Heavy Rainfall and Southwesterly Flow after the Leaving of Typhoon Mindulle (2004) from Taiwan

Chien, Fang Ching; Liu, Yi Chin; Lee, Cheng-Shang

doi:10.2151/jmsj.86.17

Cited by 48 publications

(40 citation statements)

References 20 publications

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“…The occurrence of consistent model rainfall predictions is, of course, not mere coincidence, but rather a consequence of the "terrain-locking" mechanism as mentioned in the introduction. Predictability of the accumulated rainfall associated with typhoons impinging Taiwan at different directions was also shown by Lin et al (2002), Wu et al (2002Wu et al ( , 2009), Chiao and Lin (2003), Huang et al (2005) and Yang et al (2008) using MM5, and by Chien et al (2008) and using WRF. These successful rainfall predictions benefited essentially from the presence of the high CMR in Taiwan that provides the orographic uplift of typhoon flow to produce intense rainfall.…”

Section: Rainfall Predictionmentioning

confidence: 85%

Extreme Rainfall Mechanisms Exhibited by Typhoon Morakot (2009)

Huang¹,

Wong²,

Yeh³

2011

Terr. Atmos. Ocean. Sci.

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Moderate Typhoon Morakot (2009) became the most catastrophic typhoon in Taiwan on record. The MM5 numerical experiments with and without bogus data assimilation (BDA) were used to investigate the extreme rainfall mechanisms in Taiwan associated with the westbound typhoon. The BDA, based on 4DVAR, helps MM5 to maintain a more consolidated typhoon vortex and better predict the observed track after landfall, thus producing realistic extreme rainfall (about 2400 mm) at the southern and Central Mountain Range (CMR) of Taiwan. Severe rainfall in Taiwan is dominated by the CMR that hence modulates rainfall predictability.Model analyses indicate that the synoptic environment provides low-level preconditioning with large convective available energy (CAPE) in the southwest monsoon conveying belt in conjunction with the cyclonic Morakot. When Morakot passed slowly over north Taiwan, the developing Tropical Storm Goni, originating west of Hong Kong, facilitated the moist southwesterly flow to converge with the northerly cyclonic flow of Morakot. These processes contributed to enhanced rainfall in south Taiwan. In an experiment whereby the Goni vortex was initially deactivated by BDA, the southwesterly prevailing flow, southwest of Taiwan, weakened considerably and shifted southward at a later time, resulting in one-third reduction in total accumulated rainfall in south Taiwan. Conversely, total accumulated rainfall in Taiwan is greatly reduced when the initial Morakot vortex is deactivated. Removal of Taiwan topography results in a significant reduction in total accumulated rainfall by more than 50%, due to lack of orographic lift by the CMR.

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Section: Rainfall Predictionmentioning

confidence: 85%

Extreme Rainfall Mechanisms Exhibited by Typhoon Morakot (2009)

Huang¹,

Wong²,

Yeh³

2011

Terr. Atmos. Ocean. Sci.

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“…1a) with an average terrain height of about 2000 m (Chen and Li, 1995;Lin and Chen, 2002) and a few steep peaks of almost 4 km. It is well known that damages are strongly related to the location of the typhoon's landfall and interactions between its circulation and the CMR (Brand and Blelloch 1974;Wu and Kurihara, 1996;Wu and Kuo, 1999;Lin et al, 2001;Chien et al, 2008;Ge et al, 2010). Previous studies pointed out that enormous amounts of rainfall occur and are enhanced due to mountain lifting when a typhoon passes over the CMR (Wu and Kuo, 1999;Lin et al, 2001Wu et al, 2002;Yang et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies pointed out that enormous amounts of rainfall occur and are enhanced due to mountain lifting when a typhoon passes over the CMR (Wu and Kuo, 1999;Lin et al, 2001Wu et al, 2002;Yang et al, 2008). Moreover, it is common that the strong southwesterly flow follows the departure of an invading typhoon and brings heavy rainfall over central or Southern Taiwan Chien et al, 2008). Sometimes, such rainfall associated with the southwesterly flow can be significantly heavier than the rainfall brought by the typhoon itself .…”

Section: Introductionmentioning

confidence: 99%

Mesoscale processes for super heavy rainfall of Typhoon Morakot (2009) over Southern Taiwan

et al. 2011

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Abstract.Within 100 h, a record-breaking rainfall, 2855 mm, was brought to Taiwan by typhoon Morakot in August 2009 resulting in devastating landslides and casualties. Analyses and simulations show that under favorable largescale situations, this unprecedented precipitation was caused first by the convergence of the southerly component of the pre-existing strong southwesterly monsoonal flow and the northerly component of the typhoon circulation. Then the westerly component of southwesterly flow pushed the highly moist air (mean specific humidity >16 g/kg between 950 and 700 hPa from NCEP GFS data set) eastward against the Central Mountain Range, and forced it to lift in the preferred area. From the fine-scale numerical simulation, not only did the convergence itself provide the source of the heavy rainfall when it interacted with the topography, but also convective cells existed within the typhoon's main rainband. The convective cells were in the form of small rainbands perpendicular to the main one, and propagated as wave trains downwind. As the main rainband moved northward and reached the southern CMR, convective cells inside the narrow convergence zone to the south and those to the north as wave trains, both rained heavily as they were lifted by the west-facing mountain slopes. Those mesoscale processes were responsible for the unprecedented heavy rainfall total that accompanied this typhoon.

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“…1b, c, for example). As documented in previous studies (Lin et al 2001;Chen et al 2006;Chien et al 2006Chien et al , 2008, this upstream flow is often associated with organized mesoscale convective systems (MCS) forming over the strait, propagating eastward, and producing heavy rain over the sloping mountainous area. In this study, we perform data assimilation experiments to assess the ability of a mesoscale model to predict these precipitating systems.…”

Section: Introductionmentioning

confidence: 61%

Impact of FORMOSAT-3/COSMIC GPS radio occultation and dropwindsonde data on regional model predictions during the 2007 Mei-yu season

Chien

Kuo

2009

GPS Solut

Self Cite

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A study of the impact of FORMOSAT-3/ COSMIC GPS radio occultation (RO) and dropwindsonde data on regional model simulations for a 11-day period during the 2007 Mei-yu season is presented. The Weather Research and Forecasting (WRF) model and its threedimensional variation component, WRF-Var, are used for regional model predictions of heavy rainfall events in Taiwan. Without the use of GPS RO and dropwindsonde data, pressure and relative humidity are, in general, underestimated by the model; temperature predictions have a warm bias at the low level and a cold bias at the high level; and the east-west and north-south component winds have positive and negative biases, respectively. Incorporating GPS RO data tends to improve the prediction for longer integration. The assimilation of dropwindsonde data improves the forecast at the earlier time and at higher levels, and the improvement decreases over time. The reason the dropwindsonde data produce a positive impact earlier and the GPS RO data later is that there are few GPS RO observations in the fine domain. The large-scale simulation is first improved using the GPS RO observations, and the resulting changes can have a positive impact on the mesoscale at the later time. The dropwindsonde observations were taken inside the fine domain such that their impact can be detected early in the simulation. With both types of observation included, the prediction shows even greater improvement.

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Heavy Rainfall and Southwesterly Flow after the Leaving of Typhoon Mindulle (2004) from Taiwan

Cited by 48 publications

References 20 publications

Extreme Rainfall Mechanisms Exhibited by Typhoon Morakot (2009)

Extreme Rainfall Mechanisms Exhibited by Typhoon Morakot (2009)

Mesoscale processes for super heavy rainfall of Typhoon Morakot (2009) over Southern Taiwan

Impact of FORMOSAT-3/COSMIC GPS radio occultation and dropwindsonde data on regional model predictions during the 2007 Mei-yu season

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