scholarly journals Global wave-driven beach evolution; consequences for observation strategies

2020 ◽  
Author(s):  
Erwin Bergsma ◽  
Rafael Almar ◽  
Thierry Garlan ◽  
Elodie Kestenare
Keyword(s):  
Observation Strategies

scholarly journals Data association and uncertainty pruning for tracks determined on short arcs

2020 ◽  
Vol 132 (1) ◽  
Author(s):  
Laura Pirovano ◽  
Gennaro Principe ◽  
Roberto Armellin
Keyword(s):  
Optimization Problems ◽  
Data Association ◽  
Earth Orbit ◽  
Orbital State ◽  
Geostationary Earth Orbit ◽  
Multiple Observations ◽  
Observation Strategies

AbstractWhen building a space catalogue, it is necessary to acquire multiple observations of the same object for the estimated state to be considered meaningful. A first concern is then to establish whether different sets of observations belong to the same object, which is the association problem. Due to illumination constraints and adopted observation strategies, small objects may be detected on short arcs, which contain little information about the curvature of the orbit. Thus, a single detection is usually of little value in determining the orbital state due to the very large associated uncertainty. In this work, we propose a method that both recognizes associated observations and sequentially reduces the solution uncertainty when two or more sets of observations are associated. The six-dimensional (6D) association problem is addressed as a cascade of 2D and 4D optimization problems. The performance of the algorithm is assessed using objects in geostationary Earth orbit, with observations spread over short arcs.

scholarly journals Observation Strategies Based on Singular Value Decomposition for Ocean Analysis and Forecast

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3445
Author(s):  
Maria Fattorini ◽  
Carlo Brandini
Keyword(s):  
Singular Value Decomposition ◽  
Maximum Error ◽  
Ocean Model ◽  
Singular Value ◽  
Practical Applications ◽  
Positioning Strategy ◽  
Value Decomposition ◽  
Observation Strategies

In this article, we discuss possible observing strategies for a simplified ocean model (Double Gyre (DG)), used as a preliminary tool to understand the observation needs for real analysis and forecasting systems. Observations are indeed fundamental to improve the quality of forecasts when data assimilation techniques are employed to obtain reliable analysis results. In addition, observation networks, particularly in situ observations, are expensive and require careful positioning of instruments. A possible strategy to locate observations is based on Singular Value Decomposition (SVD). SVD has many advantages when a variational assimilation method such as the 4D-Var is available, with its computation being dependent on the tangent linear and adjoint models. SVD is adopted as a method to identify areas where maximum error growth occurs and assimilating observations can give particular advantages. However, an SVD-based observation positioning strategy may not be optimal; thus, we introduce other criteria based on the correlation between points, as the information observed on neighboring locations can be redundant. These criteria are easily replicable in practical applications, as they require rather standard studies to obtain prior information.

scholarly journals Instrument observation strategy for a new generation of three-axis-stabilized geostationary meteorological satellites from China

2019 ◽  
Vol 8 (2) ◽  
pp. 161-175
Author(s):  
Jian Shang ◽  
Lei Yang ◽  
Pan Huang ◽  
Huizhi Yang ◽  
Chengbao Liu ◽  
...  
Keyword(s):  
Attitude Control ◽  
Mode Design ◽  
The Earth ◽  
Observation Strategy ◽  
Ground System ◽  
Image Navigation ◽  
Complicated Part ◽  
New Generation ◽  
Observation Strategies ◽  
Instrument Observation

Abstract. The Fengyun-4 (FY-4) satellite series is a new generation of geostationary meteorological satellites from China. The newly adopted three-axis-stabilized attitude-control platform can increase observation efficiency and flexibility while bringing great challenges for image navigation as well as integrated observation mode design. Considering the requirements of earth observation, navigation and calibration as well as observation flexibility, instrument observation strategies are proposed. These include the earth, the moon, stars, cold space, blackbody and diffuser observations on which the instruments' in-orbit daily observations must be based. The most complicated part is the star observation strategy, while navigation precision is dependent on in-orbit star observations. A flexible, effective, stable and automatic star observation strategy directly influences star data acquisition and navigation precision. According to the requirement of navigation, two specific star observation strategies for the two main instruments on board FY-4A were proposed to be used in the operational ground system. The strategies have been successfully used in FY-4A in-orbit tests for more than a year. Both the simulation results and in-orbit application results are given, including instrument observation strategies, star observation strategies and moon observation tasks, to demonstrate the validity of the proposed observation strategies, which lay important foundations for the instruments' daily operation.

Kinetic simulations of the Jovian ion circulation around Ganymede and space weather implications

2020 ◽  
Author(s):  
Christina Plainaki ◽  
Stefano Massetti ◽  
Xianzhe Jia ◽  
Alessandro Mura ◽  
Milillo Anna ◽  
...  
Keyword(s):  
Space Weather ◽  
Plasma Sheet ◽  
Preliminary Analysis ◽  
Surface Brightness ◽  
Radiation Environment ◽  
Direct Impact ◽  
The Moon ◽  
Polar Cap ◽  
Precipitation Patterns ◽  
Observation Strategies

<p>The exosphere of Jupiter’s moon Ganymede is the interface region linking the moon’s icy surface to Jupiter’s magnetospheric environment. Space weather phenomena driven by the variability of the radiation environment within the Jupiter system can have a direct impact on the sputtering-induced exosphere of Ganymede.</p><p>In this work we simulate the Jovian ion precipitation to Ganymede’s surface for different moon orbital phases around Jupiter. In particular, we consider three different configurations between Ganymede’s magnetic field and Jupiter plasma sheet, similar to those encountered during the Galileo G2, G8, and G28 flyby (i.e., the moon above, inside, below the Jupiter plasma sheet). We discuss the differences between the various ion precipitation patterns and the implications in the density distribution of the sputtered-water exosphere of this moon. We also comment the possible relation of these ion precipitation patterns with the surface brightness asymmetries both between Ganymede’s polar cap and equatorial regions and between the leading and trailing hemispheres. The results of this preliminary analysis are relevant to the JUICE mission and in particular to the preparation of the future observation strategies for the environment of Ganymede.</p>

The effect of learner's control of self-observation strategies on learning of front crawl

2016 ◽  
Vol 164 ◽  
pp. 151-156 ◽  
Author(s):  
Priscila Garcia Marques ◽  
Umberto Cesar Corrêa
Keyword(s):  
Front Crawl ◽  
Observation Strategies

scholarly journals First proof of concept of remote attendance for future observation strategies between Wettzell (Germany) and Concepcion (Chile)

2011 ◽  
Author(s):  
Martin Ettl ◽  
Alexander Neidhardt ◽  
Reiner Dassing ◽  
Hayo Hase ◽  
Sergio Sobarzo Guzmán ◽  
...  
Keyword(s):  
Proof Of Concept ◽  
Future Observation ◽  
Observation Strategies
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