Mean state and kinematic properties of mesoscale convective systems over West Africa

详细信息    查看全文

• 作者：Stephen B. Ogungbenro ; V. O. Ajayi ; D. O. Adefolalu
• 刊名：Theoretical and Applied Climatology
• 出版年：2016
• 出版时间：April 2016
• 年：2016
• 卷：124
• 期：1-2
• 页码：219-227
• 全文大小：679 KB
• 参考文献：Adefolalu DO (1983) Monsoon onset in West Africa application of satellite imagery. Arch Met Geoph Biokl Ser B 32:219–230CrossRef
  Arnaud Y, Desbois M, Maizi J (1992) Automatic tracking and characterization of African convective systems on Meteosat pictures. J Appl Meteorol 31:443–453CrossRef
  Burpee RW (1972) The origin and structure of easterly waves in the crown atmosphere of North Africa. J Atmos Sci 29:77–90CrossRef
  Chong M, Amayenc P, Scialom G, Testud J (1987) A tropical squall line observed during the COPT 81 experiment in West Africa. Part I: kinematic structure inferred from dual-doppler radar data. Mon Weather Rev 115:670–694CrossRef
  D’Amato N, Lebel T (1998) On the characteristics of the rainfall events in the Sahel with a view to the analysis of climate variability. Int J Climatol 18:955–974CrossRef
  Duvel JP (1990) Convection over tropical Africa and the Atlantic Ocean during northern summer. Part II: modulation by easterly waves. Mon Weather Rev 118:1855–1868CrossRef
  Fink AH, Reiner A (2003) Spatiotemporal variability of the relation between African Easterly Waves and West African Squall Lines in 1998 and 1999. J Geophys Res Atmos 108(D11). doi:10.​1029/​2002JD002816
  Goyens C, Lauwaet D, Schroder M, Demuzerea M, Van Lipziga NPM (2011) Tracking mesoscale convective systems in the Sahel: relation between cloud parameters and precipitation. Int J Climatol 32:1921–1934CrossRef
  Hodges KI, Thorncroft CD (1997) Distribution and statistics of African mesoscale convective weather systems based on the ISCCP METEOSAT imagery. Mon Weather Rev 125:2821–2837CrossRef
  Jobard I, Desbois M (1992) Remote sensing of rainfall over the tropical Africa using METEOSAT infrared imagery. Int J Remote Sens 13–14:2683–2700CrossRef
  Lauwaet D, van Lipzig NP, De Ridder K (2009) The effect of vegetation changes on precipitation and mesoscale convective systems in the Sahel. Clim Dyn 33(4):521–534CrossRef
  LeBarbe L, Lebel T, Tapsoba D (2002) Rainfall variability in West Africa during the years 1950–90. J Clim 15:187–202CrossRef
  Mathon V, Laurent H (2001) Life cycle of Sahelian mesoscale convective cloud systems. Q J R Meteorol Soc 127:377–406CrossRef
  Mathon V, Diedhiou A, Laurent H (2002) Relationship between easterly waves and mesoscale convective systems over the Sahel. Geophys Res Lett 29:1216. doi:10.​1029/​2001GL014371 CrossRef
  Omotosho JB (1983) Prediction of maximum gusts in West African line squalls. Niger Meteorol J 1:94–100
  Omotosho JB (1985) The separate contributions of line squalls, thunderstorms and monsoon to the total rainfall in Nigeria. Int J Climatol 5:543–552CrossRef
  Omotosho JB (1992) Long-range prediction of the onset and end of the rainy season in the West African Sahel. Int J Climatol 12:369–382CrossRef
  Omotosho JB, Abiodun BJ (2007) A numerical study of moisture build-up and precipitation in West Africa. Meteorol Appl 14:209–225CrossRef
  Orlandi E, Fierli F, Davolio S, Buzzi A, Drofa O (2010) A nudging scheme to assimilate satellite brightness temperature in a meteorological model: impact on representation of African mesoscale convective systems. Q J R Meteorol Soc 136(647):462–474
  Reed RJ, Norquist DC, Recker EE (1977) The structure and properties of African wave disturbances observed during Phase III of GATE. Mon Weather Rev 105:317–333CrossRef
  Schrage JM, Fink RH, Ermert V, Ahlonsou ED (2006) Three MCS cases occurring in different synoptic environments in the sub-Sahelian wet zone during the 2002 West African monsoon. J Atmos Sci 63:2369–2382CrossRef
  Sultan B, Janicot S (2000) Abrupt shift of the ITCZ over West Africa and intra-seasonal variability. Geophys Res Lett 27:3353–3356CrossRef
  Taylor CM, Harris P, Parker DJ (2010) Impact of soil moisture on the development of a Sahelian mesoscale convective system: a case-study from the AMMA Special Observing Period. Q J R Meteorol Soc 136:456–470. doi:10.​1002/​qj.​465 CrossRef
  Tomasini M, Lafore JP, Piriou C, Roca R, Ramage K, Laurent H, Morel C, Senesi S (2006) Atlas on a climatology of West African mesoscale convective systems. AMMA-EU report Du 2/1/3/a
  Yang GY, Slingo J (2001) The diurnal cycle in the tropics. Mon Weather Rev 129:784–801CrossRef
  
• 作者单位：Stephen B. Ogungbenro (1)
  V. O. Ajayi (1)
  D. O. Adefolalu (1)
  
  1. Department of Meteorology, Federal University of Technology, P.M.B. 704, Akure, Ondo State, Nigeria
  
• 刊物类别：Earth and Environmental Science
• 刊物主题：Earth sciences
  Meteorology and Climatology
  Atmospheric Protection, Air Quality Control and Air Pollution
  Climate Change
  Waste Water Technology, Water Pollution Control, Water Management and Aquatic Pollution
  
• 出版者：Springer Wien
• ISSN：1434-4483

文摘

A 17-year (1984 to 2000) dataset of brightness temperature (T _b) was employed to study the spatial and temporal scales of mesoscale convective systems (MCS) over West Africa. The kinematic properties of MCS were tested using wind products. A threshold brightness temperature (T _b) of ≤213 K and spatial coverage specifications of more than 5000 km2 were used as two set criteria for initiating MCS tracking. MCS occurrences vary in seasons and locations over West Africa, and their activities vary with different weather zones. They can appear at any time of the day, but this study revealed a significant preference for early morning hours and night hours over continental West Africa. The well-organized systems occur between July and September in the Sahel, and between May and September in the Savanna band. MCS activities in the Gulf of Guinea peak between March and April, while the Savanna and Sahel zones peak between June and August. The produced annual atlas gives a spatial account of areas of MCS dominance in West Africa. The presence of African Easterly Jet (AEJ) and Tropical Easterly Jet (TEJ), and deep monsoon depth all characterize an environment where MCS thrive. Kinematic study of a typical MCS reveals that the monsoon depth increases at the passage of MCS, with cyclonic vorticity dominating from the surface to 300 hpa while anticyclonic vorticity was observed around 200 hpa, and this confirms the importance of low level convergence and upper level divergence as the major requirements for storm mobilization and maintenance.