نتایج جستجو برای: scale altimeter
تعداد نتایج: 578305 فیلتر نتایج به سال:
The pseudo maximum likelihood estimator allows one to estimate the unknown parameters of Brown’s model for altimeter waveforms. However, the optimality of this estimator, for instance in terms of minimizing the mean square errors of the unknown parameters is not guarantied. Thus it is not clear whether there is some space for developing new estimators for the unknown parameters of altimetric si...
[1] One of the main limitations to current wave data assimilation systems is the lack of an accurate representation of the structure of the background errors. One method that may be used to determine background errors is the observational method of Hollingsworth and Lönnberg [1986]. This method considers correlations of the differences between observations and the background. For the case of Si...
The BepiColombo Laser Altimeter (BELA) has been selected for flight on board the European Space Agency’s BepiColombo Mercury Planetary Orbiter (MPO). The experiment is intended to be Europe’s first planetary laser altimeter system. Although the proposed system has similarities to the Mercury Laser Altimeter (MLA) currently flying on board NASA’s MESSENGER mission to Mercury, the specific orbit ...
This report presents the results of an eight-month study of signal processing techniques applicable to the Geodetic Satellite Altimeter program. The first subject treated is the analysis of random errors in the altitude measurement process which arise from signal fluctuations and receiver noise. Results are presented based on both theoretical analyses and computer simulation of the altimeter co...
Water properties critical to our understanding and managing of freshwater systems change rapidly with depth. This work presents an Unmanned Aerial Vehicle (UAV) based method of keeping a passive, cable-suspended sensor payload at a precise depth, with 95% of submerged sensor readings within ±8.4 cm of the target depth, helping dramatically increase the spatiotemporal resolution of water science...
Two sources of H113 estimates were available at Platform Harvest; a NOAA buoy and CU depth sensor highrate data. H113 estimates from the NOAA buoy were based on twenty minutes of data every hour, CU pressure measurements were taken every 1.1 seconds. For purposes of this paper, H113 estimates from the (7U depth sensor were based on one hour of data, This paper compares H113 measurements from TO...
We combine the complementary characteristics of laser altimeter data and stereoscopic digital elevation models (DEMs) to construct high-resolution ( 100m) maps of surface elevations and elevation changes over rapidly changing outlet glaciers in Greenland. Measurements from spaceborne and airborne laser altimeters have relatively low errors but are spatially limited to the ground tracks, while D...
-This paper compares four cont/nental ice sheet radar altimeter retracking algorithms using airborne radar and laser altimeter data taken over the Greenland ice sheet in 1991. The refurbished Advanced Application Flight Experiment (AAFE) airborne radar altimeter has a large range window and stores the entire return waveform during flight. Once the return waveforms are retracked, or post-process...
easuring changes in the cryosphere from satellite-based altimeters has and will continue to provide data that are essential to our understanding of the long-term trends of the earth’s ice cover. over the past years, ApL has played a major role in airborne field activities observing continental ice sheets, outlet glaciers, and sea ice using the delayDoppler phase-monopulse (D2p) airborne radar a...
An algorithm for the retrieval of surface wind speed from Ku-band altimeter backscatter coefficient is proposed. The algorithm was derived using two-month worth of ENVISAT altimeter backscatter data collocated with ECMWF model and buoy wind speeds. The algorithm was extensively verified for ENVISAT, ERS2 and Jason-1 altimeters. The algorithm performance is better than the “modified Chelton-Went...
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