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<p>Please join us TODAY at 3:30 on zoom for this week's EOAS
Colloquium speaker:</p>
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<p><font size="+2">Dr. Sharon Nicholson of EOAS at FSU</font></p>
<p><font size="+2"><font size="+1"><br>
Time: Nov 13, 2020 03:30 PM Eastern Time (US and Canada)<br>
<br>
Join Zoom Meeting<br>
<a class="moz-txt-link-freetext" href="https://fsu.zoom.us/j/93321272960" moz-do-not-send="true">https://fsu.zoom.us/j/93321272960</a><br>
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Meeting ID: 933 2127 2960</font></font></p>
<p> </p>
<p class="MsoNormal" style="text-align:center" align="center"><b style="mso-bidi-font-weight: normal">RAINFALL ENHANCEMENT OVER
THE EAST AFRICAN LAKES</b></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal" style="text-align:justify"><span style="font-family:"Times New Roman",serif"><span style="mso-tab-count:1"> </span>The numerous
lakes of the East African Rift Valley are a major resource for
the countries of the region.<span style="mso-spacerun:yes"> </span>The
largest, Lake Victoria, sustains the livelihood of some 30
million people and its level determines the flow the Nile, the
lifeblood of Egypt, Sudan and South Sudan.<span style="mso-spacerun:yes"> </span>Rainfall over the lake
occurs mainly at night and in the early morning and is known
to be enhanced by some 50% compared to rainfall in its
catchment.<span style="mso-spacerun:yes"> </span>The
enhancement is a combined result of lake/land breezes and
mountain/valley winds. <span style="mso-spacerun:yes"> </span>The
nocturnal rainfall is coupled with intense thunderstorms,
which result in some 5,000 deaths annually.</span></p>
<p class="MsoNormal" style="text-align:justify"><span style="font-family:"Times New Roman",serif"><span style="mso-tab-count:1"> </span>This talk
presents an in-depth view of the lake-effect rains over Lake
Victoria and a brief overview of the enhancement by other East
African lakes.<span style="mso-spacerun:yes"> </span>Both
the seasonal and diurnal cycles over Lake Victoria are
analyzed in the context of meteorological parameters that
might control rainfall.<span style="mso-spacerun:yes"> </span>These
include winds and wind divergence, vertical motion, convective
available potential energy (C.A.P.E.) and Mesoscale Convective
Systems (MCSs).<span style="mso-spacerun:yes"> </span>The
meteorological analysis is based on ERA5.<span style="mso-spacerun:yes"> </span>Several satellite
rainfall products were evaluated and TRMM 3B43 and 3B42 were
determined to perform best in this region and utilized for the
analyses.<span style="mso-no-proof:yes"> </span></span></p>
<p class="MsoNormal" style="text-align:justify"><span style="font-family:"Times New Roman",serif"><span style="mso-tab-count:1"> </span>Several new
conclusions about the lake-effect rains have emerged.<span style="mso-spacerun:yes"> </span>For one, there is
substantial enhancement of rainfall over Lake Victoria in all
months, even during the two dry seasons.<span style="mso-spacerun:yes"> </span>Rainfall enhancement is
also apparent over numerous other lakes in the region, even
small ones.<span style="mso-spacerun:yes"> </span>Some of
the enhancement occurs during the dry season when the
catchment is rainless.<span style="mso-spacerun:yes"> </span>The
magnitude of the enhancement is driven by large-scale
meteorological factors as opposed to local conditions over the
lakes.<span style="mso-spacerun:yes"> </span>For example,
the patterns of low-level divergence over the lake are similar
in dry season and wet season months. Most of the rainfall over
Lake Victoria is from MCSs that develop in situ at night.</span></p>
<p class="MsoNormal" style="text-align:justify"><span style="font-family:"Times New Roman",serif"><span style="mso-tab-count:1"> </span>A surprising
conclusion that emerged is that the relatively new IMERG data
of the Global Precipitation Measurement (GPM) mission vastly
overestimates rainfall over inland water bodies, such as Lakes
Victoria, Malawi, and Tanganyika.<span style="mso-spacerun:yes"> </span>This appears to be
related to the passive microwave sources incorporated into the
final product.</span></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="mso-spacerun:yes">
</span><span style="mso-no-proof:yes"><img src="file:////Users/abacotaylor/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image002.png" alt="Victoria_satellite.jpg" moz-do-not-send="true" width="282" height="211"></span><br style="mso-special-character:line-break">
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