|Title||Annual lightning data (base climatological data sets):
Annual lightning ground flash density & annual lightning total flash density.
|Custodian||Bureau of Meteorology|
|Abstract||Mean annual number of of lightning flashes per square km.
The grids show the number of lightning flashes per square km per year across Australia in the form of two-dimensional array data.
The mean data are based on the eight year period 1995-2002.
See LINEAGE below for more information.
|Search Word(s)||Gridded, analyses, climatology, lightning, meteorology|
|Geographic Extent Names(s)||Australia|
|General Category||Gridded climatological data|
|General Custodian Jurisdiction||Australian Government
|Geographic Extent Polygon||Not applicable|
|Geographic Bounding Box||See below|
|North Bounding Latitude||-8.500|
|South Bounding Latitude||-44.00|
|East Bounding Longitude||160.00|
|West Bounding Longitude||107.50|
|Stored Data Format||Arc/InfoTM grids - all Australia|
|Available Format Type||ASCII grid-point, Arc/InfoTM grid Interchange (.e00),Shapefiles.|
|Access Constraint||Please note that the copyright for any data supplied by the Bureau of Meteorology is held in the Commonwealth of Australia and the purchaser shall give acknowledgement of the source in reference to the data. Apart from dealings under the Copyright Act 1968, the purchaser shall not reproduce (electronically or otherwise), modify or supply (by sale or otherwise) these data without written permission from the supplier. Please contact us (see details below) for more information.|
|Lineage||The lightning total flash density grid and lightning ground flash density
grid are based on data from the Optical Transient Detector (OTD) and
Lightning Imaging Sensor (LIS) for the Australian region (10°S - 45°S, 105°E - 165°E).
It is important to note that the analysis is based on eight years of combined OTD and LIS data.
The grid point resolution of the data is 0.5° (approximately 50 km).
The data are acquired from polar orbiting satellites and consequently undersampling may influence the estimates of lightning activity in some areas (Kuleshov et al. 2006).
The satellite data were calibrated against the data derived from observations obtained by ground-based lighting flash counters and then adjusted applying an empirical polynomial in a form
with λ in magnitude of degrees, A=1.2339, B=2.8108E-3, C=1.3661E-5, and N=3.5.
The adjusted NtSAT values obtained by multiplying each NtSAT value by RLNP(λ) were used to produce the total flash density map for Australia (Kuleshov et al 2006).
Applying the assumption that the value of cloud flash-to-ground flash ratio, Z, over the range of latitude for the Australian continent is uniform (Z = 2), the
Ng values were derived from the average annual total flash density values Nt, by using the equation
OTD and LIS estimates of lightning ground flash density (Ng) were compared with, and evaluated against, estimates of Ng derived from a thunder day analysis as well as from direct measurements obtained by ground-based lightning flash counters (Kuleshov et al 2006).
Ng is conventionally estimated from Td using an equation of the form Ng=aTdb, in which a and b are empirically derived constants that are influenced by the meteorological conditions at a given location. In this study, Kuleshov and Jayaratnes formula with derived values of a= 0.012 and b=1.4 was used (Kuleshov and Jayaratne 2004).
Kuleshov, Y. and Jayaratne, E. R. 2004. Estimates of lightning ground flash density in Australia and its relationship to thunder-days. Aust. Met Mag. 53, 189-196.
Kuleshov, Y., Mackerras, D., and Darveniza, M. 2006. Spatial distribution and frequency of lightning activity and lightning flash density maps for Australia. J.Geophys.Res., Vol. 111, D19105, doi:10.1029/2005JD006982.
|Positional Accuracy||The OTD and LIS data on which the analysis was based have an associated accuracy of the order of 0.1° (approximately 10 km) or better.
|Attribute Accuracy||Not applicable|
|Logical Consistency||Not applicable|
|Completeness||No missing data|
|Contact Organisation||Bureau of Meteorology|
|Contact Position||Climate Data Services|
|Mail Address||PO BOX 1289, Melbourne 3001, Australia|
|Telephone||(03) 9669 4082|
|Facsimile||(03) 9669 4515|
|Additional Metadata||Additional information available on request (see contact above).|