-- Pressure dip (MM5) Pressure dip inflow PD Pressure dip Pressure dip MM5 Pressure dip( PD ) 980 Fig. TY Zeb(980) 970 40 6hPa PD TY Della(490) 4 5 6 7 8 PD Fujita(95a)Time(UTC) PD (Fujita95b 99 980979 99 99a 994 994) (hpa) PD (00) PD 0 9 (Fig.) PD PD PD Fujita(95a) PD Matsumoto and Okamura(985) 0050km (99) MD PD Fig.. Observed barograms at Tottori for period 00 800 UTC on 7 October 998. 0050km
Trough Lower layer 50 Fig.. Schematic description of the synoptic-scall 5 0 5 0 5 40 45 50 environment specifying the pressure dip. Fig.4. Infrared image from GMS at UTC on 7 October 998. 7.0 (999) (000) (00) 7 PD ) 4.0 ) 4 Upper layer PD TY Oliwa(979)TY Vicki(9807)TY Zeb(980) PSU/NCAR (MM5) PD PD 6 PD 5 PD PD 0N 0N 40N 50N T980 T9807 T979 Typhoon 0E 0E 40E 50E Fig.. Tracks of three typhoons as TY Oliwa(979), TY Vicki(9807) and TY Zeb(980). Fig. TY OliwaTY VickiTY Zeb Fig.5. Pressure dip isochrones (solid line), and the hourly position center in (a) TY Zeb (b) TY Oliwa and (c) TY Vicki. Close circles mean the stations where observed pressure dip. latitude latitude 50 45 40 5 0 6.0 5.0.0.0.0 0 4 56 0 4 4 7 8 9 0.0 N 9.0 o E 0.0 o E.0 o E.0 o E.0 o E 4.0 o E 5.0 o E 6.0 o E 4 6 5 0 longitude 7 7 8 5 7 N 9 o E 0 o E o E o E o E 4 o E 5 o E latitude 6 5.5 5 4.5 4.5 5 4 4 5 6 7 longitude 9 8 5 0 7.5 4 4.5 5 5.5 6 6.5 longitude 0 4 0 5 6 00 90 80 70 60 50 40 0 0 0 00 90 80 70 60
GMS (Shimazu 998)(Fig.4) PD Fig.5(a)TY Zeb PD 6 (JST) 00km (6UTC) 6hPa Fig.6. MM5 grid configuration for the 45km, 5km and (Fig.)Fig.5(b),(c) TY Oliwa TY Vicki PD TY Oliwa PD (Fig.5(b)) TY Vicki PD (Fig.5(c)) 99b) PSU/NCAR MM5 Luis and Joseph (00) MM5 Jordan(997) TY Zeb (case Zeb)TY Oliwa (case Oliwa)TY Vicki (case Vicki) Fig.9(a),(b) case Zeb(D)7UTC 4UTC (0x0km) 45km Domain(D) 5km (Fig.9(a)) Domain(D) 5km Domain(D) 5km grids of domains in case Zeb, and sea level pressure field at initial time of the run. Fig.7 case Zeb(D) ( MM5(Grell,994) Fig.8 Fig.4 40000hPa ( 7 4 ) 00hPa ( ) (Fig.6) (Fig.9(b)) Simple ice(dudhia,989) Grell(99) PD (Fig.5(a)) Fig.0 Fig. Fig.6 case Zeb 00km 0 hpa 448
Fig.7 Model tracks in case Zeb simulations. The positions are shown at -h intervals by cross, and dots present the typhoon track. Fig. Fig.9(b) (a)(c)(e) (b)(d)(f) 650hPa (Fig.(b)) (Fig.(a)) inflow outflow inflow (Fig.(c),(d)) Fig.(e),(f) D warm core Fig.8. Distribution of relative humidity between 400 and 00 hpa level at UTC on 7 October 998. PD Fig.9(c) case Oliwa(D 6 ) (Fig.5(b)) PD PD Fig.9(d) case Vicki(D 0 ) PD (Fig.5(c)) Fig. Fig.9(b) 6 PD Fig.(a),(b) Fig.9(a),(b) 500hPa
(a) (b) N W E S (c) (d) Fig.9. Sea level pressure fields of Domain (a) at 7 UTC, (b) at 4 UTC on 7 October 998 in Case Zeb, (c) at UTC on 6 September 997 in Case Oliwa, and (d) at 8 UTC September 998 in Case Vicki. 76hPa 687hPa 68hPa Jet 985 MD Trough inflow 4 5 6 7 8 9 warm core hpa 990 TIME(UTC) Fig.0. Time series of sea level pressure at longitude 4E and latitude N5.5 for period 00 900 UTC 7 October 998.
(a) (b) W E S N (c) (d) W E S N (e) (f) W E S N Fig.. Vertical cross sections: (a) (b) zonal wind or meridional wind (arrows) and vertical velocity (shade); (c)(d) specific humidity (shaded) and vertical velocity (short-dashed line is upward and thin line is downward); (e)(f) potential temperature (thin line), warm anomaly (shaded) and sea level pressure (solid line). (a)(c)(e) are west to south cross sections at 4.5N and (b)(d)(f) are the south to north cross sections at.5e of D in case Zeb at 4 UTC on 7 October 998. 6 000m 00K
Elizabeth and Elsberry (00) (Johnson and Hamilton988Johnson00) jet Fig.. The back trajectory analysis, which were chosen to begin at about 750 hpa level above the defined by cross in this figure and around the defined by dot at 4 UTC on 7 October 998 in case Zeb. PD TY Kirk(96) TY Opal (9707)TY Peter (9708) MM5 Fig.4 TY Peter D( 6 ) TY Oliwa case Oliwa Fig.. Geopitential height at 500 hpa, horizontal wind (m/s, arrows), vertical velocity (short-dashed line is downward), and horizontal convergence (shaded) (a) at 7 UTC, and (b) at 4 UTC on 7 October 998 in Case Zeb. Fig.4. Sea level pressure field of Domain at 4 UTC on 8 Jun 997 in Case Peter.
PD MM5 PD PD () PD Fig.5 PD outflow PD outflow inflow 994 inflow 999 980 No.8pp.0 PD 99 PD () 87 pp. PD 99. Upper layer Lower layer PD Typhoon Fig.5. Conceptual diagram around the Pressure dip within the typhoon system. PD 994 99 Pressure dip 46 pp.58. 979 PD 8 (788) B-pp.40748. 980 796 B-pp.87. 99 99 5 B-pp.89. 99a 99 5 pp.7 5. 99b 9 7 B-pp.546. (000)980 Pressure Dip 47pp.44-45. 00 Pressure dip 44 B-pp.5969. Dudhia,J,(989) Numerical Study of Convection observed during the Winter Monsoon Experiment Using a Mesoscale Two-Dimensional Model Vol.46 Journal of
the Atmospheric Science, Vol.46 pp.077-06. Elizabeth A. Ritchie and Russell L. Elsberry000of the Landfall of Hurricane Nora (997) Simulations of the Transformation Stage of the Mon.Wea.Rev. Vol.907-088. Extratropical Transition of Tropical Cyclon Johnson,R.H. and P.J.Hamilton, (988) The Relationship Mon.Wea.Rev. Vol.946-480. Fujita,T. 95a Study on Pressure Dip within Typhoon DellaKyushu Institute of TechnologyVol.pp.5 6. of Surface Pressure Features to the Precipitation and Airflow Structure of an Intense Midlatitude Squall Lin Mon.Wea.Rev. Vol.6 444-47. Johnson,R.H., (00)Surface Mesohighs and Mesolows Fujita,T.95bStudy on Typhoon and Convection Bull.Amer.Meteor.Soc., vol.8-. Report of Meteorological Laboratory, Kyushu Institute of TechnologyVol. Nos.-4pp.6467. Jordan,G.Powers (997) Numerical Model Simulations of a Mesoscale Gravity Wave Event:Sensitivity Tests and Fujita,T.99 Mystery of Severe StormsSection 5.4 Japanese TyphoonsChicago Univ. pp.4450. Luis M. Farfan and Joseph A. Zehnder (00):An Analysis Spectral Analyses Mon.Wea.Rev.Vol.5 88-869. atsumoto Sand OkamuraH985 The Internal Elizabeth A. Ritchie and Russell L. Elsberry000Gravity Wave Observed in the Typhoon T84(Gay) Simulations of the Transformation Stage of the Journal of the Meteorological Society of JapanVol.6 Extratropical Transition of Tropical Cyclon pp.75. Mon.Wea.Rev. Vol.946-480. Grell G.A., J.Dudhia, and D.R.Stauffer,(994) A description of the fifty-generation Penn State/NCAR mososcale model (MM5).NCARTech.Note NCAR Shimazu Y (998)Classification of Precipitation Systems in Mature and Early Weakening Stages of Typhoons around Japan Journal of the Meteorological Society of JapanVol.76 pp.47445. /TN-98 +R pp Hironori FUDEYASU* and Taiichi HAYASHI *Graduate School of Science, Kyoto University Synopsis A Pressure dip is small pressure depression, often observed as a meso--scale phenomenon in a typhoon internal system. Its mechanism and the details of structure have not been clarified at present. We simulated three cases of the PD within the typhoon by applying the mesoscale model MM5. The simulation resulted that the meso-scall trough was shown at back-left quadrant of the typhoon during the typhoon passing. The small trough was caused by warm anomaly by adiabatic warming in lower-troposphere due to the dry intrusion, which was an inflow from synoptic environment to the typhoon center. Since the situation around the is similar to observations of the PD, the PD has same structure as. Keywords: Pressure dip; Typhoon; moso-scale model; MM5, dry-intrusion, meso-low