Precipitation forecast of MM5 in the Taiwan area during the 1998 Mei-yu season

Fang Ching Chien, Ying Hwa Kuo, Ming Jen Yang

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

This study presents precipitation verification, in the Taiwan area, for a real-time Pennsylvania State University-National Center for Atmospheric Research Fifth-Generation Mesoscale Model (MM5) system during the 1998 Mei-yu season. The highest equitable threat score (ETS) of precipitation forecasts, verified against observed precipitation, was about 0.2 at the 2.5-mm threshold for this nearly 2-month period. The complex and steep terrain in this region presented great challenges to the 15-km model in predicting realistic rainfall because the precipitation was driven by local forcings such as thermal effects and orographic lifting. In addition, the lack of observational data over the surrounding ocean greatly limited the quality of the model's initial data. It was found that the model system more accurately simulated nighttime rainfall than daytime precipitation. This was caused by the model underforecasting the rainfall events that resulted from solar heating and orographic lifting over the mountain slopes during the daytime hours. Precipitation, however, was overforecast over the high mountain regions (> 1200 m). Further, the analysis of ETS with regard to the terrain height indicated that the model performed better over the lowlands than over the mountainous areas (slopes and highlands). It was discovered that the ETSs were much higher for precipitation forecasts after the onset of the east Asia summer monsoon than prior to the onset. Overall, the model more accurately predicted precipitation for the rainfall events associated with the Mei-yu front and the accompanying mesoscale convective systems than it predicted precipitation associated with the local forcings.

Original languageEnglish
Pages (from-to)739-754
Number of pages16
JournalWeather and Forecasting
Volume17
Issue number4
DOIs
Publication statusPublished - 2002 Jan 1

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rainfall
convective system
mountain region
forecast
temperature effect
monsoon
mountain
ocean
summer
solar heating
mountainous area
analysis
high mountain
Asia

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Precipitation forecast of MM5 in the Taiwan area during the 1998 Mei-yu season. / Chien, Fang Ching; Kuo, Ying Hwa; Yang, Ming Jen.

In: Weather and Forecasting, Vol. 17, No. 4, 01.01.2002, p. 739-754.

Research output: Contribution to journalArticle

Chien, Fang Ching ; Kuo, Ying Hwa ; Yang, Ming Jen. / Precipitation forecast of MM5 in the Taiwan area during the 1998 Mei-yu season. In: Weather and Forecasting. 2002 ; Vol. 17, No. 4. pp. 739-754.
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