The multi-parameter remote measurement of rainfall

The measurement of rainfall by remote sensors is investigated. One parameter radar rainfall measurement is limited because both reflectivity and rain rate are dependent on at least two parameters of the drop size distribution (DSD), i.e., representative raindrop size and number concentration. A generalized rain parameter diagram is developed which includes a third distribution parameter, the breadth of the DSD, to better specify rain rate and all possible remote variables. Simulations show the improvement in accuracy attainable through the use of combinations of two and three remote measurables. The spectrum of remote measurables is reviewed. These include path integrated techniques of radiometry and of microwave and optical attenuation

Radar-based Hail-producing Storm Detection Using Positive Unlabeled Classification

Machine learning methods have been widely used in many fields of weather forecasting. However, some severe weather, such as hailstorm, is difficult to be completely and accurately recorded. These inaccurate data sets will affect the performance of machine-learning-based forecasting models. In this paper, a weather-radar-based hail-producing storm detection method is proposed. This method utilizes the bagging class-weighted support vector machine to learn from partly labeled hail case data and the other unlabeled data, with features extracted from radar and sounding data. The real case data from three radars of North China are used for evaluation. Results suggest that the proposed method could improve both the forecast accuracy and the forecast lead time comparing with the commonly used radar parameter methods. Besides, the proposed method works better than the method with the supervised learning model in any situation, especially when the number of positive samples contaminated in the unlabeled set is large

Turbulence as observed by concurrent measurements made at NSSL using weather radar, Doppler radar, Doppler lidar and aircraft

As air traffic increases and aircraft capability increases in range and operating altitude, the exposure to weather hazards increases. Turbulence and wind shears are two of the most important of these hazards that must be taken into account if safe flight operations are to be accomplished. Beginning in the early 1960's, Project Rough Rider began thunderstorm investigations. Past and present efforts at the National Severe Storm Laboratory (NSSL) to measure these flight safety hazards and to describe the use of Doppler radar to detect and qualify these hazards are summarized. In particular, the evolution of the Doppler-measured radial velocity spectrum width and its applicability to the problem of safe flight is presented

Relationship between hailfall intensity and hail damage on ground, determined by radar and lightning observations

Wetterradargeräte werden mittlerweile in vielen Ländern zur Beobachtung und Messung von Hagelstürmen verwendet und liefern einen detaillierten Überblick über die Entwicklung und die Struktur von starken Gewittern. Viel Aufwand wurde in die quantitative Messung von Hagelschlägen und Kurzfristprognosen (Nowcasting) von hagelträchtigen Gewittern investiert, was für nationale Wetterdienste und Flughäfen (Warnungen), die Landwirtschaft (Hagelschutz) und Versicherungen (Schadenabschätzung und Prävention) von grossem Interesse ist. Obwohl Dual-Polarisation Techniken in letzter Zeit entscheidend verbessert wurden, basieren Methoden zur Hagelerkennung und –messung immer noch auf Single-Polarisations Radargeräten. Eine der besten Methoden zur Bestimmung der Hagelintensität mit Single-Polarisation Radargeräten ist die kinetische Hagelenergie, die aus der Radarreflektivität berechnet wird und das gesamte Hagelvolumen pro Fläche repräsentiert. Es hat sich gezeigt, dass die radarvermessene kinetische Hagelenergie (EKINPIX) gut mit Bodenmessungen von Hagel (Hailpads) und Hagelschäden an landwirtschaftlichen Kulturen korreliert. Aufgrund der guten Beziehung zwischen radar- und bodenvermessener Hagelintensität, wird EKINPIX in dieser Dissertation in Beziehung zu Hagelschäden an Autos, an Gebäuden und zur Häufigkeit von Wolken-Boden Blitzen (WB) gesetzt und anhand einer grossen Anzahl Hagelzellen analysiert. Die Dissertation besteht aus den folgenden drei Teilen: einer Einführung, drei wissenschaftlichen Publikationen (eingereicht oder publiziert in (Athmospheric Research) die in einzelnen Kapiteln wiedergegeben sind, und einem abschliessenden Kapitel, in dem zwei methodische Ansätze wie aus räumlichen Verteilungen von WB Blitzen gesamte Hagelflächen abgeleitet werden könnten. Artikel 1 zeigt die Beziehung zwischen Hagelintensitäten und Hagelschäden an Autos, während in Artikel 2 der Zusammenhang mit Schäden an Wohn- und Landwirtschaftsgebäuden untersucht wird. Die Radardaten stammen vom C-Band Doppler-Radar, der von der Eidgenössischen Technischen Hochschule (ETH) in der Nähe von Zürich (Schweiz) betrieben wird. Hagelschäden an Autos waren durch die Winterthur Versicherungen (1992-1998) und Hagelschäden an Gebäuden durch verschiedene Kantonale Gebäudeversicherungen (1992-1999) erhältlich. Die Beziehung zwischen Hagelintensitäten (EKINPIX) und Schäden an Autos (Gebäuden) wurden für 12 (neun) Hagelzellen analysiert, mit den folgenden Resultaten: Da das Ausmass eines Hagelschadens sehr stark vom Exposure und den physikalischen Eigenschaften der versicherten Objekte abhängt, wurden verschiedene Annahmen getroffen und Vereinfachungen eingeführt. Die Beziehung zwischen den mittleren Schäden und EKINPIX hängt von der Hagelsaison ab: Hagelzellen der Hauptsaison (15. Juni-15. August) produzierten generell höhere Schäden als Gewitter der Nebensaison (vorher und nachher). Ein saisonaler Unterschied in der Hagelintensität zeigt sich auch aus der Anzahl und der maximalen Hagelkorngrösse von Hailpad Daten, die aus dem Grossversuch IV stammen, welcher in der Zentralschweiz durchgeführt wurde (1976-1983). Die nicht-linearen Beziehungen zwischen EKINPIX und den Schadenvariablen lassen sich am besten mit logistischen Funktionen beschreiben, wobei Korrelationskoeffizienten von 0.80 resultieren. Nach entsprechender Verifikation und Kalibrierung generierten die logistischen Funktionen für die Schadenrate (Verhältnis zwischen Schäden und Gesamtversicherungssumme) Schäden an Wohn- und Landwirtschaftsgebäuden, die in der Grössenordnung der tatsächlich vorgekommenen Schäden liegen. Der relative Fehler zwischen realen und mit den Schadenfunktionen geschätzten Schäden liegt für die stärksten Stürme unter 30%. Die erarbeiteten logistischen Schadenfunktionen zwischen radarvermessener kinetischen Hagelenergie und Hagelschäden könnten von Versicherungen zur Bestimmung von maximal möglichen Schäden (PMLs) gebraucht werden, indem eine radarvermessene Hagelzelle über ein Auto- und/oder Gebäudeportefeuille eines bestimmten Gebietes (z.B. einer grösseren Stadt) verschoben werden kann. In Artikel 3 werden WB Blitze, die von den Blitzmessnetzen der Schweiz und Süddeutschland geortet wurden, miteinander verglichen, um eine Angabe über die relative Erfassungseffizienz zu erhalten. WB Blitzmessungen des Schweizer Ortungssystems werden einzelnen Hagelzellen (5 min. Auflösung) zugeordnet, so dass der gesamte Lebenszyklus einer Zelle erfasst und in Beziehung zur radarvermessenen kinetischen Hagelenergie (ETH C-Band Doppler-Radar) gesetzt werden kann. Die Auswertung von 41 Hagelzellen die über das Schweizer Mittelland gezogen sind (1992-1995), zeigt die folgenden Resultate: Die totale kinetische Hagelenergie steht in einer linearen Beziehung (Korrelationskoeffizient von 0.95) mit der totalen Anzahl negativer WB Blitzen (–WB). Kein direkter Zusammenhang wurde dagegen mit der Anzahl positive geladener WB Blitzen (+WB) gefunden, obwohl zwischen verschiedenen Gewittertypen unterschieden wurde. Positionen von maximaler Hagelintensität korrelieren mit zeitlichen (0.88) und räumlichen (0.84) Höchstwerten in der Häufigkeit von –WB Blitzen. Die meisten Hagelzellen (66%) zeigen, dass –WB Blitze im Mittel 22 min. (0-65 min.) und 19 km (3-58 km) vor der höchsten Hagelintensität vorkommen. Im Bezug zur maximalen Hagelenergie zeigt sich eine grosse Varianz in Positionen von Höchstwerten in der Anzahl von +WB Blitzen. In schwachen Hagelzellen befindet sich der Höchstwert von +WB Blitzen im Mittel 10 min. vor und 3.5 km nach der höchsten Hagelintensität. In grossen isolierten Zellen liegt hingegen die Position der meisten +WB Blitze 30 min. und 45 km nach der höchsten Hagelintensität. Die Resultate der relativ grossen Anzahl untersuchter Gewitter bestätigen den Einfluss des nicht-induktiven Graupel-Eis Ladungsmechanismus. Dieser erklärt die Tatsache, dass die Mehrheit der –WB Blitze zu Beginn der Gewitterentwicklung vorkommen, während die meisten +WB Blitze eher am Ende der Gewittertätigkeit, während einer Umkehrung der Ladungsteilung beim Ausfall des Niederschlags, auftreten. Die zeitliche und räumliche Beziehung zwischen Höchstwerten von WB Blitzen und maximaler Hagelintensität könnte in der Zukunft für die Verbesserung der Kurzvorhersagen (Nowcasting) von starken Gewittern verwendet werden, speziell durch eine frühere Erkennung eines Hagelschlags anhand von WB-Blitz Informationen. Im letzten Kapitel wird die räumliche Beziehung zwischen Mustern von –WB Blitzen und radarvermessener kinetischer Hagelenergie für 18 ausgewählte Hagelzellen untersucht. Kreuzkorrelationen zwischen den Blitz- und Energiemuster ergeben Koeffizienten zwischen 0.33 und 0.66, was ein vielversprechender Ansatz für eine direkte Bestimmung von Hagelflächen mittels Blitzdaten ist. Zwei methodische Ansätze zur räumlichen Verteilung der Hagelenergie werden in diesem Kapitel diskutiert, wobei die vollständige Ausarbeitung der Methoden nicht mehr im Rahmen dieser Arbeit liegt. Falls dies jedoch gelingt, können Hagelflächen für grosse Gebiete bestimmt werden, ohne direkt auf Radardaten angewiesen zu sein.Weather radars are now available in many countries for operational observations and measurements of hailstorms and provide detailed information on the formation and structure of severe thunderstorms. Much research has been devoted to the quantitative measurement of hailfalls and the nowcasting of hail-bearing thunderstorms which is of interest for national weather services and airports (warning), the agricultural community (protection) and the insurance industry (damage estimation and mitigation). Although dual-polarization techniques have been improving in recent years, hail detection and measuring methods still have to rely on single-polarization radars. One of the most successful methods to derive hailfall intensities from single-polarization radars is hail kinetic energy that is calculated from radar reflectivity measurements and represents the total volume of hailfall per surface unit. Radar-derived hail kinetic energy (EKINPIX) showed valuable results in relation to ground-based measurements of hailfalls (hailpads) and amounts of hail damage to various crops. Based on the good agreement between radar- and ground-measured hailfall intensity, EKINPIX is related in this thesis to hail damage amounts on automobiles, buildings and cloud-to-ground (CG) lightning activity in analyzing a large number of radar-measured hail cells. The thesis consists of three parts: an introduction, three articles (submitted or published in Atmospheric Research) that are reproduced in individual chapters and a final chapter that presents two methodological approaches of how CG lightning location data could be used in the future to directly determine hailfall areas. Article 1 deals with the relationship between hailfall intensities and damages to automobiles, whereas Article 2 investigates a corresponding relationship for residential and agricultural buildings in Switzerland. Radar measurements were available from the C-band Doppler radar located at the Swiss Federal Institute of Technology (ETH) near Zurich, Switzerland. Damage claim data on automobiles were available from Winterthur Insurance (1992-1998) and several cantonal building insurance companies provided hail damage data of buildings (1992-1999). Relationships between hailfall intensity (EKINPIX) and damages to automobiles (buildings) have been analyzed for 12 (nine) hail cells with the following result: As the amount of hail damage depends strongly on the exposure and the physical characteristics of the units insured, some assumptions and simplifications were necessary. The relationship between mean damages and EKINPIX depends on the hailstorm season: high season storms (15 June-15 August) produced higher damages than low season storms vi (before and after). A seasonal difference in hailfall intensity between high and low season storm appears also from numbers and maximum hailstone diameters that were available from hailpad measurements conducted during Grossversuch IV in central Switzerland (1976-1983). The nonlinear relationships between EKINPIX and the damage variables are best described by logistic damage functions that yield correlation coefficients of 0.80. After suitable verification and calibration, logistic functions for total loss ratios (ratio between damage amounts and total sums insured) of both residential and agricultural buildings, predicted damages that are in the range of occurred losses from hailfall. Relative prediction errors for the most severe hailstorms are below 30%. The results suggest that the established logistic damage functions between radar-derived hail kinetic energy and hail damage amounts could be used by insurance companies to determine possible maximum losses (PMLs), shifting a radar-measured hail cell over a motor and/or a building portfolio of interest (e.g., over a major city). In Article 3, CG lightning measurements from Lightning Location and Tracking Systems (LPATS) of Switzerland and southern Germany are compared to determine relative detection efficiencies. CG lightning measurements of the Swiss LPATS are attributed to individual hail cells (5-min resolution), so that the entire lifecycle can be assessed and be related to radar-derived hail kinetic energy (ETH C-band Doppler radar). Analyzes of 41 hail cells that propagated over the Swiss Mittelland (1992-1995) show the following key results: Total hail kinetic energy (EKINTOT) shows good linear correspondence (correlation coefficient of 0.95) with totals of negative CG (–CG) stroke counts but reveals no direct relationship regarding positive CG (+CG) stroke totals, although hail cells were stratified according to the type of cell organization. Temporal and spatial locations of maximally expected hailfall correlate with temporal (0.88) and spatial (0.84) peaks of –CG strokes. Most hail cells (66%) show –CG stroke peaks on the average 22 min (0-65 min) and 19 km (3-58 km) prior to maximally expected hailfall. Locations of +CG stroke peaks reveal large variance relative to maximally expected hailfall. +CG strokes in weak cells tend to peak on the average 10 min before and 3.5 km after maxima in hail kinetic energy, whereas +CG stroke peaks in strong large isolated cells lag maximally expected hailfall up to 30 min and 45 km. The results of the relatively large data sample confirm the importance of the non-inductive graupel-ice charging mechanisms that explains the majority of –CG strokes at the beginning of thunderstorm development and the fact that most CG discharges are of positive polarity at mature storm phase, when an electrical charge reversal occurs in the thunderstorm with the fallout of precipitation. The spatial-temporal relationship between peaks in CG strokes and maximum hailfall intensity could be used to improve nowcasting systems of severe thunderstorms, particularly through an increase of the time of onset between CG lightning initiation and the fallout of hail. In the last chapter, the spatial relationship between patterns of –CG strokes and radar-derived hail kinetic energy is analyzed for 18 selected hail cells. Cross-correlations between lightning and energy patterns produced coefficients between 0.33 and 0.66, which are the basis for a promising approach to determine hailfall surfaces directly from lightning location data. This chapter shows two methodological approaches of how hail kinetic energy could be distributed in space, whereas the full implementation of these methods is not covered in the thesis. Once accurate methods are available, it would be possible to determine entire areas of hailfall without relying on radar data

Precipitation observations from high frequency spaceborne polarimetric synthetic aperture radar and ground-based radar: theory and model validation

2010 Fall.Includes bibliographical references.Global weather monitoring is a very useful tool to better understand the Earth's hydrological cycle and provide critical information for emergency and warning systems in severe cases. Developed countries have installed numerous ground-based radars for this purpose, but they obviously are not global in extent. To address this issue, the Tropical Rainfall Measurement Mission (TRMM) was launched in 1997 and has been quite successful. The follow-on Global Precipitation Measurement (GPM) mission will replace TRMM once it is launched. However, a single precipitation radar satellite is still limited, so it would be beneficial if additional existing satellite platforms can be used for meteorological purposes. Within the past few years, several X-band Synthetic Aperture Radar (SAR) satellites have been launched and more are planned. While the primary SAR application is surface monitoring, and they are heralded as "all weather'' systems, strong precipitation induces propagation and backscatter effects in the data. Thus, there exists a potential for weather monitoring using this technology. The process of extracting meteorological parameters from radar measurements is essentially an inversion problem that has been extensively studied for radars designed to estimate these parameters. Before attempting to solve the inverse problem for SAR data, however, the forward problem must be addressed to gain knowledge on exactly how precipitation impacts SAR imagery. This is accomplished by simulating storms in SAR data starting from real measurements of a storm by ground-based polarimetric radar. In addition, real storm observations by current SAR platforms are also quantitatively analyzed by comparison to theoretical results using simultaneous acquisitions by ground radars even in single polarization. For storm simulation, a novel approach is presented here using neural networks to accommodate the oscillations present when the particle scattering requires the Mie solution, i.e., particle diameter is close to the radar wavelength. The process of transforming the real ground measurements to spaceborne SAR is also described, and results are presented in detail. These results are then compared to real observations of storms acquired by the German TerraSAR-X satellite and by one of the Italian COSMO-SkyMed satellites both operating in co-polar mode (i.e., HH and VV). In the TerraSAR-X case, two horizontal polarization ground radars provided simultaneous observations, from which theoretical attenuation is derived assuming all rain hydrometeors. A C-band fully polarimetric ground radar simultaneously observed the storm captured by the COSMO-SkyMed SAR, providing a case to begin validating the simulation model. While previous research has identified the backscatter and attenuation effects of precipitation on X-band SAR imagery, and some have noted an impact on polarimetric observations, the research presented here is the first to quantify it in a holistic sense and demonstrate it using a detailed model of actual storms observed by ground radars. In addition to volumetric effects from precipitation, the land backscatter is altered when water is on or near the surface. This is explored using TRMM, Canada's RADARSAT-1 C-band SAR and Level 3 NEXRAD ground radar data. A weak correlation is determined, and further investigation is warranted. Options for future research are then proposed

Relationships between kinematics, microphysics, and lightning in high plains storms observed during the severe thunderstorm electrification and precipitation study

Summer 2006.Includes bibliographical references (pages 168-169).The Severe Thunderstorm Electrification and Precipitation Study (STEPS) was established to improve our understanding of electrification mechanisms and lightning in High Plains storms. In particular, STEPS focused on investigating anomalous positive cloud-to-ground (CG) lightning, which had been documented to occur more often in this region than in the rest of the U.S. Radar and lightning observations of four storms observed during the STEPS field campaign are analyzed and discussed. The four cases include a predominantly positive CG-producing (PPCG) supercell on 29 June, a supercell on 3 June that produced no CG lightning of either polarity, a negative CG-producing multicellular storm on 19 June, and a PPCG multicellular storm on 22 June. Data from multiple Doppler radars have been synthesized to calculate the three-dimensional wind field, polarimetric radar variables have been combined with thermodynamic soundings to estimate hydrometeor types throughout the echo volumes, and Lightning Mapping Array (LMA) data have been sorted into flashes and studied to determine the flash rates and charge structure for several hours of each storm's lifetime. The purpose of this study is to determine what features are unique for storms that produce predominantly positive CG lightning, and attempt to reveal the processes that lead to this behavior. The 29 June supercell produced large amounts of hail and frequent positive CG lightning, as well as exhibited a large volume of strong (> 10 m S-1) updraft and a deep region of cyclonic vertical vorticity. The charge structure of the 29 June supercell was inverted, with a main region of positive charge centered near 8 km MSL with a negative charge layer above and below. The inferred charge structure in the 3 June case consisted of an inverted dipole, with positive charge beneath upper-level negative charge. A lower negative charge layer was not detected in 3 June and may have been the reason for the lack of CG lightning. This case produced some hail, but not as much hail volume as 29 June, and the updraft volume and cyclonic vertical vorticity were dramatically lower as well. The 19 June multicellular storm exhibited a normal charge structure, with main negative charge centered at 7 km MSL, and positive charge layers above and below, and therefore produced mostly negative CG lightning. The storm produced negligible hail, and had very weak and shallow updrafts, yielding near zero values of strong updraft volume. The 22 June multicellular storm exhibited both inverted and normal charge structures in different regions of the storm complex. The volume of strong updraft was very high, similar to that of 29 June, and the storm produced ample amounts of hail. Both positive and negative CG lightning was observed in this storm complex, but the majority of the CG lightning was of positive polarity. The results indicate that PPCG storms tend to have larger updrafts (both wider and larger in volume), which is consistent with previous studies. Large updrafts and enhanced vertical vorticity also play an important role in the production of large hail. Furthermore, low-level negative charge (below a larger region of positive charge) was observed in the cases that produced positive CG lightning, which may be the impetus needed for the flash to come to ground. This lower negative charge, in essence, represents the lowest charge layer of an inverted tripolar charge structure. The charge structures observed during the production of negative CG lightning were a normal tripole (with negative charge situated between upper and lower positive charge layers) on 19June and an inverted dipole (with negative charge above positive) in the anvil on 22 June. Cloud-to-ground flash rates (of either polarity) decreased when either the lower charge layer of the corresponding tripolar structure was absent, or when the low-level charge layer exhibited an enhanced number of LMA sources, in which case intra-cloud (IC) discharges seemed to be preferred between the two lowest charge layers of the tripole

Kinematic and microphysical evolution of the 29 June supercell observed during STEPS

Spring 2003.Also issued as Sarah A. Tessendorf's thesis (M.S.) -- Colorado State University, 2003.Includes bibliographical references.The focus of this thesis is to examine the kinematic and microphysical properties of a severe storm using polarimetric and Doppler radar data. The data were collected during the Severe Thunderstorm Electrification and Precipitation Study (STEPS) that took place between 17 May 2000 and 20 July 2000 in eastern Colorado and western Kansas. One goal of STEPS is to find a relationship between the microphysics and kinematics of severe storms on the High Plains and their unusual positive cloud-to­ ground lightning production. The severe storm observed on 29 June 2000 produced large hail, frequent positive cloud-to-ground lightning, an F1 tornado, and displayed characteristic storm splitting evolution during the sampling period. Unprecedented measurements from three Doppler radars were used to describe the kinematics and rnicrophysics of this storm. Radial components of the wind fields relative to the three Doppler radars were combined to produce the three-dimensional winds in the storm. Bulk precipitation types (e.g., rain, hail) were objectively determined using the multi­ parameter variables available on two of the radars. The Doppler-derived kinematic fields were compared with the microphysical classifications over a nearly three-hour period to examine trends during the lifecycle of the supercell. Results showed that the supercell intensified rapidly while storm splitting occurred. Prior to splitting, there was little cloud-to-ground lightning and little evidence of hail aloft. After storm splitting. hail volume and cloud-to-ground lightning activity quickly intensified. The updraft of this storm pulsated, with maximum speeds to nearly 50 m s·1. The peaks in hail production aloft, largely around -10° C, were well correlated with the updraft fluctuations as well as with peaks in the frequency of positive cloud-to­ ground lightning flashes. These results are consistent with experimental work that shows positive charging in ice-ice collisions around -10° C. The dynamics of the storm-splitting process, in terms of radar-derived updraft and vorticity fields, were shown to be consistent with current conceptual models. The results of this thesis advance our knowledge of supercell evolution and will be used to help determine the electrification mechanisms of severe storms that produce predominantly positive cloud-to-ground lightning.Sponsored by the National Science Foundation under grant ATM-9912051

Analysis of the first gigantic jet recorded over continental North America

[1] Two low-light cameras near Marfa, Texas, recorded a gigantic jet over northern Mexico on 13 May 2005 at approximately 0423:50 UTC. Assuming that the farthest of two candidate storm systems was its source, the bright lower channel ended in a fork at around 50–59 km height with the very dim upper branches extended to 69–80 km altitude. During the time window containing the jet, extremely low frequency magnetic field recordings show that there was no fast charge moment change larger than 50 coulomb times kilometers (C km) but there was a larger and slower charge moment change of 520 C km over 70 ms. The likely parent thunderstorm was a high-precipitation supercell cluster containing a persistent mesocyclone, with radar echo tops of at least 17 km. However, photogrammetric analysis suggests that the gigantic jet occurred over the forward flank downdraft region with echo tops of 14 km. This part of the supercell may have had an inverted-polarity charge configuration as evidenced by positive cloud-to-ground lightning flashes (+CG) dominating over negative flashes (-CG), while -CGs occurred under the downwind anvil. Four minutes before the gigantic jet, -CG activity practically ceased in this area, while +CG rates increased, culminating during the 20 s leading up to the gigantic jet with four National Lightning Detection Network–detected +CGs. A relative lull in lightning activity of both polarities was observed for up to 1.5 min after the gigantic jet. The maturing storm subsequently produced 30 sprites between 0454 and 0820 UTC, some associated with extremely large impulse charge moment change values.Peer ReviewedPostprint (published version

Summary of the High Ice Water Content (HIWC) RADAR Flight Campaigns

NASA and the FAA conducted two flight campaigns to quantify onboard weather radar measurements with in-situ measurements of high concentrations of ice crystals found in deep convective storms. The ultimate goal of this research was to improve the understanding and develop onboard weather radar processing to detect regions of high ice water content ahead of an aircraft and enable tactical avoidance of the potentially hazardous conditions. Both High Ice Water Content (HIWC) RADAR campaigns utilized the NASA DC-8 Airborne Science Laboratory which was equipped with a Honeywell RDR-4000 weather radar and icing instruments to characterize the ice crystal clouds. The purpose of this paper is to summarize how these campaigns were conducted and highlight key results