Climate prediction

Ding Yihui, Liu Yanju, Liu Yiming, Shi Xueli

National Climate Center, CMA

1. 9-yr seasonal prediction for flooding period

NCC-CGCM

1998 summer, heavy floods occurred in whole Yangtze basins, predictions for range and intensity are quite successful

Seasonal precipitation prediction (left) and observation (right) for 1998 summer (Anomaly percentage:%)

1999 年夏季，预报为中等旱涝年景，多雨范围比前一年小 ，少雨范围比前一年大，与实况一致。但预报主要雨带偏北 ，位于江淮、黄淮、华北中南部到东北东部一带；实况是主要雨带偏南，位于长江以南地区；出入较大。

1999 年夏季（ 6 ～ 8 月）降水量距平百分率图1999 年夏季（ 6 ～ 8 月）降水量距平百分率预报图

Seasonal precipitation prediction (left) and observation (right) for 1999 summer (Anomaly percentage:%)

2000 summer, predictions are right for flood over Huanghe and Huaihe valleys and drought over some regions in North of China,The prediction evaluation highly reached 76%, with 11% increase

compared to which in “9th 5-yr plan” and being the third since 1978.

Seasonal precipitation prediction (left) and observation (right) for 2000 summer (Anomaly percentage:%)

2001 summer, the prediction is consistent to observation, there are flood overEast of Huanghe and Huaihe valleys, lower of Yangtze basin, most regions in South of China, east of Southwest China, northwest of Sinkiang, with drought over most regions in North China and Yangtze basins. But raininess belts in prediction is weaker than observation in South of China and stronger in north of China.

Seasonal precipitation prediction (left) and observation (right) for 2001 summer (Anomaly percentage:%)

2002 年夏季（ 6 ～ 8 月）降水量距平百分率图2002 年夏季（ 6 ～ 8 月）降水量距平百分率预报图

预报 2002 年夏季，我国多雨的范围比前一年增大，江淮、长江中下游、江南东部、华南大部、云贵高原南部等地降水偏多，部分地区洪涝灾害比前一年加重。北方大部地区以少雨为主，华北、西北东部和东北的部分地区要多年连续干旱。上述预报意见基本正确。但部分地区预报与实况有出入。

Seasonal precipitation prediction (left) and observation (right) for 2002 summer (Anomaly percentage:%)

预报总体上正确：北方降水比前四年增多，可能出现南北两支多雨带。江淮地区少雨，有夏旱（高温少雨）。长江流域不会出现严重洪涝。登陆台风个数偏少。但淮河流域突发性暴雨未报出。

Seasonal precipitation prediction (left) and observation (right) for 2003 summer (Anomaly percentage:%)

2004

Prediction OBS

2005

Prediction OBS

2006

Prediction OBS

2. Regional climate model to predict flooding seasons

Land-surface 1. BATS 2. LPMLPM

Cumulus 1. Kuo－ Anthes 3. MFS

Convective 2. Grell 4. Betts－Miller

Rad. Trans. 1. CCM2 2. CCM3

1. Non-Holtslag 3-6. TKE 2. Holtslag (various formula)

Physical Process Parameterization ScPhysical Process Parameterization Schemes of RegCM_NCChemes of RegCM_NCC

PBL

Model Domain of operational Model Domain of operational hindcasts & predictionshindcasts & predictions

Precipitation Anomaly over 160 station (upper) and North China (below) in summer 1991-2000 simulation

-1

-0. 5

0

0. 5

1

1. 5

1 2 3 4 5 6 7 8 9 10

si m obs

Preci pi tati on Anomal y of North Chi na- 1. 5

- 1

- 0. 5

0

0. 5

1

1. 5

1 2 3 4 5 6 7 8 9 10

si m obs

ACC distribution of summer precipitationACC distribution of summer precipitation

SimulationSimulation HindcastHindcast

Assessment of RegCM_NCC hindcast (1)

year Pc SS1 SS2 ACC Ts

1991 61.50 0.02 0.17 0.00 0.14

1992 63.49 -0.02 0.14 0.05 0.14

1993 66.49 0.07 0.21 -0.02 0.18

1994 63.69 0.04 0.19 0.04 0.15

1995 62.90 -0.02 0.14 -0.07 0.13

1996 56.42 -0.12 0.05 0.00 0.11

1997 72.54 0.22 0.34 0.19 0.26

1998 56.04 -0.11 0.06 -0.05 0.13

1999 58.79 -0.12 0.05 0.04 0.14

2000 74.87 0.29 0.40 0.33 0.20

ave 63.67 0.025 0.175 0.051 0.158

Ave in NCC

67.9 -0.03 0.08 0.02 0.08

Precipitation Anomaly of summer 2002 (%)

Prediction OBS

Above normal: the mid-low reach of the Yangtze River

valley, most part of the South china;

Below normal: most regions to the north of the Yangtze

River valley

Precipitation Anomaly of summer 2003 (%)

Above normal: regions between the Yellow river and Huaihe river valley;

Below normal:Regions to the south of the Yangtze river valley, and Inner-Mongolia

Prediction in March Observation

Prediction in May

Precipitation Anomaly of summer 2004 (%)

新疆西北部、河套地区、华北大部、东北西部以及华南部分地区降水较常年同期偏少；西南地区大部、黄淮、江淮、江南部分地区降水较常年同期偏多，其余地区接近常年同期。

Precipitation Anomaly of summer 2006 (%)

3. Monsoon onset simulation by using high-resolution regional

climate model

4. Prediction of South China Sea summer monsoon

onset with POAMA

POAMA

• Newest operational model: 9 months

• AGCM: BAM, T47,17 layers

• OGCM: ACOM2（ Version 2） ,25 layers,

196*182 grids

U850

OLR

2003 OLR （ 110-120 ） NCEP

Forecast (right)Observation (left)

Ensemble forecast 16 members( April15 _30, 2003)

Precipitation

Ensemble forecast 16 members( April15 _30, 2003)

Observation (left) Forecast (right)

accepted

onset index:Wang.et.al(2004)

Actual onset date

（ 4th pentad of May）

accepted

（ 17/30=57%）

Actual onset date

（ 4th pentad of May）

(a)

(b)

850 hPa Zonal wind

2003

850 hPa Zonal wind

March

April

Taylor diagram

Taylor diagram summary of POAMA predictions for 2003. Diagrams on up (bottom) are for ensemble members with lead times of 61-31 (30-1) days. The number on each of the diagram signifies the starting date for the ensemble member and CLM the Climatological prediction

Cor=0.625

Rmse=4.6

(c)

(d)

OLR

OLR

March

April

2003

Taylor diagram

Cor=0.51

Rmse=36

(e)

(f)

precipitation

precipitation

Taylor diagram

2003

March

April Cor=0.73

Rmse=7

Case2 2004

Observation

（ a）

March

850 hPa Zonal wind

850 hPa Zonal wind （ b）

April

泰勒图的分析

2004

Taylor diagram

Cor=0.47

OLR

OLR

(a)

(b)

泰勒图的分析

2004

March

April

Taylor diagram

Cor=0.35

accepted

accepted

（ 18/30=60%）

Actual onset date

（ 4th pentad of May）

Actual onset date

（ 4th pentad of May）

U850

OLR

Observation (left) Forecast (right)

Ensemble forecast 16 members( April15 _30, 2004)