Publications
Gust front update algorithm for the Weather Systems Processor (WSP)
July 29, 2002
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-275
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Summary
The Gust Front Update Algorithm (GFUP) is part of the gust front product generation chain for the ASR-9 Weather Systems Processor (WSP). GFUP processes gust front detection and position prediction data output by the Machine Intelligent Gust Front Algorithm (MIGFA), and uses an internal timer to schedule generation of updated current and 10- and 20-minute gust front predictions at 1-minute intervals. By substituting appropriate interval gust front forecast data from MIGFA, the locations of gust fronts shown on the user display are updated at a rate that is faster than the radar base data processed by MIGFA. Prior to output, the updated curve position data are smothered by GFUP using a tangent-spline interpolation algorithm. This document provides a general overview and high level description of the GFUP algorithm.
Summary
The Gust Front Update Algorithm (GFUP) is part of the gust front product generation chain for the ASR-9 Weather Systems Processor (WSP). GFUP processes gust front detection and position prediction data output by the Machine Intelligent Gust Front Algorithm (MIGFA), and uses an internal timer to schedule generation of updated...
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300x faster Matlab using MatlabMPI
July 18, 2002
Journal Article
Published in:
https://arxiv.org/abs/astro-ph/0207389
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The true costs of high performance computing are currently dominated by software. Addressing these costs requires shifting to high productivity languages such as Matlab. MatlabMPI is a Matlab implementation of the Message Passing Interface (MPI) standard and allows any Matlab program to exploit multiple processors. MatlabMPI currently implements the basic six functions that are the core of the MPI point-to-point communications standard. The key technical innovation of MatlabMPI is that it implements the widely used MPI "look and feel" on top of standard Matlab file I/O, resulting in an extremely compact (~250 lines of code) and "pure" implementation which runs anywhere Matlab runs, and on any heterogeneous combination of computers. The performance has been tested on both shared and distributedmemory parallel computers (e.g. Sun, SGI, HP, IBM and Linux). MatlabMPI can match the bandwidth of C based MPI at large message sizes. A test image filtering application using MatlabMPI achieved a speedup of ~300 using 304 CPUs and ~15% of the theoretical peak (450 Gigaflops) on an IBM SP2 at the Maui High Performance Computing Center. In addition, this entire parallel benchmark application was implemented in 70 software-lines-of-code (SLOC) yielding 0.85 Gigaflop/SLOC or 4.4 CPUs/SLOC, which are the highest values of these software price performance metrics ever achieved for any application. The MatlabMPI software will be made available for download.
Summary
The true costs of high performance computing are currently dominated by software. Addressing these costs requires shifting to high productivity languages such as Matlab. MatlabMPI is a Matlab implementation of the Message Passing Interface (MPI) standard and allows any Matlab program to exploit multiple processors. MatlabMPI currently implements the basic...
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Potential benefits of reducing wake-related aircraft spacing at the Dallas/Fort Worth International Airport
July 12, 2002
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-304
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Summary
Measurements and modeling of wake vortices reveal that the Federal Aviation Administration's (FAA) minimum separation requirements for departing aircraft are often overly conservative. If the separation times following heavy aircraft can be safely reduced, considerable savings will be realized. The Dallas/Fort Worth International Airport (DFW) experiences departure delays daily. Banks of departing aircraft often create a significant queue at the end of the runway, with aircraft waiting between 10-20 minutes to depart. Additional delays occur during weather recovery operations after the terminal airspace has been impacted by thunderstorms. This report produces projected delay and cost benefits of implementing reduced wake spacing for departing aircraft at DFW. The benefits are calculated by simulating aircraft departures during both clear weather and weather recovery operations, using current and possible reduced spacings. The difference in delay values using different separation standards is used to calculate a cost savings to the airlines. The benefits for a single day are extended to a yearly approximation based on the estimated number of days that the separation criteria could be safely reduced. Departure information from February 19, 2001 is analyzed for clear weather operations. The simulation reveals a savings of $4.7 million/yr when the separation criteria is reduced from the current practice of 110 seconds to 90 seconds. A further reduction in the separation criteria to 60 seconds pushes the maximum savings to almost $10 million/yr. The daily savings for a weather recovery operation is $19,600 for weather impacts between 15-60 minutes and a reduction in spacing fiom the current 110 seconds to 90 seconds. The average increases to $36,200 when the spacing is reduced to 60 seconds. Significant thunderstorm events impacted the DFW terminal airspace 59 times during 2001 leading to projected yearly savings of greater than $2.1 million for a 60 second separation criteria following heavies.
Summary
Measurements and modeling of wake vortices reveal that the Federal Aviation Administration's (FAA) minimum separation requirements for departing aircraft are often overly conservative. If the separation times following heavy aircraft can be safely reduced, considerable savings will be realized. The Dallas/Fort Worth International Airport (DFW) experiences departure delays daily. Banks...
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High-speed, electronically shuttered solid-state imager technology
July 8, 2002
Conference Paper
Published in:
Rev. Sci. Instrum. Vol. 74, No. 3, Pt. II, March 2003, pp. 2027-2031 (Proceedings of the 14th Topical Conference on High-Temperature Plasma Diagnostics, 8-11 July 2002)
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Summary
Electronically shuttered solid-state imagers are being developed for high-speed imaging applications. A 5 cmx5 cm, 512x512-element, multiframe charge-coupled device (CCD) imager has been fabricated for the Los Alamos National Laboratory DARHT facility that collects four sequential image frames at megahertz rates. To operate at fast frame rates with high sensitivity, the imager uses an electronic shutter technology designed for back-illuminated CCDs. The design concept and test results are described for the burst-frame-rate imager. Also discussed is an evolving solid-state imager technology that has interesting characteristics for creating large-format x-ray detectors with short integration times (100 ps to 1 ns). Proposed device architectures use CMOS technology for high speed sampling (tens of picoseconds transistor switching times). Techniques for parallel clock distribution, that triggers the sampling of x-ray photoelectrons, will be described that exploit features of CMOS technology.
Summary
Electronically shuttered solid-state imagers are being developed for high-speed imaging applications. A 5 cmx5 cm, 512x512-element, multiframe charge-coupled device (CCD) imager has been fabricated for the Los Alamos National Laboratory DARHT facility that collects four sequential image frames at megahertz rates. To operate at fast frame rates with high sensitivity...
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Flight test results of the Earth Observing-1 Advanced Land Imager
July 7, 2002
Conference Paper
Published in:
SPIE, Vol. 4814, Earth Observing Systems VII, 7-10 July 2002, pp. 296-305.
Summary
The Advanced Land Imager (ALI) is the primary instrument on the Earth Observing-1 spacecraft (EO-1) and was developed under NASA's New Millennium Program (NMP). The NMP mission objective is to flight-validate advanced technologies that will enable dramatic improvements in performance, cost, mass, and schedule for future, Landsat-like, Earth Science Enterprise instruments. ALI contains a number of innovative features designed to achieve this objective. These include the basic instrument architecture, which employs a push-broom data collection mode, a wide field-of-view optical design, compact multi-spectral detector arrays, non-cryogenic HgCdTe for the short wave infrared bands, silicon carbide optics, and a multi-level solar calibration technique. The sensor includes detector arrays that operate in ten bands, one panchromatic, six VNIR and three SWIR, spanning the range fiom 0.433 to 2.35 um. Launched on November 21, 2000, ALI instrument performance was monitored during its first year on orbit using data collected during solar, lunar, stellar, and earth observations. This paper will provide an overview of EO-1 mission activities during this period. Additionally, the on-orbit spatial and radiometric performance of the instrument will be compared to pre-flight measurements and the temporal stability of ALI will be presented.
Summary
The Advanced Land Imager (ALI) is the primary instrument on the Earth Observing-1 spacecraft (EO-1) and was developed under NASA's New Millennium Program (NMP). The NMP mission objective is to flight-validate advanced technologies that will enable dramatic improvements in performance, cost, mass, and schedule for future, Landsat-like, Earth Science Enterprise...
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Proton irradiations of large area Hg(1-x)Cd(x)Te photovoltaic detectors for the cross-track infrared sounder
July 7, 2002
Conference Paper
Published in:
SPIE Vol. 4820, Pt. 1, Infrared Technology and Applications XXVIII, 7-11 July 2002, pp. 479-490.
Summary
The effect of radiation on Hg(1-x)Cd(x)Te photodiodes is an important parameter to understand when determining the long-term performance limitations for the Cross-track Infrared Sounder (CrIS), a Fourier Transform interferometric sensor that will fly as part of the National Polar-orbiting Operational Enviornmental Satellite System (NPOESS). The CrIS sensor uses relatively large area photovoltaic detectors, 1mm in diameter. Each p-on-n Hg(1-x)Cd(x)Te photodiode consists of MBE grown, n-type material on lattice matched CdZnTe, with arsenic implantation used to form the junction. A 1mm diameter detector is achieved by using a lateral collection. Solar, and trapped protons are a significant source of radiation in the NPOESS 833 km orbits. We irradiated 22 LWIR detectors with protons at the Harvard Cyclotron Laboratory (HCL) and monitored the I-V performance and dynamic impedance of each detector. Three groups of detectors were irradiated with either 44, 99, 153-MeV protons, each between 1x10(10) - 4x10(12) p+/cm(2) (total range ~ 0.7 - 690 krad(Si)). Several I-V data sets were collected within that fluence range at all three energies. All the detectors were warmed to room temperature for approximately 96 hours following the largest proton dose, recooled, and then re-characterized in terms of I-V performance and dynamic impedance. The total noise increase predicted for CrIS after 7-years in orbit is less than 1%.
Summary
The effect of radiation on Hg(1-x)Cd(x)Te photodiodes is an important parameter to understand when determining the long-term performance limitations for the Cross-track Infrared Sounder (CrIS), a Fourier Transform interferometric sensor that will fly as part of the National Polar-orbiting Operational Enviornmental Satellite System (NPOESS). The CrIS sensor uses relatively large...
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ASR-9 Weather Systems Processor (WSP) signal processing algorithms
June 25, 2002
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-255
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Thunderstorm activity and associated low-altitude wind shear constitute a significant safety hazard to aviation, particularly during operations near airport terminals where aircraft altitude is low and flight routes are constrained. The Federal Aviation Administration (FAA) has procured several dedicated meteorological sensors (Terminal Doppler Weather Radar (TDWR), Network Expansion Low Level Wind Shear Alert System (LLWAS) at major airports to enhance the safety and efficiency of operations during convective weather. A hardware and software modification to existing Airport Surveillance Radars (ASR-9)-the Weather Systems Processor (WSP)-will provide similar capabilities at much lower cost, thus allowing the FAA to extend its protection envelope to medium density airports and airports where thunderstorm activity is less frequent. Following successful operation demonstrations of a prototype ASR-WSP, the FAA has procured approximately 35 WSP's for nationwide deployment. Lincoln Laboratory was responsible for development of all data processing algorithms, which were provided as Government Furnished Equipment (GFE), to be implemented by the full-scale development (FSD) contractor without modification. This report defines the operations that are used to produce images of atmospheric reflectivity, Doppler velocity and data quality that are used by WSP's meteorological product algorithms to generate automated information on hazardous wind shear and other phenomena. Principle requirements are suppression of interference (e.g. ground clutter, moving points targets, meteorological and ground echoes originating from beyond the radar's unambiguous range), generation of meteorologically relevant images and estimates of data quality. Hereafter, these operations will be referred to as "signal processing" and the resulting images as "base data."
Summary
Thunderstorm activity and associated low-altitude wind shear constitute a significant safety hazard to aviation, particularly during operations near airport terminals where aircraft altitude is low and flight routes are constrained. The Federal Aviation Administration (FAA) has procured several dedicated meteorological sensors (Terminal Doppler Weather Radar (TDWR), Network Expansion Low Level...
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Broadband (200-1000 nm) back-illuminated ccd imagers
June 16, 2002
Conference Paper
Published in:
Scientific Detectors Workshop 2002, 16-22 June 2002.p. 41-50.
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Improved and stable blue/UV quantum efficiency has been demonstrated on 2Kx4K imagers using molecular-beam epitaxy to create a thin doped layer on the back surface. Quantum efficiency data on thick (40-50 pm) imagers with single and dual-layer anti-reflection coatings is presented that demonstrates high and broadband response. Measurements of the optical point-spread response show the devices to be fully depleted with good response across a broad spectrum, but interesting features appear in the near-IR as a result of deeply penetrating light being scattered off the surface structure of the CCD.
Summary
Improved and stable blue/UV quantum efficiency has been demonstrated on 2Kx4K imagers using molecular-beam epitaxy to create a thin doped layer on the back surface. Quantum efficiency data on thick (40-50 pm) imagers with single and dual-layer anti-reflection coatings is presented that demonstrates high and broadband response. Measurements of the...
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Machine intelligent gust front algorithm for the WSP
June 10, 2002
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-274
Summary
The Machine Intelligent Gust Front Algorithm (MIGFA) utilizes multi-dimensional image processing and fuzzy logic techniques to identify gust fronts in Doppler radar data generated by the ASR-9 Weather Systems Processor (WSP). The algorithm generates products that support both safety and planning functions for ATC. Outputs include current and predicted locations of gust fronts, as well as estimates of the wind shear and wind shift associated with each gust front. This document provides both high level and detailed functional descriptions of FAA build 2.0 of the WSP MIGFA. The document was written with many explicit references to data structures and routines in the actual software in order that it may serve as a useful algorithm development and programmers reference guide.
Summary
The Machine Intelligent Gust Front Algorithm (MIGFA) utilizes multi-dimensional image processing and fuzzy logic techniques to identify gust fronts in Doppler radar data generated by the ASR-9 Weather Systems Processor (WSP). The algorithm generates products that support both safety and planning functions for ATC. Outputs include current and predicted locations...
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Aircraft encounters with thunderstorms in enroute vs. terminal airspace above Memphis, Tennesssee
May 13, 2002
Conference Paper
Published in:
Proc. 10th Conf. on Aviation, Range and Aerospace Meteorology, 13-16 May 2002, pp. 162-165.
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To date, very little attention has been given to quantifying the effects of thunderstorms on air traffic in enroute airspace. What types of storms cause pilots to deviate from their nominal flight routes? What types of storms do pilots fly through? Around? Over? When thunderstorms are forecast to affect a particular region, how many planes will need to be rerouted? Which ones? Which aspects of the storm need to be accurately forecast in order to answer those questions? How does the forecast accuracy affect the quality of airspace capacity predictions? Quantitative answers to these questions would contribute to the design of useful decision support tools. Federal Aviation Administration decision support tools are being equipped with the ability for air traffic managers to define dynamic "flow constrained areas" (FCAs). Each FCA will be a polygon in latitude/longitude space with ceiling and floor altitudes and a motion vector. One primary use for FCAs will be to define regions that do, or probably will, contain convective thunderstorm activity. These tools will help air traffic managers decide which planes to re-route around the weather and which planes have a reasonable chance of flying through, between, or over the storms. Although it will be helpful to have the ability to manually define FCAs in the traffic managers' tools, the efficiency of the solutions that will be worked out with those tools would be greatly enhanced by answers to the questions posed above. In our prior work we have attempted to quantify the behavior of pilots who encounter thunderstorms in terminal airspace during the final 60 nautical miles of flight. In this study we compare the storm avoidance behavior of pilots in enroute airspace with that of pilots who encountered the very same storms at lower altitudes, in terminal airspace. The study is preliminary, but it complements the terminal work, affords some insight into pilot behavior, and raises questions that should be addressed in a larger study.
Summary
To date, very little attention has been given to quantifying the effects of thunderstorms on air traffic in enroute airspace. What types of storms cause pilots to deviate from their nominal flight routes? What types of storms do pilots fly through? Around? Over? When thunderstorms are forecast to affect a...
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