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C.G. Collier
Table 6.1. Spectrum of precipitation-producing systems (after Mason, 1970)
Idikm
Planetary
M
I
D
D
L
E
L
A
T
I
T
U
D
E
S
T
R
o
P
I
C
S
Long
Waves
SubTropical
AntiCyclones
ITCZ
Easterly
Waves
HORIZONTAL SCALE
101km
lO~km
Synoptic
Meso-scale
ExtraFronts
Tropical
Depressions
AntiCyclones
Cloud
Clusters
Tropical
Cyclones
Lee Waves
Squall Lines
Meso-scale
Convective
Elements
Time Scale
SCALES OF MOTION
6.2 General approach
6.2.1 Ground-based radar
10km
5km
Convective or
Small scale
Cumulonimbus
Showers
Tornadoes
Convective
Cells
Ikm
Microscale
Molecular
BoundaryLayer
Eddies
Boundarylayer
eddies
I HR
10 HR
Ground-based radar offers areal measurements of precipitation from a single location,
over large areas in near real-time. Both single and multi-polarisation radars have been
used over a range of wavelengths. However, the most commonly used wavelengths
lie in the region of the electromagnetic spectrum which includes wavelength of3cm
(x-band), 5 cm (c-band) and 10 cm (s-band).
As a radar beam rotates about a vertical axis, measurements are made at many
ranges out to 100 km or more, and at difference azimuths, of the energy backscattered