East Asia and Western Pacific METEOROLOGY AND CLIMATE

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Fig.6. Time sections of the areal mean vertical p-velocity -.[wi (lower, 10" hpa/s ),heating rateCQ^l/C (middle,K/day) and drying rate iQ 2 l/C (upper,K/day)for middle India. Fig.5. The 7-month mean profiles of the areal mean vertical p-velocity iwHthin solid line, 10" hpa/s},heating rate [Q^/C (thick solid line,K/day) and drying rate [Q 2 "|/C^(dash llne,K/day) for eight regions(see text for details). 200- 500- 500- 700- 850 tooo loo 200 300 500 700 B50 /WO -0 -8 -6 -* -2 0 2 4 6 8 fo -/O -8 -6 -* •* 0 2 A- 6 8 10
68 A NUMERICAL SIMULATION OF THE MEI-YU FRONT L.C. Chou, C.P. Chang and R.T. Williams Department of Meteorology, Naval Postgraduate School, Monterey, CA, USA ABSTRACT A two-dimensional frontal model was used to study the structure and behavior of the Mei-Yu front, with special emphasis on the dynamics of the low-level jet (LLJ) that is frequently observed ahead of the front. This study is motivated by the unique mixed midlatitudetropical properties of the Mei-Yu front, where heavy convection and strong low-level horizontal shear are associated with the nearly zonaliy-oriented front. The occurrence of the LLJ is highly correlated with heavy convective rainfall. The quasi-steady state responses to a large-scale stretching deformation forcing were obtained by integrating the perturbation equations from an initial state of seasonal-mean zonal^flow. Two major sets of experiments, based on midlatitude and subtropical conditions, were conducted. For. each set of initial conditions, a number of supplemental cases were integrated to study the effects of varying initial humidity values and surface fluxes of heat and moisture. The midlatitude front extends deeply into the upper troposphere with a strong poleward tilt, whereas the subtropical front is confined to the lower troposphere with less tilt, in good agreement with observations. Along the sloping front, slantwise updrafts develop with a multi-band structure. This updraft is more evident in the subtropical cases and in the more moist midlatitude cases. A westerly jet In the upper troposphere and an easterly jet in the lower troposphere develop in both midlatitude and subtropical cases, with smaller intensities in the subtropical cases. The inclusion of more humidity or surface heat and moisture fluxes leads to stronger upper westerlies, apparently as a result of stronger cumulus convection. For the subtropical cases, concurrent development of upper-level easterlies and low-level westerlies equatorward or the front Is observed. The low-level westerly maximum at z = 3-4 km resembles a LLJ, whose Intensity increases when more moisture is Included. The concurrent development suggests that the LLJ may be the result of a thermally-direct secondary circulation that resembles a "reversed Hadley" cell. This circulation is revealed by a meridionalvertical streamfunction, with a strong lower branch return flow coinciding with the development of a LLJ in the more moist, subtropical cases. The Coriolis torque of the meridional circulation can develop and maintain the upper easterlies and the LLJ. Importance of cumulus convection and especially slant-wise convection in developing the reversed Hadley cell and the LLJ is suggested. These conclusions are consistent with the observed intense convection and heavy rainfall in the Mei-Yu front, and a sinking region south of the Baiu front as revealed by Matsumoto's (1972) moisture analysis.
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UNIVERSITY OF HONG KOHG LlBEAEY
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International Conference on East As
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FOREWORD The International Conferen
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VHI LIST OF PARTICIPANTS IN THE PHO
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45 LIM, Hock National University of
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XIII INTERNATIONAL ORGANIZING COMMI
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XV! The mean heat sources over Asia
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XVIII , Jhe impact of urbanization
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XX The East Asia heavy rainfall num
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THE THERMAL STRUCTURE AND CONVECTIV
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THE COUPLING OF UPPER-LEVEL AND LOW
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Q \ ed atmospheric processes * 2. M
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2) DH Experiment The horizontal flo
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of the orography, establishing a na
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11 a o 12 21 36 4$ 60 fZ Pig.3. Nea
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14 OVERVIB/V CF MEI-YU RESEARCH IN
Page 39 and 40: 16 Fig.l Climatological daily rainf
Page 41 and 42: 18 showed a marked contrast between
Page 43 and 44: 20 3. SWDPTiC ^mLYSIS WD DIA^DSTIC
Page 45 and 46: 22 and Chang (27). It was also foun
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Page 49 and 50: 26 important mechanism for creating
Page 51 and 52: 28 mature convections. Satellite pi
Page 53 and 54: 30 States included 70 scientists an
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Page 57 and 58: 34 19.Chen, G.T. J., "A study on sy
Page 59 and 60: 36 complexes: 27-28 May 1981 case",
Page 61 and 62: 38 On Temporal Variations of Low Le
Page 63 and 64: 40 low-level flows of the Asian sum
Page 65 and 66: 42 the northern part of the Pacific
Page 67 and 68: 44 cycle is observed for the amplit
Page 69 and 70: 46 SUMMER (6-85 : 12 2 M979 P:850 M
Page 71 and 72: Observed Structure and Propagation
Page 73 and 74: 50 southeasterly current in the wes
Page 75 and 76: 40°N 30°N 15°N Equator 90°E 105
Page 77 and 78: 54 The pattern of arrows in Fig. 3
Page 79 and 80: 56 Figure 5. Vertical cross-section
Page 81 and 82: 58 TOE MEAN HEAT SOURCES OVER ASIAN
Page 83 and 84: 60 over tost parts of India, Southe
Page 85 and 86: 62 inctly different types. One is t
Page 87 and 88: 64 60 70 too no 120 00
Page 89: Fig.2.The 7-month mean values of (a
Page 93 and 94: 70 Synoptic circulation patterns fo
Page 95 and 96: 72 (iii) The mid-latitude westerlie
Page 97 and 98: 74 and the temperate latitude weste
Page 99 and 100: 76 O 1 - (b) Total I Rainf a" 4 0
Page 101 and 102: 78 LONGITUDE TIME WINOCROS5 SECTION
Page 103 and 104: A simulation of Lee-Cyclogenesis ov
Page 105 and 106: 82 implemented to the global model
Page 107 and 108: 84 In all three experiments, a deep
Page 109: 86 References: Ballish, A.B., 1980:
Page 116 and 117: 93 1.2-a I2.S 120. 127,5 US. 11.5 7
Page 118 and 119: 95 2. Climatology of East Asian mon
Page 120 and 121: 97 850 MB WIND (U*. V) S. 0 30N i~^
Page 122 and 123: 99 120 ISO ISO 210 2VJ 770 ISO 180
Page 124 and 125: Figure 6 (a) Time-longitude section
Page 126 and 127: 103 Monsoon cyclones /-~N I Subtrop
Page 128 and 129: 105 INFLUENCE OF VARIATIONS OF THE
Page 130 and 131: surface during the rainy period of
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119 Some Dynamic Aspects of the Equ
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121 equatorial zonal plane. In this
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123 where N is nondimensional Newto
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125 moisture concentration graduall
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127 boundary layer frictional conve
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129 000 - 20 30 WAVELENGTH (10 3 KM
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131 CHINESE POLAR ORBITING METEOROL
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some middle and small receiving sta
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135 local meteorology units through
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140 The Mesoscale Monitoring System
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142 The weather radar network is co
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144 where V and L are in centimeter
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146 PRF: 80-2000 Hz Minimum detecta
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148 [UHF Doppler RadaT] ^Pibalk ' Z
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150 STRUCTURAL FEATURES OF A SQUALL
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152 25 2200L 16 MAY 0000 L 17 MAY X
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154 0*73 KN 0,73 KM TAMEX IOF2 00*1
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156 4.2 East-west Cross Section The
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158 KM -20 EAST OF TOGA -10 0043 28
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160 Radar Observation of Precipitat
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162 Fig. 2. A triple doppler networ
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164 for this presentation Fig. 5a(0
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166 near the northern tip of Taiwan
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168 In order to understand the inte
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170 REMOTE SENSING OF ATMOSPHERIC C
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172 In the meantime, with the incre
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174 method (scanning frequency) and
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176 For sharp absorption lines, the
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178 [10]* Sun Jinhui, Qiu Jinhuan e
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180 COMPARISION OF RADAR ESTIMATES
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182 of 29 %). The Ra/Rg and the rel
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184 under 1) errors in estimating r
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186 Table 1. Summary of Ra/Rg for t
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188 FIGURE 3. CORRELATION COEFFICIE
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190 DOPPLER WEATHER RADAR OBSERVATI
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192 which are concerned about by th
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194 fly on schedule, take off and l
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196 and minus value. Fig. 4 is the
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198 REFERENCES 1. Donald Turnbull e
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200 evaporation, condensation, wind
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202 control valve which permits amp
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204 Table 1 Rainfall Records of a T
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206 various rainfall intensity shou
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208 c 400-- £ o "5 350 H — A —
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210 IMPACT OF HOURLY S-VISSR SATELL
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212 Fig. 1. Daily 1.200 UTC • 500
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I Fig. 2. GMS-3 IR picture taken at
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216 110E 20 115E 30. 20" X J 4o*N'\
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218 Fig. 7. Provisional best track
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220 PREDICTABILITY OF LOW FREQUENCY
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222 expressions that invoke the Mon
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224 b) A low frequency mode experim
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226 A CLOUD WAVE THEORY AND ITS APP
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228 heating indicating a substantia
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230 If N Fig. I, A schematic diagra
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232 2. A Quasi-Diabatic Geostrophic
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234 X can be q, £ c, v, or T. The
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236 On the basis of the preceding d
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238 west of the maximum cloud cover
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240 NORMAL MODES OF CLIMATOLOGICAL
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242 (1983) pointed out that simulat
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244 reach the top of model atmosphe
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246 is not clear in the tropics. Th
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248 Wang, J.-T., J.-W. Kim and W.L.
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250 (a) 30°N-30°S (January) (b) 3
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252 An Important element of the ear
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254 IOCS I02S 3SN Fig. 1 A general
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256 staion of LID (farmland in the
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258 start from October 1990 and end
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260 The measurements of surface rad
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262 Secular trends in urban tempera
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264 LONGTERM TEMPERATURE TRENDS AT
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266 Using these data sources It has
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268 (3) a nearly static phase where
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270 greater rate of increasing mini
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272 consistent with accepted theory
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274 RECENT APPLICATIONS OF THE PENN
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276 upward motion (Fig. Ib) of air
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278 Stauffer and Warner (1987) used
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280 observed precipitation rates fo
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282 coupled model system show that
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284 Baroclinic Instability of Modif
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286 Eq (2.4) corresponds to the con
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288 conventional Eady waves, except
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290 perturbations in Mode I remains
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292 5: Summary And Remarks Two diff
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294 INFLUENCES OF OROGRAPHY ON FLOW
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296 (13) The next step is to determ
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298 where „ = 1 - R a = - R 2>x c
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300 — -~ 1, thus the above relati
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302 The vertical velocity at the to
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304 THE MIGEOPHYSICS OF A MEI-YU CA
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306 O.Qg-m" 3 , which is probably d
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308 snowflakes aggregation generate
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310 (a) TRP.CK - 2 (1652 0 - 1711 0
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312 1987 6/16 17QSSO U 0.9 C 2 = 1.
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314 2. Heavy Rainfall Upstream of a
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316 accumulated rainfall amount on
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318 Figures 11 and 12 demonstrate t
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320 DEGREE K IT ( M/S ) QC (G/KG) -
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322 270 290 310 330 350 370 POTJEMP
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324 A primitive equation model was
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326 had already been affected by so
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328 I .011 I 1...J/1 l\l l-L-l L I
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330 «'.. Fig. 11 Same as Fig. 9 ex
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332 Mathiar, M. B., 1983: A quasi-L
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334 Long (1985), the maximum occure
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336 February 1979. It clearly indic
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338 Jiang H. M. and Jeng H. N., "Nu
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TEMP.GRAD.(C/100KM3 1979/2/04/OOZ 1
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TKANS.C1R. 9 1979/2/04/OE2 •; J97
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344 however, the sharp decrease in
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346 00 " XD 3 b D 3 aD b dD = [ N.
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348 heights. The median diameter an
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350 going on within the melting lay
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352 TRFICK - I (HIS 0 - H31 0J PR0B
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354 MONTHLY AND SEASONAL FORECASTS
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356 In another experiment, the heat
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358 4. CONCLUSION The forecasting e
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360 TABLE 1. COMPARISONS OF THE COR
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362 Fig. 3. Map of the correlation
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364 THE TELECONNECTION OF EQUATORIA
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366 3-*-j-] dag grid % ^Showing eve
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368 oBE (6) fl(uP) , fl(vP) ... 0(w
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370 the major tidal components over
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372 one meter. Most of the water le
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374 and Technology Advisory Group,
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376 INTRODUCTION In 1%6, Bjerknes,
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378 THE INTERANNUAL VARIABILITIES O
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380 current between 127° E—128°
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382 El Nino and Southern Oscillatio
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384 Fig.5. The ADCP measurements (s
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386 I. Introduction Climate is one
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388 specifically at the modeling an
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390 Even during the warm phase of t
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392 (iv) To investigate the morphol
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394 Change program under IGBP is a
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396 TABLE 1: PROCESSES TO BE STUDIE
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398 w / / / / / / / / /-"V / / Z Fi
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400 CHINA-JAPAN JOINT RESEARCH PROG
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402 eastward. In addition to mainta
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404 Processes of Hicroscale Air-Sea
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406 phase velocity; both ratios, th
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T i l l ! o I • GO 00 J Wind Velo
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410 Concluding Remarks In order to
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412 THE VARIATIONS OF THE SST IN TH
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414 maps, there is an extensive are
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416 Flg.1. Time series of the annua
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418 90 N 90 S|. . . 20E 20E Fig.3c.
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420 ON LABORATORY SIMULATION OF SEA
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422 EXPERIMENT: Only simple and eas
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424 With the ability to simulate co
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426 (5) Meroney, R.N., Cermak, J.E.
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428 Fig. 3 Composite Photograph of
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430 A detailed description of the m
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432 However, the schemes failed to
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434 REFERENCES Anderson, E. and A.
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436 Figure 2 Vertical structure of
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438 36 HOUR FORECAST MEAN SEA LEVEL
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440 al.,1984). In this paper, a gen
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442 where subscript x denotes u, v,
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444 AM AM PO- N3 A/i + N3' and NH--
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446 there is only a minor differenc
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448 Guo X.R.,Yan Z.H.,Zhang Y.L. an
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450 THE EAST ASIA HEAVY RAINFALL NU
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452 (described in section 2) carrie
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454 Fig. . 2. Validation of Tempera
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456 simulate the partly cloudy cond
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458 3.3 Nesting Run with 2 km Grids
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460 REFERENCES Bhumralker, C. M., 1
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462 The Impact of the Termination o
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464 and 45.8 km respectively, which
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466 relative to (P+O/2, they actual
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468 Chang, S. W., 1982: The ore-gra
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470 Table 3. 24-hour forecast error
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472 Initial Position Errors 1983-19
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474 A SPECTRAL MODEL FOR MEDIUM RAN
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476 where I p u = FC-
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478 given. This is treated separate
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480 predicted location is too far t
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482 Fig.2 Distribution of 24h preci
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484 LONG-RANGE FORECASTING OF TAIWA
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486 monsoon in east Asia and for co
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488 unfortunately are not integral
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Figure 1. SPECTRAL ANALYSIS FOR MAY
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492 TaUj.g_ji Multiple rnfjross i o
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494 THE NONLINEAR INTERACTION OF IN
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496 Burgers(l948) had put forward a
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498 From Eqs,(8), the necessary con
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500 In order to show quantitatively
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502 Multiple Equilibria Of a Therma
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504 For the two-level quasi-geostro
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506 The coefficients Z, T, H, and T
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508 just the stable Branch 7 for st
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510 REFERENCES Bolin, B., 1950: On
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512 STATIONARY SOLUTIONS WITH TOPOG
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514 ANNTTAL CYCLE OF 2TTT Fig. 7 An
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516 CISK modes have narrow axes of
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518 about one to three weeks. Predi
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520 first one. In his work, the lon
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522 The works mentioned are qualita
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524 [12] Wang, S.-W., Adv. in Atmos
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526 processes that give rise to a d
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528 3 Local energetics analysis The
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530 dominant waves of a local mode
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532 slightly longer than the length
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534 tends to induce a westerly jet
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536 TYPHOON FORMATION AND DEVELOPME
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538 influence of the mean wind prof
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540 3. Steady-State Solutions The p
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542 of maximum wind (Fig 7 c). This
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544 (A) b- l.O.(B) b- 0.8.(C) b- 0.
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546 b= 1.0,C= 0.03,0 = 120., T = 50
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548 tropical cyclones. Then, Shapir
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550 fine equation (2) will be used
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552 4) Cumulus vertical flux of hea
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554 Fig. 4 Same as Fig, 1, but for
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556 n=800 bPa and r **1. Now it is
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558 RRFKRRNCF Challa, M., and R. T,
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560 The limited-area forecast syste
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562 Our study is to obtain and anal
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564 coarse grid (Fig. 5). The struc
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566 ACCUMULATED PRECIPITATION Fig.
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569 AUTHOR INDEX ANTHES, Richard A.
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571 LIOU, Chi-Sann LIU, Cho-Teng LI
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