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<p>Please join us Friday at 3:30 on zoom for this week's EOAS
Colloquium speaker:</p>
<p><br>
</p>
<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">https://fsu.zoom.us/j/93321272960</a><br>
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Meeting ID: 933 2127 2960</font></font></p>
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<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" width="282" height="211"></span><br style="mso-special-character:line-break">
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