Cloud properties during active and break spells of the West African summer...

Efon, E., A. Lenouo, D. Monkam, and D. Manatsa (2016), Cloud properties during active and break spells of the West African summer monsoon from CloudSat–CALIPSO measurements, Journal of Atmospheric and Solar-Terrestrial Physics, 145, 1-11.
Abstract: 

High resolution of daily rainfall dataset from the Tropical Rainfall Measuring Mission (TRMM) was used to identify active and break cloud formation periods. The clouds were characterized based on CloudSatCALIPSO satellite images over West Africa during the summer monsoon during the period 2006–2010. The active and break periods are defined as the periods during the peak monsoon months of June to August when the normalized anomaly of rainfall over the monsoon core zone is greater than 0.9 or less than -0.9 respectively, provided the criteria is satisfied for at least three consecutive days. It is found that about 90% of the break period and 66.7% of the active spells lasted 3–4 days. Active spells lasting duration of about a week were observed while no break spell had such a long span. Cloud macrophysical (cloud base height (CBH), cloud top height (CTH) and cloud geometric depth (ΔH), microphysical (cloud liquid water content, (LWC), liquid number concentration (LNC), liquid effective radius, ice water content (IWC), ice number concentration (INC) and ice effective radius) and radiative (heating rate properties) over South Central West Africa (5–15°N; 15°W–10°E) during the active and break spells were also analyzed. High-level clouds are more predominant during the break periods compared to the active periods. Active spells have lower INC compared to the break spells. Liquid water clouds are observed to have more radiative forcing during the active than break periods while ice phase clouds bring more cooling effect during the break spells compared to the active spells.

Mission: 
CloudSat