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Rotating a weather map
June 1, 1999
Journal Article
Published in:
Dr. Dobb's J., Vol. 24, No. 6, June 1999, pp. 80-88.
Summary
Introduction: I was recently part of a project developing a system for aircraft pilots to access the national ground weather-radar database while in flight. This weather-radar graphical database is generated from the outputs of the FAA and National Weather Service network of radars covering the continental United States and is updated every five minutes. Each pixel in the database covers a square measuring two kilometers (about one nautical mile) on a side. The content of each data pixel is a measure of the radar reflectivity measured at that location - radar reflectivity is proportional to the water content in the atmosphere (the precipitation rate). This graphical database is available through several commercial vendors - it's what you see displayed on The Weather Channel or during typical TV weather reports. Our system, on the other hand, provides a low-speed digital datalink connection from an FAA ground computer to an avionics computer/display located in the aircraft cockpit.
Summary
Introduction: I was recently part of a project developing a system for aircraft pilots to access the national ground weather-radar database while in flight. This weather-radar graphical database is generated from the outputs of the FAA and National Weather Service network of radars covering the continental United States and is...
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Review of NYC ITWS during the September 7, 1998 severe weather event
May 26, 1999
Project Report
Published in:
Project Report ATC-269, MIT Lincoln Laboratory
Summary
The New York City Integrated Terminal Weather System (ITWS) prototype became operational for the first time on August 30, 1998. Although this was near the end of the region's convective season, site staff were afforded a unique chance to assess the system's performance during Labor Day weekend on the afternoon of September 7 when a line of severe thunderstorms wreaked havoc over large areas of the Tri-state region. The storm with gusts reported as high as 80 mph, caused fatalities as boats overturned and trees fell on cars. Tornadoes were confirmed over New Jersey and Long Island, with major structural damage occurring in other areas as the result of strong straight-line winds and hail reported as large as 1.75 inches in diameter. Significant airport delays were experienced at the three major New York airports (over 600 flights delayed at least 15 minutes) and several hundred flights were cancelled. This report will assess the performance of ITWS and NEXRAD products during the time severe weather impacted the TRACON area, from about 1700 to 1930 UTC on September 7 (hereafter all times will be given in UTC). It will also discuss the synoptic weather setting and conclude with a section on the operational benefits users derived from ITWS on this day.
Summary
The New York City Integrated Terminal Weather System (ITWS) prototype became operational for the first time on August 30, 1998. Although this was near the end of the region's convective season, site staff were afforded a unique chance to assess the system's performance during Labor Day weekend on the afternoon...
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Total global lightning inferred from Schumann resonance measurements
December 27, 1998
Journal Article
Published in:
J. Geophys. Res., Vol. 103, No. D24, 27 December 1998, pp. 31,775-31,779.
Summary
Radiation with frequencies of 5-30 Hz is ducted between Earth's surface and ionosphere with little attenuation; at the lowest frequencies, waves travel several times around the Earth before losing most of their energy. Much of this radiation is produced by lightning. Here we assume that all of this radiation is produced by lightning, and attempt to invert the observed and electric and magnetic fields to infer global lightning activity. We show 10 days of inversions. For these 10 days, the inferred average rate of vertical charge transfer squared is only 1.7 105 (ten to the fifth) (Ckm)2/s Other studies suggest that the root mean square moment change of a flash is about 166 Coulomb kilometers. If we naively assume that each of these flashes is composed of four equally sized strokes, then we conclude that our entire observed signal could be produced by only 22 flashes per second.
Summary
Radiation with frequencies of 5-30 Hz is ducted between Earth's surface and ionosphere with little attenuation; at the lowest frequencies, waves travel several times around the Earth before losing most of their energy. Much of this radiation is produced by lightning. Here we assume that all of this radiation is...
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Comparisons between total lightning data, mesocyclone strength, and storm damage associated with the Florida tornado outbreak of February 23 1998
September 14, 1998
Conference Paper
Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, pp. 681-684.
Summary
During the late evening and early morning hours of February 22/23 1998, the worst tornado outbreak in recorded history occurred over the peninsula of central Florida. Analysis of KMLB Doppler radar data indicated at least 9 supercells developed over the region, with 4 of the supercells producing tornadoes. These 4 tornadic supercells produced a total of 7 tornadoes, some of them on the ground for tens of miles (Fig. 1.). A total of 42 fatalities were reported with over 260 injured. Monetary losses totaled over 100 million dollars. During this severe weather outbreak, National Weather Service Melbourne, in collaboration with the National Aeronautics and Space Administration and the Massachusetts Institute of Technology, was collecting data from a unique lightning observing system called Lightning Imaging Sensor Data Applications Display (LISDAD). This system has the capability to combine radar reflectivity data collected from the KMLB WSR-88D, cloud to ground data collected from the National Lightning Detection Network, and total lightning data collected from NASA's Lightning Detection And Ranging (LDAR) system. The object of this study is to compare total lightning data collected from the LISDAD system to mesocyclone strength as observed from the KMLB WSR-88D. These data will then be compared to the times of tornadic winds.
Summary
During the late evening and early morning hours of February 22/23 1998, the worst tornado outbreak in recorded history occurred over the peninsula of central Florida. Analysis of KMLB Doppler radar data indicated at least 9 supercells developed over the region, with 4 of the supercells producing tornadoes. These 4...
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Observations of total lightning associated with severe convection during the wet season in Central Florida
September 14, 1998
Conference Paper
Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, 635-638.
Summary
This paper will discuss findings of a collaborative lightning research project between the Massachusetts Institute of Technology, the National Weather Service (NWS) office in Melbourne (MLB), Florida and the National Aeronautics and Space Administration. In August 1996, NWS MLB received a workstation which incorporates data from the KMLB WSR-88D, Cloud to Ground (CG) stroke data from the National Lightning Detection Network (NLDN), and 3D volumetric lightning data collected from the Kennedy Space Centers' Lightning Detection And Ranging (LDAR) system. The two primary objectives of this lightning workstation, called Lightning Imaging Sensor Data Applications Display (L1SDAD), are to: a.) Observe how total lightning relates to severe convective storm morphology over central Florida, and, b.) Compare ground based total lightning data (LDAR) to a satellite based lightning detection system. This presentation will focus on objective #1.
Summary
This paper will discuss findings of a collaborative lightning research project between the Massachusetts Institute of Technology, the National Weather Service (NWS) office in Melbourne (MLB), Florida and the National Aeronautics and Space Administration. In August 1996, NWS MLB received a workstation which incorporates data from the KMLB WSR-88D, Cloud...
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The design and evaluation of the Lightning Imaging Sensor Data Applications Display (LISDAD)
September 14, 1998
Conference Paper
Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, pp. 631-634.
Summary
The ultimate goal of the LISDAD system is to quantify the utility of total lightning infomation in short-term, severe-weather-forecasting operations. Secondary goals were to collect times series of various storm-cell parameters that relate to storm development and electrification and subsequently make these data available for post-facto analysis. To these ends scientists from NASA, NWS, and MIT/LL organized an effort to study the relationship of lightning and severe-weather on a storm-by-storm, and even cell-by-cell basis for as many storms as possible near Melbourne, Florida. Melbourne was chosen as it offers a unique combination of high probability of severe weather and proximity to major relevant sensors, specifically: NASA's total lightning mapping system at Kennedy Space Center (the LDAR system) at KSC [Lennon and Maier, 1991], a NWS / NEXRAD radar at Melbourne, and a prototype Integrated Terminal Weather System (ITWS), at Orlando. The ITWS system obtains cloud-to-ground lightning information from the National Lightning Detection Network (NLDN) via a link to Lexington, MA, and also uses NSSL's Severe Storms Analysis Package (NSSL / SSAP) to obtain information about various storm-cell parameters
Summary
The ultimate goal of the LISDAD system is to quantify the utility of total lightning infomation in short-term, severe-weather-forecasting operations. Secondary goals were to collect times series of various storm-cell parameters that relate to storm development and electrification and subsequently make these data available for post-facto analysis. To these ends...
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Total lightning as a severe weather diagnostic in strongly baroclinic systems in Central Florida
September 14, 1998
Conference Paper
Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, pp. 643-647.
Summary
Severe weather is defined by specific thresholds in wind. hail size and vorticity. All of these phenomena have close physical connections with vertical drafts in deep convection, which are themselves not directly measured with scanning Doppler radars of the NEXRAD type. Cloud electrification and lightning are particularly sensitive to these drafts because they modulate the supply of supercooled water which is the growth agent for the ice particles (ice crystals, graupel and hail) believed essential for electrical charge separation. For these reasons, one can expect correlations at the outset between total lightning activity and the development of severe weather which may aid in the understanding and prediction of these extreme weather conditions. The exploration of these ideas has historically been impeded by lack of good quantitative observations. A recent review of results on severe storm electrification (Williams, 1998) indicates a general absence of cases for which total lightning activity is documented over the lifetime of a severe storm. The recent development of LISDAD (Lightning Imaging Sensor Data Application Display) (Boldi, et aI., 1998) has largely remedied this problem. This paper is concerned with the use of LISDAD to quantify the behavior of total lightning in all types of severe weather, with a focus on a pair of extraordinarily electrified supercells in the Florida dry season.
Summary
Severe weather is defined by specific thresholds in wind. hail size and vorticity. All of these phenomena have close physical connections with vertical drafts in deep convection, which are themselves not directly measured with scanning Doppler radars of the NEXRAD type. Cloud electrification and lightning are particularly sensitive to these...
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Total lightning and radar storm characteristics associated with severe storms in Central Florida
September 14, 1998
Conference Paper
Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, pp. 639-642.
Summary
A number of prior studies have examined the association of lightning activity with the occurrence of severe weather and tornadoes, in particular. High flash rates are often observed in tornadic storms but not always. Taylor found that 23% of nontornadic storms and I% of non-severe storms had sferics rates comparable to the tornadic storms. MacGorman (1993) found that storms with mesocyclones produced more frequent intracloud (lC) lightning than cloud-ta-ground (CG) lightning. MacGorman (1993) and others suggest that the lightning activity accompanying tornadic storms will be dominated by intracloud lightning- with an increase in intracloud and total flash rates as the updraft increases in depth, size, and velocity. In a recent study, Perez et aI. (1998) found that CG flash rates alone are too variable to be a useful predictor of (F4, F5) tornado formation. Studies of non-tornadic storms have also shown that total lightning flash rates track the updraft, with rates increasing as the updraft intensifies and decreasing rapidly with cessation of vertical growth or downburst onset (Goodman et aI., 1988; Williams et aI., 1989). Such relationships result from the development of mixed phase precipitation and increased hydrometeor collisions that lead to the efficient separation of charge. Correlations between updraft strength and other variables such as cloud-top height, cloud water mass, and hail size have also been observed. In this paper we examine the total lightning activity (with high time resolution), and the associated Doppler radar time history of weaker (FO, Fl) tornadic storms in Florida. Much of the prior work has focused on tornadic supercells in the Great Plains.
Summary
A number of prior studies have examined the association of lightning activity with the occurrence of severe weather and tornadoes, in particular. High flash rates are often observed in tornadic storms but not always. Taylor found that 23% of nontornadic storms and I% of non-severe storms had sferics rates comparable...
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Terminal Weather Information for Pilots (TWIP) Program Annual Report for 1995
September 8, 1997
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-253
Topic:
R&D area:
Summary
The Federal Aviation Administration (FAA) is currently embarking on programs, such as the Terminal Doppler Weather Radar (TDWR) and Integrated Terminal Weather Systems (ITWS), that will significanlty improve the aviation weather information in the terminal area. For example, TDWR data will be available at 47 airports across the United States that have high traffic and significant risk of wind shear. The TDWRs automatically report microburst, gust front and precipitaion near the airport to air traffic control personnel on a 24-hour basis. Given the great increase in the quantity and quality of terminal weather information, it is highly desirable to provide this information directly to pilots rather than relying on voice communications. Providing terminal weather information automatically via data link will enhance pilot awareness of weather hazards and lead to more efficient utilization of aircraft. It may also decrease air traffic controller workload and reduce ratio frequency congestion. This report describes work performed in 1995 to provide direct pilot access to terminal weather information via an existing data link known as ACARS (Aircraft, Communication Addressing and Reporting System). More than 4000 aircraft operate in the United States with ACARS equipment. During 1995, five Lincoln-operated testbeds provided near real-time terminal weather information to pilots of AFCARS-equipped aircraft in both text and character graphics formats. This effort follows earlier successful demonstrations during the summers of 1993 and 1994. Section 2 of the report describes the TWIP message formats, Section 3 discusses the 1995 operational demonstration, and Section 4 presents TWIP software design. Section 5 provides case analyses from the 1995 demonstration, Section 6 discusses future work, and Section 7 is the summary.
Summary
The Federal Aviation Administration (FAA) is currently embarking on programs, such as the Terminal Doppler Weather Radar (TDWR) and Integrated Terminal Weather Systems (ITWS), that will significanlty improve the aviation weather information in the terminal area. For example, TDWR data will be available at 47 airports across the United States...
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Initial comparison of lightning mapping with operational time-of-arrival and interferometric systems
May 27, 1997
Journal Article
Published in:
J. Geophys. Res., Vol. 102, No. D10, 27 May 1997, pp. 11,071-11,085.
Summary
The mapping of lightning radiation sources produced by the operational Time-of-Arrival National Aeronautics and Space Administration/Lightning Detection and Ranging (NASA/LDAR) system is compared with that of the Interferometric French Office National D'Etudes et de Recherches Aerospatiales (ONERA-3D) system. The comparison comprises lightning activity in three Florida storms and also individual flashes in one of these storms. Although limited in scope, the comparison analysis show a significant difference in the representation of lightning radiation by each mapping system. During the duration of a flash, the LDAR data show a continuity in time and a three-dimensional structure of radiation sources. The ONERA-3D radiation source data are more intermittent in time and have a more two-dimensional structure. The distinction between the radiation sources mapped by the two systems is also reflected in the difference between their propagation speeds, 10^4-10^5 m s^-1, estimated by the LDAR system, and 10^7-10^8 m s^-1, estimated by the ONERA-3D system. We infer that this difference occurs because most of the radiation sources mapped with LDAR are associated with virgin breakdown processes typical of slowly propagating negative leaders. On the other hand, most of the radiation sources mapped with ONERA3D are produced by fast intermittent negative breakdown processes typical of dart leaders and K changes as they traverse the previously ionized channels. Thus each operational system may emphasize different stages of the lightning flash, but neither appears to map the entire flash.
Summary
The mapping of lightning radiation sources produced by the operational Time-of-Arrival National Aeronautics and Space Administration/Lightning Detection and Ranging (NASA/LDAR) system is compared with that of the Interferometric French Office National D'Etudes et de Recherches Aerospatiales (ONERA-3D) system. The comparison comprises lightning activity in three Florida storms and also individual...
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