Cloud-to-ground lightning activity and radar observations of storms in the Pyrenees range area (original) (raw)
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Total lightning activity in thunderstorms over Paris
Atmospheric Research, 2007
A statistical study of two groups of storms that occurred in the Paris area (France) during summer 2000 has been realized. The first group includes 26 high radar reflectivity (HRR) storms with radar reflectivity values exceeding 60 dBZ while the second one includes 19 moderate radar reflectivity (MRR) storms with a maximum radar reflectivity value between 50 and 55 dBZ. The radar reflectivity was provided by a C-band radar and the total lightning activity (cloud-to-ground (CG) and intra-cloud (IC) flashes) was provided by the French Météorage network and a Safir device. HRR storms seem to be characterized by a longer lifetime, and a more extended convective area. On average, they produce more CG and IC flashes than MRR storms. However, a large variability in the number, the rate, and the type of flashes is observed. The HRR storms producing the highest IC flash rates (above 100 min − 1) exhibit the lowest CG flash proportion (1.2 and 4.3%). Most of the HRR storms exhibit a peak lightning activity when the radar reflectivity is strong at low level within the cloud. However, several cases of these storms show a large time lag between the strong lightning production and the presence of high radar reflectivity values at low level. Some possible explanations of these observations, taking into account cloud dynamics, microphysics and lightning initiation, are discussed.
The CG lightning activity of a storm causing a flash-flood
Geophysical Research Letters, 1998
On August 7, 1996, a flood of the Rio Gallego, in In a mountainous region, the potential instability stored in Aragon (Spanish central Pyr6n6es)wiped out the Biescas' camp-the atmosphere is suddenly released from a limited number of ground, killing more than 80 persons. From the observations of convective areas, the spatio-temporal distribution of which is not two meteorological radars, this thunderstorm exhibited some of known. The organization of the convective field is strongly the radar characteristics of a supercell. It spread almost exactly over the Rio Gallego catchment area, upstream of Biescas, and it remained above this area for about two hours, without any advection. The rainfall reached 100 mm h '• and the total cumulative amount locally reached 200 mm. The cloud-toground (CG) flash density averaged over 5 x 5 km 2 areas, was exceptionally high, around 2 km '2, and the peak flash rate averaged over 5-minute periods reached 11.6 mm 4 within the cell area. The evolution of the CG flash rate and the radar reflectivity were closely correlated. The flash rate reached high values before the arrival of the precipitation at the ground. We observe also a very good agreement between the location of the intense rain at the ground and the high CG flash density. The rainfall water volume per flash was 3x104 m 3, a value in agreement with previous work. We propose that quantitative measurements of the lightrang activity may provide valuable information for flash-flood nowcasting and short-term forecasting in mountainous areas. 1-Introduction The nowcasting and short term forecasting of flash-floods in mountainous areas are very difficult. Some events have dramatic consequences, oRen associated with a thunderstorm. $•n•si et al. [ 1996] have studied a case of such a meteorological event, that of Vaison-La-Romaine on September 22, 1992. They note that this flash-flood was produced by several mesoscale convective systems (MCS) locally yielding a total rain of 220 min. The consequences were dramatically enhanced because of the small surface of the involved river catchment. They note a good correlation of cloud-to-ground (CG) flash activity with the rain during the whole storm. On the same event Chbze and Sauvageot [1997] found that the area-average rainfall and the lightning are closely correlated. Several other studies have previously established this kind of correlation. For example, Rutledge and MacGorman [1988] found a correlation between negative and positive CG flashes, respectively, and convective rain and stratiform rain. Buechler et al. [1990] found a good correlation between the maxima of the CG flash rate and the rain flux, and they suggested that the total flash rate should be correlated to the rain production. In two thunderstorms, Piepgrass et al. [1982] noted a good correlation between the evolution of the CG flash rate and the rain rate at the ground, and they found a delay of several minutes for the rain maximum.
Quarterly Journal of the Royal Meteorological Society, 2003
This paper presents a study about correlation between cloud-to-ground lightning ash (CG) activity, and the dynamics and microphysics of thunderclouds. Data collected during Intense Observation Period (MAP IOP) 2a of the Mesoscale Alpine Programme Special Observing Period (SOP) over the Lago Maggiore Target Area (LMTA) in northern Italy are used. IOP 2a was the most electrically active period during the SOP, representing 75% of the total CG activity. Thunderclouds were strongly vertically developed (the 30 dBZ echo tops were sometimes higher than 12 km) and produced large amounts of rainfall and some hail. Doppler and polarimetric radar data allow us to retrieve the three-dimensional wind and radar-re ectivity elds from two synchronous Doppler radars, and particle-type elds in the thunderclouds from the S-Pol polarimetric radar. Both polarities of CGs are distinguished. Temporal and spatial relationships from the global activity over the LMTA are rst studied. Then, the temporal correlation between CG rates and dynamics or microphysics for ve individual cells is considered. A very strong correlation is observed between CG and the presence of a mixture of graupel and hail, which strongly supports a non-inductive charging mechanism. CG impacts seem to be located underneath large radar-re ectivity values and around the maximum vertical velocities. Two individual cells are studied in more detail, in order to better understand their different electrical behaviours: the rst produced mainly negative CGs, and the second produced 61% positive CGs in the second phase of its lifetime. The association of positive CGs with severe weather and especially with the presence of hail is observed.
Some aspects of the correlation between lightning and rain activities in thunderstorms
Atmospheric Research, 2001
The lightning activity of convective systems is a sometimes fruitful indicator of their precipitation production. The present study compares rain volume with different types of lightning activity in several convective systems. The study uses data obtained in the Paris area where two lightning detection systems coexist. The Meteorage network provides the location and the polaritýó f cloud-to-ground flashes, while the SAFIR system detects the total flash activity: cloud-to-ground, intra-cloud flashes and VHF individual sources within a given time window. The overall spatial correlation between rain and lightning appears to be very consistent for all lightning types. A pixel-to-pixel study shows that positive CG flashes are associated with higher rainwater volume than negative flashes. Introducing a weight coefficient for positive CG flashes considerably improves the correlation between rain amount and lightning production. Taking into account the specific contribution of each type of lightning flash, the amount of rain can be estimated from the total electrical activity of each system. Comparison with the amount derived from radar measurement shows reasonable agreement. Finally, the parallel time evolutions of rain and lightning rates display quite similar characteristics.
2008
On 21 April 2006 a mesoscale convective system (MCS) passed within range of the Houston (KHGX) operational Weather Surveillance Radar -1988 Doppler (WSR-88D, S-band) and the Houston Lightning Detection and Ranging (LDAR) network, which measures the time and three-dimensional location of total, or both intracloud (IC) and cloud-to-ground (CG), lightning. This study documents the evolution of total lightning and radar reflectivity for the 21 April 2006 MCS over Texas, with emphasis on the stratiform region and those processes in the convection region that likely influence stratiform region development. As the MCS traverses the LDAR network, the system slowly matures with a weakening convective line and a developing stratiform region and radar bright band. The area of stratiform precipitation increases by an order of magnitude and mean stratiform radar reflectivity increases by 7-8 dB in the radar bright band and mixed-phase zone (0°to −10°C) just above it. As the stratiform region matures, the total lightning pathway slopes rearward and downward from the back of the convective line and into the stratiform region. At early times, the pathway extends horizontally rearward 40 to 50 km into the stratiform region at an altitude of 10 to 12 km. Near the end of the analysis time period, the total lightning pathway slopes rearward 40 km and downward 6 km through the transition zone before extending 40 to 50 km in the stratiform region at an altitude of 5 to 7 km. The sloping pathway likely results from charged ice particles advected from the convective line by storm relative front to rear flow while the level pathway extending further into the stratiform region is likely caused by both charge advection and local in-situ charging.
A study about the correlation link between lightning data and meteorological data
Lightning Imager (LI) is one of the candidates to fly on the European Meteosat satellite platform of third generation (MTG). Therefore with the MTG it will be available the lightning data on the whole Euro-African zone. The LI is a product of the application field of nowcasting, but the implications of its applications are seen also in hydrology, monitoring of land and forest and management of the crisis. Collaboration between CNMCA (Centro Nazionale di Meteorologia e climatologia dell'Aeronautica) and SELEX-GALILEO (a Finmeccanica company) aims to study a possible methodology use of lightning data, to supply more information about the modalities of LI data in the decision management. In detail this research proposes an algorithm for the identification of convective areas through the use of data LAMPINET (lightning ground network of the Italian Air Force Metereological service), SEVIRI, NEFODINA (a software developed by Italian Air Force Meteorological service that is able to identify convective system and to forecast their developments in the next 15 minutes), radar, and subsequently to characterize the cloud and its precipitation.
Atmospheric Research, 2007
This study analyzes the relationship between lightning and precipitation in nine convective events. They occurred during the summer season of 2004 in Catalonia (NE Spain) and its coastal area, in the North Western Mediterranean Sea. The data examined were issued from C-band volumetric radar observations, from radiosoundings, and total lightning detection records, including both cloud-to-ground (CG) and intra-cloud flashes. The overall Rainfall-Lightning Ratio (RLR) found was 38.9 10 3 m 3 /CG flash, which is a value closer to those found in the Southeastern United States than in the Atlantic coast of France. Moreover, the range of variation found in the studied episodes goes from 10.8 to 87.2 10 3 m 3 /CG flash. These variations are analyzed in terms of the synoptic conditions of the events and regarding their spatial distribution, comparing land and sea domains.
A Mediterranean nocturnal heavy rainfall and tornadic event. Part II: Total lightning analysis
Atmospheric Research, 2011
On the night from 1st to 2nd of November 2008, a multi-cell storm coming from the Mediterranean produced severe weather in the coastal area of Catalonia (NE Spain): groundlevel strong damaging wind gusts, a tornadowhich caused F2 damageand heavy rainfall. A general overview of the synoptic framework, damage observed and a radar analysis is given in the first part of the study. This second part is mostly centered on the detailed analysis of the total lightning behavior, its relationship with radar-derived storm parameters, and total lightning correlation with hazardous weather. The purpose is to bring more evidence about the outstanding role of total lightning in severe weather surveillance tasks. The analysis of the storm cells life cycle has showed similar trends between the total lighting flash rates and radarderived parameters like the area of reflectivity above 30 dBZ at 7-km. Regarding lightning trends, a lightning "jump" patternan abrupt increase of the total lightning rate in a short period of timehas been related to severe weather. On the contrary, cloud-to-ground lightning data did not show any pattern related to severe weather. In comparison to other parameters, like the IC:CG ratio, the lightning "jump" pattern seems more robust to forecast in a short-term basis the possible occurrence of severe weather.
Cloud-to-ground lightning activity in the Iberian Peninsula: 1992-1994
Journal of Geophysical Research: Atmospheres, 2001
For the first time, the temporal and spatial distribution of cloud-to-ground lightning activity in the Iberian Peninsula are being studied. The database covers the years 1992-1994, and it was recorded over 2.2 x 106 cloud-to-ground lightning flashes. The monthly variation shows a single peak in the warmer months (May to September) with a strong year-to-year variability. The diurnal cycle of lightning activity peaks at 1700 LT with a subsequent slow decrease toward the minimum in the morning hours. The percentage of positive flashes is 8%, although this percentage is higher in the winter than in the summer. The lightning flash polarity is found to be very similar throughout the day. The average multiplicity is found to be 2.0 for the negative flashes and 1.1 for the positive flashes and is very similar in the winter and summer seasons, while the percentage of single-stroke flashes tends to increase in the winter. The median (mean) intensity is found to be 22.5 kA (32.4 kA) for the negative flashes and 52.3 kA (69.3 kA) for the positive flashes. The excessively high intensity for the positive flashes could be due to the detection system has low efficiency in detectiong weak amplitude flashes. The distribution of amplitudes is very similar in the winter and summer seasons. The decay at large amplitudes is slower for the positive flashes. The median and mean amplitudes are higher in the winter for both polarities. The spatial cloud-to-ground lightning distribution confirms the well-known preference for certain areas in the development of thunderstorms. The average maximum negative, positive, and combined flash densities are 3.1, 0.2, and 3.3 flashes km '2 yr '• respectively. The comparison between individual years shows a considerable year-to-year variability. The average percentage of positive flashes ranges from 0% to 41%. The grid block median peak current amplitudes vary from 12.5 to 47.4 kA for the negative flashes and from 17.6 to 107.5 kA for the positive flashes. The results are discussed in the context of other measurements taken at different parts of the world. sensivity of the global circuit to change in surface air temperature, lightning might be used as an indicator of changes in the global temperature [Williams, 1992, 1994; Reeve and Toumi, 1999]. There are further interests in lightning activity, since it plays a fundamental role as cause of natural forest fires in midlatitudes [i.e., Krider et al., 1980], it is a source of nitrogen oxide and hence tropospheric ozone [Franzblau and Popp, 1989; Toumi et al., 1996], and it is a major cause of weather-related deaths, property damages, and power system breakdowns [Fisher and Krider, 1982].