%0 Journal Article
%T The Genesis of Tropical Cyclone Bilis (2000) Associated with Cross-equatorial Surges<br>
%A XU Yamei
%A <br>
%J 大气科学进展
%D 2011
%I 
%X The purpose of this paper is to explore how a tropical cyclone forms from a pre-existing large-scale depression which has been observed and associated with cross-equatorial surges in the western North Pacific. Tropical cyclone Bilis (2000) was selected as the case to study. The research data used are from the results of the non-hydrostatic mesoscale model (MM5), which has successfully simulated the transformation of a pre-existing weak large-scale tropical depression into a strong tropical storm. The scale separation technique is used to separate the synoptic-scale and sub-synoptic-scale fields from the model output fields. The scale-separated fields show that the pre-existing synoptic-scale tropical depression and the sub-synoptic scale tropical cyclone formed later were different scale systems from beginning to end. It is also shown that the pre-existing synoptic-scale tropical depression did not contract to become the tropical cyclone. A series of weak, sub-synoptic-scale low and high pressure systems appeared and disappeared in the synoptic-scale depression, with one of the low systems near the center of the synoptic-scale depression having deepened to become the tropical cyclone. The roles of the synoptic-scale flow and the sub-synoptic scale disturbances in the formation of the tropical cyclone are investigated by diagnoses of the scale-separated vertical vorticity equation. The results show that the early development of the sub-synoptic scale vortex was fundamentally dependent on the strengthening synoptic-scale environmental depression. The depression was strengthened by cross-equatorial surges, which increased the convergence of the synoptic-scale depression at low levels and triggered the formation of the tropical cyclone.
%K tropical cyclone
%K genesis
%K cross-equatorial surges
%K scale-separated vertical vorticity equation<br>
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=E62459D214FD64A3C8082E4ED1ABABED5711027BBBDDD35B&cid=28A2F569B2458C17&jid=5434AFBF6CB6E7E8D67733B541F211C7&aid=DBCEB94F44F64F3EF19863424F89B39D&yid=9377ED8094509821&vid=D3E34374A0D77D7F&iid=38B194292C032A66&sid=D559883475316B44&eid=8243B77967FFD12E&journal_id=0256-1530&journal_name=大气科学进展&referenced_num=0&reference_num=30