holmstrom  Gordon Reichert 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(5):434-449

Agriculture plays a critical role within Canada’s economy and, as such, sustainability of this sector is of high importance. Targeting and monitoring programs designed to promote economic and environmental sustainability are a vital component within Canada’s agricultural policy. A hierarchy of land information, including up to date information on cropping practices, is needed to measure the impacts of programs on land use decision-making and to gauge the environmental and economic benefits of these investments. A multi-year, multi-site research activity was completed to develop a robust methodology to inventory crops across Canada’s large and diverse agricultural landscapes. To move towards operational implementation the methodology must deliver accurate crop inventories, with consistency and reliability. In order to meet these operational requirements and to mitigate risk associated with reliance on a single data source, the methodology integrated both optical and Synthetic Aperture Radar (SAR) imagery. The results clearly demonstrated that multi-temporal satellite data can successfully classify crops for a variety of cropping systems present across Canada. Overall accuracies of at least 85% were achieved, and most major crops were also classified to this level of accuracy. Although multi-temporal optical data would be the preferred data source for crop classification, a SAR-optical dataset (two Envisat ASAR images and one optical image) provided acceptable accuracies and will mitigate risk associated with operational implementation. The preferred dual-polarization mode would be VV–VH. Not only were these promising classification results repeated year after year, but the target accuracies were met consistently for multiple sites across Canada, all with varying cropping systems.  相似文献   

Statistical analysis of the observations of the MEX/ASPERA-3 NPI in the shadow     

A. Milillo  A. Mura  S. Orsini  S. Massetti  P.C. son Brandt  T. Sotirelis  R. D’Amicis  S. Barabash  R.A. Frahm  E. Kallio  A. Galli  P. Wurz  M. Holmstrom  E.C. Roelof  J.D. Winningham  P. Cerulli-Irelli  S. Livi  R. Lundin  M. Maggi  A. Morbidini 《Planetary and Space Science》2009,57(8-9):1000-1007

The analyser of space plasma and energetic atoms (ASPERA-3) neutral particle imager (NPI) on board Mars Express (MEX) is devoted to energetic neutral atom (ENA) detection within the Martian environment. These ENAs originate from the interaction between the energetic ions flowing inside the Martian environment and the exospheric neutral gas, thus providing crucial information about the dynamics of this interaction. NPI records the instantaneous angular distribution of the energy-integrated ENA signal. In order to identify recurrent ENA signals in the Martian environment, we have performed a statistical analysis of the NPI data. Count rates have been averaged using different methods in order to be able to discriminate signals coming from the planet, from a selected direction, or from specific planetographic regions at the planetary surface. Possible recurrent ENA signals (about 5×10⁶ (cm² sr s)^?1) are found coming from the terminator direction and above the atmosphere toward nightside when the spacecraft was inside the planetary shadow, mainly close to the shadow edge. Some significant signal was found from the anti-Mars directions in 2005. No statistically significant signal related to pick-up ions from the atmosphere or related to magnetic anomalies above the sensor intrinsic error (estimated as 3×10⁶ (cm² sr s)^?1) was observed. Our analysis shows that particular attention should be given to the use of NPI data when performing statistical studies; in fact, the sensor has some intrinsic limitations due to inadequate UV suppression, difficulties in sector inter-calibrations, and variations in the sector response versus time.  相似文献   

Scientific rationale for the D-CIXS X-ray spectrometer on board ESA's SMART-1 mission to the Moon     

S.K Dunkin  M GrandeI Casanova  V FernandesD.J Heather  B KellettK Muinonen  S.S RussellR Browning  N WalthamD Parker  B KentC.H Perry  B SwinyardA Perry  J FeradayC Howe  K PhillipsG McBride  J HuovelinP Muhli  P.J HakalaO Vilhu  N ThomasD Hughes  H AlleyneM Grady  R LundinS Barabash  D BakerP.E Clark  C.D MurrayJ Guest  L.C d'UstonS Maurice  B FoingA Christou  C OwenP Charles  J LaukkanenH Koskinen  M KatoK Sipila  S NenonenM Holmstrom  N BhandariR Elphic  D Lawrence 《Planetary and Space Science》2003,51(6):435-442

The D-CIXS X-ray spectrometer on ESA's SMART-1 mission will provide the first global coverage of the lunar surface in X-rays, providing absolute measurements of elemental abundances. The instrument will be able to detect elemental Fe, Mg, Al and Si under normal solar conditions and several other elements during solar flare events. These data will allow for advances in several areas of lunar science, including an improved estimate of the bulk composition of the Moon, detailed observations of the lateral and vertical nature of the crust, chemical observations of the maria, investigations into the lunar regolith, and mapping of potential lunar resources. In combination with information to be obtained by the other instruments on SMART-1 and the data already provided by the Clementine and Lunar Prospector missions, this information will allow for a more detailed look at some of the fundamental questions that remain regarding the origin and evolution of the Moon.  相似文献   

Low energy neutral atom imaging on the Moon with the SARA instrument aboard Chandrayaan-1 mission     

Anil Bhardwaj  Stas Barabash  Yoshifumi Futaana  Yoichi Kazama  Kazushi Asamura  David McCann  R. Sridharan  Mats Holmstrom  Peter Wurz  Rickard Lundin 《Journal of Earth System Science》2005,114(6):749-760

This paper reports on the Sub-keV Atom Reflecting Analyzer (SARA) experiment that will be flown on the first Indian lunar mission Chandrayaan-1. The SARA is a low energy neutral atom (LENA) imaging mass spectrometer, which will perform remote sensing of the lunar surface via detection of neutral atoms in the energy range from 10 eV to 3 keV from a 100km polar orbit. In this report we present the basic design of the SARA experiment and discuss various scientific issues that will be addressed. The SARA instrument consists of three major subsystems: a LENA sensor (CENA), a solar wind monitor (SWIM), and a digital processing unit (DPU). SARA will be used to image the solar wind-surface interaction to study primarily the surface composition and surface magnetic anomalies and associated mini-magnetospheres. Studies of lunar exosphere sources and space weathering on the Moon will also be attempted. SARA is the first LENA imaging mass spectrometer of its kind to be flown on a space mission. A replica of SARA is planned to fly to Mercury onboard the BepiColombo mission.  相似文献