A recursive moving-target-indication algorithm for optical imagesequences

A recursive track-before-detect algorithm, producing potentially large signal-to-noise ratio (SNR) gains under realizable conditions, is described. The basic relation has the form of a linear, constant-coefficient difference equation with a unity magnitude damping factor. Known as recursive moving-target-indication (RMTI), this procedure adapts easily to digital processing and achieves SNR gains comparable to those from other robust track-before-detect algorithms. Examples are given to demonstrate the performance of the moving target indicator (MTI) procedure     

Galileo Photopolarimeter/Radiometer experiment

The Photopolarimeter/Radiometer (PPR) is a remote sensing instrument on the Galileo Orbiter designed to measure the degree of linear polarization and the intensity of reflected sunlight in ten spectral channels between 410 and 945 nm to determine the physical properties of Jovian clouds and aerosols, and to characterize the texture and microstructure of satellite surfaces. The PPR also measures thermal radiation in five spectral bands between 15 and 100 m to sense the upper tropospheric temperature structure. Two additional channels which measure spectrally integrated solar and solar plus thermal radiation are used to determine the planetary radiation budget components. The PPR photopolarimetric measurements utilize previously flown technology for high-precision polarimetry using a calcite Wollaston prism and two silicon photodiodes to enable simultaneous detection of the two orthogonal polarization components. The PPR radiometry measurements are made with a lithium tantalate pyroelectric detector utilizing a unique arrangement of radiometric stops and a scene/space chopper blade to enable a warm instrument to sense accurately the much colder scene temperatures.     

Composition Aspects of the Upper Solar Atmosphere Rapporteur Paper III

This rapporteur paper discusses the solar corona and the solar wind in the context of their chemical composition. The abundances of elements, both obtained by optical and by in situ observations, are used to infer the sources of the slow solar wind and of the fast streams. The first ionisation potential (FIP) fractionation effect is also discussed, in particular the agreed basics and the open questions. This revised version was published online in June 2006 with corrections to the Cover Date.     

How to Climb the Gravity Wall

Space Science Reviews - What type of gravity satellite mission is required for the time after GRACE and GOCE? Essentially, the variables at our disposal are experiment altitude, compensation of...     

Amplification of the influence of solar flux variations on the winter stratosphere by planetary waves

Recent observational evidence has suggested that variations in solar activity may affect winter stratospheric polar ozone and temperature levels. The paucity of direct sunlight available during this season points strongly to a dynamical mechanism. We have carried out several large ensemble experiments within the middle atmosphere and the coupled middle atmosphere and lower thermosphere to simulate the radiative/dynamical coupling via planetary waves for a range of solar fluxes. In the former case, the model response in the winter stratosphere was linear and of the order of the summer stratopause forcing, whilst in the latter, the level of correlation in the winter stratosphere remained high, but was diluted over a wider volume. The inclusion of the upper atmosphere enhanced the winter polar stratospheric response by a factor of three.     

Design of a Correlator for Real-Time Video Comparisons

The problem of locating a reference image within a larger image using a correlation technique is discussed. Although the particular application discussed is that of locating a reference image obtained from one video sensor or a photograph, within the larger field of view obtained from a second video sensor in real time (i.e., at the TV field rate), the results are general and useful for a number of applications. The tradeoffs necessary to obtain real time correlat are discussed and their effect on correlation accuracy is given.