On convection and static stability during the AMMA SOP3 campaign

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• 作者：G. B. Embolo Embolo ; André Lenouo ; Armand T. Nzeukou…
• 刊名：Theoretical and Applied Climatology
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：127
• 期：1-2
• 页码：197-211
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Atmospheric Sciences; Climatology; Atmospheric Protection/Air Quality Control/Air Pollution; Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution;
• 出版者：Springer Vienna
• ISSN：1434-4483
• 卷排序：127

文摘

Using radiosonde dataset from 15 weather stations over West Africa, this paper investigates the contribution of the couple convection-static stability in the framework of the African monsoon multidisciplinary analyses Special Observing Period 3 (AMMA SOP3) experiment. Within this 31-day period, the boundary layer-winds depictions have revealed the West African monsoon’s (WAM) depth (around 1500 m) is not thick enough to trigger intense convection. However, the midlevel winds distribution (700–600 hPa) has shown the average African easterly jet core strength (15 m s−1) is sufficient to allow the development of African easterly waves (AEWs) necessary for squall lines activities. In return, in the upper levels (200–100 hPa), the speed (below 18 m s−1) of the mean Tropical easterly jet (TEJ) core cannot favor midlevel updrafts. The free tropospheric humidity (FTH) depiction has indicated convective events are more likely in the western Sahel where the highest FTH (FTH >50 %) are recorded. The static stability analysis has testified that convection is stronger in the semi-arid (SA) area during night time (0000 GMT). However, convective activities are inhibited in the wet equatorial (WE) region due to mean low-level stability. We used METEOSAT Second Generation (MSG) infrared (IR10.8) imagery of the 8th September 2006 to confirm that result. Furthermore, a maximum midtropospheric static stability combined with maximum relative humidity (RH) was found on the fringe of the Saharan air layer’s (SAL) top (altitude around 5.3 km) in the WE region.