East Asia and Western Pacific METEOROLOGY AND CLIMATE

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473 48-hour Forecast Errors Rel. to (P + O/2 1980-1988 RO Year O JTWC Fig. 3. 48-hour forecast errors of the RO and the JTWC relative to those of the (P+O/2 method for the years 1983-88. A positive (negative) value means that the forecast is worse (better) than that of the (P+O/2 method. Warning Intensity 1983-1988 Errors 1983 1964 1985 1966 1987 a RO Year O JT W Fig. 4, Warning intensity errors of the RO and JTVC'.for the years 1983-
474 A SPECTRAL MODEL FOR MEDIUM RANGE WEATHER FORECASTS AND ITS PERFORMANCE Ji Liren Chen Jiabin Zhang Daomin Wu Wanli Shen Rujin Sheng Hua Huang Boyin (Institute of Atmospheric Physics, Beijing) ABSTRACT A global spectral model developed by Lab II, IAP and its performance are introduced in this paper, The model has some merits in the treatment of large scale orography. By introducing a standard stratification, the prognostic variables are separated into a basic part and a deviation part respectively. The spectral expansion is conducted only for the deviation, thus improving the convergence rate. Recently, the scheme has been generalized with a latitudinally dependent basic state and a still higher forecast score expected. The parameterization schemes for diabatic physical processes included in the model are also briefly discussed. Finally, as an example, a five—day forecast for a real case is given, in which the setting in of bai-u rain belt in the Yangtze Valley and the northward shift of the subtropical high over the west Pacific are well reproduced. Comparative forecast experiments show the crucial influence of diabatic factors on the medium range variation of the subtropical high. 1. INTRODUCTION Over the past ten years, substantial progress has heen achieved in medium range numerical forecast. As an example, the practical preditability of ECMWF model has reached about six and a half days on average. Efforts for this purpose in China may be traced back to the mid seventies when a hemispheric model including various diabatic physical processes (Zhu et al, 1979) was developed and a number of numerical experiments on medium range weather processes carried out (Jiang et al. 1982). However, being restricted by computer resources and other conditions, a system for operational medium range forecast was developed only in the last two years. The global spectral model reported here is a part of the joint efforts. In section two of this paper, the dynamic framework of the model will be described. The discussion will be focused on the use of standard stratification approximation in spectral formulation. Section three presents a brief description of all components of diabatic processes included in the model. Section four illustrates the performance of the model by forecast experiments for a real case. And finally, the conclusion. 2. MODEL EQUATIONS AND METHOD OF SOLUTION The model equations and their spectral formulation, and the semi-implicit time in-
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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
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16 Fig.l Climatological daily rainf
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18 showed a marked contrast between
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20 3. SWDPTiC ^mLYSIS WD DIA^DSTIC
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22 and Chang (27). It was also foun
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24 triggering mechanisms. In additi
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26 important mechanism for creating
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28 mature convections. Satellite pi
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30 States included 70 scientists an
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1-4 M-H C CO *+-« C CD 4-9 C o •
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34 19.Chen, G.T. J., "A study on sy
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36 complexes: 27-28 May 1981 case",
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38 On Temporal Variations of Low Le
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40 low-level flows of the Asian sum
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42 the northern part of the Pacific
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44 cycle is observed for the amplit
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46 SUMMER (6-85 : 12 2 M979 P:850 M
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Observed Structure and Propagation
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50 southeasterly current in the wes
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40°N 30°N 15°N Equator 90°E 105
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54 The pattern of arrows in Fig. 3
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56 Figure 5. Vertical cross-section
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58 TOE MEAN HEAT SOURCES OVER ASIAN
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60 over tost parts of India, Southe
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62 inctly different types. One is t
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64 60 70 too no 120 00
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Fig.2.The 7-month mean values of (a
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68 A NUMERICAL SIMULATION OF THE ME
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70 Synoptic circulation patterns fo
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72 (iii) The mid-latitude westerlie
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74 and the temperate latitude weste
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76 O 1 - (b) Total I Rainf a" 4 0
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78 LONGITUDE TIME WINOCROS5 SECTION
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A simulation of Lee-Cyclogenesis ov
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82 implemented to the global model
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84 In all three experiments, a deep
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86 References: Ballish, A.B., 1980:
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93 1.2-a I2.S 120. 127,5 US. 11.5 7
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95 2. Climatology of East Asian mon
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97 850 MB WIND (U*. V) S. 0 30N i~^
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99 120 ISO ISO 210 2VJ 770 ISO 180
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Figure 6 (a) Time-longitude section
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103 Monsoon cyclones /-~N I Subtrop
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105 INFLUENCE OF VARIATIONS OF THE
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surface during the rainy period of
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located at the position of the firs
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egion of western Australia. These t
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115 Fig.^57 Characteristics of vari
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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
Page 445 and 446: 422 EXPERIMENT: Only simple and eas
Page 447 and 448: 424 With the ability to simulate co
Page 449 and 450: 426 (5) Meroney, R.N., Cermak, J.E.
Page 451 and 452: 428 Fig. 3 Composite Photograph of
Page 453 and 454: 430 A detailed description of the m
Page 455 and 456: 432 However, the schemes failed to
Page 457 and 458: 434 REFERENCES Anderson, E. and A.
Page 459 and 460: 436 Figure 2 Vertical structure of
Page 461 and 462: 438 36 HOUR FORECAST MEAN SEA LEVEL
Page 463 and 464: 440 al.,1984). In this paper, a gen
Page 465 and 466: 442 where subscript x denotes u, v,
Page 467 and 468: 444 AM AM PO- N3 A/i + N3' and NH--
Page 469 and 470: 446 there is only a minor differenc
Page 471 and 472: 448 Guo X.R.,Yan Z.H.,Zhang Y.L. an
Page 473 and 474: 450 THE EAST ASIA HEAVY RAINFALL NU
Page 475 and 476: 452 (described in section 2) carrie
Page 477 and 478: 454 Fig. . 2. Validation of Tempera
Page 479 and 480: 456 simulate the partly cloudy cond
Page 481 and 482: 458 3.3 Nesting Run with 2 km Grids
Page 483 and 484: 460 REFERENCES Bhumralker, C. M., 1
Page 485 and 486: 462 The Impact of the Termination o
Page 487 and 488: 464 and 45.8 km respectively, which
Page 489 and 490: 466 relative to (P+O/2, they actual
Page 491 and 492: 468 Chang, S. W., 1982: The ore-gra
Page 493 and 494: 470 Table 3. 24-hour forecast error
Page 495: 472 Initial Position Errors 1983-19
Page 499 and 500: 476 where I p u = FC-
Page 501 and 502: 478 given. This is treated separate
Page 503 and 504: 480 predicted location is too far t
Page 505 and 506: 482 Fig.2 Distribution of 24h preci
Page 507 and 508: 484 LONG-RANGE FORECASTING OF TAIWA
Page 509 and 510: 486 monsoon in east Asia and for co
Page 511 and 512: 488 unfortunately are not integral
Page 513 and 514: Figure 1. SPECTRAL ANALYSIS FOR MAY
Page 515 and 516: 492 TaUj.g_ji Multiple rnfjross i o
Page 517 and 518: 494 THE NONLINEAR INTERACTION OF IN
Page 519 and 520: 496 Burgers(l948) had put forward a
Page 521 and 522: 498 From Eqs,(8), the necessary con
Page 523 and 524: 500 In order to show quantitatively
Page 525 and 526: 502 Multiple Equilibria Of a Therma
Page 527 and 528: 504 For the two-level quasi-geostro
Page 529 and 530: 506 The coefficients Z, T, H, and T
Page 531 and 532: 508 just the stable Branch 7 for st
Page 533 and 534: 510 REFERENCES Bolin, B., 1950: On
Page 535 and 536: 512 STATIONARY SOLUTIONS WITH TOPOG
Page 537 and 538: 514 ANNTTAL CYCLE OF 2TTT Fig. 7 An
Page 539 and 540: 516 CISK modes have narrow axes of
Page 541 and 542: 518 about one to three weeks. Predi
Page 543 and 544: 520 first one. In his work, the lon
Page 545 and 546: 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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