A study of the thunderstorm and cloud-ground lightning characteristics associated with sprite events observed in Brazil is presented. The study is based on ground and aircraft sprite observations with high sensitivity intensified CCD cameras of six different thunderstorms, GOES satellite infrared images, radar and lightning network data. A total of eighteen transient optical events were recorded at three different days in 2002 and 2003, sixteen of which exhibited vertical structures typically associated with sprites. Four thunderstorms were associated with two different cold fronts, one with a Mesoscale Convective System, and one was a local isolated thunderstorm. The sprites occurred during time periods when the percentage of positive flashes was higher than the average percentage for the storm lifetime. The lightning associated with the sprite events was all positive flashes with a mean peak current higher than the mean value for all flashes in the storms

Holzworth, R. H.

Naccarato, K. P.

Pautet, P. D.

Pinto Jr., O.

Pinto, I. R.C.A.

Saba, M. M.F.

Solorzano, N. N.

Tavares, F. S.S.

Taylor, Michael J.

English

DigitalCommons@USU

Thunderstorm and lightning characteristics associated with sprites inBrazilO. Pinto Jr., M. M. F. Saba, I. R. C. A. Pinto, F. S. S. Tavares, K. P. Naccarato,and N. N. SolorzanoNational Institute of Space Research (INPE), Sa˜o Jose dos Campos, Sao Paulo, BrazilM. J. Taylor and P. D. PautetSpace Dynamics Laboratory, Utah State University, Logan, Utah, USAR. H. HolzworthDepartment of Earth and Space Sciences, University of Washington, Seattle, Washington, USAReceived 14 April 2004; revised 25 May 2004; accepted 9 June 2004; published 14 July 2004.[1] A study of the thunderstorm and cloud-ground lightningcharacteristics associated with sprite events observed inBrazil is presented. The study is based on ground and aircraftsprite observations with high sensitivity intensified CCDcameras of six different thunderstorms, GOES satelliteinfrared images, radar and lightning network data. A totalof eighteen transient optical events were recorded at threedifferent days in 2002 and 2003, sixteen of which exhibitedvertical structures typically associated with sprites. Fourthunderstorms were associated with two different cold fronts,one with a Mesoscale Convective System, and one was alocal isolated thunderstorm. The sprites occurred during timeperiods when the percentage of positive flashes was higherthan the average percentage for the storm lifetime. Thelightning associated with the sprite events was all positiveflashes with a mean peak current higher than the mean valuefor all flashes in the storms. INDEX TERMS: 3304Meteorology and Atmospheric Dynamics: Atmospheric electricity;3314 Meteorology and Atmospheric Dynamics: Convectiveprocesses; 3324 Meteorology and Atmospheric Dynamics:Lightning; 3334 Meteorology and Atmospheric Dynamics:Middle atmosphere dynamics (0341, 0342). Citation: Pinto, O.,Jr., M. M. F. Saba, I. R. C. A. Pinto, F. S. S. Tavares, K. P.Naccarato, N. N. Solorzano, M. J. Taylor, P. D. Pautet, and R. H.Holzworth (2004), Thunderstorm and lightning characteristicsassociated with sprites in Brazil, Geophys. Res. Lett., 31,L13103, doi:10.1029/2004GL020264.1. Introduction[2] Since the first documented observation of sprites byFranz et al. [1990], optical observations of sprites havebeen carried out around the world. A review of the principalobservations is given by Rodger [1999]. In the SouthAmerica, however, only a few evidences have beenreported. The first observations were made by Sentman etal. [1995b] with a camera on an airplane near Peru, and byBoeck et al. [1995] from the Space Shuttle. Sentman et al.[1995a] found from 25 groups of events that the spriteswere similar to those reported previously in the UnitedStates. More recently, Blanc et al. [2004] have reportedsprite observations over Brazil using a camera on the ISSand Israelevich et al. [2004] have reported observationsof ELVES also in Brazil during the MEIDEX experiment(no sprite observations were done - Yoav Yair, privatecommunication).[3] Considering that a recent evidence seems to suggestthat the South America is one of the main regions in terms ofsprite occurrences [Sato and Fukunishi, 2003], more infor-mation on sprites in this region can be very important toevaluate their impact on the global circuit. With this goal, theBrazilian Institute of Space Research have initiated in 2002a campaign to observe sprites and other atmospheric relatedparameters in Brazil (R. H. Holzworth et al., Strong electricfields from positive lightning strokes in the stratosphere,submitted to Geophysical Research Letters, 2004). Theobservations during this campaign are the first observationsof sprites in Brazil from cameras on ground and airplanes.[4] In addition, the thunderstorm and lightning character-istics associated with sprites have also been extensivelystudied by several authors [e.g., Lyons, 1996; Lyons et al.,2002, 2003; Tavares et al., 2003]. In general, they foundthat most sprites are associated with positive cloud-to-ground (CG) flashes with peak current values from 10 kAto more than 100 kA. For a given storm, however, theyfound that the average intensity of the parent flashes tendsto be larger than the average of all positive flashes of thestorm. For the previous South American sprite observations,however, no lightning data were available.[5] In this paper, the lightning characteristics associatedwith six thunderstorms that produce 18 transient opticalevents were analyzed. The 18 events were recorded atthree different days in 2002 and 2003 by the Utah StateUniversity team; 16 exhibited vertical structures typicallyassociated with sprites, while the other two were disc-likeevents, characteristic of sprite halo or elves. All eventsappear just in one or two consecutive frames, implying thatthe duration of the events were shorter than 66 ms, andoccur in the mature-to-late stages of the storms. Figure 1shows an example of a sprite recorded in 25 November2002 at 02:49 UT. Table 1 summarizes all informationrelated to the 18 events, including date, time of the spritein UT, peak current of the causative positive flash (14 cases),sprite type, location of the camera and storm identificationnumber. The lightning data were obtained by a network ofGEOPHYSICAL RESEARCH LETTERS, VOL. 31, L13103, doi:10.1029/2004GL020264, 2004Copyright 2004 by the American Geophysical Union.0094-8276/04/2004GL020264L13103 1 of 423 Impact and LPATS sensors located in the Southeast andsurrounding regions of Brazil. In all cases in Table 1 that asprite-parent lightning was identified, the delay time be-tween the time of the sprite and the time of the lightningevent was lower than 10 ms.2. Lightning Data[6] The lightning data used in this study were obtained bya lightning network covering the entire Southeast region andpart of the South and Center regions of Brazil [see Pinto etal., 1999a, 1999b, 2003]. At the time of the observations,the network was composed by 23 sensors (7 Impact and16 LPATS sensors). Considering that this type of network issubject to contamination by intra-cloud flashes, mainly inthe case of positive CG flashes, in this work we have onlyconsidered positive CG flashes with peak current larger than10 kA [Cummins et al., 1998]. The data were analyzed interms of strokes, not considering any algorithm to combinethem into flashes, except for the flash rate that was calcu-lated not taken into account the detection efficiency of thenetwork in the region of study (estimated in 80%).3. Results and Discussion[7] Figure 2 shows for some of the events reported inTable 1 the related infrared satellite GOES images andreflectivity data, from the meteorological radar located inBauru (geographic coordinates 22,3S, 49W). The numbersin red identify the storm; the sprite images are also shown.While storms 2, 4, 5 and 6 (shown in Figure 2) are related tocold fronts, storm 1 was related to a Mesoscale ConvectiveSystem (MCS) and storm 3 was a local air mass thunder-storm. For all cases studied, the characteristics of thethunderstorms associated with sprites (diameter, radar-echoarea above 15 dBz, maximum reflectivity, cloud top andFigure 1. An example of sprite recorded in 25 November2002 at 02:49 UT in the Southeast of Brazil. See colorversion of this figure in the HTML.Figure 2. Infrared satellite GOES images of (a) thunder-storm 2 (at 03:09 UT), and (b) thunderstorms 4, 5 and 6 (at06:00 UT), all of them associated with cold fronts. Thesprite images are shown for case 2, taken from an airplane,and for case 4, on the ground. The PPI data from the radarof Bauru are also shown at 03:00 (in a 450 km range) and06:00 UT (in a 250 km range), respectively. See colorversion of this figure in the HTML.Table 1. Summary of the Sprite Events Reported in the Southeastern BrazilSprite Event Date (UT) Time (UT) Peak Current (kA) Sprite Type Location (of the Camera) Storm No.1 11/25/02 2:49.19.611 41 Column Sprite ground 12 11/25/02 2:52.15.022 45 Unit Sprite ground 13 11/26/02 3:00.11.947 33 Sprite aircraft 24 11/26/02 3:03.07.524 44 Cluster Sprite aircraft 25 11/26/02 3:08.51.471 122 Cluster Sprite aircraft 26 11/26/02 3:09.50.63 Carrot Sprites aircraft 27 3/21/03 0:41.11.374 29 Carrot Sprites aircraft 38 3/21/03 2:04.01.397 Carrot Sprites aircraft 39 3/21/03 5:52.19.449 150 Sprite (Fuzzy) ground 410 3/21/03 6:06.54.79 93 Cluster Sprite ground 411 3/21/03 6:10.45.13 Carrot Sprites ground 412 3/21/03 6:22.19.74 101 Sprite Halo or Elve? ground 413 3/21/03 6:32.39.63 146 Sprite Halo or Elve? ground 514 3/21/03 6:36.15.93 28 Dancing Sprite ground 415 3/21/03 6:38.03.22 Carrot Sprites ground 416 3/21/03 7:07.25.652 30 Carrot Sprites ground 417 3/21/03 7:12.15.011 28 Carrot Sprites ground 618 3/21/03 7:14.41.592 26 Carrot Sprites ground 6L13103 PINTO ET AL.: SPRITES IN BRAZIL L131032 of 4duration), as estimated from the satellite and radar informa-tion, were not significantly different from the typical valuesfor these kind of thunderstorms in this region. The diametervaried from tens to a few hundreds of kilometers, theradar-echo areas above 15 dBz were below 10,000 km2(considering just the individual cells producing sprites, notthe entire contiguous echo), the maximum reflectivitieswere marginally above 40 dBz, the cloud tops were below12 km and the duration of the storms were below 2 hours. Intwo cases, the radar-echo area was just 5000 km2, charac-teristic of small storms. The total lightning activity of thethunderstorms was also investigated. For all events the flashrate was always below 10 flashes per minute.[8] Table 2 shows for the different thunderstorms theaverage peak current of all positive flashes in 20-min. timeintervals centered in the sprite events, compared with thepeak current of the sprite-associated flashes. Sprite-associ-ated positive flashes have substantially larger averagepeak currents than the average of the remaining positivepopulation around the events, in agreement with the resultsreported by Lyons [1996]. For all events, the peak current ofthe sprite-parent positive flashes average 71% higher thanthe other positive flashes. Also shown in the second columnof Table 2 is the percentage of positive strokes during the20-min. interval centered in the sprite event. The percentagevalues are much higher than the values for the whole lifeof the storms (from 10% to 15%). Due to incompleteobservation of the storms along their life times, no estimateabout the ‘‘sprite efficiency’’ of the storms, that is, thenumber of sprite-associated positive flashes divided by thetotal number of positive flashes, was obtained.4. Conclusions[9] Observations of sprites associated with six differentthunderstorms (two related to cold fronts, one related to aMCS, and one a local isolated event) were conducted withcameras on ground and airplanes for the first time in theSoutheast Brazil during the end of 2002 and early 2003.Based on the usual characteristics of the sprite-producingthunderstorms, the results suggest that may occur morefrequently than has previously observed over U.S., inagreement with other observations [Neubert et al., 2001]and indicated that sprites are apparently common in thisregion of Brazil. More observations, however, are needto verify the estimates recently reported by Sato andFukunishi [2003], indicating that the South America maybe one of the most active regions of sprite occurrences inthe world. All sprite events were associated with positiveCG flashes with average peak current larger than theaverage peak current of the positive CG population in thesame storms, in agreement with other observations inthe United States. Also, they occur during time periodswhen the percentage of positive flashes in the storm is muchhigher than the average percentage for the whole life of thestorm.[10] Acknowledgments. We are indebted with our colleagues E.C.Ferraz, E.R. dos Santos, J.O. Fernandes, and R.V. Correˆa of INPE,M. Bailey of Utah State University and J. N. Thomas and M. P. McCarthyof University of Washington for help us during the data acquisition. Theauthors would like also to thanks the Fundac¸a˜o de Amparo a` Pesquisa doEstado de Sa˜o Paulo (FAPESP) for supporting this research through theproject 02/01329-1. The first author would also to thank the ConselhoNacional de Desenvolvimento Cientı´fico e Tecnolo´gico (CNPQ) forpersonal support.ReferencesBlanc, E., T. Farges, R. Roche, D. Brebion, T. Hua, A. Labarthe, andV. Melnikov (2004), Nadir observations of sprites from the InternationalSpace Station, J. Geophys. Res., 109, A02306, doi:10.1029/2003JA009972.Boeck, W. L., O. H. Vaughan Jr., R. J. Blakeslee, B. Vonnegut, M. Brook,and J. McKune (1995), Observations of lightning in the stratosphere,J. Geophys. Res., 100, 1465–1475.Cummins, K. L., M. J. Murphy, E. A. Bardo, W. L. Wiscox, R. B. Pyle, andA. E. Pifer (1998), A combined TOA/MDF technology upgrade of theU.S. National lightning detection network, J. Geophys. Res., 103, 9035–9044.Franz, R. C., R. J. Nemzek, and J. R. Winckler (1990), Television image ofa large upward electrical discharge above a thunderstorm system,Science, 249, 48–51.Israelevich, P. L., Y. Yair, A. D. Devir, J. H. Joseph, Z. Levin, I. Mayo,M. Moalem, C. Price, B. Ziv, and A. Sternlieb (2004), Transient airglowenhancements observed from the space shuttle Columbia during theMEIDEX sprite campaign, Geophys. Res. Lett., 31 , L06124,doi:10.1029/2003GL019110.Lyons, W. A. (1996), Sprite observations above the U.S. High Plains inrelation to their parent thunderstorm systems, J. Geophys. Res., 101,29,641–29,652.Lyons,W. A., E. R.Williams, S. A. Cummer, andM. A. Stanley (2002), 3–Dlightning characteristics of High Plains sprite-producing storms, paperpresented at 17th International Lightning Detection Conference, Vaisala,Tucson, Ariz.Lyons, W. A., T. E. Nelson, E. R. Williams, S. A. Cummer, and M. A.Stanley (2003), Characteristics of sprite-producing positive cloud-to-ground lightning during the 19 July 2000 STEPS Mesoscale ConvectiveSystems, Mon. Weather Rev., 131, 2417–2427.Neubert, T., T. H. Allin, H. Stenbaek-Nielsen, and E. Blanc (2001), Spritesover Europe, Geophys. Res. Lett., 28, 3585–3588.Pinto, O., Jr., I. R. C. A. Pinto, M. A. S. S. Gomes, A. L. Padilha, I. Vitorello,J. H. Diniz, A. M. Carvalho, and A. Cazetta Filho (1999a), Cloud-to-ground lightning in the southeastern Brazil in 1993: 1. Geographicaldistribution, J. Geophys. Res., 104, 31,369–31,379.Pinto, I. R. C. A., O. Pinto Jr., R. M. L. Rocha, J. H. Diniz, A. M. Carvalho,and A. Cazetta Filho (1999b), Cloud-to-ground lightning flashes in thesoutheastern Brazil in 1993: 2. Time variations and flash characteristics,J. Geophys. Res., 104, 31,381–31,387.Pinto, O., Jr., I. R. C. A. Pinto, J. H. Diniz, A. Cazetta Filho, A. M.Carvalho, L. C. L. Chechiglia, and G. E. Amorin (2003), A long-termTable 2. Summary of the Positive CG Flashes During the Sprite EventsStorm No.Total NO. +CG(in a 20 min.Interval Centeredin the Sprite Event)Percentage of +CG(in a 20 min.Interval Centeredin the Sprite Event)AveragePeak Current(kA)(All +CG)AveragePeak Current(kA)(Sprite-Associated +CG)1 25 47 28 432 11 78 48 663 5 42 21 294 56 44 39 805 5 33 68 1466 8 36 34 27L13103 PINTO ET AL.: SPRITES IN BRAZIL L131033 of 4study of the lightning flash characteristics in the southeastern Brazil,J. Atmos. Solar Terr. Phys., 65, 739–748.Rodger, C. J. (1999), Red sprites, upward lightning, and VLF perturbations,Rev. Geophys., 37, 317–336.Sato, M., and H. Fukunishi (2003), Global sprite occurrence location andrates derived from triangulation of transient Schumann resonance events,Geophys. Res. Lett., 30(16), 1859, doi:10.1029/2003GL017291.Sentman, D. D., E. M. Wescott, D. L. Osborne, D. L. Hampton, and M. J.Heavner (1995a), Preliminary results from the Sprites94 campaign: 1. Redsprites, Geophys. Res. Lett., 22, 1205–1208.Sentman, D. D., E. M. Wescott, D. L. Osborne, M. J. Heavner, and D. L.Hampton (1995b), The Peru95 sprite campaign: Overview, Eos Trans.AGU, 76(17), Spring Meet. Suppl., S66.Tavares, F. S. S., D. D. Sentman, E. M. Wescott, O. Pinto Jr., O. MendesJr., and M. J. Taylor (2003), Statistical analysis of space-time relation-ships between sprites and lightning, J. Atmos. Solar Terr. Phys., 65,525–536.R. H. Holzworth, Department of Earth and Space Sciences, University ofWashington, 346A Johnson Hall, Box 351650, Seattle, WA 98195-1650,USA.K. P. Naccarato, I. R. C. A. Pinto, O. Pinto Jr., M. M. F. Saba, N. N.Solorzano, and F. S. S. Tavares, National Institute of Space Research(INPE), Av. dos. Astronautas, 178, Caixa Postal 515, Sa˜o Jose dos Campos,Sao Paulo 12201, Brazil. (osmar@dge.inpe.br)P. D. Pautet and M. J. Taylor, Space Dynamics Laboratory, Utah StateUniversity, Logan, UT 84322-4145, USA.L13103 PINTO ET AL.: SPRITES IN BRAZIL L131034 of 4

Thunderstorm and Lightning Characteristics Associated With Sprites in Brazil

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Thunderstorm and Lightning Characteristics Associated With Sprites in Brazil

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