|
Collocation (remote Sensing)
Collocation is a procedure used in remote sensing to match measurements from two or more different instruments. This is done for two main reasons: for validation purposes when comparing measurements of the same variable, and to relate measurements of two different variables either for performing retrievals or for prediction. In the second case the data is later fed into some type of statistical inverse problem, inverse method such as an artificial neural network, statistical classification algorithm, kernel estimation, kernel estimator or a Linear least squares (mathematics), linear least squares. In principle, most collocation problems can be solved by a nearest neighbor search, but in practice there are many other considerations involved and the best method is highly specific to the particular matching of instruments. Here we deal with some of the most important considerations along with specific examples. There are at least two main considerations when performing collocatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Remote Sensing
Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Earth and other planets. Remote sensing is used in numerous fields, including geography, land surveying and most Earth science disciplines (e.g. hydrology, ecology, meteorology, oceanography, glaciology, geology); it also has military, intelligence, commercial, economic, planning, and humanitarian applications, among others. In current usage, the term ''remote sensing'' generally refers to the use of satellite- or aircraft-based sensor technologies to detect and classify objects on Earth. It includes the surface and the atmosphere and oceans, based on propagated signals (e.g. electromagnetic radiation). It may be split into "active" remote sensing (when a signal is emitted by a satellite or aircraft to the object and its reflection dete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbit
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point. Normally, orbit refers to a regularly repeating trajectory, although it may also refer to a non-repeating trajectory. To a close approximation, planets and satellites follow elliptic orbits, with the center of mass being orbited at a focal point of the ellipse, as described by Kepler's laws of planetary motion. For most situations, orbital motion is adequately approximated by Newtonian mechanics, which explains gravity as a force obeying an inverse-square law. However, Albert Einstein's general theory of relativity, which accounts for gravity as due to curvature of spacetime, with orbits following geodesics, provides a more accurate calculation and understanding of the exact mechanics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trilinear Interpolation
Trilinear interpolation is a method of multivariate interpolation on a 3-dimensional regular grid. It approximates the value of a function at an intermediate point (x, y, z) within the local axial rectangular prism linearly, using function data on the lattice points. For an arbitrary, unstructured mesh (as used in finite element analysis), other methods of interpolation must be used; if all the mesh elements are tetrahedra (3D simplices), then barycentric coordinates provide a straightforward procedure. Trilinear interpolation is frequently used in numerical analysis, data analysis, and computer graphics. Compared to linear and bilinear interpolation Trilinear interpolation is the extension of linear interpolation, which operates in spaces with dimension D = 1, and bilinear interpolation, which operates with dimension D = 2, to dimension D = 3. These interpolation schemes all use polynomials of order 1, giving an accuracy of order 2, and it requires 2^D = 8 adjacent pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bilinear Interpolation
In mathematics, bilinear interpolation is a method for interpolating functions of two variables (e.g., ''x'' and ''y'') using repeated linear interpolation. It is usually applied to functions sampled on a 2D rectilinear grid, though it can be generalized to functions defined on the vertices of (a mesh of) arbitrary convex quadrilaterals. Bilinear interpolation is performed using linear interpolation first in one direction, and then again in the other direction. Although each step is linear in the sampled values and in the position, the interpolation as a whole is not linear but rather quadratic in the sample location. Bilinear interpolation is one of the basic resampling techniques in computer vision and image processing, where it is also called bilinear filtering or bilinear texture mapping. Computation Suppose that we want to find the value of the unknown function ''f'' at the point (''x'', ''y''). It is assumed that we know the value of ''f'' at the four points ''Q''11 = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Interpolation
In mathematics, linear interpolation is a method of curve fitting using linear polynomials to construct new data points within the range of a discrete set of known data points. Linear interpolation between two known points If the two known points are given by the coordinates (x_0,y_0) and (x_1,y_1), the linear interpolant is the straight line between these points. For a value in the interval (x_0, x_1), the value along the straight line is given from the equation of slopes \frac = \frac, which can be derived geometrically from the figure on the right. It is a special case of polynomial interpolation with . Solving this equation for , which is the unknown value at , gives \begin y &= y_0 + (x-x_0)\frac \\ &= \frac + \frac\\ &= \frac \\ &= \frac, \end which is the formula for linear interpolation in the interval (x_0,x_1). Outside this interval, the formula is identical to linear extrapolation. This formula can also be understood as a weighted average. The weights are in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorological Reanalysis
An atmospheric reanalysis (also: meteorological reanalysis and climate reanalysis) is a meteorological and climate data assimilation project which aims to assimilate historical atmospheric observational data spanning an extended period, using a single consistent assimilation (or "analysis") scheme throughout. Operational data analysis In operational numerical weather prediction, forecast models are used to predict future states of the atmosphere, based on how the climate system evolves with time from an initial state. The initial state provided as input to the forecast must consist of data values for a range of "prognostic" meteorological fields – that is, those fields which determine the future evolution of the model. Spatially varying fields are required in the form used by the model, for example at each intersection point on a regular grid of longitude and latitude circles, and initial data must be valid at a single time that corresponds to the present or the recent past ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Assimilation
Data assimilation is a mathematical discipline that seeks to optimally combine theory (usually in the form of a numerical model) with observations. There may be a number of different goals sought – for example, to determine the optimal state estimate of a system, to determine initial conditions for a numerical forecast model, to interpolate sparse observation data using (e.g. physical) knowledge of the system being observed, to set numerical parameters based on training a model from observed data. Depending on the goal, different solution methods may be used. Data assimilation is distinguished from other forms of machine learning, image analysis, and statistical methods in that it utilizes a dynamical model of the system being analyzed. Data assimilation initially developed in the field of numerical weather prediction. Numerical weather prediction models are equations describing the dynamical behavior of the atmosphere, typically coded into a computer program. In order to use t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polarstern
RV ''Polarstern'' (meaning pole star) is a German research icebreaker of the Alfred Wegener Institute for Polar and Marine Research (AWI) in Bremerhaven, Germany. ''Polarstern'' was built by Howaldtswerke-Deutsche Werft in Kiel and Nobiskrug in Rendsburg, was commissioned in 1982, and is mainly used for research in the Arctic and Antarctica. The ship has a length of 118 metres (387 feet) and is a double-hulled icebreaker. She is operational at temperatures as low as . ''Polarstern'' can break through ice thick at a speed of . Thicker ice of up to can be broken by ramming. History On 7 September 1991, ''Polarstern'', assisted by the Swedish arctic icebreaker , reached the North Pole as the first conventional powered vessels. Both scientific parties and crew took oceanographic and geological samples and had a common tug of war and a football game on an ice floe. In 2001, ''Polarstern'' together with reached the pole again. She returned for a third time on 22 August 2011. This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rs Ascent Hist
RS may refer to: Businesses and organizations Sport * RS Sailing, an international designer and builder of sailboats and dinghies * Ford TeamRS, Ford Motor Company's European performance car and motorsport division * Renault Sport, performance and motorsport division of automobile manufacturer Renault * Queens Park Rangers F.C., a professional football club from Shepherd's Bush, London, commonly nicknamed 'The Rs' Other businesses and organizations * RS Group, entertainment & media company in Thailand * RS Group plc, electronics & industrial distributor in England ** RS Components, an international electronic component distributor * Relief Society, an official auxiliary of The Church of Jesus Christ of Latter-day Saints (LDS Church) * République solidaire, a French political party * Roberval and Saguenay Railway (reporting mark RS) * Russian Party (''Ruska stranka''), a political party in Serbia Places * Republic of Serbia, country (ISO 3166-1 code RS) * Republic of Sl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Balloon
A weather balloon, also known as sounding balloon, is a balloon (specifically a type of high-altitude balloon) that carries instruments aloft to send back information on atmospheric pressure, temperature, humidity and wind speed by means of a small, expendable measuring device called a radiosonde. To obtain wind data, they can be tracked by radar, radio direction finding, or navigation systems (such as the satellite-based Global Positioning System, GPS). Balloons meant to stay at a constant altitude for long periods of time are known as ''transosondes''. Weather balloons that do not carry an instrument pack are used to determine upper-level winds and the height of cloud layers. For such balloons, a theodolite or total station is used to track the balloon's azimuth and elevation, which are then converted to estimated wind speed and direction and/or cloud height, as applicable. Weather balloons are launched around the world for observations used to diagnose current co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiosonde
A radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calculate the following variables: altitude, pressure, temperature, relative humidity, wind (both wind speed and wind direction), cosmic ray readings at high altitude and geographical position (latitude/longitude). Radiosondes measuring ozone concentration are known as ozonesondes. Radiosondes may operate at a radio frequency of 403 MHz or 1680 MHz. A radiosonde whose position is tracked as it ascends to give wind speed and direction information is called a rawinsonde ("radar wind -sonde"). Most radiosondes have radar reflectors and are technically rawinsondes. A radiosonde that is dropped from an airplane and falls, rather than being carried by a balloon is called a dropsonde. Radiosondes are an essential source of meteorological ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rs Ascent
RS may refer to: Businesses and organizations Sport * RS Sailing, an international designer and builder of sailboats and dinghies * Ford TeamRS, Ford Motor Company's European performance car and motorsport division * Renault Sport, performance and motorsport division of automobile manufacturer Renault * Queens Park Rangers F.C., a professional football club from Shepherd's Bush, London, commonly nicknamed 'The Rs' Other businesses and organizations * RS Group, entertainment & media company in Thailand * RS Group plc, electronics & industrial distributor in England ** RS Components, an international electronic component distributor * Relief Society, an official auxiliary of The Church of Jesus Christ of Latter-day Saints (LDS Church) * République solidaire, a French political party * Roberval and Saguenay Railway (reporting mark RS) * Russian Party (''Ruska stranka''), a political party in Serbia Places * Republic of Serbia, country (ISO 3166-1 code RS) * Republic of Sl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
