Seasonal Outlook over China in Summer 2020 Liu, u, Yunyun yun - - PowerPoint PPT Presentation

Seasonal Outlook over China in Summer 2020

Liu, u, Yunyun yun Wang, g, Yongg gguang uang Contact act: : liuyuny@c yuny@cma.gov.cn ma.gov.cn Bei eijing jing Climate mate Cen enter, er, CMA 07May, ay, 2020 20

Sixteenth Session of the Forum on Regional Climate Monitoring Assessment and Prediction for Asia (FOCRAII)

• 1. Observed anomalous signals and

possible impacts

• 2. Predictions by BCC_CSM1.1(m)
• 3. Summary

Outline

IOBM Niño3.4 SSTA in DJF 2019/2020 ATL Niño

Observed anomalous signals

• Positive SSTAs were

present in the central- eastern tropical Pacific, tropical Indian, and Atlantic Oceans in DJF.

• A weak CP type El

Niño event was formed from Oct 2019 to Apr 2020.

For the future evolution of Niño3.4 index, a majority of models favored decaying trend of Niño3.4 from DJF to JJA, and ENSO-neutral conditions through summer 2020.

Pacific Niño3.4 SST Model Outlook

Possible impacts of El Niño decaying years

In El Niño decaying years, North and Northwest China favor wet conditions, while South China and the lower reach of Yangtze River valley favor dry conditions.

Tropical Indian Ocean warming

In the tropical Indian Ocean, basin-wide warming is expected to persist through summer 2020. Statistically, the basin-wide warming in the tropical Indian Ocean occurs as a lagged response to the Pacific El Niño event, which is favorable to the stronger Philippine sea anticyclone and WPSH.

A

Atlantic Ocean warming in DJF

• The ATL Niño index was significantly positive in

DJF, forming an Atlantic Niño event.

• Usually, the Atlantic Niño leads Pacific La Niña

event by 6~12 months (Kucharski et al., 2016).

• The equatorial Atlantic ocean warming in winter is

beneficial to further northward WPSH, and above normal rainfall over North China in summer.

A

• 2. Predictions by BCC_CSM1.1(m)

BCC_CSM1.1(m) predicted Z500 anomaly

• Positive

height anomalies are favored

• ver

Northeast Asia and the western North Pacific, and a near-normal height anomalies are favored over South China and east of Japan in JJA.

• WPSH favors stronger and southward in June, and

further northward in July-August.

Jun un. Jul. Aug Z500_JJA JA IC: Apr 2020 2020

uv850 IC: Apr2020 C A

BCC_CSM1.1(m) predicted uv850 anomalies

Anomalous Philippine anticyclone Southerly anomalies

• ver the southeastern

coast of China

Forecasts for monsoon circulation factors

WPSH Intensity East Asian Summer Monsoon Philippine Sea Anticyclone East Asia-Pacific teleconnection

• Wet regions are expected over the northern South China, North China, Mongolia, South Japan,

South Korea, North India, and Southeast Asia.

• Dry regions are expected over the Indo-China Peninsula, South India, and Central Asia.

Predict diction skill Prec ecipitati itation IC: Apr2020 20

BCC_CSM1.1(m) predicted Precipitation anomaly

• Predict

diction skill

BCC_CSM1.1(m) predicted T2m anomaly

• The predicted temperature is above normal over most of Asia, and near normal over South China,

North India, and part of northeastern Asia.

• Besides, the prediction skills of temperature over Asia is higher than that of rainfall in summer.

T2m IC: Apr2020

Averaged-tempe mperat ature ure in China na

Long-term trend of T2m over China

Probabil bability ty of abov

• ve-nor
• rmal

al T2m in 2011-2018 2018

• Under the background of global warming, the T2m over China is increasingly warming over the

last 30 years.

Seasonal outlook in JJA 2020

A: above normal B: below normal N: near normal

The seasonal outlooks combine the model forecasts, the long-term trends, and effects of tropical oceans warming.

• Wet regions are expected over South China, North and Northwest China, while dry regions are

favored over the eastern Inner Mongolia, northern Xinjiang, and along the Yangtze River valley.

• The above normal temperature is favored over most China, except for the Tibetan Plateau and part
• f South China.

• The WPSH is favored stronger than normal in JJA, with southward in June,

and further northward in July-August.

• The intensity of EASM is expected near-normal, which is favorable to abundant

rainfall north of Yangtze River valley in China.

• The above normal rainfall is favored over South China, North and Northwest

China, where it is necessary to prevent the flood and rainstorm disasters.

• The above-normal temperature is expected over most of China, except for the

Tibetan Plateau and part of South China.

• Average to above average tropical cyclone activity is favored in the western

North Pacific over 2020, with 26-28 TCs genesis and 7-9 TCs landfall onto the southeastern coast of China. The intensity of landing TCs are expected stronger than normal and the moving tracks may be further northwestward.

Summary

More Information

17

BCC Webpage: http://forecast.bcccsm.ncc-cma.net/htm/

• Dr. Yunyun Liu

Beijing Climate Center China Meteorological Administration 46# Zhongguancun South Avenue, Beijing Email: liuyuny@cma.gov.cn

Model: The fully coupled climate model BCC_CSM1.1m (T106L26) Forecast：initialized on 1st of each month , 13-month integration Ensemble forecast：24 samples (15 lagged-average-forecast (LAF) and 9 singular-vector (SV) method) Initial data: Atmosphere: NCEP reanalyses for hindcast, and NMC/CMA T639 assimilation for real-time Ocean: NCEP-GODAS oceanic data Hindcast period：1991-2013 Data preprocess：0-month lead (LM0) ；1-month lead (LM1); …; 6-month lead (LM6) Real-forecast for 2019: initialized on 1st April

Re-forecast configurations for seasonal prediction