scholarly journals A New Scheme for Improving the Seasonal Prediction of Summer Precipitation Anomalies

2009 ◽  
Vol 24 (2) ◽  
pp. 548-554 ◽  
Author(s):  
Huijun Wang ◽  
Ke Fan
Keyword(s):  
Summer Precipitation ◽  
Seasonal Prediction ◽  
Western Pacific ◽  
Prediction Skill ◽  
Skill Levels ◽  
Pattern Correlation ◽  
Model Predictions ◽  
Original Scheme ◽  
Precipitation Anomalies ◽  
The Western Pacific

Abstract A new scheme is developed to improve the seasonal prediction of summer precipitation in the East Asian and western Pacific region. The scheme is applied to the Development of a European Multimodel Ensemble System for Seasonal to Interannual Prediction (DEMETER) results. The new scheme is designed to consider both model predictions and observed spatial patterns of historical “analog years.” In this paper, the anomaly pattern correlation coefficient (ACC) between the prediction and the observation, as well as the root-mean-square error, is used to measure the prediction skill. For the prediction of summer precipitation in East Asia and the western Pacific (0°–40°N, 80°–130°E), the prediction skill for the six model ensemble hindcasts for the years of 1979–2001 was increased to 0.22 by using the new scheme from 0.12 for the original scheme. All models were initiated in May and were composed of nine member predictions, and all showed improvement when applying the new scheme. The skill levels of the predictions for the six models increased from 0.08, 0.08, 0.01, 0.14, −0.07, and 0.07 for the original scheme to 0.11, 0.14, 0.10, 0.22, 0.04, and 0.13, respectively, for the new scheme.

scholarly journals CP El Niño and PDO Variability Affect Summer Precipitation over East China

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Wan-Jiao Song ◽  
Qi-Guang Wang
Keyword(s):  
El Niño ◽  
El Nino ◽  
Summer Precipitation ◽  
Western Pacific Subtropical High ◽  
Western Pacific ◽  
Subtropical High ◽  
East China ◽  
Central Pacific ◽  
Cp El Niño ◽  
Precipitation Anomalies

The summer precipitation produced by the East Asian summer monsoon (EASM) is significantly affecting agriculture and socioeconomics. Based on the Precipitation Reconstruction dataset in East China from 1950 to 2017, we investigate the spatiotemporal variations of summer precipitation, influencing environmental factors and their relation with the EASM and the Pacific Decadal Oscillation (PDO) in both central Pacific (CP) El Niño developing and decaying years. Results indicate the following: (1) The evolutions of CP El Niño events modulate the summer precipitation anomalies in East China. In the cool PDO phase, CP El Niño causes enhanced precipitation anomalies in the decaying years but less precipitation anomalies in the developing years, and vice versa for the warm PDO phase. (2) Atmospheric circulation anomalies drive the moisture transportation and combine the motion of western Pacific subtropical high resulting in the variation of precipitation patterns. Anomalous cyclone over the western North Pacific and the sustained Western Pacific Subtropical High (WPSH) are favorable for the increment of summer precipitation. (3) The different CP El Niño-EASM relationship is caused by the influences of PDO on the evolution of CP El Niño. CP El Niño develops slowly (decays rapidly) and is associated with rapidly developing (slowly decaying) anomalous warming in the north Indian Ocean during the developing (decaying) years.

Relationship between prediction skill of surface winds in average of weeks 1 to 4 and interannual variability over the Western Pacific and Indian Ocean

2021 ◽  
Author(s):  
Ravi P. Shukla ◽  
J. L. Kinter
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Lead Time ◽  
Temporal Correlation ◽  
Western Pacific ◽  
Prediction Skill ◽  
Forecast System ◽  
Climate Forecast System ◽  
Region Model ◽  
The Western Pacific

AbstractThis study examines the possible relationship between predictions of weekly and biweekly averages of 10m winds at 3 weeks lead-time and interannual variability over Western Pacific and Indian Ocean (WP-IO) using Climate Forecast System version 2 (CFSv2) reforecasts for period 1979-2008. There is large temporal correlation between forecasts and reanalyses for zonal, meridional and total wind magnitudes at 10m over most of WP-IO for average of weeks 1 and 2 (W1 and W2) in reforecasts initialized in January (JIR) and May (MIR). The model has some correlations that exceed 95% confidence in some portions of WP-IO in week 3 (W3) but no skill in week 4 (W4) over most of the region. Model depicts prediction skill in 14-day average of weeks 3-4 (W3-4) over portions of WP-IO, similar to level of skill in W3. The amplitude of interannual variability (IAV) for 10m-winds in W1 of JIR and MIR is close to that in reanalyses. As lead-time increases, amplitude of IAV of 10m-winds gradually decreases over WP-IO in reforecasts; in contrast to behavior in reanalyses. The amplitude of IAV of predicted 10m-winds in W3-4 over WP-IO is equivalent to that in W3 and W4 in reforecasts. In contrast, the amplitude of IAV in W3-4 in January and May of reanalysis is much smaller than IAV of W3 and W4. Therefore, one of the possible causes for prediction skill in W3-4 over sub-regions of WP-IO is due to reduction of IAV bias in W3-4 in comparison to IAV bias in W3 and W4.

scholarly journals Improving the Northeast Asian Monsoon Simulation: Remote Impact of Tropical Heating Bias Correction

2009 ◽  
Vol 137 (2) ◽  
pp. 797-803 ◽  
Author(s):  
Kyong-Hee An ◽  
Chi-Yung Tam ◽  
Chung-Kyu Park
Keyword(s):  
General Circulation ◽  
Diabatic Heating ◽  
Asian Monsoon ◽  
Circulation Model ◽  
Seasonal Prediction ◽  
Western Pacific ◽  
Boreal Summer ◽  
Simple Method ◽  
Northeast Asian ◽  
The Western Pacific

Abstract This study investigates the role of model tropical diabatic heating error on the boreal summer northeast Asian monsoon (NEAM) simulation given by a general circulation model (GCM). A numerical experiment is carried out in which the GCM diabatic heating is adjusted toward more realistic values in the tropics. It is found that the seasonal mean NEAM circulation and rainfall are improved in the GCM. This can be attributed to the reduced positive heating bias in the western Pacific Ocean around 10°–15°N in the model, which in turn leads to better-simulated low-level southerly winds over eastern Asia and more moisture supply to the NEAM region. The GCM’s ability in capturing the year-to-year variation of NEAM rainfall is also markedly improved in the experiment. These results show that the diabatic heating error over the western Pacific can be one reason for poor NEAM simulations in GCMs. The authors also suggest a simple method to reduce model heating biases that can be readily applied to dynamical seasonal prediction systems.

Typhoon Havens Handbook for the Western Pacific and Indian Oceans. Change 3

1993 ◽  
Author(s):  
Dennis C. Perryman ◽  
Richard E. Gilmore ◽  
Ronald E. Englebretson
Keyword(s):  
Western Pacific ◽  
The Western Pacific
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