ISSN 1006-9895

CN 11-1768/O4

Evolution Pattern of Short-Time Intense Precipitation-Producing Systems Associated with Meiyu Front
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    Abstract:

    In this paper, we study the radar echo evolution patterns and other features of short-term intense precipitation-producing mesoscale convective systems (MCSs) by examining 58 heavy rainfall events associated with the Meiyu front in East China during May to July in 2010 and 2011. Short-term intense precipitation events are deemed as such when the 1-h precipitation total exceeds 30 mm. The results show that the four most common radar echo evolution patterns of MCSs leading to short-term intense precipitation are the zonal, meridional, turning (from zonal to meridional), and combined patterns. MCSs are linear in the zonal and meridional patterns and in 70% of the turning pattern, whereas the combined pattern is oval. Although MCSs in the zonal pattern, turning pattern, and combined patterns commonly propagate backward, the characteristics of their lifetimes, movement, and durations differ significantly. In the zonal pattern, the lifetime is longest, and the intense precipitation duration is shorter than that in the turning pattern in which MCS movement is fastest and the intense precipitation duration is longest. In the combined pattern, MCS movement is slowest and the lifetime and duration are shortest. Conversely, MCSs in the meridional pattern commonly propagate forward and move more quickly than those in the other three patterns. Their lifetime is approximately half that of the zonal pattern, and their duration with more than 30 and 50 mm h-1 precipitation approximately are one-third and one-fifth of those in the turning patterns, respectively. MCSs move eastward or southward in the zonal pattern, eastward or westward in the meridional pattern, and toward all directions in the combined pattern. That is, MCSs can move northward only in the combined pattern. Although the intense precipitation persistence is long-or short-term in the four patterns, differences in radar echo intensity and radar echo depth are rare. It is deduced that the intense precipitation duration is closely related to propagation type. A larger proportion of forward propagation corresponds to a shorter lifetime and shorter duration in the meridional and combined patterns; similarly, a larger proportion of backward propagation corresponds to longer duration in the turning and zonal patterns. Forward propagation associated with the longest intense precipitation in the turning pattern is rare.

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History
  • Received:August 21,2013
  • Revised:December 30,2013
  • Adopted:
  • Online: July 06,2014
  • Published: