區域系集預報系統研究：物理參數化擾動

The Study of Regional Ensemble Forecast: Physical Perturbations

李志昕(Jhih-Sin Li) ； 洪景山(Jing-Shan Hong)

《大氣科學》 39卷2期 (2011/06) Pp. 95-115

摘要

系集預報系統設計的目的是要能涵蓋模式預報的不確定性。欲發展系集預報系統，須提供有效且合理的系集預報成員，以產生足夠的預報分歧。本研究利用WRF模式不同之積雲參數法、微物理參數法、邊界層參數法以及土壤模式等，產生40組以物理參數化擾動為主的系集成員進行數值模式預報實驗，並分析模式物理參數化擾動法是否能產生足夠的預報分歧，以建構有效的區域系集預報系統。
欲找出合適之系集預報成員，需發展統計校驗技術。進行系集預報系統效能之評估時，必須分兩個層面進行，第一部分是評估系集成員分歧是否足夠，據以最大程度涵蓋可能的發生機率；第二部分是評估系集預報系統的預報能力和可信度。研究結果顯示，使用模式物理參數化擾動法產生之40組系集成員預報離散程度不足，顯示此一方法尚不足以提供足夠分散之系集成員，且預報可信度尚不足，因此未來需針對其他系集成員產生方式進行實驗和評估分析，以期望找出最合適之系集預報成員組合方式。

關鍵字

系集預報系統 ； 離散

並列摘要

In order to represent the forecast uncertainties, the spread-enough ensemble products from a robust ensemble forecast system (EFS) became more and more important in the numerical weather prediction centers. The goal of this paper is to evaluate the forecast spread based on the physical perturbations from WRF model. One-month regional forecast experiment from 40 members was conducted in this paper, including the cumulus, microphysics, planetary boundary layer parameterization schemes, and land-surface models.
Verification techniques were applied to evaluate the ensemble spread qualitatively and quantitatively. The results show that there exist systematic bias in the ensemble system and therefore result in the not enough forecast spread from the physical perturbation based on WRF model. To further apply a bias correction and perturbed the ensembles from the other technique is under assessment to implement an effective EFS in Central Weather Bureau.

並列關鍵字

ensemble forecast system ； spread