中央氣象局全球預報系統積雲參數法之改進與其對於2011年DYNAMO實驗期間MJO對流之模擬評估

Improvement of cumulus parameterization in the CWB global model and evaluations of simulated MJO convection during 2011 DYNAMO campaign

林昌鴻(Chang-Hung Lin) ； 楊明仁(Ming-Jen Yang) ； 陳建河(Jen-Ho Chen)

《大氣科學》 46卷4期 (2018/12) Pp. 406-426

https://doi.org/10.3966/025400022018124604003

摘要

本研究使用中央氣象局全球預報模式（CWB／GFS），並針對Dynamics of the Madden-Julian Oscillation（DYNAMO）實驗期間（2011年10月至2012年3月）的其中3個Madden-Julian Oscillation MJO對流事件（10月至12月），進行模擬測試。我們透過水氣收支分析，以及參考Adames（2017）的方法以分析GFS模式中的MJO水氣場與TRMM（Tropical Rainfall Measuring Mission）衛星觀測降水資料之間的相關性，藉以瞭解Tiedtke積雲參數化方案和modified new Tiedtke參數化方案對於MJO水氣、降水和結構的掌握程度。研究發現，Tiedtke積雲參數化方案與modified new Tiedtke方案所模擬的MJO對流系統，於印度洋生成後，具有對流發展過強並且強降水發生後迅速減弱的特徵，使得對流系統無法維持並橫越海洋性大陸與西太平洋地區。另外，這兩種參數化方案的模擬皆產生範圍過窄且過於旺盛的上衝氣流，兩者的MJO對流系統組織性較弱，其對流結構較為鬆散的特徵。然而modified new Tiedtke方案可以較合理地掌握時間和空間平均的MJO水氣場分佈，進而修正Tiedtke參數化方案於東印度洋至西太平洋暖池範圍內MJO模擬降水過多的偏差情形。

關鍵字

Madden-Julian Oscillation（MJO） ； Tiedtke積雲參數化方案 ； 水氣收支

並列摘要

This study investigates the simulation results of three Madden-Julian Oscillation (MJO) events during the Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign in 2011, using the Central Weather Bureau (CWB) global forecast system (GFS) with different cumulus parameterizations. In order to estimate the simulated water vaper, precipitation and convective structure in the Tiedtke and modified new Tiedtke scheme, we have performed moisture budget analysis. We also followed the methodology developed in Adames (2017) to examine the relationship between the simulated water vaper and the Tropical Rainfall Measuring Mission (TRMM) satellite precipitation data. For the simulations, both the Tiedtke and modified new Tiedtke schemes show that after the MJO convection is triggered, the updrafts by deep convection are too strong and decrease rapidly after the convective systems produce precipitation, thus the simulated MJO systems cannot propagate across the Maritime Continent. In addition, both cumulus schemes predict the convection too strong with narrow updraft width, and the simulated MJO systems do not organize very well. The simulated convection is generated more randomly, compared to the observations. Nevertheless, the modified new Tiedtke scheme can reasonably capture the space- and time-averages of simulated water vapor field over the tropical warm-pool region and reduce the overprediction bias of rainfall in the original Tiedtke scheme.

並列關鍵字

Madden-Julian Oscillation (MJO) ； Tiedtke convective parameterization ； moisture budget