| Summary: | 碩士 === 國立臺灣大學 === 大氣科學系研究所 === 86 === In the absence of diabatic and frictional effects, PV (Potential Vorticity)
is conserved. Moreover, once a balance condition, boundaryconditions, and app
ropriate background state have been specified, PV can be inverted to derive th
e entire three-dimensional wind and temperature distribution. PV inversion tec
hnique has been successfully proved in the understanding of mid-latitude and l
arge-scale dynamics and been more frequently applied in the tropical weather s
ystems. In this study,we use Piecewise PV Inversion Technique developed by Dav
is (1992) and the azimuthally averaged wind distribution as basic state propos
ed by Shapiro (1996) to diagnose how each PV anomaly attributes to the typhoon
motion. The quantitatively results show that Typhoon Doug motion is most cons
istent with the lower-layer (1000-300 hPa) flow which is primarilyattributable
to the upper-layer (250-100 hPa) PV anomalies at the beginning,nevertheless,
lately the lower-layer PV anomalies turns to have most contribution. Both of t
he upper- and lower-layer PV anomalies have the largest contribute to the lowe
r-layer flow most. We also demonstrate Doug''s motion is governed by the Pacifi
c Subtropical High. However, the same Piecewise PV Inversion Technique perform
s ill on Storm Ryan with different type of path. It implies thatthis method sh
ould be best performed under strong large-scale steering flow around the typho
on. Piecewise PV Inversion Technique is first applied on the Western Pac
ific Typhoon. The ultimate goal is to get quantitative understanding of typhoo
n motion of this area and to assistant future unmanned aircraft observations a
nd numerical modeling studies.
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