Sharon E. Nicholson

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[1] We use the Total Ozone Mapping Spectrometer (TOMS) sensor on the Nimbus 7 satellite to map the global distribution of major atmospheric dust sources with the goal of identifying common environmental characteristics. The largest and most persistent sources are located in the Northern Hemisphere, mainly in a broad “dust belt” that extends from the west(More)
This paper begins with an overview of the African rainfall regime, noting in particular the contrast among various regions Ž . of the continent, followed by a description of the nature of climatic i.e., rainfall variability over Africa on time scales of decades and centuries. The decadal scale is examined using modern data covering the twentieth century.(More)
This paper presents new calculations of Lake Victoria's water balance. Evaporation is estimated using both the Penman formula and the energy balance approach, and sensitivity studies are performed to determine the influence of input data on the estimates. Rainfall over the lake is estimated from catchment rainfall using a relationship between the two that(More)
A water balance model of Lake Victoria that can be used to assess rainfall from lake level, is derived. The model utilizes satellite estimates of rainfall directly over the lake. The model, initially derived and calibrated for the period 1956-1978, is reformulated here in such a way that all water balance terms except evaporation can be calculated from a(More)
The diurnal cycle of convective activity and cloudiness over Lake Victoria, is examined using infrared satellite data. The results indicate that geographically distinct patterns of convection occur. Maximum convective activity occurs over the northwestern quadrant of the lake and tends to occur during the night time. There is a similar pattern in the(More)
During the last deglaciation, wetter conditions developed abruptly ~14,700 years ago in southeastern equatorial and northern Africa and continued into the Holocene. Explaining the abrupt onset and hemispheric coherence of this early African Humid Period is challenging due to opposing seasonal insolation patterns. In this work, we use a transient simulation(More)
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