04/18/23
Prediction of the 10 July 2004 Beijing Flood with a High-Resolution NWP model
Ying-Hwa Kuo1 and Yingchun Wang2
1. National Center for Atmospheric Research, USA
2. Beijing Meteorological Bureau, China
04/18/23
Model Configuration
Two domain, run in two-nested mode Domain 1: 12 km; domain 2: 4 km Physics used in domain 1:
o KF CU, YSU PBL, 5-layer soil model (not LSM), RRTM lw, Dudhia sw
Physics used in domain 2:o Same as in domain 1, except no KFo Two different micropysics options: Lin et al. (1983)
and WSM-6
04/18/23
Data Used
NCEP Global Forecast System (GFS) final analysis at 1 degree resolution
Radiosonde, surface and AWS observations obtained from Beijing Meteorological Bureau (BMB)
Ground-based GPS PW from Fang Shan obtained from BMB
04/18/23
Experiments
Control: or experiment Ao GFS data only, used for both IC and BC
3DVAR 1: or experiment Bo GFS + radiosonde, sfc + AWS
3DVAR 2: or experiment Co GFS + radiosonde, sfc + AWS + GPS PW
All experiments start at 1200 UTC 7/9/04 and run for 36 hours
04/18/23
Differences of WSM-6 from Lin et al. microphysics
Differences in the assumption of particle size and number distributions for ice particles.
Melting is done on small fall-term timesteps to make it more accurate as a function of height.
Saturation processes are difference. o Line et al. use some combined ice/water saturation vapor pressure
based on temperature
o WSM-6: Ice particles respond to ice saturation and water particles respond to water saturation.
Accretion of particles takes into account of the fall speeds of both species, not just the faster falling species.
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The GPS network in FangShan Beijing area of China
115.5 116 116.5 117 117.5oE
39.5
40
40.5
No41
DDSS
SGZD
GDSS
HCHDLLHS
YCSS
QLHD
YSDD
54511
RAIN_GAUGE
116 116.2 116.4oE
39.6
No39.8
54511(Brown Square): The Radiosonde Station
RAIN_GAUGE(Green Diamond): The FangShan AWS
Black triangle: Four Single Frequency GPS Stations of BMB
Black circle: Four Dual Frequency GPS Stations of BMB
. 8 GPS Stations with mean distance less than 10km
. A Vaisala AWS(P,T,RH) built on each GPS station
. YSDD->54511 ~ 30 km
. YCSS->RAIN_GAUGE ~ 5km
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0709 0710 0711
20
25
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0:00
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Radi
oson
de &
GPS
PWV
(mm) Radi osonde
YSDD
DDSS
SGZD
GDSS
HCHDLLHS
YCSS
QLHD
YSDD
54511
RAIN_GAUGE
116 116.2 116.4oE
39.6
No39.8
30km
04/18/23
0709 0710 0711
20
25
30
35
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55
60
0:0
0
3:0
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6: 0
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9: 0
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12:
00
15:
00
18:
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21:
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0: 0
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3: 0
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6: 0
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9: 0
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0: 0
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3: 0
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PWV(
mm)
0
2
4
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Prec
ipit
atio
n(mm
)
Preci pi tat i onYCSS_PWV
0
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0:00
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PWV(
mm),
T(℃
),Td
(℃)&
Sca
led_
P
13
15
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21
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25
27
29
q(g/
kg)YCSS_PWV YCSS_T
YCSS_P YCSS_TdYCSS_q
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Preliminary Conclusions WRF 4-km model initialized with the NCEP GFS analysis did not produce any
precipitation over Beijing. GFS is quite good on the larger scale, it is the mesoscale details that it fails to capture.
WRF 3D-Var assimilation of local data set makes a big difference in the stability of the local convective environment.
Simulation of convective evolution is sensitive to quality of mesoscale analysis and precipitation microphysics
CAPE CIN
GFS 24 -362
BMB 436 -232
BMB + GPS 756 -183