An integrated satellite precipitation estimation dataset, namely, the Climate Prediction Center morphing method (CMORPH), was used to analyze precipitation regimes across Equatorial Africa between 3<span style=&quo...An integrated satellite precipitation estimation dataset, namely, the Climate Prediction Center morphing method (CMORPH), was used to analyze precipitation regimes across Equatorial Africa between 3<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">°</span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">S - 1</span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"=""><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">°</span></span></span><span style="font-family:Verdana;">N and 24</span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"=""><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">°</span></span></span><span style="font-family:Verdana;">E - 42</span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"=""><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">°</span></span></span><span style="font-family:Verdana;">E from 2000 to 2014. This region includes the Rift Valley, part of the Congo Forest, and the Lake Victoria (LV) basin, the second largest lake in the area of the world. Hovm<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"=""><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">ö</span></span>ller diagrams were obtained for all organized convective systems to estimate their spans, duration, and phase speeds. The analysis included 33,189 episodes of westward propagating convective systems. Within the study area, lake and land breezes tend to trigger convection and precipitation over LV as well as mountain-valley circulation trigger thunderstorms over the mountains east of LV and western Rift Valley. The statistics of convective systems streaks on longitude-time diagrams were obtained for yearly frequencies of starting and ending longitudes and times among other morphologic variables. Results indicate organized precipitation episodes tend to move westward across Rift valley and Congo forest with an average phase speed of 10.3 <span style="white-space:normal;font-family:Verdana;">m<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>s</span><sup style="white-space:normal;"><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;background-color:#f7f7f7;"=""><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span></span><span style="font-family:Verdana;">1</span></sup></span><sup><span style="font-family:Verdana;"></span></sup><span style="font-family:Verdana;">. More than 50% of them are triggered over LV and propagate more than 600 km at an average phase speed of 12.1 m<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>s</span><sup><span style="font-family:Verdana;"><span style="white-space:normal;color:#4F4F4F;font-family:-apple-system, " font-size:16px;background-color:#f7f7f7;"=""><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span><span style="font-family:Verdana;white-space:normal;"></span></span><span style="font-family:Verdana;">1</span></sup><span style="font-family:Verdana;">. These convective systems tend to produce high rainfall rates hundreds of kilometers away into the Congo Forest. Half of all episodes of organized convection analyzed have phase speeds between 8 <span style="white-space:normal;font-family:Verdana;">m<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>s</span><sup style="white-space:normal;"><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;background-color:#f7f7f7;"=""><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span></span><span style="font-family:Verdana;">1</span></sup></span><sup><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span></sup><span style="font-family:Verdana;"> and 16 <span style="white-space:normal;font-family:Verdana;">m<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>s</span><sup style="white-space:normal;"><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;background-color:#f7f7f7;"=""><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span></span><span style="font-family:Verdana;">1</span></sup></span><sup><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span></sup><span style="font-family:Verdana;">, lasting 8 hr to 16 hr. Most precipitating systems start east of LV and west of Rift Valley in the afternoon to early morning and propagates less than 400 km. Finally, hourly precipitation accumulation and lightning density analysis indicate three preferable regions for convective initiation: 1) The mountain range east of LV;2) Midwest of LV, and;3) The Congo Forest mountain range.</span></span></span></span>展开更多
文摘An integrated satellite precipitation estimation dataset, namely, the Climate Prediction Center morphing method (CMORPH), was used to analyze precipitation regimes across Equatorial Africa between 3<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">°</span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">S - 1</span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"=""><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">°</span></span></span><span style="font-family:Verdana;">N and 24</span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"=""><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">°</span></span></span><span style="font-family:Verdana;">E - 42</span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"=""><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">°</span></span></span><span style="font-family:Verdana;">E from 2000 to 2014. This region includes the Rift Valley, part of the Congo Forest, and the Lake Victoria (LV) basin, the second largest lake in the area of the world. Hovm<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"=""><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">ö</span></span>ller diagrams were obtained for all organized convective systems to estimate their spans, duration, and phase speeds. The analysis included 33,189 episodes of westward propagating convective systems. Within the study area, lake and land breezes tend to trigger convection and precipitation over LV as well as mountain-valley circulation trigger thunderstorms over the mountains east of LV and western Rift Valley. The statistics of convective systems streaks on longitude-time diagrams were obtained for yearly frequencies of starting and ending longitudes and times among other morphologic variables. Results indicate organized precipitation episodes tend to move westward across Rift valley and Congo forest with an average phase speed of 10.3 <span style="white-space:normal;font-family:Verdana;">m<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>s</span><sup style="white-space:normal;"><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;background-color:#f7f7f7;"=""><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span></span><span style="font-family:Verdana;">1</span></sup></span><sup><span style="font-family:Verdana;"></span></sup><span style="font-family:Verdana;">. More than 50% of them are triggered over LV and propagate more than 600 km at an average phase speed of 12.1 m<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>s</span><sup><span style="font-family:Verdana;"><span style="white-space:normal;color:#4F4F4F;font-family:-apple-system, " font-size:16px;background-color:#f7f7f7;"=""><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span><span style="font-family:Verdana;white-space:normal;"></span></span><span style="font-family:Verdana;">1</span></sup><span style="font-family:Verdana;">. These convective systems tend to produce high rainfall rates hundreds of kilometers away into the Congo Forest. Half of all episodes of organized convection analyzed have phase speeds between 8 <span style="white-space:normal;font-family:Verdana;">m<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>s</span><sup style="white-space:normal;"><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;background-color:#f7f7f7;"=""><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span></span><span style="font-family:Verdana;">1</span></sup></span><sup><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span></sup><span style="font-family:Verdana;"> and 16 <span style="white-space:normal;font-family:Verdana;">m<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>s</span><sup style="white-space:normal;"><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;background-color:#f7f7f7;"=""><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span></span><span style="font-family:Verdana;">1</span></sup></span><sup><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span></sup><span style="font-family:Verdana;">, lasting 8 hr to 16 hr. Most precipitating systems start east of LV and west of Rift Valley in the afternoon to early morning and propagates less than 400 km. Finally, hourly precipitation accumulation and lightning density analysis indicate three preferable regions for convective initiation: 1) The mountain range east of LV;2) Midwest of LV, and;3) The Congo Forest mountain range.</span></span></span></span>