Preliminary tests on the Cycle of Preliminary tests on the Cycle of

Hourly Assimilation and Forecast Hourly Assimilation and Forecast

system in Guangzhousystem in Guangzhou

WAN Qi-lin, CHEN Zi-tong, DING Wei-yu, HUANG Yan-yanWAN Qi-lin, CHEN Zi-tong, DING Wei-yu, HUANG Yan-yan

Institute of the tropical and marine meteorology, CMA, GuangzhouInstitute of the tropical and marine meteorology, CMA, Guangzhou

Outline

Motivation

system introduce

Some tests

conclusions

Motivation

How to make use of high frequent observation data for improving numerical analysis and forecast .

How to give a good support to nowcasting

system introduce

For short, the system is named as CFAF

CHAF - The Cycle of Hourly Assimilation and Forecast

based on Grapes - Global/ Regional Assimilation PrEdiction

System

Domain

Grid resolution:0.12°

CHAF domain

System flow chart

Pretreatment

ObservationDATA

Cycle

Boundary(from coarse model)

OperationPrediction

Increment interpolation

Increment Digital Filter

GRAPES_ MODELGRAPES-Model

background

GRAPES_ 3DVARGRAPES-Var

SimpleCloud analysis

nudging

The Case choosing to understand the basic character of CHAF

The case is about a typhoon , the typhoon is landing and tend to weaken.

At 12UTC, 13 August,2005, a typhoon have been landing at Guangdong Province.

In the simulation test, we chose 12UTC as initial time ,and have performed 24h forecast.

The scheme of experiment--to check if the cycle would give birth to noise, and if the cycle would benefit to improve analysis filed.

Test 1 ： The model run 24 hour, without cycle;

Test 2 ： The model run 24 hour, with the cycle of hourly assimilation and forcast.

The DFI window is six hour （ -3 ， +3 ）， and, the observation was not import 。

Test 3 ： The model run 24 hour, with the cycle of hourly assimilation and forcast.

The DFI window is six hour （ -3 ， +3 ）， and, the Sounding and surface observation was ingest 。

Test 1 –Control test

Test 2

test3 test1test2

Test2

Test1

Test 3

Surface observation Surface observation

Sounding

Initial field_SLP12z 13AUGCycle- test 3

observationControl Test

SLP12H Forecast00z 14AUG

Test 1

Test 3observation

500hPa Height12H forecast

Test 1

Test 3observation

12H FORECAST Rainfall ：6H Accum00z14AUG

Test 1

Test 3observation

conclusion

According to the result of the tests , we think that: the cycle of CHAF system did not arouse addi

tional error evidently, the CHAF system must be capable of assimil

ation some high frequent observation.

The tests to assimilate high frequent observation.

Cloud-drift wind Airline observation ( AMDAR ) Calculated Cloud (Cloud analysis)

Hourly asimilation of cloud-drift wind

The Vector of cloud-drift wind on 200hpa（ 2005-07-11 00 ： 00~12 ： 00UTC ）

The scheme of comparative experiment

Test 1

Initial value00 UTC

Analysis field

at 12UTC

forecast

Initial value 00 UTC

forecast

Hourlr assimilate cloud-drift wind

Analysis field

at 12UTC

Test 2

Height and Wind on 500hpa (analysis)

a. With cloud-drift wind

b. Without CDW

c ． Velocity difference between a and b

d ． NCEP analysis

a b

c d

24H precipitation （ 2005-7-11 12 ： 00UTC~2005-7-12 12 ： 00UTC ）

a ． With cloud-drift wind b ． without c ． Difference d ． Real

a b

c d

The observation distribution from Air report between 00 － 23UTC on 18 Jun. 2 （ left: time-height cross-section ; right: planform – look down ）

Test about Air report assimilation

The three-dimensional distribution of Airline observation between 04 － 06UTC on 18 Jun.

The comparative test of Air report assimilation

12Z18Jun00Z18Jun

Test2:1-h assimilation of Air report,and sounding,surf,ship

12Z18Jun

24h Forecast

24h Forecast

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23探空 46地面 346 1053 409 867 239 334 384船舶 4 14 4 7 4 15 4卫星 160飞机 128 127 75 131 155 149 162 112 54 118 105 139 200 155 38 25 15 5 5 15 6 7 35

00Z18Jun

Test1:1-h assimilation of sounding,surf,ship

The 24H precipitation

With airline observ-ati

on

Without

Difference Obs.

The 3km cloud at 2005082012UTC . The below pictures are thecomparing the calculated rain content and the reflection of radar

The 5km cloud at 2005082012UTC . The below pictures are thecomparing the calculated rain content and the reflection of radar

The nudging of analysis cloud has effect on 0-1h precipitation forecast

With nudging cloudWithout

Difference Obs.

The nudging of calculated cloud has effect on 1-2h precipitation forecast

Difference

With nudging cloudWithout

Obs.

The case of Real time Running

Red － CYCLE;Green － operation ； Black － observation

cycle obs

3day 2day 1day

Summary 　

In the CHAF system, the cycle did not arouse additional error evidently.

The analysis and forecast can be improved by use of high frequent observation data.

The CHAF system would have a good future in application to nowcasting.

But More research must be done to improve the cloud

analysis,3DVAR, cycle system flow, etc. Farther, a long time running must be performed t

o inspect the CHAF system.

The end,thank you !