61 6 2003 12 ACTA METEOROLO GICA SIN ICA Vol. 61,No. 6 December 2003 Ξ (,LASG,100029 ;,211101 (,LASG,100029 ;,430074 (,LASG,100029 (20 35 N,103 120 E : 1 ISCCP ( International Satellite Cloud Climatology Project2D2, 67 %, 4 % 2 [1 ] 3 K CO 2 ISCCP2D2 1983, [2 4 ] Klein [5 ],, 50 % ISCCP2D2 Ξ :2003 4 7 ; :2003 5 20 : (ZKCX22SW2210 (40233031 40023001
734 61 [6 ] (20 35 N,103 120 E, ( 20 25 N, 105 120 E, (25 35 N, [7 ], 103 120 E 60 %,, : ;,,,, 3, ISCCP W/ m 2 [8 ] Bergman [9 ], 5 15 W/ m 2, 1 5 W/ m 2,, [10 12 ] (, 5 d 1 1 2, 1990 1 1998 12 (20 35 N,103 120 (10 55 N,75 135 E 2 ( 08 20 (1000,925,850,700,500, (20 25 N,105 400,300,250,200,150,100 hpa 120 E 16 (25 35 N,103 120 E 30 6 7 8 80 % 4 E 2001 1 2001 12 46 0 10 ; 10 3 4 ( 02,08,14,20 3 1808, 4, 800 1100 ;
6 : 735 16 30 IS2 CCP (, ( 1 ( Internet NASA Langley Research Center,At mosp heric Sciences Data Center ISCCP2D2 [13,14 ] 1990 1 1998 12 ( 1983 7 2001 6, 1990 1998 2. 5 2. 5, ISCCP [15 ] ( ISCCP, 1 1990 1998 (20 35 N, 103 120 E ( 15 % [16 ] [2 ] ( 2 1990 1998 (10 55 N,75 135 E 2
736 61 3 1990 1998 (10 55 N,75 135 E 2 NCEP ( National Centers for Environmental Prediction ( % 4 ( 73. 7 m 1997 2 17 20 3 896 hpa 811 hpa,768 730 hpa,,, ( 2 ( 3, 3. 1 ( [17 ] 4 1997 2 17 20 (,
6 : 737? 730 hpa : 5, ISCCP 2 750 800 hpa ( [18 ] 3. 2 :, : 5 1990 1998 2 30 N 2 ( : % (30 N,3, ( 6 : 7 [ 6 ]
738 61, 600 500 hpa 925 hpa, 700 600 hpa, ( [19 ] 6 1979 1996 2 30 N 2 (NCEP : Pa/ s 7 (25 35 N,103 120 E 1990 1998 ( :10-7 / s
6 : 739 8 (20 25 N,105 120 E 16 4 4. 1 8 16 9 (12,1,2 [21 ] ;3 5 ;6 8 ;9, 11 03 06 14,, [20 ], 03 06,,,,,, (,, 14, 9, [ 21 ], 10 1998 12 11 20 12 08 (decouple ( 1074. 3 m
740 61 11 20,760 810 hpa hpa,,11 20 4, 12 08,11,14 ( T2ln P,17 12 08 10 1998 12 11 12 (a. 11 20, b. 12 08 ;, 11 ( 11,, 03 06 14 11 2001 (20 25 N,, 105 120 E 16 4. 2 ( 3 %, 14 ( 12, 1 %
6 : 741, : (1 ;, 12 (25 35 N,103 120 E (2 03 06 14,, ( ISCCP1990 1998, 2001 30 5, : ISCCP NASA Langley Research Cen2, ter Atmospheric Sciences Data Center 1 Wetherald R T, Manabe S. Cloud feedback processes in a general circulation model. Mon Wea Rev, 1987, 125 (12 : 3172 3189 2,.., 1998, 9 (1 : 32 37 3,,.., 1999, 57 (5 : 549 560 4,.., 2001, 20 (3 : 252 257 5 Klein S A, Hartmann D L. The seasonal cycle of low stratiform clouds. J Climate, 1993, 6 : 1587 1606 6 Yu R C, Yu Y Q, Zhang M H. Comparing cloud radiative properties between the Eastern China and the Indian monsoon region. Adr Atmos Sci, 2001, 18 (6 : 1090 1102 7 Li J ui - Lin F, Kghler, Martin, et al. The impact of stratocumulus cloud radiative properties on surface heat fluxes simulated with a general circu2 lation model. Mon Wea Rev, 2002, 130 : 1433 1441 8 Rozendaal M A, Conway B L, Stenhen A. An observational study of diurnal variations of marine stratiform cloud. J Climate, 1995,8 (7 : 1795 1809 9 Bergman J W. A numerical investigation of cloud diurnal variations. J Climate, 1997, 10 (9 : 2330 2350 10 Hignett P. Observations of diurnal variation in a cloud - capped marine boundary layer. J Atmos Sci, 1991, 48 (12 : 1474 1482 11 Rogers D P, Yang Xiaohua, Peter M Norris, et al. Diurnal evolution of the cloud - topped marine boundary layer. Part I : Nocturnal stratocumu2 lus development. J Atmos Sci, 1995, 52 (16 : 2953 2966 12 Bergman J W, Murry L S. Diurnal variations of cloud cover and their relationship to climatological conditions. J Climate, 1996, 9 (11 : 2802 2820 13 Rossow W B, Schiffer R A. ISCCP cloud data products. Bull Amer Meteor Soc, 1991, 72 : 2 20
742 61 14 Doutriaux - Boucher M, Seze G. Significant changes between the ISCCP C and D cloud climatologies. Geophys Res Lett, 1998, 25 : 4193 4196 15 Lau Ngar2Cheung, Mark W C. Comparing satellite and surface observations of cloud patterns in synoptic - scale circulation systems. Mon Wea Rev, 1997, 125 (12 : 3172 3189 16 Rossow W B, Walker A W, Garder L C. Comparison of ISCCP and other cloud amounts. J Climate, 1993, 6 : 2394 2418 17.., 1995, 31 (3 : 151 152 18.. :, 1991. 298pp 19,,.., 1999, 19 (3 : 39 45 20 Duynkerke P G. The diurnal variation of a marine stratocumulus layer : A model sensitivity study. Mon Wea Rev, 1989, 117 (8 : 1710 1725 21 R B... :, 1991. 457pp THE FORMATION AND D IURNAL CHANGES OF STRATIFORM CLOUDS IN SOUTHERN CHINA Li Yunying ( L A S G, Institute of A t mospheric Physics, Chinese Academy of Sciences, Beijing 100029 ; Institute of Meteorology, PL A U niversity of Science and Techonology, N anjing 211101 Yu Rucong ( L A S G, Institute of A t mospheric Physics, Chinese Academy of Sciences, Beijing 100029 ; Institute of Heavy Rain, CMA, W uhan 430074 Xu Youping Zhang Xuehong ( L A S G, Institute of A t mospheric Physics, Chinese Academy of Sciences, Beijing 100029 Abstract Stratiform clouds have thicker optical depths, which affect the local climate seriously. Southern China (20-35 N,103-120 E is the unique region where stratiform cloud amount is very high in the mid and low latitude, but little attention has been focused on stratiform clouds in this region. Based on the monthly and hourly data f rom surface observations and radiosonde, t he circulation condition and diurnal changes of st ratiform clouds in sout hern China are illust rated and interpreted. The main conclusions are as follows : 1. The low st ratiform clouds mainly occur along t he sout heast coast of Chinese mainland, where prevailing cloud type is St ratocumulus. The diurnal change of St ratocumulus is related to diurnal change of t he height of boundary layer. The cloud fraction increases in the day and decreases in the night, its maximum occurs at 05 o clock and minimum occurs at 14 o clock. The diurnal change of St ratocumulus is also affected by t he diurnal change of t he difference be2 tween temperature and dew point (relative humidity. The relative humidity reaches maximum at 05 o clock and minimum at 14 o clock, which is coincide well with the variation of the Stratocumulus. 2. The medium stratiform clouds dominate eastern China and are the result of dynamic effect of the Tibetan Plateau. In cold seasons, the westerlies in the lower layer move around the plateau from the north and the south and converge in eastern China, especially in Sichuan, Hubei provinces and Chongqing city. These areas are also t he larger relative humidity regions in China in cold seasons. The abundance vapor and large scale ascending mo2 tion provide t he basic condition for t he formation of st ratiform clouds. How high can ascending motion reach, is affected by circulation in the air. The surface friction of the Tibetan Plateau makes the divergence in the middle
6 : 743 of the troposphere and convergences in the lower and higher troposphere. The inversion layer occurs between 500-600 hpa because temperature decreases with lower air ascending and increases with upper air descending. Cloud cannot penetrate the inversion layer and is suppressed in the mid - level. The mid2level st ratiform clouds have no distinct diurnal changes. If the formation and diurnal changes of the stratiform clouds in China can be considered in the general circu2 lation models, t he simulation effect s of East Asia climate might be improved. Key words : Southern China, Stratiform cloud, Mechanism, Diurnal change. :2003 12 3 : : ( : : : : : ( ; ; ;, 2004 ( : ; 1 6 ; 2004 5 2004 7,