Effects of Terrain on the Surface Structure of Typhoons over Taiwan

Chang, C. P.; Yeh, Tien-Chiang; Chen, J. M.

doi:10.1175/1520-0493(1993)121<0734:eotots>2.0.co;2

Cited by 73 publications

(74 citation statements)

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“…Due to the lifting of typhoon flow over the Central Mountain Range (CMR), Wang (1992) and Chang et al (1993) concluded that the hourly rainfall distributions over the Taiwan area is displayed as a function of the typhooncenter location. Lee et al (2006) developed the TRCM to forecast typhoon rainfall.…”

Section: Methodsmentioning

confidence: 99%

Improvement of Statistical Typhoon Rainfall Forecasting with ANN-Based Southwest Monsoon Enhancement

Pan¹,

Yang²,

Kuo³

et al. 2011

Terr. Atmos. Ocean. Sci.

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Typhoon Morakot 2009, with significant southwest monsoon flow, produced a record-breaking rainfall of 2361 mm in 48 hours. This study hopes to improve a statistical typhoon rainfall forecasting method used over the mountain region of Taiwan via an artificial neural network based southwest monsoon enhancement (ANNSME) model. Rainfall data collected at two mountain weather stations, ALiShan and YuShan, are analyzed to establish the relation to the southwest monsoon moisture flux which is calculated at a designated sea area southwest of Taiwan. The results show that the moisture flux, with southwest monsoon flow, transported water vapor during the landfall periods of Typhoons Mindulle, Bilis, Fungwong, Kalmaegi, Haitaing and Morakot. Based on the moisture flux, a linear regression is used to identify an effective value of moisture flux as the threshold flux which can enhance mountain rainfall in southwestern Taiwan. In particular, a feedforward neural network (FNN) is applied to estimate the residuals from the linear model to the differences between simulated rainfalls by a typhoon rainfall climatology model (TRCM) and observations. Consequently, the ANNSME model integrates the effective moisture flux, linear rainfall model and the FNN for residuals. Even with very limited training cases, our results indicate that the ANNSME model is robust and suitable for improvement of TRCM rainfall prediction. The improved prediction of the total rainfall and of the multiple rainfall peaks is important for emergency operation.

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Section: Methodsmentioning

confidence: 99%

Improvement of Statistical Typhoon Rainfall Forecasting with ANN-Based Southwest Monsoon Enhancement

Pan¹,

Yang²,

Kuo³

et al. 2011

Terr. Atmos. Ocean. Sci.

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show abstract

“…The other reason is that the wind field was scarcely affected by the high terrain of the island of Taiwan since the storm center stayed more than 200 km away from the island, and its 7 Beaufort scale radius was too small to reach the island. Previous studies showed that the high terrain of the island has a significant influence on the low wind field and pressure field of a typhoon passing by it [Chang et al, 1993], which results in some unexpected variations in storm surges and contaminates the oscillations with near-tidal period. In this case, the uncertainty of atmospheric forcing due to the terrain of the island was avoided to the utmost because of the unique storm path.…”

Section: Observationsmentioning

confidence: 99%

Tide‐surge Interaction Intensified by the Taiwan Strait

et al. 2010

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[1] The Taiwan Strait is a long and wide shelf-channel where the hydrodynamics is extremely complex, being characterized by strong tides, and where storm surges frequently occur during the typhoon season. Obvious oscillations due to tide-surge interaction were observed by tide gauges along the northern Fujian coast, the west bank of the Taiwan Strait, during Typhoon Dan (1999). Numerical experiments indicate that nonlinear bottom friction (described by the quadratic formula) is a major factor to predict these oscillations while the nonlinear advective terms and the shallow water effect have little contribution. It is found that the tide-surge interaction in the northern portion of the Taiwan Strait is intensified by the strait. Simulations based on simplified topographies with and without the island of Taiwan show that, in the presence of the island, the channel effect strengthens tidal currents and tends to align the major axes of tidal ellipses along the channel direction. Storm-induced currents are also strengthened by the channel. The pattern of strong tidal currents and storminduced currents along the channel direction enhances tide-surge interaction via the nonlinear bottom friction, resulting in the obvious oscillations along the northern Fujian coast.

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“…4, see also Chang et al, 1993). It can be seen that heavy rainfall occurred at the east coast of Taiwan when TCs were located at the south (120 …”

mentioning

confidence: 96%

Characteristics of rainfall during tropical cyclone periods in Taiwan

Cheung

Huang

Lee

2008

Nat. Hazards Earth Syst. Sci.

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Abstract. Due to the Central Mountain Range with an elevation up to about 4 km, the amount and distribution of rainfall in Taiwan associated with typhoons or tropical cyclones (TCs) depends not only on the distribution of convection within the TCs (internal structure) and influences from monsoon-scale environmental flow, but also on the orographic effect. This study analyzes the spatial and temporal characteristics of rainfall associated with 62 TC cases that affected Taiwan by using observations from the 371 automatic rain stations available in the period 1989-2002. It is found from the climatology maps that highly different rainfall distributions occurred for TCs that approached the Taiwan area from different directions. By performing objective clustering analysis of the rainfall time series of all the rain gauges, several characteristic temporal rainfall profiles are obtained. The geographic distribution of rain gauges that possess a particular temporal profile is also consistent with the possible TC track types that bring maximum rain to the Taiwan area at different times.Based on data in the 1989-2002 period, the development of a TC rainfall climatology-persistence (CLIPER) model is described. CLIPER is an optimized combination of climatology and persistence with different relative weighting for different forecast periods. Independent cases (other than the model development database) during 2003-2004 are used to validate the model. Objective measures like equitable threat score and bias score show that CLIPER's skill is acceptable for practical applications for 24-h rain threshold below 100 mm. However, the underestimation bias for more heavy rainfall is serious and CLIPER seems to have better performance for the northwestern Taiwan than for the other locations. Future directions for improvement of the CLIPER model are discussed.

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Effects of Terrain on the Surface Structure of Typhoons over Taiwan

Cited by 73 publications

References 0 publications

Improvement of Statistical Typhoon Rainfall Forecasting with ANN-Based Southwest Monsoon Enhancement

Improvement of Statistical Typhoon Rainfall Forecasting with ANN-Based Southwest Monsoon Enhancement

Tide‐surge Interaction Intensified by the Taiwan Strait

Characteristics of rainfall during tropical cyclone periods in Taiwan

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