status of dual-doppler wind retrieval project carpe diem 6 th meeting helsinki 24 june 2004 by kheng...
TRANSCRIPT
Status of Dual-Doppler Wind Retrieval Project
Carpe Diem 6th Meeting
Helsinki
24 June 2004
by
Kheng
University of Essex
Recall in Dublin
● What we have done
– Shown visualisation examples produced by DARWIn
– Converted Polar data -> Cartesian
– Successfully constructed 3D wind fields
– Shown 2 case studies
Remarks from Dublin meeting
● Problems & comments
– Limited data sets
– How to verify validity of the constructed 3D wind fields.
– Triple Doppler retrieval
– Comparison with NWP model
New data sets● 2003 July 13 – 14
– Bologna, Gattatico, scan time (00, 12, 15, 27, 30 ...)
● 2003 July 31
– Bologna, Gattatico, Teolo
● 2003 September 09
– Bologna, Gattatico
● 2003 November 11
– Bologna, Gattatico, Teolo
Numerical procedures● Iterative method:
– horizontal components
– vertical component
● Boundary conditions:
– zero velocity on ground
● Typical convergent factor
dzd
wzw
yv
xu
1
where0
030.0,,
)1(,,
)(
,,)(
,,)1(
max
kjin
kjin
kjin
kjin
ww
ww
11 , nnnn wDCvwBAu
Comparison of reconstructed radial velocity field and radar measurement
measurement
reconstruction
Gattatico Gattatico
Bologna Bologna
“along-track” components
r1
r2
r12
v . (r12 + r2 – r1) = 0
= v(cal).r12 + vr2 (obs) r2 – vr1 (obs) r1
Typical relative deviation, /(v .r12) < ±1%
v
Problems with Triple-Doppler
● Teolo – many rays are missing
● Teolo – Doppler radial velocity convention
● Teolo – 470 m asl, lowest elevation 0.9 deg
– Minimun height ~ 1400 m (centre)
● Gattatico & Bologna – ? m asl, lowest elevation 0.5 deg
– Minimun height ~ 600 m (centre)
– Next elevation ~ 1400 m (centre)
measurement
reconstruction
Case 3: (2003 Sep 09) 1315 hr 2.3o
PPI – Radial Velocity Comparison
Gattatico Gattatico
BolognaBologna
measurement
reconstruction
Case 4: (2003 Nov 11) 0345 hr 1.4o
PPI – Radial Velocity Comparison
Gattatico Gattatico
BolognaBologna
Comparison with NWP model?
a CD with radar data has been sent to SMHI and wind field information of
several cases have been made available for comparison ...