Are you H. Höller?

Claim your profile

Publications (125)95.93 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ten lightning detection networks measured lightning activity in the São Paulo area during CHUVA-GLM Vale do Paraiba field experiment in the months of December 2011-March 2012. This field experiment gathered different lightning systems from a broad range of electromagnetic frequencies (ELF to VHF and optical), corresponding to a great opportunity for understanding the different lightning detection technologies. Assuming that the Lightning Mapper Array (LMA) can capture the majority of electromagnetic irradiated sources through a lightning discharge (breakdown, step leader, return stroke and dart leaders), it is possible to correlate in space and time what each system is really measuring (i.e., are they measuring sferics, leaders, return strokes, sources or a complete lightning channel?). In a preliminary analysis, the total lightning systems were very comparable in time, i.e., they had coincident time measurements. For the VLF and LF systems that were designed to measure mainly cloud-to-ground discharges, we did find some differences, i.e., sometimes all networks reported lightning, but most of the time just one or two systems had lightning reports. It was observed that often there are temporal coincidences between LIS groups and the ground-based total lightning measurements. Moreover, the probability of LIS groups being detected by LMA increases as the lightning signals are observed at higher heights and it is also dependent on the amount of precipitation overhead of the flash.
    XV International Conference on Atmospheric Electricity (ICAE 2014); 06/2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Future geostationary satellite systems will offer a variety of improved observing capabilities which will be extremely useful for many applications like numerical weather forecasting, nowcasting of severe weather, climate research or hydrology. The planning for MTG (Meteosat Third Generation) includes an optical lightning imager (LI) as part of the payload. One requirement for a proper interpretation of these optical data is a better understanding of what components of a flash are to be seen from space and how these observations relate to ground based radio frequency observations. Therefore, the objectives of the present study concern the improvement of the understanding of the complex lightning process which then enables a proper interpretation of the optical data. For assessing the future performances and benefits of a geostationary lightning sensor this study takes advantage of the comprehensive lightning data sets obtained from the recent CHUVA field experiment performed in Brazil. (CHUVA - Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement)). During the rainy season of 2011-2012 a large number of ground based lightning detection systems was set up in the Sao Paulo area in Brazil. In the present study we look at the detailed radio frequency (RF) based observation from LINET (Lightning detection network operated by DLR, nowcast and USP) and observing strokes in the VLF/LF (very low and low frequency) range, the LMA (Lightning mapping array) from NASA observing RF sources in the VHF (very high frequency) range and the TRMM-LIS (Tropical Rainfall Measuring Mission-Lightning Imaging Sensor) optical space borne lightning imager. The LIS is used as a reference instrument for the future MTG-LI sensor as well as for the corresponding GLM sensor (Geostationary Lightning Mapper) on GOES-R. Thus it is possible to study the relations between the RF and optical signals from lightning in detail and to assess the performance of the future geostationary observations from a set of proxy satellite data generated from the ground based observations. In confirmation of previous studies, it was found that often a direct temporal coincidence of RF signals (LINET strokes) and optical pulses (LIS groups) exists. The short baseline configuration of LINET allowed to observe the strokes mapping the flash branches similar to LMA, but by locating the limited number of strong cloud strokes rather than a large number of weak source points from leader steps. An initial breakdown phase of vertically propagating sources can often be found in LINET and LMA data. The higher level LINET and LMA signals have higher probability to be optically detected. Lower level LINET and LMA signals are optically detected from above in case of missing high level precipitation as inferred from radar observations provided by USP. The new comprehensive data set allows for constructing proxy data for the future geostationary lightning mappers.
    2013 EUMETSAT Meteorological Satellite Conference and the 19th Satellite Meteorology, Oceanography and Climatology Conference of the American Meteorological Society (AMS); 09/2013
  • Source
    V. K. Meyer, H. Höller, H. D. Betz
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a new hybrid method for automated thunderstorm observation by tracking and monitoring of electrically charged cells (ec-TRAM). The developed algorithm combines information about intense ground precipitation derived from low-level radar-reflectivity scans with three-dimensionally resolved lightning data, which are provided by the European VLF/LF lightning detection network LINET. Based on the already existing automated radar tracker rad-TRAM (Kober and Tafferner, 2009), the new method li-TRAM identifies and tracks electrically active regions in thunderclouds using lightning data only. The algorithm ec-TRAM uses the output of the two autonomously operating routines rad-TRAM and li-TRAM in order to assess, track, and monitor a more comprehensive picture of thunderstorms. The main motivation of this work is to assess the benefit of three-dimensionally resolved total lightning (TL) information for thunderstorm tracking and monitoring. The focus is laid on the temporal development whereby TL is characterized by an effective in-cloud (IC) and cloud-to-ground (CG) event discrimination. It is found that the algorithms li-TRAM and ec-TRAM are both feasible methods for thunderstorm monitoring with potential for nowcasting. The tracking performance of li-TRAM turns out to be comparable to that of rad-TRAM, a result that strongly encourages utilization of lightning data as independent data source for thunderstorm tracking. It is found that lightning data allow an accurate and close monitoring of storm regions with intense internal dynamics as soon as convection induces electrical activity. A case study shows that the current short-term storm dynamics are clearly reflected in the amount of strokes, change of stroke rates and IC/CG ratio. The hybrid method ec-TRAM outperforms rad-TRAM and li-TRAM regarding reliability and continuous assessment of storm tracks especially in more complexly developing storms, where the use of discharge information contributes to more detailed information about storm stage and storm evolution.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 05/2013; 13(10):5137-5150. · 5.51 Impact Factor
  • Source
    V. K. Meyer, H. Höller, H. D. Betz
    [Show abstract] [Hide abstract]
    ABSTRACT: Total lightning (TL) data have been found to provide valuable information about the internal dynamics of a thunderstorm allowing conclusions about its further development as well as indicating potential of thunderstorm-related severe weather at the ground. This paper investigates electrical discharge correlations of strokes and flashes with respect to the temporal evolution of thunderstorms in case studies as well as by statistical means. The recently developed algorithm li-TRAM (tracking and monitoring of lightning cells, Meyer et al., 2013) has been employed to track and monitor thunderstorms based on three-dimensionally resolved TL data provided as stroke events by the European lightning location network LINET. From statistical investigation of 863 suited thunderstorm life cycles, the cell area turned out to correlate well with (a) the total discharge rate, (b) the in-cloud (IC) discharge rate, and (c) the mean IC discharge height per lightning cell as identified by li-TRAM. All three parameter correlations consistently show an abrupt change in discharge characteristics around a cell area of 170 km2. Statistical investigations supported by the comparison of three case studies - selected to represent a single storm, a multi-cell and a supercell - strongly suggest that the correlation functions include the temporal evolution as well as the storm type. With the help of volumetric radar data, it can also be suggested that the well-defined break observed at 170 km2 marks the region where the transition occurs from short-lived and rather simple structured single storm cells to better organized, more persistent, and more complex structured thunderstorm forms, e.g. multi-cells and supercells. All three storm types experience similar discharge characteristics during their growing and dissipating phases. However, while the poorly organized and short-lived cells preferentially remain small during a short mature phase, mainly the more persistent thunderstorm types develop to sizes above 170 km2 during a pronounced mature stage. At that stage they exhibit on average higher discharge rates at higher altitudes as compared with matured single cells. With the maximum stroke distance set to 10 km and a flash duration set to 1 s, the parameterization functions found for the stroke rate as a function of the cell area have been transformed to a flash rate. The presented study suggests that, with respect to the storm type, stroke and flash correlations can be parameterized. There is also strong evidence that parameterization functions include the time parameter, so that altogether TL stroke information has good potential to pre-estimate the further evolution (nowcast) of a currently observed storm in an object-oriented thunderstorm nowcasting approach.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 05/2013; 13(10):5151-5161. · 5.51 Impact Factor
  • V. K. Meyer, H. Höller, H. D. Betz
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a new hybrid method for automated thunderstorm observation by tracking and monitoring of electrically charged cells (ec-TRAM). The developed algorithm combines information about intense ground precipitation derived from low-level radar-reflectivity scans with three-dimensionally resolved lightning data, which are provided by the European VLF/LF lightning detection network LINET. Based on the already existing automated radar tracker rad-TRAM (Kober and Tafferner, 2009), the new method li-TRAM identifies and tracks electrically active regions in thunderclouds using lightning data only. The algorithm ec-TRAM uses the output of the two autonomously operating routines rad-TRAM and li-TRAM in order to assess, track, and monitor a more comprehensive picture of thunderstorms. The main motivation of this work is to assess the benefit of three-dimensionally resolved total lightning information (TL) for thunderstorm tracking and nowcasting. The focus is laid on the temporal development whereby TL is characterized by an effective in-cloud (IC) and cloud-to-ground (CG) event-discrimination. It is found that the algorithms li-TRAM and ec-TRAM are both feasible methods for thunderstorm nowcasting. The tracking performance of li-TRAM turns out to be comparable to that of rad-TRAM, a result that strongly encourages utilization of lightning data as independent data source for thunderstorm tracking. It is found that lightning data allow an accurate and close monitoring of storm regions with intense internal dynamics as soon as convection induces electrical activity. A case study shows that the current short-term storm dynamics are clearly reflected in the amount of strokes, change of stroke rates and IC/CG ratio. The hybrid method ec-TRAM outperforms rad-TRAM and li-TRAM regarding reliability and continuous assessment of storm tracks especially in more complexly developing storms, where the use of discharge information contributes to more detailed information about storm stage and storm evolution.
    Atmospheric Chemistry and Physics 01/2013; 13(1):2179-2216. · 4.88 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Future geostationary satellite systems will offer a variety of improved observing capabilities which will be extremely useful for many applications like numerical weather forecasting, nowcasting of severe weather, climate research or hydrology. The future payloads will include the optical lightning imagers LI on MTG (Meteosat Third Generation) and GLM (Geostationary Lightning Mapper) on GOES-R (Geostationary Operational Environmental Satellite - R Series). Proper interpretation of these optical data requires a better understanding of what components of a flash are to be seen from space and how these observations relate to ground based radio frequency observations. For assessing the future performances and benefits of a geostationary lightning sensor this study takes advantage of the comprehensive lightning data sets obtained from the recent CHUVA field experiment performed in Brazil (CHUVA - Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement)). During the rainy season of 2011-2012 a large number of ground based lightning detection systems was set up in the Sao Paulo area as part of the CHUVA-GLM Vale do Paraíba campaign. In the present study we look at the detailed radio frequency (RF) based observation from LINET (Lightning detection network operated by DLR, nowcast and USP) observing strokes in the VLF/LF (very low and low frequency) range, the LMA (Lightning Mapping Array) from NASA observing RF sources in the VHF (very high frequency) range and the TRMM-LIS (Tropical Rainfall Measuring Mission-Lightning Imaging Sensor) optical space borne lightning imager. The LIS is used as a reference instrument for the future geostationary sensors. Thus it is possible to study the relations between the RF and optical signals from lightning in detail and to assess the performance of the future geostationary observations from a set of proxy satellite data generated from the ground based observations. In confirmation of previous studies, it was found that often a direct temporal coincidence of RF signals (LINET strokes) and optical pulses (LIS groups) exists. The short baseline configuration of LINET allowed observing the strokes mapping the flash branches similar to LMA, but by locating the limited number of strong cloud strokes rather than a large number of weak source points from leader steps. An initial breakdown phase of vertically propagating sources can often be found in LINET and LMA data. The higher level LINET and LMA signals have higher probability to be optically detected. Lower level LINET and LMA signals are optically detected from above in case of missing high level precipitation as inferred from radar observations provided by USP.
    CHUVA International Workshop; 01/2013
  • Source
    V. K. Meyer, H. Höller, H. D. Betz
    [Show abstract] [Hide abstract]
    ABSTRACT: Total lightning (TL) data has been found to provide valuable information about the internal dynamics of a thunderstorm allowing conclusions about its further development as well as indicating potential of thunderstorm-related severe weather at the ground. This paper investigates electrical discharge correlations of strokes and flashes with respect to the temporal evolution of thunderstorms in case studies as well as by statistical means. The recently developed algorithm li-TRAM (tracking and monitoring of lightning-cells, Meyer et al., 2012) has been employed to track and monitor thunderstorms based on three-dimensionally resolved TL lightning data provided as stroke events by the European lightning location network LINET. From statistical investigation of 863 suited thunderstorm life-cycles the cell area turned out to correlate well with (a) the total discharge rate, (b) the in-cloud (IC) discharge rate, and (c) the mean IC discharge height per lightning-cell as identified by li-TRAM. All three parameter correlations consistently show an abrupt change in discharge characteristics around a cell area of 170 km2. Statistical investigations supported by the comparison of three case studies - selected to represent a single storm, a multi-cell and a supercell - strongly suggest that the correlation functions include the temporal evolution as well as the storm type. With the help of volumetric radar data, it can also be suggested that the well defined break observed at 170 km2 marks the region, where the transition occurs from short-lived and rather simple structured single storm cells to better organized, more persistent, and more complex structured thunderstorm forms, e.g. multi-cells and super-cells. All three storm-types experience similar discharge characteristics during their growing and dissipating phases. However, while the poorly organized and short-lived cells preferentially remain small during a short mature phase, mainly the more persistent thunderstorm types develop to sizes above 170 km2 during a pronounced mature stage. At that stage they exhibit on average higher discharge rates at higher altitudes as compared with matured single-cells. With the maximum stroke distance set to 10 km and a flash duration set to 1 s the parameterisation functions found for the stroke rate as function of the cell area has been transformed to a flash rate. The presented study suggests that, with respect to the storm type, stroke and flash correlations can be parameterized. There is also strong evidence, that parameterization functions include the time parameter, so that altogether TL stroke information has good potential to pre-estimate the further evolution (nowcast) of a currently observed storm in an object-oriented thunderstorm nowcasting approach.
    Atmospheric Chemistry and Physics 01/2013; 13(1):2217-2242. · 4.88 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A detailed analysis of air flow, hydrometeor characteristics, cloud-top height, and lightning is presented for the 15/07/2007 case during the Convection and Orographically Induced Precipitation Study (COPS) field campaign. In a synergetic manner, the study makes use of multiple-Doppler analysis from three operational radars, POLDIRAD's polarimetric capabilities, data from different channels of Meteosat Second Generation (MSG) satellite, as well as lightning data to document the life cycle of deep convection. The cloud-top height derived from MSG infrared channel and radar volume scans increased rapidly during 14:20 and 14:35 UTC. The most active phase was identified during 14:35 and 14:45 UTC when cloud tops reached the tropopause, lightning occured with a maximum rate of 15 strokes per minute, and hail was detected via polarimetric radar products. During the cell's lifetime horizontal and vertical flow were derived from four consistent triple-Doppler calculations with 500 m and 15 min space and time resolution, respectively. A main updraft was identified to originate from the more humid air masses to the east of the convergennce line responsible for the cell initiation. Consistency checks of the calculated wind fields with the observed radial velocities were performed. Areas of enhanced discrepancies between the observing systems (during the early phase of mature state) match with areas of higher turbulence marked by polarimetric radar parameters. Moreover, lightning locations correspond well with volumes of distinct vertical motion, particularly within regions of extended updrafts. By interpreting hydrometeor types from polarimetric radar data the evolution of the fraction of different types per volume is investigated. While during the early phase of thunderstorm the fraction of ice (snow, graupel, hail) in the upper cloud part became enhanced, the fraction of rain increased during the decay phase.
    ICAM 2011; 08/2012
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cloud chemistry simulations are performed for a Hector storm observed on 16 November 2005 during the SCOUT-O3/ACTIVE campaigns based in Darwin, Australia, with the primary objective of estimating the average production of NO per lightning flash during the storm which occurred in a tropical environment. The 3-D WRF-AqChem model (Barth et al., 2007a) containing the WRF nonhydrostatic cloud-resolving model, online gas- and aqueous-phase chemistry, and a lightning-NOx production algorithm is used for these calculations. An idealized early morning sounding of temperature, water vapor, and winds is used to initialize the model. Surface heating of the Tiwi Islands is simulated in the model to induce convection. Aircraft observations from air undisturbed by the storm are used to construct composite initial condition chemical profiles. The idealized model storm has many characteristics similar to the observed storm. Convective transport in the idealized simulated storm is evaluated using tracer species, such as CO and O3. The convective transport of CO from the boundary layer to the anvil region was well represented in the model, with a small overestimate of the increase of CO at anvil altitudes. Lightning flashes observed by the LIghtning detection NETwork (LINET) are input to the model and a lightning placement scheme is used to inject the resulting NO into the simulated cloud. We find that a lightning NO production scenario of 500 moles per flash for both CG and IC flashes yields anvil NOx mixing ratios that match aircraft observations well for this storm. These values of NO production nearly match the mean values for CG and IC flashes obtained from similar modeling analyses conducted for several midlatitude and subtropical convective events and are larger than most other estimates for tropical thunderstorms. Approximately 85% of the lightning NOx mass was located at altitudes greater than 7 km in the later stages of the storm, which is an amount greater than found for subtropical and midlatitude storms. Upper tropospheric NO2 partial columns computed from the model output are also considerably greater than observed by satellite for most tropical marine convective events, as tropical island convection, such as Hector, is more vigorous and more productive of lightning NOx.
    Atmospheric Chemistry and Physics 07/2012; 12(7):16701-16761. · 4.88 Impact Factor
  • ATMOSPHERIC CHEMISTRY AND PHYSICS 04/2012; 12:6679-6698. · 5.51 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Consideration of lightning data from whatever source allows and improves nowcasting of thunderstorms. The present contribution highlights the particular benefits that can be drawn from utilization of LINET lightning data. Besides the measurement of cloud-to-ground strokes (CG) LINET also reports cloud lightning (IC) in terms of VLF/LF strokes that occur both in the very initial phase of a discharge and, thereafter, inside already formed discharge channels. The precise nature of these IC strokes is not yet understood. Still, for sensor baselines of up to 200 km LINET provides ample data for IC strokes along with their emission heights. It is well known that severe weather is characterized by particularly strong convection, large and high-rising convective volumes. Thus, measured rates of CG and IC strokes show distinctive increases when a cell matures and produces severe weather. In parallel, the increasing height of cloud tops results in an increase of the measured IC emission heights. Consequently, LINET can recognize the development of severe weather by exploiting IC rates and registering the increase of IC heights as a function of time. Likewise, subsequent decrease of these parameters signals the decay of severe weather conditions. For verification of the severe weather detection potential of LINET we compare the lightning characteristics with the polarimetric Doppler radar measurement of thunderstorms taken by DLR's POLDIRAD. From these measurements we obtain information on hail formation and fallout, on intense updrafts in connection with supercooled raindrops, on overshooting cloud tops or on downdrafts. The IC stroke components are connected to the graupel and ice mass within the storm and so the vertical structures are expected to be correlated to each other. Another type of stroke verification is from video recordings of storms and lightning as taken from the POLDIRAD location. Observations from different kind of storm systems have different kinds of IC/CG ratios. In the case studies shown, LINET flash rate is in excellent agreement with the video flash rate. Especially in the limiting cases of very low IC emissions as often observed in aged decaying storm systems, LINET strokes may be more difficult to categorize. Several case studies will be presented that demonstrate the nowcasting power of LINET lightning data. Particular events of severe weather will be analysed in terms of the quoted lightning parameters. In order to verify the significance of the physical lightning parameters and to exclude trivial influences, e.g. from spatially varying network efficiency, non-severe storms are also analysed in the same area where the considered severe storms have occurred. It can be concluded from the results that the quoted lightning parameters are indeed reliable indicators for severe weather.
    04/2012;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Thunderstorm electrification is mainly due to ice particle interaction processes leading to a typical main dipole structure. Intra-cloud and cloud-to-ground discharges can be detected at low and very low radio frequencies by the lightning detection network LINET. At high radio-frequencies one can detect the step-like flash structure. The optical emissions can be observed from space. The operational LINET network over Europe and networks deployed during field experiments enabled a comparison of lightning characteristics from mid-latitudes and the tropics. Important applications are nowcasting and operational weather forecasting, climate research, and the planning and support of new satellite lightning observing systems.
    Atmospheric Physics: Background - Methods - Trends. 01/2012;
  • [Show abstract] [Hide abstract]
    ABSTRACT: CHUVA is a Brazilian research program that is characterizing the main precipitating systems observed in Brazil as a support for Global Precipitation Measurement (GPM) mission. CHUVA conducts a series of field campaigns in the time frame of 2010-2013 that sample raining systems from maritime to continental regime in polluted and clean environments. From November of 2011 through March of 2012, CHUVA is hosting a field program at Vale do Paraiba, southeast of Brazil, where NOAA and EUMETSAT deployed 12 LMA and 7 LINET antennas respectively to gather lightning measurements to support the development of algorithms that will be employed by GOES-R and Third Generation Meteosat satellites. Due to this opportunity, other lightning detection systems have been invited to participate in this campaign. As a result, for the first time it will be possible to gather coincident measurements from 10 different lightning detection technologies, i.e., a) VHF: LMA and TLS200 Vaisala; b) VLF: WWLLN, STARNET, Vaisala GLD360, WSI and ATDNet; c) VLF/LF: RINDAT, LINET; c) ELF/VLF/LF/VHF: Weather Bug. As each system uses different frequencies, detection (sky/ground waves or line of sight, electrical and magnetic fields) and methodology for location (TOA, ATD and interferometry) it is expect that each system observes different parts of the lightning flash. Thus taking the opportunity that LMA measures most of the lightning sources associated to all atmospheric discharges, this study will concentrate on describing what each technology measures/detects in respect to LMA source over selected thunderstorms.
    EGU General Assembly Conference Abstracts; 01/2012
  • Martin Hagen, Hartmut Höller, Kersten Schmidt
    [Show abstract] [Hide abstract]
    ABSTRACT: Precipitation or weather radar is an essential tool for research, diagnosis, and nowcasting of precipitation events like fronts or thunderstorms. Only with weather radar is it possible to gain insights into the three-dimensional structure of thunderstorms and to investigate processes like hail formation or tornado genesis. A number of different radar products are available to analyze the structure, dynamics and microphysics of precipitation systems. Cloud radars use short wavelengths to enable detection of small ice particles or cloud droplets. Their applications differ from weather radar as they are mostly orientated vertically, where different retrieval techniques can be applied.
    Atmospheric Physics: Background - Methods - Trends. 01/2012;
  • [Show abstract] [Hide abstract]
    ABSTRACT: The primary science objective for the CHUVA lightning mapping campaign is to combine measurements of total lightning activity, lightning channel mapping, and detailed information on the locations of cloud charge regions of thunderstorms with the planned observations of the CHUVA (Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement) field campaign. The lightning campaign takes place during the CHUVA intensive observation period October-December 2011 in the vicinity of São Luiz do Paraitinga with Brazilian, US, and European government, university and industry participants. Total lightning measurements that can be provided by ground-based regional 2-D and 3-D total lightning mapping networks coincident with overpasses of the Tropical Rainfall Measuring Mission Lightning Imaging Sensor (LIS) and the SEVIRI (Spinning Enhanced Visible and Infrared Imager) on the Meteosat Second Generation satellite in geostationary earth orbit will be used to generate proxy data sets for the next generation US and European geostationary satellites. Proxy data, which play an important role in the pre-launch mission development and in user readiness preparation, are used to develop and validate algorithms so that they will be ready for operational use quickly following the planned launch of the GOES-R Geostationary Lightning Mapper (GLM) in 2015 and the Meteosat Third Generation Lightning Imager (LI) in 2017. To date there is no well-characterized total lightning data set coincident with the imagers. Therefore, to take the greatest advantage of this opportunity to collect detailed and comprehensive total lightning data sets, test and validate multi-sensor nowcasting applications for the monitoring, tracking, warning, and prediction of severe and high impact weather, and to advance our knowledge of thunderstorm physics, extensive measurements from lightning mapping networks will be collected in conjunction with electric field mills, field change sensors, high speed cameras and other lightning sensors, dual-polarimetric radars, and aircraft in-situ microphysics which will allow for excellent cross-network inter-comparisons, assessments, and physical understanding.
    AGU Fall Meeting, San Francisco, December 5 - 9, 2011; 12/2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: During summer 2010 a 7-sensor lightning detection network of type 'LINET' has been installed around KSC in Florida in order to test the detection efficiency of both cloud-to-ground and cloud strokes. The VLF/LF network has 3D capability and, thus, can detect cloud strokes along with their emission heights. Comparison with LDAR2 data revealed that LINET recognized almost all cloud flashes. Additional information can be derived from LIS observations. A significant number of LIS overpasses have been observed and the number of strokes, flashes, and spatial correlations have been analyzed. LINET data from a variety of storms at and near KSC have been inspected and the distribution of emission heights from positive and negative IC strokes was examined. Characteristic structures have been found, which were in good agreement with the corresponding LADR2 source point distributions. The observed performance characteristics of LIS, LINET and LDAR2 are commented.
    AGU Fall Meeting, San Francisco, December 5 - 9, 2011; 12/2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In Part I of this two-part paper a new method of predicting the total lightning flash rate in thunderstorms was introduced. In this paper, the implementation of this method into the convection-permitting Consortium for Small Scale Modeling (COSMO) model is presented. The new approach is based on a simple theoretical model that consists of a dipole charge structure, which is maintained by a generator current and discharged by lightning and, to a small extent, by a leakage current. This approach yields a set of four predictor variables, which are not amenable to direct observations and consequently need to be parameterized (Part I). Using an algorithm that identifies thunderstorm cells and their properties, this approach is applied to determine the flash frequency of every thunderstorm cell in the model domain. With this information, the number of flashes that are accumulated by each cell and during the interval between the activation of the lightning scheme can be calculated. These flashes are then randomly distributed in time and beneath each cell. The output contains the longitude, the latitude, and the time of occurrence of each simulated discharge. Simulations of real-world scenarios are presented, which are compared to measurements with the lightning detection network, LINET. These comparisons are done on the cloud scale as well as in a mesoscale region composing southern Germany (two cases each). The flash rates of individual cumulonimbus clouds at the extreme ends of the intensity spectrum are realistically simulated. The simulated overall lightning activity over southern Germany is dominated by spatiotemporal displacements of the modeled convective clouds, although the scheme generally reproduces realistic patterns such as coherent lightning swaths.
    Monthly Weather Review 10/2011; 139(2011):3112-3124. · 2.76 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The AMMA (African Monsoon Multidisciplinary Analysis) project set out to better understand the geophysical processes which govern the evolution of the monsoon and provide the science needed to improve prediction and decision-support systems. The control exerted by weather and climate on agronomic production, water resources and public health was studied to evaluate the potential for populations to adapt. AMMA made advances which have the potential to improve forecasts from weather to climate scales. Translating them into operational tools for decision making will require improvements to the observational networks, and stronger support for the organizations which generate and disseminate application forecasts. Copyright © 2011 Royal Meteorological Society
    Atmospheric Science Letters 02/2011; 12(1):2 - 6. · 1.75 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The AMMA (African Monsoon Multidiscplinary Analysis) field programme aimed at documenting the West African Monsoon (WAM) climate system, in all its geophysical components. It also includes an important socio-economic component. Encompassing a wide range of spatial and time scales, AMMA is one of the most ambitious such programmes ever set up. While the key accomplishments of AMMA are summarised in this paper, a few lessons of broad interest are also drawn both as a tribute to the extraordinary efforts made by a community of several hundreds of people and as possible guidelines for ensuring a long lasting future to integrated climate and environmental studies in West Africa. Copyright © 2011 Royal Meteorological Society
    Atmospheric Science Letters 02/2011; 12(1):123 - 128. · 1.75 Impact Factor
  • Source
    91st American Meteorological Society Annual Meeting, 5th Conference on the Meteorological Applications of Lightning Data & 13th Conference on Atmospheric Chemistry; 01/2011