Diagnostics for an Extreme Rain Event near Shanghai during the Landfall of Typhoon Fitow (2013)
| Autor: | Zhian Sun, Zifeng Yu, Hui Yu, Lawrence Rikus, Jianyong Liu, Xuwei Bao, Dan Wu, Mai C. N. Hankinson, Noel E. Davidson |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Monthly Weather Review. 143:3377-3405 |
| ISSN: | 1520-0493 0027-0644 |
| DOI: | 10.1175/mwr-d-14-00241.1 |
| Popis: | Typhoon Fitow made landfall south of Shanghai, China, on 6 October 2013. During the following two days, precipitation in excess of 300 mm day−1 occurred 400 km to the north of the typhoon center. The rain-producing systems included (i) outward-spiraling rainbands, which developed in the storm’s north sector in favorable environmental wind shear, and (ii) frontal cloud as a result of coastal frontogenesis. Over the rain area, in addition to enhanced ascent, there were increases in low-level moisture, convective instability, and midlevel relative vorticity. There is evidence of a preconditioning period prior to the rain when midlevel subsidence and boundary layer moistening occurred. From analysis of low-level equivalent potential temperature the following observations were made: (i) after landfall, a cold, dry airstream wrapped into Fitow’s circulation from the north, limiting the inner-core rainfall and producing a cold-air boundary, and (ii) an extended warm, moist airstream from the east converged with the cold-air intrusion over the rain area. The heavy rain occurred as the large-scale flow reorganized. Major anticyclones developed over China and the North Pacific. At upper levels, a large-amplitude trough relocated over central China with the entrance to a southwesterly jet positioned near Shanghai. Back trajectories from the rain area indicate that four environmental interactions developed: (i) increasing midlevel injection of moist potential vorticity (PV) from Fitow’s circulation; (ii) low-level warm, moist inflow from the east; (iii) midlevel inflow from nearby Typhoon Danas; and (iv) decreasing mid- to upper-level injection of PV from the midlatitude trough. The authors propose that the resultant PV structure change provided a very favorable environment for the development of rain systems. |
| Databáze: | OpenAIRE |
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