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Typhoon Morakot (2009) was one of the deadliest typhoons to impact Taiwan in the past 50 years. It brought catastrophic damage to Taiwan, leaving 673 people dead and 26 others missing. This slow-moving storm produced huge amounts of rainfall, peaking at 2,965 mm (116.73 in.) in 4 days (7-10 August 2009), and caused enormous mudslides and severe flooding throughout southern Taiwan. One massive mudslide devastated the entire Shiaolin village, killing approximately 500 people in this village alone. The estimated agricultural losses amounted to roughly NT$16.4 billion (about US$550 million). Morakot also caused widespread damage in China and the Philippines. Improving forecasting techniques and early warning systems for landfalling tropical cyclones (TCs) has thus become one of the most important tasks facing scientists and governmental agencies.
Since this extreme rainfall event, there have been extensive studies focusing on its record-breaking amount of rainfall from various scientific and forecast perspectives. Accordingly, a conference named "The International Workshop on Typhoon Morakot (2009)," summarized by C.-S. Lee and colleagues in a 2011 article, was held on 25-26 March 2010 in Taipei, Taiwan, during which various aspects of TCs were communicated and discussed. The conference specifically aimed to identify gaps in our understanding of TCs and to discuss advanced forecast guidance tools required to improve warnings of these extreme precipitation and flooding events. The community went a step further to propose a special issue to the journal Terrestrial, Atmospheric and Oceanic Sciences (TAO) in order to provide a comprehensive summary of Morakot and other extreme rainfall events associated with landfalling TCs. The special issue, "Typhoon Morakot (2009): Observation, Modeling, and Forecasting Applications," was published in December 2011 and covered observation analyses of circulations and structures, mesoscale model simulations, data assimilation techniques, and practical forecast verification and guidance.
Key findings and consensuses in this special issue are carried out from approaches of statistics, observations, and numerical simulations, and are summarized below.
1) Morakot's notable precipitation is highlighted by statistics on rainfall-return periods.
2) The extreme rainfall brought in by Morakot is associated with Taiwan's topography and the flow interactions of several multiscale weather features (monsoon gyre, moist winds, and a nearby typhoon).
3) While the forecast/simulated track errors are small, the deficiencies in the representation of the TC translation speed, the...