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Typical(?) Diurnal Variation of Radar Echo over Bangla.
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Typical(?) Diurnal Variation of Radar Echo over Bangla.
Toru Terao(Osaka Gakuin Univ.)Md. N. Islam(BUET, Banlgadesh)
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Bangladesh RADAR Four RADAR data
Dhaka RADAR is used mainly
Intensive rawin sonde obs.
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Dhaka RADAR Continuous observations are
conducted basically only for one hour duration for every other three hours, as follows; 5-6, 8-9, 11-12, 14-15, 17-18, 20-21, 23-
24BST. Almost all area of this country except
for southeastern most part is covered.
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Fig10
Fig. 10. Same as Fig. 7 except averaged for 1 August to 30 August 2000.
NE part:Night-E. Morning
S part:E.
Morning
C-W part:Daytime
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Area & Number of Echoes
Dhaka Radar
0
2
4
6
8
10
12
14
00 06 09 12 15 18 21
TIME(LST)
Ech
o E
mbe
dded
Are
a(10
3 k
m2/s
can)
APR MAY JUNJUL AUG AMJJA
Echo Embedded Area Dhaka Radar
0
10
20
30
40
50
60
70
80
90
100
00 06 09 12 15 18 21TIME(LST)
Fre
quen
cy o
f Occ
urre
nce/
scan
APR MAY JUN
JUL AUG AMJJA
Freq. of Occurrence
Afternoon: many small
echoes
Midnight: max. echo area
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Statistical Results NE part:
Heavy rain, Midnight-morning peak Larger echoes
S part(coastal area): Heavy rain, Morning peak
C-W part(plain): Light rain, Afternoon peak Many smaller echoes.
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Convection: 17/18 July 2001A typical pattern of the diurnal variation will be shown
using Dhaka RADAR data.
17 July 18 July
8:30, 11:30, 14:30, 17:30, 20:30, and 23:30
A case study
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Convection: 17/18 July 2001A typical pattern of the diurnal variation will be shown
using Dhaka RADAR data.
17 July 18 July8:30
No conv.
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Convection: 17/18 July 2001A typical pattern of the diurnal variation will be shown
using Dhaka RADAR data.
17 July 18 July11:30
SWscattering
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Convection: 17/18 July 2001A typical pattern of the diurnal variation will be shown
using Dhaka RADAR data.
17 July 18 July14:30
SWdeveloping
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Convection: 17/18 July 2001A typical pattern of the diurnal variation will be shown
using Dhaka RADAR data.
17 July 18 July17:30
Eforming
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Convection: 17/18 July 2001A typical pattern of the diurnal variation will be shown
using Dhaka RADAR data.
17 July 18 July20:30
E -> NESquall line
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Convection: 17/18 July 2001A typical pattern of the diurnal variation will be shown
using Dhaka RADAR data.
17 July 18 July23:30
NEspread
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Morning to afternoon: Scattering convectionsover the south western part of Bangladesh
Typical Diurnal Variation
Evening to Midnight: Organized convectionsover the north eastern part of Bangladesh
Patterns are strikingly similar for two days
17 and 18 July 2001
We should clarify why such pattern appeared.
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Comparison with prev. study
RADAR data Ohsawa et al. (2001)
Midnight
Noon