Preliminary Simulation of Typhoon Rananim with AREM. Rucong Yu, Rui Cheng, Youping Xu Chengzhi Ye, and Aihua Xu. LASG, IAP, CAS. Jun. 1, 2005. CONTENTS. Brief Overview of Typhoon Rananim. Observational Features. Experimental Design. Model Verification. Summary and Conclusions. - PowerPoint PPT Presentation
TRANSCRIPT
Preliminary Simulation of Typhoon Rananim with AREM
Rucong Yu, Rui Cheng, Youping Xu
Chengzhi Ye, and Aihua Xu
LASG, IAP, CAS
Jun. 1, 2005
Charles R. Cheng
Good afternoon Professors and chairman.This afternoon I'll give you a talk about simulation of typhoon Rananim with AREM.
CONTENTS
Brief Overview of Typhoon Rananim
Experimental Design
Model Verification
Summary and Conclusions
Observational Features
Charles R. Cheng
This presentation has 5 parts.1st, the introduction of typhoon Rananim given,2nd, is about 3rd part is the 4th isat last, will give
I. Brief Overview of Typhoon Rananim
Charles R. Cheng
First ,let's see the brief introduction of Rananim.
Landfall in Zhejiang occurred at 1200UTC on Aug. 12, 2004
Although early detection of Typhoon Rananim cut losses to a minimum , It ravaged the Chinese eastern provinces. Confirmed by meteorological authorities to be the worst typhoon to hit China since 1956. “Rananim” won’t be used to name typhoon in future and as the specified name of Typhoon NO. 14 last year.
Affecting the lives of 18.18 million people, the strong winds and torrential rain caused more than 21.04 billion Yuan (U.S. $2.53 billion) in direct economic losses.
Demolishing 212,600 homes and damaged reservoirs and power communication facilities.
The death toll was at 183, while about 500,000 were evacuated from their home.
Charles R. Cheng
So it has the greatly devestating impact on China.
A Chinese family was drenched by the storm in the city of HangZhou, August, 12, 2004.
Two men try to prevent a tricycle from being blown away by a gale in Wenzhou, Zhejiang, on August 12, 2004.
At 12 UTC, 08AUG2004, originating from tropical disturbance at the ocean surface in the east of Philippines
At 18 UTC, 10AUG2004, intensified to Typhoon Rananim
At 12 UTC, 12AUG2004, landfall over Zhejiang Province and moving westward
At 03 UTC, 13AUG2004, weakening to tropical storm
At 09 UTC, 13AUG2004, reducing still to depression
Evolution Stages
Charles R. Cheng
Five stages of Rananim are presented in this slide.and 6 hours later, it reduced still to
Minimum SLP, 950 hPa
Maximum wind, 58.7 m/s
Strong small eye storm, its diameter approximates to 45km
Precipitation, 874.7mm/24h; 600mm/12h
Strong echo appearing at the levels between 3 and 6km, not very high
Large affected area
Basic FeaturesA
t the lan
dfall
Charles R. Cheng
Six basic features of Rananim can be summarized here.it belongs to strong small eye storm,its precipitation about 874.7mm in 24 hours, and in 12 hours after its landing,rainfall amounts to 600mm.
II. Observational Features
Charles R. Cheng
The 2nd part is Rananim's observational features.
Data used:Typhoon Rananim’s Warning Report
Intensive surface observations
NCEP Analysis Data
Conventional observations
IR-Cloud images and TBB Data of Goes-9
Doppler Radar images
Charles R. Cheng
These data was used to analyze typhoon and verify the simulation.
Track of Rananim (Provided by Zhejiang Meteorology Administration)
Charles R. Cheng
This map was provided by Zhejiang and from it, we can see typhoon moved northwards in its first two-day track,and then westwards and northwards again.After 02UTC,11 Aug., Rananim moved northwestwards until it landfell.It proceeded westwards during its moving in the land.
Precipitation by Rananim (Provided by Zhejiang Meteorology Administration)
00000000 UTC, 12~ 00000000 UTC, 13
Charles R. Cheng
and torrential rain poured down all over the Zhejiang Province, esp. 372.2 mm rainfall in Leqing.
Radial velocity from Doppler Radar at Wenzhou
Averaged echo height from Doppler Radar at Ningbo
Vertical slice of Radar echo
Charles R. Cheng
and from these pictures, we can see the destructive winds and strong echo on lower levels.
S)• Initialization, De-grib NCEP analyses, or Cressman Iteration• Physical processes, simple but practical• Model mesh, nested• Used to forecast heavy rainfall operationally, to perform typhoon, environment
al simulations etc. • Good performance in simulating and forecasting Chinese torrential rainfall
Domain Mesh A Mesh B
Area coverageX: 85E150EY: 5N60N
Z: surface10 hPa
X: 111E131EY: 16N36N
Z: surface10 hPa
Dimensions(grid numbers)
13122132 12124132
Grid size (km) ~37km ~12km
Time step (s) 225s 90s
Integration hours1200 UTC on 11th
0000 UTC on 14th1200 UTC on 11th
0000 UTC on 14th
Initial conditions NCEP Analysis (1°×1°), Without Bogus
This table gave us Ex. design and initial conditions.Two meshes with grid space of 37km and 12km were used ;they are domains and dimensions here.Two models were initialized at 12utc on 11 Aug., 2004, and simulation time is 60 hs.Initialization was easy with Ncep analysis and without bogus; constant weekly SSTPhysical parameterization is given here.
Synoptic fields Mesh A
Storm-scale fields Mesh B
Model Verification
IV.
Charles R. Cheng
The following part is model verification.Mesh A and B were used simultaneously to test the performance of AREM in modeling synoptic and storm-scale fields respectively.
obv
fct
18Z11Aug2004 00Z12Aug2004 06Z12Aug2004
a) Synoptic fields (Mesh A)
Height (colored) and temperature (black) on 500 hPa
Charles R. Cheng
Firstly, see the 500hPa weather map.upper is observed, and lower is simulated.We can find locations and intensities of the cold front and sub-tropical high simulated accurately.So the steering flow of typhoon is very similar to the real.
obv
fct
18Z11Aug2004 00Z12Aug2004 06Z12Aug2004
a) Synoptic fields (Mesh A)
Rel. Hum. (colored) and stream (black) on 700 hPa
Charles R. Cheng
This slide gives us humidity and stream on 700hPa for different times, and uppper is observed, lower is simulated.Three moisture sources were depicted similarly to the observed, but simulated intensity of moisture transportation was weaker; weaker moisture strength and smaller speed too.
obv
fct
18Z11Aug2004 00Z12Aug2004 06Z12Aug2004
a) Synoptic fields (Mesh A)
Total moisture flux divergence and stream on 700 hPa
Charles R. Cheng
From the picture of total moisture flux divergence, we can also see the simulated moisture convergence next to typhoon (lower) was weaker.moisture convergence appeared over the typhoon region for the observed, but maily divergence for the simulated.
b) Storm-scale fields (Mesh B)
0300 UTC 12AUG2004
0400 UTC 12AUG2004
0500 UTC 12AUG2004
Infrared Satellite images (lower) and a top view of the simulated hydrometeors (upper), as determined by the 0.1g/kg surfaces
Charles R. Cheng
From this slide, simulated storm-scale fields by mesh B will be compared with Ncep analysis.The lower is infrared sta. images, and the upper is the simulated hydrometeors, we can see the eye, eye wall and spiral cloud band were simulated clearly and very similar to the real.Moreover, we can find the convection appearing in the eye wall for both.
b) Storm-scale fields (Mesh B)
0600 UTC 12AUG2004
0700 UTC 12AUG2004
0800 UTC 12AUG2004
Infra Satellite images (lower) and a top view of the simulated hydrometeors (upper), as determined by the 0.1g/kg surfaces
Charles R. Cheng
This slide same as the last but for different times.
TBB of GOES-9 (upper, C) and simulation (lower, C)
Charles R. Cheng
From the figure of TBB, we can find the convection easily.
b) Storm-scale fields (Mesh B)
Streamline on 700 hPa and Precipitation Rate (mm/h)
Charles R. Cheng
This slide is the animated hourly precipitation and stream field.We can the evolution of heavy rainfall caused by typhoon.
1113
1209
1117 1121
1201 1205
A 3-D view of constant surface of equivalent potential temperature
=346K e
Charles R. Cheng
This slide is 3D-view of constant surface of equivalent potential temperature. Here, the constant of ept is 346K.
Hydrometeors (shaded, kg/kg) and vertical velocity (black, hPa/s), longitudinal and latitudinal slice near the core
b) Storm-scale fields (Mesh B)
Charles R. Cheng
From these longitudinal and latitudinal slice near the core, it is easily found that the eye wih clear sky and slight descending motion and the eye wall with strong ascending motion and much cloud.
Pseudo-equivalent potential temperature (K),
vertical slice near the core
Charles R. Cheng
This slide is the initial vertical slice of Psudo-equivalent potential temperature near the core.We can see the warm core of the typhoon.and after 12hs simulation, the model continued to depict the thermal structure well.
Observed and simulated rainfall (mm) from 1200 UTC 11AUG2004 to 1200 UTC 12AUG2004
obv. mesh A mesh B
B B
Charles R. Cheng
This slide gives us the precipitation of obv., and rain simulations of 37km, and 12km. respectively.We can see the simulated rainfall distribution of both mesh A and B is similar to the obv. And when the model resolution is finer from 37km to 12km, the modeled heavy rainfall center is closer to the obv., and more detailed and reasonable structure of precipitation can be obtained.We chosen grid point B and drew the curve of rainfall evolution at this point.
Evolution of daily rainfall (mm)
observed
simulated
Charles R. Cheng
And this picture is the evolution of daily rainfall from 12utc on Aug. 11, 2004 to 12utc on 12th.We can find that four main rainfall processes were simulated well, although after 03utc on 12th, the modeled lagged behind the obv.
12Z11
18Z11
00Z12
06Z12
12Z12
Track of Typhoon Rananim
Red: observed
Blue: simulated (~12km)
Charles R. Cheng
The simulated and observed typhoon's track 24 hs before landing are given in this picture. We can find the modeled result is very close to the obv., esp. the landfall location, and the maximum offset distance between the simulated and the obv. is less than 100km.
Evolution of SLP (hPa)
Evolution of traveling speed (km/h)
Red: observed
Blue: simulated (12km)
~20 hPa
Charles R. Cheng
This slide presents evolutions of SLP and traveling speed of Rananim.We can see the initial strength of typhoon was about 20hPa weaker than the obv.and if we leave out consideration of this difference, the simulated offset from the real was roughly 10hPa. From this picutre, we can see the modeled traveling speed similar to the obv.
V. Summary and Conclusions
Charles R. Cheng
Finally, let's summarize this presentation and draw conclusions.