The TRIMREX Field Project:An OSSE Study

Shu-Hua Chen /UC Davis

This work is supported by NTFRI and NSC in Taiwan

Other contributors:

Jhih-Ying Chen (NCU), Wei-Yu Chang (NCU),Wen-Yih Sun (NTFRI), Pay-Liam Lin (NCU), Po-Hsiung Lin (NTU), Tai-Chi Chen (NCU),Yu-Chieng Liou (NCU)

Introduction

Where and when should we use additional instruments to obtain better analysis and forecasts ?• Location of the TEAM-R?

• Location of ISS wind profiler?• Frequency of radiosondes?• Pattern and frequency of dropsondes?

Motivation

Use OSSE to investigate better use of additional instruments during TIMREX.

Introduction

Observing System Simulation Experiments

Def: An observing system experiment in which synthetic meteorological observations are used as a surrogate for real observations. The assimilation of these observations and subsequent free forecasts are conducted the same as with real observations. The synthetic observation are usually extracted from a long forecast from a high resolution, state-of-the art model, known as a “nature run”, which acts as a proxy atmosphere specifically for the OSSE. (from http://sivo.gsfc.nasa.gov/OSSE)

OSSE

OSSE Flow Chart

Introduction

Nature run: High-resolution (1km) WRF simulations

Simulate existing & additional observations

WRF Var first guess (NCEP reanalysis)

Assimilate simulated observations

Perform WRF runs and evaluate simulated observations

Applied to TIMREX project

Nature Run – Configuration

D02

D03

D04

D01

Domain Grid points Resolution

1 141 x 121 x 31 27 km

2 331 x 271 x 31 9 km

3 721 x 541 x 31 3 km

4 901 x 961 x 31 1 km

Simulated observations

Nature Run – Physics Schemes

RadiationRRTM long waveGSFC short wave

CumulusGrell-Devenyi ensemble (domains 1 and 2 only)

PBL MYJ TKE

Microphysics Purdue

Simulated observations

WRF integrates from 00Z June 6 to 12Z June 9, 2003

Z = 3 km, June 06/00Z – 09/12Z, 2003, interval – 6h

Nature Run – Simulated Radar Echo

Simulated observations

Simulated observations

WRF domain 4 simulation with the 1 km resolution from 18Z June 6 to 00Z June 7, 2003 was use to simulate existing and additional observations. These observations will then be assimilated in WRF numerical experiments for evaluation.

Z = 3 km, June 06/18Z, 2003 Z = 3 km, June 07/00Z, 2003

Nature Run – Simulated Radar Echo

Simulated observations

List of Simulated Observations

Existing observations:

Additional observations:

Radar radial velocityRadiosondesSurface stationsEPS wind profiler

S-POL radar radial velocityTEAM-R radial velocityNCU ISS wind profilerRadiosondesDropsondes

Simulated observations

Maximum distance ~ 250 km

Gate resolution – 1 km

Beam resolution – 1 degree

Existing radar & SPOL

Simulated Radar Data Strategy

Scanning angles : 0.5, 1.5, 2.4, 3.3, 4.3, 6.0, 9.9, 14.6, 19.5

degree

Maximum distance ~ 40 km

Gate resolution – 1 km

Beam resolution – 1 degree

TEAM-R

Three potential sites :22.75 lat, 120.47 long

22.88 lat, 120.64 long

22.88 lat, 120.21 long

Simulated observations

Potential position for TEAM-R

Position for S-POL

Existing radar

Simulated Doppler Radar Locations

Simulated observations

x

y

zVr1

Vr2

Vr3

u

wv

αβ

βsin/)βcosVV(v

αsin/)αcosVV(u

Vw

βcoswβsinvV

αcoswαsinuV

wV

rr

rr

r

r

r

r

13

12

1

3

2

1

Simulated Wind Profiler Winds

Simulated observations

ISS wind profiler

EPA Wind profiler

Simulated Wind Profiler Locations

Simulated observations

Data taken every 20 Seconds Wb = 5 m/s

x

y

z

u

v

w

wb

ft

tb dt )ww(vu S

0

222

Simulated Radiosondes

Radiosonde track

Simulated observations

Regular sites:Ban-ChiaoHua-LianMa-Kung Green-IslandDong-Sa

Additional sites:Tai-ChungTai-NanPeng-DongHeng-ChunISSShip

Simulated Radiosonde Locations

Simulated observations

33 CWB surface stations

Simulated Surface Station Locations

Simulated observations

z

x

y

u

vw

-wd

ft

td dt )ww(vu S

0

222

Simulated Dropsondes

Wd

Hock and Frnaklin (BAMS, 1999)

Dropsonde track

Simulated observations

Simulated Flight Patters

Simulated observations

Simulated Flight Patters

Numerical Experiments - Configuration

Domain Grid points Resolution

1 133 x 115 x 31 27 km

2 241 x 181 x 31 9 km

3 271 x 250 x 31 3 km

Experiment design

D02

D03

D01

Same physics were chosen as the nature run

Experiment design

Numerical Experiments

WRF Var cycling WRF integration

6 h 1.5 days

Time (h)

0 36 -3-6 -5 -4 -1-2

Obs Obs Obs Obs Obs ObsObs

Case WRF Var data cycling WRF simulation

2003 18Z/06 – 00Z/07 00Z/07 – 12Z/08

Experiment design

Temperature at the 1st Half Model Level

First Guess (NCEP reanalysis)

18Z/06/06/2003

Nature run (18h simulation)

Experiment design

Moisture at the 1st Half Model Level

18Z/06/06/2003

Nature run (18h simulation) First Guess (NCEP reanalysis)

Experiment design

Wind Speed at the 1st Half Model Level

18Z/06/06/2003

Nature run (18h simulation) First Guess (NCEP reanalysis)

Experiment design

Numerical Experiment Design

EXPERIMENT Assimilated OBs

BEST_NORAD3 hourly radiosondes (existing + additional)Hourly surface stationsHourly Wind profiler

NONE No observation

Experiment design

Nature run BEST_NORAD NONE

00Z/06/07/2003 (After WRF Var cycling)

Temperature at the 1st Half Model Level

Experiment design

Moisture at the 1st Half Model Level

Nature run BEST_NORAD NONE

00Z/06/07/2003 (After WRF Var cycling)

Experiment design

Nature run BEST_NORAD NONE

00Z/06/07/2003 (After WRF Var cycling)

Wind Speed at the 1st Half Model Level

Experiment design

Still work on the assimilation of simulated radar winds (close to finish)

Still work on the assimilation of dropsondes (close to finish)

Keep evaluating the OSSE system and hopefully will finish before the TIMREX starts.

On Going