Publications
The Offshore Precipitation Capability
September 16, 2016
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-430
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Summary
In this work, machine learning and image processing methods are used to estimate radar-like precipitation intensity and echo top heights beyond the range of weather radar. The technology, called the Offshore Precipitation Capability (OPC), combines global lightning data with existing radar mosaics, five Geostationary Operational Environmental Satellite (GOES) channels, and several fields from the Rapid Refresh (RAP) 13 km numerical weather prediction model to create precipitation and echo top fields similar to those provided by existing Federal Aviation Administration (FAA) weather systems. Preprocessing and feature extraction methods are described to construct inputs for model training. A variety of machine learning algorithms are investigated to identify which provides the most accuracy. Output from the machine learning model is blended with existing radar mosaics to create weather radar-like analyses that extend into offshore regions. The resulting fields are validated using land radars and satellite precipitation measurements provided by the National Aeronautics and Space Administration (NASA) Global Precipitation Measurement Mission (GPM) core observatory satellite. This capability is initially being developed for the Miami Oceanic airspace with the goal of providing improved situational awareness for offshore air traffic control.
Summary
In this work, machine learning and image processing methods are used to estimate radar-like precipitation intensity and echo top heights beyond the range of weather radar. The technology, called the Offshore Precipitation Capability (OPC), combines global lightning data with existing radar mosaics, five Geostationary Operational Environmental Satellite (GOES) channels, and...
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The threat to weather radars by wireless technology
July 1, 2016
Journal Article
Published in:
Amer. Meteor. Soc., Vol. 97, No. 7, 1 July 2016, pp. 1159-67, doi: 10.1175/BAMS-D-15-00048.1.
Summary
Wireless technology, such as local area telecommunication networks and surveillance cameras, causes severe interference for weather radars, because they use the same operational radio frequencies. One or two disturbances can be removed from the radar image, but the number and power of the interfering wireless devices are growing all over the world, threatening that one day the radars could not be used at all. Some agencies have already changed or are considering changing frequency bands, but now even other bands are under threat. Use of equipment at radio frequencies is regulated by laws and international agreements. Technologies have been developed for peaceful co-existence. If wireless devices use these technologies to protect weather radars, their data transmission capabilities become limited, so it is tempting to violate the regulations. Hence, it is an important task for the worldwide weather community to involve themselves in the radio-frequency management process and work in close contact with their National Radio Authorities to ensure that meteorological interests be duly taken into account in any decision making process toward the future usage of wireless devices.
Summary
Wireless technology, such as local area telecommunication networks and surveillance cameras, causes severe interference for weather radars, because they use the same operational radio frequencies. One or two disturbances can be removed from the radar image, but the number and power of the interfering wireless devices are growing all over...
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2015 operational observation of CoSPA and traffic flow impact
March 15, 2016
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-429
Summary
This technical report summarizes the operational observations recorded by MIT Lincoln Laboratory (MIT LL) aviation subject matter experts during the period 13 April to 31 October 2015. Three separate field observations were conducted over four convective weather days across the eastern National Airspace System (NAS) with visits to five separate FAA facilities and five different airline operation centers. Observations of strategic management planning and decision making were documented during these visits. Specifically noted were the utilization of the deterministic convective weather forecasting model, CoSPA, and a newly developed decision support application, Traffic Flow Impact (TFI). These field evaluations were supported via the FAA AJM-334 CoSPA program.
Summary
This technical report summarizes the operational observations recorded by MIT Lincoln Laboratory (MIT LL) aviation subject matter experts during the period 13 April to 31 October 2015. Three separate field observations were conducted over four convective weather days across the eastern National Airspace System (NAS) with visits to five separate...
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Airspace flow rate forecast algorithms, validation, and implementation
December 15, 2015
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-428
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This report summarizes work performed by MIT Lincoln Laboratory during the period 1 February 2015 - 30 November 2015 focused on developing and improving algorithms to estimate the impact of convective weather on air traffic flows. The core motivation for the work is the need to improve strategic traffic flow management decision-making in the National Airspace System. The algorithms developed as part of this work translate multiple weather forecast products into a discrete airspace impact metric called permeability.
Summary
This report summarizes work performed by MIT Lincoln Laboratory during the period 1 February 2015 - 30 November 2015 focused on developing and improving algorithms to estimate the impact of convective weather on air traffic flows. The core motivation for the work is the need to improve strategic traffic flow...
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Enhanced signal processing algorithms for the ASR-9 Weather Systems Processor
October 1, 2015
Journal Article
Published in:
J. Atmos. Ocean. Technol., Vol. 32, No. 10, October 2015, pp. 1847-59.
Summary
New signal processing algorithms for the Airport Surveillance Radar-9 (ASR-9) Weather Systems Processor (WSP) are introduced. The Moving Clutter Spectral Processing for Uneven-Sampled Data with Dealiasing (MCSPUDD) algorithm suite removes isolated moving clutter targets and corrects aliased velocity values on a per-range-gate basis. The spectral differencing technique is applied to the low- and high-beam data to produce a dual-beam velocity estimate that is more accurate than the current autocorrelation-lag-1-based approach. Comparisons with Terminal Doppler Weather Radar (TDWR) data show that estimate errors are reduced by 8%, 15%, and 15% for the low-, high-, and dual-beam velocities, respectively.
Summary
New signal processing algorithms for the Airport Surveillance Radar-9 (ASR-9) Weather Systems Processor (WSP) are introduced. The Moving Clutter Spectral Processing for Uneven-Sampled Data with Dealiasing (MCSPUDD) algorithm suite removes isolated moving clutter targets and corrects aliased velocity values on a per-range-gate basis. The spectral differencing technique is applied to...
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Evaluation of the baseline NEXRAD icing hazard project
September 17, 2015
Conference Paper
Published in:
37th Conference on Radar Meteorology, 14-18 September 2015
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MIT Lincoln Laboratory has developed an icing hazard product that is now operational throughout the NEXRAD network. This initial version of the Icing Hazard Levels (IHL) algorithm is predicated on the presence of graupel as determined by the NEXRAD Hydrometeor Classification Algorithm (HCA). Graupel indicates that rime accretion on ice crystal aggregates is present. It is inferred that the riming process occurs at the altitude that HCA reports graupel as well as to some vertical depth above. To capture some of that depth, temperature and relative humidity interest fields are computed from meteorological model data based on the technique used in the National Center for Atmospheric Research's Current Icing Potential Product and utilized within IHL as warranted. A critical aspect of the IHL development has focused on the verification of the presence of icing. Two methods are used. For the first, pilot reports of icing (PIREPs) are used to score the performance of IHL. Since PIREPs are provided with inherent time and space uncertainties, a buffer of influence is associated with each PIREP when scoring IHL. Results show the IHL as configured is an effective indicator of a potential icing hazard when HCA graupel classifications are present. Results also show the importance of radar volume coverage pattern selection in detecting weak returns in winter weather. For the second, in situ icing missions were performed within range of a dual pol NEXRAD to provide quantitative data to identify the presence of supercooled liquid water. Comparisons of in situ data to HCA classifications show that HCA graupel indications do not fully expose the icing hazard and these findings are being used to direct future attention of IHL development. This paper will describe the verification method and performance assessment of the IHL initial capability.
Summary
MIT Lincoln Laboratory has developed an icing hazard product that is now operational throughout the NEXRAD network. This initial version of the Icing Hazard Levels (IHL) algorithm is predicated on the presence of graupel as determined by the NEXRAD Hydrometeor Classification Algorithm (HCA). Graupel indicates that rime accretion on ice...
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ASR-9 Weather Systems Processor technology refresh and upgrade
September 14, 2015
Conference Paper
Published in:
37th Conf. on Radar Meteorology, 14-18 September, 2015.
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The Weather Systems Processor (WSP) is an add-on system to the Airport Surveillance Radar-9 (ASR-9) that generates wind shear detection and storm tracking products for the terminal airspace. As the original system ages and pre-purchased replacement parts in the depot are used up, it becomes increasingly problematic to procure hardware components for repairs. Thus, a technical refresh is needed to sustain WSP operations into the future. This phase of the project targets the intermediate frequency digital receiver, the radar interface module, and the digital signal processor for replacement by updated hardware platforms. At the same time, the increase in computational capability allows for an upgrade in the signal processing algorithm, which will lead to data quality improvements.
Summary
The Weather Systems Processor (WSP) is an add-on system to the Airport Surveillance Radar-9 (ASR-9) that generates wind shear detection and storm tracking products for the terminal airspace. As the original system ages and pre-purchased replacement parts in the depot are used up, it becomes increasingly problematic to procure hardware...
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Aircraft in situ validation of hydrometeors and icing conditions inferred by ground-based NEXRAD polarimetric radar
June 15, 2015
Conference Paper
Published in:
SAE Int. Conf. on Icing of Aircraft, Engines, and Structures, ICE 2015, 15 June 2015.
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Summary
MIT Lincoln Laboratory is tasked by the U.S. Federal Aviation Administration to investigate the use of the NEXRAD polarimetric radars for the remote sensing of icing conditions hazardous to aircraft. A critical aspect of the investigation concerns validation that has relied upon commercial airline icing pilot reports and a dedicated campaign of in situ flights in winter storms. During the month of February in 2012 and 2013, the Convair-580 aircraft operated by the National Research Council of Canada was used for in situ validation of snowstorm characteristics under simultaneous observation by NEXRAD radars in Cleveland, Ohio and Buffalo, New York. The most anisotropic and easily distinguished winter targets to dual pol radar are ice crystals. Accordingly, laboratory diffusion chamber measurements in a tightly-controlled parameter space of temperature and humidity provide the linkage between shape and the expectation for the presence/absence of water saturation conditions necessary for icing hazard in situ. In agreement with the laboratory measurements pertaining to dendritic and hexagonal flat plate crystals, the aircraft measurements have verified the presence of supercooled water in mainly low concentrations coincident with regions showing layered anomalies of positive differential reflectivity (ZDR) by ground-based radar, otherwise known as +ZDR 'bright bands'. Extreme values of ZDR (up to +8 dB) have also been found to be coincident with hexagonal flat plate crystals and intermittent supercooled water, also consistent with laboratory measurements. The icing conditions found with the anisotropic description are considered non-classical (condensation/collision-coalescence) and require the ascent of air and availability of ice nuclei. A modest ascent rate (
Summary
MIT Lincoln Laboratory is tasked by the U.S. Federal Aviation Administration to investigate the use of the NEXRAD polarimetric radars for the remote sensing of icing conditions hazardous to aircraft. A critical aspect of the investigation concerns validation that has relied upon commercial airline icing pilot reports and a dedicated...
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Revised multifunction phased array radar (MPAR) network siting analysis
May 26, 2015
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-425
Summary
As part of the NextGen Surveillance and Weather Radar Capability (NSWRC) program, the Federal Aviation Administration (FAA) is currently developing the solution for aircraft and meteorological surveillance in the future National Airspace System (NAS). A potential solution is a multifunction phased array radar (MPAR) that would replace some or all of the single-purpose radar types used in the NAS today. One attractive aspect of MPAR is that the number of radars deployed would decrease, because redundancy in coverage by single-mission sensors would be reduced with a multifunction system. The lower radar count might then result in overall life cycle cost savings, but in order to estimate costs, a reliable estimate of the number of MPARs is needed. Thus this report addresses the question, "If today's weather and aircraft surveillance radars are replaced by a single class of multimission radars, how many would be needed to replicate the current air space coverage over the United States and its territories?" Various replacement scenarios must be considered, since it is not yet determined which of the organizations that own today's radars (the FAA, the National Weather Service (NWS), the different branches of the U.S. military) would join in an MPAR program. It updates a previous study using a revised set of legacy systems, including 81 additional military airbase radars. Six replacement scenarios were considered, depending on the radar mission categories. Scenario 1 would replace terminal radars only, i.e., the Airport Surveillance Radars (ASRs) and the Terminal Doppler Weather Radar (TDWR). Scenario 2 would include the Scenario 1 radars plus the long-range weather radar, commonly known as NEXRAD. Scenario 3 would add the long-range aircraft surveillance radars, i.e., the Air Route Surveillance Radars (ARSRs), to the Scenario 2 radars. To each of these three scenarios, we then add the military's Ground Position Navigation (GPN) airbase radars for Scenarios 1G, 2G, and 3G. We assumed that the new multimission radar would be available in two sizes--a full-size MPAR and a scaled-down terminal MPAR (TMPAR). Furthermore, we assumed that the new radar antennas would have four sides that could be populated by one, two, three, or four phased array faces, such that the azimuthal coverage provided could be scaled from 90 degrees to 360 degrees. Radars in the 50 United States, Guam, Puerto Rico, U.S. Virgin Islands, Guantanamo Bay (Cuba), and Kwajalein (Marshall Islands) were included in the study.
Summary
As part of the NextGen Surveillance and Weather Radar Capability (NSWRC) program, the Federal Aviation Administration (FAA) is currently developing the solution for aircraft and meteorological surveillance in the future National Airspace System (NAS). A potential solution is a multifunction phased array radar (MPAR) that would replace some or all...
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The 2013 Buffalo Area Icing and Radar Study (BAIRS)
March 6, 2015
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-419
Summary
The Next Generation Weather Radar (NEXRAD) network completed a dual polarization upgrade in 2013. The radars now can be used to sense the type of scatterers that cause the radar returns. The scatterers can be hydrometeors, biologicals, or earth-sourced. The ability to reliably interpret the radar-sensed thermodynamic phase of the hydrometeors (solid, liquid, mix) in the context of cloud microphysics and precipitation physics makes it possible to assess the icing hazard potential to aviation. That assessment for Federal Aviation Administration (FAA) purposes would necessarily be performed by automated algorithms based in hydrometeor classification terms. The truth as to the icing hazard aloft (where the radar scans) is required to ascertain the value of such algorithms. The Buffalo Area Icing and Radar Study (BAIRS) of 2013 was a partnership between MIT Lincoln Laboratory (LL) and the National Research Council of Canada (NRC) to perform in situ icing missions within the surveillance range of the dual polarization NEXRAD in Buffalo, NY. The goal of these 2013 missions, and the subject of this report, was to target specific winter weather scenarios known to exhibit an aviation icing hazard for the purpose of quantifying the microphysical properties of the target zones and verifying the presence of supercooled liquid water (SLW) to support validation of hydrometeor classification algorithms. These are the first such missions to execute in situ measurements within a NEXRAD's surveillance range running with the fielded, operational NEXRAD hydrometeor classifier. NRC's Convair-580 instrumented research plane was used for three icing missions covering 14 hours. Three distinctly different winter weather scenarios were encountered. This document details the analysis of in situ data such as particle type and liquid water content (LWC) with NEXRAD dual polarization parameters for the three missions. The BAIRS analysis identified these key findings: -NEXRAD radar returns are prevalent in conditions of supercooled water, -NEXRAD classification shows positive results based on particle imagery, -NEXRAD "dry snow" class masks the presence of mixed phase potential icing hazard, -NEXRAD "unknown" class contains diverse regions of icing hazard potential, and there are methods to classify some of these regions, and -In situ aircraft observations are an important tool to both verify algorithm performance and guide further development.
Summary
The Next Generation Weather Radar (NEXRAD) network completed a dual polarization upgrade in 2013. The radars now can be used to sense the type of scatterers that cause the radar returns. The scatterers can be hydrometeors, biologicals, or earth-sourced. The ability to reliably interpret the radar-sensed thermodynamic phase of the...
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