preliminary simulation of typhoon rananim with arem

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.

Charles R. Cheng

This is the real scene at Rananim landfall.

http://www.thewe.cc/this_is_real.html

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.

III. Experimental Design

Charles R. Cheng

The following part is the Ex. Design.

AREM Overview

• Advanced Regional Eta-coordinate Model• Dynamic core, fully energy-conservative time-space difference• Vertical coordinate, η, Horizontally spaced in Arakawa E-grid• Moisture transportation, Two-step Shape Preserving Advection Scheme (TSPA

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

Physical processesBetts-Miller C.P., non-local PBL, Warm-cloud M.P. , Weekly SST

Experimental Design and Initial Conditions

Charles R. Cheng

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


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


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.


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.


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


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.

1 AREM simulates Typhoon well,1 AREM simulates Typhoon well,

2 Reasonable multiple structures of Typhoon 2 Reasonable multiple structures of Typhoon obtained, obtained,

3 Further studies mainly focus on, with some problems3 Further studies mainly focus on, with some problems

Track, thermodynamic structures, landfall time and location, and evolution

Environmental background, eye, eye-wall, and spiral rain bands

sensitivity experiments, incorporation of Bogus scheme into AREM

Charles R. Cheng

First,Secondly,and third is about

Thank you！Welcome comments and advice!Welcome comments and advice!

preliminary simulation of typhoon rananim with arem

Documents

worst typhoon

rananim landfall

track of rananim

rui cheng

stages of rananim

rananim wont

brief introduction of

basic features of rananim