Journal of Atmospheric and Solar-Terrestrial Physics 65 (2003) 733 – 737
www.elsevier.com/locate/jastp
Cloud-to-ground lightning distribution in Brazil
I.R.C.A. Pinto∗ , O. Pinto Jr.
Instituto Nacional de Pesquisas Espaciais—INPE, Av. dos Astronautas 1758,
Sao Jose dos Campos, SP 12227-010, Brazil
Received 14 December 2001; accepted 18 February 2003
Abstract
The cloud-to-ground lightning distribution in Brazil is reviewed based on data from thunderstorm days, 5ash counters,
LF/VLF lightning detection networks, precipitation, and optical satellite sensors. Brazil is the largest tropical country in the
world and, in consequence, one of the countries with highest lightning activity. Although the information obtained in the
last decade covers only part of the country, it provides a unique opportunity to study the lightning geographical distribution
in Brazil. The analysis of the data suggests that 50 –70 millions of cloud-to-ground lightning 5ashes occur every year,
most of them concentrated in the north, center, and southeast regions. The analysis also suggests that 5ash densities larger
than 10 5ashes km−2 yr −1 are common in these regions. However, the information about the distribution of peak current,
multiplicity and percentage of positive cloud-to-ground 5ashes is still very limited and controversial.
c 2003 Elsevier Science Ltd. All rights reserved.
Keywords: Lightning distribution; Tropical lightning; Lightning-networks; Brazil
1. Introduction
Brazil is the largest tropical country in the world and,
in consequence, one of the countries with highest lightning
activity. The country is divided into <ve large regions, as
shown in Fig. 1. Based on meteorological satellite data, it
is known that the main regions of occurrence of thunderstorms are the north, center and southeast regions (Pinto
and Pinto, 2000). In the north (Amazon) region, most thunderstorms are associated with local conditions and tropical
squall lines produced by low-level convergence related to
the intertropical convergence zone (ITCZ). In the center region, the thunderstorm characteristics are associated with
local conditions, fronts and the proximity of the Bolivian
high. Large mesoscale convective systems are frequent in
this region. In the southeast region of the country, by turn,
most thunderstorms are associated with cold front convection in a mountainous terrain, although local thunderstorms
∗
Corresponding author.
E-mail address: [email protected] (I.R.C.A. Pinto).
and mesoscale convective systems are also present. In the
south region, the conditions are similar to those in the southeast, except for the more frequent occurrence of large systems like mesoscale convective complexes. Finally, in the
northeast region, thunderstorms are less frequent due to the
low humidity values normally found in this region.
Unlike in the United States, where the cloud-to-ground
lightning distribution has been obtained by lightning detection networks covering the whole country (Orville, 1991,
1994; Orville and Silver, 1997; Orville and HuBnes, 1999),
in Brazil similar information is available only to a limited
portion of the country. For the whole country, the only information available is that obtained from thunderstorm days
and optical satellite sensors. However, both data have their
limitations. On one hand, the relationship between thunderstorm days and cloud-to-ground 5ash density can be very
inaccurate in some region (e.g., Pinto et al., 2000a). On the
other hand, the lightning 5ash density obtained from sensors
on satellites has been shown to be more representative of the
total lightning activity instead of the cloud-to-ground lightning activity, mainly in the tropics (Boccippio and Christian,
1999; Christian et al., 1999).
c 2003 Elsevier Science Ltd. All rights reserved.
1364-6826/03/$ - see front matter doi:10.1016/S1364-6826(03)00076-2
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I.R.C.A. Pinto, O. Pinto Jr. / Journal of Atmospheric and Solar-Terrestrial Physics 65 (2003) 733 – 737
Fig. 1. Map of Brazil, indicating the <ve diFerent regions.
In this paper, the lightning distribution in Brazil is reviewed, based on all lightning and lightning-related information available. Although signi<cant progress has been done
in the last decade, the information is still not suBcient to
have a complete view of the lightning distribution.
Fig. 2. Thunderday map of Brazil. The values of thunderstorms
days per year are divided into three categories: (a) white regions,
up to 50 days per year; (b) hatched regions, from 50 to 100 days
per year; (c) black regions, from 100 to 150 days per year.
2. Lightning distribution
The <rst observations related to the lightning activity
in Brazil were done in the beginning of the 1960s, when
the keraunic level, that is, the number of days per year on
which thunder is heard at a given location, was begun to be
recorded at diFerent parts of the country. These observations
(Fig. 2) were done along three decades and provided the
<rst information (keraunic or thunderday map) related to
lightning activity in Brazil. Fig. 2 was obtained from the
Brazilian lightning standard for lightning protection
NBR-5419, modi<ed in the southeast to include information provided by the Companhia EnergHetica de Minas
Gerais (CEMIG). Based on this map, it can be concluded
that in most parts of Brazil thunderstorms occur in more
than 50 days per year. In a large fraction of the country,
they occur in more than 100 days per year. The maximum
value of approximately 140 thunderstorm days per year occurs apparently in the Amazon region and in the southeast
region.
Another observation related to the lightning activity
is the average precipitation. Fig. 3 shows a map of the
average annual precipitation from 1960 to 1980. The 7gure
was provided by the Brazilian Institute of Meteorology
(INMET). The precipitation geographical distribution is
Fig. 3. Map of the average annual precipitation in Brazil from 1960
to 1980. The precipitation values are divided into three categories:
(a) white regions, below 1500 mm per year; (b) hatched regions,
from 1500 to 2500 mm per year; (c) black regions, above 2500 mm
per year.
similar to the geographical distribution of thunderstorm
days shown in Fig. 1, although small diFerences can be observed. The diFerences are probably related to the limited
I.R.C.A. Pinto, O. Pinto Jr. / Journal of Atmospheric and Solar-Terrestrial Physics 65 (2003) 733 – 737
coverage of the observations in both cases, but may also
re5ect the contribution of diFerent types of thunderstorms
and nonthunderstorm clouds to the total precipitation.
At the end of the 1980s, the <rst direct lightning observations in Brazil were done in the southeast region through
several diFerent techniques, including 5ash counters, electric <eld sensors on board stratospheric balloons, instrumented towers, and an LF/VLF lightning detection network
(Diniz et al., 1996a,b; Pinto et al., 1992a, 1996, 1997, 1999a
Pinto et al., 1992b, 1999b). From these observations, it was
found that the lightning geographical distribution can be
quite diFerent from that estimated from the keraunic level
(Pinto et al., 2000a). Also, it was found that the estimated
peak current, multiplicity, and percentage of positive 5ashes
obtained by the lightning network were not in agreement
with measurements using instrumented towers in the same
region (Pinto et al., 2000b, 2003; Pinto and Pinto, 2000).
One of the towers, located near Belo Horizonte, MG, begun operation in 1985 and up to the present recorded the
current waveform of about 80 5ashes, approximately 95%
of negative polarity. Considering only downward negative
5ashes, an average peak current of 47 kA and an average
multiplicity of 3.3 were obtained. The other tower, located
in São JosHe dos Campos, SP, made radiation measurements
of about 500 5ashes from 1996 to 1999, obtaining an average multiplicity of 2.7 for negative 5ashes and a percentage
of positive 5ashes below 5%. These peak current and multiplicity values are higher than the values obtained by the
lightning detection network, which recorded average peak
current of about 35 kA and multiplicity of 1.8 (Naccarato et
al., 2001). In contrast, the values of percentage of positive 5ashes are lower than the values obtained from the
network.
In the 1990s, with the use of the new technology of optical sensors on board orbiting satellites, it was possible to
detect the total (cloud-to-ground and intracloud) lightning
activity in Brazil (Christian et al., 1999). From recent results obtained by the lightning imaging sensor (LIS), in orbit aboard the tropical rainfall measuring mission (TRMM)
satellite since December 1997, a map of the lightning activity in Brazil could be obtained (see Fig. 4). The map
corresponds to a 3 year period (1998–2000). Although the
lightning does not provide continuous coverage of Brazil,
the 3-year period is believed to give an approximate estimate of the large-scale climatological total 5ash rate. The
5ash density in Fig. 4 was corrected for estimated detection
eBciency, assumed as geographically invariant and equal
to 90%, and for the variability in the total sampling time
at each location (Blakeslee, private communication). Due
to the lack of discrimination between cloud-to-ground and
cloud 5ashes, however, these results should be seen with
care, since they represent more closely the total lightning
activity than the cloud-to-ground lightning activity. A comparison between the map obtained from LIS observations
and the thunderday map shows some common features, for
example the low values in the northeast region, and some
735
Fig. 4. Map of the average 5ash density in Brazil obtained
by the Lightning Imaging Sensor (LIS) on board the TRMM
satellite from December 1997 to December 1999. The density values are divided into three categories: (a) white regions, below 5 5ashes km−2 yr −1 ; (b) hatched regions, from
5 to 10 5ashes km−2 yr −1 ; (c) black regions, from 10 to
15 5ashes km−2 yr −1 .
distinct features, for example the diFerences in the south,
southeast and center regions. In particular, the LIS map indicates that the largest region of lightning activity is outside
the Amazon region in contrast with the thunderday map.
In the 1990s, there was also an expansion of the LF/VLF
lightning detection network in Brazil from four sensors installed in southeast region in the beginning of the decade
to 23 sensors installed in the southeast, south, and north
(Blakeslee et al., 1999) regions at the end of decade (see
Fig. 5). At present time, these sensors are being integrated
to produce a national lightning detection network. While
the integration is not complete, data for periods longer than
1 year are available only from small networks and for small
regions (see Fig. 6). All data in Fig. 6 were corrected assuming the estimated detection eBciency of the networks equal
to 80%, neglecting small diFerences due to the diFerent network con<gurations. Although this assumption may be very
approximate, we believe that it does not aFect the results of
this paper. Also, only positive 5ashes with peak current values above 10 kA were considered in order to avoid a possible contamination by intracloud 5ashes, even though this
assumption has no signi<cant impact on the results in this
<gure. For a grid of about 50 × 50 km, the small region in
southeast presented maximum cloud-to-ground <ash densities between 10 and 15 flashes km−2 yr −1 , a value of
the same order of the maximum in the United States, which
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I.R.C.A. Pinto, O. Pinto Jr. / Journal of Atmospheric and Solar-Terrestrial Physics 65 (2003) 733 – 737
Fig. 5. Map of Brazil, indicating the location of the LF/VLF lightning sensors. The sensors represented by dots are sensors already
in operation and those represented by crosses begin operation in
2001.
occur in Florida. In the north and south regions, the maximums were between 5 and 10 5ashes km−2 yr −1 . It is likely
that higher values exist if small grids were considered. The
diFerence in the 5ash density in the border of the two small
regions in the southeast and south in Fig. 6 might be due to
the small number of sensors.
Based on all information available today, we estimate (as a conservative value) that about 50 –70
millions cloud-to-ground 5ashes occur every year in
Brazil, corresponding to an average 5ash density around
6 –8 5ashes km−2 yr −1 .
Fig. 6. Map of Brazil showing the regions where 5ash densities
have been obtained for a period longer than 1 year with a constant network con<gurations. The density values are divided into
three categories: (a) white regions, below 5 5ashes km−2 yr −1 ;
(b) hatched regions, from 5 to 10 5ashes km−2 yr −1 ; (c) black
regions, from 10 to 15 5ashes km−2 yr −1 . The values correspond
to the year of 1999 in the vicinity of the state of Rondônia, the period from 1989 to 1997 in the vicinity of the state of São Paulo, and
the period from 1996 to 1998 in the vicinity of the state of ParanHa.
Acknowledgements
The authors would like to thank the FundaNcão de
Amparo aO Pesquisa do estado de São Paulo (FAPESP) and
the Conselho Nacional de Desenvolvimento CientHP<co e
TecnolHogico (CNPq) for providing support for the
research.
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3. Conclusions
In the last decade, there was a signi<cant progress in the
lightning observations in Brazil. The analysis of the results
suggests that about 50 –70 million cloud-to-ground lightning
5ashes occur every year, most concentrated in the north, center, and southeast regions of the country. Also, it suggests
that high 5ash densities larger than 10 5ashes km−2 yr −1
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